Effects of probiotic therapy on experimental periodontitis in rats with metabolic syndrome induced by a high-fat diet

The concept of modulating the intestinal microbiota through the use of specific bacteria to improve the host\'s metabolism gained considerable interest in recent years. Some preclinical and clinical studies showed that the use of probiotics (PROB) can be a promising therapeutic/preventive alternative for metabolic syndrome (MS) and periodontal disease (PD). These conditions are closely linked and affect thousands of people around the world. To date, no study has assessed the impact of probiotic therapy on the MS-PD association. The aim of this study was to evaluate potential effects of the probiotic agent Bifidobacterium animalis subsp. lactis HN019 (B. lactis HN019) in the development of experimental periodontitis associated or not with the comorbidities of MS in Wistar Hannover rats. 96 male Wistar Hannover rats were randomly divided according to the received food protocol: high-fat high-calorie ration for the induction of MS and common ration (C - control groups). The groups were subdivided according to the presence or absence of PD (ligature-induced) and the administration or not of probiotic therapy: i) C group (rats fed with a standard diet, n = 12); ii) CP group (rats fed with a standard diet and that received PROB - n = 12); iii) PD (rats fed with a standard diet and with PD - n = 12); iv); PDP group (rats fed with a standard diet, with PD and that received PROB - n = 12); v) MS group (rats fed a high-fat high-calorie diet, n = 12); vi) MSP group (rats fed with a high-fat high-calorie diet and that received PROB administration, n = 12); vii) MSPD group (rats fed with a high-fat high-calorie diet and with PD, n = 12); viii) MSPDP group (rats fed with a high-fat high-calorie diet with PD and that received PROB therapy, n = 12). SM was induced through the consumption of high calorie ration (60% fat). The consumption of the high calorie diet started 8 weeks before the probiotic therapy and remained until the day the animals were euthanized. On the 14th week of the study, PD was induced by placing ligatures on the lower first molars of each animal for 14 days. The probiotic strain B. lactis HN019 was added daily to the water of the animals for 8 weeks, in the dosage of 10 ¹º Colony Forming Units. All animals were euthanized 16 weeks after the beginning of the experiment. Metabolic (blood glucose, insulin, insulin resistance, lipid profile, fatty acids, and glucose tolerance) and anthropometric parameters (body mass index (BMI), abdominal circumference and weight); Blood pressure (measured by invasive method at the time of euthanasia); Levels of pro and anti-inflammatory cytokines in the gingival tissue using enzymatic immunoassays (ELISA and Luminex®); Activity of enzymes involved in oxidative stress , catalase (CAT) and myeloperoxidase (MPO), using ELISA tests; Alveolar bone level (ABL), bone volume (BV) and bone porosity (BP) using computerized microtomography; Descriptive histological analysis of hemimandible; Intestinal microbiological analysis (qRT-PCR), were evaluated. The data were statistically analyzed (p<0.05). The MS, MSP, MSPD, and MSPDP groups showed a significant increase in final weight, BMI, and abdominal circumference when compared to group C (p<0.05). The MS group also showed an increase in the blood glucose, HOMA-IR, total cholesterol, triglycerides, and fatty acids parameters when compared to group C (p<0.05). Probiotic therapy was able to attenuate the dyslipidemia present in animals with MS since the serum levels of total cholesterol in the MSPDP group were statistically lower when compared to those in the MSPD group. Likewise, MSPDP and MSP showed lower triglyceride rates when compared to the MSPD and MS groups, respectively (p<0.05). The data from the microtomographic analysis demonstrated the impact of PROB in reducing the severity of PD and the effects of MS in worsening PD. The MSPD and MSPDP groups showed a significantly higher ABL (p<0.05) than those of the PD and PDP groups, respectively. The MSPD group showed lower BV and higher BP when compared to the PD groups (p<0.05). The MSPDP and PDP groups showed lower ABL and lower BP when compared to the MSPD and PD groups, respectively (p<0.05). The immunoenzymatic analysis showed higher levels of IL-1&beta; and a higher RANKL / OPG ratio in the MSPD group when compared to the MSPDP group (p<0.05). The PDP group showed lower levels of TNF-&alpha; and IL-6 when compared to the PD group (p<0.05). Besides, the MSPD group showed a higher RANK-L / OPG ratio when compared to the PD group, as well as a lower concentration of TGF-&beta; (p<0.05). The animals in the PD and PDP groups showed reduced levels of CAT when compared to group C (p<0.05). When PD was associated with MS, there was a significant reduction in CAT compared to animals with MS alone (p<0.05). For MPO, a downward trend was observed in the comparisons of the PDP and PD, MSP and MS groups; and MSPDP and MSPD. The MPO values in the present study were significantly higher in the PD and MS groups when compared to C group (p<0.05) The microbiological analysis revealed a greater change in the proportion of Firmicutes and Bacteroidetes for the SMP group when compared to group C (p<0.05). The SM group showed a greater reduction in Lactobacilos and Bifidobacterium throughout the experiment when compared to group C (p<0.05). The use of PROB promoted a greater reduction of Bacteroidetes in the MSPDP group when compared to the MSPD group (p<0.05). Considering the limitations of the present study, it is possible to conclude that B. lactis HN019 reduced the severity of PD and modulated immunoinflammatory parameters in the periodontal tissues in rats with or without MS. Furthermore B. lactis HN019 attenuated dyslipidemia in rats with MS. (AU)