Stobadine attenuates impairment of an intestinal barrier model caused by 4-hydroxynonenal

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring.

As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders.

Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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Maternal heminic vs. non-heminic iron intake differentially and persistently imprints the offspring's fecal microbiota.

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Males from heme-fed dams exhibit increased gut lumen reactive aldehydes in absence of direct dietary exposure to heme iron.

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Some of the increased reactive aldehydes closely covariated with Orders belonging to Bacteroidales and Lachnospirales.

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Maternal exposure to dietary heme iron impairs gut barrier and glucose tolerance in male offspring.

Haem iron reshapes colonic luminal environment: impact on mucosal homeostasis and microbiome through aldehyde formation

BACKGROUND

The World Health Organization classified processed and red meat consumption as "carcinogenic" and "probably carcinogenic", respectively, to humans. Haem iron from meat plays a role in the promotion of colorectal cancer in rodent models, in association with enhanced luminal lipoperoxidation and subsequent formation of aldehydes. Here, we investigated the short-term effects of this haem-induced lipoperoxidation on mucosal and luminal gut homeostasis including microbiome in F344 male rats fed with a haem-enriched diet (1.5 μmol/g) 14-21 days.

RESULTS

Changes in permeability, inflammation, and genotoxicity observed in the mucosal colonic barrier correlated with luminal haem and lipoperoxidation markers. Trapping of luminal haem-induced aldehydes normalised cellular genotoxicity, permeability, and ROS formation on a colon epithelial cell line. Addition of calcium carbonate (2%) to the haem-enriched diet allowed the luminal haem to be trapped in vivo and counteracted these haem-induced physiological traits. Similar covariations of faecal metabolites and bacterial taxa according to haem-induced lipoperoxidation were identified.

CONCLUSIONS

This integrated approach provides an overview of haem-induced modulations of the main actors in the colonic barrier. All alterations were closely linked to haem-induced lipoperoxidation, which is associated with red meat-induced colorectal cancer risk.

Intraperitoneal injection of 4-hydroxynonenal (4-HNE), a lipid peroxidation product, exacerbates colonic inflammation through activation of Toll-like receptor 4 signaling

Human and animal studies have shown that the colonic concentrations of lipid peroxidation products, such as 4-hydroxynonenal (4-HNE), are elevated in inflammatory bowel disease (IBD). However, the actions and mechanisms of these compounds on the development of IBD are unknown. Here, we show that a systemic treatment of low-dose 4-HNE exacerbates dextran sulfate sodium (DSS)-induced IBD in C57BL/6 mice, suggesting its pro-IBD actions in vivo. Treatment with 4-HNE suppressed colonic expressions of tight-junction protein occludin, impaired intestinal barrier function, enhanced translocation of lipopolysaccharide (LPS) and bacterial products from the gut into systemic circulation, leading to increased activation of Toll-like receptor 4 (TLR4) signaling in vivo. Furthermore, 4-HNE failed to promote DSS-induced IBD in Tlr4^-/- mice, supporting that TLR4 signaling contributes to the pro-IBD effects of 4-HNE. Together, these results suggest that 4-HNE exacerbates the progression of IBD through activation of TLR4 signaling, and therefore could contribute to the pathogenesis of IBD.

HNE and cholesterol oxidation products in colorectal inflammation and carcinogenesis

Consistent experimental data suggest the importance of inflammation-associated oxidative stress in colorectal cancer (CRC) pathogenesis. Inflammatory bowel disease with chronic intestinal inflammation is now considered a precancerous condition. Oxidative stress is an essential feature of inflammation. Activation of redox-sensitive pro-inflammatory cell signals and inflammatory mediators concur to establish a pro-tumoral environment. In this frame, lipid oxidation products, namely 4-hydroxynonenal and oxysterols, can be produced in big quantity so as to be able to exert their function as inducers of cell signaling pathways of proliferation and survival. Notably, an important source of these two compounds is represented by a high fat diet, which is undoubtedly a risk factor for inflammation and CRC development. Current evidence for the emerging implication of these two oxidized lipids in inflammation and CRC development is discussed in this review.

