Supplementation with Lactobacillus reuteri or L. acidophilus reduced intestinal shedding of Cryptosporidium parvum oocysts in immunodeficient C57BL/6mice

The effect of L. acidophilus supplementation to reduce fecal shedding of Cr yptosporidium parvum oocysts was compared to L. reuteri using C57BL/6 femal e mice immunosuppressed by murine leukemia virus (strain LP-BM5) inoculatio n. After 12 weeks post LP-BM5 inoculation, 15 immunosuppressed mice each we re randomly assinged to one of the following treatment groups: historical c ontrol (group A), LP-BM5 control (group B), C. parvum (group C), L. reuteri plus C. parvum (group D) or L, acidophilus plus C. parvum (group E). Mice were pre-fed the L. reuteri or L. acidophilus bacteria strains daily for 13 days, challenged with C. parvum oocysts and thereafter fed the specified L actobacillus regimens daily during the experimental period. Animals supplem ented with L. reuteri shed fewer (p<0.05) oocysts on day-7 post C. parvum c hallenge compared to controls. Mice supplemented with L. acidophilus also s hed fewer (p<0.05) oocysts on days 7 and 14 post-challenge compared to cont rols. Overall, Lactobacillus supplementation reduced C. parvum shedding in the feces but failed to suppress the production of T-helper type 2 cytokine s [interleukin-4 (IL-4), IL-8)] which are associated with immunosuppression . Additionally, Lactobacillus supplementation did not restore T-helper type 1 cytokines (interleukin-2 (IL-2) and gamma interferon (IFN-gamma), which are required for recovery from parasitic infections. Altered T-helper types 1 and 2 cytokine production as a consequence of immunodysfunction permitte d the development of persistent cryptosporidiosis while mice with intact im mune system were refractory to infection with C, parvum. Reduction in shedd ing of oocysts observed in the Lactobacillus supplemented mice during demin ished IL-2 and IFN-gamma production may be mediated by factors released int o the intestinal lumen by the Lactobacillus and possibly other host cellula r mechanisms. These observations suggest that L. reuteri or L. acidophilus can reduce C. parvum parasite burdens in the intestinal epithelium during c ryptosporidiosis and may serve potential benefits as probiotics for host re sistance to intestinal parasitic infections. L. acidophilus was more effica cious in reducing fecal shedding than L. reuteri and therefore may also hav e implication in the therapy of cryptosporidiosis during immunosuppressive states including human AIDS.