Heparanase and macrophage interplay in the onset of liver fibrosis

Abstract The heparan sulfate endoglycosidase heparanase (HPSE) is involved in tumor growth, chronic inflammation and fibrosis. Since a role for HPSE in chronic liver disease has not been demonstrated to date, the current study was aimed at investigating the involvement of HPSE in the pathogenesis of chronic liver injury. Herein, we revealed that HPSE expression increased in mouse livers after carbon tetrachloride (CCl4)-mediated chronic induction of fibrosis, but with a trend to decline during progression of the disease. In mouse fibrotic liver tissues HPSE immunostaining was restricted in necro-inflammatory areas, co-localizing with F4/80 macrophage marker and TNF-α. TNF-α treatment induced HPSE expression as well as HPSE secretion in U937 macrophages. Moreover, macrophage-secreted HPSE regulated the expression of α-SMA and fibronectin in hepatic stellate LX-2 cells. Finally, HPSE activity increased in the plasma of patients with liver fibrosis but it inversely correlated with liver stiffness. Our results suggest the involvement of HPSE in early phases of reaction to liver damage and inflammatory macrophages as an important source of HPSE. HPSE seems to play a key role in the macrophage-mediated activation of hepatic stellate cells (HSCs), thus suggesting that HPSE targeting could be a new therapeutic option in the treatment of liver fibrosis

Non-invasive Coronary Flow Velocity Reserve Assessment Predicts Adverse Outcome In Women With unstable angina Without Obstructive Coronary Artery Stenosis

Background: Evaluation of coronary flow velocity reserve (CFVR) is the physiological approach to assess the severity of coronary stenosis and microvascular dysfunction. Impaired CFVR occurs frequently in women with suspected or known coronary artery disease . The aim of this study was to assess the role of CFVR to predict long-term cardiovascular event rate in women with unstable angina (UA) without obstructive coronary artery stenosis. Methods: CFVR in left anterior descending coronary artery was assessed by adenosine transthoracic echocardiograhy in 161 women admitted at our Department with UA and without obstructive coronary artery disease. Results: During a mean FU of 32.5 ±19.6 months, 53 cardiac events occurred: 6 nonfatal acute myocardial infarction , 22 UA, 7 coronary revascularization by percutaneous transluminal coronary angioplasty, 1 coronary bypass surgery, 3 ischemic stroke and 8 episodes of congestive heart failure with preserved ejection fraction and 6 cardiac deaths. Using a ROC curve analysis, CFVR 2.14 was the best predictor of cardiac events and was considered as abnormal CFVR. Abnormal CFVR was associated with lower cardiac event-free survival (30% vs 80%, p<0.0001). During FU, 70% of women with reduced CFVR had cardiac events whereas only 20% with normal CFVR (p=0.0001). At multivariate Cox analysis, smoke habitus (p=0.003), metabolic syndrome (p=0.01), and CFVR (p<0.0001) were significantly associated with cardiac events at FU. Conclusion: Noninvasive CFVR provides an independent predictor of cardiovascular prognosis information in women with UA without obstructive coronary artery disease whereas, impaired CFVR seems to be associated with higher CV events at FU

Effect of the Purinergic Inhibitor Oxidized ATP in a Model of Islet Allograft Rejection

The lymphocytic ionotropic purinergic P2X receptors (P2X1R-P2X7R, or P2XRs) sense ATP released during cell damage-activation, thus regulating T-cell activation. We aim to define the role of P2XRs during islet allograft rejection and to establish a novel anti-P2XRs strategy to achieve long-term islet allograft function. Our data demonstrate that P2X1R and P2X7R are induced in islet allograft-infiltrating cells, that only P2X7R is increasingly expressed during alloimmune response, and that P2X1R is augmented in both allogeneic and syngeneic transplantation. In vivo short-term P2X7R targeting (using periodate-oxidized ATP [oATP]) delays islet allograft rejection, reduces the frequency of Th1/Th17 cells, and induces hyporesponsiveness toward donor antigens. oATP-treated mice displayed preserved islet grafts with reduced Th1 transcripts. P2X7R targeting and rapamycin synergized in inducing long-term islet function in 80% of transplanted mice and resulted in reshaping of the recipient immune system. In vitro P2X7R targeting using oATP reduced T-cell activation and diminished Th1/Th17 cytokine production. Peripheral blood mononuclear cells obtained from long-term islet-transplanted patients showed an increased percentage of P2X7R+CD4+ T cells compared with controls. The beneficial effects of oATP treatment revealed a role for the purinergic system in islet allograft rejection, and the targeting of P2X7R is a novel strategy to induce long-term islet allograft function

