John Nguyen

Introduction: Type 1 diabetes mellitus, T1D, involves the autoimmune destruction of insulin producing pancreatic β cells⁵. In the U.S., 3 million individuals, or 3% of the population are affected with 78,000 youths diagnosed annually¹. T1d affects glucose, lipid, and protein metabolism, leading to polyuria, polydipsia, hyperglycemia, and ketonuria¹. Genetic components for T1D includes HLA gene substitution mutations on chromosome 6 coding MHC as well as insulin polymorphism⁵. Autoreactive CD4+ effector T (Teff) lymphocytes become activated by insulin peptide presentation; the HLA-DQB1*0302 allele translates a DQ8 protein in MHC class II β-chain that presents insulin B:9-23 epitope^4,8. T1D couples this autoreactivity with deficient regulator T (Treg) cell activity⁶. Non-FcR-binding anti-cd3 antibody therapy reduces the number of autoreactive Teff cells without diminishing the number of FOXP3+ Treg cells^2,7,8. Methods: Anti-PD-L1 antibody injections were used to assess PD-1 levels in non-obese diabetic (NOD) mice, and Th1 differentiation was conducted to assess in vitro for IFN-γ. In vivo proliferation of target Teff cells in these NOD mice was observed via CFSE staining. Co-culture with bone-marrow-derived dendritic cells (BMDC) was used to assess CD80 expression. ELISA for cytokine analysis, flow cytometry for FOXP3 detection, and immunofluorescence for GLUT1 detection were also used. Different T lymphocytes as well as their markers (CD3, CD4, CD8, FOXP3, PD-1, etc.) were assessed by flow cytometry from human subjects in a 2-year clinical trial. Anti-drug antibodies were assessed in these human subjects using ELISA. Results: Non-FcR binding anti-CD3 therapy decreases CD3+ T lymphocytes, including both CD4+ and CD8+ T cells^2,3,7. While CD4+ T cells remained diminished, CD8+ and natural killer (NK) T cells recovered in number³. The number and activity of autoreactive Teff cells were markedly reduced. A reduced production of pro-inflammatory signals IFN-γ, IL-12, IL-7, and CD80 were observed in Teff cells after anti-CD3 antibody injection/therapy^2,3,7. Treated Teffs also showed greater expression of programmed cell death protein, PD-1 as well as reduced expression of GLUT1, contributing to their diminished number^3,7. These effects were not observed in Foxp3+ Treg cells⁷. Conclusion: Non-TcR binding anti-CD3 antibody therapy is a promising treatment method for T1D. It works by reducing inflammation and pathogenicity brought on by autoreactive Teff cells while maintaining the protective functions of Treg cells. In doing so, anti-CD3 antibody therapy provides a treatment to T1D at the most basic level. This cellular approach to treating T1D gives rise to multiple systemic benefits to patients.

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