Chronic antioxidant enzyme mimetic treatment differentially modulates hyperthermia-induced liver HSP70 expression with aging

Dietary ferulic acid supplementation improves antioxidant capacity and lipid metabolism in liver of piglets with intrauterine growth retardation

Intrauterine growth retardation (IUGR) can result in early liver oxidative damage and abnormal lipid metabolism in neonatal piglets. Ferulic acid (FA), a phenolic compound widely found in plants, has many biological functions, such as anti-inflammation and anti-oxidation. Thus, we explored the effects of dietary FA supplementation on antioxidant capacity and lipid metabolism in newborn piglets with IUGR. In the study, 24 7-day-old piglets were divided into three groups: normal birth weight (NBW), IUGR, and IUGR + FA. The NBW and IUGR groups were fed formula milk as a basal diet, while the IUGR + FA group was fed a basal diet supplemented with 100 mg/kg FA. The trial lasted 21 days. The results showed that IUGR decreased absolute liver weight, increased transaminase activity, reduced antioxidant capacity, and disrupted lipid metabolism in piglets. Dietary FA supplementation enhanced absolute liver weight, reduced serum MDA level and ROS concentrations in serum and liver, markedly increased serum and liver GSH-PX and T-SOD activities, decreased serum HDL-C and LDL-C and liver NEFA, and increased TG content and HL activity in the liver. The mRNA expression related to the Nrf2-Keap1 signaling pathway and lipid metabolism in liver were affected by IUGR. Supplementing FA improved the antioxidant capacity of liver by down-regulating Keap1 and up-regulating the mRNA expression of SOD1 and CAT, and regulated lipid metabolism by increasing the mRNA expression level of Fasn, Pparα, LPL, and CD36. In conclusion, the study suggests that FA supplementation can improve antioxidant capacity and alleviate lipid metabolism disorders in IUGR piglets.

Altered accumulation of hepatic mitochondrial antioxidant proteins with age and environmental heat stress

Aging impairs overall physiological function, particularly the response to environmental stressors. Repeated heat stress elevates reactive oxygen species and macromolecular damage in the livers of aged animals, likely due to mitochondrial dysfunction. The goal of this investigation was to determine potential mechanisms for mitochondrial dysfunction after heat stress by evaluating key redox-sensitive and antioxidant proteins (Sirt-3, MnSOD, Trx-2, and Ref-1). We hypothesized that heat stress would result in greater mitochondrial abundance of these proteins, but that aging would attenuate this response. For this purpose, young (6 mo) and old (24 mo) Fisher 344 rats were exposed to heat stress on two consecutive days. During each heating trial, colonic temperature was elevated to 41°C during the first 60 min, and then clamped at this temperature for 30 min. Nonheated animals served as controls. At 2 and 24 h after the second heat stress, hepatic mitochondria were isolated from each animal, and then immunoblotted for Sirt-3, acetylated lysine residues (Ac-K), MnSOD, Trx-2, and Ref-1. Aging increased Sirt-3 and lowered Ac-K. In response to heat stress, Sirt-3, Ac-K, MnSOD, and Ref-1 increased in mitochondrial fractions in both young and old animals. At 2 h after the second heat stress, mitochondrial Trx-2 declined in old, but not in young animals. Our results suggest that some components of the response to heat stress are preserved with aging. However, the decline in Trx-2 represents a potential mechanism for age-related mitochondrial damage and dysfunction after heat stress.NEW & NOTEWORTHY Our results suggest heat stress-induced mitochondrial translocation of Sirt-3, MnSOD, and Ref-1 in young and old animals. Aged rats experienced a decline in Trx-2 after heat stress, suggesting a potential mechanism for age-related mitochondrial dysfunction.

