The impact of probiotic administration in vivo on peritoneal mouse macrophages infected by Leishmania amazonensis ex vivo.

Background: The microbiome is fundamental in the host's immunobiology and dysbiosis leads to pathological conditions, potentially affecting parasitic diseases.

Objectives: To investigate how oral probiotics affect infection and antiparasitic treatment of Leishmania in macrophages.

Methods: Swiss mice were orally treated with 109 colony forming units (CFU) multi- or single-strain probiotic formulations (PB8, Bifilac), their peritoneal mouse macrophages (PMMs) were obtained and infected ex vivo with L. amazonensis amastigotes. The effects of prior probiotic administration on ex vivo infection and treatment responses to 1 µM miltefosine and N 6-methyltubercidin were evaluated. Flow cytometry measured the inflammatory mediator release in the supernatant of the PMMs.

Findings and main conclusions: PB8 or Bifilac administration significantly reduced (p < 0.05) ex vivo infection of PMMs from male mice by 27% and 12%, respectively. No gender-dependent effect of probiotics was observed. No improved antiparasitic activity of 1 µM miltefosine or N 6-methyltubercidin was observed in probiotic-treated PMMs. Ex vivo Leishmania infection stimulated tumour necrosis factor (TNF), MCP-1, and interleukin-6 (IL-6) production by PMMs (p < 0.05). A trend of increase was recorded with elevated levels of TNF and IL-6 in PB8-treated male groups (around 43 and 52%, respectively) but were not statistically significant. Collectively, probiotic treatment of mice influences Leishmania infection in PMMs. Clinical applications in leishmaniasis warrant further studies.