Nlrp6-dependent sentinel goblet cell functions dictate defensive responses during bacterial invasion of colonic crypts

Abstract

The intestinal mucus layer serves as the primary physical barrier against microbial invasion, shielding the epithelium from luminal pathogens and inflammatory insults. This barrier is maintained by a heterogeneous population of goblet cells (GCs), which secrete regionally and organizationally distinct mucus layers. However, when this primary barrier is compromised, the burden of defense likely shifts to secondary mechanisms that remain incompletely defined. Therefore, we aimed to investigate the proposed role of microbe-sensing sentinel goblet cells (senGCs) as a secondary defensive mechanism that becomes critical when the primary mucus barrier fails, focusing on their capacity to mount localized secretory responses and preserve crypt sterility under challenge conditions. Using a GC specific Nlrp6 knockout model (Nlrp6{Delta}GC), we demonstrate that senGC deficiency leads to increased susceptibility to DSS induced colitis and Citrobacter rodentium infection, marked by exacerbated inflammation and enhanced crypt invasion respectively. Transcriptomic and immunolgical profiling revealed both common and sex-specific immune dysregulation, with especially female Nlrp6{Delta}GC mice exhibiting heightened mucosal pathogen burden, reduced Th17 expansion and increased CD8 T cell recruitment. The senGC-deficient mice also showed diminished baseline mucus secretion and accelerated GC loss during infection, suggesting a previously unrecognized mucus maintenance role for senGCs. Furthermore, infection induced expansion of Nlrp6 GCs in wild-type mice, enhancing MAMP-triggered mucus secretion, a response that is absent in Nlrp6{Delta}GC tissue. These findings confirm senGCs as an important regulator of epithelial protection by integrating GC-intrinsic microbial sensing with mucosal defense.