Effect of the Purinergic Inhibitor Oxidized ATP in a Model of Islet Allograft Rejection

The lymphocytic ionotropic purinergic P2X receptors (P2X1R-P2X7R, or P2XRs) sense ATP released during cell damage-activation, thus regulating T-cell activation. We aim to define the role of P2XRs during islet allograft rejection and to establish a novel anti-P2XRs strategy to achieve long-term islet allograft function. Our data demonstrate that P2X1R and P2X7R are induced in islet allograft-infiltrating cells, that only P2X7R is increasingly expressed during alloimmune response, and that P2X1R is augmented in both allogeneic and syngeneic transplantation. In vivo short-term P2X7R targeting (using periodate-oxidized ATP [oATP]) delays islet allograft rejection, reduces the frequency of Th1/Th17 cells, and induces hyporesponsiveness toward donor antigens. oATP-treated mice displayed preserved islet grafts with reduced Th1 transcripts. P2X7R targeting and rapamycin synergized in inducing long-term islet function in 80% of transplanted mice and resulted in reshaping of the recipient immune system. In vitro P2X7R targeting using oATP reduced T-cell activation and diminished Th1/Th17 cytokine production. Peripheral blood mononuclear cells obtained from long-term islet-transplanted patients showed an increased percentage of P2X7R+CD4+ T cells compared with controls. The beneficial effects of oATP treatment revealed a role for the purinergic system in islet allograft rejection, and the targeting of P2X7R is a novel strategy to induce long-term islet allograft function

Outcomes of pregnancies after kidney transplantation: lessons learned from CKD. A comparison of transplanted, nontransplanted chronic kidney disease patients and low-risk pregnancies: a multicenter nationwide analysis.

BACKGROUND: Kidney transplantation (KT) may restore fertility in CKD. The reasons why materno-foetal outcomes are still inferior to the overall population are only partially known. Comparison with the CKD population may offer some useful insights for management and counselling.Aim of this study was to analyse the outcomes of pregnancy after KT, compared with a large population of non-transplanted CKD patients and with low-risk control pregnancies, observed in Italy the new millennium. METHODS: We selected 121 live-born singletons after KT (Italian study group of kidney in pregnancy, national coverage about 75%), 610 live-born singletons in CKD and 1418 low-risk controls recruited in 2 large Italian Units, in the same period (2000-2014). The following outcomes were considered: maternal and foetal death; malformations; preterm delivery; small for gestational age baby (SGA); need for the neonatal intensive care unit (NICU); doubling of serum creatinine or increase in CKD stage. Data were analysed according to kidney diseases, renal function (staging according to CKD-EPI), hypertension, maternal age, partity, ethnicity. RESULTS: Materno-foetal outcomes are less favourable in CKD and KT as compared with the low-risk population. CKD stage and hypertension are important determinants of results. KT patients with e-GFR >90 have worse outcomes compared with CKD stage 1 patients; the differences level off when only CKD patients affected by glomerulonephritis or systemic diseases ('progressive CKD') are compared with KT. In the multivariate analysis, risk for preterm and early-preterm delivery was linked to CKD stage (2-5 versus 1: RR 3.42 and 3.78) and hypertension (RR 3.68 and 3.16) while no difference was associated with being a KT or a CKD patient. CONCLUSIONS: The materno-foetal outcomes in patients with kidney transplantation are comparable with those of nontransplanted CKD patients with similar levels of kidney function impairment and progressive and/or immunologic kidney diseas

Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening

A novel role for heparanase in the onset of liver fibrosis establishment

Heparan sulfate proteoglycans are important structural and functional components of basal membranes composed of a core protein (soluble or transmembrane) covalently linked to highly sulfated chains of glycosaminoglycans called heparan sulfate. Heparanase is the only endoglucuronidase capable of cleaving heparan sulfate chains of heparan sulfate proteoglycans. It exerts its enzymatic activity by catalyzing the cleavage of the β(1,4)-glycoside bond between glucuronic acid and glucosamine residues, generating fragments of about 5–7kDa. At intracellular level (endosomal and lysosomal), heparanase participates in the turnover of membrane-associated heparan sulfate proteoglycans, while secreted enzyme is involved in the remodeling and degradation of extracellular matrix. Given the electrostatic interaction of heparan sulfate with growth factors, cytokines and enzymes, heparanase cleavage indirectly facilitates the release and diffusion of these molecules. Heparanase exerts also non-enzymatic functions since it regulates gene expression by the activation of specific signaling pathways. Through degradation of heparan sulfate chains and heparan sulfate-independent functions, HPSE regulates several physiological and pathological processes. In particular, heparanase has a significant role in tumor progression and in renal glomerular diseases. In addition, it was recently shown its involvement also in bowel and kidney chronic inflammation as well as in tubulo-interstitial fibrosis. In general, fibrosis is an unregulated process of tissue repair that occurs in response to persistent damage and chronic inflammation. In the liver, the progressive accumulation of extracellular matrix can lead to cirrhosis and organ failure. In this process, activated Kupffer cells and hepatic stellate cells (HSCs) play a fundamental role, the first in the inflammatory response, the latter in fibrogenesis. The involvement of heparanase in the development of chronic liver disease has not been demonstrated so far. Given the reproducibility of the mechanisms that contribute to the development of chronic diseases, this study was aimed to: i) investigate whether heparanase is up-regulated during chronic liver disease, ii) study the possible regulation of its expression and iii) study the possible effects on the development of the disease. The tempo-spatial expression of heparanase was studied in mice with chronic hepatic damage induced by carbon tetrachloride (CCl4) administration for 1, 2, 8 and 12 weeks. The progression of chronic injury and fibrosis was assessed by Azan-Mallory and Hematoxylin-Eosin histological stainings. Extensive centrilobular areas with necro-inflammatory activity and fibrosis were observed after 1 and 2 weeks of treatment that progressively developed fibrotic septa and micronodular cirrhosis observed after 8 and 12 weeks of treatment. Analyses of gene expression (by real time RT-PCR) and protein expression (by western blot and immunofluorescence), showed a significant increase of heparanase expression in liver tissue after 1 and 2 weeks of treatment but not after 8 and 12 weeks suggesting a possible role in the early stages of chronic damage. Immunohistochemical analyses revealed the localization of heparanase in the centrilobular areas with necro-inflammatory damage and fibrosis. To identify the cellular source responsible for heparanase increase in tissue, in vitro analyses on cell cultures and co-immunofluorescence analyses on sections from 1 and 2 week-treated livers were performed. Given heparanase localization in fibrotic areas and the fundamental role of the HSCs in chronic liver disease, we wondered if the expression of heparanase increases in HSC during their activation. For this purpose, primary HSCs were isolated from rat livers and induced to activate through culture on plastic dishes. After 15 days of isolation, the levels of heparanase and transdifferentiation markers (α-SMA, fibronectin, TGF-β and collagen I) expression increased significantly compared