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Functional Defects (functional + defect)
Selected AbstractsFunctional defect of circulating regulatory CD4+ T cells in patients with Wegener's granulomatosis in remissionARTHRITIS & RHEUMATISM, Issue 6 2007Wayel H. Abdulahad Objective Accumulating data support the role of regulatory T cells, a subset of CD4+ T cells that expresses CD25high and the transcription factor forkhead box P3 (FoxP3), in controlling and preventing autoimmunity. In Wegener's granulomatosis (WG), an autoimmune vasculitis, up-regulation of CD25 on circulating CD4+ T cells has been observed, even in patients in remission. The objective of this study was to test whether the frequency and/or function of Treg cells from WG patients in remission are disturbed. Methods Peripheral blood mononuclear cells were freshly isolated from 52 WG patients in remission and from 27 age- and sex-matched healthy control subjects. The proportion of circulating Treg cells was assessed by flow cytometry using CD4, CD25, FoxP3, and CD45RO markers. Anergy and suppressive function of CD25high,CD4+ T cells were determined using polyclonal stimulants and coculture assay in 10 WG patients in remission and in 10 age- and sex-matched healthy controls. Results In WG patients, a significant increase was observed in the percentage of circulating CD25high,CD4+ and CD25low,CD4+ T cells, whereas CD25,,CD4+ T cells were decreased, as compared with healthy controls. Among circulating CD4+ T cells, an expanded percentage of Treg cells (CD25high,FoxP3+) with memory phenotype was present in WG patients. However, when the suppressive function of CD25high,CD4+ T cells was tested, CD25high,CD4+ T cells from WG patients showed diminished or absent suppression of responder T cell proliferation. The impaired suppression was not due to responder cell resistance (as shown by crisscross experiments with T cells from healthy controls) or altered survival of Treg cells. Conclusion These data indicate that WG patients in remission have an expanded proportion of Treg cells that are functionally defective. This observation may be relevant to the development and relapsing course of this autoimmune vasculitis. [source] Role of Shc in T-cell development and functionIMMUNOLOGICAL REVIEWS, Issue 1 2003Li Zhang Summary: Shc is a prototype adapter protein that is expressed from the earliest stages of T-cell development. Shc becomes rapidly tyrosine phosphorylated after T-cell receptor (TCR) engagement. Expression of dominant negative forms of Shc in T-cell lines had also suggested a role for this adapter downstream of the TCR. However, until recently, the relative significance of Shc compared to several other adapters in T cells was unclear. Mice lacking Shc expression specifically in the T-cell lineage together with inducible expression of dominant negative Shc in transgenic mice have revealed an essential and nonredundant role for Shc in thymic T-cell development. Functional defects in a Jurkat T-cell line lacking Shc expression also suggest a role for Shc in mature T-cell functions. While the requirement of Shc in T-cell signaling is now established, precisely what signaling pathways downstream of Shc make this adapter unique are less clear. Although the Shc-mediated activation of the extracellular signal regulated kinase (Erk)/mitogen-activated protein kinase (MAPK) pathway could be one component, Shc likely signals to other pathways in T cells that are not yet discovered. A better molecular understanding of Shc function in the future could provide insights into how multiple adapters coordinate the various outcomes downstream of the TCR. [source] Complementation of NADPH oxidase in p67-phox-deficient CGD patientsFEBS JOURNAL, Issue 4 2000p67-phox/p40-phox interaction Chronic granulomatous disease (CGD) is due to a functional defect of the O2, generating NADPH oxidase of phagocytes. Epstein,Barr-virus-immortalized B lymphocytes express all the constituents of oxidase with activity 100 times less than that of neutrophils. As in neutrophils, oxidase activity of Epstein,Barr-virus-immortalized B lymphocytes was shown to be defective in the different forms of CGD; these cells were used as a model for the complementation studies of two p67-phox-deficient CGD patients. Reconstitution of oxidase activity was performed in vitro by using a heterologous cell-free assay consisting of membrane-suspended