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Natural cryptic autoantibodies

Cheng HM

Autoimmunity, 1998;27(2):99-108.
PMID: 9583741
Matched MeSH terms: Autoantibodies/immunology*
Cryptic natural autoantibodies and co-potentiators

Cheng HM, Chamley L

Autoimmun Rev, 2008 Jun;7(6):431-4.
PMID: 18558357 DOI: 10.1016/j.autrev.2008.03.011

Natural autoantibodies are normal components of the humoral arm of the immune system found in clinically healthy individuals. There are two subpopulations of natural antibodies, including an overt group of antibodies that are readily detected in unfractionated normal human sera. The other natural antibody subgroup is revealed by physico or biochemical treatment of normal human sera in vitro. Unmasking of this latter cryptic natural autoantibodies (cNA) may occur in vivo by local factors in the tissue environment of disease states. The masking cryptic factors may be immunoglobulin (Ig) or non-Ig in nature. These factors may either be co-inhibitors or co-enhancers of cNA. In the heat-potentiated binding of natural anti-phospholipid antibodies, apolipoprotein H (beta 2-glycoprotein I) appears to act as a co-enhancer. The immuno-relationship between the in vitro and in vivo cNA phenomenon remains to be elucidated.

Matched MeSH terms: Autoantibodies/immunology*
Fulltext The autoantibody profile and its association with clinical manifestations in Malay SLE patients

Maraina CH, Kamaliah MD, Ishak M

Asian Pac J Allergy Immunol, 2004 Mar;22(1):33-7.
PMID: 15366656

A cross sectional study was conducted to determine the auto-antibody profile of Malay SLE patients in Kelantan, North East Malaysia and to correlate them with clinical presentations. Eighty-two Malay SLE patients who fulfilled the ARA criteria underwent the following tests: ANA, anti-dsDNA antibody, anti-ENA antibody and RF. The results revealed that ANA was positive in 91.5% of the patients, anti-dsDNA antibody in 53.7%, however, anti-ENA antibodies were positive in only 9.8% of the cases at the time of the study and none had a positive RF. The profile of autoantibodies was similar to other studies except for a lower incidence of anti-ENA antibodies. Sixty three percent of patients had lupus nephritis. The pattern of clinical presentations were noted to be more similar to those found among Chinese and Indian SLE populations than compared to the Caucasians. There was a significant association between anti-dsDNA antibody and lupus nephritis and between anti-ENA antibody and thrombocytopenia.

Matched MeSH terms: Autoantibodies/immunology*
The One with Many Facets: Anti-Glycine Receptor Antibodies-Related Parkinsonism with Complex Visual Phenomena and Stiff-Limb Syndrome

Mohd Fauzi NA, Mohd Nazi NN, Wan Mohd Azam ER, P Bhatia K

Mov Disord Clin Pract, 2024 Aug;11 Suppl 2(Suppl 2):S21-S25.
PMID: 38923295 DOI: 10.1002/mdc3.14144
Matched MeSH terms: Autoantibodies/immunology
Antiphospholipid antibodies and antiphospholipid syndrome in cancer: Uninvited guests in troubled times

Islam MA

Semin Cancer Biol, 2020 08;64:108-113.
PMID: 31351197 DOI: 10.1016/j.semcancer.2019.07.019

Antiphospholipid antibodies (aPLs) are autoantibodies with laboratory significance in developing thrombosis and pregnancy morbidity in antiphospholipid syndrome (APS). High prevalence of aPLs namely - anticardiolipin, anti-β2-glycoprotein I, lupus anticoagulant, antiphosphatidylcholine, antiphosphatidylserine, antiphosphatidylinositol, antiphosphatidylethanolamine and antiprothrombin antibodies have been observed in patients with different types of haematological malignancies and solid tumours. Although cancer patients have high risk of developing thrombosis, the risk becomes even higher in aPLs carriers. Although the relationship between aPLs and cancer has to be further investigated, however, the presence of aPLs in neoplastic patients can possibly increase the risk of developing thrombosis. As the pathogenic role of aPLs in cancer is still a matter of debate, more researches should be conducted on the association between the aPLs and malignancies towards the potential impact on understanding the pathogenicity and treatment when cancer and APS coexists.

