Influence of heat shock protein 70 and metallothionein induction by zinc-bis-(DL-hydrogenaspartate) on the release of inflammatory mediators in a porcine model of recurrent endotoxemia

Heat Hardening Ameliorates Apoptotic and Inflammatory Effects Through Increased Autophagy in Mussels

The severity, frequency, and duration of extreme events, in the context of global warming, have placed many marine ecosystems at high risk. Therefore, the application of methods that can mediate the impacts of global warming on marine organisms seems to be an emerging necessity in the near term. In this context, enhancing the thermal resilience of marine organisms may be crucial for their sustainability. It has been shown that the repeated time-limited exposure of an organism to an environmental stimulus modifies its response mode, thus enhancing resilience and allowing adaptation of the physiological and developmental phenotype to environmental stress. In the present study, we investigated the "stress memory" effect caused by heat hardening on Mytilus galloprovincialis cellular pathways to identify the underlying biochemical mechanisms that enhance mussel thermal tolerance. Heat hardening resulted in increased ETS activity and ATP production and increased autophagic performance at all elevated temperatures (24 °C, 26 °C, and 28 °C). Furthermore, at these increased temperatures, apoptosis and inflammation remain at significantly lower levels in pregnant individuals than in nonhardened individuals. Autophagy, as a negative regulator of apoptosis, may lead to decreased damage to surrounding cells, which in turn alleviates inflammatory effects. In conclusion, the exposure of mussels to heat hardening seems to provide a physiological response that enhances heat tolerance and increases cell survival through increased energy production and reduced cell death and inflammatory responses. The latter can be utilized for the management and conservation of aquatic species of economic value or endangered status.

Low concentration zinc oxide nanoparticles enrichment enhances bacterial and pro-inflammatory resistance of calcium silicate-based cements

Calcium silicate-based cement (CSC) is a commonly used material in endodontic treatment. However, it has limited antibacterial activity, especially for cases involving primary infections. Zinc oxide nanoparticles (ZnO-NPs) are recognized for their potential in biomedical applications due to their antibacterial properties and ability to reduce inflammation. This study aims to optimize CSC by incorporating ZnO-NPs to maintain its physical properties, enhance its antibacterial activity, and reduce the production of pro-inflammatory cytokines. ZnO-NPs were integrated into a commercial CSC (Endocem MTA) at 1 wt% (CSZ1) or 3 wt% (CSZ3). Setting time, compressive strength, and X-ray diffraction were then measured. In addition, pH, calcium ion release, and zinc ion release were measured for 7 days. Antibacterial activity against Enterococcus faecalis and viability of murine macrophages (RAW264.7) were determined using colorimetric assays. Gene expression levels of pro-inflammatory cytokines in lipopolysaccharide induced RAW264.7 were evaluated using quantitative polymerase chain reaction. Results were compared to an unmodified CSC group. In the CSZ3 group, there was a significant increase of approximately 12% in setting time and a reduction of about 36.4% in compressive strength compared to the control and CSZ1 groups. The presence of ZnO-NPs was detected in both CSZ1 and CSZ3. Both CSC and CSZ1 groups maintained an alkaline pH and released calcium ions, while zinc ions were significantly released in the CSZ1 group. Additionally, CSZ1 showed a 1.8-fold reduction of bacterial activity and exhibited around 85% reduction in colony-forming units compared to the CSC group. Furthermore, the CSZ1 group showed a more than 39% reduction in pro-inflammatory cytokine levels compared to the CSC group. Thus, enriching CSC with 1 wt% ZnO-NPs can enhance its antibacterial activity and reduce pro-inflammatory cytokines without showing any tangible adverse effects on its physical properties.

Dietary supplementation with pyrroloquinoline quinone promotes growth, relieves weaning stress, and regulates metabolism of piglets compared with adding zinc oxide

Hindered growth often occurs because of psychological and environmental stress during the weaning period of piglets. This study aimed to compare the effects of growth performance, diarrhea indices, digestibility of nutrients, antioxidant capacity, neurotransmitters levels and metabolism of weaned pigs fed diets supplemented with pyrroloquinoline quinone (PQQ) and zinc oxide (ZnO). Pigs weaned at d 28 (n = 108) were fed with three different diets including: the basal diet (CTRL group), the basal diet supplemented with 3.0 mg/kg PQQ (PQQ group) and the basal diet containing 1,600 mg/kg ZnO (ZNO group). During the first 14 d, weaned pigs fed the diet supplemented with PQQ and ZnO decreased feed to gain ratio and diarrhea rate (P < 0.01). Compared with the CTRL group, average daily gain was increased in weaned pigs in the PQQ group from d 15 to 28 (P = 0.03). Compared with the CTRL group, pigs fed PQQ and ZnO supplemented diets showed improved apparent total tract digestibility (ATTD) of nutrients (P ≤ 0.05). During the overall experimental period, the concentration of malondialdehyde was decreased in plasma of pigs in the PQQ and ZNO groups compared with the CTRL group (P < 0.05). At d 28, the concentration of vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) was lower in plasma of weaned pigs in the PQQ and ZNO groups compared with the CTRL group (P < 0.05). There was no difference between the PQQ and ZNO group in growth performance, ATTD of nutrition, antioxidant capacity and neurotransmitters levels. PQQ increased 3-methoxy-4-hydroxymandelate (P < 0.05) compared with the CTRL group. According to metabolomic analysis, erucamide, formononetin and 3-methyl-L-histidine were up-regulated in the PQQ group (P < 0.05). Compared with the CTRL group, aloesin and dibutyl adipate were down-regulated in the PQQ group (P < 0.05). In conclusion, similar to ZnO, PQQ improves growth performance, digestibility of nutrients, antioxidant capacity, neuromodulation and metabolism of weaned pigs. Thus, like ZnO, PQQ can be effectively applied in weaned pigs.

