Unraveling the molecular landscape of osteoarthritis: A comprehensive review focused on the role of non-coding RNAs

Osteoarthritis (OA) poses a significant global health challenge, with its prevalence anticipated to increase in the coming years. This review delves into the emerging molecular biomarkers in OA pathology, focusing on the roles of various molecules such as metabolites, noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Advances in omics technologies have transformed biomarker identification, enabling comprehensive analyses of the complex pathways involved in OA pathogenesis. Notably, ncRNAs, especially miRNAs and lncRNAs, exhibit dysregulated expression patterns in OA, presenting promising opportunities for diagnosis and therapy. Additionally, the intricate interplay between epigenetic modifications and OA progression highlights the regulatory role of epigenetics in gene expression dynamics. Genome-wide association studies have pinpointed key genes undergoing epigenetic changes, providing insights into the inflammatory processes and chondrocyte hypertrophy typical of OA. Understanding the molecular landscape of OA, including biomarkers and epigenetic mechanisms, holds significant potential for developing innovative diagnostic tools and therapeutic strategies for OA management.

The m6A/m1A/m5C-Related Methylation Modification Patterns and Immune Landscapes in Rheumatoid Arthritis and Osteoarthritis Revealed by Microarray and Single-Cell Transcriptome

Purpose

The goal of this study was to explore the expression characteristics of RNA modification-related genes, reveal immune landscapes and identify novel potential diagnostic biomarkers in osteoarthritis (OA) and rheumatoid arthritis (RA) patients.

Patients and Methods

RNA microarray and single-cell sequencing (scRNA-seq) data were downloaded from gene expression omnibus (GEO) database. Differentially expressed RNA modification-related genes were identified and then functionally annotated. Univariate logistic regression and lasso regression analysis were used to identify primary disease genes for OA and RA. Validation was done using scRNA-seq analysis and immunohistochemistry (IHC) in human knee synovial tissues and a murine destabilization of the medial meniscus (DMM) model. Through WGCNA analysis, genes associated with cell pyroptosis or autophagy in OA and RA were identified, which were then combined with differentially expressed RNA modification-related genes to construct a PPI interaction network. Furthermore, hub genes were selected for ceRNA interaction network analysis, correlation analysis with OA and RA molecular subtypes, as well as correlation analysis with 22 immune cells.

Results

Six RNA modification-related genes (ADAMDEC1, IGHM, OGN, TNFRSF11B, SCARA3 and PTN) were identified as potential OA and RA pathogenesis biomarkers. Their expression was validated in human knee synovial tissues and a murine DMM model. Functional enrichment of differentially expressed RNA modification-related genes between RA and OA was analyzed using GO, KEGG, GSEA, and GSVA. Based on WGCNA and PPI analysis, the six hub genes related to pyroptosis and RNA modification (CXCL10, CXCL9, CCR7, CCL5, CXCL1, and CCR2) were identified as central nodes for ceRNA interaction, correlation with OA and RA molecular subtypes, and association with 22 immune cells.

Conclusion

Our research revealed the significance of RNA modification-related genes in the development of OA and RA pathogenesis, thereby providing a novel research direction for understanding the mechanisms, diagnosis, and treatment of OA and RA.

Burden of knee osteoarthritis in the Middle East and North Africa (MENA): an epidemiological analysis from 1990 to 2019

BACKGROUND

Knee is the most affected joint in osteoarthritis (OA) and accounts for almost four-fifths of the burden of OA globally. We aimed to explore the prevalence, incidence, trends, and burden of knee OA during 1990-2019 in the Middle East and North Africa (MENA) region, using the Global Burden of Disease (GBD) study data.

METHODS

This is an epidemiological study based on the GBD data from 1990 to 2019 on knee OA in MENA countries. The prevalence, incidence, and years lived with disability (YLD) numbers of knee OA were obtained for both genders. Similarly, age-standardized rates of these indexes per 100,000 people and the proportion of total YLD caused by knee OA in each country and for the MENA region were evaluated.

RESULTS

The prevalence of knee osteoarthritis in the MENA region increased 2.88-fold, from 6.16 million cases to 17.75 million, between 1990 and 2019. Furthermore, in 2019, knee osteoarthritis accounted for approximately 1.69 million (95% UI 1.46-1.95) incident cases in MENA. The age-standardized prevalence was higher in women between 1990 (3.94% [95% UI 3.39-4.55] in women and 3.24% [95% UI 2.79-3.72] in men) and 2019 (4.44% [95% UI 3.83-5.10] in women and 3.66% [3.14-4.21] in men). Total YLDs due to knee osteoarthritis increased by more than 2.88-fold, rising from 196.29 thousand [95% UI 97.17-399.29] in 1990 to 564.66 thousand [95% UI 275.06-1,150.68] in 2019. In the year 2019, Kuwait, Turkey, and Oman had the highest age-standardized prevalence (4.42% [95% UI 3.79-5.08]), YLD (132.41 [95% UI 65.79-267.56] per 100 000), and increase (21.17%) in YLD compared with 1990 in MENA region, respectively.

CONCLUSION

The prevalence of and YLDs due to knee OA in MENA has escalated over the last three decades. Considering the expanding burden of knee OA in MENA, policymakers should be more concerned to implement preventive strategies.

