Fresh Water Salinization Syndrome and Impacts on host infection susceptibility and Vibriosis Severity via gut-immune axis

Fresh water salinization is an emerging threat to public health for millions of coastal inhabitants worldwide including coastlines of USA, Bangladesh, Vietnam, Myanmar and India. Notably, the above regions face sea level rise and devastating cyclones linked to climate change. Clinical epidemiology suggests that parallel to freshwater salinization, cases of cholera, vibriosis have risen in the recent decade and the specific causes that link host susceptibility to freshwater salinization are unknown. Working in two field-research sites across two countries, I test the hypothesis that saltwater exposure to host causes an altered gut-bacterial diversity leading to a leaky gut and inflammatory microenvironment that ultimately makes the host susceptible to Vibrio infections. Using water samples from the coastal fresh water sources, I created an invitro model of exposure using intestinal epithelial cells. My results showed that salt water interacts with gut bacteria to release pro-inflammatory microbial metabolites that in turn caused a disruption of gut barrier integrity as shown by higher levels of Claudin-2 and lower Occludin. Further, there was an increase in proinflammatory toll like receptor 4 (TLR4). When challenged with cholera toxin (CTX) or Vibrio Sp toxin VVHA, cells suffered increased gut barrier integrity loss, cellular inflammation, and cellular injury (necroptosis). Saltwater exposure also decreased sensitivity to antibiotics in isolated Vibrio strains. In addition, gut bacterial flora from fecal pellets exposed to salt water showed an altered gut microbiome and anti-microbial resistance signature. In summary, the study may provide important clues about the toxicology of freshwater salinization, host gut-immune health and susceptibility to enteric disease. The project was funded by institutional funds for research training at UCI and icddr, b This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.