Cytotoxic Effects and Production of Cytokines Induced by the Endophytic Paenibacillus polymyxa RNC-D in vitro.

Background: Prominent among all the organisms that have a potential value for the production of new medicines, are endophytes, fungi and bacteria that live inside plants without harming them. In this study, a total lyophilized extract (TLE) of Paenibacillus polymyxa RNC-D was used. The P. polymyxa lineages are known for their capacity to segregate a large number of extracellular enzymes and bioactive substances. Methods: The TLE of Paenibacillus polymyxa RNC-D was tested in cell viability assays for cytotoxicity and cytokine production in BALB/3T3 and J774A.1 cell lineages. Results: A 50% mortality rate of fibroblasts (BALB/3T3) was observed in the 1.171 +/- 0.161 mg/mL and 0.956 +/- 0.112 mg/mL doses after 48 and 72 hours, respectively, as well as a 50% mortality rate of macrophage cells (J774A.1) in the 0.994 +/- 0.170 mg/mL and 0.945 +/- 0.280 mg/mL doses after 48 and 72 hours, respectively. The approximate to 1 mg/mL concentration significantly affected the kinetic of growth in all the measured periods. The extract induced apoptosis and necrosis 24 hours after the approximate to 1 mg/mL concentration in both tested lineages. The treatment with the approximate to 1 mg/mL concentration led to the production of TNF-alpha and IFN-gamma cytokines in 24 hours. IL-12 and IL-10 began to be detected as a result of the treatment with 0.1 mg/mL. However, with the 0.5 mg/mL dose in 24 hours, a significant reduction in IL-10 was observed. Conclusion: Our data suggest that the TLE of P. polymyxa RNC-D modulated the production of cytokines with different patterns of immune response in a dose-dependent way.