Major Histocompatibility Complex Type Research Articles

Possible Shifts in the Genetic Diversity of Red-crowned Cranes (Grus japonensis) in Hokkaido, Japan: Indications of Continental Gene Flow.

Red-crowned cranes (Grus japonensis) consist of two distinct groups: the continental population and the island population. The island population, localized in Hokkaido, Japan, exhibits very low genetic diversity due to its rapid recovery from the brink of extinction. Our previous research in 2018 highlighted a possible mating between a male from the continental population, with the Gj5 haplotype, and a female from the island population, with the Gj2 haplotype, at Hitominuma Sawmp shore in northern Hokkaido. The present study attempted to unravel the distribution of their offspring by examining the major histocompatibility complex (MHC) of this mixed breeding pair compared with samples collected from cranes in northern and southeastern Hokkaido between 2008 and 2022. The analysis identified 55 MHC types, including 10 known types in a dataset of 89 crane samples, based on amino acid sequences. A total of 58 MHC types were recognized, based on nucleotide sequences, as there were many cases in which the same amino acid sequence had different nucleotide sequences. The five DNA types of MHC in the Hitominuma Swamp male were predominantly identified in eight cranes from northern Hokkaido and one chick from southeastern Hokkaido. In addition, population genetic analysis, based on insertion/deletion (InDel) polymorphisms, indicates distinct population differentiation between the northern and southeastern regions of Hokkaido. These results suggest that genetic contributions from the continental red-crowned crane population have already been integrated into the Hokkaido populations, with a more pronounced influence in northern Hokkaido.

Saponin Esculeoside A and Aglycon Esculeogenin A from Ripe Tomatoes Inhibit Dendritic Cell Function by Attenuation of Toll-like Receptor 4 Signaling.

Dendritic cells (DCs) can initiate immune response through the presenting antigens to naïve T lymphocytes. Esculeoside A (EsA), a spirosolane glycoside, is reported as a major component in the ripe fruit of tomato. Little is known about the effect of tomato saponin on mice bone marrow-derived DCs. This study revealed that EsA and its aglycon, esculeogenin A (Esg-A), attenuated the phenotypic and functional maturation of murine DCs stimulated by lipopolysaccharide (LPS). We found that EsA/Esg-A down-regulated the expression of major histocompatibility complex type II molecules and costimulatory molecule CD86 after LPS stimulation. It was also determined that EsA-/Esg-A-treated DCs were poor stimulators of allogeneic T-cell proliferation and exhibited impaired interleukin-12 and TNF-α production. Additionally, EsA/Esg-A was able to inhibit TLR4-related and p-NFκB signaling pathways. This study shows new insights into the immunopharmacology of EsA/Esg-A, and represents a novel approach to controlling DCs for therapeutic application.

Limited Effects of Class II Transactivator-Based Immunotherapy in Murine and Human Glioblastoma.

The major histocompatibility complex type II is downregulated in glioblastoma (GB) due to the silencing of the major transcriptional regulator class II transactivator (CIITA). We investigated the pro-immunogenic potential of CIITA overexpression in mouse and human GB. The intracerebral growth of wildtype GL261-WT cells was assessed following contralateral injection of GL261-CIITA cells or flank injections with GL261-WT or GL261-CIITA cells. Splenocytes obtained from mice implanted intracerebrally with GL261-WT, GL261-CIITA cells or phosphate buffered saline (PBS) were transferred to other mice and subsequently implanted intracerebrally with GL261-WT. Human GB cells and (syngeneic) GB-infiltrating immune cells were isolated from surgical samples and co-cultured with GB cells expressing CIITA or not, followed by RT-qPCR assessment of the expression of key immune regulators. Intracerebral vaccination of GL261-CIITA significantly reduced the subsequent growth of GL261-WT cells implanted contralaterally. Vaccination with GL261-WT or -CIITA subcutaneously, however, equivalently retarded the intracerebral growth of GL261 cells. Adoptive cell transfer experiments showed a similar antitumor potential of lymphocytes harvested from mice implanted intracerebrally with GL261-WT or -CIITA. Human GB-infiltrating myeloid cells and lymphocytes were not activated when cultured with CIITA-expressing GB cells. Tumor-infiltrating NK cells remained mostly inactivated when in co-culture with GB cells, regardless of CIITA. these results question the therapeutic potential of CIITA-mediated immunotherapy in glioblastoma.

