Ann Tamm

Genetic variation in the SMAD3 gene is associated with hip and knee osteoarthritis.

OBJECTIVE Smad3 (or, MADH3) is a key intracellular messenger in the transforming growth factor beta signaling pathway. In mice, Smad3 deficiency accelerates growth plate chondrocyte maturation and leads to an osteoarthritis (OA)-like disease. We undertook this study to investigate the role of genetic variation in SMAD3 in the risk of large-joint OA in humans. METHODS Ten tag single-nucleotide polymorphisms (SNPs) in the SMAD3 gene region were tested in a discovery set: 313 patients who had undergone total knee replacement, 214 patients who had undergone total hip replacement, and 520 controls from the UK. The SNP associated with both hip and knee OA was subsequently genotyped in 1,221 controls and 1,074 cases from 2 cohorts of patients with hip OA and 2,537 controls and 1,575 cases from 4 cohorts of patients with knee OA. RESULTS A SNP (rs12901499) mapping to intron 1 of SMAD3 was associated with both knee and hip OA (P < 0.0022 and P < 0.021, respectively) in the discovery set. In all study cohorts, the major allele (G) was increased among OA patients relative to controls. A meta-analysis for knee OA yielded an odds ratio (OR) of 1.22 (95% confidence interval [95% CI] 1.12-1.34), P < 7.5 x 10(-6). For hip OA, the OR was 1.22 (95% CI 1.09-1.36), P < 4.0 x 10(-4). No evidence for heterogeneity was found (I(2) = 0%). CONCLUSION Our data indicate that genetic variation in the SMAD3 gene is involved in the risk of both hip OA and knee OA in European populations, confirming the results from animal models on the potential importance of this molecule in the pathogenesis of OA.

The GDF5 rs143383 polymorphism is associated with osteoarthritis of the knee with genome-wide statistical significance

Osteoarthritis of the knee is a major cause of pain, disability and the use of healthcare resources among middle-aged and older people.1 Although osteoarthritis is multifactorial, it is known to have a significant genetic contribution and a number of studies have attempted to dissect such a contribution (see Valdes and Spector2 for review). The GDF5 gene encodes the growth differentiation factor 5, a bone morphogenetic protein involved in joint formation, expressed in different joint structures, which has been shown to ameliorate tendon, ligament and bone healing after trauma in mice.3 4 A promoter polymorphism (rs143383) in GDF5 has been found to be strongly associated with both hip and knee osteoarthritis in Asian individuals,4 and is the most widely replicated genetic association with knee osteoarthritis, although much less so for hip and hand osteoarthritis.5 This variant is functional, with the lower gene expression variant having increased genetic risk.4 A large-scale meta-analysis reported the association of the major (T) allele with knee osteoarthritis achieved OR 1.15 p=9.7×10−7 and achieved p=9×10−5 (OR 1.13, 95% CI 1.06 to 1.20) when Asian subjects were excluded.5 The genome-wide statistical significance level of p<5×10−8 is increasingly …

Meta-analysis of genome-wide association studies confirms a susceptibility locus for knee osteoarthritis on chromosome 7q22

Objectives Osteoarthritis (OA) is the most prevalent form of arthritis and accounts for substantial morbidity and disability, particularly in older people. It is characterised by changes in joint structure, including degeneration of the articular cartilage, and its aetiology is multifactorial with a strong postulated genetic component. Methods A meta-analysis was performed of four genome-wide association (GWA) studies of 2371 cases of knee OA and 35 909 controls in Caucasian populations. Replication of the top hits was attempted with data from 10 additional replication datasets. Results With a cumulative sample size of 6709 cases and 44 439 controls, one genome-wide significant locus was identified on chromosome 7q22 for knee OA (rs4730250, p=9.2×10−9), thereby confirming its role as a susceptibility locus for OA. Conclusion The associated signal is located within a large (500 kb) linkage disequilibrium block that contains six genes: PRKAR2B (protein kinase, cAMP-dependent, regulatory, type II, β), HPB1 (HMG-box transcription factor 1), COG5 (component of oligomeric golgi complex 5), GPR22 (G protein-coupled receptor 22), DUS4L (dihydrouridine synthase 4-like) and BCAP29 (B cell receptor-associated protein 29). Gene expression analyses of the (six) genes in primary cells derived from different joint tissues confirmed expression of all the genes in the joint environment.

