Personal PM2.5 exposure and lung function: Potential mediating role of systematic inflammation and oxidative damage in urban adults from the general population

BACKGROUND

Short-term effects of fine particulate matter (PM_2.5) exposure on lung function have been reported. However, few studies have assessed PM_2.5 exposure on the personal level, and the mechanism underlying the effects of PM_2.5 exposure on lung function remains less clear.

OBJECTIVES

To evaluate the association between personal PM_2.5 exposure and lung function alteration in general population and to explore the roles of systematic inflammation and oxidative damage in this association.

METHODS

A total of 7685 lung function tests were completed among 4697 urban adults in Wuhan, China. Plasma C-reactive protein (CRP), urinary 8-iso-prostaglandin-F_2α (8-iso-PGF_2α) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured. Personal PM_2.5 exposure levels were estimated using an estimation model from the actual measurements of individual PM_2.5 levels in 191 participants. Mixed linear models were used to evaluate the association between personal PM_2.5 exposure and lung function. Mediation analyses were conducted to investigate the roles of CRP, 8-iso-PGF_2α and 8-OHdG in above associations.

RESULTS

After adjusting for confounders, each 10 μg/m³ increase in the previous-day personal PM_2.5 exposure was associated with 2.94 mL, 2.02 mL and 16.14 mL/s decreases in forced vital capacity (FVC), forced expiration volume in 1 s (FEV₁) and peak expiratory flow, respectively. The associations were more obvious among never smokers compared with current smokers. Cumulative 7-day exposure to PM_2.5 led to the strongest adverse effects on lung function. Among never smokers with high PM_2.5 exposure levels, a positive relationship was observed between personal PM_2.5 level and urinary 8-iso-PGF_2α, and 8-iso-PGF_2α meditated 4.69% and 12.30% of the association between the 7-day moving PM_2.5 concentration and FVC and FEV₁, respectively. We did not observe a significant positive association between PM_2.5 exposure and plasma CRP or urinary 8-OHdG.

CONCLUSION

Short-term personal exposure to PM_2.5 is associated with reduced pulmonary ventilation function. Urinary 8-iso-PGF_2α partly mediates these associations.

Serum vitamin B6, folate, and homocysteine concentrations and oxidative DNA damage in Japanese men and women

OBJECTIVE

Higher vitamin B status has been linked to a lower risk for cancer, but the underlying mechanism remains elusive. The aim of the present study was to examine the association of pyridoxal, folate, and homocysteine (Hcy) with urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage.

METHODS

The participants were 500 employees (293 men and 207 women), ages 21 to 66 y, of two municipal offices in Japan. Serum pyridoxal and Hcy concentrations were measured using high-performance liquid chromatography (HPLC) method, and serum folate concentrations were measured using chemiluminescent immunoassay. Urinary 8-OHdG concentrations were measured using HPLC method. Multiple regression was used to estimate means of 8-OHdG for each tertile of pyridoxal, folate, and Hcy with adjustment for potential confounders.

RESULTS

In multivariate analysis, 8-OHdG concentration was inversely associated with pyridoxal concentration in men (P for trend = 0.045) but not in women. The association in men was confined to non-smokers (P for trend = 0.033) or those who consumed no or < 20 g/d of ethanol (P for trend = 0.048). 8-OHdG concentrations were not appreciably associated with folate and Hcy concentrations.

CONCLUSION

The results suggest that vitamin B6, but not folate and homocysteine, plays a role against oxidative DNA damage in Japanese men.

Urinary 8-OHdG: A marker of oxidative stress to DNA and total antioxidant status in essential hypertension with South Indian population

Establishment of non-invasive urinary biomarker for the early prediction of essential hypertension (EH) is important. We evaluated whether estimation of urinary DNA, serves as a marker to predict the extent of cellular oxidative stress in essential hypertension. A total of 180 South Indian subjects aged 30-65 were recruited for the study. Of these hypertensive subjects investigated, 30 were newly diagnosed and were not on any antihypertensive drugs, but had systolic blood pressure 140-160 mmHg and diastolic blood pressure 95-100 mmHg and 75 hypertensive patients who already on drug therapy for one year and 75 were South Indian normotensive healthy controls with blood pressure ≤ 120/80 mmHg. The 8-OHdG level in urine was significantly increased in hypertensive patients (both newly diagnosed and who already on drug therapy) compared with control group. The significant increase in 8-OHdG was observed in newly diagnosed hypertensive patients compared with hypertensive patients who already on drug therapy. There was a significant decrease in serum TAS value in essential hypertensive group when compared to control group. The urinary 8-OHdG was independently correlated with serum TAS. Decreased TAS levels, which reflect to increased oxidative stress, may be the reason of increased urinary 8-OHdG in South Indian hypertensive patients. Our preliminary data suggest that the competitive ELISA for 8-OHdG appears to be a simple method for quantifying the extent of oxidative stress.