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PubMed2004

Luminal bacterial flora determines physiological expression of intestinal epithelial cytoprotective heat shock proteins 25 and 72.

Heat shock proteins (HSP) 25 and 72 are expressed normally by surface colonocytes but not by small intestinal enterocytes. We hypothesized that luminal commensal microflora maintain the observed colonocyte HSP expression. The ability of the small intestine to respond to bacteria and their products and modulate HSPs has not been determined. The effects of luminal bacterial flora in surgically created midjejunal self-filling (SFL) vs. self-emptying (SEL) small-bowel blind loops on epithelial HSP expression were studied. HSP25 and HSP72 expression were assessed by immunoblot and immunohistochemistry. SFL were chronically colonized, whereas SEL contained levels of bacteria normal for the proximal small intestine. SFL creation significantly increased HSP25 and HSP72 expression relative to corresponding sections from SEL. Metronidazole treatment, which primarily affects anaerobic bacteria as well as a diet lacking fermentable fiber, significantly decreased SFL HSP expression. Small bowel incubation with butyrate ex vivo induced a sustained and significant upregulation of HSP25 and altered HSP72 expression, confirming the role of short-chain fatty acids. To determine whether HSPs induction altered responses to an injury, effects of the oxidant, monochloramine, on epithelial resistance and short-circuit current (I(sc)) responses to carbachol and glucose were compared. Increased SFL HSP expression was associated with protection against oxidant-induced decreases in transmural resistance and I(sc) responses to glucose, but not secretory responses to carbachol. In conclusion, luminal microflora and their metabolic byproducts direct expression of HSPs in gut epithelial cells, an effect that contributes to preservation of epithelial cell viability under conditions of stress.

Animals↗
PubMed2005

Cytoprotective effects of heme oxygenase in acute renal failure.

Following ischemia, superoxide is produced during the reperfusion phase in various organs. In renal pathophysiology, excess of free heme, which is released from hemeproteins under these conditions, catalyzes the formation of further reactive oxygen species to accelerate cellular injuries. There is accumulating evidence suggesting that transcriptional activation of heme oxygenase (HO)-1, the rate-limiting enzyme in heme degradation as well as the 32-kDa heat shock protein, participates in the defense against oxidative tissue injuries. Ischemia followed by reperfusion of the rat kidney accompanies significant induction of HO-1 mRNA, protein and enzyme activity, which is in part mediated through a rapid and transient increase in microsomal heme concentration. Inhibition of HO activity by tin mesoporphyrin results in a sustained and enhanced increase in microsomal heme content, and significantly exacerbates renal function. In contrast, SnCl2 treatment, which specifically induces HO-1 mRNA and protein in the proximal tubular epithelial cells, prevents the ischemia-reperfusion-mediated increase in microsomal heme concentration, and ameliorates the ischemic renal injury. In addition to these findings, recent evidence on the role of HO-1 in the kidney pathophysiology is summarized, with a particular emphasis on its protective role in the ischemic acute renal failure.

Acute Kidney Injury↗
PubMed2005

In vitro comparison of cytoprotective and antioxidative effects of latanoprost, travoprost, and bimatoprost on conjunctiva-derived epithelial cells.

PURPOSE: In a previous study, it was demonstrated that in vitro in a human conjunctiva-derived cell line, latanoprost in its commercial presentation appeared to be less toxic than the benzalkonium chloride (BAC) it contains as a preservative. Through a microplate cytometry technique, the investigation was furthered by study of whether the three commercially available antiglaucoma prostaglandin analogs could protect the same cell line in vitro against BAC toxicity and whether an antioxidative mechanism could be involved in such prostaglandin effects. METHODS: Human conjunctiva-derived epithelial cells from the Chang cell line were exposed to three prostaglandins in their commercial presentation (latanoprost, travoprost, and bimatoprost) and to three concentrations of BAC (0.02%, 0.015%, and 0.005%), corresponding to the concentrations contained in the three prostaglandin eyedrops. Each solution was diluted to 1/10 and was applied for 30 minutes Cellular membrane integrity, cytosolic H2O2, cytosolic O2*- and apoptosis were evaluated using neutral red, H2DCF-DA, hydroethidine, and Yopro-1 probes, respectively. RESULTS: Cellular viability decreased as BAC concentration increased, but it was accompanied by concentration-dependent toxicity. Toxicity of latanoprost and travoprost commercial solutions was statistically significantly lower than their respective BAC concentrations (P < 0.01), whereas bimatoprost induced no significant effects. There was a statistically significant decrease in H2O2 detection with cells exposed to latanoprost (P < 0.01) and travoprost (P < 0.01) and a lower detection of O2*- with cells exposed to latanoprost (P < 0.01) compared with the corresponding BAC concentration alone. The Yopro-1 test showed a BAC-induced apoptotic effect that increased with its concentration. Latanoprost and travoprost produced proapoptotic effects compared with control (P < 0.01), but these were lower than their respective preservative concentrations (statistically significant difference; P < 0.01). CONCLUSIONS: Latanoprost and travoprost were responsible for significant protective effects against BAC toxicity on conjunctiva-derived epithelial cells in vitro, probably related to their antioxidative properties. The low toxicity of the bimatoprost solution did not reveal a possible antioxidative effect. Reduced reactive oxygen species production could be the main mechanism by which prostaglandin analogs protect epithelial cells from the proapoptotic effects of BAC. Further studies will be useful to confirm this hypothesis.

