Common haplotypes in CD209 promoter and susceptibility to HIV-1 infection in intravenous drug users

CD46 Genetic Variability and HIV-1 Infection Susceptibility

CD46 is the main receptor for complement protein C3 and plays an important role in adaptive immune responses. CD46 genetic variants are associated with susceptibility to several infectious and autoimmune diseases. Additionally, CD46 function can be subverted by HIV-1 to evade attack by complement, a strategy shared by viruses of other families. We sought to determine the association between CD46 gene variants and HIV-1 acquired through intravenous drug use (IDU) and sexual routes (n = 823). Study subjects were of European ancestry and were HIV-1 infected (n = 438) or exposed but seronegative (n = 387). Genotyping of the rs2796265 SNP located in the CD46 gene region was done by allele-specific real-time PCR. A meta-analysis merging IDU and sexual cohorts indicates that the minor genotype (CC) was associated with increased resistance to HIV-1 infection OR = 0.2, 95% CI (0.07–0.61), p = 0.004. The HIV-1-protective genotype is correlated with reduced CD46 expression and alterations in the ratio of CD46 mRNA splicing isoforms.

A novel CD209 polymorphism is associated with rheumatoid arthritis patients in Taiwan

Single nucleotide polymorphisms (SNPs) in the promoter region of CD209 (cluster of differentiation 209) may influence expression levels, and higher expression of CD209 on immune cells correlate with severity of cartilage destruction in patients with rheumatoid arthritis (RA). Due to the lack of a comprehensive study, this study aimed to investigate the CD209 promoter variants and haplotypes in a Taiwanese population and the association with RA development. Deoxyribonucleic acid (DNA) of peripheral blood mononuclear cells from 126 RA patients and 124 healthy controls was purified, and the CD209 gene promoter was amplified by polymerase chain reaction and analyzed by Sanger sequencing. Results showed that a novel variant −96C>A polymorphism in CD209 promoter was identified in the Taiwanese population, and the frequency was significantly higher in RA patients than in controls (11.51% vs. 2.42%, P < .0001). The odds ratio (OR) for the development of RA was 5.88 (95% CI 2.35–14.74, P < .0001). Other known variants were also evaluated; for instance, −1180 T/T (rs7359874) was increased in RA patients, and the OR for the development of RA was 3.26, 95% CI 0.85–12.52, P = .07). Besides, the haplotype frequencies were calculated; −1180A‐939C‐871 T‐336 T‐139 T‐96A and −1180 T‐939 T‐871C‐336 T‐139C‐96A were increased in RA patients (P = .004 and 0.05, respectively). In summary, CD209‐96A variant could be an important factor for the development of RA in the Taiwanese population.

CD209 and Not CD28 or STAT6 Polymorphism Mediates Clinical Malaria and Parasitemia among Children from Nigeria

Malaria remains a significant disease, causing epic health problems and challenges all over the world, especially in sub-Saharan Africa. CD209 and CD28 genes act as co-stimulators and regulators of the immune system, while the STAT6 gene has been reported to mediate cytokine-induced responses. Single nucleotide polymorphisms of these genes might lead to differential disease susceptibility among populations at risk for malaria, due to alterations in the immune response. We aim to identify key drivers of the immune response to malaria infection among the three SNPs: CD209 (rs4804803), CD28 (rs35593994) and STAT6 (rs3024974). After approval and informed consent, we genotyped blood samples from a total of 531 children recruited from Nigeria using the Taqman SNP genotyping assay and performed comparative analysis of clinical covariates among malaria-infected children. Our results reveal the CD209 (rs4804803) polymorphism as a susceptibility factor for malaria infection, significantly increasing the risk of disease among children, but not CD28 (rs35593994) or STAT6 (rs3024974) polymorphisms. Specifically, individuals with the homozygous mutant allele (rs4804803G/G) for the CD209 gene have a significantly greater susceptibility to malaria, and presented with higher mean parasitemia. This observation may be due to a defective antigen presentation and priming, leading to an ineffective downstream adaptive immune response needed to combat infection, as well as the resultant higher parasitemia and disease manifestation. We conclude that the CD209 gene is a critical driver of the immune response during malaria infection, and can serve as a predictor of disease susceptibility or a biomarker for disease diagnosis.

Black rockfish C-type lectin, SsCTL4: A pattern recognition receptor that promotes bactericidal activity and virus escape from host immune defense

C-type lectin (CTL) is an immune receptor and is received extensive attention of its important roles in immune response and immune escape. Some CTL, such as CTL4, has been well characterized in human and several other mammals, but much less documentation exists about the immunological function of CTL4 in lower vertebrates. In the present study, a C-type lectin domain family 4 member, SsCTL4, which is also high homology with CD209 antigen-like protein, from the teleost fish black rockfish (Sebastes schlegelii) was identified and examined at expression and functional levels. The open reading frame of SsCTL4 is 765 bp, and the deduced amino acid sequence of SsCTL4 shares 78%-84% overall identities with the C-type lectin of several fish species. In silico analysis identified several conserved C-type lectin features, including a carbohydrate-recognition domain and four disulfide bond-forming cysteine residues. Expression of SsCTL4 occurred in multiple tissues and was upregulated during bacterial and viral infection. Recombinant SsCTL4 (rSsCTL4) exhibited apparent binding activities against bacteria (Edwardsiella tarda and Vibrio anguillarum) and virus (infectious spleen and kidney necrosis virus, ISKNV). rSsCTL4 was able to agglutinate the Gram-negative and Gram-positive bacteria in a Ca²⁺-dependent manner. The agglutinating ability of rSsCTL4 was abolished in the absence of calcium or presence of mannose. rSsCTL4 also increased macrophage bactericidal activity. In the presence of rSsCTL4, fish exhibited enhanced resistance against bacterial infection but increased susceptibility to viral infections. Collectively, these results indicate that SsCTL4 serves as a pattern recognition receptor that not only promotes bactericidal activity, but may also serve as targets for virus manipulation of host defense system.

Genetic and immune determinants of immune activation in HIV-exposed seronegative individuals and their role in protection against HIV infection

Soon thereafter infection is established, hosts strive for an efficient eradication of microorganisms, with as limited tissue damage as possible, and durable immunological protection against re-infection. On the other hand, pathogens have developed countermeasures to escape host surveillance and to warrant diffusion to other hosts. In this molecular arms race the final results relies on multiple variables, including the genetic and immunologic e correlates of protection available for the host. In the field of HIV-infection, natural protection has been repeatedly associated to the presence of an immune activation state, at least in some cohorts of HESN (HIV-exposed seronegative). Indeed, these subjects, who naturally resist HIV-infection despite repeated exposure to the virus, are characterized by an increased expression of activation markers on circulating cells and greater production of immunological effector molecules both in basal condition and upon specific-stimulation. Although these results are not univocally shared, several publications emphasize the existence of a correlation between polymorphisms in genes associated with increased immune activation and the HESN phenotype. In this review, we will describe some of the genetic variants associated with protection against HIV infection. Understanding the basis of HIV resistance in HESN is mandatory to develop new preventative and therapeutic interventions.