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PubMed2025

Major histocompatibility complex class IIB disassortative mate choice in a genetically monogamous seabird.

Among species reproducing sexually, mating strategies represent a major component of individual fitness. The major histocompatibility complex (MHC) is an extremely diverse set of genes responsible for immunological recognition and defence against pathogens. Although dissimilarity between mates at the major histocompatibility complex has been proposed to drive mate choice through increased offspring pathogen resistance, evidence is mixed. In addition, explorations of the role of the major histocompatibility complex in other mating strategies, such as divorce, are rare. We investigated whether dissimilarity at the major histocompatibility complex class IIB is associated with mate choice and divorce probability in the genetically monogamous black-legged kittiwake (Rissa tridactyla). We found that first-time male breeders, as well as divorced males, were paired with females more dissimilar at the major histocompatibility complex class IIB than expected under random mating. We did not find evidence for mate choice based on major histocompatibility complex class IIB dissimilarity when considering females. In addition, in the studied population, divorce probability was very low compared with other populations and did not significantly vary with the dissimilarity of the pair at the major histocompatibility complex class IIB. Our results pave the way to a better understanding of the complex role of major histocompatibility complex dissimilarity in mating decisions of species displaying mutual choice and biparental care.

Animals↗

PubMed2024

Local Ancestry at the Major Histocompatibility Complex Region is Not a Major Contributor to Disease Heterogeneity in a Multiethnic Lupus Cohort.

OBJECTIVE: Systemic lupus erythematosus (SLE) is an autoimmune disease resulting in debilitating clinical manifestations that vary in severity by race and ethnicity with a disproportionate burden in African American, Mestizo, and Asian populations compared with populations of European descent. Differences in global and local genetic ancestry may shed light on the underlying mechanisms contributing to these disparities, including increased prevalence of lupus nephritis, younger age of symptom onset, and presence of autoantibodies. METHODS: A total of 1,139 European, African American, and Mestizos patients with SLE were genotyped using the Affymetrix LAT1 World array. Global ancestry proportions were estimated using ADMIXTURE, and local ancestry was estimated using RFMIXv2.0. We investigated associations between lupus nephritis, age at onset, and autoantibody status with both global and local ancestry proportions within the Major Histocompatibility Complex region. RESULTS: Our results showed small effect sizes that did not meet the threshold for statistical significance for global or local ancestry proportions in either African American or Mestizo patients with SLE who presented with the clinical manifestations of interest compared with those who did not. CONCLUSION: These findings suggest that local genetic ancestry within the Major Histocompatibility Complex region is not a major contributor to these SLE manifestations among patients with SLE from admixed populations.

Humans↗

PubMed2026

Influence of Major Histocompatibility Complex (MHC) Diversity on Immune Modulation, Pathogenesis, and Control of Lumpy Skin Disease Virus.

