Association of single-nucleotide polymorphisms in HLA class II/III region with knee osteoarthritis

Mechanics- and Behavior-Related Temporomandibular Joint Differences

Fatigue of temporomandibular joint (TMJ) tissues reflects the effects of magnitude (energy density; ED) and frequency of loading (jaw muscle duty factor; DF). This observational study measured these variables and tested for differences in mechanobehavior scores (MBS = ED2 × DF) and component variables in subjects with and without TMJ disc displacement (±D). In accordance with Institutional Review Board and STROBE guidelines, written informed consent was obtained, and examination and imaging protocols identified eligible adult subjects. Specifically, magnetic resonance imaging was used to assign subjects' TMJs to ±D groups. Subjects were trained to record in-field jaw muscle activities, from which DFs (percentage of recording time) were determined. EDs (mJ/mm3) were estimated using modeled TMJ loads and in vivo dynamic stereometry. Multivariate analysis of variance, post hoc independent t tests, and K-means cluster analysis identified significant group differences (P < 0.05). Of 242 individuals screened, 65 females (TMJs: 78 +D, 52 -D) and 53 males (TMJs: 39 +D, 67 -D) participated. Subjects produced 312 daytime and 319 nighttime recordings of average duration 6.0 ± 0.2 h and 7.6 ± 0.1 h, respectively, and 219 (114 right, 105 left) intact dynamic stereometry recordings. Average EDs were 2-fold and significantly larger in +D than -D TMJs (P < 0.0001). DFs were on average 3-fold larger during the daytime versus nighttime for both masseter and temporalis muscles and 1.8- and 3.0-fold larger for the masseter versus temporalis muscle during the daytime and nighttime, respectively. Daytime masseter MBSs for +D TMJs in females were the largest overall at 621 ± 212 (mJ/mm3)2% and 2- to 43-fold larger versus -D TMJs in both sexes during daytime and nighttime. Cluster analysis (P < 0.0001) identified groups 2 and 3, which comprised 87% +D TMJs and had average MBSs 21-fold larger than group 1. The results show MBS as a potential biomarker to predict homeostasis versus progression or reversal of degenerative TMJ structural changes.

Intergenic Interactions of SBNO1, NFAT5 and GLT8D1 Determine the Susceptibility to Knee Osteoarthritis among Europeans of Russia

This study was conducted to examine the associations between genome-wide association studies (GWAS)-important single nucleotide polymorphisms (SNPs) and knee osteoarthritis (KOA) among Europeans of Russia. The present replicative study ("patient-control" design has been used) was carried out on 1000 DNA samples from KOA (n = 500) and KOA-free (n = 500) participants. Ten GWAS-important for KOA SNPs of eight candidate genes (LYPLAL1, GNL3, GLT8D1, SBNO1, WWP2, NFAT5, TGFA, GDF5) were studied. To assess the link between SNPs and KOA susceptibility, logistic regression (to establish independent SNP effects) and MB-MDR (to identify SNP-SNP interactions) were used. As a result of this genetic analysis, the associations of individual SNPs with KOA have not been proven. Eight loci out of ten tested SNPs interacted with each other (within twelve genetic models) and determined susceptibility to KOA. The greatest contribution to the disease development were made by three polymorphisms/genes such as rs6976 (C>T) GLT8D1, rs56116847 (G>A) SBNO1, rs6499244 (T>A) NFAT5 (each was included in 2/3 [8 out 12] KOA-responsible genetic interaction models). A two-locus epistatic interaction of rs56116847 (G >A) SBNO1 × rs6499244 (T>A) NFAT5 determined the maximum percentage (0.86%) of KOA entropy. KOA-associated SNPs are regulatory polymorphisms that affect the expression/splicing level, epigenetic modification of 72 genes in KOA-pathogenetically significant organs such as skeletal muscles, tibial arteries/nerves, thyroid, adipose tissue, etc. These putative KOA-effector genes are mainly involved in the organization/activity of the exoribonuclease complex and antigen processing/presentation pathways. In conclusion, KOA susceptibility among Europeans of Russia is mediated by intergenic interactions (but not the main effects) of GWAS-important SNPs.

Correlation between Interleukin-17 gene polymorphism and osteoarthritis susceptibility in Han Chinese population

Background

Interleukin-17 (IL-17), a pleiotropic cytokine, plays a significant role in the inflammatory diseases. By a pilot study with small population, IL-17 polymorphisms (IL-17A rs2275913 and IL-17F rs763780) showed a more potential risk factor in knee osteoarthritis (OA) in our recruited subjects. In the current study, the association between IL-17A rs2275913 and IL-17F rs763780and the risk of OA in a Chinese population is studied.

