The association of serum klotho with pulmonary function among US adults: a cross-sectional study

Klotho has been found to be an anti-aging gene, of which the protein expression level declines with age. Lower levels of klotho protein were found to be associated with a variety of chronic diseases including hypertension, chronic kidney disease and depression. In this study, we aim to investigate the association between serum klotho and pulmonary function parameters among American adults.

A total of 6,385 participants aged 40-79 years from the National Health and Nutrition Examination Survey 2007-2012 were included in this cross-sectional study. Multivariate linear regression and restricted cubic spline were conducted to estimate the association between serum klotho levels and forced expiratory volume 1st second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEF) and forced expiratory flow between 25% and 75% of vital capacity (FEF25-75%).

Compared with the participants of the first quartile of klotho (545.61pg/ml), those who with the second (733.14 pg/ml), third (897.18 pg/ml) and fourth (1270.51 pg/ml) quartile klotho were of higher FEV1 and FEF25-75% (all p value < 0.05); in addition, those who with the third and fourth quartile klotho were likely to perform higher FVC and PEF (all p value < 0.05). Restricted cubic spline visualized there were nonlinear correlation between log-transformed klotho and FEV1, FVC, PEF, FEF25-75%. Subgroup analysis by gender and age group indicated that there were positive associations between klotho and pulmonary function parameters in males and the 60-79-years-old participants.

There was a comprehensive positive correlation between serum klotho and pulmonary function parameters in the adults. Further research should address to the confirmation of the causal links between klotho and pulmonary function, as well as the application of klotho to the health care and clinical treatment for pulmonary function.