Genética de la artrosis

DNA methylation of bone morphogenetic protein 7 in leukocytes as a possible biomarker for hand osteoarthritis: A pilot study

Hand osteoarthritis (HOA), characterized by an earlier onset age and reduced susceptibility to mechanical stress compared with knee and hip osteoarthritis, is considered a suitable disease for identifying predictive biomarkers of osteoarthritis. In particular, DNA methylation variants, expected to contribute to HOA susceptibility, hold potential as osteoarthritis biomarkers. In this study, leukocyte DNA methylation patterns were analyzed in blood samples from patients with HOA, aiming to identify disease-specific biomarkers for osteoarthritis. Using DNA methylation microarrays, we analyzed samples from three subjects with HOA and three age- and gender-matched healthy individuals. For validation, pyrosequencing analysis was conducted using samples from 16 to 9 subjects with and without HOA, respectively. From 735,026 probes in the DNA methylation array, the Top 100 CpG sites associated with HOA, based on low adjusted P-values, including those targeting bone morphogenetic protein 7 (BMP7), SBF2-AS1, PLOD2, ICOS, and CSF1R were identified. Validation analysis revealed significantly higher methylation levels in the BMP7-related site in the HOA group compared with the control group, even after adjusting for age, gender, and body mass index (p = 0.037). In contrast, no significant difference was observed in the other selected CpG sites between the HOA and control groups. This study highlights the significantly increased frequency of methylation at the specific BMP7 site in leukocytes of patients with HOA, suggesting its potential as a biomarker for HOA. Measurement of methylation levels at the CpG sites identified in this study offers a potential approach to prevent future osteoarthritis progression, providing valuable insights into disease management.

Association study of the functional variants of the GLIS3 gene with risk of knee osteoarthritis

INTRODUCTION/OBJECTIVES

Osteoarthritis (OA) ranks the most common joint disorder and the leading cause of disability. Growing evidence has revealed that OA has a strong genetic background, except for aging and obesity. The aim of this study is to determine the associations between potential functional variants of the GLIS3 and GLIS3-AS1 gene and risk of knee OA among a Chinese population.

METHODS

In this case-control study with 810 knee OA cases and 900 healthy controls, seven selected functional SNPs of the GLIS3 and GLIS3-AS1 gene were evaluated.

RESULTS

We found minor alleles of rs10116772 (OR: 0.80, 95% CI: 0.69-0.92, P = 0.002), rs7045410 (OR: 0.74, 95% CI: 0.61-0.92, P = 0.005), and rs7032713 (OR: 0.76, 95% CI: 0.63-0.93, P = 0.006) were significantly associated with decreased risk of knee OA. Results of the dominant and recessive model, stratified analyses using Kellgren-Lawrence (KL) grading presented that the significant associations were not materially changed. Haplotype analysis indicated that haplotype CGT (OR: 0.66, 95% CI: 0.46-0.96, P = 0.031) and ATT (OR: 0.76, 95% CI: 0.6-0.95, P = 0.017) were significantly associated with decreased risk of knee OA. Further, they were also significantly associated with lower expression level of GLIS3, as well as higher expression level of GLIS3-AS1 in the articular cartilage specimens. Genotype-tissue expression (GTEX) data also validated that minor alleles of rs7045410 and rs7032713 were significantly associated with higher expression level of GLIS3-AS1 in thyroid and pituitary tissues (P < 0.001).

CONCLUSIONS

These findings revealed the essential role of genetic variants of the GLIS3 and GLIS3-AS1 gene in the occurrence of knee OA together. Key Point • Functional variants of the GLIS3 and GLIS3-AS1 gene were significantly associated with decreased risk of knee OA.

DNA methylation of noncoding RNAs: new insights into osteogenesis and common bone diseases

Bone diseases such as osteoarthritis, osteoporosis, and bone tumor present a severe public health problem. Osteogenic differentiation is a complex process associated with the differentiation of different cells, which could regulate transcription factors, cytokines, many signaling pathways, noncoding RNAs (ncRNAs), and epigenetic modulation. DNA methylation is a kind of stable epigenetic alterations in CpG islands without DNA sequence changes and is involved in cancer and other diseases, including bone development and homeostasis. ncRNAs can perform their crucial biological functions at the RNA level, and many findings have demonstrated essential functions of ncRNAs in osteogenic differentiation. In this review, we highlight current researches in DNA methylation of two relevant ncRNAs, including microRNAs and long noncoding RNAs, in the initiation and progression of osteogenesis and bone diseases.

