Biology subjects

Scharschmidt, T. C.

Publications and source records attributed to Scharschmidt, T. C..

7 recordsLinked to original sources

bioRxiv2026

Self-antigen disrupts cDC1 mediated antitumor responses

Conventional dendritic cells navigate complex tissues and sample peripheral antigens, balancing immune suppression and activation to achieve tissue homeostasis. However, it remains unclear how an individual dendritic cells reconciles co-incident signals from immunological opposing antigens within the tissue or tumor microenvironment, where tolerogenic self-antigen and immunogenic tumor antigen or microbes coexist. Here, using complementary in vivo fluorescent reporter systems, high-resolution imaging and endosomal profiling, we simultaneously tracked uptake, intracellular processing and cross-presentation of cutaneous self, tumor and microbial antigens in murine skin tissue, tumors and draining lymph nodes. We find that a substantial fraction of dendritic cells acquire antigen from multiple sources and that localization within endosomal compartments is dictated by antigen source. Notably, type 1 conventional dendritic cells that co-process self and tumor antigen represent a significant proportion of tumor antigen-bearing dendritic cells in the tumor and tumor draining lymph node. These dual-antigen loaded dendritic cells display a diminished capacity to prime tumor-specific CD8+ T cells and a marked reduction in tumor derived peptide presented on surface MHCI, while cross-priming of self-antigen specific T cells is significantly increased. These changes occur despite equivalent or greater tumor antigen uptake relative to self-antigen and high expression of surface MHCI and costimulatory molecules. Together, these data support a model in which multiantigen processing within dendritic cells can bias peptide loading away from tumor-derived epitopes, thereby limiting tumor-specific cross-priming. Modulating the antigenic context of the tumor microenvironment or endosomal routing after antigen uptake may therefore represent a strategy to restore effective dendritic cell-mediated antitumor immunity.

immunology↗

bioRxiv2025

Discovery Stack Pilot: Feasibility and Outcomes of a Scientist-Designed Peer Review Model Separating Quality and Impact

Peer review serves as the cornerstone of scientific quality control. Yet, the current journal-centric system is hindered by long timelines, high publication costs, inconsistent review quality, systemic biases, and editorial gatekeeping. Notably, the system relies on misaligned measures of impact that are tethered to journal branding and conflate scientific rigor (Quality) with perceived significance (Impact). Here, we report findings from the Discovery Stack Pilot Study, which tested a scientist-designed, journal-independent peer review model. The Discovery Stack model integrates in-line reviewer comments to promote constructive feedback and separately evaluates scientific Quality and Impact using defined criteria. To examine feasibility and effectiveness, manuscripts were reviewed in parallel with traditional journal review. A total of 162 reviews were completed, and survey data from 86 participants were analyzed. The results showed that reviewers effectively evaluated Quality and Impact as separate dimensions, with Quality scores being more consistent across reviewers than Impact scores. Participants strongly supported the core elements of the Discovery Stack model and expressed enthusiasm for its broader adoption to enhance transparency, efficiency, and value in peer review. Future studies will explore integrating this model into a digital platform for reviewing and curating scientific discoveries to improve the production and dissemination of high-quality research.

scientific communication and education↗

bioRxiv2025

The emerging fungal pathogen Candida auris induces IFNγ to colonize mammalian hair follicles

Public health alarm concerning the emerging fungus Candida auris is fueled by its antifungal drug resistance and propensity to cause deadly outbreaks. Persistent skin colonization drives transmission and lethal sepsis although its basis remains mysterious. We compared the skin colonization dynamics of C. auris with its relative C. albicans, quantifying skin fungal persistence and distribution and immune composition and positioning. C. auris displayed a higher propensity to colonize hair follicles and avidly bound to human hair. While C. albicans triggered an effective sterilizing type 3/17 antifungal immune response driven by IL-17A/F-producing lymphocytes, C. auris triggered a type 1, IFN{gamma}-driven immune response targeting hair follicles. Rather than promoting fungal clearance, IFN{gamma} enhanced C. auris skin colonization by acting directly on keratinocytes impairing epithelial barrier integrity and repressing antifungal defense programs. C. auris exploits focal skin immune responses to create a niche for persistence in hair follicles.

