Role of HLA-DQB1 alleles in the risk, signs and symptoms, and severity of celiac disease in a Venezuelan population.

INTRODUCTION AND AIMS: Celiac disease (CD) is a complex condition, whose main genetic determinant involves HLA molecules, specifically the HLA-DQ2 and/or HLA-DQ8 heterodimers. Nevertheless, the frequency of the alleles encoding those molecules has not been reported in Venezuelan celiac patients. Therefore, the aim of our study was to evaluate the frequency of the HLA-DQB1 alleles in individuals with symptoms suggestive of CD and define the diagnostic markers of the condition in a Venezuelan population. MATERIAL AND METHODS: A cross-sectional study included 516 individuals with symptoms suggestive of CD. Molecular typing of the HLA-DQB1 locus was performed using a polymerase chain reaction-sequence-specific oligonucleotide procedure (PCR-SSO). RESULTS: A total of 58.3% of the individuals with clinical manifestations consistent with CD presented with at least one risk allele (DQB1*0201 and/or DQB1*0302), and the diagnosis was confirmed in 40 of them. The patients with CD had a higher frequency of the DQB1*0201 risk allele (26.25%), followed by the DQB1*0302 (17.5%) allele. There was an association between the presence of risk alleles and the presence of lesions characteristic of CD (P = 0.001), and a correlation was found between the genetic predisposition to develop CD and the presence of anti-tissue transglutaminase antibodies (P = 0.0127). CONCLUSIONS: The results support the role of the DQB1*02 and DQB1*0302 alleles in CD susceptibility and the histologic alterations of the intestinal mucosa, in a Venezuelan population.

Papel de las variantes GSTM1, GSTT1 y MnSOD en el desarrollo de enfermedad de Alzheimer de aparición tardía y su relación con el alelo 4 de APOE / Role of genes GSTM1, GSTT1, and MnSOD in the development of late-onset Alzheimer disease and their relationship with APOE*4

Introducción: Diversos estudios han descrito que en los cerebros de pacientes con enfermedad de Alzheimer (EA) hay una mayor oxidación de lípidos, proteínas y ADN. Además, en estos pacientes se ha observado diferencias en la actividad y polimorfismos de los genes que codifican las enzimas GST (T1 y M1) y MnSOD. En virtud de ello se planteó estudiar la variabilidad de los genes GSTT1, GSTM1 y MnSOD en individuos venezolanos sanos y con EA. Métodos: Se incluyeron 179 individuos venezolanos, no relacionados, agrupados en pacientes con EA (n = 79) e individuos sanos (n = 100). La presencia o ausencia de los genes GSTT1/GSTM1 se determinó por PCR-SSP y los polimorfismo de los genes MnSOD y APOE por PCR-RFLP. Resultados: El genotipo GSTT1+/GSTM1− parece favorecer el desarrollo de la EA (OR = 2,06; p = 0,01), siendo el riesgo mayor al estar en combinación con el alelo ε4 del gen APOE: GSTT1+/GSTM1−/ ε3 ε4 (OR = 3,07; p = 0,05), GSTT1+/GSTM1−/ ε4 ε4 (OR = 5,52; p = 0,02). El polimorfismo Ala-9Val por sí solo no parece estar relacionado con la EA, sin embargo, la presencia del genotipo Ala/Ala incrementa el riesgo que proporciona el alelo ε4 del gen APOE: AlaAla/ ε3 ε4 (OR = 3,47; p = 0,03), AlaAla/ ε4 ε4 (OR = 6,3; p = 0,01). Conclusiones: Los resultados apoyan la hipótesis de que el deterioro de la función mitocondrial y el aumento de daño oxidativo están involucrados en la patogénesis de la EA. Es importante estudiar otros genes relacionados con estrés oxidativo y vías antioxidantes, los cuales pudiesen estar involucrados en la susceptibilidad a desarrollar la EA

