Oxidative Stress in Neurodegenerative Diseases: From Molecular Mechanisms to Clinical Applications

Increasing numbers of individuals, particularly the elderly, suffer from neurodegenerative disorders. These diseases are normally characterized by progressive loss of neuron cells and compromised motor or cognitive function. Previous studies have proposed that the overproduction of reactive oxygen species (ROS) may have complex roles in promoting the disease development. Research has shown that neuron cells are particularly vulnerable to oxidative damage due to their high polyunsaturated fatty acid content in membranes, high oxygen consumption, and weak antioxidant defense. However, the exact molecular pathogenesis of neurodegeneration related to the disturbance of redox balance remains unclear. Novel antioxidants have shown great potential in mediating disease phenotypes and could be an area of interest for further research. In this review, we provide an updated discussion on the roles of ROS in the pathological mechanisms of Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and spinocerebellar ataxia, as well as a highlight on the antioxidant-based therapies for alleviating disease severity

Sex-biased immunological processes drive hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition that can manifest with abscesses, sinus tracts, and scarring in the intertriginous areas of the body. HS is characterized by immune dysregulation, featuring elevated levels of myeloid cells, T helper (Th) cells, and pro-inflammatory cytokines, particularly those involved in Th1- and Th17-mediated immunity. In most epidemiological studies, HS shows a strong female sex bias, with reported female-to-male ratios estimated at roughly 3:1, suggesting that sex-related factors contribute to HS pathophysiology. In this article, we review the role of intrinsic and extrinsic factors that contribute to immunological differences between the sexes and postulate their role in the female sex bias observed in HS. We discuss the effects of hormones, X chromosome dosage, genetics, the microbiome, and smoking on sex-related differences in immunity to postulate potential immunological mechanisms in HS pathophysiology. Future studies are required to better characterize sex-biased factors that contribute to HS disease presentations

542 Murine epidermis harbors functionally distinct langerhans cell subsets

Epidermal Langerhans cells (LCs) derive from embryonic myeloid progenitors at the steady-state and monocyte progenitors under inflammatory conditions. LCs have the capacity to induce both immunity and tolerance in the skin, but how a single population of LCs mediates both these functions has perplexed researchers for decades. We hypothesized that LCs in murine epidermis have functionally heterogenous subpopulations. We employed single-cell RNA sequencing (scRNAseq) and scATACseq to identify transcriptional and epigenetic heterogeneity in LCs during late embryonic development, adult steady-state and inflamed-state. We found three transcriptionally distinct clusters in adult at steady-state: ATF3hiCD207lo (cLC1), ATF3loCD207hi (cLC2), and CD207+ cells expressing keratinocyte (KC) genes (kLCs). Ingenuity pathway analysis showed LC1 had downregulated immunostimulatory pathways and LC2 had upregulated immunostimulatory pathways. LCs from ATF3 knockout mice promoted Th1/2/17 immunity in co-culture experiments, confirming the immunotolerant function of cLC1s. cLC1 and cLC2 clusters had corresponding scATACseq clusters but kLCs did not, suggesting that kLCs may acquire their KC-“fingerprint” through interactions with KCs. scRNAseq analyses of E18.5 pre-LCs and 3 weeks post UVC-treatment also identified ATF3hi and ATF3lo clusters, but kLCs were neither present at E18.5 nor after UVC treatment. Overall, our single cell analyses uncover murine epidermal LC subsets with distinct functions during late embryonic development, steady-state and inflamed-state

Research Techniques Made Simple: Use of Imaging Mass Cytometry for Dermatological Research and Clinical Applications

Traditional immunohistochemistry (IHC) is inherently limited by its ability to analyze only several markers within a histological tissue section at a given time, which hinders in-depth characterization and phenotyping of tissues. Imaging mass cytometry (IMC), which combines IHC using metal-labeled antibodies with laser ablation and detection using mass cytometry by time-of-flight, overcomes this limitation with the capability to simultaneously analyze up to 40 protein markers to generate high-dimensional images from a single tissue section. IMC analysis preserves tissue architecture and spatial cellular relationships that would otherwise be lost or significantly altered in applications requiring tissue dissociation, such as flow cytometry or single-cell RNA sequencing. Resulting high-dimensional histological images permit spatially conserved analysis to identify unique cell populations, cellular interactions and avoidances, and insight into activation and behavioral status based on tissue location. IMC can be performed on both frozen and formalin-fixed paraffin-embedded tissue, allowing for previously banked samples to be analyzed and correlated with known clinical outcomes. Expectedly, IMC will change the landscape of investigative pathology, particularly when used in coordination with multiomic platforms to combine transcriptomic and proteomic data at a single-cell resolution. Here, we aim to highlight the potential utility of IMC within dermatologic research and clinical applications

Sex-biased immunological processes drive hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition that can manifest with abscesses, sinus tracts, and scarring in the intertriginous areas of the body. HS is characterized by immune dysregulation, featuring elevated levels of myeloid cells, T helper (Th) cells, and pro-inflammatory cytokines, particularly those involved in Th1- and Th17-mediated immunity. In most epidemiological studies, HS shows a strong female sex bias, with reported female-to-male ratios estimated at roughly 3:1, suggesting that sex-related factors contribute to HS pathophysiology. In this article, we review the role of intrinsic and extrinsic factors that contribute to immunological differences between the sexes and postulate their role in the female sex bias observed in HS. We discuss the effects of hormones, X chromosome dosage, genetics, the microbiome, and smoking on sex-related differences in immunity to postulate potential immunological mechanisms in HS pathophysiology. Future studies are required to better characterize sex-biased factors that contribute to HS disease presentations