Methods

The IL-17A rs2275913 and IL-17F rs763780 polymorphisms were determined in 594 knee OA cases and 576 healthy controls, using polymerase chain reaction-restriction fragment length polymorphism assay. The relationship between genotype distribution and disease risk, as well as OA severity was analyzed by Chi-square test and multivariate logistic regression.

Results

The experimental results indicated that the polymorphism in IL-17 gene rs2275913 site were related to knee OA risk after the adjustment of BMI, sex, age, smoking and drinking status (AA vs. GG: odds ratio (OR), 1.411; 95% confidence interval (CI), 1.021–1.950; P = 0.040; A allele vs. G allele: OR, 1.192; P = 0.037; 95% CI, 1.012–1.404;). Similarly, subjects who are bearing the rs763780 variant genotypes (TC and CC) and C allele also had a higher susceptibility to knee OA compared with those who are bearing the TT genotype (TC vs. TT, OR: 1.312; P = 0.039; 95% CI: 1.017–1.692; CC vs. TT, OR: 2.812, P = 0.006, 95% CI: 1.338–5.909; C allele Vs. T allele, OR:1.413, P = 0.002, 95% CI:1.141–1.751). In the meantime, one high-risk haplotypes, AC (OR was 7.22, P < 0.01) was found. Both two polymorphisms do not correlated with OA severity based on Kellgren-Lawrence (K&L) scales. Finally, serum IL-17 levels of knee OA patients were greatly higher than those of controls (P = 0.001).

Conclusions

With the limited size sample, our study shows that IL-17 gene polymorphisms possibly related to the high-risk knee OA occurrence.

Genome-Wide Meta-Analysis of Sciatica in Finnish Population

Sciatica or the sciatic syndrome is a common and often disabling low back disorder in the working-age population. It has a relatively high heritability but poorly understood molecular mechanisms. The Finnish population is a genetic isolate where small founder population and bottleneck events have led to enrichment of certain rare and low frequency variants. We performed here the first genome-wide association (GWAS) and meta-analysis of sciatica. The meta-analysis was conducted across two GWAS covering 291 Finnish sciatica cases and 3671 controls genotyped and imputed at 7.7 million autosomal variants. The most promising loci (p<1x10^-6) were replicated in 776 Finnish sciatica patients and 18,489 controls. We identified five intragenic variants, with relatively low frequencies, at two novel loci associated with sciatica at genome-wide significance. These included chr9:14344410:I (rs71321981) at 9p22.3 (NFIB gene; p = 1.30x10^-8, MAF = 0.08) and four variants at 15q21.2: rs145901849, rs80035109, rs190200374 and rs117458827 (MYO5A; p = 1.34x10^-8, MAF = 0.06; p = 2.32x10^-8, MAF = 0.07; p = 3.85x10^-8, MAF = 0.06; p = 4.78x10^-8, MAF = 0.07, respectively). The most significant association in the meta-analysis, a single base insertion rs71321981 within the regulatory region of the transcription factor NFIB, replicated in an independent Finnish population sample (p = 0.04). Despite identifying 15q21.2 as a promising locus, we were not able to replicate it. It was differentiated; the lead variants within 15q21.2 were more frequent in Finland (6–7%) than in other European populations (1–2%). Imputation accuracies of the three significantly associated variants (chr9:14344410:I, rs190200374, and rs80035109) were validated by genotyping. In summary, our results suggest a novel locus, 9p22.3 (NFIB), which may be involved in susceptibility to sciatica. In addition, another locus, 15q21.2, emerged as a promising one, but failed to replicate.

Role of HIF-1α signaling pathway in osteoarthritis: a systematic review

Osteoarthritis (OA) is the most common form of arthritis and is frequently diagnosed and managed in primary care; it is characterized by loss of articular hyaline cartilage, which is a unique connective tissue that physiologically lacks blood vessels. Articular cartilage survives in a microenvironment devoid of oxygen, which is regulated by hypoxia inducible factor (HIF-1α). HIF-1α is considered the main transcriptional regulator of cellular and developmental response to hypoxia. To date, the relevance of HIF-1α in the assessment of cartilage has increased since its participation is essential in the homeostasis of this tissue. Taking into account the new emerging insights of HIF-1α in the scientific literature in the last years, we focused the present review on the potential role of HIF-1α signaling pathway in OA development, especially in how some genetic factors may influence the maintenance or breakdown of articular cartilage.

