Displaying publications 21 - 40 of 63 in total

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  1. Identification of immune response-related genes and signalling pathways in spleen of Vibrio parahaemolyticus-infected Epinephelus fuscoguttatus (Forskal) by next-generation sequencing
    Low CF, Mariana NS, Maha A, Chee HY, Fatimah MY
    J Fish Dis, 2016 Mar;39(3):389-94.
    PMID: 25786532 DOI: 10.1111/jfd.12359
    Matched MeSH terms: Histocompatibility Antigens Class II/genetics*
  2. Fulltext Buccal swab as a suitable source of genomic DNA for screening of selected human leukocyte antigen (HLA) alleles
    Vivek Prasad, Lam Yan Shim, Sethu Thakachy Subha, Fazlina Nordin, Maha Abdullah
    Malaysian Journal of Medicine and Health Sciences, 2019;15(108):46-46.
    MyJurnal
    Introduction: Human leukocyte antigens (HLA) are a group of unique transmembrane glycoproteins that are ex-pressed on the surface of virtually all types of cells within the human body. These molecules are encoded by a set of highly polymorphic gene sequences known also as the major histocompatibility complex (MHC) and play an essential role in the presentation of antigenic peptides to immune cells for recognition and response. In recent years, various HLA alleles have been found to be associated with different autoimmune and inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus (SLE) and allergic rhinitis. Identification of these alleles via HLA typing is necessary for initial screening and diagnosis purposes. Besides that, HLA typing is also used to determine compatibility matching between a donor and a recipient for tissue/organ transplantations in order to prevent graft rejection. Therefore, good quality and quantity of genomic DNA is required. In most scenarios, peripheral blood is chosen as the most reliable source of DNA for analysis, however this approach is seen as invasive and may cause pain and anxiety among the patients, particularly young children and weak subjects. Hence, derivation of genomic DNA from buccal cells as an alternative source material is becoming increasingly popular, especially in PCR-based genetic assays. Some of the most commonly described methods to collect buccal cells include using oral swabs, cytological brushes, mouthwashes and treated cards. Each technique yields varying quantities of DNA with diverse purity levels. In this study, we aim to evaluate the amount and purity of genomic DNA extracted from buccal swabs and brushes as well as blood for screening of selected HLA class II alleles. Methods: Cheek cell samples were col-lected using sterile foam tipped buccal swabs (Whatman) and buccal collection brushes (Gentra Puregene) whereas peripheral blood samples were withdrawn following routine venipuncture techniques. All samples were subjected to DNA extraction according to modified commercial kit protocols. Screening of selected HLA-DRB1 alleles was con-ducted via PCR with sequence-specific primers as established by Bunce et al. 1995. Results: There was no significant difference (p > 0.05) in the total DNA yield obtained from blood and buccal swab samples, which were 17.57μg (± 8.66) and 13.28μg (± 4.81), respectively. All samples exhibited similar 260/280 ratios of about ~1.80 (p > 0.05). However, buccal brush samples contributed the least amount of DNA (0.29μg, ± 0.12) compared to other sources (p < 0.05). The pure genomic DNA isolated from both blood and buccal swab samples were successfully typed for low resolution HLA-DRB1 alleles. Conclusion: Buccal swabs provide good quantity and quality of DNA for screening of HLA alleles with high accuracy and thus can be utilized as a non-invasive substitute for venipuncture.
    Matched MeSH terms: Histocompatibility Testing; Major Histocompatibility Complex
  3. Prediction of promiscuous epitopes in NSP2 of Chikungunya virus: An in-silico approach
    Fazal F, Anwar T, Waheed Y, Parvaiz F
    Trop Biomed, 2020 Sep 01;37(3):566-577.
