Large-scale meta-analysis of interleukin-1 beta and interleukin-1 receptor antagonist polymorphisms on risk of radiographic hip and knee osteoarthritis and severity of knee osteoarthritis

Saikosaponin D alleviates inflammatory response of osteoarthritis and mediates autophagy via elevating microRNA-199-3p to target transcription Factor-4

OBJECTIVE

This study was to investigate the underlying mechanism by which Saikosaponin D (SSD) mitigates the inflammatory response associated with osteoarthritis (OA) and regulates autophagy through upregulation of microRNA (miR)-199-3p and downregulation of transcription Factor-4 (TCF4).

METHODS

A mouse OA model was established. Mice were intragastrically administered with SSD (0, 5, 10 μmol/L) or injected with miR-199-3p antagomir into the knee. Then, pathological changes in cartilage tissues were observed. Normal chondrocytes and OA chondrocytes were isolated and identified. Chondrocytes were treated with SSD and/or transfected with oligonucleotides or plasmid vectors targeting miR-199-3p and TCF4. Cell viability, apoptosis, inflammation, and autophagy were assessed. miR-199-3p and TCF4 expressions were measured, and their targeting relationship was analyzed.

RESULTS

In in vivo experiments, SSD ameliorated cartilage histopathological damage, decreased inflammatory factor content and promoted autophagy in OA mice. miR-199-3p expression was downregulated and TCF4 expression was upregulated in cartilage tissues of OA mice. miR-199-3p expression was upregulated and TCF4 expression was downregulated after SSD treatment. Downregulation of miR-199-3p attenuated the effect of SSD on OA mice. In in vitro experiments, SSD inhibited the inflammatory response and promoted autophagy in OA chondrocytes. Downregulation of miR-199-3p attenuated the effect of SSD on OA chondrocytes. In addition, upregulation of miR-199-3p alone inhibited inflammatory responses and promoted autophagy in OA chondrocytes. miR-199-3p targeted TCF4. Upregulation of TCF4 attenuated the effects of miR-199-3p upregulation on OA chondrocytes.

CONCLUSIONS

SSD alleviates inflammatory response and mediates autophagy in OA via elevating miR-199-3p to target TCF4.

The Role of Genetics and Epigenetic Regulation in the Pathogenesis of Osteoarthritis

Osteoarthritis (OA) is progressive disease characterised by cartilage degradation, subchondral bone remodelling and inflammation of the synovium. The disease is associated with obesity, mechanical load and age. However, multiple pro-inflammatory immune mediators regulate the expression of metalloproteinases, which take part in cartilage degradation. Furthermore, genetic factors also contribute to OA susceptibility. Recent studies have highlighted that epigenetic mechanisms may regulate the expression of OA-associated genes. This review aims to present the mechanisms of OA pathogenesis and summarise current evidence regarding the role of genetics and epigenetics in this process.

Cerium oxide nanoparticles protect against chondrocytes and cartilage explants from oxidative stress via Nrf2/HO-1 pathway in temporomandibular joint osteoarthritis

Oxidative stress is closely linked to the etiology of temporomandibular joint osteoarthritis. (TMJ-OA) and is an important therapeutic target. Cerium oxide nanoparticles (CNPs) have been broadly studied owing to their powerful antioxidant properties and potential preventive and therapeutic effects against chronic diseases. The current study was designed to explore the protective effects of CNPs on the progression of TMJ-OA and their potential mechanisms. We detected the ability of CNPs to eliminate reactive oxygen species (ROS) in chondrocytes. Moreover, their protective effects on chondrocytes were detected in the level of gene and protein. Furthermore, TUNEL assay, histology and safranin O-fast green staining were used to detect the beneficial effects of CNPs on cartilage explants. The mechanism of CNPs, protecting condylar cartilage by reducing inflammation, was further explored by knocking down the Nuclear factor-erythroid 2-related factor (Nrf2) gene. CNPs could reduce the ROS levels in chondrocytes and cartilage explants and reverse the IL-1β-induced imbalance of cartilage matrix metabolism and apoptosis. The protective effects of CNPs on cartilage were lost after key antioxidant factors including Nrf2 and heme-oxygenase 1(HO-1) were significantly reduced. In conclusion, this study demonstrated for the first time that activating the Nrf2/HO-1 signaling pathway by CNPs might have therapeutic potential for TMJ-OA.

Perlecan: Roles in osteoarthritis and potential treating target

Osteoarthritis (OA) is the most common joint disease, affecting hundreds of millions of people globally, which leads to a high cost of treatment and further medical care and an apparent decrease in patient prognosis. The recent view of OA pathogenesis is that increased vascularity, bone remodeling, and disordered turnover are influenced by multivariate risk factors, such as age, obesity, and overloading. The view also reveals the gap between the development of these processes and early stage risk factors. This review presents the latest research on OA-related signaling pathways and analyzes the potential roles of perlecan, a typical component of the well-known protective structure against osteoarthritic pericellular matrix (PCM). Based on the experimental results observed in end-stage OA models, we summarized and analyzed the role of perlecan in the development of OA. In normal cartilage, it plays a protective role by maintaining the integrin of PCM and sequesters growth factors. Second, perlecan in cartilage is required to not only activate vascular epithelium growth factor receptor (VEGFR) signaling of endothelial cells for vascular invasion and catabolic autophagy, but also for different signaling pathways for the catabolic and anabolic actions of chondrocytes. Finally, perlecan may participate in pain sensitization pathways.

Corynoline Alleviates Osteoarthritis Development via the Nrf2/NF-κB Pathway

Purpose

OA is a multifactorial joint disease in which inflammation plays a substantial role in the destruction of joints. Corynoline (COR), a component of Corydalis bungeana Turcz., has anti-inflammatory effects.

Materials and Methods

We evaluated the significance and potential mechanisms of COR in OA development. The viabilities of chondrocytic cells upon COR exposure were assessed by CCK-8 assays. Western blot, qPCR, and ELISA were used to assess extracellular matrix (ECM) degeneration and inflammation. The NF-κB pathway was evaluated by western blot and immunofluorescence (IF). Prediction of the interacting proteins of COR was done by molecular docking, while Nrf2 knockdown by siRNAs was performed to ascertain its significance. Micro-CT, H&E, Safranin O-Fast Green (S-O), toluidine blue staining, and immunohistochemical examination were conducted to assess the therapeutic effects of COR on OA in destabilization of medial meniscus (DMM) models.

Results

COR inhibited ECM degeneration and proinflammatory factor levels and modulated the NF-κB pathway in IL-1β-treated chondrocytes. Mechanistically, COR bound Nrf2 to downregulate the NF-κB pathway. Moreover, COR ameliorated the OA process in DMM models.

Conclusion

We suggest that COR ameliorates OA progress through the Nrf2/NF-κB axis, indicating COR may have a therapeutic potential for OA.

Interleukin-1 genetic polymorphisms in knee osteoarthritis: What do we know? A meta-analysis and systematic review

PURPOSE

Interleukin-1 is the main proinflammatory cytokine in osteoarthritis (OA). Several single-nucleotide polymorphisms (SNPs) within the IL-1 gene cluster (IL-1β, IL-1R1, and IL-1RN) have been determined, but their associations with knee OA remain poorly understood. The present study aimed to identify the associations between IL-1 SNPs and knee osteoarthritis.

METHODS

This meta-analysis and systematic review included all comparative studies published in the MEDLINE/PubMed, Embase, Google Scholar, and Cochrane Library databases. We performed a systematic search to identify relevant studies on the evaluation of the correlation between the IL-1 gene and knee OA published up to February 2020 that met the eligibility criteria. Nine studies on a total of 2256 knees with OA and 3527 healthy knees met the eligibility criteria. Results associated with IL-1A, IL-1B, IL-1R1, and IL-1RN SNPs were extracted and compared between knees with OA and healthy knees. Methodological quality was assessed using the Newcastle-Ottawa scale (NOS). All studies with fair or good quality were included.

