Deficiency of Macf1 in osterix expressing cells decreases bone formation by Bmp2/Smad/Runx2 pathway

Microtubule actin cross‐linking factor 1 (Macf1) is a spectraplakin family member known to regulate cytoskeletal dynamics, cell migration, neuronal growth and cell signal transduction. We previously demonstrated that knockdown of Macf1 inhibited the differentiation of MC3T3‐E1 cell line. However, whether Macf1 could regulate bone formation in vivo is unclear. To study the function and mechanism of Macf1 in bone formation and osteogenic differentiation, we established osteoblast‐specific Osterix (Osx) promoter‐driven Macf1 conditional knockout mice (Macf1^f/fOsx‐Cre). The Macf1^f/fOsx‐Cre mice displayed delayed ossification and decreased bone mass. Morphological and mechanical studies showed deteriorated trabecular microarchitecture and impaired biomechanical strength of femur in Macf1^f/fOsx‐Cre mice. In addition, the differentiation of primary osteoblasts isolated from calvaria was inhibited in Macf1^f/fOsx‐Cre mice. Deficiency of Macf1 in primary osteoblasts inhibited the expression of osteogenic marker genes (Col1, Runx2 and Alp) and the number of mineralized nodules. Furthermore, deficiency of Macf1 attenuated Bmp2/Smad/Runx2 signalling in primary osteoblasts of Macf1^f/fOsx‐Cre mice. Together, these results indicated that Macf1 plays a significant role in bone formation and osteoblast differentiation by regulating Bmp2/Smad/Runx2 pathway, suggesting that Macf1 might be a therapeutic target for bone disease.     

Identification of novel susceptibility loci for non‐syndromic cleft lip with or without cleft palate

Although several genome‐wide association studies (GWAS) of non‐syndromic cleft lip with or without cleft palate (NSCL/P) have been reported, more novel association signals are remained to be exploited. Here, we performed an in‐depth analysis of our previously published Chinese GWAS cohort study with replication in an extra dbGaP case‐parent trios and another in‐house Nanjing cohort, and finally identified five novel significant association signals (rs11119445: 3’ of SERTAD4, P = 6.44 × 10⁻¹⁴; rs227227 and rs12561877: intron of SYT14, P = 5.02 × 10⁻¹³ and 2.80 × 10⁻¹¹, respectively; rs643118: intron of TRAF3IP3, P = 4.45 × 10⁻⁶; rs2095293: intron of NR6A1, P = 2.98 × 10⁻⁵). The mean (standard deviation) of the weighted genetic risk score (wGRS) from these SNPs was 1.83 (0.65) for NSCL/P cases and 1.58 (0.68) for controls, respectively (P = 2.67 × 10⁻¹⁶). Rs643118 was identified as a shared susceptible factor of NSCL/P among Asians and Europeans, while rs227227 may contribute to the risk of NSCL/P as well as NSCPO. In addition, sertad4 knockdown zebrafish models resulted in down‐regulation of sox2 and caused oedema around the heart and mandibular deficiency, compared with control embryos. Taken together, this study has improved our understanding of the genetic susceptibility to NSCL/P and provided further clues to its aetiology in the Chinese population.     

MiR‐155 promotes interleukin‐1β‐induced chondrocyte apoptosis and catabolic activity by targeting PIK3R1‐mediated PI3K/Akt pathway

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degradation, in which elevated chondrocyte apoptosis and catabolic activity play an important role. MicroRNA‐155 (miR‐155) has recently been shown to regulate apoptosis and catabolic activity in some pathological circumstances, yet, whether and how miR‐155 is associated with OA pathology remain unexplored. We report here that miR‐155 level is significantly up‐regulated in human OA cartilage biopsies and also in primary chondrocytes stimulated by interleukin‐1β (IL‐1β), a pivotal pro‐catabolic factor promoting cartilage degradation. Moreover, miR‐155 inhibition attenuates and its overexpression promotes IL‐1β‐induced apoptosis and catabolic activity in chondrocytes in vitro. We also demonstrate that the PIK3R1 (p85α regulatory subunit of phosphoinositide 3‐kinase (PI3K)) is a target of miR‐155 in chondrocytes, and more importantly, PIK3R1 restoration abrogates miR‐155 effects on chondrocyte apoptosis and catabolic activity. Mechanistically, PIK3R1 positively regulates the transduction of PI3K/Akt pathway, and a specific Akt inhibitor reverses miR‐155 effects on promoting chondrocyte apoptosis and catabolic activity, phenocopying the results obtained via PIK3R1 knockdown, hence establishing that miR‐155 promotes chondrocyte apoptosis and catabolic activity through targeting PIK3R1‐mediated PI3K/Akt pathway activation. Altogether, our study discovers novel roles and mechanisms of miR‐155 in regulating chondrocyte apoptosis and catabolic activity, providing an implication for therapeutically intervening cartilage degradation and OA progression.     