    PMID: 33612772 DOI: 10.47665/tb.37.3.566
    This study is focused towards developing a global consensus sequence of nonstructural protein 2 (NSP2), a protease of Chikungunya Virus (CHIKV) and predict immunogenic promiscuous T-cell epitopes based on various bioinformatics tools. To date, no epitope data is available for the Chikungunya virus in the IEDB database. In this study, 100 available nucleotide sequences of NSP2-CHIKV belonging to different strains were downloaded from the National Centre for Biotechnology Information (NCBI) database. The nucleotide sequences were subjected to translated sequencing using the EXPASY tool followed by protein alignment using the CLC workbench and a global consensus sequence for the respective protein was developed. IEDB tool was used to predict HLA-I and HLA-II binding promiscuous epitopes from the consensus sequence of NSP2-CHIKV. Thirty-four B-cell based epitopes are predicted and the promiscuous epitope is VVDTTGSTKPDPGD at position 341-354. Twenty-six MHC-I short peptide epitopes are predicted to bind with HLA-A. The promiscuous epitopes predicted to bind with HLA-A*01:01 are VTAIVSSLHY, SLSESATMVY, FSKPLVYY, QPTDHVVGEY at positions 317-326, 84-93, 535-544 and 15-24 with percentile ranks 0.17, 0.39, 0.51 and 0.81, respectively. Twenty-four MHC-II short peptide epitopes are predicted for HLA-DRB. The promiscuous epitope predicted to bind with HLA-DRB*01:01 is VVGEYLVLSPQTVLRS from 20-35 with a lowest percentile rank of 0.01. These predicted epitopes can be effective targets towards development of vaccine against CHIKV. Epitopes predicted in this study displayed good binding affinity, antigenicity and promiscuity for the HLA classes. These predicted epitopes can prove to be translationally important towards the development of CHIKV.
    Matched MeSH terms: Histocompatibility Antigens Class II; Histocompatibility Antigens Class I
  4. Characterisation of maternal human leukocyte antigen class I antibodies in suspected foetal and neonatal alloimmune thrombocytopenia
    Refsum E, Mörtberg A, Dahl J, Meinke S, Auvinen MK, Westgren M, et al.
    Transfus Med, 2017 Feb;27(1):43-51.
    PMID: 27862486 DOI: 10.1111/tme.12375
    OBJECTIVES: To investigate the specificities and level of HLA class I antibodies in selected cases referred for suspected foetal and neonatal alloimmune thrombocytopenia (FNAIT).

    BACKGROUND: FNAIT occurs in 1 : 1-2000 live births, whereas maternal immunisation against human leukocyte antigen (HLA) class I is common. Whether HLA class I antibodies alone can cause FNAIT is debatable.

    MATERIAL AND METHODS: A total of 260 patient samples were referred between 2007 and 2012. Referrals with maternal HLA class I antibodies and no other cause for the neonatal thrombocytopenia were included for analysis (cases, n = 23). HPA-1a negative mothers were excluded. Control groups were screened positive mothers of healthy neonates (controls, n = 33) and female blood donors (blood donors, n = 19). LABScreen single antigen HLA class I beads was used for antibody analysis. Clinical records were reviewed for cases.

    RESULTS: All groups had broad antibody reactivity. Cases had more antibodies with high SFI levels compared with the controls (SFI>9999; medians 26, 6 and 0; P 

    Matched MeSH terms: Histocompatibility Antigens Class I*
  5. Charlie Loke: contributions from Tennis Court Road--past, present and future
    Moffett A
    Placenta, 2003 Apr;24 Suppl A:S4-9.
    PMID: 12842407
    Matched MeSH terms: Histocompatibility Antigens Class I/metabolism
  6. Different serotypes of dengue viruses differently regulate the expression of the host cell antigen processing machinery
    Gan CS, Yusof R, Othman S
    Acta Trop, 2015 Sep;149:8-14.
    PMID: 25981524 DOI: 10.1016/j.actatropica.2015.05.005
    Dengue virus (DV) infection demonstrates an intriguing virus-induced intracellular membrane alteration that results in the augmentation of major histocompatibility complex (MHC) class I-restricted antigen presentation. As oppose to its biological function in attracting CD8(+) T-cells, this phenomenon appears to facilitate the immune evasion. However, the molecular events that attribute to the dysregulation of the antigen presenting mechanism (APM) by DV remain obscure. In this study, we aimed to characterize the host cell APM upon infection with all serotypes of whole DV. Cellular RNA were isolated from infected cells and the gene expressions of LMP2, LMP7, TAP1, TAP2, TAPBP, CALR, CANX, PDIA3, HLA-A and HLA-B were analyzed via quantitative PCR. The profiles of the gene expression were further validated. We showed that all four DV serotypes modulate host APM at the proteasomal level with DV2 showing the most prominent expression profile.
