Rapamycin Combined with Anti-CD45RB mAb and IL-10 or with G-CSF Induces Tolerance in a Stringent Mouse Model of Islet Transplantation

Background: A large pool of preexisting alloreactive effector T cells can cause allogeneic graft rejection following transplantation. However, it is possible to induce transplant tolerance by altering the balance between effector and regulatory T (Treg) cells. Among the various Treg-cell types, Foxp3 +Treg and IL-10-producing T regulatory type 1 (Tr1) cells have frequently been associated with tolerance following transplantation in both mice and humans. Previously, we demonstrated that rapamycin+IL-10 promotes Tr1-cell-associated tolerance in Balb/c mice transplanted with C57BL/6 pancreatic islets. However, this same treatment was unsuccessful in C57BL/6 mice transplanted with Balb/c islets (classified as a stringent transplant model). We accordingly designed a protocol that would be effective in the latter transplant model by simultaneously depleting effector T cells and fostering production of Treg cells. We additionally developed and tested a clinically translatable protocol that used no depleting agent. Methodology/Principal Findings: Diabetic C57BL/6 mice were transplanted with Balb/c pancreatic islets. Recipient mice transiently treated with anti-CD45RB mAb+rapamycin+IL-10 developed antigen-specific tolerance. During treatment, Foxp3 +Treg cells were momentarily enriched in the blood, followed by accumulation in the graft and draining lymph node, whereas CD4 +IL-10 +IL-4 - T (i.e., Tr1) cells localized in the spleen. In long-term tolerant mice, only CD4 +IL-10 +IL-4 - T cells remained enriched in the spleen and IL-10 was key in the maintenance of tolerance. Alternatively, recipient mice were treated with two compounds routinely used in the clinic (namely, rapamycin and G-CSF); this drug combination promoted tolerance associated with CD4 +IL-10 +IL-4 - T cells. Conclusions/Significance: The anti-CD45RB mAb+rapamycin+IL-10 combined protocol promotes a state of tolerance that is IL-10 dependent. Moreover, the combination of rapamycin+G-CSF induces tolerance and such treatment could be readily translatable into the clinic. © 2011 Gagliani et al

Abnormal neutrophil signature in the blood and pancreas of presymptomatic and symptomatic type 1 diabetes

BACKGROUND. Neutrophils and their inflammatory mediators are key pathogenic components in multiple autoimmune diseases, while their role in human type 1 diabetes (T1D), a disease that progresses sequentially through identifiable stages prior to the clinical onset, is not well understood. We previously reported that the number of circulating neutrophils is reduced in patients with T1D and in presymptomatic at-risk subjects. The aim of the present work was to identify possible changes in circulating and pancreas-residing neutrophils throughout the disease course to better elucidate neutrophil involvement in human T1D. METHODS. Data collected from 389 subjects at risk of developing T1D, and enrolled in 4 distinct studies performed by TrialNet, were analyzed with comprehensive statistical approaches to determine whether the number of circulating neutrophils correlates with pancreas function. To obtain a broad analysis of pancreas-infiltrating neutrophils throughout all disease stages, pancreas sections collected worldwide from 4 different cohorts (i.e., nPOD, DiViD, Siena, and Exeter) were analyzed by immunohistochemistry and immunofluorescence. Finally, circulating neutrophils were purified from unrelated nondiabetic subjects and donors at various T1D stages and their transcriptomic signature was determined by RNA sequencing. RESULTS. Here, we show that the decline in β cell function is greatest in individuals with the lowest peripheral neutrophil numbers. Neutrophils infiltrate the pancreas prior to the onset of symptoms and they continue to do so as the disease progresses. Of interest, a fraction of these pancreasinfiltrating neutrophils also extrudes neutrophil extracellular traps (NETs), suggesting a tissue-specific pathogenic role. Whole-transcriptome analysis of purified blood neutrophils revealed a unique molecular signature that is distinguished by an overabundance of IFN-associated genes; despite being healthy, said signature is already present in T1D-autoantibody-negative at-risk subjects. CONCLUSIONS. These results reveal an unexpected abnormality in neutrophil disposition both in the circulation and in the pancreas of presymptomatic and symptomatic T1D subjects, implying that targeting neutrophils might represent a previously unrecognized therapeutic modality

Lack of the protein tyrosine phosphatase PTPN22 strengthens transplant tolerance to pancreatic islets in mice

Aims/hypothesis: Protein tyrosine phosphatase non-receptor 22 (PTPN22) plays a central role in T cell, B cell and innate immune cell signalling. A genetic variation in Ptpn22 is considered a major risk factor for the development of type 1 diabetes and has been the subject of extensive study. While several reports have addressed how Ptpn22 might predispose to autoimmunity, its involvement in other immune-mediated diseases, such as allograft rejection, has not been explored. Methods: To address a possible function for Ptpn22 in allograft rejection, we used a mouse model of pancreatic islet transplantation. We performed transplant tolerance experiments and determined how PTPN22 shapes tolerance induction and maintenance. Results: Ptpn22 12/ 12 recipient mice generate higher numbers of alloreactive T cells after allogeneic pancreatic islet transplantation compared with wild-type (WT) mice, but reject grafts with similar kinetics. This is not only due to their well-documented increase in forkhead box protein P3 (FOXP3)+ T regulatory (Treg) cells but also to the expansion of T regulatory type 1 (Tr1) cells caused by the lack of PTPN22. In addition, a tolerogenic treatment known to induce transplant tolerance in WT mice via Tr1 cell generation is more effective in Ptpn22 12/ 12 mice as a consequence of boosting both Tr1 and FOXP3+ Treg cells. Conclusions/interpretation: A lack of PTPN22 strengthens transplant tolerance to pancreatic islets by expanding both FOXP3+ Treg and Tr1 cells. These data suggest that targeting PTPN22 could serve to boost transplant tolerance

MOESM8 of Generation of donor-specific Tr1 cells to be used after kidney transplantation and definition of the timing of their in vivo infusion in the presence of immunosuppression

Additional file 8. Tr1 cell sorting gating strategy