to cells cultured for 7 days. However, despite immunofluorescence analyses on liver sections revealed the expression of heparanase by in vivo activated HSCs at 1 and 2 weeks of treatment with CCl4, a more significant degree of co-localization was observed with macrophages labeled with F4/80 and CD68. Given the main involvement of macrophages in increasing hepatic heparanase in the sites of inflammation, an analysis of the possible mechanisms of heparanase up-regulation by inflammatory macrophages was then conducted. To this purpose, primary Kupffer cells were isolated from rat livers and treated with LPS and TNF-α, two important pro-inflammatory stimuli. In contrast to LPS, that did not alter the expression of heparanase, TNF-α induced a significant increase of heparanase expression. Also human U937 macrophages, treated with increasing concentrations of TNF-α, increased the heparanase gene and protein levels, in a dose-dependent mechanism. By Western blot on the conditioned media from cells treated or not with TNF-α, we also showed an increase of extracellular enzyme in the presence of TNF-α, indicating that this factor stimulates also heparanase secretion. In addition, two observations provided further evidence on the possible role of TNF-α as a regulator of heparanase expression in chronic liver disease: first, the significant increase in TNF-α expression in the liver tissue only at 1 and 2 weeks of intoxication by CCl4 and, secondly, its co-localization with heparanase at the same weeks of treatment. Among the other pro-inflammatory molecules tested, while IFN-γ stimulated heparanase gene transcription, IL-4 reduced its expression thus suggesting a different regulation of heparanase by macrophages depending on their state of M1 or M2 polarization. The observation of enhanced heparanase expression in the early stages of chronic liver disease led to wonder what it could be its role in the process of fibrogenesis. Given the involvement of Kupffer cells in the activation of HSC through the release of pro-fibrotic stimuli, we examined whether a mechanism of regulation through the release of heparanase was also possible. For this purpose, LX-2 stellate cells were treated with the conditioned media of U937 cells that were previously induced to produce heparanase by stimulation with TNF-α. The involvement of heparanase in the activation of LX-2 has been verified using an heparanase inhibitor during treatment. The results showed that heparanase is able to regulate the expression of α-SMA and fibronectin by LX-2 cells. Besides extracellular matrix degradation, the promotion of macrophage activation by heparanase is already known. In this study, using an in vitro migration assay, we demonstrated that heparanase is also able to stimulate the migration of macrophages. Finally, to verify the involvement of heparanase also in human liver fibrosis, the levels of heparanase activity were measured in the plasma of healthy subjects and patients with chronic liver disease, of viral or autoimmune etiology and at different stages of fibrosis. Accordingly to the animal model, we showed that, regardless of the etiology of hepatic disease, heparanase plasma activity increased in patients with mild and moderate fibrosis compared to healthy subjects, but returned to baseline in patients with cirrhosis. In addition, in patients, plasma heparanase activity negatively correlated with the degree of liver stiffness. Overall, our results indicate the involvement of heparanase in chronic liver disease but only in its early stages. Inflammatory macrophages and, to a lesser extent, activated HSCs are an important source of heparanase. In this context, secreted heparanase in the extracellular environment may play a role in the macrophage-mediated activation of HSCs and in the migration of macrophages themselves.I proteoglicani dell'eparan solfato sono importanti componenti strutturali e funzionali delle membrane basali costituiti da un asse proteico (solubile o transmembrana) legato covalentemente a catene altamente solfatate di glicosaminoglicani chiamate eparan solfato. L'eparanasi è l'unico enzima in grado