The combinatorial diversity of KIR and HLA class I allotypes in Peninsular Malaysia.

Killer cell immunoglobulin-like receptors (KIRs) interact with polymorphic human leucocyte antigen (HLA) class I molecules, modulating natural killer (NK) cell functions and affecting both the susceptibility and outcome of immune-mediated diseases. The KIR locus is highly diverse in gene content, copy number and allelic polymorphism within individuals and across geographical populations. To analyse currently under-represented Asian and Pacific populations, we investigated the combinatorial diversity of KIR and HLA class I in 92 unrelated Malay and 75 Malaysian Chinese individuals from the Malay Peninsula. We identified substantial allelic and structural diversity of the KIR locus in both populations and characterized novel variations at each analysis level. The Malay population is more diverse than Malay Chinese, likely representing a unique history including admixture with immigrating populations spanning several thousand years. Characterizing the Malay population are KIR haplotypes with large structural variants present in 10% individuals, and KIR and HLA alleles previously identified in Austronesian populations. Despite the differences in ancestries, the proportion of HLA allotypes that serve as KIR ligands is similar in each population. The exception is a significantly reduced frequency of interactions of KIR2DL1 with C2+ HLA-C in the Malaysian Chinese group, caused by the low frequency of C2+ HLA. One likely implication is a greater protection from preeclampsia, a pregnancy disorder associated with KIR2DL1, which shows higher incidence in the Malay than in the Malaysian Chinese. This first complete, high-resolution, characterization of combinatorial diversity of KIR and HLA in Malaysians will form a valuable reference for future clinical and population studies.

Genetic variability of immune-related lncRNAs: polymorphisms in LINC-PINT and LY86-AS1 are associated with pemphigus foliaceus susceptibility.

Pemphigus foliaceus (PF) is an autoimmune blistering disease of the skin, clinically characterized by erosions and, histopathologically, by acantholysis. PF is endemic in the Brazilian Central-Western region. Numerous single nucleotide polymorphisms (SNPs) have been shown to affect the susceptibility for PF, including SNPs at long non-coding RNA (lncRNA) genes, which are known to participate in many physiological and pathogenic processes, such as autoimmunity. Here, we investigated whether the genetic variation of immune-related lncRNA genes affects the risk for endemic and sporadic forms of PF. We analysed 692 novel SNPs for PF from 135 immune-related lncRNA genes in 227 endemic PF patients and 194 controls. The SNPs were genotyped by Illumina microarray and analysed by applying logistic regression at additive model, with correction for sex and population structure. Six associated SNPs were also evaluated in an independent German cohort of 76 sporadic PF patients and 150 controls. Further, we measured the expression levels of two associated lncRNA genes (LINC-PINT and LY86-AS1) by quantitative PCR, stratified by genotypes, in peripheral blood mononuclear cells of healthy subjects. We found 27 SNPs in 11 lncRNA genes associated with endemic PF (p < .05 without overlapping with protein-coding genes). Among them, the LINC-PINT SNP rs10228040*A (OR = 1.47, p = .012) was also associated with increased susceptibility for sporadic PF (OR = 2.28, p = .002). Moreover, the A+ carriers of LY86-AS1*rs12192707 mark lowest LY86-AS1 RNA levels, which might be associated with a decreasing autoimmune response. Our results suggest a critical role of lncRNA variants in immunopathogenesis of both PF endemic and sporadic forms.

Screening the full leucocyte receptor complex genomic region revealed associations with pemphigus that might be explained by gene regulation.

Pemphigus foliaceus (PF) is a blistering autoimmune skin disease rare in most of the world but endemic in certain regions of Brazil. PF is characterized by the detachment of epidermal cells and the presence of autoantibodies against desmoglein 1. In previous studies, we have shown that genetic polymorphisms and variable expression levels of certain leucocyte receptor complex (LRC) genes were associated with PF. However, the role of the LRC on PF susceptibility remained to be investigated. Here, we analysed 527 tag single nucleotide polymorphisms (SNPs) distributed within the 1·5 Mb LRC. After quality control, a total of 176 SNPs were analysed in 229 patients with PF and 194 controls. Three SNPs were associated with differential susceptibility to PF. The intergenic variant rs465169 [odds ratio (OR) = 1·50; P = 0·004] is located in a region that might regulate several immune-related genes, including VSTM1, LILRB1/2, LAIR1/2, LILRA3/4 and LENG8. The rs35336528 (OR = 3·44; P = 0·009) and rs1865097 (OR = 0·57; P = 0·005) SNPs in LENG8 and FCAR genes, respectively, were also associated with PF. Moreover, we found four haplotypes with SNPs within the KIR3DL2/3, LAIR2 and LILRB1 genes associated with PF (P < 0·05), which corroborate previously reported associations. Thus, our results confirm the importance of the LRC for differential susceptibility to PF and reveal new markers that might influence expression levels of several LRC genes, as well as candidates for further functional studies.

