Synovial Parasitosis and Inflammatory Biomarker Profiles in Osteoarthritis: Associations with Host and Therapeutic Factors

Human HtrA1 belongs to a widely conserved family of serine proteases involved in various aspects of protein quality control and cell fate. Although HtrA1 has been implicated in the pathology of several diseases, its precise biological functions remain to be established. Through identification of potential HtrA1 targets, studies presented herein propose that within the context of arthritis pathology HtrA1 contributes to cartilage degradation. Elevated synovial HtrA1 levels were detected in fluids obtained from rheumatoid and osteoarthritis patients, with synovial fibroblasts identified as a major source of secreted HtrA1. Mass spectrometry analysis of potential HtrA1 substrates within synovial fluids identified fibronectin as a candidate target, and treatment of fibronectin with recombinant HtrA1 led to the generation of fibronectin-degradation products that may be involved in cartilage catabolism. Consistently, treatment of synovial fibroblasts with HtrA1 or HtrA1-generated fibronectin fragments resulted in the specific induction of matrix metalloprotease 1 and matrix metalloprotease 3 expression, suggesting that HtrA1 contributes to the destruction of extracellular matrix through both direct and indirect mechanisms.

Cheyne-Stokes respiration (CSR), a kind of central sleep apnea, is referred to as a poor prognostic factor in heart failure patients with reduced ejection fraction (HFrEF). Matrix metalloproteinase (MMP) and B-type natriuretic peptide (BNP) play important roles in HFrEF patients and are markers of poor prognosis. However, there is no literature mentioning the changes in MMP and BNP in HFrEF patients with CSR. From June 2018 to June 2019, 41 adult patients with stable heart failure and left ventricular ejection fraction < 50% were enrolled from the cardiology clinic. After history-taking and medication review to exclude possible central nervous system- or medication-related central sleep apnea, an overnight polysomnography study was performed, and CSR was identified. The morning serum MMP-2, MMP-9, and BNP levels were determined using enzyme-linked immunosorbent assay and fluorescence immunoassay techniques. A positive airway pressure device was applied to 7 patients for 3 months. The serum MMP-2 and BNP levels were significantly higher in HFrEF patients with CSR than in patients without CSR. In addition, elevated serum MMP-2 levels correlated well with the severity of sleep apnea and intermittent hypoxia, which were represented as the apnea-hypopnea index and the oxygen desaturation index. No positive correlation was found between those markers and left ventricular ejection fraction. Finally, the treatment of sleep apnea with continuous positive airway pressure for 3 months tended to reduce the elevated serum MMP-2 levels. Higher serum MMP-2 and BNP levels were found in HFrEF patients with CSR. Elevated MMP-2 levels were correlated with the severity of sleep apnea and intermittent hypoxia. Chuang L-P, Pang J-HS, Lin S-W, etal. Elevated serum matrix metalloproteinase-2 levels in heart failure patients with reduced ejection fraction and Cheyne-Stokes respiration. J Clin Sleep Med. 2022;18(5):1365-1373.

Background:Osteoarthritis (OA) remains one of the most common osteopathy for centuries, which can be attributed to multiple risk factors including mechanical and biochemical ones. More and more studies verified that inflammatory cytokines play important roles in the progression of OA, such as tumor necrosis factor-alpha (TNF-α). In this study, we aimed to investigate the relationship between epigenetic manifestations of TNF-? and the pathogenesis of OA.Methods:Totally, 37 OA patients’ cartilage was collected through the knee joint and 13 samples of articular cartilage as healthy control was collected through traumatic amputation. Real-time PCR, Western blot and ELISA analysis were performed to observe the expression of target genes and proteins in collected samples.Results:Compared with the healthy control group, TNF-? was over-expressing in cartilage which was collected from OA patients. DNA hypomethylation, histone hyperacetylation and histone methylation were observed in the TNF-? promoter in OA compared with normal patients, and we also studied series of enzymes associated with epigenetics. The results showed that by increasing DNA methylation and decreasing histone acetylation in the TNF-? promoter, and TNF-? over-expression in OA cartilage was suppressed, histone methylation has no significant correlation with OA.Conclusion:In conclusion, the changes of epigenetic status regulate TNF-α expression in the cells, which are pivotal to the OA disease process. These results may give us a better understanding of OA and may provide new therapeutic options.

