Immunogenetics

Turbot (Scophthalmus maximus) is an important aquaculture species, but the genomic organization and expressed diversity of its antibody repertoire remain incompletely characterized. In this study, we annotated the immunoglobulin heavy chain (IGH) locus using the haplotype resolved fScoMax1.1 genome assembly, and we used this as a reference to profile the expressed turbot IgM, IgD and IgT repertoires in skin and spleen. The primary IGH locus was located on chromosome 19, spanned approximately 72 kb, and contained 25 IGHV genes, including 24 functional genes and one pseudogene, together with three IGHD, seven IGHJ and three IGHC genes corresponding to IgT, IgM and IgD. Comparison with the alternate fScoMax1.1 haplotype and a second turbot genome assembly showed conserved IGHD, IGHJ and IGHC content, whereas IGHV gene number differed among assemblies. High throughput 5RACE repertoire sequencing revealed isotype and tissue associated differences in expressed IGH diversity. IgM represented the dominant productive repertoire in both skin and spleen and showed the highest clonotypic diversity, particularly in spleen. IgD displayed an intermediate profile, whereas IgT was more enriched in skin and exhibited the strongest clonal restriction. IGHV subgroup usage was dominated by IGHV3 in IgM and IgD, whereas IgT showed a distinct profile characterized by preferential use of IGHV4, especially in skin. Gene level analysis further showed broad IGHV-IGHJ pairing in IgM and IgD, with preferential use IGHJ3 segment, while IgT sequences paired exclusively with IGHJT. Clonotype sharing between skin and spleen was isotype dependent, being strongest for IgT, intermediate for IgM, and negligible for IgD, suggesting that clonal expansion did not necessarily predict inter tissue trafficking. Together, these results provide a curated genomic and expressed repertoire framework for turbot IGH genes and reveal isotype specific organization of antibody diversity, with IgT displaying a particular repertoire pattern.

The emergence of donor-specific antibodies (DSA) against HLA-DQ reduces graft survival and limits future transplant options. Current practice predicts DSA development from HLA antigen mismatches or unique eplet counts (HLAMatchmaker), but predictive accuracy remains limited. Improving the prediction accuracy is crucial for solid organ transplants. We analysed a retrospective cohort of 240 kidney transplants (480 donor-DQ samples) in which the donor DQ allele targeted by each post-transplant DSA was identified. We compared the predictive accuracy of unique eplets (HLAMatchmaker), total eplets, amino acid mismatches, PAM genetic distance, and electrostatic mismatch score (EMS), individually and in combination. DSA emerge through the response of two donor and two patient DQ heterodimers. We evaluate the appropriate combination method of patient and donor alleles. Total eplet or amino acid mismatch counts outperformed unique eplets as used in HLAMatchmaker (AUC 0.79 vs. 0.73). Combining eplets with PAM and EMS distances in an XGBoost classifier achieved AUC 0.84, with a hazard ratio above 7. The most informative features were PAM distance and a subset of eplets distributed across the HLA-DQ alpha and beta chains. When extending prediction from a single donor DQ allele to the donor as a whole, the maximum of the two per-allele scores outperformed a probabilistic combination. The unique-eplet approach is suboptimal for predicting anti-DQ DSA in this cohort; combining total eplets with genetic and biochemical distance metrics yields substantially better prediction, essential for the reduction of DSA emergence. External validation in independent cohorts is the necessary next step.