RESULTS

The meta-analysis showed that the risk of knee OA is decreased by the IL-1RN*1 and IL-1RN*1/*1 genotypes and increased by the IL-1RN*2 and I-L1RN*1/*2 genotypes. The systematic review revealed only two studies associating the IL-1RN allele, none associating the IL-1B polymorphism, and only one study associating IL-1A and IL-1R1 polymorphisms with knee OA.

CONCLUSIONS

Several IL-1RN alleles and genotypes play a role in knee OA but other genetic variations in the IL-1 region were still conflicting in its association with knee OA.

Evaluation of Serum Interleukin-38 Levels in Different Radiographic Grades of Idiopathic Knee Osteoarthritis

The aim of this study was to assess interleukin-1β (IL-1β), IL-1Ra, IL-36, and IL-38 levels together with hs-CRP levels in patients with different radiographic grades of knee osteoarthritis (OA) in comparison to healthy individuals. Consecutive patients aged over 50 years who were admitted to our Orthopaedics and Traumatology department between November 2018 and March 2019 and diagnosed as knee OA according to the American College of Rheumatology criteria were included in this prospective case-control study. Patients with knee OA were staged according to radiographic Kellgren-Lawrence (K-L) classification and 20 patients were assigned to each group. An age and gender matched control group consisted healthy volunteers with no clinical and radiographic sign of arthritis were conducted as the control group. Venous blood samples were collected and assessed for hs-CRP, IL-1β, IL-1Ra, IL-36, and IL-38 levels using the double-antibody sandwich ELISA method. The hs-CRP, IL-1β, IL-36 and IL-38 levels did not significantly differ among controls and independent radiographic stage groups except IL-1Ra levels which was significantly higher in K-L grade 4 knee OA groups compared to healthy controls (P = 0.045). When we compared all patients with knee OA and healthy controls, we detected that IL-1 and IL-1Ra were significantly lower and IL-38 levels were significantly higher in healthy control group compared to patients with knee OA (P = <0.001, <0.001, and 0.019, respectively). According to results obtained from our study, IL-1β, IL-1Ra, and IL-38 levels significantly differed between healthy individuals and patients with knee OA. However, we did not observe a significant difference and correlation between radiographic grade of knee OA and interleukin levels.

Isovitexin Depresses Osteoarthritis Progression via the Nrf2/NF-κB Pathway: An in vitro Study

Purpose

Osteoarthritis (OA) is a multifactorial joint disease and inflammatory processes contribute to joint destruction. Isovitexin (IVX) is a flavone component found in passion flower, Cannabis and, and the palm that is known for its anti-inflammatory properties.

Materials and Methods

This study investigated in vitro the role and underlying mechanism used by IVX in its regulation of OA development. Effects of IVX on the viability of chondrocytes were measured by CCK-8 assays. The phenotypes of extracellular matrix (ECM) degeneration and inflammation were measured by qPCR, Western blot, and ELISA; and NF-κB pathway was detected by immunofluorescence and Western blot. Molecular docking was applied to predict the interacting protein of IVX, while Nrf2 was knocked down by siRNAs to confirm its role.

Results

We demonstrated that IVX suppressed ECM degeneration and suppressed pro-inflammatory factors in IL-1β-treated chondrocytes. Additionally, IVX impact on NF-κB signaling in IL-1β-exposed chondrocytic cells; Mechanistically, it was also demonstrated in molecular docking and knock down studies that IVX might bind to Nrf2 to suppress NF-κB pathway.

Conclusion

Our data suggest that IVX halts OA disease advancement through the Nrf2/NF-κB axis, suggesting a possibility of IVX as a target for OA therapy.

Serum C-reactive protein metabolite (CRPM) is associated with incidence of contralateral knee osteoarthritis

The heterogeneous nature of osteoarthritis (OA) and the need to subtype patients is widely accepted in the field. The biomarker CRPM, a metabolite of C-reactive protein (CRP), is released to the circulation during inflammation. Blood CRPM levels have shown to be associated with disease activity and response to treatment in rheumatoid arthritis (RA). We investigated the level of blood CRPM in OA compared to RA using data from two phase III knee OA and two RA studies (N = 1591). Moreover, the association between CRPM levels and radiographic progression was investigated. The mean CRPM levels were significantly lower in OA (8.5 [95% CI 8.3–8.8] ng/mL, n = 781) compared to the RA patients (12.8 [9.5–16.0] ng/mL, n = 60); however, a significant subset of OA patients (31%) had CRPM levels (≥ 9 ng/mL) comparable to RA. Furthermore, OA patients (n = 152) with CRPM levels ≥ 9 ng/mL were more likely to develop contra-lateral knee OA assessed by X-ray over a two-year follow-up period with an odds ratio of 2.2 [1.0–4.7]. These data suggest that CRPM is a blood-based biochemical marker for early identification OA patients with an inflammatory phenotype.

Inhibition of PI3K/Akt/NF-κB signaling by Aloin for ameliorating the progression of osteoarthritis: In vitro and in vivo studies

Osteoarthritis (OA) is a progressive and degenerative joint disease. Aloin is a bitter and yellow-brown-coloured compound from the Aloe plant and is allowed for use in foods as a "natural flavour". In our study, we examined the protective effects of Aloin on the inhibition of OA development as well as its underlying mechanism in both in vitro and vivo experiments. In in-vitro experiments, the protective effect of aloin on the anabolism and catabolism of the extracellular matrix (ECM) induced by IL-1 β in chondrocytes by inhibiting the expression of pro-inflammatory factors, including TNF-α (p = 0.016), IL-6 (p = 0.006), iNOS (p = 0.001) and COX-2 (p = 0.006). Mechanistically, Aloin suppressed the IL-1β-induced activation of the PI3K/Akt/NF-κB signalling pathway cascades. Moreover, molecular docking studies demonstrated that Aloin bound strongly to PI3K. In vivo, Aloin ameliorated the OA process in the destabilization of the medial meniscus (DMM) model. In summary, our findings demonstrate that Aloin ameliorates the progression of OA via the PI3K/Akt/NF-κB signalling pathways, which supports Aloin as a promising therapeutic agent for the treatment of OA.

Resveratrol alleviates the interleukin-1β-induced chondrocytes injury through the NF-κB signaling pathway

BACKGROUND

Osteoarthritis (OA) is a regular age-related disease that affects millions of people. Resveratrol (RSV) is a flavonoid with a stilbene structure with different pharmacological effects. The purpose of the experiment was to evaluate the protective role of RSV against the human OA chondrocyte injury induced by interleukin-1β (IL-1β).

METHODS

Chondrocytes were isolated from OA patients and identified by type II collagen, safranin O staining, and toluidine blue staining. Differentially expressed genes in chondrocytes treated RSV were identified by RNA sequencing. Kyoto encyclopedia of genes and genomes (KEGG) pathway as well as gene ontology (GO) were further conducted through Metascape online tool. A cell counting kit-8 (CCK-8) assay was applied to discover the viability of chondrocytes (6, 12, 24, and 48 μM). Many genes associated with inflammation and matrix degradation are evaluated by real-time PCR (RT-PCR) as well as western blot (WB). The mechanism of RSV for protecting IL-1β induced chondrocytes injury was further measured through immunofluorescence and WB assays.