    Matched MeSH terms: Histocompatibility Antigens Class I/genetics*; Histocompatibility Antigens Class I/immunology
  7. HLA-B*15:349:02, a novel variant of HLA-B*15, discovered in a Singaporean Malay bone marrow donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 09;96(3):344-345.
    PMID: 32212215 DOI: 10.1111/tan.13879
    One nucleotide substitution in codon 112 of HLA-B*15:349:01 results in a novel allele, HLA-B*15:349:02.
    Matched MeSH terms: Histocompatibility Testing
  8. HLA-DQB1*06:132, an HLA-DQB1*06 variant, discovered in a Singaporean Malay bone marrow donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 08;96(2):243-244.
    PMID: 32250029 DOI: 10.1111/tan.13889
    One nucleotide substitution in codon 38 of HLA-DQB1*06:01:01:01 results in a novel allele, HLA-DQB1*06:132.
    Matched MeSH terms: Histocompatibility Testing
  9. HLA-B*38:64, an HLA-B*38 variant, detected in a Singaporean Malay unrelated hematopoietic stem cell donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 08;96(2):217-218.
    PMID: 32227685 DOI: 10.1111/tan.13873
    One nucleotide substitution in codon 89 of HLA-B*38:02:01:01 results in a novel allele, HLA-B*38:64.
    Matched MeSH terms: Histocompatibility Testing
  10. Discovery of HLA-B*35:368, a novel HLA-B*35 variant, in a Singaporean Malay hematopoietic stem cell donor
    Kaur A, Cho L, Cereb N, Lin PY, Yang KL
    HLA, 2020 07;96(1):94-95.
    PMID: 32166893 DOI: 10.1111/tan.13862
    DNA substitutions from codons 69 to 71 of HLA-B*35:05:01:01 result in a novel allele, HLA-B*35:368.
    Matched MeSH terms: Histocompatibility Testing
  11. Prevalence and risk factors of antibodies towards HLA Class I and Class II in Malaysian renal transplant candidates
    Khairul-Fahmy N, Ismail J, Koay BT, Md-Zakariah MZ, Mansor S, Zulkifli N, et al.
    BMC Nephrol, 2023 Feb 24;24(1):42.
    PMID: 36829106 DOI: 10.1186/s12882-023-03085-6
    Antibody-mediated rejection (AMR) still persists as the major hurdle towards successful renal allograft survival. This paper aims to report on the HLA antibody landscape of renal transplant candidates in Malaysia. A total of 2,219 adult samples from 2016 to 2019 were analysed for anti-HLA antibodies using solid-phase assay. Our findings highlight the prevalence and risk factors for antibodies against HLA antigens in renal transplant settings, which could be beneficial for selecting compatible recipients from deceased organ donors. To the best of our knowledge, this study is the first to demonstrate that ethnic Malay and Chinese showed significantly higher prevalence of anti-HLA antibodies. Based on our multivariate analysis: (i) female gender was associated with higher risk for panel reactive antibodies (PRAs) against Class I, Class II, and Class I and II (p 
    Matched MeSH terms: Histocompatibility Antigens Class I
  12. Effects of macrophage colony-stimulating factor on microglial responses to lipopolysaccharide and beta amyloid
    Vidyadaran S, Ooi YY, Subramaiam H, Badiei A, Abdullah M, Ramasamy R, et al.
    Cell Immunol, 2009;259(1):105-10.