The role of inflammation-related genes in osteoarthritis

In this review article we examine the role of inflammation-related genes in osteoarthritis (OA) from the perspective of genetics, epigenetics and gene expression. There have been great strides in such genomic analyses of OA in recent years thanks to the study of adequately powered patient cohorts, the detailed analysis of candidate genes, and the application of genome-wide approaches. These have led to some unexpected and therefore exciting discoveries, implicating pathways that would not necessarily have been predicted to have a role in this common arthritis. Inflammatory-related genes sit firmly in the candidate camp based on prior observations that the OA disease process can have an inflammatory component. What is clear from the genetic studies published to date is that there is no compelling evidence that DNA variation in inflammatory genes is an OA risk factor. This conclusion may of course change as ever more powerful association studies are conducted. There is, however, compelling evidence that epigenetic effects involving inflammatory genes are a component of OA and that alteration in the expression of these genes is also highly relevant to the disease process. We may in fact be close to demonstrating, at the genomic level, a clear separation of OA patients into those in whom inflammation is a key driver of the disease and those in whom it is not. This has obvious implications for the design of trials of novel OA interventions and may also guide the intelligent re-purposing of anti-inflammatory therapies.

Polymorphic variation of hypoxia inducible factor-1 A (HIF1A) gene might contribute to the development of knee osteoarthritis: a pilot study

Background

Osteoarthritis (OA) is a multifactorial degenerative condition of the whole joint with a complex pathogenesis whose development and progression is significantly mediated by interactions between the joint cartilage and articular tissues, particularly, proinflammatory mediators and oxidative stress, which results in cartilage deterioration and subchondral bone destruction. HIF-1 alpha regulates oxygen homeostasis in hypoxic tissues such as joint cartilage; efficiency of transcriptional activity of the HIF1A gene is strongly influenced by the presence of polymorphic variants. Given the loss of articular cartilage and with intention to restore damaged tissue, WISP-1 participates in the development of subchondral bone; further, its expression is highly increased in chondrocytes of OA patients. The aim of this study was to evaluate gene frequencies of HIF1A and WISP1 polymorphisms in Mexican patients suffering from knee OA.

Methods

We determined HIF1A rs11549465 (P582S), rs11549467 (A588T), and rs2057482 (C191T), and WISP1 rs2929970 (A2364G) polymorphisms in 70 Mexican patients with knee OA and compare them to those present in 66 ethnically matched healthy controls. Genotyping for these polymorphisms was performed by Real-Time PCR using TaqMan probes.

Results

Gene frequencies exhibited a significant increase of the CC genotype of rs11549465 polymorphism in knee OA patients as compared with those present in controls (P = 0.003 OR = 5.7, 95 % CI = 1.7–21.6); CT genotype and T allele showed decreased frequency in the knee OA group vs. the controls (P = 0.003 OR = 0.2, CI = 0.05–0.6; and P = 0.004 OR = 0.2, CI = 0.05–0.65, respectively). Allele frequencies of the other polymorphic variants were similar in both patients and controls.

Conclusions

These results suggest that the presence of the rs11549465 SNP (HIF1A) plays a role protective in the loss of articular cartilage in our population, and offers the possibility to further study the molecular mechanisms within cartilage and subchondral bone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0678-z) contains supplementary material, which is available to authorized users.

Meta-analysis of tumor necrosis factor alpha -308 polymorphism and knee osteoarthritis risk

Background

Several case–control studies have been conducted to clarify the association between the tumor necrosis factor alpha (TNF-α) -G308A polymorphism and risk of osteoarthritis (OA); however, the results are inconsistent. This meta-analysis was performed to clarify this issue using all the available evidence.

Methods

Eligible articles were retrieved by searching PubMed, Web of science and Google scholar. The strength of the association between the TNF-α -G308A polymorphism and risk of OA was assessed by odds ratios (ORs) with the corresponding 95% confidence interval (CI) for each study.