Matched MeSH terms: Autoantibodies/immunology*
Fulltext Differences in the Spectrum of Anti-Citrullinated Protein Antibody Fine Specificities Between Malaysian and Swedish Patients With Rheumatoid Arthritis: Implications for Disease Pathogenesis

Too CL, Murad S, Hansson M, Alm LM, Dhaliwal JS, Holmdahl R, et al.

Arthritis Rheumatol, 2017 01;69(1):58-69.
PMID: 27483449 DOI: 10.1002/art.39827

OBJECTIVE: Antibodies to the citrullinated protein antigens (ACPAs) are important in the diagnosis and pathogenesis of rheumatoid arthritis (RA). However, the prevalence of ACPAs with different fine specificities in different populations is unclear. This study sought to examine the fine specificity of the antibody responses toward citrullinated proteins in RA patients from Malaysia, an area where genetic and environmental determinants of RA are different from those in more frequently studied cohorts of Caucasian subjects.
METHODS: A multiplex analytic microarray system was used to analyze the occurrence of antibodies to 10 different citrullinated peptides (filaggrin [fil307-324], vimentin [Vim2-17, Vim60-75], fibrinogen [Fibα563-583, Fibα580-600, Fibβ36-52, Fibβ62-81a, Fibβ62-81b], enolase [Eno5-21], and type II collagen [CitCII355-378]) in serum samples from 4,089 RA patients (1,231 Malaysian and 2,858 Swedish) and 827 healthy control subjects (249 Malaysian and 578 Swedish). The positive reaction threshold for each peptide was set separately for each population based on a specificity of 98%.
RESULTS: Distinct differences in the frequencies of 5 ACPA fine specificities (Vim60-75, Vim2-17, Fibβ62-81b, Eno5-21, and CitCII355-378) were found between the Malaysian and Swedish RA populations, despite a nearly identical percentage of patients in each population who were positive for anti-cyclic citrullinated peptide 2 antibodies. In Malaysian RA patients compared with Swedish RA patients, the frequencies of antibodies to Vim60-75 (54% versus 44%, corrected P [Pcorr ] = 1.06 × 10-8 ) and CitCII355-378 (17% versus 13%, Pcorr = 0.02) were significantly higher, while the frequencies of antibodies to Vim2-17 (25% versus 32%, Pcorr = 1.91 × 10-4 ), Fibβ62-81b (15% versus 30%, Pcorr = 2.47 × 10-22 ), and Eno5-21 (23% versus 50%, Pcorr = 3.64 × 10-57 ) were significantly lower.
CONCLUSION: Serum ACPA fine specificities differ between RA patients in different populations, although the total proportions of individuals positive for ACPAs are similar. Differing patterns of ACPA fine specificity could be attributed to variations in genetic and/or environmental factors.

Matched MeSH terms: Autoantibodies/immunology*
Autoantibody profile of patients infected with knowlesi malaria

Liew J, Amir A, Chen Y, Fong MY, Razali R, Lau YL

Clin Chim Acta, 2015 Aug 25;448:33-8.
PMID: 26086445 DOI: 10.1016/j.cca.2015.06.006

Autoantibodies or antibodies against self-antigens are produced either during physiological processes to maintain homeostasis or pathological process such as trauma and infection. Infection with parasites including Plasmodium has been shown to generally induce elevated self-antibody (autoantibody) levels. Plasmodium knowlesi is increasingly recognized as one of the most important emerging human malaria in Southeast Asia that can cause severe infection leading to mortality. Autoimmune-like phenomena have been hypothesized to play a role in the protective immune responses in malaria infection.