Introduction: Several studies have reported increased oxidation of lipids, proteins and DNA in the brains of patients with Alzheimer disease (AD). Moreover, these patients display differences in the activity and polymorphisms of the genes encoding the enzymes GST (T1, M1) and MnSOD. For these reasons, we designed a study of the variability in GSTT1, GSTM1, and MnSOD genes in healthy and AD groups from a Venezuelan population. Methods: We included 179 unrelated Venezuelan subjects classified as either AD patients (n = 79) or healthy individuals (n = 100). Presence or absence of the GSTT1/GSTM1 genes was determined using PCR-SSP, and polymorphisms of MnSOD and APOE genes were identified with PCR-RFLP. Results: The genotype GSTT1+/GSTM1− seems to favour development of AD (OR = 2.06, P = .01). The risk level is higher when it is combined with the ε4 allele of the APOE gene: GSTT1+/GSTM1−/ ε3 ε4 (OR = 3.07, P = .05), GSTT1+/GSTM1−/ ε4 ε4 (OR = 5.52, P = .02). The Ala-9Val polymorphism does not appear to be related to AD. However, the presence of the Ala/Ala genotype increases the risk provided by the ε4 allele of the APOE gene: AlaAla/_3_4 (OR = 3.47, P = .03), AlaAla/ ε4 ε4 (OR = 6.3, P = .01). Conclusions: The results support the hypothesis that impaired mitochondrial function and increased oxidative damage are involved in the pathogenesis of AD. It is important to study other genes related to oxidative stress and antioxidant pathways which could be involved in susceptibility to AD

Role of genes GSTM1, GSTT1, and MnSOD in the development of late-onset Alzheimer disease and their relationship with APOE*4. / Papel de las variantes GSTM1, GSTT1 y MnSOD en el desarrollo de enfermedad de Alzheimer de aparición tardía y su relación con el alelo 4 de APOE.

INTRODUCTION: Several studies have reported increased oxidation of lipids, proteins and DNA in the brains of patients with Alzheimer disease (AD). Moreover, these patients display differences in the activity and polymorphisms of the genes encoding the enzymes GST (T1, M1) and MnSOD. For these reasons, we designed a study of the variability in GSTT1, GSTM1, and MnSOD genes in healthy and AD groups from a Venezuelan population. METHODS: We included 179 unrelated Venezuelan subjects classified as either AD patients (n=79) or healthy individuals (n=100). Presence or absence of the GSTT1/GSTM1 genes was determined using PCR-SSP, and polymorphisms of MnSOD and APOE genes were identified with PCR-RFLP. RESULTS: The genotype GSTT1+/GSTM1- seems to favour development of AD (OR=2.06, P=.01). The risk level is higher when it is combined with the ɛ4 allele of the APOE gene: GSTT1+/GSTM1-/ɛ3ɛ4 (OR=3.07, P=.05), GSTT1+/GSTM1-/ɛ4ɛ4 (OR=5.52, P=.02). The Ala-9Val polymorphism does not appear to be related to AD. However, the presence of the Ala/Ala genotype increases the risk provided by the ɛ4 allele of the APOE gene: AlaAla/ɛ3ɛ4 (OR=3.47, P=.03), AlaAla/ɛ4ɛ4 (OR=6.3, P=.01). CONCLUSIONS: The results support the hypothesis that impaired mitochondrial function and increased oxidative damage are involved in the pathogenesis of AD. It is important to study other genes related to oxidative stress and antioxidant pathways which could be involved in susceptibility to AD.

Distribution of killer cell immunoglobulin-like receptor genes in the mestizo population from Venezuela.

This study represents the first report on the distribution of KIR genes in 205 unrelated healthy mestizo Venezuelan individuals. Genotyping analysis showed that all KIR genes are present in this population. Frequency of inhibitory killer cell immunoglobulin-like receptors (KIRs) exceeded 0.69, except for KIR2DL2 (0.29) and 2DL5 (0.37). Activating KIRs showed low frequencies (0.11-0.29), except for KIR2DS4 (0.68). Forty-five different KIR genotypes were identified, with a predominance of three genotypes found in 50.7% of the population of which 25.9% were individuals homozygous for haplotype A. The frequencies of KIR genes reflect the ethnic admixture existing in the mestizo Venezuelan population.

