Our results thus provide a novel mechanistic basis reconciling previous opposite observations in the field of infections and T1D. In addition, our finding that stimulation through

TLR2 constitutes a well-suited means to expand CD4+CD25+ Tregs while ameliorating their tolerogenic function in T1D opens new possibilities for therapy of this disease and possibly other autoimmune disorders. NOD/ShiLtJ mice, and WT or TLR2−/− C57BL/6J (B6) mice were purchased from the Jackson Laboratory. C57BL/6-RIP-GP (B6 RIP-GP) transgenic mice were described previously 5, 6. For infection, a single dose of 104 PFU LCMV Armstrong 53b was given BI 2536 chemical structure intraperitoneally. Blood glucose was monitored using OneTouch Ultra system (LifeScan), and mice exhibiting values greater than 300 mg/dL were considered diabetic. Animal work in all studies was approved by the LIAI Animal Care Committee. All injections were performed intraperitoneally in 200 μL volume. Tregs, DCs, and mouse anti-mouse TLR2 mAb (Invivogen) were injected in PBS, and P3C (EMC Microcollections) was injected in DMEM (Invitrogen). Pancreas was collected and snap-frozen at the indicated time point after treatment. Frozen sections were stained with hematoxylin and eosin, and insulitis was scored blinded, as follows: (0) no insulitis, (1) peri-insulitis with no islet destruction, (2) severe peri-insulitis and some infiltrating insulitis, (3)

infiltrating insulitis Selleck C646 and some islet destruction, (4) infiltrating insulits and extensive islet destruction (or islet destroyed). Cells were stained with fluorescently labeled mAbs (BD Biosciences, eBioscience, BioLegend, Caltag) as described previously 12. Suplatast tosilate Samples were processed on a LSRII or FACScalibur (BD Biosciences) and results analyzed using FlowJo (Tree Star). Non-specific binding was blocked using unlabeled anti-FcγR

(BD Biosciences). Intracellular Foxp3 expression was assessed using a Foxp3 detection kit (eBioscience). For intracellular staining of cytokines, CD4+CD25+ T cells were stimulated with PMA and ionomycin (10 ng/mL and 0.5 μg/mL, respectively) or anti-CD3 (5 μg/mL) in Brefeldin A (Sigma-Aldrich) buffer prior to mAb staining. Female mice were euthanized 21 days after P3C treatment or LCMV infection, at which point virus was cleared from lymphoid tissue (data not shown). Cell suspensions were prepared from pooled spleens, mesenteric, inguinal, and pancreatic LN of 10–25 mice per group, and CD4+CD25+ T cells were purified as described previously 12. Briefly, CD4+ T cells negatively selected by magnetic separation using sheep anti-rat Dynabeads (Dynal) were stained with biotinylated anti-CD25 mAb, and CD4+CD25+ cells were purified by magnetic separation using anti-streptavidin MACS microbeads (Miltenyi Biotec). Cell purity was measured by flow cytometry and always greater than 95%.