Abstract O.24: Gut Microflora Influences Pathology in the Kawasaki Disease Vasculitis Mouse Model

Abstract

Background: Kawasaki Disease (KD) is the leading cause of acquired heart disease in the US. We have demonstrated the critical role of innate immune responses via IL-1R/MyD88 signaling in the Lactobacillus casei cell wall extract (LCWE)-induced KD mouse model. The diversity and composition of microflora (both bacterial and fungal) have been associated with the regulation and alterations of immune responses and various pathologies. However, the role of gut microbiota in immunopathology of KD has not been investigated. Objective: To evaluate the role of gut microflora in development of coronary arteritis, and vascular abnormalities in KD mouse model. Methods and Results: We investigated the role of gut microflora in the LCWE-induced KD mouse model, using Specific-Pathogen Free (SPF) and Germ Free (GF) mice (C57BL/6). GF mice showed a significant decrease of KD lesions, including coronary arteritis compared with SPF mice. The development of LCWE-induced AAA, which we recently discovered in this mouse model, was also markedly diminished in GF mice. In addition to GF mice, we also investigated the specific role of commensal fungi, and determined whether altered fungal burden in this KD mouse model contributes to disease severity. To deplete fungi in the gut microflora, we exposed pregnant SPF mice and their offspring to fluconazole (antifungal) in their drinking water for 5 wks and induced KD. The fluconazole treated mice had significantly reduced coronary arteritis, and AAA compared to controls. Since Dectin-1 has emerged as a key receptor that recognizes β-1,3-glucans found in the cell wall of nearly all fungi, we next induced KD in Dectin-1 deficient mice. Dectin-1 deficient mice also had significantly reduced KD lesions such as coronary arteritis compared with WT mice. Conclusions: We demonstrate here that gut microflora play a critical role in the development of KD vasculitis in LCWE-induced mouse model. Our results suggest that fungi in the intestinal microbiota may specifically control the induction and severity of KD vasculitis, which may be mediated by Dectin-1. These findings provide a new perspective on the potential role of the microbiome in KD pathogenesis and may offer new diagnostic and therapeutic strategies for KD patients.