Antonio Di Sario

Bone mass and metabolism in patients with celiac disease

BACKGROUND & AIMS Several aspects of the pathogenesis of osteopenia in celiac disease are still unclear. Therefore, bone mass and metabolism were evaluated in adults with celiac disease in a cross-sectional study. METHODS Bone mineral density (BMD), assessed by total body dual-photon absorptiometry, and serum indices of bone metabolism and remodeling were evaluated in 17 patients with untreated celiac disease, 14 with celiac disease on a gluten-free diet, and 24 healthy volunteers. RESULTS BMD, expressed as a z score, was significantly lower in patients with untreated celiac disease than in patients with treated celiac disease and volunteers and lower in patients with treated celiac disease than in volunteers. Similar changes were observed in serum calcium level, whereas intact parathyroid hormone level was significantly higher in untreated than in treated patients with celiac disease and volunteers, and no difference was found between the latter two groups. 25-Vitamin D level was significantly lower and 1,25-vitamin D level significantly higher in untreated celiac disease than in treated celiac disease and volunteers. Indices of bone remodeling were significantly higher in untreated than in treated patients and volunteers and significantly and positively correlated with iPTH in untreated patients with celiac disease. CONCLUSIONS BMD is almost invariably low in patients with untreated celiac disease. Results in treated patients suggest that gluten-free diet improves but does not normalize BMD. Untreated celiac disease is characterized by high levels of 1,25-vitamin D and by increased bone turnover, caused by the increase in intact parathyroid hormone level.

Effect of pirfenidone on rat hepatic stellate cell proliferation and collagen production

BACKGROUND/AIMS Pirfenidone has been recently shown to reduce dimethynitrosamine-induced liver fibrosis in the rat, but no information are available on the effect of this drug on cultured hepatic stellate cells (HSC). METHODS HSC proliferation was evaluated by measuring bromodeoxyuridine incorporation; PDGF-receptor autophosphorylation, extracellular signal-regulated kinase (ERK1/2) and pp70(S6K) activation were evaluated by western blot; protein kinase C activation was evaluated by western blot and by ELISA; type I collagen accumulation and alpha1(I) procollagen mRNA expression were evaluated by ELISA and northern blot, respectively. RESULTS Pirfenidone significantly inhibited PDGF-induced HSC proliferation, starting at a concentration of 1 microM, with a maximal effect at 1000 microM, without affecting HSC viability and without inducing apoptosis. The inhibition of PDGF-induced HSC proliferation was associated neither with variations in PDGF-receptor autophosphorylation, or with ERK1/2 and pp70(S6K) activation. On the other hand, pirfenidone was able to inhibit PDGF-induced activation of the Na(+)/H(+) exchanger, which is involved in PDGF-induced HSC proliferation in HSC, with a maximal effect at 1000 microM and inhibited PDGF-induced protein kinase C activation. Pirfenidone 100 and 1000 microM inhibited type I collagen accumulation in the culture medium induced by transforming growth factor(beta1) by 54% and 92%, respectively, as well as TGF(beta1)-induced alpha1(I) procollagen mRNA expression. RESULTS Pirfenidone could be a new candidate for antifibrotic therapy in chronic liver diseases.

The Na+/H+ exchanger modulates the fibrogenic effect of oxidative stress in rat hepatic stellate cells

BACKGROUND/AIMS Oxidative stress is associated with liver fibrosis in vivo and with hepatic stellate cell (HSC) activation in vitro, but the intracellular mechanisms mediating these effects are mostly unknown. The Na+/H+ exchanger plays a key role in regulating the cell cycle, and is involved in HSC proliferation. Its role in different HSC features, such as collagen accumulation, is still unknown. We thus evaluated if the Na+/H+ exchanger modulates the fibrogenic effect of oxidative stress in rat HSC. METHODS HSC were incubated with 0.1 mM ferric nitrilotriacetate complex (FeNTA). Intracellular hydroperoxides and malonildialdehyde (MDA) levels in the culture media were measured by the dichlorofluorescein and TBARS method, respectively. Intracellular pH and Na+/H+ exchanger activity were measured using the fluorescent dye BCECF. Cell proliferation was measured by immunohistochemistry for bromodeoxyuridine incorporation. Collagen type I accumulation in the culture media was measured by ELISA. RESULTS HSC incubation with FeNTA resulted in a significant production of intracellular hydroperoxides and MDA, associated with increased Na+/H+ exchange activity and baseline intracellular pH (pHi). Exposure of HSC to FeNTA significantly enhanced the number of proliferating HSC and collagen type I levels in the culture medium. All these effects were reversed by the antioxidant resveratrol and by the Na+/H+ exchanger inhibitor amiloride. CONCLUSIONS This study indicates that the Na+/H+ exchanger might represent a common mediator of the different effects induced by oxidative stress on HSC. The reduction in cell proliferation and collagen synthesis induced by amiloride could represent a new therapeutic challenge in liver fibrosis.

