Bicarbonate secretion and acid/base sensing by the intestine

Role of declined electrogenic Na+/HCO3- cotransporter NBCe1 in mucus barrier impairment and colonic inflammation

BACKGROUND

Electrogenic Na+/HCO3- co-transporter 1 (NBCe1) plays a pivotal role in epithelial bicarbonate transport involved in the maintenance of the intestinal mucus barrier. However, the specific role of NBCe1 in colitis remains unknown.

METHODS

NBCe1 was identified by bioinformatics analysis methods including GO/KEGG/GSEA, protein-protein interaction (PPI) network analysis, immune infiltration analysis, and Mendelian randomization (MR) analysis. Expression level of NBCe1 was detected in patients with IBD and in DSS-induced colitis mice. The role of NBCe1 in intestinal mucus barrier and colitis was accessed by S0859 pretreatment in DSS model. The function of NBCe1 and related bicarbonate secretion were evaluated using short-circuit current (Isc) measurements in Ussing chamber system.

RESULTS

Bioinformatic analyses indicated that SLC4A4 (NBCe1) was a signature gene in bicarbonate transport implicated in ulcerative colitis (UC) development and was negatively associated with the risk of UC. NBCe1's expression was significantly diminished in colonic mucosa of UC patients and DSS-treated mice. More severe intestinal inflammation and impaired mucus barrier were observed in S0859-treated mice. Moreover, S0859 administration led a significant decrease in mucus secretion rate and an significant increase in Isc of colonic mucosa. The forskolin-induced ΔIsc was also suppressed by S0859 pretreatment.

CONCLUSION

NBCe1 has been identified as a valuable signature gene may have a protective effect against the onset of colitis. Function of NBCe1 is diminished in colitis, which is associated with impaired mucus barrier and declined HCO3- secretion both contributing to the development of IBD.

Targeting Enterotoxins: Advancing Vaccine Development for Enterotoxigenic Escherichia coli ETEC

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease worldwide, particularly in children in low- and middle-income countries. Its ability to rapidly colonize the intestinal tract through diverse colonization factors and toxins underpins its significant public health impact. Despite extensive research and several vaccine candidates reaching clinical trials, no licensed vaccine exists for ETEC. This review explores the temporal and spatial coordination of ETEC virulence factors, focusing on the interplay between adherence mechanisms and toxin production as critical targets for therapeutic intervention. Advancements in molecular biology and host-pathogen interaction studies have uncovered species-specific variations and cross-reactivity between human and animal strains. In particular, the heat-labile (LT) and heat-stable (ST) toxins have provided crucial insights into molecular mechanisms and intestinal disruption. Additional exotoxins, such as EAST-1 and hemolysins, further highlight the multifactorial nature of ETEC pathogenicity. Innovative vaccine strategies, including multiepitope fusion antigens (MEFAs), mRNA-based approaches, and glycoconjugates, aim to enhance broad-spectrum immunity. Novel delivery methods, like intradermal immunization, show promise in eliciting robust immune responses. Successful vaccination against ETEC will offer an effective and affordable solution with the potential to greatly reduce mortality and prevent stunting, representing a highly impactful and cost-efficient solution to a critical global health challenge.

Sodium Bicarbonate Decreases Alcohol Consumption in Mice

We previously reported that mice with low neuronal pH drink more alcohol, demonstrating the importance of pH for alcohol reward and motivation. In this study, we tested whether systemic pH affects alcohol consumption and if so, whether it occurs by changing the alcohol reward. C57BL/6J mice were given NaHCO3 to raise their blood pH, and the animals' alcohol consumption was measured in the drinking-in-the-dark and two-bottle free choice paradigms. Alcohol consumption was also assessed after suppressing the bitterness of NaHCO3 with sucrose. Alcohol reward was evaluated using a conditioned place preference. In addition, taste sensitivity was assessed by determining quinine and sucrose preference. The results revealed that a pH increase by NaHCO3 caused mice to decrease their alcohol consumption. The decrease in high alcohol contents (20%) was significant and observed at different ages, as well as in both males and females. Alcohol consumption was also decreased after suppressing NaHCO3 bitterness. Oral gavage of NaHCO3 did not alter quinine and sucrose preference. In the conditioned place preference, NaHCO3-treated mice spent less time in the alcohol-injected chamber. Conclusively, the results show that raising systemic pH with NaHCO3 decreases alcohol consumption, as it decreases the alcohol reward value.