A genetic variant in the region of MMP-9 is associated with serum levels and progression of joint damage in rheumatoid arthritis

Association between matrix metalloproteinase-9-1562C/T gene polymorphism and MMP-9 serum level in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease indicated by joint inflammation and cartilage destruction. Matrix metalloproteinase (MMP) enzymes play an influential role in inflammation by affecting the invasion and degradation of anatomical barriers. In this way, the current study investigated the relationship between the MMP-9-1562C/T gene polymorphism and this enzyme's serum level in RA.

METHODS

The serum levels of MMP-9 in RA patients and healthy controls were measured using the enzyme-linked immunosorbent assay (ELISA). RA was confirmed using rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP), and C-reactive protein (CRP). Then the MMP-9-1562C/T gene polymorphism was analyzed utilizing polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Also, multivariate analysis investigated the connection between this polymorphism and the risk of RA.

RESULTS

In this study, the increase of MMP-9 in patients due to the development of single nucleotide polymorphism in the promoter region of this gene (-1562 C→T) was confirmed by increasing the frequency of heterozygous genotype (CT). Logistic regression analysis also demonstrated that the chance of development of RA is higher in people with CT/CC genotype than in other alleles.

CONCLUSIONS

We demonstrated that MMP-9-1562C/T gene polymorphism can play a significant role in the occurrence of RA.

Applications and recent advances in transdermal drug delivery systems for the treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic, systemic autoimmune disease predominantly based on joint lesions with an extremely high disability and deformity rate. Several drugs have been used for the treatment of rheumatoid arthritis, but their use is limited by suboptimal bioavailability, serious adverse effects, and nonnegligible first-pass effects. In contrast, transdermal drug delivery systems (TDDSs) can avoid these drawbacks and improve patient compliance, making them a promising option for the treatment of rheumatoid arthritis (RA). Of course, TDDSs also face unique challenges, as the physiological barrier of the skin makes drug delivery somewhat limited. To overcome this barrier and maximize drug delivery efficiency, TDDSs have evolved in terms of the principle of transdermal facilitation and transdermal facilitation technology, and different generations of TDDSs have been derived, which have significantly improved transdermal efficiency and even achieved individualized controlled drug delivery. In this review, we summarize the different generations of transdermal drug delivery systems, the corresponding transdermal strategies, and their applications in the treatment of RA.

Matrix Metalloproteinase-9 Level in Synovial Fluid-Association with Joint Destruction in Early Rheumatoid Arthritis

Background and objective: Matrix metalloproteinases (MMPs) are the key enzymes in the pathogenesis of cartilage and joint damage and potentially a new biomarker of the early erosive form of rheumatoid arthritis (RA). Firstly, the study aimed to compare the level of MMP-9 in plasma (PL) and synovial fluid (SF) of patients with RA and osteoarthritis (OA). Secondly, the goal was to examine the association of MMP-9 level in PL and SF with early erosive changes in RA, and finally, to determine the association of MMP-9 level with serological parameters of the disease (rheumatoid factor-RF and anti-citrulline protein antibodies-ACPA). Materials and Methods: A total of 156 subjects were involved in this study (84 patients with RA and 72 patients with OA, who were involved as a control group). MMP-9 level was measured in PL and SF of all subjects by the sandwich enzyme-linked immunosorbent assay (ELISA) method. Standard radiographs of the hands and feet were used to detect joint damage and classification into erosive or non-erosive RA. The Larsen score (LS) was used for the quantitative assessment of joint damage, and its annual change (∆ LS) was used to assess the radiographic progression of the disease. Results: MMP-9 level in PL and SF was significantly higher in RA compared to controls (PL: 19.26 ± 7.54 vs. 14.57 ± 3.11 ng/mL, p< 0.01; SF: 16.17 ± 12.25 vs. 0.75 ± 0.53 ng/mL, p < 0.001) as well as in SF of patients with erosive compared to non-erosive RA (18.43 ± 12.87 vs. 9.36 ± 7.72; p < 0.05). Faster radiographic progression was recorded in erosive compared to non-erosive early RA (11.14 ± 4.75 vs. 6.13 ± 2.72; p < 0.01). MMP-9 level in SF, but not in PL, significantly correlates with the radiographic progression in both erosive and non-erosive RA (ρ = 0.38 and ρ = 0.27). We did not find a significant association between RF and MMP-9 level in early RA, but the ACPA level significantly correlates with MMP-9 level in SF (r = 0.48). Conclusion: The level of MMP-9 in plasma and synovial fluid of patients with RA is significantly higher compared to patients with osteoarthritis. The level of MMP-9 in synovial fluid is significantly higher in erosive than non-erosive early RA. It is significantly associated with the radiographic progression of the disease and the level of anti-citrulline protein antibodies.

Insights into the anticancer activity of chiral alkylidene-β-lactams and alkylidene-γ-lactams: Synthesis and biological investigation

Chiral alkylidene-β-lactams and alkylidene-γ-lactams were synthesized and screened for their in vitro activity against four human cancer cell lines (melanoma, esophageal, lung and fibrosarcoma carcinoma). Alkylidene-β-lactams were synthesized via Wittig reaction of diverse phosphorus ylides with benzhydryl 6-oxopenicillanate, derived from 6-aminopenicillanic acid. Moreover, novel chiral alkylidene-γ-lactams were synthesized through a multistep strategy starting from a chiral substrate (d-penicillamine). The in vitro assays allowed the identification of four compounds with IC₅₀ values < 10 μM for A375 cell line, and three compounds with IC₅₀ values < 10 μM for OE19 cell line. The effect of the most promising compounds on cell death mechanism, reactive oxygen species generation as well as the evaluation of their ability to act as MMP-9 inhibitors were studied. The reported results unveil the potential of alkylidene-β-lactams as anticancer agents.

The protein-protein interaction between connective tissue growth factor and annexin A2 is relevant to pannus formation in rheumatoid arthritis

Background

Connective tissue growth factor (CTGF)-induced angiogenesis is a crucial factor in rheumatoid arthritis (RA), but CTGF-interacting protein and related molecular mechanism of their interaction have not been fully elucidated.

