Arthritis Patients (arthritis + patient)

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Arthritis Patients

  • rheumatoid arthritis patient


  • Selected Abstracts


    Prescription rates of protective co-therapy for NSAID users at high GI risk and results of attempts to improve adherence to guidelines

    ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2009
    L. LAINE
    Summary Background, Protective co-therapy is recommended in NSAID users with GI risk factors, but adherence is poor. Aim, To assess the proportion of NSAID users receiving co-therapy and strategies to improve adherence. Methods, Arthritis patients ,50 years of age received etoricoxib or diclofenac in a double-blind randomized trial. Reminders that high-risk patients (age , 65; previous ulcer/haemorrhage; corticosteroid, anticoagulant, aspirin use) should receive co-therapy were given at study initiation. Free PPI was provided. An intervention midway through the study included a written reminder and required written response regarding co-therapy. Results, 16 244/23 504 (69%) patients had GI risk factors. Pre-intervention, co-therapy was most common with previous ulcer/haemorrhage [706/1107 (64%)] and 3,4 risk factors [331/519 (64%)]. In the 10 026 patients enrolled pre-intervention and remaining in the study ,6 months after, co-therapy in high-risk patients increased from 2958/6843 (43%) to 4177/6843 (61%) (difference = 18%; 95% CI 16%,19%). The increase was greater outside the US (22%; 19%,24%) than in the US (15%; 13%,17%). Conclusions, Less than 50% of NSAID users with GI risk factors are given protective co-therapy , even if prescribers are given reminders and cost is not an issue. Direct communication requiring written response significantly increased adherence to guidelines, but achieving higher levels of adherence will require additional strategies. [source]


    Miliary tuberculosis and necrotizing tuberculous fasciitis , An unusual coexistence in a rheumatoid arthritis patient

    INTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 2 2010
    Hyun-Hee KWON
    Abstract We report a case of a 65-year-old Korean female patient with rheumatoid arthritis, who presented with extensive necrotizing fasciitis of the gluteus muscles, as an unusual initial manifestation of miliary tuberculosis. The patient had been previously treated with conventional disease-modifying antirheumatic drugs and low-dose steroids for 7 years. However, she recently developed fever, warmth and painful swelling in her right buttock. Magnetic resonance imaging indicated necrotizing fasciitis of the gluteus muscles and a fasciectomy specimen revealed a Mycobacterium tuberculosis infection. Two weeks after a fasciectomy, miliary tuberculosis of the lung was diagnosed by high resolution chest computed tomography. Soft tissue infection due to M. tuberculosis should be included as a differential diagnosis in the immunocompromised host. Clinicians should be alert to the possibility of miliary tuberculosis even in the absence of respiratory symptoms and normal chest radiograph. [source]


    Successful treatment of a leg ulcer occurring in a rheumatoid arthritis patient under leflunomide therapy

    JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 2 2005
    J Knab
    ABSTRACT Objective, We report the case of a leg ulcer in a rheumatoid arthritis (RA) patient under treatment with leflunomide, discuss the influence of the drug on the aetiopathogenesis of the ulcer and describe its successful treatment. Case summary, A 68-year-old woman with a 12-year history of RA developed a leg ulcer after 4 months of leflunomide treatment. Other ulcerogenic factors were ruled out. There were some clinical hints for rheumatoid vasculitis. The ulcer was resistant to ambulant conservative phase adapted wound bed preparation and a split skin transplantation failed. After omission of leflunomide and washout procedure with cholestyramine a second split skin transplantation resulted in complete healing. Discussion, Leflunomide inhibits the division of activated T cells and thus inhibits among others the production of proinflammatory cytokines and the adhesion of cells to the endothelium. These mechanisms may partly explain the possible influence of leflunomide on the perpetuation of the ulcer. Until now, occurrence of vasculitis and leg ulcers has been described in one case each for the novel immunomodulator leflunomide. No successful treatment of a leg ulcer under leflunomide has been described yet. Omission of leflunomide and a washout treatment in our case led to a complete healing. This may indicate a critical role of leflunomide in the maintenance of this slow healing ulcer. Conclusions, An association between leflunomide intake, occurrence of leg ulcers in RA patients and delayed wound healing should be considered. [source]


    Clonally expanded CD4+CD28null T,cells in rheumatoid arthritis use distinct combinations of T cell receptor BV and BJ elements

    EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2003
    Ulf Wagner
    Abstract Clonally expanded, autoreactive CD4+CD28null cells can be found in the peripheral blood of patients with rheumatoid arthritis and have been shown to be associated with severeextra-articular disease manifestations. We investigated the size of the CD4+CD28null compartment and the TCR , chain repertoire of expanded CD4+ clonotypes in 94 rheumatoid arthritis patients by complementarity-determining region 3 (CDR3) length analysis (spectratyping) in the BV6 and BV14 TCR families, with primers specific for three arbitrarily chosen , chain joining elements (BJ1S2, BJ2S3 and BJ2S7). The spectratyping results showed a strong correlation of the size of the CD4+CD28null compartment with the detected number of BV14 clonotypes, whereas no association with BV6 oligoclonality was found. Only clones using the BV14,BJ1S2 and BV14,BJ2S3 combinations contributed to this correlation, however, whereas BV14,BJ2S7 clones did not. This preferential correlation implies a role for the TCR , chain in stimulating clonal outgrowth and argues against the previously suggested superantigenic stimulation of in-vivo -expanded clones. Instead, since no evidence for shared antigen specificity could be detected, clonal expansion of T cells in rheumatoid arthritis might be influenced by the BJ elements because of changes in the flexibility of the protein backbone of the ,-chain. [source]


    Regulation of human neutrophil-mediated cartilage proteoglycan degradation by phosphatidylinositol-3-kinase