Polimorfismo HLA-DQ en pacientes pediátricos con enfermedad Celíaca

La Enfermedad celíaca es una enteropatía caracterizada por malabsorción y daño epitelial del intestino delgado, del cual se han aislado células T específicas al gluten y restringidas a los heterodímeros DQ2-DQ8, sugiriendo que los alelos DQ juegan un papel clave en la patogénesis de la enfermedad por la presentación de péptidos derivados del gluten a linfocitos T de la mucosa. En nuestro estudio evaluamos el polimorfismo HLA-DQA y DQB en pacientes pediátricos con Enfermedad Celiaca. Se estudiaron 16 pacientes que acudieron al Servicio de Gastroenterología Pediátrica del Hospital "JM de los Ríos". Los polimorfismos se definieron mediante PCR-secuenciación; las asignaciones alélicas y haplotípicas se determinaron por contaje directo. En concordancia con estudios realizados en otras poblaciones, este estudio sugiere que los heterodímeros HLA-DQ2 y DQ8 son marcadores genéticos de predisposición al desarrollo de la enfermedad celíaca. Siendo este reporte el primero en el País en resaltar la presencia de los HLA en la enfermedad celíaca.

The celiac disease is an enteropathy characterized by malabsortion and epitelial damage of the small bowel, of the one which cells specific T has been isolated to gluten and restricted to the DQ2-DQ8 heterodímers, suggesting that the DQ alelles play a key role in the pathogenesis of the disease for the presentation of derived péptides from the gluten to T linfocites. In our study we evaluate the HLA-DQA and DQB polymorphism in pediatric patients with celiac Disease. 16 patients were studied from Gastroenterology service of the "Hospital de Niños JM de los Ríos". The polymorphism was defined through PCR-sequence; the assignments of alleles and haplotype were determined by direct count. Similar to other reports which suggest HLA DQ2 y DQ8 as markers in genetic predisposition in celiac disease, this study is the first in Venezuela in screened HLA in Celiac Disease.

HLA-DRB1*0402 haplotypes without DQB1*0302 in Venezuelan patients with pemphigus vulgaris.

The two basic forms of autoimmune intraepidermal blistering diseases, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), affect different layers of the skin, have different symptoms and target different antigens. We have defined human leukocyte antigen (HLA)-DRB1-DQB1 alleles and haplotypes in a case-control study of 66 non-Jewish patients attending a public reference Hospital over the past 10 years. The control group consisted of 101 matched individuals tested also by medium to high-resolution polymerase chain reaction-sequence-specific oligonucleotide with primers and probes from the 12th and 13th International Histocompatibility Workshop. Patients and controls were descendants of three-generation individuals born in the country. Among the patients, 49 had PV, 50% showed predominantly mucosal involvement, 50% showed predominantly the cutaneous clinical phenotype and 17 had PF. Statistically significant HLA-DR frequency differences between patients with PV and controls were found only for DRB1*0402 and DRB1*1401 [odds ratio (OR) = 27.22, confidence interval (CI) 94.7-7.82, P= 1.1 x 10(-14) and OR = 46.56, CI 801.4-2.70 P= 7.5 x 10(-6), respectively]. Both alleles were also increased in the patients with PF compared with the controls (OR = 7.0, P= 0.038 and OR = 21.64, P= 0.009, respectively), but the significance of the difference did not resist Bonferroni correction. Haplotype analysis showed that DRB1*0402 was always present with DQB1*0302 and DRB1*1401 with DQB1*0503, but no independent effect of the DQB1*0302 in the former haplotype was evident. Our results support the hypothesis that the DRB1*0402 without DQB1*0302 is the most relevant HLA-DRB1 allele responsible for the pathogenesis of pemphigus in Venezuelan patients with PV and discard the DQB1*0302 influence observed in other populations.

Human leukocyte antigen class I and MICA haplotypes in a multicase family with Cladophialophora carrionii chromoblastomycosis.