Methods

CTGF-interacting proteins were identified through the LC-MS/MS analysis of the Co-IP products from fibroblast-like synoviocyte (FLS) lysates, and the interaction between CTGF and annexin A2 (ANXA2) was further confirmed through Co-IP and BiFC assay. The binding domain, mutant, mechanism, and angiogenesis function were assessed by homology modeling, molecular docking, MTT, cell scratch, tube formation, and chick chorioallantoic membrane (CAM) assays. Additionally, severe combined immunodeficiency (SCID) mouse co-implantation model was constructed to confirm the effect of ANXA2/CTGF-TSP1 in the process of RA in vivo.

Results

ANXA2 was identified and verified as an interaction partner of CTGF for the first time by Co-IP and LC-MS/MS analysis. Co-localization of CTGF and ANXA2 was observed in RA-FLS, and direct interaction of the TSP-1 domain of CTGF and ANXA2 was determined in HEK293T cells. The spatial conformation and stable combination of the ANXA2/CTGF-TSP1 complex were assessed by homology modeling in the biomimetic environment. The function of the ANXA2/CTGF-TSP1 complex was proved on promoting FLS proliferation, migration, and angiogenesis in vitro and deteriorating FLS invasion and joint damage in SCID mice.

Conclusions

TSP-1 is the essential domain in CTGF/ANXA2 interaction and contributes to FLS migration and pannus formation, inducing the process of RA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02656-y.

Serum matrix metalloproteinase-13 as a diagnostic biomarker for cutaneous squamous cell carcinoma

Background

A significant proportion of newly diagnosed patients with cutaneous squamous cell carcinoma (cSCC) have metastasis and eventually die of the disease, necessitating the exploration of novel biomarkers for early detection of cSCC aggressiveness, risk assessment and monitoring. Matrix metalloproteinase-13 (MMP-13) has been implicated in cSCC pathogenesis. Serum MMP-13 levels have been shown to predict survival in patients with esophageal SCC, but their diagnostic value for cSCC has not been explored.

Methods

We conducted a case-control study to examine serum MMP-13 as a biomarker for cSCC. Patients with cSCC undergoing surgical resection and health controls undergoing plastic surgery were recruited. ELISA for measurement of serum MMP-13 and immunohistochemistry for detection of tissue MMP-13 were performed, and the results were compared between the case and the control group, and among different patient groups. ROC curve analysis was performed to determine the diagnostic value of serum MMP-13 levels.

Results

The ratio of male to female, and the age between the case (n = 77) and the control group (n = 50) were not significantly different. Patients had significantly higher serum MMP-13 levels than healthy controls. Subjects with stage 3 cSCC had markedly higher serum MMP-13 levels than those with stage 1 and stage 2 cSCC. Patients with invasive cSCC had remarkably higher serum MMP-13 than those with cSCC in situ. Post-surgery serum MMP-13 measurement was done in 12 patients, and a significant MMP-13 decrease was observed after removal of cSCC. Tumor tissues had a remarkably higher level of MMP-13 than control tissues. Serum MMP-13 predicted the presence of invasive cSCC with an AUC of 0.87 (95% CI [0.78 to 0.95]) for sensitivity and specificity of 81.7 and 82.4%, respectively for a cut-off value of 290 pg/mL. Serum MMP-13 predicted lymph node involvement with an AUC of 0.94 (95% CI [0.88 to 0.99]) for sensitivity and specificity of 93.8 and 88.5%, respectively for a cut-off value of 430 pg/mL.

Conclusion

Serum MMP-13 might serve as a valuable biomarker for early detection of cSCC invasiveness and monitoring of cSCC progression.

Inflammatory factors, genetic variants, and predisposition for preterm birth

Preterm birth is a major clinical and public health challenge, with a prevalence of 11% worldwide. It is the leading cause of death in children younger than 5 years old and represents 70% of neonatal deaths and 75% of neonatal morbidity. Despite the clinical and public health significance, this condition's etiology is still unclear, and most of the cases are spontaneous. There are several known preterm birth risk factors, including inflammatory diseases and the genetic background, although the underlying molecular mechanisms are far from understood. The present review highlights the research advances on the association between inflammatory-related genes and the increased risk for preterm delivery. The most associated genetic variants are the TNFα rs1800629, the IL1α rs17561, and the IL1RN rs2234663. Moreover, many of the genes discussed in this review are also implicated in pathologies involving inflammatory or autoimmune systems, such as periodontal disease, bowel inflammatory disease, and autoimmune rheumatic diseases. This review presents evidence suggesting a common genetic background to preterm birth, autoimmune and inflammatory diseases susceptibility.

Polysaccharides from Ulva prolifera O.F. Müller inhibit cell proliferation via activating MAPK signaling in A549 and H1650 cells

Reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), have recently been reported to cause a significant increase in the production and expression of matrix metalloproteinases (MMPs), which are closely correlated with lung cancer metastasis. The aim of the present study is to determine the inhibitory effects of a polysaccharide isolated from Ulva prolifera O.F. Müller (U. prolifera) on the invasive potential of non-small cell lung cancer (NSCLC) cells, and further to explore the underlying mechanisms connected to that potential. The data showed that increased MMP-9 resulting from H2O2 exposure was mediated by activating mitogen-activated protein kinases (MAPKs). Pre-treatment with polysaccharides suppressed the activation of H2O2-mediated MAPK pathways and cell invasion. Hence, MMP-9 production triggered by H2O2 was demonstrated by activating MAPK signaling in a Myc-dependent manner. Taken together, these results suggested that polysaccharides suppress H2O2-induced cell invasion by inhibiting Myc-mediated MMP-9 gene transcription through the MAPK signaling pathway in A549 and NCI-H1650 cells. Our data also suggested that polysaccharides may be useful in minimizing the development of lung cancer metastasis. In the future, pretreatment with polysaccharides because of their antioxidant properties might be beneficial to enhance surgical outcomes.

Zinc and Cadmium in the Aetiology and Pathogenesis of Osteoarthritis and Rheumatoid Arthritis

Osteoarthritis (OA) and rheumatoid arthritis (RA) are inflammatory articular conditions with different aetiology, but both result in joint damage. The nutritionally essential metal zinc (Zn²⁺) and the non-essential metal cadmium (Cd²⁺) have roles in these arthritic diseases as effectors of the immune system, inflammation, and metabolism. Despite both metal ions being redox-inert in biology, they affect the redox balance. It has been known for decades that zinc decreases in the blood of RA patients. It is largely unknown, however, whether this change is only a manifestation of an acute phase response in inflammation or relates to altered availability of zinc in tissues and consequently requires changes of zinc in the diet. As a cofactor in over 3000 human proteins and as a signaling ion, zinc affects many pathways relevant for arthritic disease. How it affects the diseases is not just a question of zinc status, but also an issue of mutations in the many proteins that maintain cellular zinc homoeostasis, such as zinc transporters of the ZIP (Zrt-/Irt-like protein) and ZnT families and metallothioneins, and the multiple pathways that change the expression of these proteins. Cadmium interferes with zinc's functions and there is increased uptake under zinc deficiency. Remarkably, cadmium exposure through inhalation is now recognized in the activation of macrophages to a pro-inflammatory state and suggested as a trigger of a specific form of nodular RA. Here, we discuss how these metal ions participate in the genetic, metabolic, and environmental factors that lead to joint destruction. We conclude that both metal ions should be monitored routinely in arthritic disease and that there is untapped potential for prognosis and treatment.

