Glial-derived neurotrophic factor regulates enteric mast cells and ameliorates dextran sulfate sodium-induced experimental colitis.

BACKGROUND & AIMS: Although interactions between enteric glial cells (EGCs) and enteric mast cells have been demonstrated to play an important role in the pathogenesis of inflammatory bowel disease (IBD), the exact mechanisms by which EGCs regulate enteric mast cells are still unknown. The aims of this study were to investigate whether glial-derived neurotrophic factor (GDNF), which has been confirmed to be produced mostly by EGCs, might regulate enteric mast cells and ameliorate dextran sulfate sodium (DSS)-induced experimental colitis. METHODS: Recombinant adenoviral vectors encoding GDNF (Ad-GDNF) were administered intracolonically in experimental colitis induced by DSS. The disease activity index and histological score were measured. The expression of tumour necrosis factor-α (TNF-α), interleukin-6 and myeloperoxidase (MPO) activity were measured by ELISA assay. The expression of trypsin and ß-hexosaminidase were evaluated. GDNF specific receptor (GFR-α1/RET) was detected. The calcium reflux was tested by microplate reader. The expression p-JNK was analyzed by western blot assay. RESULTS: GDNF resulted in a significant inhibition of the activation of enteric mast cells by down-regulating JNK signal pathway, lessening intracellular calcium influx, and then reducing the degranulation as well as the expression of pro-inflammatory cytokines via combing with its receptor (GFR-α1/RET) in mast cells, and these inhibitory effects were abrogated by treatment with neutralizing antibody against GDNF. Moreover, the administration of GDNF led to an amelioration of experimental colitis. CONCLUSIONS: GDNF are able to regulate enteric mast cells and ameliorate experimental colitis. GDNF might be an important mediator of the cross-talk between EGCs and enteric mast cells, and GDNF might be a useful therapeutic drug for IBD.

Effect of PLCε gene silencing on inhibiting the cancerous transformation of ulcerative colitis.

The aim of the present study was to investigate the effect of phosphoinositide-specific phospholipase Cε (PLCε) gene silencing on the inhibition of cancer development in ulcerative colitis (UC) and to explore the pathogenesis and carcinogenic mechanism of UC, in order to facilitate the establishment of novel strategies for the treatment of UC, prevent the cancerous transformation of UC and discern the association between inflammation and cancer. A pGenesil-PLCε RNA interference vector was constructed and transfected into HEK293 cells (pGenesil-PLCε group). HEK293 cells transfected with pGenesil empty plasmid were set as the negative control (pGenesil-NC group). The expression of PLCε was observed, and molecules associated with the PLC signaling pathway were detected using a reverse transcription-quantitative polymerase chain reaction and western blotting. ELISA was used to determine the expression of serum interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) of mice in which the PLCε gene had been silenced. Compared with the pGenesil-NC group, the mRNA and protein levels of PLCε were significantly decreased in the pGenesil-PLCε group. In addition, the mRNA levels of K-ras, NF-κB, Fas and Bcl-2 were markedly reduced, while P53 mRNA level was notably enhanced, in the pGenesil-PLCε group, and these changes were accompanied by similar changes in the corresponding protein levels. The serum IL-1 and TNF-α expression in the PLCε gene-silenced mice was significantly reduced compared with that in the control mice. In conclusion, PLCε RNA silencing can effectively inhibit the cancerous transformation of UC by regulating the colorectal cancer-related cell proliferation and cell cycle in vivo. In addition, PLCε RNA silencing can suppress the expression of inflammatory factors in vitro.

Blockade of p38 mitogen-activated protein kinase pathway ameliorates delayed gastric emptying in streptozotocin-induced diabetic rats.

BACKGROUND AND AIM: Gastrointestinal dysfunction is one of the major complications of diabetes. The roles of inflammation in diabetes and its associated complications are increasingly recognized. p38 mitogen-activated protein kinase (MAPK) has been shown to be involved in the production of pro-inflammatory mediators. The aims of this study were to investigate the effects of SB203580, a specific p38 MAPK inhibitor, on delayed gastric emptying in diabetic rats and to elucidate its possible mechanism. METHODS: SB203580 was administered in diabetic rats induced by intraperitoneal injection of streptozotocin. The gastric emptying rate of rats was measured by using phenol red solution, and blood glucose levels and body weights were observed. p38 MAPK activity and iNOS expression were assessed by Western blot analysis. The expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1ß were determined by enzyme-linked immunosorbent assay. RESULTS: Gastric emptying was delayed significantly in diabetic rats and improved significantly with SB203580; high glucose significantly activated p38 MAPK and increased the expression of iNOS, TNF-α and IL-1ß. The administration of SB203580 led to a significant decrease in the activation of p38 MAPK and the expression of iNOS, TNF-α and IL-1ß. CONCLUSIONS: Inflammation was associated with the development of delayed gastric emptying, and blockade of p38 MAPK pathway with SB203580 ameliorates delayed gastric emptying in diabetic rats, at least in part, by inhibiting the expression of iNOS, TNF-a and IL-1ß. Therefore, p38MAPK may serve as a novel target for the therapy of diabetes-related gastrointestinal dysmotility.

