Theophylline Acetaldehyde as the Initial Product in Doxophylline Metabolism in Human Liver.

Doxophylline (DOXO) and theophylline are widely used as bronchodilators for treating asthma and chronic obstructive pulmonary disease, and DOXO has a better safety profile than theophylline. How DOXO's metabolism and disposition affect its antiasthmatic efficacy and safety remains to be explored. In this study, the metabolites of DOXO were characterized. A total of nine metabolites of DOXO were identified in vitro using liver microsomes from human and four other animal species. Among them, six metabolites were reported for the first time. The top three metabolites were theophylline acetaldehyde (M1), theophylline-7-acetic acid (M2), and etophylline (M4). A comparative analysis of DOXO metabolism in human using liver microsomes, S9 fraction, and plasma samples demonstrated the following: 1) The metabolism of DOXO began with a cytochrome P450 (P450)-mediated, rate-limiting step at the C ring and produced M1, the most abundant metabolite in human liver microsomes. However, in human plasma, the M1 production was rather low. 2) M1 was further converted to M2 and M4, the end products of DOXO metabolism in vivo, by non-P450 dismutase in the cytosol. This dismutation process also relied on the ratio of NADP+/NADPH in the cell. These findings for the first time elucidated the metabolic sites and routes of DOXO metabolism in human. SIGNIFICANCE STATEMENT: We systematically characterized doxophylline metabolism using in vitro and in vivo assays. Our findings evolved the understandings of metabolic sites and pathways for methylxanthine derivatives with the aldehyde functional group.

Thymoquinone ameliorates the PM2.5-induced lung injury in rats.

BACKGROUND: This study aims to explore the effect of thymoquinone (TQ) on particulate matter 2.5 (PM2.5)-induced lung injury. METHODS: The PM2.5 sample was provided by Shenyang Environment Monitor Central Station. Lung injury was established by intratracheal instillation PM2.5 (7.5 mg/kg) followed by TQ treatment (20 and 40 mg/kg) for 14 d in rats. Hematoxylin and eosin (HE) and Evans blue dye (EBD) staining were detected on lung tissues. ELISA, real-time PCR, western blotting and TUNEL assays were also performed. RESULTS: The data showed that TQ diminished lung injury and EBD accumulation. The number of macrophages, neutrophils, eosinophils, and lymphocytes was ameliorated after TQ treatment. In addition, TQ suppressed the inflammation reaction parameters (interleukin-1ß and -6, IL-1ß and IL-6; tumor necrosis factor-α, TNF-α) and oxidative stress in PM2.5-induced lung injury. The levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase (HO-1) were increased due to the treatment of TQ. The number of TUNEL-positive cells was prominently reduced in TQ-treated rats compared with that in PM2.5 group. Intratracheal instillation PM2.5 activated autophagy, whilst TQ blocked it in lung. CONCLUSIONS: Taken together, this study provides the first in vivo evidence that TQ suppresses inflammation, oxidative stress, apoptosis, and autophagy in PM2.5-induced lung injury.

Overexpression of Forkhead box C1 attenuates oxidative stress, inflammation and apoptosis in chronic obstructive pulmonary disease.

AIM: Chronic obstructive pulmonary disease (COPD) is a disease caused by cigarette smoke, which has been emerging as a serious health problem worldwide. The aim of this study is to explore the mRNA expression profile of lung tissues from the COPD rats and to characterize the role of Forkhead box C1 (Foxc1) in COPD. MAIN METHODS: Wistar rats were exposed to cigarette smoke during 16 weeks for COPD model establishment. The microarray was used to identify the differential gene expression in the lung of rats. Adenovirus carrying Foxc1 was administered to rats by intratracheally instillation once a week for 16 weeks. Human bronchial epithelial cell line (16HBE) cells were transfected with Foxc1 siRNA followed by incubation in the presence of CSE (10%) for 24 h. Subsequently, the pathological changes, fibrosis, apoptosis, inflammatory cytokines and oxidative stress were detected. KEY FINDINGS: Microarray results showed an upregulation of Foxc1 in lung tissues in COPD rats. Overexpression of Foxc1 mitigated the lung injury, as evidenced by reducing alveolar fusion, inflammatory cell infiltration and oxidative stress. Additionally, the apoptosis was remarkably increased in the lung in rats exposed to cigarette smoke, which was suppressed by Foxc1 overexpression. Furthermore, downregulation of Foxc1 aggravated the inflammation, oxidative stress and apoptosis in 16HBE cells with CSE treatment. SIGNIFICANCE: Overexpression of Foxc1 could prevent oxidative stress, inflammation responses and cell apoptosis and knockdown of Foxc1 has the opposite effect, suggesting that Foxc1 may be available for lung protection during COPD.