The family history of rheumatoid arthritis in anti-cyclic citrullinated peptide antibody-positive patient is not a predictor of poor clinical presentation and treatment response with modern classification criteria and treatment strategy: the ANSWER cohort study

A family history of rheumatoid arthritis (RA) is a strong risk factor for developing RA, affecting both genetically and environmentally. However, whether family history provides clinically relevant information in the modern classification and treatment remains largely unknown. This study aimed to determine whether a family history of RA is associated with a different clinical presentation of RA and treatment response. We retrospectively evaluated the demographic data and disease activity of newly diagnosed RA patients at baseline, 1 year, and 2 years after onset, using the ANSWER (Kansai consortium for the well-being of rheumatic disease patients) cohort data. Thirty-one patients (11.9%) among 260 newly diagnosed RA patients had a family history of RA up to second degree. There was no significant difference in the age at onset, time from onset to first visit, sex, positivity or value of rheumatoid factor or anti-cyclic citrullinated peptide antibody (ACPA), or disease activity between patients with and without a family history of RA. However, patients who had a family history of RA and were ACPA positive showed significantly lower erythrocyte sedimentation rate, and C-reactive protein. Disease activity in patients with a family history was not worse at baseline, after 1 year or 2 years of treatment. The Larsen score 2 years after onset was equivalent between the patients with and without a family history of RA in ACPA-positive patients. Family history of RA in ACPA-positive patients is not associated with high disease activity at baseline and is not a predictor of poor outcome 2 years after onset.

Genetic associations with radiological damage in rheumatoid arthritis: Meta-analysis of seven genome-wide association studies of 2,775 cases

BACKGROUND

Previous studies of radiological damage in rheumatoid arthritis (RA) have used candidate-gene approaches, or evaluated single genome-wide association studies (GWAS). We undertook the first meta-analysis of GWAS of RA radiological damage to: (1) identify novel genetic loci for this trait; and (2) test previously validated variants.

METHODS

Seven GWAS (2,775 RA cases, of a range of ancestries) were combined in a meta-analysis. Radiological damage was assessed using modified Larsen scores, Sharp van Der Heijde scores, and erosive status. Single nucleotide polymophsim (SNP) associations with radiological damage were tested at a single time-point using regression models. Primary analyses included age and disease duration as covariates. Secondary analyses also included rheumatoid factor (RF). Meta-analyses were undertaken in trans-ethnic and European-only cases.

RESULTS

In the trans-ethnic primary meta-analysis, one SNP (rs112112734) in close proximity to HLA-DRB1, and strong linkage disequilibrium with the shared-epitope, attained genome-wide significance (P = 4.2x10-8). In the secondary analysis (adjusting for RF) the association was less significant (P = 1.7x10-6). In both trans-ethnic primary and secondary meta-analyses 14 regions contained SNPs with associations reaching P<5x10-6; in the European primary and secondary analyses 13 and 10 regions contained SNPs reaching P<5x10-6, respectively. Of the previously validated SNPs for radiological progression, only rs660895 (tagging HLA-DRB1*04:01) attained significance (P = 1.6x10-5) and had a consistent direction of effect across GWAS.

CONCLUSIONS

Our meta-analysis confirms the known association between the HLA-DRB1 shared epitope and RA radiological damage. The lack of replication of previously validated non-HLA markers highlights a requirement for further research to deliver clinically-useful prognostic genetic markers.

Genetic implications in the pathogenesis of rheumatoid arthritis; an updated review

Three important factors, including genetics, environment factors and autoimmunity play a role in the pathogenesis of rheumatoid arthritis (RA). The heritability of RA has been accounted to be 50-60%, while the HLA involvement in heritability of the disease has been accounted to be 10-40%. It has been documented that shared epitope (SE) alleles, such as HLA-DRB1*01 and DRB1*04, some HLA alleles like HLA-DRB1*13 and DRB1*15 are connected to RA susceptibility. An advanced classification of SE categorizes SE alleles into four main groups namely, S1, S2, S3D, and S3P. The S2 and S3P groups have been linked to susceptibility of seropositive RA. Various genome-wide association studies (GWAS) have discovered many susceptibility loci implicated in pathogenesis of RA. Some of the important single nucleotide polymorphisms (SNPs) linked to RA are TRAF1, STAT4, CTLA4, IRF5, CCR6, PTPN22, IL23R, and PADI4. HLA and non-HLA genes may discriminate anti-cyclic citrullinated peptide (anti-CCP) antibody-positive and anti-CCP-negative RA groups. Furthermore, risk of the disease has also been linked to environmental agents, mainly cigarette smoking. Pharmacogenomics has also confirmed SNPs or genetic patterns that might be linked to drugs responses. Different aspects of genetic involvement in the pathogenesis, etiology, and RA complications are reviewed in this article.

TIM family gene polymorphism and susceptibility to rheumatoid arthritis: Systematic review and meta-analysis

BACKGROUND

TIM-family proteins are expressed on different immune cells such as dendritic cells, macrophages, type 1 and 2 T helper (Th) cells. Therefore, they have the ability to contribute to the various intracellular signals and immune responses, importantly the regulation of Th1 and Th17 cell differentiation, which plays a remarked role in fight against inflammatory and autoimmune diseases. Association of TIM family gene polymorphisms with rheumatoid arthritis (RA) has been frequently investigated. The findings however are not entirely consistent. Therefore, we carried out the present meta-analysis to examine the association between RA and the following TIM family gene polymorphisms: rs41297579, rs1036199, rs10515746, and rs7700944.

METHODS

A systematic search of Scopus, PubMed, and Web of Science databases was conducted through December 2018. Combined odds ratios (OR) with their corresponding 95% confidence intervals (CI) were calculated under different possible genetic models.