Reduced Sirtuin1 signalling exacerbates diabetic mice hindlimb ischaemia injury and inhibits the protective effect of a liver X receptor agonist

Diabetes mellitus causes endothelial dysfunction, which further exacerbates peripheral arterial disease (PAD). Improving endothelial function via reducing endothelial oxidative stress (OS) may be a promising therapy for diabetic PAD. Activation of liver X receptor (LXR) inhibits excessive OS and provides protective effects on endothelial cells in diabetic individuals. Therefore, we investigated the effects of LXR agonist treatment on diabetic PAD with a focus on modulating endothelial OS. We used a streptozotocin-induced diabetes mouse model combined with a hindlimb ischaemia (HLI) injury to mimic diabetic PAD, which was followed by LXR agonist treatment. In our study, the LXR agonist T0901317 protected against HLI injury in diabetic mice by attenuating endothelial OS and stimulating angiogenesis. However, a deficiency in endothelial Sirtuin1 (SIRT1) largely inhibited the therapeutic effects of T0901317. Furthermore, we found that the underlying therapeutic mechanisms of T0901317 were related to SIRT1 and non-SIRT1 signalling, and the isoform LXRβ was involved in LXR agonist-elicited SIRT1 regulation. In conclusion, LXR agonist treatment protected against HLI injury in diabetic mice via mitigating endothelial OS and stimulating cellular viability and angiogenesis by LXRβ, which elicited both SIRT1-mediated and non-SIRT1-mediated signalling pathways. Therefore, LXR agonist treatment may be a promising therapeutic strategy for diabetic PAD.     

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.     

Endothelial S1pr1 regulates pressure overload‐induced cardiac remodelling through AKT‐eNOS pathway

Cardiac vascular microenvironment is crucial for cardiac remodelling during the process of heart failure. Sphingosine 1‐phosphate (S1P) tightly regulates vascular homeostasis via its receptor, S1pr1. We therefore hypothesize that endothelial S1pr1 might be involved in pathological cardiac remodelling. In this study, heart failure was induced by transverse aortic constriction (TAC) operation. S1pr1 expression is significantly increased in microvascular endothelial cells (ECs) of post‐TAC hearts. Endothelial‐specific deletion of S1pr1 significantly aggravated cardiac dysfunction and deteriorated cardiac hypertrophy and fibrosis in myocardium. In vitro experiments demonstrated that S1P/S1pr1 praxis activated AKT/eNOS signalling pathway, leading to more production of nitric oxide (NO), which is an essential cardiac protective factor. Inhibition of AKT/eNOS pathway reversed the inhibitory effect of EC‐S1pr1‐overexpression on angiotensin II (AngII)‐induced cardiomyocyte (CM) hypertrophy, as well as on TGF‐β‐mediated cardiac fibroblast proliferation and transformation towards myofibroblasts. Finally, pharmacological activation of S1pr1 ameliorated TAC‐induced cardiac hypertrophy and fibrosis, leading to an improvement in cardiac function. Together, our results suggest that EC‐S1pr1 might prevent the development of pressure overload‐induced heart failure via AKT/eNOS pathway, and thus pharmacological activation of S1pr1 or EC‐targeting S1pr1‐AKT‐eNOS pathway could provide a future novel therapy to improve cardiac function during heart failure development.     

Structure Elucidation of Two New Norlignans from Anemone vitifolia and Their Anti‐Inflammatory Activities

Two new norlignans together with two known phenylpropanoids were isolated from the whole herb of Anemone vitifolia. All compounds were reported from this plant for the first time. The structures of these compounds were identified by comprehensive HR‐ESI‐MS, 1D and 2D NMR spectroscopic data analysis and comparison with literature data. Additionally, bioactivity study results showed that two new compounds have potential anti‐inflammatory activity. The plausible biosynthetic pathway for these compounds were also speculated in this article.