Obesity, Metabolic Syndrome, and Osteoarthritis-An Updated Review

Synovial microenvironment in temporomandibular joint osteoarthritis: crosstalk with chondrocytes and potential therapeutic targets

Temporomandibular joint osteoarthritis (TMJOA) is considered to be a low-grade inflammatory disease involving multiple joint tissues. The crosstalk between synovium and cartilage plays an important role in TMJOA. Synovial cells are a group of heterogeneous cells and synovial microenvironment is mainly composed of synovial fibroblasts (SF) and synovial macrophages. In TMJOA, SF and synovial macrophages release a large number of inflammatory cytokines and extracellular vesicles and promote cartilage destruction. Cartilage wear particles stimulate SF proliferation and macrophages activation and exacerbate synovitis. In TMJOA, chondrocytes and synovial cells exhibit increased glycolytic activity and lactate secretion, leading to impaired chondrocyte matrix synthesis. Additionally, the synovium contains mesenchymal stem cells, which are the seed cells for cartilage repair in TMJOA. Co-culture of chondrocytes and synovial mesenchymal stem cells enhances the chondrogenic differentiation of stem cells. This review discusses the pathological changes of synovium in TMJOA, the means of crosstalk between synovium and cartilage, and their influence on each other. Based on the crosstalk between synovium and cartilage in TMJOA, we illustrate the treatment strategies for improving synovial microenvironment, including reducing cell adhesion, utilizing extracellular vesicles to deliver biomolecules, regulating cellular metabolism and targeting inflammatory cytokines.

Curcumenol regulates Histone H3K27me3 demethylases KDM6B affecting Succinic acid metabolism to alleviate cartilage degeneration in knee osteoarthritis

BACKGROUND

Cartilage metabolism dysregulation is a crucial driver in knee osteoarthritis (KOA). Modulating the homeostasis can mitigate the cartilage degeneration in KOA. Curcumenol, derived from traditional Chinese medicine Curcuma Longa L., has demonstrated potential in enhancing chondrocyte proliferation and reducing apoptosis. However, the specific mechanism of Curcumenol in treating KOA remains unclear. This study aimed to demonstrate the molecular mechanism of Curcumenol in treating KOA based on the transcriptomics and metabolomics, and both in vivo and in vitro experimental validations.

MATERIALS AND METHODS

In this study, a destabilization medial meniscus (DMM)-induced KOA mouse model was established. And the mice were intraperitoneally injected with Curcumenol at 4 and 8 mg/kg concentrations. The effects of Curcumenol on KOA cartilage and subchondral was evaluated using micro-CT, histopathology, and immunohistochemistry (IHC). In vitro, OA chondrocytes were induced with 10 μg/mL lipopolysaccharide (LPS) and treated with Curcumenol to evaluate the proliferation, apoptosis, and extracellular matrix (ECM) metabolism through CCK8 assay, flow cytometry, and chondrocyte staining. Furthermore, transcriptomics and metabolomics were utilized to identify differentially expressed genes (DEGs) and metabolites. Finally, integrating multi-omics analysis, virtual molecular docking (VMD), and molecular dynamics simulation (MDS), IHC, immunofluorescence (IF), PCR, and Western blot (WB) validation were conducted to elucidate the mechanism by which Curcumenol ameliorates KOA cartilage degeneration.

RESULTS

Curcumenol ameliorated cartilage destruction and subchondral bone loss in KOA mice, promoted cartilage repair, upregulated the expression of COL2 while downregulated MMP3, and improved ECM synthesis metabolism. Additionally, Curcumenol also alleviated the damage of LPS on the proliferation activity and suppressed apoptosis, promoted ECM synthesis. Transcriptomic analysis combined with weighted gene co-expression network analysis (WGCNA) identified a significant downregulation of 19 key genes in KOA. Metabolomic profiling showed that Curcumenol downregulates the expression of d-Alanyl-d-alanine, 17a-Estradiol, Glutathione, and Succinic acid, while upregulating Sterculic acid and Azelaic acid. The integrated multi-omics analysis suggested that Curcumenol targeted KDM6B to regulate downstream protein H3K27me3 expression, which inhibited methylation at the histone H3K27, consequently reducing Succinic acid levels and improving KOA cartilage metabolism homeostasis. Finally, both in vivo and in vitro findings indicated that Curcumenol upregulated KDM6B, suppressed H3K27me3 expression, and stimulated collagen II expression and ECM synthesis, thus maintaining cartilage metabolism homeostasis and alleviating KOA cartilage degeneration.

