Altered interaction between enteric glial cells and mast cells in the colon of women with irritable bowel syndrome

BACKGROUND

Enteric glial cells (EGC) and mast cells (MC) are intimately associated with gastrointestinal physiological functions. We aimed to investigate EGC-MC interaction in irritable bowel syndrome (IBS), a gut-brain disorder linked to increased intestinal permeability, and MC.

METHODS

Parallel approaches were used to quantify EGC markers in colonic biopsies from healthy controls (HC) and patients with IBS. Data were correlated with MC, vasoactive intestinal polypeptide (VIP) and VIP receptors (VPAC1/VPAC2) expressions, and bacterial translocation through biopsies mounted in Ussing chambers. In addition, we investigated the effects of EGC mediators on colonic permeability and the pharmacological-induced responses of EGC and MC cell lines.

KEY RESULTS

Immunofluorescence of IBS colonic mucosa, as well as Western blotting and ELISA of IBS biopsy lysates, revealed increased glial fibrillary intermediate filament (GFAP) expression, indicating EGC activation. Mucosal GFAP correlated with increased MC and VPAC1⁺ MC numbers and decreased VIP⁺ MC, which seemed to control bacterial translocation in HC. In the contrary, EGC activation in IBS correlated with less MC and VPAC1⁺ MC numbers, and more VIP⁺ MC. In vitro, MC and EGC cell lines showed intracellular calcium responses to each other's mediators. Furthermore, EGC mediators prevented VIP-induced MC degranulation, while MC mediators induced a reactive EGC phenotype. In Ussing chambers, EGC mediators decreased paracellular passage through healthy colonic biopsies.

CONCLUSIONS & INFERENCES

Findings suggest the involvement of EGC and MC in the control of barrier function in the human colon and indicate a potential EGC-MC interaction that seems altered in IBS, with detrimental consequences to colonic permeability. Altogether, results suggest that imbalanced EGC-MC communication contributes to the pathophysiology of IBS.

Elevated F-EDN correlates with mucosal eosinophil degranulation in patients with IBS-A possible association with microbiota?

Eosinophils have been linked to functional dyspepsia; however, less is known about their role in irritable bowel syndrome (IBS). This study tested the hypothesis of alterations in levels of fecal eosinophil-derived neurotoxin (F-EDN) and eosinophil density and degranulation within the colonic mucosa of IBS patients compared with healthy controls (HC). Colonic biopsies were collected from 37 IBS patients and 20 HC and analyzed for eosinophil numbers and local degranulation of eosinophil cationic protein (ECP) by histologic procedures. Fecal samples were collected for F-EDN and microbiota analysis. Differentiated 15HL-60 cells were used in vitro to investigate the direct effect of live bacteria on eosinophil activation measured by a colorimetric assay with o-phenylenediamine (OPD) substrate. We observed a higher number of eosinophils and increased extracellular ECP in the mucosa of IBS patients compared with HC. Moreover, F-EDN levels in IBS samples were elevated compared with HC and positively correlated to extracellular ECP. Metagenomic analysis showed significant correlations between bacterial composition and eosinophil measurements in both HC and IBS patients. In vitro experiments revealed an increased degranulation of 15HL-60 after stimulation with Salmonella typhimurium, Salmonella enterica, and Yersinia enterocolitica. To conclude, we could demonstrate alterations related to eosinophils in IBS, and, for the first time, a positive correlation between F-EDN levels and degranulated eosinophils in the colonic mucosa of IBS patients. Together our results suggest that eosinophils play a role in the pathophysiology of IBS and the mechanisms might be linked to an altered microbiota.

Colonic paracellular permeability and circulating zonulin-related proteins

OBJECTIVE

Irritable bowel syndrome (IBS) is a gut-brain disorder associated with increased gut permeability. Zonulin has been suggested to regulate the gut barrier and claimed to be pre-haptoglobin 2 (pre-HP2) and circulating zonulin is often used as a proxy for gastrointestinal permeability. This study investigated the correlation between colonic paracellular permeability and levels of circulating zonulin and pre-HP2.

