Reduction of oxidative stress and cytokine-induced neutrophil chemoattractant (CINC) expression by red wine polyphenols in zinc deficiency induced intestinal damage of rat.

Consumption of red wine has been associated with health promotion and disease prevention. We have previously found that the intestine of zinc-deficient (ZD) rats develop oxidative damage associated with inflammation. Here we have used this model to investigate whether red wine polyphenols could protect against intestinal injury and, if so, whether this protection was achieved through antioxidant and anti-inflammatory activity. The intestinal alterations induced by zinc deficiency such as morphological damage, increased TBA-RS level and CuZn-superoxide dismutase activity, and decreased glutathione peroxidase activity, did not develop with the administration to ZD rats of a suspension of dealcoholated red wine (RWS). The same treatment induced in control rats a decrease of TBA-RS level but also of glutathione peroxidase and catalase activity. Treatment with RWS to ZD rats prevented a marked mucosal macrophage and neutrophil infiltration. The expression of pro-inflammatory cytokines, such as tumor necrosis factor alpha and cytokine-induced neutrophil chemoattractant (CINC), was induced by zinc deficiency, whereas that of the anti-inflammatory interleukin-10 was suppressed. Treatment with RWS reduced CINC expression. These results report a novel activity of red wine polyphenols in downregulation of intestinal CINC expression, which likely protects cells against inflammatory processes.

Bifidobacterium animalis protects intestine from damage induced by zinc deficiency in rats.

We investigated the potential beneficial effects of Bifidobacterium animalis on intestinal damage using zinc-deficient (ZD) rats as a model for intestinal alterations. The ZD rats were fed diets containing 1 mg Zn/kg for 20 (ZD(20)) or 40 (ZD(40)) d to induce damage that differed in severity. Subgroups of these rats, the ZD(20) + B and ZD(40) + B groups, received a suspension of B. animalis (3.5 x 10(8) colony forming units) daily for the last 10 d. Another subgroup, the ZD(40) + B + 7 d group, was fed the ZD diet for 7 d after the B. animalis treatment period. Zinc deficiency induced ulcerations, edema, inflammatory cell infiltration and dilatation of blood vessels in duodenum, jejunum and ileum, with increasing severity between 20 and 40 d of zinc deficiency. The mucosa of the ZD(20) + B group was well preserved, and most of the morphologic alterations induced by zinc deficiency were normalized in the ZD(40) + B group. The high fecal concentrations of B. animalis in the ZD(40) + B and ZD(40) + B + 7 d groups indicate that these bifidobacteria survived passage through the gastrointestinal tract and proliferated. Electron microscopy confirmed the elevated numbers of bifidobacteria in cecum. Treatment with B. animalis resulted in greater epithelial cell proliferation and disaccharidase activities in the ZD(40) + B group compared with the ZD(40) group. These findings indicate that B. animalis can protect the intestine from alterations induced by zinc deficiency, suggesting that this bacterium may play a role in intestinal mucosal defense.

Intestinal damage induced by zinc deficiency is associated with enhanced CuZn superoxide dismutase activity in rats: effect of dexamethasone or thyroxine treatment.

Zinc has a wide spectrum of biological activities and its deficiency has been related to various tissue dysfunctions and alterations of normal cell metabolism. Zinc also plays an important role in the antioxidant cellular defenses being a structural element of the non-mitochondrial form of the enzyme superoxide dismutase (CuZnSOD). We have already reported that Zn deficiency induces severe alterations in the rat intestine, that are reverted by treatment with dexamethasone (Dex) or thyroxine (T4). Here we report a paradoxical increase of CuZnSOD activity in rat intestine after 20 and 40 days of zinc deficiency. The increase of CuZnSOD activity is not due to an upregulation of gene expression because both Northern and Western blot analysis indicate that CuZnSOD mRNA and protein levels are not affected by zinc deficiency. A significant increase of lipid peroxidation was also observed in duodenum and jejunum associated with zinc deficiency. Treatment with either Dex or T4 to zinc-deficient rats protects against intestinal oxidative damage and results in SOD activity similar to control rats. Because glutathione peroxidase and catalase activities decreased in zinc deficiency, we speculate that the increase in SOD activity may be associated with an accumulation of hydrogen peroxide that may activate inflammatory molecules, further worsening tissue damage.