RESULTS

A total of eight case-control studies were included in the present meta-analysis. The results demonstrated significant association of RA with TIM-3 rs1036199 polymorphism under dominant (OR, 1.93, 95% CI, 1.43-2.61) and allelic models (OR, 1.74, 95% CI, 1.31-2.30). None of the other examined polymorphisms indicated significant association with RA.

CONCLUSIONS

The present meta-analysis revealed that the TIM-3 rs1036199 polymorphism might confer susceptibility to RA. Further studies are required to reassert our findings.

Potential Novel Prediction of TMJ-OA: MiR-140-5p Regulates Inflammation Through Smad/TGF-β Signaling

Temporomandibular joint osteoarthritis (TMJ-OA), mainly exhibit extracellular matrix loss and condylar cartilage degradation, is the most common chronic and degenerative maxillofacial osteoarthritis; however, no efficient therapy for TMJ-OA exists due to the poor understanding of its pathological progression. MicroRNA (miR)-140-5p is a novel non-coding microRNAs (miRNAs) that expressed in osteoarthritis specifically. To investigate the molecular mechanisms of miR-140-5p in TMJ-OA, primary mandibular condylar chondrocytes (MCCs) from C57BL/6N mice were treated with interleukins (IL)-1β or transfected with miR-140-5p mimics or inhibitors, respectively. The expression of matrix metallopeptidase (MMP)-13, miR-140-5p, nuclear factor (NF)-kB, Smad3 and transforming growth factor (TGF)-β3 were examined by western blotting or quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The interaction between the potential binding sequence of miR-140-5p and the 3'-untranslated region (3'UTR) of Smad3 mRNA was testified by dual-luciferase assay. Small Interfering RNA of Smad3 (Si-Smad3) was utilized to further identify the role of Smad3 mediated by miR-140-5p. The data showed MMP13, miR-140-5p and NF-kB increased significantly in response to IL-1β inflammatory response in MCCs, meanwhile, Smad3 and TGF-β3 reduced markedly. Moreover, transfection of miR-140-5p mimics significantly suppressed the expression of Smad3 and TGF-β3 in MCCs, while miR-140-5p inhibitors acted in a converse manner. As the luciferase reporter of Smad3 mRNA observed active interaction with miR-140-5p, Smad3 was identified as a direct target of miR-140-5p. Additionally, the expression of TGF-β3 was regulated upon the activation of Smad3. Together, these data suggested that miR-140-5p may play a role in regulating mandibular condylar cartilage homeostasis and potentially serve as a novel prognostic factor of TMJ-OA-like pathology.

A noncanonical role for the engulfment gene ELMO1 in neutrophils that promotes inflammatory arthritis

Rheumatoid arthritis is characterized by progressive joint inflammation and affects ~1% of the human population. We noted single nucleotide polymorphisms (SNPs) in the apoptotic cell engulfment genes ELMO1, DOCK2, and RAC1 linked to rheumatoid arthritis. As ELMO1 promotes cytoskeletal reorganization during engulfment, we hypothesized that ELMO1 loss would worsen inflammatory arthritis. Surprisingly, Elmo1-deficient mice showed reduced joint inflammation in acute and chronic arthritis models. Genetic and cell biological studies revealed that ELMO1 associates with receptors linked to neutrophil function in arthritis and regulates activation and early neutrophil recruitment to the joints, without general inhibition of inflammatory responses. Further, neutrophils from peripheral blood of human donors that carry the SNP in ELMO1 associated with arthritis display increased migratory capacity, whereas ELMO1 knockdown reduces human neutrophil migration to chemokines linked to arthritis. These data identify ‘non-canonical’ roles for ELMO1 as an important cytoplasmic regulator of specific neutrophil receptors and promoter of arthritis.

Matrix Metalloproteinase-9 (MMP-9) as a Cancer Biomarker and MMP-9 Biosensors: Recent Advances

As one of the most widely investigated matrix metalloproteinases (MMPs), MMP-9 is a significant protease which plays vital roles in many biological processes. MMP-9 can cleave many extracellular matrix (ECM) proteins to regulate ECM remodeling. It can also cleave many plasma surface proteins to release them from the cell surface. MMP-9 has been widely found to relate to the pathology of cancers, including but not limited to invasion, metastasis and angiogenesis. Some recent research evaluated the value of MMP-9 as biomarkers to various specific cancers. Besides, recent research of MMP-9 biosensors discovered various novel MMP-9 biosensors to detect this enzyme. In this review, some recent advances in exploring MMP-9 as a biomarker in different cancers are summarized, and recent discoveries of novel MMP-9 biosensors are also presented.

PheWAS and Beyond: The Landscape of Associations with Medical Diagnoses and Clinical Measures across 38,662 Individuals from Geisinger

Most phenome-wide association studies (PheWASs) to date have used a small to moderate number of SNPs for association with phenotypic data. We performed a large-scale single-cohort PheWAS, using electronic health record (EHR)-derived case-control status for 541 diagnoses using International Classification of Disease version 9 (ICD-9) codes and 25 median clinical laboratory measures. We calculated associations between these diagnoses and traits with ∼630,000 common frequency SNPs with minor allele frequency > 0.01 for 38,662 individuals. In this landscape PheWAS, we explored results within diseases and traits, comparing results to those previously reported in genome-wide association studies (GWASs), as well as previously published PheWASs. We further leveraged the context of functional impact from protein-coding to regulatory regions, providing a deeper interpretation of these associations. The comprehensive nature of this PheWAS allows for novel hypothesis generation, the identification of phenotypes for further study for future phenotypic algorithm development, and identification of cross-phenotype associations.

Are programmed cell death 1 gene polymorphisms correlated with susceptibility to rheumatoid arthritis?: A meta-analysis

BACKGROUND

Several studies investigated the relationship between programmed cell death 1 (PDCD1) gene polymorphisms and rheumatoid arthritis (RA) risk, but the results were controversial. To explore whether PDCD1 gene polymorphisms have an effect on RA risk, we conducted this meta-analysis to investigate the relationships between PDCD1 polymorphisms (rs36084323 [PD-1.1 G/A], rs11568821 [PD-1.3 G/A] and rs2227981 [PD-1.5 C/T]) and RA risk under 4 genetic models.