INTRODUCTION: Lumpy Skin Disease Virus (LSDV), a member of the genus Capripoxvirus within the family Poxviridae, is an economically important transboundary viral pathogen affecting cattle and water buffalo. The disease causes severe production losses through decreased milk yield, infertility, hide damage, reduced growth performance, and occasional mortality. The rapid geographic spread of LSDV, together with its vectorborne transmission and emerging recombinant strains, has intensified the need for improved understanding of viral pathogenesis, host immune responses, and effective prevention strategies. In particular, the role of the bovine Major Histocompatibility Complex (BoLA/MHC) in regulating antiviral immunity, disease susceptibility, and vaccine responsiveness has gained increasing scientific attention. METHODS: This review summarises the published literature related to the epidemiology, transmission, structure, pathogenesis, diagnosis, prevention, and control of LSDV, with special emphasis on the immunological and molecular role of bovine MHC molecules. Relevant studies concerning BoLA-mediated antigen presentation, immunoinformaticsbased epitope prediction, vaccine development, antiviral drug repurposing, molecular docking, genomic surveillance, and diagnostic approaches, including PCR- and ELISAbased assays, were critically evaluated. Recent advances in computational biology, molecular virology, and host-pathogen interaction studies were also reviewed. RESULTS: The reviewed studies demonstrate that Lumpy Skin Disease Virus (LSDV) possesses a complex double-stranded DNA genome enabling immune modulation and efficient transmission through arthropod vectors such as mosquitoes, ticks, and biting flies. Disease progression involves systemic viral replication, vascular injury, dermal necrosis, and inflammatory skin lesions. Real-time PCR remains the most sensitive diagnostic method for early detection, while ELISA supports surveillance. Evidence highlights the central role of bovine Major Histocompatibility Complex (BoLA) molecules in antigen presentation and T-cell activation. Computational studies identified promising BoLA-binding epitopes and repurposed antiviral candidates, including ivermectin, theaflavin, canagliflozin, and tepotinib, for future therapeutic development. DISCUSSION: Current evidence indicates that effective LSDV control requires integration of molecular diagnostics, vector management, vaccination, and host immunogenetics. BoLAguided immunoinformatics provides promising opportunities for developing multi-epitope vaccines, although experimental validation remains essential. Similarly, repurposed antiviral candidates require comprehensive in vivo and pharmacological evaluation before clinical application. Future research should focus on elucidating viral immune-evasion mechanisms, validating predicted epitopes, and translating computational findings into practical vaccines and therapeutics for sustainable disease control. CONCLUSION: Lumpy Skin Disease continues to pose a major threat to global cattle health and livestock economies. Advances in molecular diagnostics, genomic surveillance, antiviral drug discovery, and BoLA-guided vaccine design provide promising opportunities for improved disease control. Understanding the interaction between LSDV and the bovine MHC system is essential for developing next-generation vaccines, immunotherapeutics, and precision disease-management strategies. Future research should prioritise experimental validation of predicted epitopes, large-scale vaccine trials, and mechanistic studies on host-virus immune interactions to establish effective and sustainable global control programs for LSDV.

BoLA↗

PubMed2025

Epistasis of ERAP1 With 4 Major Histocompatibility Complex Class I Alleles in Frontal Fibrosing Alopecia: A Genome-Wide Association Study Meta-Analysis.

IMPORTANCE: Frontal fibrosing alopecia (FFA) is an inflammatory and scarring form of hair loss of increasing prevalence that most commonly affects women. An improved understanding of the genetic basis of FFA will support the identification of pathogenic mechanisms and therapeutic targets. OBJECTIVE: To identify novel genomic loci at which common genetic variation affects FFA susceptibility and assess nonadditive effects on genetic risk between susceptibility loci. DESIGN, SETTING, AND PARTICIPANTS: Four genome-wide association studies were combined using an SE-weighted meta-analysis. Within the major histocompatibility complex (MHC) locus, stepwise conditional analysis was undertaken to determine independently associated classical MHC class I alleles. Statistical tests for epistatic interaction were performed between risk alleles at the MHC and endoplasmic reticulum aminopeptidase 1 (ERAP1) loci. MAIN OUTCOMES AND MEASURES: Genome-wide significant locus associated with FFA and nonadditive effects on genetic risk between susceptibility loci. RESULTS: Of 6668 included patients, there were 1585 European female individuals with FFA and 5083 controls. Genome-wide significant associations were identified at 4 genomic loci, including a novel susceptibility locus at 5q15, and the association signal could be fine-mapped to a single nucleotide substitution (rs10045403) in the 5' untranslated region of ERAP1 (rs10045403; odds ratio, 1.30; 95% CI, 1.19-1.43; P = 3.6 × 10-8). Within the MHC, FFA risk was statistically independently associated with HLA-A*11:01, HLA-A*33:01, HLA-B*07:02, and HLA-B*35:01. FFA risk was affected by genetic variation at the ERAP1 locus only in individuals who carried at least 1 of the MHC class I risk alleles. CONCLUSIONS AND RELEVANCE: In this genome-wide meta-analysis, a supra-additive effect of genetic variation was found that affected peptide trimming and antigen presentation on FFA susceptibility. Patients with FFA may benefit from emerging therapeutic approaches that modulate ERAP-mediated processes.

Female↗

PubMed2026

Intra-colony divergence and global allele sharing reflect purifying selection and recombination at the Botryllus histocompatibility factor locus.

