Background Prenatal exposure to fine particulate matter (PM_2.5) is closely associated with cortical damage and neuroinflammation in offspring. The cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS)–stimulator of interferon genes (STING) signaling pathway is a key regulator of inflammation and may be subject to epigenetic regulation. Objective To investigate the role of cGAS-STING pathway activation in PM_2.5-induced cortical damage in offspring mice during pregnancy and the underlying epigenetic regulatory mechanisms. Methods Open field tests were used to assess depressive-like behavior in offspring mice. Morphological analysis was conducted to evaluate cortical damage and microglial activation in offspring brains. Real-time fluorescent quantitative PCR (RT-qPCR) and Western blot (WB) were performed to detect changes in the expression of key molecules in the cGAS-STING pathway in cortical tissue. A PM_2.5-induced microglial cell injury model was established in BV2 cells. Microglial activation was observed, cell viability was measured using the Cell Counting Kit-8 (CCK-8), and the expression levels of inducible nitric oxide synthase (iNOS) and key molecules in the cGAS-STING pathway were detected by RT-qPCR and WB. Bioinformatics analysis was performed to explore the epigenetic regulatory association between the STING signaling pathway and lysine-specific demethylase 5A (KDM5A). Changes in KDM5A mRNA and protein expression, as well as the protein level of histone H3 lysine 4 trimethylation (H3K4me3), were detected in an in vitro PM_2.5 injury model. Using small interfering RNA (siRNA) technology, the KDM5A gene was silenced in BV2 cells exposed to PM_2.5. The protein expression of H3K4me3 was detected to evaluate improvements in microglial activation, changes in inflammatory markers such as iNOS and mannose receptor (CD206), and alterations in the cGAS-STING pathway. Results Compared with the control group, the total distance of offspring mice in the PM_2.5 group was significantly reduced, and both the distance traveled and the time spent in the central area of the open field were significantly decreased (P<0.01, P<0.001), indicating depressive-like behavior in the offspring mice. Compared with the control group, the offspring mice in the PM_2.5 group exhibited disorganized cortical structure and significantly activated microglia (P<0.01), with significantly increased mRNA and protein levels of cGAS and STING (P<0.05, P<0.01, or P<0.001). The in vitro experiments demonstrated that the PM_2.5 treatment induced BV2 cells to polarize toward the M1 phenotype, exhibiting a distinct amoeboid morphology, with upregulated expression of the pro-inflammatory factor iNOS (P<0.05, P<0.01, or P<0.001) and activation of the cGAS-STING pathway (P<0.05, P<0.01). The analysis of RNA-seq data from KDM5A knockout cells revealed significantly downregulated STING expression, suggesting that KDM5A may activate the STING signaling pathway. The in vitro experiments further confirmed that the PM_2.5-treated BV2 cells exhibited significantly elevated mRNA and protein levels of KDM5A (P<0.01), while the H3K4me3 protein levels were markedly reduced (P<0.05). After silencing KDM5A in BV2 cells exposed to PM_2.5, compared with the PM_2.5+siNC group, the PM_2.5+siKDM5A group showed no obvious microglial activation and polarized toward the M2 phenotype, with significantly decreased expression levels of iNOS, cluster of differentiation 16 (CD16), and interleukin-1β (P<0.05, P<0.01), and significantly increased expression levels of anti-inflammatory factors CD206, YM1, and interleukin-10 (P<0.01, P<0.001). Meanwhile, the expression levels of cGAS and STING were also reduced (P<0.05, P<0.01). Conclusion KDM5A activates microglia through the cGAS-STING pathway, thereby contributing to PM_2.5-induced cortical damage in offspring mice during pregnancy.

