Adaptive Admixture of HLA Class I Allotypes Enhanced Genetically Determined Strength of Natural Killer Cells in East Asians

Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.     

Targeted therapy and immunotherapy: Emerging biomarkers in metastatic melanoma

Targeted therapy directed against oncogenic BRAF mutations and immune checkpoint inhibitors have transformed melanoma therapy over the past decade and prominently improved patient outcomes. However, not all patients will respond to targeted therapy or immunotherapy and many relapse after initially responding to treatment. This unmet need presents two major challenges. First, can we elucidate novel oncogenic drivers to provide new therapeutic targets? Second, can we identify patients who are most likely to respond to current therapeutic strategies in order to both more accurately select populations and avoid undue drug exposure in patients unlikely to respond? In an effort to evaluate the current state of the field with respect to these questions, we provide an overview of some common oncogenic mutations in patients with metastatic melanoma and ongoing efforts to therapeutically target these populations, as well as a discussion of biomarkers for response to immune checkpoint inhibitors—including tumor programmed death ligand 1 expression and the future use of neoantigens as a means of truly personalized therapy. This information is becoming important in treatment decision making and provides the framework for a treatment algorithm based on the current landscape in metastatic melanoma.     

Distribution of HLA class Ⅰ and class Ⅱ haplotypes in Chinese Han population based on family segregation

HLA haplotype analysis has important application value in human population genetics, anthropological research and HLA matching transplantation. Based on HLA-A, -B, -C, -DRB1 and -DQB1 genotyping data from 663 families including 663 leukemia patients and 991 related donors, the allele frequency (AF) and haplotype frequency (HF) of two-, three- and five-locus haplotype distribution patterns in the Chinese Han population were determined by family segregation. A total of 38 alleles at A locus, 75 alleles at B locus, 35 alleles at C locus, 53 alleles at DRB1 locus and 22 alleles at DQB1 locus were discovered in this population. The frequencies of these alleles were basically consistent with those of previous reports except for some tiny differences. The study found 11 A-C, 15 C-B, 4 B-DRB1 and 11 DRB1-DQB1 two-locus haplotypes with a frequency over 2%. The number of A-C-B and A-B-DRB1 three-locus haplotype with a frequency over 1% were 11 and 3 respectively. The most common HLA-A-C-B-DRB1-DQB1 haplotype (HF>1%) were A*3001-C*0602-B*1302-DR*0701-DQ*0202 (4.30%), A*0207-C*0102-B*4601-DR*0901-DQ*0303 (3.07%), A*3303-C*0302-B*5801-DR*0301-DQ*0201 (1.49%) and A*1101-C*0102-B*4601-DR*0901-DQ*0303 (1.01%). The results are helpful for finding matching donors for hematopoietic stem cell transplant patients and also contribute to transplant immunology, HLA-related diseases, research of human genetics and other fields.     

HLA-A, -B, -C, -DRB1 and -DQB1 alleles associated with different hematological diseases in Chinese population

The purpose of this study was to explore the association between human leukocyte antigens (HLA)-A, -B, -C, -DRB1 and -DQB1 allele polymorphisms and different hematological diseases in Chinese groups. Retrospective analyses of HLA genotyping data in high-resolution for patients with acute myeloid leukemia (AML, 766 cases), chronic myeloid leukemia (CML, 330 cases), acute lymphoblastic leukemia (ALL, 605 cases), aplastic anemia (AA, 229 cases), myelodysplastic syndrome (MDS, 204 cases) were performed, and the susceptible or protective HLA alleles of the above-mentioned diseases were analyzed by Chi-square test and Fisher exact test with unrelated hematopoietic stem cell donors as control. The Results indicated that A*0201, B*4402, C*0701, DRB1*1201, DRB1*1401, and DQB1*0602 might be susceptible genes of AML, while A*1101, A*3303, B*5801, C*0302, DRB1*0301, DQB1*0201 and DQB1*0502 might be protective genes of AML. A*3303 might be a protective gene of CML, and DRB1*1401 might be a susceptible gene of CML. ALL's susceptible genes included A*0201, A*0210, B*5201, DRB1*1201, DRB1*1401 and DQB1*0602, but its protective genes included DQB1*0502. For AA, A*0201, A*0206, B*1511, DRB1*0901, DRB1*1401, DQB1*0303, DQB1*0602 might be susceptible genes, while A*3303, B*5801, C*0302, DRB1*1602 and DQB1*0502 might be protective genes. A*0201, A*0206, B*1511, DRB1*0901, DRB1*1401, DQB1*0303. A*0201, B*1558, B*4801, B*5201, DRB1*1401, DRB1*1501, and DQB1*0602 might be susceptible genes of MDS, and A*3303, B*4601, B*5801, C*0302, and DRB1*0901 might be protective genes of MDS. On the basis of HLA high-resolution genotyping for the first time, this study comprehensively analyzed HLA alleles associated with different hematological diseases in the Chinese population, which should provide clues for further study on the pathogenesis of these diseases.     

HLA class II SNP interactions and the association with type 1 diabetes mellitus in Bengali speaking patients of Eastern India

Background

Several studies have demonstrated a fundamental role for the HLA in the susceptibility of, or protection to, type 1 diabetes mellitus (T1DM). However, this has not been adequately studied in Asian Indian populations. To assess the frequency of HLA class II (DPA1, DPB1, DQA1, DQB1 and DRB1) associated to susceptibility or protection toT1DM in a Bengali population of India with diabetes.

