Cinzia Signorini - Academia.edu (original) (raw)

Papers by Cinzia Signorini

Frontiers in Neurology

BackgroundBreathing abnormalities are common in Rett syndrome (RTT), a pervasive neurodevelopment... more BackgroundBreathing abnormalities are common in Rett syndrome (RTT), a pervasive neurodevelopmental disorder almost exclusively affecting females. RTT is linked to mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Our aim was to assess the clinical relevance of apneas during sleep-wakefulness cycle in a population with RTT and the possible impact of apneas on circulating oxidative stress markers.MethodsFemale patients with a clinical diagnosis of typical RTT (n = 66), MECP2 gene mutation, and apneas were enrolled (mean age: 12.5 years). Baseline clinical severity, arterial blood gas analysis, and red blood cell count were assessed. Breathing was monitored during the wakefulness and sleep states (average recording time: 13 ± 0.5 h) with a portable polygraphic screening device. According to prevalence of breath holdings, the population was categorized into the wakefulness apnea (WA) and sleep apnea (SA) groups, and apnea-hypopnea index (AHI) was calculated. The impact of res...

Previous studies suggested a relation between oxidative stress and collagen hyperproduction. Carb... more Previous studies suggested a relation between oxidative stress and collagen hyperproduction. Carbon tetrachloride-induced hepatic fibrosis has been considered to be mediated by aldehydic lipid peroxidation products. In the present study we investigated whether collagen synthesis is induced by F 2 -isoprostanes, the most proximal products of lipid peroxidation and known mediators of impor- tant biological effects. By contrast with aldehydes, F 2 -isoprostanes act through receptors able to elicit definite signal transduction pathways. In a rat model of carbon tetrachloride-induced hepatic fibrosis, plasma F 2 -isoprostanes were mark- edly elevated for the entire experimental period; hepatic collagen content also increased. When hepatic stellate cells from normal liver were cultured up to acti- vation (expression of α-SMA) with F 2 -isoprostanes in the concentration range found in the in vivo studies (10 �9 to 10 �8 M), a striking increase in DNA synthesis, in cell proliferation and in...

Introduzione. Precedenti studi hanno suggerito che la fibrosi epatica indotta da tetracloruro di ... more Introduzione. Precedenti studi hanno suggerito che la fibrosi epatica indotta da tetracloruro di carbonio (CCl4) possa essere legata allo stress ossidativo (SO). In effetti è stato riportato che la perossidazione lipidica indotta in vitro nelle cellule stellate epatiche (HSC) (1) o il trattamento di quest’ultime con 4-idrossinonenale (HNE) o malondialdeide (2), stimola l’espressione del gene per il procollagene. Inoltre nell’intossicazione cronica con CCl4 si ha un aumento dell’mRNA per il TGFβ nelle cellule non parenchimali fra le quali le HSC rappresentano la più importante sorgente di produzione di collagene (3). Gli F2-Isoprostani (F2-Iso), i prodotti più prossimali dell’acido arachidonico e i più attendibili markers dello SO, sono anche mediatori di importanti effetti biologici, come l’effetto vasocostrittore sulle arteriole glomerulari renali (effetto mediato da recettori analoghi a quelli per il trombossano A2) e di altri effetti. Pertanto nel presente studio abbiamo valutato se la sintesi del collagene possa essere indotta dagli F2-Iso, i quali, differentemente dalle aldeidi, presentano recettori capaci di mettere in moto definite vie di trasduzione del segnale. Abbiamo pertanto condotto uno studio in vivo su ratti intossicati con CCl4 e parallelamente uno studio in vitro su colture di HSC trattate con gli stessi livelli F2-Iso ritrovati in vivo. Materiali e Metodi. Gli F2-Iso plasmatici sono stati valutati per mezzo di gas cromatografia/spettrometria di massa tandem con trappola ionica. Il contenuto totale di collagene è stato determinato dal livello di idrossiprolina in idrolisati tissutali. Le HSC sono state preparate da fegato normale di ratto per mezzo di digestioni sequenziali con pronasi/collagenasi (4). Le HSC attivate sono state trattate con diverse dosi di F2-Iso. La valutazione del TGF-1 è stata effettuata per mezzo di un metodo ELISA. Risultati e Discussione. Nel modello di fibrosi epatica indotta da CCl4 i livelli di F2-Iso plasmatici sono elevati per tutto il periodo sperimentale e sono strettamente correlati al contenuto di collagene epatico. Quando le HSC in coltura vengono trattate con F2-Iso esattamente nel range delle concentrazioni ritrovate negli studi in vivo (10-9-10-8 M), si osserva un marcato incremento (2-4 volte) nella proliferazione cellulare (valutata dall’incorporazione di timidina triziata) e della sintesi di collagene (valutata dall’incorporazione di prolina triziata). La produzione relativa di collagene, cioè la percentuale di produzione del collagene sulla produzione di proteine totali (proteine collageniche e non collageniche) è anch’essa fortemente aumentata (3,5 volte), così come è aumentato il contenuto totale di collagene. Il trattamento con F2-Iso (10-9-10-7 M) di colture di cellule di linea promonocitica umana, le cellule U937, assunte come corrispettivo di cellule di Kupffer o di macrofagi epatici, produce un significativo aumento della sintesi del TGF-1. In vista dei numerosi effetti biologici presentati dagli F2-Iso, viene proposta l’ipotesi che gli F2-Iso, generati dalla perossidazione lipidica negli epatociti, possano mediare la proliferazione delle HSC e la iperproduzione di collagene che si osserva nella fibrosi epatica

