RESUMO
INTRODUCTION: Non-classical class I human leukocyte antigens (HLA) molecules are known to modulate the function of cytotoxic cells (NK and T CD8+) during viral infection by interacting with inhibitory/activating receptors. However, little is known about the HLA-E/-F genetic variability on arbovirus infections. METHODS: We evaluated by massive parallel sequencing the full HLA-E/-F genetic diversity among patients infected during the arbovirus (ZIKV, DENV, and CHIKV) outbreak leading to a broad range of neurological complications in the Brazilian State of Pernambuco. In parallel, healthy blood donors from the same area were also studied. Plink and R software were used for genetic association study. To limit the false-positive results and enhance the reliability of the results, we adopted P-values <0.01 as significant levels. RESULTS: Compared to controls, the HLA-F alleles: -1610 C (rs17875375), +1383 G (rs17178385), and +3537 A (rs17875384), all in complete linkage disequilibrium with each other (r2 = 1), were overrepresented in patients presenting peripheral spectrum disorders (PSD). The HLA-F*Distal-D haplotype that harbored the -1610 C allele exhibited a trend increase in PSD group. No associations were found for HLA-E. CONCLUSIONS: Our findings showed that the HLA-F genetic background seems to be more important than HLA-E on the susceptibility to PSD complications.
Assuntos
Infecções por Arbovirus/genética , Infecções por Arbovirus/virologia , Predisposição Genética para Doença/genética , Variação Genética/genética , Antígenos de Histocompatibilidade Classe I/genética , Doenças do Sistema Nervoso/genética , Doenças do Sistema Nervoso/virologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Alelos , Arbovírus/patogenicidade , Brasil , Criança , Feminino , Frequência do Gene/genética , Estudos de Associação Genética/métodos , Haplótipos/genética , Humanos , Desequilíbrio de Ligação/genética , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
HLA-F is one of the most conserved loci among the HLA gene family. The exact function of HLA-F is still under investigation. HLA-F might present tolerogenic features, participate in the stabilization of HLA molecules in open conformation, and also participate in the recycling of HLA molecules. Here we evaluate the variability and haplotype structure of the HLA-F distal promoter segment (from -1893 to -943) and how this segment is correlated with the coding region. Variability at the promoter segment was surveyed in 196 Brazilian samples using second-generation sequencing. The HLA-F promoter region presents two major haplotype lineages. Most of the variable sites are in perfect linkage and associated with a single promoter haplotype, here named F∗distal-C. This haplotype is associated with F∗01:01:02 alleles, while alleles from the F∗01:01:01 or F∗01:03 groups present closely related promoter sequences. F∗distal-C is quite frequent in Brazil and in worldwide populations, with frequencies ranging from 8.41% at the Iberian Population in Spain to 34.34% in Vietnam. F∗distal-C is also present in Neanderthal and Denisovan samples. In silico analyses demonstrated that F∗distal-C presents a different transcription factor binding profile compared with other HLA-F promoters. Moreover, individuals carrying this haplotype present higher HLA-F mRNA expression levels. Functional studies are required to define the exact mechanism underlying this higher HLA-F mRNA expression level associated with F∗distal-C and F∗01:01:02 alleles.
Assuntos
Antígenos de Histocompatibilidade Classe I/genética , Regiões Promotoras Genéticas/genética , RNA Mensageiro/genética , Animais , Brasil , Regulação da Expressão Gênica , Frequência do Gene , Genética Populacional , Haplótipos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Desequilíbrio de Ligação , Homem de Neandertal/genética , Polimorfismo GenéticoRESUMO
Human Leucocyte Antigen F (HLA-F) is a non-classical HLA class I gene distinguished from its classical counterparts by low allelic polymorphism and distinctive expression patterns. Its exact function remains unknown. It is believed that HLA-F has tolerogenic and immune modulatory properties. Currently, there is little information regarding the HLA-F allelic variation among human populations and the available studies have evaluated only a fraction of the HLA-F gene segment and/or have searched for known alleles only. Here we present a strategy to evaluate the complete HLA-F variability including its 5' upstream, coding and 3' downstream segments by using massively parallel sequencing procedures. HLA-F variability was surveyed on 196 individuals from the Brazilian Southeast. The results indicate that the HLA-F gene is indeed conserved at the protein level, where thirty coding haplotypes or coding alleles were detected, encoding only four different HLA-F full-length protein molecules. Moreover, a same protein molecule is encoded by 82.45% of all coding alleles detected in this Brazilian population sample. However, the HLA-F nucleotide and haplotype variability is much higher than our current knowledge both in Brazilians and considering the 1000 Genomes Project data. This protein conservation is probably a consequence of the key role of HLA-F in the immune system physiology.
Assuntos
Antígenos de Histocompatibilidade Classe I/genética , Sistema Imunitário/fisiologia , Fases de Leitura Aberta/genética , Sequências Reguladoras de Ácido Nucleico/genética , Brasil , Etnicidade , Frequência do Gene , Genética Populacional , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Teste de Histocompatibilidade , Humanos , Imunomodulação , Polimorfismo GenéticoRESUMO
HLA-F is a non-classical major histocompatibility complex (MHC) gene. It codes class Ib MHC molecules with restricted distribution and less nucleotide variations than MHC class Ia genes. Of the 22 alleles registered on the IMGT database only four alleles encode for proteins that differ in their primary structure. To estimate genotype and allele frequencies, this study targeted on known protein coding regions of the HLA-F gene. Genotyping was performed by Sequence Base Typing (SBT). The sample was composed by 199-unrelated bone marrow donors from the Brazilian Bone Marrow Donor Registry (REDOME), Euro-Brazilians, from Southern Brazil. About 1673 bp were analyzed. The most frequent allele was HLA-F*01:01 (87.19%), followed by HLA-F*01:03 (12.31%), HLA-F*01:02 (0.25%) and HLA-F*01:04 (0.25%). Significant linkage disequilibrium (LD) was verified between HLA-F and HLA classes I and II alleles. This is the first study regarding HLA-F polymorphisms in a Euro-Brazilian population contributing to the Southern Brazilian genetic characterization.