Biomedical subjects

Segundo González

Publications and source records attributed to Segundo González.

15 recordsLinked to original sources

PubMed2006

The predictive value of soluble major histocompatibility complex class I chain-related molecule A (MICA) levels on heart allograft rejection.

BACKGROUND: Recently the presence of a soluble form of major histocompatibility complex class I chain-related molecule A (sMICA) has been detected in the sera of patients with tumors. Shedding of sMICA by tumor cells downregulates NKG2D-mediated antitumor immunity. The aim of this investigation was to study the possible involvement of sMICA in the allograft acceptance after heart transplantation (HTX). METHODS: We monitored the levels of sMICA by specific enzyme-linked immunosorbent assay (ELISA) in a total of 146 serum samples obtained from 34 heart transplantation patients followed up during the first year post-HTX. RESULTS: The persistence of sMICA expression was correlated with the clinical evolution of these patients. sMICA was detected in the serum of 21 of 34 patients (61.70%) between 15 and 20 days after implantation and was practically absent in pretransplant serum samples. Twenty of these 21 patients (95.24%) with sMICA did not experience episodes of severe rejection during this period (P = 0.0001), whereas sMICA was practically absent in patients with manifestations of severe acute rejection. The longitudinal study of these patients revealed that the presence of sMICA was consistently maintained in 75% of the patients with good graft status during the period of observation. CONCLUSION: This has led us to believe that the presence of levels of sMICA during the first year post-HTX may contribute to allograft acceptance. Additionally, functional studies indicate that sMICA downregulates NKG2D surface expression, which may lead to a functional impairment of cell-mediated cytolysis. These data suggest a significant correlation between the presence of sMICA and a lower incidence of rejection.

Adult↗

PubMed2006

Transcriptional regulation of ULBP1, a human ligand of the NKG2D receptor.

Tumor cells expressing ligands of the NKG2D receptor stimulate anti-tumor immunity mediated by natural killer and T cells. In humans, NKG2D ligands (NKG2DL) are encoded by MIC and ULBP proteins. NKG2DL exhibit highly restricted expression in healthy tissues but are widely expressed in tumors. However, regulation of each NKG2DL differs substantially in different cancer cells. In this study, we characterized the mechanisms that regulate the expression of ULBP1. We show that the transcription of ULBP1 strictly depends on the binding of Sp1 and Sp3 to a CRE(1) site located in the ULBP1 minimal promoter. The mutation or deletion of this Sp1/Sp3 binding site abolished the transcription of ULBP1. It also diminished the transactivation of ULBP1 promoter by Sp3 overexpression, but not by Sp1, indicating that Sp3 is the main transcription factor that regulates ULBP1 through the CRE(1) site. Experiments in SL2 cells showed that the ULBP1 promoter was inactive in the absence of the Sp proteins and indicate that Sp3 is the essential activator of ULBP1 transcription, because the overexpression of Sp3 up-regulated its promoter activity > 500-fold. Additionally, we demonstrated that AP-2alpha repressed the expression of ULBP1 in HeLa cells by interfering with the binding of Sp3 and Sp1 to the ULBP1 promoter. These data indicate that Sp1, Sp3, and AP-2alpha may play an important role in the immunosurveillance against cancer. Finally, the definition of ULBP1 regulation may have implications for development of new therapeutic strategies against cancer cells.

Base Sequence↗

PubMed2005

The amino acid at position 97 is involved in folding and surface expression of HLA-B27.