or solubilized and purified cytochrome b558 that was associated with cytosol or with the isolated cytosolic-activating factors (p67-phox, p47-phox, p40-phox) from healthy or CGD patients. In p67-phox-deficient CGD patients, two cytosolic factors are deficient or missing: p67-phox and p40-phox. Not more than 20% of oxidase activity was recovered by complementing the cytosol of p67-phox-deficient patients with recombinant p67-phox. On the contrary, a complete restoration of oxidase activity was observed when, instead of cytosol, the cytosolic factors were added in the cell-free assay after isolation in combination with cytochrome b558 purified from neutrophil membrane. Moreover, the simultaneous addition of recombinant p67-phox and recombinant p40-phox reversed the previous complementation in a p40-phox dose-dependent process. These results suggest that in the reconstitution of oxidase activity, p67-phox is the limiting factor; the efficiency of complementation depends on the membrane tissue and the cytosolic environment. In vitro, the transition from the resting to the activated state of oxidase, which results from assembling, requires the dissociation of p40-phox from p67-phox for efficient oxidase activity. In the process, p40-phox could function as a negative regulatory factor and stabilize the resting state. [source] p.Gln200Glu, a putative constitutively active mutant of rod ,-transducin (GNAT1) in autosomal dominant congenital stationary night blindness,,HUMAN MUTATION, Issue 7 2007Viktoria Szabo Abstract Congenital stationary night blindness (CSNB) is a non-progressive Mendelian condition resulting from a functional defect in rod photoreceptors. A small number of unique missense mutations in the genes encoding various members of the rod phototransduction cascade, e.g. rhodopsin (RHO), cGMP phosphodiesterase ,-subunit (PDE6B), and transducin ,-subunit (GNAT1) have been reported to cause autosomal dominant (ad) CSNB. While the RHO and PDE6B mutations result in constitutively active proteins, the only known adCSNB-associa-ted GNAT1 change (p.Gly38Asp) produces an ,-transducin that is unable to activate its downstream effector molecule in vitro. In a multigeneration Danish family with adCSNB, we identified a novel heterozygous C to G transversion (c.598C>G) in exon 6 of GNAT1 that should result in a p.Gln200Glu substitution in the evolutionarily highly conserved Switch 2 region of ,-transducin, a domain that has an important role in binding and hydrolyzing GTP. Computer modeling based on the known crystal structure of transducin suggests that the p.Gln200Glu mutant exhibits impaired GTPase activity, and thereby leads to constitutive activation of phototransduction. This assumption is in line with our results of trypsin protection assays as well as previously published biochemical data on mutants of this glutamine in the GTPase active site of ,-transducin following in vitro expression, and observations that inappropriately activating mutants of various members of the rod phototransduction cascade represent one of the major molecular causes of adCSNB. © 2007 Wiley-Liss, Inc. [source] Effect of ,-butyrobetaine on fatty liver in juvenile visceral steatosis miceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2001Yasuhiko Higashi We pharmacokinetically examined the effect of ,-butyrobetaine, a precursor of l -carnitine, on the change of fatty acid metabolism in juvenile visceral steatosis (JVS) mice, which have systemic l -carnitine deficiency due to lack of l -carnitine transporter activity. The concentrations of total free fatty acid (FFA), palmitic acid and stearic acid in the liver of JVS mice were significantly higher than those in wild-type mice. After intravenous administration of ,-butyrobetaine (50 mg kg,1), the concentration of l -carnitine in the plasma of JVS mice reached about twice that of the control level and levels in the brain, liver and kidney were also significantly increased, whereas those in wild-type mice hardly changed. Although the plasma concentrations of FFA in both types of mice were unchanged after administration of ,-butyrobetaine, the concentrations of palmitic acid and stearic acid were significantly decreased. In particular, the liver concentration of FFA in JVS mice was decreased to the wild-type control level, accompanied by significant decreases in long-chain fatty acids, palmitic acid and stearic acid, whereas those