Urochordates, the closest relatives of vertebrates, lack adaptive immunity. However, some taxa, such as the colonial species Botryllus schlosseri, provide a unique model for studying innate self/non-self recognition through natural allogeneic transplantation responses. In this species, interactions between colonies are controlled by a highly polymorphic locus, with the Botryllus histocompatibility factor (BHF) being the only gene known to predict tissue fusion or rejection outcomes with complete accuracy. Here, we analyzed full-length BHF alleles from 19 laboratory-born and wild colonies and found that highly divergent alleles tend to coexist within individuals, whereas identical alleles can be shared across continental-scale distances. Despite extensive length variation, evidence of intragenic recombination, and pronounced nucleotide diversity, BHF exhibits limited protein divergence, with 33 alleles encoding only 17 distinct protein variants. Contrary to expectations for polymorphic recognition genes, no evidence of balancing or directional selection was detected. Instead, signatures of purifying selection were observed. We propose that this contrast between nucleotide and protein diversity arises from the combined effects of recombination, human-mediated gene flow, and linkage to nearby loci under balancing selection, while functional constraints maintain protein stability. These findings suggest that extensive protein diversification may not be a universal driver of allorecognition gene evolution.

Animals↗

PubMed2025

Frequency and Distribution of KIR Genotypes of Donors-Recipient Pairs in the Haploidentical Haematopoietic Stem Cell Transplantation Setting: Collaborative Study by the Spanish Working Group in Histocompatibility and Transplant Immunology (GETHIT) and the Spanish Haematopoietic Transplantation and Cell Therapy Group (GETH-TC).

There is limited information regarding the influence of KIR genotype, compared to the HLA system, in haploidentical haematopoietic stem cell transplantation (haplo-HSCT). This study aimed to determine the frequencies of KIR genotypes in Spanish haematologic patients undergoing haplo-HSCT. A study was conducted on 113 oncohaematological patients and their donors, treated across five centres that are members of the Spanish Working Group in Histocompatibility and Transplant Immunology (GETHIT) and the Spanish Haematopoietic Transplantation and Cell Therapy Group (GETH-TC). KIR typing was performed using PCR-rSSO or PCR-SSP. KIR genotypes were identified using the KIR Allele Frequency Net Database. Among donors, the most frequent KIR genotypes were Type 1 (28.3%), Type 2 (12.4%) and Type 4 (10.6%). In patients, Genotypes 1 (23.9%), 4 (23%) and 2 (14.2%) were most prevalent. Donors exhibited AA centromeric (46%) and telomeric (59.3%) types, while patients had a higher AB centromeric frequency (52.2%). Differences were observed in the BB centromeric type (3.5% patients; 16.8% donors, p = 0.002). The AB KIR genotype was the most common (70.8% donors; 75.2% patients). Most were classified as 'neutral' (61.9% donors; 73.5% patients). B-content score1 was the most common (48.7% patients; 33.6% donors). Notably, classification as best was rare (2.7% patients; 16.8% donors, p = 0.002). The study highlights the distribution of KIR genotypes in haplo-HSCT patients and donors, with Genotypes 1, 2 and 4 being the most prevalent. AB KIR genotypes and B-content score 1 were dominant. Moreover, KIR genotypes ID may serve as criteria for future investigation about the immunogenetic predisposition to malignant haematological diseases.

Humans↗

PubMed2004

Bovine leukocyte antigen major histocompatibility complex class II DRB32703 and DRB31501 alleles are associated with variation in levels of protection against Theileria parva challenge following immunization with the sporozoite p67 antigen.

Initial laboratory trials of an experimental subunit vaccine against Theileria parva based on the 67-kDa major sporozoite surface antigen revealed a range of responses to challenge. We have analyzed convergence in seven sets of monozygotic twins which suggests that genetic factors may have an influence in determining the degree of protection provided by p67 immunization. In addition, we have examined whether allelic diversity at major histocompatibility complex class II loci influences protection. Analysis of bovine leukocyte antigen DRB3 diversity in 201 animals identified significant associations with vaccine success (DRB3*2703; P = 0.027) and vaccine failure (DRB3*1501; P = 0.013). Furthermore, DRB3*2703 was associated with the likelihood of immunized animals showing little to no clinical signs of disease following challenge. We discuss the acquired and innate immune mechanisms that may be behind the associations described here.

Alleles↗

PubMed2026

Functional Annotation of the Major Histocompatibility Complex Locus.

