Transmembrane adaptor protein WBP1L regulates CXCR4 signalling and murine haematopoiesis

WW domain binding protein 1‐like (WBP1L), also known as outcome predictor of acute leukaemia 1 (OPAL1), is a transmembrane adaptor protein, expression of which correlates with ETV6‐RUNX1 (t(12;21)(p13;q22)) translocation and favourable prognosis in childhood leukaemia. It has a broad expression pattern in haematopoietic and in non‐haematopoietic cells. However, its physiological function has been unknown. Here, we show that WBP1L negatively regulates signalling through a critical chemokine receptor CXCR4 in multiple leucocyte subsets and cell lines. We also show that WBP1L interacts with NEDD4‐family ubiquitin ligases and regulates CXCR4 ubiquitination and expression. Moreover, analysis of Wbp1l‐deficient mice revealed alterations in B cell development and enhanced efficiency of bone marrow cell transplantation. Collectively, our data show that WBP1L is a novel regulator of CXCR4 signalling and haematopoiesis.     

Interleukin‐38 protects against sepsis by augmenting immunosuppressive activity of CD4+CD25+ regulatory T cells

Naturally occurring CD4⁺CD25⁺ regulatory T cells (Tregs) are required to limit immune‐induced pathology and to maintain homeostasis during the early‐phase of sepsis. This study aimed to investigate the role of interleukin (IL)‐38, a newly described member of the IL‐1 cytokine family, in mediated immune response of CD4⁺CD25⁺ Tregs in sepsis. Here, we provide evidence that expressions of IL‐38 and its receptor were detected in murine CD4⁺CD25⁺ Tregs. Stimulation of CD4⁺CD25⁺ Tregs with LPS markedly up‐regulated the expression of IL‐38. Treatment with rmIL‐38 dramatically enhanced the immunosuppressive activity of CD4⁺CD25⁺ Tregs after LPS stimulation and in septic mice induced by CLP, resulting in amplification of helper T cell (Th) 2 response and reduction in the proliferation of effector T cells. These effects were robustly abrogated when anti–IL‐38 antibody was administered. Administration of rmIL‐38 improved the survival rate of CLP mice. In addition, CD4⁺CD25⁺ Tregs depletion before the onset of sepsis obviously abolished IL‐38–mediated protective response. These findings suggest that IL‐38 enhances the immunosuppressive activity of CD4⁺CD25⁺ Tregs, which might contribute to the improvement of host immune function and prognosis in the setting of sepsis.     

Effect of c‐Ski on atrial remodelling in a rapid atrial pacing canine model

Atrial fibrosis is an important factor in the initiation and maintenance of atrial fibrillation (AF); therefore, understanding the pathogenesis of atrial fibrosis may reveal promising therapeutic targets for AF. In this study, we successfully established a rapid atrial pacing canine model and found that the inducibility and duration of AF were significantly reduced by the overexpression of c‐Ski, suggesting that this approach may have therapeutic effects. c‐Ski was found to be down‐regulated in the atrial tissues of the rapid atrial pacing canine model. We artificially up‐regulated c‐Ski expression with a c‐Ski–overexpressing adenovirus. Haematoxylin and eosin, Masson's trichrome and picrosirius red staining showed that c‐Ski overexpression alleviated atrial fibrosis. Furthermore, we found that the expression levels of collagen III and α‐SMA were higher in the groups of dogs subjected to right‐atrial pacing, and this increase was attenuated by c‐Ski overexpression. In addition, c‐Ski overexpression decreased the phosphorylation of smad2, smad3 and p38 MAPK (p38α and p38β) as well as the expression of TGF‐β1 in atrial tissues, as shown by a comparison of the right‐atrial pacing + c‐Ski‐overexpression group to the control group with right‐atrial pacing only. These results suggest that c‐Ski overexpression improves atrial remodelling in a rapid atrial pacing canine model by suppressing TGF‐β1–Smad signalling and p38 MAPK activation.     

