Folate Deficiency Triggered Apoptosis of Synoviocytes: Role of Overproduction of Reactive Oxygen Species Generated via NADPH Oxidase/Mitochondrial Complex II and Calcium Perturbation

The association of folate deficiency with clinical and radiological severity of knee osteoarthritis

CONTEXT

Folate deficiency is often observed in patients with inflammatory diseases, raising questions about its role in knee osteoarthritis (OA) progression.

OBJECTIVES

This study aimed to assess the association of folate deficiency with the clinical and radiological severity of knee OA.

METHODS

A prospective cross-sectional study was conducted from January 1, 2019 to January 1, 2020. Primary knee OA patients referred to orthopedic clinics in Zabol, Iran were included. Radiographic severity was gauged utilizing the Kellgren-Lawrence (KL) classification. For clinical severity, patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. IBM SPSS v.27 facilitated the statistical analysis.

RESULTS

Forty-nine knee OA patients, averaging 67.45±13.44 years in age, were analyzed. Spearman correlation analysis revealed a negative correlation between folate levels and both WOMAC and KL scores. The correlation was stronger between folate and KL score (Spearman correlation coefficient: -0.75) than between folate and WOMAC total score (Spearman correlation coefficient: -0.46). Additionally, a significantly higher KL score was observed in patients with folate deficiency (p=0.004).

CONCLUSIONS

Our study highlights a significant correlation between folate deficiency and increased severity of OA, which is evident in radiological and clinical assessments. These findings suggest that folate plays a key role in OA pathogenesis and could be a modifiable factor in its management.

Network Pharmacology and Molecular Docking to Elucidate the Potential Mechanism of Ligusticum Chuanxiong Against Osteoarthritis

Background: Osteoarthritis (OA) is a degenerative disease which serious affects patients. Ligusticum chuanxiong (CX) has been shown to have a certain curative effect on osteoarthritis in traditional Chinese medicine therapy. This study is based on network pharmacology and molecular docking technology to explore the potential mechanism of CX.

Methods: Components of CX to treat osteoarthritis were screened in the TCMSP database and targets were predicted by the PharmMapper database, the osteoarthritis targets were collected from the GeneCards database, and intersection genes were found to be the possible targets of CX anti-OA. The STRING database and Cytoscape software were utilized for protein-protein interaction analysis and further screening of core targets. The Metascape database was used for KEGG and GO enrichment analyses. Then, the top 10 pathways were selected to construct “drug-compound-target-pathway-disease” network analysis. Finally, molecular docking was used to analyze the binding affinity of seven compounds with core targets and TNF-α.

Results: Seven compounds with 253 non-repetitive targets of CX were screened from the TCMSP database and 60 potential intersection targets of CX anti-OA were found. PPI network analysis showed that the core targets were ALB, AKT1, IGF1, CASP3, MAPK1, ANXA5, and MAPK14, while GO and KEGG pathway enrichment analyses showed that the relevant biological processes involved in the treatment of osteoarthritis by CX might include the MAPK cascade and reactive oxygen species metabolic process. The KEGG pathway analysis result was mainly associated with the MAPK signaling pathway and PI3K-AKT signaling pathway. We further docked seven ingredients with MAPK1 and MAPK14 enriched in the MAPK pathway, and TNF-α as the typical inflammatory cytokine. The results also showed good binding affinity, especially FA, which may be the most important component of CX anti-OA.

Conclusion: Our research revealed the potential mechanism of CX in the treatment of OA, and our findings can also pave the way for subsequent basic experimental verification and a new research direction.

Folic Acid Homeostasis and Its Pathways Related to Hepatic Oxidation in Adolescent Rats Exposed to Binge Drinking

