A genetic locus complements resistance to Bordetella pertussis-induced histamine sensitization.

Histamine plays pivotal role in normal physiology and dysregulated production of histamine or signaling through histamine receptors (HRH) can promote pathology. Previously, we showed that Bordetella pertussis or pertussis toxin can induce histamine sensitization in laboratory inbred mice and is genetically controlled by Hrh1/HRH1. HRH1 allotypes differ at three amino acid residues with P263-V313-L331 and L263-M313-S331, imparting sensitization and resistance respectively. Unexpectedly, we found several wild-derived inbred strains that carry the resistant HRH1 allotype (L263-M313-S331) but exhibit histamine sensitization. This suggests the existence of a locus modifying pertussis-dependent histamine sensitization. Congenic mapping identified the location of this modifier locus on mouse chromosome 6 within a functional linkage disequilibrium domain encoding multiple loci controlling sensitization to histamine. We utilized interval-specific single-nucleotide polymorphism (SNP) based association testing across laboratory and wild-derived inbred mouse strains and functional prioritization analyses to identify candidate genes for this modifier locus. Atg7, Plxnd1, Tmcc1, Mkrn2, Il17re, Pparg, Lhfpl4, Vgll4, Rho and Syn2 are candidate genes within this modifier locus, which we named Bphse, enhancer of Bordetella pertussis induced histamine sensitization. Taken together, these results identify, using the evolutionarily significant diversity of wild-derived inbred mice, additional genetic mechanisms controlling histamine sensitization.

T Cell Receptor Genotype and Ubash3a Determine Susceptibility to Rat Autoimmune Diabetes.

Genetic analyses of human type 1 diabetes (T1D) have yet to reveal a complete pathophysiologic mechanism. Inbred rats with a high-risk class II major histocompatibility complex (MHC) haplotype (RT1B/Du) can illuminate such mechanisms. Using T1D-susceptible LEW.1WR1 rats that express RT1B/Du and a susceptible allele of the Ubd promoter, we demonstrate that germline knockout of Tcrb-V13S1A1, which encodes the Vß13a T cell receptor ß chain, completely prevents diabetes. Using the RT1B/Du-identical LEW.1W rat, which does not develop T1D despite also having the same Tcrb-V13S1A1 ß chain gene but a different allele at the Ubd locus, we show that knockout of the Ubash3a regulatory gene renders these resistant rats relatively susceptible to diabetes. In silico structural modeling of the susceptible allele of the Vß13a TCR and its class II RT1u ligand suggests a mechanism by which a germline TCR ß chain gene could promote susceptibility to T1D in the absence of downstream immunoregulation like that provided by UBASH3A. Together these data demonstrate the critical contribution of the Vß13a TCR to the autoimmune synapse in T1D and the regulation of the response by UBASH3A. These experiments dissect the mechanisms by which MHC class II heterodimers, TCR and regulatory element interact to induce autoimmunity.

The Vbeta13 T Cell Receptor Monoclonal Antibody Reduces Hyaluronan and CD68+, CD3+, and CD8+ Cell Infiltrations to Delay Diabetes in Congenic BB DRLyp/Lyp Rats.

