Research progression in the pathogenesis of osteoarthritis / 中国骨伤

Osteoarthritis(OA) is one of the most common joint diseases. As Chinese society enters the age of aging, the incidence of OA has been soar year by year, and research on its pathogenesis has been continuously valued by researchers. Studies have found that inflammatory cytokines, mainly interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), were responsible for the construction of OA inflammatory networks. It was also found that the overexpression of proteases, mainly matrix metalloproteinases(MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), was the direct cause of OA cartilage deficiency. What's more, signaling pathways such as stromal cell derived factor-1 (SDF-1) and Wnt, chondrocytic senescence and the senescence-associated secretory phenotype (SASP), chondrocyte apoptosis and autophagy, and estrogen all play significant roles in OA pathogenesis. This paper extensively reviews the research literature relevant to the pathogenesis of OA in recent years, and systematically expounds the pathogenesis of OA from two aspects:molecular level and cell level. At the end of the paper, we discussed and predicted some potential directions in the future clinical diagnosis and treatment of OA.

LncRNA SNHG7/miR-34a-5p/SYVN1 axis plays a vital role in proliferation, apoptosis and autophagy in osteoarthritis

BACKGROUND: Osteoarthritis (OA) is one of the most common rheumatic diseases of which clinical symptoms includes swelling, synovitis and inflammatory pain, affect patients' daily life. It was reported that non-coding RNAs play vital roles in OA. However, the regulation mechanism of ncRNA in OA pathogenesis has not been fully elucidated. METHODS: The expression of SNHG7, miR-34a-5p and SYVN1 was detected using qRT-PCR in tissues, serum and cells. The protein expression of SYVN1, PCNA, cleavage-caspase 3, beclinl and LC3 were measured using western blot. The RNA immunoprecipitation (RIP), RNA pulldown, and luciferase reporter assays were used to verify the relationship between SNHG7, miR-34a-5p and SYVN1. The MTT and flow cytometry assay was performed to detected cell proliferation and cell apoptosis respectively. RESULTS: In this study, SNHG7 and SYVN1 expression were down-regulated, but miR-34a-5p was up-regulated in OA tissues and IL-1P treated cells compared with normal tissues and chondrocyte. Functional investigation revealed that up-regulated SNHG7 or down-regulated miR-34a-5p could promote cell proliferation and inhibit cell apoptosis and autophagy in OA cells. More than that, RIP, pulldown and luciferase reporter assay was applied to determine that miR-34a-5p was a target miRNA of SNHG7 and SYVN1 was a target mRNA of miR-34-5p. Rescue experiments showed that overexpression of miR-34a reversed high expression of SNHG7-mediated suppression of apoptosis and autophagy as well as promotion of proliferation, while its knockdown inhibited cell apoptosis and autophagy and promoted cell proliferation which could be impaired by silencing SYVN1. In addition, SNHG7 regulated SYVN1 through sponging miR-34a-5p. CONCLUSION: SNHG7 sponged miR-34a-5p to affect cell proliferation, apoptosis and autophagy through targeting SYVN1 which provides a novel sight into the pathogenesis of OA.

Research progress on long non-coding RNA (lncRNA) in osteoarthritis / 中国骨伤

Osteoarthritis(OA) is a common clinical disease. The incidence of OA increases significantly with age, and the quality of life of patients is seriously affected. In the pathogenesis of OA, cartilage degeneration is the main cause. There are many long non-coding RNA (lncRNA) specifically expressed in osteoarthritis, which is closely related to the occurrence and development of osteoarthritis. Based on the latest research from 2014 to 2019, this paper summarizes the differential expression of lncRNA in osteoarthritis, the mechanism of lncRNA regulating chondrocyte function, and the mechanism of lncRNA regulating cartilage matrix metabolism. The fact that the expression of lncRNA is altered at different stages of OA development indicates that lncRNA can be developed forlife. The biomarkers and therapeutic targets can provide reference for the prevention, treatment and research of osteoarthritis.

