Oleic acid modulates mRNA expression of liver X receptor (LXR) and its target genes ABCA1 and SREBP1c in human neutrophils

Purpose: Regulation of liver X receptors (LXRs) is essential for cholesterol homeostasis and inflammation. The present study was conducted to determine whether oleic acid (OA) could regulate mRNA expression of LXRα and LXRα-regulated genes and to assess the potential promotion of oxidative stress by OA in neutrophils. Methods: Human neutrophils were treated with OA at different doses and LXR target gene expression, oxidative stress production, lipid efflux and inflammation state were analyzed. Results: We describe that mRNA synthesis of both LXRα and ABCA1 (a reverse cholesterol transporter) was induced by OA in human neutrophils. This fatty acid enhanced the effects of LXR ligands on ABCA1 and LXR expression, but it decreased the mRNA levels of sterol regulatory element-binding protein 1c (a transcription factor that regulates the synthesis of triglycerides). Although OA elicited a slight oxidative stress in the short term (15–30 min) in neutrophils, it is unlikely that this is relevant for the modulation of transcription in our experimental conditions, which involve longer incubation time (i.e., 6 h). Of physiological importance is our finding that OA depresses intracellular lipid levels and that markers of inflammation, such as ERK1/2 and p38 mitogen-activated protein kinase phosphorylation, were decreased by OA treatment. In addition, 200 μM OA reduced the migration of human neutrophils, another marker of the inflammatory state. However, OA did not affect lipid peroxidation induced by pro-oxidant agents. Conclusions: This work presents for the first time evidence that human neutrophils are highly sensitive to OA and provides novel data in support of a protective role of this monounsaturated acid against the activation of neutrophils during inflammation.

Restoration of adipose function in obese, glucose-tolerant men following pioglitazone treatment is associated with CCAAT enhancer-binding protein β upregulation

Obese AT (adipose tissue) exhibits increased macrophage number. Pro-inflammatory CD16+ peripheral monocyte numbers are also reported to increase with obesity. The present study was undertaken to simultaneously investigate obesity-associated changes in CD16+ monocytes and ATMs (AT macrophages). In addition, a pilot randomized placebo controlled trial using the PPAR (peroxisome-proliferator-activated receptor) agonists, pioglitazone and fenofibrate was performed to determine their effects on CD14+/CD16+ monocytes, ATM and cardiometabolic and adipose dysfunction indices. Obese glucose-tolerant men (n=28) were randomized to placebo, pioglitazone (30 mg/day) and fenofibrate (160 mg/day) for 12 weeks. A blood sample was taken to assess levels of serum inflammatory markers and circulating CD14+/CD16+ monocyte levels via flow cytometry. A subcutaneous AT biopsy was performed to determine adipocyte cell surface and ATM number, the latter was determined via assessment of CD68 expression by IHC (immunohistochemistry) and real-time PCR. Subcutaneous AT mRNA expression of CEBPß (CCAAT enhancer-binding protein ß), SREBP1c (sterol-regulatory-element-binding protein 1c), PPAR?2, IRS-1 (insulin receptor substrate-1), GLUT4 (glucose transporter type 4) and TNFa (tumour necrosis factor a) were also assessed. Comparisons were made between obese and lean controls (n=16) at baseline, and pre- and post-PPAR agonist treatment. Obese individuals had significantly increased adipocyte cell surface, percentage CD14+/CD16+ monocyte numbers and ATM number (all P=0.0001). Additionally, serum TNF-a levels were significantly elevated (P=0.017) and adiponectin levels reduced (total: P=0.0001; high: P=0.022) with obesity. ATM number and percentage of CD14+/CD16+ monocytes correlated significantly (P=0.05). Pioglitazone improved adiponectin levels significantly (P=0.0001), and resulted in the further significant enlargement of adipocytes (P=0.05), without effect on the percentage CD14+/CD16+ or ATM number. Pioglitazone treatment also significantly increased subcutaneous AT expression of CEBPß mRNA. The finding that improvements in obesity-associated insulin resistance following pioglitazone were associated with increased adipocyte cell surface and systemic adiponectin levels, supports the centrality of AT to the cardiometabolic derangement underlying the development of T2D (Type 2 diabetes) and CVD (cardiovascular disease).

