Antibody levels correlate with creatine kinase levels and strength in anti–3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase–associated autoimmune myopathy

Objective

Autoantibodies recognizing 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) are found in patients with statin‐associated immune‐mediated necrotizing myopathy and, less commonly, in statin‐unexposed patients with autoimmune myopathy. The main objective of this study was to define the association of anti‐HMGCR antibody levels with disease activity.

Methods

Anti‐HMGCR levels, creatine kinase (CK) levels, and strength were assessed in anti‐HMGCR–positive patients. Associations of antibody level with CK level and strength at visit 1 were analyzed in 55 patients, 40 of whom were exposed to statins. In 12 statin‐exposed and 5 statin‐unexposed patients with serum from 5 serial visits, the evolution of antibody levels, CK levels, and strength was investigated.

Results

Antibody levels were associated with CK levels (P < 0.001), arm strength (P < 0.05), and leg strength (P < 0.05) at visit 1, but these associations were only significant among statin‐exposed patients in stratified analyses. With immunosuppressive treatment over 26.2 ± 12.6 months (mean ± SD), antibody levels declined (P < 0.05) and arm abduction strength improved (P < 0.05) in the 17 patients followed up longitudinally. The separate analysis showed that statin‐exposed patients developed decreased antibody levels (P < 0.01), decreased CK levels (P < 0.001), improved arm strength (P < 0.05), and improved hip flexion strength (P < 0.05) with treatment. Anti‐HMGCR antibody levels did not normalize in any patient.

Conclusion

In the entire cohort, initial anti‐HMGCR levels correlated with indicators of disease activity; with immunosuppressive treatment, antibody levels declined and arm strength improved. Statin‐exposed patients had significant improvements in CK levels and strength whereas statin‐unexposed patients did not, suggesting a phenotypic difference between statin‐exposed and statin‐unexposed anti‐HMGCR–positive patients.

     

Autoantibodies against 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase in patients with statin‐associated autoimmune myopathy

Objective

In addition to inducing a self‐limited myopathy, statin use is associated with an immune‐mediated necrotizing myopathy (IMNM), with autoantibodies that recognize ∼200‐kd and ∼100‐kd autoantigens. The purpose of this study was to identify these molecules to help clarify the disease mechanism and facilitate diagnosis.

Methods

The effect of statin treatment on autoantigen expression was addressed by immunoprecipitation using sera from patients. The identity of the ∼100‐kd autoantigen was confirmed by immunoprecipitation of in vitro–translated 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) protein. HMGCR expression in muscle was analyzed by immunofluorescence. A cohort of myopathy patients was screened for anti‐HMGCR autoantibodies by enzyme‐linked immunosorbent assay and genotyped for the rs4149056 C allele, a predictor of self‐limited statin myopathy.

Results

Statin exposure induced expression of the ∼200‐kd/∼100‐kd autoantigens in cultured cells. HMGCR was identified as the ∼100‐kd autoantigen. Competition experiments demonstrated no distinct autoantibodies recognizing the ∼200‐kd protein. In muscle biopsy tissues from anti‐HMGCR–positive patients, HMGCR expression was up‐regulated in cells expressing neural cell adhesion molecule, a marker of muscle regeneration. Anti‐HMGCR autoantibodies were found in 45 of 750 patients presenting to the Johns Hopkins Myositis Center (6%). Among patients ages 50 years and older, 92.3% had taken statins. The prevalence of the rs4149056 C allele was not increased in patients with anti‐HMGCR.

Conclusion

Statins up‐regulate the expression of HMGCR, the major target of autoantibodies in statin‐associated IMNM. Regenerating muscle cells express high levels of HMGCR, which may sustain the immune response even after statins are discontinued. These studies demonstrate a mechanistic link between an environmental trigger and the development of sustained autoimmunity. Detection of anti‐HMGCR autoantibodies may facilitate diagnosis and direct therapy.

     

Chronic periaortitis and HLA–DRB1*03: Another clue to an autoimmune origin

Objective

Patients with chronic periaortitis (CP) often show clinical and laboratory findings of a systemic autoimmune disorder. The aim of the present study was to investigate the role of the HLA system in CP.

