RESUMO
BACKGROUND: Vitamin D may prevent the development of hypertension through down-regulation of renin-angiotensin system. However, epidemiologic studies assessing the interrelation of vitamin D-related biomarkers with hypertension are sparse. METHODS: We examined the prospective associations between vitamin D-related biomarkers and risk of hypertension in a nested case-control study. In each of the Women's Health Study (WHS) and Physicians' Health Study (PHS) II, 500 incident hypertension cases and 500 age and race matched controls were randomly selected. Baseline plasma 25(OH)-vitamin D [25(OH)D], parathyroid hormone (PTH), and total renin concentrations were measured. RESULTS: Among controls, 25(OH)D and PTH were inversely correlated, but neither was correlated with total renin. In the crude model, there was a trend of association between increasing quintiles of 25(OH)D and lower risk of hypertension in women, with relative risks and 95% CIs of 1.00, 1.24 (0.84-1.83), 0.82 (0.53-1.25), 0.75 (0.48-1.16), and 0.81 (0.52-1.27) (p, trend: 0.07). Adjustment for body mass index and other hypertension risk factors eliminated this association (RR of 5th quintile: 1.03). No associations were found in men. Baseline PTH and ratio of 25(OH)D to PTH were not associated with risk of hypertension in women or men. When men and women were included in the same model, vitamin D insufficiency (defined as 25(OH)D <20 ng/mL) also was not associated with increased risk of hypertension. No interactions were found across subgroups. CONCLUSIONS: Our study found no association of baseline plasma 25(OH)D or PTH with risk of hypertension or total renin concentration in middle-aged and older men and women.
RESUMO
Cell-mediated immune suppression may play an important role in lung carcinogenesis. We investigated the associations for circulating levels of tryptophan, kynurenine, kynurenine:tryptophan ratio (KTR), quinolinic acid (QA) and neopterin as markers of immune regulation and inflammation with lung cancer risk in 5,364 smoking-matched case-control pairs from 20 prospective cohorts included in the international Lung Cancer Cohort Consortium. All biomarkers were quantified by mass spectrometry-based methods in serum/plasma samples collected on average 6 years before lung cancer diagnosis. Odds ratios (ORs) and 95% confidence intervals (CIs) for lung cancer associated with individual biomarkers were calculated using conditional logistic regression with adjustment for circulating cotinine. Compared to the lowest quintile, the highest quintiles of kynurenine, KTR, QA and neopterin were associated with a 20-30% higher risk, and tryptophan with a 15% lower risk of lung cancer (all ptrend < 0.05). The strongest associations were seen for current smokers, where the adjusted ORs (95% CIs) of lung cancer for the highest quintile of KTR, QA and neopterin were 1.42 (1.15-1.75), 1.42 (1.14-1.76) and 1.45 (1.13-1.86), respectively. A stronger association was also seen for KTR and QA with risk of lung squamous cell carcinoma followed by adenocarcinoma, and for lung cancer diagnosed within the first 2 years after blood draw. This study demonstrated that components of the tryptophan-kynurenine pathway with immunomodulatory effects are associated with risk of lung cancer overall, especially for current smokers. Further research is needed to evaluate the role of these biomarkers in lung carcinogenesis and progression.