The human major histocompatibility complex (MHC) locus has the greatest density of disease-associations in the human genome, including links to over 100 polygenic disorders. Its complex haplotype structure, rich gene density, and high degree of linkage disequilibrium combine to make deciphering the gene regulatory logic of the MHC locus extremely challenging. Employing complementary high-throughput CRISPR interference (CRISPRi) and activation (CRISPRa) epigenetic screens coupled with single-cell transcriptome profiling across three distinct human cell types, we identified hundreds of new connections between cis -regulatory elements (CREs) and their target genes in this locus. These CRE-gene links are largely cell type-specific and act as enhancers. Additionally, some CREs have complex features, including harboring both active and repressive histone marks, lacking chromatin accessibility, targeting multiple genes, or acting as silencers. Computational methods fail to predict a majority of these CRE-gene connections. These findings emphasize the potential for functional perturbation experiments to dissect complex loci and reveal shared and cell type-specific regulatory mechanisms relevant to genomics of complex diseases. Collectively, this study provides a unique resource for understanding the complex regulatory landscape within the MHC locus and supports the need for creating new models that encompass CRE-gene interactions, cell type-specific gene expression, and disease genetics in the noncoding genome.

Journal Article↗

PubMed2025

Guidelines From the French-Speaking Society for Histocompatibility and Immunogenetics (SFHI) for Harmonisation of HLA Genotyping in Autoimmune Diseases, Drug Hypersensitivity and Pharmacogenetics.

HLA molecules play a central role in the adaptive immune response. Their high polymorphism influences individual susceptibility to various autoimmune diseases and certain drug-induced hypersensitivities. In France, HLA genotyping is classified as a medical genetics procedure and is strictly regulated. The Société Francophone d'Histocompatibilité et d'Immunogénétique (SFHI) has established national guidelines outlining clinically validated indications, required resolution levels and interpretation criteria based on robust data. These guidelines are particularly relevant for common clinical contexts, including autoimmune diseases and pharmacogenetic testing. Well-established associations include HLA-DQB1*02/DQA1*05 (DQ2) and HLA-DQB1*03:02/DQA1*05 (DQ8) with celiac disease, HLA-B*27 with spondyloarthritis, HLA-DQB1*06:02 with type 1 narcolepsy, HLA-A*29 with Birdshot chorioretinopathy and several pharmacogenetic risk alleles such as HLA-B*57:01 (abacavir), HLA-B*15:02 and HLA-A*31:01 (carbamazepine) and HLA-B*58:01 (allopurinol). In immunotherapy, the efficacy of tebentafusp has been shown to depend on HLA-A*02:01 positivity. HLA alleles must be interpreted as relative risk factors, not absolute predictors. Critical analysis of HLA-related scientific literature requires consideration of the genotyping technique, typing resolution, allele frequencies within the studied population and environmental factors. High-resolution typing is essential in pharmacogenetics and recommended in selected autoimmune disorders. Interpretation should be conducted by qualified medical biologists, integrating clinical context, allelic diversity and recent technological advances, particularly next-generation sequencing. HLA genotyping represents a valuable tool in diagnosis and risk assessment, with increasing importance in the era of personalised medicine.

Humans↗

PubMed2025

Dissecting the shared genetic architecture of schizophrenia with ventricular subregion volumes.

Schizophrenia is characterized by cerebral ventricular enlargement as an early and consistent structural anomaly. While genetic factors significantly influence both schizophrenia and cerebral ventricular enlargement, the shared genetic etiology between them requires further investigation. Using summary statistics from recent large genome-wide association studies on schizophrenia and 9 ventricular subregion volumes phenotypes. Gaussian causal mixture modeling was applied to characterize the genetic architecture and overlap between schizophrenia and ventricular subregion volumes phenotypes. Local genetic correlation was investigated with Local Analysis of Variant Association. The conjunctional false discovery rate framework was used to identify the specific shared genetic loci, annotated with FUMA. Gaussian causal mixture modeling estimated schizophrenia to be more polygenic more polygenic (9574 trait-influencing variants) than ventricular subregion volumes phenotypes (157-1267 trait-influencing variants). Conjunctional false discovery rate analysis identified 42 shared genetic loci, 17 loci were identified as novel for both schizophrenia and the ventricular subregion volumes phenotypes. Local Analysis of Variant Association revealed that 11 distinct loci demonstrated significant differences, among which 4 loci were situated in the Major Histocompatibility Complex region. Annotated genes in shared loci were enriched in molecular signaling pathways involved in inflammation and the brain structure. The shared loci between them were annotated and enriched in Major Histocompatibility Complex and inflammation-related pathways, highlighting new opportunities for future investigation.