Desempenho, características de carcaça e expressão de genes em tourinhos alimentados com lipídeos e monensina

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Participação da conexina 32 na fisiopatogênese da doença hepática gordurosa não alcoólica em camundongos

A doença hepática gordurosa não alcoólica (DHGNA) abrange alterações desde esteatose até esteato-hepatite não alcoólica (EHNA), podendo evoluir para fibrose, cirrose e carcinoma hepatocelular. A DHGNA é considerada a doença hepática mais comum na atualidade e com prevalência mundial alarmante. Esta doença caracteriza-se, basicamente, pela deposição de triglicérides nos hepatócitos, podendo evoluir com inflamação e fibrose, e está intimamente associada com resistência à insulina (RI), diabetes mellitus tipo 2 e obesidade. Os hepatócitos representam as principais células hepáticas e se comunicam através de junções do tipo gap, formadas principalmente por conexina 32 (Cx32). Esta proteína apresenta importante função no controle da homeostase tecidual, regulando processos fisiológicos e tem sido associada como agente protetor na hepatocarcinogênese e outros processos patológicos, porem pouco se sabe sobre sua participação na DHGNA. Sendo assim, o objetivo deste trabalho foi avaliar a participação da Cx32 na fisiopatogênese da DHGNA, utilizando camundongos knockout para Cx32 (Cx32-KO) submetidos a uma dieta hiperlipídica deficiente em colina. Foram analisados dados biométricos, histopatológicos, função hepática, RI, citocinas inflamatórias, adipocinas, estresse oxidativo, peroxidação lipídica e a expressão de genes envolvidos na DHGNA. Os animais Cx32-KO apresentaram maior acumulo de triglicérides hepáticos em relação aos animais selvagens e, consequentemente, maior peso absoluto e relativo do fígado. Adicionalmente, apresentaram maior inflamação hepática demonstrado pela exacerbação da citocina TNF-α e supressão da IL-10, maior dano hepatocelular indicado pelo aumento das enzimas AST e ALT, aumento da peroxidação lipídica e alterações na expressão de genes chaves na fisiopatogênese da DHGNA, como SREBP1c. No entanto, não houve diferença nos marcadores histopatológicos, RI e estresse oxidativo hepático. Por fim, os animais Cx32-KO apresentaram maior produção de leptina e adiponectina no tecido adiposo. Todos esses resultados revelam que a Cx32 pode atuar como um agente protetor ao desenvolvimento da DHGNA, sugerindo seu potencial como novo alvo terapêutico

Transcription of liver X receptor is down-regulated by 15-deoxy-Δ12,14-prostaglandin J2 through oxidative stress in human neutrophils

Liver X receptors (LXRs) are ligand-activated transcription factors of the nuclear receptor superfamily. They play important roles in controlling cholesterol homeostasis and as regulators of inflammatory gene expression and innate immunity, by blunting the induction of classical pro-inflammatory genes. However, opposite data have also been reported on the consequences of LXR activation by oxysterols, resulting in the specific production of potent pro-inflammatory cytokines and reactive oxygen species (ROS). The effect of the inflammatory state on the expression of LXRs has not been studied in human cells, and constitutes the main aim of the present work. Our data show that when human neutrophils are triggered with synthetic ligands, the synthesis of LXRα mRNA became activated together with transcription of the LXR target genes ABCA1, ABCG1 and SREBP1c. An inflammatory mediator, 15-deoxy-Δ12,14-prostaglandin J2 (15dPGJ2), hindered T0901317-promoted induction of LXRα mRNA expression together with transcription of its target genes in both neutrophils and human macrophages. This down-regulatory effect was dependent on the release of reactive oxygen species elicited by 15dPGJ2, since it was enhanced by pro-oxidant treatment and reversed by antioxidants, and was also mediated by ERK1/2 activation. Present data also support that the 15dPGJ2-induced serine phosphorylation of the LXRα molecule is mediated by ERK1/2. These results allow to postulate that down-regulation of LXR cellular levels by pro-inflammatory stimuli might be involved in the development of different vascular diseases, such as atherosclerosis.