A second IgD gene, IgD2, was first described in the leopard gecko as a hybrid constant-region gene containing IgD-derived exons and terminal IgA-like exons. Related IgD2 architectures have subsequently been recognized in turtles and crocodilians. Here we analyzed Testudines constant-region annotations to determine whether turtle IgD2 represents an intact ancient paralogue or a locally remodeled mosaic gene. Across representative turtle genomes, mixed loci frequently contained upstream D1-D4 exons followed by 3_XA and 4_XA. A direct comparison of paired turtle XA3-XA4 modules with amphibian IgXA and IgM references showed that all turtle modules were closer to amphibian IgXA than to either amphibian or turtle IgM. Upstream D exons, especially D1-D3, instead showed strong local similarity to canonical IgD exons within the same species. A conservative nucleotide tract-permutation test confirmed clustered conversion-like tracts in a subset of D1 and D2 exons, whereas D3 retained local affinity without significant tract clustering. IgY analysis identified 76 complete Y1-Y4 blocks; most were genomically proximal to XA-bearing IgD2 loci on the opposite strand, and contig-restricted randomization confirmed that this association was non-random. All six amino-acid distance-matrix comparisons among Y1-Y4 were significantly correlated, supporting a coupled IgY history without a D-like domain-specific rupture. Independent reannotation recovered 13 complete, one-to-one IgD2/XA-IgY pairs in Chelonia mydas; a thymus transcript encoded the complete D1-D4/XA3- XA4 architecture. Dermochelys coriacea provided three further complete pairs. In Mauremys reevesii, 14 oppositely oriented modules form an array marked by segmental duplication, strand switches, and exon loss. These results support an ancestral paired IgD2-IgY architecture that expanded by segmental duplication to generate the present germline array, while a subset of IgD2 D1 and D2 exons continued to undergo recent intra-species exchange with canonical IgD-derived material. The genomic mechanism can be reconstructed, but the biological significance of maintaining this unusual opposite-strand association remains unknown.

Black-footed ferrets (Mustela nigripes) are highly susceptible to sylvatic plague caused by Yersinia pestis, but the genetic basis of this vulnerability remains poorly understood. Here, comparative immunogenomic analyses across Carnivora species identified a conserved class of immunoglobulin lambda variable (IGLV) genes with unusually long antigen-binding sites (CDRL1) that are common among Caniformia species but absent in Feliformia species. First discovered in the domestic ferret (Mustela putorius furo), these genes encode tyrosine-rich and anionic motifs resembling the chemokine receptor CCR5 and contain experimentally validated sulfotyrosines previously associated with pathogen-interacting interfaces. Evolutionary analyses revealed distinct selective pressures across Caniformia lineages and showed strong purifying selection acting on long-CDRL1 IGLV genes in mustelids and bears. Antibody repertoire sequencing demonstrated that these genes are actively utilized in expressed repertoires and that their usage correlates with evolutionary conservation. Functional analyses of monoclonal antibodies derived from the long-CDRL1 IGLV gene identified an antibody that significantly reduced intracellular Y. pestis survival in macrophages and revealed a positive correlation between anti-plague activity and sulfotyrosine signal. Notably, all analyzed black-footed ferrets carried a frameshifting deletion in the long-CDRL1 IGLV gene resulting in loss of its expression in antibody repertoires. Together, these findings uncover a germline-encoded immunoglobulin feature conserved across dog-like carnivores and suggest a potential link between antibody germline variation and immune responses to plague.

Doublesex and mab-3 related (DMRT) genes encode a family of transcription factors central to sexual development across metazoa. DMRT genes are characterised by a highly conserved DNA binding domain (DM) while flanking regions may vary between species. Gene duplication and loss has shaped the diversity of the DMRT genes with several unresolved questions about their evolution. The most well characterised and conserved DMRT gene, DMRT1, functions as a sexual regulator universally in metazoans. In chicken, DMRT1 is located on the Z chromosome and acts as a dosage dependent primary sex determination gene. In therian mammals DMRT1 is autosomal, however, two copies are required for male development. Interestingly in the basal lineage of egg-laying mammals (monotremes), DMRT1 is localised on the X specific part of one of the X chromosomes. This provided the first evidence of a sex chromosome system with homology to the avian Z chromosome and raises questions about the function and evolution of DMRT1 in egg-laying mammals. To gain insight into the evolution of mammalian DMRT genes we performed sequence and expression analysis of monotreme DMRT genes and comparative analysis with other vertebrates. In monotremes, we identified DMRT genes 1-7, and show that DMRT8 is absent, suggesting that DMRT8 evolved in therian mammals after the divergence of monotremes. Sequence and expression analysis revealed multiple monotreme specific DMRT1 isoforms with additional protein-coding exons. The independent evolution of monotreme specific changes in DMRT1 may be the first indication of functional or regulatory differences in monotreme DMRT1. Article SummaryGenes in the Doublesex and mab-3 related (DMRT) family play important roles in sexual development across animals, but a comprehensive analysis of these transcription factors is lacking in the most basal mammalian lineage of monotremes. This comparative analysis of DMRT genes in monotremes and other vertebrates shows the conservation of DMRT genes 1- 7 but found no evidence of DMRT8 in monotremes or marsupial species, suggesting that this gene evolved in eutherians after the divergence of marsupials. The discovery of several monotreme specific isoforms and novel exons of the X linked DMRT1 reveals unique evolutionary changes in monotreme DMRT1.