HLA-B27 confers susceptibility to ankylosing spondylitis (AS) but the mechanism linking this association remains unknown. Other properties unrelated to its natural role of antigen presenting function may be important in disease pathogenesis. We determined here the impact of N97D substitution on the folding and expression of HLA-B*2704 transfected in the 721.221 cell line. The mutation at position 97 abolishes the surface expression of non-conformational (HC10) and conformational (ME1) forms. The expression of ME1 forms was found to be absent in B*2704 N97D by immunoprecipitation and flow cytometry of fixed and permeabilized cell experiments with the conformation-sensitive ME1 antibody. However, immunoblotting cell lysates with HC10 revealed the presence of unfolded heavy chain (HC) and HC-dimer forms. The impact of the N97D mutation in the exit from the endoplasmic reticulum (ER) was analysed by western blot after endoglycosidase-H treatment, and it was found that B*2704 N97D was retained and accumulated as unfolded molecules. We tested for mutant association with transporter associated with antigen processing (TAP), calnexin (CNX), calreticulin (CLR) and beta2 microglobulin (beta2m). The wild-type B*2704 and N97D mutants were associated with TAP, CNX and CLR, although HC10 forms of mutant N97D interact more weakly with TAP. Only folded molecules of HLA-B*2704 were associated with beta2m. Surprisingly, the peptide-binding assay demonstrated the ability of unfolded N97D molecules to bind high-affinity peptides. It has been suggested that AS may arise because of aberrant folding of HLA-B27 molecules within the ER. Future work must therefore aim to clarify the functional connection between the unfolded protein response pathway in response to the accumulation of HLA-B27 in the ER. This mutant could be useful as a model for the misfolding of HLA-B27.

Amino Acid Substitution↗

PubMed2005

The region of 150 kb telometic to HLA-C is associated with psoriasis in the Jewish population.

The HLA-Cw*0602 has been associated with psoriasis in different ethnic groups. But, it remains unclear whether HLA-C is the PSORS1 gene (the psoriasis gene in the MHC). Thus, several case-control studies have been performed in order to investigate whether HLA-C itself determines the susceptibility to the disease. We studied 59 Jewish patients with type I psoriasis and 79 matched controls. Polymorphic genes and markers from HLA-B (centromeric to HLA-C) to the corneodesmosin (CDSN) gene (telomeric to HLA-C) were genotyped in order to determine their contribution to the susceptibility to psoriasis. Neither HLA-Cw*0602 nor the allele CDSN*TTC were significantly associated with psoriasis with the size of the sample studied. The genes and markers telomeric to HLA-C such as the microsatellite C1_4_4 (OR = 2.6, 95% CI = 1.4-4.7, p(c) = 0.018) the octamer transcription factor (OTF)-3 gene (OR = 2.6, 95% CI = 1.6-4.3, p(c) = 0.0001) and the alpha-helix coiled-coil rod homologue (HCR) gene (OR = 2.5, 95% CI = 1.3-4.5, p(c) = 0.004), however, were associated with the disease. These results suggest that a major psoriasis susceptibility gene is likely to be located within a region of 150 kb telomeric to HLA-C and centromeric to the CDSN gene.

Adolescent↗

PubMed2004

Extended human leukocyte antigen haplotype EH18.1 influences progression to hepatocellular carcinoma in patients with hepatitis C virus infection.

Our aim was to investigate whether different human leukocyte antigen (HLA) genes might be associated with hepatitis C virus (HCV) infection. DNA obtained from 141 Spanish patients with HCV infection (48 with alanine aminotransferase levels in the range considered to be normal, 47 with liver cirrhosis, and 46 with hepatocellular carcinomas [HCCs]) and from 116 control subjects were typed for HLA-B, HLA-DRB1, and HLA-DQB1 alleles, as well as for major histocompatibility complex class I chain-related gene A (MICA) transmembrane polymorphism. The frequency of HLA-DR11 was increased in HCV carriers, compared with patients with end-stage liver disease (ESLD) (corrected P value [Pc],.0002) and, especially, with patients who had HCC (Pc=.003). The frequency of the HLA-B18 allele was increased in patients with HCC, and the allele was absent in HCV carriers (Pc=.003). The MICA-A4 allele was overrepresented in patients with HCC, compared with HCV carriers (Pc=.0002). The DR3/MICA-A4/B18 haplotype was associated with HCC (Pc=.01). In conclusion, HLA-DR11 seems to be protective against the development of severe forms of infection, and the DR3/MICA-A4/B18 haplotype may be an important factor in the progression to the most severe HCV-infection status.

Adult↗

PubMed2004

Association of MHC class I related gene B (MICB) to celiac disease.