Osteoarthritis (OA) is the most prevalent form of arthritis and affects over 528 million people worldwide. Degenerative joint disease involves cartilage degradation, subchondral bone remodeling, and synovial inflammation, leading to chronic pain, stiffness, and impaired joint function. Initially regarded as a "wear and tear" condition associated with aging and mechanical stress, OA is now recognized as a multifaceted disease influenced by systemic factors such as metabolic syndrome, obesity, and chronic low-grade inflammation. Recent studies have focused on the gut-joint axis to investigate how the gut microbiome modulates inflammation and pain in OA. A systematic review was conducted following the PRISMA guidelines and was registered with PROSPERO (CRD42024556265). This review included studies involving adults with symptomatic OA and analyzed the relationship between the gut microbiome and OA-related pain. Randomized and non-randomized clinical trials, case reports, editorials, and pilot studies were excluded. Searches were performed in PubMed, Cochrane Library, and Web of Science without publication date restrictions, and filtered for "observational studies". The study selection and data extraction were performed by two independent researchers, and the risk of bias was assessed using appropriate tools. Five observational studies were included in the systematic review, and three were included in the meta-analysis. Two studies reported an association between different tryptophan metabolites and pain levels in patients with OA. Two other studies demonstrated a correlation between lipopolysaccharide levels and pain in OA. A fifth study confirmed the relationship between Streptococcus relative abundance of Streptococcus spp. and knee pain. These results were not supported by a meta-analysis, which found no significant association between the presence of pain in OA and the presence of bacilli of the genus Streptococcus or plasma markers of the tryptophan pathway. Current evidence indicates a potential link between gut microbiome dysbiosis and OA-related pain. However, methodological limitations preclude definitive conclusions. Further research using advanced techniques and larger cohorts is needed to validate and extend these findings and elucidate the underlying mechanisms. Targeted manipulation of the gut microbiome may be a valuable strategy for pain management in OA patients.

Cleavage of Type II Collagen by Cathepsin K in Human Osteoarthritic Cartilage

Synovial Mesenchymal Stem Cell-Derived EV-Packaged miR-31 Downregulates Histone Demethylase KDM2A to Prevent Knee Osteoarthritis

To identify long noncoding RNAs (lncRNAs) associated with the inflammatory phenotype of synovial fibroblasts from obese patients with osteoarthritis (OA), and to explore the expression and function of these lncRNAs. Synovium was collected from normal-weight patients with hip fracture (non-OA; n = 6) and from normal-weight (n = 8) and obese (n = 8) patients with hip OA. Expression of RNA was determined by RNA-sequencing and quantitative reverse transcription-polymerase chain reaction. Knockdown of lncRNA was performed using LNA-based GapmeRs. Synovial fibroblast cytokine production was measured by enzyme-linked immunosorbent assay. Synovial fibroblasts from obese patients with OA secreted greater levels of interleukin-6 (IL-6) (mean ± SEM 162 ± 21 pg/ml; P < 0.001) and CXCL8 (262 ± 67 pg/ml; P < 0.05) compared to fibroblasts from normal-weight patients with OA (IL-6, 51 ± 4 pg/ml; CXCL8, 78 ± 11 pg/ml) or non-OA patients (IL-6, 35 ± 3 pg/ml; CXCL8, 56 ± 6 pg/ml) (n = 6 patients per group). RNA-sequencing revealed that fibroblasts from obese OA patients exhibited an inflammatory transcriptome, with increased expression of proinflammatory messenger RNAs (mRNAs) as compared to that in fibroblasts from normal-weight OA or non-OA patients (>2-fold change, P < 0.05; n = 4 patients per group). A total of 19 lncRNAs were differentially expressed between normal-weight OA and non-OA patient fibroblasts, and a further 19 lncRNAs were differentially expressed in fibroblasts from obese OA patients compared to normal-weight OA patients (>2-fold change, P < 0.05 for each), which included the lncRNA for metastasis-associated lung adenocarcinoma transcript 1 (MALAT1). MALAT1 was rapidly induced upon stimulation of OA synovial fibroblasts with proinflammatory cytokines, and was up-regulated in the synovium from obese OA patients as compared to normal-weight OA patients (1.6-fold change, P < 0.001) or non-OA patients (6-fold change, P < 0.001). MALAT1 knockdown in OA synovial fibroblasts (n = 4 patients) decreased the levels of mRNA expression and protein secretion of CXCL8 (>1.5-fold change, P < 0.01), whereas it increased expression of mRNAs for TRIM6 (>2-fold change, P < 0.01), IL7R (<2-fold change, P < 0.01), HIST1H1C (>1.5-fold change, P < 0.001), and MAML3 (>1.5-fold change, P < 0.001). In addition, MALAT1 knockdown inhibited the proliferation of synovial fibroblasts from obese patients with OA. Synovial fibroblasts from obese patients with hip OA exhibit an inflammatory phenotype. MALAT1 lncRNA may mediate joint inflammation in obese OA patients.

The gut microbiome compositions of osteoarthritis (OA) and rheumatoid arthritis (RA) patients have been revealed; however, the functional genomics, particularly antibiotic resistance genes (ARGs) and virulence factor genes (VFGs), have not yet been explored. We used gut metagenomic data to elucidate the distribution of ARGs and VFGs. Building on these differences in gut microbiome, we developed a diagnostic model using a random forest classifier based on ARG and VFG abundances. Our results indicated that both OA and RA patients exhibit significantly higher alpha diversity in ARGs, as measured by observed genes, the Shannon index, and the Simpson index, compared to healthy controls. However, this increased diversity is not significantly different between OA and RA patients. In contrast, VFGs showed higher diversity in RA patients than in healthy individuals, which was not as pronounced in OA patients. An analysis of the top 20 ARGs and VFGs revealed a largely similar composition between the three groups, with notable exceptions of certain genes that were uniquely enriched in either OA or RA patients. This suggests unique microbial patterns associated with each condition. Our beta diversity analysis further demonstrated distinct distributions of ARG and VFG profiles across the three groups, with several genes significantly enriched in both OA and RA patients, indicating potential markers for these diseases. The model achieved high accuracy (74.7-83.6%) when distinguishing both OA and RA from healthy controls using ARG profiles and substantial accuracy using VFG profiles. These results support the potential of ARGs and VFGs as reliable biomarkers for diagnosing OA and RA.