The depleting Vß13a T cell receptor monoclonal antibody (mAb) 17D5 prevents both induced and spontaneous autoimmune diabetes in BB rats. Here it was tested in congenic DRLyp/Lyp rats, all of which spontaneously developed diabetes. Starting at 40 days of age, rats were injected once weekly with either saline, His42 Vß16 mAb, or 17D5 mAb and monitored for hyperglycemia. Diabetes occurred in 100% (n = 5/5) of saline-treated rats (median age, 66 days; range 55-73), and in 100% (n = 6/6) of His42-treated rats (median age, 69 days; range 59-69). Diabetes occurred in fewer (n = 8/11, 73%) 17D5-treated rats at a later age (median 76 days, range 60-92). Three (27%) of the 17D5-treated rats were killed at 101-103 days of age without diabetes (17D5 no-diabetes rats). Survival analysis demonstrated that 17D5 mAb delayed diabetes onset. Saline- and His42-treated rats had severely distorted islets with substantial loss of insulin-positive cells. These rats exhibited prominent hyaluronan (HA) staining, with the intra-islet HA+ accumulations measuring 5,000 ± 2,400 µm2 and occupying 36 ± 12% of islet area, and severe (grade 4) insulitis with abundant infiltration by CD68+, CD3+, and CD8+ cells. The 17D5 mAb-treated rats with delayed diabetes onset exhibited less severe insulitis (predominantly grade 3). In contrast, the 17D5 no-diabetes rats had mostly normal islets, with insulin+ cells representing 76 ± 3% of islet cells. In these rats, the islet HA deposits were significantly smaller than in the diabetic rats; the intra-islet HA+ areas were 1,200 ± 300 µm2 and accounted for 8 ± 1% of islet area. Also, islet-associated CD68+ and CD3+ cells occurred less frequently (on average in 60 and 3% of the islets, respectively) than in the diabetes rats (present in >95% of the islets). No CD8+ cells were detected in islets in all 17D5 no-diabetes rats. We conclude that mAb 17D5 delayed diabetes in DRLyp/Lyp rats and markedly reduced expression of HA and concomitant infiltration of CD68+, CD3+, and CD8+ cells. Our findings underscore the importance of refining immune suppression in prevention or intervention clinical trials to use mAb reagents that are directed against specific T cell receptors.

PEGylation enables subcutaneously administered nanoparticles to induce antigen-specific immune tolerance.

The development of nanomaterials to induce antigen-specific immune tolerance has shown promise for treating autoimmune diseases. While PEGylation has been widely used to reduce host immune responses to nanomaterials, its tolerogenic potential has not been reported. Here, we report for the first time that a subcutaneous injection of PEGylated poly(lactide-co-glycolide) (PLGA) nanoparticles containing auto-antigen peptide MOG35-55 without any tolerogenic drugs is sufficient to dramatically ameliorate symptoms after disease onset in an antigen-specific manner in a mouse model of multiple sclerosis. Neither free MOG35-55 nor particles without PEG exhibit this efficacy. Interestingly, mechanistic studies indicate that PEGylation of nanoparticles does not reduce dendritic cell activation through direct nanoparticle-cell interactions. Instead, PEGylated nanoparticles induce lower complement activation, neutrophil recruitment, and co-stimulatory molecule expression on dendritic cells around the injection sitecompared to non-PEGylated PLGA nanoparticles, creating a more tolerogenic microenvironment in vivo. We further demonstrate that the locally recruited dendritic cells traffic to lymphoid organs to induce T cell tolerance. These results highlight the critical role of surface properties of nanomaterials in inducing immune tolerance via subcutaneous administration.

Erratum: Author Correction: A natural mouse model reveals genetic determinants of systemic capillary leak syndrome (Clarkson disease).

[This corrects the article DOI: 10.1038/s42003-019-0647-4.].

A natural mouse model reveals genetic determinants of systemic capillary leak syndrome (Clarkson disease).

The systemic capillary leak syndrome (SCLS, Clarkson disease) is a disorder of unknown etiology characterized by recurrent episodes of vascular leakage of proteins and fluids into peripheral tissues, resulting in whole-body edema and hypotensive shock. The pathologic mechanisms and genetic basis for SCLS remain elusive. Here we identify an inbred mouse strain, SJL, which recapitulates cardinal features of SCLS, including susceptibility to histamine- and infection-triggered vascular leak. We named this trait "Histamine hypersensitivity" (Hhs/Hhs) and mapped it to Chromosome 6. Hhs is syntenic to the genomic locus most strongly associated with SCLS in humans (3p25.3), revealing that the predisposition to develop vascular hyperpermeability has a strong genetic component conserved between humans and mice and providing a naturally occurring animal model for SCLS. Genetic analysis of Hhs may reveal orthologous candidate genes that contribute not only to SCLS, but also to normal and dysregulated mechanisms underlying vascular barrier function more generally.

Network-Based Functional Prediction Augments Genetic Association To Predict Candidate Genes for Histamine Hypersensitivity in Mice.

