Biology subjects

Vacca, M.

Publications and source records attributed to Vacca, M..

9 recordsLinked to original sources

bioRxiv2026

TLR5 drives metabolic dysfunction-associated steatohepatitis through lipid- and flagellin-induced hepatocyte injury signalling

Liver fibrosis is a strong predictor of clinical outcomes in metabolic dysfunction-associated steatohepatitis (MASH). Fibrosis is a consequence of persistent liver cell injury and inflammation in which Toll-like receptors (TLRs) play a key initiating role. Here we test the hypothesis that TLR5 is involved in the development of MASH and fibrosis using a combination of clinical data from multiple independent patient cohorts, single cell liver transcriptomics and human in vitro and ex vivo models. Hepatic TLR5 expression, but not TLR2 or TLR4, is associated with liver fibrosis and mortality. Plasma levels of TLR5s cognate ligand flagellin are increased in MASH with advanced fibrosis and fall with liver disease improvement. Mechanistically, we identify two parallel TLR5-mediated routes to hepatocyte injury: one elicited by flagellin and the other indirectly by lipid injury. Furthermore, hepatocyte TLR5 inhibition abrogates paracrine activation of hepatic stellate cells to suppress collagen production. This is also seen ex vivo in patient-derived precision-cut liver slices where TLR5 inhibition significantly reduces lipid-induced collagen deposition. These findings reveal a new role for TLR5 signalling, specifically in the development of advanced MASH fibrosis and may offer a novel disease-specific therapeutic approach.

molecular biology↗

bioRxiv2025

Decoding MASLD Progression: A Molecular Trajectory-Based Framework for Modelling Disease Dynamics

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) has emerged as a silent pandemic, affecting nearly one-third of the global population. MASLD encompasses a spectrum of liver disorders, ranging from simple steatosis to Metabolic Dysfunction-Associated Steatohepatitis (MASH), characterised by lipotoxicity, hepatocellular injury, inflammation, and fibrosis, which can eventually progress to cirrhosis and hepatocellular carcinoma. Despite the progressive nature of MASLD/MASH, current research and clinical practice primarily rely on static, histopathology-defined stages that fail to capture the continuous nature of disease progression. Here, we present an integrative framework that combines patient pseudo-temporal ordering, network analysis, and cell-type deconvolution to reconstruct the continuous MASLD/MASH trajectory. By analysing patient liver transcriptomic profiles, we position patients along this data-driven trajectory, moving beyond conventional stage-based classifications. This approach reveals the sequence of critical molecular events underlying MASLD/MASH progression, providing mechanistic insights into the diseases pathophysiology. By integrating these findings with plasma proteomics data, we identify novel trajectory-specific plasma biomarkers that predict disease stage (and trajectory position) independently of histology. Together, these findings demonstrate the value of trajectory-based frameworks for understanding MASLD pathophysiology and highlight new opportunities for precision diagnosis and therapeutic target prioritisation across the disease spectrum.

systems biology↗

bioRxiv2024

Chronic inorganic nitrate supplementation does not improve metabolic health and worsens disease progression in mice with diet-induced obesity.

Inorganic nitrate (NO3-) has been proposed to be of therapeutic use as a dietary supplement in obesity and related conditions including the Metabolic Syndrome (MetS), type-II diabetes and metabolic dysfunction associated steatotic liver disease (MASLD). Administration of NO3- to endothelial nitric oxide synthase-deficient mice reversed aspects of MetS, however the impact of NO3- supplementation in diet-induced obesity is not well understood. Here we investigated the whole-body metabolic phenotype and cardiac and hepatic metabolism in mice fed a high-fat high-sucrose (HFHS) diet for up to 12-months of age, supplemented with 1 mM NaNO3 (or NaCl) in their drinking water. HFHS-feeding was associated with a progressive obesogenic and diabetogenic phenotype, which was not ameliorated by NO3-. Furthermore, HFHS-fed mice supplemented with NO3- showed elevated levels of cardiac fibrosis, and accelerated progression of MASLD including development of hepatocellular carcinoma in comparison with NaCl-supplemented mice. NO3- did not enhance mitochondrial {beta}-oxidation capacity in any tissue assayed and did not suppress hepatic lipid accumulation, suggesting it does not prevent lipotoxicity. We conclude that NO3- is ineffective in preventing the metabolic consequences of an obesogenic diet and may instead be detrimental to metabolic health against the background of HFHS-feeding. This is the first report of an unfavorable effect of long-term nitrate supplementation in the context of the metabolic challenges of overfeeding, warranting urgent further investigation into the mechanism of this interaction. New & NoteworthyInorganic nitrate has been suggested to be of therapeutic benefit in obesity-related conditions as it increases nitric oxide bioavailability, enhances mitochondrial {beta}-oxidation and reverses Metabolic Syndrome in eNOS-/- mice. However, we here show that over 12 months, nitrate was ineffective in preventing metabolic consequences in high-fat high-sucrose fed mice, and worsened aspects of metabolic health, impairing cholesterol handling, increasing cardiac fibrosis, and exacerbating steatotic liver disease progression, with acceleration to hepatocellular carcinoma.

