RESUMO
Spontaneous clearance of acute hepatitis C virus (HCV) infection is associated with single nucleotide polymorphisms (SNPs) on the MHC class II. We fine-mapped the MHC region in European (n = 1,600; 594 HCV clearance/1,006 HCV persistence) and African (n = 1,869; 340 HCV clearance/1,529 HCV persistence) ancestry individuals and evaluated HCV peptide binding affinity of classical alleles. In both populations, HLA-DQß1Leu26 (p valueMeta = 1.24 × 10-14) located in pocket 4 was negatively associated with HCV spontaneous clearance and HLA-DQß1Pro55 (p valueMeta = 8.23 × 10-11) located in the peptide binding region was positively associated, independently of HLA-DQß1Leu26. These two amino acids are not in linkage disequilibrium (r2 < 0.1) and explain the SNPs and classical allele associations represented by rs2647011, rs9274711, HLA-DQB1∗03:01, and HLA-DRB1∗01:01. Additionally, HCV persistence classical alleles tagged by HLA-DQß1Leu26 had fewer HCV binding epitopes and lower predicted binding affinities compared to clearance alleles (geometric mean of combined IC50 nM of persistence versus clearance; 2,321 nM versus 761.7 nM, p value = 1.35 × 10-38). In summary, MHC class II fine-mapping revealed key amino acids in HLA-DQß1 explaining allelic and SNP associations with HCV outcomes. This mechanistic advance in understanding of natural recovery and immunogenetics of HCV might set the stage for much needed enhancement and design of vaccine to promote spontaneous clearance of HCV infection.
Assuntos
Cadeias beta de HLA-DQ/genética , Hepacivirus/patogenicidade , Hepatite C/genética , Interações Hospedeiro-Patógeno/genética , Polimorfismo de Nucleotídeo Único , Doença Aguda , Alelos , Substituição de Aminoácidos , População Negra , Feminino , Expressão Gênica , Estudo de Associação Genômica Ampla , Genótipo , Cadeias beta de HLA-DQ/imunologia , Hepacivirus/crescimento & desenvolvimento , Hepacivirus/imunologia , Hepatite C/etnologia , Hepatite C/imunologia , Hepatite C/virologia , Interações Hospedeiro-Patógeno/imunologia , Humanos , Leucina/imunologia , Leucina/metabolismo , Masculino , Prolina/imunologia , Prolina/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Remissão Espontânea , População BrancaRESUMO
The clinical spectrum of hypertensive disorders of pregnancy (HDP) is determined by the interplay between environmental and genetic factors, most of which remains unknown. ERAP1, ERAP2 and LNPEP genes code for multifunctional aminopeptidases involved with antigen processing and degradation of small peptides such as angiotensin II (Ang II), vasopressin and oxytocin. We aimed to test for associations between genetic variants in aminopeptidases and HDP. A total of 1282 pregnant women (normotensive controls, n = 693; preeclampsia, n = 342; chronic hypertension with superimposed preeclampsia, n = 61; eclampsia, n = 74; and HELLP syndrome, n = 112) were genotyped for variants in LNPEP (rs27300, rs38034, rs2303138), ERAP1 (rs27044, rs30187) and ERAP2 (rs2549796 rs2927609 rs11135484). We also evaluated the effect of ERAP1 rs30187 on plasma Ang II levels in an additional cohort of 65 pregnant women. The genotype C/C, in ERAP1 rs30187 variant (c.1583 T > C, p.Lys528Arg), was associated with increased risk of eclampsia (OR = 1.85, p = 0.019) whereas ERAP2 haplotype rs2549796(C)-rs2927609(C)-rs11135484(G) was associated with preeclampsia (OR = 1.96, corrected p-value = 0.01). Ang II plasma levels did not differ across rs30187 genotypic groups (p = 0.895). In conclusion, ERAP1 gene is associated with eclampsia whereas ERAP2 is associated with preeclampsia, although the mechanism by which genetic variants in ERAPs influence the risk of preeclampsia and eclampsia remain to be elucidated.