Mouse genetics identifies unique and overlapping functions of fibroblast growth factor receptors in keratinocytes

Fibroblast growth factors (FGFs) are key regulators of tissue development, homeostasis and repair, and abnormal FGF signalling is associated with various human diseases. In human and murine epidermis, FGF receptor 3 (FGFR3) activation causes benign skin tumours, but the consequences of FGFR3 deficiency in this tissue have not been determined. Here, we show that FGFR3 in keratinocytes is dispensable for mouse skin development, homeostasis and wound repair. However, the defect in the epidermal barrier and the resulting inflammatory skin disease that develops in mice lacking FGFR1 and FGFR2 in keratinocytes were further aggravated upon additional loss of FGFR3. This caused fibroblast activation and fibrosis in the FGFR1/FGFR2 double‐knockout mice and even more in mice lacking all three FGFRs, revealing functional redundancy of FGFR3 with FGFR1 and FGFR2 for maintaining the epidermal barrier. Taken together, our study demonstrates that FGFR1, FGFR2 and FGFR3 act together to maintain epidermal integrity and cutaneous homeostasis, with FGFR2 being the dominant receptor.     

LncRNA H19 ameliorates myocardial infarction‐induced myocardial injury and maladaptive cardiac remodelling by regulating KDM3A

Myocardial infarction (MI) remains the leading cause of morbidity and mortality worldwide, and novel therapeutic targets still need to be investigated to alleviate myocardial injury and the ensuing maladaptive cardiac remodelling. Accumulating studies have indicated that lncRNA H19 might exert a crucial regulatory effect on cardiovascular disease. In this study, we aimed to explore the biological function and molecular mechanism of H19 in MI. To investigate the biological functions of H19, miRNA‐22‐3p and KDM3A, gain‐ and loss‐of‐function experiments were performed. In addition, bioinformatics analysis, dual‐luciferase reporter assays, RNA immunoprecipitation (RIP) assays, RNA pull‐down assays, quantitative RT‐PCR and Western blot analyses as well as rescue experiments were conducted to reveal an underlying competitive endogenous RNA (ceRNA) mechanism. We found that H19 was significantly down‐regulated after MI. Functionally, enforced H19 expression dramatically reduced infarct size, improved cardiac performance and alleviated cardiac fibrosis by mitigating myocardial apoptosis and decreasing inflammation. However, H19 knockdown resulted in the opposite effects. Bioinformatics analysis and dual‐luciferase assays revealed that, mechanistically, miR‐22‐3p was a direct target of H19, which was also confirmed by RIP and RNA pull‐down assays in primary cardiomyocytes. In addition, bioinformatics analysis and dual‐luciferase reporter assays also demonstrated that miRNA‐22‐3p directly targeted the KDM3A gene. Moreover, subsequent rescue experiments further verified that H19 regulated the expression of KDM3A to ameliorate MI‐induced myocardial injury in a miR‐22‐3p‐dependent manner. The present study revealed the critical role of the lncRNAH19/miR‐22‐3p/KDM3A pathway in MI. These findings suggest that H19 may act as a potential biomarker and therapeutic target for MI.     

ATPR triggers acute myeloid leukaemia cells differentiation and cycle arrest via the RARα/LDHB/ERK‐glycolysis signalling axis

Acute myeloid leukaemia (AML) remains a therapeutic challenge and improvements in chemotherapy are needed. 4‐Amino‐2‐trifluoromethyl‐phenyl retinate (ATPR), a novel all‐trans retinoic acid (ATRA) derivative designed and synthesized by our team, has been proven to show superior anticancer effect compared with ATRA on various cancers. However, its potential effect on AML remains largely unknown. Lactate dehydrogenase B (LDHB) is the key glycolytic enzyme that catalyses the interconversion between pyruvate and lactate. Currently, little is known about the role of LDHB in AML. In this study, we found that ATPR showed antileukaemic effects with RARα dependent in AML cells. LDHB was aberrantly overexpressed in human AML peripheral blood mononuclear cell (PBMC) and AML cell lines. A lentiviral vector expressing LDHB‐targeting shRNA was constructed to generate a stable AML cells with low expression of LDHB. The effect of LDHB knockdown on differentiation and cycle arrest of AML cells was assessed in vitro and vivo, including involvement of Raf/MEK/ERK signalling. Finally, these data suggested that ATPR showed antileukaemic effects by RARα/LDHB/ ERK‐glycolysis signalling axis. Further studies should focus on the underlying leukaemia‐promoting mechanisms and investigate LDHB as a therapeutic target.     