Matched MeSH terms: Autoantibodies/immunology*
Fulltext Anti-carbamylated protein antibodies in rheumatoid arthritis patients and their association with rheumatoid factor

Othman MA, Ghazali WSW, Hamid WZWA, Wong KK, Yahya NK

Saudi Med J, 2017 Sep;38(9):934-941.
PMID: 28889152 DOI: 10.15537/smj.2017.9.20841

OBJECTIVES: To evaluate levels of anti-carbamylated protein (anti-CarP) antibodies in rheumatoid arthritis (RA) patients and to determine their association with serological parameters and disease activity. Methods: A cross-sectional study involving 105 multiethnic RA patients (48 rheumatoid factor [RF]-positive and 57 RF-negative patients) was conducted at Hospital Universiti Sains Malaysia, Kelantan, Malaysia, from January 2015 to February 2016. Fifty healthy controls (HCs) were included. C-reactive protein (CRP), RF, anti-cyclic citrullinated peptide (anti-CCP) and anti-CarP antibodies were measured. A health assessment questionnaire (HAQ) was administered to the study participants and 28-joint Disease Activity Score (DAS28) were obtained. Results: The level of anti-CarP antibodies was significantly increased in the RA patients compared with HCs (p=0.042). The presence of anti-CarP antibodies was significantly associated with RF (p=0.019) and the HAQ (p=0.010). A significant association between the presence of anti-CarP antibodies and the DAS28 was not found (p=0.632). Conclusion: Our study provides further evidence that the level of anti-CarP antibodies is significantly elevated in RA patients.

Study site: Rheumatology clinic, Hospital Universiti Sains Malaysia

Matched MeSH terms: Autoantibodies/immunology*
Fulltext Different IVIG glycoforms affect in vitro inhibition of anti-ganglioside antibody-mediated complement deposition

Sudo M, Yamaguchi Y, Späth PJ, Matsumoto-Morita K, Ong BK, Shahrizaila N, et al.

PLoS One, 2014;9(9):e107772.
PMID: 25259950 DOI: 10.1371/journal.pone.0107772

Intravenous immunoglobulin (IVIG) is the first line treatment for Guillain-Barré syndrome and multifocal motor neuropathy, which are caused by anti-ganglioside antibody-mediated complement-dependent cytotoxicity. IVIG has many potential mechanisms of action, and sialylation of the IgG Fc portion reportedly has an anti-inflammatory effect in antibody-dependent cell-mediated cytotoxicity models. We investigated the effects of different IVIG glycoforms on the inhibition of antibody-mediated complement-dependent cytotoxicity. Deglycosylated, degalactosylated, galactosylated and sialylated IgG were prepared from IVIG following treatment with glycosidases and glycosyltransferases. Sera from patients with Guillain-Barré syndrome, Miller Fisher syndrome and multifocal motor neuropathy associated with anti-ganglioside antibodies were used. Inhibition of complement deposition subsequent to IgG or IgM autoantibody binding to ganglioside, GM1 or GQ1b was assessed on microtiter plates. Sialylated and galactosylated IVIGs more effectively inhibited C3 deposition than original IVIG or enzyme-treated IVIGs (agalactosylated and deglycosylated IVIGs). Therefore, sialylated and galactosylated IVIGs may be more effective than conventional IVIG in the treatment of complement-dependent autoimmune diseases.

Matched MeSH terms: Autoantibodies/immunology*
Silica exposure is associated with an increased risk of developing ACPA-positive rheumatoid arthritis in an Asian population: evidence from the Malaysian MyEIRA case-control study

Yahya A, Bengtsson C, Larsson P, Too CL, Mustafa AN, Abdullah NA, et al.