In CCl4 induced hepatotoxicity, besides steatonecrosis, fibrosis also develops which evolves to c... more In CCl4 induced hepatotoxicity, besides steatonecrosis, fibrosis also develops which evolves to cirrhosis. Such fibrosis may be linked to oxidative stress. In fact, lipid peroxidation induced in vitro in hepatic stellate cells (HSC, the major source of matrix proteins) or the treatment of the latter with 4-hydroxynonenal or malonaldehyde stimulates expression of procollagen gene and synthesis of TGFbeta1. F2-isoprostanes (F2-Iso) are considered the most reliable markers of oxidative stress and are also mediators of important biological effects. Since aldehydic lipid peroxidation products seem to induce collagen expression, we have investigated whether analogue effects are induced by F2-Iso, which present receptors able to elicit definite signal transduction pathways. In a rat model of chronic CCl4 intoxication leading to fibrosis, plasma F2-Iso were elevated for the entire experimental period. HSC from normal liver were cultured up to activation and then treated for 48 h with F2-Iso in the range of the concentrations found in the in vivo studies (10-8 to 10-9M). F2-Iso induced marked increase in cell proliferation as well as increase in collagen synthesis. Total collagen content was similarly increased. Therefore, F2-Iso generated by lipid peroxidation in hepatocytes may mediate the HSC proliferation and collagen hyperproduction seen in hepatic fibrosis

Free Radical Biology and Medicine, 2018

F 2-isoprostanes (F 2-IsoPs) have been considered markers of oxidative stress in various pulmonar... more F 2-isoprostanes (F 2-IsoPs) have been considered markers of oxidative stress in various pulmonary diseases, but little is known about their possible role in pulmonary fibrosis. In this study, we have investigated the potential key role of F 2-IsoPs as markers and mediators of bleomycin (BLM)-induced pulmonary fibrosis in rats. During the in vivo study, plasma F 2-IsoPs showed a peak at 7 days and remained elevated for the entire experimental period. Lung F 2-IsoP content nearly tripled 7 days following the intratracheal instillation of BLM, and by 28 days, the value increased about fivefold compared to the controls. Collagen deposition correlated with F 2-IsoP content in the lung. Furthermore, from day 21 onwards, lung sections from BLM-treated animals showed α-smooth muscle actin (α-SMA) positive cells, which were mostly evident at 28 days. In vitro studies performed in rat lung fibroblasts (RLF) demonstrated that either BLM or F 2-IsoPs stimulated both cell proliferation and collagen synthesis. Moreover, RLF treated with F 2-IsoPs showed a significant increase of α-SMA expression compared to control, indicating that F 2-IsoPs can readily activate fibroblasts to myofibroblasts. Our data demonstrated that F 2-IsoPs can be mediators of key events for the onset and development of lung fibrosis, such as cell proliferation, collagen synthesis and fibroblast activation. Immunocytochemistry analysis, inhibition and binding studies demonstrated the presence of the thromboxane A 2 receptor (TP receptor) on lung fibroblasts and suggested that the observed effects may be elicited through the binding to this receptor. Our data added a new perspective on the role of F 2-IsoPs in lung fibrosis by providing evidence of a profibrotic role for these mediators in the pathogenesis of pulmonary fibrosis.