Higher Concentration of Dietary Selenium, Zinc, and Copper Complex Reduces Heat Stress-Associated Oxidative Stress and Metabolic Alteration in the Blood of Holstein and Jersey Steers

This study investigated the influence of high concentrations of dietary minerals on reducing heat stress (HS)-associated oxidative stress and metabolic alterations in the blood of Holstein and Jersey steers. Holstein steers and Jersey steers were separately maintained under a 3 × 3 Latin square design during the summer conditions. For each trial, the treatments included Control (Con; fed basal TMR without additional mineral supplementation), NM (NRC recommended mineral supplementation group; [basal TMR + (Se 0.1 ppm + Zn 30 ppm + Cu 10 ppm) as DM basis]), and HM (higher than NRC recommended mineral supplementation group; [basal TMR + (Se 3.5 ppm + Zn 350 ppm + Cu 28 ppm) as DM basis]). Blood samples were collected at the end of each 20-day feeding trial. In both breeds, a higher superoxide dismutase concentration (U/mL) along with lower HSP27 (μg/L) and HSP70 (μg/L) concentrations were observed in both mineral-supplemented groups compared to the Con group (p < 0.05). The HM group had significantly higher lactic acid levels in Jersey steers (p < 0.05), and tended to have higher alanine levels in Holstein steers (p = 0.051). Based on star pattern recognition analysis, the levels of succinic acid, malic acid, γ-linolenic acid, 13-methyltetradecanoic acid, and tyrosine decreased, whereas palmitoleic acid increased with increasing mineral concentrations in both breeds. Different treatment groups of both breeds were separated according to the VIP scores of the top 15 metabolites through PLS−DA analysis; however, their metabolic trend was mostly associated with the glucose homeostasis. Overall, the results suggested that supplementation with a higher-than-recommended concentration of dietary minerals rich in organic Se, as was the case in the HM group, would help to prevent HS-associated oxidative stress and metabolic alterations in Holstein and Jersey steers.

Targeting oxidative stress in disease: promise and limitations of antioxidant therapy

Oxidative stress is a component of many diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer disease and cancer. Although numerous small molecules evaluated as antioxidants have exhibited therapeutic potential in preclinical studies, clinical trial results have been disappointing. A greater understanding of the mechanisms through which antioxidants act and where and when they are effective may provide a rational approach that leads to greater pharmacological success. Here, we review the relationships between oxidative stress, redox signalling and disease, the mechanisms through which oxidative stress can contribute to pathology, how antioxidant defences work, what limits their effectiveness and how antioxidant defences can be increased through physiological signalling, dietary components and potential pharmaceutical intervention.

Alpha lipoic acid supplementation ameliorates the wrath of simulated tropical heat and humidity stress in male Murrah buffaloes

A supplement which ameliorates temperature-humidity menace in food producing livestock is a prerequisite to develop climate smart agricultural packages. A study was conducted to investigate the heat stress ameliorative efficacy of alpha lipoic acid (ALA) in male Murrah water buffaloes (Bubalus bubalis). Eighteen animals (293.61 ± 4.66Kg Bwt) were randomly allocated into three groups (n = 6); NHSC (non-heat-stressed control), HS (heat-stressed) and HSLA (heat-stressed-supplemented with ALA@32 mg/kg Bwt orally) based on the temperature humidity index (THI) and ALA supplementation. HS and HSLA were exposed to simulated heat challenge in a climatically controlled chamber (40 °C) for 21 consecutive days, 6 h daily. Physiological responses viz. Respiration rate (RR), Pulse rate (PR) and Rectal temperature (RT) were recorded daily before and after heat exposure. Blood samples were collected at the end of heat exposure on days 1, 6, 11, 16, and 21 and on day 28 (7th day post exposure which is considered as recovery) for peripheral blood mononuclear cells (PBMCs) separation, followed by RNA and Protein extraction for Real time quantitative PCR and Western blot analysis respectively, of heat shock proteins (HSPs). Two-way repeated measure ANOVA was performed between groups at different experimental periods. RR (post exposure) in HS and HSLA was significantly higher (P < 0.05) than NHSC from day 1 onwards but HSLA varied significantly from the HS 8th day onwards. Post exposure RT and PR in both HS and HSLA varied (P < 0.05) from NHSC throughout the study; but between HS and HSLA, RT significantly varied on initial 2 days and last 6 days (from days 16 to 21). HSP70 mRNA expression significantly up regulated in high THI groups with respect to the low THI group throughout the experimental period. During chronic stress (days 16 and 21) HSP70 significantly (P < 0.05) increased in HS but not in HSLA (P > 0.05) with respect to NHSC. ALA supplementation up-regulates and sustains (P < 0.05) the expression of HSP90 in HSLA in comparison to the HS and NHSC. HSP105 expression was significantly up-regulated (P < 0.05) in HS on days 16 and 21 (during long-term exposure) but only on day 21 (P < 0.05) in HSLA. HSP70, HSP90, and HSP105 protein expression dynamics were akin to the mRNA transcript data between the study groups. In conclusion, supplementing ALA ameliorates the deleterious effect of heat stress as reflected by improved physiological and cellular responses. ALA supplementation improved cellular antioxidant status and sustained otherwise easily decaying heat shock responses which concertedly hasten the baton change from a limited window of thermo tolerance to long run acclimatization.

