Inverse expression of prostaglandin E2-related enzymes highlights differences between diverticulitis and inflammatory bowel disease.

BACKGROUND: Prostaglandin E2 (PGE2) is the dominant prostaglandin in the colon and is associated with colonic inflammation. PGE2 levels are regulated not only by cyclooxygenases (COX-1 and COX-2) but also by 15-hydroxyprostaglandin dehydrogenase (15-PGDH), the major PGE2-degrading enzyme. Information about the involvement of 15-PGDH in colonic inflammation is sparse. AIM: We thus aimed to determine the gene expression and immunoreactivity (IR) of COX-1, COX-2, and 15-PGDH in colonic mucosa from patients with diverse inflammatory disorders: ulcerative colitis (UC), Crohn's disease (CD), and acute diverticular disease (DD). METHODS: RNA from human colonic mucosa was extracted and assessed for gene expression by real-time PCR. Intact colon sections were processed for immunohistochemistry with immunostaining of the mucosal areas quantified using ImageJ. RESULTS: In colonic mucosa of both UC and CD, COX-2 mRNA and COX-2-IR were significantly increased, whereas 15-PGDH mRNA and 15-PGDH-IR were significantly reduced. In macroscopically undamaged acute DD mucosa, the opposite findings were seen: for both gene expression and immunoreactivity, there was a significant downregulation of COX-2 and upregulation of 15-PGDH. COX-1 mRNA and COX-1-IR remained unchanged in all diseases. CONCLUSIONS: Our study for the first time demonstrated differential expression of the PGE2-related enzymes COX-2 and 15-PGDH in colonic mucosa from UC, CD, and acute DD. The reduction of 15-PGDH in IBD provides an additional mechanism for PGE2 increase in IBD. With respect to DD, alterations of PGE2-related enzymes suggest that a low PGE2 level may precede the onset of inflammation, thus providing new insight into the pathogenesis of DD.

Nitrergic neuro-muscular transmission is up-regulated in patients with diverticulosis.

BACKGROUND: Neuro-transmission impairment could be associated to motility changes observed in patients with diverticular disease. Therefore, the objective was to characterize the inhibitory neuro-muscular transmission and gene expression changes of the enteric inhibitory pathways in patients with diverticulosis (DS). METHODS: Circular muscle strips from sigmoid colon of patients with DS and controls were studied using the organ bath technique to evaluate spontaneous contractility and enteric motor neurons stimulated by electrical field and qRT-PCR to assess the expression of nNOS, iNOS, P2Y1 R and PGP9.5. KEY RESULTS: Patients with DS presented decreased spontaneous rhythmic contractions (SRC) that were significantly enhanced after incubation with L-NNA (1 mM) and TTX (1 µM), and unaffected by the P2Y1 antagonist MRS2500 (1 µM). Stimulation on enteric motor neurons caused an increased duration of the latency of OFF-contractions in DS group (p < 0.001), antagonized by L-NNA and slightly affected by MRS2500 (1 µM). No differences in the IC50 between controls and DS patients were observed on inhibition of SRC for the NO-donor sodium nitroprusside (SNP) and the preferential P2Y agonist ADPßS. Moreover, nNOS relative expression was also up-regulated 2.3-fold in the DS group (p < 0.05) whereas there was no significant difference in relative expression of iNOS, P2Y1 R and the neuronal marker PGP9.5 between groups. CONCLUSIONS & INFERENCES: Patients with DS presented an over-expression of nNOS with increased endogenously NO-mediated responses suggesting enhanced NO-release. Up-regulation in the nitrergic pathway in early stages of the disease might play a role in colonic motor disorders associated to diverticular disease.

Morphologic pattern of myenteric neural plexus in colonic diverticular disease. A whole-mount study employing histochemical staining for acetylcholinesterase.

BACKGROUND: Diverticular disease (DD) of the colon is a frequent clinical problem because 30-50% of the population over the age of 60 years in western communities are affected by DD. Although certain clinical, physiological and biochemical studies have shown that the origin of DD may be neurogenic, the mechanism of DD pathogenesis is still not clear. METHODS: The aim of the present study has been to assess the morphologic pattern of the myenteric nerve plexus (MNP) in diverticulous sigmoid colon (DSC) comparing the structural organization in DSC (n=10) to relatively normal sigmoid colon (rNSC) that had been resected from patients for rectal tumors (n=10). The histochemical method for acetylcholinesterase was utilized to visualize the MNP on pressure bloated, non-sectioned gut preparations. RESULTS: The study revealed that the MNP of DSC was degenerated, as its interganglionic nerves were periodically interrupted and thinner than in rNSC. The number of myenteric ganglia in same-sized areas (125 mm(2)) as well as the average area of myenteric plexus was significantly higher in controls compared with the DD patients, (respectively, ganglion number: 163 +/- 12 and 149 +/- 12, p<0.02; MN-plexal area: 8.1 +/- 0.3 mm(2) and 7.2 +/- 0.2 mm(2), p<0.001). CONCLUSION: The occurrence of DD in sigmoid colon is associated with morphologic alterations in MNP (i.e. the number of ganglia and plexus rarefaction, ganglion size and plexal area involution), which presumably demonstrate the failure of MNP in DD patients.