Glial-derived neurotrophic factor reduces inflammation and improves delayed colonic transit in rat models of dextran sulfate sodium-induced colitis.

BACKGROUND: Intestinal inflammation is well known to cause gut dysmotility through the effects on the enteric nervous system. Glial-derived neurotrophic factor (GDNF) has been demonstrated to have anti-inflammatory effects and neuronal protective actions. The aim of this study was to investigate whether the GDNF could improve inflammation-induced gut dysmotility. METHODS: Recombinant adenoviral vectors encoding GDNF (Ad-GDNF) were administered intracolonically in experimental colitis induced by dextran sulfate sodium (DSS). The disease activity index (DAI) and histological score were measured. Colonic transit was measured by using phenol red and assessed with the geometric center. PGP 9.5 immunostaining was used to examine the number and distribution of enteric neurons. The expression of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and myeloperoxidase (MPO) activity were measured by ELISA assay. The expression of Akt, caspase-3, bcl-2 and PGP 9.5 was analyzed by western blot assay. RESULTS: A significant neuronal cell loss and a significant delay in colonic transit accompanied with the neuronal loss following inflammation were observed. GDNF prevented partially the loss of enteric neurons and ameliorated significantly experimental colitis and delayed colonic transit by, at least in part, down-regulation of TNF-α and IL-1ß expression, decrease of infiltration of leukocytes, and inhibition of neuronal cell apoptosis. CONCLUSIONS: GDNF reduces inflammation and improves delayed colonic transit in DSS-induced colitis. GDNF may be a useful therapeutic agent for the treatment of gut dysmotility in patients with UC.

[Role of p38 mitogen-activated protein kinase pathway in pathogenesis of ulcerative colitis].

OBJECTIVE: To elucidate the role of p38 mitogen-activated protein kinase (p38MAPK) in the pathogenesis of ulcerative colitis (UC) and DSS-induced colitis in mice. METHODS: (1) 27 Balb/c mice were divided randomly into three groups: DSS-induced colitis group, normal control group and SB203580 treatment group. In DSS-induced colitis group, mice were feed with 5% DSS solution. In SB203580 treatment group, mice were feed with 5%DSS solution for 72 hours, then treated with intraperitoneal injection of SB203580 (1 mg/kg) once daily. Disease activity index (DAI) was record to evaluate the severity of colitis. The mice were executed after 7 days. The levels of TNF-alpha and IL-1beta were measured by ELISA. (2) A total of 54 cases were included in the study. 36 cases were patients with active ulcerative colitis, 18 cases were normal mucosa from 18 colon cancer cases served as control. Effects of SB203580 (a selective p38MAPK inhibitor) on expression of TNF-alpha and IL-1beta in intestinal mucosal biopsy specimens from patients with ulcerative colitis were determined on condition of tissue culture. RESULTS: (1) The DAI scores, the levels of TNF-alpha and IL-1beta in SB203580 group were lower significantly compared with DSS group (P < 0.05), and were increased significantly compared with normal control group (P < 0.05). (2) The levels of TNF-alpha and IL-1beta in intestinal mucosal biopsy specimens in SB203580 treatment group were lower significantly than those in UC group (P < 0.05). CONCLUSION: SB203580 can inhibit p38MAPK signal transduction pathway, then reduce the expression of pro-inflammatory cytokine TNF-alpha and IL-1beta.

[Study on esophageal motor function against reflux after esophagogastric anastomosis with mucosal valve].

OBJECTIVE: To find an effective operative procedure against reflux after esophagogastric anastomosis with mucosal valve. METHODS: Four hundred and sixty-four patients with esophageal or cardiac cancer were randomly divided into three groups according to anastomosis modes. Group A underwent esophagogastric anastomosis with mucosal valve (175 cases), group B with mechanical stapler (151 cases) and group C one layer anastomosis with handcraft suture (138 cases). The gastroesophageal reflux index (GERI) was examined by isotope,and 24 h esophageal pH was also monitored. The esophageal motor function was compared among three groups. RESULTS: The reflux rates were 0, 33.3%, and 6.7% in group A, B, C respectively. The esophageal motor function and the 24 h esophageal pH monitoring indicated that the various indexes were approaching to the normal level in group A, but the various indexes in group B and C were significantly different from the normal values (P< 0.05). CONCLUSION: The esophagogastric anastomosis with mucosal valve has better antireflux effect and can prevent the reflux esophagitis after esophageal or cardiac cancer eradication.