Schizophrenia↗

PubMed2005

Comparative genomics of natural killer cell receptor gene clusters.

Many receptors on natural killer (NK) cells recognize major histocompatibility complex class I molecules in order to monitor unhealthy tissues, such as cells infected with viruses, and some tumors. Genes encoding families of NK receptors and related sequences are organized into two main clusters in humans: the natural killer complex on Chromosome 12p13.1, which encodes C-type lectin molecules, and the leukocyte receptor complex on Chromosome 19q13.4, which encodes immunoglobulin superfamily molecules. The composition of these gene clusters differs markedly between closely related species, providing evidence for rapid, lineage-specific expansions or contractions of sets of loci. The choice of NK receptor genes is polarized in the two species most studied, mouse and human. In mouse, the C-type lectin-related Ly49 gene family predominates. Conversely, the single Ly49 sequence is a pseudogene in humans, and the immunoglobulin superfamily KIR gene family is extensive. These different gene sets encode proteins that are comparable in function and genetic diversity, even though they have undergone species-specific expansions. Understanding the biological significance of this curious situation may be aided by studying which NK receptor genes are used in other vertebrates, especially in relation to species-specific differences in genes for major histocompatibility complex class I molecules.

Journal Article↗

PubMed2026

Novel HLA class I and II insights into the pathogenesis of systemic sclerosis-associated interstitial lung disease.

OBJECTIVES: Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is the leading cause of mortality in systemic sclerosis (SSc), yet its genetic architecture remains incompletely understood. Therefore, given the key role of the major histocompatibility complex (MHC) in SSc, we aimed to perform a comprehensive MHC-wide association study in the largest SSc-ILD cohort to date. METHODS: We analysed 2412 patients with SSc-ILD⁺, 3550 patients with SSc-ILD⁻, and 15,076 controls of European ancestry from 10 international cohorts. After quality control, the MHC region was imputed, and inverse variance weighted meta-analysis was performed. Subsequently, conditional stepwise analyses, adjustment for antitopoisomerase autoantibody (ATA) status, and functional annotation of significant single-nucleotide polymorphisms were performed. Finally, we constructed a composite score combining genetic, clinical, and demographic variables to predict SSc-ILD. RESULTS: After conditional analysis, we detected 12 significant associations within class I and class II human leukocyte antigen (HLA) genes. ATA adjustment reduced the significance of class II HLA variants, whereas class I HLA variants remained unaffected. Finally, the built composite score had an area under the curve of 0.754, significantly outperforming the models including any of the variables alone. CONCLUSIONS: In this study, we identify genetic mechanisms underlying SSc-ILD that support the potential implication of CD8+ T cells and ATAs in its pathogenesis. Moreover, we also demonstrate the enhanced efficacy of integrating genetic information into predictive models to detect patients at high risk of SSc-ILD. These findings provide new insights into disease pathogenesis and suggest potential biomarkers and therapeutic targets for improved patient management.

Humans↗

PubMed2026

Allelic variation alters expression and antigen presentation of MR1 allomorphs.

The major histocompatibility complex (MHC) class I-related protein 1 (MR1) presents vitamin B-derived metabolites to mucosal-associated invariant T (MAIT) and other T cells. There is limited polymorphism of MR1, the functional impact of which is not understood. We examined the impact of allelic variation of MR1 on the expression, structure and function of the known MR1 allomorphs. The expression and function of MR1∗02, MR1∗03, and MR1∗06 were similar to the canonical MR1∗01. Crystal structures of four MR1 allomorphs show that their polymorphisms do not impact the three-dimensional fold of MR1. Despite the binding of 5-OP-RU to MR1∗05 and its cell surface upregulation, this allomorph was severely impaired in its ability to activate primary MAIT cells. This phenotype was controlled by two (His90Gln and Glu52Gly) of its three polymorphisms, which led to the loss of structurally stabilizing interactions. When cells expressing the MR1 allomorphs were infected with herpes simplex virus type 1 (HSV-1), the nascent expression of all allomorphs was severely impaired, but surface expression of MR1∗04:01 and MR1∗04:02 was relatively less impacted. Hence, MR1 allelic variation alters the expression and function of the MR1∗04 and MR1∗05 allomorphs, with implications for MAIT cell and diverse MR1-reactive T cell immunity.