Previous studies carried out in an endemic semiarid region northwest of Venezuela at Falcon State have shown a prevalence of 15.4/1000 of chromoblastomycosis following traumatisms with xenophile vegetation infected with Cladophialophora carrionii. We performed high-resolution DNA typing of human leukocyte antigen (HLA)-A, -B and -C and major histocompatibility complex class I chain related gene A (MICA) alleles and segregation analysis in 49 members of one extended family with 12 affected individuals, who have lived for approximately 70 years in this endemic zone. None of the alleles, haplotypes or genotypes is shared by all the patients. No deviation from the expected HLA haplotype distribution or association of chromoblastomycosis with HLA-A, -B and -C haplotypes was observed. Further, a haplotype-sharing transmission/disequilibria testing of 11 nuclear families did not give enough evidence to claim linkage (P = 0.398), suggesting that genes located in the short arm of chromosome 6 may not be relevant in the immune response toward infection with C. carrionii in this Venezuelan endemic zone. Deleted MICA alleles on HLA-B*4802 haplotypes were present among several members of the extended family, but only two of them were affected.

Genetic variability of Apolipoprotein E in different populations from Venezuela.

The genetic variation at the Apolipoprotein E locus (APOE) is an important determinant of plasma lipids and has been implicated in various human pathological conditions. The objective of the present study was to estimate the distribution of APOE alleles in five Venezuelan communities: two Amerindian tribes (Bari and Yucpa), one Negroid population from Curiepe, one Caucasoid population from Colonia Tovar and the Mestizo urban population living in Caracas. The APOE*3 allele was the most common allele in all populations studied. However, a significant increase in the APOE*2 allele frequency in the Mestizo (18.96%) and Negroid (16.25%) populations was found. Similar to results reported in other Native American populations we have found that the APOE*2 allele is completely absent in the Bari and Yucpa Amerindians. Frequencies found in the Colonia Tovar population are in agreement with those reported in the population of Germany, indicating a high degree of relatedness. The results support the notion that the distribution of the APOE alleles shows ethnic variability.

TNF-alpha-308A allele, a possible severity risk factor of hemorrhagic manifestation in dengue fever patients.

Among the several hypothesis postulated to explain the pathogenesis of severe dengue disease, the model of immunopathogenesis is the most supported one with a likely important role played by the cascade of cytokines. This work describes single-nucleotide polymorphism of tumor necrosis factor (TNF)-alpha, interferon-gamma, interleukin (IL)-6, transforming growth factor-beta1, and IL-10 in patients with dengue virus infections and analyzes their relation with clinical manifestations of the disease. Because cytokine gene polymorphisms affect cytokine production, the significant increase of the TNF-308A allele we have observed among patients with dengue fever (DF) with hemorrhagic manifestations compared to patients with DF only indicates that the former patients are genetically predisposed to express higher levels of TNF-alpha. This finding supports studies reporting a possible association between elevated levels of circulating TNF, vascular permeability, and hemorrhage in patients with dengue hemorrhagic fever.

Is the CCR5-59029-G/G genotype a protective factor for cardiomyopathy in Chagas disease?

Investigated were two CCR5 gene polymorphisms, the CCR5 Delta 32 deletion and the pCCR5 59029 A-->G promoter point mutation, in 107 ethnically mixed Venezuelan patients serologically positive for Trypanosoma cruzi (34 asymptomatic, 38 arrhythmic, 35 cardiomyopathic). No difference in the distribution of CCR5 Delta 32 among asymptomatic and symptomatic patients was found. We have observed an increase of the 59029-G phenotype among asymptomatic compared with symptomatic chagasic patients (68% vs. 58%), in agreement with previously reported data (57% vs. 31%). This frequency difference, although not statistically significant, is more marked when the 59029-G allele is present in homozygous form. However, a similar distribution of the G/G genotype is present among asymptomatic patients and patients with heart failure. Because it has been reported that the 59029G/G genotype associates with lower CCR5 expression, 37% of our T. cruzi-infected patients with heart failure are genetically predisposed to express low levels of CCR5 on the surface of CD8(+) T cells, contrary to what would be expected if an inflammatory response is required for severe cardiac damage. If confirmed, the possible protection that might be conferred by the G/G genotype may be due to the existence of other genes in linkage disequilibria.

Analysis of the T-cell receptor beta-chain variable-region (Vbeta) repertoire in chronic human Chagas' disease.

