Supernatants from Newly Isolated Lacticaseibacillus paracasei P4 Ameliorate Adipocyte Metabolism in Differentiated 3T3-L1 Cells

<b>Background:</b><i>Lacticaseibacillus paracasei</i> (<i>L. paracasei</i>) strains and their postbiotics show potential for managing metabolic disorders such as diabetes and obesity. Two newly isolated <i>L. paracasei</i> strains, M2.1 and P4, were yielded from <i>Formica rufa</i> anthills in Sinite Kamani National Park, Bulgaria. Their metabolic effects on mature 3T3-L1 adipocytes were investigated. <b>Methods:</b> Mature 3T3-L1 adipocytes were treated for 24 h with 10% (<i>v</i>/<i>v</i>) cell-free supernatants (CFSs) of M2.1 or P4. Two experimental (M2.1, P4) and two control groups (mature, untreated adipocytes and mature adipocytes, treated with 10% (<i>v</i>/<i>v</i>) MRS broth) were analyzed for intracellular lipid accumulation, glucose uptake, and the mRNA expression of lipid metabolism and beta-oxidation-related genes. Fold changes in gene expression were assessed using RT-qPCR. <b>Results:</b> Both M2.1 and P4 CFSs enhanced glucose uptake by over 30% compared to the control. P4 demonstrated a more favorable effect by significantly upregulating adipose triglyceride lipase-patatin-like phospholipase domain containing 2, adiponectin, and peroxisomal beta-oxidation enzymes-acyl-coenzyme A oxidase 1, palmitoyl. Intracellular lipid accumulation increased only with M2.1, while P4 supported improved lipid turnover without promoting excessive lipid storage or lipolysis. <b>Conclusions:</b> P4 CFS exhibits the potential to improve adipocyte metabolism by enhancing glucose uptake, promoting beta-oxidation, and increasing adiponectin expression, offering a promising strategy for managing metabolic dysfunctions.