Biology subjects

Weichhart, T.

Publications and source records attributed to Weichhart, T..

9 recordsLinked to original sources

bioRxiv2026

Alternatively polarized neutrophils metabolically restrain macrophage-driven inflammation

Macrophage-driven inflammation underlies many inflammatory diseases, yet the mechanisms that restrain macrophage activation within inflamed tissues remain poorly understood. Using mouse models of foreign body granuloma formation and macrophage activation syndrome, we show that neutrophils accumulate at sites of inflammation and metabolically restrain macrophage-driven pathology. Neutrophil depletion or genetic impairment exacerbated tissue pathology, whereas induced neutrophilia attenuated inflammatory damage. Tissue-infiltrating neutrophils acquired an alternatively polarized state characterized by high arginase 1 activity that was regulated by an IL4Ra-STAT3-NOX2 signaling axis. Functionally, polarized neutrophils depleted extracellular arginine in an arginase 1-dependent manner, thereby limiting macrophage effector programs. Human neutrophils exhibited conserved regulation of arginase activity, and alternatively polarized neutrophils were detected in patients with sarcoidosis and macrophage activation syndrome. Together, these findings identify an arginine-dependent metabolic mechanism through which alternatively polarized neutrophils restrain macrophage-driven inflammation and reveal a previously unrecognized immune-regulatory role for these cells in chronic inflammatory disease.

immunology↗

bioRxiv2026

A cell death screen identifies macrophage-depleting agents with therapeutic potential

Macrophages are critical regulators of inflammation and tissue homeostasis, yet aberrant macrophage activation contributes to a wide spectrum of inflammatory and malignant diseases. Therapeutic strategies that directly reduce macrophage numbers have shown promise, but macrophage survival pathways remain incompletely defined, limiting the development of targeted therapeutic strategies. Here, we establish a high-throughput screening platform to identify small molecule inhibitors that impair macrophage survival. Screening a library of more than 2,000 targeted compounds in a cell survival assay, combined with in silico and in vitro analysis of macrophage specificity, revealed the identification of three potent inhibitors: BIX-01294, GSK-J4, and Masitinib. All three compounds downregulated leukemia inhibitory factor receptor (LIFR), whose inhibition markedly reduced macrophage viability. In vivo, these inhibitors effectively depleted large peritoneal macrophages, ameliorated key symptoms of macrophage activation syndrome (MAS), and suppressed tumor growth in a syngeneic transplanted melanoma model as well as in an autochthonous lung cancer model. Together, these findings identify small molecule-mediated macrophage depletion as a promising therapeutic strategy and establish an experimental approach to uncover regulators of macrophage survival.

immunology↗

bioRxiv2026

Stress-induced Metabolic Remodeling of Adipose and Brain Tissue revealed by Positron Emission Tomography

Stress impacts our health and triggers physiological adaptations, yet the metabolic programs engaged during stress remain incompletely understood. To fill this knowledge gap, we utilized total-body positron emission tomography (PET), multi-OMICS, and endocrine profiling to assess how various murine stress models affect systemic metabolic remodeling. We found that acute immobilization and surgery activate brown adipose tissue as part of the stress response, independently of hypothermia, thereby acting as a highly stress-sensitive metabolic hub. Additionally, we identified stress-specific hypo- and hypermetabolic signatures in different brain regions, and distinguished networks between brain and adipose tissue depots across the different stress groups. Our work presents a novel perspective on stress and its mobilization of metabolic resources and identifies PET imaging of brain and adipose tissue as a valuable, minimally invasive technique for tracking metabolic stress responses in mice, with relevance for animal welfare and disease models, and translational impact for mental health studies and preventive medicine.

physiology↗

bioRxiv2026

Fibroblast-derived thrombospondin-1 shapes macrophage polarization in advanced human co-culture models

