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Biomedical subjects

M A Figueredo

Publications and source records attributed to M A Figueredo.

At least 19 recordsLinked to original sources
PubMed2006

NFkappaB1 gene does not affect type 1 diabetes predisposition in a Spanish population.

The chromosomal location of the NFkappaB1 gene on 4q, a region linked to type 1 diabetes (T1D), together with the observed resistance to T1D of NFkappaB1-deficient mice, suggests its potential role as candidate gene increasing diabetes predisposition. Previous association studies in diverse populations yielded inconclusive results. Two polymorphisms in the promoter region of the NFkappaB1 gene have been studied: a functional -94ins/delATTG regulating the gene expression and a very informative CA-repeat microsatellite. A strong association with the latter was reported in British population but could not be replicated in Danish families. No evidence of association was detected for those genetic markers in 270 Spanish T1D patients and 484 healthy ethnically matched controls. Therefore, it seems that this gene plays no major role in T1D predisposition.

Adolescent↗
PubMed2002

Triplet repeat polymorphism in the transmembrane region of the MICA gene in celiac disease.

Celiac disease (CD) is characterized by a striking expansion of gamma delta T cells in the intestine. These cells interact with MICA, a cell surface protein encoded by a major histocompatibility complex gene. We investigated whether MICA gene polymorphism could contribute to susceptibility to CD. DNA typing for HLA-DR, DQA1, DQB1, TNF-308, TNFa, TNFb and a triplet repeat polymorphism in the transmembrane region of the MICA gene were carried out. We performed case-control stratified association studies and transmission disequilibrium tests. Our results indicate that although there is no primary association between MICA polymorphism and CD, there is, in addition to HLA-DQ, a second susceptibility locus on the 8.1 ancestral haplotype in strong linkage disequilibrium with MICA A5.1 allele.

Alleles↗
PubMed2000

Influenza virus immunization effectivity in kidney transplant patients subjected to two different triple-drug therapy immunosuppression protocols: mycophenolate versus azathioprine.

BACKGROUND: Due to possible complications and treatment limitations, the prevention of influenza in renal transplant (RT) patients is highly indicated. METHODS: Forty-nine patients with a 1-year functioning RT subjected to two different immunosuppressive regimens and 37 healthy relatives (HR) were administered the anti-influenza vaccine as recommended for 1996 to 1997. Anti-influenza antibody, creatinine, and immunological markers were estimated at 1 and 3 months after vaccination. RESULTS: Three months after vaccination, 46.2% of the RT patients and 69% of the HR (P=0.06) showed protective antibody titers to influenza A (relative risk [RR]; 0.67; 95% confidence interval: 0.44-1.02). A total of 20.5% of the RT patients and 44.8% of the HR showed antibodies to influenza B (P=0.03). Despite these differences, the incidence of illness was similar. The immunosuppressive regimen had no effect on the antibody response. CONCLUSIONS: Although the RT patients showed a reduced antibody response, no negative effects on graft outcome were observed.

Adult↗
PubMed2000

Celiac disease and TNF promoter polymorphisms.

The possibility that genetic susceptibility to celiac disease (CD) might be influenced by tumor necrosis factor (TNF) genes polymorphism has repeatedly been put forward. To date, this has only been investigated in case-control studies and results have been contradictory. In order to avoid any possible ethnic mismatching between patients and controls, we have approached this problem studying 71 celiac families, establishing the parental haplotypes and comparing CD versus control haplotypes (the so-called AFBAC or affected family-based controls). We used DNA-based methods to screen for HLA-DRB1, -DQA1, and -DQB1 alleles, TNFalpha promoter polymorphims and TNFa and b microsatellites. The guanine-to-adenine polymorphism at position -308 of the TNFalpha gene promoter region was found associated with CD as the TNF-308A allele appeared significantly increased in frequency in CD haplotypes, and this was shown to be independent of the association between CD and the DRB1*0301,DQA1*0501,DQB1*0201 alleles. Our results indicate that at least another gene, in addition to the known association of CD with HLA class II, has a susceptibility role in this disease. This should be either TNFalpha or another polymorphic gene in the telomeric end of the HLA class III region.