A hyperactivating proinflammatory RIPK2 allele associated with early-onset osteoarthritis

Osteoarthritis (OA) is a common debilitating disease characterized by abnormal remodeling of the cartilage and bone of the articular joint. Ameliorating therapeutics are lacking due to limited understanding of the molecular pathways affecting disease initiation and progression. Notably, although a link between inflammation and overt OA is well established, the role of inflammation as a driver of disease occurrence is highly disputed. We analyzed a family with dominant inheritance of early-onset OA and found that affected individuals harbored a rare variant allele encoding a significant amino acid change (p.Asn104Asp) in the kinase domain of receptor interacting protein kinase 2 (RIPK2), which transduces signals from activated bacterial peptidoglycan sensors through the NF-κB pathway to generate a proinflammatory immune response. Functional analyses of RIPK2 activity in zebrafish embryos indicated that the variant RIPK2104Asp protein is hyperactive in its signaling capacity, with augmented ability to activate the innate immune response and the NF-κB pathway and to promote upregulation of OA-associated genes. Further we show a second allele of RIPK2 linked to an inflammatory disease associated with arthritis also has enhanced activity stimulating the NF-κB pathway. Our studies reveal for the first time the inflammatory response can function as a gatekeeper risk factor for OA.

The transcriptional coactivator YAP1 is overexpressed in osteoarthritis and promotes its progression by interacting with Beclin-1

Osteoarthritis (OA) constitutes the most common disease of degenerative joints, with chondrocytes playing an important role in disease progression. However, the underlying pathobiological mechanisms have not been fully characterized. In this study, we investigated the role of Yes-associated protein 1 (YAP1)-regulated autophagy in chondrocyte proliferation, apoptosis, and differentiation. The data showed that YAP1, a transcriptional coactivator, was overexpressed in OA tissues from a murine model of OA, as analyzed by real time PCR and western blot. Overexpression of YAP1 significantly suppressed ATDC5 chondrogenic cell proliferation and decreased the expression of differentiation-related genes including Runx2, osteocalcin, and collagen I, and elevated cell apoptosis, whereas these cellular processes were reversed by knockdown of YAP1. Immunofluorescence analysis demonstrated that YAP1 co-localized with the autophagy regulator beclin1. Co-immunoprecipitation experiments indicated that this interaction was enhanced in OA tissues. In contrast, YAP1 lacking the internal WW domains failed to interact with beclin1 and was unable to inhibit beclin1 ubiquitination. This resulted in upregulated autophagy, which significantly improved OA by increasing chondrocyte proliferation and differentiation. Notably, YAP1 expression was significantly downregulated by various anti-OA drugs. Finally, the Yap1 promoter was activated by transcriptional factors AP2α and SP1, whereas its 3'UTR was targeted by miR-5624-5p, miR-33-3p, and miR-6918-5p. In conclusion, inhibition of YAP1 could facilitate beclin1-regulated autophagy in OA, suggesting a potential therapeutic approach to combat OA.

Identification of MAVS as a Novel Risk Factor for the Development of Osteoarthritis

Evidence indicated that inflammatory response and some pattern-recognition receptors play important roles in the occurrence and progression of osteoarthritis. This study is conducted to evaluate the role of RIG-I and its adaptor protein MAVS in the pathogenesis of osteoarthritis. Four SNPs in RIG-I gene and four in MAVS gene were genotyped in 1056 Chinese Han population. We also overexpressed MAVS in murine chondrogenic ATDC5 cells and analyzed the cell viability and apoptosis. Rs11795343 (P_-allele: 0.063394) in RIG-I, rs17857295 (P_-allele: 0.073518) and rs7262903 (P_-allele: 0.054052, P_-genotype: 0.067930) in MAVS were marginally associated with OA. Rs7269320 (P_-allele: 0.014783, P_-genotype: 0.03272) in MAVS was significant associated with OA. Further analyses in different genders indicated that rs7262903 (P_-allele: 0.017256, P_-genotype: 0.045683) and rs7269320 (P_-allele: 0.013073, P_-genotype: 0.038881) are significantly associated with OA in female group. Haplotype analyses indicated G-C-G (χ²: 4.328, P_-value: 0.037503) in rs10813821-rs11795343-rs659527 block of RIG-I, G-C-A-T (χ²: 4.056, P_-value: 0.044028) and G-C-C-C (χ²: 14.295, P_-value: 0.000158) in rs17857295-rs2326369-rs7262903-rs7269320 block of MAVS were significantly associated with OA. Furthermore, forced expression of MAVS could suppress the viability and promote the apoptosis of ATDC5 chondrogenic cells. In conclusion, this study indicated that RIG-I and MAVS are probably associated with OA in the females of Chinese Han population. And MAVS might be a novel risk factor for OA which may involve in growth of chondrocytes and cartilage homeostasis.

Adipokine genes and radiographic hand osteoarthritis in Finnish women: a cross-sectional study

OBJECTIVES

Available evidence suggests that genetic factors and overweight play major roles in the aetiology of osteoarthritis (OA). We analysed the association of 18 single-nucleotide polymorphisms (SNPs) from nine adipokine and adipokine receptor genes (LEP, LEPR, ADIPOQ, RETN, NAMPT, SERPINA12, ITLN1, RARRES2, and APLN) with radiographic hand OA.

METHOD

The study design was cross-sectional. Bilateral hand radiographs of 542 occupationally active Finnish female dentists and teachers aged 45-63 years were examined and classified for the presence of hand OA using reference images. Hand OA was defined as at least three finger joints with radiographic OA of grade 2-4. The genotypes were determined using polymerase chain reaction-based methods. Body mass index (BMI) was calculated based on self-reported height and measured weight. Associations of the individual SNPs and their haplotypes with hand OA were tested using logistic regression analysis.