Complement Receptor 1 (CR1, CD35) Polymorphisms and Soluble CR1: A Proposed Anti-inflammatory Role to Quench the Fire of "Fogo Selvagem" Pemphigus Foliaceus.

Pemphigus foliaceus is an autoimmune disease that is sporadic around the world but endemic in Brazil, where it is known as fogo selvagem (FS). Characterized by autoantibodies against the desmosomal cadherin desmoglein 1, FS causes painful erosions, and crusts that may be widespread. The recognition of antigens, including exposed sugar moieties, activates the complement system. Complement receptor 1 (CR1, CD35), which is responsible for the Knops blood group on erythrocytes (York and McCoy antigens), is also expressed by antigen-presenting cells. This regulates the complement system by removing opsonized antigens, blocking the final steps of the complement cascade. Membrane-bound CR1 also fosters antigen presentation to B cells, whereas soluble CR1 has anti-inflammatory properties. CR1 gene polymorphisms have been associated with susceptibility to complex diseases. In order to investigate the association of CR1 polymorphisms with FS susceptibility, we developed a multiplex sequence-specific assay to haplotype eleven polymorphisms in up to 367 FS patients and 242 controls from an endemic area and 289 from a non-endemic area. We also measured soluble CR1 (sCR1) in the serum of 53 FS patients and 27 controls and mRNA levels in the peripheral blood mononuclear cells of 63 genotyped controls. The haplotypes CR1*3B2B (with the York antigen-encoded by p.1408Met) and CR1*3A2A (with p.1208Arg) were associated with protection against FS (OR = 0.57, P = 0.027, and OR = 0.46, P = 0.014, respectively). In contrast, the CR1*1 haplotype (with the McCoy antigen - encoded by p.1590Glu) was associated with FS susceptibility (OR = 4.97, P < 0.001). Heterozygote rs12034383*A/G individuals presented higher mRNA expression than homozygotes with the G allele (P = 0.04). The lowest sCR1 levels occurred in patients with active disease before treatment (P = 0.036). Patients in remission had higher levels of sCR1 than did healthy controls (P = 0.013). Among those under treatment, patients with localized lesions also presented higher sCR1 levels than those with generalized lesions (P = 0.0073). In conclusion, the Knops blood group seems to modulate susceptibility to the disease. Furthermore, corticosteroid treatment might increase sCR1 serum levels, and higher levels may play an anti-inflammatory role in patients with FS, limiting the distribution of lesions. Based on these results, we suggest CR1 as a potential new therapeutic target for the treatment of FS.

Association of PDCD1 polymorphism to systemic lupus erythematosus and rheumatoid arthritis susceptibility.

OBJECTIVE: This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population. METHODS: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05. RESULTS: The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data. CONCLUSION: There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

Association of PDCD1 polymorphism to Systemic Lupus Erythematosus and Rheumatoid Arthritis susceptibility. / Associação entre o polimorfismo do gene PDCD1 e a susceptibilidade ao lúpus eritematoso sistêmico e à artrite reumatoide.

OBJECTIVE: This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population. METHODS: Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg Equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05. RESULTS: The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data. CONCLUSION: There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

Lack of association between interleukin-18 polymorphisms and rheumatoid arthritis.

OBJECTIVE: To assess the association of the polymorphisms of the interleukin-18 (IL-18) gene with rheumatoid arthritis (RA) and with risk factors for cardiovascular diseases (CVD). METHODS: This sample comprised 97 patients with RA and 151 healthy controls. In the patients, risk factors for CVD were analyzed, such as cholesterol levels, arterial hypertension, smoking habit, C-reactive protein (CRP) level, and rheumatoid factor. DNA was extracted and the single nucleotide polymorphisms (SNP) at the -607C/A and -137G/C positions of the IL-18 gene were assessed in both groups. The Hardy-Weinberg equilibrium (HWE) was calculated and the odds ratio (OR) test performed, considering a 95% CI and P < 0.05. RESULTS: The frequencies of the -607A allele in patients with RA and in controls were 0,443 and 0.424, respectively, and of the -137C allele, 0.304 and 0.291, respectively. The genotype frequencies were in HWE, except for controls in the -137 locus (P = 0.006). Association of the polymorphisms of the IL-18 gene was found with neither RA nor risk factors for CVD, including cholesterol level and CRP (P > 0.05). In addition, more smokers were found among patients with RA as compared with controls (OR = 1.691; P = 0.088), and the CRP levels were slightly higher in patients who smoked than in patients who did not (OR = 2.673; P = 0.061). CONCLUSIONS: In this sample of patients with RA in the South of Brazil, association of the polymorphisms of the IL-18 gene was observed with neither RA nor risk factors for CVD.