Zinc supplementation prior to heat shock enhances HSP70 synthesis through HSF1 phosphorylation at serine 326 in human peripheral mononuclear cells

Zinc supplementation prior to heat shock increases HSP70 (Heat shock protein 70) expression, which has cytoprotective effects in tissue cells during inflammation. Effects of zinc deficiency in this regard are...

Evidence-based traditional Siddha formulations for prophylaxis and management of respiratory symptoms in COVID-19 pandemic-a review

The recent outbreak of COVID-19 is attributed to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This viral disease is rapidly spreading across the globe, including India. The mainstay in managing the disease is supportive care, nutrition, and preventing further progression in the absence of proven antiviral drugs. Currently two vaccines Covishield and Covaxin are administered in India. Long-term plans of developing most reliable mRNA-based vaccines are also underway for the future method of prophylaxis. The Siddha system of medicine's holistic approach emphasizes lifestyle modification, prophylactic interventions, and dietary management to boost the host immunity and treatment with herbal medicines and higher-order medicines as the case may be. In this review, a brief outline of the disease COVID-19, Coronavirus, evidence-based traditional Siddha interventions for respiratory ailments and immune boosters highlighting the relevant published research on individual herbs are dealt, which pave way for further research on drug repurposing for COVID-19. Historical evidence on the prevention and treatment of infections especially antivirals in Siddha classics is studied.

A review on anti-inflammatory activity of green synthesized zinc oxide nanoparticle: Mechanism-based approach

Inflammation plays a very important role in the pathogenesis of various diseases like atherosclerosis, rheumatoid arthritis, asthma, and cancer. Lack of anti-inflammatory drugs and vectors provokes the need for developing new molecules for the management of inflammatory disorders. Nanotechnology has emerged as a wonderful research area in the past decade owing to its enhanced properties than bulk counterparts. This paper discusses the green synthesis of zinc oxide nanoparticle (ZnO NPs) and various characterization tools employed to comprehend the physiochemical properties of nanoparticles. ZnO NPs interaction with cells and its pharmacokinetic behavior inside the cells has also been discussed. The anti-inflammatory activity of ZnO NPs has been elucidated with the mechanism-based approach. A concise literature review has been included which summarizes the size, shape of ZnO NPs and the inflammatory model used for analyzing the anti-inflammatory activity of ZnO NPs. ZnO NPs potential offering towards anti-inflammatory activity like stable nature, selective targeting has been discussed briefly. The present study highlights the potential of ZnO NPs as an anti-inflammatory drug molecule or a vector for drug delivery.

Effects of dietary zinc source on the metabolic and immunological response to lipopolysaccharide in lactating Holstein dairy cows

The objectives of this study were to evaluate the effects of replacing 40 mg/kg of Zn from Zn sulfate (control; CON) with Zn AA complex (AvZn) on metabolism and immunological responses following an intravenous lipopolysaccharide (LPS) challenge in lactating cows. Cows were randomly assigned to 1 of 4 treatments: (1) pair-fed (PF) control (PF-CON; 5 mL of saline; n = 5), (2) PF AvZn (PF-AvZn; 5 mL of saline; n = 5), (3) LPS euglycemic clamp control (LPS-CON; 0.375 μg of LPS/kg of BW; n = 5), and (4) LPS euglycemic clamp AvZn (LPS-AvZn; 0.375 μg of LPS/kg of BW; n = 5). Cows were enrolled in 3 experimental periods (P). During period 1 (3 d), cows received their respective dietary treatments and baseline data were obtained. During period 2 (P2; 2 d), a 12-h LPS euglycemic clamp was conducted or cows were PF to their respective dietary counterparts. During period 3 (P3; 3 d), cows received their dietary treatment and consumed feed ad libitum. Mild hyperthermia (1°C) was observed in LPS cows at 3 h postbolus. Throughout P2, the rectal temperature of LPS-AvZn cows was decreased (0.3°C) relative to LPS-CON cows. Administrating LPS decreased dry matter intake (47%) during P2, and by experimental design the pattern was similar in PF cohorts. During P3, dry matter intake from LPS cows remained decreased (15%) relative to PF cows. Milk yield from LPS cows decreased (54%) during P2 relative to PF cows, but it was similar during P3. During P2, somatic cell count increased 3-fold in LPS cows relative to PF controls. Dietary AvZn tended to decrease somatic cell count (70%) during P3 relative to LPS-CON cows. Insulin increased 7-fold in LPS cows at 12 h postbolus and remained increased (4-fold) for the duration of P2. Circulating glucagon from LPS cows increased (65%) during P2, and supplementing AvZn blunted the increase (30% relative to LPS-CON). During P2, circulating cortisol increased 7-fold post-LPS infusion relative to PF cows, and supplementing AvZn decreased cortisol (58%) from 6 to 48 h postbolus relative to LPS-CON cows. Administrating LPS increased circulating LPS-binding protein and serum amyloid A (3- and 9-fold, respectively) relative to PF cows. Compared with LPS-CON, LPS-AvZn cows had increased circulating serum amyloid A (38%) 24 h postbolus. The 12-h total glucose deficit was 36 and 1,606 g for the PF and LPS treatments, respectively, but was not influenced by Zn source. In summary, replacing a portion of the Zn sulfate with Zn AA complex appeared to reduce the inflammatory response but had no effect on the glucose deficit.