physiology↗

bioRxiv2023

Sustained liver HBsAg loss and clonal T and B cell expansion upon therapeutic DNA vaccination require low HBsAg levels

Background & AimsSuppression of HBV DNA, inhibition of HBsAg production and therapeutic vaccination to reverse HBV-specific T-cell exhaustion in chronic HBV patients are likely required to achieve functional cure. In the AAV-HBV mouse model, therapeutic vaccination can be effective in clearing HBsAg when hepatitis B surface (HBsAg) levels are low. The factor(s) required for mounting an effective immune control of HBV infection are unclear. Using a single-cell approach, we investigated the liver immune environment in the context of different levels of HBsAg as well as upon sustained HBsAg loss through treatment with an HBV specific GalNAc-siRNA followed by therapeutic vaccination. MethodsC57BL/6 mice were transduced with a range of rAAV-HBV DNA to express different HBsAg levels. Mice were treated with GalNAc-siRNA targeting HBV transcripts to lower the HBsAg levels and then vaccinated 4 times with a DNA vaccine encoding HBV Core, Pol and Surface. We used single-cell RNA-sequencing on homogenised liver resident cells, paired with single-cell V(D)J receptor sequencing to understand the changes in the liver immune microenvironment. ResultsTreatment with GalNAc-HBV siRNA followed by therapeutic vaccination, achieved a sustained HBsAg loss in all mice. This was accompanied by an induction of CD4 follicular helper T-cell responses, polyclonal activation of CD8 T-cells in the liver and clonal expansion of plasma cells that were responsible for antibody production. ConclusionsThis study provides novel insight into the immune changes in the liver at the single-cell level, highlighting the correlation between the induced reduction in HBsAg levels and the clonal expansion of CD4 follicular helper T-cells, CD8 cytotoxic T-cells, plasma cells, and ISG-producing neutrophils in the liver upon HBV siRNA and subsequent therapeutic vaccine treatment. Lay SummaryChronic hepatitis B infection is characterized by a complex interplay between immune responses and viral replication in the liver. To achieve functional cure a combination of different treatments is likely required. In this study single-cell approach was used to understand the liver microenvironment in the context of different HBsAg levels followed by therapeutic vaccination in AAV-HBV mouse model and to identify key factors required to achieve functional cure. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/556204v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@5776a4org.highwire.dtl.DTLVardef@2e1b9forg.highwire.dtl.DTLVardef@1179a2eorg.highwire.dtl.DTLVardef@8b801d_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIAAV-HBV transduced mice sequentially treated with GalNAc-siRNA and therapeutic vaccine showed sustained HBsAg loss. C_LIO_LIThe sustained HBsAg loss correlates with increased proportion and clonal expansion of CD4 follicular helper T-cells, CD8 cytotoxic T-cells, plasma cells, and ISG producing neutrophils in the liver. C_LIO_LIBaseline levels of HBsAg are important to determine outcome of therapeutic vaccination in mice. C_LI

immunology↗

bioRxiv2022

HAPLN1 is a driver for peritoneal carcinomatosis in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) frequently metastasizes into the peritoneum, which contributes to poor prognosis. Metastatic spreading is promoted by cancer cell plasticity, yet its regulation by the microenvironment is incompletely understood. Here we show that the presence of hyaluronan and proteoglycan link protein-1 (HAPLN1) in the extracellular matrix enhances tumor cell plasticity and PDAC metastasis. Bioinformatic analysis showed that HAPLN1 expression is enriched in the basal PDAC subtype and associated with worse overall patient survival. In a mouse model for peritoneal carcinomatosis, HAPLN1-induced immunomodulation favored a more permissive microenvironment, which accelerated the peritoneal spread of tumor cells. Mechanistically, HAPLN1, via hyaluronic acid synthesis and signaling, promoted adoption of a highly plastic cancer cell state, facilitating EMT, stemness, invasion and immunomodulation in a paracrine manner. Extracellular HAPLN1 modifies cancer cells as well as fibroblasts, rendering them immunomodulatory. We identify HAPLN1 as a prognostic marker and a driver for peritoneal metastasis in PDAC.

cancer biology↗

bioRxiv2021

Early neutrophilia marked by aerobic glycolysis sustains host metabolism and delays cancer cachexia

An elevated neutrophil-to-lymphocyte ratio negatively predicts the outcome of patients with cancer and is associated with cachexia, the terminal wasting syndrome. Here, we show using murine model systems of colorectal and pancreatic cancer that neutrophilia in the circulation and multiple organs, accompanied by extramedullary hematopoiesis, is an early event during cancer progression. Transcriptomic and metabolic assessment reveals that neutrophils in tumor-bearing animals utilize aerobic glycolysis, alike to cancer cells. Although pharmacological inhibition of aerobic glycolysis slows down tumor growth in C26 tumor-bearing mice, it precipitates cachexia, thereby shortening overall survival. This negative effect may be explained by our observation that acute depletion of neutrophils in pre-cachectic mice impairs systemic glucose homeostasis secondary to altered hepatic lipid processing. Thus, changes in neutrophil number, distribution and metabolism play an adaptive role in host metabolic homeostasis during cancer progression. Our findings provide insight into early events during cancer progression to cachexia, with implications for therapy.

