Smooth muscle is an essential component of the intestine, both to maintain its structure and produce peristaltic and segmentation movements. However, very little is known about other putative roles that smooth muscle cells may have. Here, we show that smooth muscle cells may be the dominant suppliers of BMP antagonists, which are niche factors essential for intestinal stem cell maintenance. Furthermore, muscle-derived factors render epithelium reparative and fetal-like, which includes heightened YAP activity. Mechanistically, we find that the membrane-bound matrix metalloproteinase MMP17, which is exclusively expressed by smooth muscle cells, is required for intestinal epithelial repair after inflammation- or irradiation-induced injury. Furthermore, we propose that MMP17 affects intestinal epithelial reprogramming after damage indirectly by cleaving diffusible factor(s) such as the matricellular protein PERIOSTIN. Together, we identify an important signaling axis that establishes a role for smooth muscle cells as modulators of intestinal epithelial regeneration and the intestinal stem cell niche.

The intestinal tract is a common site for various types of infections including viruses, bacteria, and helminths, each requiring specific modes of immune defense. The intestinal epithelium has a pivotal role in both immune initiation and effector stages, which are coordinated by lymphocyte cytokines such as IFNγ, IL-13, and IL-22. Here, we studied intestinal epithelial immune responses using organoid image analysis based on a convolutional neural network, transcriptomic analysis, and in vivo infection models. We found that IL-13 and IL-22 both induce genes associated with goblet cells, but the resulting goblet cell phenotypes are dichotomous. Moreover, only IL-13–driven goblet cells are associated with classical NOTCH signaling. We further showed that IL-13 induces the bone morphogenetic protein (BMP) pathway, which acts in a negative feedback loop on immune type 2–driven tuft cell hyperplasia. This is associated with inhibiting Sox4 expression to putatively limit the tuft cell progenitor population. Blocking ALK2, a BMP receptor, with the inhibitor dorsomorphin homolog 1 (DMH1) interrupted the feedback loop, resulting in greater tuft cell numbers both in vitro and in vivo after infection with Nippostrongylus brasiliensis . Together, this investigation of cytokine effector responses revealed an unexpected and critical role for the BMP pathway in regulating type 2 immunity, which can be exploited to tailor epithelial immune responses.

Highlights d Helminth infection promotes pathology to vaginal HSV-2 infectiond Promoted pathology is IL-5, IL-33 mediated but Il4ra independent d The enhanced vaginal epithelial ulceration is eosinophil driven

Infectious and inflammatory diseases in the intestine remain a serious threat for patients world-wide. Reprogramming of the intestinal epithelium towards a protective effector state is important to manage inflammation and immunity and can be therapeutically targeted. The role of epigenetic regulatory enzymes within these processes is not yet defined. Here, we use a mouse model that has an intestinal-epithelial specific deletion of the histone demethylase Lsd1 (cKO mice), which maintains the epithelium in a fixed reparative state. Challenge of cKO mice with bacteria-induced colitis or a helminth infection model both resulted in increased pathogenesis. Mechanistically, we discovered that LSD1 is important for goblet cell maturation and goblet-cell effector molecules such as RELMß. We propose that this may be in part mediated by directly controlling genes that facilitate cytoskeletal organization, which is important in goblet cell biology. This study therefore identifies intestinal-epithelial epigenetic regulation by LSD1 as a critical element in host protection from infection.

21 22 SUMMARY (~150 words) 23Smooth muscle is an essential component of the intestine, both to maintain its structure and 24 produce peristaltic and segmentation movements. However, very little is known about other 25 putative roles that smooth muscle may have. Here, we show that smooth muscle is the 26 dominant supplier of BMP antagonists, which are niche factors that are essential for 27intestinal stem cell maintenance. Furthermore, muscle-derived factors can render epithelium 28 reparative and fetal-like, which includes heightened YAP activity. Mechanistically, we find 29 that the matrix metalloproteinase MMP17, which is exclusively expressed by smooth muscle, 30 is required for intestinal epithelial repair after inflammation-or irradiation-induced injury. 31Furthermore, we provide evidence that MMP17 affects intestinal epithelial reprogramming 32 indirectly by cleaving the matricellular protein PERIOSTIN, which itself is able to activate 33 YAP. Together, we identify an important signaling axis that firmly establishes a role for 34 smooth muscle as a modulator of intestinal epithelial regeneration and the intestinal stem 35 cell niche. 36 37