Alterations in the molecular control of mitochondrial turnover in COPD lung and airway epithelial cells.

Abnormal mitochondria have been observed in bronchial- and alveolar epithelial cells of patients with chronic obstructive pulmonary disease (COPD). However, it is unknown if alterations in the molecular pathways regulating mitochondrial turnover (mitochondrial biogenesis vs mitophagy) are involved. Therefore, in this study, the abundance of key molecules controlling mitochondrial turnover were assessed in peripheral lung tissue from non-COPD patients (n = 6) and COPD patients (n = 11; GOLDII n = 4/11; GOLDIV n = 7/11) and in both undifferentiated and differentiated human primary bronchial epithelial cells (PBEC) from non-COPD patients and COPD patients (n = 4-7 patients/group). We observed significantly decreased transcript levels of key molecules controlling mitochondrial biogenesis (PPARGC1B, PPRC1, PPARD) in peripheral lung tissue from severe COPD patients. Interestingly, mRNA levels of the transcription factor TFAM (mitochondrial biogenesis) and BNIP3L (mitophagy) were increased in these patients. In general, these alterations were not recapitulated in undifferentiated and differentiated PBECs with the exception of decreased PPARGC1B expression in both PBEC models. Although these findings provide valuable insight in these pathways in bronchial epithelial cells and peripheral lung tissue of COPD patients, whether or not these alterations contribute to COPD pathogenesis, underlie changes in mitochondrial function or may represent compensatory mechanisms remains to be established.

Perinatal High-Fat Diet Influences Ozone-Induced Responses on Pulmonary Oxidant Status and the Molecular Control of Mitophagy in Female Rat Offspring.

Previous research has shown that a perinatal obesogenic, high-fat diet (HFD) is able to exacerbate ozone-induced adverse effects on lung function, injury, and inflammation in offspring, and it has been suggested that mitochondrial dysfunction is implicated herein. The aim of this study was to investigate whether a perinatal obesogenic HFD affects ozone-induced changes in offspring pulmonary oxidant status and the molecular control of mitochondrial function. For this purpose, female Long-Evans rats were fed a control diet or HFD before and during gestation, and during lactation, after which the offspring were acutely exposed to filtered air or ozone at a young-adult age (forty days). Directly following this exposure, the offspring lungs were examined for markers related to oxidative stress; oxidative phosphorylation; and mitochondrial fusion, fission, biogenesis, and mitophagy. Acute ozone exposure significantly increased pulmonary oxidant status and upregulated the molecular machinery that controls receptor-mediated mitophagy. In female offspring, a perinatal HFD exacerbated these responses, whereas in male offspring, responses were similar for both diet groups. The expression of the genes and proteins involved in oxidative phosphorylation and mitochondrial biogenesis, fusion, and fission was not affected by ozone exposure or perinatal HFD. These findings suggest that a perinatal HFD influences ozone-induced responses on pulmonary oxidant status and the molecular control of mitophagy in female rat offspring.

Galacto-oligosaccharides supplementation in prefrail older and healthy adults increased faecal bifidobacteria, but did not impact immune function and oxidative stress.

BACKGROUND & AIMS: Ageing is associated with an increased risk of frailty, intestinal microbiota perturbations, immunosenescence and oxidative stress. Prebiotics such as galacto-oligosaccharides (GOS) may ameliorate these ageing-related alterations. We aimed to compare the faecal microbiota composition, metabolite production, immune and oxidative stress markers in prefrail elderly and younger adults, and investigate the effects of GOS supplementation in both groups. METHODS: In a randomised controlled cross-over study, 20 prefrail elderly and 24 healthy adults received 21.6 g/day Biotis™ GOS (containing 15.0 g/day GOS) or placebo. Faecal 16S rRNA gene-based microbiota and short-chain fatty acids were analysed at 0, 1 and 4 weeks of intervention.Volatile organic compounds were analysed in breath, and stimulated cytokine production, CRP, malondialdehyde, trolox equivalent antioxidant capacity (TEAC) and uric acid (UA) in blood at 0 and 4 weeks. RESULTS: Principle coordinate analysis showed differences in microbial composition between elderly and adults (P≤0.05), with elderly having lower bifidobacteria (P≤0.033) at baseline. In both groups, GOS affected microbiota composition (P≤0.05), accompanied by increases in bifidobacteria (P<0.001) and decreased microbial diversity (P≤0.023). Faecal and breath metabolites, immune and oxidative stress markers neither differed between groups (P ≥ 0.125) nor were affected by GOS (P ≥ 0.236). TEAC values corrected for UA were higher in elderly versus adults (P<0.001), but not different between interventions (P ≥ 0.455). CONCLUSIONS: Elderly showed lower faecal bifidobacterial (relative) abundance than adults, which increased after GOS intake in both groups. Faecal and breath metabolites, parameters of immune function and oxidative stress were not different at baseline, and not impacted by GOS supplementation. CLINICALTRIALS. GOV WITH STUDY ID NUMBER: NCT03077529.