RESULTS

A total of 845 differentially expressed genes (upregulated = 499, downregulated = 346) were found. These differentially expressed genes mainly enriched into negative regulation of catabolic process, autophagy, and cellular catabolic process, intrinsic apoptotic, apoptotic, and regulation of apoptotic signaling pathway, cellular response to abiotic stimulus, external stimuli, stress, and radiation. These differentially expressed genes were obviously enriched in NF-kB signaling pathway. RSV at the concentration of 48 μM markedly weakened the viability of the cells after 24 h of treatment (87% vs 100%, P < 0.05). No obvious difference was observed between the 6, 12, and 24 μM groups (106% vs 100%, 104% vs 100%, 103% vs 100%, P > 0.05). RSV (24 μM) also markedly depressed the levels of PGE2 and NO induced by IL-1β by 25% and 29% respectively (P < 0.05). Our experiment pointed out that RSV could dramatically inhibit the inflammatory response induced by IL-1β, including the MMP-13, MMP-3, and MMP-1 in human OA chondrocytes by 50%, 35%, and 33% respectively. On the other hand, RSV inhibited cyclooxygenase-2 (COX-2), matrix metalloproteinase-1 (MMP-1), MMP-3, MMP-13, and inducible nitric oxide synthase (iNOs) expression (P < 0.05), while increased collagen-II and aggrecan levels (P < 0.05). From a mechanistic perspective, RSV inhibited the degradation of IκB-α as well as the activation of nuclear factor-kappa B (NF-κB) induced by IL-1β.

CONCLUSION

In summary, RSV regulates the signaling pathway of NF-κB, thus inhibiting inflammation and matrix degradation in chondrocytes. More studies should be focused on the treatment efficacy of RSV for OA in vivo.

Genetics in Cartilage Lesions: Basic Science and Therapy Approaches

Cartilage lesions have a multifactorial nature, and genetic factors are their strongest determinants. As biochemical and genetic studies have dramatically progressed over the past decade, the molecular basis of cartilage pathologies has become clearer. Several homeostasis abnormalities within cartilaginous tissue have been found, including various structural changes, differential gene expression patterns, as well as altered epigenetic regulation. However, the efficient treatment of cartilage pathologies represents a substantial challenge. Understanding the complex genetic background pertaining to cartilage pathologies is useful primarily in the context of seeking new pathways leading to disease progression as well as in developing new targeted therapies. A technology utilizing gene transfer to deliver therapeutic genes to the site of injury is quickly becoming an emerging approach in cartilage renewal. The goal of this work is to provide an overview of the genetic basis of chondral lesions and the different approaches of the most recent systems exploiting therapeutic gene transfer in cartilage repair. The integration of tissue engineering with viral gene vectors is a novel and active area of research. However, despite promising preclinical data, this therapeutic concept needs to be supported by the growing body of clinical trials.

Genetic Predictors of Knee Pain in Persons With Mild to Moderate Osteoarthritis

The purpose of this study was to examine genetic variability and knee pain in persons with osteoarthritis (OA). Seventy-five participants with medial compartment knee OA were recruited from a large Midwestern tertiary care center. Participants exhibited a mean age of 56.3 years; females comprised 61% of the sample. Measures of pain included subjective pain intensity at rest and with movement, cutaneous mechanical sensation and pain testing, heat pain threshold, and pressure pain threshold. Seventy-four participants were genotyped for 25 genetic variants across 15 candidate genes for central or peripheral pain pathways. Analysis suggests a role for four genes (EDNRA, COMT, BDRKB1, and IL1B) in several components of pain in persons with knee OA. The results from this study will help guide the development and evaluation of tailored strategies to decrease pain, improve function, and prevent the development of new chronic pain syndromes in older adults experiencing OA. [Research in Gerontological Nursing, xx(x), xx-xx.].

Generation and characterization of human induced pluripotent stem cells (iPSCs) from hand osteoarthritis patient-derived fibroblasts

Knowledge and research results about hand osteoarthritis (hOA) are limited due to the lack of samples and animal models of the disease. Here, we report the generation of two induced pluripotent stem cell (iPSC)-lines from patients with radiographic hOA. Furthermore, we wondered whether these iPSC-lines carried single nucleotide polymorphisms (SNPs) within genes that have been associated with hOA. Finally, we performed chondrogenic differentiation of the iPSCs in order to prove their usefulness as cellular models of the disease. We performed a non-integrative reprogramming of dermal fibroblasts obtained from two patients with radiographic rhizarthrosis and non-erosive hOA by introducing the transcriptional factors Oct4, Sox2, Klf4 and c-Myc using Sendai virus. After reprogramming, embryonic stem cell-like colonies emerged in culture, which fulfilled all the criteria to be considered iPSCs. Both iPSC-lines carried variants associated with hOA in the four studied genes and showed differences in their chondrogenic capacity when compared with a healthy control iPSC-line. To our knowledge this is the first time that the generation of iPSC-lines from patients with rhizarthrosis and non-erosive hOA is reported. The obtained iPSC-lines might enable us to model the disease in vitro, and to deeper study both the molecular and cellular mechanisms underlying hOA.

Two novel SNPs in genes involved in immune response and their association with mandibular residual ridge resorption

“Residual ridge resorption” (RRR) is a multifactorial condition involving bone resorption of the residual ridge. We investigated 10 single nucleotide polymorphisms (SNPs) in seven genes with the aim of identifying the genetic factors associated with RRR susceptibility. The study group included 96 RRR patients and 96 controls. Age at first edentulism, duration of edentulism, and bone height were recorded. Saliva was collected from the subjects for DNA extraction. Genotype analysis was performed on the ‘SequenomMassARRAYiPLEX’. The genotype and allele frequencies calculated in patients and controls were compared. We found that rs1800896 in the IL10 gene and rs5743289 in NOD2 gene showed significant association with RRR. Within the RRR group, genotypes for each SNP were separated, and we observed that the age at first edentulism and bone height showed variations in the different genotypes of the ten studied SNPs. This study showed an association between SNPs in IL10 and NOD2 genes. It also revealed that the genotypes of the different SNPs influence bone resorption and health. Additionally, age at first edentulism and bone height were much lower in some genotypes. This study demonstrates the need for larger multicenter trials to confirm these findings. Finally, we suggest that the results of this study may be utilized for developing novel genetic diagnostic tests and for identifying Saudi individuals who may be more susceptible to RRR development following dental extraction.

Interleukin 1 receptor antagonist (IL1RN) gene variants predict radiographic severity of knee osteoarthritis and risk of incident disease

OBJECTIVE

In these studies, we examined the association of single nucleotide polymorphisms (SNPs) of the IL1RN gene with radiographic severity of symptomatic knee osteoarthritis (SKOA) and the risk of incident OA. We also explored these genetic polymorphisms in patients with new onset rheumatoid arthritis (RA).

METHODS

Over 1000 subjects who met American College of Rheumatology criteria for tibiofemoral OA were selected from three independent, National Institute of Health (NIH)-funded cohorts. CTA and TTG haplotypes formed from three SNPs of the IL1RN gene (rs419598, rs315952, rs9005) were assessed for association with radiographic severity, and risk for incident radiographic OA (rOA) in a nested case-control cohort. These IL1RN haplotypes were also assessed for association with disease activity (DAS28) and plasma inflammatory markers in patients with RA.

RESULTS

Carriage of the IL1RN TTG haplotype was associated with increased odds of more severe rOA compared with age-matched, sex-matched and body mass index-matched individuals. Examination of the osteoarthritis initiative Incidence Subcohort demonstrated that carriage of the TTG haplotype was associated with 4.1-fold (p=0.001) increased odds of incident rOA. Plasma IL-1Ra levels were lower in TTG carriers, while chondrocytes from TTG carriers exhibited decreased secretion of IL-1Ra. In patients with RA, the TTG haplotype was associated with increased DAS28, decreased plasma IL-1Ra and elevations of plasma inflammatory markers (hsCRP, interleukin 6 (IL-6)).