Assuntos
Aminopeptidases/genética , Eclampsia/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Antígenos de Histocompatibilidade Menor/genética , Pré-Eclâmpsia/genética , Alelos , Brasil/epidemiologia , Eclampsia/diagnóstico , Eclampsia/epidemiologia , Feminino , Frequência do Gene , Genótipo , Síndrome HELLP/diagnóstico , Síndrome HELLP/epidemiologia , Síndrome HELLP/genética , Haplótipos , Humanos , Desequilíbrio de Ligação , Modelos Genéticos , Razão de Chances , Fenótipo , Vigilância da População , Pré-Eclâmpsia/diagnóstico , Pré-Eclâmpsia/epidemiologia , Gravidez , Reprodutibilidade dos TestesRESUMO
Background: Cryptosporidium species are enteric protozoa that cause significant morbidity and mortality in children worldwide. We characterized the epidemiology of Cryptosporidium in children from 8 resource-limited sites in Africa, Asia, and South America. Methods: Children were enrolled within 17 days of birth and followed twice weekly for 24 months. Diarrheal and monthly surveillance stool samples were tested for Cryptosporidium by enzyme-linked immunosorbent assay. Socioeconomic data were collected by survey, and anthropometry was measured monthly. Results: Sixty-five percent (962/1486) of children had a Cryptosporidium infection and 54% (802/1486) had at least 1 Cryptosporidium-associated diarrheal episode. Cryptosporidium diarrhea was more likely to be associated with dehydration (16.5% vs 8.3%, P < .01). Rates of Cryptosporidium diarrhea were highest in the Peru (10.9%) and Pakistan (9.2%) sites. In multivariable regression analysis, overcrowding at home was a significant risk factor for infection in the Bangladesh site (odds ratio, 2.3 [95% confidence interval {CI}, 1.2-4.6]). Multiple linear regression demonstrated a decreased length-for-age z score at 24 months in Cryptosporidium-positive children in the India (ß = -.26 [95% CI, -.51 to -.01]) and Bangladesh (ß = -.20 [95% CI, -.44 to .05]) sites. Conclusions: This multicountry cohort study confirmed the association of Cryptosporidium infection with stunting in 2 South Asian sites, highlighting the significance of cryptosporidiosis as a risk factor for poor growth. We observed that the rate, age of onset, and number of repeat infections varied per site; future interventions should be targeted per region to maximize success.
Assuntos
Criptosporidiose/epidemiologia , Diarreia/epidemiologia , Áreas de Pobreza , África/epidemiologia , Ásia/epidemiologia , Pré-Escolar , Estudos de Coortes , Aglomeração , Cryptosporidium/isolamento & purificação , Diarreia/parasitologia , Fezes/parasitologia , Feminino , Transtornos do Crescimento/parasitologia , Humanos , Lactente , Recém-Nascido , Masculino , Desnutrição/parasitologia , Análise de Regressão , Fatores de Risco , Fatores Socioeconômicos , América do Sul/epidemiologia , Inquéritos e QuestionáriosRESUMO
Genetic risk factors contribute to asymptomatic versus symptomatic visceral leishmaniasis (VL) outcomes following infection with Leishmania infantum. We therefore carried out a family-based (n = 918 post-quality control fully genotyped and phenotyped individuals) candidate gene study for symptomatic VL or asymptomatic delayed-type hypersensitivity (DTH) skin test phenotypes in highly endemic neighborhoods of northeast Brazil. A total of 248 SNPs were genotyped in 42 genes selected as candidates on the basis of prior genetic, immunological, and transcriptional profiling studies. The most significant association with the VL phenotype was with SNP rs6785358 (P = 5.7e-04; pcorrected = 0.026) 3.8 kb upstream of TGFBR2, the gene encoding the type 2 receptor for transforming growth factor beta (TGFß). A second inhibitory member of the TGBß superfamily signaling pathway, SMAD7, was associated with the DTH phenotype (SNP rs7238442: P = 0.001; pcorrected = 0.051). The most significant association for the DTH phenotype was with SNP rs10800309 (P = -8.4e-06; pcorrected = 3.9e-04) situated 3.1 kb upstream of FCGR2A, the gene encoding the low-affinity IIa receptor for the Fc fragment of IgG. Overall, our results imply a role for IgG-mediated inflammation in determining DTH associated with asymptomatic infection and contribute to growing evidence that the TGFß pathway is important in the immunopathogenesis of VL.
