Project description:Alzheimer’s disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. Here, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the role of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss. In an AD-related mouse model expressing APOE4, XY sex chromosomes heightened interferon response and tau-induced demyelination. The X-linked gene Toll-like receptor 7 (Tlr7) regulated sex-specific interferon response to myelin. Deletion of Tlr7 dampened sex differences while protecting against demyelination. Administering TLR7 inhibitor mitigated tau-induced motor impairment and demyelination in male mice, indicating that Tlr7 plays a role in the male-biased IFN-I response in aging- and AD-related demyelination.
Project description:Alzheimer’s disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. Here, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the role of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss. In an AD-related mouse model expressing APOE4, XY sex chromosomes heightened interferon response and tau-induced demyelination. The X-linked gene Toll-like receptor 7 (Tlr7) regulated sex-specific interferon response to myelin. Deletion of Tlr7 dampened sex differences while protecting against demyelination. Administering TLR7 inhibitor mitigated tau-induced motor impairment and demyelination in male mice, indicating that Tlr7 plays a role in the male-biased IFN-I response in aging- and AD-related demyelination.
Project description:Alzheimer’s disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. Here, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the role of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss. In an AD-related mouse model expressing APOE4, XY sex chromosomes heightened interferon response and tau-induced demyelination. The X-linked gene Toll-like receptor 7 (Tlr7) regulated sex-specific interferon response to myelin. Deletion of Tlr7 dampened sex differences while protecting against demyelination. Administering TLR7 inhibitor mitigated tau-induced motor impairment and demyelination in male mice, indicating that Tlr7 plays a role in the male-biased IFN-I response in aging- and AD-related demyelination.
2024-11-29 | GSE282130 | GEO
Project description:Tlr7 Drives Sex Differences in Age- and AD-related Demyelination
Project description:Aging and sex are major risk factors for developing late-onset Alzheimer’s disease. Compared to men, women are not only nearly twice as likely to develop Alzheimer’s, but they also experience worse neuropathological burden and cognitive decline despite living longer with the disease. It remains unclear how and when sex differences in biological aging emerge and contribute to Alzheimer’s disease pathogenesis. We hypothesized that these differences lead to distinct molecular Alzheimer’s disease signatures in males and females, which could be harnessed for therapeutic and biomarker development. We aged male and female, 3xTg-AD and B6129 control mice across their respective lifespans while longitudinally collecting brain samples. We conducted RNA sequencing analysis on bulk brain tissue and examined differentially expressed genes between 3xTg-AD and B6129 samples and across ages in each sex. 3xTg-AD males experienced an accelerated upregulation of immune-related gene expression in the brain relative to females, especially in genes involved in complement system activation, suggesting distinct inflammatory disease trajectories between the sexes. Our data demonstrate that chronic inflammation and complement activation are associated with increased mortality, revealing that age-related changes in immune response act as a primary driver of sex differences in Alzheimer’s disease trajectories.
Project description:Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized by chronic inflammation of exocrine tissue, resulting in loss of tears and saliva. Patients also experience many extra-glandular disease manifestations. Treatment for pSS is palliative, and there are currently no treatments available that target disease etiology. Previous studies in our lab demonstrated that Myd88 is crucial for pSS pathogenesis in the NOD.B10Sn-H2b (NOD.B10) pSS mouse model, although the way in which Myd88-dependent pathways become activated in disease remains unknown. Based on its importance in other autoimmune diseases, we hypothesized that TLR7 activation accelerates pSS pathogenesis. We administered the TLR7 agonist Imiquimod (Imq) or sham treatment to pre-disease NOD.B10 females for 6 weeks. Parallel experiments were performed in age and sex-matched C57BL/10 controls. Imq-treated pSS animals exhibited cervical lymphadenopathy, splenomegaly, and expansion of TLR7-expressing B cells. Robust lymphocytic infiltration of exocrine tissues, kidney and lung was observed in pSS mice following treatment with Imq. TLR7 agonism also induced salivary hypofunction in pSS mice, which is a hallmark of disease. Anti-nuclear autoantibodies, including Ro (SSA) and La (SSB) were increased in pSS mice following Imq administration. Cervical lymph nodes from Imq-treated NOD.B10 animals demonstrated an increase in the percentage of activated/memory CD4+ T cells. Finally, aged-associated B cells (ABCs) were expanded in the spleens of Imq-treated pSS mice. Thus, activation of TLR7 accelerates local and systemic disease and promotes expansion of the ABC subset in pSS.
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:While circumstantial evidence supports enhanced TLR7 signaling as a mechanism of human systemic autoimmune disease, we have lacked the proof afforded by lupus-causing TLR7 gene variants. Here we undertook a whole exome sequencing (WES) approach to identify novel TLR7 variants in human lupus patients. We establish the importance of TLR7 for human SLE pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.
Project description:UNC93B1 is critical for trafficking and function of nucleic acid-sensing Toll-like receptors (TLRs) TLR3, TLR7, TLR8, and TLR9, which are essential for antiviral immunity. Overactive TLR7 signaling induced by recognition of self-nucleic acids has been implicated in systemic lupus erythematosus (SLE). Here, we report UNC93B1 variants (E92G and R336L) in four patients with early-onset SLE. Patient cells or mouse macrophages carrying the UNC93B1 variants produced high amounts of TNF-α and IL-6 and upon stimulation with TLR7/TLR8 agonist, but not with TLR3 or TLR9 agonists. E92G causes UNC93B1 protein instability and reduced interaction with TLR7, leading to selective TLR7 hyperactivation with constitutive type I IFN signaling. Thus, UNC93B1 regulates TLR subtype-specific mechanisms of ligand recognition. Our findings establish a pivotal role for UNC93B1 in TLR7-dependent autoimmunity and highlight the therapeutic potential of targeting TLR7 in SLE.