Oleuropein Promotes Neural Plasticity and Neuroprotection via PPARα-Dependent and Independent Pathways

Oleuropein (OLE), a main constituent of olives, displays a pleiotropic beneficial dynamic in health and disease; the effects are based mainly on its antioxidant and hypolipidemic properties, and its capacity to protect the myocardium during ischemia. Furthermore, OLE activates the peroxisome proliferator-activated receptor (PPARα) in neurons and astrocytes, providing neuroprotection against noxious biological reactions that are induced following cerebral ischemia. The current study investigated the effect of OLE in the regulation of various neural plasticity indices, emphasizing the role of PPARα. For this purpose, 129/Sv wild-type (WT) and Pparα-null mice were treated with OLE for three weeks. The findings revealed that chronic treatment with OLE up-regulated the brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the prefrontal cortex (PFC) of mice via activation of the ERK1/2, AKT and PKA/CREB signaling pathways. No similar effects were observed in the hippocampus. The OLE-induced effects on BDNF and TrkB appear to be mediated by PPARα, because no similar alterations were observed in the PFC of Pparα-null mice. Notably, OLE did not affect the neurotrophic factors NT3 and NT4/5 in both brain tissues. However, fenofibrate, a selective PPARα agonist, up-regulated BDNF and NT3 in the PFC of mice, whereas the drug induced NT4/5 in both brain sites tested. Interestingly, OLE provided neuroprotection in differentiated human SH-SY5Y cells against β-amyloid and H2O2 toxicity independently from PPARα activation. In conclusion, OLE and similar drugs, acting either as PPARα agonists or via PPARα independent mechanisms, could improve synaptic function/plasticity mainly in the PFC and to a lesser extent in the hippocampus, thus beneficially affecting cognitive functions.

The sodium does not affect joint pain and functional activity of knee osteoarthritis patients

Background: The sodium may aggravate synovial inflammation and cartilage thinning. This incidence can cause joint pain and reduce functional activity. Not many people know the effect of sodium on the incidence of OA. Objective: This study aims to determine the relationship between sodium in the body and knee joint pain which results in functional activity. Methods: The quantitative descriptive study used accidental sampling. The study was conducted at three outpatient polyclinic orthopedics of hospitals and was approved by the Health Ethics Committee. All data were collected during the interview. The Semi-Quantitative Food Frequency Questionnaire (SQ-FFQ) and the Nutrisurvey Indonesia 2007 application were used as a tool to collect daily sodium intake (mg). Knee joint pain score was measured using the Visual Analog Scale (VAS) while functional body activity was measured using the Western Ontario McMaster Osteoarthritis Index (WOMAC). The Pearson and Spearman test (p<0.05) were used as a correlation test. Results: 80 subjects were according to the inclusion criteria. Characteristics of the subjects were pre-elderly (32, 40%), women (74, 92.5%), BMI≥ 30 kg/m2 (54, 67.5%) and occupation (43, 53.75%). Average sodium intake = 2090.78 ± 1084.33 mg, VAS score = 6.28 ± 1.95 and WOMAC score = 32.65 ± 14.88. The correlation sodium, VAS, and WOMAC were not significant (p=0.196, p=0.372). Conclusions: Increased sodium intake is not associated with knee joint pain and functional body activity.

Metformin attenuates symptoms of osteoarthritis: role of genetic diversity of Bcl2 and CXCL16 in OA

OBJECTIVE

This study aimed to evaluate the effectiveness of metformin versus placebo in overweight patients with knee osteoarthritis (OA). In addition, to assess the effects of inflammatory mediators and apoptotic proteins in the pathogenesis of OA, the genetic polymorphisms of two genes, one related to apoptosis (rs2279115 of Bcl-2) and the other related to inflammation (rs2277680 of CXCL-16), were investigated.

METHODS

In this double-blind placebo-controlled clinical trial, patients were randomly divided to two groups, one group receiving metformin (n = 44) and the other one receiving an identical inert placebo (n = 44) for 4 consecutive months (starting dose 0.5 g/day for the first week, increase to 1 g/day for the second week, and further increase to 1.5 g/day for the remaining period). Another group of healthy individuals (n = 92) with no history and diagnosis of OA were included in this study in order to evaluate the role of genetics in OA. The outcome of treatment regimen was evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. The frequency of variants of rs2277680 (A181V) and rs2279115 (938C>A) were determined in extracted DNAs using PCR-RFLP method.

RESULTS

Our results indicated an increase in scores of pain (P ≤ 0.0001), activity of daily living (ADL) (P ≤ 0.0001), sport and recreation (Sport/Rec) (P ≤ 0.0001), and quality of life (QOL) (P = 0.003) and total scores of the KOOS questionnaire in the metformin group compared to the placebo group. Susceptibility to OA was associated with age, gender, family history, CC genotype of 938C>A (Pa = 0.001; OR = 5.2; 95% CI = 2.0-13.7), and GG+GA genotypes of A181V (Pa = 0.04; OR = 2.1; 95% CI = 1.1-10.5). The C allele of 938C>A (Pa = 0.04; OR = 2.2; 95% CI = 1.1-9.8) and G allele of A181V (Pa = 0.02; OR = 2.2; 95% CI = 1.1-4.8) were also associated with OA.

CONCLUSION

Our findings support the possible beneficial effects of metformin on improving pain, ADL, Sport/Rec, and QOL in OA patients. Our findings support the association between the CC genotype of Bcl-2 and GG+GA genotypes of CXCL-16 and OA.