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

OBJECTIVE To clarify the role of common genetic variation in the Interleukin-1β (IL1B) and Interleukin-1R antagonist (IL1RN) genes on risk of knee and hip osteoarthritis (OA) and severity of knee OA by means of large-scale meta-analyses. METHODS We searched PubMed for articles assessing the role of IL1B and IL1RN polymorphisms/haplotypes on the risk of hip and/or knee OA. Novel data were included from eight unpublished studies. Meta-analyses were performed using fixed- and random-effects models with a total of 3595 hip OA and 5013 knee OA cases, and 6559 and 9132 controls respectively. The role of ILRN haplotypes on radiographic severity of knee OA was tested in 1918 cases with Kellgren-Lawrence (K/L) 1 or 2 compared to 199 cases with K/L 3 or 4. RESULTS The meta-analysis of six published studies retrieved from the literature search and eight unpublished studies showed no evidence of association between common genetic variation in the IL1B or IL1RN genes and risk of hip OA or knee OA (P>0.05 for rs16944, rs1143634, rs419598 and haplotype C-G-C (rs1143634, rs16944 and rs419598) previously implicated in risk of hip OA). The C-T-A haplotype formed by rs419598, rs315952 and rs9005, previously implicated in radiographic severity of knee OA, was associated with reduced severity of knee OA (odds ratio (OR)=0.71 95%CI 0.56-0.91; P=0.006, I(2)=74%), and achieved borderline statistical significance in a random-effects model (OR=0.61 95%CI 0.35-1.06 P=0.08). CONCLUSION Common genetic variation in the Interleukin-1 region is not associated with prevalence of hip or knee OA but our data suggest that IL1RN might have a role in severity of knee OA.

Missense single nucleotide polymorphism of the ADAM12 gene is associated with radiographic knee osteoarthritis in middle-aged Estonian cohort

OBJECTIVE One of the recognized candidate genes of osteoarthritis (OA) is the ADAM metallopeptidase domain 12 (meltrin alpha) gene. We investigated the potential role of two single nucleotide polymorphisms (SNP) of the ADAM12 gene in susceptibility to radiographic knee OA and its progression in an Estonian cohort. METHODS The rs3740199 and rs1871054 polymorphisms were genotyped according to restriction fragment polymorphism in a population-based cohort consisting of 189 subjects selected from the age group 32-55 years. The radiological features of OA were measured in the tibio- and patellofemoral joints (PFJ). The X-ray investigation was repeated 3 years later for estimation of OA progression. RESULTS We found statistically significant association between rs3740199 polymorphism and patellofemoral OA in male patients (P=0.014), genetic risk was mostly related to CC homozygosity. The same SNP also affected the presence of advanced grade (II+III) osteophytes in the whole group (P=0.042) and the occurrence of osteophytes on the patellar margins in the PFJ (P=0.046). In OA progression the most significant association was found between joint space narrowing of the tibiofemoral joint and rs3740199 SNP in women (P=0.018). The rs1871054 polymorphism was not related to OA susceptibility or to progression traits. In our study the haplotype GC (rs3740199/rs1871054) was associated with reduced risk for development of osteophytes in the PFJ (P=0.041). CONCLUSIONS We conclude that rs3740199 polymorphism may affect occurrence of knee OA and its progression. We also hypothesize that the genetic contribution of ADAM12 to OA is remarkably gender-dependent and anatomical site-specific.