Lactose intolerance and bone mass in postmenopausal Italian women

Previous studies on the role of lactose malabsorption in the pathogenesis of postmenopausal osteoporosis have yielded conflicting results and further information is needed. To date, all studies have been carried out on populations with a low prevalence of lactose malabsorption and the lactose intestinal absorptive capacity was tested using a non-physiological dose of lactose. In fifty-eight Italian postmenopausal women (mean age 57 (SD 7) years), bone mineral density (BMD) at lumbar spine, H2 breath response after ingestion of 20 g lactose, intensity of symptoms of intolerance after a lactose load and daily Ca intake were evaluated. No differences were found between women with or without a positive H2 breath test with regard to BMD (-1.2 (SD 0.9) v. -0.9 (SD 0.8)) and Ca intake (509 (SD 266) v. 511 (SD 313) mg/d). On the contrary, both BMD and Ca intake were significantly lower in women with lactose malabsorption and symptoms of intolerance (-1.5 (SD 0.7) and 378 (SD 220) mg/d) than in those with malabsorption without symptoms (-0.9 (SD 0.9) and 624 (SD 254) mg/d). Moreover, in lactose malabsorbers Ca intake was correlated inversely with symptom score (rs -0.31, P < 0.05) and positively with BMD (rs 0.42, P < 0.005). Our results show that in Italian postmenopausal women Ca intake and BMD are not influenced directly by lactose malabsorption; the appearance of symptoms of intolerance seems to influence BMD unfavourably through a reduced Ca intake.

Intracellular pathways mediating Na+/H+ exchange activation by platelet-derived growth factor in rat hepatic stellate cells

BACKGROUND & AIMS The Na+/H+ exchanger is the main intracellular pH regulator in hepatic stellate cells (HSCs), and its activity is increased by platelet-derived growth factor (PDGF). Amiloride, an Na+/H+ exchange inhibitor, reduces PDGF-induced HSC proliferation, suggesting that the Na+/H+ exchanger plays a role in regulating HSC proliferative response. The aim of this study was to characterize the intracellular pathways mediating activation of the Na+/H+ exchanger by PDGF in HSCs. METHODS The activity of the Na+/H+ exchanger and HSC proliferation rate were evaluated under control condition and after incubation with PDGF in the absence or presence of specific inhibitors of the main intracellular pathways of signal transduction. Na+/H+ exchange protein expression was evaluated by means of Western blot. RESULTS PDGF induced a significant increase in the activity of the Na+/H+ exchanger without modifying protein expression. Inhibition of the calcium/calmodulin- and protein kinase C-dependent pathways resulted in a significant inhibition of both Na+/H+ exchange activity and of PDGF-induced HSC proliferation. The involvement of the two pathways was confirmed by showing that incubation of HSCs with both phorbol-12-myristate-13-acetate, a potent protein kinase C activator, and thapsigargin, which increases intracellular calcium levels, significantly increased both the Na+/H+ exchanger activity and HSC proliferation rate. Inhibition of the protein kinase A pathway did not modify either PDGF-induced Na+/H+ exchange activation or PDGF-induced HSC proliferation. On the contrary, inhibition of the mitogen-activated protein kinase- and of phosphatidylinositol 3-kinase-dependent pathways significantly reduced PDGF-induced HSC proliferation without affecting the activity of the Na+/H+ exchanger. CONCLUSIONS Activation of the Na+/H+ exchanger by PDGF in HSCs is mediated by calcium/calmodulin- and protein kinase C-dependent pathways. PDGF-induced HSC proliferation is mediated by Na+/H+ exchange-dependent and -independent pathways.

Subclinical coeliac disease: an anthropometric assessment

Abstract. Objectives. To evaluate the prevalence of malnutrition in patients with untreated coeliac disease (CD) according to their pattern of presentation, and the effect of gluten‐free diet (GFD) upon nutritional status.