    IMMUNOLOGY, Issue 1 2001
    C. S. T. Hii
    Summary The ability of neutrophils to degrade cartilage proteoglycan suggests that the neutrophils that accumulate in the joints of rheumatoid arthritis patients are mediators of tissue damage. The regulatory mechanisms which are relevant to the proteoglycan-degrading activity of neutrophils are poorly understood. Since phosphatidylinositol 3-kinase (PI3-K), protein kinase C (PKC), the extracellular signal-regulated protein kinase (ERK)1/ERK2 and cyclic adenosine monophosphate (cAMP) have been reported to regulate neutrophil respiratory burst and/or degranulation, a role for these signalling molecules in regulating proteoglycan degradation was investigated. Preincubation of human neutrophils with GF109203X (an inhibitor of PKC), PD98059 (an inhibitor of MEK, the upstream regulator of ERK1/ERK2) or with forskolin or dibutyryl cAMP, failed to suppress proteoglycan degradation of opsonized bovine cartilage. In contrast, preincubation of neutrophils with wortmannin or LY294002, specific inhibitors of PI3-K, inhibited proteoglycan degradation. Incubation of neutrophils with cartilage resulted in the activation of PI3-K in neutrophils, consistent with a role for PI3-K in proteoglycan degradation. Activation of PI3-K and proteoglycan degradation was enhanced by tumour necrosis factor-,. Degradation caused by neutrophils from the synovial fluid of rheumatoid arthritis patients was also inhibited by wortmannin. These data demonstrate that the proteoglycan degradative activity of neutrophils required PI3-K but not PKC or the ERK1/ERK2/ERK5 cascades and was insensitive to increases in intracellular cAMP concentrations. [source]


    Interleukin-10 gene promoter polymorphism in Polish rheumatoid arthritis patients

    INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 4 2010
    A. Paradowska-Gorycka
    Summary Interleukin (IL)-10 is an important multifunctional cytokine with both anti-inflammatory and immunoregulatory effects in rheumatoid arthritis (RA). In the present study, we evaluated the frequency and potential impact of IL-10 promoter polymorphisms on susceptibility to and severity of RA in Polish in , patients with a high disease activity (mean DAS 28 C-reactive protein 5.25). DNA was obtained from 244 RA patients and 106 healthy controls. The ,592C/A and ,1082G/A IL-10 gene polymorphisms were amplified by polymerase chain reaction with restriction endonuclease mapping. The frequency of the IL-10-592CA, -592AA genotypes (respectively: 30% vs 5% and 7% vs 0%) and allele ,592A (37% vs 5%) were significantly higher in RA patients as compared with a control group. We did not find any association of the IL-10-592C/A genotype distribution with disease parameters, except for an increased ESR (erythrocyte sedimentation rate) in patients with the ,592CC genotype as compared with those with ,592CA or ,592AA genotypes (P = 0.01). The frequency of the IL-10-1082GG genotype was lower (P = 0.0001), and that of the IL-10-1082GA genotype was higher (P = 0.009) in RA patients comparing with the control group. In RA patients with ,1082GA or ,1082AA genotypes the time duration of the disease (P = 0.03), Health Assessment Questionnaire (HAQ) Score (P = 0.04) and PLT count (P = 0.001) were significantly increased as compared with subjects with ,1082GG genotype. Presented findings indicate that IL-10-592C/A and IL-10-1082G/A polymorphisms may be considered genetic risk factors for RA susceptibility and severity. [source]


    Variation in the matrix metalloproteinase-3, -7, -12 and -13 genes is associated with functional status in rheumatoid arthritis

    INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 2 2007
    S. Ye
    As matrix metalloproteinases (MMPs) play an important role in rheumatoid arthritis, we investigated whether variation in MMP genes was associated with functional disability in rheumatoid arthritis patients. A cohort of patients with seropositive rheumatoid arthritis were recruited and genotyped for the MMP1-1607 1G > 2G, MMP3-1612 5A > 6A, MMP7-153C > T, MMP7-181G > A, MMP12-82A > G and MMP13-77A > G polymorphisms. Genotypes were then analysed in relation to functional disability assessed by Steinbrocker index and Health Assessment Questionnaire (HAQ) score. We detected an association between the MMP13-77 A > G polymorphism and Steinbrocker index, with patients of the A/A genotype having higher score than patients of the A/G or G/G genotype (P = 0.005), and the association remained significant after adjusting for age, sex, erythrocyte sedimentation rate, presence of erosive disease, Ritchie score, prednisolone therapy and years of diagnosis (P = 0.003). We also observed a relationship of Steinbrocker index with the MMP3-1612 5A > 6A, MMP7-181 A > G and MMP12-82A > G polymorphisms (P = 0.082, P = 0.037 and P = 0.045). No association was detected between the MMP1-1607 1G > 2G and MMP7-153C > T polymorphisms and either Steinbrocker index or HAQ score. These results suggest that MMP3, MMP7, MMP12 and MMP13 genotypes may play a role in determining functional status of rheumatoid arthritis. [source]


    Does prolonged systemic glucocorticoid use increase risk of tophus formation among gouty arthritis patients?

    INTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 3 2009
    Anne-Annette P. RASO
    Abstract Aim:, To determine the relationship of steroid use with tophus formation and other comorbid conditions among male gout patients. Methods:, Review of medical records of Filipino gout patients under the care of rheumatologists was conducted. Univariate analysis (chi-square, Student's t -test) and multiple logistic regression analysis were performed to establish the risk for tophus formation among glucocorticoid users. Bivariate analysis was separately done to determine the confounding effect of steroid use in the association of comorbidities and tophi formation. Results:, There were 295 Filipino men with a mean age of 56 years and a mean duration of 12 years of gouty arthritis who were included in the study. Multivariate analysis showed a five times higher likelihood (OR 4.81 95% CI 1.92,12.04, P < 0.001) for tophus formation among prolonged steroid users. Confounders identified were disease duration of gout (, 10 years), presence of chronic kidney disease (CKD) and elevated serum creatinine level (SCr). Bivariate analysis of comorbidities showed that steroid use introduced a considerable bias in the relationship of hypertension, elevated SCr, CKD and dyslipidemia. Conclusion:, Patients with equivalent prednisone intake of at least 15 mg/week for , 3 months is associated with tophi formation. In the presence of hypertension, renal impairment, and elevated serum creatinine level, use of steroids confounds the individual risk that each factor carries. [source]


    Clinical experience with tumor necrosis factor blockers in Korean rheumatoid arthritis patients

    INTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 2 2006
    Jin-Wuk HUR
    Abstract Tumor necrosis factor (TNF) blockers have become an important treatment in rheumatoid arthritis (RA) with its proven effectiveness. But it is not universally effective in all patients and it comes with a relatively high economic burden. We should use them effectively. Advances in pharmacoeconomics and pharmacogenetics may be able to help us reach this goal. This article will review our clinical experience of biological agents to treat RA at Hanyang University in Korea, with emphasis on the current therapies targeting TNF and the rational use of theses agents in RA. [source]


