Evaluation of the effects of peptide antibiotics human beta-defensins-1/-2 and LL-37 on histamine release and prostaglandin D(2) production from mast cells

Correlation between expression of human cathelicidin peptide LL-37 and colon inflammation in patients with ulcerative colitis

AIM: To investigate the expression of human cathelicidin LL-37 in the colon mucosa of patients suffering from ulcerative colitis and to assess its relationship with colon inflammation.

METHODS: Thirty-two patients with ulcerative colitis were included in the study. The severity of ulcerative colitis was assessed using the Ulcerative Colitis Disease Activity Index (UCDAI). The expression of LL-37 and cytokines (TNF-α, IL-1β and IL-4) in the colon mucosa was detected by real-time RT-PCR. Immunohistochemistry was used to investigate the location of the LL-37 peptide in the normal and inflamed colon mucosa. Colon epithelial cells were stimulated in vitro with cytokines to evaluate mechanisms that influence cathelicidin production.

RESULTS: The mRNA expression of LL-37 and cytokines in the colon mucosa was significantly elevated with the severity of disease activity in UC patients compared to controls (LL-37: 4.97 ± 6.95, 31.46 ± 10.74, 75.50 ± 13.19 vs 0.27 ± 0.45; TNF-α: 97.04 ± 23.74, 201.07 ± 33.46, 290.81 ± 30.45 vs 72.82 ± 18.85; IL-1β: 72.98 ± 38.03, 153.46 ± 22.68, 211.34 ± 25.12 vs 38.56 ± 10.38; IL-4: 26.04 ± 12.47, 46.38 ± 15.12, 46.94 ± 16.53 vs 19.34 ± 11.61, all P < 0.05). Significant correlations were found between the mRNA expression of LL-37 and cytokines (r = 0.965, 0.940, 0.628, all P < 0.01). Immunohistochemistry analysis showed that the LL-37 peptide was located in the colon epithelial surface in both normal controls and UC patients. In addition, the LL-37 peptide was detected easily in inflammatory cells infiltrating into the inflamed colon mucosa in UC patients. In vitro stimulation with cytokines did not up-regulate LL-37 expression in colon epithelial cells.

CONCLUSION: The up-regulation of LL-37 expression in inflamed colon mucosa of UC patients and high correlation between the expression of LL-37 and cytokines indicate a close relationship between LL-37 and immune inflammatory response in UC patients with ulcerative colitis; however, this process does not involve colonic epithelial cells.