Role of HLA-G and other immune mechanisms in pregnancy

Variations in killer-cell immunoglobulin-like receptor and human leukocyte antigen genes and immunity to malaria

Malaria is one of the deadliest infectious diseases in the world. Immune responses to Plasmodium falciparum malaria vary among individuals and between populations. Human genetic variation in immune system genes is likely to play a role in this heterogeneity. Natural killer (NK) cells produce inflammatory cytokines in response to malaria infection, kill intraerythrocytic Plasmodium falciparum parasites by cytolysis, and participate in the initiation and development of adaptive immune responses to plasmodial infection. These functions are modulated by interactions between killer-cell immunoglobulin-like receptors (KIRs) and human leukocyte antigens (HLAs). Therefore, variations in KIR and HLA genes can have a direct impact on NK cell functions. Understanding the role of KIRs and HLAs in immunity to malaria can help to better characterize antimalarial immune responses. In this review, we summarize the different KIRs and HLAs associated with immunity to malaria thus far.

HLA-G Polymorphisms Associated with HIV Infection and Preeclampsia in South Africans of African Ancestry

OBJECTIVES

HLA-G, part of the major histocompatibility complex (MHC), is associated with the risk of developing preeclampsia (PE). In this study, we determined the contribution of specific HLA-G polymorphisms on the risk of developing preeclampsia in HIV-infected and uninfected South Africans of African ancestry.

METHODS

One hundred and ninety-three women of African ancestry were enrolled (74 HIV-uninfected normotensive, 60 HIV-infected normotensive, 34 HIV-uninfected, and 25 HIV-infected preeclamptics). Sanger sequencing of the untranslated region was performed to genotype six SNPs, i.e., 14 bp Ins/Del of rs66554220, rs1710, rs1063320, rs1610696, rs9380142, and rs1707).

RESULTS

For rs66554220, we have the following results: (a) based on pregnancy type-the Ins/Ins and Del/Ins genotype frequency was higher in preeclampsia (PE) compared to normotensive pregnancies (Ins/Ins vs. Del/Ins, P = 0.02∗: OR (95%CI) = 13.44 (0.7222-249.9); Del/Del vs. Del/Ins, P = 0.03∗: OR (95%CI) = 2.95 (1.10-7.920)); (b) based on HIV status-the Ins/Ins showed both genotypic and allelic association with HIV infection. HIV-infected PE has higher Ins/Ins genotypic and allelic frequencies compared to HIV-uninfected PE (Ins/Ins vs. Del/Ins, P = 0.005∗∗: OR (95%CI) = 21.32 (1.71-4.17); Ins, P = 0.005∗∗; OR (95%IC) = 21.32 (1.71-4.17)). For rs1707, we have the following results: (a) based on pregnancy type-there were CT genotypic frequencies in PE, more especially LOPE compared to normotensive pregnancies (TT vs. CT, P = 0.0092∗∗: OR (95%CI) = 5.(1.39 - 25.64)), and no allelic association was noted; (b) based on HIV status-CT was higher in HIV-infected LOPE compared to uninfected LOPE (TT vs. TC, P = 0.0006∗∗∗: OR (95%CI) = 40.00 (2.89 - 555.1)). For rs1710 and rs1063320, no significant differences in the genotype and allele frequencies were noted based on pregnancy type and HIV status. For rs9380142, we have the following results: (a) based on pregnancy type-no significant differences were noted between normotensive compared to PE pregnancies; (b) based on HIV status-AA genotypes occurred more in the HIV-infected PE group (AA vs. GG, P = 0.02∗: OR (95%CI) = 13.97 (0.73 - 269.4)), while A allelic frequency occurred more in HIV-infected PE, especially LOPE compared to uninfected groups (A vs. G, P = 0.0003∗∗∗: OR (95%CI) = 10.72 (2.380 - 48.32); P = 0.02∗: OR (95%CI) = 9.00 (1.07 - 75.74)). For rs1610696, we have the following results: (a) based on pregnancy type-genotypic and allelic frequencies of CC were higher in PE compared to normotensive pregnancies (CC vs. GG, P = 0.0003∗∗∗: OR (95%CI) = 31.87 (1.861 - 545.9); C, P = 0.0001∗∗∗: OR (95%IC) = 21.91 (2.84 - 169.0)); (b) based on HIV status-GG frequencies were higher in the HIV-infected PE more especially LOPE groups (GG vs. GC, P = 0.02∗: OR (95%CI) = 16.87 (0.81 - 352.1); GG vs. CC, P = 0.0001∗∗∗: OR (95%CI) = 159.5 (13.10 - 1942)).

CONCLUSION

Selected HLA-G 14 bp polymorphisms (Ins/Ins) and genotypic and allelic differences in rs9380142, rs1610696, and rs1707 are associated with the pathogenesis of preeclampsia in HIV-infected South African women of African ancestry. More genetic studies evaluating the association between preeclampsia and HIV infection are needed to improve diagnosis and antenatal care.

From animal models to patients: the role of placental microRNAs, miR-210, miR-126, and miR-148a/152 in preeclampsia

Placental microRNAs (miRNAs) regulate the placental transcriptome and play a pathological role in preeclampsia (PE), a hypertensive disorder of pregnancy. Three PE rodent model studies explored the role of placental miRNAs, miR-210, miR-126, and miR-148/152 respectively, by examining expression of the miRNAs, their inducers, and potential gene targets. This review evaluates the role of miR-210, miR-126, and miR-148/152 in PE by comparing findings from the three rodent model studies with in vitro studies, other animal models, and preeclamptic patients to provide comprehensive insight into genetic components and pathological processes in the placenta contributing to PE. The majority of studies demonstrate miR-210 is upregulated in PE in part driven by HIF-1α and NF-κBp50, stimulated by hypoxia and/or immune-mediated processes. Elevated miR-210 may contribute to PE via inhibiting anti-inflammatory Th2-cytokines. Studies report an up- and downregulation of miR-126, arguably reflecting differences in expression between cell types and its multifunctional capacity. MiR-126 may play a pro-angiogenic role by mediating the PI3K-Akt pathway. Most studies report miR-148/152 family members are upregulated in PE. Evidence suggests they may inhibit DNA methylation of genes involved in metabolic and inflammatory pathways. Given the genetic heterogeneity of PE, it is unlikely that a single placental miRNA is a suitable therapeutic target for all patients. Investigating miRNAs in PE subtypes in patients and animal models may represent a more appropriate approach going forward. Developing methods for targeting placental miRNAs and specific placental cell types remains crucial for research seeking to target placental miRNAs as a novel treatment for PE.