Regulatory role and translational potential of CCL11 in liver fibrosis.

BACKGROUND AND AIMS: Myofibroblasts are considered the major effector cell type of liver fibrosis and primarily derived from hepatic stellate cells (HSCs). In the present study, we investigated the contribution of C-C motif chemokine (CCL11) to HSC-myofibroblast trans -differentiation and its implication in liver fibrosis. APPROACH AND RESULTS: We report that CCL11 levels were elevated in HSCs, but not in hepatocytes or Kupffer cells, isolated from mice with liver fibrosis compared with the control mice. CCL11 levels were also up-regulated by 2 pro-fibrogenic growth factors TGF-ß and platelet derived growth factor in cultured HSCs. Mechanistically, zinc finger factor 281 bound to the CCL11 promoter and mediated CCL11 trans -activation in HSCs. Depletion of CCL11 attenuated whereas treatment with recombinant CCL11 promoted HSC activation. Further, global CCL11 deletion ( CCL11-/- ) or HSC/myofibroblast-specific CCL11 knockdown mitigated fibrogenesis in mice. RNA-sequencing revealed that CCL11 might regulate HSC activation by stimulating the transcription of Jagged 1. Reconstitution of Jagged 1 restored the fibrogenic response in CCL11-/- mice. Finally, several targeting strategies that aimed at blockading CCL11 signaling, either by administration of an antagonist to its receptor C-C motif chemokine receptor 3 or neutralizing antibodies against CCL11/C-C motif chemokine receptor 3, ameliorated liver fibrosis in mice. CONCLUSIONS: Our data unveil a previously unrecognized role for CCL11 in liver fibrosis and provide proof-of-concept evidence that targeting CCL11 can be considered as an effective therapeutic approach.

H3K36 methyltransferase NSD1 is essential for normal B1 and B2 cell development and germinal center formation.

B cells, which consist of two well-defined populations: B1 and B2 cells, which can produce antibodies that are essential for host protection against infections, through virus neutralization, opsonization and antibody-dependent cellular cytotoxicity. Epigenetic modifications, such as DNA methylation and histone modification could regulate immune cell differentiation and functions. In this study, we found a significant reduction of GC response in the B cell specific knockout of H3K36 methyltransferase NSD1 (Mb1-Cre+ NSD1fl/fl, NSD1B KO) mice compared with the wildtype control (Mb1-Cre+ NSD1+/+, NSD1B WT). We also demonstrated reduced production of high-affinity antibody, but increased production of low-affinity antibody in the NSD1B KO mice. Further analysis revealed that loss of NSD1 promoted the development of B1 cells by increasing the expression of Rap1b and Arid3a. In conclusion, our data suggest that NSD1 plays an important role in regulation the development of B1 and B2 cells, and the process of germinal center formation and high-affinity antibody production.

Brahma-Related Gene 1 Deficiency in Endothelial Cells Ameliorates Vascular Inflammatory Responses in Mice.

Endothelial dysfunction plays an important role in promoting the progression of disease genesis such as atherosclerosis and abdominal aortic aneurysm (AAA). The physiological unbalance of endothelial cells is a major pathological basis. In this present study, we investigated Brahma-related gene 1 (BRG1), a chromatin remodeling protein, was in mouse models of diabetic atherosclerosis and AAA, focusing on its role in endothelial dysfunction. We report that compared with their wild-type (WT, ApoE -/- ; BRG1 fl/fl ) littermates, endothelium conditional BRG1 knockout mice (CKO, ApoE -/- ; BRG1 fl/fl ; CDH5-cre) exhibited an alleviated phenotype of diabetic atherosclerosis. Immunohistochemically staining and real-time PCR analysis demonstrated fewer macrophages recruitment with a reduction of vascular inflammatory in CKO mice compared with WT mice. Further research in the Ang-II induced AAA model revealed that BRG1 deficiency had the protective effects on endothelium conditional BRG1 deletion, evidenced by the downregulation of pro-inflammatory mediators [interleukin (IL)-1ß and IL-6, not tumor necrosis factor-α (TNF-α)] in the vessels of CKO mice compared with WT mice. In Ea.hy926 cell lines, anti-BRG1 small interfering RNA and PFI-3 treatment obviously alleviated tumor necrosis factor-α-induced IL-6 and CCL2 expression, and further research demonstrated that the BRG1 inhibition in endothelial cells not only decreased c-Fos expression but also blocked the c-Fos translocation into nuclei. In conclusion, our results suggest that endothelial BRG1 deficiency may protect the mice from diabetic atherosclerosis and AAA via inhibiting inflammatory response in vessels.

BRG1 Activates PR65A Transcription to Regulate NO Bioavailability in Vascular Endothelial Cells.

Vascular endothelial cells contribute to the pathogenesis of cardiovascular diseases by producing and disseminating angiocrine factors. Nitric oxide (NO), catalyzed by endothelial NO synthase (eNOS), is one of the prototypical angiocrine factors. eNOS activity is modulated by site-specific phosphorylation. We have previously shown that endothelial-specific knockdown of BRG1 in Apoe -/- mice attenuates the development of atherosclerosis, in which eNOS-dependent NO catalysis plays an antagonizing role. Here we report that attenuation of atherogenesis in mice by BRG1 knockdown was accompanied by partial restoration of NO biosynthesis by 44% in the arteries and a simultaneous up-regulation of eNOS serine 1177 phosphorylation by 59%. Indeed, BRG1 depletion or inhibition ameliorated oxLDL-induced loss of NO bioavailability and eNOS phosphorylation in cultured endothelial cells. Further analysis revealed that BRG1 regulated eNOS phosphorylation and NO synthesis by activating the transcription of protein phosphatase 2A (PP2A) structural subunit a (encoded by PR65A). BRG1 interacted with ETS1, was recruited by ETS1 to the PR65A promoter, and cooperated with ETS1 to activate PR65A transcription. Finally, depletion of ETS1, similar to BRG1, repressed PR65A induction, normalized eNOS phosphorylation, and rescued NO biosynthesis in endothelial cells treated with oxLDL. In conclusion, our data characterize a novel transcriptional cascade that regulates NO bioavailability in vascular endothelial cells.