Defibrotide inhibits donor leucocyte‐endothelial interactions and protects against acute graft‐versus‐host disease

Allogeneic hematopoietic stem cell transplantation (allo‐HCT) is an effective therapy for the treatment of high‐risk haematological malignant disorders and other life‐threatening haematological and genetic diseases. Acute graft‐versus‐host disease (aGvHD) remains the most frequent cause of non‐relapse mortality following allo‐HCT and limits its extensive clinical application. Current pharmacologic agents used for prophylaxis and treatment of aGvHD are not uniformly successful and have serious secondary side effects. Therefore, more effective and safe prophylaxis and therapy for aGvHD are an unmet clinical need. Defibrotide is a multi‐target drug successfully employed for prophylaxis and treatment of veno‐occlusive disease/sinusoidal obstruction syndrome. Recent preliminary clinical data have suggested some efficacy of defibrotide in the prevention of aGvHD after allo‐HCT. Using a fully MHC‐mismatched murine model of allo‐HCT, we report here that defibrotide, either in prophylaxis or treatment, is effective in preventing T cell and neutrophil infiltration and aGvHD‐associated tissue injury, thus reducing aGvHD incidence and severity, with significantly improved survival after allo‐HCT. Moreover, we performed in vitro mechanistic studies using human cells revealing that defibrotide inhibits leucocyte‐endothelial interactions by down‐regulating expression of key endothelial adhesion molecules involved in leucocyte trafficking. Together, these findings provide evidence that defibrotide may represent an effective and safe clinical alternative for both prophylaxis and treatment of aGvHD after allo‐HCT, paving the way for new therapeutic approaches.     

Epigenetic silencing of LncRNA ANRIL enhances liver fibrosis and HSC activation through activating AMPK pathway

Long non‐coding RNAs (LncRNAs) and DNA methylation are important epigenetic mark play a key role in liver fibrosis. Currently, how DNA methylation and LncRNAs control the hepatic stellate cell (HSC) activation and fibrosis has not yet been fully characterized. Here, we explored the role of antisense non‐coding RNA in the INK4 locus (ANRIL) and DNA methylation in HSC activation and fibrosis. The expression levels of DNA methyltransferases 3A (DNMT3A), ANRIL, α‐Smooth muscle actin (α‐SMA), Type I collagen (Col1A1), adenosine monophosphate‐activated protein kinase (AMPK) and p‐AMPK in rat and human liver fibrosis were detected by immunohistochemistry, qRT‐PCR and Western blotting. Liver tissue histomorphology was examined by haematoxylin and eosin (H&E), Sirius red and Masson staining. HSC was transfected with DNMT3A‐siRNA, over‐expressing ANRIL and down‐regulating ANRIL. Moreover, cell proliferation ability was examined by CCK‐8, MTT and cell cycle assay. Here, our study demonstrated that ANRIL was significantly decreased in activated HSC and liver fibrosis tissues, while Col1A1, α‐SMA and DNMT3A were significantly increased in activated HSC and liver fibrosis tissues. Further, we found that down‐regulating DNMT3A expression leads to inhibition of HSC activation. Reduction in DNMT3A elevated ANRIL expression in activated HSC. Furthermore, we performed the over expression ANRIL suppresses HSC activation and AMPK signalling pathways. In sum, our study found that epigenetic DNMT3A silencing of ANRIL enhances liver fibrosis and HSC activation through activating AMPK pathway. Targeting epigenetic modulators DNMT3A and ANRIL, and offer a novel approach for liver fibrosis therapy.