Presented by Dr Andrew Prendergast, Queen Mary University of London, London, UK
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Breastmilk is not just food, it contains maternal immune cells, stem cells, immunoglobulins, microbiota, cytokines, growth factors, and glutamine which leads to intestinal maturity of the infant.
Moreover, breastmilk is extraordinarily adaptive, it is driven by gestational age, mode of delivery, time from birth, geography, infant sex, and infant illness. It adapts to infant’s illness by changing its composition according to the infant’s needs. As a result, the macrophage count is much higher during infant illness. The maternal and infant gut are intimately linked through breastfeeding.
These variations in breastmilk changes the intestinal permeability in the baby. HIV infected cells can penetrate breastmilk and will get to the intestinal mucosa of the infant. The mechanism of entry to the gut is still unclear, some argue is due to the CD4 cells in the epithelium.
From many studies carried out in Africa, it is known that mixed breastfeeding increases the risk of HIV transmission compared to exclusive feeding. Introducing solids in the first 2 months of life also increased the risk of transmission by 2-fold. Gut permeability rises with complimentary feeding and may increase HIV transmission. In Zimbabwe, low birth weight also increased the risk of postnatal HIV transmission. Intrauterine growth retardation affects gut structure by changing pannet cells and goblet cells in infant’s microbiota.
Why do most HIV-exposed infants not acquire HIV? The speaker argued that it is due to a combination of factors, including the viral bottleneck, breastmilk antimicrobial factors, passive maternal antibodies, and HIV specific T cells in breastmilk.
The risk of HIV transmission through breastfeeding in virally suppressed females is less than 1% and according to WHO guidelines, women living in resource-limited countries should breastfeed exclusively for the first 6 months of life in view that that the benefits of breastfeeding outweighs the possible risks!
