IL‐36γ and IL‐36Ra Reciprocally Regulate Colon Inflammation and Tumorigenesis by Modulating the Cell–Matrix Adhesion Network and Wnt Signaling

Abstract Inflammatory bowel disease and colorectal cancer are associated with dysregulation of cytokine networks. However, it is challenging to target cytokines for effective intervention because of the overlapping functions and unpredictable interactions of cytokines in such diverse networks. Here, it is shown that IL‐36γ and IL‐36Ra, an agonist and an antagonist for IL‐36R signaling respectively, reciprocally regulate the experimental colitis and the colon cancer development in mice. Knockout or neutralization of IL‐36γ alleviates dextran sulfate sodium (DSS)‐induced colitis and inhibits colon cancer development, whereas knockout of IL‐36Ra exacerbates DSS‐induced colitis and promotes colonic tumorigenesis in multiple colon cancer models in mice. Mechanistically, IL‐36γ upregulates extracellular matrix and cell–matrix adhesion molecules and facilitates Wnt signaling, which is mitigated by IL‐36Ra or IL‐36γ neutralizing antibody. Consistently, IL‐36γ levels are positively correlated with extracellular matrix levels and β‐catenin levels in human colorectal tumor biopsies. These findings suggest the critical role of IL‐36γ and IL‐36Ra in gut inflammation and tumorigenesis and indicate that targeting the IL‐36γ/IL‐36Ra signal balance provides potential therapeutic strategy for inflammatory bowel disease and gastrointestinal cancers.

(D) IHC analysis of IL-36g (upper) or IL-36Ra (lower) in the colons from the indicated bone marrow chimeric mice after colitis induction.
(G) qRT-PCR of Il1f9 in the colon tumors versus the normal colon tissues from the AOM/DSS (n=8 for normal or tumor, respectively), AOM/VP (n=12 for normal or tumor, respectively) or Apc Min/+ mice (n=12 for normal or tumor, respectively).
(H) Images (left) and quantification analysis (right) of IHC with anti-IL-36g in human CRC biopsies and the adjacent normal colon tissues (n=36).
Graphs show mean  SEM. Two-tailed student's t-test. Scale bars represent 0.4 mm (H). Data are combined two (A, C) or three (B, D) independent experiments or representative of two independent experiments (G). Cytokine-cytokine Chemokine Serpina3n Il1b 1000   (A) KEGG pathway enrichment analysis of the transcriptome of colon tissues from Il1f9 +/+ (n=2) and Il1f9 -/-(n=2) mice that were given 2.5% DSS in drinking water for 5 d, followed by normal drinking water for another 2 d (left) or from Il1f5 +/+ (n=3) and Il1f5 -/-(n=3) mice that were given 2% DSS in drinking water for 5 d, followed by normal drinking water for another 2 d (right).
(C) Images of HE stained colon sections from the mice treated as in (A).
(D) qRT-PCR analysis of the indicated genes in the colon tissues of the mice treated as in (A) (n=12 for PBS and z-API groups).
(E) A scheme of DSS and z-API treatment (upper) and body weight change (lower) of Il1f9 -/mice that were fed with 3% DSS for 7 d followed by normal sterile water for 2 d and were intraperitoneally injected with PBS (n=6 mice) or z-API (100 mg) per mouse (n=6 mice) every day for seven successive days.