Search Results (6)

Major histocompatibility complex (MHC) genes are the most polymorphic in vertebrates and the high variability in many MHC genes is thought to play a crucial role in pathogen recognition. The MHC class II locus DQA polymorphism was analyzed in the endangered Przewalski’s horse, Equus przewalskii, a species that has been extinct in the wild and all the current living individuals descend from 12 founders. We used the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) to detect the polymorphism within the MHC DQA in 31 Przewalski’s horses from two reintroduced populations. Consequently, only seven alleles were identified, with only four presenting in each population. In comparison with other mammals, the Przewalski’s horse demonstrated less MHC variation. The nucleotide genetic distance of the seven ELA-DQA alleles was between 0.012 and 0.161. The Poisson corrected amino acid genetic distance of the founded alleles was 0.01–0.334. The allele and genotype frequencies of both reintroduced populations of Przewalski’s horse deviated from the Hardy–Weinberg equilibrium. Specific MHC DQA alleles may have been lost during the extreme bottleneck event that this species underwent throughout history. We suggest the necessity to detect the genetic background of individuals prior to performing the reintroduction project. Full article

Background: This study was designed to investigate the effect of cluster differentiation (CD)39 and CD73 inhibitors on the expresion of tumour-associated macrophages (TAMs), M1- versus M2-tumour phenotypes in mice with colon cancer. Methods: An in vivo study of co-culture with colon cancer cells and immune cells from the bone marrow (BM) of mice was performed. After the confirmation of the effect of polyoxotungstate (POM-1) as an inhibitor of CD39 on TAMs, the mice were randomly divided into a control group without POM-1 and a study group with POM-1, respectively, after subcutaneous injection of CT26 cells. On day 14 after the injection, the mice were sacrificed, and TAMs were evaluated using fluorescence-activated cell sorting. Results: In the in vivo study, the co-culture with POM-1 significantly increased the apoptosis of CT26 cells. The cell population from the co-culture with POM-1 showed significant increases in the expression of CD11b⁺ for myeloid cells, lymphocyte antigen 6 complex, locus C (Ly6C⁺) for monocytes, M1-tumour phenotypes from TAMs, and F4/80⁺ for macrophages. In the in vivo study, tumour growth in the study group with POM-1 was significantly limited, compared with the control group without POM-1. The expressions of Ly6C⁺ and major histocompatibility complex class II⁺ for M1-tumour phenotypes from TAMs on F4/80⁺ from the tumour tissue in the study group had significantly higher values compared with the control group. Conclusion: The inhibition of CD39 with POM-1 prevented the growth of colon cancer in mice, and it was associated with the increased expression of M1-tumour phenotypes from TAMs in the cancer tissue. Full article

Genetic analyses of human type 1 diabetes (T1D) have yet to reveal a complete pathophysiologic mechanism. Inbred rats with a high-risk class II major histocompatibility complex (MHC) haplotype (RT1B/D^u) can illuminate such mechanisms. Using T1D-susceptible LEW.1WR1 rats that express RT1B/D^u and a susceptible allele of the Ubd promoter, we demonstrate that germline knockout of Tcrb-V13S1A1, which encodes the Vβ13a T cell receptor β chain, completely prevents diabetes. Using the RT1B/D^u-identical LEW.1W rat, which does not develop T1D despite also having the same Tcrb-V13S1A1 β chain gene but a different allele at the Ubd locus, we show that knockout of the Ubash3a regulatory gene renders these resistant rats relatively susceptible to diabetes. In silico structural modeling of the susceptible allele of the Vβ13a TCR and its class II RT1^u ligand suggests a mechanism by which a germline TCR β chain gene could promote susceptibility to T1D in the absence of downstream immunoregulation like that provided by UBASH3A. Together these data demonstrate the critical contribution of the Vβ13a TCR to the autoimmune synapse in T1D and the regulation of the response by UBASH3A. These experiments dissect the mechanisms by which MHC class II heterodimers, TCR and regulatory element interact to induce autoimmunity. Full article