Mod Rheumatol, 2014 Mar;24(2):271-4.
PMID: 24593203 DOI: 10.3109/14397595.2013.854076

OBJECTIVES: Silica exposure has been associated with an increased risk of developing rheumatoid arthritis (RA), especially among smokers. In this study, we aimed at examining the association between silica exposure (and its interaction with smoking) and the risk of RA in the Malaysian population.
METHODS: In total, 149 cases and 213 matched controls, all men, were included between August 2005 and December 2009. A case was defined as a person with early diagnosed RA using the 1987 American College of Rheumatology criteria for RA. Controls were randomly selected matched on sex, age and residential area. Silica exposure was defined as exposure to stone dust, rock drilling or stone crushing, and smoking status was categorized as ever/never cigarette smoking.
RESULTS: An increased risk of anti-citrullinated protein antibody (ACPA)-positive RA (OR = 2.4, 95 % CI 1.0-5.6) was observed among those exposed to silica. Ever-smokers exposed to silica had a particularly high risk of developing ACPA-positive RA (OR = 7.5, 95 % CI 2.3-24.2), compared with never-smokers not exposed to silica. No association was found regarding ACPA-negative RA.
CONCLUSION: Our data demonstrate that exposure to both silica and cigarette smoke comprise risks for developing RA in the Malaysian genetic context. The findings expand a link between environmental lung exposures and ACPA-positive RA to Asian populations.

Matched MeSH terms: Autoantibodies/immunology*
Nystagmus and diplopia in a patient with positive aquaporin-4 antibody

Koh KL, Sonny Teo KS, Halim SA, Wan Hitam WH

Can J Ophthalmol, 2019 04;54(2):e66-e69.
PMID: 30975364 DOI: 10.1016/j.jcjo.2018.06.022
Matched MeSH terms: Autoantibodies/immunology*
Rheumatoid arthritis: Recent advances on its etiology, role of cytokines and pharmacotherapy

Alam J, Jantan I, Bukhari SNA

Biomed Pharmacother, 2017 Aug;92:615-633.
PMID: 28582758 DOI: 10.1016/j.biopha.2017.05.055

An autoimmune disease is defined as a clinical syndrome resulted from an instigation of both T cell and B cell or individually, in the absence of any present infection or any sort of distinguishable cause. Clonal deletion of auto reactive cells remains the central canon of immunology for decades, keeping the role of T cell and B cell aside, which are actually the guards to recognize the entry of foreign body. According to NIH, 23.5 million Americans are all together affected by these diseases. They are rare, but with the exception of RA. Rheumatoid arthritis is chronic and systemic autoimmune response to the multiple joints with unknown ethology, progressive disability, systemic complications, early death and high socioeconomic costs. Its ancient disease with an old history found in North American tribes since 1500 BCE, but its etiology is yet to be explored. Current conventional and biological therapies used for RA are not fulfilling the need of the patients but give only partial responses. There is a lack of consistent and liable biomarkers of prognosis therapeutic response, and toxicity. Rheumatoid arthritis is characterized by hyperplasic synovium, production of cytokines, chemokines, autoantibodies like rheumatoid factor (RF) and anticitrullinated protein antibody (ACPA), osteoclastogensis, angiogenesis and systemic consequences like cardiovascular, pulmonary, psychological, and skeletal disorders. Cytokines, a diverse group of polypeptides, play critical role in the pathogenesis of RA. Their involvement in autoimmune diseases is a rapidly growing area of biological and clinical research. Among the proinflammatory cytokines, IL-1α/β and TNF-α trigger the intracellular molecular signalling pathway responsible for the pathogenesis of RA that leads to the activation of mesenchymal cell, recruitment of innate and adaptive immune system cells, activation of synoviocytes which in term activates various mediators including tumour necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) and interleukin-8 (IL-8), resulting in inflamed synovium, increase angiogenesis and decrease lymphangiogensis. Their current pharmacotherapy should focus on their three phases of progression i.e. prearthritis phase, transition phase and clinical phase. In this way we will be able to find a way to keep the balance between the pro and anti-inflammatory cytokines that is believe to be the dogma of pathogenesis of RA. For this we need to explore new agents, whether from synthetic or natural source to find the answers for unresolved etiology of autoimmune diseases and to provide a quality of life to the patients suffering from these diseases specifically RA.

