Biology subjects

Radtke, C.

Publications and source records attributed to Radtke, C..

4 recordsLinked to original sources

bioRxiv2026

Spatially organized cancer-associated fibroblast subtypes partition cutaneous carcinomas into immune-active and contracted, immune-repressed niches

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (SCC) are the most common keratinocyte-derived malignancies, yet they differ markedly in invasiveness, metastatic potential, and immune contexture. Although cancer-associated fibroblasts (CAFs) are increasingly recognized as key regulators of tumor architecture and tumor immunity, the spatial organization of distinct CAF subtypes in cutaneous carcinomas and their functional relationship with immune cells remains incompletely understood. Using a 33-plex imaging mass cytometry (IMC) panel, we profiled 28 regions of interest (ROIs) from 17 human BCC and SCC specimens, encompassing more than 739,000 single cells, and integrated these data with RNA fluorescence in situ hybridization (RNA-FISH), immunohistochemistry (IHC), multiplex immunofluorescence, and in vitro functional assays. We identified four fibroblast populations, including immunomodulatory CAFs (iCAFs), matrix CAFs (mCAFs), myofibroblast-like CAFs (myoCAFs), and reticular fibroblasts (retFIBs), and found that aggressive tumor subtypes were characterized by increased stromal area, extracellular matrix deposition, and altered CAF composition. CAF composition differed most prominently across BCC subtypes, with nodular BCC enriched for mCAFs and infiltrative BCC showing increased myoCAF density, consistent with a shift toward a contractile stromal program. Spatial analyses revealed distinct CAF-immune niches: iCAFs localized to immune-cell-rich, inflamed niches enriched for activated and/or exhaustion-associated immune-cell marker programs, whereas myoCAFs occupied fibroblast-dense, immune-poor niches with globally reduced immune activation. mCAFs were preferentially associated with immune cell accumulation in the stroma and spatial immune compartmentalization, with limited immune cell presence within tumor nests. At the invasive front, CAF-immune coupling was highly subset-dependent, with iCAFs linked to antigen-experienced T-cell states and myoCAFs linked to immune exclusion. In vitro, patient-derived CAF cultures from myoCAF-rich biopsies showed enhanced collagen-gel contraction, with cultures enriched for MCAM+ CAFs displaying increased contractile capacity. Aggressive tumor variants displayed increased stromal nuclear YAP/TAZ, while complementary single-cell pathway analysis supported a mechanically remodeled stromal microenvironment in which mCAFs contribute ECM/matrix-remodeling programs and RGS5/myoCAF-like populations show enhanced mechanotransduction-associated signaling, rather than a uniform CAF-wide increase in canonical YAP/TAZ transcriptional output. Together, these findings define spatially organized CAF programs in cutaneous carcinomas and identify myoCAF-rich stromal niches as a recurrent feature of aggressive, immune-repressed tumor architecture. These results nominate CAF composition as a biomarker of immune architecture and a potential determinant of therapeutic response.

cancer biology↗

bioRxiv2023

CAF variants control the tumor-immune microenvironment and predict skin cancer malignancy

Cancer-associated fibroblasts (CAFs) play a key role in cancer progression and treatment outcome. This study dissects the yet unresolved intra-tumoral variety of CAFs in three skin cancer types -- Basal Cell Carcinoma, Squamous Cell Carcinoma, and Melanoma -- at molecular and spatial single-cell resolution. By integral analysis of the fibroblasts with the tumor microenvironment, including epithelial, mesenchymal, and immune cells, we characterize three distinct CAF subtypes: myofibroblast-like RGS5+ CAFs, matrix CAFs (mCAFs), and immunomodulatory CAFs (iCAFs). Notably, large cohort tissue analysis reveals marked shifts in CAF subtype patterns with increasing malignancy. Two CAF types exhibit immunomodulatory capabilities via distinct mechanisms. mCAFs synthesize extracellular matrix and have the ability to ensheath tumor nests, potentially limiting T cell invasion in low-grade tumors. In contrast, iCAFs are enriched in late-stage tumors, especially infiltrative BCC and high-grade melanoma, and express unexpectedly high mRNA and protein levels of cytokines and chemokines, pointing to their integral role in immune cell recruitment and activation. This finding is further supported by our observation that in vitro exposure of primary healthy fibroblasts to skin cancer cell secretomes induces an iCAF-like phenotype with immunomodulatory functions. Thus, targeting CAF variants, particularly the immunomodulatory iCAF subtype, holds promise for improved efficacy of immunotherapy in skin cancers.