The roles of synovial hyperplasia, angiogenesis and osteoclastogenesis in the protective effect of apigenin on collagen-induced arthritis.

Apigenin (API) is a plant flavone that is known to exert a protective effect in rheumatoid arthritis (RA), which is a chronic autoimmune disease. However, the molecular mechanism for API's protective effect against RA is still unclear. Here, a collagen-induced arthritis (CIA) mouse model was used to assess the protective effect of API on RA. Histomorphological studies, immunohistochemistry, RT-PCR, and western blot were conducted to elucidate the roles of synovial hyperplasia, angiogenesis, and osteoclastogenesis in the protective effect of API on RA. Fibroblast-like synoviocytes (FLSs) were isolated to measure the effect of API on FLS proliferation and apoptosis. API exhibited a significant protective effect in CIA mice in a dose- and time-dependent manner. An increase in apoptosis and decrease in proliferation were observed after the API treatment in FLSs, suggesting that API might inhibit synovial hyperplasia. Moreover, CIA angiogenesis was repressed by API via down-regulation of VEGF and VEGFR. Furthermore, API regulated the osteoclastogenesis-associated RANKL/RANK/OPG system in CIA mice. Therefore, API inhibits CIA by repressing synovial hyperplasia, angiogenesis, and osteoclastogenesis. This suggested that API might be a putative low toxicity candidate drug for RA treatment.

Development and validation of a UPLC-MS/MS method for quantification of doxofylline and its metabolites in human plasma.

A sensitive and specific ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for simultaneous determination of doxofylline and its two metabolites in human plasma. After protein precipitation with methanol, the chromatographic separation was carried out on an ACQUITY UPLC HSS T3 column, with acetonitrile and 0.1% formic acid in water as mobile phase at a flow rate of 0.30 mL·min-1. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source, with target quantitative ion pairs of m/z 267.0→181.1 for doxofylline, 239.0→181.1 for theophylline-7-acetic acid and 225.1→181.1 for etofylline. The calibration curve was linear over the range of 2-3000 ng·mL-1 (r > 0.99). The LLOQ was evaluated to be 2 ng·mL-1. The method described herein allowed simultaneous determination of the three analytes for the first time and was successfully applied to the pharmacokinetic study of doxofylline and its metabolites after intravenous administration in healthy volunteers.

Relationship between atmospheric pollutants and risk of death caused by cardiovascular and respiratory diseases and malignant tumors in Shenyang, China, from 2013 to 2016: an ecological research.

BACKGROUND: Air pollutants and their pathogenic effects differ among regions and seasons. We aimed to explore the relationship between fine particulate matter (PM2.5), sulfur dioxide (SO2), and ozone-8 hours (O3-8h) concentrations in heating and non-heating seasons and the associated death risk due to cardiovascular diseases (CDs), respiratory diseases (RDs), and malignant tumors. METHODS: Data were collected in Shenyang, China, from April 2013 to March 2016. We analyzed the correlation or lagged effect of atmospheric pollutant concentration, meteorological conditions, and death risk due to disorders of the circulatory system, respiratory system, and malignant tumor in heating and non-heating seasons. We also used multivariate models to analyze the association of air pollutants during holidays with the death risk due to the evaluated diseases while considering the presence or absence of meteorological factors. RESULTS: An increase in the daily average SO2 concentration by 10 µg/m increased the death risk by CDs, which reached a maximum of 2.0% (95% confidence interval [CI]: 1.3%-2.7%) on lagging day 4 during the non-heating season and 0.2% (95% CI: 0.1%-0.4%) on lagging day 3 during the heating season. The risk of death caused by RDs peaked on lagging day 1 by 0.8% (95% CI: 0.4%-1.2%) during the heating season. An increase in O3-8h concentration by 10 µg/m increased the risk of RD-related death on lagging day 2 by 1.0% (95% CI: 0.4%-1.7%) during the non-heating season, which was significantly higher than the 0.1% (95% CI: 0-0.9%) increase during the heating season. Further, an increase in the daily average PM2.5 concentration by 10 µg/m increased the risk of death caused by RDs by 0.3% and 0.8% during heating and non-heating seasons, respectively, which peaked on lagging day 0. However, air pollution was not significantly associated with the risk of death caused by malignant tumors. CONCLUSION: Short-term exposure to PM2.5, SO2, and O3 during the non-heating season resulted in higher risks of CD-related death, followed by RD-related death.