Chronic ethanol consumption and liver disease are intimately related to folic acid (FA) homeostasis. Despite the fact that FA decreases lipid oxidation, its mechanisms are not yet well elucidated. Lately, adolescents have been practising binge drinking (BD), consisting of the intake of a high amount of alcohol in a short time; this is a particularly pro-oxidant form of consumption. The aim of this study is to examine, for the first time, FA homeostasis in BD adolescent rats and its antioxidant properties in the liver. We used adolescent rats, including control rats and rats exposed to an intermittent intraperitoneal BD model, supplemented with or without FA. Renal FA reabsorption and renal FA deposits were increased in BD rats; hepatic deposits were decreased, and heart and serum levels remained unaffected. This depletion in the liver was accompanied by higher transaminase levels; an imbalance in the antioxidant endogenous enzymatic system; lipid and protein oxidation; a decrease in glutathione (GSH) levels; hyper-homocysteinemia (HHcy); an increase in NADPH oxidase (NOX) 1 and NOX4 enzymes; an increase in caspase 9 and 3; and a decrease in the anti-apoptotic metallopeptidase inhibitor 1. Furthermore, BD exposure increased the expression of uncoupled endothelial nitric oxide synthase (eNOS) by increasing reactive nitrogen species generation and the nitration of tyrosine proteins. When FA was administered, hepatic FA levels returned to normal levels; transaminase and lipid and protein oxidation also decreased. Its antioxidant activity was due, in part, to the modulation of superoxide dismutase activity, GSH synthesis and NOX1, NOX4 and caspase expression. FA reduced HHcy and increased the expression of coupled eNOS by increasing tetrahydrobiopterin expression, avoiding nitrosative stress. In conclusion, FA homeostasis and its antioxidant properties are affected in BD adolescent rats, making it clear that this vitamin plays an important role in the oxidative, nitrosative and apoptotic hepatic damage generated by acute ethanol exposure. For this, FA supplementation becomes a potential BD therapy for adolescents, preventing future acute alcohol-related harms.

Efficacy and Safety of N-acetylcysteine for the Management of Chronic Pain in Adults: A Systematic Review & Meta-analysis

OBJECTIVE

To assess the efficacy and safety of N-acetylcysteine in the treatment of chronic pain.

METHODS

A systematic search was carried out until April 2020 for clinical studies of N-acetylcysteine in the management of any persistent or recurrent chronic pain condition for adults ≥ 18 years old. Risk of Bias was assessed using the validated risk of bias tools. When appropriate, a meta-analysis using a random-effects model was performed, with a fixed-effect model for sensitivity analysis.

RESULTS

Nine studies (n = 863) were included (5 randomized controlled trials [RCTs], 2 open-label non-comparative studies and 2 comparative studies), that evaluated patients with sickle cell disease (3), complex regional pain syndrome (1), pelvic pain/endometriosis (2), rheumatoid arthritis (1), diabetic neuropathy (1), and chronic neuropathic pain (1). In the pooled analysis of 3 RCTs, N-acetylcysteine did not reduce pain intensities (SMD -0.21, 95% CI -0.33 to 0.75, random-effects), improve functional outcomes (SMD 0.21, 95% CI -0.33 to 0.75) or quality of life (SMD 0.60, 95% CI -4.44 to 5.64); however, sensitivity analysis with a fixed effect model demonstrated an effect for pain intensities and function. Due to adverse events being inconsistently reported, no conclusion could be made regarding safety of N-acetylcysteine in chronic pain.

CONCLUSIONS

While there is some evidence to indicate N-acetylcysteine may provide analgesic efficacy for certain pain conditions, there is insufficient evidence to provide definitive evidence on NAC in chronic pain management. Larger-size RCTs spanning a variety of chronic pain conditions are needed to determine N-acetylcysteine's role, if any, in pain medicine.

High-dose folic acid supplementation results in significant accumulation of unmetabolized homocysteine, leading to severe oxidative stress in Caenorhabditis elegans

Using Caenorhabditis elegans as a model animal, we evaluated the effects of chronical supplementation with high-dose folic acid on physiological events such as life cycle and egg-laying capacity and folate metabolism. Supplementation of high-dose folic acid significantly reduced egg-laying capacity. The treated worms contained a substantial amount of unmetabolized folic acid and exhibited a significant downregulation of the mRNAs of cobalamin-dependent methionine synthase reductase and 5,10-methylenetetrahydrofolate reductase. In vitro experiments showed that folic acid significantly inhibited the activity of cobalamin-dependent methionine synthase involved in the metabolism of both folate and methionine. In turn, these metabolic disorders induced the accumulation of unmetabolized homocysteine, leading to severe oxidative stress in worms. These results were similar to the phenomena observed in mammals during folate deficiency.

•

High-dose folic acid supplementation reduced egg-laying ability in worms.