Involvement of interleukin-1beta in zinc deficiency-induced intestinal damage and beneficial effect of cyclosporine A.

In a previous study we have shown that zinc deficiency caused several alterations in intestine of rats. Here we report that interleukin-1beta (IL-1beta) is involved in the zinc deficiency-induced mucosal damage and that cyclosporine A (CsA) protects the intestine against both structural and functional alterations by different mechanisms. The zinc deficient (ZD) rats were maintained on a zinc deficient diet for 40 days. They received a daily injection of CsA (12 mg/kg) for the last 10 days. The histological analysis of small intestine revealed that the dramatic alterations induced by zinc deficiency (ulcerations, inflammation, edema, vasodilatation), were not present after CsA treatment. The IL-1beta gene expression, analyzed by PCR, was increased in the three intestinal regions of ZD rats, as compared to C rats. There was a relation between increasing IL-1beta expression and increased severity of damage, and the highest cytokine elevation was in the most damaged region, i.e. the jejunum. After CsA administration the IL-1beta mRNA was similar to control rats. The intestinal cell proliferation, measured as crypt cell production rate and labelling index, as well the cell renewal, measured as cell migration rate and turnover time, were affected by zinc deficiency. After CsA treatment, all these variables were similar to control rats, suggesting that CsA induces a stimulation of intestinal cell proliferation in zinc deficiency. Finally, the decrease in the disaccharidase activities induced by zinc deficiency was abrogated by CsA treatment.

Treatment of rats with dexamethasone or thyroxine reverses zinc deficiency-induced intestinal damage.

Structural and functional damage to the intestine and the potential beneficial effects of dexamethasone (Dex) and thyroxine (T4) were examined in zinc-deficient rats. Rats were assigned to zinc deficient (ZD), control (C) or pair-fed (PF ) groups and fed for 40 d a zinc deficient (1 mg/kg) diet (ZD rats) or a similar diet supplemented with 50 mg Zn/kg (C and PF rats). Some rats of the ZD group were treated for the last 10 d with low (250 mg/kg) or high (5 mg/kg) doses of Dex or with T4 (100 mg/kg). Serum corticosterone of T4-treated ZD rats did not differ from untreated ZD rats. Serum T4 of T4-treated ZD rats did not differ from C rats. ZD rats developed ulcerations, inflammation and edema in the small intestine, particularly in the jejunum. PF rats did not show mucosal changes relative to C rats. ZD rats showed significantly lower crypt cell production rate (CCPR) and labeling index (LI) in the three intestinal regions, and lower cell migration rate and higher turnover time in the duodenum relative to C rats. Sucrase and maltase activities of ZD rats were significantly lower than C rats in the three mucosal regions. Treatment with the low dose of Dex resulted in fewer ulcerations compared with ZD rats. In rats administered the high dose of Dex or T4, all morphological alterations disappeared; the CCPR, LI, cell migration rate, cell turnover time and disaccharidase activities did not differ from C rats. In conclusion, Dex and T4 exert beneficial effects on zinc deficiency-induced intestinal alterations in rats.

Cytokine gene expression in intestine of rat during the postnatal developmental period: increased IL-1 expression at weaning.

In the present study we have investigate whether cytokines are constitutively and differently expressed in intestine during the differentiative processes that take place at weaning. We have analyzed the expression of IL-1 beta, IL-2, IL-4 and IFN gamma by polymerase chain reaction in Peyer's patches (PP) and in intestine deprived of PP (I-PP) of rats from 16 to 30 days of age. The results showed a constitutive and marked expression of the cytokines already before weaning, with the exception of IL-2 in PP and IFN gamma in I-PP. IL-beta was the only cytokine to show a different expression at various ages with an initial increase at 19 days and a further elevation at 21 days when intestinal epithelium passes through major differentiative stages, suggesting an involvement of this cytokine in intestinal development. We have also tested whether treatment of rats with the immunosuppressor cyclosporin A (CsA) could affect intestinal differentiation. The results showed that only some markers of differentiation were affected (proliferation of staminal crypt cells and length of crypts). This was probably due to a direct effect rather than an immunomediated effect of CsA, since treatment of three intestinal cell lines (Caco-2, HT-29, FRIC) with CsA indicated that this drug can exert a cytostatic activity on intestinal cells.