Free Radical Research, 2016

IsoPs, F 2-dihomo-isoprostanes; F 2-IsoPs, F 2-Isoprostanes; F 4-Neuro-Ps, F 4-neuroprostanes; IE... more IsoPs, F 2-dihomo-isoprostanes; F 2-IsoPs, F 2-Isoprostanes; F 4-Neuro-Ps, F 4-neuroprostanes; IE-NPBI, intraerythrocyte non-protein bound iron; IREs, iron responsive elements; NPBI, nonprotein bound iron; OS, oxidative stress; P-NPBI, plasma non-protein bound iron; RBC, erythrocytes; RCPM, Raven's colored progressive matrices; ROS, reactive oxygen species; STI, serum total iron; tert-BHP, tert-butyl hydroperoxide; TIBC, total iron-binding capacity.

Neurochemical Research, 2009

Nerve cells are very susceptible to hypoxia responsive for mitochondrial dysfunctions involved in... more Nerve cells are very susceptible to hypoxia responsive for mitochondrial dysfunctions involved in the subsequent oxidative stress, apoptosis and necrosis. In this paper, we examined the effect of 12 h incubation of U-373 MG astrocytes in hypoxic environment (73% N(2): 2% O(2): 5% CO(2), v:v) by evaluating cell proliferation, modifications of NO and ATP production, intracellular Ca(2+) concentration [Ca(2+)](i), membrane potential, desferoxamine-chelatable free iron, esterified F2-isoprostanes levels and the production of phosphorylated ERK. The same parameters were evaluated also after a following re-oxygenation period of 24 h. Immediately after hypoxia the NO concentration increased significantly and returned to values similar to those of controls after the re-oxygenation period. At the same time, ATP levels remained similar to controls and the cell proliferation significantly decreased. This involved a significant increase of [Ca(2+)](i) immediately after hypoxia and the value remained significantly elevated after the following re-oxygenation period. Moreover, after hypoxia, astrocytes were slightly although not significantly depolarized. Indeed iron and F2-isoprostanes levels increased significantly after hypoxia. Finally ERK proteins increased slowly and not significantly after hypoxia and the same trend was observed after the re-oxygenation period. On the whole, our results indicate that 2% O(2) hypoxia induces a moderate oxidative stress, well tolerated by U-373 MG cells, remaining the ATP production, mitochondrial membrane potential and activated ERK proteins, similar to the values of controls.

Free Radical Research, 2008

Increased oxidative stress and decreased life span of erythrocytes (RBCs) are repeatedly reported... more Increased oxidative stress and decreased life span of erythrocytes (RBCs) are repeatedly reported in diabetes. In the aim to elucidate the mechanism of the latter, i.e. the events leading to erythrocyte ageing, this study determined in RBCs from diabetic patients iron release in a free desferrioxamine-chelatable form (DCI), methemoglobin (MetHb) formation, binding of autologous IgG to membrane proteins and in plasma non-protein-bound iron (NPBI), F(2)-Isoprostanes (F(2)-IsoPs) and advanced oxidation protein products (AOPP). DCI and MetHb were higher in diabetic RBCs than in controls and autologous IgG binding occurred in a much higher percentage of diabetic patients than controls. A significant correlation between DCI and IgG binding was found in diabetic RBCs. Plasma NPBI, esterified F(2)-IsoPs and AOPP were higher in diabetic patients and a significant correlation was found between plasma NPBI and intra-erythrocyte DCI. The increased DCI and autologous IgG binding appear to be important factors in the accelerated removal of RBCs from the blood stream in diabetes and the increase in plasma NPBI could play an important role in the increased oxidative stress.