Humans↗

PubMed2026

GAMMA: gap-aware motif mining under incomplete labeling with applications to MHC motifs.

MOTIVATION: Sequence motif identification is crucial for understanding molecular recognition, particularly in immune responses involving peptide binding to major histocompatibility complex (MHC) Class I molecules for antigen presentation to T cells. Traditionally, MHC Class I binding motifs are assumed to be contiguous and span nine amino acids. However, structural evidence suggests that binding may involve nonadjacent residues, challenging the assumptions of existing methods. RESULTS: In this study, we propose Gap-Aware Motif Mining Algorithm (GAMMA), a probabilistic framework designed to identify noncontiguous motifs under conditions of incomplete labeling. GAMMA employs Bayesian inference with Markov chain Monte Carlo sampling to jointly estimate motif parameters, binding locations, and the relative spacing between binding positions. Through extensive simulations and real-world applications to MHC Class I peptide datasets, GAMMA outperforms existing motif discovery tools such as GLAM2 in accurately localizing binding residues and identifying the underlying motifs. Notably, our results suggest that the true number of binding residues may be eight, fewer than the commonly assumed nine. In addition, for longer peptides, the model captures increased flexibility in the central region, consistent with structural observations that peptides may bulge in the middle. AVAILABILITY AND IMPLEMENTATION: The raw data and the source codes are available on GitHub (https://github.com/RanLIUaca/GAMMAmotif).

Amino Acid Motifs↗

PubMed2025

Multivariate Effects of SNPs on Environmental Streptococcal Mastitis Evaluated With an NGS-Based Association Study Using Targeted Resequencing in the Bovine MHC Region.

Mastitis is an inflammatory reaction caused by bacterial infection of the teat, and a relationship between its onset and cattle major histocompatibility complex (BoLA) region has been reported. However, no comprehensive genetic analysis of mastitis caused by environmental streptococci has been reported. Here, we resequenced the BoLA region using a hybridisation capture target next-generation sequencing (NGS) method to identify disease susceptibility markers mapped to the BoLA region in environmental streptococcal mastitis. This study examined 75 cows with mastitis caused by environmental streptococci selected from 1641 cows with mastitis and 222 healthy cows without mastitis in Japan. Targeted sequences obtained from MiSeq NGS were aligned to the bovine reference genome (ARS-UCD1.2/bosTau9), and 2,920,355 variants were detected within the BoLA region of the 297 Holstein cattle. In an association study using 2264 variants after quality control, the top 20 variants with the lowest P values were selected and assigned to the 18 surrounding candidate genes, and a gene network analysis of these genes resulted in the narrowing down of five candidate genes POU5F1, IER3, GNL1, ABCF1, and PRR3. Multivariate effect analysis of all 6 SNPs associated with these 5 genes revealed that they were significantly correlated with mastitis, indicating that they were useful for classification of mastitis-resistant and mastitis-susceptible cattle. This is the first report to identify SNPs associated with environmental streptococcal mastitis with an NGS-based association study using targeted resequencing in the BoLA region, and understanding host factors may provide important clues for mastitis control.

Animals↗

PubMed2026

Dendritic cells control tertiary lymphoid structure development and maintenance in cancer.

Tertiary lymphoid structures (TLSs) are associated with immunotherapy response, yet the mechanisms controlling their formation and maintenance remain unclear. Using spatial transcriptomics and multiplex imaging across human tumors, we found that CCR7+ mature dendritic cells (DCs) accumulate in TLSs. In a mouse non-small cell lung cancer model that forms mature TLSs, we show that early TLS development requires interferon-γ (IFN-γ)-driven type 1 conventional dendritic cell (cDC1) maturation, migration to tumor-draining lymph nodes (tdLNs), and T cell recruitment. As tumors progress, TLSs persist independently of tdLN T cell egress, coinciding with cDC1 accumulation within intratumoral CCL19 stromal hubs. There, cDC1-major histocompatibility complex class 1 (MHC-I) and -MHC-II concomitant antigen presentation, along with CD40 signaling, sustain TLS, T follicular helper (TFH) cell pool, germinal centers, and tumor-specific immunoglobulin G (IgG). These findings highlight local mature cDC1s as key TLS orchestrators and potential targets to enhance antitumor TLS function.