Expression levels and clinical significance of matrix metalloproteinase-1 (MMP1), MMP-2 and inflammatory factors in the serum of patients with deep venous thrombosis (DVT) of lower extremity were investigated. Fifty untreated DVT patients were selected as the DVT group, and 50 patients undergoing health examination were enrolled as the normal control group. Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of MMP-1, MMP-2, interleukin-6 (IL-6), IL-8 and tumor necrosis factor-α (TNF-α) in the serum. Western blotting was adopted to detect the expression levels of MMP-1 and MMP-2 proteins. Fluorescent reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to examine the messenger ribonucleic acid (mRNA) expression levels. Moreover, the circumferences of the patients were measured. The difference between the circumference of affected extremity and unaffected extremity was calculated. Correlation analysis was conducted separately for the levels of serum MMP-1, MMP-2, IL-6, IL-8 and TNF-α of patients in the DVT group. In the DVT group, the levels of MMP-1, MMP-2, IL-6, IL-8, and TNF-α at 7 days after treatment were significantly lower than those before treatment (P<0.01). Compared with that before treatment, the circumference difference of the affected and unaffected extremities of the patients was reduced at 7 days after treatment (P<0.01). The levels of IL-6, IL-8 and TNF-α were positively correlated with the levels of MMP-1 and MMP-2, respectively in the DVT group (P<0.05 or P<0.01). MMP-1, MMP-2 and inflammatory factors play an important role in the occurrence and development of DVT, of which the levels of IL-6, IL-8 and TNF-α are positively correlated with the levels of MMP-1 and MMP-2, respectively. Therefore, monitoring the concentration of MMP-1, MMP-2 and inflammatory factors is of significant value for the diagnosis, progression and judgement of treatment effect of DVT in clinical practice.

Gut microbiota from osteoarthritic patients without obesity aggravates osteoarthritis progression in rats by enriching acetic acid.

The identification of differentially expressed microRNA in osteoarthritic tissue that modulate the production of TNF-α and MMP13

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BackgroundPreventing synovial fibroblasts (SF) from migrating into the adjacent cartilage is a desirable therapeutic target in rheumatoid arthritis (RA) in order to avoid joint destruction and disability. In our previous...

Background and objectivesAdipose derived stem cells (ADSC) have a potential to differentiate into cells of mesodermal origin (chondrocytes, osteoblasts, adipocytes) and recently emerged as an attractive source of mesenchymal stem...

Objective: To investigate the clinical significance of soluble Semaphorin 5A(Sema 5A) in patients of rheumatoid arthritis(RA) and the effect of Sema 5A on osteoclastogenesis in RAW264.7 cells. Methods: (1)Soluble Sema 5A was detected in the serum of 62 RA patients, 30 osteoarthritis(OA) patients and 48 healthy controls(HC) by enzyme-linked immunosorbent assay(ELISA).The relationships between serum Sema 5A and disease activity, radiographic severity and laboratory parameters were investigated in RA patients.(2)RAW264.7 cells were treated with different concentrations of Sema 5A(0,0.5,1,2.5,5 μg/ml).After 7 days, tartrate-resistant acid phosphate(TRAP) staining was performed. The mRNA levels of TRAP, cathepsin-K and matrix metallopeptidase 9(MMP-9) were tested using real-time polymerase chain reaction (RT-PCR).(3)Bone resorption area of dentine slides cultured with RAW264.7 cells was calculated after Sema 5A(5μg/ml) treatment. Results: (1)The serum Sema 5A in RA patients[(5.24±0.59)μg/L] was significantly higher than those in healthy controls[(2.93±0.34)μg/L,P<0.01] and OA patients[(2.68±0.47)μg/L,P<0.05]. The Sema 5A level in RA patients was positively correlated with disease activity score with 28 joint using C-reactive protein(DAS28-CRP), clinical disease activity index (CDAI),C-reactive protein(CRP) and sharp scores(P<0.05 or P<0.01).In addition,the serum Sema 5A in RA patients with positive anti-cyclic citrullinated peptide(CCP) antibody was significantly greater than that of anti-CCP antibody-negative patients(P<0.05).(2)After RAW264.7 cells were treated with Sema 5A, the number of TRAP positive osteoclasts increased according to the increase of Sema 5A concentration with maximal effect at 5 μg/ml. Meanwhile, Sema 5A promoted mRNA expression of TRAP,Cathepsin-K and MMP-9.(3)Bone resorption area increased when RAW264.7 cells were treated with Sema 5A(5 μg/ml). Conclusions: Serum Sema 5A is elevated in RA patients and correlated with disease activity and radiographic severity. Sema 5A promotes osteoclastogenesis of RAW264.7 cells.