Previous studies have shown that infection with the protozoan Trypanosoma cruzi (Chagas' disease) is associated with genetic components [human leukocyte antigen (HLA) genes and T-cell receptor (TCR) genes]. We studied the TCR Vbeta repertoire of peripheral blood lymphocytes of 23 unrelated serologically positive subjects using reverse transcriptase-polymerase chain reaction (RT-PCR). The patients, previously tested for HLA genotypes, were clinically classified as asymptomatic, arrhythmic and cardiopathic patients. Statistical analysis showed the significant increment of the Vbeta7 family in chagasics with arrhythmia compared with asymptomatic and cardiopathic patients, indicating that the frequency of this family is variable in different clinical forms of the disease and possibly that these T cells might be a marker of the progression of Chagas' disease. Based on the calculation of a Delta score the order of variability in the TCR repertoire was: patients with heart failure > asymptomatic > arrhythmic patients. The major histocompatibility complex (MHC) of the individual may influence the use of particular V genes in T-cell response to foreign antigens. We found a significant increase of the Vbeta7 family in arrhythmic patients who were DRB1*01 DQB1*0501 DPB1*0401, a marker associated with susceptibility to cardiac damage in Chagas' disease. If confirmed by further studies in a larger cohort, a possible association between the TCR Vbeta repertoire and the MHC haplotype of chagasic patients could be postulated.

Inmunogenética de la enfermedad de Chagas / Immunogenetics of Chagas' disease

La enfermedad de Chagas, debida al parásito T. cruzi, representa uno de los más importantes problemas de salud pública en América latina. Aunque, en las últimas décadas, muchos parasitólogos han aunado esfuerzos en la búsqueda de moléculas o péptidos protectores que puedan ser candidatos para la elaboración de una vacuna efectiva contra esta parasitosis, la enfermedad de Chagas constituye un reto en la investigación inmunológica. Efectivamente, la presencia de epítopos de reactividad cruzada entre el hospedero y el parásito, así como el desarrollo de células T autorreactivas o promotoras de la enfermedad, apoyan la hipótesis de que un proceso autoinmune está asociado a la enfermedad crónica. Los estudios de genes HLA en la enfermedad de Chagas, por métodos serológicos, celulares y moleculares, indican la existencia de una relación entre determinados alelos y/o haplotipos HLA y la predisposición a la infección y/o el desarrollo de la cardiomiopatía chagásica. Recientemente, el estudio del repertorio del receptor de las células T indica la posible implicación de las células T en la patología de esta enfermedad. Es posible entonces, que la susceptibilidad a la infección causada por el parásito T. cruzi esté asociada con componentes genéticos del hospedero (genes HLA, genes TCR). Por lo tanto, la identificación de esos factores inmunogenéticos puede ser útil para el desarrollo de terapias que permitan mejorar o prevenir la progresión de las lesiones cardiacas (AU)

Influence of the HLA class II polymorphism in chronic Chagas' disease.

Chagas' disease or American trypanosomiasis due to Trypanosoma cruzi has existed at least since the time of the Inca empire and contributes significantly to cardiovascular morbidity and mortality in several countries of this continent. Due to the fundamental role of human class II molecules polymorphic residues in the control of the immune response, a study was designed to define by DNA typing HLA class II alleles in a sample of 67 serologically positive individuals with and without cardiomyopathy and in 156 healthy controls of similar ethnic origin. Genomic DNA extraction, PCR amplification of the HLA-DRB1 and DQB1 second exon regions and hybridization to labelled specific probes were carried out following the 11th International Histocompatibility Workshop reference protocol. Comparison of DRB1 and DQB1 allele frequencies among the patients and control subjects showed a decreased frequency of DRB1*14 and DQB1*0303 in the patients, suggesting independent protective effects to the chronic infection in this population. Allele frequencies comparison between patients with and without cardiomyopathy showed a higher frequency of DRB1*01, DRB1*08 and DQB1*0501 and a decreased frequency of DRB1*1501 in the patients with arrhythmia and congestive heart failure. The results suggest that HLA Class II genes may be associated with the development of a chronic infection and with heart damage in Chagas' disease.