Free Radical Biology and Medicine, 2008

F(2)-isoprostanes are not just markers of oxidative stress. The discovery of F(2)-isoprostanes (F... more F(2)-isoprostanes are not just markers of oxidative stress. The discovery of F(2)-isoprostanes (F(2)-IsoPs) as specific and reliable markers of oxidative stress in vivo is briefly summarized here. F(2)-IsoPs are also agonists of important biological effects, such as the vasoconstriction of renal glomerular arterioles, the retinal vessel, and the brain microcirculature. In addition to the F(2)-IsoPs, E(2)- and D(2)-IsoPs can be formed by rearrangement of H(2)-IsoP endoperoxides and can give rise to cyclopentenone IsoPs, which are very reactive alpha,beta-unsaturated aldehydes. The same type of reactivity is also shown by acyclic gamma-ketoaldehydes formed as products of the IsoP pathway. Because previous studies suggested a relation between oxidative stress and collagen hyperproduction, it was investigated whether collagen synthesis is induced by F(2)-IsoPs, the most proximal products of lipid peroxidation. In contrast to aldehydes, F(2)-IsoPs act through receptors able to elicit definite signal transduction pathways. In a rat model of carbon tetrachloride-induced hepatic fibrosis, plasma F(2)-IsoPs were markedly elevated for the entire experimental period; hepatic collagen content was also increased. When hepatic stellate cells from normal liver were cultured up to activation (expression of smooth muscle alpha-actin) and then treated with F(2)-IsoPs in the concentration range found in the in vivo studies (10(-9) to 10(-8) M), a striking increase in DNA synthesis, cell proliferation, and collagen synthesis was observed. Total collagen content was similarly increased. All these stimulatory effects were reversed by the specific antagonist of the thromboxane A(2) receptor, SQ 29 548, whereas the receptor agonist, I-BOP, also had a stimulatory effect. Therefore F(2)-IsoPs generated by lipid peroxidation in hepatocytes may mediate hepatic stellate cell proliferation and collagen hyperproduction seen in hepatic fibrosis.

FEBS Letters, 1995

The aerobic incubation of erythrocytes in phosphate buffer for 24–60 h (a model of rapid in vitro... more The aerobic incubation of erythrocytes in phosphate buffer for 24–60 h (a model of rapid in vitro ageing) induced progressive iron release and methemoglobin formation. Membrane proteins showed electrophoretic alterations and increase in carbonyl groups (as documented by IR spectroscopy). None of these phenomena were seen when the erythrocytes were incubated under anaerobic conditions. The membranes from aerobically incubated cells bound a much higher amount of autologous IgG than those from anaerobically incubated ones, suggesting that the aerobic incubation gives rise to the senescent antigen. The addition of ferrozine during the aerobic incubation prevented both the IgG binding and the protein alterations seen in the IR spectra, suggesting an intracellular chelation of the released iron by ferrozine.

Mediators of inflammation, 2017

Rett syndrome (RTT) is a rare neurodevelopmental disorder usually caused by mutations in the X-li... more Rett syndrome (RTT) is a rare neurodevelopmental disorder usually caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). Several Mecp2 mutant mouse lines have been developed recapitulating part of the clinical features. In particular, Mecp2-308 female heterozygous mice, bearing a truncating mutation, are a validated model of the disease. While recent data suggest a role for inflammation in RTT, little information on the inflammatory status in murine models of the disease is available. Here, we investigated the inflammatory status by proteomic 2-DE/MALDI-ToF/ToF analyses in symptomatic Mecp2-308 female mice. Ten differentially expressed proteins were evidenced in the Mecp2-308 mutated plasma proteome. In particular, 5 positive acute-phase response (APR) proteins increased (i.e., kininogen-1, alpha-fetoprotein, mannose-binding protein C, alpha-1-antitrypsin, and alpha-2-macroglobulin), and 3 negative APR reactants were decreased (i.e., serotransferrin, albumin,...

Antioxidants

Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aer... more Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aerobic metabolism. Below a certain threshold, ROS are important in signal transduction pathways and cellular physiological processes, whereas ROS overproduction damages spermatozoa. Sperm manipulation and preparation protocols during assisted reproductive procedures—for example, cryopreservation—can result in excessive ROS production, exposing these cells to oxidative damage. Thus, antioxidants are a relevant topic in sperm quality. This narrative review focuses on human spermatozoa as an in vitro model to study which antioxidants can be used to supplement media. The review comprises a brief presentation of the human sperm structure, a general overview of the main items of reduction–oxidation homeostasis and the ambivalent relationship between spermatozoa and ROS. The main body of the paper deals with studies in which human sperm have been used as an in vitro model to test antioxidant comp...

