Evaluation of the effect of auranofin alone and in combination with nitazoxanide on Cryptosporidium parvum in immunosuppressed mice.

Cryptosporidium parvum (C. parvum), a zoonotic protozoan parasite with a worldwide distribution, causes life-threatening diarrhea in children and immunosuppressed individuals. Although Nitazoxanide (NTZ) is the only FDA-approved drug against C. parvum, it has shown unsatisfactory results. Auranofin (AUR), an FDA-approved drug for rheumatoid arthritis, has a robust anti-protozoal effect through thioredoxin reductase (TrxR) inhibition, inducing oxidative stress and reactive oxygen species (ROS) production, thus causing parasites' apoptosis. The purpose of the present study was to evaluate the effect of AUR on C. parvum in comparison and in combination with NTZ in immunosuppressed mice. Sixty mice were divided into six groups (10 mice each): Normal control, uninfected immunosuppressed, infected control, NTZ, AUR, and combination groups. The combination group showed the highest percentage of oocysts reduction (93.5 %), followed by the AUR group (64.7 %), with the least reduction in the NTZ group (45.4 %). Histological examination of ileal tissues revealed marked restoration of normal histological features in the combination group, and remarkable improvement in the AUR group, with mild improvement in the NTZ group. The combination group also showed the least nod-like receptor protein 3 (NLRP3) immunohistochemical expression, followed by the AUR group, then the NTZ group. Biochemically, the combination and AUR groups showed the highest reduction in interferon gamma (IFN-γ) and interleukin 1β (IL-1β) levels and the highest increase in IL-10 levels, suggesting AUR's anti-inflammatory effect. The AUR group produced the highest levels of malondialdehyde (MDA) and nitric oxide (NO) and the lowest levels of reduced glutathione (GSH), superoxide dismutase (SOD) and TrxR, signifying AUR-induced oxidant effect. In conclusion, AUR achieved superior results regarding different studied parameters compared to NTZ, thus emphasizing its promising anti-cryptosporidial activities, with the best outcomes in the combination group.