Genetic mapping is a primary tool of genetics in model organisms; however, many quantitative trait loci (QTL) contain tens or hundreds of positional candidate genes. Prioritizing these genes for validation is often ad hoc and biased by previous findings. Here we present a technique for prioritizing positional candidates based on computationally inferred gene function. Our method uses machine learning with functional genomic networks, whose links encode functional associations among genes, to identify network-based signatures of functional association to a trait of interest. We demonstrate the method by functionally ranking positional candidates in a large locus on mouse Chr 6 (45.9 Mb to 127.8 Mb) associated with histamine hypersensitivity (Histh). Histh is characterized by systemic vascular leakage and edema in response to histamine challenge, which can lead to multiple organ failure and death. Although Histh risk is strongly influenced by genetics, little is known about its underlying molecular or genetic causes, due to genetic and physiological complexity of the trait. To dissect this complexity, we ranked genes in the Histh locus by predicting functional association with multiple Histh-related processes. We integrated these predictions with new single nucleotide polymorphism (SNP) association data derived from a survey of 23 inbred mouse strains and congenic mapping data. The top-ranked genes included Cxcl12, Ret, Cacna1c, and Cntn3, all of which had strong functional associations and were proximal to SNPs segregating with Histh. These results demonstrate the power of network-based computational methods to nominate highly plausible quantitative trait genes even in challenging cases involving large QTL and extreme trait complexity.

Genetic Variation Within the HLA-DRA1 Gene Modulates Susceptibility to Type 1 Diabetes in HLA-DR3 Homozygotes.

Type 1 diabetes (T1D) involves the interaction of multiple gene variants, environmental factors, and immunoregulatory dysfunction. Major T1D genetic risk loci encode HLA-DR and -DQ. Genetic heterogeneity and linkage disequilibrium in the highly polymorphic HLA region confound attempts to identify additional T1D susceptibility loci. To minimize HLA heterogeneity, T1D patients (N = 365) and control subjects (N = 668) homozygous for the HLA-DR3 high-risk haplotype were selected from multiple large T1D studies and examined to identify new T1D susceptibility loci using molecular inversion probe sequencing technology. We report that risk for T1D in HLA-DR3 homozygotes is increased significantly by a previously unreported haplotype of three single nucleotide polymorphisms (SNPs) within the first intron of HLA-DRA1. The homozygous risk haplotype has an odds ratio of 4.65 relative to the protective homozygous haplotype in our sample. Individually, these SNPs reportedly function as "expression quantitative trait loci," modulating HLA-DR and -DQ expression. From our analysis of available data, we conclude that the tri-SNP haplotype within HLA-DRA1 may modulate class II expression, suggesting that increased T1D risk could be attributable to regulated expression of class II genes. These findings could help clarify the role of HLA in T1D susceptibility and improve diabetes risk assessment, particularly in high-risk HLA-DR3 homozygous individuals.

A new class of biological materials: Cell membrane-derived hydrogel scaffolds.

Biological materials are superior to synthetic biomaterials in biocompatibility and active interactions with cells. Here, a new class of biological materials, cell membrane-derived hydrogel scaffolds are reported for harnessing these advantages. To form macroporous scaffolds, vesicles derived from red blood cell membranes (RBCMs) are chemically crosslinked via cryogelation. The RBCM scaffolds with a pore size of around 70 µm are soft and injectable. Highly biocompatible scaffolds are typically made of superhydrophilic polymers and lack the ability to encapsulate and release hydrophobic drugs in a controlled manner. However, hydrophobic molecules can be efficiently encapsulated inside RBCM scaffolds and be sustainedly released. RBCM scaffolds show low neutrophil infiltration after subcutaneous injection in mice, and a significantly higher number of infiltrated macrophages than methacrylate alginate (MA-alginate) scaffolds. According to gene expression and surface markers, these macrophages have an M2-like phenotype, which is anti-inflammatory and immune suppressive. There are also higher percentages of macrophages presenting immunosuppressive PD-L1 in RBCM-scaffolds than in MA-alginate scaffolds. Interestingly, the concentrations of anti-inflammatory cytokine, IL-10 in both types of scaffolds are higher than those in normal organ tissues. This study sheds light on cell membrane-derived hydrogels, which can actively modulate cells in unique ways unavailable to existing hydrogel scaffolds.

