Kidney transplant is a common procedure in those with late-stage renal disease. These patients can experience gastrointestinal complaints such as diarrhea, which may be associated with premature kidney allograft failure and mortality. Historically, has been thought due to medication, however the etiology is not well understood.
A study led by Stephan J. L. Bakker of University Medical Center Groningen, The Netherlands, set out to understand the basis of post-kidney transplant diarrhea in greater detail using breath biopsies. The study made use of the TransplantLines Biobank and Cohort Study and was published in the Journal of Clinical Medicine.
Kidney transplant recipients had significantly lower methane, but not hydrogen, in their breath than healthy controls. The use of the use of mycophenolate mofetil was also associated with a lower breath methane concentration. A lower percentage of kidney transplant recipients had detectable Methanobrevibacter smithii, a methanogen archaeon, in their feces than controls.
Methane can reduce inflammation, oxidative stress and apoptosis and it is possible that lack of methane in the gut plays a causal role in diarrhea experienced by kidney transplant patients, however the study did not investigate this.
A major limitation of the study was that methane concentrations and the abundance of M. smithii in the feces of kidney transplant patients were not measured before transplantation in addition to the measurements made. It remains possible that the conditions, such as diabetes, that led to the need for a kidney transplant also caused the change in the gut microbiota, raising the question of why diarrhea was not experienced before the transplant.
“These findings provide novel insight into the alterations of fermentation after renal transplantation, which may contribute to the occurrence of posttransplant diarrhea. In addition, this study has raised important hypotheses regarding the potential role of SRB and M. stadtmanae in post-transplant diarrhea. Future studies are needed to investigate the role of sulfate-reducing bacteria and M. stadtmanae. Additionally, future research may study whether altered methanogenesis is associated with clinical outcomes, such as posttransplant diarrhea,” concluded the authors.