Oxidative Stress: A Unifying Mechanism for Cell Damage Induced by Noise, (Water-Pipe) Smoking, and Emotional Stress-Therapeutic Strategies Targeting Redox Imbalance

SIGNIFICANCE

Modern technologies have eased our lives but these conveniences can impact our lifestyles in destructive ways. Noise pollution, mental stresses, and smoking (as a stress-relieving solution) are some environmental hazards that affect our well-being and healthcare budgets. Scrutinizing their pathophysiology could lead to solutions to reduce their harmful effects. Recent Advances: Oxidative stress plays an important role in initiating local and systemic inflammation after noise pollution, mental stress, and smoking. Lipid peroxidation and release of lysolipid by-products, disturbance in activation and function of nuclear factor erythroid 2-related factor 2 (Nrf2), induction of stress hormones and their secondary effects on intracellular kinases, and dysregulation of intracellular Ca²⁺ can all potentially trigger other vicious cycles. Recent clinical data suggest that boosting the antioxidant system through nonpharmacological measures, for example, lifestyle changes that include exercise have benefits that cannot easily be achieved with pharmacological interventions alone.

CRITICAL ISSUES

Indiscriminate manipulation of the cellular redox network could lead to a new series of ailments. An ideal approach requires meticulous scrutiny of redox balance mechanisms for individual pathologies so as to create new treatment strategies that target key pathways while minimizing side effects.

FUTURE DIRECTIONS

Extrapolating our understanding of redox balance to other debilitating conditions such as diabetes and the metabolic syndrome could potentially lead to devising a unifying therapeutic strategy. Antioxid. Redox Signal. 28, 741-759.

Implications of impaired zinc homeostasis in diabetic cardiomyopathy and nephropathy

Impaired zinc homeostasis is observed in diabetes mellitus (DM2) and its complications. Zinc has a specific role in pancreatic β-cells via insulin synthesis, storage, and secretion. Intracellular zinc homeostasis is tightly controlled by zinc transporters (ZnT and Zip families) and metallothioneins (MT) which modulate the uptake, storage, and distribution of zinc. Several investigations in animal models demonstrate the protective role of MT in DM2 and its cardiovascular or renal complications, while a copious literature shows that a common polymorphism (R325W) in ZnT8, which affects the protein's zinc transport activity, is associated with increased DM2 risk. Emerging studies highlight a role of other zinc transporters in β-cell function, suggesting that targeting them could make a possible contribution in managing the hyperglycemia in diabetic patients. This article summarizes the current findings concerning the role of zinc homeostasis in DM2 pathogenesis and development of diabetic cardiomyopathy and nephropathy and suggests novel therapeutic targets. © 2017 BioFactors, 43(6):770-784, 2017.

Cytokine synthesis in the liver of endotoxin-tolerant and normal rats during hemorrhagic shock

In the present study the effects of endotoxin tolerance on hemorrhagic shock were investigated with particular focus on hepatic alterations. The following questions were addressed: (i) does hemorrhagic shock induce cytokine formation and heat shock response in the liver; and (ii) does endotoxin tolerance alter these reactions. Endotoxin tolerance was induced by repetitive daily injections of LPS for 5 days. Hemorrhagic shock was induced by hypovolemia (MAP 35 ± 5 mmHg). After 3 h, the animals were resuscitated by re-infusion of homologous blood. m-RNA was isolated from liver biopsies and the mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10) and heat shock protein 70 (HSP-70) were determined by RT-PCR. TNF-α was measured by ELISA in serum samples and in the supernatants of whole blood cultures. It was found that endotoxin tolerance reduced mortality caused by hemorrhagic shock from 80% to 20%. In parallel, TNF-α production in response to LPS in vivo and in vitro was significantly decreased. During hemorrhage and after resuscitation. increased mRNA levels were detected in hepatic biopsies for TNF-α, IL-6, IL-10 and HSP-70, with highest levels immediately after re-infusion. Endotoxin-tolerant rats produced significantly lower levels of TNF-α, while no differences were found for IL-10 and HSP-70. Within 30 min after reperfusion, significantly higher levels of IL-6 mRNA were found in hepatic biopsies from tolerant rats; these differences disappeared 2 h after reperfusion.

