Gestational PFAS exposure and newborn size:The modifying effect of cord blood fatty acids

Per-and polyfluoroalkyl substances(PFASs)can disrupt lipid metabolism,and changes in cord blood fatty acid composition have been observed in small newborns.Emerging evidence suggests that exposure to PFASs during pregnancy is linked to decreased newborn size,although the evidence is not consistent.The modifying effect of fatty acids on the associations of gestational PFAS exposure with newborn size is still unknown.Here we show that the nutritional status of the fetus,as indicated by the level of fatty acids in the cord blood,mitigates the adverse effects of gestational PFAS exposure on the size of the newborn.Our study confirms the adverse developmental effects of PFASs and identifies emerging short-chain PFASs as the primary drivers of reduced newborn size,despite their lower exposure burden compared to legacy PFASs.Additionally,we find the protective role of cord blood fatty acids,suggesting potential strategies for mitigating the detrimental effects of emerging environmental exposures on human health.Our findings provide new evidence of the potential toxicity of emerging PFASs and call for further toxicity evaluations of these pollutants for regulatory purposes.Future studies should consider the complex interaction between exposure and nutrition within the human body,particularly during the first thousand days of life,to promote lifelong health.

Respective IL-17A production by γδ T and Th17 cells and its implication in host defense against chlamydial lung infection

The role of IL-17A is important in protection against lung infection with Chlamydiae,an obligate intracellular bacterial pathogen.In this study,we explored the producers of IL-17A in chlamydial lung infection and specifically tested the role of major IL-17A producers in protective immunity.We found thatγδT cells and Th17 cells are the major producers of IL-17A at the early and later stages of chlamydial infection,respectively.Depletion ofγδT cells in vivo at the early postinfection(p.i.)stage,when mostγδT cells produce IL-17A,failed to alter Th1 responses and bacterial clearance.In contrast,the blockade of IL-17A at the time when IL-17A was mainly produced by Th17(day 7 p.i.)markedly reduced the Th1 response and increased chlamydial growth.The data suggest that theγδT cell is the highest producer of IL-17A in the very early stages of infection,but the protection conferred by IL-17A is mainly mediated by Th17 cells.In addition,we found that depletion ofγδT cells reduced IL-1αproduction by dendritic cells,which was associated with a reduced Th17 response.This finding is helpful to understand the variable role of IL-17A in different infections and to develop preventive and therapeutic approaches against infectious diseases by targeting IL-17A.