Walker, L. S. K. | bioRxiv Science

bioRxiv2023

An IL-2 mutein increases IL-10 and CTLA-4-dependent suppression of dendritic cells by regulatory T cells

Interleukin-2 (IL-2) variants with increased CD25 dependence that selectively expand Foxp3+ regulatory T (TR) cells are in clinical trials for treating inflammatory diseases. Using an Fc-fused IL-2 mutein (Fc.IL-2 mutein) we developed that prevents diabetes in non-obese diabetic (NOD) mice, we show that Fc.IL-2 mutein induced an activated TR population with elevated proliferation, a transcriptional program associated with Stat5- and TCR-dependent gene modules, and high IL-10 and CTLA-4 expression. Increased IL-10 signaling limited surface MHC class II upregulation during conventional dendritic cell (cDC) maturation, while increased CTLA-4-dependent transendocytosis led to the transfer of CD80 and CD86 costimulatory ligands from maturing cDCs to TR cells. In NOD mice, Fc.IL-2 mutein treatment promoted the suppression of cDCs in the inflamed pancreas and pancreatic lymph nodes resulting in T cell anergy. Thus, IL-2 mutein-expanded TR cells have enhanced functional properties and restrict cDC function, offering promise for targeted immunotherapy use in autoimmune disease.

immunology↗

bioRxiv2017

Quantitative characterization of CTLA4 trafficking and turnover using a combined in vitro and in silico approach

CTLA4 is an essential negative regulator of T cell immune responses and is a key checkpoint regulating autoimmunity and anti-tumour immunity. Genetic mutations resulting in a quantitative defect in CTLA4 are associated with the development of an immune dysregulation syndrome. Endocytosis of CTLA4 is rapid and continuous with subsequent degradation or recycling. CTLA4 has two natural ligands, the surface transmembrane proteins CD80 and CD86 that are shared with the T cell co-stimulatory receptor CD28. Upon ligation with CD80/CD86, CTLA4 can remove these ligands from the opposing cells by transendocytosis. The efficiency of ligand removal is thought to be highly dependent on the processes involved in CTLA4 trafficking. With a combined in vitro-in silico study, we quantify the rates of CTLA4 internalization, recycling and degradation. We incorporate experimental data from cell lines and primary human T cells. Our model provides a framework for exploring the impact of altered affinity of natural ligands or therapeutic anti-CTLA4 antibodies and for predicting the effect of clinically relevant CTLA4 pathway mutations. The presented methodology for extracting trafficking rates can be transferred to the study of other transmembrane proteins.

immunology↗