Impacts of selenium and vitamin E supplementation on mRNA of heat shock proteins, selenoproteins and antioxidants in broilers exposed to high temperature

The study was carried out to investigate the effect of dietary selenium (Se) and vitamin E (VE) supplementation on mRNA level of heat shock proteins, selenoproteins, and antioxidant enzyme activities in the breast meat of broilers under summer heat stress conditions. A total of 200 male broilers (Ross 308) of 1 day age were randomly separated into 4 groups in a complete randomized design and were given a basal diet (Control, 0.08 mg Se/kg diet) or basal diet supplemented with VE (250 mg/kg VE), sodium selenite (0.2 mg/kg Se), or Se + VE (0.2 mg/kg Se + 250 mg/kg VE) to investigate the expression of key antioxidant and heat shock protein (HSP) genes under high temperature stress. Dietary Se, VE and Se + VE significantly enhanced the activities and mRNA levels of catalase as well as superoxide dismutase (SOD) but decreased the mRNA levels of HSP70 and HSP90. Se alone or combined with VE increased the concentration of selenoprotein P and selenoproteins mRNA level and decreased the expression of HSP60. In addition, Se and Se + VE significantly enhanced the glutathione peroxidase (GPx) activity and the expression of GPx1 and GPx4 in breast muscle tissues. It is noteworthy that all the treatments significantly decreased malondialdehyde (MDA) level in the breast meat. Overall results showed that Se in combination with VE has maximal effects to mitigate heat stress. Based on given results it can be recommended that Se + VE are a suitable dietary supplement for broilers to ameliorate the negative effects of summer heat stress conditions.

Heat Shock Protein 70 Expression is Increased in the Liver of Neonatal Intrauterine Growth Retardation Piglets

Intrauterine growth retardation (IUGR) leads to the dysfunction in digestive system, as well as the alteration in the expression of some functional proteins. Heat shock protein 70 (Hsp70) could be induced by various stress factors, but whether Hsp70 expression is changed in neonatal IUGR infants has not been demonstrated. This study was conducted to explore the expression of Hsp70 in the liver by using the IUGR piglet model. Liver and plasma samples were obtained from IUGR and normal birth weight (NBW) piglets at birth. The neonatal IUGR piglets had significantly lower liver weight than their counterparts. The activities of aspartate aminotransferase and alanine aminotransferase in serum were enhanced significantly in IUGR indicating liver dysfunction. The activities of superoxide dismutase (p<0.01), glutathione peroxidase (p<0.01) and catalase (p>0.05) were lower and the level of malondialdehybe was higher (p<0.05) in IUGR liver compared with in NBW. According to the results of histological tests, fatty hepatic infiltrates and cytoplasmic vacuolization were present in the liver of IUGR piglets, but not in NBW liver. The expression of Hsp70 protein was significantly higher (p<0.05) in IUGR piglet liver than in NBW. Similar to where the hepatic injuries were observed, location of Hsp70 was mostly in the midzonal hepatic lobule indicating that oxidative stress might be responsible for the increased expression of Hsp70.

