Respiratory disorders: Ironing out smoking-related airway disease

Targeting the mitochondria in chronic respiratory diseases

Mitochondria are one of the basic essential components for eukaryotic life survival. It is also the source of respiratory ATP. Recently published studies have demonstrated that mitochondria may have more roles to play aside from energy production. There is an increasing body of evidence which suggest that mitochondrial activities involved in normal and pathological states contribute to significant impact to the lung airway morphology and epithelial function in respiratory diseases such as asthma, COPD, and lung cancer. This review summarizes the pathophysiological pathways involved in asthma, COPD, lung cancer and highlights potential treatment strategies that target the malfunctioning mitochondria in such ailments. Mitochondria are responsive to environmental stimuli such as infection, tobacco smoke, and inflammation, which are essential in the pathogenesis of respiratory diseases. They may affect mitochondrial shape, protein production and ultimately cause dysfunction. The impairment of mitochondrial function has downstream impact on the cytosolic components, calcium control, response towards oxidative stress, regulation of genes and proteins and metabolic activities. Several novel compounds and alternative medicines that target mitochondria in asthma and chronic lung diseases have been discussed here. Moreover, mitochondrial enzymes or proteins that may serve as excellent therapeutic targets in COPD are also covered. The role of mitochondria in respiratory diseases is gaining much attention and mitochondria-based treatment strategies and personalized medicine targeting the mitochondria may materialize in the near future. Nevertheless, more in-depth studies are urgently needed to validate the advantages and efficacy of drugs that affect mitochondria in pathological states.

The Interactive Effect of High Doses of Chromium(III) and Different Iron(III) Levels on the Carbohydrate Status, Lipid Profile, and Selected Biochemical Parameters in Female Wistar Rats

The aim of the study was to evaluate the main and interactive effects of chromium(III) propionate complex (Cr3) supplementation and different iron supply on the carbohydrate metabolism, lipid profile and other selected biochemical parameters of rats. The experiment was carried out in a two-factor design, in which rats were fed a diet with different proportions of Fe(III) and Cr(III) for six weeks. Fifty-four healthy female Wistar rats were divided into nine experimental groups with different Fe(III) levels, i.e. adequate-control group (45 mg/kg)-100% recommended daily dietary dose of Fe for rodents, deficient (5 mg/kg) and oversupply (180 mg/kg-400%). At the same time they were supplemented with Cr(III) of doses 1 (adequate), 50 and 500 mg/kg of diet. The activity and concentrations of most biochemical parameters were measured with standard enzymatic, kinetic, and colorimetric methods. HOMA-IR and QUICKI indexes were calculated according to appropriate formulas. It was found that there was an interactive effect of high Cr(III) doses and different Fe(III) levels in the diet on the carbohydrate metabolism and insulin resistance indexes. The presented results suggested that iron deficient diet fed animals led to insulin resistance; however, an effect is attenuated by Cr(III) supplementation at high doses. There were no significant changes in the rats' lipid profile (except for the high density lipoprotein cholesterol (HDL-C) level) and most of the other biochemical parameters, such as the leptin, aspartate aminotransferase (AST), alanine transaminase (ALT), total protein (TP), creatinine (Crea) and the urea (BUN) concentrations. The study proved that the Cr(III) supplementation, independently and in combination with diversified Fe(III) content in the diet, affected the carbohydrate metabolism and insulin resistance indexes but did not affect lipid profile and most of the other biochemical parameters in healthy rats. The findings proved the role of Fe and Cr(III) and their interactions on disturbances carbohydrates metabolism.

Overexpression of MECP2 attenuates cigarette smoke extracts induced lung epithelial cell injury by promoting CYP1B1 methylation

MECP2 (Methyl-CpG-binding protein 2) has been shown to have a critical role in regulating DNA methylation against smoke exposed lung injury. However, the biological function of MECP2 and the underlying molecular mechanism remains elusive. Human bronchial epithelial (16HBE) and alveolar type II epithelial cells (AECII) were exposed to increasing concentrations of cigarette smoke extracts (CSE) solution to establish CSE-induced lung epithelial cell injury models. Our findings revealed that MECP2 was down-regulated, while CYP1B1 was up-regulated in CSE-induced lung epithelial cell injury models by quantitative real time PCR, western blotting and immunofluorescence staining. Down-regulated CYP1B1 was ascribed to the demethylation of its promoter by methylation-specific PCR (MSP). The in vitro experiments further showed that MECP2 overexpression significantly attenuated CSE-triggered cell growth attenuation, cell cycle arrest, apoptosis and ROS generation in lung epithelial cells by CCK-8 and flow cytometry assays. In molecular level, we further demonstrated that MECP2 overexpression obviously suppressed the expression of CYP1B1 through enhancing DNA methylation. Therefore, our data suggest that MECP2 protects against CSE-induced lung epithelial cell injury possibly through down-regulating CYP1B1 expression via elevating its methylation status.

The Combined Effects of Cr(III) Supplementation and Iron Deficiency on the Copper and Zinc Status in Wistar Rats

The aim of the study was to assess the combined effects of chromium(III) supplementation and iron deficiency on the copper (Cu) and zinc (Zn) status in female rats. The Cr, Fe, Cu and Zn dietary and tissular levels were measured by Atomic Absorption Spectrometry (AAS) method. The data show that chromium(III) supplementation compensated for the negative effects of Fe deficiency on the Cu content but it deepened the effect on Zn levels in the female rats. Detailed data on the status of trace elements and their interactions in healthy subjects and patients with metabolic disorders (e.g. anaemia, diabetes mellitus) are strongly required for effective nutritional and therapeutic strategies.