Protocatechualdehyde Protects Against Cerebral Ischemia-Reperfusion-Induced Oxidative Injury Via Protein Kinase Cε/Nrf2/HO-1 Pathway

Oxidative stress is closely related to the pathogenesis of ischemic stroke. Protocatechualdehyde (PCA) is a phenolic acid compound that has the putative antioxidant activities. The present study was aimed to investigate the molecular mechanisms involved in the antioxidative effect of PCA against cerebral ischemia/reperfusion (I/R) injury. The experiment stroke model was produced in Sprague-Dawley rats via middle cerebral artery occlusion (MCAO). To model ischemia-like conditions in vitro, differentiated SH-SY5Y cells were exposed to transient oxygen and glucose deprivation (OGD). Treatment with PCA significantly improved neurologic score, reduced infarct volume and necrotic neurons, and also decreased reactive oxygen species (ROS) production, 4-hydroxynonenal (4-HNE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents at 24 h after reperfusion. Meanwhile, PCA significantly increased the transcription nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions in the ischemic cerebral cortex as shown by immunofluorescence staining and Western blot analysis. In vitro experiment showed that PCA protected differentiated SH-SY5Y cells against OGD-induced injury. Likewise, PCA also increased markedly the Nrf2 and HO-1 expressions in a dose-dependent manner. The neuroprotection effect of PCA was abolished by knockdown of Nrf2 and HO-1. Moreover, knockdown of protein kinase Cε (PKCε) also blocked PCA-induced Nfr2 nuclear translocation, HO-1 expression, and neuroprotection. Taken together, these results provide evidences that PCA can protect against cerebral ischemia-reperfusion-induced oxidative injury, and the neuroprotective effect involves the PKCε/Nrf2/HO-1 pathway.

Dietary polyunsaturated fatty acids and heme iron induce oxidative stress biomarkers and a cancer promoting environment in the colon of rats

The end products of polyunsaturated fatty acid (PUFA) peroxidation, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE), and isoprostanes (8-iso-PGF2α), are widely used as systemic lipid oxidation/oxidative stress biomarkers. However, some of these compounds have also a dietary origin. Thus, replacing dietary saturated fat by PUFAs would improve health but could also increase the formation of such compounds, especially in the case of a pro-oxidant/antioxidant imbalanced diet. Hence, the possible impact of dietary fatty acids and pro-oxidant compounds was studied in rats given diets allowing comparison of the effects of heme iron vs. ferric citrate and of ω-6- vs. ω-3-rich oil on the level of lipid peroxidation/oxidative stress biomarkers. Rats given a heme iron-rich diet without PUFA were used as controls. The results obtained have shown that MDA and the major urinary metabolite of HNE (the mercapturic acid of dihydroxynonane, DHN-MA) were highly dependent on the dietary factors tested, while 8-iso-PGF2α was modestly but significantly affected. Intestinal inflammation and tissue fatty acid composition were checked in parallel and could only explain the differences we observed to a limited extent. Thus, the differences in biomarkers were attributed to the formation of lipid oxidation compounds in food or during digestion, their intestinal absorption, and their excretion into urine. Moreover, fecal extracts from the rats fed the heme iron or fish oil diets were highly toxic for immortalized mouse colon cells. Such toxicity can eventually lead to promotion of colorectal carcinogenesis, supporting the epidemiological findings between red meat intake and colorectal cancer risk. Therefore, the analysis of these biomarkers of lipid peroxidation/oxidative stress in urine should be used with caution when dietary factors are not well controlled, while control of their possible dietary intake is needed also because of their pro-inflammatory, toxic, and even cocarcinogenic effects.

Pharmaceutical properties of calycosin, the major bioactive isoflavonoid in the dry root extract of Radix astragali

CONTEXT

Radix astragali (Fabaceae astragalus propinquus Schischkin) is a Chinese medicinal herb traditionally used for the treatment of several diseases. Calycosin is the major bioactive chemical in the dry root extract of this medical plant.

OBJECTIVE

This work presents a brief overview of recent reports on the potential effects of calycosin on several diseases and the possible mechanisms of action of this chemical.

MATERIALS AND METHODS

This review gathers information from the scientific literature (before 1 June 2013) that was compiled from various databases, such as Science Direct, PubMed, Google Scholar, and Scopus.

RESULTS

The potential pharmaceutical properties of calycosin in the treatment of tumors, inflammation, stroke, and cardiovascular diseases have gained increasing attention in the recent years. The literature survey showed that calycosin exhibits promising effects for the treatment of several diseases and that these effects may be due to its isoflavonoid and phytoestrogenic properties. The effects of calycosin most likely result from its interaction with the ER receptors on the cell membrane and the modulation of the MAPK signaling pathway.

