Study on the Protective Effect of a New Manganese Superoxide Dismutase on the Microvilli of Rabbit Eyes Exposed to UV Radiation.

We present a study on the protective effects against UV radiation of a gel formulation containing a new recombinant form of manganese superoxide dismutase on the conjunctiva and corneal epithelia of rabbit eyes. The integrity of the microvilli of both ocular tissues has been considered as an indicator of the health of the tissues. Samples, collected by impression cytology technique, were added of 80 µL of a gel formulation containing superoxide dismutase (2.0 µg/mL) and irradiated with UV rays for 30 minutes and were evaluated with scanning electron microscopy. Wilcoxon test was used to verify the possible occurrence of statistically significant differences between damage for treated and nontreated tissues. Application of gel produces a significant reduction of damage by UV irradiation of ocular epithelia; both epithelia present a significant reduction of damaged microvilli number if treated with the superoxide dismutase gel formulation: the p values (differences between damage found for treated and nontreated both ocular tissues) for conjunctiva and cornea samples were p ≪ 0.01 and p ≪ 0.0001, respectively, at confidence level of 95%. The administration of this gel formulation before UV exposure plays a considerable protective role in ocular tissues of rabbit eye with a significant reduction of the damage.

Effect of a recombinant manganese superoxide dismutase on prevention of contrast-induced acute kidney injury.

BACKGROUND: Contrast media (CM)-induced nephropathy (CIN) is an acute deterioration of renal function following administration of CM mediated to a large extent by the increased production of ROS within the kidney. Aim of this study was to evaluate whether a novel isoform of a recombinant Manganese SOD (rMnSOD) could provide an effective protection against CIN; this molecule shares the same ability of physiological SODs in scavenging reactive oxygen species (ROS) but, due to its peculiar properties, enters inside the cells after its administration. METHODS: We studied the effects rMnSOD on oxidative damage in a rat model of CIN in uninephrectomized rats, that were randomly assigned to 3 experimental Groups: Group CON, control rats treated with the vehicle of CM, Group HCM, rats treated with CM and Group SOD, rats treated with CM and rMnSOD. RESULTS: In normal rats, pretreatment with rMnSOD, reduced renal superoxide anion production, induced by the activation of NAPDH oxidase, by 84 % (p < 0.001). In rats of Group HCM, ROS production was almost doubled compared to rat of Group CON (p < 0.01) but returned to normal values in rats of Group SOD, where a significant increase of SOD activity was detected (+16 % vs HCM, p < 0.05). Administration of CM determined a striking fall of GFR in rats of Group HCM (-70 %, p < 0.001 vs CON), greatly blunted in Group SOD (-28 % vs CON, p < 0.01); this was associated with a lower presence of both tubular necrosis and intratubular casts in SOD-treated rats (both p < 0.01 vs Group HCM). CONCLUSIONS: Our data indicate that rMnSOD is able to reduce renal oxidative stress, thus preventing the reduction of GFR and the renal histologic damage that follows CM administration.

A new recombinant MnSOD prevents the cyclosporine A-induced renal impairment.

BACKGROUND: Cyclosporine A (CsA) is one of the most frequently used anticalcineurinic drugs for preventing graft rejection and autoimmune disease. Its use is hampered by nephrotoxic effects, namely an impairment of the glomerular filtration rate (GFR) and hypertension. Evidence suggests that reactive oxygen species (ROS) play a causal role in the nephrotoxicity. The present study aims to investigate in vivo the effects of a new recombinant mitochondrial manganese-containing superoxide dismutase (rMnSOD), a strong antioxidant, on the CsA-induced nephotoxicity. METHODS: Rats were treated with CsA (25 mg/kg/day) alone or in combination with rMnSOD (10 µg/kg/day) for 7 days. At the end of the treatment, GFR was estimated by inulin clearance (mL/min/100 g b.w.) and the mean arterial pressure (MAP) was recorded through a catheter inserted in the carotid artery. Superoxide concentration within the cells of the abdominal aorta was quantified from the oxidation of dihydroethidium (DHE). In kidney tissues, ROS levels were measured by the 2'7' dichloroflurescin diacetate assay. Renal morphology was examined at the histochemistry level. RESULTS: CsA-treated rats showed a severe decrease in GFR (0.34 ± 0.17 versus 0.94 ± 0.10 in control, P < 0.001) which was prevented by rMnSOD co-administration (0.77 ± 0.10). CsA-injected animals presented with higher blood pressure which was unaffected by rMnSOD. ROS levels both in the aorta and in renal tissue were significantly increased by CsA treatment, and normalized by the co-administration with rMnSOD. This effect was, partly, paralleled by the recovery from CsA-induced morphological lesions. CONCLUSIONS: Administration of rMnSOD prevents CsA-mediated impairment of the GFR along with morphological alteration. This effect could be related to the inhibition of ROS.

Ochratoxin A induces craniofacial malformation in mice acting on Dlx5 gene expression.

