Control of expression and activity of peroxisome proliferated-activated receptor γ by Annexin A1 on microglia during efferocytosis.

Annexin A1 (AnxA1) is a protein secreted by phagocytic cells which plays a pivotal role on the resolution of inflammation by enhancing phagocytosis carried out by phagocytes. Which factors and intracellular mechanisms are linked to such actions exerted by AnxA1 are yet to be completely understood. In order to investigate such, BV2 microglial cells were transfected with plasmids aimed at down-modulating AnxA1 expression and also treated with exogenous recombinant rAnxA1; gene and protein expression of proliferated-activated receptor γ (PPARγ) and CD36, STAT6 phosphorylation and phagocytosis of apoptotic neurons were investigated. Down-modulating AnxA1 in BV2 cells impaired gene and protein expression of PPARγ, effects reversed by treatment with recombinant AnxA1 (rAnxA1). Lower levels of CD36 were also verified in AnxA1 down-modulated BV2 cells. AnxA1-mediated phagocytosis of apoptotic cells was abrogated due to blockade of PPARγ activation, and in AnxA1 down-modulated cells exogenous AnxA1 failed to exert any effects on phagocytosis. Lower levels of STAT6/pSTAT6 in AnxA1 down-modulated BV2 cells suggest the involvement of this transcription factor with PPARγ and CD36 synthesis and actions. Data here shown suggest that there is a probable connection between AnxA1, PPARγ, and CD36, which must all act in association in order for efferocytosis to occur properly. AnxA1-mediated phosphorylation of STAT6 is probably involved with intracellular pathways involving PPARγ and CD36 actions. These data evidence that PPARγ/CD36 play a role on AnxA1-mediated efferocytosis in microglial cells. SIGNIFICANCE OF THE STUDY: The findings of this work provide evidence that the glucocorticoid-mediated protein annexin A1 modulates PPARγ expression and that PPARγ is important for annexin A1-mediated efferocytosis. Only recently the interaction between these two factors has begun to be explored, and knowledge on associated cell mechanisms are still scarce. Elucidating how annexin A1 and PPARγ interact with one another provides basis for further research aimed at understanding molecular pathways and cell signaling events involved with these factors, expanding existing knowledge on the anti-inflammatory effects of such factors.

Connections of annexin A1 and translocator protein-18 kDa on toll like receptor stimulated BV-2 cells.

BACKGROUND: Annexin A1 (ANXA1) and Translocator Protein-18KDa (TSPO) down-regulate neuroinflammation. We investigated the role of recombinant ANXA1 (rANXA) on TSPO functions on Toll Like Receptor (TLR) activated microglia. METHODS: BV-2 cells (murine microglia), were stimulated by E. coli Lipopolysaccharide (LPS) and treated with rANXA1 in order to measure TSPO expression and inflammatory parameters. Anti-sense ANXA1 and TLR4 and TSPO shRNA, as well as pharmacological treatments, were employed to assess the mechanisms involved. RESULTS: LPS-stimulated BV-2 cells caused overexpression of TSPO, which was inhibited by: pharmacological blockade of TLR4 or TLR4 mRNA silencing; inhibition of myeloid differentiation primary response gene 88 (MyD88) dimerization; or blocking of nuclear factor κB (NF-κB) activation. rANXA1 treatment impaired LPS-induced TSPO upregulation by down-modulating MyD88 and NF-κB signaling; the effect was abolished by WRW4, an antagonist of formyl peptide receptor 2 (FPR2). rANXA1 treatment also downregulated interleukin 1ß (IL-1ß) and tumor necrosis factor-α (TNFα) secretion in LPS-stimulated BV-2 cells. TSPO knockdown in BV-2 cells augmented LPS-induced TNFα secretion and abolished the inhibitory effect of rANXA1 on TNFα secretion evoked by LPS. CONCLUSIONS: exogenous ANXA1 down-modulates LPS-induced TSPO via MyD-88/NF-κB pathways, and constitutive TSPO is pivotal for the control of ANXA1 on TNFα secretion. TSPO actions may be involved with the mechanisms of ANXA1 on inflammatory brain diseases.

Mecanismos de modulação da ANXA1 sobre a função da proteína translocadora (TSPO) em células da glia (OU) Mecanismos de modulação da anexina A1 sobre a função da proteína translocadora em células da glia / Annexin A1 modulation mechanism on the expression of the Translocator Protein (TSPO) in BV2 cells

A inflamação no sistema nervoso central (SNC) está envolvida na gênese de uma série de doenças neurodegenerativas, sendo assim, compreender o processo inflamatório nessas circunstâncias se torna essencial para propor novas abordagens terapêuticas. Sabemos que a Anexina A1 (ANXA1) e o receptor TSPO são dois moduladores importantes da neuroinflamação. Enquanto se sabe que a ANXA1 possui propriedades antiinflamatórias, o papel do TSPO ainda não está esclarecido. Desta forma, este projeto avaliou a atuação da ANXA1 sobre a expressão do TSPO em linhagem de células da microglia (BV2), e sua conexão com o receptor Toll-like receptor-4 (TLR4) em BV2 ativada pelo lipopolisacarídeo de E.coli (LPS). Os resultados obtidos mostram que o tratamento de BV2 com LPS induz a expressão de TSPO, dependente de ativação de TLR4, através das vias da molécula adaptadora do fator de diferenciação mielóide 88 (MyD88) e do fator nuclear κB (NFκB). O tratamento com ANXA1 recombinante induz um perfil antiinflamatório em células BV2 estimuladas com LPS, por reduzir a secreção de citocinas proinflamatórias e, ao mesmo tempo, aumentar secreção de citocinas antiinflamatórias. A exposição com ANXA1 ainda impede o aumento da expressão de TSPO induzida pelo LPS. Mostramos também que esta ação da ANXA1 é dependente da interação com o receptor de peptídeo formilado (FPR2). Adicionalmente, o silenciamento de TSPO em células BV2 predispõe essas células a um perfil ativado exacerbando a secreção do fator de necrose tumoral (TNFα) em resposta ao LPS, o que não pode ser revertido pelo tratamento com ANXA1 recombinante. Em conjunto, os resultados expõe a relação existente entre ANXA1 e TSPO em micróglia ativada pelo LPS, mostrando que a ANXA1 9 modula negativamente a expressão do TSPO. Ademais, o silenciamento de TSPO inibiu a fagocitose de neurônios apoptóticos, o que ainda sugere a participação do TSPO na eferocitose

