Vivo Proliferation (vivo + proliferation)

Distribution by Scientific Domains

Selected Abstracts

Availability of autoantigenic epitopes controls phenotype, severity, and penetrance in TCR Tg autoimmune gastritis

Ditza Levin
Abstract We examined TCR:MHC/peptide interactions and in vivo epitope availability to explore the Th1- or Th2-like phenotype of autoimmune disease in two TCR Tg mouse models of autoimmune gastritis (AIG). The TCR of strains A23 and A51 recognize distinct IAd -restricted peptides from the gastric parietal cell H/K-ATPase. Both peptides form extremely stable MHC/peptide (MHC/p) complexes. All A23 animals develop a Th1-like aggressive, inflammatory AIG early in life, while A51 mice develop indolent Th2-like AIG at 6,8,wk with incomplete penetrance. A51 T cells were more sensitive than A23 to low doses of soluble antigen and to MHC/p complexes. Staining with IAd/peptide tetramers was only detectable on previously activated T cells from A51. Thus, despite inducing a milder AIG, the A51 TCR displays a higher avidity for its cognate IAd/peptide. Nonetheless, in vivo proliferation of adoptively transferred A51 CFSE-labeled T cells in the gastric lymph node was relatively poor compared with A23 T cells. Also, DC from WT gastric lymph node, presenting processed antigen available in vivo, stimulated proliferation of A23 T cells better than A51. Thus, the autoimmune potential of these TCR in their respective Tg lines is strongly influenced by the availability of the peptide epitope, rather than by differential avidity for their respective MHC/p complexes. [source]

Positive crosstalk between ERK and p38 in melanoma stimulates migration and in vivo proliferation

Yeriel Estrada
Summary Melanoma is one of the most therapy-resistant cancers. Activating mutations in BRAF and NRAS are the source of extracellular signal regulated protein kinase (ERK) pathway activation. We show that melanoma cell lines, originating in different metastatic sites, with BRAF or NRAS mutations, in addition to active mitogen activated protein kinase (MAPK),ERK, also have highly activated stress activated protein kinase (SAPK)-p38. This is in direct contrast to carcinoma cells in which the activity of the two kinases appears to be mutually exclusive; high level of p38 activity inhibits, through a negative feedback, ERK activity and prevents tumorigenesis. Melanomas are insensitive to ERK inhibition by p38 and utilize p38-signaling pathway for migration and growth in vivo. We found a positive functional loop linking the high ERK activity to surface expression of ,V,3-integrin. This integrin, by interacting with vitronectin, induces p38 activity and increases IL-8 production, enhancing cell migration. Because the negative loop from p38 to ERK is lost, the two kinases can remain simultaneously activated. Inhibition of ERK and p38 activities is more effective in blocking in vivo growth than inhibition of each kinase individually. Future therapies might have to consider targeting of both pathways. [source]

Combined Coinhibitory and Costimulatory Modulation with Anti-BTLA and CTLA4Ig Facilitates Tolerance in Murine Islet Allografts

W. Truong
Complex interactions between positive and negative cosignaling receptors ultimately determine the fate of the immune response. The recently identified coinhibitory receptor, B and T lymphocyte attenuator (BTLA), contributes to regulation of autoimmune and potentially alloimmune responses. We investigated the role of BTLA in a fully major histocompatibility complex-mismatched mouse islet transplant model. We report that anti-BTLA mAb (6F7) alone does not accelerate graft rejection. Rather, while CTLA4Ig alone improved allograft survival, the addition of anti-BTLA mAb to CTLA4Ig led to indefinite (>100 days) allograft survival. Immediately after treatment with anti-BTLA mAb and CTLA4Ig, islet allografts showed intact islets and insulin production despite a host cellular response, with local accumulation of Foxp3+ cells. We clearly demonstrate that combined therapy with anti-BTLA mAb and CTLA4Ig mice induced donor-specific tolerance, since mice accepted a second donor-specific islet graft without further treatment and rejected third party grafts. CTLA4Ig and anti-BTLA mAb limited the initial in vivo proliferation of CFSE-labeled allogeneic lymphocytes, and anti-BTLA mAb enhanced the proportion of PD-1 expressing T cells while depleting pathogenic BTLA+ lymphocytes. We conclude that targeting the BTLA pathway in conjunction with CTLA4Ig costimulatory blockade may be a useful strategy for promoting immunological tolerance in murine islet allografts. [source]

In vitro measurement of post-natal changes in proliferating satellite cell frequency during rat muscle growth

Takahiro SUZUKI
ABSTRACT Satellite cells, resident myogenic stem cells found in postnatal skeletal muscle, are most abundant during early postnatal development and sharply decline in frequency thereafter to adult levels in mice and rats. Therefore, postnatal changes in satellite cell mitotic activities are important aspects for further understanding a muscle growth strategy. In large meat-production animals, however, the traditional in vivo proliferation assay may be less realistic because it requires intra-peritoneal (ip) injection of huge dosage of mutagenic nucleosides, 3H-labeled thymidine or bromodeoxyuridine (BrdU), at each age-time of sacrifice. We report in the present pilot study using rats that in vivo proliferation activity of satellite cells can be evaluated by an in vitro BrdU-incorporation assay in early cultures. Briefly, satellite cells were prepared from upper hind-limb and back muscles and maintained for 24 h with imposing by BrdU addition for the last 2 h, followed by the regular immunocytochemistry for determining BrdU-incorporated cell percentage. This in vitro assay demonstrated a rapid decrease in proliferating satellite cell frequency to the adult level during about 3-month period after birth, and yielded a high correlation to the measurements by the in vivo BrdU ip-injection method during the postnatal period examined from day-2 to month-11. The in vitro proliferation assay may be further adaptable for large domestic animals by the combination with a muscle biopsy technique that enables age-interval sampling from the same growing animals. [source]

Elevated levels of transferrin receptor 2 mRNA, not transferrin receptor 1 mRNA, are associated with increased survival in acute myeloid leukaemia

Tsuyoshi Nakamaki
Summary Transferrin receptor 1 (TfR1) is a type II membrane protein that mediates cellular iron uptake. Transferrin receptor 2(TfR2), another receptor for transferrin (Tf), has recently been cloned. We examined expression levels of TfR1, TfR2-, (membrane form) and TfR2-, (non-membrane form) transcripts in cells from 67 patients with de novo acute myeloid leukaemia (AML) using reverse transcription-polymerase chain reaction (RT-PCR), and correlated the results with a variety of clinical features and disease outcomes of these patients. Significant correlations were noted between the levels of both TfR1 and TfR2-, (r = 0771, P < 0001) and TfR1 and TfR2-, (r = 0534, P < 0001). Unexpectedly, initial white blood cell (WBC) counts were inversely correlated with levels of expression of either TfR1(r = ,0357, P = 0003), TfR2-, (r = ,0486, P < 00001), or TfR2-, (r = ,0435, P = 00003). Only TfR2 expression was significantly associated with either serum iron (r = ,0270, P = 0045) or serum ferritin (r = ,0364, P = 0008). Multivariate analyses using Cox's proportional hazard model showed that elevated TfR2-,, but not TfR1 or TfR2-, mRNA levels significantly contributed to a better prognosis for AML patients. Furthermore, a group with high expression levels of both TfR2-, and TfR2-, survived significantly longer than a group without high expression of both of them (P < 001 by log-rank). The present study suggests that (i) TfRs-independent iron uptake might have an important role in in vivo proliferation of AML cells; (ii) expression of TfR2 (especially the , form) is a novel prognostic factor for patients with AML. [source]