in wild-type mice were not changed. These results suggest that ,-butyrobetaine can be taken up into organs, including the liver, of JVS mice, and transformed to l -carnitine. Consequently, administration of ,-butyrobetaine may be more useful than that of l -carnitine itself for treatment of primary deficiency of carnitine due to a functional defect of the carnitine transporter. [source] Dendritic cell infiltration pattern along the colorectal adenoma-carcinoma sequence,APMIS, Issue 6 2008APING YUAN We have previously reported that the dendritic cell (DC) functional index cytokine interleukin-12 was significantly decreased in colorectal carcinoma (CRC) tissues. In this study, the DC infiltration pattern and the density of mature DCs (mDCs; labeled by anti-CD83 and anti-CD208) and immature DCs (iDCs; labeled by anti-CD1,) were characterized using immunohistochemistry (IHC) in tissue samples from 23 patients with CRC, 33 patients with colorectal adenoma (CRA), and 19 healthy controls. In addition, the DC function inhibitor cyclooxygenase-2 (COX-2) and the downstream signal molecule prostaglandin E2 (PGE2) and related receptors EP2/EP4 were measured by quantitative real-time PCR and double immunofluorescence staining. The IHC analyses revealed changed densities of mDCs and iDCs in the tumor microenvironment; in CRA and CRC, the density of mDCs was decreased, but the density of iDCs was gradually increased. Furthermore, the distribution patterns of DCs were also altered. In CRA, mDCs were abundantly distributed in the subepithelial stroma of the adenomatous mass. In CRC, the distribution of mDCs in the tumor stroma was not homogeneous, and mDCs residing in the stroma at invading edges were more frequently found compared with in the intratumoral stroma (P<0.05). Increased iDCs were found in the intratumoral mass in CRC, and some infiltrated into the malignant epithelium. By quantitative real-time PCR, a gradually increased level of COX-2 mRNA was demonstrated in the local tissues along the adenoma-carcinoma sequence, and double immunofluorescence staining showed a colocalization of PGE2 receptors EP2/EP4 with mDCs in the stroma of CRC. In conclusion, our current findings revealed an altered DC infiltration pattern along the adenoma-carcinoma sequence; gradually increased COX-2 expression might contribute to the DC functional defect. [source] Hereditary angioedema and pregnancyAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 1 2009Niranthari CHINNIAH Background:, Hereditary angioedema (HAE) is an autosomal dominant disease caused by a quantitative or functional defect in C1-esterase inhibitor (C1-INH). Patients with this deficiency present with episodes of angioedema which can be life-threatening. Studies examining HAE and pregnancy are scarce with little known about the interrelationship between the two. Objective:, To examine the effect, and evaluate the clinical manifestations of HAE in pregnancy using retrospective interviews of affected women. Methods:, Women with HAE who have undergone one of more pregnancies were identified throughout Australia using the national Australasian Society of Clinical Immunology and Allergy immunodeficiency database. Following informed consent, identified women were interviewed regarding their HAE status during pregnancy and the perinatal period using a questionnaire. Results:, Seven women with a total of 16 pregnancies were identified. During the first trimester of pregnancy, more than ten attacks of angioedema were experienced in six of 16 pregnancies. During the second trimester only in three of 16 pregnancies did women experience greater than ten attacks. During the post-partum period, four of seven women experienced increased frequency and severity of attacks as compared to the pre-pregnancy state. For two of four patients, this impacted on their breast-feeding routine. Conclusion:, Our study showed that women with HAE have greatly reduced or absent attacks in the last two trimesters of pregnancy, although, during the post-partum period, the majority of women experienced increased frequency and severity of attacks. [source] Hyperthermia in utero due to maternal influenza is an environmental risk factor for schizophreniaCONGENITAL ANOMALIES, Issue 3 2007Marshall J. Edwards ABSTRACT A hypothesis is presented that the association between maternal influenza and other causes of fever during the second trimester of