Inflammation in the Central Nervous System (CNS) is involved in the genesis of a number of neurodegenerative diseases, so understanding the inflammatory process in these circumstances is essential to proposal new therapeutic approaches. We know that Annexin A1 (ANXA1) and the TSPO receptor are two important modulators of neuroinflammation. While it is known that ANXA1 has anti-inflammatory properties, the role of TSPO has not yet been clarified. Thus, this project evaluated the interference of ANXA1 on the expression of TSPO in microglia cell line (BV2), and its connection with the Toll-like receptor-4 receptor (TLR4) in BV2 activated by E. coli lipopolysaccharide LPS). The results show that the treatment of BV2 with LPS induces the expression of TSPO, dependent on activation of TLR4, through the pathways of the adapter molecule of myeloid differentiation factor 88 (MyD88) and nuclear factor κB (NFκB). Treatment with recombinant ANXA1 induces an anti-inflammatory profile in LPS-stimulated BV2 cells, by reducing the secretion of proinflammatory cytokines and, at the same time, increasing secretion of anti-inflammatory cytokines. Exposure with ANXA1 still prevents the increase of LPS-induced TSPO expression. We also show that this action of ANXA1 is dependent on the interaction with the formylated peptide receptor (FPR2). In addition, TSPO silencing in BV2 cells predisposes these cells to an activated profile exacerbating secretion of tumor necrosis factor (TNFα) in response to LPS, which can not be reversed by treatment with recombinant ANXA1. Together, the results show the relationship between ANXA1 and TSPO in LPS activated microglia, showing that ANXA1 negatively modulates TSPO 11 expression. In addition, TSPO silencing inhibited the phagocytosis of apoptotic neurons, which still suggests the participation of TSPO in eferocytosis

Determination of low levels of benzodiazepines and their metabolites in urine by hollow-fiber liquid-phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

In this study, it is shown a method for the determination of benzodiazepines and their main metabolites in urine samples by hollow-fiber liquid-phase microextraction (LPME) in the three-phase mode. Initially, the hydrolysis step was performed using 100 µL of sodium acetate 2.0 mol/L buffer solution (pH 4.5), 25 µL of ß-glucuronidase enzyme and incubation for 90 min at 55 °C. In parallel with hydrolysis, the LPME fiber (9 cm) was prepared. Its pores were filled with a mixture of dihexyl ether: 1-nonanol (9:1). Afterwards, a solution of 3.0 mol/L of HCl was introduced into the lumen of the fiber (acceptor phase). After hydrolysis, the fiber was submersed in the alkalinized urine (pH 10) containing 10% NaCl. Samples were then submitted to orbital shaking (2400 rpm) for 90 min. The acceptor phase was later withdrawn from the fiber, dried and the residue derivatized with trifluoroacetic anhydride (TFAA) for 10 min at 60 °C with further addition of N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide containing 1% tert-butyldimethylchlorosilane (MTBSTFA) for 45 min at 90 °C followed by determination by gas chromatography-mass spectrometry (GC-MS). The calibration curves obtained showed linearity over the specified range, with a similar sensitivity to traditional techniques and a higher detection capability compared to most of the miniaturized methods described in the literature. The method has been developed and successfully validated and applied to urine samples from real cases of benzodiazepines intake.

Hollow-fiber liquid-phase microextraction of amphetamine-type stimulants in human hair samples.

A fast method was optimized and validated in order to quantify amphetamine-type stimulants (amphetamine, AMP; methamphetamine, MAMP; fenproporex, FPX; 3,4-methylenedioxymethamphetamine, MDMA; and 3,4-methylenedioxyamphetamine, MDA) in human hair samples. The method was based in an initial procedure of decontamination of hair samples (50 mg) with dichloromethane, followed by alkaline hydrolysis and extraction of the amphetamines using hollow-fiber liquid-phase micro extraction (HF-LPME) in the three-phase mode. Gas chromatography-mass spectrometry (GC-MS) was used for identification and quantification of the analytes. The LoQs obtained for all amphetamines (around 0.05 ng/mg) were below the cut-off value (0.2 ng/mg) established by the Society of Hair Testing (SoHT). The method showed to be simple and precise. The intra-day and inter-day precisions were within 10.6% and 11.4%, respectively, with the use of only two deuterated internal standards (AMP-d5 and MDMA-d5). By using the weighted least squares linear regression (1/x²), the accuracy of the method was satisfied in the lower concentration levels (accuracy values better than 87%). Hair samples collected from six volunteers who reported regular use of amphetamines were submitted to the developed method. Drug detection was observed in all samples of the volunteers.