BACKGROUND AND AIMS: Celiac disease (CD) is an enteropathic disorder characterized by strong association with HLA-DQ2. Our aim was to investigate whether MICB, a gene located in the MHC class I region, may contribute to CD susceptibility. PATIENTS AND METHODS: Total of 133 CD patients, previously reported to be associated with MICA-A5.1, and 116 controls were initially analyzed. Twenty-eight additional DQ2-negative CD patients were also studied. MICB was typed by PCR using sequence-specific primers. HLA-B, -DRB1, -DQA1, -DQB1, and MICA were also typed. RESULTS: The allele MICB0106 was strongly associated with CD (pc < 0.000001, odds ratio (OR) = 5.6, 95% confidence interval (CI) = 3.1-10.1) and it was overrepresented in atypical patients compared with typical ones (pc = 0.04, OR = 2.9, CI = 1.4-6.1). MICB0106 was part of DR3-DQ2 haplotype (B8-MICA-A5.1-MICB0106-DR3-DQ2), and consequently a strong linkage disequilibrium between MICB0106 with DQ2 (lambdas = 1) and MICA-A5.1 (lambdas = 0.55) was found. To analyze whether the association of MICB is independent of this haplotype, its association was also studied in DQ2-negative patients (n = 46). DQ8 (28%vs 9%, p = 0.0085, pc = NS) and MICB0104 (52%vs 30%, p = 0.01, pc = NS) were increased in DQ2-negative patients. MICA-A5.1 was significantly increased in atypical patients (p(c)= 0.001, OR = 6.4, CI = 2.2-18.4), and this association was independent of DQ2 and DQ8 (pc = 0.02, OR = 2.6, CI = 1.1-6.1). CONCLUSIONS: The expression of MIC genes on enterocytes under stressful conditions and their function as ligands of intraepithelial gammadelta and CD8 T cells, together with the data presented here suggest a potential role of MIC genes in the pathogenesis of CD.

Adult↗

PubMed2004

MHC class I region plays a role in the development of diverse clinical forms of celiac disease in a Saharawi population.

OBJECTIVE: The aim of this study was to investigate the association of MHC genes in the development of celiac disease (CD) and its diverse clinical forms in a Saharawi population. METHODS: One hundred and twenty-five CD patients and 98 healthy controls were selected from the Saharawi refugee camps in Tindouf. All were investigated for the presence of antitransglutaminase 2 antibodies. Patients were divided into two groups according to their clinical manifestations: 70 typical and 55 atypical. Patients and controls were typed for HLA-B, DRB1, DQB1, and DQA1, and for MICA transmembrane polymorphism. RESULTS: The frequency of HLA-DQ2 in Saharawi controls was notably increased compared with other populations. No differences in the distribution of DQ2 in either group of patients were found. However, the haplotype B8/DR3/DQ2 was notably overrepresented in atypical patients compared to typical ones (pc= 0.001). The MICA-A5.1 allele was increased in atypical CD patients compared to those with typical forms (pc= 0.0006). Finally, we found that the increased frequency of MICA-A5.1 in the atypical group was independent of the linkage disequilibrium with B8/DR3/DQ2 haplotype (p= 0.02). CONCLUSIONS: The elevated prevalence of CD in Saharawi seems to be related to the high frequency of HLA-DQ2 in this population. However, the development of atypical or typical forms of the disease may be due to a gene or genes located in the class I side of the haplotype B8/DR3/DQ2, especially MICA. This appears not to be implicated in the susceptibility to CD but may play an important role in the development of the different forms of the disease.

Adult↗

PubMed2003

MICB typing by PCR amplification with sequence specific primers.

MICB is a member of the MIC (MHC class I chain-related gene) family. Sixteen MICB alleles have been described; however, the functional relevance and population distribution of MICB alleles or their potential association to disease has not yet been evaluated. In this study, we have developed a PCR system using sequence-specific primers (PCR-SSP) that allows unambiguous amplification of all MICB alleles. This approach has been applied to type 100 healthy unrelated individuals from the Spanish population. The extent of polymorphism in this population is lower than that initially expected, and only nine alleles were detected. The alleles MICB01021 (46%), MICB0103101 (13.5%), MICB0104 (13.5%) and MICB0106 (12.5%) were found to be the most frequent alleles. HLA-B and MICA transmembrane polymorphism typing were also performed in this population. Our data showed that MICB is in linkage disequilibrium with MICA and even with HLA-B. Thus, the linkage disequilibrium with MICA and HLA-B suggests that MICB is a potential candidate for those diseases classically associated with HLA class I alleles.