Strategies to decrease ongoing oxidant burden in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity globally, and its development is mainly associated with tobacco/biomass smoke-induced oxidative stress. Hence, targeting systemic and local oxidative stress with agents that can balance the antioxidant/redox system can be expected to be useful in the treatment of COPD. Preclinical and clinical trials have revealed that antioxidants/redox modulators can detoxify free radicals and oxidants, control expression of redox and glutathione biosynthesis genes, chromatin remodeling and inflammatory gene expression; and are especially useful in preventing COPD exacerbations. In this review, various novel approaches and problems associated with these approaches in COPD are reviewed.

Pharmacological antioxidant strategies as therapeutic interventions for COPD

Cigarette/tobacco smoke/biomass fuel-induced oxidative and aldehyde/carbonyl stress are intimately associated with the progression and exacerbation of chronic obstructive pulmonary disease (COPD). Therefore, targeting systemic and local oxidative stress with antioxidants/redox modulating agents, or boosting the endogenous levels of antioxidants are likely to have beneficial effects in the treatment/management of COPD. Various antioxidant agents, such as thiol molecules (glutathione and mucolytic drugs, such as N-acetyl-L-cysteine and N-acystelyn, erdosteine, fudosteine, ergothioneine, and carbocysteine), have been reported to modulate various cellular and biochemical aspects of COPD. These antioxidants have been found to scavenge and detoxify free radicals and oxidants, regulate of glutathione biosynthesis, control nuclear factor-kappaB (NF-kappaB) activation, and hence inhibiting inflammatory gene expression. Synthetic molecules, such as specific spin traps like α-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (ECSOD mimetic), porphyrins (AEOL 10150 and AEOL 10113), and a superoxide dismutase mimetic M40419, iNOS and myeloperoxidase inhibitors, lipid peroxidation inhibitors/blockers edaravone, and lazaroids/tirilazad have also been shown to have beneficial effects by inhibiting cigarette smoke-induced inflammatory responses and other carbonyl/oxidative stress-induced cellular alterations. A variety of oxidants, free radicals, and carbonyls/aldehydes are implicated in the pathogenesis of COPD, it is therefore, possible that therapeutic administration or supplementation of multiple antioxidants and/or boosting the endogenous levels of antioxidants will be beneficial in the treatment of COPD. This review discusses various novel pharmacological approaches adopted to enhance lung antioxidant levels, and various emerging beneficial and/or prophylactic effects of antioxidant therapeutics in halting or intervening the progression of COPD. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Treatment of chronic hepatitis C in elderly patients

IMPORTANCE OF THE FIELD

The issue of age in cases of chronic hepatitis C (HCV) in the West is a major problem; the average age of patients with HCV is increasing and its prevalence increases with advancing age.

AREAS COVERED IN THIS REVIEW

This review is devoted to the analysis of the limited number of clinical studies performed to treat HCV in elderly patients.

WHAT THE READER WILL GAIN

The importance of the age factor is outlined in nearly all the studies done in the field. Advanced age is associated with a lower sustained virologic response (SVR) rate. Moreover, in elderly patients, these studies also tend to suggest that, before initiating an antiviral treatment, the physician should not only take into account the classical parameters associated with SVR but also the presence of co-morbidities and life expectancy. TAKE-HOME MESSAGES: Antiviral therapy should be used in selected elderly HCV patients with advanced fibrosis and more studies are required in this population to better define the parameters associated with SVR. As age is an important factor in the success of antiviral therapy, starting antiviral treatment at a young age should be favored.

Diminished reproductive potential of male mice in response to selenium-induced oxidative stress: involvement of HSP70, HSP70-2, and MSJ-1

