母親が重症インフルエンザと闘うと胎児の脳に影響: 新しいマウス研究でメカニズムが明らかに(Fetal brain impacted when mom fights severe flu: New mouse study explains how)

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2024-07-29 イリノイ大学アーバナ・シャンペーン校

妊娠中のインフルエンザ感染が胎児の神経発達障害のリスクを高めるが、それはウイルス自体ではなく母親の免疫反応によるものです。イリノイ大学アーバナ・シャンペーン校の研究チームは、マウスを使った実験でこの過程を細胞レベルで詳しく解明しました。研究では、生きたインフルエンザウイルスを用いて、母親の感染が一定の重症度を超えると胎児の脳に変化が生じることを示しました。特に高用量感染では、胎児の新皮質に顕著な変化が見られました。この研究は「Molecular Psychiatry」に発表されました。

<関連情報>

妊娠中のA型インフルエンザウイルスは、母親の腸管免疫と胎児の皮質発達を用量・時間依存的に破壊する Influenza A virus during pregnancy disrupts maternal intestinal immunity and fetal cortical development in a dose- and time-dependent manner

Ashley M. Otero,Meghan G. Connolly,Rafael J. Gonzalez-Ricon,Selena S. Wang,Jacob M. Allen & Adrienne M. Antonson
Molecular Psychiatry  Published:03 July 2024
DOI:https://doi.org/10.1038/s41380-024-02648-9

母親が重症インフルエンザと闘うと胎児の脳に影響: 新しいマウス研究でメカニズムが明らかに(Fetal brain impacted when mom fights severe flu: New mouse study explains how)

Abstract

Epidemiological studies link exposure to viral infection during pregnancy, including influenza A virus (IAV) infection, with increased incidence of neurodevelopmental disorders (NDDs) in offspring. Models of maternal immune activation (MIA) using viral mimetics demonstrate that activation of maternal intestinal T helper 17 (TH17) cells, which produce effector cytokine interleukin (IL)-17, leads to aberrant fetal brain development, such as neocortical malformations. Fetal microglia and border-associated macrophages (BAMs) also serve as potential cellular mediators of MIA-induced cortical abnormalities. However, neither the inflammation-induced TH17 cell pathway nor fetal brain-resident macrophages have been thoroughly examined in models of live viral infection during pregnancy. Here, we inoculated pregnant mice with two infectious doses of IAV and evaluated peak innate and adaptive immune responses in the dam and fetus. While respiratory IAV infection led to dose-dependent maternal colonic shortening and microbial dysregulation, there was no elevation in intestinal TH17 cells nor IL-17. Systemically, IAV resulted in consistent dose- and time-dependent increases in IL-6 and IFN-γ. Fetal cortical abnormalities and global changes in fetal brain transcripts were observable in the high-but not the moderate-dose IAV group. Profiling of fetal microglia and BAMs revealed dose- and time-dependent differences in the numbers of meningeal but not choroid plexus BAMs, while microglial numbers and proliferative capacity of Iba1+ cells remained constant. Fetal brain-resident macrophages increased phagocytic CD68 expression, also in a dose- and time-dependent fashion. Taken together, our findings indicate that certain features of MIA are conserved between mimetic and live virus models, while others are not. Overall, we provide consistent evidence of an infection severity threshold for downstream maternal inflammation and fetal cortical abnormalities, which recapitulates a key feature of the epidemiological data and further underscores the importance of using live pathogens in NDD modeling to better evaluate the complete immune response and to improve translation to the clinic.

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