MATERIALS AND METHODS

Colonic biopsies from 32 patients with IBS and 15 healthy controls (HC) were used to measure permeability in Ussing chambers and levels of zonulin (Cusabio ELISA). Zonulin was also measured in blood samples from 40 HC, 78 patients with IBS and 20 patients with celiac disease (CeD), before and after a gluten-free diet. In addition, we verified HP genotype and circulating pre-HP2 using a monoclonal pre-HP2 antibody (Bio-Rad) by ELISA.

RESULTS

Increased colonic paracellular permeability correlated positively with zonulin levels in IBS biopsies, but negatively with plasma zonulin. We found no agreement between circulating zonulin and pre-HP2. Genotyping revealed non-specificity of the zonulin kit, as all pre-HP2 non-producers presented detectable levels. Patients with CeD displayed higher pre-HP2 and zonulin levels compared to HC. A gluten-free diet in patients with CeD led to lower serum zonulin and pre-HP2 concentrations.

CONCLUSIONS

Our study suggests that neither circulating zonulin nor pre-HP2 mirror colonic permeability. Our data corroborate previous reports showing the inability of the Cusabio zonulin kit to target zonulin and highlights that the results of studies using this kit must be re-examined with caution.

Gastroprotective effects of hydroethanolic root extract of Arrabidaea brachypoda: Evidences of cytoprotection and isolation of unusual glycosylated polyphenols

The hydroethanolic root extract of Arrabidaea brachypoda, from Bignoniaceae family, a Brazilian medicinal plant, demonstrated significant in vivo gastroprotective effects using different in vivo assays. The activity was evaluated in several models of experimental gastric ulcer in rats (absolute ethanol, glutathione depletion, nitric oxide depletion, non-steroidal anti-inflammatory drugs, pylorus ligation and acetic acid). Using 300 mg/kg (p.o.) the extract significantly reduced gastric injury in all models. In depth phytochemical investigation of this extract led to the isolation of two previously undescribed phenylethanoid glycosides derivatives and seven unusual glycosylated dimeric flavonoids. The structures were elucidated using UV, NMR and HRMS analysis. Absolute configuration of the dimeric flavonoids was performed by electronic circular dichroism (ECD) spectroscopy.

Healing, antioxidant and cytoprotective properties of Indigofera truxillensis in different models of gastric ulcer in rats

The present study evaluated the antiulcerogenic activity and mechanisms of the aqueous (AqF 100 mg/kg) and ethyl acetate (AcF 50 mg/kg) fractions from Indigofera truxillensis leaves. This dose was selected to assess its activity on ulcer healing and its action on gastric acid and mucus secretion, prostaglandin production and antioxidant enzyme activity (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd)). Gastric ulcer was induced by absolute ethanol. Antisecretory action, mucus and prostaglandin production, healing and antioxidant enzyme activities were evaluated for both fractions. AqF and AcF significantly inhibited the gastric mucosal damage caused by ethanol. This effect was statistically significant at 100 and 50 mg/kg compared with the vehicle. Neither fraction interfered with gastric secretion. AcF increased the PGE(2) production, and both fractions increased mucus production. l-NAME did not alter the gastroprotection exerted by the fractions, but N-ethylmaleimide attenuated only AcF. In the ischemia/reperfusion model both fractions inhibited the mucosal damage. AcF increased SOD, GSH-Px and GSH-Rd activity, but AqF increased only SOD and GSH-Px. In the acetic acid-induced ulcer model AcF only accelerated ulcer healing. These results showed that Indigofera truxillensis acted as a gastroprotective agent, stimulating protective factors and antioxidants enzymes.

Antioxidant action of mangrove polyphenols against gastric damage induced by absolute ethanol and ischemia-reperfusion in the rat

Rhizophora mangle, the red mangrove, has long been known as a traditional medicine. Its bark has been used as astringent, antiseptic, hemostatic, with antifungic and antiulcerogenic properties. In this paper, we aimed to evaluate the antioxidant properties of a buthanolic fraction of the R. mangle bark extract (RM) against experimental gastric ulcer in rats. Unib-Wh rats received pretreatment of R. mangle after the induction of gastric injury with absolute ethanol and ischemia-reperfusion. Gastric tissues from both methods were prepared to the enzymatic assays, the levels of sulfhydril compounds (GSH), lipid peroxides (LPO), and the activities of glutathione reductase (GR), glutathione peroxidase (GPx), superoxide dismutase (SOD) and myeloperoxidase (MPO) were measured. The RM protected the gastric mucosa in both methods used, ethanol-induced gastric ulcer and ischemia-reperfusion, probably, by modulating the activities of the enzymes SOD, GPx, and GR and increasing or maintaining the levels of GSH; in adittion, LPO levels were reduced. The results suggest that the RM antioxidant activity leads to tissue protection; thus one of the antiulcer mechanisms present on the pharmacological effects of R. mangle is the antioxidant property.

