Diet-induced obesity management: modulation of gut microbiota composition and body weight control after Lactobacillus plantarum IMC 510 administration

Objectives: Obesity, one of the main public health problem, is a multifactorial condition implicating medical, psychiatric, social, behavioural, environmental and genetic factors. The evidence linking the gut bacteria to host metabolism could allow the development of new therapeutic strategies based on gut microbiota modulation to treat or prevent obesity. Related to obesity management an animal model has been used and the first aim of the study was to investigate whether rats fed on Cafeteria diet (high salt, high fat, energy dense foods) develop changes in the gut microbiota compared to rats fed on Standard Chow diet. The second aim was to assess the effect of daily probiotic administration on gut microbiota of rats fed on Standard (CHOW) or Cafeteria diet (CAF). Methods: Thirty-six Wistar male rats were divided into four groups: CHOW rats (control group), and CHOW rats supplemented with probiotics (CHOW+P), CAF rats and CAF rats supplemented with probiotics (CAF+P). Lactobacillus plantarum IMC 510 (Synbiotec S.r.l., Camerino, Italy) was administered once a day (108 cells/die) for 84 days. Microbiota composition was assessed on faecal samples collected at different time points by Real-Time PCR, quantifying the main selected bacterial groups (Bacteroides-Prevotella-Porohyromonas spp., Staphylococcus spp., Clostridium coccoides-Eubacterium rectale group, Lactobacillus spp., Bifidobacterium spp. and Enterobacteriaceae). Rats weight and food consumption were measured every day. Results: The study, on the first step, revealed that the obesity-induced Cafeteria diet, cause an increase in Firmicutes and a decrease in Bacteroidetes levels in obese rats. In the second study step, a Two-Way ANOVA showed a significant difference in body weight among the groups [F(1,28)=5.27; P<0.05] and after 4 days, post-hoc test showed that the average body weight CAF rats began to be significantly higher compared to CHOW rats (P<0.05). After 84 days, CAF+P rats showed 12% of reduction in body weight compared to the CAF counterpart. Cafeteria diet caused a significant decrease in Bacteroidetes-Prevotella-Porphyromonas spp. concentration related to the obesity status, while the probiotic treatment re-equilibrate the level at the end of probiotic administration. On the other hand, the probiotic consumption significantly increased Lactobacillus spp. and Bifidobacterium spp. after 84 days and 3 weeks of follow-up in CAF+P rats compared with CAF group. Discussion: Evidence suggests a complex relationship between the gut microbiota, host’s metabolic pathways, immune system, adipose tissue, genetic factors, and host’s behaviours and diet. Modulation of gut microbiota by probiotic treatment or dietary intervention can affect body weight, influence glucose and fat metabolism, improve insulin sensitivity and reduce chronic systemic inflammation. The probiotic supplements might therefore constitute a valuable support in obesity treatment. Further researches are required to better investigate how probiotic reduce the increase of body weight in CAF+P group of rats.