Alleles↗

PubMed2003

MHC class I chain-related gene A transmembrane polymorphism modulates the extension of ulcerative colitis.

Recent evidence from several studies has suggested a genetic predisposition in the pathogenesis of ulcerative colitis (UC), which is especially related with major histocompatibility complex (MHC) genes. The aim of this study was to investigate the possible association of human leukocyte antigen (HLA-B, HLA-DR) and MHC class I chain-related-transmembrane (MICA-TM) polymorphism with the behavior and extension of UC. We selected 121 unrelated patients with UC. These were divided into two groups according to the extension of the disease: 31 patients with distal UC and 90 with wide extension UC; 116 blood donors were also selected as healthy controls, all of whom were typed for HLA-B, HLA-DR, and MICA-TM alleles. HLA-B7 was found to be overrepresented in distal UC patients compared with those with extensive UC (p(c) = 0.007, OR = 5.33) and healthy controls (p(c) = 0.03, OR = 4.09). The MICA-A5.1 allele was also increased in distal UC (p(c) = 0.015, OR = 3.82) when compared with extensive forms. These alleles are in strong linkage disequilibrium in our population. The MICA-A5 allele was significantly increased in extensive forms when compared with healthy controls(p(c) = 0.02, OR = 2.4). According to our results, MICA-A5.1 allele seems to be protective against extensive forms of UC, and MICA-A5 may condition a worse progression of the disease. These results are in agreement with other studies that suggest a similar role of such alleles in other diseases, such as insulin-dependent diabetes mellitus and celiac disease.

Age of Onset↗

PubMed2003

TNF-alpha -308A promoter polymorphism is associated with enhanced TNF-alpha production and inflammatory activity in Crohn's patients with fistulizing disease.

OBJECTIVE: Tumor necrosis factor-alpha (TNF-alpha) plays a key role in the inflammatory response and pathogenesis of Crohn's disease (CD). TNF-alpha -308A polymorphism within the TNF-alpha gene promoter has been associated with enhanced TNF-alpha production in vitro. The aim of this study was to investigate the effect of TNF-alpha promoter polymorphism at -308 on the susceptibility and phenotypic expression of fistulizing CD. METHODS: The distribution of -308 TNF-alpha genotypes was analyzed in 50 patients with fistulizing CD and 100 healthy matched controls. TNF-alpha, interleukin-1beta, and interleukin-6 serum levels were measured by ELISA. Serum amyloid-A, C-reactive protein, alpha1-antitrypsin, alpha1-acid glycoprotein, and haptoglobin were measured by nephelometry. RESULTS: No significant differences were found in the allele frequencies of the polymorphism between patients and controls. However, compared with -308GG patients, those carrying -308AG had a significant increase of serum levels of TNF-alpha (58 +/- 79 vs 8 +/- 19 pg/ml, p < 0.001), interleukin-1beta (36 +/- 45 vs 16 +/- 20 pg/ml, p = 0.048), and acute phase proteins (APPs). -308A carriers had also a higher frequency of arthritis (66% vs 26%, p = 0.039). The logistic regression model showed that the patients carrying -308A polymorphism had a relative risk for developing arthritis of 5.45 (95% CI = 1.1-25.6). No other clinical or analytical findings were predictive for the risk of development of arthritis. CONCLUSIONS: TNF-alpha -308A polymorphism is associated with enhanced TNF-alpha production, more intense inflammatory activity, and an increased risk for arthritis susceptibility in CD patients with fistulizing disease.

Acute-Phase Proteins↗

PubMed2003

HLA antigens may influence the age of onset of psoriasis and psoriatic arthritis.