Animals↗

PubMed2025

Factors that increase class I MHC expression may contribute to the development of immune checkpoint inhibitor-induced diabetes.

Immune checkpoint inhibitors (ICIs) have improved survival of patients with cancer, yet they pose risks of immune-related adverse events (irAEs). ICI-induced insulin-dependent diabetes mellitus (ICI-DM) is a life-threatening and life-altering irAE. Previously, we reported a high incidence of a germline missense variant in NLRC5, a key class I transcription activator, among patients with ICI-DM compared with similarly treated patients who did not develop ICI-DM. Our purpose was to validate this finding in additional ICI-treated patients and study effects of the NLRC5 variant on expression of class I major histocompatibility complex (MHC) antigen presentation genes.We assessed the prevalence of the C>T missense variant at chr16:57 025 515 (NLRC5Pro191Leu) in germline DNA from an additional 33 patients with ICI-DM and in patients with ICI-induced colitis (n=15), ICI-induced hypothyroidism (n=19) and ICI-induced hypophysitis (n=17). The 1,000 Genomes Project was used for comparison. We assessed peripheral blood mononuclear cells from 16 individuals with or without the NLRC5 variant, studying expression of NLRC5 and select downstream target genes, before and after stimulation with interferon-γ.We validated the higher prevalence of NLRC5Pro191Leu in a non-overlapping cohort of patients with ICI-DM compared with the general population (51.5% vs 12.8%, p<0.0001). The prevalence of NLRC5Pro191Leu in ICI-induced colitis or thyroiditis patients did not significantly differ from the general population, while the prevalence in ICI-induced hypophysitis was somewhat higher (21.6%, p=0.048). We found greater increases in messenger RNA expression of NLRC5 (p=0.007), TAP1 (p=0.0002), B2M (p=0.0005), HLA-G (p=0.04), PSMB8 (p=0.03) and PSMB9 (p=0.01) in NLRC5Pro191Leu cells stimulated with interferon-γ compared with NLRC5WT cells. A similar trend was observed for HLA-A (p=0.09).We confirm the significantly higher prevalence of the NLRC5Pro191Leu variant in patients with ICI-DM relative to the general population. This abundance appears to be unique to patients who develop ICI-DM or hypophysitis on ICIs, underscoring its potential involvement in the pathogenesis of these endocrinopathies. The effects of this NLRC5 variant on class I MHC regulators suggest a mechanistic connection between the variant and development of ICI-DM. Further work is warranted to determine whether class I MHC molecules can be modulated in patients with the NLRC5Pro191Leu variant requiring ICIs.

Humans↗

PubMed2026

HLA-A ∗01:01 Allele Is Associated With Increased Risk of Transplant-Related Mortality After MHC Matched Unmodified Allogeneic Hematopoietic Stem Cell Transplantation.

Acute graft-versus-host disease (aGvHD) remains a substantial cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HCT). Limited studies explore the association between specific major histocompatibility complex (MHC) alleles and aGvHD or transplant-related mortality (TRM). After a noted clinical trend of higher TRM among a series of patients with aGvHD and MHC class I HLA-01:01, we retrospectively evaluated transplant outcomes of 404 adult allo-HCT patients who underwent unmodified allografts between 03/2010 and 02/2017. HLA-01:01 was expressed by 104 (25.7%) patients. In a univariate analysis, patients who underwent unmodified transplants and expressed HLA-01:01 had a higher risk of TRM (HR 1.63 [95% CI: 1.05-2.53], p = 0.035). In a multivariate cause-specific Cox model, HLA-01:01 was significantly associated with TRM after adjusting for grade II-IV aGvHD, conditioning regimen intensity, and age at transplant (HR 1.59 (95% CI: 1.02-2.48) p = 0.039). There were no significant differences in overall survival (OS), aGvHD, or chronic GvHD based on HLA-01:01 expression. With confirmation in a larger cohort, these findings have potential implications for the selection of allograft type, conditioning regimen, and post-transplant monitoring for this high-risk population.

Humans↗