Biology subjects

Friedman, S. L.

Publications and source records attributed to Friedman, S. L..

9 recordsLinked to original sources

bioRxiv2025

Cannabinoid Receptor 2 Activating Antibodies: A Promising Therapeutic Strategy for Macrophage-Driven Fibro-Inflammatory Diseases

Fibrotic diseases, often fueled by chronic inflammation, represent a major unmet medical need. A critical driver of this process is the activation of macrophages, which secrete pro-inflammatory cytokines and chemokines, leading to immune cell recruitment and collagen deposition by myofibroblasts. Agonizing the cannabinoid receptor 2 (CB2), expressed on macrophages, offers a potential therapeutic avenue to suppress this activation. Despite widespread interest in CB2 modulation, challenges remain in the development of small molecule agonists, including insufficient specificity and poor drug-like properties. Antibodies are highly specific with favorable pharmacokinetics and bioavailability, but GPCR agonist antibodies have been difficult to discover. Here we present first-in-class CB2 agonist antibodies, AB120 and AB150. These antibodies are CB2 specific, G-alpha biased, and effectively decrease the expression of macrophage activation markers and key pro-inflammatory cytokines, including IL-6, IL-1{beta} and TNF-. Furthermore, using an ex vivo human precision-cut liver slice (hPCLS) model of liver fibrosis, we observe that treatment with these CB2 agonist antibodies not only reduces inflammatory markers but also decreases collagen expression, indicating a potential to halt or reverse fibrosis. These novel CB2-specific agonist antibodies hold promise as therapeutics for a range of fibrotic and inflammatory conditions driven by chronic macrophage activation and demonstrate the potential of GPCR antibody agonists to drug this challenging class of targets. Significance StatementFibrotic diseases driven by chronic inflammation lack effective treatments. CB2 agonism modulates macrophage activation to reduce pro-inflammatory cytokines suggesting a novel avenue of treatment, but small molecule CB2 agonists have faced substantial limitations due to off-target effects. We introduce two novel CB2-specific agonist antibodies with potent anti-inflammatory and anti-fibrotic effects in vitro and in a human ex vivo liver fibrosis model. These antibodies provide a promising new therapeutic strategy and highlight the advantages of antibodies as GPCR agonist drugs.

pharmacology and toxicology↗

bioRxiv2025

Scar-associated endothelial-stellate cellular crosstalk drives fibrosis resolution in MASH

Fibrosis, or scarring, can affect many organs including liver, lung, heart, kidney, intestines etc. and is responsible for [~]40% of mortality in the industrialized world. Compared to other organs, fibrosis in the liver typically resolves when the source of injury is extinguished. Elucidating the molecular mechanisms that underlie spontaneous fibrosis resolution in the liver may lead to novel antifibrotic strategies for all organs. In this study we established a robust mouse model of fibrosis regression in MASH (Metabolic dysfunction-Associated Steatohepatitis), a highly prevalent chronic liver diseases worldwide, and performed single cell and in situ molecular profiling of the liver to define novel drivers of fibrosis regression. As fibrosis regressed, we detected a reduction of inflammatory cells and an expansion of endothelial cells. Prediction of cell-cell communication using the Calligraphy pipeline identified a Wnt9b-Sfrp2 crosstalk that emerges as fibrosis resolved in our model. To establish the Wnt9b-Sfrp2 crosstalk as a driver of fibrosis resolution we treated mice with recombinant Sfrp2, which slowed spontaneous fibrosis regression compared to vehicle treated mice. From our single cell datasets we identified a subset of endothelial cells, termed "Endo4", as the source of Wnt9b. Immunostaining of the Endo4 marker VWF using tissue clearing and 3D imaging revealed VWF+ vasculature enveloped by activated hepatic stellate cells (HSCs) that penetrated deep into the fibrotic septa, establishing Endo4 as de facto scar-associated endothelial cells and providing a structural basis of their cellular crosstalk with HSCs. Finally, using a recently developed in situ protease activity screen, prominent serine protease activity co-localized with both scar-associated Endo4 cells and HSCs. In summary, we uncovered an WNT-dependent endo-stellate crosstalk within the fibrotic niche as a novel regulatory node underlying murine MASH fibrosis regression, and a promising therapeutic target.

molecular biology↗

bioRxiv2025

In vivo anti-FAP CAR T therapy reduces fibrosis and restores liver homeostasis in metabolic dysfunction-associated steatohepatitis