CONCLUSION

Calycosin exhibits great potential as a therapeutic drug and may be a successful example of the standardization and modernization of traditional Chinese herbal medicine.

Therapeutic time window and underlying therapeutic mechanism of breviscapine injection against cerebral ischemia/reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Breviscapine injection is a Chinese herbal medicine standardized product extracted from Erigeron breviscapus (Vant.) Hand.-Mazz. It has been widely used for treating cardiovascular and cerebrovascular diseases. However, the therapeutic time window and the action mechanism of breviscapine are still unclear. The present study was designed to investigate the therapeutic time window and underlying therapeutic mechanism of breviscapine injection against cerebral ischemic/reperfusion injury.

MATERIALS AND METHODS

Sprague-Dawley rats were subjected to middle cerebral artery occlusion for 2h followed by 24h of reperfusion. Experiment part 1 was used to investigate the therapeutic time window of breviscapine. Rats were injected intravenously with 50mg/kg breviscapine at different time-points of reperfusion. After 24h of reperfusion, neurologic score, infarct volume, brain water content and serum level of neuron specific enolase (NSE) were measured in a masked fashion. Part 2 was used to explore the therapeutic mechanism of breviscapine. 4-Hydroxy-2-nonenal (4-HNE), 8-hydroxyl-2'- deoxyguanosine (8-OHdG) and the antioxidant capacity of ischemia cortex were measured by ELISA and ferric-reducing antioxidant power (FRAP) assay, respectively. Immunofluorescence and western blot analysis were used to analyze the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1).

RESULTS

Part 1: breviscapine injection significantly ameliorated neurologic deficit, reduced infarct volume and water content, and suppressed the levels of NSE in a time-dependent manner. Part 2: breviscapine inhibited the increased levels of 4-HNE and 8-OHdG, and enhanced the antioxidant capacity of cortex tissue. Moreover, breviscapine obviously raised the expression of Nrf2 and HO-1 proteins after 24h of reperfusion.

CONCLUSION

The therapeutic time window of breviscapine injection for cerebral ischemia/reperfusion injury seemed to be within 5h after reperfusion. By up-regulating the expression of Nrf2/HO-1 pathway might be involved in the therapeutic mechanism of breviscapine injection.

Age- and diabetes-induced regulation of oxidative protein modification in rat brain and peripheral tissues: consequences of treatment with antioxidant pyridoindole

The increased glyco- and lipo-oxidation events are considered one of the major factors in the accumulation of non-functional damaged proteins, and the antioxidants may inhibit extensive protein modification and nitrosylated protein levels, enhancing the oxidative damage at the cellular levels in aging and diabetes. Because of its central role in the pathogenesis of age-dependent and diabetes-mediated functional decline, we compared the levels of oxidatively modified protein markers, namely AGEs (Advanced Glycation End-protein adducts), 4-HNE (4-hydroxy-nonenal-histidine) and 3-NT (3-nitrotyrosine), in different tissues of young and old rats. Separately, these three oxidative stress parameters were explored in old rats subjected to experimentally induced diabetes and following a long-term treatment with a novel synthetic pyridoindole antioxidant derived from stobadine-SMe1EC2 (2-ethoxycarbonyl-8-methoxy-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b]indolinium dichloride). Diabetes induced by streptozotocin injection in rats aged 13-15 months, and SMe1EC2 treatment was applied during 4months to aged diabetic rats. AGEs and 4-HNE levels were significantly elevated in brain, ventricle and kidney, but not in lens and liver of aged rats when compared with young rats. Diabetes propagated ageing-induced increase in AGEs and 4-HNE in brain, ventricle and kidney, and raised significantly lens and liver AGEs and 4-HNE levels in aged rats. In aged diabetic rats, SMe1EC2 protected only the kidney against increase in AGEs, and inhibited significantly 4-HNE levels in brain, kidney, liver and lens that were observed more pronounced in lens. 3-NT was significantly increased in brain of aged rats and in kidney, lens and ventricle of aged diabetic rats, while SMe1EC2 has no protective effect on 3-NT increase. Results demonstrate that (1) the responsiveness of different tissue proteins to glyco-lipo-oxidative and nitrosative stress in the course of normal aging was miscellaneous. (2) Diabetes is a major factor contributing to accelerated aging. (3) SMe1EC2 selectively inhibited the generation of oxidatively modified proteins, only in a limited number of tissues.