Celiac Disease↗
PubMed1999

Primary association of a TNF gene polymorphism with susceptibility to multiple sclerosis.

The associations of three promoter polymorphisms in the tumor necrosis factor (TNFA) gene have been studied in 238 patients and 324 control subjects. A significant correlation was found between MS susceptibility and the TNFA-376 polymorphism. This association was independent of the human leukocyte antigen (HLA) class II association and the combined inheritance of HLA-DRB1*1501 and the TNFA-376A allele more than additively increased susceptibility to MS.

Alleles↗
PubMed1999

Pancolitis and genetic markers in the Spanish population.

BACKGROUND: although the etiology of ulcerative colitis disease remains an enigma, the importance of the major histocompatibility complex genes has been described, as in many other autoimmune diseases. AIM: we investigated the contribution of HLA-DRB1, DQA1 and DQB1 genes (HLA region) in patients with pancolitis. METHODS: we studied a total of 89 patients diagnosed as having ulcerative colitis (34 pancolitis and 55 left colitis) and 275 healthy control subjects. Complete information on sex, age, family history, age of onset, localization, complications, surgery and treatment was obtained from all patients. DNA was extracted from peripheral blood leukocytes and all individuals were HLA-DRB1 genotyped. RESULTS AND CONCLUSIONS: there was an association between pancolitis and the presence of DR4-Val86 (p = 0.009; OR = 3.3) and DRB1*0103 (p = 0.02; OR = 5.1) alleles. In patients with left colitis an association with DRB1*1501 (p = 0.03; OR = 1.9) and DRB1*0103 alleles (p = 0.03; OR = 3.8) was observed. We conclude that a strong association between DR4-Val86 and pancolitis exists.

Adult↗
PubMed1998

Polymorphism within the HLA-DQB1*02 promoter associated with susceptibility to coeliac disease.

Susceptibility to coeliac disease is associated with a particular HLA-DQ alpha beta heterodimer encoded by the DQA1*0501 and DQB1*02 genes. A single base polymorphism in the DQB1*02 promoter region in DR7, DQA1*0201, DQB1*02 haplotypes was observed, associated with an increased susceptibility to the disease. This finding suggests a novel mechanism of susceptibility to immune-mediated diseases.

Alleles↗
PubMed1998

Contribution of HLA class II genes to susceptibility in achalasia.

Achalasia is a motor disorder of the esophagus resulting in functional obstruction. The cause of the lesion is unknown although genetic and immunologic factors have been suggested. An association with serological HLA epitopes has been previously reported. In this study, we have further examined this HLA class II association with susceptibility to achalasia by DNA based methods. Achalasia patients (n=40) and healthy controls (n=275), all Caucasians and unrelated, were included in the analysis. The strongest associations were with HLA-DQA1*0101 and two HLA-DQ alphabeta heterodimers having their alpha chain encoded by this allele. Moreover, relative risk was significantly higher in DQA1*0101 homozygotes as compared to heterozygotes and results suggested that DQB1*02 may have a protective role.

Alleles↗
PubMed1998

HLA-DR2 gene and Spanish patients with ulcerative colitis.

BACKGROUND: An association with class II MHC genes has been described in ulcerative colitis, as in other diseases with immunological pathogenesis. Heterogeneous results have been reported, depending on the studied population. OBJECTIVE: To study the importance of these genes in our population, mainly the alleles of group HLA DR2 (gene HLA-DRB1). PATIENTS AND METHODS: We studied a total of 107 patients diagnosed of ulcerative colitis and 200 unaffected controls. Complete information about sex, age, family antecedent, age of onset, localization, complications, surgery and treatment was obtained from these patients. DNA was extracted from peripheral blood leukocytes and all the individuals were HLA-DRB1 genotyping. RESULTS AND CONCLUSIONS: We conclude that a positive association exists between DR15 and ulcerative colitis (p < 0.05). This positive association was characterized and various clinical parameters were analyzed, being concluded that DR1501 is more frequent in this disease (p < 0.05) and in benign manifestations; the frequency of the allele DR1502 was also found to be elevated in severe manifestations.