MRNAs encoding self-DNA reactive cGAS enhance the immunogenicity of lipid nanoparticle vaccines.

Nucleic acid-based vaccines hold promise in preventing infections and treating cancer. The most common use of this technology is to encode antigenic proteins on mRNAs that are delivered to cells via lipid nanoparticle (LNP) formulations. In this study, we discovered that immunostimulatory proteins can also be encoded on mRNAs in LNPs. We found that an active mutant of the enzyme cGAS, referred to as cGAS∆N, acts as a catalytic adjuvant in LNP-encapsulated mRNA vaccines. The delivery of cGAS∆N mRNA via LNPs in combination with antigen mRNA-LNPs led to durable antigen-specific IFNγ-producing T cells that exceeded the efficiency of antigen-LNPs similar to those currently used in the clinic. This strategy did not compromise B cell responses; rather it induced Th1-biased antibody isotypes. This work unveils new vaccine design strategies using mRNA-encoded catalytic adjuvants that could be ideal for generating CD8+ T cell and B cell responses for immunotherapies.

Elucidation of binding mechanism, affinity, and complex structure between mWT1 tumor-associated antigen peptide and HLA-A*24:02.

We have applied our advanced computational and experimental methodologies to investigate the complex structure and binding mechanism of a modified Wilms' Tumor 1 (mWT1) protein epitope to the understudied Asian-dominant allele HLA-A*24:02 (HLA-A24) in aqueous solution. We have applied our developed multicanonical molecular dynamics (McMD)-based dynamic docking method to analyze the binding pathway and mechanism, which we verified by comparing the highest probability structures from simulation with our experimentally solved x-ray crystal structure. Subsequent path sampling MD simulations elucidated the atomic details of the binding process and indicated that first an encounter complex is formed between the N-terminal's positive charge of the 9-residue mWT1 fragment peptide and a cluster of negative residues on the surface of HLA-A24, with the major histocompatibility complex (MHC) molecule preferring a predominantly closed conformation. The peptide first binds to this closed MHC conformation, forming an encounter complex, after which the binding site opens due to increased entropy of the binding site, allowing the peptide to bind to form the native complex structure. Further sequence and structure analyses also suggest that although the peptide loading complex would help with stabilizing the MHC molecule, the binding depends in a large part on the intrinsic affinity between the MHC molecule and the antigen peptide. Finally, our computational tools and analyses can be of great benefit to study the binding mechanism of different MHC types to their antigens, where it could also be useful in the development of higher affinity variant peptides and for personalized medicine.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Background: A growing body of evidence has indicated impaired function or compositional changes of monocytes in inflammatory disorders, such as acute respiratory syndrome and covid-19. In myeloma tumor microenvironment, activation of type I interferon pathway and dysregulated expression of major histocompatibility complex type II genes are observed in classical monocytes, which result in loss of antigen presentation of monocytes. The proportions of BAFF+PD-L1+ monocytes in the bone marrow also correlate with survival of myeloma patients following chimeric antigen-receptor T cell therapy. Nevertheless, the mechanisms underlying PB and BM monocytes defects in myeloma remain poorly addressed, at least in part by the lack of large scale scRNA-seq studies. To resolve the heterogeneous bone marrow and peripheral blood monocyte subpopulations and their transcriptional factors between healthy donors and multiple myeloma patients. Methods: We conducted scRNA-seq on monocytes of 7 newly diagnosed myeloma patients and 12 healthy donors. Specifically, 3 and 5 bone marrow aspirates and 9 and 7 peripheral blood samples of 12 healthy controls and 7 newly diagnosed patients were obtained, respectively. Results: Heterogeneous bone marrow and peripheral blood monocyte subpopulations and their transcriptional factors were resolved. The function characteristics of monocyte were compared between MM patients and healthy donors, which indicated a stress signature induced by multiple myeloma. Furthermore, we identified two monocyte differentiation pathways, and discovered that bone marrow monocyte feature type I IFN-associated differentiation dysregulation in patients with MM as well as dysregulated patterns at transcriptome. Finally, we included 10 MM patients as a validation cohort, by tracking the stress signature over time in those patients undergoing first-line treatment, we founded that the stress signature was partially overcome by antitumor therapy. Conclusion: Our results provided further insight into transcriptional and differentiation changes occurring in the bone marrow and peripheral blood monocytes from patients with multiple myeloma and hint and mechanisms of immune evasion. Encore Abstract - previously submitted to EHA 2023 The research was funded by: This investigation was supported by the International Cooperation Projects of National Natural Science Foundation (grants 81920108006), CAMS Innovation Fund for Medical Sciences (CIFMS) (grants 2022-I2M-1-022), the National Natural Science Foundation (grants 81630007; grants 82270218, 81670202; grants 81900214), and the Atlas of Blood Cell Alliance. Keywords: genomics, epigenomics, and other -omics, microenvironment, multiple myeloma No conflicts of interests pertinent to the abstract.