Prevalence of Symptomatic Knee Osteoarthritis in Saudi Arabia and Associated Modifiable and Non-Modifiable Risk Factors: A Population-Based Cross-Sectional Study

OBJECTIVE

This study aimed to determine the prevalence of knee osteoarthritis (OA) in Saudi Arabia and the association between knee OA and modifiable and non-modifiable risk factors.

METHODS

A self-reported, population-based, cross-sectional survey between January 2021 and October 2021 was conducted. A large, population-representative sample (n = 2254) of adult subjects aged 18 years and over from all regions of Saudi Arabia was collected electronically using convenience sampling. The American College of Rheumatology (ACR) clinical criteria were used to diagnose OA of the knee. The knee injury and osteoarthritis outcome score (KOOS) was used to investigate the severity of knee OA. This study focused on modifiable risk factors (body mass index, education, employment status, marital status, smoking status, type of work, previous history of knee injury, and physical activity level) and non-modifiable risk factors (age, gender, family history of OA, and presence of flatfoot).

RESULTS

The overall prevalence of knee OA was 18.9% (n = 425), and women suffered more compared to their male counterparts (20.3% vs. 13.1%, p = 0.001). The logistic regression analysis model showed age (OR: 1.06 [95% CI: 1.05-1.07]; p < 0.01), sex (OR: 2.14 [95% CI: 1.48-3.11]; p < 0.01), previous injury (OR: 3.95 [95% CI: 2.81-5.56]; p < 0.01), and obesity (OR: 1.07 [95% CI: 1.04-1.09]; p < 0.01) to be associated with knee OA.

CONCLUSIONS

A high prevalence of knee OA underlines the need for health promotion and prevention programmes that focus on modifiable risk factors to decrease the burden of the problem and the cost of treatment in Saudi Arabia.

Novel genetic loci associated with osteoarthritis in multi-ancestry analyses in the Million Veteran Program and UK Biobank

Osteoarthritis is a common progressive joint disease. As no effective medical interventions are available, osteoarthritis often progresses to the end stage, in which only surgical options such as total joint replacement are available. A more thorough understanding of genetic influences of osteoarthritis is essential to develop targeted personalized approaches to treatment, ideally long before the end stage is reached. To date, there have been no large multiancestry genetic studies of osteoarthritis. Here, we leveraged the unique resources of 484,374 participants in the Million Veteran Program and UK Biobank to address this gap. Analyses included participants of European, African, Asian and Hispanic descent. We discovered osteoarthritis-associated genetic variation at 10 loci and replicated findings from previous osteoarthritis studies. We also present evidence that some osteoarthritis-associated regions are robust to population ancestry. Drug repurposing analyses revealed enrichment of targets of several medication classes and provide potential insight into the etiology of beneficial effects of antiepileptics on osteoarthritis pain.

Early Detection of Cartilage Degradation Among Heavy Manual Workers Using Serum Level of Collagen Type II Metabolite

BACKGROUND

Work-related musculoskeletal disorders are common health problems in brick manufacturers, where mechanical load leads to degenerative joint diseases. Collagen type II metabolite (C2C) is a small peptide excreted in urine, and its serum concentration can directly reflect articular cartilage decomposition.

OBJECTIVE

Early detection of musculoskeletal disorders among brick workers, using serum C2C as a biomarker of cartilage damage.

METHODS

This study involved 88 male brick workers in Arab Abu Saed matched to 88 age- and sex-matched controls. Full history taking, pain assessment using the Standardized Nordic Questionnaire, and complete clinical examination were done for both groups. Serum C2C was measured using a competitive immunoassay method.

RESULTS

Brick workers involved in the study were of a mean age 30.66 ± 7.90 years and mean work duration 14.80 ± 7.89 years, matched to 88 controls. The majority of the participants (77.3%) were of normal body mass index. An increase in pain/discomfort was found among the exposed group. Serum C2C had an increased mean among the exposed group compared with the control. Pearson correlation between serum C2C level, body mass index, age, and years of employment showed no correlation.

CONCLUSIONS

Musculoskeletal disorders are prevalent among brick workers who adopt specific awkward postures, unhealthy working conditions, and nonexistent safety procedures, for prolonged periods. Detection of serum C2C level can be used as a predictive biomarker for the early detection of musculoskeletal disorders among brick workers.

LncRNA GAS5 upregulates Smad4 to suppress the apoptosis of chondrocytes induced by lipopolysaccharide

BACKGROUND

Osteoarthritis (OA) is closely correlated with inflammation. It has been reported that lncRNA GAS5 plays an important role in inflammation, indicating the potential involvement of GAS5 in OA. This study was carried out to investigate the function of GAS5 in OA.

METHODS

Expression levels of GAS5 in synovial fluid from 45 OA patients and 45 healthy controls were measured by RT-qPCR. Cell transfections were performed to explore the potential interactions among GAS5, miR-146a, and Smad4 in chondrocytes. Lipopolysaccharide (LPS)-induced cell apoptosis after overexpression of GAS5, miR-146a, and Smad4 was analyzed by cell apoptosis assay.

RESULTS

GAS5 was downregulated in OA. Moreover, LPS treatment downregulated GAS5 in chondrocytes. Interaction between GAS5 could with miR-146a was predicted by bioinformatics analysis and further confirmed by RNA-RNA pulldown assay. However, overexpression of GAS5 and miR-146a did not affect the expression of each other. GAS5 overexpression increased Smad4 expression in chondrocytes. In contrast, miR-146a overexpression downregulated Smad4 in chondrocytes. Moreover, GAS5 and Smad4 overexpression inhibited LPS- induced chondrocytes apoptosis, while miR-146a overexpression played an opposite role and attenuated the effects of GAS5 and Smad4 overexpression on cell apoptosis.