CONCLUSION

Curcumenol promotes cartilage repair and ameliorates cartilage degeneration in KOA by upregulating KDM6B expression, thereby reducing H3K27 methylation and downregulating Succinic Acid, restoring metabolic stability and ECM synthesis.

Deciphering the ameliorative effect of Aloe vera (L.) burm. F. extract on histopathological alterations in Streptozotocin-induced WNIN/GR-ob rats

ETHNOPHARMACOLOGICAL RELEVANCE

Natural products have emerged as a novel source in the management of non-communicable diseases, more so in diabetes mellitus and its comorbidities. Aloe vera is widely recognized for its anti-hyperglycemic and anti-hyperlipidemic properties and numerous researchers have identified component (s) from Aloe vera attributing to these therapeutic effects.

AIM OF THE STUDY

The current work was undertaken to gain insight into the protective effect of Aloe vera (L.) Burm. f. extract to study the cytoarchitecture/histopathological alterations in the target organs in mutant Obese WNIN/GR-Ob rats that were made frank diabetic with streptozotocin.

MATERIALS AND METHODS

Rats were divided into five groups. 1)WNIN-GR-Ob/control group 2)WNIN-GR-Ob treated with STZ 3)WNIN-GR-Ob + STZ + Sitagliptin 4)WNIN-GR-Ob + STZ + Aloe vera 5)WNIN-GR-Ob/control group + Aloe vera. Histopathological analysis of the pancreas, kidney, liver, and adipocytes was done after 4 weeks of treatment.

RESULTS

The histopathological examination of STZ-induced diabetic rats revealed significant changes in all the vital organs including cell infiltration, degeneration, and necrosis. Treatment with A. vera negated most of the histopathological changes seen in STZ induced rats. Sitagliptin-which served as a positive control in the present study-reversed the alterations seen in streptozotocin rats.

CONCLUSION

Considering the hypoglycaemic and hypolipidemic activities of Aloe vera that have been previously demonstrated by us, the present study further re-instates the therapeutic efficacy of Aloe vera towards vital organs. It was able to restore islet cells and reduce β-cell damage. In addition, it was also able to aid in kidney tubular regeneration and reverse the degenerative changes brought on by streptozotocin on liver. Further, Aloe vera treated group exhibited moderate hyperplasia with decreased size of adipocytes and reduced macrophage infiltration. Thus, our findings advocate its application as an important nutraceutical in the therapeutic management of diabetes mellitus and associated complications.

Two Members of Vitamin-K-Dependent Proteins, Gla-Rich Protein (GRP) and Matrix Gla Protein (MGP), as Possible New Players in the Molecular Mechanism of Osteoarthritis

Objectives: The pathophysiology of osteoarthritis is mainly unknown. Matrix Gla protein (MGP) and Gla-rich protein (GRP) are both vitamin-K-dependent mineralization inhibitors. In this study, we aimed to compare the levels of MGP and GRP in the synovial fluid of osteoarthritic (OA) and non-osteoarthritic (non-OA) knee joints. Materials and Methods: Two groups were formed, with one consisting of patients with OA and the other non-OA, serving as a control group. The non-OA group included individuals who had arthroscopic surgery for non-cartilage-related issues. In the OA group, all participants had undergone total knee arthroplasty because of grade 4 primary degenerative osteoarthritis. During the operation, at least 1 mL of knee synovial fluid was collected. The GRP and MGP levels in the synovial fluid were measured using an ELISA kit. Results: The mean age in the OA group (62.03 ± 11.53 years) was significantly higher than that in the non-OA group (47.70 ± 14.49 years; p = 0.0001). GRP levels were significantly higher in the OA group (419.61 ± 70.14 ng/mL) compared to the non-OA group (382.18 ± 62.34 ng/mL; p = 0.037). MGP levels were significantly higher in the OA group (67.76 ± 11.36 ng/mL) compared to the non-OA group (53.49 ± 18.28 ng/mL; p = 0.001). Calcium levels (Ca++) were also significantly higher in the OA group (12.89 ± 3.43 mg/dL) compared to the non-OA group (9.51 ± 2.15 mg/dL; p = 0.0001). There was a significantly positive correlation between MGP levels and age (p = 0.011, R = +0.335). Linear regression analysis was performed to determine the effect of age on MGP levels (p = 0.011, R-Square = 0.112). The dependent variable in this analysis was MGP (ng/mL), and age was the predictor. Conclusions: In conclusion, both GRP and MGP are potentially usable biomarkers in osteoarthritis. However, GRP seems to be more valuable because it is not associated with age. In the future, both proteins could provide important contributions to the diagnosis and treatment of osteoarthritis.