The expression and prognostic value of transporter 1, ATP binding cassette subfamily B member in clear cell renal cell cancer with experimental validation.

Transporter associated with antigen processing 1(TAP1) serves as a protein to transport antigenic peptides from the surface of the endoplasmic reticulum to the lumen of the endoplasmic reticulum when the antigens are presented by major histocompatibility complex type I (MHC-I), which has been identified to play a critical role in antigen presentation in innate immunity. In tumors, the role of TAP1 seems to remain controversial. On the one hand, given the role of TAP1 in antigen presentation, it is indicated that high TAP1 expression corresponds to the emergence of more neoantigens epitopes that facilitate the recognition for phagocytes, T cells and other cells. On the other hand, the genetic ablation of transporter associated with antigen processing (TAP) results in the presentation of new class I-restricted epitopes encoded in house-keeping products. Opposite result has been revealed by studies in other tumors suggest, which implies a more complex function of TAP1. Therefore, it's significant to clarify the role of TAP1 in clear cell renal cell carcinoma (ccRCC). In this study, we found the elevated expression levels in mRNA and protein of TAP1 in ccRCC tissues, which indicated a relatively worse prognosis. Transwell assay and Scratch assay in vitro demonstrated the promotive role of TAP1 in ccRCC migration as well as a significant role in metastasis. And the increased expression of TAP1 resulted in more immune cells infiltrated in cancer tissues. TAP1 was also demonstrated to be related to immune regulator genes, as gene set enrichment analysis (GSEA) indicated its significant role in immune regulation. The results of CancerSEA indicated the positive association of the high-level TAP1 expression with epithelial-mesenchymal transition (EMT) and the inverse association with Cell Cycle. The effective drugs were also predicted based on TAP1 expression, of which the high level was indeed associated with resistance to multiple drugs, but some effective drugs still identified based on high TAP1 expression. According to the analysis of various databases, the role of TAP1 in ccRCC was explored, especially in relationship of TAP1 with tumor microenvironment. These results indicate that TAP1 can serve as a potential target for treatment of ccRCC.

Periosteum and fascia lata: Are they so different?

Introduction: The human fascia lata (HFL) is used widely in reconstructive surgery in indications other than fracture repair. The goal of this study was to compare microscopic, molecular, and mechanical properties of HFL and periosteum (HP) from a bone tissue engineering perspective. Material and Methods: Cadaveric HP and HFL (N = 4 each) microscopic morphology was characterized using histology and immunohistochemistry (IHC), and the extracellular matrix (ECM) ultrastructure assessed by means of scanning electron microscopy (SEM). DNA, collagen, elastin, glycosaminoglycans, major histocompatibility complex Type 1, and bone morphogenetic protein (BMP) contents were quantified. HP (N = 6) and HFL (N = 11) were submitted to stretch tests. Results: Histology and IHC highlighted similarities (Type I collagen fibers and two-layer organization) but also differences (fiber thickness and compaction and cell type) between both tissues, as confirmed using SEM. The collagen content was statistically higher in HFL than HP (735 vs. 160.2μg/mg dry weight, respectively, p < 0.0001). On the contrary, DNA content was lower in HFL than HP (404.75 vs. 1,102.2μg/mg dry weight, respectively, p = 0.0032), as was the immunogenic potential (p = 0.0033). BMP-2 and BMP-7 contents did not differ between both tissues (p = 0.132 and p = 0.699, respectively). HFL supported a significantly higher tension stress than HP. Conclusion: HP and HFL display morphological differences, despite their similar molecular ECM components. The stronger stretching resistance of HFL can specifically be explained by its higher collagen content. However, HFL contains many fewer cells and is less immunogenic than HP, as latter is rich in periosteal stem cells. In conclusion, HFL is likely suitable to replace HP architecture to confer a guide for bone consolidation, with an absence of osteogenicity. This study could pave the way to a bio-engineered periosteum built from HFL.

