Heeger, P. S. | Search bioRxiv

bioRxiv2024

Butyrophilin 2A2 promotes T cell immunoregulation by enhancing CD45 phosphatase activity within the immune synapse

B7 costimulatory family member Butyrophilin 2A2 (BTN2A2) is predominantly expressed by antigen presenting cells and regulates T cell immunity, but molecular mechanisms are unclear. Using immunoblots analyzing TCR-initiated signaling intermediaries, co-immunoprecipitation studies, confocal microscopy, structural modeling-guided mutational analyses, and microscale thermophoresis, we demonstrate that BTN2A2 directly interacts with CD45RO, resulting in CD45 retention within the immune synapse during TCR activation. Recombinant BTN2A2 increased murine CD4+Foxp3+ regulatory T cells (Treg) and reduced T helper 17 (Th17) cells in vitro through mechanisms dependent on CD45 phosphatase activity. BTN2A2 treatment reduced clinical expression of two murine autoimmune disease models and increased Treg/Th17 ratios. Analyses of BTN2A2-deficient animals showed exacerbated disease associated with reduced Treg/Th17 ratios. Addition of BTN2A2 to human mixed lymphocyte responses similarly enhanced human Treg and suppressed Th17 cells and was CD45 phosphatase dependent. Together, our studies identify BTN2A2 as a physiological CD45RO ligand that enhances CD45 phosphatase activity in murine and human T cells, providing mechanisms for BTN2A2-mediated amelioration of autoimmunity. SummaryButyrophilin 2A2 ameliorates autoimmunity by binding to CD45RO on activated T cell surfaces leading to dampened TCR signaling which in turn leads to expansion of T regulatory cells and reduction of Th17 differentiation.

immunology↗

bioRxiv2024

Compartmentalization of Transcripts During Antibody Mediated Rejection in Renal Transplants

We used Digital Spatial Profiling to localize transcripts in glomeruli and tubulointerstitial compartments in a series of 4 biopsies from a patient diagnosed with acute antibody-mediated rejection (AMR). The 4 biopsies included: a baseline protocol biopsy 25 days after transplantation; a 3 month biopsy diagnosed as acute AMR; a biopsy 4 months after treatment with intravenous immunoglobulin (IVIg) showing ongoing AMR with a mild increase in tubulointerstitial fibrosis; and a biopsy 7 months later with resolution of glomerulitis. Glomeruli were captured in regions of interest (ROIs) for whole exome sequencing. Compared to baseline glomeruli, 17 transcripts were increased and 39 decreased in the 3 subsequent biopsies (> 2-fold and p < 0.005). Increased signatures for macrophages correlated with increased numbers of CD68 positive cells imaged in the corresponding glomeruli. The Human Cell Atlas classified the 39 transcripts decreased during the initial rejection as characteristic of podocytes and this gene signature did not recover in the subsequent 2 biopsies. Additional ROIs encompassing areas of tubulointerstitial fibrosis disclosed signatures for memory B cells in the acute AMR sample. Treatment with IVIg did not eliminate the B cell signal in the subsequent biopsy. Collectively these data demonstrate a compartmentalization of injury processes. Innate immune cells including macrophages were located in glomerular and tubulointerstitial compartments, whereas, adaptive immune cells including memory B cells localized to the tubulointerstitial compartment. Furthermore, podocyte transcripts were decreased in glomeruli and did not recover with treatment indicating a vulnerability of these cells to acute AMR.

pathology↗