Association between cardiovascular health and all-cause mortality risk in patients with osteoarthritis

BACKGROUND

This study was to explore the relationship between cardiovascular health (CVH) and the risk of all-cause mortality in patients with osteoarthritis (OA).

METHODS

This cohort study retrieved the data of 3642 patients with OA aged ≥ 20 years from the 2007-2018 National Health and Nutrition Examination Survey (NHANES). CVH was evaluated based on Life's Essential 8 (LE8) includes diet, physical activity, nicotine exposure, sleep health, body mass index, blood lipids, blood glucose, and blood pressure. The outcome of all-cause mortality was assessed using the death certificate records of participants from the National Death Index. Variables that might affect all-cause mortality were used as covariates. The weighted univariate COX proportional hazards model was used to explore the association between each covariate and all-cause mortality. The weighted univariate and multivariate COX proportional hazards models were used to explore the association between different CVH levels and all-cause mortality. A restricted cubic spline (RCS) curve was plotted to show the association between different CVH levels and all-cause mortality in OA patients. Hazard ratio (HR) and 95% confidence interval (CI) were calculated.

RESULTS

Findings show that people with moderate CVH (HR = 0.67, 95% CI = 0.45-0.98) and high CVH (HR = 0.47, 95% CI = 0.26-0.87) were associated with reduced risk of all-cause mortality in patients with OA. The HR of all-cause mortality in patients with OA decreased by 0.12 as per 10 points increase of LE8 score (HR = 0.81, 95% CI = 0.73-0.90). The RCS curve revealed that the HR of all-cause mortality decreased with the increase in LE8 score. The survival probability of patients in the high CVH group was higher than the moderate CVH group and low CVH group (p = 0.002).

CONCLUSION

Moderate-to-high CVH is associated with a decreased risk of all-cause mortality in patients with OA. These findings might provide a reference for the formulation of prognosis improvement strategies for the management of patients with OA.

The involvement of signaling pathways in the pathogenesis of osteoarthritis: An update

Osteoarthritis (OA) is one of the most common disabling pathologies, characterized by joint pain and reduced function, significantly worsening the quality of life. Even if important progresses have been made in OA research, little is yet known about the precise cellular and molecular mechanisms underlying OA. Understanding dysregulated signaling networks and their crosstalk in OA may offer a strong opportunity for the development of combined targeted therapies. Hence, this review highlights the recent findings on the main pathways involved in OA development, including Wnt, Notch, Hedgehog, MAPK, AMPK, and JAK/STAT, providing insights on current targeted therapies in OA patients' management.

The translational potential of this article

The identification of key signaling pathways involved in OA development and the investigation of their signaling crosstalk could pave the way for more effective treatments and improved management of OA patients in the future.