The dietary antioxidant quercetin reduces hallmarks of bleomycin-induced lung fibrogenesis in mice.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic, lethal disease of which the etiology is still not fully understood. Current treatment comprises two FDA-approved drugs that can slow down yet not stop or reverse the disease. As IPF pathology is associated with an altered redox balance, adding a redox modulating component to current therapy might exert beneficial effects. Quercetin is a dietary antioxidant with strong redox modulating capacities that is suggested to exert part of its antioxidative effects via activation of the redox-sensitive transcription factor Nrf2 that regulates endogenous antioxidant levels. Therefore, the aim of the present study was to investigate if the dietary antioxidant quercetin can exert anti-fibrotic effects in a mouse model of bleomycin-induced pulmonary fibrogenesis through Nrf2-dependent restoration of redox imbalance. METHODS: Homozygous Nrf2 deficient mice and their wildtype littermates were fed a control diet without or with 800 mg quercetin per kg diet from 7 days prior to a single 1 µg/2 µl per g BW bleomycin challenge until they were sacrificed 14 days afterwards. Lung tissue and plasma were collected to determine markers of fibrosis (expression of extracellular matrix genes and histopathology), inflammation (pulmonary gene expression and plasma levels of tumor necrosis factor-α (TNFα) and keratinocyte chemoattrachtant (KC)), and redox balance (pulmonary gene expression of antioxidants and malondialdehyde-dG (MDA)- DNA adducts). RESULTS: Mice fed the enriched diet for 7 days prior to the bleomycin challenge had significantly enhanced plasma and pulmonary quercetin levels (11.08 ± 0.73 µM versus 7.05 ± 0.2 µM) combined with increased expression of Nrf2 and Nrf2-responsive genes compared to mice fed the control diet in lung tissue. Upon bleomycin treatment, quercetin-fed mice displayed reduced expression of collagen (COL1A2) and fibronectin (FN1) and a tendency of reduced inflammatory lesions (2.8 ± 0.7 versus 1.9 ± 0.8). These beneficial effects were accompanied by reduced pulmonary gene expression of TNFα and KC, but not their plasma levels, and enhanced Nrf2-induced pulmonary antioxidant defences. In Nrf2 deficient mice, no effect of the dietary antioxidant on either histology or inflammatory lesions was observed. CONCLUSION: Quercetin exerts anti-fibrogenic and anti-inflammatory effects on bleomycin-induced pulmonary damage in mice possibly through modulation of the redox balance by inducing Nrf2. However, quercetin could not rescue the bleomycin-induced pulmonary damage indicating that quercetin alone cannot ameliorate the progression of IPF.

Does Ataxia Telangiectasia Mutated (ATM) protect testicular and germ cell DNA integrity by regulating the redox status?

A balanced redox homeostasis in the testis is essential for genetic integrity of sperm. Reactive oxygen species can disturb this balance by oxidation of glutathione, which is regenerated using NADPH, formed by glucose-6-phosphate dehydrogenase (G6PDH). G6PDH is regulated by the Ataxia Telangiectasia Mutated (Atm) protein. Therefore, we studied the redox status and DNA damage in testes and sperm of mice that carried a deletion in Atm. The redox status in heterozygote mice, reflected by glutathione levels and antioxidant capacity, was lower than in wild type mice, and in homozygotes the redox status was even lower. The redox status correlated with oxidative DNA damage that was highest in mice that carried Atm deletions. Surprisingly, G6PDH activity was highest in homozygotes carrying the deletion. These data indicate that defective Atm reduces the redox homeostasis of the testis and genetic integrity of sperm by regulating glutathione levels independently from G6PDH activity.

The flavonoid monoHER promotes the adaption to oxidative stress during the onset of NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease. An evidence-based pharmacological treatment for NAFLD is still lacking, but flavonoids have shown therapeutic potential. The present study was designed to investigate the effect of the flavonoid monoHER on the onset of NAFLD in Ldlr(-/-) mice on a high-fat and high-cholesterol diet. The focus was put on the effect on oxidative stress as well as the adaptive response. Wild type mice served as a control and the effect of monoHER was compared to that of a placebo. In the Ldlr(-/-) group, monoHER provided only a mild protection against oxidative stress. In the placebo Ldlr(-/-) group an adaptive response elicited by the NRF2 antioxidant defense system was observed, evidenced by a higher HO-1 and Gpx3 gene expression, as well as an increased redox status, evidenced by the higher GSH/GSSG ratio. In the monoHER treated Ldlr(-/-) group both the adaptive response as well as the increase in redox status tended to be higher, although this did not reach significance on a group level. Unexpectedly, a strong within animal relationship was found that links a high adaptive response to a low redox status in the monoHER Ldlr(-/-) group. This correlation was absent in the placebo and wild type group. The concept that emerges is that a thiol-reactive oxidation product of monoHER, formed during oxidative stress, selectively induces the NRF2 pathway and enforces the endogenous antioxidant shield, to provide protection against NAFLD.

Inhibition of transmethylation disturbs neurulation in chick embryos.

Periconceptional folic acid supplementation can reduce the occurrence of neural tube defects. A low folate status will result in reduced remethylation of homocysteine (Hcy) to methionine and, subsequently, in a rise of Hcy levels. Indeed, elevated Hcy concentrations have been reported in mothers of children with neural tube defects. In our previous study, we showed that treatment of chick embryos with Hcy resulted in a delay of neural tube closure in an in vitro model. In the present study, we examined whether this effect of Hcy is due to inhibition of transmethylation via elevation of S-adenosylhomocysteine (AdoHcy). Transmethylation involves methylation of DNA, RNA and proteins by donation of a methyl group from S-adenosylmethionine (AdoMet). After application of inhibitors of S-adenosylhomocysteine hydrolase and of methionine adenosyltransferase, a delay of anterior neuropore closure, comparable to that observed after Hcy treatment, was observed. The changes in AdoMet and AdoHcy concentrations confirmed the inhibition of S-adenosylhomocysteine hydrolase or methionine adenosyltransferase, respectively, and the AdoMet/AdoHcy ratio was decreased in all cases, indicating reduced transmethylation. Moreover, the inhibition of methionine adenosyltransferase was prevented by pretreatment with methionine. This study, therefore, indicates that the Hcy-induced delay of the neural tube closure is caused by the inhibition of transmethylation via elevation of AdoHcy levels and a reduction of the AdoMet/AdoHcy ratio.