Cyclo(His-Pro) exerts anti-inflammatory effects by modulating NF-κB and Nrf2 signalling

Mifepristone-inducible recombinant adenovirus attenuates paraquat-induced lung injury in rats

Objective:

To investigate the effects of overexpression of nuclear factor E2-related factor-2 (NRF2) on lung injury in rats exposed to paraquat (PQ) poisoning.

Methods:

A mifepristone (RU486)-inducible recombinant adenoviral vector carrying the human NRF2 gene (Ad-RUNRF2) was constructed and transfected via airway into the rats 7 days before the administration of RU486. Rats were orally challenged with PQ at 20 mg/kg 24 h after the injection of RU486. On days 0.5, 3 and 21 after PQ poisoning, the expressions of NRF2 and cytokines related to inflammation and oxidation in lung tissue were examined.

Results:

RU486 remarkably enhanced NRF2 mRNA and NRF2 protein levels in Ad-RUNRF2-transfected rats in a dose-dependent manner ( p < 0.01). PQ stimulated compensatory overexpression of NRF2, heme oxygenase 1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO-1) in lungs on days 0.5 and 3 after exposure ( p < 0.05), but depleted the expression of catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione (GSH), with an increased malondialdehyde (MDA) ( p < 0.05). However, pretreatment with Ad-RUNRF2 and RU486 strongly enhanced the expression levels of NRF2, HO-1, NQO-1, CAT and GSH-Px in the lungs of PQ intoxicated rats, with increased GSH and decreased MDA ( p < 0.05). Pretreatment with Ad-RUNRF2 and RU486 also strongly suppressed the PQ-induced activation of nuclear factor κB (NF-κB) and decreased the levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). In addition, Ad-RUNRF2 and RU486 induction significantly reduced PQ-induced pathological changes in lungs and attenuated lung oedema and protein leakage caused by PQ ( p < 0.05).

Conclusion:

RU486-induced overexpression of NRF2 in lungs transfected with Ad-RUNRF2 can ameliorate PQ-induced lung injury by the activation of the NRF2-antioxidant response element (ARE) pathway.

Neuroinflammation and endoplasmic reticulum stress are coregulated by cyclo(His-Pro) to prevent LPS neurotoxicity

Many neurological and neurodegenerative diseases are associated with oxidative stress and glial inflammation, all related to endoplasmic reticulum stress. Cyclo(His-Pro) is an endogenous cyclic dipeptide that exerts cytoprotection by interfering with the Nrf2-NF-κB systems, the former presiding the antioxidant and the latter the pro-inflammatory cellular response. Here we investigated whether the cyclic dipeptide inhibits glial inflammation thus reducing the detrimental effect of inflammatory neurotoxins on neurons. We found that systemic administration of cyclo(His-Pro) exerts in vivo anti-inflammatory effects in the central nervous system by down-regulating hepatic and cerebral TNFα expression thereby counteracting LPS-induced gliosis. Mechanistic studies indicated that the cyclic dipeptide-mediated effects are achieved through the activation of Nrf2-driven antioxidant response and the inhibition of the pro-inflammatory NF-κB pathway. Moreover, by up-regulating Bip, cyclo(His-Pro) increases the ER stress sensitivity and triggers the unfolded protein response to alleviate the ER stress. These results unveil a novel potential therapeutic use of cyclo(His-Pro) against neuroinflammatory-related diseases and we might now consider its potential anti-inflammatory role in other neuropathological conditions.

Dietary vitamin D deficiency in rats from middle to old age leads to elevated tyrosine nitration and proteomics changes in levels of key proteins in brain: implications for low vitamin D-dependent age-related cognitive decline