Metallothionein gene is expressed in developing rat intestine and is induced by zinc but not by corticosteroids.

The expression of metallothionein (MT) mRNA during perinatal development of rat intestine and its induction by zinc and corticosteroids were studied. Pregnant rats from d 17 to 22 of gestation and rats at 2, 4, 13 and 21 d of postnatal life were injected with saline solution (control) or with zinc (10 mg/kg body wt) or corticosteroids (1 mg/kg body wt). After 6 h, tissues were removed for analysis. Northern hybridization of polyA + RNA to 32P-MT-cDNA revealed that MT was expressed already at d 17 of fetal life, increased afterwards (reaching the maximal expression around birth) and decreased soon after until weaning. Metallothionein mRNA was markedly induced by zinc at d 18 of fetal life to a level that remained constant throughout postnatal life. Corticosteroids were ineffective in inducing MT gene expression during prenatal and postnatal development. In 21-d-old adrenalectomized rats the level of MT mRNA was similar to that of control rats of the same age and was not changed by hormone treatment. The results indicate that MT gene expression can be induced by zinc during fetal life and that its expression without exogenous inducers cannot be ascribed to circulating corticosteroids.

Evidence that polyunsaturated lecithin induces a reduction in plasma cholesterol level and favorable changes in lipoprotein composition in hypercholesterolemic rats.

For 30 d adult rats were fed a hypercholesterolemic (H) diet (25% saturated fat, 1% cholesterol and 0.5% cholic acid) containing different amounts of saponins (1% or 0.2%) and/or purified polyunsaturated lecithin (2.5% or 0.7%). Lecithin induced a striking reduction in the plasma levels of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) cholesterol as well as an increase in the level of high density lipoprotein (HDL) cholesterol. Saponins had only a very slight effect in lowering the level of VLDL cholesterol. Apoprotein A-I was unexpectedly present in VLDL, IDL and LDL after feeding rats the H diet and disappeared only after lecithin feeding. The activity of plasma lecithin-cholesterol acyltransferase was higher when the two lecithin diets were fed than when the other diets were fed. Fecal excretion of neutral sterols was unmodified by the various diets whereas acid steroid excretion increased after lecithin feeding. Saponins, when added with lecithin to the diet, reduced the beneficial effect of lecithin. The results indicate that polyunsaturated lecithin induced a reduction in plasma cholesterol, possibly through an increased formation of HDL particles.

Modifications in plasma cholesterol and apolipoproteins of hypercholesterolaemic rats induced by ethanol-soluble factors of Vicia faba.

High-fat-high-cholesterol diets containing casein or a Vicia faba bean (faba bean) protein concentrate as the protein source were given to rats for 5 weeks. When the faba bean protein concentrate or its ethanol extract was present in the diet, a marked decrease was found in the level of circulating cholesterol associated with the lower-density lipoproteins (very-low-, intermediate- and low-density lipoproteins) compared with the level found on the diets containing casein or the faba bean protein concentrate deprived of ethanol-soluble factors. Alterations in apoprotein pattern were detected after the different dietary treatments. In particular, apoA-I appeared in an unusual form with electrophoretic mobility faster than normal in all lipoprotein fractions after feeding the diets that did not lower plasma cholesterol. When the diets contained the faba bean protein concentrate or its ethanol extract, the apoA-I disappeared from the lower-density lipoproteins but its normal form and the unusual one were apparent in the high-density lipoproteins. A moderate increase in faecal excretion of acidic steroids was found after feeding the diets containing the ethanol-soluble factors, irrespective of the protein source. The results are discussed in relation to the presence of saponin and polyunsaturated lecithin in the ethanol extract of the faba bean protein concentrate.