Identification of Optimal Mouse Models of Systemic Sclerosis by Interspecies Comparative Genomics.

OBJECTIVE: Understanding the pathogenesis of systemic sclerosis (SSc) is confounded by considerable disease heterogeneity. Animal models of SSc that recapitulate distinct subsets of disease at the molecular level have not been delineated. We applied interspecies comparative analysis of genomic data from multiple mouse models of SSc and patients with SSc to determine which animal models best reflect the SSc intrinsic molecular subsets. METHODS: Gene expression measured in skin from mice with sclerodermatous graft-versus-host disease (GVHD), bleomycin-induced fibrosis, Tsk1/+ or Tsk2/+ mice was mapped to human orthologs and compared to SSc skin biopsy-derived gene expression. Transforming growth factor ß (TGFß) activation was assessed using a responsive signature in mice, and tumor necrosis factor receptor superfamily member 12A (TNFRSF12A) expression was measured in SSc patient and mouse skin. RESULTS: Gene expression in skin from mice with sclerodermatous GVHD and bleomycin-induced fibrosis corresponded to that in SSc patients in the inflammatory molecular subset. In contrast, Tsk2/+ mice showed gene expression corresponding to the fibroproliferative SSc subset. Enrichment of a TGFß-responsive signature was observed in both Tsk2/+ mice and mice with bleomycin-induced skin fibrosis. Expression of TNFRSF12A (the TWEAK receptor/fibroblast growth factor-inducible 14) was elevated in skin from patients with fibroproliferative SSc and the skin of Tsk2/+ mice. CONCLUSION: This study reveals similarities in cutaneous gene expression between distinct mouse models of SSc and specific molecular subsets of the disease. Different pathways underlie the intrinsic subsets including TGFß, interleukin-13 (IL-13), and IL-4. We identify a novel target, Tnfrsf12a, with elevated expression in skin from patients with fibroproliferative SSc and Tsk2/+ mice. These findings will inform mechanistic and translational preclinical studies in SSc.

Copy number variation in Y chromosome multicopy genes is linked to a paternal parent-of-origin effect on CNS autoimmune disease in female offspring.

BACKGROUND: The prevalence of some autoimmune diseases is greater in females compared with males, although disease severity is often greater in males. The reason for this sexual dimorphism is unknown, but it may reflect negative selection of Y chromosome-bearing sperm during spermatogenesis or male fetuses early in the course of conception/pregnancy. Previously, we showed that the sexual dimorphism in experimental autoimmune encephalomyelitis (EAE) is associated with copy number variation (CNV) in Y chromosome multicopy genes. Here, we test the hypothesis that CNV in Y chromosome multicopy genes influences the paternal parent-of-origin effect on EAE susceptibility in female mice. RESULTS: We show that C57BL/6 J consomic strains of mice possessing an identical X chromosome and CNV in Y chromosome multicopy genes exhibit sperm head abnormalities and female-biased sex ratio. This is consistent with X-Y intragenomic conflict arising from an imbalance in CNV between homologous X:Y chromosome multicopy genes. These males also display paternal transmission of EAE to female offspring and differential loading of microRNAs within the sperm nucleus. Furthermore, in humans, families of probands with multiple sclerosis similarly exhibit a female-biased sex ratio, whereas families of probands affected with non-sexually dimorphic autoimmune diseases exhibit unbiased sex ratios. CONCLUSIONS: These findings provide evidence for a mechanism at the level of the male gamete that contributes to the sexual dimorphism in EAE and paternal parent-of-origin effects in female mice, raising the possibility that a similar mechanism may contribute to the sexual dimorphism in multiple sclerosis.