METHODS

PubMed, EMBASE, Web of Science, Cochrane Library China National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature Database (CBLM) were systematically searched for all eligible case-control studies. The last search was updated on September 10, 2016. Studies were accessed using Newcastle-Ottawa Scale case control study (NOS), and the combined effect size was calculated using STATA software, version 12.0. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated to assess the association. Heterogeneity analysis and subgroup analysis were also performed. Sensitivity analysis and publication bias were also performed if necessary.

RESULTS

This meta-analysis included 6 studies. The result demonstrated null association between rs36084323 (PD-1.1 G/A) polymorphism and RA susceptibility in all 4 genetic models. With regard to rs11568821 (PD-1.3 G/A), statistically significant association with RA risk was observed under allele model in Caucasians (allele model A vs G, OR = 1.19, 95% CI = 1.03-1.41). There was no significant association between rs2227981 (PD-1.5 C/T) polymorphism and RA risk.

CONCLUSION

The present study suggests that mutant A allele in rs11568821 (PD-1.3 G/A) might increase the susceptibility to RA in Caucasians.

Association Between Genetic Variation in FOXO3 and Reductions in Inflammation and Disease Activity in Inflammatory Polyarthritis

Objective

Genetic variation in FOXO3 (tagged by rs12212067) has been associated with a milder course of rheumatoid arthritis (RA) and shown to limit monocyte‐driven inflammation through a transforming growth factor β1–dependent pathway. This genetic association, however, has not been consistently observed in other RA cohorts. We sought to clarify the contribution of FOXO3 to prognosis in RA by combining detailed analysis of nonradiographic disease severity measures with an in vivo model of arthritis.

Methods

Collagen‐induced arthritis, the most commonly used mouse model of RA, was used to assess how Foxo3 contributes to arthritis severity. Using clinical, serologic, and biochemical methods, the arthritis that developed in mice carrying a loss‐of‐function mutation in Foxo3 was compared with that which occurred in littermate controls. The association of rs12212067 with nonradiographic measures of RA severity, including the C‐reactive protein level, the swollen joint count, the tender joint count, the Disease Activity Score in 28 joints, and the Health Assessment Questionnaire score, were modeled longitudinally in a large prospective cohort of patients with early RA.

Results

Loss of Foxo3 function resulted in more severe arthritis in vivo (both clinically and histologically) and was associated with higher titers of anticollagen antibodies and interleukin‐6 in the blood. Similarly, rs12212067 (a single‐nucleotide polymorphism that increases FOXO3 transcription) was associated with reduced inflammation, both biochemically and clinically, and with lower RA activity scores.

Conclusion

Consistent with its known role in restraining inflammatory responses, FOXO3 limits the severity of in vivo arthritis and, through genetic variation that increases its transcription, is associated with reduced inflammation and disease activity in RA patients, effects that result in less radiographic damage.

Genetics of rheumatoid arthritis susceptibility, severity, and treatment response

A decade after the first genome-wide association study in rheumatoid arthritis (RA), a plethora of genetic association studies have been published on RA and its clinical or serological subtypes. We review the major milestones in the study of the genetic architecture of RA susceptibility, severity, and response to treatment. We set the scientific context necessary for non-geneticists to understand the potential clinical applications of human genetics and its significance for a stratified approach to the management of RA in the future.

S-propargyl-cysteine attenuates inflammatory response in rheumatoid arthritis by modulating the Nrf2-ARE signaling pathway

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder. Hydrogen sulfide (H₂S), the third physiological gasotransmitter, is well recognized as an anti-inflammatory mediator in various inflammatory conditions. Herein, we explored the protective effects of S-propargyl-cysteine (SPRC, also known as ZYZ-802), an endogenous H₂S modulator, on RA and determined the underlying mechanisms. In the present study, SPRC concentration-dependently attenuated inflammatory mediator expression, reactive oxidase species generation, and the expression and activity of matrix metalloproteinases (MMP)-9 in interleukin (IL)-1β-induced human rheumatoid fibroblast-like synoviocytes MH7A. In addition, SPRC blocked IL-1β-mediated migration and invasion of MH7A cells. As expected, the protective effects of SPRC were partially abrogated by DL-propargylglycine (PAG, a H₂S biosynthesis inhibitor). In vivo study also demonstrated that SPRC treatment markedly ameliorated the severity of RA in adjuvant-induced arthritis rats, and this effect was associated with the inhibition of inflammatory response. We further identified that SPRC remarkably induced heme oxygenase-1 expression associated with the degradation of Kelch-like ECH-associated protein 1 (Keap1) and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2); this effect was attributed to the sulfhydrylation of the cysteine residue of Keap1. Our data demonstrated for the first time that SPRC, an endogenous H₂S modulator, exerted anti-inflammatory properties in RA by upregulating the Nrf2-antioxidant response element (ARE) signaling pathway.

Recent Advances in Defining the Genetic Basis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory arthritis and exhibits genetic overlap with other autoimmune and inflammatory disorders. Although predominant associations with the HLA-DRB1 locus have been known for decades, recent data have revealed additional insight into the likely causative variants within HLA-DRB1 as well as within other HLA loci that contribute to disease risk. In addition, more than 100 common variants in non-HLA loci have been implicated in disease susceptibility. Genetic factors are involved not only in the development of RA, but also with various disease subphenotypes, including production and circulating levels of autoantibodies and joint destruction. The major current challenge is to integrate these new data into a precise understanding of disease pathogenesis, including the critical cell types and molecular networks involved as well as interactions with environmental factors. We predict that delineating the functional effects of genetic variants is likely to drive new diagnostic and therapeutic approaches to the disease.

Roads Less Traveled: Sexual Dimorphism and Mast Cell Contributions to Migraine Pathology

Migraine is a common, little understood, and debilitating disease. It is much more prominent in women than in men (~2/3 are women) but the reasons for female preponderance are not clear. Migraineurs frequently experience severe comorbidities, such as allergies, depression, irritable bowel syndrome, and others; many of the comorbidities are more common in females. Current treatments for migraine are not gender specific, and rarely are migraine and its comorbidities considered and treated by the same specialist. Thus, migraine treatments represent a huge unmet medical need, which will only be addressed with greater understanding of its underlying pathophysiology. We discuss the current knowledge about sex differences in migraine and its comorbidities, and focus on the potential role of mast cells (MCs) in both. Sex-based differences in pain recognition and drug responses, fluid balance, and the blood–brain barrier are recognized but their impact on migraine is not well studied. Furthermore, MCs are well recognized for their prominent role in allergies but much less is known about their contributions to pain pathways in general and migraine specifically. MC-neuron bidirectional communication uniquely positions these cells as potential initiators and/or perpetuators of pain. MCs can secrete nociceptor sensitizing and activating agents, such as serotonin, prostaglandins, histamine, and proteolytic enzymes that can also activate the pain-mediating transient receptor potential vanilloid channels. MCs express receptors for both estrogen and progesterone that induce degranulation upon binding. Furthermore, environmental estrogens, such as Bisphenol A, activate MCs in preclinical models but their impact on pain pathways or migraine is understudied. We hope that this discussion will encourage scientists and physicians alike to bridge the knowledge gaps linking sex, MCs, and migraine to develop better, more comprehensive treatments for migraine patients.