Assuntos
Leishmania infantum , Leishmaniose Visceral/genética , Proteínas Serina-Treonina Quinases/genética , Receptores de IgG/genética , Receptores de Fatores de Crescimento Transformadores beta/genética , Adolescente , Infecções Assintomáticas , Brasil , Criança , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Leishmaniose Visceral/parasitologia , Desequilíbrio de Ligação , Masculino , Polimorfismo de Nucleotídeo Único , Receptor do Fator de Crescimento Transformador beta Tipo IIRESUMO
Infection with the protozoan Leishmania infantum can lead to asymptomatic infection and protective immunity, or to the progressive and potentially fatal disease visceral leishmaniasis (VL). Published studies show host genetic background determines in part whether infected individuals will develop a symptomatic or asymptomatic outcome. The purpose of the current study was to fine map chromosome regions previously linked with risk for symptomatic (chromosome 9) or asymptomatic (chromosomes 15 and 19) manifestations of L. infantum infection. We conducted a family-based genetic study of VL and asymptomatic infection (detected by a DTH skin test) with a final post quality control sample of 961 individuals with full genotype and phenotype information from highly endemic neighborhoods of northeast Brazil. A total of 5485 SNPs under the linkage peaks on chromosomes 9, 15 and 19 were genotyped. No strong SNP associations were observed for the DTH phenotype. The most significant associations with the VL phenotype were with SNP rs1470217 (p=5.9e-05; pcorrected=0.057) on chromosome 9, and with SNP rs8107014 (p=1.4e-05; pcorrected=0.013) on chromosome 19. SNP rs1470217 is situated in a 180kb intergenic region between TMEM215 (Transmembrane protein 215) and APTX (Aprataxin). SNP rs8107014 lies in the intron between exons 26 and 27 of a 34 exon transcript (ENST00000204005) of LTBP4, (Latent transforming growth factor-beta-binding protein 4a). The latter supports growing evidence that the transforming growth factor-beta pathway is important in the immunopathogenesis of VL.
Assuntos
Mapeamento Cromossômico/métodos , Cromossomos Humanos Par 15/genética , Cromossomos Humanos Par 19/genética , Cromossomos Humanos Par 9/genética , Leishmaniose Visceral/genética , Polimorfismo de Nucleotídeo Único , Brasil , Proteínas de Ligação a DNA/genética , Feminino , Ligação Genética , Predisposição Genética para Doença , Genótipo , Humanos , Leishmania infantum/fisiologia , Masculino , Proteínas Nucleares/genética , Linhagem , Fenótipo , Locos de Características QuantitativasRESUMO
BACKGROUND: Preeclampsia is a disease with great variability in incidence across the world. The mortality is higher in lower income countries, where it is the leading cause of maternal mortality. This study aimed to determine the frequency of and risk factors for preeclampsia in a low income population from an urban area of Brazil. METHODS: A prospective case control study of 242 women of which 30 developed preeclampsia, 4 had gestational hypertension, 2 had superimposed hypertension, 11 had spontaneous abortion, 13 were lost to follow up and 192 had normal pregnancy. This latter group was considered the normotensive controls. The rate of preeclampsia and the risk of cardiovascular disease, after onset of preeclampsia, were determined. RESULTS: Of the 218 women who completed the study, the frequency of hypertensive disorder of pregnancy was 16.5% (36 of 218) and of preeclampsia was 13.8% (30 of 218). Women with preeclampsia had a higher body mass index (BMI), mean of 25.3 ± 4.8 compared to 23.5 ± 3.7 for the normotensive controls, p = 0.02. The risk of preeclampsia increased with BMI [Odds ratio (OR) 1.12, 95% Confidence Interval (CI = 1.02;1.24, p-value = 0.023)]. Women with preeclampsia developed chronic hypertension more often than normotensive controls (p = 0.043) and their systolic and ambulatory blood pressure monitoring was elevated (p = 0.034). Women with preeclampsia had higher BMI even 5 years post-pregnancy (p = 0.008). CONCLUSIONS: Women who are overweight or older have an increased risk of preeclampsia. Previous history of preeclampsia increases the risk of early onset of chronic hypertension. Therefore, effective preventive measures are needed, particularly women at lower social economic stratum who have less access to proper medical care and adequate nutrition.