Matched MeSH terms: Autoantibodies/immunology
Vitamin D status in a monocentric cohort of systemic lupus erythematosus (SLE) patients and correlations with clinical and immunological profile

Ong SG, Ding HJ

Med J Malaysia, 2019 12;74(6):492-498.
PMID: 31929474

INTRODUCTION: Numerous studies have found that a majority of systemic lupus erythematosus (SLE) patients have suboptimal vitamin D levels. The major contributory factor is most likely attributed to sun protection measures in order to avoid SLE flares. The objectives of this research included the assessment of vitamin D status and its association with clinical manifestations of SLE, cardiovascular risk factors, autoantibodies, SLE disease activity and damage accrual.
METHOD: This retrospective study involved SLE patients who attended the Rheumatology Clinic at the Hospital Kuala Lumpur from January 2014 to December 2016. Vitamin D was categorised as normal, insufficient or deficient, and the clinical variables were compared across vitamin D categories with chi-squared tests and Pearson correlation coefficient.
RESULTS: We included 216 patients. The mean 25(OH)D concentration was 51.3(Standard Deviation; SD 14.8) nmol/L. Fifty (23.1%) patients had vitamin D deficiency, 120 (55.6%) had vitamin D insufficiency, while 46 (21.3%) had adequate vitamin D levels. There were statistically significant associations between vitamin D status and ethnic group, lupus nephritis and hypertension. No correlations were observed between vitamin D status with SLEDAI score (Pearson correlation coefficient -0.015, p=0.829) as well as SDI score (Pearson correlation coefficient -0.017, p=0.801).
CONCLUSION: SLE patients should be screened for vitamin D concentrations and their levels optimised.

Matched MeSH terms: Autoantibodies/immunology*
Clinical and autoantibody profile in systemic sclerosis: baseline characteristics from a West Malaysian cohort

Sujau I, Ng CT, Sthaneshwar P, Sockalingam S, Cheah TE, Yahya F, et al.

Int J Rheum Dis, 2015 May;18(4):459-65.
PMID: 24618222 DOI: 10.1111/1756-185X.12322

AIM: To evaluate the clinical and antibody profile of systemic sclerosis (SSc) in a Malaysian cohort.
METHODS: Consecutive patients with SSc in University Malaya Medical Centre from March to November 2012 were included in this study. In addition to clinical characterization, all subjects underwent autoantibody testing using Euroline immunoblot assay. The association between clinical features and autoantibody profile was evaluated.
RESULTS: There were 31, predominantly Chinese (45.2%), subjects. Limited cutaneous disease was the most common subtype (71%). Raynaud's phenomenon was the most commonly observed feature (83.9%). Nine (29%) had esophageal dysmotility symptoms and 23 (74.2%), including all patients with diffuse SSc, had symptoms of gastro-esophageal reflux disease (GERD). Restrictive pattern on pulmonary function test and evidence of lung fibrosis were seen in more than 70% of patients. Echocardiographic evidence of pulmonary arterial hypertension was seen in 58.1%. Telangiectasia, calcinosis, digital ulcers, digital pulp loss or pitting were seen more commonly in the diffuse subtype. The two most prevalent autoantibodies were anti-Scl-70 and anti-Ro-52. The presence of anti-Scl-70 was significantly associated with restrictive lung disease (P = 0.05). Anti-Ro-52 was associated with control subjects with other autoimmune diseases (P = 0.043). The presence of anti-PM-Scl-75 was associated with overlap syndrome (P = 0.032). Patients with anticentromere antibodies were more likely to have vasculitic rash (P = 0.012).
CONCLUSION: In Malaysia, SSc most commonly affects the Chinese. Limited cutaneous is more common than diffuse subtype. Features of CREST (calcinosis, Reynaud disease, esophageal dysmotility, sclerodactyly, telangiectasia) are more commonly observed in the diffuse cutaneous subgroup. Anti-Scl-70 and anti-Ro-52 antibodies are promising biomarkers for pulmonary involvement in SSc.
KEYWORDS: Malaysia; autoantibodies; clinical profile; systemic sclerosis

Matched MeSH terms: Autoantibodies/immunology*
Fulltext Augmentation of Autoantibodies by Helicobacter pylori in Parkinson's Disease Patients May Be Linked to Greater Severity

Suwarnalata G, Tan AH, Isa H, Gudimella R, Anwar A, Loke MF, et al.