Mechanisms of action underlying the gastric antiulcer activity of the Rhizophora mangle L

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizophora mangle, the red mangrove, has long been known as a traditional antiulcer medicine. The present work evaluated the mechanisms of action involved in the anti-ulcer properties of the Rhizophora mangle bark extracts.

MATERIALS AND METHODS

Gastroprotection of Rhizophora mangle was evaluated in rodent experimental models (ethanol). To elucidate the mechanisms of action the antisecretory action and involvement of NO, SH, mucus and PGE(2) were evaluated. The acetic acid-induced gastric ulcer model, Western blotting assay (COX-1, COX-2 and EGF) and immunohistochemical localization of HSP-70, PCNA and COX-2 were also used to evaluate the Rhizophora mangle healing properties.

RESULTS

Results showed that Rhizophora mangle bark crude extract (CE), as well as ethyl acetate (EtOAc) and butanolic fractions (BuOH) provided significant gastroprotection at all the tested doses. Thereby, the following protocols were performed using the lowest dose capable of producing the most effective gastroprotection, which was the BuOH 0.5mg/kg (P<0.001). Several mechanisms are involved in the antiulcer activity of Rhizophora mangle, such as, participation of NO, SH and mucus. The enhancement of PGE(2) levels and the upregulation of COX-2 and EGF seem to be directly linked to the antisecretory, cytoprotective and healing effects of BuOH. HSP-70 and PCNA are also involved in this cicatrisation process. No sign of toxicity was observed in this study, considering the analyzed parameters.

CONCLUSION

Our study reinforces its traditional medicinal use. Considering that the current therapies are based on the use of antisecretory or cytoprotective drugs, the Rhizophora mangle arises as a promising alternative antiulcer therapy.

Gastroprotective and ulcer healing effects of essential oil from Hyptis spicigera Lam. (Lamiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis Jacq. (Lamiaceae) is being used in traditional medicine to treat fever, inflammation and gastric disturbances. Hyptis spicigera Lam. is a native plant distributed across the central region of Brazil. The essential oil extracted from this plant is used in folk medicine as antipyretic.

AIM OF THE STUDY

The effects of the essential oil obtained from the aerial parts of Hyptis spicigera (OEH) were evaluated for their gastroprotective and healing activities.

MATERIALS AND METHODS

OEH chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). The gastroprotective action of the OEH was evaluated in rodent experimental models (ethanol and NSAID). To elucidate mechanisms of action, the antisecretory action and involvements of NO, SH, mucus and PGE2 were evaluated. The acetic acid-induced gastric ulcer model and Western Blot assay (COX-2 and EGF) were also used to evaluate the OEH healing capacity.

RESULTS

GC-MS analysis of OEH indicated three monoterpenes as major compounds: alpha-pinene (50.8%), cineole (20.3%) and beta-pinene (18.3%) and, at the dose of 100 mg/Kg, p.o., OEH provided effective gastroprotection against lesions induced by absolute ethanol (97%) and NSAID (84%) in rats. OEH do not interfere with H+ secretion in gastric mucosa and its gastric protection does not depend on nitric oxide (NO) and sulfhydryl compounds (SH). The gastroprotective action of OEH occurs due to an increase in the gastric mucus production (28%) induced by PGE2 levels. Furthermore, OEH demonstrated a great healing capacity with 87% of reduction in ulcerative lesion area. It accelerated the healing of acetic acid-induced gastric lesions due to an increase in COX-2 (75%) and EGF (115%) expression in gastric mucosa. No sign of toxicity was observed in this study, considering the analyzed parameters.

CONCLUSIONS

All these results suggest the efficacy and safety of Hyptis spicigera in combating and healing gastric ulcer. Considering the results, it is suggested that the OEH could probably be a good therapeutic agent for the development of new phytotherapeutic medicine for the treatment of gastric ulcer.