OBJECTIVE: To analyze whether HLA antigens may influence the age of onset of both psoriasis and psoriatic arthritis (PsA). METHODS: One hundred thirty-five patients with PsA (77 men, 58 women, mean age 47 +/- 12 yrs) were analyzed. All were studied with a standard protocol and consecutively recruited to evaluate the relative contribution of HLA-Cw and HLA-B27 alleles to PsA susceptibility. Fifty patients with psoriasis alone were also recruited to analyze the role of HLA-Cw genes on disease susceptibility. HLA-Cw antigens were investigated by DNA based methods (PCR-SSOP), while HLA-B27 antigen was studied using serological methods, and their frequencies were compared to 177 healthy controls. RESULTS: In PsA Cw6+ patients, the mean age at psoriasis onset was 23 +/- 12 years compared to 32 +/- 12 years in Cw6- patients (p = 0.012). Age of arthritis onset was 35 +/- 13 years in Cw6+ patients versus 38 +/- 12 years in Cw6- patients (p = NS). In patients with psoriasis alone, the age at onset was 18 +/- 10 years in Cw6+ versus 30 +/- 11 years in Cw6- patients (p < 0.01). Cw6 correlated well with a positive family history of psoriasis among first-degree relatives (64% of patients with family history were Cw6+, whereas only 30% of those without family history had this allele (p < 0.05). The onset age of psoriasis in HLA-B27+ patients was 24 +/- 8 years vs 32 +/- 14 years in B27- patients (p = 0.026), whereas onset age of arthritis was 30 +/- 10 years in B27+ compared to an age of onset of 40 +/- 12 in B27- patients (p = 0.0056). CONCLUSION: Our results confirm the known association between Cw6, early onset psoriasis and positive family history (type I psoriasis). The association between HLA-B27 and earlier onset ages for both psoriasis and arthritis in PsA had not previously been emphasized. The HLA antigens may determine not only disease susceptibility, but also the age of disease onset in psoriasis and PsA.

Adult↗

PubMed2002

Association of ankylosing spondylitis with HLA-B*1403 in a West African population.

OBJECTIVE: To investigate the contribution of HLA class I alleles in the susceptibility to primary ankylosing spondylitis (AS) in West African patients living in Togo. METHODS: A large epidemiologic analysis of 9,065 West African rheumatology patients living in Togo was performed in order to identify those who had AS. Eight Togolese patients with AS were identified. HLA was typed by polymerase chain reaction using sequence-specific oligonucleotide probes. DNA typing was also performed on a control population of 85 healthy subjects matched for ethnic background. RESULTS: A significant association between AS and B*14 was identified. This allele was found in 62.5% of the AS patients (odds ratio 69), but was carried by only 2% of the healthy controls. Analysis for B14 subtypes showed that B*1403 was the predominant allele in AS patients (odds ratio 171), and that this allele was absent in healthy controls. B27 was virtually absent, being observed in only 1 AS patient (B*2705). CONCLUSION: HLA-B*1403 shows the B27 "supertype" motif and may exert an effect on AS susceptibility according to the arthritogenic peptide model. The association of B*1403 with AS has not previously been reported in either population.

Adult↗

PubMed2002

HFE gene mutations in alcoholic and virus-related cirrhotic patients with hepatocellular carcinoma.

OBJECTIVE: The increased risk of developing hepatocellular carcinoma in hereditary hemochromatosis has been associated with cirrhosis and hepatic iron overload. The aim of this study was to investigate the association between HFE gene mutations (C282Y, H63D) and hepatocellular carcinoma in patients with alcoholic and virus-related cirrhosis. METHODS: Serum markers of iron status and HFE mutations were determined in 179 patients with alcoholic cirrhosis and 98 patients with hepatitis B and/or hepatitis C virus-related cirrhosis. A total of 43 patients with alcoholic cirrhosis and 34 patients with virus-related cirrhosis had hepatocellular carcinoma. The control group consisted of 159 healthy bone marrow donors. RESULTS: No differences were found in the frequencies of mutations among patients with alcoholic cirrhosis, those with virus-related cirrhosis, and the control subjects. However, nine (20.9%) of the 43 patients with alcoholic cirrhosis and hepatocellular carcinoma were heterozygous for the C282Y mutation, compared with six (4.4%) of the 136 patients without tumor (p = 0.002). This difference was not found in patients with virus-related cirrhosis, with or without hepatocellular carcinoma, or the H63D mutation. The transferrin saturation was the only serum iron marker the value of which was significantly higher among C282Y heterozygotes with alcoholic cirrhosis compared to those without mutation. CONCLUSIONS: The high frequency of heterozygosity for the C282Y mutation in patients with alcoholic cirrhosis plus hepatocellular carcinoma suggests that the presence of this mutation could be associated with an increased risk of developing hepatocellular carcinoma in these patients.