Assuntos
Peso Corporal , Pré-Eclâmpsia/epidemiologia , População Urbana/estatística & dados numéricos , Adolescente , Adulto , Pressão Sanguínea , Índice de Massa Corporal , Brasil/epidemiologia , Estudos de Casos e Controles , Creatinina/sangue , Feminino , Seguimentos , Humanos , Hipertensão/epidemiologia , Pré-Eclâmpsia/sangue , Gravidez , Estudos Prospectivos , Fatores de Risco , Fatores Socioeconômicos , Adulto JovemRESUMO
Visceral leishmaniasis (VL) in northeast Brazil is a disease caused by infection with the protozoan Leishmania chagasi. Infection leads to variable clinical outcomes ranging from asymptomatic infection to potentially fatal disease. Prior studies suggest the genetic background of the host contributes to the development of different outcomes after infection, although it is not known if ancestral background itself influences outcomes. VL is endemic in peri-urban areas around the city of Natal in northeast Brazil. The population of northeast Brazil is a mixture of distinct racial and ethnic groups. We hypothesized that some sub-populations may be more susceptible than others to develop different clinical outcomes after L. chagasi infection. Using microsatellite markers, we examined whether admixture of the population as a whole, or markers likely inherited from a distinct ethnic background, differed between individuals with VL, individuals with an asymptomatic infection, or individuals with no infection. There was no apparent significant difference in overall population admixture proportions among the three clinical phenotype groups. However, one marker on Chr. 22 displayed evidence of excess ancestry from putative ancestral populations among different clinical phenotypes, suggesting this region may contain genes determining the course of L. chagasi infection.
Assuntos
Leishmania/fisiologia , Leishmaniose Visceral/etnologia , Leishmaniose Visceral/genética , Animais , Brasil/etnologia , Humanos , Leishmaniose Visceral/parasitologia , Repetições de MicrossatélitesRESUMO
The protozoan Leishmania chagasi can cause disseminated, fatal visceral leishmaniasis (VL) or asymptomatic infection in humans. We hypothesized that host genetic factors contribute to this variable response to infection. A family study was performed in neighborhoods of endemicity for L. chagasi near Natal in northeastern Brazil. Study subjects were assessed for the presence of VL or asymptomatic infection, which was defined by a positive delayed-type hypersensitivity (DTH) skin test response to Leishmania antigen without disease symptoms. A genomewide panel of 385 autosomal microsatellite markers in 1254 subjects from 191 families was analyzed to identify regions of linkage. Regions with potential linkage to the DTH response on chromosomes 15 and 19, as well as a novel region on chromosome 9 with potential linkage to VL, were identified. Understanding the genetic factors that determine whether an individual will develop symptomatic or asymptomatic infection with L. chagasi may identify proteins essential for immune protection against this parasitic disease and reveal strategies for immunotherapy or prevention.
Assuntos
Cromossomos Humanos Par 15 , Cromossomos Humanos Par 19 , Imunidade Inata/genética , Leishmania/patogenicidade , Leishmaniose/imunologia , Adolescente , Animais , Brasil , Criança , Pré-Escolar , Cromossomos Humanos Par 15/genética , Cromossomos Humanos Par 15/imunologia , Cromossomos Humanos Par 15/parasitologia , Cromossomos Humanos Par 19/genética , Cromossomos Humanos Par 19/imunologia , Cromossomos Humanos Par 19/parasitologia , Doenças Endêmicas , Feminino , Ligação Genética , Humanos , Hipersensibilidade Tardia/genética , Hipersensibilidade Tardia/imunologia , Lactente , Leishmaniose/fisiopatologia , Masculino , FenótipoRESUMO
Few comparison studies have been performed on single nucleotide polymorphism (SNP) tagging methods to examine their consistency and effectiveness in terms of inferences about association with disease. We applied several SNP tagging methods to SNPs on chromosome 12q (n=713) and compared the utility of these methods to detect association for asthma and serum IgE levels among a sample of African Caribbean families from Barbados selected through asthmatic probands. We found that a high level of information regarding association is retained in Clayton's htSNP, Stram's TagSNP, and de Bakker's Tagger. We also found a high degree of consistency between TagSNP and Tagger. Using this set of 713 SNPs on chromosome 12q, our study provides insight towards analytic strategies for future studies of complex traits.