di tagliare le catene di eparan solfato a livello di specifici siti intracatena, generando frammenti di circa 5-7kDa. Essa si definisce endo-β-D-glucuronidasi, in quanto capace di tagliare i legami glicosidici tra i monomeri di acido glucuronico a glucosamina che costituiscono l'eparan solfato. A livello intracellulare (endosomale e lisosomale), l'eparanasi partecipa al turnover dei proteoglicani dell'eparan solfato associati alla membrana cellulare mentre, quando secreta, è coinvolta nella degradazione e nel rimodellamento della matrice extracellulare. Data l'interazione elettrostatica dell'eparan solfato con fattori di crescita, citochine ed enzimi, il suo taglio da parte dell'eparanasi facilita indirettamente anche il rilascio e la diffusione di queste molecole. L'eparanasi svolge poi funzioni non enzimatiche in quanto è in grado di regolare l'espressione genica attraverso l'attivazione di vie di segnalazione intracellulari. Nello svolgere queste funzioni, l'eparanasi è coinvolta sia in processi fisiologici che patologici. In particolare l'eparanasi ha un ruolo significativo nella progressione tumorale e nelle malattie glomerulari renali. Inoltre, è stato recentemente dimostrato il suo coinvolgimento anche nell'infiammazione cronica a livello intestinale e renale così come nella fibrosi tubulo-interstiziale. In generale, la fibrosi è un processo sregolato di riparazione tissutale che insorge in seguito ad un danno persistente e ad infiammazione cronica. Nel fegato, il progressivo accumulo di matrice extracellulare può portare a cirrosi e insufficienza epatica. In questo processo, l'attivazione delle cellule di Kupffer e delle cellule stellate (HSC) svolge un ruolo fondamentale, le prime nella risposta infiammatoria, le seconde nella fibrogenesi. Finora, nessuno studio ha dimostrato un coinvolgimento dell'eparanasi nello sviluppo della malattia cronica epatica. Considerata la riproducibilità dei meccanismi che concorrono allo sviluppo delle malattie croniche, questo studio ha lo scopo di: i) verificare se l'eparanasi sia up-regolata nel corso della malattia cronica di fegato, ii) studiare l'eventuale regolazione della sua espressione e iii) studiare i possibili effetti sullo sviluppo della malattia. Il quadro di espressione temporo-spaziale dell'eparanasi è stato studiato in topi con danno cronico epatico indotto da somministrazioni di tetracloruro di carbonio (CCl4) per 1, 2, 8 e 12 settimane. La progressione del danno cronico e della fibrosi è stata valutata tramite le colorazioni istologiche di Azan-Mallory ed Ematossilina-Eosina. Estese aree centrolobulari ad elevata attività necro-infiammatoria e fibrosi si sono osservate dopo 1 e 2 settimane di trattamento che hanno progressivamente generato fasci fibrotici e cirrosi micronodulare osservati dopo 8 e 12 settimane di trattamento. Analisi di espressione genica (tramite real time RT-PCR) e proteica (tramite Western blot e immunofluorescenza), hanno dimostrato un significativo aumento di espressione dell'eparanasi dopo 1 e 2 settimane di trattamento ma non dopo 8 e 12 settimane suggerendo un possibile ruolo dell'enzima nelle fasi iniziali del danno cronico. Analisi di immunoistochimica hanno poi evidenziato una localizzazione dell'eparanasi nelle aree centrolobulari con danno necro-infiammatorio e fibrosi. Per identificare la sorgente cellulare di eparanasi responsabile del suo aumento tissutale, sono state condotte analisi in vitro su colture cellulari ed analisi di co-immuofluorescenza su sezioni di fegato trattato con CCl4 per 1 e 2 settimane. Data la localizzazione dell'eparanasi nelle aree fibrotiche e il ruolo fondamentale delle HSC nella malattia cronica di fegato, ci siamo chiesti se l'espressione di eparanasi aumenti nelle HSC durante la loro attivazione. A tal scopo, cellule primarie sono state isolate da fegato di ratto e indotte ad attivarsi tramite coltura su plastica. Dopo 15 giorni dall'isolamento, i livelli di espressione dell'eparanasi e di marcatori del transdifferenziamento (α-SMA, fibronectina, TGF-β e collagene I) sono significativamente aumentati rispetto a cellule coltivate per 7 giorni. Tuttavia, nonostante