    CXCL12 chemokine up-regulates bone resorption and MMP-9 release by human osteoclasts: CXCL12 levels are increased in synovial and bone tissue of rheumatoid arthritis patients

    JOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2004
    Francesco Grassi
    Chemokines are involved in a number of inflammatory pathologies and some of them show a pivotal role in the modulation of osteoclast development. Therefore, we evaluated the role of CXCL12 chemokine on osteoclast differentiation and function and we analyzed its expression on synovial and bone tissue biopsies from rheumatoid arthritis (RA) patients. Osteoclasts were obtained by 7 days in vitro differentiation with RANKL and M-CSF of CD11b positive cells in the presence or absence of CXCL12. The total number of osteoclast was analyzed by Tartrate-resistant acid phosphatase (TRAP)-staining and bone-resorbing activity was assessed by pit assay. MMP-9 and TIMP-1 release was evaluated by ELISA assay. CXCL12 expression on biopsies from RA patients was analyzed by immunohistochemistry. Osteoclasts obtained in the presence of CXCL12 at 10 nM concentration displayed a highly significant increase in bone-resorbing activity as measured by pit resorption assay, while the total number of mature osteoclasts was not affected. The increased resorption is associated with overexpression of MMP-9. Immunostaining for CXCL12 on synovial and bone tissue biopsies from both rheumatoid arthritis (RA) and osteoarthritis (OA) samples revealed a strong increase in the expression levels under inflammatory conditions. CXCL12 chemokine showed a clear activating role on mature osteoclast by inducing bone-resorbing activity and specific MMP-9 enzymatic release. Moreover, since bone and synovial biopsies from RA patients showed an elevated CXCL12 expression, these findings may provide useful tools for achieving a full elucidation of the complex network that regulates osteoclast function in course of inflammatory diseases. J. Cell. Physiol. 199: 244,251, 2004© 2003 Wiley-Liss, Inc. [source]


    Self-evaluation and peer review , an example of action research in promoting self-determination of patients with rheumatoid arthritis

    JOURNAL OF CLINICAL NURSING, Issue 3a 2007
    LicNSc, Päivi Löfman RN
    Aims and objectives., The aim of this paper was to describe the areas that have been performed well and the areas in need of further development of rheumatoid arthritis patients. Background., Nurses' self-evaluation and peer review are important methods for ascertaining the changes and success in the development of nursing practice. To date, there has been minimal research regarding the use of those evaluation methods in nursing practice. Design., The findings of self-evaluation and peer review of nurses are described in a participatory action research study aimed at promotion of self-determination for patients with rheumatoid arthritis. Methods., In self-evaluation, the collection of data was accomplished using a self-evaluation instrument with the permanent nursing staff (n = 18), then analysed through quantitative methods. For peer review, the data were gathered through focus groups (n = 21) using a tool similar to the one used for self-evaluation. The participants included many of the same nurses as in self-evaluation. The data were analysed using qualitative content analysis. Results., Well-performed areas in nursing of rheumatoid arthritis patients were found to be promoting patient participation, supporting self-determination, performing patient-centred nursing and raising patient self-respect. The areas in need of development were connected to the nursing staff themselves: increasing collaboration of nursing staff, decreasing authoritarianism in nursing care and developing nursing practice with colleagues. Conclusions., Self-evaluation and peer review are complementary and support one another, especially since nurses were found to be more critical in their self-evaluations than in peer review. Relevance to clinical practice., Both evaluation tools proved to be useful methods in the evaluation phase of the action research process as a means of professional development. Also assisting in the development of clinical nursing practice. [source]


    Detection of periodontal bacterial DNA in serum and synovial fluid in refractory rheumatoid arthritis patients

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2009
    Rita E. Martinez-Martinez
    Abstract Aim: To identify periodontal bacterial DNA (PBDNA) by PCR in subgingival dental plaque (SDP), serum and synovial fluid (SF) of rheumatoid arthritis (RA) with periodontal disease (PD) patients and to explore the possible PBDNA transport pathways from mouth to joints. Methods: This cross-sectional prolective study involved 19 subjects with RA and PD. Informed consent, health and dental questionnaires were obtained. SDP, SF and serum samples were obtained, and leucocytes were isolated from blood. DNA was extracted and PCR assays to detect main PD species were carried out. Cultures on agar plates and broth, from each sample, were performed. Results: Hundred percentage of patients showed PBDNA in SDP and SF and 83.5% in serum. Prevotella intermedia (89.4% and 73.6%) and Porphyromonas gingivalis (57.8% and 42.1%) were the species most frequently detected in SDP and SF, respectively. In SDP, 4.05 different bacterial species were found followed by 1.19 in serum and 2.26 in SF. Culture onto agar plates and broth did not show any bacterial growth, leucocytes were not positive to PBDNA by PCR. Conclusion: This study suggests that PBDNA could have a role on the RA aetiology. The possible pathway of transport of PBDNA from mouth to joints could be via the free form of DNA. [source]


    Evaluation of t-PA, PAI-2, IL-1, and PGE2 in gingival crevicular fluid of rheumatoid arthritis patients with periodontal disease

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 9 2006

    Abstract Aims: This study was undertaken to compare periodontal conditions, gingival crevicular fluid (GCF) levels of tissue-type plasminogen activator (t-PA), its inhibitor plasminogen activator inhibitor-2 (PAI-2), interleukin-1, (IL-1,), prostaglandin E2 (PGE2) in rheumatoid arthritis (RA) patients and control groups. Methods: Twenty-three RA patients, 17 systemically healthy patients with periodontal disease (PD), and 17 systemically and periodontally healthy subjects were recruited. GCF samples were obtained from two single-rooted teeth. Full-mouth clinical periodontal measurements were recorded at six sites/tooth. GCF samples were analysed using relevant ELISA kits. Data were tested statistically by appropriate tests. Results: Total amounts of t-PA, PAI-2 and PGE2 in GCF samples of the healthy control group were significantly lower than the other groups (p<0.05). The RA group exhibited a higher total amount of t-PA in GCF samples than the PD group (p<0.05). PAI-2, IL-1, and PGE2 total amounts were similar in RA and PD groups (p>0.05). Conclusion: The coexistence of RA and periodontitis does not seem to affect clinical periodontal findings or systemic markers of RA. Similar inflammatory mediator levels in RA and PD groups, despite the long-term usage of corticosteroids, non-steroidal anti-inflammatory drugs, suggest that RA patients may have a propensity to overproduce these inflammatory mediators. [source]