Results

Single nucleotide polymorphism study. The HLA genotyping was performed by a polymerase chain reaction followed by their HLA-DP, DQ, and DRB1 genotypes and haplotypes by sequencing method. The results are studied by Plink software. The χ² tests were used for the inferential statistics. To our knowledge, this study is the first of a kind which has attempted to check the HLA association with T1DM by SNPs analysis. The study recruited 151 patients with T1DM and same number of ethno-linguistic, sex matched non-diabetic controls. The present study found a significant SNP rs7990 of HLA-DQA1 (p = 0.009) negative correlation, again indicating that risk from HLA is considerably more with T1DM.

Conclusions

This study demonstrates that the HLA class-II alleles play a major role in genetic basis of T1DM.     

Rapid methods of detecting the target molecule in immunohistology using a bioluminescence probe

We demonstrate a novel rapid direct detection method for immunohistochemistry, using a bioluminescent probe. An anti‐CEA antibody‐fused far‐red bioluminescent protein can monitor the accumulation of this type of probe in tumour tissues. The bimodal spectrum (λ_max = 460 and 675 nm) of this bioluminescent probe is extremely stable under different conditions of pH and ion concentration. The sensitivity of our bioluminescent labelling was at the same level of enzymatic labelling, e.g. peroxidase, as an indirect system. Our novel technique is simple and can shorten the pretreatment time of paraffin sections to around 30 min. The utility of our bioluminescent labelling covers all imaging in vitro, in vivo and ex vivo, suggesting that our antibody‐fused bioluminescent probe has the potential to detect tumour antigens with a high sensitivity in routine immune histological examinations. Copyright © 2012 John Wiley & Sons, Ltd.     

A convenient synthesis of GDP-d-rhamnose: The donor substrate for d-rhamnosyltransferase WbpZ from Pseudomonas aeruginosa PAO1

Gram negative bacteria have lipopolysaccharides (LPS) that are critical for their survival. LPS molecules are composed of antigenic exopolysaccharide chains (O antigens). We are interested in discovering the enzymes involved in the biosynthesis of O antigens in Pseudomonas aeruginosa. The common polysaccharide antigen contains α-linked d-rhamnose residues. We have now synthesized GDP-d-rhamnose by a convenient synthesis in aqueous solution, and have shown that it can be used without extensive purification as the donor substrate for d-rhamnosyltransferase (WbpZ) from the P. aeruginosa strain PAO1. The availability of this nucleotide sugar preparation allows for characterization of d-rhamnosyltransferases.     

Identifying molecularly defined antigens for a Histoplasma capsulatum-specific interferon gamma release assay

BackgroundIn a previous work we showed the feasibility of an interferon gamma release assay (IGRA) for detecting latent infection by Histoplasma capsulatum. While in that proof-of-concept study we used crude fungal extracts as antigens, the newest IGRAs developed for other infections are based on molecularly defined antigens, mostly on mixtures of immunogenic peptides.AimsTo identify proteins in H. capsulatum that might serve as molecularly defined antigens for an IGRA test.MethodsWe surveyed the literature looking for known H. capsulatum-immunogenic proteins and assayed two of them as antigens in an IGRA test, in a study that involved 80 volunteers. Furthermore, we used several bioinformatics tools to identify specific H. capsulatum proteins and to analyze possible strategies for the design of H. capsulatum-specific immunogenic peptides.ResultsSeven H. capsulatum-immunogenic proteins were retrieved from the literature. IGRA tests using either the heat shock protein 60 or the M antigen showed high sensitivities but low specificities, most likely due to the high sequence similarity with the corresponding orthologs in other pathogenic microorganisms. We identified around 2000 H. capsulatum-specific proteins, most of which remain unannotated. Class II T-cell epitope predictions for a small number of these proteins showed a great variability among different alleles, prompting for a “brute force” approach for peptide design.ConclusionsThe H. capsulatum genome encodes a large number of distinctive proteins, which represent a valuable source of potential specific antigens for an IGRA test. Among them, the Cfp4 protein stands out as a very attractive candidate.     

Invariant chain modulates HLA class II protein recycling and peptide presentation in nonprofessional antigen presenting cells

The expression of MHC class II molecules and the invariant chain (Ii) chaperone, is coordinately regulated in professional antigen presenting cells (APC). Ii facilitates class II subunit folding as well as transit and retention in mature endosomal compartments rich in antigenic peptides in these APC. Yet, in nonprofessional APC such as tumors, fibroblasts and endocrine tissues, the expression of class II subunits and Ii may be uncoupled. Studies of nonprofessional APC indicate class II molecules access antigenic peptides by distinct, but poorly defined pathways in the absence of Ii. Here, investigations demonstrate that nonprofessional APC such as human fibroblasts lacking Ii internalize antigenic peptides prior to the binding of these ligands to recycling class II molecules. By contrast, fibroblast lines expressing Ii favor exogenous peptides binding directly to cell surface class II molecules without a need for ligand internalization. Endocytosis of class II molecules was enhanced in cells lacking Ii compared with Ii-expressing APC. These results suggest enhanced reliance on the endocytic recycling pathway for functional class II presentation in nonprofessional APC.