An Update on the Emerging Role of Visfatin in the Pathogenesis of Osteoarthritis and Pharmacological Intervention

The Role of Adipokines between Genders in the Pathogenesis of Osteoarthritis

Osteoarthritis (OA) is a chronic, progressive, degenerative joint disease characterized by joint pain, stiffness, and limited movement. It presents significant intra- and inter-individual variability-in particular, between genders. Recent research has increasingly focused on the role of adipokines-especially leptin, adiponectin, and resistin-in the development of OA. Adipokines, peptide hormones primarily secreted by adipose tissue, are involved in crucial physiological processes related to metabolism and immunity. They can also impact bone and cartilage turnover by interacting with joint cells such as osteoblasts, osteoclasts, chondrocytes, and mesenchymal stem cells, thereby linking inflammation with bone cartilage homeostasis. This review aims to elucidate the structure and functions of various adipokines, their serum and synovial levels, and their association with clinical presentation and radiographic progression in OA patients, with a focus on differences between sexes. A narrative literature review was conducted using three databases specifically analyzing sex differences. OA patients generally show elevated serum and synovial levels of leptin, chemerin, and visfatin, as well as high plasma levels of resistin and visfatin. In contrast, synovial levels of adiponectin and omentin are reduced in OA patients compared to healthy individuals, with an inverse relationship to disease severity, suggesting a potential protective role. Resistin and leptin were positively correlated with pain severity and radiographic progression, while adiponectin's role in OA remains controversial. Regarding sex differences, male OA patients exhibited higher serum levels of leptin, chemerin, and omentin compared to healthy controls, with a positive correlation to the BMI and estrogen levels, potentially explaining the sexual dimorphism observed in this condition. Studies on visfatin and lipocalin did not reveal significant differences in synovial or serum levels between the sexes. The role of resistin remains controversial. Adipokines influence the joint microenvironment and contribute to the progression of osteoarthritis (OA). However, the precise biological mechanisms are not yet fully understood due to the complex interactions between the metabolic, mechanical, and immune systems. Further research is needed to clarify their roles in OA and to identify targeted therapies for managing this degenerative disease.

The role of adipokines in osteoporosis management: a mini review

The prevalence of osteoporosis has been on the rise globally. With ageing populations, research has sought therapeutic solutions in novel areas. One such area is that of the adipokines. Current literature points to an important role for these chemical mediators in relation to bone metabolism. Well-established adipokines have been broadly reported upon. These include adiponectin and leptin. However, other novel adipokines such as visfatin, nesfatin-1, meteorin-like protein (Metrnl), apelin and lipocalin-2 are starting to be addressed pre-clinically and clinically. Adipokines hold pro-inflammatory and anti-inflammatory properties that influence the pathophysiology of various bone diseases. Omentin-1 and vaspin, two novel adipokines, share cardioprotective effects and play essential roles in bone metabolism. Studies have reported bone-protective effects of omentin-1, whilst others report negative associations between omentin-1 and bone mineral density. Lipocalin-2 is linked to poor bone microarchitecture in mice and is even suggested to mediate osteoporosis development from prolonged disuse. Nesfatin-1, an anorexigenic adipokine, has been known to preserve bone density. Animal studies have demonstrated that nesfatin-1 treatment limits bone loss and increases bone strength, suggesting exogenous use as a potential treatment for osteopenic disorders. Pre-clinical studies have shown adipokine apelin to have a role in bone metabolism, mediated by the enhancement of osteoblast genesis and the inhibition of programmed cell death. Although many investigations have reported conflicting findings, sufficient literature supports the notion that adipokines have a significant influence on the metabolism of bone. This review aims at highlighting the role of novel adipokines in osteoporosis while also discussing their potential for treating osteoporosis.

Obesity, Metabolic Syndrome, and Osteoarthritis-An Updated Review

PURPOSE OF REVIEW

Metabolic syndrome (MetS), also called the 'deadly quartet' comprising obesity, diabetes, dyslipidemia, and hypertension, has been ascertained to have a causal role in the pathogenesis of osteoarthritis (OA). This review is aimed at discussing the current knowledge on the contribution of metabolic syndrome and its various components to OA pathogenesis and progression.

RECENT FINDINGS

Lately, an increased association identified between the various components of metabolic syndrome (obesity, diabetes, dyslipidemia, and hypertension) with OA has led to the identification of the 'metabolic phenotype' of OA. These metabolic perturbations alongside low-grade systemic inflammation have been identified to inflict detrimental effects upon multiple tissues of the joint including cartilage, bone, and synovium leading to complete joint failure in OA. Recent epidemiological and clinical findings affirm that adipokines significantly contribute to inflammation, tissue degradation, and OA pathogenesis mediated through multiple signaling pathways. OA is no longer perceived as just a 'wear and tear' disease and the involvement of the metabolic components in OA pathogenesis adds up to the complexity of the disease. Given the global surge in obesity and its allied metabolic perturbations, this review aims to throw light on the current knowledge on the pathophysiology of MetS-associated OA and the need to address MetS in the context of metabolic OA management. Better regulation of the constituent factors of MetS could be profitable in preventing MetS-associated OA. The identification of key roles for several metabolic regulators in OA pathogenesis has also opened up newer avenues in the recognition and development of novel therapeutic agents.