Life, 2021

Inflammatory and immune processes are defensive mechanisms that aim to remove harmful agents. As ... more Inflammatory and immune processes are defensive mechanisms that aim to remove harmful agents. As a response to infections, inflammation and immune response contribute to the pathophysiological mechanisms of diseases. Coronavirus disease 2019 (COVID-19), whose underlying mechanisms remain not fully elucidated, has posed new challenges for the knowledge of pathophysiology. Chiefly, the inflammatory process and immune response appear to be unique features of COVID-19 that result in developing a hyper-inflammatory syndrome, and air pollution, the world’s largest health risk factor, may partly explain the behaviour and fate of COVID-19. Understanding the mechanisms involved in the progression of COVID-19 is of fundamental importance in order to avoid the late stage of the disease, associated with a poor prognosis. Here, the role of the inflammatory and immune mediators in COVID-19 pathophysiology is discussed.

Journal of Neurodevelopmental Disorders, 2020

Background Rett syndrome (RTT), an X-linked neurodevelopmental rare disease mainly caused by MECP... more Background Rett syndrome (RTT), an X-linked neurodevelopmental rare disease mainly caused by MECP2-gene mutations, is a prototypic intellectual disability disorder. Reversibility of RTT-like phenotypes in an adult mouse model lacking the Mecp2-gene has given hope of treating the disease at any age. However, adult RTT patients still urge for new treatments. Given the relationship between RTT and monoamine deficiency, we investigated mirtazapine (MTZ), a noradrenergic and specific-serotonergic antidepressant, as a potential treatment. Methods Adult heterozygous-Mecp2 (HET) female mice (6-months old) were treated for 30 days with 10 mg/kg MTZ and assessed for general health, motor skills, motor learning, and anxiety. Motor cortex, somatosensory cortex, and amygdala were analyzed for parvalbumin expression. Eighty RTT adult female patients harboring a pathogenic MECP2 mutation were randomly assigned to treatment to MTZ for insomnia and mood disorders (mean age = 23.1 ± 7.5 years, range ...

Biochemical Journal, 1992

Mouse erythrocytes were incubated with oxidizing agents, phenylhydrazine, divicine and isouramil.... more Mouse erythrocytes were incubated with oxidizing agents, phenylhydrazine, divicine and isouramil. With all the oxidants a rapid release of iron in a desferrioxamine (DFO)-chelatable form was seen and it was accompanied by methaemoglobin formation. If the erythrocytes were depleted of GSH by a short preincubation with diethyl maleate, the release of iron was accompanied by lipid peroxidation and, subsequently, haemolysis. GSH depletion by itself did not induce iron release, methaemoglobin formation, lipid peroxidation or haemolysis. Rather, the fate of the cell in which iron is released depended on the intracellular availability of GSH. In addition, iron release was higher in depleted cells than in native ones, suggesting a role for GSH in preventing iron release when oxidative stress is imposed by the oxidants. Iron release preceded lipid peroxidation. The latter was prevented when the erythrocytes were preloaded with DFO in such a way (preincubation with 10 mM-DFO) that the intrace...

Free Radical Biology and Medicine, 2014

Atherosclerosis is a chronic inflammatory disorder occurs as a result of mononuclear lymphocyte i... more Atherosclerosis is a chronic inflammatory disorder occurs as a result of mononuclear lymphocyte infiltration to the arterial wall accompanied by smooth muscle cell proliferation and damage in the arterial wall caused by extracellular matrix accumulation. Besides several genetic and environmental factors, increased serum cholesterol and oxidized low density lipoproteins are considered to be major risk factors of the disease. During atherosclerosis, lipoproteins such as LDL become trapped at the site of lesion and are converted to oxLDL. Smooth muscle cells become activated by oxLDL, start to proliferate, and migrate into the intima of the arterial wall. OxLDL provokes a cascade of cellular responses at the atherosclerotic lesion, ultimately leading to formation of atherosclerotic plaques. In this process, scavenger receptors could play a critical role because of their ability to bind oxLDL and their function in transporting lipids and cholesterol into and out of the cells. Scavenger receptors are expressed on macrophages and foam cells in atherosclerotic lesions. CD36 is the most important one among them playing role in atherosclerotic process. CD36 is a raft associated glycosylated protein with an 88 kDa molecular weight and various ligands such as oxLDL, apoptotic cells, advanced glycation end products bind to this receptor. It has been shown that mice knockouts for the apolipoprotein E exhibited a marked decrease in atherosclerotic lesions if CD36 gene was made inactive. Previously we have shown that the aortas of cholesterol-fed rabbits showed typical atherosclerotic lesions, detected by macroscopic and microscopic examination, and exhibited an increase in CD36 mRNA expression. In this study, we planned to compare CD36 mRNA expressions in the aortic tissue and peripheral blood mononuclear cells in cholesterol induced atherosclerosis. Our results suggests that CD36 mRNA levels in peripheral blood mononuclear cells reflect the levels in aorta and this might be used as a marker for diagnosis of atherosclerosis.