AIM:To investigate the role and mechanism of histone demethylase lysine-specific demethylase 5A(KDM5A)in regulating the Notch signaling pathway in particulate matter 2.5(PM2.5)-induced cortical damage in off-spring mice.METHODS:A pregnancy PM2.5 exposure model was established using intratracheal nebulization.Pregnant mice were randomly divided into PBS control group and PM2.5 exposure group.The cortices of offspring mice were isolated 14 d after birth.Golgi staining,electron microscopy and other methods were used to detect damage to neurons and chroma-tin in the cortex.Western blot,RT-qPCR and immunofluorescence staining were used to detect the mRNA and protein ex-pression of KDM5A in the cortex,and the distribution of KDM5A co-localized with neural cells.A PM2.5-treated PC12 cell injury model was established to detect changes in cell viability and the expression of proteins related to cell proliferation and apoptosis.Further,Western blot,RT-qPCR and immunofluorescence staining were used to detect the mRNA and pro-tein expression of KDM5A,the distribution of KDM5A co-localized with neurons,and changes in the protein level of his-tone H3K4me3.Bioinformatics methods were used to predict the interaction between KDM5A and Notch1,which was fur-ther validated by transfection experiments.In both in vivo and in vitro PM2.5 exposure models,changes in key molecules of the Notch signaling pathway and the co-expression of Notch1 with neural cells in the cortices of 14-day-old offspring mice and PC12 cells were detected.RESULTS:Prenatal PM2.5 exposure during pregnant led to a reduction in the number of neurons and decreased dentritic complexity in the cerebral cortex of offspring at 14 d after birth.It also caused abnormal chromatin condensation within neuronal nuclei,decreased mRNA and protein expression of KDM5A protein in the cortex,increased H3K4me3 protein levels(P＜0.05),and a significant reduction in KDM5A/NeuN double-positive cells.Expo-sure to PM2.5 also resulted in decreased viability and proliferation,and increased apoptosis of PC12 cells,with reduced ex-pression of KDM5A mRNA and protein,increased H3K4me3 protein expression(P＜0.05),and a reduction in the num-ber of KDM5A/MAP-2 double-positive cells.Bioinformatics analysis and transfection experiments in PC12 cells revealed that Notch1 is a downstream target gene of KDM5A.Further in vivo and in vitro experiments found that PM2.5 exposure lead to decreased mRNA and protein expression of key Notch signaling molecules Notch1,Jagged1 and Hes1,and reduced numbers of Notch1/NeuN and Notch1/MAP-2 double-positive cells.CONCLUSION:Exposure to PM2.5 can lead to abnor-mal expression of KDM5A in the offspring's cerebral cortex,which may cause neuronal damage by down-regulating the Notch signaling pathway,a downstream target.This could be one of the significant factors contributing to the neurodevelop-mental disorders in offspring exposed to PM2.5 during pregnancy.

AIM:To investigate the role and mechanism of histone demethylase lysine-specific demethylase 5A(KDM5A)in regulating the Notch signaling pathway in particulate matter 2.5(PM2.5)-induced cortical damage in off-spring mice.METHODS:A pregnancy PM2.5 exposure model was established using intratracheal nebulization.Pregnant mice were randomly divided into PBS control group and PM2.5 exposure group.The cortices of offspring mice were isolated 14 d after birth.Golgi staining,electron microscopy and other methods were used to detect damage to neurons and chroma-tin in the cortex.Western blot,RT-qPCR and immunofluorescence staining were used to detect the mRNA and protein ex-pression of KDM5A in the cortex,and the distribution of KDM5A co-localized with neural cells.A PM2.5-treated PC12 cell injury model was established to detect changes in cell viability and the expression of proteins related to cell proliferation and apoptosis.Further,Western blot,RT-qPCR and immunofluorescence staining were used to detect the mRNA and pro-tein expression of KDM5A,the distribution of KDM5A co-localized with neurons,and changes in the protein level of his-tone H3K4me3.Bioinformatics methods were used to predict the interaction between KDM5A and Notch1,which was fur-ther validated by transfection experiments.In both in vivo and in vitro PM2.5 exposure models,changes in key molecules of the Notch signaling pathway and the co-expression of Notch1 with neural cells in the cortices of 14-day-old offspring mice and PC12 cells were detected.RESULTS:Prenatal PM2.5 exposure during pregnant led to a reduction in the number of neurons and decreased dentritic complexity in the cerebral cortex of offspring at 14 d after birth.It also caused abnormal chromatin condensation within neuronal nuclei,decreased mRNA and protein expression of KDM5A protein in the cortex,increased H3K4me3 protein levels(P＜0.05),and a significant reduction in KDM5A/NeuN double-positive cells.Expo-sure to PM2.5 also resulted in decreased viability and proliferation,and increased apoptosis of PC12 cells,with reduced ex-pression of KDM5A mRNA and protein,increased H3K4me3 protein expression(P＜0.05),and a reduction in the num-ber of KDM5A/MAP-2 double-positive cells.Bioinformatics analysis and transfection experiments in PC12 cells revealed that Notch1 is a downstream target gene of KDM5A.Further in vivo and in vitro experiments found that PM2.5 exposure lead to decreased mRNA and protein expression of key Notch signaling molecules Notch1,Jagged1 and Hes1,and reduced numbers of Notch1/NeuN and Notch1/MAP-2 double-positive cells.CONCLUSION:Exposure to PM2.5 can lead to abnor-mal expression of KDM5A in the offspring's cerebral cortex,which may cause neuronal damage by down-regulating the Notch signaling pathway,a downstream target.This could be one of the significant factors contributing to the neurodevelop-mental disorders in offspring exposed to PM2.5 during pregnancy.