Methods

Low‐resolution genotyping for HLA–A, HLA–B, and HLA–DRB1 loci and genotyping of TNFA(‐238)A/G and TNFA(‐308)A/G single nucleotide polymorphisms were performed in 35 consecutive patients with CP and 350 healthy controls.

Results

The HLA–DRB1*03 allele frequency was strikingly higher in patients with CP than in controls (24.28% versus 9.14%; χ² = 15.50, P = 0.000084, corrected P [P_corr] = 0.0012, odds ratio [OR] 3.187, 95% confidence interval [95% CI] 1.74–5.83); the HLA–B*08 allele frequency was also higher in patients than in controls (17.14% versus 6.28%; χ²=11.12, P = 0.0008, P_corr = 0.0269, OR 3.085, 95% CI 1.54–6.16). The A*01 allele frequency was significantly different (P = 0.0463), but the statistical significance was lost after correction for multiple testing (P_corr = 0.5088). TNFA(‐238)A allele and TNFA(‐308)A allele frequencies were not significantly different (P = 0.512 and P = 0.445, respectively). Comparison of the main clinical and laboratory findings suggestive of a systemic autoimmune disease (e.g., acute‐phase reactants, constitutional symptoms, other autoimmune diseases associated with CP) between the HLA–DRB1*03–positive and the HLA–DRB1*03–negative patients showed that the former group had significantly higher levels of C‐reactive protein (P = 0.045) at disease onset, although this difference was not statistically significant after correction for multiple tests (P_corr = 0.369).

Conclusion

The HLA system plays a role in susceptibility to CP. The strong association between CP and HLA–DRB1*03, an allele linked to a wide range of autoimmune conditions, further supports the view that CP may represent a clinical manifestation of an autoimmune disease.

     

Increased susceptibility to rheumatoid arthritis in Koreans heterozygous for HLA–DRB1*0405 and *0901

Objective

To investigate the association of susceptibility and protective HLA–DRB1 alleles with rheumatoid arthritis (RA) and its clinical markers in an Asian population.

Methods

All RA patients (n = 574) and control subjects (n = 392) were Korean. HLA–DRB1 typing and further subtyping of all alleles was performed by polymerase chain reaction, sequence‐specific oligonucleotide probe hybridization, and direct DNA sequencing analysis. We used a relative predispositional effects (RPEs) method and a false discovery rate correction method for multiple comparisons.

Results

The DRB1*0405 and *0901 alleles showed the most significant associations with RA (P = 7.83 × 10⁻²⁴, odds ratio [OR] 4.40 [95% confidence interval (95% CI) 3.24–5.99], and P = 3.76 × 10⁻⁹, OR 2.47 [95% CI 1.82–3.36], respectively). The RPEs test showed that the DRB1*0401 and *0410 alleles conferred susceptibility and that the DRB1*0701, *0802, *1301, *1302, *1403, and *1405 alleles showed significant protective effects. Susceptibility and protective alleles both showed a pattern consistent with additive genetic effects, and each influenced RA independently of the other. The compound heterozygote DRB1*0405/*0901 was associated with the highest risk of RA (corrected P = 1.81 × 10⁻¹¹, OR 58.2 [95% CI 7.95–425.70]). The mean age at disease onset was ∼4 years earlier or was 3 years earlier, respectively, in patients with at least 1 copy of the DRB1*0405 or the DRB1*0901 allele. Radiographic changes (stages II–IV) were more frequent in patients with at least 1 copy of DRB1*0405 (P = 0.032, 92.6% versus 84.3%, OR 2.33 [95% CI 1.24–4.39]).

Conclusion

The DRB1*0405/*0901 heterozygote has the strongest association with RA, suggesting that this heterozygote enhances the susceptibility to RA in Koreans.