analisi di immunofluorescenza abbiano evidenziato l'espressione di eparanasi da parte di HSC attivate in vivo a 1 e 2 settimane di trattamento con CCl4, un più significativo grado di co-localizzazione è stato osservato con i macrofagi marcati con F4/80 e CD68. Dato il principale coinvolgimento dei macrofagi nell'aumento di eparanasi epatica in sede di infiammazione, è stata quindi condotta un'analisi sui possibili meccanismi di up-regolazione dell'eparanasi da parte dei macrofagi infiammatori. A tal scopo, cellule primarie di Kupffer sono state isolate da fegato di ratto e trattate con LPS e TNF-α, due importanti stimoli pro-infiammatori. Al contrario dell'LPS che non ha alterato l'espressione dell'eparanasi, il TNF-α ne ha indotto un significativo aumento. Anche macrofagi umani U937, trattati con concentrazioni crescenti di TNF-α, hanno aumentato l'espressione genica e proteica dell'eparanasi, con un meccanismo dose-dipendente. Tramite Western blot sui mezzi condizionati di U937 trattate o meno con TNF-α, abbiamo inoltre dimostrato un incremento di enzima extracellulare in presenza di TNF-α, suggerendo come questo fattore stimoli anche la secrezione di eparanasi. Due osservazioni hanno poi fornito ulteriori evidenze sul possibile ruolo del TNF-α come regolatore dell'espressione dell'eparanasi nella malattia cronica epatica: in primo luogo il significativo aumento di espressione del TNF-α nel tessuto epatico solo a 1 e 2 settimane di intossicazione da CCl4 e, in secondo luogo, la sua co-localizzazione con l'eparanasi alle stesse settimane di trattamento. Tra le altre molecole pro-infiammatorie testate, mentre IFN-γ ha stimolato la trascrizione genica dell'eparanasi, IL-4 ne ha ridotto l'espressione suggerendo una diversa regolazione dell'eparanasi da parte dei macrofagi a seconda del loro stato di polarizzazione M1 e M2. L'elevata espressione dell'eparanasi negli stadi iniziali della malattia cronica di fegato ha portato a chiederci quale potesse essere il suo ruolo nel processo di fibrogenesi. Dato il coinvolgimento delle cellule di Kupffer nell'attivazione delle HSC tramite il rilascio di stimoli pro-fibrotici, abbiamo verificato se fosse possibile un meccanismo di regolazione anche attraverso il rilascio di eparanasi. A tale scopo, cellule stellate LX-2 sono state trattate con i mezzi condizionati delle U937 precedentemente indotte a produrre eparanasi tramite stimolazione con TNF-α. Il coinvolgimento dell'eparanasi nell'attivazione delle LX-2 è stato verificato utilizzando un inibitore dell'eparanasi durante il trattamento. I risultati hanno dimostrato come l'eparanasi sia in grado di regolare l'espressione di α-SMA e di fibronectina da parte delle LX-2. Oltre alla degradazione della matrice extracellulare, anche la capacità di promuovere l'attivazione dei macrofagi è un'attività dell'eparanasi già nota. In questo studio, tramite un saggio di migrazione in vitro, è stato dimostrato come la forma latente dell'eparanasi sia in grado di stimolare anche la migrazione dei macrofagi. Infine, per verificare il coinvolgimento dell'eparanasi nella fibrosi epatica umana, i livelli di attività dell'eparanasi sono stati misurati nel plasma di soggetti sani e pazienti affetti da malattia cronica di fegato, ad eziologia virale o autoimmune e a diversi stadi di fibrosi. A conferma di quanto riscontrato nel modello animale, abbiamo osservato come, indipendentemente dall'eziologia della malattia epatica, l'attività plasmatica dell'eparanasi aumenti nei pazienti con fibrosi lieve e moderata rispetto ai soggetti sani, ma ritorni basale nei pazienti cirrotici. Inoltre, nei pazienti, l'attività plasmatica dell'eparanasi correlava negativamente con il grado di stiffness epatica. Complessivamente, i nostri risultati indicano un coinvolgimento dell'eparanasi nella malattia cronica di fegato ma solo nelle sue fasi iniziali. Macrofagi infiammatori e, in misura minore, HSC attivate costituiscono un'importante fonte di eparanasi. In questo contesto, l'eparanasi secreta nell'ambiente extracellulare può avere un ruolo nell'attivazione delle HSC mediata dai macrofagi e nella migrazione dei macrofagi stessi