Blood biomarkers of nicotine-induced toxicity in healthy males

Identification of biomarkers specific to five different nicotine product user groups: Study protocol of a controlled clinical trial

Background

Assessing biomarker profiles in various body fluids is of large value to discern between the sole use of nicotine products. In particular, the assessment of the product compliance is required for long-term clinical studies. The objective of this study was the identification of biomarkers and biomarker patterns in body fluids, to distinguish between combustibles, heated tobacco products, electronic cigarettes, oral tobacco and oral/dermal nicotine products used for nicotine replacement therapy (NRT), as well as a control group of non-users.

Methods

A controlled, single-center study was conducted with 60 healthy subjects, divided into 6 groups (5 nicotine product user groups and one non-user group) based on their sole use of the products of choice. The subjects were confined for 76 h, during which, free and uncontrolled use of the products was provided. Sample collections were performed according to the study time schedule provided in Table 2. The primary outcome will be validated through analysis of the collected biospecimens (urine, blood, saliva, exhaled breath and exhaled breath condensate) by means of untargeted omics approaches (i.e. exposomics, breathomics and adductomics). Secondary outcome will include established biomarker quantification methods to allow for the identification of typical biomarker patterns. Statistical analysis tools will be used to specifically discriminate different product use categories.

Results/Conclusions

The clinical trial was successfully completed in May 2020, resulting in sample management and preparations for the quantitative and qualitative analyses. This work will serve as a solid basis to discern between biomarker profiles of different nicotine product user groups. The knowledge collected during this research will be required to develop prototype diagnostic tools that can reliably assess the differences and evaluate possible health risks of various nicotine products.

The Restorative Effect of Red Guava (Psidium guajava L.) Fruit Extract on Pulmonary Tissue of Rats (Rattus norvegicus) Exposed to Cigarette Smoke

Since the damage to alveolar tissue due to cigarette smoke exposure (CSE) is lipid peroxidation, antioxidant treatment is needed. The red guava (Psidium guajava L.) fruit contains antioxidants derived from quercetin, lycopene, and vitamin C. This study aimed to determine the effect of red guava fruit extract (RGFE) on the alveolar tissue of rats exposed to cigarette smoke. The 25 rats (Rattus norvegicus) were divided into five groups. The control and T0 groups were only administered placebo, while T1, T2, and T3 groups were orally administered RGFE of 18.9, 37.8, and 56.7 mg/kg body weight daily for 44 days. The CSE dose of 20 suctions daily was conducted on T0, T1, T2, and T3 groups on days 15–44. On day 45, all rats were sacrificed for serum collection and histopathological lung slides with eosin-nigrosin staining. The result showed that CSE caused an increase (p < 0.05) in malondialdehyde (MDA) levels, cell death, apoptosis, and necrosis percentages, congestion and thickening of alveolar septum tissue, and reduction in the alveolar diameter and alveolar number. Administration of RGFE suppressed those effects, and the highest dose of RGFE (T3) restored (p > 0.05) MDA levels, percentage of apoptotic and necrosis, alveolar septal thickening, and alveolar diameter. However, the percentages of cell death, alveolar congestion, and the alveolar number were still worse (p < 0.05) than in normal rats. It could be concluded that RGFE has proved relief and restoration of the alveolar tissue of rats exposed to cigarette smoke.

Urinary biomarkers for secondhand smoke and heated tobacco products exposure

Concerns have recently grown about the health effects of secondhand smoke exposure and heated tobacco products. The analysis of tobacco smoke biomarkers is critical to assess the health effects of tobacco smoke exposure. For this purpose, the simultaneous determinations of exposure markers and health effect markers would provide a better evaluation of smoke exposure. In this study, nicotine metabolites (nicotine, cotinine, trans-3'-hydroxycotinine) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in urine were analyzed as exposure markers. The DNA damage markers, 7-methylguanine and 8-hydroxy-2'-deoxyguanosine, were simultaneously measured as health effect markers. The results revealed significant levels of urinary nicotine metabolites and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in the subjects exposed to secondhand smoke and heated tobacco products. In addition, the urinary levels of 7-methylguanine and 8-hydroxy-2'-deoxyguanosine tended to be high for secondhand smoke and heated tobacco products exposures, as compared to those of non-smokers. These biomarkers will be useful for evaluating tobacco smoke exposure.