PLoS One, 2016;11(4):e0153725.
PMID: 27100827 DOI: 10.1371/journal.pone.0153725

Parkinson's disease (PD) is the second most common chronic and progressive neurodegenerative disorder. Its etiology remains elusive and at present only symptomatic treatments exists. Helicobacter pylori chronically colonizes the gastric mucosa of more than half of the global human population. Interestingly, H. pylori positivity has been found to be associated with greater of PD motor severity. In order to investigate the underlying cause of this association, the Sengenics Immunome protein array, which enables simultaneous screening for autoantibodies against 1636 human proteins, was used to screen the serum of 30 H. pylori-seropositive PD patients (case) and 30 age- and gender-matched H. pylori-seronegative PD patients (control) in this study. In total, 13 significant autoantibodies were identified and ranked, with 8 up-regulated and 5 down-regulated in the case group. Among autoantibodies found to be elevated in H. pylori-seropositive PD were included antibodies that recognize Nuclear factor I subtype A (NFIA), Platelet-derived growth factor B (PDGFB) and Eukaryotic translation initiation factor 4A3 (eIFA3). The presence of elevated autoantibodies against proteins essential for normal neurological functions suggest that immunomodulatory properties of H. pylori may explain the association between H. pylori positivity and greater PD motor severity.

Matched MeSH terms: Autoantibodies/immunology*
Fulltext ANA negative (Ro) lupus erythematosus with multiple major organ involvement: a case report

Che Maraina CH, Kamaliah MD, Ishak M

Asian Pac J Allergy Immunol, 2002 Dec;20(4):279-82.
PMID: 12744629

Anti-nuclear antibody (ANA) negative systemic lupus erythematosus (SLE) occurs in about 4-13% of SLE cases. A small group of ANA negative SLE patients with positive anti-Ro antibodies usually present with typical vasculitic skin lesions which can be associated with photosensitivity, renal disease, congenital heart block or neonatal lupus. We present a case of a persistently ANA negative patient who presented with joint pain, rashes, mouth ulcer and alopecia. Clinical diagnosis of systemic lupus erythematosus was made even though ANA was negative. She was started on steroids and went into remission. Later, she developed several episodes of convulsions associated with fever and prominent vasculitic lesions. The patient was also found to have microscopic hematuria, proteinuria, anemia and thrombocytopenia. Renal biopsy showed lupus nephritis class 1B. Due to the prominent skin lesions, we performed anti-extractable nuclear antigens (ENA) antibodies test and anti-Ro turned out to be positive. The final diagnosis was ANA negative SLE (Ro lupus) with cutaneous, renal, musculoskeletal, hematological and cerebral Involvement.

Matched MeSH terms: Autoantibodies/immunology
Prevalence and clinical significance of antibodies to ribonucleoproteins in systemic lupus erythematosus in Malaysia

Wang CL, Ooi L, Wang F

Br J Rheumatol, 1996 Feb;35(2):129-32.
PMID: 8612023

One hundred and seventy patients with systemic lupus erythematosus (SLE) were studied for the prevalence of antibodies to the small RNA-associated proteins Ro/SSA, La/SSB, Sm, U1RNP and Sm. The relationship of these autoantibodies to different races, sexes and clinical manifestations of SLE was evaluated. Passive immunodiffusion was employed using human spleen extract as antigen source for Ro and rabbit thymus extract for La, Sm and U1RNP. We found the prevalence of antibodies to be as follows: anti-Ro/SSA, 36%; anti-La/SSB, 8%; anti-Sm, 15% ; anti-U1RNP, 21%. Except for a low prevalence of anti-La, the prevalence of these antibodies was similar to that in Western studies, The prevalence of anti-Ro/SSA is similar to that reported in the Western studies, but lower than that reported in the Oriental patients from Singapore and Hong Kong. Linkages of anti-Ro with anti-La antibodies were usual; however, although anti-Sm antibodies were usually associated with anti-U1RNP, they were more frequently associated with anti-Ro antibodies. The Malay patients had a high prevalence of anti U1RNP compared to other races. No gender difference was detected. Anti-Sm antibody was associated with serositis and anti-U1RNP antibodies with Raynaud's phenomenon. No association was found between the presence of skin renal or cerebral manifestations and any specific antibodies or combination of antibodies.