T cell repertoire sequencing has unveiled a vast, complex array of T cells responsible for the human immune responses. Traditional analytic methodology fails to fully characterize and quantify the diversity of T cell receptors constituting the T cell repertoire. T cell receptor clonal frequency measured in terms of T cell receptor beta (TRB) V gene segment usage when arrayed in correspondence with the respective V gene segment positions on the TRB loci yields a periodic, undulating curve in the spatial domain of the TRB genomic locus. Using the genomic distance from the TRB-D1 segment to the TRB-V1-29 segments, Fourier analysis was performed utilizing Lomb-Scargle periodogram to obtain Spectral Power curves quantifying the TRB V clonal frequencies from 6 allogeneic stem cell transplant donors (baseline) and recipients (>/=100 days) using a variety of analytic software. Spectral Power curves revealed dominant spectral peaks at wavelengths ranging from 4-9 kb (113-252 millicycles/kb) in the six donors, with consistent frequency domain spectral patterns. This is consistent with similar use of V segments across healthy individuals. Recipients on the other hand demonstrated more dispersed spectra, with a spectral centroid shifted towards higher frequencies compared to donors (260 vs. 247 millicycles/kb). Consistent with this observation, the Low Frequency Index was lower in the recipients (0.18 vs 0.20). Power was concentrated in the <3 kb and 3-12 kb wavelengths in both groups. The analyses reported here demonstrate that the healthy SCT donors have a remarkably similar spectral signature occupying short to intermediate wavelegnths in the frequency domain, whereas recipients tend to shift towards higher frequencies. These findings are consistent with a normal organized distribution of TRB V segment usage in healthy individuals (by analogy other loci), and a more diffuse and disorderly usage in recipients, consistent with the notion of T cell responses constituting a dynamical system which evolves as a function of time. Fourier analysis of TRB (and potentially TRA) sequencing data provides a repertoire wide summary of T cell clonal distribution.

Variant intolerance methods score the essentiality of genes based on large datasets of genetic variants and have been used in population genomics of humans and model organisms. In this paper, we estimated Residual Variation Intolerance Scores for protein-coding genes and predicted protein domains in cattle. In agreement with results from other species, the most variant-tolerant genes and domains included genes related to olfaction and adaptive immunity, whereas the least-variant tolerant genes and domains included genes involved in fundamental cellular processes. There was a moderate positive correlation with estimates from orthologous human genes. We provide estimates of variant intolerance for cattle may be useful for genomic analyses of deleterious variants and population genomics in cattle.

Advances in immunophenotyping of tumour-infiltrating lymphocytes (TILs) have improved our understanding of prognostic biomarkers and immune targets in human melanoma. However, whether the tumour-immune landscape in canine oral malignant melanoma (COMM) is concordant with that of human melanoma has not been properly defined. To address this gap, we developed a 16-colour spectral flow cytometry panel to characterise TIL phenotypic and functional profiles in COMM. Validation using mitogen-stimulated peripheral blood mononuclear cells from healthy dogs (n = 5) demonstrated robust identification of major T cell lineages, including regulatory T cells (Tregs) and memory subsets, and reliable evaluation of their activation and exhaustion status. COMM patients (n = 8) displayed a distinct protumour microenvironment, characterised by an increased proportion of Tregs, enrichment of tumour-specific exhausted-like T cells co-expressing programmed cell death protein 1 (PD-1) and tumour necrosis factor receptor 2 (TNFR2), and a reduction in cytotoxic CD8 and natural killer T (NKT) cell populations compared with tissue-resident (n = 4) and circulating (n = 8) lymphocytes. Analysis of additional solid tumours, including a mast cell tumour, nerve sheath tumour and adrenal cortical carcinoma, further supported the capability of the panel to identify similar patterns of immune dysregulation across diverse canine tumour landscapes. Collectively, this work describes the first detailed evaluation of canine TIL immunophenotyping using spectral flow cytometry and provides insights into the immunosuppressive mechanisms shaping the tumour microenvironment in COMM. These findings not only increase our understanding of canine tumour immunology but also identify potential immune targets and support ongoing comparative immuno-oncology efforts.

