Bone-muscle crosstalk under physiological and pathological conditions.

Anatomically connected bones and muscles determine movement of the body. Forces exerted on muscles are then turned to bones to promote osteogenesis. The crosstalk between muscle and bone has been identified as mechanotransduction previously. In addition to the mechanical features, bones and muscles are also secretory organs which interact closely with one another through producing myokines and osteokines. Moreover, besides the mechanical features, other factors, such as nutrition metabolism, physiological rhythm, age, etc., also affect bone-muscle crosstalk. What's more, osteogenesis and myogenesis within motor system occur almost in parallel. Pathologically, defective muscles are always detected in bone associated diseases and induce the osteopenia, inflammation and abnormal bone metabolism, etc., through biomechanical or biochemical coupling. Hence, we summarize the study findings of bone-muscle crosstalk and propose potential strategies to improve the skeletal or muscular symptoms of certain diseases. Altogether, functional improvement of bones or muscles is beneficial to each other within motor system.

NOR1 promotes the osteoblastic differentiation of human periodontal ligament stem cells via TGF-ß signaling pathway.

Alveolar bone loss is a main manifestation of periodontitis. Human periodontal ligament stem cells (PDLSCs) are considered as optimal seed cells for alveolar bone regeneration due to its mesenchymal stem cell like properties. Osteogenic potential is the premise for PDLSCs to repair alveolar bone loss. However, the mechanism regulating osteogenic differentiation of PDLSCs remain elusive. In this study, we identified Neuron-derived orphan receptor 1 (NOR1), was particularly expressed in PDL tissue in vivo and gradually increased during osteogenic differentiation of PDLSCs in vitro. Knockdown of NOR1 in hPDLSCs inhibited their osteogenic potential while NOR1 overexpression reversed this effect. In order to elucidate the downstream regulatory network of NOR1, RNA-sequencing was used. We found that downregulated genes were mainly enriched in TGF-ß, Hippo, Wnt signaling pathway. Further, by western blot analysis, we verified that the expression level of phosphorylated-SMAD2/3 and phosphorylated-SMAD4 were all decreased after NOR1 knockdown. Additionally, ChIP-qPCR and dual luciferase reporter assay indicated that NOR1 could bind to the promoter of TGFBR1 and regulate its activity. Moreover, overexpression of TGFBR1 in PDLSCs could rescue the damaged osteogenic potential after NOR1 knockdown. Taken together, our results demonstrated that NOR1 could activate TGF-ß/SMAD signaling pathway and positively regulates the commitment of osteoblast lineages of PDLSCs by targeting TGFBR1 directly.

Sensory nerve regulation of bone homeostasis: Emerging therapeutic opportunities for bone-related diseases.

Understanding the intricate interplay between sensory nerves and bone tissue cells is of paramount significance in the field of bone biology and clinical medicine. The regulatory role of sensory nerves in bone homeostasis offers a novel perspective for the development of targeted therapeutic interventions for a spectrum of bone-related diseases, including osteoarthritis, osteoporosis, and intervertebral disc degeneration. By elucidating the mechanisms through which sensory nerves and their neuropeptides influence the differentiation and function of bone tissue cells, this review aims to shed light on emerging therapeutic targets that harness the neuro-skeletal axis for the treatment and management of debilitating bone disorders. Moreover, a comprehensive understanding of sensory nerve-mediated bone regulation may pave the way for the development of innovative strategies to promote bone health and mitigate the burden of skeletal pathologies in clinical practice.

Albumin, an interesting and functionally diverse protein, varies from 'native' to 'effective' (Review).