Adult↗
PubMed1997

Positive and negative associations of distinct HLA-DR2 subtypes with ulcerative colitis (UC).

In UC, as in many other diseases with a suspected autoimmune etiology or pathogenesis, an association with certain HLA class II specificities has been investigated. In the Japanese, several studies have shown a positive association with DR2, but in Caucasian populations the results are conflicting. Therefore we undertook a study of HLA class II gene association with UC in a large group of white Madrid patients and ethnically matched controls, using molecular biology techniques to investigate whether any allelic subspecificity within the HLA-DR2 group is associated with susceptibility to or protection against UC. Patients with ulcerative colitis (n = 107) and 200 controls were typed using molecular, DNA-based techniques for HLA-DRB1, DQA1 and DQB1 alleles. Those HLA-DR2+ were then specifically typed for the individual alleles within the HLA-DR2 group. We observed a positive association with HLA-DR15 (P=0.021) and its subtype DRB1*1501 (P=0.018). HLA-DRB1*1502 was also increased, although its frequency both in patients and controls was very low. When the HLA-DR2+ population was studied, HLA-DRB1*1601 was significantly decreased in patients (P=0.026). Both HLA-DR3 (P=0.002) and HLA-DQB1*02 (P=0.001) were also negatively associated with the disease, the latter especially with pancolitis. Therefore, HLA class II association with UC is complex, and separate alleles confer either susceptibility or resistance. Conflicting results with HLA-DR2 appear to be due to the presence in this group of both positively associated (HLA-DRB1*1501 and DRB1*1502) and negatively associated (HLA-DRB1*1601) subspecificities. Moreover, HLA-DR3 and HLA-DQB1*02 are associated negatively.

Adolescent↗
PubMed1995

HLA-linked genes acting as additive susceptibility factors in celiac disease.

Susceptibility to developing CD is widely accepted to be primarily associated with a particular HLA-DQ alpha beta heterodimer encoded by the DQA1*0501 and DQB1*0201 alleles in cis position on the DR3,DQ2 haplotype or in trans position by DR5,DQ7/DR7,DQ2 heterozygotes. We performed genomic HLA-DR and -DQ typing of 100 unrelated Spanish celiac children and 180 ethnically matched controls. As expected, most (92 out of 100) celiac patients carried the HLA-DQ alpha beta heterodimer, and we selected these individuals for further studies. The results corroborate that although the DQA1*0501 and DQB1*0201 genes in single dosage appear sufficient for conferring disease susceptibility, individuals homozygotes for DQB1*0201 show an increased risk. Furthermore, our data also show that those carrying the genotype DR5,DQ7/DR7,DQ2 have a significantly increased risk of developing CD as compared to those that are non-DR7 positive, also carrying the CD-associated HLA-DQ alpha beta heterodimer. This strongly suggests that there is an MHC linked non-HLA-DQ gene primarily associated with CD present on DR7,DQ2 haplotype, which should either be DR7 or in strong linkage disequilibrium with it. Our data also indicate that, as has already been suggested, another HLA-associated CD susceptibility gene may be present on some DR4-carrying haplotypes.

Blotting, Southern↗
PubMed1994

Inhibition of histone/anti-histone reactivity by histone-binding serum components; differential effect on anti-H1 versus anti-H2B antibodies.