Adult↗

PubMed2002

High serum tumor necrosis factor-alpha levels are associated with lack of response to infliximab in fistulizing Crohn's disease.

OBJECTIVES: Infliximab, a chimeric monoclonal antibody directed against tumor necrosis factor-alpha (anti-TNF-alpha), has been effective in the treatment of patients with active Crohn's disease and with fistulas. We investigated the effect of infliximab on circulating cytokines and acute phase proteins in patients with fistulas to determine the clinical response to anti-TNF-alpha. METHODS: A total of 36 patients with fistulizing Crohn's disease were selected for study. Serum from patients was drawn before the infusion on day 0 and at wk 2, 4, 6, 8, and 10 after completion of treatment. Circulating concentrations of TNF-alpha, interleukin-1beta (IL-1beta), and IL-6 were measured by ELISA. The functional activity of circulating TNF-alpha was assessed by the WEHI 164 TNF-alpha bioassay. Acute phase proteins were also determined. RESULTS: Elevated TNF-alpha, IL-1beta, IL-6, and acute phase proteins were observed in patients with Crohn's disease. Of the patients with fistulas, 22 (61.1%) responded to treatment. Before receiving infliximab, higher levels of serum TNF-alpha were found in patients who did not respond to infliximab compared with those who did (median interquartile range 26, 0-245 pg/ml; n = 14 vs 0, 0-22 pg/ml, n = 22). Patients showed no change in circulating levels of TNF-alpha during the course of the study. CONCLUSIONS: This treatment produces a clinical improvement in about two-thirds of CD patients with fistulas. The circulating levels of TNF-alpha are associated with the response to infliximab and could help to identify patients who would benefit from anti-TNF-alpha treatment.

Acute-Phase Proteins↗

PubMed2002

MICA rather than MICB, TNFA, or HLA-DRB1 is associated with susceptibility to psoriatic arthritis.

OBJECTIVE: To analyze the genetic contribution of HLA in development of psoriatic arthritis (PsA) and to study whether MICA is primarily associated with PsA or whether its association is secondary to linkage disequilibrium with centromeric genes, such as MICB, TNFA, or HLA-DRB1. METHODS: DNA samples from 81 Spanish patients with PsA and 110 healthy controls were examined by polymerase chain reaction (PCR) sequence-specific primers to type HLA-Cw and HLA-DRB1, PCR sequence-specific oligonucleotides to determine HLA-B, and PCR restriction fragment length polymorphism for tumor necrosis factor-alpha promoter polymorphisms at positions -238 and -308. Analysis of microsatellite polymorphisms in the transmembrane region of MICA and in intron 1 of MICB was also carried out. RESULTS: HLA-Cw*0602 was significantly increased in PsA [60% vs 17%; p(c) < 0.00002, OR 7.33, etiological fraction (EF) 0.52]. MICA-A9 (60% vs 30%; p(c) = 0.0002, OR 3.57, EF 0.43) and the microsatellite MICB-CA-22 allele (23% vs 7%; p(c) = 0.028, OR 3.9, EF 0.17) were also significantly increased in PsA. MICA-A9 was in linkage disequilibrium with MICB-CA-22 (delta = 0.6). The association of MICA-A9 was independent of MICB-CA-22 and Cw*0602, since it was also associated in MICB-CA-22 negative (p(c) = 0.0015, OR 2.96, EF 0.34) and in Cw*0602 negative patients (p(c) = 0.034, OR 2.83, EF 0.34). TNFA and DRB I alleles were not significantly associated with PsA. CONCLUSION: Cw*0602 and MICA-A9 appear to be the strongest genetic susceptibility factors for PsA. However, MICA-A9 was associated independently of Cw6. HLA-B alleles and MICB-CA22 are associated secondarily to linkage with MICA. TNFA and HLA-DRB1 were not associated with PsA susceptibility, and our data suggest that their reported association may only reflect the linkage disequilibrium with MICA-A9 among the different populations studied.

Adult↗