In this study, we aimed to determine the efficacy of in vivo chimeric antigen receptor (CAR) T cell therapy, generated by targeted lipid nanoparticles (t-LNPs), as an anti-fibrotic in metabolic dysfunction-associated steatotic liver disease. Hepatic fibrosis is a key predictor of mortality in liver disease, driven by fibrogenic hepatic stellate cells (HSCs). In heart, chimeric antigen receptor (CAR) T cells targeting fibroblast activation protein alpha (FAP) reduce murine cardiac fibrosis. However, the value of this approach in liver is unknown. We explored the anti-fibrotic potential of in vivo-generated anti-FAP CAR T cells in metabolic dysfunction-associated steatohepatitis (MASH), a highly prevalent disease with no approved anti-fibrotic therapies. We first established that FAP expression in both human and murine MASH is specific to HSCs. We then used flow cytometry, Sirius Red morphometry, digital pathology analysis, and single nuclear RNA-sequencing to assess the impact of anti-FAP CAR T cell therapy on murine MASH. Anti-CD5 targeted-LNPs carrying anti-FAPCAR mRNA generate activated, transient anti-FAP CAR T cells, which significantly reduced fibrosis by depleting pro-fibrogenic HSCs, and by modulating immune cells, endothelial cells and hepatocytes in a non-cell autonomous manner to mitigate inflammation and restore hepatic homeostasis. These findings reinforce the potential of in vivo CAR T therapy to attenuate a highly morbid and pervasive liver disease through integrated, multicellular salutary effects. One Sentence SummaryRNA-based treatment transiently reprograms immune cells to target scar-forming cells in fatty liver disease, thus improving liver health overall.

cell biology↗

bioRxiv2024

Conditional deletion of CEACAM1 causes hepatic stellate cell activation

ObjectivesHepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with MASH. Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPAR{gamma} on CEACAM1 transcriptoin and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation. MethodsWe examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre+Cc1fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts. ResultsLratCre+Cc1fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HDCs. This was inhibited by nicotinic acid treatment which stemmed the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-{kappa}B/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1. ConclusionsLoss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

physiology↗

bioRxiv2024

Mannose Supplementation Curbs Liver Steatosis and Fibrosis in Murine MASH by Inhibiting Fructose Metabolism

Metabolic dysfunction-associated steatohepatitis (MASH) can progress to cirrhosis and liver cancer. There are no approved medical therapies to prevent or reverse disease progression. Fructose and its metabolism in the liver play integral roles in MASH pathogenesis and progression. Here we focus on mannose, a simple sugar, which dampens hepatic stellate cell activation and mitigates alcoholic liver disease in vitro and in vivo. In the well-validated FAT-MASH murine model, oral mannose supplementation improved both liver steatosis and fibrosis at low and high doses, whether administered either at the onset of the model ("Prevention") or at week 6 of the 12-week MASH regimen ("Reversal"). Thein vivo anti-fibrotic effects of mannose supplementation were validated in a second model of carbon tetrachloride-induced liver fibrosis. In vitro human and mouse primary hepatocytes revealed that the anti-steatotic effects of mannose are dependent on the presence of fructose, which attenuates expression of ketohexokinase (KHK), the main enzyme in fructolysis. KHK is decreased with mannose supplementation in vivo and in vitro, and overexpression of KHK abrogated the anti-steatotic effects of mannose. Our study identifies mannose as a simple, novel therapeutic candidate for MASH that mitigates metabolic dysregulation and exerts anti-fibrotic effects.

cell biology↗

bioRxiv2023

Hepatic stellate cells maintain liver homeostasis through paracrine neurotrophin-3 signaling

Organ homeostasis is maintained by regulated proliferation of distinct cell populations. In mouse liver, cyclin D1-positive hepatocytes in the midlobular zone repopulate the parenchyma at a constant rate to preserve liver homeostasis. The mitogenic cues that underlie this process are unknown. Hepatic stellate cells, the livers pericytes, are in close proximity to hepatocytes and have been implicated in supporting hepatocyte proliferation, but their role in liver homeostasis is unknown. Here, we employ a T cell-mediated hepatic stellate cell ablation model to remove nearly all hepatic stellate cells in the murine liver, enabling the unbiased characterization of hepatic stellate cell functions. In the normal murine liver, complete loss of hepatic stellate cells persists for up to 6 weeks and reduces liver mass. Our results show that hepatic stellate cells induce cyclin D1 in midlobular hepatocytes by release of neurotrophin-3 to promote hepatocyte proliferation via tropomyosin receptor kinase B signaling. These findings establish that hepatic stellate cells form the niche for midlobular hepatocytes and reveal a novel hepatocyte growth factor signaling pathway. One-Sentence SummaryHepatic stellate cells provide mitogenic cues for midlobular hepatocyte proliferation and metabolic zonation by secreting neurotrophin-3.

cell biology↗

bioRxiv2022

Secreted folate receptor-gamma drives fibrogenesis in nonalcoholic steatohepatitis by amplifying TGFβ signaling in hepatic stellate cells