CONCLUSION

Carriage of the IL1RN TTG haplotype is associated with more severe rOA, increased risk for incident OA, and increased evidence of inflammation in RA. These data suggest that the IL1RN TTG risk haplotype, associated with decreased IL-1Ra plasma levels, impairs endogenous 'anti-inflammatory' mechanisms.

Ibuprofen attenuates interleukin-1β-induced inflammation and actin reorganization via modulation of RhoA signaling in rabbit chondrocytes

Ibuprofen, a medication in the nonsteroidal anti-inflammatory drug class, is widely used for treating inflammatory diseases such as osteoarthritis. It has been shown in recent years that ibuprofen has a strong effect on Ras homolog gene family, member A (RhoA) inhibition in multiple cell types. Our previous finding also demonstrated that interleukin-1β (IL-1β) increases filamentous actin (F-actin) of chondrocytes via RhoA pathway. Therefore, we hypothesized that ibuprofen may suppress the IL-1β-induced F-actin upregulation in chondrocytes by inhibiting RhoA pathway. To this end, in this study, articular chondrocytes from New Zealand White rabbits were pretreated with 500 μM ibuprofen for 2 h, then with 10 ng/ml IL-1β for 24 h. Results showed that pretreatment with ibuprofen inhibited the IL-1β-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production, protected the chondrocyte phenotype from IL-1β stimulation, and inhibited the IL-1β-induced actin remodeling via RhoA signaling modulation. In conclusion, ibuprofen showed not only anti-inflammatory function, but also RhoA inhibition in articular chondrocytes.

Inhibiting the PI3K/AKT/NF-κB signal pathway with nobiletin for attenuating the development of osteoarthritis: in vitro and in vivo studies

Osteoarthritis (OA), an age-related degenerative disease, is characterized by progressive degradation of the articular cartilage. There is increasing evidence that nobiletin (NOB) exerts special biological functions in a variety of diseases. However, whether it protects against OA remains unknown. In this study, we investigated the anti-inflammatory and chondroprotective effects of NOB on IL-1β-induced human OA chondrocytes and in the surgical DMM mice OA models. In vitro, NOB treatment completely suppressed the overproduction of pro-inflammatory mediators, including PGE2, NO, COX-2, iNOS, TNF-α and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, NOB exerted a potent inhibitory effect on the expression of MMP-13 and ADAMTS-5 as well as the degradation of aggrecan and collagen-II, which leads to the degradation of the extracellular matrix. Furthermore, NOB dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with NOB not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. In conclusion, our study suggests that NOB holds novel therapeutic potential for the treatment of OA.

Curcumin reduces inflammation in knee osteoarthritis rats through blocking TLR4 /MyD88/NF-κB signal pathway

Preclinical Research & Development Curcumin has been shown to possess a series of beneficial effects, such as antiinflammatory, antioxidant, analgesic, and promoting healing. However, the effect and relative mechanism of curcumin on knee osteoarthritis (OA) have not been elucidated. The aim of this study is to explore the protective effect of curcumin on monosodium iodoacetate (MIA)-induced OA. Forty-eight rats were randomized into four experimental groups: control group, OA group, OA + PBS group, and OA + curcumin group, respectively. A single intraarticular injection of MIA was applied to establish the rat model of knee OA. Hematoxylin-eosin staining was used to evaluate histological changes of knee joint. The paw withdrawal threshold was collected and the expression of synovial fluid cytokine levels was measured by ELISA. The protein expression of TRL-4, MyD88, p-IκBα, NF-κB, TNF-α, IL-1β, and IL6 was measured by western blot. Treating with curcumin can significantly reduce joint diameter and Mankin's score, and increase the paw withdrawal threshold. The expression of synovial fluid inflammatory biomarkers, IL-6, IL-1β, and TNF-α in the OA + curcumin group were lower than that in OA and OA + PBS group. The protein expression of the TLR4 receptor was increased in the OA, OA + PBS, and OA + curcumin group compared to the control group. However, curcumin treatment can significantly decrease the expression of MyD88, p-IκBα, NF-κB, TNF-α, IL-1β, and IL6 in OA + curcumin group. These findings may indicate that curcumin could block TLR4/NF-κB signal pathway, and reduce inflammation level to prevent knee wound in OA rats. Curcumin may be a feasible kind of medicament in the treatment of knee OA.

Phase IIa, placebo-controlled, randomised study of lutikizumab, an anti-interleukin-1α and anti-interleukin-1β dual variable domain immunoglobulin, in patients with erosive hand osteoarthritis

OBJECTIVE

To assess the efficacy, safety, pharmacokinetics and pharmacodynamics of the anti-interleukin (IL)-1α/β dual variable domain immunoglobulin lutikizumab (ABT-981) in erosive hand osteoarthritis (HOA).

METHODS

Patients with ≥1 erosive and ≥3 tender and/or swollen hand joints were randomised to placebo or lutikizumab 200 mg subcutaneously every 2 weeks for 24 weeks. The primary endpoint was change in Australian/Canadian Osteoarthritis Hand Index (AUSCAN) pain subdomain score from baseline to 16 weeks. At baseline and week 26, subjects had bilateral hand radiographs and MRI of the hand with the greatest number of baseline tender and/or swollen joints. Continuous endpoints were assessed using analysis of covariance models, with treatment and country as main factors and baseline measurements as covariates.

RESULTS

Of 132 randomised subjects, 1 received no study drug and 110 completed the study (placebo, 61/67 (91%); lutikizumab, 49/64 (77%)). AUSCAN pain was not different among subjects treated with lutikizumab versus placebo at week 16 (least squares mean difference, 1.5 (95% CI -1.9 to 5.0)). Other clinical and imaging endpoints were not different between lutikizumab and placebo. Lutikizumab significantly decreased serum high-sensitivity C reactive protein levels, IL-1α and IL-1β levels, and blood neutrophils. Lutikizumab pharmacokinetics were consistent with phase I studies and not affected by antidrug antibodies. Injection site reactions and neutropaenia were more common in the lutikizumab group; discontinuations because of adverse events occurred more frequently with lutikizumab (4/64) versus placebo (1/67).

CONCLUSION

Despite adequate blockade of IL-1, lutikizumab did not improve pain or imaging outcomes in erosive HOA compared with placebo.

Inflammation-Accelerated Senescence and the Cardiovascular System: Mechanisms and Perspectives. Int J Mol Sci. 2018;19. [PMID: 30469478 PMCID: PMC6321367 DOI: 10.3390/ijms19123701]

Low-grade chronic inflammation is a common denominator in atherogenesis and related diseases. Solid evidence supports the occurrence of an impairment in the innate and adaptive immune system with senescence, favoring the development of acute and chronic age-related diseases. Cardiovascular (CV) diseases (CVD), in particular, are a leading cause of death even at older ages. Inflammation-associated mechanisms that contribute to CVD development include dysregulated redox and metabolic pathways, genetic modifications, and infections/dysbiosis. In this review, we will recapitulate the determinants and consequences of the immune system dysfunction at older age, with particular focus on the CV system. We will examine the currently available and potential future strategies to counteract accelerated CV aging, i.e., nutraceuticals, probiotics, caloric restriction, physical activity, smoking and alcohol cessation, control of low-grade inflammation sources, senolytic and senescence-modulating drugs, and DNA-targeting drugs.