Large Scale Replication Study of the Association between HLA Class II/BTNL2 Variants and Osteoarthritis of the Knee in European-Descent Populations

Osteoarthritis (OA) is the most common form of arthritis and a major cause of disability. This study evaluates the association in Caucasian populations of two single nucleotide polymorphisms (SNPs) mapping to the Human Leukocyte Antigen (HLA) region and deriving from a genome wide association scan (GWAS) of knee OA in Japanese populations. The frequencies for rs10947262 were compared in 36,408 controls and 5,749 knee OA cases from European-descent populations. rs7775228 was tested in 32,823 controls and 1,837 knee OA cases of European descent. The risk (major) allele at rs10947262 in Caucasian samples was not significantly associated with an odds ratio (OR)  = 1.07 (95%CI 0.94 -1.21; p = 0.28). For rs7775228 the meta-analysis resulted in OR = 0.94 (95%CI 0.81-1.09; p = 0.42) for the allele associated with risk in the Japanese GWAS. In Japanese individuals these two SNPs are in strong linkage disequilibrium (LD) (r2 = 0.86) with the HLA class II haplotype DRB1*1502 DQA1*0103 DQB1*0601 (frequency 8%). In Caucasian and Chinese samples, using imputed data, these SNPs appear not to be in LD with that haplotype (r2<0.07). The rs10947262 and rs7775228 variants are not associated with risk of knee OA in European descent populations and they do not appear tag the same HLA class II haplotype as they do in Japanese individuals.

A meta-analysis of interleukin-6 promoter polymorphisms on risk of hip and knee osteoarthritis

OBJECTIVE Interleukin-6 is a pro-inflammatory cytokine involved in the pathogenesis of osteoarthritis (OA). We investigated the role of two single nucleotide polymorphisms (SNPs) mapping to the promoter of the IL-6 gene on genetic susceptibility to hip and knee OA. METHODS The -174G/C (rs1800795) and -597G/A (rs1800797) SNPs, implicated in the literature in risk of hip and hand OA, were genotyped in 2511 controls, 1101 hip OA cases and 1904 knee OA cases from four cohorts from the UK and Estonia. Data were analysed in conjuntion with published data on rs1800797 from the Genetics of OA and Lifestyle study (UK) on 791 controls, 1034 knee and 997 hip OA cases and rs1800795 data on 75 hip OA cases and 96 controls from Italy. Cases included both radiographic OA only and radiographic and symptomatic OA. Fixed and random-effects meta-analysis models were tested. RESULTS No significant association was found with hip OA or knee OA with either SNP nor with the haplotypes formed by them. For individual SNPs the smallest P-value for hip OA was observed using a random-effects model for rs1800795 OR(Gallele)=1.066 (95% CI 0.89-1.28) P<0.49, and significant heterogeneity between cohorts (I(2)=65%, P<0.034) was detected. For knee OA the smallest P-value was seen for rs1800797 OR(Aallele)=1.055 (95%CI 0.98-1.12) P<0.18, no significant heterogeneity was observed (I(2)=0%, P<0.68). CONCLUSIONS Our data do not support a role for the -174 and -597 IL-6 promoter polymorphisms in genetic susceptibility to knee or hip OA in Caucasian populations.

Diagnostic and prognostic value of bone biomarkers in progressive knee osteoarthritis: a 6-year follow-up study in middle-aged subjects

OBJECTIVE To determine the value of bone markers in early-stage progressive knee osteoarthritis (OA), a population-based cohort of middle-aged subjects with chronic knee complaints was followed over 6 years (two consecutive two 3-year periods). METHODS Tibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline 45 ± 6.2 years) in 2002, 2005 and 2008. Bone formation was assessed by the serum concentration of procollagen type I amino-terminal propeptide (sPINP); bone resorption by the level of the C-terminal cross-linked telopeptides of type I collagen (sCTx-I); and bone mineralization by the values of osteocalcin (sOC) by electrochemiluminescence immunoassay. A novel marker of bone resorption, urinary osteocalcin midfragments (uMidOC), was assayed using enzyme linked immunosorbent assay (ELISA). RESULTS Several diagnostic associations were found between the bone markers (PINP, OC, MidOC) and progressive OA expressed by TF osteophytosis. The increasing output of MidOC demonstrated several-fold higher risk for progressive TF osteophytosis [odds ratio (OR) 5.32; 95% confidence interval (CI) 1.41-20.06, P = 0.014] than other bone markers. The values of PINP had prognostic value for subsequent more severely expressed knee OA progression [r(s) = 0.460, P = 0.005]. CONCLUSIONS Bone metabolism is activated in early-stage knee OA. OA progression was preceded by the enhanced bone formation (by PINP) and accompanied by the activation of bone formation (by PINP), non-collagenous bone resorption (by MidOC), as well as by changes in mineralization (by OC). All three bone markers had diagnostic value, and one of them, PINP, had also a predictive value for knee OA progression, especially for progressive osteophytosis.

