Project description:Background. Assessment of non-HLA variants alongside standard HLA testing was previously shown to improve the identification of potential coeliac disease (CD) patients. We intended to identify new genetic variants associated with CD in the Polish population that would improve CD risk prediction when used alongside HLA haplotype analysis. Results. Association analysis using four HLA-tagging SNPs showed that, as was found in other populations, positive predicting genotypes (HLA-DQ2.5/DQ2.5, HLA-DQ2.5/DQ2.2, and HLA-DQ2.5/DQ8) were found at higher frequencies in CD patients than in healthy control individuals in the Polish population. Both CD-associated SNPs discovered by GWAS were found in the CD susceptibility region, confirming the previously-determined association of the major histocompatibility (MHC) region with CD pathogenesis. The two most significant SNPs from the GWAS were rs9272346 (HLA-dependent; localized within 1 Kb of DQA1) and rs3130484 (HLA-independent; mapped to MSH5). Specificity of CD prediction using the four HLA-tagging SNPs achieved 92.9%, but sensitivity was only 45.5%. However, when a testing combination of the HLA-tagging SNPs and the MSH5 SNP was used, specificity decreased to 80%, and sensitivity increased to 74%.
Project description:The etiology of preeclampsia, a hypertensive disorder of human pregnancy, remains unknown. We addressed fetal sex selection and the suggestive role of fetal HLA-G and related genes, regulating maternal immune responses, in preeclampsia pathogenesis. We assessed birth sex ratios, weights, and seasonality of preeclampsia among 1.79 million births in Finland. We studied haplotypes of HLA-G 3’ untranslated region (UTR), regulating HLA-G expression, in 1000 Genomes series and in a preeclampsia cohort (n=1249). We quantified placental (n=163) mRNA expression of 136 genes, studied HLA-G and IFNα protein expression by immunohistochemistry, and measured maternal and fetal circulating IFNα levels by ELISA. Population-level data showed loss of male fetuses as a characteristic of preeclampsia. As a potential contributor to immune-mediated loss, we found balancing selection at HLA-G 3’UTR modulating sex ratio, and association of HLA-G 3’UTR haplotypes with placental HLA-G expression. HLA-G and its receptors were downregulated in preeclampsia placentas, and surprisingly, interferon alpha-1 (IFNA1) was highly upregulated. IFNA1 and HLA-G distinguished preeclampsia better than placental FLT1 expression. Fetal but not maternal circulating IFNα, produced by trophoblasts, showed association with maternal hypertension and fetal growth restriction. We uncover the link between placental HLA-G expression and human birth sex ratio. We propose that preeclampsia shares, through reduced HLA-G mediated immunotolerance, the mechanism needed to fight placental viral infections and malaria in evolution. IFNα upregulation in preeclampsia placenta, together with its known actions upstream of inflammatory genes, encourages testing IFNα inhibitors and especially the pregnancy-approved antimalarial hydroxichloroquine in treatment of preeclampsia.
Project description:Here we report binding index of 305 human HLA class I molecules from 18,771 unique haplotypes of 28,104 individuals to the 821 peptides experimentally observed from spike protein receptor-binding domain (RBD) of 5 main SARS-CoV-2 strains hydrolysed by human proteasomes with constitutive and immuno catalytic phenotypes. Our data read that 4 point mutations in the C-terminal RBD region 496-505 of Omicron B1.1.529 strain results in a dramatic increase of proteasome-mediated release of two public HLA class I epitopes covering 82% and 27% of world population haplotypes. Global population analysis of HLA class I haplotypes specific to these peptides demonstrated decreased mortality of human populations bearing these haplotypes to COVID-19 after but not before December, 2021, when Omicron spread over the world and became dominant SARS-CoV-2 strain. Analysis of population frequency of HLA class I alleles revealed that HLA-B*07:02, -B*08:01, -B*15:01, -C*01:02, -C*06:02 and -C*07:02 potentially provides increased resistance of human population to Omicron. Concluding, we found direct experimental observation, which might be one of the key factors that forced the SARS-CoV-2 virus to cross back the red line of pandemic status.
