Nicotine and the kidney: Mr. Hyde, and perhaps some Dr. Jekyll

Comparison of secondhand smoking exposure between self-report and creatinine-corrected urine cotinine: Result from Korean NHANES 2009-2018

BACKGROUND/PURPOSE

Second-hand smoking (SHS) is usually examined by self-report (SR). However, there is a possibility that SR may not accurately measure SHS exposure. This study aimed to identify yearly trends and gender differences in SHS by SR and cotinine.

METHODS

We used data from the 2009-2018 Korea National Health and Nutrition Examination Survey (KNHANES) and included adults aged 19 years and older. We analyzed data of 47,907 respondents on SHS exposures in the past week and of 23,572 respondents who had both urine cotinine and creatinine measurements. SHS exposure was defined as those who answered 'yes' to whether or not they were exposed to smoking by SR. We performed descriptive analysis, Average annual percentage change (AAPC), and multiple regression analysis. All analyses were weighted reflecting the multi-stratified cluster sampling.

RESULTS

Exposure to SHS indoors at the work place (WSHS) (2009: 44.8%, 2018: 12.3%), indoors at home (HSHS) (2009: 14.1%, 2018: 3.9%), and indoors at public places (PSHS) (2013: 55.6%, 2018: 15.4%) decreased steadily over the years. WSHS and PSHS exposure was higher for males but HSHS was higher for females. However, the concentration of cotinine-to-creatinine ratio (Co/Cr) was higher among females regardless of SHS exposure status and environment. Multiple regression analysis showed that among males, the association between Co/Cr education level and WSHS was the strongest, and among females, the association was the strongest with HSHS. In addition, home exposure to SHS intensified the differences in Co/Cr levels between males and females.

CONCLUSION

Our study confirmed that cotinine-induced SHS showed different results by year and gender compared to SR. In particular, Co/Cr level in females was higher than in males regardless of exposure by SR, suggesting that SR did not correctly evaluate SHS. To reflect reality more accurately, biomarkers should be monitored along with SR.

Activation of the Cholinergic Anti-Inflammatory Pathway as a Novel Therapeutic Strategy for COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) underlined the urgent need for alleviating cytokine storm. We propose here that activating the cholinergic anti-inflammatory pathway (CAP) is a potential therapeutic strategy. However, there is currently no approved drugs targeting the regulatory pathway. It is evident that nicotine, anisodamine and some herb medicine, activate the CAP and exert anti-inflammation action in vitro and in vivo. As the vagus nerve affects both inflammation and specific immune response, we propose that vagus nerve stimulation by invasive or non-invasive devices and acupuncture at ST36, PC6, or GV20, are also feasible approaches to activate the CAP and control COVID-19. It is worth to investigate the efficacy and safety of the strategy in patients with COVID-19.

Maternal Hypercholesterolemia Associated with Nicotine Exposure in Adulthood May Induce Kidney Injury in Male Rats if Hypomagnesemia Occurs

BACKGROUND/AIMS

Maternal hypercholesterolemia is a risk factor to renal injury in rat pups at adulthood, especially if they feed a cholesterol-enriched diet after weaning. However, the renal function of male pups of dams with hypercholesterolemia (PH) that were fed a regular chow from weaning to adulthood needs investigation, particularly those exposed to an adverse risk such as nicotine.

METHODS

We evaluated the renal function of PH animals and we compared the data with those found in male pups of control dams (PC) at 3- and 6-month-old by inulin clearance. Moreover, we investigated the effect of nicotine treatment for 8 days in both PH and PC animals at 6 months old via metabolic function studies and by renal histological analysis.

RESULTS

Inulin clearance and other renal function parameters were similar in PH and PC animals at 3 and 6 months old. Nevertheless, the PH group showed significant differences with regard to histological analysis despite a similar number of glomeruli. The glomerular area of PH animals was significantly smaller than that measured in PC animals, and the fractional interstitial area was significantly larger in PH animals than that measured in PC animals at 3 months old. With regard to nicotine treatment, we observed a trend for a reduction in creatinine clearance in both PC and PH groups, but only PH animals showed hypomagnesemia and the highest fractional interstitial area.

CONCLUSIONS

The offspring exposed to a high cholesterol milieu during intrauterine and neonatal life may show a silent kidney injury at adulthood that may be aggravated by nicotine exposure if hypomagnesemia occurs.

Anti-smoking legislation and its effects on urinary cotinine and cadmium levels

Anti-smoking legislation has been associated with an improvement in health indicators. Since the cadmium (Cd) body burden in the general population is markedly increased by smoke exposure, we analyzed the impact of the more restrictive legislation that came into force in Spain in 2011 by measuring Cd and cotinine in first morning urine samples from 83 adults in Madrid (Spain) before (2010) and after (2011) introduction of this law. Individual pair-wise comparisons showed a reduction of creatinine corrected Cotinine and Cd levels for non-active smokers, i. e. those which urinary cotinine levels are below 50 μg/L. After the application of the stricter law, cotinine levels in urine only decreased in non-active smokers who self-reported not to be exposed to second-hand smoke. The reduction in second hand smoke exposure was significantly higher in weekends (Friday to Sunday) than in working days (Monday to Thursday). The decrease in U-Cd was highly significant in non-active smokers and, in general, correlated with lower creatinine excretion. Therefore correction by creatinine could bias urinary Cd results, at least for cotinine levels higher than 500 μg/L. The biochemical/toxicological benefits detected herein support the stricter application of anti-smoking legislation and emphasize the need to raise the awareness of the population as regards exposure at home.