High‐fat diet (HFD) induced hepatic endoplasmic reticulum (ER) stress drives insulin resistance (IR) and steatosis. NK cells in adipose tissue play an important role in the pathogenesis of IR in obesity. Whether NK cells in the liver can induce hepatic ER stress and thus promote IR in obesity is still unknown. We demonstrate that HFD‐fed mice display elevated production of proinflammatory cytokine osteopontin (OPN) in hepatic NK cells, especially in CD49a+DX5– tissue‐resident NK (trNK) cells. Obesity‐induced ER stress, IR, and steatosis in the liver are ameliorated by ablating NK cells with neutralizing antibody in HFD‐fed mice. OPN treatment enhances the expression of ER stress markers, including p‐PERK, p‐eIF2, ATF4, and CHOP in both murine liver tissues and HL‐7702, a human liver cell line. Pretreatment of HL‐7702 cells with OPN promotes hyperactivation of JNK and subsequent decrease of tyrosine phosphorylation of insulin receptor substrate‐1 (IRS‐1), resulting in impaired insulin signaling, which can be reversed by inhibiting ER stress. Collectively, we demonstrate that hepatic NK cells induce obesity‐induced hepatic ER stress, and IR through OPN production.

A novel diaminodiphenylmethane (DDM) modified ammonium polyphosphate (APP) flame retardant, DDP, was successfully synthesized via ion-exchange reaction. DDP was introduced into epoxy resins (EPs) to reduce flammability. A comparable level of DDP exerts better flame-retardant and smoke suppression efficiencies in EP than APP. An EP blend containing 15 wt% DDP displays a limiting oxygen index (LOI) value of 37.1% and a UL 94 V-0 rating, and further exhibits a 32.3% reduction in total heat release and a 48.0% reduction in total smoke production compared with pure EP. The presence of DDP greatly facilitates char formation during combustion, and the char mass from thermal decomposition of an EP blend is 37.8% smaller than that of an EP blend containing 15 wt% DDP at 800 °C. The incorporation of DDP into EP blends has a smaller impact on the glass transition temperature and tensile strength than those of a comparable level of APP. This reflects the better compatibility of DDP with the EP matrix compared with that for APP.

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