M.F. González-Escribano

Association of vitamin D receptor genotypes with early onset rheumatoid arthritis.

The presence of certain vitamin D receptor (VDR) genotypes has been associated with low bone mineral density (BMD) in elderly populations as well as with accelerated bone loss in patients with rheumatoid arthritis (RA). In the present study, VDR genotypes from 120 Spanish patients with RA were investigated. Three VDR gene polymorphisms (BsmI, ApaI and TaqI) were investigated using polymerase chain reaction followed by enzymatic digestion. The distributions of VDR allelic frequencies were similar in patients and controls and therefore no influence of VDR polymorphisms on rheumatoid arthritis susceptibility could be demonstrated. However, in an analysis of the clinical features of the different VDR-related genetic subgroups, the BB/tt genotype, defined by the BsmI and TaqI restriction site polymorphisms, was identified to be weakly associated with an early onset RA in female patients. This VDR genotype has been associated with a low BMD level in various studies. When patients were stratified according to the presence of the shared HLA epitope SE, it was found that SE + female patients bearing the BB/tt genotype showed the earliest disease onset. The mechanisms by which the VDR polymorphism is associated with RA is unknown, but they could be related to the immunoregulatory properties of vitamin D.

TAP polymorphism in patients with Behçet's disease.

OBJECTIVE--To determine if susceptibility to Behçets disease (BD) is associated with polymorphism of HLA-DRB1, HLA-DQB1, DQB1, and TAP1 and TAP2 genes. METHODS--Fifty eight Spanish BD patients and 116 ethnically matched unrelated healthy subjects were typed at the HLA-DRB1 and HLA-DQB1 loci using polymerase chain reaction/sequence specific oligotyping (PCR/SSO). TAP1 and TAP2 alleles were assigned using amplification refractory mutation system-PCR. RESULTS--TAP1C was absent in BD patients, but was found in 12.1% of control subjects (pcorr < 0.05; relative risk = 0.06). Additionally, a linkage disequilibrium between HLA-DQB1*0501 and TAP2B was observed in BD patients (delta = 0.095, pcorr < 0.02), but not in the control group (delta = -0.0031, p > 0.05). CONCLUSIONS--The complete absence of TAP1C alleles in BD patients may indicate that TAP1 polymorphism is not without some significance in the development of BD. Furthermore, the existence of a linkage disequilibrium between HLA-DQB1*0501 and TAP2B in our patients suggests that the gene conferring susceptibility for BD is inherited as an extended haplotype in the population studied.

SLC11A1 promoter gene polymorphisms and fibrosis progression in chronic hepatitis C

Background and aims: The solute carrier family 11 member 1 (SLC11A1) gene (formerly Nramp1) encodes for the protein solute carrier family 11, member 1. It affects susceptibility and clinical outcome of autoimmune and infectious diseases. We investigated the possible role of the functional polymorphism located in the promoter region of SLC11A1 and tumour necrosis factor (TNF) genes in the progression of fibrosis in chronic hepatitis C. Methods: A total of 242 Caucasian Spanish patients with biopsy proven chronic hepatitis C and 194 healthy control subjects were genotyped for SLC11A1 and TNF promoter polymorphisms. Results: No significant differences in the distribution of frequencies among patient and control groups were observed. The SCL11A1 homozygous 2/2 genotype was rarely detected among patients showing advanced fibrosis (2/82; 2.4%) but was highly represented in those with mild fibrosis (29/160; 18.1%; odds ratio (OR) 8.85 (95% confidence interval (CI) 1.9–55.2, pc = 0.002). In patients carrying allele 3 of SLC11A1, the presence of −238 TNF A/G was associated with advanced fibrosis (14/26 (53.8%) v 68/216 (31.4%); OR 2.53 (95% CI 1.03–6.23); p = 0.02). Conclusions: SLC11A1 gene promoter polymorphism could influence fibrosis progression in chronic hepatitis C in that the homozygous genotype 2/2 exerts a protective effect against cirrhosis development. Also, the combination of TNF −238 A/G and the presence of allele 3 is conducive to progression to pre-cirrhotic or cirrhotic stages of the disease.

Association of the AIRE gene with susceptibility to rheumatoid arthritis in a European population: a case control study.

