Limits...
Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages.

Lanuti M, Talamonti E, Maccarrone M, Chiurchiù V - PLoS ONE (2015)

Bottom Line: However, its physiological role and underlying mechanism remain unclear.Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects.Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

View Article: PubMed Central - PubMed

Affiliation: European Center for Brain Research (CERC), IRCCS, Santa Lucia Foundation, Rome, Italy.

ABSTRACT
The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9)-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

No MeSH data available.


Related in: MedlinePlus

Effect of GPR55 activation on NFAT transcription factor members.Human THP-1 macrophages (MΦ) were left untreated or were treated for 18 h with 100 μg/ml oxLDL to generate foam cells (FC). FC were treated for 24h with O-1602, and pre-treated or not with CDB. mRNA analysis of NFAT members was performed by qRT-PCR. Data are shown as mean ± SD of three independent experiments, each in duplicate. *p<0.05 versus FC; #p<0.05 versus FC+O-1602.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4430319&req=5

pone.0126839.g005: Effect of GPR55 activation on NFAT transcription factor members.Human THP-1 macrophages (MΦ) were left untreated or were treated for 18 h with 100 μg/ml oxLDL to generate foam cells (FC). FC were treated for 24h with O-1602, and pre-treated or not with CDB. mRNA analysis of NFAT members was performed by qRT-PCR. Data are shown as mean ± SD of three independent experiments, each in duplicate. *p<0.05 versus FC; #p<0.05 versus FC+O-1602.

Mentions: Besides bearing a disrupted cholesterol homeostasis, oxLDL-induced FC are also characterized by an overt proinflammatory phenotype. Thus, we next evaluated the possible impact of GPR55 activation on the production of inflammatory cytokines. At the transcriptional level, FC expressed higher levels of IL-12, TNF-α and IL-10 compared to MΦ (Fig 3A). When cells were treated with O-1602, TNF-α mRNA levels were further increased, whereas those of IL-10 significantly decreased. Instead, IL-12 transcription was hardly affected by GPR55 activation. Next, protein expression of IL-10 and TNF-α was evaluated by means of flow cytometry. Intracellular cytokine staining revealed a ∼1.4-fold decrease in IL-10 production (Fig 3B), and a parallel ∼1.3-fold increase in TNF-α (Fig 3C) in FC treated with O-1602, and these effects were significantly reverted by CBD, further supporting the proinflammatory nature of GPR55 in these cells. OxLDL-activated FC also produce extracellular matrix-degrading metalloproteinases (MMP), which are involved in atherosclerotic plaque instability. Thus, we assessed the possible effect of GPR55 activation on MMP-9 production by means of zymography. Interestingly, we found that O-1602-treated FC supernatants had higher MMP-9 activity than those of untreated FC, and that such an enzyme activity was significantly reverted by CBD (Fig 4). Since GPR55 downstream signaling engages Rho, which then stimulates intracellular calcium release and nuclear translocation of the nuclear factor of activated T-cells (NFAT) [35], we sought to investigate whether GRP55 could modulate gene expression of the main members of NFAT in FC. To this aim, we analyzed mRNA levels of NFAT-c1, NFAT-c2 and NFAT5, which are all largely expressed in macrophages [36], upon GPR55 activation or blockade. qRT-PCR analysis showed that only NFAT-c2 mRNA levels were upregulated by GPR55 activation, an effect that was specifically blunted by receptor antagonism with CBD (Fig 5). No changes in NFAT-c1 and NFAT5 expression were observed upon GPR55 activation, suggesting that the proinflammatory effects of GPR55 shown in this study could be mediated by the NFAT-c2 transcription factor.


Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages.

Lanuti M, Talamonti E, Maccarrone M, Chiurchiù V - PLoS ONE (2015)

Effect of GPR55 activation on NFAT transcription factor members.Human THP-1 macrophages (MΦ) were left untreated or were treated for 18 h with 100 μg/ml oxLDL to generate foam cells (FC). FC were treated for 24h with O-1602, and pre-treated or not with CDB. mRNA analysis of NFAT members was performed by qRT-PCR. Data are shown as mean ± SD of three independent experiments, each in duplicate. *p<0.05 versus FC; #p<0.05 versus FC+O-1602.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430319&req=5

pone.0126839.g005: Effect of GPR55 activation on NFAT transcription factor members.Human THP-1 macrophages (MΦ) were left untreated or were treated for 18 h with 100 μg/ml oxLDL to generate foam cells (FC). FC were treated for 24h with O-1602, and pre-treated or not with CDB. mRNA analysis of NFAT members was performed by qRT-PCR. Data are shown as mean ± SD of three independent experiments, each in duplicate. *p<0.05 versus FC; #p<0.05 versus FC+O-1602.
Mentions: Besides bearing a disrupted cholesterol homeostasis, oxLDL-induced FC are also characterized by an overt proinflammatory phenotype. Thus, we next evaluated the possible impact of GPR55 activation on the production of inflammatory cytokines. At the transcriptional level, FC expressed higher levels of IL-12, TNF-α and IL-10 compared to MΦ (Fig 3A). When cells were treated with O-1602, TNF-α mRNA levels were further increased, whereas those of IL-10 significantly decreased. Instead, IL-12 transcription was hardly affected by GPR55 activation. Next, protein expression of IL-10 and TNF-α was evaluated by means of flow cytometry. Intracellular cytokine staining revealed a ∼1.4-fold decrease in IL-10 production (Fig 3B), and a parallel ∼1.3-fold increase in TNF-α (Fig 3C) in FC treated with O-1602, and these effects were significantly reverted by CBD, further supporting the proinflammatory nature of GPR55 in these cells. OxLDL-activated FC also produce extracellular matrix-degrading metalloproteinases (MMP), which are involved in atherosclerotic plaque instability. Thus, we assessed the possible effect of GPR55 activation on MMP-9 production by means of zymography. Interestingly, we found that O-1602-treated FC supernatants had higher MMP-9 activity than those of untreated FC, and that such an enzyme activity was significantly reverted by CBD (Fig 4). Since GPR55 downstream signaling engages Rho, which then stimulates intracellular calcium release and nuclear translocation of the nuclear factor of activated T-cells (NFAT) [35], we sought to investigate whether GRP55 could modulate gene expression of the main members of NFAT in FC. To this aim, we analyzed mRNA levels of NFAT-c1, NFAT-c2 and NFAT5, which are all largely expressed in macrophages [36], upon GPR55 activation or blockade. qRT-PCR analysis showed that only NFAT-c2 mRNA levels were upregulated by GPR55 activation, an effect that was specifically blunted by receptor antagonism with CBD (Fig 5). No changes in NFAT-c1 and NFAT5 expression were observed upon GPR55 activation, suggesting that the proinflammatory effects of GPR55 shown in this study could be mediated by the NFAT-c2 transcription factor.

Bottom Line: However, its physiological role and underlying mechanism remain unclear.Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects.Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

View Article: PubMed Central - PubMed

Affiliation: European Center for Brain Research (CERC), IRCCS, Santa Lucia Foundation, Rome, Italy.

ABSTRACT
The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9)-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

No MeSH data available.


Related in: MedlinePlus