cancer biology↗

bioRxiv2021

Semaphorin 3C exacerbates liver fibrosis

Background & AimsChronic liver disease is a growing epidemic leading to fibrosis and cirrhosis. TGF-{beta} is the pivotal pro-fibrogenic cytokine which activates hepatic stellate cells (HSC), yet, other molecules can substantially modulate TGF-{beta} signaling in the course of liver fibrosis. Expression of the axon guidance molecules Semaphorins (SEMAs), which signal through Plexins and Neuropilins (NRPs), have been associated with liver fibrosis in HBV-induced chronic hepatitis. This study aims at determining their function in the regulation of HSCs. Approach & ResultsWe analyzed publicly available patient databases and liver biopsies. We employed transgenic mice where genes are deleted only in activated HSCs to perform ex vivo analysis and animal models. SEMA3C is the most enriched member of the Semaphorin family in liver samples from cirrhotic patients. Higher expression of SEMA3C in patients with NASH, alcoholic hepatitis or HBV-induced hepatitis discriminates those with a more pro-fibrotic transcriptomic profile. SEMA3C expression is also elevated in different mouse models of liver fibrosis and in isolated HSCs upon activation. In keeping with this, deletion of SEMA3C in activated HSCs reduces myofibroblast marker expression. Conversely, SEMA3C overexpression exacerbates TGF-{beta}-mediated myofibroblast activation, as shown by increased SMAD2 phosphorylation and target gene expression. Among SEMA3C receptors, only NRP2 expression is maintained upon activation of isolated HSCs. Interestingly, lack of NRP2 in those cells reduces myofibroblast marker expression. Finally, deletion of either SEMA3C or NRP2, specifically in activated HSCs, reduces liver fibrosis in mice. ConclusionSEMA3C is a novel marker for activated HSCs that plays a fundamental role in the acquisition of the myofibroblastic phenotype and liver fibrosis.

pathology↗

bioRxiv2020

Extreme phenotypes define epigenetic and metabolic signatures in cardiometabolic syndrome.

Improving the understanding of cardiometabolic syndrome pathophysiology and its relationship with thrombosis are ongoing healthcare challenges. Using plasma biomarkers analysis coupled with the transcriptional and epigenetic characterisation of cell types involved in thrombosis, obtained from two extreme phenotype groups (obese and lipodystrophy) and comparing these to lean individuals and blood donors, the present study identifies the molecular mechanisms at play, highlighting patterns of abnormal activation in innate immune phagocytic cells and shows that extreme phenotype groups could be distinguished from lean individuals, and from each other, across all data layers. The characterisation of the same obese group, six months after bariatric surgery shows the loss of the patterns of abnormal activation of innate immune cells previously observed. However, rather than reverting to the gene expression landscape of lean individuals, this occurs via the establishment of novel gene expression landscapes. Netosis and its control mechanisms emerge amongst the pathways that show an improvement after surgical intervention. Taken together, by integrating across data layers, the observed molecular and metabolic differences form a disease signature that is able to discriminate, amongst the blood donors, those individuals with a higher likelihood of having cardiometabolic syndrome, even when not presenting with the classic features.

genomics↗

bioRxiv2020

Macrophage Scavenger Receptor 1 mediates lipid-induced inflammation in non-alcoholic fatty liver disease

Obesity-associated inflammation is a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the exact mechanisms remain incompletely understood. Here we demonstrate that macrophage scavenger receptor 1 (MSR1, CD204) expression is associated with the occurrence of hepatic lipid-laden foamy macrophages and correlates with the degree of steatosis and steatohepatitis in a cohort of 170 NAFLD patients. Mice lacking Msr1 are protected against high fat-cholesterol diet (HFD)-induced metabolic disorder, showing fewer hepatic lipid-laden foamy macrophages, less hepatic inflammation, improved dyslipidemia and glucose tolerance, while showing a change in hepatic lipid metabolism. We show that MSR1 induces a pro-inflammatory response via the JNK signaling pathway upon triggering by saturated fatty acids. In vitro blockade of the receptor prevented the accumulation of lipids in primary macrophages which inhibited the switch towards a pro-inflammatory phenotype and the release of cytokines such as TNFa. Targeting MSR1 using monoclonal antibody therapy in an obesity-associated NAFLD mouse model and ex vivo human liver slices resulted in the prevention of foamy macrophage formation and liver inflammation. Moreover, we identified that rs41505344, a polymorphism in the upstream transcriptional region of MSR1, was associated with altered serum triglycerides and aspartate transaminase levels in a cohort of over 400,000 patients. Taken together, our data suggest a critical role for MSR1 in lipid homeostasis and a potential therapeutic target for the treatment of NAFLD. One Sentence SummaryThe immunometabolic role of MSR1 in human NAFLD.

immunology↗