Prohibitin is Upregulated on Donor T cells in Murine Acute Graft-versus-Host Disease and Promotes Th17 Response

Abstract

Abstract Introduction: Acute graft-versus-host disease (GVHD) is a T cell-mediated disorder and the main cause of non-relapse mortality in allogeneic hematopoietic cell transplantation recipients. Here, we investigate PHB in Th17-mediated inflammation and as a therapeutic target for acute GVHD. Methods: Irradiated mice received T cell depleted bone marrow cells and allogeneic or syngeneic splenocytes. At day 25 post-transplant, blood, spleen, liver, and colon were harvested and analyzed for surface PHB, IFNγ, and IL-17 on donor T cells by flow cytometry. Splenocytes were cultured in the presence of PHB pharmacological inhibitor rocaglamide (RocA) and analyzed for PHB and IL-17 expression in donor T cells. Naïve murine CD4 T cells were cultured in Th17 polarizing conditions with RocA. CRISPR/Cas9-mediated knockout of PHB was performed followed by evaluation of Il17a, Il17f, and Il22 gene expression by quantitative PCR. Results: Surface expression of PHB is increased in murine allogeneic donor T cells in liver, spleen, colon, and peripheral blood in acute GVHD. PHB-expressing splenic T cells secrete IL-17, which is reduced with treatment with a PHB inhibitor in ex vivo experiments. PHB inhibition of murine CD4 T cells in vitro impairs differentiation into the Th17 subtype resulting in reduced IL-17 secretion and downregulation of Il17a, Il17f, and Il22 genes. Knockout of PHB reduces transcription of Il17 and Il22 genes. Conclusions: These findings show relevancy of PHB in Th17-mediated inflammation and suggest a potential role for PHB in acute GVHD. To our knowledge, this study is the first to investigate PHB in acute GVHD, and our findings will offer greater support for clinical use of PHB inhibition to treat this fatal disease. Supported by grants from AAI (KS, PR), ACS (PR; RSG-22-053-01-IBCD), and NIH NCI (PR; R01 CA252469).