RESULTS

The minor allele of RETN rs10401670 was associated with a decreased [odds ratio (OR) = 0.73, 95% confidence interval (CI) 0.55-0.97, p = 0.03] and RARRES2 rs4721 with an increased (OR 1.41, 95% CI 1.07-1.87, p = 0.01) prevalence of hand OA. Also, LEPR AC (OR 1.54, 95% CI 1.01-2.35, p = 0.05) and RETN GGTT (OR 0.58, 95% CI 0.37-0.93, p = 0.02) haplotypes were associated with hand OA. These associations were modified by BMI when comparing normal and overweight women. However, the associations lost their statistical significance after adjusting for multiple testing.

CONCLUSION

Our results suggest weak associations between the studied variations in LEPR, RARRES2, and RETN genes and hand OA in Finnish women, and that the associations are modified by BMI. However, these associations could not be verified in the current study.

No association of the single nucleotide polymorphism rs8044769 in the fat mass and obesity-associated gene with knee osteoarthritis risk and body mass index: A population-based study in China

OBJECTIVES

Previous genome-wide association studies (GWAS) have reported significant association of the single nucleotide polymorphism (SNP) rs8044769 in the fat mass and obesity-associated gene (FTO) with osteoarthritis (OA) risk in European populations. However, these findings have not been confirmed in Chinese populations.

METHODS

We systematically genotyped rs8044769 and evaluated the association between the genetic variants and OA risk in a case-controlled study including 196 OA cases and 442 controls in a northern Chinese population. Genotyping was performed using the Sequenom MassARRAY iPLEX platform.

RESULTS

We found that the variant T allele of rs8044769 showed no significant association of OA risk (p = 0.791), or association with body mass index (BMI) (pmeta = 0.786) in an additive genetic model. However, we detected a significant interaction between rs8044769 genotypes and BMI on OA risk (p = 0.037), as well as a borderline interaction between rs8044769 genotypes and age on OA risk (p = 0.062).

CONCLUSIONS

Our findings indicate that rs8044769 in the FTO gene may not modify individual susceptibility to OA or increased BMI in the Chinese population. Further studies are warranted to validate and extend our findings.Cite this article: Prof L. Jiang. No association of the single nucleotide polymorphism rs8044769 in the fat mass and obesity-associated gene with knee osteoarthritis risk and body mass index: A population-based study in China. Bone Joint Res 2016;5:169-174. DOI: 10.1302/2046-3758.55.2000589.

Genome-wide DNA methylation profile implicates potential cartilage regeneration at the late stage of knee osteoarthritis

OBJECTIVE

The aim of this work was to characterize the genome-wide DNA methylation profile of cartilage from three regions of tibial plateau isolated from patients with primary knee osteoarthritis (OA), providing the first DNA methylation study that reflects OA progression.

METHODS

The unique model system was used to section three regions of tibial plateau: the outer lateral tibial plateau (oLT), the inner lateral tibial plateau (iLT) and the inner medial tibial plateau (iMT) regions which represented the early, intermediate and late stages of OA, respectively. Genome-wide DNA methylation profile was examined using Illumina Infinium HumanMethylation450 BeadChip array. Comparisons of the iLT/oLT and iMT/oLT groups were carried out to identify differentially methylated (DM) probes (DMPs) associated with OA progression. DM genes were analyzed to identify the gene ontologies (GO), pathways, upstream regulators and networks.

RESULTS

No significant DMPs were identified in iLT/oLT group, while 519 DMPs were identified in iMT/oLT group. Over half of them (68.2%) were hypo-methylated and enriched in enhancers and OpenSea. Upstream regulator analysis identified many microRNAs. DM genes were enriched in transcription factors, especially homeobox genes and in Wnt/β-catenin signaling pathway. These genes also showed changes in expression when analyzed with expression profiles generated from previous studies.

CONCLUSION

Our data suggested the changes in DNA methylation occurred at the late stage of OA. Pathways and networks enriched in identified DM genes highlighted potential etiologic mechanism and implicated the potential cartilage regeneration in the late stage of knee OA.

The Genetic Epidemiological Landscape of Hip and Knee Osteoarthritis: Where Are We Now and Where Are We Going?

Osteoarthritis (OA) is a complex disease that affects the whole joint, with multiple biological and environmental factors contributing to its development. The heritable component for primary OA accounts for ∼50% of susceptibility. So far, candidate gene studies and genome-wide association scans have established 18 OA-associated loci. These findings account for 11% of the heritability, explaining a rather small fraction of the genetic component. To further unravel the genetic architecture of OA, the field needs to facilitate more precise phenotypic definitions, high genome coverage, and large sample metaanalyses, expecting the identification of rare and low frequency variants with potentially higher penetrance, and more accurate methods for calculating phenotype-genotype correlation. Expression analysis, epigenetics, and investigation of interactions can also help clarify the implicated transcriptional regulatory pathways and provide insights into further novel pathogenic OA mechanisms leading to diagnostic biomarker identification and new, more focused therapeutic disease approaches.