Project description:The clinical use of human pluripotent stem cells and their derivatives is limited by the rejection of transplanted cells due to differences in their HLA genes. This has led to the proposed use of histocompatible, patient-specific stem cells, however the preparation of many different stem cell lines for clinical use is a daunting task. Here we develop two distinct genetic engineering approaches that address this problem. First, we use a combination of gene targeting and mitotic recombination to derive HLA-homozygous embryonic stem cell (ESC) subclones from an HLA-heterozygous parental line. A small bank of HLA-homozygous stem cells with common haplotypes would match a significant proportion of the population. Second, we derive HLA class I-negative cells by targeted disruption of both alleles of the B2M gene in ESCs. Mixed leukocyte reactions and peptide-specific HLA-restricted CD8+ T cell responses were reduced in class I-negative cells that had undergone differentiation in embryoid bodies. These B2M-/- ESCs could act as universal donor cells in applications where the transplanted cells do not express HLA class II genes. Both approaches used adeno-associated virus (AAV) vectors for efficient gene targeting in the absence of potentially genotoxic nucleases, and produced pluripotent, transgene-free cell lines. Total RNA, 4 samples were analyzed as follows: 2 replicates for the hESC H1 wt ( rep1 and rep2) and 2 independent clones of hESC B2M knock-out
Project description:Rapid advances in high-throughput DNA sequencing technologies are accelerating the pace of research into personalized medicine. While methods for variant discovery and genotyping from whole genome sequencing (WGS) datasets have been well established, linking variants together into a single haplotype remains a challenge. An understanding of complete haplotypes of an individual will help clarify the consequences of inheriting multiple alleles in combination, identify novel disease associations, and augment studies of gene regulation. Although numerous methods have been developed to reconstruct haplotypes from WGS data, chromosome-span haplotypes at high resolution have been difficult to obtain. Here we present a novel method to accurately reconstruct chromosome-span haplotypes from proximity-ligation and DNA shotgun sequencing. We demonstrate the utility of this approach in producing high-resolution chromosome-span haplotype phasing in mouse and human. While proximity-ligation based methods were originally designed to investigate spatial organization of the genome, our results lend support for their use as a general tool for haplotyping in the future. Hi-C experiments in two replicates of Human GM12878 Lymphoblastoid cells and two replicates of F123 mouse ES cells (4 total samples)
Project description:Rapid advances in high-throughput DNA sequencing technologies are accelerating the pace of research into personalized medicine. While methods for variant discovery and genotyping from whole genome sequencing (WGS) datasets have been well established, linking variants together into a single haplotype remains a challenge. An understanding of complete haplotypes of an individual will help clarify the consequences of inheriting multiple alleles in combination, identify novel disease associations, and augment studies of gene regulation. Although numerous methods have been developed to reconstruct haplotypes from WGS data, chromosome-span haplotypes at high resolution have been difficult to obtain. Here we present a novel method to accurately reconstruct chromosome-span haplotypes from proximity-ligation and DNA shotgun sequencing. We demonstrate the utility of this approach in producing high-resolution chromosome-span haplotype phasing in mouse and human. While proximity-ligation based methods were originally designed to investigate spatial organization of the genome, our results lend support for their use as a general tool for haplotyping in the future.
Project description:The clinical use of human pluripotent stem cells and their derivatives is limited by the rejection of transplanted cells due to differences in their HLA genes. This has led to the proposed use of histocompatible, patient-specific stem cells, however the preparation of many different stem cell lines for clinical use is a daunting task. Here we develop two distinct genetic engineering approaches that address this problem. First, we use a combination of gene targeting and mitotic recombination to derive HLA-homozygous embryonic stem cell (ESC) subclones from an HLA-heterozygous parental line. A small bank of HLA-homozygous stem cells with common haplotypes would match a significant proportion of the population. Second, we derive HLA class I-negative cells by targeted disruption of both alleles of the B2M gene in ESCs. Mixed leukocyte reactions and peptide-specific HLA-restricted CD8+ T cell responses were reduced in class I-negative cells that had undergone differentiation in embryoid bodies. These B2M-/- ESCs could act as universal donor cells in applications where the transplanted cells do not express HLA class II genes. Both approaches used adeno-associated virus (AAV) vectors for efficient gene targeting in the absence of potentially genotoxic nucleases, and produced pluripotent, transgene-free cell lines.
Project description:Prediction of HLA epitopes is important for the development of cancer immunotherapies and vaccines. However, current prediction algorithms have limited predictive power, in part because they were not trained on high-quality epitope datasets covering a broad range of HLA alleles. To enable prediction of endogenous HLA class I-associated peptides across a large fraction of the human population, we used mass spectrometry to profile >185,000 peptides eluted from 95 HLA-A, -B, -C and -G mono-allelic cell lines. We identified canonical peptide motifs per HLA allele, unique and shared binding submotifs across alleles and distinct motifs associated with different peptide lengths. By integrating these data with transcript abundance and peptide processing, we developed HLAthena, providing allele-and-length-specific and pan-allele-pan-length prediction models for endogenous peptide presentation. These models predicted endogenous HLA class I-associated ligands with 1.5-fold improvement in positive predictive value compared with existing tools and correctly identified >75% of HLA-bound peptides that were observed experimentally in 11 patient-derived tumor cell lines.
Project description:To fully comprehend how genetic variants influence phenotypes, we must understand the functions of the epigenome. To assess the degree to which genetic variants influence epigenome activity, we integrate epigenetic and genotypic data from lupus patient lymphoblastoid cell lines to identify variants that induce allelic imbalance in the magnitude of histone post-translational modifications, referred to herein as histone quantitative trait loci (hQTLs). We demonstrate that enhancer hQTLs are enriched on autoimmune disease risk haplotypes and disproportionately influence gene expression variability compared with non-hQTL variants in strong linkage disequilibrium. We show that the epigenome regulates HLA class II genes differently in individuals who carry HLA-DR3 or HLA-DR15 haplotypes, resulting in differential 3D chromatin conformation and gene expression. Finally, we identify significant expression QTL (eQTL) x hQTL interactions that reveal substructure within eQTL gene expression, suggesting potential implications for functional genomic studies that leverage eQTL data for subject selection and stratification.