CONCLUSION

GAS5 might sponge miR-146a to upregulate Smad4, thereby suppressing LPS- induced chondrocytes apoptosis.

Role of IL-17 gene polymorphisms in osteoarthritis: A meta-analysis based on observational studies

BACKGROUND

Osteoarthritis (OA) is a chronic complex multifactorial joint disease, and a major degenerative form of arthritis. Existing studies on the association between polymorphisms of the IL-17 gene and the risk of OA in different populations have yielded conflicting findings.

AIM

To investigate the association between polymorphisms of the IL-17 gene and the risk of OA.

METHODS

We conducted a meta-analysis by systematically searching databases, including PubMed, EMBASE, MEDLINE, Cochrane Library, and Google Scholar to evaluate this association by calculating pooled odds ratios with 95% confidence intervals. Moreover, subgroup analyses stratified by ethnicity and OA type were also conducted.

RESULTS

In a total of 6 citations involving 8 studies (2131 cases and 2299 controls), 4 single nucleotide polymorphisms were identified. Of these 4 polymorphisms, 2 (rs2275913, rs763780) were common in five case-control studies. Together, the pooled results revealed that the A allele and genotype AA/GA of the rs2275913 polymorphism, and the C allele and genotype CC of the rs763780 polymorphism in the IL-17 gene increased the risk of OA. Furthermore, stratification analyses by ethnicity and OA type showed that the rs2275913 polymorphism increased the risk of OA among Asians and in knee/hip OA, respectively. In addition, stratification analyses also revealed that the rs763780 polymorphism increased OA risk among both Asians and Caucasians in knee/hip OA.

CONCLUSION

The rs763780 polymorphism of the IL-17F gene increased the risk of OA, whereas the rs2275913 polymorphism of the IL-17A gene increased the risk of OA only among Asians. Due to the limitations of this study, these findings should be validated in future studies.

Osteoarthritis, entheses, and long bone cross-sectional geometry in the Andes: Usage, history, and future directions

Akin to approaches encouraged by Verano (1997) in the Andes, and Ortner (2011, 2012) for general paleopathological studies, this article focuses on accurate descriptions and definitions of osteoarthritis, entheses, and long bone cross-sectional geometry. By evaluating these conditions as part of biological responses to abnormal skeletal changes and biomechanical stress, this research discusses each condition's pathogenesis. Further, this article emphasizes a "small data" approach to evaluating these conditions in ancient culturally and biologically related human populations, where the study samples must have good skeletal preservation, where estimates of age and sex need to be included as major factors, and where abnormalities need to be described and evaluated. This article also discusses global clinical and osteological research on ways scholars are currently trying to establish industry-wide methods to evaluate osteoarthritis, entheses, and long bone cross-sectional geometry. Recent studies have focused on rigorous evaluation of methodological techniques, recording protocols, and inter- and intra-observer error problems. Additionally, scholars have focused on physical intensity of movement using biomechanics, evaluated burials of known occupation, and used complex statistical methods to help interpret skeletal changes associated with these conditions. This article also narrows to focus on these conditions within thematic "small data" areas throughout the Andes. This research concludes with describing future directions to understand skeletal changes, such as more multidisciplinary studies between osteologists and pathologists, collaborations with living people to collect CT, x-rays, or computer-aided motion capture, and a stronger focus on how these conditions correlate with intense biomechanical changes in younger individuals.

LncRNA CTBP1-AS2 is upregulated in osteoarthritis and increases the methylation of miR-130a gene to inhibit chondrocyte proliferation

OBJECTIVES

LncRNA CTBP1-AS2 has been reported to be involved in type 2 diabetes and cardiomyocyte hypertrophy, while its roles in other human diseases are unknown. Our preliminary deep sequencing analysis showed altered expression of CTBP1-AS2 in osteoarthritis (OA). In addition, CTBP1-AS2 was inversely correlated with miR-130a. This study was therefore carried out to investigate the interactions between CTBP1-AS2 and miR-130a in OA.

METHODS

Synovial fluid was collected from 62 OA patients and 62 healthy controls. RT-qPCR was performed to determine the expression levels of CTBP1-AS2 and miR-130a in synovial fluid. Cell transfections were performed to investigate the interactions between CTBP1-AS2 and miR-130a. Methylation-specific PCR (MSP) was performed to assess the effects of CTBP1-AS2 on the methylation of miR-130a. Cell counting Kit-8 (CCK-8) assay was performed to evaluate the roles of CTBP1-AS2 and miR-130a in regulating proliferation of chondrocytes.

RESULTS

The results showed that CTBP1-AS2 was upregulated in OA and inversely correlated with miR-130a. In chondrocytes of OA patients, overexpression of CTBP1-AS2 led to increased methylation of miR-130a gene and downregulated expression of miR-130a, while overexpression of miR-130a did not affect the expression of CTBP1-AS2. In contrast, no interaction between CTBP1-AS2 and miR-130a was observed in chondrocytes from healthy adults. Analysis of chondrocyte proliferation showed that overexpression of miR-130a led to increased proliferation rate of chondrocytes extracted from OA patients. Overexpression of CTBP1-AS2 led to decreased proliferation rate of chondrocytes and reversed the effects of overexpressing miR-130a.

