Changes in motor behavior, neuropathology, and gut microbiota of a Batten disease mouse model following administration of acidified drinking water

Abstract

CLN3 mutations cause the fatal neurodegenerative disorder, CLN3 Batten disease. The Cln3−/− mouse model displays characteristic features of the human disease including motor deficits. When mice received acidified drinking water (pH 2.5–2.9) instead of normal tap water (pH 8.4) for several generations, the motor skills of Cln3−/− mice normalized to control levels, indicating a disease-modifying effect of acidified water. Here we investigated if acidified water administered from postnatal day 21 has therapeutic benefits in Cln3−/− mice. Indeed, acidified water temporarily attenuated the motor deficits, had beneficial effects on behavioral parameters and prevented microglial activation in the brain of Cln3−/− mice. Interestingly, in control mice, acidified drinking water caused brain region-specific glial activation and significant changes in motor performance. Since the gut microbiota can influence neurological functions, we examined it in our disease model and found that the gut microbiota of Cln3−/− mice was markedly different from control mice, and acidified water differentially changed the gut microbiota composition in these mice. These results indicate that acidified water may provide therapeutic benefit to CLN3 Batten disease patients, and that the pH of drinking water is a major environmental factor that strongly influences the results of murine behavioral and pathological studies.

The acidified drinking water-induced changes in the behavior and gut microbiota of wild-type mice depend on the acidification mode

“…Male 129S6/SvEv mice received drinking water acidified to pH 2.8 with H 2 SO 4 from weaning (postnatal day 21) to examine if consumption of H 2 SO 4 -acidified water results in changes of behavior and the gut microbiota similarly to that observed previously with HCl-acidified drinking water 1 .…”

“…Since the gut microbiota can influence neurological functions, we examined how H 2 SO 4 -acidified drinking water affects the gut flora in comparison to HCl-acidified water. The gut microbiota composition of male 129S6/SvEv mice receiving H 2 SO 4 -acidified drinking water from weaning was determined from fecal samples by 16S rRNA gene sequencing, and analyzed together with gut microbiota data previously obtained from male 129S6/SvEv mice that were kept on non-acidified water or received HCl-acidified water from weaning 1 . Thus, the fecal DNA samples from mice receiving H 2 SO 4 -acidified drinking water were sequenced separately from the samples from mice on non-acidified and HCl-acidified water.…”

“…Since pathogenic bacteria cannot grow in acidified water, acidification of drinking water to a pH between 2.5 and 3.0 is widely used to prevent the spread of bacterial diseases in animal colonies 1 . Many research institutes including e.g., the National Institute of Health, Bethesda, MD 2 – 4 , Harvard Medical School, Boston, MA 5 – 8 , Stanford University, Stanford, CA 9 – 11 , Cornell University, Ithaca, NY 12 – 14 , University of California, Los Angeles, CA 15 – 17 , Boston Children’s Hospital, Boston, MA 18 , 19 , Texas A&M University, College Station, TX 20 , and Emory University, Atlanta, GA 21 use acidified drinking water in their animal facilities.…”

“…Although, no adverse health effect of acidified drinking water has been reported, three recent studies showed that acidified drinking water can change the microbial flora living in the gut (gut microbiota), and this change affects autoimmunity 23 – 25 . Furthermore, we have recently demonstrated that HCl-acidified drinking water (average pH: 2.8) received from weaning (postnatal day 21) significantly altered the behavior and gut microbiota of Cln3 −/− and 129S6/SvEv wild-type mice 1 . Besides HCl, sulfuric acid (H 2 SO 4 ) is also used to acidify drinking water for animal colonies 26 – 28 .…”

Calcium Oxalate Nephrolithiasis and Gut Microbiota: Not just a Gut-Kidney Axis. A Nutritional Perspective

“…Water pH is able to influence the microbiota composition of mice, probably because different pH allows the growth of different microbial populations in drinking water [156]. The supply of acidified drinking water to mice was able to induce deep changes of gut microbiota composition, including the overrepresentation of several taxa that are notable components of microbiota in humans, such as Bacteroides, Alistipes, Barnesiella, and Lactobacillus [157]. For this reason, some authors recently proposed that drinking water pH should be considered as a covariate in microbiome studies conducted in animal models [158].…”