Beyond mechanical loading: The metabolic contribution of obesity in osteoarthritis unveils novel therapeutic targets

Osteoarthritis (OA) is a prevalent progressive disease that frequently coexists with obesity. For several decades, OA was thought to be the result of ageing and mechanical stress on cartilage. Researchers' perspective has been greatly transformed when cumulative findings emphasized the role of adipose tissue in the diseases. Nowadays, the metabolic effect of obesity on cartilage tissue has become an integral part of obesity research; hoping to discover a disease-modifying drug for OA. Recently, several adipokines have been reported to be associated with OA. Particularly, metrnl (meteorin-like) and retinol-binding protein 4 (RBP4) have been recognized as emerging adipokines that can mediate OA pathogenesis. Accordingly, in this review, we will summarize the latest findings concerned with the metabolic contribution of obesity in OA pathogenesis, with particular emphasis on dyslipidemia, insulin resistance and adipokines. Additionally, we will discuss the most recent adipokines that have been reported to play a role in this context. Careful consideration of these molecular mechanisms interrelated with obesity and OA will undoubtedly unveil new avenues for OA treatment.

Macrophage-Driven Inflammation in Metabolic Osteoarthritis: Implications for Biomarker and Therapy Development

Osteoarthritis (OA) is a common and debilitating joint disorder that leads to progressive joint breakdown and loss of articular cartilage. Accompanied by a state of low-grade inflammation, its etiology extends beyond that of a wear-and-tear disease, and the immune system might have a role in its initiation and progression. Obesity, which is directly associated with an increased incidence of OA, alters adipokine release, increases pro-inflammatory macrophage activity, and affects joint immune regulation. Studying inflammatory macrophage expression and strategies to inhibit inflammatory macrophage phenotype polarization might provide insights into disease pathogenesis and therapeutic applications. In pre-clinical studies, the detection of OA in its initial stages was shown to be possible using imaging techniques such as SPECT-CT, and advances are made to detect OA through blood-based biomarker analysis. In this review, obesity-induced osteoarthritis and its mechanisms in inducing joint degeneration are summarized, along with an analysis of the current developments in patient imaging and biomarker use for diagnostic and therapeutic strategies.

Effects of Visfatin on Intracellular Mechanics and Catabolism in Human Primary Chondrocytes through Glycogen Synthase Kinase 3β Inactivation

Osteoarthritis (OA) is still a recalcitrant musculoskeletal disease on account of its complex biochemistry and mechanical stimulations. Apart from stimulation by external mechanical forces, the regulation of intracellular mechanics in chondrocytes has also been linked to OA development. Recently, visfatin has received significant attention because of the clinical finding of the positive correlation between its serum/synovial level and OA progression. However, the precise mechanism involved is still unclear. This study determined the effect of visfatin on intracellular mechanics and catabolism in human primary chondrocytes isolated from patients. The intracellular stiffness of chondrocytes was analyzed by the particle-tracking microrheology method. It was shown that visfatin damages the microtubule and microfilament networks to influence intracellular mechanics to decrease the intracellular elasticity and viscosity via glycogen synthase kinase 3β (GSK3β) inactivation induced by p38 signaling. Further, microtubule network destruction in human primary chondrocytes is predominantly responsible for the catabolic effect of visfatin on the cyclooxygenase 2 upregulation. The present study shows a more comprehensive interpretation of OA development induced by visfatin through biochemical and biophysical perspectives. Finally, the role of GSK3β inactivation, and subsequent regulation of intracellular mechanics, might be considered as theranostic targets for future drug development for OA.

Exploring the Crosstalk between Hydrostatic Pressure and Adipokines: An In Vitro Study on Human Osteoarthritic Chondrocytes

Obesity is a risk factor for osteoarthritis (OA) development and progression due to an altered biomechanical stress on cartilage and an increased release of inflammatory adipokines from adipose tissue. Evidence suggests an interplay between loading and adipokines in chondrocytes metabolism modulation. We investigated the role of loading, as hydrostatic pressure (HP), in regulating visfatin-induced effects in human OA chondrocytes. Chondrocytes were stimulated with visfatin (24 h) and exposed to high continuous HP (24 MPa, 3 h) in the presence of visfatin inhibitor (FK866, 4 h pre-incubation). Apoptosis and oxidative stress were detected by cytometry, B-cell lymphoma (BCL)2, metalloproteinases (MMPs), type II collagen (Col2a1), antioxidant enzymes, miRNA, cyclin D1 expressions by real-time PCR, and β-catenin protein by western blot. HP exposure or visfatin stimulus significantly induced apoptosis, superoxide anion production, and MMP-3, -13, antioxidant enzymes, and miRNA gene expression, while reducing Col2a1 and BCL2 mRNA. Both stimuli significantly reduced β-catenin protein and increased cyclin D1 gene expression. HP exposure exacerbated visfatin-induced effects, which were counteracted by FK866 pre-treatment. Our data underline the complex interplay between loading and visfatin in controlling chondrocytes' metabolism, contributing to explaining the role of obesity in OA etiopathogenesis, and confirming the importance of controlling body weight for disease treatment.