Leonurine inhibits IL-1β induced inflammation in murine chondrocytes and ameliorates murine osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage degradation, subchondral bone sclerosis and synovitis. Leonurine, an active component extracted from the leaves of Herba leonuri, has been reported to possess various potent biological effects such as anti-oxidant, anti-apoptosis, and anti-inflammatory. However, the therapeutic benefits of leonurine on OA have not been reported. This study aimed to evaluate the therapeutic effect of leonurine on chondrocytes and in murine OA models. Murine chondrocytes were pre-treated with leonurine (5, 10, and 20 μM) for 2 h and then stimulated with IL-1β for 24 h. Production of NO, PGE2, IL-6, TNF-α, MMP-3, MMP-13, and ADAMTS-5 was assessed with the Griess reagent and ELISAs. The mRNA expression of COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5, aggrecan, and collagen-II was tested with real-time polymerase chain reaction. The protein expression of iNOS, COX-2 and NF-κB-related signaling molecules was measured with western blotting. In this study, leonurine visibly inhibited the IL-1β-induced production of NO, PGE2, IL-6 and TNF-α; and decreased the expression of iNOS, COX-2, MMP-3, MMP-13 and ADAMTS-5 in chondrocytes. Furthermore, leonurine significantly suppressed IL-1β-stimulated NF-κB activation. In addition, treatment with leonurine not only prevented cartilage destruction and subchondral bone thickening, but also alleviated synovitis in a murine OA model. Taken together, these results suggest that leonurine may be a potential therapeutic agent in OA treatment.

Novel protein therapeutic joint retention strategy based on collagen-binding Avimers

Designing drugs to treat diseases associated with articular joints, particularly those targeting chondrocytes, is challenging due to unique local environmental constraints including the avascular nature of cartilage, the absence of a closed joint compartment, and a highly cross-linked extracellular matrix. In an effort to address these challenges, we developed a novel strategy to prolong residence time of intra-articularly administered protein therapeutics. Avimer domains are naturally found in membrane polypeptides and mediate diverse protein-protein interactions. Screening of a phage Avimer domain library led to identification of several low affinity type II collagen-binding Avimers. Following several rounds of mutagenesis and reselection, these initial hits were transformed to high affinity, selective type II collagen-binding Avimers. One such Avimer (M26) persisted in rat knees for at least 1 month following intra-articular administration. Fusion of this Avimer to a candidate therapeutic payload, IL-1Ra, yielded a protein construct which simultaneously bound to type II collagen and to IL-1 receptor. In vitro, IL-1Ra_M26 bound selectively to cartilage explants and remained associated even after extensive washing. Binding appeared to occur preferentially to pericellular regions surrounding chondrocytes. An acute intra-articular IL-1-induced IL-6 challenge rat model was employed to assess in vivo pharmacodynamics. Whereas both IL-1Ra_M26 and native IL-1Ra inhibited IL-6 output when co-administered with the IL-1 challenge, only IL-1Ra_M26 inhibited when administered 1 week prior to IL-1 challenge. Collagen-binding Avimers thus represent a promising strategy for enhancing cartilage residence time of protein therapeutics. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1238-1247, 2018.

Downregulating PI3K/Akt/NF-κB signaling with allicin for ameliorating the progression of osteoarthritis:in vitroandvivostudies

A schematic illustration of the potential protective effects of allicin on osteoarthritis development.

Gout and risk of knee replacement for severe knee osteoarthritis in the Singapore Chinese Health Study

OBJECTIVE

While cross-sectional and retrospective case-control studies suggest that gout is associated with knee osteoarthritis (KOA), no prospective study has evaluated the risk of total knee replacement (TKR) for KOA in association with gout. We prospectively evaluated the association between gout and the risk of TKR due to severe KOA.

DESIGN

We used data from the Singapore Chinese Health Study (SCHS), a prospective cohort with 63,257 Chinese adults aged 45-74 years at recruitment (1993-1998). Self-report of physician-diagnosed gout was enquired at follow-up I interview (1999-2004) from 52,322 subjects. TKR cases for KOA after follow-up I were identified via linkage with nationwide hospital discharge database through 31 December 2011. Multivariable Cox proportional hazards regression model was applied with adjustment for potential risk factors of KOA.

RESULTS

Among 51,858 subjects (22,180 men and 29,678 women) included in this analysis, after average 9.7 follow-up years, there were 1,435 cases of TKR. Gout was associated with 39% higher risk of TKR in women [hazard ratio (HR) 1.39; 95% confidence interval (CI) 1.08-1.79] but not in men (HR 0.78; 95% CI 0.49-1.23). The positive gout-TKR association in women remained after excluding participants with self-reported history of arthritis (HR 1.57; 95% CI 1.04-2.37). This association was stronger in women who were lean (body mass index [BMI] < 23 kg/m²) (HR 2.17; 95% CI 1.30-3.64) compared to their heavier counterparts (P_interaction = 0.016).

CONCLUSION

Gout is associated with risk of severe KOA, especially in lean women, suggesting the crystal arthritis may play a role in the pathogenesis or progression of OA.

Genome-wide association and functional studies identify a role for matrix Gla protein in osteoarthritis of the hand

OBJECTIVE

Osteoarthritis (OA) is the most common form of arthritis and the leading cause of disability in the elderly. Of all the joints, genetic predisposition is strongest for OA of the hand; however, only few genetic risk loci for hand OA have been identified. Our aim was to identify novel genes associated with hand OA and examine the underlying mechanism.

METHODS

We performed a genome-wide association study of a quantitative measure of hand OA in 12 784 individuals (discovery: 8743, replication: 4011). Genome-wide significant signals were followed up by analysing gene and allele-specific expression in a RNA sequencing dataset (n=96) of human articular cartilage.

RESULTS

We found two significantly associated loci in the discovery set: at chr12 (p=3.5 × 10-10) near the matrix Gla protein (MGP) gene and at chr12 (p=6.1×10-9) near the CCDC91 gene. The DNA variant near the MGP gene was validated in three additional studies, which resulted in a highly significant association between the MGP variant and hand OA (rs4764133, Betameta=0.83, Pmeta=1.8*10-15). This variant is high linkage disequilibrium with a coding variant in MGP, a vitamin K-dependent inhibitor of cartilage calcification. Using RNA sequencing data from human primary cartilage tissue (n=96), we observed that the MGP RNA expression of the hand OA risk allele was significantly lowercompared with the MGP RNA expression of the reference allele (40.7%, p<5*10-16).

CONCLUSIONS

Our results indicate that the association between the MGP variant and increased risk for hand OA is caused by a lower expression of MGP, which may increase the burden of hand OA by decreased inhibition of cartilage calcification.

A Brief History of IL-1 and IL-1 Ra in Rheumatology

The history of what, in 1979, was called interleukin-1 (IL-1), orchestrator of leukocyte inter-communication, began many years before then, initially by the observation of fever induction via the endogenous pyrogen (EP) (1974) and then in rheumatology on the role in tissue destruction in rheumatoid diseases via the induction of collagenase and PGE₂ in human synovial cells by a mononuclear cell factor (MCF) (1977). Since then, the family has exploded to presently 11 members as well as many membrane-bound and soluble receptor forms. The discovery of a natural Interleukin-1 receptor antagonist (IL-1Ra) in human biological fluids has highlighted the importance of IL-1 and IL-1Ra in human diseases. Evidence delineating its role in autoinflammatory syndromes and the elucidation of the macromolecular complex referred to as "inflammasome" have been instrumental to our understanding of the link with IL-1. At present, the IL-1blockade as therapeutic approach is crucial for many hereditary autoinflammatory diseases, as well as for adult-onset Still's disease, crystal-induced arthropathies, certain skin diseases including neutrophil-triggered skin diseases, Behçet's disease and deficiency of IL-1Ra and other rare fever syndromes. Its role is only marginally important in rheumatoid arthritis and is still under debate with regard to osteoarthritis, type 2 diabetes mellitus, cardiovascular diseases and cancer. This brief historical review focuses on some aspects of IL-1, mainly IL-1β and IL-Ra, in rheumatology. There are many excellent reviews focusing on the IL-1 family in general or with regard to specific diseases or biological discoveries.