CONCLUSION

Therefore, CTBP1-AS2 is upregulated in OA and may increase the methylation of miR-130a gene to inhibit chondrocyte proliferation. Key Points • CTBP1-AS2 is overexpressed in OA and may downregulate miR-130a through methylation to suppress the proliferation of chondrocytes. • The interaction between CTBP1-AS2 and miR-130a is indirect and mediated by certain pathological mediators.

Long noncoding RNA LINC00461 induced osteoarthritis progression by inhibiting miR-30a-5p

Mounting studies have shown that long noncoding RNAs (lncRNAs) play important roles in the development and occurrence of several human diseases. However, the role of LINC00461 in osteoarthritis (OA) remains obscure. A CCK-8 assay was performed to detect cell viability, and qRT-PCR analysis was used to measure mRNA expression. The targeting by miR-30a-5p of the LINC00461 3'UTR was detected using a luciferase reporter assay. Our data indicated that the inflammatory mediators IL-6 and TNF-α induced LINC00461 expression in chondrocytes and that the expression of LINC00461 was upregulated in OA tissues. Furthermore, we showed that TNF-α and IL-6 suppressed the expression of miR-30a-5p and that miR-30a-5p expression was lower in OA tissues than in normal samples. The expression level of miR-30a-5p in OA tissues was negatively related to LINC00461 expression. In addition, we showed that LINC00461 directly interacted with miR-30a-5p in chondrocytes. Elevated expression of LINC00461 induced chondrocyte proliferation, cell cycle progression, inflammation, and extracellular matrix (ECM) degradation. However, we demonstrated that ectopic expression of miR-30a-5p suppressed cell growth, cell cycle progression, inflammation and ECM degradation. Finally, we found that overexpression of LINC00461 enhanced chondrocyte proliferation, cell cycle progression, inflammation, and ECM degradation by downregulating miR-30a-5p. These data demonstrated that LINC00461 may modulate the development of OA by suppressing miR-30a-5p expression in chondrocytes. We propose that LINC00461 and miR-30a-5p may be potential therapeutic and diagnostic targets for OA.

The role and function of long non-coding RNAs in osteoarthritis

Osteoarthiritis (OA) is the most prevalent disease of articulating joints in human that frequently results in joint pain, movement limitations, inflammation, and progressive degradation of articular cartilage. The etiology of OA is not completely clear and there is no full treatment for this disease. Molecular investigations have revealed the involvement of non-coding RNAs such as Long non-coding RNAs (lncRNAs) in OA pathogenesis. LncRNAs play roles in multiple cellular and biological processes. Moreover, numerous lncRNAs are differentially expressed in human OA cartilage. In this review, we underlie the increasing evidence for the critical role of lncRNAs in OA pathogenesis reviewing the latest researches.

MiR93-5p inhibits chondrocyte apoptosis in osteoarthritis by targeting lncRNA CASC2

Background

It has been reported that miR-93-5p and long non-coding RNA (lncRNA) Cancer Susceptibility 2 (CASC2) play opposite roles in regulating chondrocyte apoptosis, indicating the possible interaction between them. This study aimed to investigate the interaction between miR-93-5p and lncRNA CASC2 in chondrocyte apoptosis, which plays critical roles in osteoarthritis (OA).

Methods

The interaction between CASC2 and miR-93-5p was analyzed by dual luciferase assay and overexpression experiments. Levels of CASC2 and miR-93-5p in plasma sample from OA patients and healthy controls were measured by RT-qPCR. The roles of CASC2 and miR-93-5p in regulating the apoptosis of chondrocyte induced by LPS were analyzed by cell apoptosis assay.

Results

Through bioinformatics analysis we observed the potential interaction between CASC2 and miR-93-5p, which was confirmed by dual luciferase assay. In OA patients, miR-93-5p was downregulated, while CASC2 was upregulated, and they were inversely correlated. LPS treatment led to downregulated miR-93-5p and upregulated CASC2. Overexpression of miR-93-5p led to the downregulated CASC2 in chondrocytes. Under LPS treatment, CASC2 overexpression promoted the apoptosis of chondrocyte. MiR-93-5p overexpression played an opposite role and attenuated the effects of CASC2 overexpression.

Conclusion

MiR-93-5p was downregulated in OA may inhibit LPS-induced chondrocyte apoptosis by targeting lncRNA CASC2.

Osteoarthritis from evolutionary and mechanistic perspectives

Developmental osteogenesis and the pathologies associated with tissues that normally are mineralized are active areas of research. All of the basic cell types of skeletal tissue evolved in early aquatic vertebrates. Their characteristics, transcription factors, and signaling pathways have been conserved, even as they adapted to the challenge imposed by gravity in the transition to terrestrial existence. The response to excess mechanical stress (among other factors) can be expressed in the pathologic phenotype described as osteoarthritis (OA). OA is mediated by epigenetic modification of the same conserved developmental gene networks, rather than by gene mutations or new chemical signaling pathways. Thus, these responses have their evolutionary roots in morphogenesis. Epigenetic channeling and heterochrony, orchestrated primarily by microRNAs, maintain the sequence of these responses, while allowing variation in their timing that depends at least partly on the life history of the individual.