Pathological Features in Paediatric Patients with TK2 Deficiency.

Thymidine kinase (TK2) deficiency causes mitochondrial DNA depletion syndrome. We aimed to report the clinical, biochemical, genetic, histopathological, and ultrastructural features of a cohort of paediatric patients with TK2 deficiency. Mitochondrial DNA was isolated from muscle biopsies to assess depletions and deletions. The TK2 genes were sequenced using Sanger sequencing from genomic DNA. All muscle biopsies presented ragged red fibres (RRFs), and the prevalence was greater in younger ages, along with an increase in succinate dehydrogenase (SDH) activity and cytochrome c oxidase (COX)-negative fibres. An endomysial inflammatory infiltrate was observed in younger patients and was accompanied by an overexpression of major histocompatibility complex type I (MHC I). The immunofluorescence study for complex I and IV showed a greater number of fibres than those that were visualized by COX staining. In the ultrastructural analysis, we found three major types of mitochondrial alterations, consisting of concentrically arranged lamellar cristae, electrodense granules, and intramitochondrial vacuoles. The pathological features in the muscle showed substantial differences in the youngest patients when compared with those that had a later onset of the disease. Additional ultrastructural features are described in the muscle biopsy, such as sarcomeric de-structuration in the youngest patients with a more severe phenotype.

Antigen presentation by cardiac fibroblasts promotes cardiac dysfunction.

Heart failure (HF) is a leading cause of morbidity and mortality. Studies in animal models and patients with HF revealed a prominent role for CD4+ T cell immune responses in the pathogenesis of HF and highlighted an active crosstalk between cardiac fibroblasts and IFNγ producing CD4+ T cells that results in profibrotic myofibroblast transformation. Whether cardiac fibroblasts concomitantly modulate pathogenic cardiac CD4+ T cell immune responses is unknown. Here we show report that murine cardiac fibroblasts express major histocompatibility complex type II (MHCII) in two different experimental models of cardiac inflammation. We demonstrate that cardiac fibroblasts take up and process antigens for presentation to CD4+ T cells via MHCII induced by IFNγ. Conditional deletion of MhcII in cardiac fibroblasts ameliorates cardiac remodelling and dysfunction induced by cardiac pressure overload. Collectively, we demonstrate that cardiac fibroblasts function as antigen presenting cells (APCs) and contribute to cardiac fibrosis and dysfunction through IFNγ induced MHCII.

Long term patterns of association between MHC and helminth burdens in the bank vole support Red Queen dynamics.

Major histocompatibility complex (MHC) genes encode proteins crucial for adaptive immunity of vertebrates. Negative frequency‐dependent selection (NFDS), resulting from adaptation of parasites to common MHC types, has been hypothesized to maintain high, functionally relevant polymorphism of MHC, but demonstration of this relationship has remained elusive. In particular, differentiation of NFDS from fluctuating selection, resulting from changes in parasite communities in time and space (FS), has proved difficult in short‐term studies. Here, we used temporal data, accumulated through long‐term monitoring of helminths infecting bank voles (Myodes glareolus), to test specific predictions of NFDS on MHC class II. Data were collected in three, moderately genetically differentiated subpopulations in Poland, which were characterized by some stable spatiotemporal helminth communities but also events indicating introduction of new species and loss of others. We found a complex association between individual MHC diversity and species richness, where intermediate numbers of DRB supertypes correlated with lowest species richness, but the opposite was true for DQB supertypes—arguing against universal selection for immunogenetic optimality. We also showed that particular MHC supertypes explain a portion of the variance in prevalence and abundance of helminths, but this effect was subpopulation‐specific, which is consistent with both NFDS and FS. Finally, in line with NFDS, we found that certain helminths that have recently colonized or spread in a given subpopulation, more frequently or intensely infected voles with MHC supertypes that have been common in the recent past. Overall, our results highlight complex spatial and temporal patterns of MHC‐parasite associations, the latter being consistent with Red Queen coevolutionary dynamics.