BackgroundTumor-associated macrophages (TAMs) are key drivers of the immunosuppressive tumor microenvironment (TME), supporting tumor progression through diverse functions. However, mechanistic studies of TAM polarization remain limited by the lack of physiologically relevant human model systems that capture stromal-immune interactions and macrophage heterogeneity. MethodsWe established advanced human co-culture systems that integrate healthy donor-derived macrophages with patient-derived organoids and tumoroids (PDOs and PDTs), as well as matched normal fibroblasts (NFs) and cancer-associated fibroblasts (CAFs). These multicellular models enabled the investigation of interactions among stromal, epithelial, and immune cells within tumor and adjacent normal tissue environments. ResultsThe co-culture systems recapitulated distinct macrophage states associated with tumor and adjacent normal environments and identified fibroblasts as major regulators of macrophage phenotypes. CAFs promoted macrophage metabolic remodeling characterized by altered lipid handling and enrichment of TAM-like signatures. Mechanistically, we identified thrombospondin 1 (TSP1) as a CAF-secreted factor linked to metabolic priming. Recombinant TSP1 induced transient lipid accumulation followed by mitochondrial remodeling. In tumor co-culture conditions, CD36 inhibition reduced lipid accumulation in macrophages, supporting a role for TSP1-linked lipid crosstalk in stromal-immune interactions. ConclusionOur study establishes advanced patient-derived co-culture models as a platform to investigate human TAM biology and stromal-immune interactions in CRC. Using these systems, we identify a fibroblast-associated TSP1-lipid axis linked to macrophage metabolic remodeling and TAM-like polarization, highlighting stromal metabolic communication as a potential targetable feature of the CRC microenvironment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=176 HEIGHT=200 SRC="FIGDIR/small/728363v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@11b8c9borg.highwire.dtl.DTLVardef@1ac3aa2org.highwire.dtl.DTLVardef@3da223org.highwire.dtl.DTLVardef@5fc3a7_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

IRF4 is a master regulator of multinucleated giant cell formation

Multinucleated giant cells (MGCs) are a hallmark pathological feature of a wide range of diseases, yet the mechanisms underlying their formation and function remain poorly understood. Although it is recognized that MGCs arise from a heterogeneous pool of myeloid precursors, how a committed MGC fate develops therein remains unknown. Here, combining temporal in vitro and in vivo differentiation of bone marrow-derived myeloid precursors with single cell and bulk RNA sequencing as well as CRISPR/Cas9-mediated gene editing, we shed insight into how MGCs emerge. Our findings reveal that coordinated upregulation of cell fusion genes and cellular metabolism, particularly oxidative phosphorylation, regulate the transition from macrophage progenitors to fusion competent cells. In vivo fate-mapping unveils Ms4a3-, and Cd11c-but not Cx3cr1-traced cells as the predominant precursor populations for MGCs in a lung granuloma formation model. Notably, transcription factor profiling in the progression from early myeloid precursors to pre-MGCs identifies IRF4 as a key molecular switch driving MGC generation. IRF4+ MGCs are present in different pathologies, including Schistosoma mansoni egg induced granulomas, Aspergillus fumigatus conidia mediated allergic airway inflammation and human head and neck squamous cell carcinomas. Mechanistically, IRF4 controls critical fusion related genes such as Dcstamp and Ocstamp. Consequently, Irf4 deficient cells are unable to develop into MGCs. Collectively, our work delineates the trajectory of MGC differentiation, establishing IRF4 as a defining transcription factor required for the generation of fusion-competent progenitors that ultimately give rise to MGCs.

immunology↗

bioRxiv2025

Itaconate is metabolized to 2-hydroxymethylsuccinate through a CoA-independent degradation pathway in mitochondria

The immunometabolite itaconate modulates cellular metabolism and is converted into structurally similar C5 dicarboxylates that require advanced analytics to decipher their metabolic fate. Here, we employ high-resolution mass spectrometry and tracing approaches and identify 2-hydroxymethylsuccinate (2HMS) as a previously unrecognized C5 dicarboxylate derived from itaconate. 2HMS synthesis occurs during inflammatory responses and upon itaconate treatment, as detected by 13C itaconate tracing. Pathway analysis reveals that methylglutaconyl-CoA hydratase (AUH) drives 2HMS synthesis through a CoA-independent conversion (CIC) pathway. This pathway is distinct from the CoA-dependent conversion (CDC) pathway that generates mesaconate and itaconyl-CoA influencing B12-dependent processes. In vivo inflammation studies reveal that adipose tissue prefers CIC to produce 2HMS and liver favors CDC-mediated mesaconate synthesis, highlighting tissue-specific itaconate degradation routes. This study identifies a new branch of itaconate metabolism, provides an analytical framework to resolve C5 dicarboxylate networks, and links 2HMS to inflammation and mitochondrial metabolism that might be targeted therapeutically.

cell biology↗

bioRxiv2025

Pro- and anti-inflammatory macrophages adjust UCP2 protein levels based on their intrinsic metabolism and available metabolites