Hydrogel-Based 3D Bioprinting Technology for Articular Cartilage Regenerative Engineering

Articular cartilage is an avascular tissue with very limited capacity of self-regeneration. Trauma or injury-related defects, inflammation, or aging in articular cartilage can induce progressive degenerative joint diseases such as osteoarthritis. There are significant clinical demands for the development of effective therapeutic approaches to promote articular cartilage repair or regeneration. The current treatment modalities used for the repair of cartilage lesions mainly include cell-based therapy, small molecules, surgical approaches, and tissue engineering. However, these approaches remain unsatisfactory. With the advent of three-dimensional (3D) bioprinting technology, tissue engineering provides an opportunity to repair articular cartilage defects or degeneration through the construction of organized, living structures composed of biomaterials, chondrogenic cells, and bioactive factors. The bioprinted cartilage-like structures can mimic native articular cartilage, as opposed to traditional approaches, by allowing excellent control of chondrogenic cell distribution and the modulation of biomechanical and biochemical properties with high precision. This review focuses on various hydrogels, including natural and synthetic hydrogels, and their current developments as bioinks in 3D bioprinting for cartilage tissue engineering. In addition, the challenges and prospects of these hydrogels in cartilage tissue engineering applications are also discussed.

Weight change patterns across adulthood are associated with the risk of osteoarthritis: a population-based study

BACKGROUND

Body weight has been recognized as a driving factor of osteoarthritis. Few studies had investigated the association between weight status across adulthood and risk of osteoarthritis (OA). This study investigates the association of weight change patterns across adulthood (lasting at least 25 years) with the risk of OA from the National Health and Nutrition Examination Survey (NHANES) 2013-2018.

METHODS

The study assessed the relationship between weight change across adulthood and OA in 7392 individuals aged > 50 spanning a minimum of 25 years. Multivariate linear regression analyses were utilized to detect the association between weight change patterns and self-reported OA. Restricted cubic splines (RCS) were used to examine the nonlinear relationship between absolute weight change and OA risk.

RESULTS

From 10 years ago to survey, the risk of OA was 1.34-fold (95% CI 1.07-1.68) in people changed from obese to non-obese, 1.61-fold (95% CI 1.29-2.00) in people change from non-obese to obese, and 1.82-fold (95% CI 1.49-2.22) in stable obese people compared with people who were at stable normal weight. Similar patterns were also observed at age 25 years to baseline and age 25 years to 10 years before the baseline. The dose-response association of RCS found a U-shaped relationship between absolute weight change and OA risk.

CONCLUSIONS

The study suggests that weight patterns across adulthood are associated with the risk of OA. These findings stressed important to maintain a normal weight throughout adulthood, especially to prevent ignored weight gain in early adulthood to reduce OA risk later.

The impact of diabetes status on pain and physical function following total joint arthroplasty for hip and knee osteoarthritis: variation by sex and body mass index

Few studies have examined diabetes impact on total joint arthroplasty (TJA) outcomes, with variable findings. We investigated the association between diabetes and post-TJA physical function and pain, examining whether diabetes impact differs by sex and BMI. Patient sample completed questionnaires within 3 months prior to hip or knee TJA for osteoarthritis (OA) and 1-year post-surgery. Surgical 'non-response' was defined as < 30% improvement in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function at 1-year. Two adjusted logistic regression models were estimated: (1) excluding, (2) including an interaction between diabetes, sex and BMI. The sample (626 hip, 754 knee) was 54.9% female, had mean BMI of 30.1, 13.0% reported diabetes. In adjusted models excluding an interaction, diabetes was not associated with non-response. However, a significant 3-way interaction (physical function: p = 0.003; pain: p = 0.006) between diabetes, sex, and BMI was found and was associated with non-response: non-response probability increased with increasing BMI in men with diabetes, but decreased with increasing BMI in women in diabetes. Findings suggest uncertainty in diabetes impact may be due to differential impacts by sex and BMI. A simple consideration of diabetes as present vs. absent may not be sufficient, with implications for the large TJA population.

Obesity and body mass index: Past and future considerations in osteoarthritis research

Obesity is an important topic for the osteoarthritis (OA) scientific community. However, the predominant use of body mass index (BMI) to define obesity in OA research is associated with uncertainties and limitations. These include an inability to discern fat and muscle mass, account for sex-differences in fat distribution, or identify adiposity-related health impairments. A focus on BMI in OA research may influence weight bias in clinical practice and impact disparities in access to effective OA treatments. To ensure that our understanding and approaches to improve health outcomes for individuals with or at risk for OA continues to advance in the next decade, future research will need to consider alternative measures beyond BMI for obesity identification and align with evolving obesity science. OA researchers must be aware of issues associated with weight stigma and work to minimize negative generalizations based on BMI.