immunology↗

bioRxiv2025

CD38 expression by neonatal human naïve CD4+ T cells shapes their distinct metabolic state and high regulatory T cell potential

Neonatal life is marked by rapid antigen exposure, necessitating establishment of peripheral immune tolerance via conversion of naive CD4+ T cells into regulatory T cells (Tregs). Here, we demonstrate heighted capacity for FOXP3 expression and tolerogenic function among cord blood versus adult blood naive CD4+ T cells and that this is linked to their unique metabolic profile and elevated expression of the NADase, CD38. Early life naive CD4+ T cells demonstrate a metabolic preference for glycolysis, which directly facilitates their differentiation trajectory. We reveal an age-dependent gradient in CD38 levels on naive CD4+ T cells and show that high CD38 expression contributes to both the glycolytic state and tolerogenic potential of neonatal CD4+ T cells, effects that are mediated at least in part via the NAD-dependent deacetylase SIRT1. Thus, the early life window for peripheral tolerance in humans is critically enabled by the immunometabolic state of the naive CD4+ compartment.

immunology↗

bioRxiv2023

Commensal myeloid crosstalk in neonatal skin regulates long-term cutaneous type 17 inflammation

Early life microbe-immune interactions at barrier surfaces have lasting impacts on the trajectory towards health versus disease. Monocytes, macrophages and dendritic cells are primary sentinels in barrier tissues, yet the salient contributions of commensal-myeloid crosstalk during tissue development remain poorly understood. Here, we identify that commensal microbes facilitate accumulation of a population of monocytes in neonatal skin. Transient postnatal depletion of these monocytes resulted in heightened IL-17A production by skin T cells, which was particularly sustained among CD4+ T cells and sufficient to exacerbate inflammatory skin pathologies. Neonatal skin monocytes were enriched in expression of negative regulators of the IL-1 pathway. Functional in vivo experiments confirmed a key role for excessive IL-1R1 signaling in T cells as contributing to the dysregulated type 17 response in neonatal monocyte-depleted mice. Thus, a commensal-driven wave of monocytes into neonatal skin critically facilitates immune homeostasis in this prominent barrier tissue.

immunology↗

bioRxiv2022

Early life tolerance depends on a subset of specialized dendritic cells and is reinforced by the skin microbiota

Early life establishment of tolerance to commensal bacteria at barrier surfaces carries enduring implications for immune health but remains poorly understood. Here we show that this process is controlled by microbial interaction with a specialized subset of antigen presenting cells. More particularly, we identify CD301b+ type 2 conventional dendritic cells (DC) as a subset in neonatal skin specifically capable of uptake, presentation and generation of regulatory T cells (Tregs) to commensal antigens. In early life, CD301b+ DC2 are enriched for programs of phagocytosis and maturation, while also expressing tolerogenic markers. In both human and murine skin, these signatures were reinforced by microbial uptake. In contrast to their adult counterparts or other early life DC subsets, neonatal CD301b+ DC2 highly expressed the retinoic acid-producing enzyme, RALDH2, deletion of which limited commensal-specific Tregs. Thus, synergistic interactions between bacteria and a specialized DC subset critically support early life tolerance at the cutaneous interface.

immunology↗

bioRxiv2020

Developing human fetal skin demonstrates a unique lymphocyte signature

Lymphocytes in barrier tissues play critical roles in host defense and homeostasis. These cells take up residence in tissues during defined developmental windows, when they may demonstrate distinct phenotypes and functions. Here, we utilized mass and flow cytometry to elucidate early features of human skin immunity, demonstrating a unique fetal skin lymphocyte signature. While most conventional {beta} T (Tconv) cells in fetal skin have a naive, proliferative phenotype, a subset of CD4+ Tconv and CD8+ cells demonstrate memory-like features and a propensity for IFN{gamma} production. Skin regulatory T cells dynamically accumulate over the second trimester in temporal and regional association with hair follicle development. These fetal skin Tregs demonstrate an effector memory phenotype while differing from their adult counterparts in expression of key effector molecules. Thus, we identify features of prenatal skin lymphocytes that may have key implications for understanding antigen and allergen encounters in utero and in infancy.

immunology↗