Inflammasome Blockade Prevents Severe Acute Graft-Versus-Host Disease after Allogeneic Stem Cell Transplantation: Evidence from Murine Allogeneic Transplant Models

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains a curative therapy for high-risk hematologic malignancies; however, acute graft-versus-host disease (aGVHD) continues to limit its clinical benefits associated with morbidity and mortality. Acute GVHD (aGVHD) occurs when donor-derived immune cells attack host tissues. A gastrointestinal (GI) aGVHD (GI aGVHD) accounts for 30%-50% GVHD, characterized by epithelial barrier disruption, inflammatory cytokine release, immune cell infiltration, and apoptosis. We investigated the involvement of the inflammasome in activating inflammatory pathways, and its inhibitor Kamuvudine-9 (K-9) in the GI aGVHD murine model. The inhibition of inflammasomes may be beneficial in mitigating GI aGVHD mediated by altering cellular/cytokine functions. As a potential therapeutic approach, targeting the inflammasome by using Kamuvidine-9 (K-9) may be therapeutically achievable and beneficial with disease prognosis. B6D2F1/J mice received total body irradiation of 1200cGy and infusion of 5*10 6 bone marrow and 6*10 6 splenocytes of syngeneic (B6D2F1/J) or allogeneic (C57BL/6) mice. Recipient mice were orally administered with K-9 or vehicle control daily twice until day +7. Clinical GVHD scores, survival, histopathology, serum cytokine levels, and cellular and molecular markers were evaluated to portray the mechanistic effects of K-9 and its pathophysiology. When compared to allogeneic controls, K-9 treatments showed a significant reduction in clinical GVHD (p<0.0001), organ pathology of small intestine (p=0.0060), gut (p=0.0116) and serum tumor necrosis factor levels (p=0.0038). Tight junction protein expressions were significantly increased (claudin-1 (p=0.0007), zona occludin-1 (p=0.0030) and occludin (p<0.0001)) in the K-9 treated animals. A reduced T lymphocyte and neutrophil cell population also validated the treatment of K-9 reduced the pro-inflammatory cell infiltration and thereby amelioration of the disease. Nevertheless, a decreased apoptotic cell (p<0.0001) and proliferation (p<0.0001) upon K-9 treatment, followed by an enhancement in mucosal recovery by restoring goblet cells, also correlated with K-9 efficacy in GI injury models. The treatment with K-9 resulted in improved epithelial barrier integrity, reduced pro-inflammatory cytokines and cells. The reduced apoptotic cell and proliferative potential suggest inflammasome inhibition and therapeutic potential of K-9 by protecting against GI injury in aGVHD pathophysiology. Subsequent investigations will focus on defining the transcriptional and metabolomic signatures that govern the therapeutic efficacy of K-9 in attenuating aGVHD pathogenesis.