     

Brief Report: Association of HLA–DRB1*0101/*0405 with susceptibility to anti–melanoma differentiation–associated gene 5 antibody–positive dermatomyositis in the Japanese population

Objective

The complication of interstitial lung disease (ILD) in polymyositis/dermatomyositis (PM/DM) is associated with anti–aminoacyl–transfer RNA synthetase (anti‐aaRS) antibody or anti–melanoma differentiation–associated gene 5 (anti–MDA‐5) antibody positivity. Anti–MDA‐5 antibody is associated with clinically amyopathic DM and fatal outcome due to rapidly progressive ILD in Asian populations. The association between genetic factors and anti–MDA‐5 antibody–positive DM is unclear. This study was undertaken to investigate the HLA–DRB1 genotype in patients with anti–MDA‐5 antibody–positive DM.

Methods

We examined genetic differences among 17 patients with anti–MDA‐5 antibody–positive DM, 33 patients with anti‐aaRS antibody–positive PM/DM, 33 patients with PM/DM without anti‐aaRS antibody or ILD, and 265 healthy controls.

Results

The frequencies of HLA–DRB1*0101 and DRB1*0405 were 29% and 71%, respectively, in patients with anti–MDA‐5 antibody–positive DM, which were higher than the frequencies in healthy controls (10% and 25%, respectively). Among the 17 patients with anti–MDA‐5 antibody–positive DM, 16 (94%) harbored either the DRB1*0101 or DRB1*0405 allele. The combined frequency of the DRB1*0101 allele and the DRB1*0405 allele was significantly higher in patients with anti–MDA‐5 antibody–positive DM than in patients with PM/DM without anti‐aaRS antibody or ILD, with an odds ratio (OR) of 42.7 (95% confidence interval [95% CI] 4.9–370.2) (P = 1.1 × 10⁻⁵), or in patients with anti‐aaRS antibody–positive PM/DM (OR 13.3 [95% CI 1.6–112.6], P = 4.5 × 10⁻³).

Conclusion

Our findings indicate that HLA–DRB1*0101/*0405 is associated with susceptibility to anti–MDA‐5 antibody–positive DM in the Japanese population.

     

Rituximab therapy for myopathy associated with anti–signal recognition particle antibodies: A case series

Objective

The myopathy associated with anti–signal recognition particle (anti‐SRP) is a severe necrotizing immune‐mediated disease characterized by rapidly progressive proximal muscle weakness, markedly elevated serum creatine kinase (CK) levels, and poor responsiveness to traditional immunosuppressive therapies. Reports on the efficacy of B cell depletion therapy for anti‐SRP–associated myopathy are mixed. We describe 8 patients with anti‐SRP–associated myopathy and their response to treatment with the anti‐CD20 monoclonal antibody rituximab.

Methods

We identified 8 patients with myopathy who tested positive for anti‐SRP antibodies by immunoprecipitation and were treated with rituximab as part of clinical care. We reviewed their medical records to assess clinical, serologic, and histologic characteristics and response to therapy. In 5 patients, serum was collected before and after rituximab therapy. Autoantibodies were detected by immunoprecipitation and quantitated by densitometry, and the percent decreases in anti‐SRP autoantibody levels were calculated.

Results

Six of 8 patients who had been refractory to standard immunosuppressive therapy demonstrated improved manual muscle strength and/or decline in CK levels as early as 2 months after rituximab treatment. Three patients sustained the response for 12–18 months after initial dosing. All of the patients were continued on adjunctive corticosteroids, but doses were substantially reduced after rituximab. Quantitative levels of serum anti‐SRP antibodies also decreased after rituximab treatment.

Conclusion

B cell depletion therapy with rituximab is effective for patients with myopathy associated with anti‐SRP. The substantial decrease in anti‐SRP antibody levels after rituximab treatment also suggests that B cells and anti‐SRP antibodies may play a role in the pathogenesis of this myopathy.     

Opposing effects of HLA–DRB1*13 alleles on the risk of developing anti–citrullinated protein antibody–positive and anti–citrullinated protein antibody–negative rheumatoid arthritis

Objective

The effect of non–shared epitope HLA–DRB1 alleles on rheumatoid arthritis (RA) is poorly understood. This study was undertaken to investigate the effects of several HLA–DRB1 alleles, independent of the shared epitope, on the risk of developing anti–citrullinated protein antibody (ACPA)–positive or ACPA‐negative RA in a large case–control study.