The oxidative stress imposed by nutritional variations in selenium (Se) has plausible role in reproductive toxicology and affects the reproductive potential. Also, the expression of heat shock proteins (HSPs) is a highly regulated event throughout the process of spermatogenesis and is modulated by stressful stimuli. This prompted us to investigate the possibility that Se-induced oxidative stress may affect the fertility status by altering the expressions of the constitutive and inducible HSP70 proteins, having crucial role in spermatogenesis. Different Se status-deficient, adequate, and excess, male Balb/c mice were created by feeding yeast-based Se-deficient diet (group I) and deficient diet supplemented with Se as sodium selenite at 0.2 and 1 ppm Se (group II and III) for a period of 8 weeks. After completion of the diet-feeding schedule, a significant decrease in the Se and glutathione peroxidase (GSH-Px) levels was observed in the Se-deficient group (I), whereas Se-excess group (III) demonstrated an increase. Increased levels of reactive oxygen species, malondialdehyde, and alterations in the redox status in both groups I and III indicated oxidative-stressed conditions. There was an overall reduced fertility status in mice supplemented with Se-deficient and Se-excess diet. The mRNA and protein expression of HSP70 was found to be elevated in these two groups, whereas the expression patterns of HSP70-2 and MSJ-1 demonstrated a reverse trend. In vitro CDC2 kinase assay showed reduced kinase activity in group I and group III. These findings suggest that Se-induced oxidative stress by differentially regulating various HSP70s can affect its downstream factors having crucially important role in differentiation of germ cells and completion of spermatogenesis. Therefore, it can provide an insight into the mechanism(s) by which the oxidative stress-induced reproductive toxicity can lead to increased apoptosis/growth arrest and infertility. This will thus add new dimensions to the molecular mechanism underlying the human male infertility and open new vistas in the development of various chemo-preventive methods.

Differential regulation of hepatic heme oxygenase-1 protein with aging and heat stress

Increased expression of heme oxygenase-1 (HO-1) in response to physiological stress is considered to be a protective response, which may be altered with aging. In this study, HO-1 expression was assessed following heat stress by immunoblotting of liver homogenates and isolated hepatocytes from young (6 months) and old (24 months) Fischer 344 rats and by immunohistochemistry. Livers of old rats showed higher baseline levels of HO-1, which was predominately localized to Kupffer cells. After heat stress, young animals showed a greater relative increase in hepatic HO-1, part of which was caused by increased numbers of nonparenchymal cells that were immunoreactive to HO-1. Consistent with these data, HO-1 was significantly upregulated after hyperthermia in vitro only in hepatocytes from young rats. Hence, aging alters stress-induced expression of HO-1 in a cell-specific manner, which may contribute to the diminished stress tolerance observed in older organisms.

Aging augments mitochondrial susceptibility to heat stress

The pathophysiology of aging is accompanied by a decline in tolerance to environmental stress. While mitochondria are primary suspects in the etiology of aging, little is known about their ability to tolerate perturbations to homeostasis in older organisms. To investigate the role of mitochondria in the increased susceptibility to heat stress that accompanies aging, young and old Fischer 344 rats underwent a heat stress protocol known to elicit exaggerated cellular damage with aging. At either 2 or 24 h after heat stress, livers were removed from animals, and hepatic mitochondria were isolated. Electron microscopy revealed extensive morphological damage to mitochondria from young and, to a greater extent, old rats after heat stress. There was also a significant loss of cytochrome c from old, but not young, mitochondria and a persistent increase in 4-hydroxynonenal-modified proteins in old vs. young mitochondria exposed to heat stress. Electron paramagnetic resonance measurements of superoxide indicate greater superoxide production from mitochondria of old compared with young animals and suggest that mitochondrial integrity was altered during heat stress. The mitochondrial stress response, which functions to correct stress-induced damage to mitochondrial proteins, was also blunted in old rats. Delayed and reduced levels of heat shock protein 60 (Hsp60), the main inducible mitochondrial stress protein, were observed in old compared with young mitochondria after heat stress. Additionally, the amount of Hsp10 protein increased in young, but not old, rat liver mitochondria after hyperthermic challenge. Taken together, these data suggest that mitochondria in old animals are more vulnerable to incurring and less able to repair oxidative damage that occurs in response to a physiologically relevant heat stress.