Mass Cytometry profiling of the peripheral blood immunome in patients with psoriasis and psoriatic arthritis uncovers potential biomarkers related to disease progression

Cutaneous psoriasis (PsC) is an auto-immune disorder affecting 60 million people globally, among 30% of whom progress to psoriatic arthritis (PsA), a disease with poorly understood etiology, making diagnosis and treatment difficult. Indeed, a complete systemic immune profile of PsA has yet to be performed. In the study herein, we collected peripheral blood samples from patients with PsC, PsA with or without systemic therapy, and healthy controls (HC), and utilized mass cytometry by time of flight (CyTOF) to acquire immune cell profiles of major leukocyte subsets. We found that patients with PsC and/or PsA exhibited increased frequencies of intermediate (CD14+CD16+) and nonclassical (CD14-CD16+) monocytes as well as regulatory T cells. Separation of our heterogenous patient population revealed distinct immune profiles according to ethnicity and sex in patient groups. Analysis of homing markers revealed upregulation of CCR4, CCR7, and CXCR3 on Classical Monocytes and/or Naïve CD8+ T cells in PsC and/or PsA patients. Moreover, analysis of functional markers revealed upregulation of CD38, CD28, and CD25 on Tregs and EM CD4+ T cells in PsC and/or PsA patients. Unbiased machine learning algorithms (CITRUS) revealed upregulation of Classical Monocytes in PsC and PsA compared to HC patients. Lastly, CITRUS revealed upregulated Intermediate Monocytes in PsA compared to PsC patients, and upregulated Classical Monocytes in treated PsA compared to untreated PsA patients. Therefore, we provide a comprehensive profile of immune cell population frequencies and phenotypes in patients with PsC and PsA, highlighting Monocytes and Tregs as potential biomarkers for early diagnosis of PsA

Insights from γ-Secretase: Functional Genetics of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, relapsing, and remitting inflammatory disease of the skin with significant heritability and racial disposition. The pathogenesis of HS remains enigmatic, but occlusion of the terminal hair follicle and dysregulation of the local innate immune response may contribute to pathogenesis. Genetic predisposition might also contribute to disease susceptibility and phenotypic heterogeneity because mutations in γ-secretase have been found to underlie a minor but characteristic subset of patients with HS. In this review, we synthesized the current data on γ-secretase in HS, evaluated its importance in the context of disease pathobiology, and discussed avenues of future studies

Cell Competition Boosts Clonal Evolution and Hypoxic Selection in Cancer

The comparison of fitness between cells leads to the elimination of less competent cells in the presence of more competent neighbors via cell competition (CC). This phenomenon has been linked with several cancer-related genes and thus may play an important role in cancer. Various processes are involved in the regulation of tumor initiation and growth, including tumor hypoxia, clonal stem cell selection, and immune cell response, all of which have been recently shown to have a potential connection with the mechanisms involved in CC. This review aims to unravel the relation between these processes and competitive cell interactions and how this affects disease progression

Surface translocation of ACE2 and TMPRSS2 upon TLR4/7/8 activation is required for SARS-CoV-2 infection in circulating monocytes

Infection of human peripheral blood cells by SARS-CoV-2 has been debated because immune cells lack mRNA expression of both angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease type 2 (TMPRSS2). Herein we demonstrate that resting primary monocytes harbor abundant cytoplasmic ACE2 and TMPRSS2 protein and that circulating exosomes contain significant ACE2 protein. Upon ex vivo TLR4/7/8 stimulation, cytoplasmic ACE2 was quickly translocated to the monocyte cell surface independently of ACE2 transcription, while TMPRSS2 surface translocation occurred in conjunction with elevated mRNA expression. The rapid translocation of ACE2 to the monocyte cell surface was blocked by the endosomal trafficking inhibitor endosidin 2, suggesting that endosomal ACE2 could be derived from circulating ACE2-containing exosomes. TLR-stimulated monocytes concurrently expressing ACE2 and TMPRSS2 on the cell surface were efficiently infected by SARS-CoV-2, which was significantly mitigated by remdesivir, TMPRSS2 inhibitor camostat, and anti-ACE2 antibody. Mass cytometry showed that ACE2 surface translocation in peripheral myeloid cells from patients with severe COVID-19 correlated with its hyperactivation and PD-L1 expression. Collectively, TLR4/7/8-induced ACE2 translocation with TMPRSS2 expression makes circulating monocytes permissive to SARS-CoV-2 infection

The Hidradenitis Suppurativa Omics Database (HS-OmicsDB)

Large scale meta-analyses of genomics and genetics have spurred research in a number of fields, such as cancer, genetics and immunology. Publicly available ‘omics databases provide valuable hypothesis generating and validation tools. To date, no such initiative has been undertaken for Hidradenitis Suppurativa (HS), an inflammatory skin disease of unknown etiology. We present here, a longitudinal initiative seeking to aggregate publicly available ‘omics data to enhance research efforts in HS. In its first iteration, we include bulk and single-cell RNA sequencing data from untreated HS patients. Our data, aggregated from publicly available GEO datasets provides a tool to profile gene expression in specific tissue types (i.e. lesional, perilesional, nonlesional and healthy skin) as well as map cell-specific gene expression on single-cell data from HS lesions