Human serum albumins (HSAs) are synthesized in the liver and are the most abundant proteins in plasma of healthy human. They play an important role in the pathophysiological processes of the liver and even the whole organism. Previous studies have mainly focused on the regulation of HSAs' expression. However, with the progress of research in recent years, it has been found that the content of circulating albumin cannot fully reflect the biological function of albumin itself. Given the aforementioned fact, the concept of serum 'effective albumin concentration' has been proposed. It refers to the content of albumin that is structurally and functionally intact. Alterations in the molecular structure and function of albumin have been reported in a variety of diseases, including liver disease. Moreover, these changes have been verified to affect the progression of oxidative stress­related diseases. However, the link between albumin structure and function has not been fully elaborated, and the mechanisms by which different forms of albumin affect disease also need to be further investigated. In this context, the present review mainly expounded the biological characteristics and functions of albumin, summarized the different types of post­translational modification of albumin, and discussed their functional changes and possible mechanisms in non­alcoholic fatty liver disease, alcoholic hepatitis, viral hepatitis and different stages of cirrhosis. This will help to improve understanding of the role of albumin in disease development and provide a more comprehensive physiological basis for it in disease treatment.

Pharmacological Research Progress of Novel Antihypertensive Drugs.

Cardiovascular disease stands as the leading cause of death globally, with hypertension emerging as an independent risk factor for its development. The worldwide prevalence of hypertension hovers around 30%, encompassing a staggering 1.2 billion patients, and continues to escalate annually. Medication plays a pivotal role in managing hypertension, not only effectively regulating blood pressure (BP) but also substantially mitigating the occurrence of cardiovascular and cerebrovascular diseases. This review comprehensively outlines the categories, mechanisms, clinical applications, and drawbacks of conventional antihypertensive drugs. It delves into the five primary pharmacological classifications, namely ß-receptor blockers, calcium channel blockers (CCBs), angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), and diuretics. The emphasis is placed on elucidating the mechanisms, advantages, and research progress of novel antihypertensive drugs targeting emerging areas. These include mineralocorticoid receptor antagonists (MRAs), atrial natriuretic peptides (ANPs), neutral endopeptidase inhibitors (NEPIs), sodium-dependent glucose transporter 2 inhibitors (SGLT-2Is), glucagon-like peptide-1 receptor agonists (GLP-1RAs), endothelin receptor antagonists (ERAs), soluble guanylate cyclase (sGC) agonists, brain aminopeptidase A inhibitors (APAIs), and small interfering ribonucleic acids (siRNAs) targeting hepatic angiotensinogen. Compared to conventional antihypertensive drugs, these novel alternatives exhibit favorable antihypertensive effects with minimal adverse reactions. This review serves as a valuable reference for future research and the clinical application of antihypertensive drugs.

Phosphorylation of RGS16 at Tyr168 promote HBeAg-mediated macrophage activation by ERK pathway to accelerate liver injury.

Liver injury is closely associated with macrophage activation following HBV infection. Our previous study showed that only HBeAg, but not HBsAg and HBcAg, stably enhances inflammatory cytokine production in macrophages. And we also indicated that HBeAg could induce macrophage activation via TLR2 and thus aggravate the progression of liver fibrosis. However, the specific molecular mechanism of HBeAg in macrophage activation is not clear. We screened significantly overexpressed RGS16 from RNASeq results of HBeAg-stimulated macrophages and validated them with cellular assays, GSE83148 microarray dataset, and in clinical samples. Meanwhile, small interference, plasmid, and lentivirus transfection assays were used to establish cell models for knockdown and overexpression of RGS16, and q-PCR, ELISA, Transwell, and CCK-8 assays were used to analyze the role of RGS16 in HBeAg-induced macrophage activation. In addition, the upstream and downstream mechanisms of RGS16 in HBeAg-treated macrophage activation were explored using inhibitors, phostag gels, and RGS16 phosphorylation mutant plasmids. Finally, the effect of RGS16 on hepatic inflammation in murine tissues was evaluated by H&E staining, liver enzyme assay and immunofluorescence. RGS16 was significantly upregulated in HBeAg-induced macrophage activation, and its expression was enhanced with increasing HBeAg content and treatment time. Functional experiments showed that overexpression of RGS16 promoted the production of inflammatory factors TNF-α and IL-6 and boosted macrophage proliferation and migration, while knockdown of RGS16 exhibited the opposite effect. Mechanistically, we discovered that RGS16 is regulated by the TLR2/P38/STAT5 signaling pathway. Meanwhile, RGS16 enhanced ERK phosphorylation via its own Tyr168 phosphorylation to contribute to macrophage activation, thereby accelerating liver injury. Finally, in mice, overexpression of RGS16 markedly strengthened liver inflammation. HBeAg upregulates RGS16 expression through the TLR2-P38-STAT5 axis, and the upregulated expression of RGS16 enhances macrophage activation and accelerates liver injury by promoting ERK phosphorylation. In this process, phosphorylation of Tyr168 is necessary for RGS16 to function. KEY MESSAGES: RGS16 boosted HBeAg-induced macrophage inflammation, proliferation, and migration. Tyr168 phosphorylation of RGS16 affected by ERK promoted macrophage activation. HBeAg upregulated the expression of RGS16 through TLR2/P38/STAT5 signal pathway. RGS16 promoted liver injury by regulating macrophage functions in mouse model.

