Proteção tópica in vitro da mucosa esofágica de pacientes com doença do refluxo gastroesofágico usando a “goma do angico”, um biopolímero de Anadenanthera colubrina

Abstract

Gastroesophageal reflux disease (GERD) is a prevalent condition that affects about 13% of the world population. Approximately 60-70% of patients do not present macroscopic changes in the esophagus, while about 20-30% have erosions on endoscopy. Although PPI therapy is the treatment of choice, about a third of patients do not respond adequately to treatment, especially those with Non-Erosive Reflux Disease (NERD). Therefore, alternative forms of treatment should be considered. We aimed to evaluate the integrity of the esophageal mucosa in patients with gastroesophageal reflux disease and to investigate the topical protective effect of polysaccharide Anadenanthera colubrina (Angico Gum, AG in acronym). Six biopsies of the distal esophageal mucosa were collected from 35 patients (24 without erosion or NERD and 11 with erosive esophagitis or EE) and mounted in Ussing chambers. AG was applied topically and in different concentrations (1%, 3% and 10%, w/v), followed by exposure with pH 2.0 acid solution containing pepsin and taurodeoxycholic acid (TDCA) for 30 min, where Transepithelial Electrical Resistance (TER) was continuously measured. Control biopsies (no coated) were also exposed to acid solution. Then, the acid solution was replaced by the fluorescein solution, to assess transepithelial permeability for 90 min. In another experiment, the control and pretreated biopsies with AG at the concentration of 10% were exposed to acid solution pH 2.0 containing pepsin and TDCA for 120 min. The TER of the control biopsies and pretreated with AG-10% or sodium alginate was also evaluated after exposure to acid solution pH 1.0 containing pepsin and TDCA for 30 minutes, and then the acid solution was replaced by the fluorescein solution, for evaluation of the transepithelial permeability for 90 min. We performed an epifluorescence microscopy to localize on the oesopageal epithelium the biopolymer previously labeled with FITC. The pH 2.0 acid solution containing pepsin and TDCA promoted a gradual drop in TER in control biopsies of NERD patients and EE at the end of 30 min Pretreatment with AG-10% was able to prevent the drop in TER (P<0,05) compared to control biopsies. AG-1% and AG-3% did not protect the esophageal mucosa against the refluxate-like solution (P> 0.05). Acid exposure (pH 2.0 + TDCA + pepsin) on the luminal side of the esophageal mucosa of NERD and EE patients promoted a gradual increase in fluorescein permeability, with maximum effect over 90 min. Topical application of AG-10% significantly decreases (P <0.05) the fluorescein permeability in NERD patients, however, this reduction was not significant in EE patients (P> 0.05). The protective effect of AG-10% was sustained for up to 120 min both in biopsies of NERD and EE (P <0.05), when compared to control biopsies. AG-10% and sodium alginate were not able to protect biopsies against more acidic solution (pH 1.0) containing pepsin and TDCA when compared to control biopsies (P> 0.05). AG-10% and alginate were not able to decrease the fluorescein permeability when compared to the control group. Epifluorescent microscope images showed mucosal luminal adherence of FITC- labeled AG-10%. We concluded that AG-10% applied to mucosal biopsies of patients with NERD and EE has a prolonged topical protective effect against exposure to acid solution (pH 2.0 + TDCA + pepsin). However, this effect was not observed with the exposure of biopsies to more acidic solutions (pH 1.0 + TDCA + pepsin). These findings should be further explored in the development of new topical treatments for GERD patients.