Rehabilitation protocol with or without mobile health in overweight and obese knee osteoarthritis patients - a pilot study

Knee osteoarthritis (OA) is a degenerative and weight bearing joint disease that resulted from wear and tear of articular cartilage. It is more common in the overweight and obese knee OA patients. The objectives of pilot study were to assess the feasibility, acceptability and challenges of study design, study setting and tools of lower limb rehabilitation protocol among the knee OA patients who are overweight and obese. Twelve overweight and obese knee OA patients attending a Teaching Bay in the Pakistan were enrolled in the study and completed 6 training sessions over 2 weeks. The participants were divided randomly into Intervention Group with Mobile Health (IGW-mH), Intervention Group without Mobile Health (IGWO-mH) and the Control Group (CG). Both intervention groups were provided fifteen days of lower limb rehabilitation protocol but the CG did not. Two text messages per day for three days a week were sent to IGW-mH as a reminder to carry on their training session and instructions of daily care. All participants of intervention groups showed willingness to randomization and adherence to training sessions. The results indicated that eligibility criteria, recruitment rate and randomization procedures were feasible and there were no adverse events from training sessions. The participants demanded Urdu translation and pictures of lower limb rehabilitation protocol. Key words: mobile health technology, overweight, knee, osteoarthritis,

Gene Expression Profiles of Peripheral Blood Monocytes in Osteoarthritis and Analysis of Differentially Expressed Genes

Background

There is little understanding of the molecular processes involved in the pathogenesis of osteoarthritis, limiting early diagnosis and effective treatment of OA. Use of genechips can provide insights into the molecular pathogenesis of diseases. In this study, determination of gene expression profiles of osteoarthritis peripheral blood mononuclear cells will allow exploration of the molecular pathogenesis of OA and find out more candidate biomarkers and potential drug targets of OA.

Result

A total of 1231 DEGs were screened out including 791 upregulated DEGs and 440 downregulated DEGs. The most significant upregulated DEG was RPL38, which may inhibit chondrocyte differentiation and synthesis of the extracellular matrix. PIK3CA, PIK3CB, PIK3CD, PIK3R1, MAPK14, IL1A, JUND, FOSL2, and PPP3CA were the gene symbols of the osteoclast differentiation pathway which was the most significant pathway enriched by DEGs. However, the MAPK signaling pathway occupied the core position of all the pathways which can regulate apoptosis, cell cycle, wnt signaling pathway, p53 signaling pathway, and phosphatidylinositol signaling system. Furthermore, PI3Ks may regulate IL1A, JUND, FOSL2 and PPP3CA through the MAPK signaling pathway.

Conclusion

These identified DEGs and pathways may be novel biomarkers to monitor the changes of OA and can be a potential drug target for the treatment of OA.

Evaluating the Potential of Younger Cases and Older Controls Cohorts to Improve Discovery Power in Genome-Wide Association Studies of Late-Onset Diseases

For more than a decade, genome-wide association studies have been making steady progress in discovering the causal gene variants that contribute to late-onset human diseases. Polygenic late-onset diseases in an aging population display a risk allele frequency decrease at older ages, caused by individuals with higher polygenic risk scores becoming ill proportionately earlier and bringing about a change in the distribution of risk alleles between new cases and the as-yet-unaffected population. This phenomenon is most prominent for diseases characterized by high cumulative incidence and high heritability, examples of which include Alzheimer’s disease, coronary artery disease, cerebral stroke, and type 2 diabetes, while for late-onset diseases with relatively lower prevalence and heritability, exemplified by cancers, the effect is significantly lower. In this research, computer simulations have demonstrated that genome-wide association studies of late-onset polygenic diseases showing high cumulative incidence together with high initial heritability will benefit from using the youngest possible age-matched cohorts. Moreover, rather than using age-matched cohorts, study cohorts combining the youngest possible cases with the oldest possible controls may significantly improve the discovery power of genome-wide association studies.

MicroRNAs and Osteoarthritis

An imbalance in gene expressional events skewing chondrocyte anabolic and catabolic pathways toward the latter causes an aberrant turnover and loss of extracellular matrix proteins in osteoarthritic (OA) articular cartilage. Thus, catabolism results in the elevated loss of extracellular matrix proteins. There is also evidence of an increase in the frequency of chondrocyte apoptosis that compromises the capacity of articular cartilage to undergo repair. Although much of the fundamental OA studies over the past 20 years identified and characterized many genes relevant to pro-inflammatory cytokines, apoptosis, and matrix metalloproteinases (MMPs)/a disintegrin and metalloproteinase with thrombospondin motif (ADAMTS), more recent studies focused on epigenetic mechanisms and the associated role of microRNAs (miRs) in regulating gene expression in OA cartilage. Thus, several miRs were identified as regulators of chondrocyte signaling pathways, apoptosis, and proteinase gene expression. For example, the reduced expression of miR-146a was found to be coupled to reduced type II collagen (COL2) in OA cartilage, whereas MMP-13 levels were increased, suggesting an association between MMP-13 gene expression and COL2A1 gene expression. Results of these studies imply that microRNAs could become useful in the search for diagnostic biomarkers, as well as providing novel therapeutic targets for intervention in OA.

