15-deoxyspergualin prevents mucosal injury by inhibiting production of TNF-α and down-regulating expression of MD-1 in a murine model of TNBS-induced colitis

The pro-inflammatory cytokine TNF-α inhibits lymphatic pumping via activation of the NF-κB-iNOS signaling pathway

OBJECTIVE

Mesenteric lymphatic vessel pumping, important to propel lymph and immune cells from the intestinal interstitium to the mesenteric lymph nodes, is compromised during intestinal inflammation. The objective of this study was to test the hypothesis that the pro-inflammatory cytokine TNF-α, is a significant contributor to the inflammation-induced lymphatic contractile dysfunction, and to determine its mode of action.

METHODS

Contractile parameters were obtained from isolated rat mesenteric lymphatic vessels mounted on a pressure myograph after 24-hours incubation with or without TNF-α. Various inhibitors were administered, and quantitative real-time PCR, Western blotting, and immunofluorescence confocal imaging were applied to characterize the mechanisms involved in TNF-α actions.

RESULTS

Vessel contraction frequency was significantly decreased after TNF-α treatment and could be restored by selective inhibition of NF-кB, iNOS, guanylate cyclase, and ATP-sensitive K⁺ channels. We further demonstrated that NF-кB inhibition also suppressed the significant increase in iNOS mRNA observed in TNF-α-treated lymphatic vessels and that TNF-α treatment favored the nuclear translocation of the p65 NF-κB subunit.

CONCLUSIONS

These findings suggest that TNF-α decreases mesenteric lymphatic contractility by activating the NF-κB-iNOS signaling pathway. This mechanism could contribute to the alteration of lymphatic pumping reported in intestinal inflammation.

Encenicline, an α7 Nicotinic Acetylcholine Receptor Partial Agonist, Reduces Immune Cell Infiltration in the Colon and Improves Experimental Colitis in Mice

The α7 pentamer nicotinic acetylcholine receptors (nAChRs) are a target in transduction of anti-inflammatory signals from the central nervous system to the gastrointestinal (GI) tract. The aim of this study was to investigate the anti-inflammatory action of the novel α7 nAChR partial agonist encenicline and to determine the mechanism underlying its activity. Anti-inflammatory activity of encenicline was evaluated using trinitrobenzenesulfonic acid (TNBS)- and dextran sulfate sodium (DSS)-induced models of colitis. Macroscopic score, ulcer score, colon length and thickness, as well as myeloperoxidase (MPO) activity were recorded. Immunohistochemistry (IHC) was used to measure the infiltration of immune cells in the colon. Furthermore, we employed flow cytometry to determine the effect of encenicline on frequencies of FoxP3(+) and interleukin (IL)-17A(+) T cells in the mouse colon. Encenicline attenuated TNBS- and DSS-induced colitis in mice via α7 nAChRs, as indicated by significantly reduced macroscopic parameters and MPO activity. Treatment with encenicline significantly reduced the infiltration of macrophages, neutrophils, and B cells in the colon of TNBS-treated animals, as indicated by IHC. In the TNBS model encenicline reduced the frequency of FoxP3(+) IL-17A(+) T cells in the colon. In the DSS-model treatment encenicline increased the frequency of FoxP3(+) T cells and reduced IL-17A(+) T cells. Stimulation of α7 nAChR with partial agonist encenicline alleviates colitis via alteration of the number and/or activation status of the immune cells in the gut, emphasizing a potential role of α7 nAChRs as a target for anticolitic drugs.

Inhibitory effects of Geijigajakyak-Tang on trinitrobenzene sulfonic acid-induced colitis

AIM OF THE STUDY

Water extract of Geijigajakyak-Tang (GJT) consisting of five crude drugs [dried root of P. lactiflora Peony (Paeoniaceae), dried trunk bark of C. cassia Blume (Lauraceae), seed of Z. jujube var. inermis Mill (Rhamnaceae), fresh root of Z. officinale Rocoe (Zingiberaceae) and dried trunk bark of G. uralensis Fish (Leguminosae)] is a folk medicine used for the treatment of chronic colitis. This study was designed to further elucidate the effect of GJT on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats.

MATERIALS AND METHODS

GJT orally given to mice before and after TNBS intoxication, and their clinical and morphological changes, myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels in colon tissues, were evaluated on Day 8 post-TNBS. Furthermore, the effect of six major constituents of individual herbs on ileum smooth muscle contraction and neutrophil chemotaxis was studied.

RESULTS

GJT had a significant anti-inflammatory effect based on clinical and morphologic changes, MPO activity and MDA levels in colon tissues as compared with sham control. GJT and 5 major active constituents of individual herbs, paeoniflorin, cinnamaldehyde, jujuboside A, jujubogenin, and diammonium glycyrhhizinate significantly inhibited neutrophil chemotaxis. GJT significantly inhibited muscle contraction (IC(50); 2.10 +/- 0.11 mg/ml), and 1,8-cineol has the most spasmolytic activity (IC(50); 0.10 +/- 0.03 mg/ml).

CONCLUSION

GJT has significant anti-inflammatory effects on TNBS-induced colitis via inhibitions of smooth muscle contraction and neutrophil chemotaxis.