<i>Clostridioides difficile</i> major toxins remodel the intestinal epithelia, affecting spore adherence/internalization into intestinal tissue and their association with gut vitronectin

Abstract

The most common cause of healthcare-associated diarrhea and colitis in the U.S., is <i>Clostridioides difficile</i>, a spore-forming pathogen. Two toxins, TcdA and TcdB, are major virulence factors essential for disease manifestations, while <i>C. difficile</i> spores are essential for disease transmission and recurrence. Both toxins cause major damage to the epithelial barrier, trigger massive inflammation, and reshape the microbiome and metabolic composition, facilitating <i>C. difficile</i> colonization. <i>C. difficile</i> spores, essential for transmission and recurrence of the disease, persist adhered and internalized in the intestinal epithelia. Studies have suggested that toxin-neutralization in combination with antibiotic during CDI treatment in humans significantly reduces disease recurrence, suggesting a link between toxin-mediated damage and spore persistence. Here, we show that TcdA/TcdB-intoxication of intestinal epithelial Caco-2 cells leads to remodeling of accessible levels of fibronectin (Fn) and vitronectin (Vn) and their cognate alpha-integrin subunits. While TcdB-intoxication of intestinal tissue had no impact in accessible levels of Fn and Vn, but significantly increased levels of intracellular Vn. We observed that Fn and Vn released to the supernatant readily bind to <i>C. difficile</i> spores <i>in vitro</i>, while TcdB-intoxication of intestinal tissue led to increased association of <i>C. difficile</i> spores with gut Vn. Toxin-intoxication of the intestinal tissue also contributes to increased adherence and internalization of <i>C. difficile</i> spores. However, TcdB-intoxicated ligated loops infected of mice treated with Bezlotoxumanb (monoclonal anti-TcdB antibodies) did not prevent TcdB-mediated increased spore adherence and internalization into intestinal tissue. This study highlights the importance of studying the impact of <i>C. difficile</i> toxins of host tissues has in <i>C. difficile</i> interaction with host surfaces that may contribute to increased persistence and disease recurrence.