Matched MeSH terms: Autoantibodies/immunology
Fulltext Amino acid signatures of HLA Class-I and II molecules are strongly associated with SLE susceptibility and autoantibody production in Eastern Asians

Molineros JE, Looger LL, Kim K, Okada Y, Terao C, Sun C, et al.

PLoS Genet, 2019 04;15(4):e1008092.
PMID: 31022184 DOI: 10.1371/journal.pgen.1008092

Human leukocyte antigen (HLA) is a key genetic factor conferring risk of systemic lupus erythematosus (SLE), but precise independent localization of HLA effects is extremely challenging. As a result, the contribution of specific HLA alleles and amino-acid residues to the overall risk of SLE and to risk of specific autoantibodies are far from completely understood. Here, we dissected (a) overall SLE association signals across HLA, (b) HLA-peptide interaction, and (c) residue-autoantibody association. Classical alleles, SNPs, and amino-acid residues of eight HLA genes were imputed across 4,915 SLE cases and 13,513 controls from Eastern Asia. We performed association followed by conditional analysis across HLA, assessing both overall SLE risk and risk of autoantibody production. DR15 alleles HLA-DRB1*15:01 (P = 1.4x10-27, odds ratio (OR) = 1.57) and HLA-DQB1*06:02 (P = 7.4x10-23, OR = 1.55) formed the most significant haplotype (OR = 2.33). Conditioned protein-residue signals were stronger than allele signals and mapped predominantly to HLA-DRB1 residue 13 (P = 2.2x10-75) and its proxy position 11 (P = 1.1x10-67), followed by HLA-DRB1-37 (P = 4.5x10-24). After conditioning on HLA-DRB1, novel associations at HLA-A-70 (P = 1.4x10-8), HLA-DPB1-35 (P = 9.0x10-16), HLA-DQB1-37 (P = 2.7x10-14), and HLA-B-9 (P = 6.5x10-15) emerged. Together, these seven residues increased the proportion of explained heritability due to HLA to 2.6%. Risk residues for both overall disease and hallmark autoantibodies (i.e., nRNP: DRB1-11, P = 2.0x10-14; DRB1-13, P = 2.9x10-13; DRB1-30, P = 3.9x10-14) localized to the peptide-binding groove of HLA-DRB1. Enrichment for specific amino-acid characteristics in the peptide-binding groove correlated with overall SLE risk and with autoantibody presence. Risk residues were in primarily negatively charged side-chains, in contrast with rheumatoid arthritis. We identified novel SLE signals in HLA Class I loci (HLA-A, HLA-B), and localized primary Class II signals to five residues in HLA-DRB1, HLA-DPB1, and HLA-DQB1. These findings provide insights about the mechanisms by which the risk residues interact with each other to produce autoantibodies and are involved in SLE pathophysiology.

Matched MeSH terms: Autoantibodies/immunology*
Fulltext Polymorphisms in peptidylarginine deiminase associate with rheumatoid arthritis in diverse Asian populations: evidence from MyEIRA study and meta-analysis

Too CL, Murad S, Dhaliwal JS, Larsson P, Jiang X, Ding B, et al.