Association of genetic polymorphisms of IL1β -511 C>T, IL1RN VNTR 86 bp, IL6 -174 G>C, IL10 -819 C>T and TNFα -308 G>A, involved in symptomatic patients with dengue in Brazil

OBJECTIVE

In this study, single nucleotide polymorphisms (SNP) of interleukin (IL) 1β -511C>T, IL1RN VNTR 86 bp, IL6 -174G>C, IL10 -819C>T and TNFα -308G>A were analyzed by PCR-RFLP with symptoms of dengue with the clinical features.

SUBJECTS

196 individuals admitted to the São José Infectious Diseases Hospital with suspected dengue infection. Dengue was confirmed in 111 of the patients. The control group consisted of 85 other individuals confirmed without dengue.

RESULTS

It was demonstrated that the presence the T allele of IL1β (P < 0.05) was associated with susceptibility to developing the disease. Other results also suggested that the polymorphism in the combinations IL6 × IL1β (C and T alleles, respectively), IL1β (T allele) × IL1RN (*2/*2 genotype), IL6 (C allele) × TNFα (A allele), IL10 (C/T genotype) × TNFα (A/A genotype) (P < 0.01, P = 0.01, P < 0.05 and P = 0.03, respectively) were associated with predisposition to developing the disease and its symptoms.

CONCLUSIONS

In summary, the findings of this study in a Brazilian population point out the importance of studies of combinations of polymorphisms in the development of dengue, which can increase the risk of dengue infection and its severity.

Vitamin E slows down the progression of osteoarthritis

Osteoarthritis is a chronic degenerative joint disorder with the characteristics of articular cartilage destruction, subchondral bone alterations and synovitis. Clinical signs and symptoms of osteoarthritis include pain, stiffness, restricted motion and crepitus. It is the major cause of joint dysfunction in developed nations and has enormous social and economic consequences. Current treatments focus on symptomatic relief, however, they lack efficacy in controlling the progression of this disease, which is a leading cause of disability. Vitamin E is safe to use and may delay the progression of osteoarthritis by acting on several aspects of the disease. In this review, how vitamin E may promote the maintenance of skeletal muscle and the regulation of nucleic acid metabolism to delay osteoarthritis progression is explored. In addition, how vitamin E may maintain the function of sex organs and the stability of mast cells, thus conferring a greater resistance to the underlying disease process is also discussed. Finally, the protective effect of vitamin E on the subchondral vascular system, which decreases the reactive remodeling in osteoarthritis, is reviewed.

The IL-1β/AP-1/miR-30a/ADAMTS-5 axis regulates cartilage matrix degradation in human osteoarthritis

The proinflammatory cytokine interleukin-1β (IL-1β) is involved in the initiation and progression of osteoarthritis (OA) by stimulating the expression of matrix-degrading proteinases, such as a disintegrin metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), a key player in OA pathogenesis. However, how IL-1β induces ADAMTS-5 overexpression is poorly understood. We demonstrate that IL-1β regulates ADAMTS-5 expression by suppressing microRNA-30a (miR-30a). Bioinformatics was performed to predict miRNAs targeting ADAMTS-5. miR-30a inhibited ADAMTS-5 expression by directly targeting its 3'-untranslated region. miR-30a expression was downregulated in OA patients and was negatively correlated with ADAMTS-5 expression and positively correlated with Hospital for Special Surgery (HSS) scores. IL-1β suppressed miR-30a expression by recruiting the activator protein (AP-1) transcription factor c-jun/c-fos to the miR-30a promoter. IL-1β-induced c-jun/c-fos expression regulated ADAMTS-5 expression and cartilage matrix degradation via miR-30a in human chondrocytes. These data indicate that the IL-1β/AP-1/miR-30a/ADAMTS-5 pathway contributes to IL-1β-induced cartilage matrix degradation in human OA chondrocytes. miR-30a may act as a pivotal regulator of cartilage homeostasis and a potential diagnostic and therapeutic target for OA.

KEY MESSAGES

ADAMTS-5 was identified as a novel direct target of miR-30a. IL-1β suppresses miR-30a expression through activation of AP-1 (c-jun/c-fos). AP-1/miR-30a is essential for IL-1β-induced ADAMTS-5 upregulation in OA. Downregulation of miR-30a in OA is negatively correlated with ADAMTS-5 expression.

Presence of gout is associated with increased prevalence and severity of knee osteoarthritis among older men: results of a pilot study

BACKGROUND

Gout and osteoarthritis (OA) are the most prevalent arthritides, but their relationship is neither well established nor well understood.

OBJECTIVES

We assessed whether a diagnosis of gout or asymptomatic hyperuricemia (AH) is associated with increased prevalence/severity of knee OA.

METHODS

One hundred nineteen male patients aged 55 to 85 years were sequentially enrolled from the primary care clinics of an urban Veterans Affairs hospital, assessed and categorized into 3 groups: gout (American College of Rheumatology Classification Criteria), AH (serum urate ≥6.8 mg/dL, no gout), and control (serum urate <6.8 mg/dL, no gout). Twenty-five patients from each group subsequently underwent formal assessment of knee OA presence and severity (American College of Rheumatology Clinical/Radiographic Criteria, Kellgren-Lawrence grade). Musculoskeletal ultrasound was used to detect monosodium urate deposition at the knees and first metatarsophalangeal joints.

RESULTS

The study showed 68.0% of gout, 52.0% of AH, and 28.0% of age-matched control subjects had knee OA (gout vs control, P = 0.017). Odds ratio for knee OA in gout versus control subjects was 5.46 prior to and 3.80 after adjusting for body mass index. Gout subjects also had higher Kellgren-Lawrence grades than did the control subjects (P = 0.001). Subjects with sonographically detected monosodium urate crystal deposition on cartilage were more likely to have OA than those without (60.0 vs 27.5%, P = 0.037), with crystal deposition at the first metatarsophalangeal joints correlating most closely with OA knee involvement.

CONCLUSIONS

Knee OA was more prevalent in gout patients versus control subjects and intermediate in AH. Knee OA was more severe in gout patients versus control subjects.

Can We Identify Patients with High Risk of Osteoarthritis Progression Who Will Respond to Treatment? A Focus on Biomarkers and Frailty

Osteoarthritis (OA), a disease affecting different patient phenotypes, appears as an optimal candidate for personalized healthcare. The aim of the discussions of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) working group was to explore the value of markers of different sources in defining different phenotypes of patients with OA. The ESCEO organized a series of meetings to explore the possibility of identifying patients who would most benefit from treatment for OA, on the basis of recent data and expert opinion. In the first meeting, patient phenotypes were identified according to the number of affected joints, biomechanical factors, and the presence of lesions in the subchondral bone. In the second meeting, summarized in the present article, the working group explored other markers involved in OA. Profiles of patients may be defined according to their level of pain, functional limitation, and presence of coexistent chronic conditions including frailty status. A considerable amount of data suggests that magnetic resonance imaging may also assist in delineating different phenotypes of patients with OA. Among multiple biochemical biomarkers identified, none is sufficiently validated and recognized to identify patients who should be treated. Considerable efforts are also being made to identify genetic and epigenetic factors involved in OA, but results are still limited. The many potential biomarkers that could be used as potential stratifiers are promising, but more research is needed to characterize and qualify the existing biomarkers and to identify new candidates.