Genetic background effects on disease onset and lifespan of the mutant dynactin p150Glued mouse model of motor neuron disease.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease primarily affecting motor neurons in the central nervous system. Although most cases of ALS are sporadic, about 5-10% of cases are familial (FALS) with approximately 20% of FALS caused by mutations in the Cu/Zn superoxide dismutase (SOD1) gene. We have reported that hSOD1-G93A transgenic mice modeling this disease show a more severe phenotype when the transgene is bred on a pure SJL background and a milder phenotype when bred on a pure B6 background and that these phenotype differences link to a region on mouse Chromosome 17.To examine whether other models of motor neuron degeneration are affected by genetic background, we bred the mutant human dynactin p150Glued (G59S-hDCTN1) transgene onto inbred SJL and B6 congenic lines. This model is based on an autosomal dominant lower motor neuron disease in humans linked to a mutation in the p150Glued subunit of the dynactin complex. As seen in hSOD1-G93A mice, we observed a more severe phenotype with earlier disease onset (p<0.001) and decreased survival (p<0.00001) when the G59S-hDCTN1 transgene was bred onto the SJL background and delayed onset (p<0.0001) with increased survival (p<0.00001) when bred onto the B6 background. Furthermore, B6 mice with an SJL derived chromosome 17 interval previously shown to delay disease onset in hSOD1-G93A mice also showed delays onset in G59S-hDCTN1 mice suggesting that at least some genetic modifiers are shared. We have shown that genetic background influences phenotype in G59S-hDCTN1 mice, in part through a region of chromosome 17 similar to the G93-hSOD1 ALS mouse model. These results support the presence of genetic modifiers in both these models some of which may be shared. Identification of these modifiers will highlight intracellular pathways involved in motor neuron disease and provide new therapeutic targets that may be applicable to motor neuron degeneration.

Identification of genetic determinants of the sexual dimorphism in CNS autoimmunity.

Multiple sclerosis (MS) is a debilitating chronic inflammatory disease of the nervous system that affects approximately 2.3 million individuals worldwide, with higher prevalence in females, and a strong genetic component. While over 200 MS susceptibility loci have been identified in GWAS, the underlying mechanisms whereby they contribute to disease susceptibility remains ill-defined. Forward genetics approaches using conventional laboratory mouse strains are useful in identifying and functionally dissecting genes controlling disease-relevant phenotypes, but are hindered by the limited genetic diversity represented in such strains. To address this, we have combined the powerful chromosome substitution (consomic) strain approach with the genetic diversity of a wild-derived inbred mouse strain. Using experimental allergic encephalomyelitis (EAE), a mouse model of MS, we evaluated genetic control of disease course among a panel of 26 consomic strains of mice inheriting chromosomes from the wild-derived PWD strain on the C57BL/6J background, which models the genetic diversity seen in human populations. Nineteen linkages on 18 chromosomes were found to harbor loci controlling EAE. Of these 19 linkages, six were male-specific, four were female-specific, and nine were non-sex-specific, consistent with a differential genetic control of disease course between males and females. An MS-GWAS candidate-driven bioinformatic analysis using orthologous genes linked to EAE course identified sex-specific and non-sex-specific gene networks underlying disease pathogenesis. An analysis of sex hormone regulation of genes within these networks identified several key molecules, prominently including the MAP kinase family, known hormone-dependent regulators of sex differences in EAE course. Importantly, our results provide the framework by which consomic mouse strains with overall genome-wide genetic diversity, approximating that seen in humans, can be used as a rapid and powerful tool for modeling the genetic architecture of MS. Moreover, our data represent the first step towards mechanistic dissection of genetic control of sexual dimorphism in CNS autoimmunity.

The Tsk2/+ mouse fibrotic phenotype is due to a gain-of-function mutation in the PIIINP segment of the Col3a1 gene.

Systemic sclerosis (SSc) is a polygenic, autoimmune disorder of unknown etiology, characterized by the excessive accumulation of extracellular matrix (ECM) proteins, vascular alterations, and autoantibodies. The tight skin (Tsk)2/+ mouse model of SSc demonstrates signs similar to SSc including tight skin and excessive deposition of dermal ECM proteins. By linkage analysis, we mapped the Tsk2 gene mutation to <3 megabases on chromosome 1. We performed both RNA sequencing of skin transcripts and genome capture DNA sequencing of the region spanning this interval in Tsk2/+ and wild-type littermates. A missense point mutation in the procollagen III amino terminal propeptide segment (PIIINP) of collagen, type III, alpha 1 (Col3a1) was found to be the best candidate for Tsk2; hence, both in vivo and in vitro genetic complementation tests were used to prove that this Col3a1 mutation is the Tsk2 gene. All previously documented mutations in the human Col3a1 gene are associated with the Ehlers-Danlos syndrome, a connective tissue disorder that leads to a defect in type III collagen synthesis. To our knowledge, the Tsk2 point mutation is the first documented gain-of-function mutation associated with Col3a1, which leads instead to fibrosis. This discovery provides insight into the mechanism of skin fibrosis manifested by Tsk2/+ mice.