Reversal of cholestatic liver disease by the inhibition of sphingosine 1-phosphate receptor 2 signaling.

Aims: The objective of this study is to examine the impact of inhibiting Sphingosine 1-phosphate receptor 2 (S1PR2) on liver inflammation, fibrogenesis, and changes of gut microbiome in the context of cholestasis-induced conditions. Methods: The cholestatic liver injury model was developed by common bile duct ligation (CBDL). Sprague-Dawley rats were randomly allocated to three groups, sham operation, CBDL group and JTE-013 treated CBDL group. Biochemical and histological assessments were conducted to investigate the influence of S1PR2 on the modulation of fibrogenic factors and inflammatory infiltration. We conducted an analysis of the fecal microbiome by using 16S rRNA sequencing. Serum bile acid composition was evaluated through the utilization of liquid chromatography-mass spectrometry techniques. Results: In the BDL rat model, the study findings revealed a significant increase in serum levels of conjugated bile acids, accompanied by an overexpression of S1PR2. Treatment with the specific inhibitor of S1PR2, known as JTE-013, resulted in a range of specific effects on the BDL rats. These effects included the improvement of liver function, reduction of liver inflammation, inhibition of hepatocyte apoptosis, and suppression of NETosis. These effects are likely mediated through the TCA/S1PR2/NOX2/NLRP3 pathway. Furthermore, the administration of JTE-013 resulted in an augmentation of the diversity of the bacterial community's diversity, facilitating the proliferation of advantageous species while concurrently inhibiting the prevalence of detrimental bacteria. Conclusions: The results of our study suggest that the administration of JTE-013 may have a beneficial effect in alleviating cholestatic liver disease and restoring the balance of intestinal flora.

SH-Alb inhibits phenotype remodeling of pro-fibrotic macrophage to attenuate liver fibrosis through SIRT3-SOD2 axis.

Albumin has a variety of biological functions, such as immunomodulatory and antioxidant activity, which depends largely on its thiol activity. However, in clinical trials, the treatment of albumin by injection of commercial human serum albumin (HSA) did not achieve the desired results. Here, we constructed reduced modified albumin (SH-Alb) for in vivo and in vitro experiments to investigate the reasons why HSA did not achieve the expected effects. SH-Alb was found to delay the progression of liver fibrosis in mice by alleviating liver inflammation and oxidative stress. Although R-Alb also has some of the above roles, the effect of SH-Alb is more remarkable. Mechanism studies have shown that SH-Alb reduces the release of pro-inflammatory and pro-fibrotic cytokine through the mitogen-activated protein kinase (MAPK) signaling pathway. In addition, SH-Alb deacetylates SOD2, a key enzyme of mitochondrial reactive oxygen species (ROS) production, by promoting the expression of SIRT3, thereby reducing the accumulation of ROS. Finally, macrophages altered by R-Alb or SH-Alb can inhibit the activation of hepatic stellate cells and endothelial cells, further delaying the progression of liver fibrosis. These results indicate that SH-Alb can remodel the phenotype of macrophages, thereby affecting the intrahepatic microenvironment and delaying the process of liver fibrosis. It provides a good foundation for the application of albumin in clinical treatment.