Association of PDCD1 polymorphism to systemic lupus erythematosus and rheumatoid arthritis susceptibility / Associação entre o polimorfismo do gene PDCD1 e a susceptibilidade ao lúpus eritematoso sistêmico e à artrite reumatoide

ABSTRACT Objective: This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population. Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p ≤ 0.05. Results: The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data. Conclusion: There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

RESUMO Objetivo: Este estudo teve como objetivo analisar a relação entre o polimorfismo do gene PDCD1 (programmed cell death 1) (PD1.3G/A - rs11568821) com características do lúpus eritematoso sistêmico (LES) e da artrite reumatoide (AR) em uma população do sul do Brasil. Métodos: A técnica de PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Lenght Polymorphism) foi utilizada para analisar amostras de 95 pacientes com LES e 87 com AR, assim como em 128 indivíduos do grupo controle de Santa Catarina, sul do Brasil. Foi analisada a probabilidade de equilíbrio de Hardy-Weinberg (EHW) e a odds ratio (OR), considerando um IC 95% e p ≤ 0,05. Resultados: As frequências alélicas PD1.3 A foram de 0,095 (LES), 0,115 (AR) e 0,078 (controles). Os genótipos do grupo controle estavam em EHW, enquanto aqueles dos pacientes com LES e AR não estavam. No entanto, não foi encontrada associação entre o polimorfismo PD1.3 e a suscetibilidade ao LES ou à AR, nem com dados clínicos ou epidemiológicos. Conclusão: Não foi encontrada associação significativa entre o polimorfismo PD1.3 e a susceptibilidade ao LES ou à AR nessa população do sul do Brasil.

Ausência de associação entre os polimorfismos do gene interleucina-18 e artrite reumatoide / Lack of association between interleukin-18 polymorphisms and rheumatoid arthritis

OBJETIVO: Analisar a associação dos polimorfismos do gene interleucina-18 (IL-18) com artrite reumatoide (AR) e com fatores de risco de doenças cardiovasculares (DCV). MÉTODOS: A amostra foi constituída por 97 pacientes com AR e 151 controles saudáveis. Nos primeiros, foram analisados fatores de risco de DCV, tais como níveis do colesterol, hipertensão arterial, tabagismo e fator reumatoide, bem como o nível da proteína C-reativa (CRP). O DNA foi extraído e foram analisados os polimorfismos de nucleotídeo único (SNP) nas posições -607C/A e -137G/C do gene IL-18 em ambos os grupos. O equilíbrio de Hardy-Weinberg (EHW) e o odds ratio (OR) foram realizados, considerando IC 95% e P < 0,05. RESULTADOS: As frequências do alelo -607A nos pacientes com AR e nos controles foram de 0,443 e 0,424 e do alelo -137C foram de 0,304 e 0,291, respectivamente. As frequências do genótipo estavam em EHW, exceto em controles no locus -137 (P = 0,006). Não foi encontrada associação dos polimorfismos do gene IL-18 com AR, nem com fatores de risco de DCV, incluindo o nível do colesterol e de CRP (P > 0,05). Além disso, observaram-se mais indivíduos fumantes entre pacientes com AR em comparação aos controles (OR = 1,691; P = 0,088), e os níveis de CRP eram ligeiramente mais elevados em pacientes fumantes quando comparados aos de pacientes não fumantes (OR = 2,673; P = 0,061). CONCLUSÕES: Ao analisar uma amostra de pacientes com AR no sul do Brasil, não foi encontrada associação dos polimorfismos do gene IL-18 com AR, nem com os fatores de risco de DCV.

OBJECTIVE: To assess the association of the polymorphisms of the interleukin-18 (IL-18) gene with rheumatoid arthritis (RA) and with risk factors for cardiovascular diseases (CVD). METHODS: This sample comprised 97 patients with RA and 151 healthy controls. In the patients, risk factors for CVD were analyzed, such as cholesterol levels, arterial hypertension, smoking habit, C-reactive protein (CRP) level, and rheumatoid factor. DNA was extracted and the single nucleotide polymorphisms (SNP) at the -607C/A and -137G/C positions of the IL-18 gene were assessed in both groups. The Hardy-Weinberg equilibrium (HWE) was calculated and the odds ratio (OR) test performed, considering a 95% CI and P < 0.05. RESULTS: The frequencies of the -607A allele in patients with RA and in controls were 0,443 and 0.424, respectively, and of the -137C allele, 0.304 and 0.291, respectively. The genotype frequencies were in HWE, except for controls in the -137 locus (P = 0.006). Association of the polymorphisms of the IL-18 gene was found with neither RA nor risk factors for CVD, including cholesterol level and CRP (P > 0.05). In addition, more smokers were found among patients with RA as compared with controls (OR = 1.691; P = 0.088), and the CRP levels were slightly higher in patients who smoked than in patients who did not (OR = 2.673; P = 0.061). CONCLUSIONS: In this sample of patients with RA in the South of Brazil, association of the polymorphisms of the IL-18 gene was observed with neither RA nor risk factors for CVD.