Results

Seven studies were included in the meta-analysis, which included 983 OA cases and 1355 controls. The pooled analysis based on all included studies showed a significantly increased OA risk in the recessive genetic model analysis (OR = 11.08, 95% CI = 4.75-25.86, p < 0.001) and in the A allele vs. G allele analysis (OR = 2.30, 95% CI = 1.08-4.90). However, there was no statistical difference in the dominant genetic model analysis (OR = 2.45, 95% CI = 0.95-6.27, p = 0.06). Furthermore, we found that OA patients had a higher frequency of the AA genotype (OR = 10.49, 95% CI = 4.47-24.61) and GA genotype (OR = 1.78, 95% CI = 1.03-3.08) compared with the control population.

Conclusion

Our results suggested that the TNF-α -G308A polymorphism were associated with an increased risk of OA.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-373) contains supplementary material, which is available to authorized users.

Advances in osteoarthritis genetics

Osteoarthritis (OA), the most common form of arthritis, is a highly debilitating disease of the joints and can lead to severe pain and disability. There is no cure for OA. Current treatments often fail to alleviate its symptoms leading to an increased demand for joint replacement surgery. Previous epidemiological and genetic research has established that OA is a multifactorial disease with both environmental and genetic components. Over the past 6 years, a candidate gene study and several genome-wide association scans (GWAS) in populations of Asian and European descent have collectively established 15 loci associated with knee or hip OA that have been replicated with genome-wide significance, shedding some light on the aetiogenesis of the disease. All OA associated variants to date are common in frequency and appear to confer moderate to small effect sizes. Some of the associated variants are found within or near genes with clear roles in OA pathogenesis, whereas others point to unsuspected, less characterised pathways. These studies have also provided further evidence in support of the existence of ethnic, sex, and joint specific effects in OA and have highlighted the importance of expanded and more homogeneous phenotype definitions in genetic studies of OA.

Association analysis of two candidate polymorphisms in the tumour necrosis factor-α gene with osteoarthritis in a Chinese population

PURPOSE

The purpose of this study was to investigate the possible association between single nucleotide polymorphisms (SNPs) rs1800629 (TNF-α -308) and rs361525 (TNF-α -238) of the tumour necrosis factor (TNF)-α gene and susceptibility to osteoarthritis (OA) in the Han Chinese population.

METHODS

The TNF-α -308 and -238 genotypes were determined by TaqMan assay in 200 OA cases and 305 controls. Odds ratios (ORs) for OA and 95% confidence intervals (CIs) from unconditional logistic regression models were used to evaluate relative risks.

RESULTS

The frequencies of the allele 'A' of rs1800629 were 16% and 8.85% in OA cases and in controls, respectively, and thus the -308A allele had a 1.9612-fold (95% CI = 1.3323-2.8869, P < 0.001) increased risk for OA as compared to the -308G allele. However, no significant differences were found in the genotype and allele frequencies for rs361525 between OA and HC groups.

CONCLUSIONS

In the Han Chinese population, the allele 'A' of TNF-α -308 may increase the risk for OA, whereas TNF-α -238 polymorphisms do not play a role in OA patients.

Genetic factors in OA pathogenesis

Osteoarthritis (OA) is known to have an important genetic component and human genetic studies can help unravel the molecular mechanisms responsible for joint damage and nociception involved in OA. Genetic studies in humans have identified molecules involved in signaling cascades that are important for the pathology of the joint components such as the bone morphogenetic protein growth differentiation factor 5 (GDF5). Genomewide association scans (GWAS) in Asians have uncovered a likely role for structural extracellular matrix components (DVWA), and for molecules involved in immune response (HLA class II DQB1 and BTNL2) but these genes are not associated in Caucasian patients. In Caucasians a ~300 kilobase region in chromosome 7q22 containing several genes has been found to be reproducibly associated with OA. A recent European GWAS taking advantage of imputation techniques has uncovered a variant in the MCF2L gene as significantly associated with large joint OA. MCF2L is involved in neurotrophin mediated regulation of cell motility in the peripheral nervous system, and thus potentially implicated in nociception in OA. As the number of OA cases with genomewide genotyping increases it is expected that many more reproducible variants implicated in OA will be reported. This article is part of a Special Issue entitled "Osteoarthritis".