    PMID: 19577228 DOI: 10.1016/j.cellimm.2009.06.005
    A challenge for studies involving microglia cultures is obtaining sufficient cells for downstream experiments. Macrophage colony-stimulating factor (M-CSF) has been used to improve yield of microglia in culture. However, the effects of M-CSF on activation profiles of microglia cultures are still unclear. Microglia activation is characterised by upregulation of co-stimulatory molecules and an inflammatory phenotype. The aim of this study is to demonstrate whether M-CSF supplementation alters microglial responses in resting and activated conditions. Microglia derived from mixed glia cultures and the BV-2 microglia cell line were cultivated with/without M-CSF and activated with lipopolysaccharide (LPS) and beta amyloid (Abeta). We show M-CSF expands primary microglia without affecting microglial responses to LPS and Abeta, as shown by the comparable expression of MHC class II and CD40 to microglia grown without this growth factor. M-CSF supplementation in BV-2 cells had no effect on nitric oxide (NO) production. Therefore, M-CSF can be considered for improving microglia yield in culture without introducing activation artefacts.
    Matched MeSH terms: Histocompatibility Antigens Class II/metabolism
  13. In vitro characterization of chicken bone marrow-derived dendritic cells following infection with very virulent infectious bursal disease virus
    Yasmin AR, Yeap SK, Tan SW, Hair-Bejo M, Fakurazi S, Kaiser P, et al.
    Avian Pathol, 2015;44(6):452-62.
    PMID: 26305169 DOI: 10.1080/03079457.2015.1084997
    Infectious bursal disease is caused by infectious bursal disease virus (IBDV), an immunosuppressive virus that targets immune cells such as B cells and macrophages. However, the involvement of dendritic cells (DCs) during IBDV infection is not well understood. In this study the in vitro effects of live and inactivated very virulent IBDV (vvIBDV) UPM0081 on bone marrow-derived DCs (BM-DC) were characterized and compared with BM-DC treated with lipopolysaccharide (LPS). Morphologically, BM-DC treated with LPS and vvIBDV showed stellate shape when compared to immature BM-DC. In addition, LPS-treated and both live and inactivated vvIBDV-infected BM-DC expressed high levels of double positive CD86 and major histocompatibility complex class II antigens (>20%). vvIBDV-infected BM-DC showed significantly higher numbers of apoptotic cells compared to LPS. Replication of vvIBDV was detected in the infected BM-DC as evidenced by the increased expression of VP3 and VP4 IBDV antigens based on flow cytometry, real-time polymerase chain reaction and immunofluorescence tests. Levels of different immune-related genes such as interleukin-1β (IL-1β), CXCLi2 (IL-8), IL-18, interferon gamma (IFN-γ, IL-12α, CCR7 and Toll-like receptor-3 (TLR3) were measured after LPS and vvIBDV treatments. However, marked differences were noticed in the onset and intensity of the gene expression between these two treatment groups. LPS was far more potent than live and inactivated vvIBDV in inducing the expression of IL-1β, IL-18 and CCR7 while expression of Th1-like cytokines, IFN-γ and IL-12α were significantly increased in the live vvIBDV treatment group. Meanwhile, the expression of TLR3 was increased in live vvIBDV-infected BM-DC as compared to control. Inactivated vvIBDV-treated BM-DC failed to stimulate IFN-γ, IL-12α and TLR3 expressions. This study suggested that BM-DC may serve as another target cells during IBDV infection which require further confirmation via in vivo studies.
    Matched MeSH terms: Histocompatibility Antigens Class II; Major Histocompatibility Complex
  14. Fulltext SNP variants associated with non-Hodgkin lymphoma (NHL) correlate with human leukocyte antigen (HLA) class II expression
    Ten LC, Chin YM, Tai MC, Chin EF, Lim YY, Suthandiram S, et al.
    Sci Rep, 2017 01 31;7:41400.
    PMID: 28139690 DOI: 10.1038/srep41400
    Large consortia efforts and genome-wide association studies (GWASs) have linked a number of genetic variants within the 6p21 chromosomal region to non-Hodgkin lymphoma (NHL). Complementing these efforts, we genotyped previously reported SNPs in the human leukocyte antigen (HLA) class I (rs6457327) and class II (rs9271100, rs2647012 and rs10484561) regions in a total of 1,145 subjects (567 NHL cases and 578 healthy controls) from two major ethnic groups in Malaysia, the Malays and the Chinese. We identified a NHL-associated (PNHL_add = 0.0008; ORNHL_add = 0.54; 95% CI = 0.37-0.77) and B-cell associated (PBcell_add = 0.0007; ORBcell_add = 0.51; 95% CI = 0.35-0.76) SNP rs2647012 in the Malaysian Malays. In silico cis-eQTL analysis of rs2647012 suggests potential regulatory function of nearby HLA class II molecules. Minor allele rs2647012-T is linked to higher expression of HLA-DQB1, rendering a protective effect to NHL risk. Our findings suggest that the HLA class II region plays an important role in NHL etiology.