Intracellular pH regulation and Na+/H+ exchange activity in human hepatic stellate cells: effect of platelet-derived growth factor, insulin-like growth factor 1 and insulin

BACKGROUND/AIMS The Na+/H+ exchanger is involved in rat hepatic stellate cell (HSC) proliferation induced by platelet-derived growth factor (PDGF). We therefore evaluated in human HSC: (1) the mechanisms of intracellular pH regulation; (2) the relationship between Na+/H+ exchange activation and cell proliferation induced by PDGF, insulin-like growth factor 1 (IGF-1) and insulin. METHODS/RESULTS pH(i) regulation was mainly dependent on the activity of the Na+/H+ exchanger, which was evaluated by measuring pH(i) recovery from an acute acid load. PDGF (25 ng/ml) gradually increased the activity of the Na+/H+ exchanger which peaked at 18 h and remained stable until the 24th h. IGF-1 (10 nmol/l), but not insulin (100 nmol/l), slightly but significantly increased the activity of the Na+/H+ exchanger. Amiloride (100 micromol/l) and 20 micromol/l 5-N-ethyl-N-isopropyl-amiloride completely inhibited HSC proliferation (evaluated by measurement of bromodeoxyuridine incorporation) induced by PDGF and IGF-1, but did not affect proliferation of HSC induced by insulin. Finally, IGF-1 did not modify the activity of the Na+/Ca2+ exchanger. CONCLUSIONS The Na+/H+ exchanger is involved in HSC proliferation induced by PDGF and IGF-1, whereas the proliferative effect of insulin is mediated by intracellular pathways which are Na+/H+ exchange-independent.

Rearrangement of the cytoskeletal network induced by platelet-derived growth factor in rat hepatic stellate cells: role of different intracellular signalling pathways.

BACKGROUND/AIMS Cytoskeletal reorganization plays an important role in the regulation of different cell functions, such as proliferation and migration. Since platelet-derived growth factor (PDGF) stimulates both proliferation and chemotaxis of hepatic stellate cells (HSC), we investigated the effects of this cytokine on cytoskeletal components of cultured rat HSC. METHODS/RESULTS Exposure of HSC to PDGF induced the formation of stress fibres and of a ruffled configuration of the plasma membrane, evaluated by both fluorescence and electron microscopy. These modifications were also induced by exposure to the protein kinase C (PKC) activator phorbol-12-myristate-13-acetate (PMA) and abolished by pretreatment with the PKC inhibitor calphostin C, with the Rho inhibitor C3 exoenzyme and with the intracellular calcium chelator MAPTAM, but not with the PI-3 kinase inhibitor wortmannin or with the mitogen-activated protein kinase kinase inhibitor PD 98059. PDGF induced a translocation of Rho from the cytosol to the membrane which was inhibited by C3 exoenzyme and by calpostin C, and which was also induced by PMA. Moreover, PDGF induced a rearrangement of vinculin which was prevented by C3 exoenzyme and calphostin C. CONCLUSIONS PDGF-induced cytoskeletal reorganization in HSC is dependent on PKC and Rho, thus suggesting that these two pathways may play an important role in the response of liver to injury.

Role of Small Intestinal Bacterial Overgrowth and Helicobacter pylori Infection in Chronic Spontaneous Urticaria: A Prospective Analysis

The aim of this study is to assess the associations between chronic spontaneous urticaria (CSU), Helicobacter pylori infection and small intestinal bacterial overgrowth. Forty- eight patients with CSU were studied by scoring the urticaria activity and assesing the quality of life. Patients with H. pylori infection (n=11) or small intestinal bacterial overgrowth (n=13) were specifically treated for one week and clinically evaluated both before and 4 weeks after the eradication therapy. Eradication of H. pylori infection led to a significant improvement in CSU (p<0.002). In contrast, eradication of small intestinal bacterial overgrowth was not associated with any clinical improvement in CSU, despite the fact that these patients had statistically significant more urticaria activity at baseline. Thus there is no evidence to support the eradication of small intestinal bacterial overgrowth in CSU, but eradication of H. pylori infection may result in an improvement of the disease.

Biologic Drugs in Crohn's Disease and Ulcerative Colitis: Safety Profile.

Ulcerative Colitis (UC) and Crohns Disease (CD) are chronic, progressive and disabling disorders characterized by a heterogeneous clinical course. Some years ago the main goal of the therapy was to achieve and maintain clinical remission, whereas at present the main goal of therapy is represented by the deep remission, characterized by sustained clinical remission, complete mucosal healing and normalization of serological markers of inflammation. In the last years new therapeutic approaches have been introduced which have led to a reduction in the mortality rate and have modified the natural history of Inflammatory Bowel Diseases (IBD). In addition, several prognostic factors have been identified which have allowed to better stratify the disease and to choose the most appropriate therapy for the single patient. Moreover, early treatment with immunosuppressive drugs and/or biologics has changed, at least in the short term, the course of the disease by reducing hospitalization rate and the need for surgery. Therefore, the development of biologic therapies has represented an important step in the treatment of IBD, since these drugs induce remission and response rates that are not achieved by other therapies. Since their use can result in significant adverse events that increase morbidity, patients must be aware of the risks associated with treatment and must be strictly monitored. Although treatment with biologic drugs is not successful in all patients and many of them lose clinical response, new therapies are currently under evaluation.