•

Substantial amounts of folic acid and homocysteine were accumulated in the worms.

•

The mRNA expression of methylenetetrahydrofolate reductase was reduced in the treated worms.

•

Folic acid was a potent inhibitor of cobalamin-dependent methionine synthase in in vitro tests.

•

High-dose folic acid supplementation in worms resulted in severe oxidative stress.

Potential role of mitochondria in synoviocytes

Synoviocytes are located in the synovium lining layer, which is composed of macrophage-like synoviocytes (MLS) and fibroblast-like synoviocytes (FLS) with different characteristics. Mitochondria, which exist in most cells, are two membrane-covered organelles. In addition to providing the necessary ATP for synoviocytes, mitochondria are involved in the regulation of redox homeostasis and the integration of synoviocytes death signals. In recent years, mitochondrial dysfunction has been found in rheumatoid arthritis (RA) and osteoarthritis (OA). Interestingly, recent studies have started uncovering that mitochondria that were previously reported to play a role in chondrocytes or immune cells, but not known to have pronounced roles in synoviocytes, can actually play crucial roles in the regulation of the pathological properties of the synoviocytes. The purpose of this review is to summarize our current understanding of the key role of mitochondria in synoviocytes, including mitochondrial dysfunction in synoviocytes can induce and aggravate inflammatory responses and changes in mitochondrial structure and function with the involvement of multiple cytokines, signal pathway, and hypoxic state of synovial tissue alter the response of synoviocytes to apoptotic stimulation. Also, mitochondrial abnormalities in synoviocytes promote the synoviocytes invasion and proliferation.

Hypoxia/reoxygenation activates the JNK pathway and accelerates synovial senescence

Hypoxia/reoxygenation (H/R) may play an important role via senescence in the mechanism of osteoarthritis (OA) development. The synovial membrane is highly sensitive to H/R due to its oxygen consumption feature. Excessive mechanical loads and oxidative stress caused by H/R induce a senescence-associated secretory phenotype (SASP), which is related to the development of OA. The aim of the present study was to investigate the differences of SASP manifestation in synovial tissue masses between tissues from healthy controls and patients with OA. The present study used tumor necrosis factor-α (TNF-α) to pre-treat synovial tissue and fibroblast-like synoviocytes (FLS) to observe the effect of inflammatory cytokines on the synovial membrane before H/R. It was determined that H/R increased interleukin (IL)-1β and IL-6 expression levels in TNF-α-induced cell culture supernatants, increased the proportion of SA-β-gal staining, and increased the expression levels of high mobility group box 1, caspase-8, p16, p21, matrix metalloproteinase (MMP)-3 and MMP-13 in the synovium. Furthermore, H/R opened the mitochondrial permeability transition pore, caused the loss of mitochondrial membrane potential (ΔΨm) and increased the release of reactive oxygen species (ROS). Moreover, H/R caused the expansion of the mitochondrial matrix and rupture of the mitochondrial extracorporeal membrane, with a decrease in the number of cristae. In addition, H/R induced activation of the JNK signaling pathway in FLS to induce cell senescence. Thus, the present results indicated that H/R may cause inflammation and escalate synovial inflammation induced by TNF-α, which may lead to the pathogenesis of OA by increasing changes in synovial SASP and activating the JNK signaling pathway. Therefore, further studies expanding on the understanding of the pathogenesis of H/R etiology in OA are required.

Malnutrition impairs mitochondrial function and leukocyte activation

BACKGROUND

The aim of this study was to evaluate markers of inflammation, oxidative stress and endothelial function in a disease-related malnutrition (DRM) outpatient population.

METHODS

For this cross-sectional study, a total of 83 subjects were included and clustered in 3 groups: 34 with normonutrition (NN), 21 with DRM without inflammation (DRM-I) and 28 with DRM and inflammation (DRM + I). Nutritional diagnosis was conducted for all subjects according to ASPEN. Biochemical parameters, proinflammatory cytokines, reactive oxygen species production, glutathione, mitochondrial membrane potential, oxygen consumption, adhesion molecules and leukocyte-endothelium interactions were evaluated.