Tight Skin 2 Mice Exhibit Delayed Wound Healing Caused by Increased Elastic Fibers in Fibrotic Skin.

Rationale: The Tight Skin 2 (Tsk2) mouse model of systemic sclerosis (SSc) has many features of human disease, including tight skin, excessive collagen deposition, alterations in the extracellular matrix (ECM), increased elastic fibers, and occurrence of antinuclear antibodies with age. A tight skin phenotype is observed by 2 weeks of age, but measurable skin fibrosis is only apparent at 10 weeks. We completed a series of wound healing experiments to determine how fibrosis affects wound healing in Tsk2/+ mice compared with their wild-type (WT) littermates. Method: We performed these experiments by introducing four 4 mm biopsy punched wounds on the back of each mouse, ventral of the midline, and observed wound healing over 10 days. Tsk2/+ mice showed significantly delayed wound healing and increased wound size compared with the WT littermates at both 5 and 10 weeks of age. We explored the potential sources of this response by wounding Tsk2/+ mice that were genetically deficient either for the NLRP3 inflammasome (a known fibrosis mediator), or for elastic fibers in the skin, using a fibulin-5 knockout. Conclusion: We found that the loss of elastic fibers restores normal wound healing in the Tsk2/+ mouse and that the loss of the NLRP3 inflammasome had no effect. We conclude that elastic fiber dysregulation is the primary cause of delayed wound healing in the Tsk2/+ mouse and therapies that promote collagen deposition in the tissue matrix in the absence of elastin deposition might be beneficial in promoting wound healing in SSc and other diseases.

Tight skin 2 mice exhibit a novel time line of events leading to increased extracellular matrix deposition and dermal fibrosis.

The tight skin 2 (Tsk2) mouse model of systemic sclerosis (SSc) has many features of the human disease including tight skin, fibrosis, extracellular matrix abnormalities, and reported antinuclear antibodies (ANA). Here we report that Tsk2/+ mice develop excess dermal fibrosis with age, as skin is not significantly fibrotic until 10 weeks, a full eight weeks after the development of the physical tight skin phenotype. Concomitantly with the tight skin phenotype at two weeks of age, Tsk2/+ mice demonstrate increased levels of total transforming growth factor beta 1 (TGF-ß1) and excessive accumulation of dermal elastic fibers. The increase in elastic fibers is not responsible for tight skin, however, because Tsk2/+ mice genetically engineered to lack skin elastic fibers nevertheless have tight skin and fibrosis. Finally, about two months after the first measurable increases of total collagen, a portion of Tsk2/+ mice produce ANAs, but at a similar level to wild-type littermates. The timeline of disease development in the Tsk2/+ mouse shows that fibrosis is progressive, with elastic fiber alterations and TGF-ß1 over-production occurring at least two months before bona fide fibrosis, that is not dependent on ANA production.

Autoantigen-induced focusing of Vß13+ T cells precedes onset of autoimmune diabetes in the LEW.1WR1 rat.