Amides↗
PubMed2005

Organic osmolytes as compatible, metabolic and counteracting cytoprotectants in high osmolarity and other stresses.

Organic osmolytes are small solutes used by cells of numerous water-stressed organisms and tissues to maintain cell volume. Similar compounds are accumulated by some organisms in anhydrobiotic, thermal and possibly pressure stresses. These solutes are amino acids and derivatives, polyols and sugars, methylamines, methylsulfonium compounds and urea. Except for urea, they are often called ;compatible solutes', a term indicating lack of perturbing effects on cellular macromolecules and implying interchangeability. However, these features may not always exist, for three reasons. First, some of these solutes may have unique protective metabolic roles, such as acting as antioxidants (e.g. polyols, taurine, hypotaurine), providing redox balance (e.g. glycerol) and detoxifying sulfide (hypotaurine in animals at hydrothermal vents and seeps). Second, some of these solutes stabilize macromolecules and counteract perturbants in non-interchangeable ways. Methylamines [e.g. trimethylamine N-oxide (TMAO)] can enhance protein folding and ligand binding and counteract perturbations by urea (e.g. in elasmobranchs and mammalian kidney), inorganic ions, and hydrostatic pressure in deep-sea animals. Trehalose and proline in overwintering insects stabilize membranes at subzero temperatures. Trehalose in insects and yeast, and anionic polyols in microorganisms around hydrothermal vents, can protect proteins from denaturation by high temperatures. Third, stabilizing solutes appear to be used in nature only to counteract perturbants of macromolecules, perhaps because stabilization is detrimental in the absence of perturbation. Some of these solutes have applications in biotechnology, agriculture and medicine, including in vitro rescue of the misfolded protein of cystic fibrosis. However, caution is warranted if high levels cause overstabilization of proteins.

Adaptation, Physiological↗
PubMed2006

Heat-shock proteins: new keys to the development of cytoprotective therapies.

As molecular chaperones, heat-shock proteins (HSPs) function to limit protein aggregation, facilitate protein refolding and chaperone other proteins. Under conditions of cellular stress, intracellular HSP levels increase in order to provide cellular protection and maintain homeostasis. Evidence exists that the HSP family may be secreted into the circulation via lipid raft-mediated, granule-mediated or exosome-mediated exocytosis in haematopoietic and tumour cells. Extracellular HSPs exert immunomodulatory activities and play an important role in innate immune activation against pathogen infection. Membrane-bound Hsp70 in tumour cells or released chaperone-tumour associated antigen complex represent a target structure for the cytolytic attack by natural killer cells or T lymphocytes. Cellular stresses induce stress granule formation to evade detrimental cellular effects, mediating preconditioning phenotype. Therefore, induction of cellular stress tolerance by preconditioning (e.g., heat shock) might be potential therapeutic targets.

Animals↗
PubMed2006

Peroxiredoxin 6 is a potent cytoprotective enzyme in the epidermis.

Peroxiredoxin 6 is an enzyme that detoxifies hydrogen peroxide and various organic peroxides. In previous studies we found strongly increased expression of peroxiredoxin 6 in the hyperproliferative epidermis of wounded and psoriatic skin, suggesting a role of this enzyme in epidermal homeostasis. To address this question, we generated transgenic mice overexpressing peroxiredoxin 6 in the epidermis. Cultured keratinocytes from transgenic mice showed enhanced resistance to the toxicity of various agents that induce oxidative stress. However, overexpression of peroxiredoxin 6 did not affect skin morphogenesis or homeostasis. On skin injury, enhancement of wound closure was observed in aged animals. Most importantly, peroxiredoxin 6 overexpression strongly reduced the number of apoptotic cells after UVA or UVB irradiation. These findings demonstrate that peroxiredoxin 6 protects keratinocytes from cell death induced by reactive oxygen species in vitro and in vivo, suggesting that activation of this enzyme could be a novel strategy for skin protection under stress conditions.

Animals↗
PubMed1998

Role of tetrahydrobiopterin in the function of nitric oxide synthase, and its cytoprotective effect (Review).

