Myeloid-specific blockade of Notch signaling alleviates murine pulmonary fibrosis through regulating monocyte-derived Ly6c(lo) MHCII(hi) alveolar macrophages recruitment and TGF-β secretion.

Macrophages in lung, including resident alveolar macrophages (AMs) and interstitial macrophages (IMs), and monocyte-derived macrophages, play important roles in pulmonary fibrosis (PF), but mechanisms underlying their differential regulation remain unclear. Recombination signal-binding protein Jκ (RBP-J)-mediated Notch signaling regulates macrophage development and phenotype. Here, using bleomycin-induced fibrosis model combined with myeloid-specific RBP-J disruption (RBP-JcKO ) mouse, we investigated the role of Notch signaling in macrophages during PF. Compared with the control, RBP-JcKO mice exhibited alleviated lung fibrosis as manifested by reduced collagen deposition and inflammation, and decreased TGF-β production. FACS analysis suggested that decreased Ly6clo MHCIIhi AMs might make the major contribution to attenuated fibrogenesis in RBP-JcKO mice, probably by reduced inflammatory factor release and enhanced matrix metalloproteinases expression. Using clodronate-mediated macrophage depletion in RBP-JckO mice, we demonstrated that embryonic-derived AMs play negligible role in lung fibrosis, which was further supported by adoptive transfer experiments. Moreover, on CCR2 knockout background, the effect of RBP-J deficiency on fibrogenesis was not elicited, suggesting that Notch regulated monocyte-derived AMs. Co-culture experiment showed that monocyte-derived AMs from RBP-JcKO mice exhibit reduced myofibroblast activation due to decreased TGF-β secretion. In conclusion, monocyte-derived Ly6clo MHCIIhi AMs, which are regulated by RBP-J-mediated Notch signaling, play an essential role in lung fibrosis.

Zhang N ，Yang K ，Bai J ，Yi J ，Gao C ，Zhao J ，Liang S ，Wei T ，Feng L ，Song L ，Han H ，Qin H ... -  《-》

Myeloid-specific targeting of Notch ameliorates murine renal fibrosis via reduced infiltration and activation of bone marrow-derived macrophage.

Jiang Y ，Wang Y ，Ma P ，An D ，Zhao J ，Liang S ，Ye Y ，Lu Y ，Zhang P ，Liu X ，Han H ，Qin H ... -  《-》

Myeloid-specific blockade of notch signaling alleviates dopaminergic neurodegeneration in Parkinson's disease by dominantly regulating resident microglia activation through NF-κB signaling.

Yolk sac-derived microglia and peripheral monocyte-derived macrophages play a key role during Parkinson's disease (PD) progression. However, the regulatory mechanism of microglia/macrophage activation and function in PD pathogenesis remains unclear. Recombination signal-binding protein Jκ (RBP-J)-mediated Notch signaling regulates macrophage development and activation. In this study, with an 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) hydrochloride-induced acute murine PD model, we found that Notch signaling was activated in amoeboid microglia accompanied by a decrease in tyrosine hydroxylase (TH)-positive neurons. Furthermore, using myeloid-specific RBP-J knockout (RBP-JcKO) mice combined with a PD model, our results showed that myeloid-specific disruption of RBP-J alleviated dopaminergic neurodegeneration and improved locomotor activity. Fluorescence-activated cell sorting (FACS) analysis showed that the number of infiltrated inflammatory macrophages and activated major histocompatibility complex (MHC) II+ microglia decreased in RBP-JcKO mice compared with control mice. Moreover, to block monocyte recruitment by using chemokine (C-C motif) receptor 2 (CCR2) knockout mice, the effect of RBP-J deficiency on dopaminergic neurodegeneration was not affected, indicating that Notch signaling might regulate neuroinflammation independent of CCR2+ monocyte infiltration. Notably, when microglia were depleted with the PLX5622 formulated diet, we found that myeloid-specific RBP-J knockout resulted in more TH+ neurons and fewer activated microglia. Ex vitro experiments demonstrated that RBP-J deficiency in microglia might reduce inflammatory factor secretion, TH+ neuron apoptosis, and p65 nuclear translocation. Collectively, our study first revealed that RBP-J-mediated Notch signaling might participate in PD progression by mainly regulating microglia activation through nuclear factor kappa-B (NF-κB) signaling.