Some immunological responses in rats injected with prepared bacterin toxoid of local methicillin resistant Staphylococcus aureus

This study was aimed to prepare bacterin toxoid from local isolate of methicillin resistant Staphylococcus aureus (MRSA) isolated from bovine mastitis in Basrah province. Isolated MRSA was detected and confirmed using polymerase chain reaction. Then inactivated bacterin toxoid was prepared. A total of 45 male albino rats were used in 3 mainly groups to assess the bacterin toxoid. For immunological response, the concentrations of IL-4, CD4+, and CD8+ T-cells were estimated using enzyme linked immunosorbent assay. The results showed increase in the concentrations of IL-4, CD4+ and CD8+ T-cells in vaccinated group comparing with non-vaccinated control group. Increasing concentrations of IL-4 enhance humoral immune response by stimulation of Th2 that effect directly on B-cells differentiating them to plasma cells responsible for production of specific antibodies against MRSA. Increased CD4+T-cells also enhance humoral immune response as a result of interaction between them and antigen-presenting cells which presented major histocompatibility complex (MHC) type II on their surface, while increased CD8+T-cells enhance cellular immune response as a result of interaction between them and somatic effected cells presented MHC type I on their surface leading to differentiation them to Cytotoxic T lymphocytes (CTLs) responsible for the killing of effected cells. It was concluded that locally prepared bacterin toxoid proved their efficacy to stimulate both humoral and cell mediated immunity in rats as an experimental animal model.

Distribution of Immune Cells Including Macrophages in the Human Cochlea.

Background: The human cochlea was earlier believed to lack capacity to mount specific immune responses. Recent studies established that the human cochlea holds macrophages. The cells appear to surveil, dispose of, and restore wasted cells to maintain tissue integrity. Macrophage activities are believed to be the central elements in immune responses and could swiftly defuse invading microbes that enter via adjacent infection-prone areas. This review updates recent human studies in light of the current literature and adds information about chemokine gene expression.Materials and Methods: We analyzed surgically obtained human tissue using immunohistochemistry, confocal microscopy, and multichannel super-resolution structured illumination microscopy. The samples were considered representative of steady-state conditions. Antibodies against the ionized calcium-binding adaptor molecule 1 were used to identify the macrophages. CD68 and CD11b, and the major histocompatibility complex type II (MHCII) and CD4 and CD8 were analyzed. The RNAscope technique was used for fractalkine gene localization.Results: Many macrophages were found around blood vessels in the stria vascularis but not CD4 and CD8 lymphocytes. Amoeboid macrophages were identified in the spiral ganglion with surveilling “antennae” projecting against targeted cells. Synapse-like contacts were seen on spiral ganglion cell bodies richly expressing single CXC3CL gene transcripts. Branching neurite-like processes extended along central and peripheral axons. Active macrophages were occasionally found near degenerating hair cells. Some macrophage-interacting T lymphocytes were observed between the scala tympani wall and Rosenthal's canal. CD4 and CD8 cells were not found in the organ of Corti.Conclusions: The results indicate that the human cochlea is equipped with macrophages and potentially lymphocytes, suggesting both an innate and adaptive immune capacity. A rich expression of fractalkine gene transcripts in spiral ganglion neurons suggest an essential role for auditory nerve protection, as has been demonstrated experimentally. The findings provide further information on the important role of the immune machinery present in the human inner ear and its potential to carry adverse immune reactions, including cytotoxic and foreign body responses. The results can be used to form a rationale for therapies aiming to modulate these immune activities.