    Prevalence of risk factors for statin-induced myopathy in rheumatoid arthritis patients

    MUSCULOSKELETAL CARE, Issue 1 2010
    Tracey E. Toms MBChB MRCP
    Abstract Objectives:,Statins are widely prescribed in patients with rheumatoid arthritis (RA). Although statins offer overwhelming cardiovascular benefits, their use can be associated with the development of a statin-induced myopathy. Several factors increase the risk of developing statin-induced myopathy, including the single nucleotide polymorphism (SNP) rs4149056, located within the gene encoding solute carrier organic anion transporter (SLCO1B1). We aimed to identify the frequency of risk factors for statin-induced myopathy and establish whether the rs4149056 genotype is more prevalent in RA. Methods:,A total of 396 RA patients and 438 non-RA controls were studied. DNA samples were obtained from all patients. The SNP rs4149056 was identified using real-time polymerase chain reaction and melting curve analysis. Genotypic and allelic frequencies were calculated using the chi-squared test. Results:,Almost 80% of RA patients had one or more risk factor (range 1,5) for the development of statin-induced myopathy. Of the 74 RA patients treated with statins, 90% had one or more (range 1,4) risk factors. No differences in genotype or allelic frequencies were observed between RA patients and controls. Conclusions:,RA patients harbour multiple risk factors for statin-induced myopathy. However, the frequency of the rs4149056 genotypes does not differ according to the presence of RA. Despite this, no cases of statin-induced myopathy were observed in this cohort over a period of four years of follow-up. Thus, we conclude that statin use among RA patients is probably safe, but large-scale prospective studies are needed to confirm this. In the meantime, it may be good practice systematically to consider and record myopathy risk factors in these patients. Copyright © 2009 John Wiley & Sons, Ltd [source]


    The FOOTSTEP self-management foot care programme: Are rheumatoid arthritis patients physically able to participate?

    MUSCULOSKELETAL CARE, Issue 1 2009
    PgCert, R. Semple BSc Hons
    Abstract Background:,The FOOTSTEP self-management foot care programme is a clinical and cost-effective programme for basic foot care in the elderly. The aim of this study was to determine if patients with rheumatoid arthritis (RA) would be physically able to participate. Methods:,A consecutive cohort of RA patients undergoing podiatry care underwent tests for sight, reach and grip strength to determine their physical ability to undertake self-managed foot care. Results:,Thirty RA patients (10 male, 20 female), with a median age of 61 years (range 42 to 84) and disease duration of 10 years (range one to 40), were recruited. All patients passed the sight test, whereas the reach and grip tests were passed by 77% and 67% of patients, respectively. Only 57% of patients passed all the physical tests. Patients who failed the physical tests were older, and had longer disease duration and higher physical disability, pain and general health scores but these were not statistically different. Conclusions:,Just over half the patients in this present cohort may be physically able to undertake some aspects of self-managed foot care, including nail clipping and filing, callus filing and daily hygiene and inspection. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    The development of a user-led clinical service for newly diagnosed rheumatoid arthritis patients.

    MUSCULOSKELETAL CARE, Issue 4 2004
    An action research study
    Abstract Objective: To identify the clinical services required to meet the perceived needs of patients within the first 6,12 months following a diagnosis of rheumatoid arthritis in an orthopaedic NHS trust. Methods: An action research methodology was utilized. Twenty three newly diagnosed patients were asked to complete a questionnaire focusing on their needs at the time of diagnosis. The content included reactions to diagnosis, physical and psychological implications and clinical services that were required. A sub-sample of patients (n = 6) participated in an interview to explore these issues in more depth. A questionnaire was also distributed to 14 members of the multidisciplinary team (MDT) to ascertain their views on the purpose, content, and provision of a clinical service for newly diagnosed patients. Results: Eighteen patients agreed to take part (M:F, 9:9, age range 23,74 years, mean age 52.3 years, mean disease duration from diagnosis 16 weeks). Data from the questionnaires and interviews led to the following themes being identified: pre-diagnosis anxiety and fear, the impact of the diagnosis, physical and psychological implications of the diagnosis, and issues related to control perceptions. There was concordance between the MDT and the patients regarding impact of the disease and the need for information. Areas of the service that were identified independently by patients related to the importance of the period of time pre-diagnosis while awaiting the hospital appointment, and employment issues. Conclusions: This study has identified the impact of RA in the early stages of pre- and post- diagnosis on physical, psychological and social functioning and has consequently informed service development. Copyright © 2004 Whurr Publishers Ltd. [source]


    Patient education in arthritis: helping people change

    MUSCULOSKELETAL CARE, Issue 2 2003
    Alison Hammond PhD, BSc(Hons), DipCOTArticle first published online: 16 FEB 200
    Abstract Systematic reviews of education for arthritis patients have emphasized behavioural approaches are effective in facilitating behaviour change and improving psychological and health status. This article discusses how a range of patient education and motivational approaches could be integrated into clinical practice to help people make behavioural changes to benefit their health. These include information giving, counselling, motivational interviewing, behaviour-orientated self-management therapy and cognitive,behavioural approaches. Copyright © 2003 Whurr Publishers Ltd. [source]


    MS analysis of rheumatoid arthritic synovial tissue identifies specific citrullination sites on fibrinogen

