A novel therapeutic potential of the anti-hiv ritonavir against Blastocystis hominis: a dual approach in vitro and in vivo.

Blastocystis hominis (B. hominis) is one of the most prevalent enteric protists. Treatment is challenging because the standard drug, metronidazole, has reported treatment failures and drug resistance in some instances. This highlights the need for new, active, safe, and more efficient alternatives. The purpose of this study was to assess the in vitro and in vivo efficacy of ritonavir (an anti-HIV protease inhibitor) compared to metronidazole against B. hominis. Concerning the in vitro study, three cultures were used as follows: inoculated un-treated, metronidazole-treated, and ritonavir-treated. Parasite count and scanning electron microscopy were assessed. The in vivo study was done on 40 laboratory- bred albino mice, which were divided into four groups (each of ten) as follows: non-infected un-treated, infected un-treated group, metronidazole-treated, and ritonavir-treated. The effects of treatment were assessed by parasitological study, histopathological examination of the intestine, and immunohistochemical evaluation of immunoglobulin A (IgA) expression. Moreover, ELISA measurement of the serum levels of IL-1β, IL-8, and TNF-α was done. For the in vitro findings, ritonavir revealed a high efficacy in comparison with metronidazole in decreasing the parasite count and showed effective surface changes. For the in vivo findings, there was a highly significant decrease in the parasite count in stool and intestinal contents with marked improvement of the histopathological changes as compared to the infected un-treated group with increasing the expression of IgA. Moreover, there was a highly significant reduction in the serum levels of IL-1β, IL-8, and TNF-α. In conclusion, ritonavir was found to be effective against B. hominis with anti-inflammatory and immune stimulatory effects.