The earliest events leading to autoimmune type 1 diabetes (T1D) are not known in any species. A T-cell receptor (TCR)-variable region, TCR-Vß13, is required for susceptibility to autoimmune diabetes in rats, and selective depletion of Vß13(+) T cells with an allele-specific monoclonal antibody prevents disease in multiple rat strains. To investigate the role of Vß13 early in diabetes, we examined islet T-cell transcripts in susceptible (LEW.1WR1) and resistant (LEW.1W and Wistar Furth) strains induced with polyinosinic:polycytidylic acid. Vß13(+) T cells displayed antigenic focusing in LEW.1WR1 islets 5 days postinduction and were characterized by a substantial decrease in complementarity determining region 3 diversity. This occurred prior to significant islet T-cell accumulation (day 7) or frank diabetes (days 10-14). Vß13(+) transcripts increased in LEW.1WR1 islets during diabetes progression, but not in resistant rats. We also analyzed transcript clonality of rat TCR-Vα5, an ortholog of the dominant TCR-Vα chain found on insulin B:9-23-reactive T cells in nonobese diabetic rat islets. We observed clonal expansion of Vα5(+) transcripts in prediabetic LEW.1WR1 islets, suggesting that rat Vα5 is also an important component of islet autoantigen recognition. These data provide additional evidence that genome-encoded TCR sequences are important determinants of genetic susceptibility to T1D.

Histamine H(3) receptor integrates peripheral inflammatory signals in the neurogenic control of immune responses and autoimmune disease susceptibility.

Histamine H(3) receptor (Hrh3/H(3)R) is primarily expressed by neurons in the central nervous system (CNS) where it functions as a presynaptic inhibitory autoreceptor and heteroreceptor. Previously, we identified an H(3)R-mediated central component in susceptibility to experimental allergic encephalomyelitis (EAE), the principal autoimmune model of multiple sclerosis (MS), related to neurogenic control of blood brain barrier permeability and peripheral T cell effector responses. Furthermore, we identified Hrh3 as a positional candidate for the EAE susceptibility locus Eae8. Here, we characterize Hrh3 polymorphisms between EAE-susceptible and resistant SJL and B10.S mice, respectively, and show that Hrh3 isoform expression in the CNS is differentially regulated by acute peripheral inflammatory stimuli in an allele-specific fashion. Next, we show that Hrh3 is not expressed in any subpopulations of the immune compartment, and that secondary lymphoid tissue is anatomically poised to be regulated by central H(3)R signaling. Accordingly, using transcriptome analysis, we show that, inflammatory stimuli elicit unique transcriptional profiles in the lymph nodes of H(3)RKO mice compared to WT mice, which is indicative of negative regulation of peripheral immune responses by central H(3)R signaling. These results further support a functional link between the neurogenic control of T cell responses and susceptibility to CNS autoimmune disease coincident with acute and/or chronic peripheral inflammation. Pharmacological targeting of H(3)R may therefore be useful in preventing the development and formation of new lesions in MS, thereby limiting disease progression.

The Y chromosome as a regulatory element shaping immune cell transcriptomes and susceptibility to autoimmune disease.

Understanding the DNA elements that constitute and control the regulatory genome is critical for the appropriate therapeutic management of complex diseases. Here, using chromosome Y (ChrY) consomic mouse strains on the C57BL/6J (B6) background, we show that susceptibility to two diverse animal models of autoimmune disease, experimental allergic encephalomyelitis (EAE) and experimental myocarditis, correlates with the natural variation in copy number of Sly and Rbmy multicopy ChrY genes. On the B6 background, ChrY possesses gene regulatory properties that impact genome-wide gene expression in pathogenic CD4(+) T cells. Using a ChrY consomic strain on the SJL background, we discovered a preference for ChrY-mediated gene regulation in macrophages, the immune cell subset underlying the EAE sexual dimorphism in SJL mice, rather than CD4(+) T cells. Importantly, in both genetic backgrounds, an inverse correlation exists between the number of Sly and Rbmy ChrY gene copies and the number of significantly up-regulated genes in immune cells, thereby supporting a link between copy number variation of Sly and Rbmy with the ChrY genetic element exerting regulatory properties. Additionally, we show that ChrY polymorphism can determine the sexual dimorphism in EAE and myocarditis. In humans, an analysis of the CD4(+) T cell transcriptome from male multiple sclerosis patients versus healthy controls provides further evidence for an evolutionarily conserved mechanism of gene regulation by ChrY. Thus, as in Drosophila, these data establish the mammalian ChrY as a member of the regulatory genome due to its ability to epigenetically regulate genome-wide gene expression in immune cells.