The Association Between IL-23/Th17Pathway Gene And Inflammatory Bowel Diseases

Part I The intestinal and systemic expression levels of Interleukin-23/T-helper17pathway in Chinese patients withinflammatory bowel diseaseBackground Interleukin-23/T-helper17(IL-23/Th17) pathway shows a key effect in the pathogenesis of inflammatory bowel disease (IBD), but little is known about its expression in Chinese Han population. We aim to evaluate the local (intestinal mucosal) and systemic (peripheral blood) expression of IL-23/Th17pathway associated genes and genotype-phenotype effect in IBD patients.Methods Unrelated118Chinese patients with ulcerative colitis (UC),30patients with Crohn’s disease (CD) and93healthy controls were studied. The levels of IL-12p40, Tumor necrosis factor-like cytokine1A (TL1A), Janus kinase2(JAK2) and Interleukin-23receptor (IL-23R) mRNA were measured using real-time polymerase chain reaction (PCR) in colon tissues. Serum IL-12p40and TL1A expression was measured by enzyme-linked immunosorbent assay (ELISA). Western blot analysis was performed to determine the JAK2and IL-23R protein expression.Results The mRNA levels of IL-12p40and TL1A was increased in UC patients (P<0.001). Serum IL-12p40and TL1A levels were higher in active UC patients, particularly in patients with disease course less than1.25years or initial onset (P<0.05). No association was found between the genotype and serum IL-12p40or TL1A expression in UC patients (P>0.05). Meanwhile, the mRNA and protein expression of JAK2and IL-23R was increased in IBD patients (P<0.05).Conclusions The mRNA and protein levels of IL-23/Th17pathway genes were aberrant both locally and systemically in IBD patients. Serum IL-12p40and TL1A expression had no significant association with the IL-12B and TNF superfamily member15(TNFSF15) gene polymorphism, but was highly expressed in the early onset and active condition of UC patients. Part II Amelioration of DSS-induced colitis by SR1001and matrine treatment through inhibition of Thl and IL-23/Th17pathwayBackground SRI001is a high-affinity synthetic ligand to retinoic acid-related orphan receptor gamma t (RORyt) and matrine is aquinolizidine alkaloid that is widely used in ancient China. They have been demonstrated to suppress the clinical severity of autoimmune disease in mice through the inhibition of Thl and IL-23/Th17pathway function. However, their effects on inflammatory bowel disease (IBD), which pathogenesis related with dysregulation of mucosal immunity, genetic susceptibility and dysbiosis of intestinal bacteria remain unknown. In the present study, we investigated the effects of matrine and SRI001on intestinal inflammation and IL-23/Thl7pathway in dextran sodium sulfate (DSS)-induced colitis in mice.Mehtods We established DSS-induced colitis in mouse model and assessed the weight, DAI value, length of colon and histological score after matrine and SRI001treatments. The mRNA expression of T-bet, Gata-3, Foxp3, IL-17, IL-23R, JAK2, Signal transducer and activator of transcription3(STAT3) and IL-22was detected by real-time PCR in colonic mucosa and spleen. Protein levels of IL-17, IL-23R, RORyt, JAK2, p-JAK2, STAT3and p-STAT3were further measured by ELISA and western blot, respectively.Results The results indicate SRI001and matrine might be efficacious anti-inflammatory drugs. We find that SR1001and matrine could improve the weight loss, DAI value, colon length and histological score in a dose-dependent manner. Additionally, we demonstrate that SR1001and matrine reduce the mRNA expression of T-bet, IL-17, IL-23R and JAK2in colonic mucosa, and IL-22in spleen. The serum levels of IL-17could be inhibited by SR1001only. Furthermore, our data verifies that SRI001and matrine could suppress the protein levels of IL-23R, RORyt, JAK2and activity of p-JAK2, p-STAT3, which play important roles in IL-23/Th17pathway.Conclusions Taken together, the results provide evidence that matrine and SR1001improve DSS-induced colitis by regulating the mRNA and protein levels of Thl and IL-23/Thl7pathway genes, and thus may serve as novel and efficient candidate agents for IBD treatment.