IntroductionAIRE is a transcriptional regulator playing a functional role in thymocyte education and negative selection by controlling the expression of peripheral antigens in the thymus. Recently, the AIRE gene was identified as a genetic risk factor for rheumatoid arthritis (RA) in genome wide association (GWA) studies performed in the Japanese population. According to the available data this association is restricted to the Asian population. However, different facts could influence the lack of association in Caucasian populations. The aim of this study was to further investigate the possible role of the AIRE gene in susceptibility to RA in a Caucasian population.MethodsA total of 472 Spanish Caucasian RA patients and 475 ethnically matched controls were included in the study. Three single-nucleotide polymorphisms (SNPs) (rs2776377, rs878081 and rs1055311) with a minor allele frequency >0.05 in the Caucasian population which were not included in the high-throughput platforms used in the GWA studies performed in susceptibility to RA, and two SNPs (rs2075876 and rs1800520) associated with RA in the Japanese population, were selected and genotyped using TaqMan assays.ResultsNo significant differences in the distribution of the alleles of rs2776377, rs2075876, rs1055311 and rs1800520 SNPs between RA patients and controls were observed. Nevertheless, the frequency of the C allele of rs878081 was significantly higher among RA patients (80.5% vs. 74.6% in the control group, pc = 0.012, OR = 1.41, 95%CI 1.13-1.75). Regarding the distribution of the rs878081 genotypes, a higher frequency of CC homozygous individuals was found in the RA patient group (65.56% vs. 56.47% in the control group, pc = 0.013, OR = 1.47, 95%CI 1.12-1.93). The in silico analysis predicted lower affinity to the binding-site of a motif of the transcription NF-κB family and lower transcription levels of AIRE gene for the rs878081C risk variantConclusionsOur findings suggest that the AIRE gene is associated with susceptibility to RA in the Spanish population. Probably, this association has not been detected in the European population in the GWA studies because the earliest high-throughput platforms did not include SNP suitable markers (e.g. rs878081).

Influence of the STAT3 genetic variants in the susceptibility to psoriatic arthritis and Behcet's disease.

OBJECTIVE Signal-transducer and activator of transcription protein 3 (STAT3) gene encodes a transducer and transcription factor that plays an important role in many cellular processes such as cell growth, apoptosis and immune response. Several STAT3 genetic variants have been associated to different autoimmune diseases. Our aim was to reveal the possible STAT3 influence in other immune-mediated diseases such as psoriatic arthritis (PsA) and Behcet disease (BD). METHODS The STAT3 rs744166 and rs2293152 polymorphisms were genotyped using predesigned TaqMan® assays in a total of 335 PsA patients, 217 BD patients, and 1844 ethnically matched healthy controls of Spanish Caucasian origin. RESULTS A statistically significant association of the STAT3 rs744166(∗)G allele with PsA was observed (P-value=1.36×10(-3), OR 1.35). The detected effect was more evident when the rs744166(∗)GG homozygote frequencies were compared between PsA patients and controls (genotype P-value=9.77×10(-5), OR 1.82). In contrast, the allele and genotypic distributions of rs744166 polymorphism showed no significant differences between patients with BD and control subjects (allelic P-value=0.80, OR 1.03). Additionally, no evidence of association was detected between the rs2293152 genetic variant and both studied diseases. CONCLUSION Our results suggest for the first time that the STAT3 gene might be involved in PsA but not in Behcets disease predisposition.

Insulin resistance predicts sustained virological response to treatment of chronic hepatitis C independently of the IL28b rs12979860 polymorphism

Insulin resistance has been strongly associated with the attainment of sustained viral response (SVR) in hepatitis C patients.

Donor-specific antibody detection: comparison of single antigen assay and Luminex crossmatches.

Luminex bead-based assays are routinely used in the study of anti-human leukocyte antigen (HLA) donor-specific antibodies (DSA). Single antigen (SA) assays use beads coated with recombinant antigens whereas Luminex crossmatch (Xm-DSA) tests consist of beads coated with isolated donor-specific HLA molecules. The aim of this study was to compare these techniques used to detect DSA. A total of 24 sera recognizing different HLA class I (seven anti-HLA-A and seven anti-HLA-B) as well as class II (seven anti-HLA-DR and three anti-HLA DQ) specificities by complement dependent cytotoxicity were included in the study. These sera were used undiluted and in serial dilutions to perform both class I and II SA and Xm-DSA assays. In the case of Xm-DSA the same serum was checked with different lysates. A total of 42 lysates were used to perform a total of 61 crossmatches: 42 to detect anti-class I and 19 to detect anti-class II antibodies. The maximum positive dilution was higher for SA in 76% of the class I and in 90% of the class II crossmatches. Those cases with a higher sensitivity of the Xm-DSA could not be explained by a larger number of antigen targets.