    Matched MeSH terms: Histocompatibility Antigens Class II/genetics*
  15. Fulltext Novel defect in phosphatidylinositol 4-kinase type 2-alpha (PI4K2A) at the membrane-enzyme interface is associated with metabolic cutis laxa
    Mohamed M, Gardeitchik T, Balasubramaniam S, Guerrero-Castillo S, Dalloyaux D, van Kraaij S, et al.
    J Inherit Metab Dis, 2020 11;43(6):1382-1391.
    PMID: 32418222 DOI: 10.1002/jimd.12255
    Inherited cutis laxa, or inelastic, sagging skin is a genetic condition of premature and generalised connective tissue ageing, affecting various elastic components of the extracellular matrix. Several cutis laxa syndromes are inborn errors of metabolism and lead to severe neurological symptoms. In a patient with cutis laxa, a choreoathetoid movement disorder, dysmorphic features and intellectual disability we performed exome sequencing to elucidate the underlying genetic defect. We identified the amino acid substitution R275W in phosphatidylinositol 4-kinase type IIα, caused by a homozygous missense mutation in the PI4K2A gene. We used lipidomics, complexome profiling and functional studies to measure phosphatidylinositol 4-phosphate synthesis in the patient and evaluated PI4K2A deficient mice to define a novel metabolic disorder. The R275W residue, located on the surface of the protein, is involved in forming electrostatic interactions with the membrane. The catalytic activity of PI4K2A in patient fibroblasts was severely reduced and lipid mass spectrometry showed that particular acyl-chain pools of PI4P and PI(4,5)P2 were decreased. Phosphoinositide lipids play a major role in intracellular signalling and trafficking and regulate the balance between proliferation and apoptosis. Phosphatidylinositol 4-kinases such as PI4K2A mediate the first step in the main metabolic pathway that generates PI4P, PI(4,5)P2 and PI(3,4,5)P3 . Although neurologic involvement is common, cutis laxa has not been reported previously in metabolic defects affecting signalling. Here we describe a patient with a complex neurological phenotype, premature ageing and a mutation in PI4K2A, illustrating the importance of this enzyme in the generation of inositol lipids with particular acylation characteristics.
    Matched MeSH terms: Minor Histocompatibility Antigens/genetics*
  16. Expression profile of immune-related genes in Lates calcarifer infected by Cryptocaryon irritans
    Mohd-Shaharuddin N, Mohd-Adnan A, Kua BC, Nathan S
    Fish Shellfish Immunol, 2013 Mar;34(3):762-9.
    PMID: 23296118 DOI: 10.1016/j.fsi.2012.11.052
    Cryptocaryon irritans causes Cyptocaryonosis or white spot disease in a wide range of marine fish including Lates calcarifer (Asian seabass). However, the immune response of this fish to the parasite is still poorly understood. In this study, quantitative polymerase chain reaction (qPCR) was performed to assess the expression profile of immune-related genes in L. calcarifer infected by C. irritans. A total of 21 immune-related genes encoding various functions in the fish immune system were utilized for the qPCR analysis. The experiment was initiated with the infection of juvenile fish by exposure to theronts from 200 C. irritans cysts, and non-infected juvenile fish were used as controls. Spleen, liver, gills and kidney tissues were harvested at three days post-infection from control and infected fish. In addition, organs were also harvested on day-10 post-infection from fish that had been allowed to recover from day-4 up to day-10 post-infection. L. calcarifer exhibited pathological changes on day-3 post-infection with the characteristic presence of white spots on the entire fish body, excessive mucus production and formation of a flap over the fish eye. High quality total RNA was extracted from all tissues and qPCR was performed. The qPCR analysis on the cohort of 21 immune-related genes of the various organs harvested on day-3 post-infection demonstrated that most genes were induced significantly (p 
    Matched MeSH terms: Histocompatibility Antigens Class II/genetics; Histocompatibility Antigens Class II/metabolism
  17. Fulltext The association of the HLA class II antigens with clinical and autoantibody expression in Malaysian Chinese patients with systemic lupus erythematosus
    Azizah MR, Ainoi SS, Kuak SH, Kong NCT, Normaznah Y, Rahim MN
    Asian Pac J Allergy Immunol, 2001 Jun;19(2):93-100.
