(DCP010) EXPLORING THE IMPACT OF ANTI-CD3 IMMUNOTHERAPY ON BETA CELL STRESS IN TYPE 1 DIABETES

Background: For the past century, insulin has been the only Federal Drug Administration (FDA) approved treatment for the type 1 diabetes (T1D). However, in November 2022, Teplizumab, an anti-CD3 immunotherapy, received FDA approval for delaying the onset of T1D. Studies have shown that patients with the worst beta cell function had the most benefit from Teplizumab. It is clear Teplizumab is not just stopping beta cell death, but rather improving beta cell function, possibly by limiting stress-induced programs, such as senescence. We hypothesize that Teplizumab’s effects in the progression of T1D may be related to reducing the accumulation of senescent beta cells, which can adversely affect beta cell function.

METHODS AND RESULTS: Euglycemic female non-obese diabetic (NOD) mice were treated with anti-CD3 monoclonal antibodies or IgG controls once per week from 9-13 weeks of age. Intraperitoneal glucose tolerance tests (IPGTTs) were conducted to assess beta cell function prior to isolation of whole pancreas or pancreatic islets. Senescent beta cell frequency, senescence genes, and senescence associated secretory phenotype (SASP) were measured using immunohistochemistry (IHC), RT-qPCR, and Luminex, respectively. The anti-CD3 treatment was validated using flow cytometry on splenocytes from each mouse. Additionally, a positive control treatment using ABT-199, a selective Bcl-2 inhibitor, will be used to validate senescent beta cell depletion.
A statistically significant modulation of total CD3+ T cells (p=0.0020) and antigen specific CD8+ T cells (p=0.0047) was observed in the anti-CD3 treated mice compared to IgG mice. IHC staining revealed differences in insulin+ stained area in anti-CD3 treated mice compared to IgG mice. RT-qPCR data showed changes in senescent gene expression in anti-CD3 treated mice and Luminex results suggest that the anti-CD3 treated mice may exhibit a lower average secretion of SASP compared to the IgG mice.

Conclusion: Our findings suggest that treatment of NOD mice with anti-CD3 antibodies at the pre-diabetic stage and the resultant modulation of CD3+ T cells may coincide, at least in part, with changes in SASP factor secretion and senescent gene expression. These findings raise interesting questions about the potential interplay between T cell depletion, beta cell function, and beta cell senescence/SASP, while offering exciting avenues to further investigate the relationship between these factors.