Abstract Mucosal healing following inflammatory injury is poorly understood and often neglected, despite being the best indicator of long-term outcomes in inflammatory bowel diseases. We report here that the enigmatic small molecular weight heat shock protein, Hsp25 (the human form is Hsp27), plays a vital role in converging microbial and host factors to promote pSTAT3-mediated mucosal healing. In wild type mice, the proximal-to-distal gradient of intestinal epithelial cell (IEC) Hsp25 expression is dependent on microbial cues. Patients with left-sided ulcerative colitis, however, show reduced levels of Hsp27 expression in both uninvolved and involved areas compared to normal colons of non-IBD patients. In mice with global or IEC-specific Hsp25 gene-targeted deletion, impaired mucosal healing with development of hallmarks of chronic disease are observed following DSS-induced or TNBS-induced colitis, whereas mucosal restitution is accelerated in IEC-specific overexpressing Hsp25 transgenic mice. In colonic IECs derived from these murine lines, Hsp25 binds and stabilizes a phospho-STAT3/YAP nuclear complex stimulated by IL-22 to sustain its wound healing gene programming. Thus, our findings provide insight into the mechanism of action of IEC Hsp25/27 in integrating host and microbial drivers of mucosal restitution, which can be leveraged to develop novel approaches for achieving and maintaining remission in complex immune disorders like IBD.

Intestinal Epithelial Heat Shock Protein 25/27 integrates host and microbial drivers of mucosal restitution following inflammatory injury