HAVCR1 Gene Haplotypes and Infection by Different Viral Hepatitis C Virus Genotypes

ABSTRACT The hepatitis A virus cellular receptor 1 (HAVCR1) gene is highly polymorphic, and several variants have been associated with susceptibility to allergic and autoimmune diseases. The HAVCR1 gene region was identified as a candidate for hepatitis C virus (HCV) natural clearance in a genotyping study of selected immune response genes in both European-American and African-American populations. The aim of the present study was to explore the influence of HAVCR1 in the outcome of HCV infection in the Spanish population. Three cohorts, consisting of 354 subjects with persistent HCV infection (285 with persistent HCV monoinfection and 69 with natural clearance), 182 coinfected HIV/HCV patients, and 320 controls, were included. Samples were genotyped in several polymorphic positions, insertion/deletion variants in exon 4 and tag single nucleotide polymorphisms (SNPs), in order to define previously described HAVCR1 haplotypes (haplotypes A to D). No statistically significant differences were observed with spontaneous resolution of infection or with viral clearance after treatment. Nevertheless, different rates of infection by viral genotypes (Gs) were observed among the HAVCR1 haplotypes. Individuals bearing haplotype C had the highest viral G1 infection rate when compared to individuals bearing other haplotypes (75.82% versus 57.72%, respectively; corrected P value [Pc], 3.2 × 10−4; odds ratio [OR], 2.30; 95% confidence interval [CI], 1.51 to 3.47). Thus, HAVCR1 could be involved in susceptibility or resistance to infection by a particular HCV genotype.

Interactive effects of immunoglobulin gamma and human leucocyte antigen genotypes on clearance and persistence of infection with hepatitis C virus.

Particular alleles of human leucocyte antigen (HLA) and immunoglobulin gamma (GM) and immunoglobulin kappa (KM) allotypes (polymorphic determinants of IgG heavy chains and κ‐type light chains, respectively) are associated with the outcome of several infections. To examine their role in the outcome of hepatitis C virus (HCV) infection, we genotyped 50 individuals with resolved and 117 with persistent HCV infection. None of the GM, KM or HLA‐C genotypes by themselves were associated with the resolution or persistence of HCV infection. However, particular combinations of HLA and GM genotypes were associated significantly with the outcome of HCV infection. Subjects with the HLA C1C1 genotype, in the absence of GM ff, were more than seven times [odds ratio (OR) 7·15] as likely to have persistent infection as the subjects who lacked both these genotypes. The presence of GM ff, in the absence of HLA C1C2, was associated with the resolution of infection (OR 0·27). The absence of GM fz, in the presence of HLA C2C2, was also associated with the resolution of infection (OR 0·27). Compared to the subjects who lacked both these genotypes, subjects with GM fz, in the absence of HLA C1C2, were almost four times as likely to have persistent infection (OR 3·91); similarly, subjects with HLA C1C2, in the absence of GM fz, were almost three times as likely to have persistent infection (OR 2·80). These results show, for the first time, interactive effects of GM and HLA genotypes in the outcome of HCV infection.

Fine-mapping butyrophilin family genes revealed several polymorphisms influencing viral genotype selection in hepatitis C infection

Host–viral genetic interaction has a key role in hepatitis C infection (HCV) and maybe in the viral selection. In a preliminary GWAS analysis, we identified BTN3A2 rs9104 to be associated with HCV genotype 1. Therefore, our aim was to determine the influence of BTN family on the selection of HCV genotype. We performed a fine-mapping analysis of BTN gene region in a cohort of chronic HCV infection (N=841), validating significant results in another independent chronic HCV infection cohort (N=637), according to selection of viral genotype. BTN3A2 rs9104, BTN3A2 rs733528, BTN2A1 rs6929846, BTN2A1 rs7763910 and BTN3A3 rs13220495 were associated with viral genotype selection. Interestingly, BTN3A2 rs9104 GG genotype was closely related to genotype 1 infection (80.7% (394/488) compared with genotype 3 infection (53.5% (23/43); P=0.0001) in patients harboring IL28B-CT/TT genotype, although this effect was not observed in IL28B-CC genotype. Similarly, BTN3A3 rs13220495 CC genotype was linked to genotype 3 infection (100% (32/32)) compared to genotype 1 (87.3% (137/157); P=0.028) in patients harboring IL28B-CC genotype, but did not in IL28B-CT/TT genotype. Genetic variants in the butyrophilin family genes may alter susceptibility to infection, selecting HCV genotype and influencing disease progression. BTN3A2 rs9104 was strongly associated with genotype 1 infection and the haplotype BTN3A3 rs13220495 CC+IL28B genotype CC was universal in patients with hepatitis C genotype 3a.