Zinc oxide influences intestinal integrity, the expressions of genes associated with inflammation and TLR4-myeloid differentiation factor 88 signaling pathways in weanling pigs

This study explored whether zinc oxide (ZnO) supplementation could alleviate weanling-induced intestinal injury through TLR and NOD-like receptor signaling pathways. Twelve early-weanling piglets were allotted to two dietary treatments (control vs 2200 mg Zn/kg from ZnO) for 1 wk. The results showed that supplemental ZnO improved daily gain and feed intake, decreased post weaning scour scores, increased villus height and villus height:crypt depth ratio at the jejunal mucosa, and decreased diamine oxidase activity and endotoxin concentration in plasma. The intestinal mRNA levels of TLR4 and its downstream signals, including MyD88, IL-1 receptor-associated kinase 1 and TNF-α receptor-associated factor 6, were decreased, and the expressions of intestinal pro-inflammatory cytokines and chemokines were decreased simultaneously in the ZnO-supplemented piglets. Although NF-κB p65 mRNA abundance was not affected by ZnO supplementation, NF-κB p65 protein expression was down-regulated by ZnO. However, ZnO supplementation had no effect on intestinal expressions of NOD1 and NOD2, and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2, as well as protein expressions of caspase-3 and heat shock protein 70. The results indicated that the protective effects of ZnO on intestinal integrity were closely related to decreasing the expressions of genes associated with inflammation through inhibiting the TLR4-MyD88 signaling pathways.

Antioxidant and anti-inflammatory effects of exercise in diabetic patients

Diabetes is a chronic metabolic disease which is characterized by absolute or relative deficiencies in insulin secretion and/or insulin action. The key roles of oxidative stress and inflammation in the progression of vascular complications of this disease are well recognized. Accumulating epidemiologic evidence confirms that physical inactivity is an independent risk factor for insulin resistance and type II diabetes. This paper briefly reviews the pathophysiological pathways associated with oxidative stress and inflammation in diabetes mellitus and then discusses the impact of exercise on these systems. In this regard, we discuss exercise induced activation of cellular antioxidant systems through “nuclear factor erythroid 2-related factor.” We also discuss anti-inflammatory myokines, which are produced and released by contracting muscle fibers. Antiapoptotic, anti-inflammatory and chaperon effects of exercise-induced heat shock proteins are also reviewed.

Inflammatory response of porcine epithelial IPEC J2 cells to enterotoxigenic E. coli infection is modulated by zinc supplementation

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhoea in pigs and humans. The duration and severity of diarrhoea can be controlled using zinc supplementation, typically pharmacological levels of zinc oxide in pigs. In this study, IPEC J2 cells were used as an in vitro model of intestinal ETEC infection, with separate and simultaneous zinc treatment. Genomic analysis identified increased expression of a variety of innate immune response genes (NF-κB targets) in response to ETEC exposure, and several stress response genes in response to zinc exposure, provided as ZnO. Expression of genes involved in the innate immune response was reduced when cells were simultaneously exposed to ZnO, and it is suggested that ZnO treatment inhibits the induction of NF-κB in response to pathogens, possibly through up-regulated heat shock proteins. A similar response in vivo with consequent down-regulation in the inflammatory response would reduce further pathogen invasion, maintain normal gut function and maintain growth.

Pro-inflammatory genetic background and zinc status in old atherosclerotic subjects

Inflammation and genetics are prominent mechanisms in the pathogenesis of atherosclerosis (AT) and its complications. In this review we discuss the possible impact on AT development of several genetic determinants involved in inflammation, oxidative stress and cytoprotection (IL-6, TNF-alpha, IL-10, CD14, TLR4, MT, HSP70). Genetic polymorphisms of these genes may affect a differential inflammatory response predisposing to AT. However, allelic polymorphisms of genes which increase the risk of AT frequently occur in the general population but, only adequate gene-environment-polymorphism interactions promote the onset of the disease. Zinc deficiency has been suggested as an environmental risk factor for AT. With advancing age, the incidence of zinc deficiency increases for several reasons. Among them, dietary intake, malabsorption and genetic background of inflammatory markers may be involved. A crucial contribution may also be played by increased oxidative stress which may lead to the appearance of dysfunctional proteins, including metallothioneins (MT) that are in turn involved in zinc homeostasis. The detection of candidate genes related to inflammation and promoting AT and their reciprocal influence/interaction with zinc status might allow earlier appropriate dietary interventions in genetically susceptible subjects.

Anti-inflammatory effects of the 70 kDa heat shock protein in experimental stroke

The 70-kDa heat shock protein (Hsp70) is involved in protecting the brain from a variety of insults including stroke. Although the mechanism has been largely considered to be because of its chaperone functions, recent work indicates that Hsp70 also modulates inflammatory responses. To explore how and whether Hsp70 regulate immune responses in brain ischemia, mice overexpressing Hsp70 (Hsp Tg) were subjected to 2 h middle cerebral artery occlusion, followed by 24 h reperfusion. Parallel experiments were performed using a brain inflammation model. Hsp Tg microglia cocultured with astrocytes were used to evaluate the direct effects of Hsp70 on cytotoxicity of microglia. Compared with wild-type (Wt) littermates, Hsp Tg mice showed decreased infarct size and improved neurological deficits. The number of activated microglia/macrophages were also reduced in ischemic brains of Hsp Tg mice. Similar observations were made in a model of brain inflammation that does not result in brain cell death. Overexpression of Hsp70 in microglia completely prevented microglia-induced cytotoxicity to astrocytes. Activation of the inflammatory transcription factor, nuclear factor-kappaB (NF-kappaB) was inhibited significantly in Hsp Tg mice and microglia. This was associated with decreased phosphorylation of NF-kappaB inhibitor protein, IkappaBalpha, and decreased expression of several NFkappaB-regulated genes. Co-immunoprecipitation studies revealed an interaction of Hsp70 with NF-kappaB and IkappaBalpha, but not with IkappaB kinase, IKKgamma, suggesting that Hsp70 binds to the NF-kappaB:IkappaB complex preventing IkappaB phosphorylation by IKK. The findings of the present work establish an anti-inflammatory role for Hsp70 in the context of brain ischemia as a novel mechanism of protection.

