Rosanna Di Paola

Cellular stress responses, hormetic phytochemicals and vitagenes in aging and longevity.

Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This paper introduces the emerging role of exogenous molecules in hormetic-based neuroprotection and the mitochondrial redox signaling concept of hormesis and its applications to the field of neuroprotection and longevity. Maintenance of optimal long-term health conditions is accomplished by a complex network of longevity assurance processes that are controlled by vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as polyphenols and L-carnitine/acetyl-L-carnitine, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. Hormesis provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose response relationships, their mechanistic foundations, their relationship to the concept of biological plasticity as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This paper describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways including sirtuin, Nrfs and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

A role for superoxide in gentamicin-mediated nephropathy in rats

Gentamicin is an antibiotic effective against Gram-negative infection, whose clinical use is limited by its nephrotoxicity. Oxygen free radicals are considered to be important mediators of gentamicin-mediated nephrotoxicity, but the exact nature of the radical in question is not known with certainty. We have investigated the potential role of superoxide in gentamicin-induced renal toxicity by using M40403, a low molecular weight synthetic manganese containing superoxide dismutase mimetic, which selectively removes superoxide. Administration of gentamicin at 100 mg/kg, s.c. for 5 days to rats induced a marked renal failure, characterised by a significant decrease in creatinine clearance and increased plasma creatinine levels, fractional excretion of sodium, lithium, urine gamma glutamyl transferase (gamma GT) and daily urine volume. A significant increase in kidney myeloperoxidase activity and lipid peroxidation was also observed in gentamicin-treated rats. M40403 (10 mg/kg, i.p. for 5 days) attenuated all these parameters of damage. Immunohistochemical localisation demonstrated nitrotyrosine formation and poly(ADP-ribose) synthetase (PARS) activation in the proximal tubule of gentamicin-treated rats. Renal histology examination confirmed tubular necrosis. M40403 significantly prevented gentamicin-induced nitrotyrosine formation, poly(ADP-ribose) synthetase activation and tubular necrosis. These results confirm our hypothesis that superoxide anions play an important role in gentamicin-mediated nephropathy and support the possible clinical use of low molecular weight synthetic superoxide dismutase mimetics in those conditions that are associated with over production of superoxide.

Protective Effects of Anthocyanins from Blackberry in a Rat Model of Acute Lung Inflammation

Anthocyanins are a group of naturally occuring phenolic compounds related to the coloring of plants, flowers and fruits. These pigments are important as quality indicators, as chemotaxonomic markers and for their antioxidant activities. Here, we have investigated the therapeutic efficacy of anthocyanins contained in blackberry extract (cyanidin-3-O-glucoside represents about 80% of the total anthocyanin contents) in an experimental model of lung inflammation induced by carrageenan in rats. Injection of carrageenan into the pleural cavity elicited an acute inflammatory response characterized by fluid accumulation which contained a large number of neutrophils as well as an infiltration of polymorphonuclear leukocytes in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NOx) and prostaglandin E2 (PGE2). All parameters of inflammation were attenuated in a dose-dependent manner by anthocyanins (10, 30 mg kg-1 30 min before carrageenan). Furthermore, carrageenan induced an upregulation of the adhesion molecule ICAM-1, nitrotyrosine and poly (ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining was lowered by anthocyanins treatment. Thus, the anthocyanins contained in the blackberry extract exert multiple protective effects in carrageenan-induced pleurisy.

Immunomodulatory Effects of Etanercept in an Experimental Model of Spinal Cord Injury

Etanercept is a tumor necrosis factor antagonist with anti-inflammatory effects. The aim of our study was to evaluate for the first time the therapeutic efficacy of in vivo inhibition of tumor necrosis factor-α (TNF-α) in experimental model of spinal cord trauma, which was induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5–T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration, and cytokine production that it is followed by recruitment of other inflammatory cells, such as production of a range of inflammation mediators, tissue damage, apoptosis, and disease. Treatment of the mice with etanercept significantly reduced the degree of 1) spinal cord inflammation and tissue injury (histological score); 2) neutrophil infiltration (myeloperoxidase evaluation); 3) inducible nitric-oxide synthase, nitrotyrosine, cyclooxygenase-2, and cytokines expression (TNF-α and interleukin-1β); and 4) apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and Bax and Bcl-2 expression). In a separate set of experiment, we have also clearly demonstrated that TNF-α inhibitor significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results clearly demonstrate that treatment with etanercept reduces the development of inflammation and tissue injury events associated with spinal cord trauma.

Pure MnTBAP selectively scavenges peroxynitrite over superoxide: comparison of pure and commercial MnTBAP samples to MnTE-2-PyP in two models of oxidative stress injury, an SOD-specific Escherichia coli model and carrageenan-induced pleurisy.