Gene duplication is a major source of evolutionary novelty, yet recurrent duplication of the same genomic locus across independent lineages remains understudied. Using a chromosome-scale assembly and de novo annotation of the North American bison (Bison bison), we investigated the mechanisms underlying immune-system diversification in ungulates. Comparative genomics of bison, cattle, elk, and 13 mammalian species identified a large segmental duplication encompassing the regulatory genes REST and NOA1. Although similar duplications were present in 14/16 species examined, phylogenetic analyses revealed that duplicated genes cluster within species rather than across taxa, indicating repeated independent origins rather inheritance from a common ancestor. To characterize the evolutionary consequences of this duplication, we integrated transcriptomics from six tissues with weighted gene co-expression and comparative protein clustering. We identified extensive structural divergence among duplicated copies of REST and NOA1, including domain losses, truncations, and expression partitioning across tissues, consistent with functional divergence following duplication. Comparative analyses revealed substantial remodeling of immune-related genes in bison, including BOLA class I molecules, T-cell receptor genes, leukocyte immunoglobulin-like receptors, and regulators of immune signaling. These modifications included domain rearrangements, novel sequence insertions, and lineage-specific duplications associated with immune-related expression networks. Together, these findings identify the REST-NOA1 locus as a recurrent hotspot of segmental duplication in ungulates and demonstrate how repeated duplication, structural divergence, and regulatory partitioning contribute to genome evolution. These results suggest that immune system diversification in bison and related species has been shaped not only by sequence evolution but also by recurrent remodeling of regulatory pathways and antigen-recognition pathways.

Pathogenesis inflicted by Entamoeba histolytica causes amoebic diarrhea and liver abscesses and is one of the leading causes of mortality from parasitic disease worldwide. Preventive therapeutics in the form of a vaccine could be highly effective at providing umbrella protection for a vulnerable community. In this study, a group of ten putative hypothetical surface N-linked glycoproteins was examined to assess their potential as vaccine candidates and/or diagnostic markers against amoebic intestinal colitis and liver abscesses. To evaluate the immunogenicity of putative surface glycoproteins, we used Entamoeba histolytica-infected patients sera from Bangladesh and then assessed the titer of antibody these glycoproteins elicited in patients by enzyme-linked immunosorbent assay (ELISA) and immunoblot. Based on this study, eight of ten surface glycoproteins were found immunogenic, as specific antibodies against these glycoproteins were detected in patients sera. Three of the immunogenic glycoproteins showed strong IgG antibody responses in both patients with intestinal amoebiasis and those with liver abscess. On the other hand, the other two glycoproteins showed the presence of specific serum antibodies exclusively in patients with amoebic liver abscesses, not in individuals with amoebic colitis. The remaining two glycoproteins showed more specific sera antibodies against ALA, but the preference was not very distinct. Immunolocalization with a specific antibody against the most immunogenic glycoproteins further confirmed their presence in the cell membrane. This differential immunogenicity of these glycoproteins in the two groups of patients qualifies them to become prospective sera-based diagnostic markers and also has the potential to become vaccine candidates for amoebiasis protection.