Genetic data: The new challenge of personalized medicine, insights for rheumatoid arthritis patients

Rapid advances in genotyping technology, analytical methods, and the establishment of large cohorts for population genetic studies have resulted in a large new body of information about the genetic basis of human rheumatoid arthritis (RA). Improved understanding of the root pathogenesis of the disease holds the promise of improved diagnostic and prognostic tools based upon this information. In this review, we summarize the nature of new genetic findings in human RA, including susceptibility loci and gene-gene and gene-environment interactions, as well as genetic loci associated with sub-groups of patients and those associated with response to therapy. Possible uses of these data are discussed, such as prediction of disease risk as well as personalized therapy and prediction of therapeutic response and risk of adverse events. While these applications are largely not refined to the point of clinical utility in RA, it seems likely that multi-parameter datasets including genetic, clinical, and biomarker data will be employed in the future care of RA patients.

Genetic Variants Influencing Joint Damage in Mexican Americans and European Americans With Rheumatoid Arthritis

Joint destruction in rheumatoid arthritis (RA) is heritable, but knowledge on specific genetic determinants of joint damage in RA is limited. We have used the Immunochip array to examine whether genetic variants influence variation in joint damage in a cohort of Mexican Americans (MA) and European Americans (EA) with RA. We studied 720 MA and 424 EA patients with RA. Joint damage was quantified using a radiograph of both hands and wrists, scored using Sharp's technique. We conducted association analyses with the transformed Sharp score and the Immunochip single nucleotide polymorphism (SNP) data using PLINK. In MAs, 15 SNPs from chromosomes 1, 5, 9, 17 and 22 associated with joint damage yielded strong p-values (p < 1 × 10(-4) ). The strongest association with joint damage was observed with rs7216796, an intronic SNP located in the MAP3K14 gene, on chromosome 17 (β ± SE = -0.25 ± 0.05, p = 6.23 × 10(-6) ). In EAs, 28 SNPs from chromosomes 1, 4, 6, 9, and 21 showed associations with joint damage (p-value < 1 × 10(-4) ). The best association was observed on chromosome 9 with rs59902911 (β ± SE = 0.86 ± 0.17, p = 1.01 × 10(-6) ), a synonymous SNP within the CARD9 gene. We also observed suggestive evidence for some loci influencing joint damage in MAs and EAs. We identified two novel independent loci (MAP3K14 and CARD9) strongly associated with joint damage in MAs and EAs and a few shared loci showing suggestive evidence for association.

Regulation of mouse chondrocyte differentiation by CCAAT/enhancer-binding proteins

CCAAT/enhancer-binding protein (C/EBP) β regulates chondrocyte differentiaion and proliferation during endochondral ossification. However, expression and function of other C/EBP family members in chondrocytes have not been fully understood. To understand the comprehensive regulation of chondrocyte differentiation by C/EBPs, we initially examined their expression levels. Among four members (C/EBPα, C/EBPβ, C/EBPδ and C/EBPε) with transactivation domain, expression of Cebpb and Cebpd was abundant compared to Cebpa, while Cebpe was hardly expressed in mouse isolated chondrocytes. Doxycycline (DOX)-inducible overexpression of each of the three C/EBPs (C/EBPα, C/EBPβ and C/EBPδ) in ATDC5 cells suppressed expressions of early differentiation markers including Col2a1, aggrecan and Sox9, enhanced those of late differentiation markers including Mmp13, Vegfa and Col10a1, and decelerated cell proliferation, indicating their overlapped functions in chondrocytes. In contrast, DOX-inducible overexpression of A-CEBP, which exerts a dominant-negative effect against all C/EBPs, increased expressions of early differentiation markers and decreased those of late differentiation markers. Finally, microarray and gene ontology analyses showed that A-CEBP altered many genes related with various events or tissues such as skeletal development, cartilage, cell cycle, inflammation and apoptosis. In conclusion, C/EBPα, C/EBPβ and C/EBPδ regulate proliferation and differentiation of chondrocytes and possibly is involved with apoptosis and inflammation. C/EBPs may play a variety of roles in the homeostasis of joint cartilage under physiological and pathological conditions.

PTGER4 gene variant rs76523431 is a candidate risk factor for radiological joint damage in rheumatoid arthritis patients: a genetic study of six cohorts

Introduction

Prostaglandin E receptor 4 (PTGER4) is implicated in immune regulation and bone metabolism. The aim of this study was to analyze its role in radiological joint damage in rheumatoid arthritis (RA).

Methods

Six independent cohorts of patients with RA of European or North American descent were included, comprising 1789 patients with 5083 sets of X-rays. The Hospital Clínico San Carlos Rheumatoid Arthritis, Princesa Early Arthritis Register Longitudinal study, and Hospital Universitario de La Paz early arthritis (Spain) cohorts were used as discovery cohorts, and the Leiden Early Arthritis Clinic (The Netherlands), Wichita (United States), and National Databank for Rheumatic Diseases (United States and Canada) cohorts as replication cohorts. First, the PTGER4 rs6896969 single-nucleotide polymorphism (SNP) was genotyped using TaqMan assays and available Illumina Immunochip data and studied in the discovery and replication cohorts. Second, the PTGER4 gene and adjacent regions were analyzed using Immunochip genotyping data in the discovery cohorts. On the basis of pooled p values, linkage disequilibrium structure of the region, and location in regions with transcriptional properties, SNPs were selected for replication. The results from discovery, replication, and overall cohorts were pooled using inverse-variance–weighted meta-analysis. Influence of the polymorphisms on the overall radiological damage (constant effect) and on damage progression over time (time-varying effect) was analyzed.

