Modulation of cell-mediated immunity during pregnancy in wild bonobos

Abstract

During pregnancy, the mammalian immune system must simultaneously protect against pathogens while being accommodating to the foreign fetal tissues. Our current understanding of this immune modulation derives predominantly from industrialized human populations and laboratory animals. However, their environments differ considerably from the pathogen-rich, resource-scarce environments in which pregnancy and the immune system co-evolved. For a better understanding of immune modulation during pregnancy in challenging environments, we measured urinary neopterin, a biomarker of cell-mediated immune responses, in 10 wild female bonobos (Pan paniscus) before, during and after pregnancy. Bonobos, sharing evolutionary roots and pregnancy characteristics with humans, serve as an ideal model for such investigation. Despite distinct environments, we hypothesized that cell-mediated immune modulation during pregnancy is similar between bonobos and humans. As predicted, neopterin levels were higher during than outside of pregnancy, and highest in the third trimester, with a significant decline post-partum. Our findings suggest shared mechanisms of cell-mediated immune modulation during pregnancy in bonobos and humans that are robust despite distinct environmental conditions. We propose that these patterns indicate shared immunological processes during pregnancy among hominins, and possibly other primates. This finding enhances our understanding of reproductive immunology.

Keywords: comparative immunology; gestation; immune modulation; neopterin; primate reproduction.

Figure 1.

Urinary neopterin levels of female bonobos before, during and after pregnancy. Boxes in blue indicate non-pregnant (before and after pregnancy) states, while boxes showing measurements from pregnant females (first, second and third trimester) are coloured in orange. The boxplot shows the distribution of urinary neopterin levels (log-transformed) before, during and after pregnancy as estimated by the models (for population level effects) see (a), for within-individual patterns see (b). Each box represents the interquartile range (IQR), with the horizontal line inside the box indicating the median. Whiskers extend to the minimum and maximum values within 1.5 times the IQR. Black dots show actual datapoints.