Modern lifestyle and diets have been associated with metabolic disorders and an imbalance in the normal gut microbiota. Probiotics are widely known for their health beneficial properties targeting the gut microbial ecosystem. The aim of our study was to evaluate the preventive effect of Lactobacillus kefiri (L. kefiri) administration in a fructose-rich diet (FRD) mice model. Mice were provided with tap water or fructose-added (20% w/v) drinking water supplemented or not with L. kefiri. Results showed that probiotic administration prevented weight gain and epidydimal adipose tissue (EAT) expansion, with partial reversion of the adipocyte hypertrophy developed by FRD. Moreover, the probiotic prevented the increase of plasma triglycerides and leptin, together with the liver triglyceride content. Leptin adipocyte secretion was also improved by L. kefiri, being able to respond to an insulin stimulus. Glucose intolerance was partially prevented by L. kefiri treatment (GTT) and local inflammation (TNFα; IL1β; IL6 and INFγ) was completely inhibited in EAT. L. kefiri supplementation generated an impact on gut microbiota composition, changing Bacteroidetes and Firmicutes profiles. Overall, our results indicate that the administration of probiotics prevents the deleterious effects of FRD intake and should therefore be promoted to improve metabolic disorders.

We have previously addressed that fructose rich diet (FRD) intake for three weeks increases the adipogenic potential of stromal vascular fraction cells from the retroperitoneal adipose tissue (RPAT). We have now evaluated the effect of prolonged FRD intake (eight weeks) on metabolic parameters, number of adipocyte precursor cells (APCs) and in vitro adipogenic potential from control (CTR) and FRD adult male rats. Additionally, we have examined the direct fructose effects on the adipogenic capacity of normal APCs. FRD fed rats had increased plasma levels of insulin, triglyceride and leptin, and RPAT mass and adipocyte size. FACS studies showed higher APCs number and adipogenic potential in FRD RPAT pads; data is supported by high mRNA levels of competency markers: PPARγ2 and Zfp423. Complementary in vitro experiments indicate that fructose-exposed normal APCs displayed an overall increased adipogenic capacity. We conclude that the RPAT mass expansion observed in eight week-FRD fed rats depends on combined accelerated adipogenesis and adipocyte hypertrophy, partially due to a direct effect of fructose on APCs.

Fructose-rich diet (FRD) has been associated with obesity development, which is characterized by adipocytes hypertrophy and chronic low-grade inflammation. Interaction of adipocytes and immune cells plays a key role in adipose tissue (AT) alterations in obesity. We assessed the metabolic and immune impairments in AT in a murine obesity model induced by FRD at different periods. Adult Swiss mice were divided into groups of 6 and 10 weeks of fructose (FRD 6wk, FRD 10wk) or water intake (CTR 6wk, CTR 10wk). FRD induced increased in body weight, epidydimal AT mass, and plasmatic and liver Tg, and impaired insulin sensitivity. Also, hypertrophic adipocytes from FRD 6wk-10wk mice showed higher IL-6 when stimulated with LPS and leptin secretion. Several of these alterations worsened in FRD 10wk. Regarding AT inflammation, FRD mice have increased TNFα, IL-6 and IL1β, and decrease in IL-10 and CD206 mRNA levels. Using CD11b, LY6C, CD11c and CD206 as macrophages markers, we identified for first time in AT M1 (M1a: Ly6C+/-CD11c+CD206- and M1b: Ly6C+/-CD11c+CD206+) and M2 subtypes (Ly6C+/-CD11c-CD206+). M1a phenotype increased from 6 weeks onward, while Ly6C+/- M1b phenotype increased only after 10 weeks. Finally, co-culture of RAW264.7 (monocytes cell line) and CTR or FRD adipocytes showed that FRD 10wk adipocytes increased IL-6 expression in non- or LPS-stimulated monocytes. Our results showed that AT dysfunction got worse as the period of fructose consumption was longer. Inflammatory macrophage subtypes increased depending on the period of FRD intake, and hypertrophic adipocytes were able to create an environment that favored M1 phenotype in vitro.

Adipose tissue (AT) expansion is the result of two processes: hyperplasia and hypertrophy; and both, directly or indirectly, depend on the adipogenic potential of adipocyte precursor cells (APCs). Glucocorticoids (GCs) have a potent stimulatory effect on terminal adipogenesis; while their effects on early stages of adipogenesis are largely unknown. In the present work, we study, in a model of high GC levels, the adipogenic potential of APCs from retroperitoneal AT (RPAT) and its relationship with RPAT mass expansion. We employed a model of hyper-adiposity (30- and 60-day-old rats) due to high endogenous GC levels induced by neonatal treatment with l-monosodium glutamate (MSG). We found that the RPAT APCs from 30-day-old MSG rats showed an increased adipogenic capacity, depending on the APCs’ competency, but not in their number. Analyses of RPAT adipocyte diameter revealed an increase in cell size, regardless of the rat age, indicating the prevalence of a hypertrophic process. Moreover, functional RPAT alterations worsened in 60-day-old rats, suggesting that the hyperplastic AT expansion found in 30-day-old animals might have a protective role. We conclude that GCs chronic excess affects APCs’ adipogenic capacity, modifying their competency. This change would modulate the hyperplastic/hypertrophic balance determining healthy or unhealthy RPAT expansion and, therefore, its functionality.