The immune and metabolic responses of macrophages are closely linked, and mitochondria play a key role in polarizing them into pro-inflammatory (classical) and anti-inflammatory (alternative) states. Mitochondrial uncoupling protein 2 (UCP2) is involved in regulating macrophage inflammation and glucose metabolism; however, its regulatory mechanisms are unclear. We found that inflammatory stimuli reduce UCP2 expression and oxygen consumption rates (OCR), indicating mitochondrial suppression. Conversely, IL-4-activated macrophages displayed higher UCP2 levels and enhanced respiration. Under glucose deprivation, LPS-stimulated macrophages retained mitochondrial activity despite lower UCP2 levels. Pyruvate emerged as a key regulator of UCP2, blocking its mitochondrial entry reduced UCP2 expression. Additionally, hypoxia markedly decreased UCP2 levels in IL-4-activated macrophages, suggesting that hypoxia contributes to UCP2 suppression in pro-inflammatory macrophages. Notably, pro-inflammatory macrophages exhibit reduced reliance on UCP2 due to suppressed mitochondrial respiration. Pyruvate regulates UCP2 expression, highlighting the connection between glycolysis and mitochondrial metabolism. These findings may inform therapeutic strategies for diseases involving immune dysregulation.

biophysics↗

bioRxiv2024

Computational metabolic modeling unveils gut microbiomes role in metabolic shifts during murine cancer cachexia

Cancer cachexia is a multifactorial syndrome characterized by involuntary weight loss, muscle wasting, systemic inflammation, and metabolic alterations, affecting up to 87% of pancreatic and gastric cancer patients. Unlike simple starvation, cachexia is driven by metabolic disruption involving both host physiology and the gut microbiome. While microbiome changes in cachexia have been documented, a coherent understanding of how these changes translate into functional metabolic shifts remains elusive. In this study, we combined in vivo fecal and plasma metabolomic analyses with a novel computational microbiome simulation pipeline to identify cachexia-associated microbial metabolites. Using the murine MCA207 tumor line and its cachectic derivative CHX207, we differentiated microbiome changes driven by cachexia from those induced by tumor growth. Our computational tool, McMurGut, a murine-tailored extension of MICOM, enabled simulation of microbial metabolic interactions specific to the mouse microbiome, covering 91% of identified genera. We identified significant abundance changes in 35 microbial genera and corresponding shifts in metabolite production, including reductions in short-chain fatty acids (SCFAs) like acetate and butyrate, alongside increased production of galactose, formate, and propionate. Notably, decreases in SCFA production, particularly by genera such as Faecalibaculum and Dubosiella, correlated with exacerbated cachectic symptoms. Additionally, the elevated production of formate and galactose, primarily by Bacteroides and Lactobacillus, suggested altered fermentation pathways in cachexia, potentially linked to increased mucus degradation. Validation of our computational predictions via NMR metabolomics highlighted key congruencies between predicted and experimentally observed metabolites, supporting the role of microbiome-driven metabolic shifts in cachexia pathology. These findings provide crucial insights into the microbiomes involvement in cachexia and suggest future avenues for therapeutic interventions aimed at modulating microbial taxa and their metabolic outputs to improve patient outcomes.

microbiology↗

bioRxiv2021

24-Nor-Ursodeoxycholic acid reshapes immunometabolism in CD8+ T cells and alleviates hepatic inflammation

Background & Aims24-NorUrsodeoxycholic acid (NorUDCA) is novel therapy for immune-mediated liver diseases such as primary sclerosing cholangitis (PSC) where dysregulated T cells including CD8+ T cells cause liver immunopathology. We hypothesized that NorUDCA may directly modulate CD8+ T cell effector function thus contributing to its therapeutic efficacy independent of anti-cholestatic effects. MethodsNorUDCA effects on CD8+ T cell function in vivo were investigated in a hepatic injury model system induced by excessive CD8+ T cell immune response upon non-cytolytic lymphocytic choriomeningitis virus (LCMV) infection. Mechanistic studies included molecular and biochemical approaches, flow cytometry and metabolic assays in mouse CD8+ T cells in vitro. Mass spectrometry (MS) was used to identify potential targets modulated by NorUDCA in CD8+ T cells. NorUDCA signaling effects observed in murine systems were validated in peripheral T cells from healthy volunteers and PSC patients. ResultsIn vivo NorUDCA ameliorated hepatic injury and systemic inflammation upon LCMV infection. Mechanistically, NorUDCA demonstrated a strong immunomodulatory efficacy in CD8+ T cells affecting lymphoblastogenesis, mTORC1 signaling and glycolysis of CD8+ T cells. With MS, we identified that NorUDCA regulates CD8+ T cells via targeting mTORC1. NorUDCAs impact on mTORC1 signaling was further confirmed in circulating human CD8+ T cells. ConclusionsNorUDCA possesses a yet-unrecognized direct modulatory potency on CD8+ T cells and attenuates excessive CD8+ T cell hepatic immunopathology. These findings may be relevant for treatment of immune-mediated liver diseases such as PSC and beyond.

molecular biology↗