Predictors of Osteoarthritis Pain: the Importance of Resilience

PURPOSE OF REVIEW

Osteoarthritis (OA) is one of the most common and disabling forms of arthritis worldwide, with joint pain being a primary symptom. Given that clinical symptoms often show poor concordance with tissue damage in OA, processes other than joint remodeling likely play a role in the condition. Using the biopsychosocial model of pain as a guiding framework, the purpose of this review is to highlight the extra-articular mechanisms that contribute to pain and dysfunction in OA, with a specific focus on resilience.

RECENT FINDINGS

Whereas previous research has mostly focused on risk factors for worsening of OA pain, recently emerging evidence places greater emphasis on the identification of protective mechanisms that enhance pain adaptation and palliate the negative effects of joint pain. In view of this new and important research, more emphasis should be placed on endogenous pain modulation and, in particular, pain attenuation. The result of such work could serve as a basis for optimizing treatment in the OA population.

Mechanisms of Osteoarthritic Pain. Studies in Humans and Experimental Models

Pain due to osteoarthritis (OA) is one of the most frequent causes of chronic pain. However, the mechanisms of OA pain are poorly understood. This review addresses the mechanisms which are thought to be involved in OA pain, derived from studies on pain mechanisms in humans and in experimental models of OA. Three areas will be considered, namely local processes in the joint associated with OA pain, neuronal mechanisms involved in OA pain, and general factors which influence OA pain. Except the cartilage all structures of the joints are innervated by nociceptors. Although the hallmark of OA is the degradation of the cartilage, OA joints show multiple structural alterations of cartilage, bone and synovial tissue. In particular synovitis and bone marrow lesions have been proposed to determine OA pain whereas the contribution of the other pathologies to pain generation has been studied less. Concerning the peripheral neuronal mechanisms of OA pain, peripheral nociceptive sensitization was shown, and neuropathic mechanisms may be involved at some stages. Structural changes of joint innervation such as local loss and/or sprouting of nerve fibers were shown. In addition, central sensitization, reduction of descending inhibition, descending excitation and cortical atrophies were observed in OA. The combination of different neuronal mechanisms may define the particular pain phenotype in an OA patient. Among mediators involved in OA pain, nerve growth factor (NGF) is in the focus because antibodies against NGF significantly reduce OA pain. Several studies show that neutralization of interleukin-1β and TNF may reduce OA pain. Many patients with OA exhibit comorbidities such as obesity, low grade systemic inflammation and diabetes mellitus. These comorbidities can significantly influence the course of OA, and pain research just began to study the significance of such factors in pain generation. In addition, psychologic and socioeconomic factors may aggravate OA pain, and in some cases genetic factors influencing OA pain were found. Considering the local factors in the joint, the neuronal processes and the comorbidities, a better definition of OA pain phenotypes may become possible. Studies are under way in order to improve OA and OA pain monitoring.

The Role of Malnutrition during Pregnancy and Its Effects on Brain and Skeletal Muscle Postnatal Development

“Foetal programming” refers to nutritional and hormonal variations during pregnancy. A maternal proper diet has a fundamental role in decreasing pregnancy complications and to prevent possible diseases in postnatal life. In our narrative review, we analyze and discuss the role of malnutrition during pregnancy and its effects on pre- and postnatal development of embryos. Our review proposes a comprehensive and careful analysis of the studies in this field regarding malnutrition and foetal programming. Evidence shows that nutrient imbalance before implantation may result in somatic hypoevolutism at birth, and endocrine and metabolic dysfunctions in postnatal life. In addition, the maternal malnutrition could exert a suppressive effect on the maternal and foetal immune response. It could also affect both the proliferation of myogenic precursors reducing the number of muscle fibres and the future reproductive maturation with possible consequent impaired fertility and quality of gametes. In conclusion, it is necessary to develop dietary strategies to optimize nutrition, not only during pregnancy but already when it is programmed, in order to improve the outcomes of pregnancy, promote growth, healthy child development, reduce the risk of chronic diseases, and slow down the metabolic decline associated with aging.

Mesenchymal Stem Cell-Based Cartilage Regeneration Approach and Cell Senescence: Can We Manipulate Cell Aging and Function?

Aging is the most prominent risk factor triggering several degenerative diseases, such as osteoarthritis (OA). Due to its poor self-healing capacity, once injured cartilage needs to be reestablished. This process might be approached through resorting to cell-based therapies and/or tissue engineering. Human mesenchymal stem cells (MSCs) represent a promising approach due to their chondrogenic differentiation potential. Presently, in vitro chondrogenic differentiation of MSCs is limited by two main reasons as follows: aging of MSCs, which determines the loss of cell proliferative and differentiation capacity and MSC-derived chondrocyte hypertrophic differentiation, which limits the use of these cells in cartilage tissue regeneration approach. The effect of aging on MSCs is fundamental for stem cell-based therapy development, especially in older subjects. In the present review we focus on homeostasis alterations occurring in MSC-derived chondrocytes during in vitro aging. Moreover, we deal with potential cell aging regulation approaches, such as cell stimulation through telomerase activators, mechanical strain, and epigenetic regulation. Future investigations in this field might provide new insights into innovative strategies for cartilage regeneration and potentially inspire novel therapeutic approaches for OA treatment.

