Peer-reviewed article
Immunoglobulin recognition of fecal bacteria in stunted and non-stunted children: findings from the Afribiota study
Kelsey E. Huus, André Rodriguez Pozo, Nathalie Kapel, Alison Nestoret, Azimdine Habib et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined how the intestinal immune system recognizes bacteria in stunted versus non-stunted children aged 2-5 years in Madagascar and Central African Republic. Stunted children had a higher proportion of bacteria recognized by immunoglobulin A (IgA), an antibody that helps manage gut bacteria. Two bacteria commonly found in stunted children—Haemophilus and Campylobacter—were strongly recognized by IgA in both countries. The findings suggest that undernutrition is associated with altered immune responses to gut microbes.
Key points
- Stunted children had a greater proportion of IgA-positive bacteria in their fecal microbiota compared to non-stunted controls
- The trend of higher IgA+ bacteria in stunted children was consistent across both Madagascar and Central African Republic
- Haemophilus and Campylobacter were among the most highly IgA-recognized bacteria regardless of nutritional status
- IgG-bound intestinal bacteria were rare in both stunted and non-stunted children
- Stunted children carry a high load of intestinal pathogens and pathobionts
Limitations
This is a descriptive observational study that cannot establish causation between IgA-targeting patterns and stunting. The study does not test an intervention, so it provides evidence of association rather than demonstrating that modifying immune responses would improve child growth or health outcomes.
Abstract
BACKGROUND: Child undernutrition is a global health issue that is associated with poor sanitation and an altered intestinal microbiota. Immunoglobulin (Ig) A mediates host-microbial homeostasis in the intestine, and acutely undernourished children have been shown to have altered IgA recognition of the fecal microbiota. We sought to determine whether chronic undernutrition (stunting) or intestinal inflammation were associated with antibody recognition of the microbiota using two geographically distinct populations from the Afribiota project. Fecal bacteria from 200 children between 2 and 5 years old in Antananarivo, Madagascar, and Bangui, Central African Republic (CAR), were sorted into IgA-positive (IgA+) and IgA-negative (IgA-) populations by flow cytometry and subsequently characterized by 16S rRNA gene sequencing to determine IgA-bacterial targeting. We additionally measured IgG+ fecal bacteria by flow cytometry in a subset of 75 children. RESULTS: Stunted children (height-for-age z-score ≤ -2) had a greater proportion of IgA+ bacteria in the fecal microbiota compared to non-stunted controls. This trend was consistent in both countries, despite the higher overall IgA-targeting of the microbiota in Madagascar, but lost significance in each country individually. Two of the most highly IgA-recognized bacteria regardless of nutritional status were Campylobacter (in CAR) and Haemophilus (in both countries), both of which were previously shown to be more abundant in stunted children; however, there was no association between IgA-targeting of these bacteria and either stunting or inflammatory markers. IgG-bound intestinal bacteria were rare in both stunted and non-stunted children, similar to levels observed in healthy populations. CONCLUSIONS: Undernourished children carry a high load of intestinal pathogens and pathobionts. Our data suggest that stunted children have a greater proportion of IgA-recognized fecal bacteria. We moreover identify two putative pathobionts, Haemophilus and Campylobacter, that are broadly targeted by intestinal IgA. This study furthers our understanding of host-microbiota interactions in undernutrition and identifies immune-recognized microbes for future study.