    PROTEOMICS - CLINICAL APPLICATIONS, Issue 5 2010
    Monika Hermansson
    Abstract Purpose: Citrullination is a post-translational modification of arginine residues to citrulline catalyzed by peptidyl arginine deiminases. Induced expression of citrullinated proteins are frequently detected in various inflammatory states including arthritis; however, direct detection of citrullination in arthritic samples has not been successfully performed in the past. Experimental design: Citrullination of human fibrinogen, a candidate autoantigen in arthritis, was studied. Accurate identification of citrullinated fibrinogen peptides from rheumatoid arthritis synovial tissue specimens was performed using accurate mass and retention time analysis. Results: A peptide with the sequence ESSSHHPGIAEFPSRGK corresponding to amino acids 559,575 of fibrinogen ,-chain was identified to be citrullinated with an occupancy rate between 1.4 and 2.5%. Citrullination of the peptide KREEAPSLRPAPPPISGGGYRARPAK corresponding to amino acids 52,77 of the fibrinogen ,-chain was identified with an occupancy rate of 1.2%. Conclusions and clinical relevance: We report a proof of principle study for the identification of citrullinated proteins and within them, identification of citrullination sites and quantification of their occupancies in synovial tissue from rheumatoid arthritis patients using high-resolution MS. Detailed studies on which molecules are citrullinated in arthritis can provide information about their role in immune regulation and serve as novel biomarkers and potentially even as therapeutic targets. [source]


    MS characterization of apheresis samples from rheumatoid arthritis patients for the improvement of immunoadsorption therapy , a pilot study

    PROTEOMICS - CLINICAL APPLICATIONS, Issue 7 2009
    Mike Kienbaum
    Abstract Identification of proteins from apheresis samples was performed by both SDS-PAGE and 2-D gel separation of eluted proteins from staphylococcal protein A-based immunoadsorption columns (Prosorba®) followed by MS peptide mass fingerprinting and MS/MS peptide sequencing on a MALDI QIT TOF mass spectrometer. MS/MS peptide sequencing was performed in conjunction with a micro reversed phase HPLC configured with an online MALDI plate-spotting device. Apheresis treatment had been performed in three patients with longstanding therapy refractory rheumatoid arthritis. 2-D gels displayed ca. 500 spots representing proteins that were eluted from the Prosorba® columns. From 54 gels, a total of 1256 protein spots had been picked and yielded in the identification of 56 non-redundant proteins without counting isoforms. Proteins from the eluates belong to five major groups comprising (i) immunoglobulins (IgG, IgA, IgM heavy and light chains; about 40% of the spots), (ii) proteins involved in coagulation, (iii) HDL/LDL-associated proteins, (iv) proteins from the complement system, and (v) acute phase proteins. MS analysis showed that the full-length C3 complement protein had been cleaved upon complement activation, presumably on the column, such that the anaphylatoxin C3a was produced and released during therapy. Our results are consistent with clinical observations on both patient responses to therapy and reported adverse events. For the first time, direct molecular information has become available to support mechanistic reasoning for the principle of function of staphylococcal protein A-based immunoadsorption therapy and for the explanation of adverse events. According to our results, removal and/or modulation of immune complexes together with complement activation can be regarded as the major events that are taking place during Prosorba® therapy. In order to avoid complement activation and induction of an inflammatory cascade, we suggest the prevention of C3a anaphylatoxin-related reactions during immunoadsorption therapy. [source]


    Cilostazol enhances apoptosis of synovial cells from rheumatoid arthritis patients with inhibition of cytokine formation via Nrf2-linked heme oxygenase 1 induction

    ARTHRITIS & RHEUMATISM, Issue 3 2010
    So Youn Park
    Objective To assess the effects of cilostazol in inhibiting proliferation and enhancing apoptosis in synovial cells from patients with rheumatoid arthritis (RA). Methods Synovial cell proliferation was measured by MTT assay. The expression of NF-,B, I,B,, Bcl-2, Bax, heme oxygenase 1 (HO-1), and Nrf2 was determined by Western blotting. Results Cilostazol suppressed synovial cell proliferation by arresting the G2/M phases of the cell cycle, and this was reversed by KT5720, an inhibitor of protein kinase A. Cilostazol increased the number of TUNEL-positive cells, with increased cytochrome c release and apoptosis-inducing factor translocation as well as increased caspase 3 activation. Cilostazol (10 ,M) and cobalt protoporphyrin IX (CoPP) increased HO-1 messenger RNA and protein expression. These effects were suppressed by zinc protoporphyrin IX (ZnPP), an HO-1 inhibitor. Cilostazol and CoPP significantly increased I,B, in the cytosol and decreased NF-,B p65 expression in the nucleus. Increased expression of tumor necrosis factor , (TNF,), interleukin-1, (IL-1,), and IL-6 induced by lipopolysaccharide was attenuated by cilostazol and CoPP, and this was reversed by ZnPP. In mice with collagen-induced arthritis treated with cilostazol (10 and 30 mg/kg/day), paw thickness was decreased with increased apoptotic cells in the joints. In synovial cells transfected with small interfering RNA (siRNA) targeting HO-1, cilostazol did not suppress expression of TNF,, IL-1,, and IL-6, in contrast to findings with negative control cells. Cilostazol- and CoPP-induced HO-1 expression was diminished in cells transfected with Nrf2 siRNA. Conclusion Cilostazol suppressed proliferation of synovial cells from RA patients by enhancing apoptosis, and also inhibited cytokine production via mediation of cAMP-dependent protein kinase activation,coupled Nrf2-linked HO-1 expression. [source]


    Periarticular bone structure in rheumatoid arthritis patients and healthy individuals assessed by high-resolution computed tomography

    ARTHRITIS & RHEUMATISM, Issue 2 2010
    Christian M. Stach
    Objective To define the nature of structural bone changes in patients with rheumatoid arthritis (RA) compared with those in healthy individuals by using the novel technique of high-resolution microfocal computed tomography (micro-CT). Methods Fifty-eight RA patients and 30 healthy individuals underwent a micro-CT scan of the proximal wrist and metacarpophalangeal joints. Bone lesions such as cortical breaks, osteophytes, and surface changes were quantified on 2-dimensional (2-D) slices as well as by using 3-D reconstruction images, and exact localization of lesions was recorded. Results Micro-CT scans could detect bone lesions <0.5 mm in width or depth. Small erosions could be observed in healthy individuals and RA patients, whereas lesions >1.9 mm in diameter were highly specific for RA. Cortical breaks were mostly found along the radial sites of the metacarpal heads. No significant difference in the presence of osteophytes between healthy individuals and RA patients was found. Cortical surface changes, presumably cortical thinning and fenestration, became evident from 3-D reconstructions and were more pronounced in RA patients. Conclusion Micro-CT allows exact detection of morphologic changes of juxtaarticular bone in healthy individuals and RA patients. Even healthy individuals occasionally show bone changes, but the severity of these lesions, with the exception of osteophytes, is greater in RA patients. Thus, micro-CT allows accurate differentiation among physiologic bone changes in joints and among types of pathologic bone damage resulting from RA. [source]


    The selective estrogen receptor , agonist Org 37663 induces estrogenic effects but lacks antirheumatic activity: A phase IIa trial investigating efficacy and safety of Org 37663 in postmenopausal female rheumatoid arthritis patients receiving stable background methotrexate or sulfasalazine

    ARTHRITIS & RHEUMATISM, Issue 2 2010
    Ronald F. van Vollenhoven
    Objective Multiple lines of evidence suggest that sex hormones may play a role in the pathogenesis or clinical expression of rheumatoid arthritis (RA). Studies on the effects of exogenous estrogens in RA patients have yielded contradictory results. We undertook this study to determine the effects of the selective estrogen receptor , (ER,) agonist Org 37663 in patients with RA, in terms of both its estrogenic effects and its ability to ameliorate disease activity. Methods A 10-week, multicenter, randomized, double-blind, placebo-controlled, parallel group, dose-finding, proof-of-concept trial was initiated to obtain data on the efficacy and safety of Org 37663 in postmenopausal female patients with RA who were receiving background treatment with either methotrexate or sulfasalazine. Patients were randomized to receive placebo or Org 37663 at doses of 4 mg/day, 15 mg/day, or 50 mg/week. The primary efficacy variable was the Disease Activity Score in 28 joints (DAS28). Results Org 37663 induced a clear biologic, estrogenic response in several organ systems, including a dose-related increase in levels of sex hormone binding globulin. However, the DAS28 decreased similarly for all treatment groups including placebo, indicating lack of clinical efficacy of Org 37663 in this trial. Conclusion The observed lack of clinical benefit in RA patients treated with an ER, agonist, in association with a clear biologic response to the study drug, provides evidence that a biologically relevant ER,-mediated estrogenic effect is not associated with a clinically relevant effect on RA symptoms and signs. [source]


    Methotrexate polyglutamate concentrations are not associated with disease control in rheumatoid arthritis patients receiving long-term methotrexate therapy,

    ARTHRITIS & RHEUMATISM, Issue 2 2010
    Lisa K. Stamp
    Objective There are limited data suggesting that methotrexate polyglutamate (MTXGlu) concentrations can guide MTX dosing in patients with rheumatoid arthritis (RA). The aim of this study was to define a therapeutic range of red blood cell (RBC) MTXGlun concentrations (where n refers to the number of glutamate groups), including threshold values for efficacy and adverse effects in patients receiving long-term oral MTX treatment. Methods A cross-sectional study of 192 patients receiving oral MTX was undertaken. Disease activity was assessed by the swollen and tender joint counts, the C-reactive protein level, and the Disease Activity Score in 28 joints (DAS28). High disease activity was defined as a DAS28 of >3.2. A standardized questionnaire regarding common MTX adverse effects was completed. Results The MTX dosage was significantly higher in patients in whom the swollen joint count and DAS28 were higher. The MTXGlu4, MTXGlu5, MTXGlu3,5, and MTXGlu1,5 concentrations were significantly higher in patients with high disease activity. After correction for age, the estimated glomerular filtration rate, and the MTX dosage, the association remained significant for MTXGlu5. RBC folate concentrations were significantly higher in the group with high disease activity. There was no association between any MTXGlun concentration and adverse effects. Conclusion In contrast to other studies, the results of the present study did not show a relationship between the MTXGlun concentration and reduced disease activity in patients with RA who were receiving long-term MTX therapy. However, disease activity was influenced by the RBC folate level, which may be a more important factor than MTXGlun concentrations for disease control. In accordance with the findings of previous studies, we were unable to show a relationship between MTXGlun concentrations and adverse effects. Prospective studies will be important to determine whether there is a role for measuring MTXGlun concentrations in patients receiving long-term treatment with MTX. [source]


    Association of the response to tumor necrosis factor antagonists with plasma type I interferon activity and interferon-,/, ratios in rheumatoid arthritis patients: A post hoc analysis of a predominantly Hispanic cohort

    ARTHRITIS & RHEUMATISM, Issue 2 2010
    Clio P. Mavragani
    Objective Despite the substantial clinical efficacy of tumor necrosis factor , (TNF,) antagonist therapy in patients with rheumatoid arthritis (RA), some patients respond poorly to such agents. Since an interferon (IFN) signature is variably expressed among RA patients, we investigated whether plasma type I IFN activity might predict the response to TNF antagonist therapy. Methods RA patients (n = 35), the majority of whom were Hispanic, from a single center were evaluated before and after initiation of TNF antagonist therapy. As controls, 12 RA patients from the same center who were not treated with a TNF antagonist were studied. Plasma type I IFN activity was measured using a reporter cell assay, and disease status was assessed using the Disease Activity Score in 28 joints (DAS28). Levels of interleukin-1 receptor antagonist (IL-1Ra) were determined in baseline plasma samples using a commercial enzyme-linked immunosorbent assay. The clinical response was classified according to the European League Against Rheumatism criteria for improvement in RA. Results Plasma type I IFN activity at baseline was significantly associated with clinical response (odds ratio 1.36 [95% confidence interval 1.05,1.76], P = 0.020), with high baseline IFN activity associated with a good response. Changes in DAS28 scores were greater among patients with a baseline plasma IFN,/, ratio >0.8 (indicating elevated plasma IFN, levels). Consistent with the capacity of IFN, to induce IL-1Ra, elevated baseline IL-1Ra levels were associated with better therapeutic outcomes (odds ratio 1.82 [95% confidence interval 1.1,3.29], P = 0.027). Conclusion The plasma type I IFN activity, the IFN,/, ratio, and the IL-1Ra level were predictive of the therapeutic response in TNF antagonist,treated RA patients, indicating that these parameters might define clinically meaningful subgroups of RA patients with distinct responses to therapeutic agents. [source]


    Rapid and sustained improvement in bone and cartilage turnover markers with the anti,interleukin-6 receptor inhibitor tocilizumab plus methotrexate in rheumatoid arthritis patients with an inadequate response to methotrexate: Results from a substudy of the multicenter double-blind, placebo-controlled trial of tocilizumab in inadequate responders to methotrexate alone,