Association between ADAMTS14 gene polymorphism and the temporomandibular joint osteoarthritis in Chinese Han females / 北京大学学报(医学版)

OBJECTIVE@#To investigate the association between single nucleotide polymorphisms (SNP) of ADAMTS14 gene rs4747096 and osteoarthritis of the temporomandibular joint in Chinese Han females.@*METHODS@#As a case-control study, a total of 213 Chinese Han females were involved in the present study, which contained 103 temporomandibular joint osteoarthritis patients and 110 healthy people who had no symptoms or signs of temporomandibular joint osteoarthritis as control. Peripheral blood samples were collected from each participant. Genomic DNAs of temporomandibular joint osteoarthritis patients and healthy control were extracted from peripheral venous blood, which were stored in -80 °C refrigerator by using DNA extraction kits. The designed primers were used for polymerase chain reaction (PCR) amplification of specific DNA fragments. Genotype was determined by sequencing the PCR products. The software Chromas 2.22 was used to analyze the genotype. The genotype distributions, allele frequencies and genetic models between the patients and controls were compared. The age distribution was checked by t-test. Genotype and allele frequency were detected by Chi-square test.@*RESULTS@#In the present study, there were no significant differences between the osteoarthritis patients and healthy controls in terms of age. The genotype distribution was in accordance with Hardy-Weinberg equilibrium in the two groups. The genotype frequency of the ADAMTS14 (rs4747096) in the experimental group was 38.8% (AA), 55.4% (AG), and 5.8% (GG), respectively. The genotype frequency in the control group was 40.9% (AA), 43.6% (AG), and 15.5% (GG), respectively. The difference of genotype frequency of the ADAMTS14 (rs4747096) was significant between the experimental group and the control group (P=0.047). There was no significant difference in allele frequency between the two groups (P=0.415). AA and AG genotypes significantly increased the risk of the disease compared with GG in dominant model (OR=1.114, 95% CI: 1.015-1.223, P=0.028).@*CONCLUSION@#A significant correlationship was found between the ADAMTS14 (rs4747096) SNP and the temporomandibular joint osteoarthritis in Chinese Han females. The distribution of rs4747096 may be different between temporomandibular joint osteoarthritis and healthy population.

Crosstalk between FLS and chondrocytes is regulated by HIF-2alpha-mediated cytokines in arthritis

Rheumatoid arthritis (RA) and osteoarthritis (OA), two common types of arthritis, affect the joints mainly by targeting the synovium and cartilage. Increasing evidence indicates that a significant network connects synovitis and cartilage destruction during the progression of arthritis. We recently demonstrated that hypoxia-inducible factor (HIF)-2alpha causes RA and OA by regulating the expression of catabolic factors in fibroblast-like synoviocytes (FLS) or chondrocytes. To address the reciprocal influences of HIF-2alpha on FLS and chondrocytes, we applied an in vitro co-culture system using a transwell apparatus. When co-cultured with HIF-2alpha-overexpressing chondrocytes, FLS exhibited increased expression of matrix metalloproteinases and inflammatory mediators, similar to the effects induced by tumor-necrosis factor (TNF)-alpha treatment of FLS. Moreover, chondrocytes co-cultured with HIF-2alpha-overexpressing FLS exhibited upregulation of Mmp3 and Mmp13, which is similar to the effects induced by interleukin (IL)-6 treatment of chondrocytes. We confirmed these differential HIF-2alpha-induced effects via distinct secretory mediators using Il6-knockout cells and a TNF-alpha-blocking antibody. The FLS-co-culture-induced gene expression changes in chondrocytes were significantly abrogated by IL-6 deficiency, whereas TNF-alpha neutralization blocked the alterations in gene expression associated with co-culture of FLS with chondrocytes. Our results further suggested that the observed changes might reflect the HIF-2alpha-induced upregulation of specific receptors for TNF-alpha (in FLS) and IL-6 (in chondrocytes). This study broadens our understanding of the possible regulatory mechanisms underlying the crosstalk between the synovium and cartilage in the presence of HIF-2alpha, and may suggest potential new anti-arthritis therapies.

miR-139 modulates MCPIP1/IL-6 expression and induces apoptosis in human OA chondrocytes