Naturally occurring variation in the bovine mannose receptor C-type 1 gene (MRC1) may shape macrophage responses to Mycobacterium (M.) bovis, a key driver of bovine tuberculosis (bTB). We identified four coding region SNPs in MRC1 across Bos taurus (Holstein Friesian, Brown Swiss) and Bos indicus (Boran, Sahiwal) cattle breeds, including a non-synonymous variant, rs380943118 (c.2963G>A; Ser988Asn) in C-type lectin-like domain (CTLD) 6, most prevalent in Sahiwal cattle. Structural modelling suggested that the S988N substitution, which is spatially separated from the monosaccharide binding site of CTLD4, might indirectly affect glycan binding, perhaps through a conformational change in the receptor. Monocyte-derived macrophages upregulated MR expression during differentiation, with heterozygous (G/A) animals showing higher MR expression and increased uptake of GFP-M. bovis BCG, although differences were not statistically significant. Anti-CD206 blockade did not inhibit BCG internalization, either indicating that this specific antibody did not bind to a CTLD involved in ligand binding or that MR is not the sole entry receptor. These results highlight naturally occurring MRC1 polymorphisms that may influence MR structure and macrophage function, providing a foundation for future studies to assess their role in bTB susceptibility.

Introduction: How much of the variable (V) and joining (J) gene identity of a T-cell receptor is recoverable from its third complementarity-determining region (CDR3) amino-acid sequence alone? Immune repertoire studies often report the CDR3 with V and J annotation that is missing, low-confidence, or inconsistent, so what the CDR3 alone can and cannot fix is both a basic question about the receptor and a practical one for reading those repertoires. Methods: For each of 118,096 pooled human rearrangements (37,687 and 80,409 {beta}) we computed the posterior distribution over candidate genes under a generative model of V(D)J recombination and under its post-selection counterpart, and measured recoverability by conditional entropy, the candidate-list size needed to contain the annotated gene, the fraction of sequences admitting a high-confidence single-gene call, and the structure of gene-by-gene confusion. Results: The J gene was nearly determined by the CDR3 in both chains. The V gene was only partially recoverable, and behaved as a group rather than a gene: junctional trimming and non-templated insertion, together with the loss of synonymous codon information in translation, leave sets of mutually confusable V genes whose grouping departs sharply from germline family nomenclature (adjusted Rand index 0.05 for and 0.21 for {beta}). Selection sharpened the V posterior modestly (usage-controlled entropy shift -0.06 nats for and -0.28 for {beta}) and redistributed which V gene was most probable, a locus-scale rewrite in {beta} against a mild reweight in . Both the recoverability measurements and the confusion grouping reproduced in two held-out tumor cohorts. Discussion: V identity is an emergent, system-level property of the repertoire, set jointly by recombination and selection and invisible in any single rearrangement, so it should be reported as a calibrated group rather than a single gene. We also release the pipeline with a computational tool which can output a set of candidate genes with confidence values given a CDR3 sequence.

Production of aberrant glycans by cancer cells constitutes a key immunosuppressive strategy to avoid destruction by immune cells. Although sialic acid-containing glycans are known to dampen the activation of lymphocytes, including Natural Killer (NK) cells, the role of fucose-containing glycans remains poorly characterized. In this work, we explored the role of Lewis X (LeX) in cancer cell-NK cell interactions. We induced ectopic expression of FUT9, an 1-3/4-fucosyltransferase, in two colorectal cancer cell lines and showed this enzyme only synthesized LeX structures but not sialyl-LeX. FUT9 introduction was not associated with altered MHC class I surface expression, nor with CD2 (which has been proposed as a receptor for LeX) binding to cancer cells. By inhibiting fucosylation we could demonstrate that CD2 binding was furthermore independent of surface fucosylated glycans in three independent cell lines. Lastly, FUT9/LeX had a limited role in cancer cell destruction and expression of activation markers by NK cells. Overall, our study suggests that, unlike sialylated glycans, 1-3/4-fucosylated glycans have limited impact on cancer cell evasion of NK cell-mediated destruction.

Sensory systems, built around specialized cell types, are central to how animals perceive and respond to their environments. Yet many of the molecular components defining these systems predate the origin of animal multicellularity. Among these, transient receptor potential (TRP) channels form a polymodal and evolutionarily ancient superfamily of ion channels involved in diverse sensory processes. To better understand how sensory complexity emerged in animals, we investigated the diversity of TRP channels in choanoflagellates, the closest living relatives of animals. Using a combination of homology-based searches, phylogenetics, and structural predictions, we find extensive TRP channel repertoires across choanoflagellates, including representatives of most major animal TRP channel families. Comparative analyses across species revealed two distinct evolutionary patterns for TRP channel families: conserved, low-copy families with stable domain architectures, and lineage-specific expansions within the families TRPM and TRPW, indicative of functional diversification. Functional insights from fluorescent localization studies in the choanoflagellate Salpingoeca rosetta demonstrated that TRPA, TRPC, and TRPV channels are spatially segregated within the collar complex, a key interface for environmental sensing and feeding. Distinct localization domains, along with evidence for heteromeric interactions between TRPA paralogs, suggest that subcellular organization likely contributes to sensory specialization in these single cells. Together, our findings indicate that a diverse and functionally versatile TRP channel toolkit was already present in the last common ancestor of choanoflagellates and animals. We propose that the evolution of animal sensory systems involved both expansion and reorganization of this ancestral repertoire, with subcellular patterning in unicellular organisms representing a precursor to cell-type specialization in multicellular animals.

The natural vector method is an important method for the analysis of biological sequences. In this study, we applied this method to population genetic analysis, with the core purpose of using it to evaluate the characteristics of a set of sequences rather than just pairwise comparison. We used the mitochondrial genome dataset from the human 1000 Genomes Project as a dataset to verify the feasibility of this improved natural vector method. The results showed that the modified natural vector method could be used for various population genetic approaches at least in the sense of population average, including the calculation of principal component analysis, population structure analysis and genetic diversity parameters. The results were in good agreement with those based on traditional molecular genetic markers such as SNP. The new method validates the feasibility of natural vector method for population genetic analysis and provides a framework for the application of matchless pair method to population genomic analysis on a wider scale.

The European flat oyster (Ostrea edulis), like numerous other oyster species, has been exploited for millennia and cultivated and translocated for centuries. Following a severe population decline, and in the context of ongoing conservation and restoration programs, genetic considerations must now be addressed to avoid mistakes. The objective of our study was to complement population genetic studies conducted at various scales along European coasts. Our sampling primarily targeted the French Atlantic, English Channel, and Mediterranean coasts, aiming to provide a fine-scale genetic characterization of populations in these regions. By integrating SNP array and low-coverage sequencing datasets, we obtained a comprehensive overview of the population genetic structure of Ostrea edulis across western Europe. Most previously identified clusters in Western Europe were confirmed. In France, populations assigned to these clusters exhibited notable within-patch homogeneity. However, two key findings emerged: (1) an extensive overlap zone between the Atlantic and western Mediterranean clusters, spanning at least from southern Portugal to southern France, and (2) the detection of a novel, clearly distinct cryptic cluster east of the English Channel, whose geographic range remains to be better delineated. These insights are critical for informing management decisions, particularly as restoration and conservation plans are currently being implemented across the species range.

Gene model for the ortholog of tango (tgo) in the May 2011 (Broad dper_caf1/DperCAF1) Genome Assembly (GenBank Accession: GCA_000005195.1) of Drosophila persimilis. This ortholog was characterized as part of a developing dataset to study the evolution of the Insulin/insulin-like growth factor signaling pathway (IIS) across the genus Drosophila using the Genomics Education Partnership gene annotation protocol for Course-based Undergraduate Research Experiences.

Genetic screens in immune cells enable the systematic interrogation of gene function at scale, uncovering key regulators of cell functions such as tumor cell killing and persistence. However, existing datasets typically focus on specific biological questions, employ targeted gene panels, are generated under diverse experimental conditions, and are not readily accessible, which together limit their integration and future usability. To address this, we developed the Functional Immunogenomics and Transcriptomics Database (FITdb), a freely accessible resource that harmonizes functional genomics datasets for the study of immune cell biology. FITdb currently integrates 43 independent functional genetics screens, including 32 pooled and 11 single-cell screens, spanning 20, 696 mouse genes and 22, 293 human genes across 199 immune cell types and conditions. All datasets are uniformly re-analyzed to enable cross-study comparisons. FITdb provides intuitive, gene-centric visualizations, detailed exploration of individual screens, and access to sgRNA-level data. Additionally, built-in tools such as "Compare MyGeneSet" and "Compare MyScreen" identify statistically significant overlaps between user-defined gene lists and functional gene sets in FITdb, and enable direct comparison of user-generated screening data with existing datasets, respectively. Together, FITdb provides a comprehensive, user-friendly platform for accelerating the discovery of immune regulatory programs. The database is freely available at https://fitdb.lji.org. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/741304v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@17ce74borg.highwire.dtl.DTLVardef@134efbdorg.highwire.dtl.DTLVardef@6787deorg.highwire.dtl.DTLVardef@1090007_HPS_FORMAT_FIGEXP M_FIG C_FIG