Transcriptional Immunoediting of AML Cells after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse of AML after allogeneic hematopoietic stem cell transplantation (alloSCT) has been linked to reduced expression of major histocompatibility complex type II proteins (MHC-II), which appears to have a regulatory basis. To understand the mechanism of immune evasion in AML, we developed CORENODE, a computational algorithm for genome-wide transcription network decomposition. CORENODE identified the transcription factors (TFs) IRF8 and MEF2C as positive regulators and MYB and MEIS1 as negative regulators of the MHC-II expression in AML. We validated this prediction using several approaches. First, inactivation of IRF8 and MEF2C in AML cell lines by CRISPR-Cas9 resulted in decreased MHC-II expression, while inactivation of MYB and MEIS1 led to MHC-II induction. Second, decreased levels of IRF8 and MEF2C, and increased levels of MYB and MEIS1 were seen in patients with AML relapse after alloSCT, correlating with reduced expression of MHC-II. Finally, MHC-II expression in various patient-derived datasets could be accurately predicted by CORENODE from the combinatorial levels of the 4 TFs. Although immune evasion in AML has been linked to the transcriptional coactivator CIITA, CORENODE predicted that members of the TF tetrad regulate MHC-II genes independently from CIITA. Indeed, inactivation of MYB and MEIS1 in a CIITA knockout AML cell line was able to cause MHC-II induction. Beyond MHC-II, CORENODE identified a module of 58 genes that were up-regulated by IRF8 and down-regulated by MYB. The module was highly enriched for genes participating in graft-versus-leukemia (GvL) reactivity and we found it to be downregulated in 5 of 6 patients with a post-alloSCT AML relapse. Thus, the post-alloSCT changes in MHC-II expression are part of a broader transcriptional program of GvL response in AML, antagonistically regulated by MYB and IRF8. However, reduced expression of MHC-II and other GvL response genes at relapse does not correlate with the myeloid differentiation state, indicating that it is regulated independently. To understand the clonal basis of MHC-II expression loss at the time of relapse, we analyzed MHC-II expression at the single-cell level. Analysis of previously published paired scRNA data at the time of initial diagnosis and after alloSCT demonstrated a small number of cells with reduced MHC-II expression driven by altered MYB and IRF8 levels present at the time of initial diagnosis. These MHC-II-low cells appear to be selected by the immune pressure, resulting in eventual relapse. In summary, our findings reveal an adaptive transcriptional mechanism of AML immunoediting after allogenic transplantation whereby combinatorial fluctuations of TF levels under immune pressure result in selection of cells with a silenced T-cell stimulation program. [Display omitted] DisclosuresStegmaier: Auron Therapeutics, Kronos Bio, AstraZeneca, Novartis Institute of Biomedical Research: Consultancy, Research Funding.

Beyond the Driver Mutation: Immunotherapies in Gastrointestinal Stromal Tumors.

Gastrointestinal stromal tumors (GISTs) are a subtype of soft tissue sarcoma (STS), and have become a concept of oncogenic addiction and targeted therapies.The large majority of these tumors develop after a mutation in KIT or platelet derived growth factor receptor α (PDGFRα), resulting in uncontrolled proliferation. GISTs are highly sensitive to imatinib. GISTs are immune infiltrated tumors with a predominance of tumor-associated macrophages (TAMs) and T-cells, including many CD8+ T-cells, whose numbers are prognostic. The genomic expression profile is that of an inhibited Th1 response and the presence of tertiary lymphoid structures and B cell signatures, which are known as predictive to response to ICI. However, the microtumoral environment has immunosuppressive attributes, with immunosuppressive M2 macrophages, overexpression of indoleamine 2,3-dioxygenase (IDO) or PD-L1, and loss of major histocompatibility complex type 1. In addition to inhibiting the KIT oncogene, imatinib appears to act by promoting cytotoxic T-cell activity, interacting with natural killer cells, and inhibiting the expression of PD-L1. Paradoxically, imatinib also appears to induce M2 polarization of macrophages. There have been few immunotherapy trials with anti-CTLA-4 or anti-PD-L1drugs and available clinical data are not very promising. Based on this comprehensive analysis of TME, we believe three immunotherapeutic strategies must be underlined in GIST. First, patients included in clinical trials must be better selected, based on the identified driver mutation (such as PDGFRα D842V mutation), the presence of tertiary lymphoid structures (TLS) or PD-L1 expression. Moreover, innovative immunotherapeutic agents also provide great interest in GIST, and there is a strong rationale for exploring IDO targeting after disease progression during imatinib therapy. Finally and most importantly, there is a strong rationale to combine of c-kit inhibition with immune checkpoint inhibitors.