Liang SQ ，Li PH ，Hu YY ，Zhao JL ，Shao FZ ，Kuang F ，Ren KX ，Wei TX ，Fan F ，Feng L ，Han H ，Qin HY ... -  《Frontiers in Immunology》

Myeloid-specific disruption of recombination signal binding protein Jκ ameliorates hepatic fibrosis by attenuating inflammation through cylindromatosis in mice.

Macrophages play multidimensional roles in hepatic fibrosis, but their control has not been fully understood. The Notch pathway mediated by recombination signal binding protein Jκ (RBP-J), the transcription factor transactivated by signals from four mammalian Notch receptors, is implicated in macrophage activation and plasticity. In this study, by using mouse hepatic fibrosis models, we show that myeloid-specific disruption of RBP-J resulted in attenuated fibrosis. The activation of hepatic stellate cells and production of profibrotic factors including platelet-derived growth factor (PDGF)-B and transforming growth factor beta1 (TGF-β1) reduced significantly in myeloid-specific RBP-J deficient mice. The infiltration of inflammatory cells and production of proinflammatory factors were reduced in liver of myeloid-specific RBP-J-deficient mice during fibrosis. In RBP-J-deficient macrophages, the nuclear factor kappa B (NF-κB) activation was remarkably attenuated as compared with the control. This could be attributed to the up-regulation of cylindromatosis (CYLD), a negative regulator of NF-κB, in Notch signal-compromised macrophages, because the knockdown of CYLD in RBP-J-deficient macrophages or overexpression of p65 in RBP-J knockdown cells both restored NF-κB activation and the production of proinflammatory and/or profibrotic factors by macrophages. In human hepatic fibrosis biopsies, stronger Notch activation is correlated with more severe fibrosis, which is accompanied by a lower level of CYLD but irrespective of etiological reasons. RBP-J-mediated Notch signaling is required for macrophages to promote hepatic fibrosis by up-regulation of NF-κB activation through CYLD.

He F ，Guo FC ，Li Z ，Yu HC ，Ma PF ，Zhao JL ，Feng L ，Li WN ，Liu XW ，Qin HY ，Dou KF ，Han H ... -  《-》

RBP-J regulates homeostasis and function of circulating Ly6C(lo) monocytes.

Notch-RBP-J signaling plays an essential role in the maintenance of myeloid homeostasis. However, its role in monocyte cell fate decisions is not fully understood. Here, we showed that conditional deletion of transcription factor RBP-J in myeloid cells resulted in marked accumulation of blood Ly6Clo monocytes that highly expressed chemokine receptor CCR2. Bone marrow transplantation and parabiosis experiments revealed a cell-intrinsic requirement of RBP-J for controlling blood Ly6CloCCR2hi monocytes. RBP-J-deficient Ly6Clo monocytes exhibited enhanced capacity competing with wildtype counterparts in blood circulation. In accordance with alterations of circulating monocytes, RBP-J deficiency led to markedly increased population of lung tissues with Ly6Clo monocytes and CD16.2+ interstitial macrophages. Furthermore, RBP-J deficiency-associated phenotypes could be genetically corrected by further deleting Ccr2 in myeloid cells. These results demonstrate that RBP-J functions as a crucial regulator of blood Ly6Clo monocytes and thus derived lung-resident myeloid populations, at least in part through regulation of CCR2.

Kou T ，Kang L ，Zhang B ，Li J ，Zhao B ，Zeng W ，Hu X ... -  《eLife》