In vivo effect of chronic nicotine exposure on outcome of Plasmodium berghei ANKA malaria

Abstract

Objective: To assess effect of nicotine, major addictive component of tobacco smoke, on outcomes of the deadly malaria parasite using mice as animal model. Methods: Male Swiss albino mice were treated with 100 and 200 µg/mL of nicotine in drinking water daily for 6 weeks followed by Plasmodium berghei ANKA (PbA) infection. On the seventh day of post infection (p.i.), physical, clinical, histopathological, biochemical and hematological parameters were assessed. Data were analyzed using SPSS software. Results: Nicotine was significantly (P < 0.05) positively associated with lower levels of hemoglobin (Hb), hematocrit (HCT), red blood cells (RBCs), C-reactive protein (CRP) and uric acid (UA), higher risk to incidence of pulmonary edema, elevated level of liver and kidney biomarkers. Also significant increment (P < 0.01) of monocyte-lymphocyte count ratio (MLCR) was observed. Risk to high temperature, lower platelet count, high parastemia and cerebral malaria was lesser in mice treated with nicotine (100 and 200 µg/mL) followed by PbA infection than the positive control. Lack of neurological symptoms might be accounted to the anti-inflammatory property of nicotine that could inhibit production of pro-inflammatory mediators responsible for occurrence of cerebral malaria. Conclusions: This study showed that despite down regulation of most cerebral malaria symptoms nicotine was strongly associated with increased risk to most clinical symptoms of malaria. Thus, like in respiratory infections, nicotine use might enhance susceptibility to malaria.