IL-6 is an inflammatory cytokine and its overexpression plays an important role in osteoarthritis (OA) pathogenesis. Expression of IL-6 is regulated post-transcriptionally by MCPIP1. The 3' untranslated region (UTR) of MCPIP1 mRNA harbors a miR-139 'seed sequence', therefore we examined the post-transcriptional regulation of MCPIP1 by miR-139 and its impact on IL-6 expression in OA chondrocytes. Expression of miR-139 was found to be high in the damaged portion of the OA cartilage compared with unaffected cartilage from the same patient and was also induced by IL-1beta in OA chondrocytes. Inhibition of miR-139 decreased the expression of IL-6 mRNA by 38% and of secreted IL-6 protein by 40%. However, overexpression of miR-139 increased the expression of IL-6 mRNA by 36% and of secreted IL-6 protein by 56%. These data correlated with altered expression profile of MCPIP1 in transfected chondrocytes. Studies with a luciferase reporter construct confirmed the interactions of miR-139 with the 'seed sequence' located in the 3' UTR of MCPIP mRNA. Furthermore, miR-139 overexpression increased the catabolic gene expression but expression of anabolic markers remained unchanged. Overexpression of miR-139 also induced apoptosis in OA chondrocytes. Importantly, we also discovered that IL-6 is a potent inducer of miR-139 expression in OA chondrocytes. These findings indicate that miR-139 functions as a post-transcriptional regulator of MCPIP1 expression and enhances IL-6 expression, which further upregulates miR-139 expression in OA chondrocytes. These results support our hypothesis that miR-139-mediated downregulation of MCPIP1 promotes IL-6 expression in OA. Therefore, targeting miR-139 could be therapeutically beneficial in the management of OA.

MiR-17-5p modulates osteoblastic differentiation and cell proliferation by targeting SMAD7 in non-traumatic osteonecrosis

MicroRNAs (miRNAs) have recently been recognized to have a role in human orthopedic disorders. The objective of our study was to explore the expression profile and biological function of miRNA-17-5p (miR-17-5p), which is well known to be related to cancer cell proliferation and invasion, in osteoblastic differentiation and in cell proliferation. The expression levels of miR-17-5p in the femoral head mesenchymal stem cells of 20 patients with non-traumatic osteonecrosis (ON) and 10 patients with osteoarthritis (OA) were examined by quantitative reverse transcription-PCR (qRT-PCR). Furthermore, the interaction between miR-17-5p and SMAD7 was observed. We found that in non-traumatic ON samples the level of mature miR-17-5p was significantly lower than that of OA samples (P=0.0002). By targeting SMAD7, miR-17-5p promoted nuclear translocation of beta-catenin, enhanced expression of COL1A1 and finally facilitated the proliferation and differentiation of HMSC-bm cells. We also demonstrated that restoring expression of SMAD7 in HMSC-bm cells partially reversed the function of miR-17-5p. Together, our data suggested a theory that dysfunction of a network containing miR-17-5p, SMAD7 and beta-catenin could contribute to ON pathogenesis. The present study prompts the potential clinical value of miR-17-5p in non-traumatic ON.

Regulation of hypoxia-inducible factor-1α (HIF-1α) expression by interleukin-1β (IL-1 β), insulin-like growth factors I (IGF-I) and II (IGF-II) in human osteoarthritic chondrocytes

OBJECTIVE: Hypoxia-inducible factor 1 alpha regulates genes related to cellular survival under hypoxia. This factor is present in osteroarthritic chondrocytes, and cytokines, such as interleukin-1 beta, participate in the pathogenesis of osteoarthritis, thereby increasing the activities of proteolytic enzymes, such as matrix metalloproteinases, and accelerating cartilage destruction. We hypothesize that Hypoxia Inducible Factor-1 alpha (HIF-1α) can regulate cytokines (catabolic action) and/or growth factors (anabolic action) in osteoarthritis. The purpose of this study was to investigate the modulation of HIF-1α in human osteoarthritic chondrocytes by interleukin-1 beta (IL-1β) and insulin-like growth factors I (IGF-I) and II (IGF-II) and to determine the involvement of the phosphatidylinositol-3kinase (PI-3K) pathway in this process. METHODS: Human osteroarthritic chondrocytes were stimulated with IL-1β, IGF-I and IGF-II and LY294002, a specific inhibitor of PI-3K. Nuclear protein levels and gene expression were analyzed by western blot and quantitative reverse transcription-polymerase chain reaction analyses, respectively. RESULTS: HIF-1α expression was upregulated by IL-1β at the protein level but not at the gene level. IGF-I treatment resulted in increases in both the protein and mRNA levels of HIF-1α , whereas IGF-II had no effect on its expression. However, all of these stimuli exploited the PI-3K pathway. CONCLUSION: IL-1β upregulated the levels of HIF-1α protein post-transcriptionally, whereas IGF-I increased HIF-1α at the transcript level. In contrast, IGF-II did not affect the protein or gene expression levels of HIF-1α . Furthermore, all of the tested stimuli exploited the PI-3K pathway to some degree. Based on these findings, we are able to suggest that Hypoxia inducible Factor-1 exhibits protective activity in chondrocytes during osteoarthritis.

