PURPOSE OF THE STUDY.
Multiple studies have demonstrated that perinatally HIV-exposed but HIV-uninfected (HEU) infants experience greater morbidity and mortality than HIV-unexposed, uninfected infants (HUU). Newborn acquisition of the maternal microbiome provides metabolic and immunologic health benefits. The purpose of this study was to examine the effects of HIV infection on the maternal microbiome and breast milk oligosaccharides and the subsequent impact these may have on the microbiomes of their HEU infants.
A total of 50 Haitian mother-infant pairs were studied. All infants were breastfed, and no infants were on antibiotics at the time of the study. A total of 25 HIV-positive mothers and their infants were studied and compared with 25 HIV-uninfected mothers and their infants. Notably, all HIV-positive mothers were on combination antiretroviral therapy, and most had low HIV viral loads and normal CD4+ T-cell counts.
Demographic and clinical data were obtained from patient records. Selected body sites were sampled for bacterial microbiological analysis from each subject. 16S ribosomal DNA was analyzed by using a previously described method. Breast milk oligosaccharides were characterized with high-pressure liquid chromatography.
Surprisingly, the microbiomes of the 2 groups of mothers did not differ appreciably. However, the microbiomes of the HEU infants had significant differences compared with the microbiomes from the HUU infants. Uninfected infants born to HIV-infected mothers showed lower microbial diversity and a different taxonomic composition. For example, HEU infants had an increased proportion of Pseudomonadaceae and less mature bacterial communities. HUU infants had an increase in Prevotellaceae and a greater maturity of their bacterial communities. This study examined 1 potential cause for this difference in the infants’ microbiomes. Infants cannot digest human milk oligosaccharides, which may act as prebiotics to influence the infants’ microbiomes. The data presented showed that normal breast milk oligosaccharide composition is altered by maternal HIV infection, and this was in turn associated with changes in the infants’ gut microbiomes.
The gut microbiome in HIV-exposed, uninfected infants differs from that of HIV-unexposed and uninfected infants, and human milk oligosaccharides were associated with specific bacterial species. It was speculated that this dysbiosis may contribute to the increased risk of illness in HEU infants.
It is not unexpected that the presence of a chronic infection would alter individual microbiomes. However, in this study, the changes in the microbiomes of HIV-infected versus HIV-uninfected mothers are relatively subtle. It is possible that the effective treatment of the HIV-infected mothers allowed relative normalization of their microbiota. Despite this, there were still variations in the infant microbiota depending on their exposure (or not) to HIV. A majority of the studies that have reported increased morbidity and mortality in HEU infants come from sub-Saharan Africa. Additionally, study subjects from France who demonstrated this increased risk were largely composed of mothers also from sub-Saharan Africa. In a study from Denmark, there was no significant difference in the hospitalization rate among HIV-exposed compared with HIV-unexposed children when admission for infectious diseases was analyzed. Finally, in the French cohort, the increased risk for serious bacterial infections in HIV-exposed, uninfected infants was related primarily to maternal immunosuppression. If the limited differences in the microbiomes between HIV-infected mothers and HIV-uninfected mothers in the current study is related to effective maternal antiretroviral therapy, the end result (regardless of the mechanism) is most favorable to HIV-exposed infants.
- Copyright © 2017 by the American Academy of Pediatrics