    ARTHRITIS & RHEUMATISM, Issue 1 2010
    Patrick Garnero
    Objective To investigate the effects of tocilizumab (TCZ) added to a stable dosage of methotrexate (MTX) on biochemical markers of bone and cartilage metabolism in patients in the multicenter double-blind, placebo-controlled OPTION (Tocilizumab Pivotal Trial in Methotrexate Inadequate Responders) study who have moderate-to-severe rheumatoid arthritis (RA) and an inadequate response to MTX. Methods Included in this study were 416 of the 623 patients with active RA enrolled in the OPTION study. Patients were randomized to receive TCZ (4 mg/kg or 8 mg/kg) or placebo intravenously every 4 weeks, with MTX continued at the stable prestudy doses (10,25 mg for 20 weeks, with a final followup at week 24). Serum biochemical markers of bone formation (osteocalcin, N-terminal propeptide of type I collagen [PINP]), bone resorption (C-terminal crosslinking telopeptide of type I collagen [CTX-I] and C-terminal crosslinking telopeptide of type I collagen generated by matrix metalloproteinases [ICTP]), cartilage metabolism (N-terminal propeptide of type IIA collagen [PIIANP]), collagen helical peptide [HELIX-II]), and matrix metalloproteinase 3 (MMP-3) were measured at baseline and at weeks 4, 16, and 24. Results TCZ induced marked dose-dependent reductions in PIIANP, HELIX-II, and MMP-3 levels at week 4 that were maintained until week 24, an effect associated with increased levels of bone formation markers that were significant as compared with placebo only for PINP and only at 4 weeks (P < 0.01 for both TCZ doses). TCZ induced significant decreases in the bone degradation markers CTX-I and ICTP, providing initial evidence of a beneficial effect on bone turnover. TCZ-treated patients who met the American College of Rheumatology 50% improvement criteria (achieved an ACR50 response) or achieved clinical remission (as determined by a Disease Activity Score in 28 joints <2.6) at week 24 had greater reductions in ICTP, HELIX-II, and MMP-3 levels as compared with ACR50 nonresponders. Conclusion TCZ combined with MTX reduces systemic bone resorption, cartilage turnover, and proteolytic enzyme MMP-3 levels, which provides evidence of a limitation of joint damage and possible beneficial effects on skeletal structure in patients with established moderate-to-severe RA. [source]


    Antibodies to several citrullinated antigens are enriched in the joints of rheumatoid arthritis patients,

    ARTHRITIS & RHEUMATISM, Issue 1 2010
    Omri Snir
    Objective High titers of specific anti,citrullinated protein antibodies (ACPAs) are frequently present in the serum of rheumatoid arthritis (RA) patients, but their presence in synovial fluid is less well characterized. The purpose of this study was to compare the levels of antibody to 4 well-defined citrullinated candidate RA autoantigens in serum and synovial fluid and to determine whether antibodies to one citrullinated antigen are dominant over another. Furthermore, we studied their relationships with mutated citrullinated vimentin (MCV), a newly identified RA-specific serum assay, and the classic cyclic citrullinated peptide (CCP) in the synovial fluid of well-defined HLA,DR groups. Methods Paired serum and synovial fluid samples from 290 RA patients and serum samples from 100 age- and sex-matched healthy controls were analyzed for the presence of anti-MCV and anti-CCP antibodies and for reactivity to citrullinated fibrinogen, ,-enolase, type II collagen, and vimentin. A total of 219 of the 290 patients were genotyped for the HLA,DR shared epitope alleles. Results Significantly higher proportions of antibodies against all RA-associated citrullinated antigens were found in synovial fluid as compared with serum. This was also true for the MCV and CCP responses but not for non,RA-associated anti,tetanus toxoid antibodies. As expected, we found a high correlation between citrullinated vimentin and MCV responses. All synovial fluid ACPAs were predominantly associated with HLA,DRB1*04 alleles and were confined to the CCP+/MCV+ subset of patients. Conclusion MCV and CCP positivity represent a similar subset of RA patients, whereas ACPAs with different fine specificities fall into subgroups of anti-CCP+/anti-MCV+ patients. The levels of all specific ACPAs were elevated in synovial fluid, suggesting that there is local antibody production and/or retention of ACPAs at the site of inflammation governed by RA-predisposing genes. [source]


    Immunization responses in rheumatoid arthritis patients treated with rituximab: Results from a controlled clinical trial,

    ARTHRITIS & RHEUMATISM, Issue 1 2010
    Clifton O. Bingham III
    Objective To examine immunization responses in patients with rheumatoid arthritis (RA) treated with rituximab and to investigate the effects of rituximab-induced CD20+ B cell depletion on immune responses to tetanus toxoid (T cell,dependent antigen), pneumococcal polysaccharide (T cell,independent antigen), and keyhole limpet hemocyanin (KLH) (neoantigen) and on delayed-type hypersensitivity (DTH). Methods In a controlled trial, we enrolled 103 patients with active RA receiving a stable dose of methotrexate (MTX). Tetanus toxoid, pneumococcal polysaccharide, and KLH vaccines as well as a Candida albicans skin test were administered to 1 group of patients receiving rituximab plus MTX (called rituximab-treated patients) for 36 weeks and to 1 group of patients receiving MTX alone for 12 weeks. The primary end point was the proportion of patients with a ,4-fold rise in antitetanus IgG levels. Antitetanus, antipneumococcal, and anti-KLH serum IgG levels were measured prior to and 4 weeks following vaccine administration. The DTH response to C albicans was measured 2,3 days following placement. Results Responses to tetanus toxoid vaccine (,4-fold rise) were similar in both groups (39.1% of rituximab-treated patients and 42.3% of patients treated with MTX alone). The ability to maintain a positive DTH response to the C albicans skin test was comparable in both groups (77.4% of rituximab-treated patients and 70% of patients treated with MTX alone), showing no effect of rituximab treatment. Rituximab-treated patients had decreased responses to pneumococcal polysaccharide vaccine (57% of patients had a 2-fold rise in titer in response to ,1 serotype, compared with 82% of patients treated with MTX alone) and to KLH vaccine (47% of patients had detectable anti-KLH IgG, compared with 93% of patients treated with MTX alone). Conclusion Recall responses to the T cell,dependent protein antigen tetanus toxoid as well as DTH responses were preserved in rituximab-treated RA patients 24 weeks after treatment. Responses to neoantigen (KLH) and T cell,independent responses to pneumococcal vaccine were decreased, but many patients were able to mount responses. These data suggest that polysaccharide and primary immunizations should be administered prior to rituximab infusions to maximize responses. [source]