The ADAM12 is upregulated in synovitis and postinflammatory fibrosis of the synovial membrane in patients with early radiographic osteoarthritis

OBJECTIVE To investigate the possible association between ADAM12 (disintegrin and metalloproteinase domain12) expression in the synovium and the histological synovitis of patients with radiographic knee osteoarthritis (rKOA). METHODS The synovial biopsy samples were harvested from 44 subjects with chronic knee complaints during arthroscopy. In all subjects, the radiographs of both knee joints were performed for rKOA assessment. Histological features of synovitis were graded 0-3 in synovial samples. Messenger RNA (mRNA) of two ADAM12 splice variants [ADAM12-S(hort) and ADAM12-L(ong)] and the identical region for both-ADAM12-B(oth) were measured by real-time reverse transcription-PCR in all synovial samples (TaqMan® gene expression assay). Immunohistochemical staining of the synovial membrane with ADAM12 antibody was performed in 42 subjects. RESULTS ADAM12 mRNA was expressed in all synovial samples, whereas the main part of overall expression consisted of its long isoform (ADAM12-L). ADAM12 protein expression was detected in 80% of the synovial samples and correlated with mRNA expression (ρ=0.30, P<0.05). The expression of ADAM12 mRNA and protein in synovium correlated with the severity of histological synovitis (ρ=0.28, P<0.05 for ADAM12-B mRNA, R2=0.20, P<0.05 for ADAM12 protein). Out of several features of synovitis the expression level of both splice variants correlated only with the grade of fibrosis in the synovium (ρ=0.30, P<0.05 for ADAM12-L and ρ=0.33, P<0.05 for ADAM12-S). CONCLUSIONS ADAM12 is upregulated in the synovial tissue during synovitis on mRNA and protein level. We suggest that ADAM12 could be implicated in the development of KOA-associated synovitis, especially in the occurrence of postinflammatory fibrosis.

Two Single-Nucleotide Polymorphisms in ADAM12 Gene Are Associated with Early and Late Radiographic Knee Osteoarthritis in Estonian Population

Objectives. To investigate associations of selected single-nucleotide polymorphisms (SNPs) in ADAM12 gene with radiographic knee osteoarthritis (rKOA) in Estonian population. Methods. The rs3740199, rs1871054, rs1278279, and rs1044122 SNPs in ADAM12 gene were genotyped in 438 subjects (303 women) from population-based cohort, aged 32 to 57 (mean 45.4). The rKOA features were evaluated in the tibiofemoral joint (TFJ) and patellofemoral joint. Results. The early rKOA was found in 51.4% of investigated subjects (72% women) and 12.3% of participants (63% women) had advanced stage of diseases. The A allele of synonymous SNP rs1044122 was associated with early rKOA in TFJ, predominantly with the presence of osteophytes in females (OR 1.57; 95% CI 1.08–2.29, P = 0.018). The C allele of intron polymorphism rs1871054 carried risk for advanced rKOA, mostly to osteophyte formation in TFJ in males (OR 3.03; 95% CI 1.11–7.53, P = 0.018). Also the CCAA haplotype of ADAM12 was associated with osteophytosis, again mostly in TFJ in males (P = 0.014). For rs3740199 and rs1278279, no statistically significant associations were observed. Conclusion.   ADAM12 gene variants are related to rKOA risk during the early and late stages of diseases. The genetic risk seems to be predominantly associated with the appearance of osteophytes—a marker of bone remodelling and neochondrogenesis.