Zinc-dependent suppression of TNF-alpha production is mediated by protein kinase A-induced inhibition of Raf-1, I kappa B kinase beta, and NF-kappa B

Excessive and permanent cytokine production in response to bacterial LPS causes cell and tissue damage, and hence organ failure during sepsis. We have previously demonstrated that zinc treatment prevents LPS-induced TNF-alpha expression and production in human monocytes by inhibiting cyclic nucleotide phosphodiesterase (PDE) activity and expression, and subsequent elevation of the cyclic nucleotide cGMP. In the present study, we investigated the molecular mechanism by which cGMP signaling affects the LPS-induced signaling cascade to suppress TNF-alpha transcription and release from monocytes. Zinc-mediated cGMP elevation led to cross activation of protein kinase A. This zinc-induced protein kinase A activation inhibited Raf-1 activity by phosphorylation at serine 259, preventing activation of Raf-1 by phosphorylation of serine 338. By this mechanism, zinc suppressed LPS-induced activation of IkappaB kinase beta (IKKbeta) and NF-kappaB, and subsequent TNF-alpha production. Our study shows that PDE inhibition by zinc modulates the monocytic immune response by selectively intervening in the Raf-1/IKKbeta/NF-kappaB pathway, which may constitute a common mechanism for the anti-inflammatory action of PDE inhibitors.

Protection of Zinc against Tumor Necrosis Factor–Induced Lethal Inflammation Depends on Heat Shock Protein 70 and Allows Safe Antitumor Therapy

Tumor necrosis factor (TNF)-induced inflammation prevents its broad application as an antitumor agent. We here report that addition of ZnSO(4) to the drinking water of mice induces expression of heat shock protein 70 (HSP70) in several organs, notably the gastrointestinal track. Zinc conferred dose-responsive protection against TNF-induced hypothermia, systemic induction of interleukin-6 and NO(x), as well as against TNF-induced bowel cell death and death of the organism. The protective effect of zinc was completely absent in mice deficient in the major HSP70-inducible gene, hsp70.1, whereas transgenic mice constitutively expressing the human HSP70.A gene, under control of a beta-actin promoter, was also protected against TNF, indicating that an increase in HSP70 is necessary and sufficient to confer protection. The therapeutic potential of the protection induced by ZnSO(4) was clearly shown in a TNF/IFNgamma-based antitumor therapy using three different tumor models. In hsp70.1 wild-type mice, but not in hsp70.1-deficient mice, zinc very significantly protected against lethality but left the antitumor effect intact. We conclude that zinc protects against TNF in a HSP70-dependent way and that protection by zinc could be helpful in developing a safer anticancer therapy with TNF/IFNgamma.

Macro- and micronutrients in African-Americans with heart failure

An emerging body of evidence suggests secondary hyperparathyroidism (SHPT) may be an important covariant of congestive heart failure (CHF), especially in African-Americans (AA) where hypovitaminosis D is prevalent given that melanin, a natural sunscreen, mandates prolonged exposure of skin to sunlight and where a housebound lifestyle imposed by symptomatic CHF limits outdoor activities and hence sunlight exposure. In addition to the role of hypovitaminosis D in contributing to SHPT is the increased urinary and fecal losses of macronutrients Ca(2+) and Mg(2+) associated with the aldosteronism of CHF and their heightened urinary losses with furosemide treatment of CHF. Thus, a precarious Ca(2+) balance seen with reduced serum 25(OH)D is further compromised when AA develop CHF with circulating RAAS activation and are then treated with a loop diuretic. SHPT accounts for a paradoxical Ca(2+) overloading of diverse tissues and the induction of oxidative stress at these sites which spills over to the systemic circulation. In addition to SHPT, hypozincemia and hyposelenemia have been found in AA with compensated and decompensated heart failure and where an insufficiency of these micronutrients may have its origins in inadequate dietary intake, altered rates of absorption or excretion and/or tissue redistribution, and treatment with an ACE inhibitor or AT(1) receptor antagonist. Zn and Se deficiencies, which compromise the activity of several endogenous antioxidant defenses, could prove contributory to the severity of heart failure and its progressive nature. These findings call into question the need for nutriceutical treatment of heart failure and which is complementary to today's pharmaceuticals, especially in AA.

Zinc-mediated inhibition of cyclic nucleotide phosphodiesterase activity and expression suppresses TNF-alpha and IL-1 beta production in monocytes by elevation of guanosine 3',5'-cyclic monophosphate

The trace element zinc affects several aspects of immune function, such as the release of proinflammatory cytokines from monocytes. We investigated the role of cyclic nucleotide signaling in zinc inhibition of LPS-induced TNF-alpha and IL-1beta release from primary human monocytes and the monocytic cell line Mono Mac1. Zinc reversibly inhibited enzyme activity of phosphodiesterase-1 (PDE-1), PDE-3, and PDE-4 in cellular lysate. It additionally reduced mRNA expression of PDE-1C, PDE-4A, and PDE-4B in intact cells. Although these PDE can also hydrolyze cAMP, only the cellular level of cGMP was increased after incubation with zinc, whereas cAMP was found to be even slightly reduced due to inhibition of its synthesis. To investigate whether an increase in cGMP alone is sufficient to inhibit cytokine release, the cGMP analogues 8-bromo-cGMP and dibutyryl cGMP as well as the NO donor S-nitrosocysteine were used. All three treatments inhibited TNF-alpha and IL-1beta release after stimulation with LPS. Inhibition of soluble guanylate cyclase-mediated cGMP synthesis with LY83583 reversed the inhibitory effect of zinc on LPS-induced cytokine release. In conclusion, inhibition of PDE by zinc abrogates the LPS-induced release of TNF-alpha and IL-1beta by increasing intracellular cGMP levels.

Missing effects of zinc in a porcine model of recurrent endotoxemia

Background

Chronic human sepsis often is characterised by the compensatory anti-inflammatory response syndrome (CARS). During CARS, anti-inflammatory cytokines depress the inflammatory response leading to secondary and opportunistic infections. Proved in vitro as well as in vivo, zinc's pro-inflammatory effect might overcome this depression.

Methods

We used the model of porcine LPS-induced endotoxemia established by Klosterhalfen et al. 10 pigs were divided into two groups (n = 5). Endotoxemia was induced by recurrent intravenous LPS-application (1.0 μg/kg E. coli WO 111:B4) at hours 0, 5, and 12. At hour 10, each group received an intravenous treatment (group I = saline, group II = 5.0 mg/kg elementary zinc). Monitoring included hemodynamics, blood gas analysis, and the thermal dilution technique for the measurement of extravascular lung water and intrapulmonary shunt. Plasma concentrations of IL-6 and TNF-alpha were measured by ELISA. Morphology included weight of the lungs, width of the alveolar septae, and rate of paracentral liver necrosis.

Results

Zinc's application only trended to partly improve the pulmonary function. Compared to saline, significant differences were very rare. IL-6 and TNF-alpha were predominately measured higher in the zinc group. Again, significance was only reached sporadically. Hemodynamics and morphology revealed no significant differences at all.

Conclusion

The application of zinc in this model of recurrent endotoxemia is feasible and without harmful effects. However, a protection or restoration of clinical relevance is not evident in our setting. The pulmonary function just trends to improve, cytokine liberation is only partly activated, hemodynamics and morphology were not influenced. Further pre-clinical studies have to define zinc's role as a therapeutic tool during CARS.

Deleterious effect of zinc in a pig model of acute endotoxemia

By antiapoptotic effects and the induction of the heat-shock response, zinc is supposed to be a promising means of therapy during sepsis. As zinc also stimulates the expression of proinflammatory cytokines, its administration during the proinflammatory stage of septic shock might have adverse effects. Therefore, this study analyzes the influence of zinc during the acute phase of endotoxemia. In a pig model of acute endotoxemia, animals were divided into two groups: group I (n = 5) with saline treatment and group II (n = 5) with zinc treatment in close succession to lipopolysaccharide (LPS) (1.0 mu g/kg Escherichia coli endotoxin WO 111:B4). Hemodynamic and pulmonary monitoring was followed by combined reflection photometry, pulse oxymetry, blood gas samples, and temperature measurement. Plasma concentrations of tumor necrosis factor (TNF)alpha and interleukin (IL)-6 were analyzed by enzyme-linked immunosorbent assay (ELISA). Morphology included the weight of the lungs, the width of the alveolar septae, and the paracentral necrosis rate of the liver. After LPS infusion, group II (zinc) showed an impressive and significant deterioration of all pulmonary and most of the hemodynamical parameters compared to group I (saline). Levels of TNFalpha and IL-6 measured were significantly higher after zinc treatment. In accordance, we found significant more morphologic damages in group II (zinc). The almost simultaneous infusion of zinc and LPS complementary induced proinflammatory effects with a deleterious outcome. The same potentials characterizing zinc as a promising tool of prophylactic therapy in sepsis seem to ban its use during the acute phase.

Effect of zinc pretreatment on pulmonary endothelial cells in vitro and pulmonary function in a porcine model of endotoxemia

BACKGROUND

During endotoxemia, the systemic inflammatory response often leads to severe pulmonary damages. Destruction of endothelial cells, interstitial edema, and interstitial alveolitis depress pulmonary circulation and raise extravascular lung water and intrapulmonary shunt. As protective effects of zinc are described in vitro as well as in vivo, this study investigates its impact on septic porcine pulmonary endothelial monolayers as well as on the pulmonary function of endotoxemic pigs.

MATERIALS AND METHODS

Cell culture: Endothelial cells were incubated with ascending doses of zinc and pooled with septic plasma. Cellular damage, metabolism, and proliferation were measured by vital stain, XTT-assay, and BrDU-ELISA. HSP70 was visualized by immunohistochemistry. Animal study: We used an established porcine model. Twenty-four hours before endotoxemia (intravenous infusion of 1.0 microg/kg Escherichia coli endotoxin WO111:B4), each animal received an intravenous pretreatment. Group I (n = 3): saline pretreatment, group II (n = 5): zinc pretreatment (5 mg/kg elementary zinc). Monitoring included blood gas analysis and the thermal dye dilution technique.

RESULTS

In vitro, zinc leads to significantly altered rates of viable cells, metabolism, and proliferation with the strongest cell-protective effect at moderate concentrations of 1 microg/ml Zn2+. This correlates with a qualitatively increased expression of HSP70. In vivo, the zinc pretreatment before LPS-induced endotoxemia grossly improves all measured hemodynamic and pulmonary parameters.

CONCLUSION

Zinc pretreatment of endotoxemia decreases cellular damages in vitro and improved pulmonary function in vivo. This could be mediated by the heat shock response. Further studies, particularly concerning the dose-effect relationship and the underlying mode of action, are mandatory.

Role of Zn(2+) in oxidative stress caused by endotoxin challenge

The role of Zn(2+) in oxidative stress during endotoxemia was investigated. In rats fed a Zn(2+)-deficient diet (Zn(2+) concentration of less than 1.5 mg/kg) for 8 weeks, the Zn(2+) level in the serum was about 62% lower than that in rats fed a Zn(2+)-adequate diet (Zn(2+) concentration, 50 mg/kg). The Zn(2+) level in serum 18 h after administration of endotoxin (6 mg/kg, i.p.) to Zn(2+)-deficient diet rats was markedly lower than that of the endotoxin/Zn(2+)-adequate diet group. Lipid peroxide formation in the liver of Zn(2+)-deficient diet rats was markedly increased 18 h after endotoxin injection compared with that in the endotoxin/Zn(2+)-adequate diet group. Metallothionein in the liver of endotoxin/Zn(2+)-adequate diet rats was increased more than 17-fold by endotoxin administration, while a markedly lower level of metallothionein was observed in the endotoxin/Zn(2+)-deficient diet group. On the other hand, treatment with ZnSO(4) (100 microM) significantly increased endotoxin (1 microg/ml)-induced tumor necrosis factor-alpha (TNF-alpha) production in J774A.1 cells. Our results clearly demonstrated that treatment with ZnSO(4) significantly inhibited the endotoxin-induced increase in intracellular Ca(2+) level in J774A.1 cells. However, a cell membrane-permeable Zn(2+) chelator, N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN, 1 microM), did not affect the endotoxin-induced TNF-alpha production or Ca(2+) level in J774A.1 cells. In addition, we investigated whether Zn(2+) can suppress nitric oxide (NO) generation and cytotoxicity in endotoxin-treated cells. Treatment with ZnSO(4) (50 microM) significantly inhibited endotoxin-induced NO production in J774A.1 cells, but did not affect endotoxin-induced cytotoxicity. These findings suggest that zinc may play an important role, at least in part, in the oxidative stress during endotoxemia.

Long-term recombinant porcine somatotropin (PST) treatment mitigates the responses to subchronic lipopolysaccharide in swine

The effect of multiple lipopolysaccharide (LPS) challenges in swine undergoing long-term treatment with porcine somatotropin (PST) was determined. Changes in aspartate serine transaminase (AST) occurred only at 24h following the first LPS challenge dose (P<0.05), while PST treatment moderated any change from occurring. Nonesterified free fatty acid (NEFA) levels were elevated in PST treated animals for the first 3 days following daily LPS treatment (P<0.05), while LPS treatment alone had no effect on plasma NEFA levels. Plasma urea nitrogen (PUN) levels were unchanged by LPS following the initial LPS challenge, but were decreased following the second challenge dose (P=0.014). These changes were long lasting, with a return to normal PUN levels not evident until Day 6. The PST treatment mitigated changes in PUN (P<0.05) when LPS was administered. Haptoglobin plasma levels, along with lipid peroxide production were not affected by LPS challenge or PST administration. LPS challenge reduced the levels of immunoreactive heat shock protein 70 (HSP70) throughout the entire challenge period (P<0.001). PST-LPS animals had normal levels of this protein. The results of the present study demonstrate that long-term PST treatment mitigates the adverse effects of subchronic LPS administration.

Molecular chaperones in the kidney

The normal milieu of the kidney includes hypoxia, large osmotic fluxes, and an enormous amount of fluid/solute reabsorption. Renal adaptation to these conditions requires a host of molecular chaperones that stabilize protein conformation, target nascent proteins to their final intracellular destination, and prevent protein aggregation. Under physiologic or pharmacologic stress, inducible molecular chaperones provide additional mechanisms for repairing or degrading non-native proteins and for inhibiting stress-induced apoptosis. In contrast to intracellular chaperones, chaperones present on the cell surface regulate the immune system and have cytokine-like effects. A diverse range of chaperones and chaperone functions provide the renal cell with an armamentarium of responses to improve the chances of survival.

A mediator role for metallothionein in tumor necrosis factor-induced lethal shock

Tumor necrosis factor (TNF) is a proinflammatory cytokine, which is centrally involved in several inflammatory disorders. Administration of TNF leads to a potentially lethal systemic inflammatory response syndrome (SIRS). We observed that (a) mice lacking functional genes for metallothionein 1 and 2 (MT-null) were protected compared with wild-type controls (P = 0.0078), and (b) mice overexpressing MT-1 (MT-TG) were more sensitized for the lethal effect of TNF than control mice (P = 0.0003), indicating a mediating role for MT in TNF induced SIRS. As MT is involved in the body zinc homeostasis, we tested whether zinc-deprivation or -supplementation alters the response to TNF. Although zinc-depletion strongly sensitized (P = 0.036), and pretreatment with zinc sulfate (ZnSO4) conferred protection against the deleterious effects of TNF (P < 0.0002), it was also found that the protection provided by zinc is independent of MT. Our observation that hsp70 is strongly induced in jejunum after ZnSO4 treatment, suggests a contribution of hsp70 in the protection against TNF. In addition, ZnSO4 cotreatment allowed complete regression of inoculated tumors with TNF and interferon gamma, leading to a significantly better survival (P = 0.0045).

Effects of zinc acetate on splenocytes of endotoxemic mice: enhanced immune response, reduced apoptosis, and increased expression of heat shock protein 70

Immune function is markedly attenuated in endotoxemia. Zinc is involved in the regulation of cellular functions and maintenance of immune function, and its level in the serum is low in endotoxemia. We mainly investigated the effects of zinc acetate (ZA) on splenocytes in mice with endotoxemia. After we confirmed increased plasma zinc level by ZA treatment, C57BL/6 mice were randomly divided into four groups: 10 control mice received 500 microL saline solution as vehicle; 10 control mice received ZA at 3 mg/kg body weight; 20 endotoxemic mice received a 40 mg/kg lethal dose of lipopolysaccharide (LPS); 20 mice received ZA followed by LPS as the above dose. In vivo, we confirmed that ZA pretreatment did not significantly affect the plasma cytokine level in endotoxemic mice. In vitro, splenocytes from ZA-plus-LPS mice showed drastic effects, in that ZA abrogated LPS-induced suppression of cellular proliferation and production of interleukin-2 and interferon-gamma. The percentage of apoptotic splenocytes was significantly reduced in ZA-plus-LPS mice (23.4%) as compared with LPS mice (41.6%). Furthermore, the expression of HSP-70 mRNA in splenocytes was strongly enhanced in both ZA and ZA-plus-LPS mice, especially in the latter group. Finally, studies monitoring survival rates for 6 days showed that LPS caused 100% mortality while ZA-plus-LPS mice showed 75% survival. Our results suggest that zinc normalized the immune response and reduced apoptosis of splenocytes. These changes were probably caused by increased synthesis of HSP-70 by splenocytes, which might enhance survival of mice with LPS-induced endotoxemia.

Zinc and the immune system

Zn is an essential trace element for all organisms. In human subjects body growth and development is strictly dependent on Zn. The nervous, reproductive and immune systems are particularly influenced by Zn deficiency, as well as by increased levels of Zn. The relationship between Zn and the immune system is complex, since there are four different types of influence associated with Zn. (1) The dietary intake and the resorption of Zn depends on the composition of the diet and also on age and disease status. (2) Zn is a cofactor in more than 300 enzymes influencing various organ functions having a secondary effect on the immune system. (3) Direct effects of Zn on the production, maturation and function of leucocytes. (4) Zn influences the function of immunostimulants used in the experimental systems. Here we summarize all four types of influence on the immune function. Nutritional aspects of Zn, the physiology of Zn, the influence of Zn on enzymes and cellular functions, direct effects of Zn on leucocytes at the cellular and molecular level, Zn-altered function of immunostimulants and the therapeutic use of Zn will be discussed in detail.

Septic shock

1. Septic shock is still a major complication of patients in intensive care units (ICUs) and, therefore, a main goal of ICU-related research. 2. After the unsatisfying results of multicenter clinical trials in blocking proinflammatory mediators such as tumor necrosis factor and interleukin-1 or endotoxin itself, research has focused on other important members of the cytokine pathways--in particular, anti-inflammatory cytokines such as interleukin 10. Moreover, there is an increasing knowledge of intracellular activation and deactivation pathways, inaugurating the theoretical advantage to block, attenuate or manipulate the inflammatory response at an early stage of disease or in a more specific fashion. 3. This review points out new developments in our understanding of the pathophysiology of septic shock and gives an example of a more recent approach in septic shock research--the heat shock response.

Interleukin-6 production in human intestinal epithelial cells increases in association with the heat shock response

BACKGROUND

In recent studies, IL-1beta stimulated the production of IL-6 in human enterocytes. The heat shock response influences the production of inflammatory mediators in certain cell types. We tested the hypothesis that heat shock regulates IL-1beta-induced IL-6 production in human intestinal epithelial cells.

MATERIALS AND METHODS

Cultured Caco-2 cells, a human intestinal epithelial cell line, were exposed to thermal heat shock at 43 degreesC for 1 h and recovered at 37 degreesC for 1 h. Cells were harvested for analysis of heat shock protein-70 (HSP-70) production by Western blotting. In other experiments, IL-1beta (0.5 ng/ml) was added following heat shock and recovery. IL-6 protein was measured in culture medium after 24 h by enzyme-linked immunosorbent assay and IL-6 messenger RNA (mRNA) levels were measured after 4 h by competitive reverse transcriptase polymerase chain reaction.

RESULTS

Heat shock resulted in the production of HSP-70 and potentiated IL-1beta-induced IL-6 production. The response to heat shock was associated with increased IL-6 mRNA levels.

CONCLUSIONS

The results suggest that IL-1beta-induced IL-6 production in human enterocytes is increased in association with the heat shock response. The biological role of heat shock-potentiated IL-6 production in the enterocyte remains to be determined.