Adaptation of organisms to extreme environments requires dramatic phenotypic changes. Studying these changes can elucidate mechanisms underlying phenotypic differences in the context of both evolution and human disease. The Mexican tetra, Astyanax mexicanus, is a powerful model of extreme adaptation over a short evolutionary time scale. This fish species includes surface- and cave-dwelling ecotypes, with cavefish displaying many adaptations to subterranean life, including behavioral changes such as sleep loss, increased appetite, and reduced aggression. Unraveling the mechanisms underlying these changes has been challenging, presumably because they are complex traits that required coordinated changes across multiple cell types to evolve. Here, we present a spatially integrated comparative cell atlas of whole adult brains of surface and cavefish. After establishing the molecular signatures of 35 cell types, we show that cave colonization drove canalized regulatory changes to gene expression across diverse cell types. Cavefish brains show shifts in cell-type composition compared to their surface counterparts, as well as complex regulatory changes to pathways governing hypoxia response and circadian rhythm. Microglia in the cavefish brain underwent extensive transcriptional remodelling, including changes in senescence and AMPK pathways. Further, cell-cell communication analysis identified a cave-enriched ligand-receptor communication pattern centered on signals sent from glial cells to diverse populations of neurons. This atlas identifies genetic changes associated with neural and behavioral evolution and provides a resource for mechanistic studies examining brain evolution.

Background and objectivesMyasthenia gravis associated with antibodies against muscle-specific kinase (MuSK-MG) is a well-characterized IgG4-autoimmune disease, however, the mechanisms driving IgG4 predominance remain poorly understood. This study investigated whether promoter DNA methylation of cytokine genes involved in IgG4 class switching is associated with this immune response. MethodsPeripheral blood mononuclear cells were isolated from MuSK-MG patients (n=36), acetylcholine receptor myasthenia gravis (AChR-MG) patients as disease controls (n=7), and sex-matched healthy controls (n=12). Promoter DNA methylation of IL4, IL10, and IL13 was assessed by methylation-sensitive high-resolution melting and relative cytokine mRNA expression by qPCR. Associations with clinical variables, and antibody levels were subsequently evaluated. ResultsMuSK-MG patients showed lower median IL13 promoter methylation compared with healthy controls (p = 0.004). Median IL4 promoter methylation was also reduced in MuSK-MG compared with healthy controls (p < 0.001) and AChR-MG disease controls (p < 0.001), whereas no differences were observed for IL10 promoter methylation. Relative mRNA expression of IL4 (p = 0.0005), IL10 (p = 0.0462), and IL13 (p = 0.0002) was increased in MuSK-MG compared with AChR-MG. Compared with healthy controls, only IL4 expression remained significantly increased (p < 0.0001). Promoter methylation was inversely correlated with relative mRNA expression for IL4 (p < 0.0001), while IL13 showed a similar but non-significant trend (p = 0.054), no association was observed for IL10. Multivariable analysis demonstrated that treatment at sampling was independently associated with lower IL10 and IL13 promoter methylation, whereas no associations were observed with age, sex, disease phase, or disease duration. Promoter methylation did not correlate with total serum IgG4 or anti-MuSK IgG4 levels. DiscussionMuSK-MG is associated with selective hypomethylation of IL4 and IL13 promoters accompanied by increased cytokine gene expression, while IL10 promoter methylation remains unchanged. The association between treatment and IL10 and IL13 promoter methylation suggests that immunosuppressive therapy may influence epigenetic regulation in MuSK-MG. Together, these findings support a role for epigenetic dysregulation of Th2-associated cytokines in the immunological environment associated with IgG4 subclass switch. To our knowledge, this is the first study investigating IL4, IL10, and IL13 promoter DNA methylation in MuSK-MG.