IgG fractions were purified on a protein G-agarose column from sera of both systemic lupus erythematosus (SLE) patients and healthy donors. All IgG fractions, after elution with 0.5 M acetic acid, reacted with histones in an anti-histone ELISA assay, and IgG anti-histone activity was in all instances higher in the IgG fraction than in the corresponding whole serum. This was shown to be due to the presence in serum of histone-binding components that inhibited IgG binding to histones. Both normal human and SLE patients' sera had these histone-binding components, and disparity between serum-positive and -negative anti-histone antibody (AHA) tests was not dependent on differences in the blocking capacity but on IgG antibody levels and avidity. Interaction of normal serum IgG fraction with all five histones was of low avidity, whereas interaction of IgG from AHA-positive SLE sera with both H1 and H2B had high avidity. Low-affinity antibodies to every histone fraction, but also high-affinity anti-H1 antibodies, were preferentially inhibited. Our data indicate that several serum protein components are inhibiting histone/anti-histone interaction and may play a protective role against both high-affinity anti-H1 antibodies present in SLE patients, and natural, low-affinity, anti-histone antibodies. As some acute phase proteins, notably C-reactive protein, bind to histones, it is conceivable that they play such a role. High-affinity anti-H2B antibodies, present in some SLE patients, and not inhibited by these serum components, may, on the other hand, participate in the pathogenesis of the disease.

Antibody Affinity↗
PubMed1991

Occurrence of antibodies to protease-treated histones in a patient with vasculitis.

We describe the presence of IgG antibodies reacting with histones previously treated with proteases in a patient with vasculitis. The patient's serum did not react with nontreated histones and when several enzymes were tested separately, only alpha-chymotrypsin reproduced the effect. Reactivity was directed against histone fraction H2B and no other autoantibody was found in the patient's serum. This could represent an autoantigen-driven response, histones hydrolyzed in vivo with proteases being the immunogenic stimulus. Diagnostic and pathogenic implications derived from the existence of such autoantibodies are discussed.

Adult↗
PubMed1990

[Lymphocyte subpopulations in the evolution of brucellosis].

We have sequentially studied for one year CD3+, CD4+, CD8+, CD11b+, and CD20+ lymphocyte subpopulations in 52 brucellosis patients whose diagnosis was confirmed by hemoculture. We observe at diagnosis a decreased percentage of CD4+ lymphocytes with an increase in CD8+ and inverted CD4+/CD8+ ratio, which was greater in patients with an evolution longer than 4 weeks (p less than 0.05) returning to normal very slowly. The percentage of monocytes was also increase at diagnosis (p less than 0.01) and at their second month CD3+ an CD20+ subpopulations did not suffer any changes during the follow up period. Patients were divided into two groups according to whether one or two anti-Brucella IgG peaks were observed in ELISA throughout the evolution. Patients in whom IgG titer decreased uninterruptedly, the inversion of the ratio during the first two months was greater, while those patients who suffered a relapse showed a simultaneous new decrease in CD4/CD8 ratio (p less than 0.05).

Antibodies, Bacterial↗
PubMed1989

Development of splenic natural suppressor (NS) cells in Ehrlich tumor-bearing mice.

Spleen cells from C57BL/6J mice bearing Ehrlich carcinoma growing as a solid tumor show progressive unresponsiveness to concanavalin A (Con A) and lipopolysaccharide (LPS) mitogens. This is accompanied by striking spleen enlargement with marked hematopoietic activity. Lymphoproliferative assays of normal spleen cells in co-culture with tumor-bearing spleen cells (TBSC) show that: (a) TBSC contain non-specific suppressor cells able to abrogate both Con A and LPS responses, or mixed lymphocyte reaction, of normal spleen cells and (b) suppression by TBSC is MHC-unrestricted, non-prostaglandin-mediated and greatly enhanced by Con A supernatants. Suppressor cells associated with TBSC are large, low-density cells without markers of mature B or T lymphocytes or of the mononuclear phagocyte system. Most appear to be asialo-GM1-negative, as suppression was only partially inhibited by treatment with anti-asialo-GM1 and complement. Since NK activity is lacking in TBSC, our data strongly suggest that these "null" suppressor cells are related to the natural suppressor (NS) cells found described in normal bone-marrow and neonatal spleens, or induced in adult spleens by total lymphoid irradiation, graft-vs.-host disease, or cyclophosphamide treatment.

Animals↗