Engineered cartilage regeneration from adipose tissue derived-mesenchymal stem cells: A morphomolecular study on osteoblast, chondrocyte and apoptosis evaluation

The poor self-repair capacity of cartilage tissue in degenerative conditions, such as osteoarthritis (OA), has prompted the development of a variety of therapeutic approaches, such as cellular therapies and tissue engineering based on the use of mesenchymal stem cells (MSCs). The aim of this study is to demonstrate, for the first time, that the chondrocytes differentiated from rat adipose tissue derived-MSCs (AMSCs), are able to constitute a morphologically and biochemically healthy hyaline cartilage after 6 weeks of culture on a Collagen Cell Carrier (CCC) scaffold. In this study we evaluated the expression of some osteoblasts (Runt-related transcription factor 2 (RUNX2) and osteocalcin), chondrocytes (collagen I, II and lubricin) and apoptosis (caspase-3) biomarkers in undifferentiated AMSCs, differentiated AMSCs in chondrocytes cultured in monolayer and AMSCs-derived chondrocytes seeded on CCC scaffolds, by different techniques such as immunohistochemistry, ELISA, Western blot and gene expression analyses. Our results showed the increased expression of collagen II and lubricin in AMSCs-derived chondrocytes cultured on CCC scaffolds, whereas the expression of collagen I, RUNX2, osteocalcin and caspase-3 resulted decreased, when compared to the controls. In conclusion, this innovative basic study could be a possible key for future therapeutic strategies for articular cartilage restoration through the use of CCC scaffolds, to reduce the morbidity from acute cartilage injuries and degenerative joint diseases.

Pain in knee osteoarthritis is associated with variation in the neurokinin 1/substance P receptor (TACR1) gene

BACKGROUND

Substance P (SP) is a pain- and inflammation-related neuropeptide which preferentially binds to the neurokinin receptor 1 (NK₁ ). SP and NK₁ receptors have been implicated in joint pain, inflammation and damage in animal models and human studies of osteoarthritis (OA). The aim of this study was to test if genetic variation at the neurokinin 1 receptor gene (TACR1) is associated with pain in individuals with radiographic knee OA.

METHODS

Participants from the Genetics of OA and Lifestyle study were used for the discovery group (n = 1615). Genotype data for six SNPs selected to cover most variation in the TACR1 gene were used to test for an association with symptomatic OA. Replication analysis was performed using data from the Chingford 1000 Women Study, Hertfordshire Cohort Study, Tasmanian Older Adult Cohort Study and the Clearwater OA Study. In total, n = 1715 symptomatic OA and n = 735 asymptomatic OA individuals were analysed.

RESULTS

Out of six SNPs tested in the TACR1 gene, one (rs11688000) showed a nominally significant association with a decreased risk of symptomatic OA in the discovery cohort. This was then replicated in four additional cohorts. After adjusting for age, gender, body mass index and radiographic severity, the G (minor) allele at rs11688000 was associated with a decreased risk of symptomatic OA compared to asymptomatic OA cases (p = 9.90 × 10^-4 , OR = 0.79 95% 0.68-0.90 after meta-analysis).

CONCLUSIONS

This study supports a contribution from the TACR1 gene in human OA pain, supporting further investigation of this gene's function in OA.

SIGNIFICANCE

This study contributes to the knowledge of the genetics of painful osteoarthritis, a condition which affects millions of individuals worldwide. Specifically, a contribution from the TACR1 gene to modulating pain sensitivity in osteoarthritis is suggested.

Procyanidins Mitigate Osteoarthritis Pathogenesis by, at Least in Part, Suppressing Vascular Endothelial Growth Factor Signaling

Procyanidins are a family of plant metabolites that have been suggested to mitigate osteoarthritis pathogenesis in mice. However, the underlying mechanism is largely unknown. This study aimed to determine whether procyanidins mitigate traumatic injury-induced osteoarthritis (OA) disease progression, and whether procyanidins exert a chondroprotective effect by, at least in part, suppressing vascular endothelial growth factor signaling. Procyanidins (extracts from pine bark), orally administered to mice subjected to surgery for destabilization of the medial meniscus, significantly slowed OA disease progression. Real-time polymerase chain reaction revealed that procyanidin treatment reduced expression of vascular endothelial growth factor and effectors in OA pathogenesis that are regulated by vascular endothelial growth factor. Procyanidin-suppressed vascular endothelial growth factor expression was correlated with reduced phosphorylation of vascular endothelial growth factor receptor 2 in human OA primary chondrocytes. Moreover, components of procyanidins, procyanidin B2 and procyanidin B3 exerted effects similar to those of total procyanidins in mitigating the OA-related gene expression profile in the primary culture of human OA chondrocytes in the presence of vascular endothelial growth factor. Together, these findings suggest procyanidins mitigate OA pathogenesis, which is mediated, at least in part, by suppressing vascular endothelial growth factor signaling.

Altered joint tribology in osteoarthritis: Reduced lubricin synthesis due to the inflammatory process. New horizons for therapeutic approaches

Osteoarthritis (OA) is the most common form of joint disease. This review aimed to consolidate the current evidence that implicates the inflammatory process in the attenuation of synovial lubrication and joint tissue homeostasis in OA. Moreover, with these findings, we propose some evidence for novel therapeutic strategies for preventing and/or treating this complex disorder. The studies reviewed support that inflammatory mediators participate in the onset and progression of OA after joint injury. The flow of pro-inflammatory cytokines following an acute injury seems to be directly associated with altered lubricating ability in the joint tissue. The latter is associated with reduced level of lubricin, one of the major joint lubricants. Future research should focus on the development of new therapies that attenuate the inflammatory process and restore lubricin synthesis and function. This approach could support joint tribology and synovial lubrication leading to improved joint function and pain relief.