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 2012

The aim of this study was to test the value of F 2-isoprostane (F 2-IsoP) levels in the pericoron... more The aim of this study was to test the value of F 2-isoprostane (F 2-IsoP) levels in the pericoronal gingiva as a potential predictor of oral disability after mandibular third molar (M3M) surgery. Study design. Thirteen patients (5 male, 8 female) with partially impacted M3M were enrolled. Pericoronal soft tissues histology was obtained, gingival F 2-IsoPs were measured by gas chromatography/negative-ion chemical ionization tandem mass spectrometry, and health-related quality of life (HRQOL) scores were assessed. Results. A variable degree of pericoronitis was evident before the M3M surgery, with a mean level of pericoronal F 2-IsoPs of 634.8 Ϯ 193.5 pg/mg of tissue. A significant positive correlation between pericoronal F 2-IsoPs and HRQOL was observed in male (r s ϭ 0.440; P ϭ .0011), but not female (r s ϭ Ϫ0.062; P ϭ .5124) patients. Conclusions. Levels of F 2-IsoPs in the pericoronal soft tissues are correlated with the degree of oral disability after M3Ms surgery in male, but not female, patients.

Neurochemical Research, 2010

Nervous system cells are highly dependent on adequate tissue oxygenation and are very susceptible... more Nervous system cells are highly dependent on adequate tissue oxygenation and are very susceptible to hypoxia, which causes mitochondrial dysfunctions involved in apoptosis and necrosis. In this paper, we examine the effect of a 12-h incubation of differentiated IMR-32 neuroblastoma cells in a hypoxic environment (73% N(2): 2% O(2): 5% CO(2), v:v) by evaluating cell viability, modifications of NO, intracellular Ca(2+) concentration [Ca(2+)](i) and membrane potential, the production of phosphorylated ERK, desferoxamine-chelatable free iron and esterified F2-isoprostane levels. The same parameters were evaluated after a subsequent 24-h re-oxygenation period. The NO concentration increased significantly immediately after hypoxia and returned to values similar to those of controls after the reoxygenation period. At the same time, we observed a significant increase of [Ca(2+)](i) immediately after hypoxia. Phosphorylated ERK proteins increased significantly during the first 2 h of hypoxia, then decreased, and remained practically unmodified after 12 h hypoxia and the following reoxygenation period. Moreover, IMR-32 cell mitochondria were significantly depolarized after hypoxia, while membrane potential returned to normal after the reoxygenation period. Finally, desferoxamine-chelatable free iron and F2-isoprostane levels also increased significantly after hypoxia. Our results indicate that 2% O(2) hypoxia induces variations of NO and [Ca(2+)](i) with subsequent mitochondrial depolarization, and it is responsible for oxidative stress, represented by increased free iron and F2-isoprostane, protein carbonyls and 4 hydroxynonenal protein adducts levels.

Molecular Aspects of Medicine, 2008

After a brief introduction to oxidative stress, the discovery of F 2-isoprostanes as specific and... more After a brief introduction to oxidative stress, the discovery of F 2-isoprostanes as specific and reliable markers of oxidative stress is described. Isoprostanes are also agonists of important biological effects. Since a relation between oxidative stress and collagen hyperproduction has been previously suggested and since lipid peroxidation products have been proposed as possible mediators of liver fibrosis, we investigated whether collagen synthesis is induced by F 2-isoprostanes the most proximal products of lipid peroxidation. In a rat model of carbon tetrachloride-induced hepatic fibrosis, plasma isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content was also increased. When hepatic stellate cells from normal liver were cultured up to activation (expression of a-smooth muscle-alpha actin) and then treated with F 2-isoprostanes in the concentration range found in the in vivo studies (10 À9-10 À8 M), a striking increase in DNA synthesis, in cell proliferation and in collagen synthesis was observed. Moreover, F 2-isoprostanes increased the production of transforming growth factor-b1 by U937 cells, assumed as a model of Kupffer cells or liver macrophages. The data suggest the possibility that F 2-isoprostanes generated by lipid peroxidation in hepatocytes mediate hepatic stellate cell proliferation and collagen hyperproduction seen in hepatic fibrosis.