Co-stimulatory molecules are essential in the orchestration of immune response and polymorphisms in their genes are associated with various diseases. However, in the case of variable allele frequencies among continental populations, this variation can lead to biases in genetic studies conducted in admixed populations such as those from Brazil. The aim of this study was to evaluate the influence of genomic ancestry on distributions of co-stimulatory genes polymorphisms in an admixed Brazilian population. A total of 273 individuals from the north of Brazil participated in this study. Nine single nucleotide polymorphisms in 7 genes (CD28, CTLA4, ICOS, CD86, CD40, CD40L and BLYS) were determined by polymerase chain reaction-restriction fragment length polymorphism. We also investigated 48 insertion/deletion ancestry markers to characterize individual African, European and Amerindian ancestry proportions in the samples. The analysis showed that the main contribution was European (43.9%) but also a significant contribution of African (31.6%) and Amerindian (24.5%) ancestry. ICOS, CD40L and CD86 polymorphisms were associated with genomic ancestry. However there were no significant differences in the proportions of ancestry for the other SNPs and haplotypes studied. Our findings reinforce the need to apply AIMs in genetic association studies involving these polymorphisms in the Brazilian population.
The development of an effective immune response can help decrease mortality from malaria and its clinical symptoms. However, this mechanism is complex and has significant inter-individual variation, most likely owing to the genetic contribution of the human host. Therefore, this study aimed to investigate the influence of polymorphisms in genes involved in the costimulation of B-lymphocytes in the naturally acquired humoral immune response against proteins of the asexual stage of Plasmodium vivax. A total of 319 individuals living in an area of malaria transmission in the Brazilian Amazon were genotyped for four SNPs in the genes CD40, CD40L, BLYS and CD86. In addition, IgG antibodies against P. vivax apical membrane antigen 1 (PvAMA–1), Duffy binding protein (PvDBP) and merozoite surface protein 1 (PvMSP–119) were detected by ELISA. The SNP BLYS –871C>T was associated with the frequency of IgG responders to PvAMA–1 and PvMSP–119. The SNP CD40 –1C>T was associated with the IgG response against PvDBP, whereas IgG antibody titers against PvMSP–119 were influenced by the polymorphism CD86 +1057G>A. These data may help to elucidate the immunological aspects of vivax malaria and consequently assist in the design of malaria vaccines.
Interleukin 2 (IL-2) is a monomeric glycoprotein that is primarily produced by activated CD4+ T cells, CD8+ T cells and dendritic cells. It is characterized as a proinflammatory cytokine that is secreted by Th1 cells. IL-2 plays a central role in the activation of regulatory T cells to produce the cytokines tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). IL-2 may also enhance the cytolytic activity of natural killer cells, thereby ensuring their significance in the control of the immune response, and effectively participate in the pathogenesis of several pathological conditions, such as cancer and metabolic, infectious, autoimmune and inflammatory diseases. We emphasize the importance of studies of IL-2 and discuss perspectives resulting from our increasing understanding of genetic diversity and its role in the immune response.
Background Humoral immune responses against proteins of asexual blood-stage malaria parasites have been associated with clinical immunity. However, variations in the antibody-driven responses may be associated with a genetic component of the human host. The objective of the present study was to evaluate the influence of co-stimulatory molecule gene polymorphisms of the immune system on the magnitude of the humoral immune response against a Plasmodium vivax vaccine candidate antigen.MethodsPolymorphisms in the CD28, CTLA4, ICOS, CD40, CD86 and BLYS genes of 178 subjects infected with P. vivax in an endemic area of the Brazilian Amazon were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The levels of IgM, total IgG and IgG subclasses specific for ICB2-5, i.e., the N-terminal portion of P. vivax merozoite surface protein 1 (PvMSP-1), were determined by enzyme-linked immuno assay. The associations between the polymorphisms and the antibody response were assessed by means of logistic regression models.ResultsAfter correcting for multiple testing, the IgG1 levels were significantly higher in individuals recessive for the single nucleotide polymorphism rs3116496 in CD28 (p = 0.00004). Furthermore, the interaction between CD28 rs35593994 and BLYS rs9514828 had an influence on the IgM levels (p = 0.0009).ConclusionsThe results of the present study support the hypothesis that polymorphisms in the genes of co-stimulatory components of the immune system can contribute to a natural antibody-driven response against P. vivax antigens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1350-2) contains supplementary material, which is available to authorized users.
The results of this study show that, although the investigated CD40, CD40L and BLYS alleles differ functionally, this variation does not alter the functionality of the molecules in a way that would interfere in susceptibility to the disease. The variants of these genes may influence the clinical course rather than simply increase or decrease susceptibility.
Background
It is well established that infection by Plasmodium vivax is a result of host-parasite interactions. In the present study, association with the IL1/IL2 cytokine profiles, anticircumsporozoite protein antibody levels and parasitic loads was evaluated in individuals naturally infected with P. vivax in an endemic area of the Brazilian Amazon.
Methods
Molecular diagnosis of P. vivax and variants was performed using the PCR-RFLP method and IL1B -511C>T, IL2 -330T>G and IL2+114T>G polymorphisms were identified using PCR-RFLP and allele-specific PCR. IL-1β and IL-2 cytokine levels were detected by flow cytometry and circumsporozoite protein (CSP) antibodies were measured by ELISA.
Results
Three variants of P. vivax CSP were identified and VK247 was found to be the most frequent. However, the prevalence and magnitude of IgG antibodies were higher for the VK210 variant. Furthermore, the antibody response to the CSP variants was not associated with the presence of the variant in the infection. Significant differences were observed between the single nucleotide polymorphism (SNP) -511T>C in the IL1B gene and levels of antibodies to the VK247 and P. vivax-like variants, but there were no associations between SNPs in IL1 and IL2 genes and their plasma products.
Conclusions
Individuals with the rs16944 CC genotype in the IL1β gene have higher antibody levels to the CSP of P. vivax of VK247 and P. vivax-like variants.
Polymorphisms in cytokine genes can alter the production of these proteins and consequently affect the immune response. The trihybrid heterogeneity of the Brazilian population is characterized as a condition for the use of ancestry informative markers. The objective of this study was to evaluate the frequency of -1031T>C, -308G>A and -238G>A TNFA, +874 A>T IFNG and -819C>T, and -592C>A IL10 gene polymorphisms and their association with malaria vivax and genomic ancestry. Samples from 90 vivax malaria-infected individuals and 51 noninfected individuals from northern Brazil were evaluated. Genotyping was carried out by using ASO-PCR or PCR/RFLP. The genomic ancestry of the individuals was classified using 48 insertion/deletion polymorphism biallelic markers. There were no differences in the proportions of African, European, and Native American ancestry between men and women. No significant association was observed for the allele and genotype frequencies of the 6 SNPs between malaria-infected and noninfected individuals. However, there was a trend toward decreasing the frequency of individuals carrying the TNF-308A allele with the increasing proportion of European ancestry. No ethnic-specific SNPs were identified, and there was no allelic or genotype association with susceptibility or resistance to vivax malaria. Understanding the genomic mechanisms by which ancestry influences this association is critical and requires further study.
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