The role of cyclooxygenase-2, interleukin-1β and fibroblast growth factor-2 in the activation of matrix metalloproteinase-1 in sheared-chondrocytes and articular cartilage

MMP-1 expression is detected in fluid shear stress (20 dyn/cm²)-activated and osteoarthritic human chondrocytes, however, the precise mechanisms underlying shear-induced MMP-1 synthesis remain unknown. Using primary chondrocytes and T/C-28a2 chondrocytic cells as model systems, we report that prolonged application of high fluid shear to human chondrocytes induced the synthesis of cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β) and fibroblast growth factor-2 (FGF-2), which led to a marked increase in MMP-1 expression. IL-1β, COX-2-dependent PGE₂ activated the PI3-K/AKT and p38 signaling pathways, which were in turn responsible for MMP-1 synthesis via NF-κB- and c-Jun-transactivating pathways. Prolonged shear stress exposure (>12 h) induced 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) synthesis. Although 15d-PGJ₂ suppressed PI3-K/AKT and p38 signaling pathways, it stimulated MMP-1 expression via activating heme oxygenase 1 (HO-1). The critical role of COX-2 in regulating MMP-1 expression in articular cartilage in vivo was demonstrated using COX-2^+/− transgenic mice in the absence or presence of rofecoxib oral administration. These findings provide novel insights for developing therapeutic strategies to combat OA.

Role of IL-38 and its related cytokines in inflammation

Interleukin- (IL-) 38 is a recently discovered cytokine and is the tenth member of the IL-1 cytokine family. IL-38 shares structural features with IL-1 receptor antagonist (IL-1Ra) and IL-36Ra. IL-36R is the specific receptor of IL-38, a partial receptor antagonist of IL-36. IL-38 inhibits the production of T-cell cytokines IL-17 and IL-22. IL-38 also inhibits the production of IL-8 induced by IL-36γ, thus inhibiting inflammatory responses. IL-38-related cytokines, including IL-1Ra and IL-36Ra, are involved in the regulation of inflammation and immune responses. The study of IL-38 and IL-38-related cytokines might provide new insights for developing anti-inflammatory treatments in the near future.

Improved prediction of knee osteoarthritis progression by genetic polymorphisms: the Arthrotest Study

OBJECTIVE

The aim of this study was to develop a genetic prognostic tool to predict radiographic progression towards severe disease in primary knee OA (KOA) patients.

METHODS

This investigation was a cross-sectional, retrospective, multicentric association study in 595 Spanish KOA patients. Caucasian patients aged ≥40 years at the time of diagnosis of primary KOA of Kellgren-Lawrence grade 2 or 3 were included. Patients who progressed to Kellgren-Lawrence score 4 or who were referred for total knee replacement within 8 years after diagnosis were classified as progressors to severe disease. Clinical variables of the initial stages of the disease (gender, BMI, age at diagnosis, OA in the contralateral knee, and OA in other joints) were registered as potential predictors. Single nucleotide polymorphisms and clinical variables with an association of P < 0.05 were included in the multivariate analysis using forward logistic regression.

RESULTS

A total of 23 single nucleotide polymorphisms and the time of primary KOA diagnosis were significantly associated with KOA severe progression in the exploratory cohort (n = 220; P < 0.05). The predictive accuracy of the clinical variables was limited: area under the curve (AUC) = 0.66. When genetic variables were added to the clinical model (full model), the prediction of KOA progression was significantly improved (AUC = 0.82). Combining only genetic variables (rs2073508, rs10845493, rs2206593, rs10519263, rs874692, rs7342880, rs780094 and rs12009), a predictive model with good accuracy was also obtained (AUC = 0.78). The predictive ability for KOA progression of the full model was confirmed on the replication cohort (two-sample Z-test; n = 62; P = 0.190).

CONCLUSION

An accurate prognostic tool to predict primary KOA progression has been developed based on genetic and clinical information from OA patients.

Mitochondrial DNA (mtDNA) haplogroups influence the progression of knee osteoarthritis. Data from the Osteoarthritis Initiative (OAI)

OBJECTIVE

To evaluate the influence of the mtDNA haplogroups on knee osteoarthritis progression in Osteoarthritis Initiative (OAI) participants through longitudinal data from radiographs and magnetic resonance imaging (MRI).

METHODS

Four-year knee osteoarthritis progression was analyzed as increase in Kellgren and Lawrence (KL) grade, in addition to increase in OARSI atlas grade for joint space narrowing (JSN), osteophytes and subchondral sclerosis in the tibia medial compartment of 891 Caucasian individuals from the progression subcohort. The influence of the haplogroups on the rate of structural progression was also assessed as the four-year change in minimum joint space width (mJSW in millimetres) in both knees of (n = 216) patients with baseline unilateral medial-tibiofemoral JSN. Quantitative cartilage measures from longitudinal MRI data were those related to cartilage thickness and volume with a 24 month follow-up period (n = 381).

RESULTS

During the four-year follow-up period, knee OA patients with the haplogroup T showed the lowest increase in KL grade (Hazard Risk [HR] = 0.499; 95% Confidence Interval [CI]: 0.261-0.819; p<0.05) as well as the lowest cumulative probability of progression for JSN (HR = 0.547; 95% CI: 0.280-0.900; p<0.05), osteophytes (HR = 0.573; 95% CI: 0.304-0.893; p<0.05) and subchondral sclerosis (HR = 0.549; 95% CI: 0.295-0.884; p<0.05). They also showed the lowest decline in mJSW (standardized response means (SRM) = -0.39; p = 0.037) in those knees without baseline medial JSN (no-JSN knees). Normalized cartilage volume loss was significantly lower in patients carrying the haplogroup T at medial tibia femoral (SRM = -0.33; p = 0.023) and central medial femoral (SRM = -0.27; p = 0.031) compartments. Cartilage thickness loss was significantly lower in carriers of haplogroup T at central medial tibia-femoral (SRM = -0.42; p = 0.011), medial tibia femoral (SRM = -0.32; p = 0.018), medial tibia anterior (SRM = +0.31; p = 0.013) and central medial femoral (SRM = -0.19; p = 0.013) compartments.

CONCLUSIONS

Mitochondrial genome seems to play a role in the progression of knee osteoarthritis. mtDNA variation could improve identification of patients predisposed to faster or severe progression of the disease.

Calcitonin treatment is associated with less severe osteoarthritis and reduced toll-like receptor levels in a rat model

BACKGROUND

Studies indicate that inflammation promotes progression of osteoarthritis. Cartilage damage is aggravated by the binding of toll-like receptors and endogenous ligands that release large amounts of cytokines and inflammation mediators. Calcitonin can inhibit degeneration of articular cartilage, by inhibiting activation of toll-like receptors and generation of endogenous ligands. To study the effect of calcitonin in the pathogenesis of osteoarthritis and the underlying molecular mechanism, we monitored levels of toll-like receptors during osteoarthritis progression, and after calcitonin injection.

METHODS

Male Sprague-Dawley rats were randomly assigned to either a surgery-only or a calcitonin-treatment group (n = 35, each). To induce osteoarthritis, the anterior cruciate ligament and the medial meniscus were cut in the right knees of both groups. Rats in the calcitonin-treatment group received a subcutaneous injection of 15 IU/kg calcitonin once every other day, starting one day post-surgery, until euthanised. Signs of osteoarthritic changes were noted. The amount of collagen II was measured by antibody staining. The amounts of MMP1 and MMP3 in cartilage were measured by use of ELISA. RNA from operated and matched control knee cartilage was extracted to determine expression levels of Col2a1, ACAN, Tlr2, Tlr3, and Tlr4.