Catalase and glutathione peroxidase mimics

Overproduction of the reactive oxygen species (ROS) superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)) are increasingly implicated in human disease and aging. ROS are also being explored as important modulating agents in a number of cell signaling pathways. Earlier work has focused on development of small catalytic scavengers of O(2)(-), commonly referred to as superoxide dismutase (SOD) mimetics. Many of these compounds also have substantial abilities to catalytically scavenge H(2)O(2) and peroxynitrite (ONOO(-)). Peroxides have been increasingly shown to disrupt cell signaling cascades associated with excessive inflammation associated with a wide variety of human diseases. Early studies with enzymatic scavengers like SOD frequently reported little or no beneficial effect in biologic models unless SOD was combined with catalase or a peroxidase. Increasing attention has been devoted to developing catalase or peroxidase mimetics as a way to treat overt inflammation associated with the pathophysiology of many human disorders. This review will focus on recent development of catalytic scavengers of peroxides and their potential use as therapeutic agents for pulmonary, cardiovascular, neurodegenerative and inflammatory disorders.

Aging results in increased autophagy of mitochondria and protein nitration in rat hepatocytes following heat stress

The natural breakdown of cells, tissues, and organ systems is a significant consequence of aging and is at least partially caused by a decreased ability to tolerate environmental stressors. Based on quantitative ultrastructural analysis using transmission electron microscopy and computer imaging, we show significant differences in hepatocyte morphology between young and old rats during a 48-hr recovery period following a 2-day heat stress protocol. Mitochondrial injury was greater overall in old compared with young rats. Autophagy was observed in both young and old rats, with autophagy greater overall in old compared with young hepatocytes. Lipid peroxidation and protein nitration were evaluated by localization and quantification of 4-hydroxy-2-nonenal (4-HNE)-modified protein adducts and 3-nitrotyrosine (3-NT) levels, respectively. Levels of 3-NT but not 4-HNE-protein adducts were significantly elevated in hepatocytes of old rats in comparison with young at 90 min after heat stress, suggesting a major role for reactive nitrogen species in the pathology observed at this time point. These results show a differential response of hepatocyte mitochondria to heat stress with aging, as well as greater levels of both autophagic and nitrative damage in old vs young hepatocytes. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Mechanisms of aging and liver functions

BACKGROUND/AIMS

Morphofunctional studies suggest that the liver, compared with other organs, ages fairly well. Its success is ascribable to its lasting ability to regenerate, even if the potential of the cells to replicate progressively declines with age. The aim of this study was to analyze some aspects of the early phases of liver regeneration, its capacity to mount a stress response, and the inflammatory response in the early stage of an acute injury.

METHODS

Rats aged 2, 6, 12 and 19 months received a single intraperitoneal injection of CCl(4), and morphological, biochemical and molecular evaluations were done 2 and 24 h later.

RESULTS

AST and ALT, starting at age 12 months, were significantly higher than in the younger rats after CCl(4). Histological modifications were already detectable after 2 h in rats aged 12 and 19 months, thereafter becoming more diffuse and marked, whereas they become evident only 24 h after the intoxication in rats aged 2 and 6 months. Albumin, c-fos, c-myc, hepatocyte growth factor, transforming growth factor-alpha and HSP70 mRNA levels decreased 24 h after CCl(4 )starting at age 12 months. Mast cell density was higher in the young rats than the old ones.

CONCLUSION

Our results point to: (a) a basically preserved regenerative response of the aged liver, although somehow weaker and slower, with reduced ability to counteract agents inducing cell necrosis; (b) a decrease in the HSP70 response suggesting a reduction in homeostatic capacity, and (c) a lower inflammatory response during aging.

Hsp70 Chaperone as a Survival Factor in Cell Pathology

Heat shock protein Hsp70 is implicated in the mechanism of cell reaction to a variety of cytotoxic factors. The protective function of Hsp70 is related to its ability to promote folding of nascent polypeptides and to remove denatured proteins. Many types of cancer cells contain high amounts of Hsp70, whose protective capacity may pose a problem for therapy in oncology. Hsp70 was shown to be expressed on the surface of cancer cells and to participate in the presentation of tumor antigens to immune cells. Therefore, the chaperone activity of Hsp70 is an important factor that should be taken into consideration in cancer therapy. The protective role of Hsp70 is also evident in neuropathology. Many neurodegenerative processes are associated with the accumulation of insoluble aggregates of misfolded proteins in neural cells. These aggregates hamper intracellular transport, inhibit metabolism, and activate apoptosis through diverse pathways. The increase of Hsp70 content results in the reduction of aggregate size and number and ultimately enhances cell viability.