Loss of NLRP6 expression increases the severity of intestinal injury after syngeneic hematopoietic stem cell transplantation

NLRP6 plays a crucial role in maintaining intestinal homeostasis by regulating the interaction between the intestinal mucosa and the microbiota. However, the impact of NLRP6 deficiency on intestinal damage following hematopoietic stem cell transplantation (HSCT) remains poorly understood. In this study, we established a syngeneic HSCT mouse model using C57BL/6 mice as donors and NLRP6-/- or C57BL/6 mice as recipients. Our findings revealed that NLRP6 deficiency had minimal influence on peripheral blood cell counts and splenic immune cell proportions in transplanted mice. However, it exacerbated pathological changes in the small intestine on day 14 post-transplantation, accompanied by increased proportions of macrophages, dendritic cells, and neutrophils. Furthermore, the NLRP6 deficiency resulted in elevated expression of MPO and CD11b, while reducing the levels mature caspase-1 and mature IL-1β in the intestine. Moreover, the NLRP6 deficiency disturbed the expression of apoptosis-related molecules and decreased the tight junction protein occludin. Notably, recipient mice with NLRP6 deficiency exhibited lower mRNA expression levels of antimicrobial genes, such as Reg3γ and Pla2g2a. The short-term increase in inflammatory cell infiltration caused by NLRP6 deficiency was associated with intestinal damage, increased apoptosis, reduced expression of antimicrobial peptides, and impaired intestinal repair. Taken together, our findings demonstrate that the loss of NLRP6 exacerbates post-transplantation intestinal damage in recipient mice.