Background and purpose: The phytocannabinoid, Δ9‐tetrahydrocannabivarin (THCV), can block cannab... more Background and purpose: The phytocannabinoid, Δ9‐tetrahydrocannabivarin (THCV), can block cannabinoid CB1 receptors. This investigation explored its ability to activate CB2 receptors, there being evidence that combined CB2 activation/CB1 blockade would ameliorate certain disorders.Experimental approach: We tested the ability of THCV to activate CB2 receptors by determining whether: (i) it inhibited forskolin‐stimulated cyclic AMP production by Chinese hamster ovary (CHO) cells transfected with human CB2 (hCB2) receptors; (ii) it stimulated [35S]GTPγS binding to hCB2 CHO cell and mouse spleen membranes; (iii) it attenuated signs of inflammation/hyperalgesia induced in mouse hind paws by intraplantar injection of carrageenan or formalin; and (iv) any such anti‐inflammatory or anti‐hyperalgesic effects were blocked by a CB1 or CB2 receptor antagonist.Key results: THCV inhibited cyclic AMP production by hCB2 CHO cells (EC50= 38 nM), but not by hCB1 or untransfected CHO cells or by hC...
Introduction: CR4056 is a novel imidazoline-2 receptor ligand endowed with low affinity MAO inhib... more Introduction: CR4056 is a novel imidazoline-2 receptor ligand endowed with low affinity MAO inhibition properties. Objectives: Aims of this study was to test with different methods the anti-nociceptive effect of CR4056 in rat models of neuropathic pain, i.e. Bortezomib(Btz)-induced neuropathic pain, streptozotocin-induced diabetes and chronic constriction injury (CCI). In the Btz model (0.20mg/kg 3qwx8 iv) and in the experimental diabetes model CR4056 was administered at 6-60mg/kg po. In the CCI mononeuropathy model CR4056 was administered at 10-80 mg/kg po. Nerve conduction velocity (NCV), dynamic, Randall-Selitto, plantar and von Frey tests were used to assess the effect of CR4056. Results: After 8 weeks of treatment, Btz induced a severe reduction in NCV and this impairment was not reversed by CR4056. The behavioral assessment showed a significant mechanical allodynia in rats treated wit Btz for 8 wks and the daily administration of CR4056 significantly reduced this condition. This effect was persistent along the entire period of administration after Btz withdrawal (2 weeks). In the models of streptozotocin-induced diabetes and CCI, treatment with CR4056 significantly attenuated mechanical and thermal hyperalgesia, while CR4056 had no effect on mechanical allodynia in both experimental models. Conclusions: These results promote the use of CR4056 as a potential treatment in the chronic neuropathic pain therapy.
Heme is a prosthetic group in a large number of essential proteins that have a pivotal role in ox... more Heme is a prosthetic group in a large number of essential proteins that have a pivotal role in oxygen transport, storage and electron shuttling. High amounts of free heme are associated with pathological states. Recently, it has been suggested that activation of Toll-like receptor 4 (TLR4) is one of the ways in which the ‘danger signal’ of free heme is detected. Here, we examine the biochemical basis of the modulation of the TLR4 pathway by hemin (iron(III)-protoporphyrin IX) and its metabolic, oxidated derivative coprohemin (iron(III)-coproporphyrin I). High concentrations of hemin (50 μM) triggered TLR4-mediated IL-8 production in the human HEK293/TLR4 cell line in the absence of the co-receptors CD14 and MD-2; the latter an essential co-receptor for TLR4 activation by endotoxin. Hemin and endotoxin have additive effects when co-administrated to HEK/TLR4 cells, suggesting that hemin and endotoxin activate TLR4 by different mechanisms. Coprohemin, in contrast to hemin, is unable to...
Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the co... more Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol−ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.