Hepatic fibrosis is the primary determinant of mortality in nonalcoholic steatohepatitis (NASH) patients. Antagonism of transforming growth factor {beta} (TGF{beta}), a master profibrogenic cytokine, is a promising therapeutic target that has not yet been translated into an effective therapy, due in part to the lack of animal models resembling the human phenotype of NASH. Here we have identified that soluble secreted folate receptor gamma (FOLR3), expressed in humans but not rodents, is a secreted protein that is elevated in livers of NASH subjects but not in subjects with nonalcoholic fatty liver, type II diabetes, or healthy subjects. FOLR3, based on global proteomics, was the most highly expressed NASH-specific protein and positively correlated with increasing fibrosis stages, suggesting an impact on activated hepatic stellate cells (HSCs), the key fibrogenic cell in the liver. Exposure of stellate cells to exogenous FOLR3 led to elevated extracellular matrix (ECM) protein production, an effect synergistic with TGF{beta}1. Structurally, FOLR3 interacts with serine protease HTRA1, which downregulates TGF{beta} signaling through the degradation of its receptor TGFBR2. Administration of human FOLR3 to mice induced severe bridging fibrosis and an ECM pattern resembling human NASH. Our study uncovers a novel role of FOLR3 in enhancing fibrosis and identifies FOLR3 as a potential therapeutic target in NASH fibrosis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/500829v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1ac3ce3org.highwire.dtl.DTLVardef@d1945corg.highwire.dtl.DTLVardef@1632eb1org.highwire.dtl.DTLVardef@8e8d21_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2021

The peroxisomal transporter ABCD3 plays a major role in dicarboxylic fatty acid metabolism

Peroxisomes metabolize a specific subset of fatty acids, which include dicarboxylic fatty acids (DCAs) generated by {omega}-oxidation. Data obtained in vitro suggest that the peroxisomal transporter ABCD3 (also known as PMP70) mediates the transport of DCAs into the peroxisome, but in vivo evidence to support this role is lacking. In this study, we studied an Abcd3 KO mouse model generated by CRISPR-Cas9 technology using targeted and untargeted metabolomics, histology, immunoblotting, and stable isotope tracing technology. We show that ABCD3 functions in DCA metabolism and uncover a novel role for this peroxisomal transporter in lipid metabolic homeostasis. The Abcd3 KO mouse presents with lipodystrophy, increased circulating free fatty acids, decreased ketone bodies, enhanced hepatic cholesterol synthesis and decreased hepatic de novo lipogenesis. Moreover, our study suggests that DCAs are metabolized by mitochondrial {beta}-oxidation when ABCD3 is not functional, reflecting the importance of the metabolic compartmentalization and communication between peroxisomes and mitochondria. In summary, this study provides data on the role of the peroxisomal transporter ABCD3 in hepatic lipid homeostasis and DCA metabolism, and the consequences of peroxisomal dysfunction for the liver.

physiology↗

bioRxiv2021

Murine deficiency of peroxisomal L-bifunctional protein (EHHADH) causes medium-chain 3-hydroxydicarboxylic aciduria and perturbs hepatic cholesterol homeostasis

Peroxisomes play an essential role in the {beta}-oxidation of dicarboxylic acids (DCAs), which are metabolites formed upon {omega}-oxidation of fatty acids. Genetic evidence linking transporters and enzymes to specific DCA {beta}-oxidation steps is generally lacking. Moreover, the physiological functions of DCA metabolism remain largely unknown. In this study, we aimed to characterize the DCA {beta}-oxidation pathway in human cells, and to evaluate the biological role of DCA metabolism using mice deficient in the peroxisomal L-bifunctional protein (Ehhadh KO mice). In vitro experiments using HEK-293 KO cell lines demonstrate that ABCD3 and ACOX1 are essential in DCA {beta}-oxidation, whereas both the bifunctional proteins (EHHADH and HSD17B4) and the thiolases (ACAA1 and SCPx) have overlapping functions and their contribution may depend on expression level. We also show that medium-chain 3-hydroxydicarboxylic aciduria is a prominent feature of EHHADH deficiency in mice most notably upon inhibition of mitochondrial fatty acid oxidation. Using stable isotope tracing methodology, we confirmed that products of peroxisomal DCA {beta}-oxidation can be transported to mitochondria for further metabolism. Finally, we show that, in liver, Ehhadh KO mice have increased mRNA and protein expression of cholesterol biosynthesis enzymes with decreased (in females) or similar (in males) rate of cholesterol synthesis. We conclude that EHHADH plays an essential role in the metabolism of medium-chain DCAs and postulate that peroxisomal DCA {beta}-oxidation is a regulator of hepatic cholesterol biosynthesis.

physiology↗