The hypertrophy of the cervical ligamentum flavum results in incomplete paralysis of both lower limbs: A case report

INTRODUCTION

The occurrence of cervical spinal stenosis caused by single-segment hypertrophic folds of the non-calcified ligamentum flavum (LF) at a single level is exceedingly rare, with previous surgical interventions predominantly employing posterior approaches and open procedures. This case report presents an exceptional instance wherein a patient achieved satisfactory outcomes following endoscopic surgery, thereby furnishing valuable evidence supporting the feasibility of endoscopic treatment for cervical LF hypertrophy.

CASE PRESENTATION

The patient, a 66-year-old male, presented to our hospital with chronic cervical pain, bilateral lower limb weakness, and gait instability. Physical examination revealed significant tenderness in the cervical region, diminished muscle strength in both lower limbs with poor resistance against resistance testing, and unsteady ambulation even with the assistance of a walking aid.

CLINICAL DISCUSSION

The primary diagnosis considered was cervical spinal stenosis caused by hypertrophy of the LF at the C4/5 level. The patient underwent treatment using the "key-hole" technique under spinal endoscopy. Postoperative treatment included detumescence of the nerve and improvement of circulation.

CONCLUSIONS

LF hypertrophy could be the principal factor of cervical spinal stenosis inducing neurological symptoms. Endoscopic surgery can get satisfactory clinical effects on single-segment cervical LF hypertrophy, including a minimally invasive approach, less bleeding, reduced cervical spine stability, and rapid recovery, especially for elderly patients with diabetes.

A Review of Cyclic Phosphatidic Acid and Other Potential Therapeutic Targets for Treating Osteoarthritis

Osteoarthritis (OA), a chronic degenerative joint disease, is the most common form of arthritis. OA occurs when the protective cartilage that cushions the ends of bones gradually breaks down. This leads to the rubbing of bones against each other, resulting in pain and stiffness. Cyclic phosphatidic acid (cPA) shows promise as a treatment for OA. In this article, we review the most recent findings regarding the biological functions of cPA signaling in mammalian systems, specifically in relation to OA. cPA is a naturally occurring phospholipid mediator with unique cyclic phosphate rings at the sn-2 and sn-3 positions in the glycerol backbone. cPA promotes various responses, including cell proliferation, migration, and survival. cPA possesses physiological activities that are distinct from those elicited by lysophosphatidic acid; however, its biochemical origin has rarely been studied. Although there is currently no cure for OA, advances in medical research may lead to new therapies or strategies in the future, and cPA has potential therapeutic applications.

PSD95 as a New Potential Therapeutic Target of Osteoarthritis: A Study of the Identification of Hub Genes through Self-Contrast Model

Osteoarthritis (OA) is a worldwide joint disease. However, the precise mechanism causing OA remains unclear. Our primary aim was to identify vital biomarkers associated with the mechano-inflammatory aspect of OA, providing potential diagnostic and therapeutic targets for OA. Thirty OA patients who underwent total knee arthroplasty were recruited, and cartilage samples were obtained from both the lateral tibial plateau (LTP) and medial tibial plateau (MTP). GO and KEGG enrichment analyses were performed, and the protein-protein interaction (PPI) assessment was conducted for hub genes. The effect of PSD95 inhibition on cartilage degeneration was also conducted and analyzed. A total of 1247 upregulated and 244 downregulated DEGs were identified. Significant differences were observed between MTP and LTP in mechanical stress-related genes and activated sensory neurons based on a self-contrast model of human knee OA. Cluster analysis identified DLG4 as the hub gene. Cyclic loading stress increased PSD95 (encoded by DLG4) expression in LTP cartilage, and PSD95 inhibitors could alleviate OA progression. This study suggests that inhibiting PSD95 could be a potential therapeutic strategy for preventing articular cartilage degradation.