Assuntos
Asma/genética , População Negra/genética , Cromossomos Humanos Par 12/genética , Imunoglobulina E/sangue , Polimorfismo de Nucleotídeo Único/genética , Barbados , Humanos , Desequilíbrio de LigaçãoRESUMO
BACKGROUND: Mucosal leishmaniasis (ML) is associated with exaggerated tumor necrosis factor- alpha and interferon- gamma responses and tissue destruction. ML follows localized cutaneous leishmaniasis (CL) caused by Leishmania braziliensis infection. Interleukin (IL)-6 down-regulates T helper (Th) cell type 1 differentiation and drives Th2 cell differentiation. The IL6 -174 G/C polymorphism is associated with proinflammatory diseases and IL-6 regulation. METHODS: The -174 G/C polymorphism was genotyped in population samples and families with CL and ML from Brazil. Genotype frequencies were compared among patients with ML, patients with CL, and 2 control groups by logistic regression and family-based association test (FBAT) analysis. IL-6 levels were measured in macrophages. RESULTS: The C allele was more common in patients with ML than in patients with CL (odds ratio [OR], 2.55 [95% confidence interval {CI}, 1.32-4.91]; P=.005), than in patients who were leishmanin skin-test positive (OR, 2.23 [95% CI, 1.23-4.05]; P=.009), and than in neighborhood control subjects (OR, 2.47 [95% CI, 1.24-4.90]; P=.01). FBAT analysis confirmed an association between allele C and ML under both additive (z=4.295; P=.000017) and dominant (z=4.325; P=.000015) models. Significantly lower levels of IL-6 were measured in unstimulated macrophages from CC individuals than from GG individuals (P=.003) as well as after stimulation with soluble leishmania antigen (P=.009). CONCLUSIONS: IL-6 may regulate type 1 proinflammatory responses, putting individuals with low macrophage IL-6 levels at increased risk for ML.
Assuntos
Interleucina-6/genética , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/genética , Adulto , Animais , Brasil/epidemiologia , Estudos de Casos e Controles , Feminino , Habitação , Humanos , Interleucina-6/biossíntese , Leishmania braziliensis , Leishmaniose Cutânea/etiologia , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/patologia , Masculino , Pessoa de Meia-Idade , Mucosa , Polimorfismo Genético , Regiões Promotoras Genéticas/genética , Fatores de RiscoRESUMO
Peri-urban visceral leishmaniasis (VL) caused by Leishmania chagasi is emerging in a new epidemiologic pattern in Brazilian cities. We studied peri-urban VL in endemic neighborhoods surrounding Natal, Brazil, identified through hospitalized individuals with VL. Clinical and environmental information obtained for 1106 members of 216 families living in endemic neighborhoods enabled us to identify 4 groups: VL: individuals with current or prior symptomatic visceral leishmaniasis (n = 135); DTH+: individuals with positive delayed-type hypersensitivity response with no history of VL (n = 390); Ab +: individuals with negative DTH response and seropositive (n = 21); DTH -: individuals with negative DTH and seronegative (n = 560). The mean +/-SD age of VL was 9.3+/-12.3 y. The gender distribution was nearly equal below age 5, but skewed toward males at higher ages. Acutely infected VL subjects had significantly lower hematocrits, neutrophils, and eosinophils than other categories. AB+ subjects also had lower eosinophil counts than others, a possible immune marker of early infection. VL was not associated with ownership of dogs or other animals, raising the question whether the reservoir differs in peri-urban settings. This new pattern of L. chagasi infection enables us to identify epidemiological and host factors underlying this emerging infectious disease.