RESULTS

Signs of osteoarthritis were less severe in rats treated with calcitonin. In the surgery-only group, Tlr2 levels increased early after surgery and then decreased substantially by the latter stages. Tlr3 levels gradually increased and correlated with the severity of osteoarthritis. Tlr4 levels were high but fluctuated over the experimental period. Calcitonin treatment was associated with lower Tlr3 and Tlr4 levels than in the surgery-only group whereas Tlr2 expression was initially lower but increased 28 days after administration of calcitonin.

CONCLUSION

Calcitonin treatment may lessen the severity of osteoarthritis in the rat model, perhaps by inhibition of Tlr expression in cartilage.

Mitochondrial DNA haplogroups modulate the radiographic progression of Spanish patients with osteoarthritis

Not all patients with osteoarthritis (OA) show the same disease progression, as some of them remain relatively stable over time, while others progress to severe structural deterioration of the joint. In this sense, the main goal of both genetic and protein biomarkers in OA is to predict not only the risk of OA at an earlier stage of the disease but also which OA patients are more likely to progress to severe disease. Taking into account the incidence of the mitochondria and the mtDNA haplogroups in the pathogenesis of OA, the main objective of this work was to evaluate the incidence of the mtDNA haplogroups in the radiographic progression of the OA disease in a well-characterized follow-up cohort of Spanish patients. DNA from 281 OA patients from Hospital Universitario A Coruña was isolated to determine the European mtDNA haplogroups. Knee or hip radiographs from all affected joints were obtained at two time points with at least 36 months apart. Radiographs were evaluated using the Kellgren/Lawrence (K/L) scale; radiographic OA progression was defined as any radiographic worsening of the K/L joint score. Statistical analyses included Kaplan-Meier survival curves and Cox regression models. Patients belonging to the cluster TJ showed a slower radiographic OA progression than patients in the cluster KU (p = 0.036). Moreover, patients carrying the most common mtDNA haplogroup H are more apt to require total joint replacement surgery than non-H patients (p = 0.049). The inherited mitochondrial variants influence the radiographic progression of OA and could be considered among the genetic variants taken into account when the radiographic progression of OA is analyzed.

Genetic epidemiology of osteoarthritis: recent developments and future directions

PURPOSE OF REVIEW

Despite the high prevalence of osteoarthritis and its enormous public health impact, the cause of the disease remains largely obscure. The identification of genes associated with osteoarthritis can help reveal underlying biological mechanisms that may lead to development of new therapeutic targets or biomarkers for early detection and risk stratification. The goal of this short review is to provide a brief overview of the current status of genetics of osteoarthritis with an emphasis on developments generated in the last year.

RECENT FINDINGS

This review focuses on the following areas: identification of new genes through genetic association studies, including genome-wide association studies; family-based studies and extreme osteoarthritis phenotypes; endophenotypes and pain; and overlap of osteoarthritis with other age-related disorders.

SUMMARY

Although recent genetic discoveries have produced innovative findings with respect to the pathophysiology of osteoarthritis, we have yet to realize new treatments to improve the quality of life of patients with osteoarthritis.

Genomics of pain in osteoarthritis

Osteoarthritis (OA) accounts for the majority of the disease burden for musculoskeletal disorders and is one of the leading causes of disability worldwide. This disability is the result not of the cartilage loss that defines OA radiographically, but of the chronic pain whose presence defines symptomatic OA. It is becoming clear that many genes, each with a small effect size, contribute to the risk of developing OA. However, the genetics of OA pain are only just starting to be explored. This review will describe the first genes to have been identified in genomic studies of OA pain, as well as the possible dual roles of genes previously identified in genomic studies of OA in the context of pain. Difficulties associated with attempting to characterise the genetics of OA pain will be discussed and promising future avenues of research into genetic and epigenetic factors affecting OA pain described.

IL-1 receptor antagonist gene as a predictive biomarker of progression of knee osteoarthritis in a population cohort

OBJECTIVE

Within the interleukin-1 (IL-1) cytokine family, IL-1 receptor antagonist (IL1RN) gene variants have been associated with radiological severity of knee osteoarthritis (OA) in cross-sectional studies. The present study tested the relation between IL1RN gene variants and progression of knee OA assessed radiographically by change in Kellgren-Lawrence (KL) score over time.

DESIGN

1153 Caucasian adults (age range: 44-89) from the Johnson County Osteoarthritis Project were evaluated for unequivocal radiographic evidence of knee OA at baseline, defined as KL score ≥2, and were re-examined after 4-11 years for radiographic changes typical of OA progression. IL1RN gene variants were tested for association with OA progression and for potential interaction with body mass index (BMI). Other IL-1 gene variations were tested for association with OA progression as a secondary objective.

RESULTS

Of 154 subjects with OA at baseline, 88 showed progression at follow-up. Seven IL1RN single nucleotide polymorphisms (SNPs) and one IL-1 receptor SNP were associated with progression. Four IL1RN haplotypes, each occurring in >5% of this population, showed different relationships with progression, including one (rs315931/rs4251961/rs2637988/rs3181052/rs1794066/rs419598/rs380092/rs579543/rs315952/rs9005/rs315943/rs1374281; ACAGATACTGCC) associated with increased progression [odds ratio (OR) 1.91 (95%CI 1.16-3.15); P = 0.012]. Haplotypes associated with progression by KL score were also associated with categorical change in joint space narrowing. BMI was associated with OA progression in subjects carrying a specific IL1RN haplotype, but not in subjects without that haplotype.

CONCLUSION

A significantly greater likelihood of radiological progression of knee OA was associated with a commonly occurring IL1RN haplotype that could be tagged by three IL1RN SNPs (rs419598, rs9005, rs315943). Interactions were also observed between IL1RN gene variants and BMI relative to OA progression. This suggests that IL1RN gene markers may be useful in stratifying patients for medical management and drug development.

Assessment of interleukin-1 gene cluster polymorphisms in lone atrial fibrillation: new insight into the role of inflammation in atrial fibrillation

BACKGROUND

Systemic inflammation is accepted as one of the pathophysiological mechanisms of atrial fibrillation (AF). The role of inflammation has been shown previously. Interleukin (IL) system is the main modulator of the inflammatory responses and genetic polymorphisms of IL-1 cluster genes are associated with increased risk for inflammatory diseases.

OBJECTIVES

To investigate the association between polymorphisms of IL-1 cluster genes and lone AF.

SUBJECTS AND METHODS

DNA samples were collected from 70 proven lone AF patients and 70 healthy subjects. Genomic DNA was typed for the variable number of the tandem repeat (VNTR) IL-1 receptor antagonist (RN) gene polymorphism, IL-1B -511 C > T(rs16944) promoter polymorphism, and +3953 C > T(rs1143634) polymorphism in exon 5 by polymerase chain reaction.

RESULTS

In lone AF group the frequency of IL-1RN2/2 and IL-1RN1/2 genotypes were higher than in the control group (7.2% vs 4.3% and 48.5% vs 22.8%, respectively; χ(2) = 14.1; P = 0.028). The frequency of allele 2 was significantly higher in the lone AF group (32.1% vs 15.7%; χ(2) = 10.7; P = 0.005). Allele and genotype distribution of IL-1B -511 C > T and +3953 C > T polymorphisms were not statistically different between the groups. C-reactive protein (CRP) levels were higher in lone AF patients compared to the control group (median = 1.25, interquartile range [IQR] = 0.85 vs median = 1.08, IQR 0.46 mg/L, respectively; P = 0.02). In multivariate regression analysis, presence of allele 2 of IL-1 VNTR polymorphism and elevated plasma high-sensitive-CRP levels were the independent predictors of lone AF.

CONCLUSION

Presence of allele 2 of VNTR polymorphism of IL-1RN gene may cause increased risk for lone AF probably due to the inadequate limitation of inflammatory reactions.