RESULTS

DRM + I patients showed lower albumin, prealbumin, transferrin, and retinol-binding protein levels with respect to the NN group (p < 0.05), differences that were less noticeable in the DRM-I group. DRM + I was associated with a significant increase in hsCRP and IL6 vs the NN and DRM-I groups, and TNFα was increased in both DRM vs NN. DRM was characterised by increased oxidative stress, which was marked by a significant increase in ROS levels and a decrease in mitochondrial membrane potential in the DRM + I group. An evident reduction in mitochondrial oxygen consumption and glutathione concentration was observed in both DRM groups, and was accompanied by increased leukocyte adhesion and adhesion molecules and decreased rolling velocity in the DRM + I group. Furthermore, percentage of weight loss was negatively correlated with albumin, prealbumin, transferrin, O₂ consumption, glutathione and leukocyte rolling velocity, and positively correlated with hsCRP, IL6, TNFα, ROS, leukocyte adhesion, and VCAM-1.

CONCLUSIONS

Our results show that DRM is associated with oxidative stress and an inflammatory state, with a deterioration of endothelial dysfunction in the DRM + I population.

ROCK/actin/MRTF signaling promotes the fibrogenic phenotype of fibroblast-like synoviocytes derived from the temporomandibular joint

Malocclusion caused by abnormal jaw development or muscle overuse during mastication results in abnormal mechanical stress to the tissues surrounding the temporomandibular joint (TMJ). Excessive mechanical stress against soft and hard tissues around the TMJ is involved in the pathogenesis of inflammatory diseases, including osteoarthritis (OA). OA-related fibrosis is a possible cause of joint stiffness in OA. However, cellular and molecular mechanisms underlying fibrosis around the TMJ remain to be clarified. Here, we established a cell line of fibroblast‑like synoviocytes (FLSs) derived from the mouse TMJ. Then, we examined whether the Rho‑associated coiled‑coil forming kinase (ROCK)/actin/myocardin-related transcription factor (MRTF) gene regulatory axis positively regulates the myofibroblast (MF) differentiation status of FLSs. We found that i) FLSs extensively expressed the MF markers α‑smooth muscle actin (α‑SMA) and type I collagen; and ii) an inhibitor against the actin‑polymerizing agent ROCK, Y‑27632; iii) an actin-depolymerizing agent cytochalasin B; iv) an inhibitor of the MRTF/serum response factor‑regulated transcription, CCG‑100602, clearly suppressed the mRNA levels of α‑SMA and type I collagen in FLSs; and v) an MF differentiation attenuator fibroblast growth factor‑1 suppressed filamentous actin formation and clearly suppressed the mRNA levels of α-SMA and type I collagen in FLSs. These results strongly suggest that the ROCK/actin/MRTF axis promotes the fibrogenic activity of synoviocytes around the TMJ. Our findings partially clarify the molecular mechanisms underlying the emergence of TMJ‑OA and may aid in identifying drug targets for treating this condition at the molecular level.

Benefits of Selenium Supplementation on Leukocyte DNA Integrity Interact with Dietary Micronutrients: A Short Communication

A male cohort from New Zealand has previously shown variability in Selenium (Se) supplementation effects on measured biomarkers. The current analysis is to understand the reasons for variability of the H₂O₂-induced DNA damage recorded after Se supplementation. We have looked at the variation of demographic, lifestyle, medication, genetic and dietary factors and biomarkers measured at baseline and post-supplementation in these two extreme subgroups A and B. Group A showed increased H₂O₂-induced DNA damage and group B showed decreased damage after Se supplementation. We have also considered correlations of biomarkers and dietary factors in the complete dataset. The glutathione peroxidase (GPx) activity and DNA damage were significantly lower at post-supplementation in Group B compared to Group A. Post-supplementation, Group B showed a significant reduction in the GPx activity, while Group A showed a significant increase in DNA damage compared to baseline levels. Dietary methionine intake was significantly higher and folate intake was significantly lower in Group B compared to Group A. Se supplementation significantly increased the caspase-cleaved keratin 18 levels in both groups, indicating increased apoptotic potential of this supplement. Parameter correlation with the complete dataset showed dietary methionine to have a significant negative correlation with H₂O₂-induced DNA damage post-supplementation. The data suggest that Se supplementation is beneficial for the leukocyte DNA integrity only in interaction with the dietary methionine and folate intake.