Exploratory Detection of Nile Red-Positive Microparticles in Peripheral Blood Samples from Chronic Users of Nicotine...

Particles exhibiting fluorescence after Nile Red staining have been increasingly investigated in human biological samples in the context of microplastic exposure, but their clinical relevance remains unclear. In this study, Nile Red-positive microparticles were quantified in whole blood from chronic users of different nicotine-delivery systems and non-user controls. The study included 73 nicotine users, including conventional cigarette smokers, e-cigarette users, and heated tobacco product users, as well as an age- and sex-matched control group. Only participants without diagnosed chronic somatic disease were enrolled. Microparticles were quantified by flow cytometry after Nile Red staining. Associations with age, nicotine dependence assessed with the FTND and FTQ, motivation to quit smoking assessed with the Schneider Motivation Test, and selected hematological and biochemical parameters were also analyzed. In the overall analysis, the mean number of microparticles was higher in nicotine users than in controls, but the difference was not statistically significant (p = 0.38). In subgroup analyses, higher particle counts were observed in conventional cigarette smokers and heated tobacco product users compared with controls. No significant difference was found for e-cigarette users. Higher particle counts were also observed in older participants and in participants with greater nicotine dependence. Participants with higher particle counts more often showed stronger nicotine dependence and lower motivation to quit smoking. These results suggest that circulating Nile Red-positive microparticle counts may differ according to the type of nicotine product used and selected behavioral characteristics. However, the subgroup findings should be interpreted with caution due to the exploratory design and limited statistical power.