cancer biology↗

bioRxiv2022

The secretome of irradiated peripheral mononuclear cells attenuates hypertrophic skin scarring

BackgroundHypertrophic scars can cause pain, movement restrictions, and reduction of quality of life. Despite numerous options to tackle hypertrophic scarring, efficient therapies are still scarce, and cellular mechanisms are not well understood. Secreted factors from peripheral blood mononuclear cells (PBMCsec) were previously described for their beneficial effects in tissue regeneration. Here, we investigated the effects of PBMCsec on skin scarring in mouse models and human scar explant cultures at single cell resolution (scRNAseq). MethodsMouse wounds and scars were treated with PBMCsec either intradermally or topically. Human mature scars were treated with PBMCsec ex vivo in explant cultures. All experimental settings were analyzed by single cell RNA sequencing (scRNAseq). A variety of bioinformatics approaches were used to decipher gene regulation in the scRNAseq data sets. Components of the extracellular matrix (ECM) were investigated in situ by immunofluorescence. The effect of PBMCsec on myofibroblast differentiation and elastin expression was investigated by stimulating human primary fibroblasts with TGF{beta}. FindingsTopical and intradermal application of PBMCsec regulated the expression of a variety of genes involved in pro-fibrotic processes and tissue remodeling. Our bioinformatics approach identified elastin as a common linchpin of antifibrotic action in both, the mouse and human experimental setting. In vitro, we found that PBMCsec prevents TGF{beta}-mediated myofibroblast-differentiation and attenuates abundant elastin expression through non-canonical signaling inhibition. Furthermore, TGF{beta}-induced breakdown of elastic fibers was strongly inhibited by addition of PBMCsec. InterpretationTogether, we showed anti-fibrotic effect of PBMCsec on cutaneous scars in mouse and human experimental settings, suggesting PBMCsec as a novel therapeutic option to treat skin scarring. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSParacrine factors secreted from irradiated peripheral mononuclear cells (PBMCsec) show strong tissue regenerative properties in a variety of organs and are shown to enhance cutaneous wound healing. Whether PBMCsec shows anti-fibrotic properties on scar formation has not been investigated so far. Added value of this studyIn the present study, we were able to demonstrate that PBMCsec improves quality of developing and mature scars in mouse and human scar tissue. We found that PBMCsec is able to attenuate the expression of various genes, promoting scar formation and inhibit TGF{beta}-induced myofibroblast differentiation. Elastin and TXNIP were identified as a common linchpin of its anti-fibrotic action. Implications of all the available evidenceUsing in vivo, ex vivo, and in vitro models and analyses on a single-cell level, our study paves the way for clinical studies evaluating the use of PBMCsec for the treatment of human cutaneous scars.

cell biology↗

bioRxiv2020

Single cell landscape of hypertrophic scars identifies serine proteases as key regulators of myofibroblast differentiation

Despite recent advances in understanding skin scarring, mechanisms triggering hypertrophic scar formation are still poorly understood. In the present study we performed single-cell sequencing of mature human hypertrophic scars and developing scars in mice. Compared to normal skin, we found significant differences in gene expression in most cell types present in scar tissue. Fibroblasts (FBs) showed the most prominent alterations in gene expression, displaying a distinct fibrotic signature. By comparing genes upregulated in murine FBs during scar development with genes highly expressed in mature human hypertrophic scars, we identified a group of serine proteases, tentatively involved in scar formation. Two of them, dipeptidyl-peptidase 4 (DPP4) and urokinase (PLAU), were further analyzed in functional assays, revealing a role in TGF{beta}1-mediated myofibroblast differentiation and over-production of components of the extracellular matrix (ECM) without interfering with the canonical TGF{beta}1-signaling pathway. In this study, we delineate the genetic landscape of hypertrophic scars and present new insights into mechanisms involved in hypertrophic scar formation. Our data suggest the use of serine protease inhibitors for the treatment of skin fibrosis.

cell biology↗