Kidney damage following a 90-day subchronic inhalation exposure to HTP aerosol in SD rats

Cigarette smoking (CS) was reported to induce the risk of renal diseases. However, heated tobacco product (HTP), a modified risk tobacco product, was claimed to reduce exposure risk, its health risk of kidney was still unclear. In this study, subchronic inhalation toxicity of HTP aerosols for 90 days was performed to assess its health risk of kidney. The nose-only exposure experiments were performed with SD rats. All the rats were randomly divided into sham, HTP (HTP_10, HTP_23, and HTP_50), and CS (Cig_23) groups. After exposure, the blood and kidney were prepared to detect its redox state, biomarkers in the early injury, apoptosis, and histopathology. The results showed that HTP and cigarette smoke both induced the expression of biomarkers including kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, interleukin 18, and oxidative stress. For biochemical markers associated with kidney function, CS induced increased creatinine and urea for female rats and uric acid decreased, while HTP exposure only induced the upregulation of creatinine. Moreover, no obvious apoptosis and pathology of kidney were observed after HTP exposure, which indicated that HTP exposure may induce some biomarkers in the early stage of kidney injury without more serious changes. Overall, these results suggested that HTP with high concentration exposure showed potential slight health risks of kidney.