IL-10 from marginal zone precursor B cells controls the differentiation of Th17, Tfh and Tfr cells in transplantation tolerance.

B cells are known to control CD4T cell differentiation in secondary lymphoid tissues. We hypothesized that IL-10 expression by marginal zone precursor (MZP) regulatory B cells controls the differentiation and positioning of effector and regulatory T cells during tolerization. Costimulatory blockade with donor-specific transfusion (DST) and anti-CD40L mAb in C57BL/6 mice induced tolerance to allogeneic cardiac allograft. B cell depletion or IL-10 deficiency in B cells prevented tolerance, resulting in decreased follicular regulatory CD4(+) T cells (Tfr) and increased IL-21 expression by T follicular helper (Tfh) cells in the B cell and T cell zones. IL-21 acted with IL-6 to induce CCR6(+) Th17 that caused rejection. Deficiency or blockade of IL-6, IL-21, IL-21R, or CCR6 prevented B cell depletion-induced acute cellular rejection; while agonistic mCCL20-Ig induced rejection. Adoptive transfer of IL-10(+/+) MZP in tolerogen treated CD19-Cre(+/-):IL-10(fl/fl) mice rescued the localization of Tfh and Tfr cells in the B cell follicle and prevented allograft rejection. MZP B cell IL-10 is necessary for tolerance and controls the differentiation and position of Th17, Tfh and Tfr cells in secondary lymphoid tissues. This has implications for understanding tolerance induction and how B cell depletion may prevent tolerance.

Interleukin-10 From Marginal Zone Precursor B-Cell Subset Is Required for Costimulatory Blockade-Induced Transplantation Tolerance.

BACKGROUND: Blocking CD40-CD40L costimulatory signals induces transplantation tolerance. Although B-cell depletion prevents alloantibody formation, nonhumoral functions of B cells in tolerance have not been well characterized. We investigated whether specific subsets of B cell or B cell-derived interleukin (IL)-10 contribute to tolerance. METHODS: Wild type C57BL/6, or B cell-specific interleukin (IL)-10 (CD19-Cre::IL-10) mice, received vascularized BALB/c cardiac allografts. BALB/c donor-specific splenocyte transfusion and anti-CD40L monoclonal antibody were used as tolerogen. B cells were depleted with antimouse CD20 monoclonal antibody. Various B-cell subsets were purified and characterized by flow cytometry, reverse transcription polymerase chain reaction, and adoptive transfer. RESULTS: B-cell depletion prevented costimulatory blockade-induced allogeneic tolerance. Costimulatory blockade increased IL-10 in marginal zone precursor (MZP) B cells, but not other subsets. In particular, costimulatory blockade did not change other previously defined regulatory B-cell subsets (Breg), including CD5CD1d Breg or expression of TIM1 or TIM4 on these Breg or other Breg cell subsets. Costimulatory blockade also induced IL-21R expression in MZP B cells, and IL-21R MZP B cells expressed even more IL-10. B-cell depletion or IL-10 deficiency in B cells prevented tolerance in a cardiac allograft model, resulting in rapid acute cardiac allograft rejection. Adoptive transfer of wild type MZP B cells but not other subsets to B cell-specific IL-10 deficient mice prevented graft rejection. CONCLUSIONS: CD40 costimulatory blockade induces MZP B cell IL-10 which is necessary for tolerance. These observations have implications for understanding tolerance induction and how B cell depletion may prevent tolerance.

Role of miRNAs in CD4 T cell plasticity during inflammation and tolerance.

Gene expression is tightly regulated in a tuneable, cell-specific and time-dependent manner. Recent advancement in epigenetics and non-coding RNA (ncRNA) revolutionized the concept of gene regulation. In order to regulate the transcription, ncRNA can promptly response to the extracellular signals as compared to transcription factors present in the cells. microRNAs (miRNAs) are ncRNA (~22 bp) encoded in the genome, and present as intergenic or oriented antisense to neighboring genes. The strategic location of miRNA in coding genes helps in the coupled regulation of its expression with host genes. miRNA together with complex machinery called RNA-induced silencing complex (RISC) interacts with target mRNA and degrade the mRNA or inhibits the translation. CD4 T cells play an important role in the generation and maintenance of inflammation and tolerance. Cytokines and chemokines present in the inflamed microenvironment controls the differentiation and function of various subsets of CD4 T cells [Th1, Th2, Th17, and regulatory CD4 T cells (Tregs)]. Recent studies suggest that miRNAs play an important role in the development and function of all subsets of CD4 T cells. In current review, we focused on how various miRNAs are regulated by cell's extrinsic and intrinsic signaling, and how miRNAs affect the transdifferentiation of subsets of CD4 T cell and controls their plasticity during inflammation and tolerance.

The effect of aspirin on atherogenic diet-induced diabetes mellitus.

Exploration of atherogenic diet-induced diabetes mellitus and the evaluation of antidiabetic potential of aspirin were carried out in this study. Male albino Wistar rats were divided into three groups of seven each (1, 2 and 3). Animals of groups 2 and 3 received CCT diet (normal rat chow supplemented with 4% cholesterol, 1% cholic acid and 0.5%, 2-thiouracil), whereas the animals of group 1 received normal feed and served as control. In addition to CCT, animals of group 3 (CCT + Asp) also received aspirin (8 gm/kg), commencing from day 8 till the end of study (day 15). In another experiment (exp. 2), aspirin-supplemented normal rat chow (Asp) was fed to the animals for 7 days and compared with the normal rat chow-fed control group. In experiment 3, an in vitro nitric oxide radical-scavenging potential of aspirin at three different doses (25, 50 and 100 µg/ml) was evaluated. In response to CCT diet, a decrease in serum insulin, α-amylase activity, hepatic glycogen, pancreatic calcium with a concomitant increase in serum glucose, lipid profile (except high-density lipoprotein cholesterol (HDL-C)), pancreatic nitrite and lipid peroxidation and the size of adipocytes along with macrophages infiltration were observed. Aspirin administration to CCT diet-fed animals (CCT + Asp) reverted all the studied biochemical and histological changes towards normality. In experiment 2, aspirin administration decreased the serum glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C) and VLDL-C with concomitantly increased HDL-C and insulin; however, it increased hepatic glycogen and pancreatic calcium concentration with a decrease in pancreatic and adipose lipid peroxidation. In vitro assay revealed the nitric oxide radical-scavenging potential of aspirin in all the studied doses. It is concluded that CCT diet-induced diabetes mellitus might be the outcome of nitric oxide radical-induced oxidative stress in pancreatic tissue, as well as diminished insulin secretion because of decrease in pancreatic calcium release, obesity and inflammation. However, aspirin treatment reversed all the above-mentioned parameters to normality.