Ochratoxin A (OTA) is a mycotoxin produced by fungal of Aspergillus species absorbed in human through contaminate food in gastrointestinal tract. OTA has been demonstrated to be teratogenic in a number of species including mice and potentially human. Mice exposed in uterus to OTA develop craniofacial abnormalities such as exencephaly, microencephaly, microphthalmia and facial clefts. An important role in differentiation of maxillofacial are exerted by the Hox related genes Dlx and Msx. In the present investigation we have confirmed that 2.75 mg/kg body weight OTA, given at gestational day 7.5, induces significant developmental craniofacial anomalies in mice and we have demonstrated the down expression of Dlx5, a member of Dlx gene family, that seems to be responsible of the observed deformities. These results support the hypothesis that Dlx5 is a target for ochratoxin and the inhibition of its function, directly or indirectly, could be at origin of the observed differentiation defects.

A recombinant MnSOD is radioprotective for normal cells and radiosensitizing for tumor cells.

Organisms exposed to ionizing radiation are mainly damaged by free radicals, which are generated by the radiolysis of water contained in the cells. Recently a significant reduction of tissue injury from irradiation damage was demonstrated by using MnSOD-plasmid/liposome treatments in the protection of murine lung. In this study we show that a new active recombinant human MnSOD (rMnSOD), easily administered in vivo, not only exerts the same radioprotective effect on normal cells and organisms as any MnSOD, but it is also radiosensitizing for tumor cells. In addition, we show how healthy animals, exposed to lethal doses of ionizing radiation and daily injections with rMnSOD, were protected from radiodamage and were still alive 30 days after the irradiation, while animals treated with only PBS solution, in the absence of rMnSOD, died after 7-8 days from the radiotreatments. The molecular analysis of all irradiated tissues revealed that the antiapoptotic AVEN gene appeared activated only in the animals treated in the presence of rMnSOD. The data suggest that rMnSOD deserves to be considered as a pharmaceutical tool for making radiotherapy more selective on cancer cells and to prevent and/or cure the accidental damage derived from exposure to ionizing radiation.

Biophysical and biochemical characterization of a liposarcoma-derived recombinant MnSOD protein acting as an anticancer agent.

A recombinant MnSOD (rMnSOD) synthesized by specific cDNA clones derived from a liposarcoma cell line was shown to have the same sequence as the wild-type MnSOD expressed in the human myeloid leukaemia cell line U937, except for the presence of the leader peptide at the N-terminus. These results were fully confirmed by the molecular mass of rMnSOD as evaluated by ES/MS analysis (26662.7 Da) and the nucleotide sequence of the MnSOD cDNA. The role of the leader peptide in rMnSOD was investigated using a fluorescent and/or (68)Gallium-labelled synthetic peptide. The labelled peptide permeated MCF-7 cells and uptake could be inhibited in the presence of an excess of oestrogen. In vivo it was taken up by the tumour, suggesting that the molecule can be used for both therapy and diagnosis. The in vitro and in vivo pharmacology tests confirmed that rMnSOD is only oncotoxic for tumour cells expressing oestrogen receptors. Pharmacokinetic studies in animals performed with (125)I- and (131)I-labelled proteins confirmed that, when administered systemically, rMnSOD selectively reached the tumour, where its presence was unambiguously demonstrated by scintigraphic and PET scans. PCR analysis revealed that Bax gene expression was increased and the Bcl2 gene was down regulated in MCF7 cells treated with rMnSOD, which suggests that the protein induces a pro-apoptotic mechanism.

Tumor suppressive activity of a variant isoform of manganese superoxide dismutase released by a human liposarcoma cell line.

A cell line derived from a pleiomorphic liposarcoma, named LSA, was previously reported to secrete (a) factor(s) exhibiting oncotoxic properties. The present article describes the isolation, purification and sequence analysis of a protein released by LSA cells into conditioned culture medium. This protein proved to be a variant isoform of manganese superoxide dismutase (MnSOD), hence its designation as LSA-type-MnSOD. This LSA-type-SOD differed from conventional SODs in its secretion by producer cells, contrasting with the normal localization of SODs in the mitochondrial matrix. Interestingly, during the protein purification process, LSA-type-SOD cosegregated with a cytotoxic activity directed against a number of tumor cell lines, as determined under in vitro conditions. This cytopathic effect was most likely due to LSA-type-SOD, since it could be fully reproduced using recombinant SOD that was expressed from cDNA clones isolated from LSA cells mRNA preparations and henceforth designated L-rSOD. In addition to its manifestation in cell lines kept in tissue culture, the oncotoxicity of LSA-type-SOD was further reflected in a remarkable capacity of this protein for suppression of mammary tumors in Balb-C-FR(III) mice. Animals subcutaneously injected with L-rSOD in the tumor area showed a complete disruption of established mammary carcinomas, as monitored by nuclear magnetic resonance (NMR) scanning. Moreover, metastatic spreading, which was readily detected in the control group, was suppressed in the treated animals. Altogether these data suggest that LSA-type-SOD interferes with survival and spreading of neoplastically transformed cells and deserves to be future validated as a therapeutic agent against cancer, either alone or in combination with conventional treatments.