MnTBAP is often referred to as an SOD mimic in numerous models of oxidative stress. We have recently reported that pure MnTBAP does not dismute superoxide, but commercial or poorly purified samples are able to perform O2.- dismutation with low-to-moderate efficacy via non-innocent Mn-containing impurities. Herein, we show that neither commercial nor pure MnTBAP could substitute for SOD enzyme in a SOD-deficient Escherichia coli model, whereas MnTE-2-PyP-treated SOD-deficient E. coli grew as well as a wild-type strain. This SOD-specific system indicates that MnTBAP does not act as an SOD mimic in vivo. In another model, carrageenan-induced pleurisy in mice, inflammation was evidenced by increased pleural fluid exudate and neutrophil infiltration and activation: these events were blocked by 0.3 mg/kg MnTE-2-PyP and, to a slightly lesser extent, by 10 mg/kg of either MnTBAP. Also, 3-nitrotyrosine formation, an indication of peroxynitrite existence in vivo, was blocked by both compounds; again MnTE-2-PyP was 33-fold more effective. Pleurisy model data indicate that MnTBAP exerts some protective actions in common with MnTE-2-PyP, which are not O2.- related and can be fully rationalized if one considers that the common biological role shared by MnTBAP and MnTE-2-PyP is related to their reduction of peroxynitrite and carbonate radical, the latter arising from ONOOCO2 adduct. The log kcat (O2.-) value for MnTBAP is estimated to be about 3.16, which is approximately 5 and approximately 6 orders of magnitude smaller than the SOD activities of the potent SOD mimic MnTE-2-PyP and Cu,Zn-SOD, respectively. This very low value indicates that MnTBAP is too inefficient at dismuting superoxide to be of any biological impact, which was confirmed in the SOD-deficient E. coli model. The peroxynitrite scavenging ability of MnTBAP, however, is only approximately 2.5 orders of magnitude smaller than that of MnTE-2-PyP and is not significantly affected by the presence of the SOD-active impurities in the commercial MnTBAP sample (log k red (ONOO-) = 5.06 for pure and 4.97 for commercial sample). The reduction of carbonate radical is equally fast with MnTBAP and MnTE-2-PyP. The dose of MnTBAP required to yield oxidative stress protection and block nitrotyrosine formation in the pleurisy model is > 1.5 orders of magnitude higher than that of MnTE-2-PyP, which could be related to the lower ability of MnTBAP to scavenge peroxynitrite. The slightly better protection observed with the commercial MnTBAP sample (relative to the pure MnTBAP) could arise from its impurities, which, by scavenging O2.-, reduce consequently the overall peroxynitrite and secondary ROS/RNS levels. These observations have profound biological repercussions as they may suggest that the effect of MnTBAP observed in numerous studies may conceivably relate to peroxynitrite scavenging. Moreover, provided that pure MnTBAP is unable to dismute superoxide at any significant extent, but is able to partially scavenge peroxynitrite and carbonate radical, this compound may prove valuable in distinguishing ONOO-/CO3.- from O2.- pathways.

Rosiglitazone and 15-deoxy-Δ12,14-prostaglandin J2, ligands of the peroxisome proliferator-activated receptor-γ (PPAR-γ), reduce ischaemia/reperfusion injury of the gut

The peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) is a member of the nuclear receptor superfamily of ligand‐dependent transcription factors related to retinoid, steroid and thyroid hormone receptors. The thiazolidinedione rosiglitazone and the endogenous cyclopentenone prostaglandin (PG)D2 metabolite, 15‐deoxy‐Δ12,14‐PGJ2 (15d‐PGJ2), are two PPAR‐γ ligands, which modulate the transcription of target genes. The aim of this study was to investigate the effect of rosiglitazone and 15d‐PGJ2 on the tissue injury caused by ischaemia/reperfusion (I/R) of the gut. I/R injury of the intestine was caused by clamping both the superior mesenteric artery and the coeliac trunk for 45 min, followed by release of the clamp allowing reperfusion for 2 or 4 h. This procedure results in splanchnic artery occlusion (SAO) shock. Rats subjected to SAO developed a significant fall in mean arterial blood pressure, and only 10% of the animals survived for the entire 4 h reperfusion period. Surviving animals were killed for histological examination and biochemical studies. Rats subjected to SAO displayed a significant increase in tissue myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels, significant increases in plasma tumour necrosis factor (TNF)‐α and interleukin (IL)‐1β levels and marked injury to the distal ileum. Increased immunoreactivity to nitrotyrosine was observed in the ileum of rats subjected to SAO. Staining of sections of the ileum obtained from SAO rats with anti‐intercellular adhesion molecule (ICAM‐1) antibody resulted in diffuse staining. Administration at 30 min prior to the onset of gut ischaemia of the two PPAR‐γ agonists (rosiglitazone (0.3 mg kg−1 i.v.) and 15d‐PGJ2 (0.3 mg kg−1 i.v.)) significantly reduced the (i) fall in mean arterial blood pressure, (ii) mortality rate, (iii) infiltration of the reperfused intestine with polymorphonuclear neutrophils (MPO activity), (iv) lipid peroxidation (MDA levels), (v) production of proinflammatory cytokines (TNF‐α and IL‐1β) and (vi) histological evidence of gut injury. Administration of rosiglitazone and 15d‐PGJ2 also markedly reduced the nitrotyrosine formation and the upregulation of ICAM‐1 during reperfusion. In order to elucidate whether the protective effects of rosiglitazone and 15d‐PGJ2 are related to the activation of the PPAR‐γ receptor, we also investigated the effect of a PPAR‐γ antagonist, bisphenol A diglycidyl ether (BADGE), on the protective effects of rosiglitazone and 15d‐PGJ2. BADGE (1 mg kg−1 administered i.v. 30 min prior to the treatment of rosiglitazone or 15d‐PGJ2) significantly antagonised the effect of the two PPAR‐γ agonists and thus abolished the protective effect against gut I/R. These results demonstrate that the two PPAR‐γ agonists, rosiglitazone and 15d‐PGJ2, significantly reduce I/R injury of the intestine.

Superoxide: a key player in hypertension

Superoxide is increased in the vessel wall of spontaneously hypertensive rats (SHR) where, if “blocked,” potentiates endothelium‐dependent vasodilation. The purpose of this study was to determine the role of superoxide anion in hypertension and its interaction with nitric oxide (NO). For this purpose we used a low molecular weight synthetic superoxide dismutase mimetic (M40403), known to remove selectively superoxide anion. Baseline mean arterial pressure (MAP) was significantly elevated in the SHR compared with its normal counterpart, Wistar Kyoto (WKY). M40403 at a dose (2 mg•kg−1•h−1), which had no effect in the WKY, significantly decreased MAP in SHR rats. To determine whether superoxide anion increases MAP by inactivating NO, NO synthesis was blocked with NG nitroarginine methyl ester (L‐NAME, 3 mg/kg i.v.), a nonselective nitric oxide synthase inhibitor. L‐NAME (3 mg/ kg, i.v) blocked the anti‐hypertensive effect of M40403 (2 mg/kg over 30 min). When used at a dose that yielded similar increases in MAP, norepinephrine (2.1 µg/kg) failed to alter the anti‐hypertensive effects of M40403 in the SHR. To investigate whether the anti‐hypertensive effect of M40403 was associated with an improvement of the alterations in vascular reactivity, a separate group of experiments was carried out ex vivo. Endothelium‐dependent vasorelaxation to acetylcholine (10 nM–10 µM), an index of endothelial function, was reduced in aortic rings taken from SHR rats when compared with WKY rats. In vivo treatment with M40403 caused an improvement of the degree of the endothelial dysfunction in SHR rats. Furthermore, immunohistochemical analysis for nitrotyrosine (the product formed from the interaction of nitric oxide with superoxide) revealed a positive staining in aorta from SHR rats. The degree of staining for nitrotyrosine was markedly reduced in tissue sections obtained from SHR rats treated with M40403. Our data suggest that overt production of superoxide in SHR couples with nitric oxide, reducing its function and leading to a loss of blood vessel tone and hypertension. Another important effect appears to be at the level of endothelial cellular integrity, where by interacting with nitric oxide, superoxide anion forms peroxynitrite and subsequent endothelial cell dysfunction. By removing superoxide, v M40403 restores blood pressure to near‐to‐normal values.—Cuzzocrea, S., Mazzon, E., Dugo, L., Di Paola, R., Caputi, A. P., Salvemini, D. Superoxide: a key player in hypertension. FASEB J. 18, 94–101 (2004)

The cyclopentenone prostaglandin 15-deoxy-Δ12,14-PGJ2 attenuates the development of colon injury caused by dinitrobenzene sulphonic acid in the rat