Arthritis Res Ther, 2012;14(6):R250.
PMID: 23164236 DOI: 10.1186/ar4093

INTRODUCTION: The majority of our knowledge regarding disease-related mechanisms of uncontrolled citrullination and anti-citrullinated protein antibody development in rheumatoid arthritis (RA) was investigated in Caucasian populations. However, peptidylarginine deiminase (PADI) type 4 gene polymorphisms are associated with RA in East Asian populations and weak or no association was found in Caucasian populations. This study explores the association between the PADI4 polymorphisms and RA risk in a multiethnic population residing in South East Asia with the goal of elucidating generalizability of association in non-Caucasian populations.
METHODS: A total of 320 SNPs from the PADI locus (including PADI1, PADI2, PADI3, PADI4 and PADI6 genes) were genotyped in 1,238 RA cases and 1,571 control subjects from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) case-control study. Additionally, we conducted meta-analysis of our data together with the previously published studies of RA from East Asian populations.
RESULTS: The overall odds ratio (ORoverall) for the PADI4 (rs2240340) allelic model was 1.11 (95% confidence interval (CI) = 1.00 to 1.23, P = 0.04) and for the genotypic model was 1.20 (95% CI = 1.01 to 1.44, P = 0.04). Haplotype analysis for four selected PADI4 SNPs revealed a significant association of one with susceptibility (P = 0.001) and of another with a protective effect (P = 0.02). The RA susceptibility was further confirmed when combined meta-analysis was performed using these data together with data from five previously published studies from Asia comprising 5,192 RA cases and 4,317 control subjects (ORoverall = 1.23 (95% CI = 1.16 to 1.31, Pheterogeneity = 0.08) and 1.31 (95% CI = 1.20 to 1.44, Pheterogeneity = 0.32) in allele and genotype-based models, respectively). In addition, we also detected a novel association of PADI2 genetic variant rs1005753 with RA (ORoverall = 0.87 (95% CI = 0.77 to 0.99)).
CONCLUSION: Our study demonstrates an association between PADI4 and RA in the multiethnic population from South East Asia and suggests additional association with a PADI2 gene. The study thus provides further support for the notion that polymorphisms in genes for enzymes responsible for citrullination contribute to RA development in multiple populations of Asian descent.

Matched MeSH terms: Autoantibodies/immunology
Fulltext DNA methylation mediates genotype and smoking interaction in the development of anti-citrullinated peptide antibody-positive rheumatoid arthritis

Meng W, Zhu Z, Jiang X, Too CL, Uebe S, Jagodic M, et al.

Arthritis Res Ther, 2017 03 29;19(1):71.
PMID: 28356135 DOI: 10.1186/s13075-017-1276-2

BACKGROUND: Multiple factors, including interactions between genetic and environmental risks, are important in susceptibility to rheumatoid arthritis (RA). However, the underlying mechanism is not fully understood. This study was undertaken to evaluate whether DNA methylation can mediate the interaction between genotype and smoking in the development of anti-citrullinated peptide antibody (ACPA)-positive RA.

METHODS: We investigated the gene-smoking interactions in DNA methylation using 393 individuals from the Epidemiological Investigation of Rheumatoid Arthritis (EIRA). The interaction between rs6933349 and smoking in the risk of developing ACPA-positive RA was further evaluated in a larger portion of the EIRA (1119 controls and 944 ACPA-positive patients with RA), and in the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) (1556 controls and 792 ACPA-positive patients with RA). Finally, mediation analysis was performed to investigate whether DNA methylation of cg21325723 mediates this gene-environment interaction on the risk of developing of ACPA-positive RA.

RESULTS: We identified and replicated one significant gene-environment interaction between rs6933349 and smoking in DNA methylation of cg21325723. This gene-smoking interaction is a novel interaction in the risk of developing ACPA-positive in both Caucasian (multiplicative P value = 0.056; additive P value = 0.016) and Asian populations (multiplicative P value = 0.035; additive P value = 0.00027), and it is mediated through DNA methylation of cg21325723.

CONCLUSIONS: We showed that DNA methylation of cg21325723 can mediate the gene-environment interaction between rs6933349 and smoking, impacting the risk of developing ACPA-positive RA, thus being a potential regulator that integrates both internal genetic and external environmental risk factors.

Matched MeSH terms: Autoantibodies/immunology*

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