Methods

HLA typing for the DRB1 gene was performed in 1,352 patients with RA and 922 controls from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study. Relative risks (RRs) and 95% confidence intervals (95% CIs) were calculated.

Results

DRB1*13 was found to protect against ACPA‐positive RA when stratifying for the shared epitope and using a dominant genetic model (RR 0.41 [95% CI 0.26–0.64]). Furthermore, DRB1*13 neutralized the effect of the shared epitope in ACPA‐positive RA (RR 3.91 [95% CI 3.04–5.02] in patients who had the shared epitope but not DRB1*13, and RR 1.22 [95% CI 0.81–1.83] in patients with both the shared epitope and DRB1*13, as compared with patients negative for both the shared epitope and DRB1*13). However, we did not replicate the previous published risk of ACPA‐negative RA conferred by DRB1*03 when a dominant genetic model was used (RR 1.29 [95% CI 0.91–1.82]). Similarly, no significant effect of DRB1*03 on RR for ACPA‐negative RA was seen using the recessive genetic model (RR 1.18 [95% CI 0.6–2.4]). In contrast, the combination of DRB1*03 and DRB1*13 was significantly associated with increased risk of developing ACPA‐negative RA (RR 2.07 [95% CI 1.17–3.67]).

Conclusion

Our findings indicate that the DRB1*13 allele plays a dual role in the development of RA, by protecting against ACPA‐positive RA but, in combination with DRB1*03, increasing the risk of ACPA‐negative RA.

     

HLA DRB1*01 and DRB1*04 phenotyping does not predict the need for joint surgery in rheumatoid arthritis. A retrospective quantitative evaluation of 300 French patients

OBJECTIVE: To determine if the presence of HLA-DR disease-associated epitopes predicts the need for total joint arthroplasty or joint fusion in rheumatoid arthritis (RA). METHODS: Tertiary-referral, monocenter study. Three hundred RA patients (1987 ACR criteria) were retrospectively evaluated; outcome measure was recourse to total joint arthroplasty, joint fusion or bone resection. HLA-DR1 and DR4 were considered as the disease-associated epitopes (subtypes were not available for analysis). Analysis was performed using the lifetable method (Kaplan-Meyer technique). RESULTS: Of the 300 patients included, 78% were women, mean age: 56+/-14 years, mean RA follow-up: 12+/-9 years. Phenotyping: 73% of patients carried one (52%) or two (21%) disease-associated epitopes. Surgery was performed on 24% of the patients during follow-up. The most frequent surgery was total hip arthroplasty (13% of patients). According to lifetable analysis, 13% of patients had surgery (total joint arthroplasty or joint fusion) after 10 years of follow-up, 34% after 20 years. years of follow-up, There was no statistically significant difference in recourse to surgery according to absence or presence (single or double-dose) of disease-associated epitopes. Similar results were observed if the event was the second surgical procedure on a given patient. CONCLUSION: This study failed to demonstrate a relation between HLA phenotyping and the severity of RA defined by the requirement for surgery.     

Associations of HLA‐DRB1 alleles with anti‐citrullinated protein antibody‐positive and anti‐citrullinated protein antibody‐negative rheumatoid arthritis in northern east part of Turkey