    PMID: 11699726
    The frequency of the HLA class II antigens/alleles (HLA-DR, DQ and DP) were studied in 70 Malaysian Chinese patients with systemic lupus erythematosus (SLE) to examine the contribution of these genes to disease susceptibility, their clinical expression and Immunological responses. This was done using modified PCR-RFLP technique. These samples were then compared with 66 ethnically matched controls. We found a strong association of the DQA1*0102 (p corr = 0.032, rr = 3.39), DQB1*0501 (p corr = 0.003, rr = 4.55), *0601 (p corr = 0.006, rr = 4.22) and DPB1* 0901(p corr = 0.02, rr = 4.58) with SLE. Clinically, we found a strong association of DR2 and DQA1*0301 with renal involvement and DQA1*0102 with alopecia. Immunologically, statistical analysis (Chi-square test ) showed a strong association of DQA1*0102 with anti-Ro/La antibodies while DQA1*0301 was observed to be strongly associated with antibodies to ds DNA. DQA1*0102 was found more frequently in those with a later disease onset (30 years of age or above). From these data we suggest that the HLA class II genes play a role in conferring disease susceptibility and clinical and immunological expression.
    Study site: SLE clinics, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
    Matched MeSH terms: Histocompatibility Antigens Class II/genetics; Histocompatibility Antigens Class II/immunology*
  18. Fulltext Genetic risk factors of systemic lupus erythematosus in the Malaysian population: a minireview
    Chai HC, Phipps ME, Chua KH
    Clin. Dev. Immunol., 2012;2012:963730.
    PMID: 21941582 DOI: 10.1155/2012/963730
    SLE is an autoimmune disease that is not uncommon in Malaysia. In contrast to Malays and Indians, the Chinese seem to be most affected. SLE is characterized by deficiency of body's immune response that leads to production of autoantibodies and failure of immune complex clearance. This minireview attempts to summarize the association of several candidate genes with risk for SLE in the Malaysian population and discuss the genetic heterogeneity that exists locally in Asians and in comparison with SLE in Caucasians. Several groups of researchers have been actively investigating genes that are associated with SLE susceptibility in the Malaysian population by screening possible reported candidate genes across the SLE patients and healthy controls. These candidate genes include MHC genes and genes encoding complement components, TNF, FcγR, T-cell receptors, and interleukins. However, most of the polymorphisms investigated in these genes did not show significant associations with susceptibility to SLE in the Malaysian scenario, except for those occurring in MHC genes and genes coding for TNF-α, IL-1β, IL-1RN, and IL-6.
    Matched MeSH terms: Major Histocompatibility Complex/genetics
  19. Strategies for evaluating B*18 allelic diversity by sequence-based typing applied to studies of a population from Singapore and African-Americans
    Hou L, Tu B, Ling G, Tang T, Cao K, Steiner NK, et al.
    Tissue Antigens, 2006 Jan;67(1):66-9.
    PMID: 16451205
    Strategies to resolve B*18 alleles which carry a deletion in intron 1 close to the 5' end of exon 2 relative to other HLA-B alleles or a null allele mutation in exon 1 and to resolve ambiguities among allele combinations including B*18 are described. B*18 allele frequencies from volunteer donors recruited for two hematopoietic stem cell registries show the presence of two alleles, B*180101 and B*1802, in a population from Singapore and only B*180101 in African-Americans.
    Matched MeSH terms: Histocompatibility Testing*
  20. 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: Major Histocompatibility Complex/genetics
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