In addition to the well-known effects of vitamin D (VitD) in maintaining bone health, there is increasing appreciation that this vitamin may serve important roles in other organs and tissues, including the brain. Given that VitD deficiency is especially widespread among the elderly, it is important to understand how the range of serum VitD levels that mimic those found in humans (from low to high) affects the brain during aging from middle age to old age. To address this issue, 27 male F344 rats were split into three groups and fed isocaloric diets containing low (100 IU/kg food), control (1000 IU/kg food), or high (10,000 IU/kg food) VitD beginning at middle age (12 months) and continued for a period of 4-5 months. We compared the effects of these dietary VitD manipulations on oxidative and nitrosative stress measures in posterior brain cortices. The low-VitD group showed global elevation of 3-nitrotyrosine compared to control and high-VitD-treated groups. Further investigation showed that this elevation may involve dysregulation of the nuclear factor κ-light-chain enhancer of activated B cells (NF-κB) pathway and NF-κB-mediated transcription of inducible nitric oxide synthase (iNOS) as indicated by translocation of NF-κB to the nucleus and elevation of iNOS levels. Proteomics techniques were used to provide insight into potential mechanisms underlying these effects. Several brain proteins were found at significantly elevated levels in the low-VitD group compared to the control and high-VitD groups. Three of these proteins, 6-phosphofructokinase, triose phosphate isomerase, and pyruvate kinase, are involved directly in glycolysis. Two others, peroxiredoxin-3 and DJ-1/PARK7, have peroxidase activity and are found in mitochondria. Peptidyl-prolyl cis-trans isomerase A (cyclophilin A) has been shown to have multiple roles, including protein folding, regulation of protein kinases and phosphatases, immunoregulation, cell signaling, and redox status. Together, these results suggest that dietary VitD deficiency contributes to significant nitrosative stress in brain and may promote cognitive decline in middle-aged and elderly adults.

Redox activation of Nrf2 & NF-κB: a double end sword?

Moderate concentrations of reactive oxygen species (ROS) are produced by diverse sources under physiological conditions. At such low levels, these molecules may act as upstream mediators of relevant signaling pathways; however an increase in their concentration with respect to the antioxidant system activity, changes their redox signaling function into a deleterious role. Thus, cell health depends, at least in part, on redox balance. This review includes global aspects of oxygen chemistry, ROS generation, antioxidant system, and redox signaling. It is also focused on the description of two relevant redox-sensitive transcription factors: nuclear factor erythroid 2-related factor 2 (Nrf2), which may be a potential target to confer cell protection, and nuclear factor κB (NF-κB), which is involved in deleterious effects in the cell. Finally, recent findings on the interplay between both factors for the development of different pathologies are discussed.

Direction of aminoacylated transfer RNAs into antibiotic synthesis and peptidoglycan-mediated antibiotic resistance

Prokaryotic aminoacylated-transfer RNAs often need to be efficiently segregated between translation and other cellular biosynthetic pathways. Many clinically relevant bacteria, including Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa direct some aminoacylated-tRNA species into peptidoglycan biosynthesis and/or membrane phospholipid modification. Subsequent indirect peptidoglycan cross-linkage or change in membrane permeability is often a prerequisite for high-level antibiotic resistance. In Streptomycetes, aminoacylated-tRNA species are used for antibiotic synthesis as well as antibiotic resistance. The direction of coding aminoacylated-tRNA molecules away from translation and into antibiotic resistance and synthesis pathways are discussed in this review.

Relationship between hepatic dysfunction and prognosis in patients with paraquat poisoning: Clinical effects of hemopurification therapy

AIM: To investigate the relationship between hepatic dysfunction and prognosis in patients with paraquat poisoning, and to assess the clinical effects of hemopurification therapy [hemoperfusion (HP), continuous venovenous hemodiafiltration (CVVHDF), plasma exchange (PE)] in these patients.

METHODS: The clinical data for 55 patients with paraquat poisoning who were treated at EICU in our hospital from January 2009 to October 2012 were analyzed retrospectively. The patients were divided into two groups, death group and survival group. ALT, AST, TBIL and DBIL were measured on the 1st, 4th, 7th and 14th day after poisoning. The patients were then divided into two groups according to the use of CVVHDF therapy or not to evaluate the effect of this treatment on hepatic function.

RESULTS: At each time point, the levels of all the hepatic function parameters in the death group were significantly higher than those in the survival group (all P < 0.05). HP was performed in all patients. Two patients who received PE treatment were dead. The mortality in the CVVHDF group was significantly higher than that in the non-CVVHDF group (P < 0.01), and there was no significant difference for all liver function parameters at each time point between the CVVHDF group and non-CVVHDF group.

CONCLUSION: Paraquat poisoning can cause hepatic dysfunction. The changes in liver function parameters, especially high bilirubin, might be reliable predictors of prognosis. Hemopurification therapy, especially CVVHDF, is useless in patients with paraquat poisoning in terms of improving liver function and decreasing mortality.