pregnancy and the subsequent development of schizophrenia in the child is due to the damage caused by hyperthermia to the developing amygdalohippocampal complex and associated structures in the fetal brain. Hyperthermia is a known cause of congenital defects of the central nervous system and other organs after sufficiently severe exposures during early organogenesis. The pathogenic mechanisms include death of actively dividing neuroblasts, disruption of cell migration and arborization and vascular damage. In experimental studies, hyperthermia during later stages of central nervous system development also caused damage to the developing brainstem that was associated with functional defects. This damage usually results in hypoplasia of the parts undergoing active development at the time of exposure. Recent studies have shown no evidence of direct invasion of the fetus by the influenza virus. Factors that might interact with hyperthermia include familial liability to schizophrenia, season of birth, maternal nutrition, severe stress and medications used to alleviate the symptoms of fevers. The time of the development of the fetal amygdalohippocampal complex and the changes found in its structure and associated areas of the brain are compatible with the known effects of hyperthermia. [source] Severe functional impairment and elevated PD-1 expression in CD1d-restricted NKT cells retained during chronic HIV-1 infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2009Markus Moll Abstract Invariant CD1d-restricted NKT cells play important roles in regulating both innate and adaptive immunity. They are targeted by HIV-1 infection and severely reduced in number or even lost in many infected subjects. Here, we have investigated the characteristics of NKT cells retained by some patients despite chronic HIV-1 infection. NKT cells preserved under these circumstances displayed an impaired ability to proliferate and produce IFN-, in response to CD1d-restricted lipid antigen as compared with cells from uninfected control subjects. HIV-1 infection was associated with an elevated expression of the inhibitory programmed death-1 (PD-1) receptor (CD279) on the CD4, subset of NKT cells. However, blocking experiments indicated that the functional defects in NKT cells were largely PD-1-independent. Furthermore, the elevated PD-1 expression and the functional defects were not restored by anti-retroviral treatment, and the NKT cell numbers in blood did not recover significantly in response to treatment. The functional phenotype of NKT cells in these patients suggests an irreversible immune exhaustion due to chronic activation in vivo. The data demonstrate a severe functional impairment in the remaining NKT-cell compartment in HIV-1-infected patients, which limits the prospects to mobilize these cells in immunotherapy approaches in patients. [source] Novel mutations in type 2 Gaucher disease in Chinese and their functional characterization by heterologous expression,,HUMAN MUTATION, Issue 1 2005Nelson L.S. Tang Abstract We investigated 10 unrelated Chinese patients with type 2 Gaucher disease and performed ex vivo expression for the novel mutations to characterize their functional defects. These patients were diagnosed by enzymatic assays and clinicopathologic features over the past five years in a national centre in China. Genomic DNA was sequenced by a two-stage PCR approach for mutations in the functional GBA gene. Novel mutations were expressed with baculovirus-transfected Sf21 cells. Six novel mutations were found (in traditional nomenclature): P122L, Y363C, N382K, L383R, L385P, and M416V. Review of reported mutations indicated clustering of type 2 mutations in three regions of the GBA gene. Expression of novel mutations revealed that the enzyme defect could arise from one of two mechanisms: loss of catalytic activity (Y363C and M416V) or enzyme instability (P122L and N382K). © 2005 Wiley-Liss, Inc. [source] Positive Regulation of Adult Bone Formation by Osteoblast-Specific Transcription Factor Osterix,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2009Wook-Young Baek Abstract Osterix (Osx) is essential for osteoblast differentiation and bone formation, because mice lacking Osx die within 1 h of birth with a complete absence of intramembranous and endochondral bone formation. Perinatal lethality caused by the disruption of the Osx gene prevents studies of the role of Osx in