Persistent Aerointolerant Gut Microbes and Butyrate Depletion in Severe Acute Malnutrition

Abstract Severe acute malnutrition (SAM) constitutes the leading risk for childhood mortality worldwide. Butyrate, a critical metabolite for mucosal immunity produced by anaerobic gut microbes, has been found to be dramatically depleted in children experiencing fatal outcomes related to SAM. However, the association between butyrate depletion and gut microbiota alteration has not yet been fully explored. Here, we performed a large group-matched case-control study in children aged 0-59 months in Mali. We compared faecal short-chain fatty acids (SCFAs) and gut microbiota from children with SAM and healthy controls, using gas chromatography-mass spectrometry and 16S rRNA v3v4 gene amplicon sequencing. A total of 253 children, including 143 with SAM and 110 controls, were included. Our findings revealed a dramatic imbalance in gut microbiota characterised by the predominance of aerotolerant micro-organisms in children with SAM, irrespective of age and sex. Importantly, aerointolerant species were totally absent in eight samples from children with SAM. A pronounced depletion of faecal valeric, butyric, propanoic and, to a lesser extent, acetic acid was observed, correlating with a ten-fold decrease in butyrate-producing microbes among the SAM population. This notable depletion of gut aerointolerant prokaryotes and butyrate levels persisted without being reversed at the time of discharge. Future therapeutic strategies aimed at addressing SAM should focus on restoring the gut anaerobic microbiota and faecal propionate and butyrate. Competing Interest Statement The authors have declared no competing interest. Funding Statement This work was funded by ANR-15-CE36-0004-01 and by ANR Investissements d avenir, Mediterranee Infection 10-IAHU-03 and was also supported by the Region Pro-vence-Alpes-Cote d Azur. This work received financial support from the Mediterranean Infection Foundation. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics Committee of the University of Bamako Faculty of Medicine and Odon-to-Stomatology waived ethical approval for this work on 22 May 2014 (2014/46/CE/FMPOS). Informed and signed consent was obtained from all legal representatives (parents). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes