Ferroptosis: A Double-Edged Sword in Gastrointestinal Disease.

Ferroptosis is a novel form of regulated cell death (RCD) that is typically accompanied by iron accumulation and lipid peroxidation. In contrast to apoptosis, autophagy, and necroptosis, ferroptosis has unique biological processes and pathophysiological characteristics. Since it was first proposed in 2012, ferroptosis has attracted attention worldwide. Ferroptosis is involved in the progression of multiple diseases and could be a novel therapeutic target in the future. Recently, tremendous progress has been made regarding ferroptosis and gastrointestinal diseases, including intestinal ischemia/reperfusion (I/R) injury, inflammatory bowel disease (IBD), gastric cancer (GC), and colorectal cancer (CRC). In this review, we summarize the recent progress on ferroptosis and its interaction with gastrointestinal diseases. Understanding the role of ferroptosis in gastrointestinal disease pathogenesis could provide novel therapeutic targets for clinical treatment.

l-Homocarnosine attenuates inflammation in cerebral ischemia-reperfusion injury through inhibition of nod-like receptor protein 3 inflammasome.

We investigated the therapeutic effects of l-homocarnosine against inflammation in a rat model of cerebral ischemia-reperfusion injury. Rats were grouped into control, middle cerebral artery occlusion (MCAO), 0.5 mM l-homocarnosine + MCAO, and 1 mM l-homocarnosine + MCAO treatment groups. Superoxide dismutase (SOD), glutathione peroxidase (Gpx), catalase, lipid peroxidation, and reduced glutathione (GSH) levels were measured. Neurological scores were assessed, and histopathology, scanning electron microscopy (SEM), and fluorescence microscopy analyses were conducted. The mRNA expression levels of nod-like receptor protein 3 (NLRP3), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) and protein expression levels of NLRP3 were assessed. l-Homocarnosine supplementation substantially increased SOD, catalase, Gpx, and GSH levels, whereas it reduced the levels of lipid peroxidation relative to MCAO rats. l-Homocarnosine significantly reduced the infarct area and neurological deficit score, as well as histopathological alteration, apoptosis, and necrosis in brain tissue. The mRNA expression levels of NLRP3, TNF-α, and IL-6 were increased in MCAO rats, whereas l-homocarnosine supplementation reduced mRNA expression by >40%, and NLRP3 protein expression was reduced by >30% in 1 mM l-homocarnosine-treated MCAO rats. We propose that l-homocarnosine exerts a protective effect in cerebral ischemia-reperfusion injury-induced rats by downregulating NLRP3 expression.

Protective effects of persian honey, Apis Mellifera Meda Skorikov on side effects of chemotherapy and ischemia/reperfusion induced testicular injury.

Introduction The aim of the present study was to survey the protective effect of pretreatment with Persian honey on amelioration of side effects of chemotherapy and ischemia/reperfusion induced testicular injury. Materials and methods Forty adult's male wistar rats were divided into four groups of ischemia-reperfusion (IR), honey + ischemia-reperfusion (HIR), Busulfan (B) and Busulfan intraperitoneally+ honey (BH). The seminiferous tubules were rated for their modified spermatogenesis index (SI) by Johnsons score. Detection of single- and double-stranded DNA breaks at the early stages of apoptosis was performed using the in-situ cell death detection kit. Total serum concentration of Follicle-stimulating hormone (FSH) , Luteinizing hormone (LH) and testosterone was measured using ELISA. All data were expressed as mean ± SD and significance was set at p≤0.05. Results Honey improved SI in the HIR and BH groups and serum levels of FSH and LH in the BH and HIR groups (p<0.001). Also, serum levels of testosterone were significantly higher in BH and HIR groups. But, apoptotic cells in IR and B groups significantly increased (p<0.001), while in HIR and BH groups, the number of apoptotic cells decreased and the positive cells of TUNEL (TdT-mediated dUTP-X nick end labelling) staining were detected in spermatocytes and spermatid. Discussion Pretreatment with honey protect testis against chemotherapy and testicular IR injury, increase FSH and LH and testosterone and decrease the cellular damage and apoptosis. Honey can decrease the side effects of chemotherapy on reproductive system and prevent sterility.

Selenium Pretreatment for Mitigation of Ischemia/Reperfusion Injury in Cardiovascular Surgery: Influence on Acute Organ Damage and Inflammatory Response.

Ischemia/reperfusion injury (IRI) contributes to morbidity and mortality after cardiovascular surgery requiring cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA). Multi-organ damage is associated with substantial decreases of blood selenium (Se) levels in patients undergoing cardiac surgery with CPB. We compared the influence of a dietary surplus of Se and pretreatment with ebselen, a mimic of the selenoenzyme glutathione peroxidase, on IRI-induced tissue damage and inflammation. Male Wistar rats were fed either a Se-adequate diet containing 0.3 ppm Se or supplemented with 1 ppm Se (as sodium selenite) for 5 weeks. Two other groups of Se-adequate rats received intraperitoneal injection of ebselen (30 mg/kg) or DMSO (solvent control) before surgery. The animals were connected to a heart-lung-machine and underwent 45 min of global ischemia during circulatory arrest at 16 °C, followed by re-warming and reperfusion. Selenite and ebselen suppressed IRI-induced leukocytosis and the increase in plasma levels of tissue damage markers (AST, ALT, LDH, troponin) during surgery but did not prevent the induction of proinflammatory cytokines (IL-6, TNF-α). Both Se compounds affected phosphorylation and expression of proteins related to stress response and inflammation: Ebselen increased phosphorylation of STAT3 transcription factor in the heart and decreased phosphorylation of ERK1/2 MAP kinases in the lungs. Selenite decreased ERK1/2 phosphorylation and HSP-70 expression in the heart. Pretreatment with selenite or ebselen protected against acute IRI-induced tissue damage during CPB and DHCA. Potential implications of their different actions with regard to molecular stress markers on the recovery after surgery represent promising targets for further investigation.

Effects of kefir on ischemia-reperfusion injury.

OBJECTIVE: We aimed to investigate the effect of kefir on Ischemia-Reperfusion (I/R) injury on rats. MATERIALS AND METHODS: 24 male Sprague-Dawley rats between 250-350 g were selected. Rats were divided into three groups, and there were eight rats in each group. Rats were fed for 60 days. All of the rats were fed with the same diet for the first 30 days. In the second thirty days, kefir [10 cc/kg/day body weight (2 x 109 cfu/kg/day)] was added to the diet of the study group by gavage method. In all groups, lung and kidney tissues were removed after the procedure and rats were sacrificed. The biochemical and histopathological changes were observed in the lung and kidney within the samples. Serum urea, creatinine and tumor necrosis factor (TNF-α) were determined. RESULTS: Kefir + I/R groups was compared with I/R groups, a significant decrease (p < 0.05) was seen in Lipid peroxidation (MDA) levels of lung and renal tissues. Superoxide dismutase (SOD), Catalase (CAT) and Glutathione peroxidase (GSH-Px) activities of lung and kidney tissues decreased in I/R groups (p < 0.05). The enzyme activities in Kefir + I/R groups of renal tissues were significantly (p < 0.05) higher than I/R, not significantly different in lung tissues (p < 0.05). Kefir reduced the levels of serum urea, creatinine and TNF-α significantly. CONCLUSIONS:   This would be useful in this model against ischemia/reperfusion, and shows the protective effect of kefir in tissue and serum functions.

Temporal changes in hepatic antioxidant enzyme activities after ischemia and reperfusion in a rat liver ischemia model: effect of dietary fish oil.

This study investigated the hypothesis that administration of tilapia fish oil diet would attenuate warm liver ischemia/reperfusion injury (IRI) and whether fish oil modulates prooxidant/antioxidant status. Male Wistar rats were subjected to 30 min of approximately 70% hepatic ischemia followed by 1, 12, and 24 h reperfusion. Rats were randomly divided into three groups: sham-operated group (SO), control-warm hepatic ischemia (WI) group, and Oil-WI group given tilapia oil for 3 weeks followed by liver IRI. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured in the plasma. Levels of thiobarbituric acid reactive substances (TBARS) and antioxidant enzymes as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were measured in liver fractions. In the sham group, there was no enzymatic or histological change. I/R caused significant increase in serum AST, ALT, and tissue TBARS levels. As compared to the control group, animals treated with tilapia oil experienced a significant decrease (p < 0.05) in AST and ALT levels in reperfusion periods. Tissue TBARS levels in Oil-WI group were significantly (p < 0.05) reduced as compared to control group at 60 min after reperfusion. After ischemia, 1, 12, and 24 h of reperfusion, CAT, SOD, and GPx values were the lowest in the Oil-WI group and highest in the control group and were statistically significant (p < 0.05). Histological analysis also revealed that fish oil provided some protection compared with the control group. Tilapia oil exerts a protective effect during the early phase of reperfusion, and it modulates prooxidant/antioxidant status of rat liver subjected to warm IRI.

The TSC complex is required for the benefits of dietary protein restriction on stress resistance in vivo.

Protein restriction (PR) is important for the benefits of dietary restriction on longevity and stress resistance, but relevant nutrient sensors and downstream effectors in mammals remain poorly defined. We used PR-mediated protection from hepatic ischemia reperfusion injury to probe genetic requirements for the evolutionarily conserved nutrient sensors GCN2 and mTORC1 in stress resistance. One week of PR reduced free amino acids and circulating growth factors, activating GCN2 and mTORC1 repressor tuberous sclerosis complex (TSC). However, although GCN2 was dispensable for PR-induced protection, hepatic TSC1 was required. PR improved hepatic insulin sensitivity in a TSC1-dependent manner prior to ischemia, facilitating increased prosurvival signaling and reduced apoptosis after reperfusion. These benefits were partially abrogated by pharmacological PI3K inhibition or genetic deletion of the insulin receptor in hepatocytes. In conclusion, improved insulin sensitivity upon short-term PR required TSC1, facilitated increased prosurvival signaling after injury, and contributed partially to PR-mediated resistance to clinically relevant ischemia reperfusion injury.

Benefits of short-term dietary restriction in mammals.

Dietary or calorie restriction (DR, CR), defined as reduced food intake without malnutrition, imparts many benefits in model organisms. Extended longevity is the most popularized benefit but the least clinically relevant due to the requirement for long-term food restriction. DR also promotes stress resistance and metabolic fitness. Emerging data in experimental models and in humans indicate that these benefits occur rapidly upon initiation of DR, suggesting potential clinical relevance. Here we review data on the ability of short-term DR to induce beneficial effects on clinically relevant endpoints including surgical stress, inflammation, chemotherapy and insulin resistance. The encouraging results obtained in these preclinical and clinical studies, and the general lack of mechanistic understanding, both strongly suggest the need for further research in this emerging area.

Pectin and high-amylose maize starch increase caecal hydrogen production and relieve hepatic ischaemia-reperfusion injury in rats.

We investigated whether the feeding of high H2-generating dietary fibre and resistant starch (RS) could suppress hepatic ischaemia-reperfusion (IR) injury, which results from oxidative stress, in rats fed a pectin (Pec) or high-amylose maize starch (HAS) diet. Male Sprague-Dawley rats were fed a control (C) diet, with or without Pec (0-5 % Pec) or HAS (0-30 % HAS) supplementation for 7 d. Portal H2 concentration showed a significant dose-dependent increase with the amount of Pec or HAS supplementation. Plasma alanine and aspartate aminotransferase activities remarkably increased in the C rats (5 % cellulose) due to IR treatment, while it decreased significantly or showed tendencies to decrease in 5 % Pec and 20 % HAS diet-fed rats. The hepatic oxidised glutathione (GSSG):total glutathione ratio increased significantly in IR rats maintained on the C diet compared with sham-operated rats. On the other hand, reduced glutathione (GSH):total glutathione and GSH:GSSG ratios decreased significantly. The GSSG:total glutathione ratio that increased due to IR treatment decreased significantly on HAS and Pec intake, while GSH:total glutathione and GSH:GSSG ratios increased significantly. Hepatic sinusoids of IR rats fed the C diet were occluded, but those of IR rats fed the Pec diet were similar to those in the sham-operated rats. In conclusion, we found that Pec or HAS, which enhance H2 generation in the large intestine, alleviated hepatic IR injury. The present study demonstrates another physiological significance of dietary fibre and RS.

A new immune-modulating diet enriched with whey-hydrolyzed peptide, fermented milk, and isomaltulose attenuates gut ischemia-reperfusion injury in mice.

BACKGROUND & AIMS: Gut ischemia-reperfusion (I/R) is considered an important mechanism underlying multiple organ failure after severe surgical insults. We previously demonstrated an enteral diet enriched with whey-hydrolyzed peptide, fermented milk, and isomaltulose to have anti-inflammatory effects in a concanavalin A-induced hepatitis model. Here, we investigated whether the immune-modulating diet (IMD), could prevent systemic inflammation, thereby improving survival in a gut I/R model. METHODS: Mice were randomized into control enteral diet (n = 58) or IMD (n = 56) for 2 weeks' feeding. In experiment 1, 39 mice underwent 45 min of gut ischemia, and were sacrificed at 3 h after reperfusion to collect blood samples. Plasma IL-6 and glucose levels were measured. In experiment 2, 75 mice underwent 60 min of ischemia, and their survival was observed until 48 h. RESULTS: Plasma IL-6 and glucose levels of the IMD group were significantly lower than those of control mice. In association with these changes, the IMD improved survival rate at early time points (12 and 30 h) after gut I/R (p < 0.05, χ(2) test). CONCLUSIONS: Nutritional management with the IMD may be useful for preventing systemic inflammatory response after gut I/R.

Dietary red palm oil supplementation reduces myocardial infarct size in an isolated perfused rat heart model.

BACKGROUND AND AIMS: Recent studies have shown that dietary red palm oil (RPO) supplementation improves functional recovery following ischaemia/reperfusion in isolated hearts. The main aim of this study was to investigate the effects of dietary RPO supplementation on myocardial infarct size after ischaemia/reperfusion injury. The effects of dietary RPO supplementation on matrix metalloproteinase-2 (MMP2) activation and PKB/Akt phosphorylation were also investigated. MATERIALS AND METHODS: Male Wistar rats were divided into three groups and fed a standard rat chow diet (SRC), a SRC supplemented with RPO, or a SRC supplemented with sunflower oil (SFO), for a five week period, respectively. After the feeding period, hearts were excised and perfused on a Langendorff perfusion apparatus. Hearts were subjected to thirty minutes of normothermic global ischaemia and two hours of reperfusion. Infarct size was determined by triphenyltetrazolium chloride staining. Coronary effluent was collected for the first ten minutes of reperfusion in order to measure MMP2 activity by gelatin zymography. RESULTS: Dietary RPO-supplementation decreased myocardial infarct size significantly when compared to the SRC-group and the SFO-supplemented group (9.1 +/- 1.0% versus 30.2 +/- 3.9% and 27.1 +/- 2.4% respectively). Both dietary RPO- and SFO-supplementation were able to decrease MMP2 activity when compared to the SRC fed group. PKB/Akt phosphorylation (Thr 308) was found to be significantly higher in the dietary RPO supplemented group when compared to the SFO supplemented group at 10 minutes into reperfusion. There was, however, no significant changes observed in ERK phosphorylation. CONCLUSIONS: Dietary RPO-supplementation was found to be more effective than SFO-supplementation in reducing myocardial infarct size after ischaemia/reperfusion injury. Both dietary RPO and SFO were able to reduce MMP2 activity, which suggests that MMP2 activity does not play a major role in protection offered by RPO. PKB/Akt phosphorylation may, however, be involved in RPO mediated protection.

Temporal changes in cerebral antioxidant enzyme activities after ischemia and reperfusion in a rat focal brain ischemia model: effect of dietary fish oil.

This study investigated the neuroprotective effects of dietary supplementation of fish oil on both brain infarction and the activities of antioxidant enzymes. Male Sprague-Dawley rats (4-weeks old) were divided into two groups and received either a regular diet (RD) or a fish-oil-supplemented diet (FOD) for 6 weeks prior to middle cerebral artery (MCA) occlusion. The infarction volume of the brain was calculated using image analysis after staining. Antioxidant enzymes were measured before ischemia (BI), after 2 h of ischemia (AI) and after 24 h (24hR), 48 h (48hR) and after 7 days (7dR) of reperfusion. The infarction volume of the brain was significantly smaller in the FOD group than in the RD group after 24 h of reperfusion (p<0.05). Before ischemia, the levels of lipid peroxide and the glutathione peroxidase (GPx) activity were higher in the FOD group than in the RD group. During reperfusion, the catalase (CAT) activity in the FOD group remained at the preischemia level until after 48 h of reperfusion, while those in the RD group did not. The Mn-superoxide dismutase (SOD) activity and GPx activity were higher in the FOD group than in the RD group only after 2 h of ischemia. In the fatty acid analysis, the ratio of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were higher in the FOD group than in the RD group (p<0.05). Our results demonstrate that supplementing the diet with fish oil could decrease the cerebral infarction volume following ischemia and reperfusion (I/R) partly by working directly as an antioxidant and partly by modulating antioxidant enzyme activities.

Nutritional supplementation with mixed essential amino acids enhances myocyte survival, preserving mitochondrial functional capacity during ischemia-reperfusion injury.

In patients undergoing coronary surgery, the uptake of amino acids, which has been shown to correlate with oxygen consumption, is a mechanism of cardiac adaptation to the iatrogenic ischemia-reperfusion injury associated with cardioplegic arrest. Based on these premises, we sought to determine whether oral supplementation with mixed amino acids may protect the rat heart exposed to ischemia-reperfusion and to address whether this hypothesized cardioprotection is achieved, at least in part, through preservation of the energy-producing properties of mitochondria. Sprague-Dawley rats were fed (by enteral route) a liquid diet, with or without mixed essential amino acids (daily dose of 1 g/kg) for 30 days. Hearts from anesthetized rats were perfused by the Langendorff method and randomized to 3 groups. The control group was perfused with buffer for 60 minutes; the ischemia-reperfusion control and the amino acid-treated groups were exposed to 35 minutes of ischemia, followed by 60 or 120 minutes of reperfusion. Amino acid supplements minimized infarct size (22 +/- 1.8% vs 33 +/- 2.5%; p <0.05) and occurrence of cardiomyocyte apoptosis, as assessed by co-localization of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and caspase-3-positive staining (p <0.01). Long-term treatment with amino acids also reduced the proportion of cardiomyocytes exhibiting immunostaining for cleaved caspase-9 (p <0.01) but was ineffective on processing of caspase-8. Similar results were obtained in the whole heart by caspase activity assays (p <0.01). The lessened activation of caspase-9 detected in amino acid-treated hearts paralleled a strong reduction in mitochondrial release of cytochrome c. Adenosine triphosphate (ATP) content and rate of ATP production in isolated mitochondria were reduced by >75% in control hearts after 2 hours of reperfusion (p <0.05 vs control hearts); these values returned toward those of the control group in hearts supplemented with amino acids (p <0.01). Finally, the oxygen consumption rate in myocardial skinned bundles was markedly reduced in ischemia-reperfusion control hearts and almost normalized in amino acid-treated hearts (approximately 20% and 93% of the value for normoxic hearts; p <0.01). These results suggest that oral amino acid supplementation attenuates the extent of ischemia-reperfusion injury in the rat heart, through preservation of the mitochondria-generated production of high-energy phosphates.

Antioxidant and anti-inflammatory effects of a diet supplemented with sesamin on hepatic ischemia-reperfusion injury in rats.

BACKGROUND/AIMS: The antioxidant and anti-inflammatory properties of sesamin (a non-fat constituent of sesame oil) have been attributed to an increased accumulation of dihomo-y-linolenic acid, a precursor of 1-series prostaglandins, and the decreasing production of proinflammatory 2-series prostaglandins and 4-series leukotrienes by inhibiting the delta-5 desaturase activity. We investigated the effects of a diet containing sesamin on hepatic ischemia-reperfusion injury in rats. METHODOLOGY: After feeding rats either a basal diet (control group) or a diet supplemented with sesamin (sesamin group) for 14 days, the rats underwent 60 minutes of partial hepatic ischemia and 3 hours of reperfusion. The phospholipid fatty acid composition of both liver and lung tissue specimens were then analyzed. The plasma levels of leukotriene B4 and PCOOH (phosphatidylcholine hydroperoxide) were also determined. RESULTS: The consumption of the dietary sesamin resulted in a significant increase in the dihomo-y-linolenic acid content in the tissue phospholipids of the liver and lung specimens. The amounts of polyunsaturated fatty acids in the lungs subjected to the ischemia-reperfusion injury were well preserved in the animals from the sesamin group. Despite a lack of differences in the levels of arachidonic acid, the plasma levels of leukotriene B4 in the rats fed dietary sesamin (88 +/- 15 pg) tended to be lower (P = 0.07) than those fed the control diet (110 +/- 20 pg). Furthermore, the plasma concentrations of PCOOH in the sesamin group (130 +/- 62 pmol) were also significantly lower (P < 0.05) than those in the control group (223 +/- 33 pmol). CONCLUSIONS: These findings indicate that a diet containing sesamin may thus reduce hepatic ischemia-reperfusion injury by inducing both antioxidant and anti-inflammatory activities.

Fatty acid oxidation in the heart.

The heart is known for its ability to produce energy from fatty acids (FA) because of its important beta-oxidation equipment, but it can also derive energy from several other substrates including glucose, pyruvate, and lactate. The cardiac ATP store is limited and can assure only a few seconds of beating. For this reason the cardiac muscle can adapt quickly to the energy demand and may shift from a 100% FA-derived energy production (after a lipid-rich food intake) or any balanced situation (e.g., diabetes, fasting, exercise). These situations are not similar for the heart in terms of oxygen requirement because ATP production from glucose is less oxygen-consuming than from FA. The regulation pathways for these shifts, which occur in physiologic as well as pathologic conditions (ischemia-reperfusion), are not yet known, although both insulin and pyruvate dehydrogenase activation are clearly involved. It becomes of strategic importance to clarify the pathways that control these shifts to influence the oxygen requirement of the heart. Excess FA oxidation is closely related to myocardial contraction disorders characterized by increased oxygen consumption for cardiac work. Such an increased oxygen cost of cardiac contraction was observed in stunned myocardium when the contribution of FA oxidation to oxygen consumption was increased. In rats, an increase in n-3 polyunsaturated FA in heart phospholipids achieved by a fish-oil diet improved the recovery of pump activity during postischemic reperfusion. This was associated with a moderation of the ischemia-induced decrease in mitochondrial palmitoylcarnitine oxidation. In isolated mitochondria at calcium concentrations close to that reported in ischemic cardiomyocytes, a futile cycle of oxygen wastage was reported, associated with energy wasting (constant AMP production). This occurs with palmitoylcarnitine as substrate but not with pyruvate or citrate. The energy wasting can be abolished by CoA-SH and other compounds, but not the oxygen wasting. Again, the calcium-induced decrease in mitochondrial ADP/O ratio was reduced by increasing the n-3 polyunsaturated FA in the mitochondrial phospholipids. These data suggest that in addition to the amount of circulating lipids, the quality of FA intake may contribute to heart energy regulation through the phospholipid composition. On the other hand, other intervention strategies can be considered. Several studies have focused on palmitoylcarnitine transferase I to achieve a reduction in beta-oxidation. In a different context, trimetazidine was suggested to exert its anti-ischemic effect on the heart by interfering with the metabolic shift, either at the pyruvate dehydrogenase level or by reducing the beta-oxidation. Further studies will be required to elucidate the complex system of heart energy regulation and the mechanism of action of potentially efficient molecules.