The Paratuberculosis Paradigm Examined: A Review of Host Genetic Resistance and Innate Immune Fitness in Mycobacterium avium subsp. Paratuberculosis Infection.

Paratuberculosis, or Johne's Disease (JD) is a debilitating chronic enteritis mainly affecting ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This organism causes worldwide economic losses to the livestock industry, and is of public health importance due to the potential zoonotic risk between MAP and Crohn's disease (CD) in humans. Without economical treatments, or a vaccine capable of preventing infection without causing cross-reactions with bovine tuberculosis, test-and-cull methods for disease control are imperative. Unfortunately, difficulties in diagnostics and long subclinical stage hinder adequate control and is further complicated by variation in MAP exposure outcome. Interestingly, the majority of infections result in asymptomatic presentation and never progress to clinical disease. One contributing factor is host genetics, where polymorphisms in innate immune genes have been found to influence resistance and susceptibility to disease. Candidate genes identified across studies overlap with those found in CD and tuberculosis including; Solute carrier family 11 member 1 gene (SLC11A1), Nucleotide-binding-oligomerization domain containing gene 2 (NOD2), Major histocompatibility complex type II (MHC-II), and Toll-like receptor (TLR) genes. This review will highlight evidence supporting the vital role of these genes in MAP infection outcome, associated challenges, and implications for the future of JD research.

A Decade Experience on Severe Combined Immunodeficiency Phenotype in Oman, Bridging to Newborn Screening.

IntroductionSevere combined immunodeficiency (SCID) results from various monogenic defects that impair immune function and brings on early severe and life-threatening infections. The main stay of treatment for SCID is hematopoietic stem cell transplant (HSCT) with near normal survival at 5 years for an early transplant done at or before the age of 3.5 months of life and the patient is maintained free of infections. Although overall rare, it constitutes a major burden on affected children, their families and on the health system especially in communities with a high rate of consanguinity where incidence and prevalence of recessive inborn errors of immunity (IEI) are expected to be high.MethodHere, we report the clinical, immunological, and molecular findings in 36 children diagnosed with SCID from a single tertiary center in Oman for the last decade.ResultsWe observed a median annual incidence rate of 4.5 per 100,000 Omani live births, and 91.7% of affected children were born to consanguineous parents. Twenty-three children (63.9%) fulfilled the criteria for typical SCID. The median age at onset, diagnosis and diagnostic delay were 54, 135, and 68 days, respectively. The most common clinical manifestations were pneumonia, septicemia, and chronic diarrhea. Eleven children (30.6%) have received hematopoietic stem cell transplant (HSCT) with a survival rate of 73%. The most frequent genetic cause of SCID in this cohort (n = 36) was (RAG-1), encoding for recombination activating gene (n = 5, 13.9%). Similarly, Major histocompatibility complex type II deficiency accounted for (n = 5, 13.9%) of our cohort.ConclusionOur report broadens the knowledge of clinical and molecular manifestations in children with SCID in the region and highlights the need to initiate newborn based screening program (NBS) program.

Characterization of two MHC II genes (DOB, DRB) in white-tailed deer (Odocoileus virginianus)

BackgroundThe major histocompatibility complex (MHC) is responsible for detecting and addressing foreign pathogens inside the body. While the general structure of MHC genes is relatively well conserved among mammalian species, it is notably different among ruminants due to a chromosomal inversion that splits MHC type II genes into two subregions (IIa, IIb). Recombination rates are reportedly high between these subregions, and a lack of linkage has been documented in domestic ruminants. However, no study has yet examined the degree of linkage between these subregions in a wild ruminant. The white-tailed deer (Odocoileus virginianus), a popular ruminant of the Cervidae family, is habitually plagued by pathogens in its natural environment (e.g. Haemonchus contortus, Elaeophora). Due to the association between MHC haplotypes and disease susceptibility, a deeper understanding of MHC polymorphism and linkage between MHC genes can further aid in this species’ successful management. We sequenced MHC-DRB exon 2 (IIa) and MHC-DOB exon 2 (IIb) on the MiSeq platform from an enclosed white-tailed deer population located in Alabama.ResultsWe identified 12 new MHC-DRB alleles, and resampled 7 alleles, which along with other published alleles brings the total number of documented alleles in white-tailed deer to 30 for MHC-DRB exon 2. The first examination of MHC-DOB in white-tailed deer found significantly less polymorphism (11 alleles), as was expected of a non-classical MHC gene. While MHC-DRB was found to be under positive, diversifying selection, MHC-DOB was found to be under purifying selection for white-tailed deer. We found no significant linkage disequilibrium between MHC-DRB and MHC-DOB, suggesting that these loci are unlikely to be closely linked.ConclusionsOverall, this study identified 12 new MHC-DRB exon 2 alleles and characterized a new, non-classical, MHC II gene (MHC-DOB) for white-tailed deer. We also found a lack of significant linkage between these two loci, which supports previous findings of a chromosomal inversion within the MHC type II gene region in ruminants, and suggests that white-tailed deer may have a recombination hotspot between these MHC regions similar to that found for Bos taurus.

