Influence of Lactobacillus reuteri on Porphyromonas gingivalis infection in an invertebrate model

Abstract

Periodontal disease is a multifactorial chronic inflammation, which the main etiological factor is the association of Gram-negative bacteria, as Porphyromonas gingivallis, and host susceptibility. New therapies involving the host response modulation have been tested, and recent studies demonstrate that some probiotics, as Lactobacillus reuteri, are beneficial to oral health, decreasing the indicators of periodontal disease. The objective of this study is to analyze the effects of L. reuteri alive, dead and his products (sobrenadant), on P. gingivallis in a Galleria mellonella model. Before the study of the interaction between P. gingivallis and L. reuteri, we will analyze the susceptibility of G. mellonella to the infection by both microorganisms, to determine the sub-lethal concentration to be used in the experiments. For the survival analysis of G. mellonella, suspensions of P. gingivallis and/ or L. reuteri will be injected in larvae. The animals will be placed in Petri dishes and incubated at 37°C in the dark. Daily, for 7 days, the number of dead larvae will be recorded. For evaluation of hemocyte density, three larvae in each group will be incubated at 37°C for 3 hours after infection. Next, the hemolymph will be removed, and hemocytes will be counted using a hemocytometer. For survival analysis of G. mellonella, survival curves will be constructed and differences will be estimated by the log-rank method (Mantel- Cox test). For statistical analyses of hemocytes, number ANOVA or Kruskal-Wallis test will be used, depending on the normality of the sample. A level of significance of 5% will be adopted for all tests. (AU)