Results

The rs6896969 polymorphism showed a significant association with radiological damage in the constant effect pooled analysis of the discovery cohorts, although no significant association was observed in the replication cohorts or the overall pooled analysis. Regarding the analysis of the PTGER4 region, 976 variants were analyzed in the discovery cohorts. From the constant and time-varying effect analyses, 12 and 20 SNPs, respectively, were selected for replication. Only the rs76523431 variant showed a significant association with radiographic progression in the time-varying effect pooled analysis of the discovery, replication, and overall cohorts. The overall pooled effect size was 1.10 (95 % confidence interval 1.05–1.14, p = 2.10 × 10⁻⁵), meaning that radiographic yearly progression was 10 % greater for each copy of the minor allele.

Conclusions

The PTGER4 gene is a candidate risk factor for radiological progression in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0830-z) contains supplementary material, which is available to authorized users.

IL2RA is associated with persistence of rheumatoid arthritis

INTRODUCTION

Although rheumatoid arthritis (RA) is generally a chronic disease, a proportion of RA-patients achieve disease-modifying antirheumatic drug (DMARD)-free sustained remission, reflecting loss of disease-persistence. To explore mechanisms underlying RA-persistence, we performed a candidate gene study. We hypothesized that variants associating with lack of radiographic progression also associate with DMARD-free sustained remission.

METHODS

645 Dutch RA-patients were studied on DMARD-free sustained remission during a maximal follow-up duration of 10-years. Variants associated with radiographic progression under an additive model in the total RA-population (Human Leukocyte Antigens (HLA)-DRB1-shared epitope (SE), Dickkopf-1 (DKK1)-rs1896368, DKK1-rs1896367, DKK1-rs1528873, C5Orf30-rs26232, Interleukin-2 receptor-α (IL2RA)-rs2104286, Matrix metalloproteinase-9 (MMP-9)-rs11908352, rs451066 and Osteoprotegerin (OPG)-rs1485305) were studied. Cox-regression analyses were performed and Bonferroni correction applied. Soluble IL2Rα (sIL2Rα)-levels were studied. For replication, 622 RA-patients included in the French Evaluation et Suivi de POlyarthrites Indifférenciées Récentes cohort (ESPOIR)-cohort were investigated. Results were combined in inverse-variance weighted meta-analysis.

RESULTS

Similar as previously reported, the SE-alleles associated with less remission (hazard ratio (HR) = 0.57, 95 % confidence interval (95 % CI) = 0.42-0.77, p = 2.72×10(-4)). Variants in DKK-1, C5orf30, MMP-9 and OPG were not associated with remission. The IL2RA-rs2104286 minor allele associated with a higher chance on remission (HR = 1.52, 95 % CI = 1.16-1.99, p = 2.44×10(-3)). The rs2104286 minor allele associated with lower sIL2Rα-levels (p = 1.44×10(-3)); lower sIL2Rα-levels associated with a higher chance on remission (HR per 100 pg/L = 0.81, 95 % CI = 0.68-0.95, p = 0.012). When including rs2104286 and sIL2Rα-levels in one analysis, the HR for rs2104286 was 2.27 (95 % CI = 1.06-4.84, p = 0.034) and for sIL2Rα 0.83 (95 % CI = 0.70-0.98, p = 0.026). Within ESPOIR, the HR of rs2104286 was 1.31 (95 % CI = 0.90-1.90). The meta-analysis revealed a p-value of 1.01×10(-3).

CONCLUSION

IL2RA-rs2104286 and sIL2Rα-level associated with RA-persistence. IL2RA variants are known to protect against multiple sclerosis, diabetes mellitus and RA. Besides HLA-SE, IL2RA-rs2104286 is thus far the only known genetic variant associated with both joint destruction and RA-persistence. This underlines the relevance of IL2RA for RA.

Association of valine and leucine at HLA-DRB1 position 11 with radiographic progression in rheumatoid arthritis, independent of the shared epitope alleles but not independent of anti-citrullinated protein antibodies

OBJECTIVE

For decades it has been known that the HLA-DRB1 shared epitope (SE) alleles are associated with an increased risk of development and progression of rheumatoid arthritis (RA). Recently, the following variations in the peptide-binding grooves of HLA molecules that predispose to RA development have been identified: Val and Leu at HLA-DRB1 position 11, Asp at HLA-B position 9, and Phe at HLA-DPB1 position 9. This study was undertaken to investigate whether these variants are also associated with radiographic progression in RA, independent of SE and anti-citrullinated protein antibody (ACPA) status.

METHODS

A total of 4,911 radiograph sets from 1,878 RA patients included in the Leiden Early Arthritis Clinic (The Netherlands), Umeå (Sweden), Hospital Clinico San Carlos-Rheumatoid Arthritis (Spain), and National Data Bank for Rheumatic Diseases (US) cohorts were studied. HLA was imputed using single-nucleotide polymorphism data from an Immunochip, and the amino acids listed above were tested in relation to radiographic progression per cohort using an additive model. Results from the 4 cohorts were combined in inverse-variance weighted meta-analyses using a fixed-effects model. Analyses were conditioned on SE and ACPA status.

RESULTS

Val and Leu at HLA-DRB1 position 11 were associated with more radiographic progression (meta-analysis P = 5.11 × 10(-7)); this effect was independent of SE status (meta-analysis P = 0.022) but not independent of ACPA status. Phe at HLA-DPB1 position 9 was associated with more severe radiographic progression (meta-analysis P = 0.024), though not independent of SE status. Asp at HLA-B position 9 was not associated with radiographic progression.

CONCLUSION

Val and Leu at HLA-DRB1 position 11 conferred a risk of a higher rate of radiographic progression independent of SE status but not independent of ACPA status. These findings support the relevance of these amino acids at position 11.

Do Genetic Susceptibility Variants Associate with Disease Severity in Early Active Rheumatoid Arthritis?

OBJECTIVE

Genetic variants affect both the development and severity of rheumatoid arthritis (RA). Recent studies have expanded the number of RA susceptibility variants. We tested the hypothesis that these associated with disease severity in a clinical trial cohort of patients with early, active RA.

METHODS

We evaluated 524 patients with RA enrolled in the Combination Anti-Rheumatic Drugs in Early RA (CARDERA) trials. We tested validated susceptibility variants - 69 single-nucleotide polymorphisms (SNP), 15 HLA-DRB1 alleles, and amino acid polymorphisms in 6 HLA molecule positions - for their associations with progression in Larsen scoring, 28-joint Disease Activity Scores, and Health Assessment Questionnaire (HAQ) scores over 2 years using linear mixed-effects and latent growth curve models.

