Effects of Pine Bark Extract Administered to Immunosuppressed Adult Mice Infected with Cryptosporidium parvum

The treatment of cryptosporidiosis using pine bark extract (Pycnogenol®) in immunosuppressed adult C57BL/6N mice infected with Cryptosporidium parvum was investigated. Five groups of 10 mice/group were used. Groups 1, 2, 3, and 5 served as normal, toxicity, placebo, and positive controls, respectively. Mice in groups 2—5 were immunosuppressed with dexamethasone phosphate administered ad libitum in drinking water at a dosage level of 12 μg/ml. Mice in groups 3—5 were inoculated per os with 10⁶C. parvum oocysts on the day immunosuppression was started. Mice in groups 2 and 4 were treated by administering Pycnogenol® orally at 30 mg/kg/day. In group 4, Pycnogenol® was first administered on day 3 postinoculation. Of the four groups of mice immunosuppressed with DEXp (groups 2—5), the two groups treated with Pycnogenol® (groups 2 and 4) had no premature deaths. The other two groups (groups 3 and 5) had 3 and 4 mice die, respectively, before the experiment ended. Consequently, Pycnogenol® was judged to be non-toxic at the dosage level used and even afforded mice some positive health benefits. Fecal oocyst shedding in groups 3—5 was initially detected on day 3 postinoculation. These mice continued to shed oocysts throughout the duration of the 28-day experiment. Oocyst shedding intensities were greater in group 3 and 5 than in group 4. However, histological examination of infected intestinal tissues in groups 3—5 revealed no significant difference with regard to parasite colonization and villus/crypt (V/C) length ratios. As a result, Pycnogenol® was determined to be therapeutically effective against C. parvum at 30 mg/kg/day only when measured by fecal oocyst shedding intensity. There was no effect on parasite tissue colonization and V/C ratios in infected mice. We conclude that Pycnogenol® is a useful dietary supplement for C. parvum-infected patients by affording some positive health benefits, significantly reduces fecal oocyst shedding, but does not decrease parasite colonization of intestinal tissue.