Inflamación en osteoartritis / Osteoarthritis inflammation

La osteoartritis es una enfermedad de alto impacto que produce importante morbilidad y discapacidad en adultos sobre 60 años. Su proceso patológico se caracteriza por degeneración del cartílago articular, asociado a inflamación secundaria, lo que produce cambios proliferativos con la formación de osteofitos y esclerosis del hueso subcondral. Actualmente existe evidencia de la importancia del proceso inflamatorio subyacente, destacando la participación de polimorfismos genéticos que fomentan el proceso inflamatorio. Asociado a esto, se ha evidenciado un cambio en el fenotipo del condrocito, el cual produce mayor cantidad de IL-1-beta y TNF-alfa, las que activan el catabolismo del cartílago. Además, se postula que la sinovial actuaría como un potenciador de la inflamación, pues los fibroblastos ahí presentes son capaces de producir diversas sustancias proinflamatorias, tales como citoquinas, prostaglandinas y óxido nítrico. Por otra parte, alteraciones mecánicas y la obesidad pueden activar al condrocito, fomentado su cambio de fenotipo, lo que aumenta la producción de citoquinas proinflamatorias que aumentan el daño cartilaginoso. Sin embargo, aún no existe claridad sobre los “gatillantes” exactos del proceso inflamatorio en OA.

Osteoarthritis (OA) is a disease of high impact that produces significant morbidity and disability in adults over 60 years. His disease process is characterized by degeneration of articular cartilage, associated with secondary inflammation that produces proliferative changes with osteophyte formation and subchondral bone sclerosis. There is evidence of the importance of the underlying inflammatory process, highlighting the involvement of genetic polymorphisms that promote the inflammatory process. Associated with this has shown a change in chondrocyte phenotype which produces more IL-1-beta and TNF-alpha, which activate the catabolism of cartilage. Furthermore, it is postulated that synovial act as an enhancer of inflammation present there as fibroblasts are capable of producing various proinflammatory substances such as cytokines, prostaglandins and nitric oxide. Moreover, mechanical alterations and obesity can activate the chondrocyte phenotype promoted the change of increasing the production of proinflammatory cytokines that promote cartilage damage. However, even there is no clarity on the exact “gatillantes” the inflammatory process in OA.

Expression of p53 protein in rheumatoid arthritis synovium. An immunohistochemical analysis

OBJECTIVES: Mutation of p53 may play a role in manifestation of rheumatoid arthritis synovium, but several studies on p53 expression in synovial tissues of rheumatoid arthritis showed conflicting results. We investigated the amount and pattern of p53 positive cells in rheumatoid arthritis synovium, in comparison with osteoarthritis synovium, by using immunohistochemistry with two other monoclonal antibodies for p53. METHODS: Synovial tissues from 9 patients with rheumatoid arthritis and 5 patients with osteoarthritis were examined for p53 expression by immunohistochemistry with 2 monoclonal antibodies for p53, DO-1 and DO-7. Histologic features of inflammation were also scored and compared with p53 expression. RESULTS: There was no significant difference between inflammatory scores in both groups. In the synovial tissues of rheumatoid arthritis patients, p53 positive cells were detected in 3 out of 9 samples(33%) and p53 expressions were restricted to inflammatory mononuclear cells, but synovial lining cells, subsynovial fibroblast-like cells and vascular endothelial cells were p53 negative. p53 expressions in osteoarthritis synovial tissues as control were observed in 2 out of 5 samples(40%) and the amount and pattern of p53 positive cells were comparable to those seen in rheumatoid arthritis synovial tissues. There was no demonstrable correlation between the synovial tissues of both groups with respect to inflammation scores and expression of p53 protein. CONCLUSION: Our findings suggest that altered p53 expression may not play a significant role in the manifestation of rheumatoid arthritis synovium. However these data need to be strengthened by increasing the number of samples and molecular biology approaches.