A large-scale replication study for the association of rs17039192 in HIF-2α with knee osteoarthritis

Osteoarthritis (OA) is a common disease with a genetic component for its etiology. Recently, a genetic association of a single nucleotide polymorphism (SNP), rs17039192 in HIF-2α with knee OA has been reported in a Japanese population; however, controversy exits for its replication and a role of HIF-2α in OA. This study aimed to evaluate the association of the SNP by a large-scale replication study. A total of 8,457 subjects (3,129 OA cases and 5,328 controls) from seven independent cohorts from six countries (Japan, China, Taiwan, Korea, Greece, and Australia) were recruited and genotyped. The association of rs17039192 with knee OA was evaluated by meta-analyses. The association of the HIF-2α SNP was not replicated in any of the populations. Contrary to the previous report, the odds ratios (ORs) of the risk allele frequency were all less than 1. A combined analysis for the seven populations also showed no replication of the association (OR = 0.91, 95% confidence interval = 0.81-1.03). Our large-scale meta-analysis showed that the association of rs17039192 in HIF-2α with knee OA is negative. The significance of HIF-2α in human OA (idiopathic OA as a common disease) should be further evaluated carefully.

Osteoarthritis year 2011 in review: genetics

In the last decades, many researchers aimed to identify causal genetic variants by means of candidate gene analyses, genome wide linkage and association studies to elucidate underlying mechanisms of osteoarthritis (OA). Although several consistent genetic variants were identified the successes are limited. This review has a focus on studies published until mid 2011 and on data presented at the Osteoarthritis Research Society International 2011 (OARSI) in San Diego and that aim to elucidate the primary molecular and cellular events commencing OA onset in humans by applying genetic study designs.

TNF-α and TNF-β Polymorphisms are Associated with Susceptibility to Osteoarthritis in a Korean Population

BACKGROUND

The tumor necrosis factor (TNF) is believed to play an important role in the pathophysiology of osteoarthritis (OA). Evidence shows that genetic polymorphisms make substantial contributions to the etiology of OA.

METHODS

We investigated the genotypes TNF-α and TNF-β in 301 OA patients and 291 healthy subjects as controls. We employed a polymerase chain reaction-restriction fragment length polymorphism and a polymerase chain reaction-single strand conformation polymorphism assay to identify the genotypes TNFA -G308A and TNFB +G252A, respectively.

RESULTS

For TNFA -G308A, the percentages of genotypes GG, AG, and AA were 26.3% (79/301), 62.5% (188/301), and 11.3% (34/301) in OA patients and 88.7% (258/291), 11.3% (33/291), and 0% (0/291) in controls. For TNFB +G252A, the percentages of genotypes GG, AG, and AA were 15.3% (46/301), 41.9% (126/301), and 42.9% (129/301) in OA patients and 12% (35/291), 52.6% (153/291), and 35.4% (103/291) in controls. There were significant differences in genotypes and alleles of TNFA -308 between OA patients and controls (p<0.0001) and in alleles of TNFB +252 (p=0.0325). The risk of OA was significantly higher for carriers of the TNFA -308A allele and the TNFB +252 AA homozygote (p=0.0224).

CONCLUSIONS

The results suggest close relationships between TNFA -G308A and TNFB +G252A polymorphisms and individual susceptibility to OA in the Korean population.

Genetics of osteoarthritis

PURPOSE OF REVIEW

A number of reasonably powered osteoarthritis genome-wide association scans are now in the final phases of their analysis, leaving us all with baited breath. This review highlights some of the osteoarthritis signals and subsequent insights that have emerged from the candidate studies and smaller scale scans that have preceded these more powered studies, and which could therefore be considered as appetizers to the hopeful treats to follow.

RECENT FINDINGS

If one applies the strict criteria of genome-wide significance thresholds, only two current signals pass muster: GDF5 and 7p22. If one relaxes slightly, other signals emerge, such as DIO2, SMAD3 and ASPN. After these, however, we enter the realm where faith takes precedence.

SUMMARY

The search for osteoarthritis susceptibility loci has not been as successful as many had anticipated. This reflects many factors, including the heterogeneous nature of the disease, the tendency to use less severe phenotypes in genetic searches and the reliance on underpowered studies. We do, however, have some successes and in the very near future others will emerge from the more powered scans. Hopefully, combining the current with the new will help our attempts to understand the cause of this complex, common arthritis.

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) (r(2) = 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 (r(2)<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.

Osteoarthritis year 2010 in review: genetics

At the 2010 Osteoarthritis Research Society International (OARSI) congress in Brussels I was asked to present on "Genetics" in the "Year in Review" session. This gave me an opportunity to reflect on the talk that I gave on the same topic at the 2007 OARSI congress in Ft Lauderdale, Florida. My 2007 talk was very upbeat and ended with the hostage to fortune statement "The next few years will provide tremendous clarity in our genetic understanding of osteoarthritis".