    B lymphocyte stimulator expression in pediatric systemic lupus erythematosus and juvenile idiopathic arthritis patients

    ARTHRITIS & RHEUMATISM, Issue 11 2009
    Sandy D. Hong
    Objective To assess the expression of B lymphocyte stimulator (BLyS) in patients with pediatric systemic lupus erythematosus (SLE) or juvenile idiopathic arthritis (JIA). Methods Blood samples collected from patients with pediatric SLE (n = 56) and patients with JIA (n = 54) at the beginning and end of a 6-month interval were analyzed for plasma BLyS protein levels by enzyme-linked immunosorbent assay and for blood leukocyte full-length BLyS and ,BLyS messenger RNA (mRNA) levels by quantitative real-time polymerase chain reaction (normalized to 18S expression). Healthy siblings (n = 34) of these patients served as controls. Results In pediatric SLE, plasma BLyS protein and blood leukocyte BLyS mRNA levels were each significantly elevated, and plasma BLyS protein levels, but not blood leukocyte BLyS mRNA levels, were correlated with disease activity. In contrast, plasma BLyS protein levels were normal in JIA despite blood leukocyte BLyS mRNA levels being elevated to degrees similar to those in pediatric SLE. Among JIA patients, neither BLyS parameter was correlated with disease activity. In both pediatric SLE and JIA, the BLyS expression profiles remained stable at 6 months. Conclusion Our findings indicate that, as previously noted in adult SLE, plasma BLyS protein and blood leukocyte BLyS mRNA levels are elevated in pediatric SLE. The correlation of plasma BLyS protein levels with disease activity points to BLyS as a candidate therapeutic target in pediatric SLE. Contrary to previous observations in adults with rheumatoid arthritis, plasma BLyS protein levels are normal in JIA despite elevated blood leukocyte BLyS mRNA levels. The absence of correlation between either of the BLyS parameters and disease activity in JIA calls for circumspection prior to assigning BLyS as a candidate therapeutic target in this disorder. [source]


    Normalization of A2A and A3 adenosine receptor up-regulation in rheumatoid arthritis patients by treatment with anti,tumor necrosis factor , but not methotrexate

    ARTHRITIS & RHEUMATISM, Issue 10 2009
    Katia Varani
    Objective To investigate A1, A2A, A2B, and A3 adenosine receptors in lymphocytes and neutrophils from patients with early rheumatoid arthritis (ERA) as well as from RA patients treated with methotrexate (MTX) or anti,tumor necrosis factor , (anti-TNF,), as compared with those in age-matched healthy controls, and to examine correlations between the status and functionality of adenosine receptors and TNF, release and NF-,B activation. Methods Adenosine receptors were analyzed by saturation binding assays and Western blot analyses. We investigated the potency of typical A2A and A3 agonists in the production of cAMP in control subjects, ERA patients, and RA patients treated with MTX or anti-TNF,. In a separate cohort of RA patients, TNF, release and NF-,B activation were evaluated in plasma and nuclear extracts, respectively. Results In ERA patients, we found a high density and altered functionality of A2A and A3 receptors. The binding and functional parameters of A2A and A3 receptors normalized after anti-TNF,, but not MTX, treatment. TNF, release was increased in ERA patients and in MTX-treated RA patients, whereas in anti-TNF,,treated RA patients, release was comparable to that in the controls. NF-,B activation was elevated in ERA patients and in MTX-treated RA patients. Anti-TNF, treatment mediated decreased levels of NF-,B activation. Conclusion A2A and A3 receptor up-regulation in ERA patients and in MTX-treated RA patients was associated with high levels of TNF, and NF-,B activation. Treatment with anti-TNF, normalized A2A and A3 receptor expression and functionality. This new evidence of A2A and A3 receptor involvement opens the possibility of exploiting their potential role in human diseases characterized by a marked inflammatory component. [source]


    Determinants of red blood cell methotrexate polyglutamate concentrations in rheumatoid arthritis patients receiving long-term methotrexate treatment,

    ARTHRITIS & RHEUMATISM, Issue 8 2009
    Lisa K. Stamp
    Objective Methotrexate (MTX) is the most commonly used disease-modifying antirheumatic drug (DMARD) in the management of rheumatoid arthritis (RA). MTX is transported into cells, where additional glutamate moieties are added and it is retained as MTX polyglutamates (MTXGlu [referred to as a group as MTXGlun]). There is large interpatient variability in MTXGlun concentrations. This study was undertaken to determine nongenetic factors that influence red blood cell (RBC) MTXGlun concentrations in patients receiving long-term stable low-dose oral MTX. Methods One hundred ninety-two patients receiving long-term oral MTX for the treatment of RA were recruited. Trough MTXGlun concentrations were measured by high-performance liquid chromatography. Univariate analysis was performed to determine variables influencing MTXGlun concentrations. Backward stepwise multivariate regression analysis was done to determine variables that affect individual MTXGlun concentrations; variables with P values of <0.1 in the univariate analysis for any MTXGlun were included. Results Univariate analysis revealed that increased age, lower estimated glomerular filtration rate (GFR), higher MTX dosage, longer duration of MTX treatment, and use of prednisone were associated with significantly higher MTXGlun concentrations. Smokers had significantly lower concentrations of MTXGlu3, MTXGlu3,5, and MTXGlu1,5. Sex, rheumatoid factor and anti,cyclic citrullinated peptide status, RBC folate level, and body mass index had no significant effect on MTXGlun levels. Concomitant use of other DMARDs was associated with lower MTXGlu2 levels, and treatment with nonsteroidal antiinflammatory drugs was associated with lower MTXGlu3 and MTXGlu1,5 concentrations. Multivariate regression analysis revealed that age, MTX dosage, and estimated GFR were the major determinants of MTXGlun concentrations. Conclusion Large interpatient variability in MTXGlun concentrations can be explained, at least in part, by a combination of factors, particularly age, MTX dosage, and renal function. There are complex interactions between smoking, RBC folate levels, and concentrations of MTXGlun. [source]