Inflammatory bowel disease (IBD) is characterized by oxidative and nitrosative stress, leukocyte infiltration, and increased expression of the adhesion molecules intercellular adhesion molecule 1 (ICAM‐1) in the colon. Recent evidence also suggests that the cyclopentenone prostaglandin (PG) 15‐deoxy‐Δ12,14‐PGJ2 (15d‐ PGJ2) functions as an early anti‐inflammatory signal. The aim of the present paper is to investigate the effects of 15d‐PGJ2 in rats subjected to experimental colitis. Colitis was induced in rats by intra‐colonic instillation of dinitrobenzene sulphonic acid (DNBS). 15d‐PGJ2 was administered daily as intraperitoneal injection (20 or 40 μg kg−1). On day 4, animals were sacrificed and tissues were taken for histological and biochemical analysis. 15d‐PGJ2 significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. 15d‐PGJ2 also caused a substantial reduction of (i) the degree of colonic injury, (ii) the rise in myeloperoxidase (MPO) activity (mucosa), (iii) the increase in the tissue levels of malondialdehyde (MDA) and (iv) of the pro‐inflammatory cytokines tumour necrosis factor‐alpha (TNF‐α) and interleukin‐1β (IL‐1β). Furthermore, 15d‐PGJ2 reduced the increase in immunohistochemical staining for (i) inducible nitric oxide synthase (iNOS), (ii) nitrotyrosine and (iii) poly (ADP‐ribose) polymerase (PARP), as well as (iv) the increased expression of ICAM‐1 caused by DNBS in the colon. Electrophoresis mobility shift assay (EMSA) of inflamed colon revealed that 15d‐ PGJ2 also caused a substantial reduction of the activation of nuclear factor‐kappaB (NF‐κB). Furthermore, 15d‐PGJ2 stimulates the activation of heat shock protein 72 (hsp72) in the inflamed colon, as assessed by Western blot analysis. In conclusion, 15d‐PGJ2 reduces the development of experimental colitis.

The role of the peroxisome proliferator-activated receptor-α (PPAR-α) in the regulation of acute inflammation

The peroxisome proliferator‐activated receptor‐α (PPAR‐α) is a member of the nuclear receptor superfamily of ligand‐dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The aim of the present study was to evaluate the role of the PPAR‐α receptor on the development of acute inflammation. To address this question, we used two animal models of acute inflammation (carrageenan‐induced paw edema and carrageenan‐induced pleurisy). We report here that when compared with PPAR‐α wild‐type mice, PPAR‐α knockout mice (PPAR‐αKO) mice experienced a higher rate of the extent and severity when subjected to carrageenan injection in the paw edema model or to carrageenan administration in the pleurisy model. In particular, the absence of a functional PPAR‐α gene in PPAR‐αKO mice resulted in a significant augmentation of various inflammatory parameters (e.g., enhancement of paw edema, pleural exudate formation, mononuclear cell infiltration, and histological injury) in vivo. Furthermore, the absence of a functional PPAR‐α gene enhanced the staining (immunohistochemistry) for FAS ligand in the paw and in the lung and the expression of tumor necrosis factor α and interleukin‐1β in the lungs of carrageenan‐treated mice. In conclusion, the increased inflammatory response observed in PPAR‐αΚΟ mice strongly suggests that a PPAR‐α pathway modulates the degree of acute inflammation in the mice.

Role of endogenous and exogenous ligands for the peroxisome proliferators activated receptors alpha (PPAR- α ) in the development of inflammatory bowel disease in mice

The peroxisome proliferator-activated receptor-α (PPAR-α) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid and thyroid hormone receptors. The aim of the present study was to examine the effects of endogenous and exogenous PPAR-α ligand on the development of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated PPAR-α wild-type (WT) mice, DNBS-treated PPAR-α knockout mice (PPAR-αKO) mice experienced a higher rate of the extent and severity of the histological signs of colon injury. After administration of DNBS PPAR-αWT mice experienced hemorrhagic diarrhea, weight loss and large areas of necrosis in the mucosa of the colon were also observed. Neutrophil infiltration was associated with upregulation of ICAM-1. Immunohistochemistry for nitrotyrosine showed an intense staining in the inflamed colon. Absence of a functional PPAR-α gene in PPAR-αKO mice resulted in a significant augmentation of all the above-described parameters. On the contrary, the treatment of PPAR-αWT with Wy-14643 (1 mg/kg daily i.p) significantly reduced: (i) the degree of hemorrhagic diarrhea and weight loss, (ii) the degree of colon injury, (iii) the rise in MPO activity (mucosa), (iv) the increase in staining (immunohistochemistry) for nitrotyrosine, as well as (v) the upregulation of ICAM-1 caused by DNBS in the colon. In order to elucidate whether the protective effects of Wy-14643 is related to activation of the PPAR-α receptor, we also investigated the effect the of Wy-14643 treatment on PPAR-α-deficient mice. The absence of the PPAR-α receptor significantly abolished the protective effect of the PPAR-α agonist against DNBS-induced colitis. Thus, endogenous and exogenous PPAR-α ligands reduce the degree of colitis caused by DNBS. We propose that PPAR-α ligand may be useful in the treatment of inflammatory bowel disease.