Galectin-8 Enhances T cell Response by Promotion of Antigen Internalization and Processing.

SummaryGalectin-8 (Gal-8) is a mammalian lectin endowed with immunostimulatory ability. In the present work, we demonstrate that Gal-8-glycan interactions on the surface of antigen-presenting cells (APCs) promote antigen binding and internalization, independently from antigen nature. Both Gal-8 and antigen were together internalized and localized in early endosomes. Interestingly, antigen processing by APCs was also accelerated in the presence of Gal-8 as a separate mechanism, distinct from the increased antigen internalization. Moreover, APCs pulsed together with antigen and Gal-8 were able to activate cognate CD4+ T cells more efficiently than those pulsed with antigen alone. This enhanced antigen presentation was still evident in the absence of costimulatory signals and APCs-derived soluble mediators. Therefore, our results provide evidence for as yet unrecognized mechanism by which Gal-8 stimulates the elicitation of the immune response in a lectin-dependent manner, by inducing antigen uptake and processing upon lattice formation at APCs surface.

Radiation effects on Toxoplasma antigens: different immune responses of irradiated intact tachyzoites or soluble antigens in experimental mice models

Purpose: Purpose: Protein irradiation causes aggregation, chain breakage, and oxidation, enhancing its uptake by antigen-presenting cells. To evaluate if irradiated proteins participate on the protection, we studied the immune response induced in mice immunized with irradiated soluble extracts of T. gondii tachyzoites (STag) or irradiated intact T. gondii RH tachyzoites (RH0.25 kGy).Material and Methods: Soluble extracts of Toxoplasma gondii tachyzoites (STag) were irradiated at different dose by Cobalt-60 source. By polyacrylamide gel electrophoresis (SDS-Page) we evaluated the effects on primary structures of protein STags induced by irradiation. By Enzyme-linked Immunosorbent Assay (ELISA) we evaluated the difference between humoral immune response induced by irradiated STag or RH tachyzoites in immunized mice from the detection of specific immunoglobulin G (IgG) antibodies in the serum of immunized mice. From challenge with viable RH strain of T. gondii we evaluated the protection induced in the immunized animals. By cytometry we performed the phenotyping of T and B lymphocytes in the peripheral blood of the immunized animals.Results: Irradiation dose of 1.5 kGy induced minimal changes in most proteins, without affecting their antigenicity or immunogenicity. Immunization showed saturation at the dose of 10 µg/mice, with worst response at higher doses. STag irradiated at 1.5 kGy (STag1.5 kGy) induced higher survival and protection similar to T. gondii RH strain irradiated at 0.25 kGy (RH0.25 kGy), with higher serum levels of high affinity IgG compared to STag native. Blood immune memory cells of mice immunized with STag1.5 kGy had higher proportions of CD19+ (cluster of differentiation 19) and CD4+ (cluster of differentiation 14) cells, whereas mice RH0.25 kGy had high proportion of memory CD8+ (cluster of differentiation 8) cells.Conclusions: Our data suggest that major histocompatibility complex type I (MHCI) pathway, appears seem to be used by RH0.25 kGy to generate cytotoxic cells while STag1.5 kGy uses a major histocompatibility complex type II (MHCII) pathway for B-cell memory, but both induce sufficient immune response for protection in mice without any adjuvant. Irradiation of soluble protein extracts enhances their immune response, allowing similar protection against T. gondii in mice as compared to irradiated intact parasites.