Genes of the major histocompatibility complex (MHC) code for cell surface proteins essential for adaptive immunity. They show the most outstanding genetic diversity in vertebrates, which has been connected with various fitness traits and thus with the long-term persistence of populations. In this study, polymorphism of the MHC class II DRB locus was investigated in chamois with Single-Strand Conformation Polymorphism (SSCP)/Sanger genotyping and Ion Torrent S5 next-generation sequencing (NGS). From eight identified DRB variants in 28 individuals, five had already been described, and three were new, undescribed alleles. With conventional SSCP/Sanger sequencing, we were able to detect seven alleles, all of which were also detected with NGS. We found inconsistencies in the individual genotypes between the two methods, which were mainly caused by allelic dropout in the SSCP/Sanger method. Six out of 28 individuals were falsely classified as homozygous with SSCP/Sanger analysis. Overall, 25% of the individuals were identified as genotyping discrepancies between the two methods. Our results show that NGS technologies are better performing in sequencing highly variable regions such as the MHC, and they also have a higher detection capacity, thus allowing a more accurate description of the genetic composition, which is crucial for evolutionary and population genetic studies. Full article

Genome-wide association studies of schizophrenia encompassing the major histocompatibility locus (MHC) were highly significant following genome-wide correction. This broad region implicates many genes including the MHC complex class II. Within this interval we examined the expression of two MHC II genes (HLA-DPA1 and HLA-DRB1) in brain from individual subjects with schizophrenia (SZ), bipolar disorder (BD), major depressive disorder (MDD), and controls by differential gene expression methods. A third MHC II mRNA, CD74, was studied outside of the MHC II locus, as it interacts within the same immune complex. Exon microarrays were performed in anterior cingulate cortex (ACC) in BD compared to controls, and both HLA-DPA1 and CD74 were decreased in expression in BD. The expression of HLA-DPA1 and CD74 were both reduced in hippocampus, amygdala, and dorsolateral prefrontal cortex regions in SZ and BD compared to controls by specific qPCR assay. We found several novel HLA-DPA1 mRNA variants spanning HLA-DPA1 exons 2-3-4 as suggested by exon microarrays. The intronic rs9277341 SNP was a significant cis expression quantitative trait locus (eQTL) that was associated with the total expression of HLA-DPA1 in five brain regions. A biomarker study of MHC II mRNAs was conducted in SZ, BD, MDD, and control lymphoblastic cell lines (LCL) by qPCR assay of 87 subjects. There was significantly decreased expression of HLA-DPA1 and CD74 in BD, and trends for reductions in SZ in LCLs. The discovery of multiple splicing variants in brain for HLA-DPA1 is important as the HLA-DPA1 gene is highly conserved, there are no reported splicing variants, and the functions in brain are unknown. Future work on the function and localization of MHC Class II proteins in brain will help to understand the role of alterations in neuropsychiatric disorders. The HLA-DPA1 eQTL is located within a large linkage disequilibrium block that has an irrefutable association with schizophrenia. Future tests in a larger cohort are needed to determine the significance of this eQTL association with schizophrenia. Our findings support the long-held hypothesis that alterations in immune function are associated with the pathophysiology of psychiatric disorders. Full article

Members of major histocompatibility complex (MHC) family are important in immune systems. Great efforts have been made to reveal their complicated gene structures. But many existing studies focus on partial sequences of MHC genes. In this study, by gene cloning and sequencing, we identified cDNA sequences and DNA sequences of the MHC class II B in two flatfishes, stone flounder (Kareius bicoloratus) and homozygous diploid Japanese flounder (Paralichthys olivaceus). Eleven cDNA sequences were acquired from eight stone flounder individuals, and most of the polymorphic sites distributed in exons 2 and 3. Twenty-eight alleles were identified from the DNA fragments in these eight individuals. It could be deduced from their Bayesian inference phylogenetic tree that at least four loci of MHC class II B exist in stone flounder. The detailed whole-length DNA sequences in one individual were analyzed, revealing that the intron length varied among different loci. Four different cDNA sequences were identified from one homozygous diploid Japanese flounder individual, implying the existence of at least four loci. Comparison of the cDNA sequences to the DNA sequence confirmed that six exons existed in this gene of Japanese flounder, which was a common feature shared by Pleuronectiformes fishes. Our results proved the multi-locus feature of MHC class II B. The sequences we obtained would provide detailed and systematic data for further research. Full article