Aim: The aim of this study was to investigate the associations between human leukocyte antigen (HLA)‐DRB1 alleles with genetic susceptibility to rheumatoid arthritis (RA) and production of antibodies against cyclic citrullinated peptide (anti‐CCP antibody) and rheumatoid factor (RF) in Turkish RA patients. Methods: We studied 291 RA patients and 253 controls. Genotyping was performed by polymerase chain reaction with sequence‐specific oligonucleotide probes hybridization method. Serum levels of anti‐CCP antibody, IgM‐RF and high sensitive C‐reactive protein titers were measured by commercial kits using immunological methods. Results: We found that HLA‐DRB1*04 and *09 alleles were associated in anti‐CCP+ and anti‐CCP+ RA patients (P < 0.0001 and P < 0.001, respectively), while DRB1*01 and *04 were determined to be higher in RF+ RA patients (P < 0.001 and P < 0.0001, respectively). Moreover, DRB1*11 and DRB1*13 alleles were determined to be lower in RF and anti‐CCP/RF+ RA patients (P < 0.001 for both). HLA‐DRB1*04 was identified as a common responsible allele for susceptibility to the disease in anti‐CCP, RF and anti‐CCP/RF? RA patients (P = 0.0018, P = 0.0004 and P = 0.0023, respectively). HLA‐DRB1*13 allele alone was found to be protective against to anti‐CCP+ and RF? RA (P = 0.0003 and P = 0.006, respectively). On the contrary, there was no protective allele in anti‐CCP/RF? RA as well as anti‐CCP? RA patients. Conclusion: This study indicates that associate and protective HLA‐DRB1 allele distributions are different in autoantibody (anti‐CCP or RF or anti‐CCP/RF)+ RA and autoantibody? RA patients, with exceptions of DRB1*04 and DRB1*13.     

Interferon-β1A–induced polyarthritis in a patient with the HLA–DRB1*0404 allele

Human interferon-α (IFNα) and IFNβ are administered for treatment of several diseases, including viral infections, malignancies, and multiple sclerosis (MS). IFNα therapy has been associated with the production of autoantibodies and the development of a variety of autoimmune disorders, including polyarthritis. This report describes the development of seronegative, symmetric polyarthritis in a patient with relapsing-remitting MS, after 8 weeks of therapy with IFNβ1a. HLA phenotyping analysis of the patient revealed the presence of HLA–DRB1*0404, an allele known to be associated with the development of rheumatoid arthritis. Therefore, IFNβ1a may have induced arthritis in a patient who was genetically predisposed to develop arthritis on the basis of HLA determinants. The English-language literature regarding IFNα- and IFNβ-induced polyarthritis is reviewed, and possible mechanisms for IFNα- and IFNβ-induced autoimmunity, including the contribution of HLA determinants and nitric oxide overproduction, are discussed.     

A possible mechanism for endogenous activation of the type I interferon system in myositis patients with anti–Jo‐1 or anti–Ro 52/anti–Ro 60 autoantibodies

Objective

To investigate type I interferon (IFN) system activation and its correlation with autoantibodies and organ manifestations in polymyositis (PM), dermatomyositis (DM), and inclusion body myositis.

Methods

Sera from 30 patients and 16 healthy controls, or purified IgG, were combined with material released from necrotized cells to stimulate IFNα production by peripheral blood mononuclear cells (PBMCs) from healthy blood donors. Muscle biopsy specimens from 25 patients and 7 healthy controls were investigated for blood dendritic cell antigen 2 (BDCA‐2)–positive plasmacytoid dendritic cells (PDCs) and IFNα/β‐inducible myxovirus resistance 1 (MX‐1) protein.

Results

Sera from 13 patients who were positive for anti–Jo‐1 or anti–Ro 52/anti–Ro 60 autoantibodies induced IFNα production in PBMCs when combined with necrotic cell material. In addition, IgG prepared from anti–Jo‐1–positive PM sera induced IFNα with necrotic material, but not when the latter was treated with RNase. BDCA‐2 expression in PDCs in muscle tissue was increased in PM patients with anti–Jo‐1 autoantibodies, while MX‐1 staining in capillaries was increased in DM patients, compared with healthy individuals. IFNα‐inducing capacity correlated with interstitial lung disease, while MX‐1 expression in the capillaries correlated with DM.

Conclusion

Immune complexes containing anti–Jo‐1 or anti–Ro 52/anti–Ro 60 autoantibodies and RNA may act as endogenous IFNα inducers that activate IFNα production in PDCs. These PDCs could be of importance for inducing myositis, whereas in DM patients without autoantibodies the presence of MX‐1 protein in capillaries suggests another cellular IFNα source and induction mechanism. Consequently, the type I IFN system may be of importance in both PM and DM, but via different pathways.