RESULTS

HLA variants were associated with joint destruction. The *04:01 SNP (rs660895, p = 0.0003), *04:01 allele (p = 0.0002), and HLA-DRβ1 amino acids histidine at position 13 (p = 0.0005) and valine at position 11 (p = 0.0012) significantly associated with radiological progression. This association was only significant in anticitrullinated protein antibody (ACPA)-positive patients, suggesting that while their effects were not mediated by ACPA, they only predicted joint damage in ACPA-positive RA. Non-HLA variants did not associate with radiograph damage (assessed individually and cumulatively as a weighted genetic risk score). Two SNP - rs11889341 (STAT4, p = 0.0001) and rs653178 (SH2B3-PTPN11, p = 0.0004) - associated with HAQ scores over 6-24 months.

CONCLUSION

HLA susceptibility variants play an important role in determining radiological progression in early, active ACPA-positive RA. Genome-wide and HLA-wide analyses across large populations are required to better characterize the genetic architecture of radiological progression in RA.

Functional polymorphisms in the promoter region of MMP-2 and MMP-9 and susceptibility to obstructive sleep apnea

Genetic susceptibility to obstructive sleep apnea (OSA) has been a research focus in the scientific community in the past few years. In this study, we recruited 375 subjects to investigate whether functional polymorphisms in the promoter region of matrix metalloproteinase (MMP)-2 (-1306C/T) and MMP-9 (-1562C/T) increased susceptibility to OSA. Our study showed no significant association between MMP-2 -1306C/T polymorphism and risk of OSA (T vs. C: OR = 1.01, 95% CI = 0.67-1.52; P = 0.97). Compared with the MMP-9 -1562C allele, the -1562T allele was associated with increased risk of OSA (T vs. C: OR = 1.56, 95% CI = 1.02-2.39; P = 0.04). However, neither MMP-2 -1306C/T nor MMP-9 -1562C/T polymorphism was found to be associated with severity of the disease. Our study suggested that the MMP-2 -1306C/T polymorphism was not associated with OSA susceptibility, whereas the MMP-9 -1562T allele was associated with increased risk of OSA.

A genetic study on C5-TRAF1 and progression of joint damage in rheumatoid arthritis

Introduction

The severity of joint damage progression in rheumatoid arthritis (RA) is heritable. Several genetic variants have been identified, but together explain only part of the total genetic effect. Variants in Interleukin-6 (IL-6), Interleukin-10 (IL-10), C5-TRAF1, and Fc-receptor-like-3 (FCRL3) have been described to associate with radiographic progression, but results of different studies were incongruent. We aimed to clarify associations of these variants with radiographic progression by evaluating six independent cohorts.

Methods

In total 5,895 sets of radiographs of 2,493 RA-patients included in six different independent datasets from the Netherlands, Sweden, Spain and North-America were studied in relation to rs1800795 (IL-6), rs1800896 (IL-10), rs2900180 (C5-TRAF1) and rs7528684 (FCRL3). Associations were tested in the total RA-populations and in anti-citrullinated peptide antibodies (ACPA)-positive and ACPA-negative subgroups per cohort, followed by meta-analyses. Furthermore, the associated region C5-TRAF1 was fine-mapped in the ACPA-negative Dutch RA-patients.

Results

No associations were found for rs1800795 (IL-6), rs1800896 (IL-10) and rs7528684 (FCRL3) in the total RA-population and after stratification for ACPA. Rs2900180 in C5-TRAF1 was associated with radiographic progression in the ACPA-negative population (P-value meta-analysis = 5.85 × 10⁻⁷); the minor allele was associated with more radiographic progression. Fine-mapping revealed a region of 66Kb that was associated; the lowest P-value was for rs7021880 in TRAF1. The P-value for rs7021880 in meta-analysis was 6.35 × 10⁻⁸. Previous studies indicate that the region of rs7021880 was associated with RNA expression of TRAF1 and C5.

Conclusion

Variants in IL-6, IL-10 and FCRL3 were not associated with radiographic progression. Rs2900180 in C5-TRAF1 and linked variants in a 66Kb region were associated with radiographic progression in ACPA-negative RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0514-0) contains supplementary material, which is available to authorized users.

Genetic basis of rheumatoid arthritis: a current review

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases. As with other complex traits, genome-wide association studies (GWASs) have tremendously enhanced our understanding of the complex etiology of RA. In this review, we describe the genetic architecture of RA as determined through GWASs and meta-analyses. In addition, we discuss the pathologic mechanism of the disease by examining the combined findings of genetic and functional studies of individual RA-associated genes, including HLA-DRB1, PADI4, PTPN22, TNFAIP3, STAT4, and CCR6. Moreover, we briefly examine the potential use of genetic data in clinical practice in RA treatment, which represents a challenge in medical genetics in the post-GWAS era.

SPP1 rs9138 variant contributes to the severity of radiological damage in anti-citrullinated protein autoantibody-negative rheumatoid arthritis

OBJECTIVE

We recently reported an association of the SPP1 rs9138 and rs11439060 functional variants with the risk of rheumatoid arthritis (RA), the association being greater in anti-citrullinated protein autoantibody (ACPA)-negative patients. We hypothesised that SPP1 may contribute to the severity of joint destruction in RA, specifically in the ACPA-negative population.

METHODS

Patients with RA in the ESPOIR cohort underwent genotyping for SPP1 rs9138 and rs11439060. Radiographs of the hands and feet were obtained at the first visit and at 1- and 2-year follow-up. Association analyses were performed by ACPA status. A replication study of the relevant subset of the Leiden Early Arthritis Clinic (EAC) cohort was performed.

RESULTS

In the ESPOIR cohort (652 patients), rs9138 was significantly associated with radiological progression of joint destruction at 2 years, the association being restricted to 358 ACPA-negative patients (p=0.034). In the replication study with the Leiden EAC cohort (273 ACPA-negative patients), rs4754, which is in complete linkage disequilibrium with rs9138, was significantly associated with joint damage progression in ACPA-negative patients at 2- and 7-year follow-up (p=0.019 and p=0.005, respectively). Combined analysis of the two cohorts revealed a 0.95-fold rate of joint destruction per year per minor allele (p=0.022).

CONCLUSIONS

The SPP1 rs9138 variant contributes to joint damage progression in ACPA-negative RA.