Vitamin D: a potential therapeutic for giardiasis in experimentally infected mice

The prevalence rates of giardiasis, caused by G. lamblia (G. lamblia), vary significantly, with estimates of 20-30% and 2-5% in developing and developed countries respectively. Metronidazole is the primary medication for treating giardiasis, but it is associated with several side effects. Moreover, studies have shown that G. lamblia has developed resistance to many drugs including metronidazole, which necessitate the development of other effective therapeutics. Recent studies suggested that Vitamin D supplementation might be beneficial in the treatment of parasitic diseases. Therefore, our study investigated the therapeutic potential of Vitamin D in murine giardiasis. Molecular docking of Vitamin D was performed on the active site of both pyruvate: ferredoxin oxidoreductase (PFOR) and aldose reductase. G. lamblia cysts were collected from stool samples of infected patients after their consent. Forty male Swiss albino mice, each between 3 and 4 weeks old and weighing 20-25 g, were divided into four groups, ten mice each. Group 1 included uninfected untreated mice (negative control), whereas group 2 included infected untreated mice (positive control). Group 3 consisted of infected mice treated orally with metronidazole (MTZ) at a dose of 15 mg/kg/day for seven consecutive days while group 4 consisted of infected mice treated orally with Vitamin D at dosages of 10,000 IU/kg for eight doses. All mice were euthanized 3 days post-treatment and the small intestine and livers were collected for the assessment of drug efficacy. The efficacy of Vitamin D was evaluated by counting the number of G. lamblia trophozoites in infected mice, histopathological examination of the intestine and liver tissues and measurement of the level of liver enzymes, and evaluation of the expression of iNOS and IL-17 in the intestine of mice. Our findings indicate that mice infected with G. lamblia and treated with vitamin D demonstrated a modest decrease in the mean counts of G. lamblia trophozoites in comparison to MTZ treated group (reductions (R%) were 71.7% and 52.6%, for MTZ- and Vitamin D-treated groups respectively, in comparison to infected untreated mice group). On the other hand, the histopathological examination demonstrated that Vitamin D treatment mitigated G. lamblia induced histopathological alterations in the intestine and liver tissues with normal normalization of liver enzymes level. Vitamin D treated mice showed significantly lower IL 17 expression in intestinal sections. Our results underscore the potential therapeutic benefits of Vitamin D in preserving intestinal structure and combating parasitic infections. We believe that Vitamin D can serve as an adjunctive treatment in conjunction primary medications like MTZ for managing giardiasis. However, future studies are needed to determine the underlying mechanisms that mediate the therapeutic effects of Vitamin D.