Mesenchymal stem cells(MSCs)closely interact with the immune system,and they are known to secrete inflammatory cytokines in response to stress stimuli.The biological function of MSC-derived inflammatory cytokines rema...Mesenchymal stem cells(MSCs)closely interact with the immune system,and they are known to secrete inflammatory cytokines in response to stress stimuli.The biological function of MSC-derived inflammatory cytokines remains elusive.Here,we reveal that even under physiological conditions,MSCs produce and release a low level of tumor necrosis factor alpha(TNFα),which is unexpectedly required for preserving the self-renewal and differentiation of MSCs via autocrine/paracrine signaling.Furthermore,TNFαcritically maintains MSC function in vivo during bone homeostasis.Mechanistically,we unexpectedly discovered that physiological levels of TNFαsafeguard MSC homeostasis in a receptor-independent manner through mechanical force-driven endocytosis and that endocytosed TNFαbinds to mammalian target of rapamycin(mTOR)complex 2 and restricts mTOR signaling.Importantly,inhibition of mTOR signaling by rapamycin serves as an effective osteoanabolic therapeutic strategy to protect against TNFαdeficiency and mechanical unloading.Collectively,these findings unravel the physiological framework of the dynamic TNFαshuttlebased mTOR equilibrium that governs MSC and bone homeostasis.展开更多
Mesenchymal stem cells(MSCs)influence T cells in health,disease and therapy through messengers of intercellular communication including extracellular vesicles(EVs).Apoptosis is a mode of cell death that tends to promo...Mesenchymal stem cells(MSCs)influence T cells in health,disease and therapy through messengers of intercellular communication including extracellular vesicles(EVs).Apoptosis is a mode of cell death that tends to promote immune tolerance,and a large number of apoptotic vesicles(apoVs)are generated from MSCs during apoptosis.In an effort to characterize these apoVs and explore their immunomodulatory potential,here we show that after replenishing them systemically,the apoV deficiency in Fas mutant mice and pathological lymphoproliferation were rescued,leading to the amelioration of inflammation and lupus activity.ApoVs directly interacted with CD4^(+)T cells and inhibited CD25 expression and IL-2 production in a dose-dependent manner.A broad range of Th1/2/17 subsets and cytokines including IFNγ,IL17A and IL-10 were suppressed while Foxp3^(+)cells were maintained.Mechanistically,exposed phosphatidylserine(PtdSer/PS)on apoVs mediated the interaction with T cells to disrupt proximal T cell receptor signaling transduction.Remarkably,administration of apoVs prevented Th17 differentiation and memory formation,and ameliorated inflammation and joint erosion in murine arthritis.Collectively,our findings unveil a previously unrecognized crosstalk between MSC apoVs and CD4^(+)T cells and suggest a promising therapeutic use of apoVs for autoimmune diseases.展开更多
基金This work was supported by grants from the National Institute of Dental and Craniofacial Research,National Institutes of Health,Department of Health and Human Services(K99E025915 to C.C.)a Schoenleber Pilot Research Grant(to S.S.)from the University of Pennsylvania School of Dental Medicine,the Guangdong Financial Fund for High-Caliber Hospital Construction,the Postdoctoral Innovative Talents Support Program of China(BX20190380 to B.S.)the General Program of the China Postdoctoral Science Foundation(2019M663986 to B.S.).
文摘Mesenchymal stem cells(MSCs)closely interact with the immune system,and they are known to secrete inflammatory cytokines in response to stress stimuli.The biological function of MSC-derived inflammatory cytokines remains elusive.Here,we reveal that even under physiological conditions,MSCs produce and release a low level of tumor necrosis factor alpha(TNFα),which is unexpectedly required for preserving the self-renewal and differentiation of MSCs via autocrine/paracrine signaling.Furthermore,TNFαcritically maintains MSC function in vivo during bone homeostasis.Mechanistically,we unexpectedly discovered that physiological levels of TNFαsafeguard MSC homeostasis in a receptor-independent manner through mechanical force-driven endocytosis and that endocytosed TNFαbinds to mammalian target of rapamycin(mTOR)complex 2 and restricts mTOR signaling.Importantly,inhibition of mTOR signaling by rapamycin serves as an effective osteoanabolic therapeutic strategy to protect against TNFαdeficiency and mechanical unloading.Collectively,these findings unravel the physiological framework of the dynamic TNFαshuttlebased mTOR equilibrium that governs MSC and bone homeostasis.
基金This work was supported by grants from the State Scholarship Fund of China(201506240225to R.W.)the Pearl River Talent Recruitment Program(2019ZT08Y485,2019QN01Y138,2019JC01Y182)+2 种基金the National Key R&D Program of China(2021YFA1100600to S.S.)the Guangdong Financial Fund for High-Caliber Hospital Construction(174-2018-XMZC-0001-03-0125,D-07 to S.S.,C-03 and D-11 to X.K.)the National Natural Science Foundation of China(82170924to X.K.).
文摘Mesenchymal stem cells(MSCs)influence T cells in health,disease and therapy through messengers of intercellular communication including extracellular vesicles(EVs).Apoptosis is a mode of cell death that tends to promote immune tolerance,and a large number of apoptotic vesicles(apoVs)are generated from MSCs during apoptosis.In an effort to characterize these apoVs and explore their immunomodulatory potential,here we show that after replenishing them systemically,the apoV deficiency in Fas mutant mice and pathological lymphoproliferation were rescued,leading to the amelioration of inflammation and lupus activity.ApoVs directly interacted with CD4^(+)T cells and inhibited CD25 expression and IL-2 production in a dose-dependent manner.A broad range of Th1/2/17 subsets and cytokines including IFNγ,IL17A and IL-10 were suppressed while Foxp3^(+)cells were maintained.Mechanistically,exposed phosphatidylserine(PtdSer/PS)on apoVs mediated the interaction with T cells to disrupt proximal T cell receptor signaling transduction.Remarkably,administration of apoVs prevented Th17 differentiation and memory formation,and ameliorated inflammation and joint erosion in murine arthritis.Collectively,our findings unveil a previously unrecognized crosstalk between MSC apoVs and CD4^(+)T cells and suggest a promising therapeutic use of apoVs for autoimmune diseases.