This review discusses the role of (6R)-5,6,7,8-tetrahydrobiopterin (H4 biopterin) in the function of nitric oxide synthase (NOS), and the protective effect of H4 biopterin against nitric oxide (NO)- and/or reactive oxygen species-induced cytotoxicity. Although NOS releases NO, which regulates vascular tone and immune surveillance under normal conditions, NOS seems to produce superoxide anion and hydrogen peroxide when H4 biopterin, one of the cofactors, or L-arginine, a substrate, is decreased, suggesting the possibility that NOS is a source of reactive oxygen species under pathological conditions. Moreover, simultaneous release of NO and reactive oxygen species in the presence of suboptimal concentrations of H4 biopterin and/or L-arginine may be highly toxic, since NO reacts with superoxide anion and hydrogen peroxide to form peroxynitrite, singlet oxygen and the hydroxyl radical, which are toxic. An increase in H4 biopterin content in cells obviates NOS dysfunction (production of reactive oxygen species instead of NO) and protects the cells against NOS dysfunction-related cell injury. Moreover, H4 biopterin has a strong scavenging activity for reactive oxygen species, and inhibits thier cytotoxicity. H4 biopterin is also likely to reduce NO-induced cytotoxicity. Thus, H4 biopterin is not only an important regulator of NOS function, but is also an intracellular antioxidant. NO and reactive oxygen species are known to be implicated in the development of many pathological states. It is possible that H4 biopterin could be effective for treating many diseases, such as ischemia-reperfusion injury, inflammation and diabetes mellitus.

Biopterins↗
PubMed1998

[Cytoprotection of the endothelium cells in primary hypertension].

Normal endothelium cells play a huge role in small blood vessels function. It's not only physical barrier between blood and surrounding structures, but also producers a lot vasodilatators and vasodepresors. It's controlled by blood humoral factors plaing important role on blood circulation physiology. Endothelium cells injury gives its function abnormality local and general as well. The main injury factor is hypertension, which provides to endothelium disfunction with vasopressors level growth which induces hypertension. Also primary endothelial injury induces hypertension and atherogenesis.

Antihypertensive Agents↗
PubMed1999

[Cytoprotection with amifostine in the framework of radiochemotherapy in previously irradiated head and neck carcinoma].

PURPOSE: The radiotherapeutic possibilities are limited for patients with a recurrent or second head and neck cancer if the patient was already irradiated in the first therapy. In the presented study we investigated the changes of this situation due to the usage of amifostine in the case of re-irradiation (simultaneous radio-chemotherapy). PATIENTS AND METHODS: Between 1995 and 1997 we treated 14 patients with a recurrent or second malignancy of the head and neck region by a simultaneous radio-chemotherapy (20 x 1.5 Gy, Carboplatin 70 mg/m2 BSA on days 1 to 5 and 16 to 20, 500 mg amifostine prior to every carboplatin infusion). Six out of 14 patients got an additional brachytherapy (10 to 15 Gy) to increase the local dose because of a residual tumor. In 4 cases the treatment was an adjunctive one, following the surgical tumor debulking. RESULTS: We have seen 3 complete remissions (21.4%), and 8 partial remissions (57.1%). The median time of observation is 13 months now. Three out of 14 patients died, 2 because of the tumor. Hematological toxicities: side effects Grade 2 WHO were seen only in 1 patient. Acute non-hematological toxicities: mucositis Grade 0/1 in 7 patients, mucositis Grade 2 in 7 patients, dysphagia Grade 0/1 in 9 patients, dysphagia Grade 2 in 5 patients, xerostomia Grade 1 in 9 patients, xerostomia Grade 2 in 3 patients. We registrated only 1 serious late toxicity due to radio-chemotherapy: 4 months after brachytherapy a patient (with laryngectomy) developed a submental fistula. CONCLUSION: These first results suggest that the usage of amifostine offers new potential ways for re-irradiation of patients with recurrent or second malignancies in the head neck region.

Adult↗
PubMed2000

Metallothionein acts as a cytoprotectant against doxorubicin toxicity.

The protective role of metallothionein (MT) against the myocardiotoxicity and hepatotoxicity of doxorubicin (Dox) was investigated in mice. Dox-induced elevations of plasma creatine kinase activity, a measure of myocardiac damage, and plasma glutamate pyruvate transaminase activity, reflecting hepatic damage, were prevented by pretreatment with an MT inducer. Pretreatment with zinc induced MT in the liver and heart, thereby reducing Dox toxicity in these two organs. Pretratment with n-hexane also induced MT and reduced Dox toxicity, but only in the liver. In primary hepatocyte cultures, the leakage of lactate dehydrogenase induced by Dox was prevented by zinc pretreatment. These results suggest that MT induction prevents Dox toxicity in vivo and in vitro. Furthermore, we determined that MT-null mice were more sensitive to the myocardiotoxic and hepatotoxic effects of Dox. These findings indicate that both basal and induced MT protect against Dox toxicity.

Alanine Transaminase↗