EFFECTS OF LACTICASEIBACILLUS RHAMNOSUS GG IN PROBIOTIC AND POSTBIOTIC FORMS ON SHORT-CHAIN FATTY ACIDS AND IMMUNOMETABOLIC MARKERS IN AN ANIMAL MODEL OF OBESITY

Short-chain fatty acids (SCFAs) are gut microbiota metabolites involved in immune and metabolic regulation. Consequently, probiotics and postbiotics have been investigated as potential modulators of these immune processes. To evaluate the effects of Lacticaseibacillus rhamnosus GG in both probiotic and postbiotic forms on SCFAs (acetate, propionate, and butyrate), cytokines (IL-4 and IL-5), and metabolic parameters (glucose and triglycerides) in Wistar rats with diet-induced obesity. The study was approved by the Ethics Committee on Animal Use of the State University of Campinas – CEUA/UNICAMP (protocol 6118-1/2022). Forty 10-week-old male Wistar rats were used, distributed into four groups (n=10): Control, Model, Postbiotic, and Probiotic. Animals in the Control group received the AIN-93M diet, while animals in the other groups received a modified high-fat diet. Additionally, L. rhamnosus GG was administered as a postbiotic and a probiotic at concentrations of 10⁷ n-AFU/g and 10⁷ AFU/g, respectively, resuspended in 2 mL of skim milk via gavage. Acetate, propionate, and butyrate levels were determined, as well as IL-4, IL-5, glucose, and triglycerides. Data were expressed as median and interquartile range. The Kruskal-Wallis and Dunn tests were used, along with linear regression adjusted for final weight, considering p<0.05. No significant differences were observed between the groups for acetate (p=0.240), propionate (p=0.262), or butyrate (p=0.086). Regarding IL-4, the Postbiotic group showed a lower level (5.27 pg/mL) compared to the Model group (14.51 pg/mL) (p=0.049). For IL-5, no significant difference was observed between the Postbiotic and Model groups (p=0.065). In the glucose analysis, the Postbiotic group showed a concentration of 177.0 mg/dL, compared to 247.5 mg/dL in the Control group (p=0.004). In the regression adjusted for final weight, negative coefficients were observed for the Model (β=−67.36; p=0.002), Postbiotic (β=−98.03; p<0.001), and Probiotic (β=−58.66; p=0.008) groups. For triglycerides, concentrations were 103.5 mg/dL in the Model group, 100.0 mg/dL in the Postbiotic group, and 135.0 mg/dL in the Probiotic group, with β=−109.11 (p<0.001) for the Postbiotic group and β=−62.36 (p=0.009) for the Probiotic group. Previous studies have suggested that viable and inactivated L. rhamnosus GG may influence metabolic outcomes and gut microbiota composition in obesity models (de Oliveira Melo et al., 2023; Arellano-García et al., 2025). Interventions with L. rhamnosus GG in both forms did not promote statistically significant changes in the evaluated SCFAs. The postbiotic showed a reduction in IL-4 and favorable changes in metabolic parameters, while both formulations were associated with lower glucose and triglyceride levels in the adjusted analysis.