IL-38 regulates intestinal stem cell homeostasis by inducing WNT signaling and beneficial IL-1beta secretion

Dinarello, A.; May, M.; Amo-Aparicio, J.; Azam, T.; Gaballa, J. M.; Marchetti, C.; Tesoriere, A.; Ghirardo, R.; Redzic, J. S.; Webber, W.; Atif, S. M.; Li, S.; Eisenmesser, E. Z.; de Graaf, D. M.; Dinarello, C. A.

doi:10.1101/2023.04.04.535251

bioRxiv · 10.1101/2023.04.04.535251

IL-38 regulates intestinal stem cell homeostasis by inducing WNT signaling and beneficial IL-1beta secretion

Dinarello, A.·May, M.·Amo-Aparicio, J.·Azam, T.·Gaballa, J. M.·Marchetti, C.·Tesoriere, A.·Ghirardo, R.·Redzic, J. S.·Webber, W.·Atif, S. M.·Li, S.·Eisenmesser, E. Z.·de Graaf, D. M.·Dinarello, C. A.

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Abstract

The IL-1 Family member IL-38 has been characterized primarily as an anti-inflammatory cytokine in human and mouse models of systemic diseases. Here, we examined the role of IL-38 in the murine small intestine (SI). Immunostaining of SI revealed that IL-38 expression partially confines to intestinal stem cells. Cultures of intestinal organoids reveal IL-38 functions as a growth factor by increasing organoid size via inducing WNT3a. In contrast, organoids from IL-38 deficient mice develop more slowly. This reduction in size is likely due to downregulation of intestinal stemness markers (i.e., Fzd5, Ephb2, Olfm4) expression compared with wild type organoids. IL-38 binding to IL-1R6 is postulated to recruit the co-receptor IL-1R9. Therefore, to analyze the molecular mechanisms of IL-38 signaling, we also examined organoids from IL-1R9 deficient mice. Unexpectedly, these organoids, although significantly smaller than wild type, respond to IL-38, suggesting that IL-1R9 is not involved in IL-38 signaling in the stem cell crypt. Nevertheless, silencing of IL-1R6 disabled the organoid response to the growth property of IL-38, thus suggesting IL-1R6 as the main receptor used by IL-38 in the crypt compartment. In organoids from wild type mice, IL-38 stimulation induced low concentrations of IL-1{beta} which contribute to organoid growth. However, high concentrations of IL-1{beta} have detrimental effects on the cultures that were prevented by treatment with recombinant IL-38. Overall, our data demonstrate an important regulatory function of IL-38 as a growth factor, and as an anti-inflammatory molecule in the SI, maintaining homeostasis. SignificanceThe IL-1 family member IL-38 has been characterized primarily as an anti-inflammatory cytokine for systemic diseases. Here we describe a fundamental role of IL-38 in driving intestinal stem cell differentiation through the upregulation of WNT3a and IL-1{beta}. Our findings reveal a dual role of IL-38 in regulating intestinal functions; (a) in resting conditions IL-38 maintains intestinal homeostasis, driving WNT3a production and organoid budding, whereas (b) in highly inflamed conditions, IL-38 contributes to proper recovery, by exerting anti-inflammatory activities. Thus, we demonstrate a pivotal role of IL-38 in driving tissue turnover and maintenance of homeostasis in intestinal health.

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Dinarello, A., May, M., Amo-Aparicio, J., Azam, T., Gaballa, J. M., Marchetti, C., Tesoriere, A., Ghirardo, R., Redzic, J. S., Webber, W., Atif, S. M., Li, S., Eisenmesser, E. Z., de Graaf, D. M., Dinarello, C. A.. 2023-04-04. IL-38 regulates intestinal stem cell homeostasis by inducing WNT signaling and beneficial IL-1beta secretion. https://doi.org/10.1101/2023.04.04.535251

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