Abstract
Oleanolic acid (OA), a triterpene that is highly present in olive leaves, has been proposed as a component of functional foods for the prevention of metabolic syndrome, due to its anti-inflammatory activity. We analyzed the effects of OA on inflammatory parameters and signaling proteins in LPS-stimulated THP-1 macrophages. Thus, THP-1 macrophages were incubated with LPS for 48 h after pretreatment with OA at different concentrations. Pretreatment with OA was significantly effective in attenuating IL-6 and TNF-α overproduction induced by LPS in macrophages, and also improved the levels of AMPK-α. We also evaluated the effects of human triglyceride-rich lipoproteins (TRLs) derived from individuals consuming an OA-enriched functional olive oil. For this purpose, TRLs were isolated from healthy adolescents before, 2 and 5 h postprandially after the intake of a meal containing the functional olive oil or common olive oil, and were incubated with THP-1 macrophages. THP-1 macrophages incubated with TRLs isolated at 2 h after the consumption of the OA-enriched olive oil showed significant lower levels of IL-6 compared to the TRLs derived from olive oil. Our results suggest that OA might have potential to be used as a lipid-based formulation in functional olive oils to prevent inflammatory processes underlying metabolic syndrome in adolescents.
Highlights
We evaluated the ability of Oleanolic acid (OA) to attenuate the overproduction of proinflammatory cytokines and to modulate signaling pathways in THP-1 macrophages stimulated by LPS, as well as its activity when forming part of human triglyceride-rich lipoproteins (TRLs) obtained after the intake of an olive oil enriched in the triterpene
The main findings presented here are (i) pretreatment with OA attenuated the LPS-induced overproduction of pro-inflammatory cytokines, especially of IL-6, and tumor necrosis factor-α (TNF-α), in THP-1 macrophages; (ii) levels of AMPK-α were increased by OA in a dose-dependent manner in LPS-stimulated THP-1 macrophages; and (iii) OA-enriched olive oil alleviated the levels of IL-6 and Akt in THP-1 macrophages stimulated with 2 h postprandial TRLs
Pretreatment of THP-1 macrophages with OA attenuated the overproduction of proinflammatory cytokines, especially of IL-6, and enhanced the AMPK-α levels in a dose-dependent manner
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Metabolic syndrome (MetS) is a worrying health public problem that affects approximately 31% of the world population, and it is expected that its prevalence will increase by about 53% by 2035 [1,2]. The International Diabetes Federation defines central obesity as the unique fixed component of MetS [3]. Inadequate control of abdominal obesity and insulin resistance (IR), among others, lead to the development of Type 2
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