Ginsenoside Rb3 exerts protective properties against cigarette smoke extract-induced cell injury by inhibiting the p38 MAPK/NF-κB and TGF-β1/VEGF pathways in fibroblasts and epithelial cells

Cigarette smoke causes many adverse effects such as inflammation, oxidative stress, and excessive accumulation of the extracellular matrix (ECM). Ginsenoside Rb3 has anti-inflammatory and anti-oxidative effects, which may contribute to delaying the injury caused by cigarette smoke. In this study, we used cigarette smoke extract (CSE) to establish cell injury models in WI-38 human fetal lung fibroblasts and 16HBE human bronchial epithelial cells. Our results showed that Rb3 protected against CSE-induced cytotoxicity in both cell lines. In addition, it significantly inhibited the secretion of inflammatory factors, such as interleukin-8 and tumor necrosis factor alpha, by inhibiting the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB). Moreover, Rb3 pre-treatment led to an increase in the levels of glutathione (GSH) and activities of superoxide dismutase, glutathione peroxidase (GSH-Px), and catalase to reduce the oxidative stress induced by CSE. Additionally, Rb3 decreased the levels of ECM proteins including collagen I (Col I), Col III, and elastin after CSE treatment by inhibiting the expression of transforming growth factor beta 1 (TGF-β1)-induced vascular endothelial growth factor (VEGF). Our findings suggest that Rb3 prevented CSE-induced inflammation and oxidative stress as well as the excessive accumulation of ECM in WI-38 and 16HBE cells to protect against cell injury by inhibiting the p38 MAPK/NF-κB and TGF-β1/VEGF pathways. The results of this study may be valuable for the development of Rb3 to combat the damage caused by cigarette smoke.

The Combined Effects of Iron Excess in the Diet and Chromium(III) Supplementation on the Iron and Chromium Status in Female Rats

Inadequate iron supply has significant consequences to health. There are some relations between the metabolism of different trace elements, such as iron, zinc, copper and chromium. However, the direction of these interactions can be antagonistic or synergistic, and it depends on many factors. The aim of the study was to evaluate the combined effects of supplementary of chromium(III) propionate complex (Cr3) with iron excess on the Cr and Fe status in healthy female rats. The 36 healthy female Wistar rats were divided into six experimental groups (six animals in each) with different Fe levels-adequate (45 mg kg^-1-100% RDA) and high (excessive-180 mg kg^-1-400% RDA). At the same time, they were supplemented with Cr(III) at doses of 1, 50 and 500 mg kg^-1 of diet: C1-control (Fe 45 mg kg^-1, Cr 1 mg kg^-1); C50 (Fe 45 mg kg^-1, Cr 50 mg kg^-1); C500 (Fe 45 mg kg^-1, Cr 500 mg kg^-1); H1 (Fe 180 mg kg^-1, Cr 1 mg kg^-1); H50 (Fe 180 mg kg^-1, Cr 50 mg kg^-1); H500 (Fe 180 mg kg^-1, Cr 500 mg kg^-1). The serum iron level and total iron binding capacity (TIBC) were measured with colorimetric methods. The serum ferritin level was measured by means of electrochemiluminescence immunoassay. The serum transferrin level was measured with the ELISA method. Haematological measurements were made with an automated blood analyser. The Cr and Fe tissular levels were measured with the AAS method. The exposure to a high level of Fe(III) alone or in combination with Cr caused Fe accumulation in tissues, especially in the liver and kidneys, but there were no significant changes in the TIBC, transferrin, ferritin concentration in the serum and most haematological parameters. Moreover, the serum, hepatic and renal Cr concentrations decreased. The doses of supplementary Cr(III) given separately or in combination with high level of Fe(III) disturbed the Cr content in the liver and kidneys of healthy female rats. However, they did not change most of the parameters of Fe metabolism, except the Fe kidney concentration. Supplementary Cr3 decreased the renal Fe level in groups with adequate Fe content in the diet. However, the renal Fe levels increased along with a higher Cr level in the diet in groups with high Fe content. The findings proved a relationship between Fe(III) and Cr(III) metabolism in healthy female rats. However, the direction of change varied and depended on relative amounts of these elements in the diet.

What do polymorphisms tell us about the mechanisms of COPD?

COPD (chronic obstructive pulmonary disease) is characterized by irreversible lung airflow obstruction. Cigarette smoke is the major risk factor for COPD development. However, only a minority number of smokers develop COPD, and there are substantial variations in lung function among smokers, suggesting that genetic determinants in COPD susceptibility. During the past decade, genome-wide association studies and exome sequencing have been instrumental to identify the genetic determinants of complex traits, including COPD. Focused studies have revealed mechanisms by which genetic variants contribute to COPD and have led to novel insights in COPD pathogenesis. Through functional investigations of causal variants in COPD, from the proteinase-antiproteinase theory to emerging roles of developmental pathways (such as Hedgehog and Wnt pathways) in COPD, we have greatly expanded our understanding on this complex pulmonary disease. In this review, we critically review functional investigations on roles of genetic polymorphisms in COPD, and discuss future challenges and opportunities in discovering novel mechanisms of functional variants.