bones that are growing or already formed. Here, the function of Osx was examined in adult bones using the time- and site-specific Cre/loxP system. Osx was inactivated in all osteoblasts by Col1a1-Cre with the activity of Cre recombinase under the control of the 2.3-kb collagen promoter. Even though no bone defects were observed in newborn mice, Osx inactivation with 2.3-kb Col1a1-Cre exhibited osteopenia phenotypes in growing mice. BMD and bone-forming rate were decreased in lumbar vertebra, and the cortical bone of the long bones was thinner and more porous with reduced bone length. The trabecular bones were increased, but they were immature or premature. The expression of early marker genes for osteoblast differentiation such as Runx2, osteopontin, and alkaline phosphatase was markedly increased, but the late marker gene, osteocalcin, was decreased. However, no functional defects were found in osteoclasts. In summary, Osx inactivation in growing bones delayed osteoblast maturation, causing an accumulation of immature osteoblasts and reducing osteoblast function for bone formation, without apparent defects in bone resorption. These findings suggest a significant role of Osx in positively regulating osteoblast differentiation and bone formation in adult bone. [source] 4252: An introduction to autoinflammatory syndromesACTA OPHTHALMOLOGICA, Issue 2010B BODAGHI To define the spectrum and pathophysiology of autoinflammatory syndromes. This term has been proposed to describe a new group of diseases characterized by attacks of seemingly unprovoked inflammation in the absence of pathogens, without significant levels of autoantibodies and autoreactive T cells. Hereditary periodic fever syndrome, Crohn's disease, Blau syndrome, Chronic infantile neurologic cutaneous and articular syndrome and Muckle-Wells syndrome are examples of autoinflammatory conditions characterized by recurrent attacks of inflammation without any association with auto-antigens. The study of autoinflammatory diseases has progressed from genetics to definition of the functional defects. Although a direct association between defective innate immune responses to bacterial components and these diseases has not been established yet, this hypothesis remains highly plausible. Mutations in genes encoding the tumour necrosis factor (TNF) receptor and pyrin superfamilies of molecules may induce persistence of leukocytes that would ordinarily undergo apoptosis with further amplification of inflammatory stimuli. The use of biologics may control some of these conditions. [source] Identification and functional characterization of three novel human melanocortin-4 receptor gene variants in an obese Chinese populationCLINICAL ENDOCRINOLOGY, Issue 2 2006Rong Rong Summary Objective, Mutations in the melanocortin-4 receptor gene (MC4R) are the most common monogenic form of human obesity. However, the contribution of MC4R mutations to obesity in Chinese has not been investigated. We studied the frequency of MC4R mutations in an obese southern Chinese population and the functional consequences of the novel variants identified. Methods, We screened for MC4R mutations in 227 obese [body mass index (BMI) 35·29 ± 5·75 kg/m2] and 100 lean (BMI 21·57 ± 0·29 kg/m2) southern Chinese subjects using PCR-direct sequencing. In vitro functional studies, including cell surface expression, ligand binding, and cyclic adenosine monophosphate (cAMP) accumulation, were performed to examine the functional properties of three novel missense mutations. Results, Apart from two previously reported polymorphisms, V103I and ,176 A > C, three novel missense heterozygous variants (Y35C, C40R and M218T) were identified. The polymorphisms ,176 A > C and Y35C were detected in both obese and normal subjects with similar frequency. C40R was identified only in an obese subject. Pedigree analysis revealed M218T carriers in both lean and obese subjects. The prevalence of V103I carriers in normal-weight controls was significantly higher than that in obese subjects (5·3%vs. 1·3%, P < 0·05). In vitro functional studies showed that all three novel missense variants have normal functions. Conclusions, Two known polymorphisms and three novel variants of the MC4R were identified. No overt functional defects were observed for the three novel MC4R variants, suggesting that they might not be the cause of obesity in variant carriers. [source] | |||||||||||||