The antiin¯ammatory activity of synthetic cannabinoid nabilone in the rat model of carrageenanind... more The antiin¯ammatory activity of synthetic cannabinoid nabilone in the rat model of carrageenaninduced acute hindpaw in¯ammation was compared with that of the endocannabinoid palmitoylethanolamide and the nonsteroidal antiin¯ammatory drug indomethacin. 2 Preliminary experiments in rats used a tetrad of behavioural tests, speci®c for tetrahydrocannabinol-type activity in the CNS. These showed that the oral dose of nabilone 2.5 mg kg 71 had no cannabinoid psychoactivity. 3 Intraplantar injection of carrageenan (1% w v 71) elicited a time-dependent increase in paw volume and thermal hyperalgesia. 4 Nabilone (0.75, 1.5, 2.5 mg kg 71 , p.o.), given 1 h before carrageenan, reduced the development of oedema and the associated hyperalgesia in a dose-related manner. Nabilone 2.5 mg kg 71 , palmitoylethanolamide 10 mg kg 71 and indomethacin 5 mg kg 71 , given p.o. 1 h before carrageenan, also reduced the in¯ammatory parameters in a time-dependent manner. 5 The selective CB 2 cannabinoid receptor antagonist {N-[(1S)-endo-1,3,3-trimethyl bicyclo [2.2.1]heptan-2yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide} (SR 144528), 3 mg kg 71 p.o. 1 h before nabilone and palmitoylethanolamide, prevented the anti-oedema and antihyperalgesic eects of the two cannabinoid agonists 3 h after carrageenan. 6 Our ®ndings show the antiin¯ammatory eect of nabilone and con®rm that of palmitoylethanolamide indicating that these actions are mediated by an uncharacterized CB 2-like cannabinoid receptor.
The antinociceptive properties of cannabinoids in persistent pain are not fully elucidated. We in... more The antinociceptive properties of cannabinoids in persistent pain are not fully elucidated. We investigated the effect of repeated treatment with the synthetic cannabinoid receptor agonist WIN 55,212-2 on the neuropathic pain induced in rats by chronic constriction of the sciatic nerve. WIN 55,212-2 administered daily throughout the development of neuropathy reversed the hyperalgesia, at a dose (0.1 mg kg À1 , s.c.) that had no effect on the nociceptive responses of either paw contralateral to the sciatic ligation or of animals subjected to sham surgery. At 14 days after injury, the levels of mediators known to be involved in neuropathic pain, such as prostaglandin E2, NO and the neuronal NOS, were increased. Repeated treatment with WIN 55,212-2 abolished these increases. In the light of the current clinical need for neuropathic pain treatments, these findings indicate that cannabinoid agonists, at doses devoid of psychoactive effects, could constitute important compounds for the development of new analgesics.
Palmitoylethanolamide (PEA) is an endogenous lipid that is thought to be involved in endogenous p... more Palmitoylethanolamide (PEA) is an endogenous lipid that is thought to be involved in endogenous protective mechanisms activated as a result of stimulation of inflammatory response. In spite of the well demonstrated anti-inflammatory properties of PEA, its involvement in controlling pain pathways still remains poorly characterized. On this basis, we tested the efficacy of PEA in vivo against a peculiar persistent pain, such as neuropathic one. PEA was administered i.p. to mice with chronic constriction injury of sciatic nerve (CCI) once a day for one week starting the day after the lesion. This therapeutic regimen evoked a relief of both thermal hyperalgesia and mechanical allodynia in neuropathic mice. Various selective receptor antagonists were used in order to clarify the relative contribution of cannabinoid, vanilloid and peroxisome proliferator-activated receptor to PEA-induced effects. The results indicated that CB 1 , PPARc and TRPV1 receptors mediated the antinociception induced by PEA, suggesting that the most likely mechanism might be the so-called ''entourage effect" due to the PEA-induced inhibition of the enzyme catalyzing the endocannabinoid anandamide (AEA) degradation that leads to an enhancement of its tissue levels thus increasing its analgesic action. In addition, the hypothesis that PEA might act through the modulation of local mast cells degranulation is sustained by our findings showing that PEA significantly reduced the production of many mediators such as TNFa and neurotrophic factors, like NGF. The findings presented here, in addition to prove the beneficial effects of PEA in chronic pain, identify new potential targets for analgesic medicine.
Biochemical Characterization of the Effects of the ... Mariapia Colleoni', Barbara Costal, E... more Biochemical Characterization of the Effects of the ... Mariapia Colleoni', Barbara Costal, Enzo Gori' and Angela Santagostino* 'Institute of Pharmacology. Faculty of Sciences MM FF NN, University of Milano. via Vanvitelli 32/A, 1-20129. Milano, and 'Department of Environmental and ...
Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the co... more Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol-ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.
Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyp... more Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyperalgesic compound in a rat model of acute inflammation. We examined whether the CBD antihyperalgesic effect could be mediated by cannabinoid receptor type 1 (CB1) or cannabinoid receptor type 2 (CB2) and/or by transient receptor potential vanilloid type 1 (TRPV1). Rats received CBD (10 mg kg À1 ) and the selective antagonists: SR141716 (N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) for CB1, SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide) for CB2 and capsazepine (CPZ) for TRPV1 receptors. The intraplantar injection of carrageenan in rats induced a time-dependent thermal hyperalgesia, which peaked at 3 h and decreased at the following times. CBD, administered 2 h after carrageenan, abolished the hyperalgesia to the thermal stimulus evaluated by plantar test. Neither SR141716 (0.5 mg kg À1 ) nor SR144528 (3 and 10 mg kg À1 ) modified the CBD-induced antihyperalgesia; CPZ partially at the lowest dose (2 mg kg À1 ) and fully at the highest dose (10 mg kg À1 ) reversed this effect. These results demonstrate that TRPV1 receptor could be a molecular target of the CBD antihyperalgesic action.
Toll-like receptors (TLRs) are the best characterized pattern recognition receptors 1 . Individua... more Toll-like receptors (TLRs) are the best characterized pattern recognition receptors 1 . Individual TLRs recruit diverse combinations of adaptor proteins, triggering signal transduction pathways and leading to the activation of various transcription factors, including nuclear factor kB, activation protein 1 and interferon regulatory factors 2 . Interleukin-2 is one of the molecules produced by mouse dendritic cells after stimulation by different pattern recognition receptor agonists 3-6 . By analogy with the events after T-cell receptor engagement leading to interleukin-2 production, it is therefore plausible that the stimulation of TLRs on dendritic cells may lead to activation of the Ca 21 /calcineurin and NFAT (nuclear factor of activated T cells) pathway. Here we show that mouse dendritic cell stimulation with lipopolysaccharide (LPS) induces Src-family kinase and phospholipase Cc2 activation, influx of extracellular Ca 21 and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. We also show that LPS-induced NFAT activation via CD14 is necessary to cause the apoptotic death of terminally differentiated dendritic cells, an event that is essential for maintaining self-tolerance and preventing autoimmunity 7,8 . Consequently, blocking this pathway in vivo causes prolonged dendritic cell survival and an increase in T-cell priming capability. Our findings reveal novel aspects of molecular signalling triggered by LPS in dendritic cells, and identify a new role for CD14: the regulation of the dendritic cell life cycle through NFAT activation. Given the involvement of CD14 in disease, including sepsis and chronic heart failure 9,10 , the discovery of signal transduction pathways activated exclusively via CD14 is an important step towards the development of potential treatments involving interference with CD14 functions.
Background and purpose: The phytocannabinoid, Δ9‐tetrahydrocannabivarin (THCV), can block cannab... more Background and purpose: The phytocannabinoid, Δ9‐tetrahydrocannabivarin (THCV), can block cannabinoid CB1 receptors. This investigation explored its ability to activate CB2 receptors, there being evidence that combined CB2 activation/CB1 blockade would ameliorate certain disorders.Experimental approach: We tested the ability of THCV to activate CB2 receptors by determining whether: (i) it inhibited forskolin‐stimulated cyclic AMP production by Chinese hamster ovary (CHO) cells transfected with human CB2 (hCB2) receptors; (ii) it stimulated [35S]GTPγS binding to hCB2 CHO cell and mouse spleen membranes; (iii) it attenuated signs of inflammation/hyperalgesia induced in mouse hind paws by intraplantar injection of carrageenan or formalin; and (iv) any such anti‐inflammatory or anti‐hyperalgesic effects were blocked by a CB1 or CB2 receptor antagonist.Key results: THCV inhibited cyclic AMP production by hCB2 CHO cells (EC50= 38 nM), but not by hCB1 or untransfected CHO cells or by hC...
Introduction: CR4056 is a novel imidazoline-2 receptor ligand endowed with low affinity MAO inhib... more Introduction: CR4056 is a novel imidazoline-2 receptor ligand endowed with low affinity MAO inhibition properties. Objectives: Aims of this study was to test with different methods the anti-nociceptive effect of CR4056 in rat models of neuropathic pain, i.e. Bortezomib(Btz)-induced neuropathic pain, streptozotocin-induced diabetes and chronic constriction injury (CCI). In the Btz model (0.20mg/kg 3qwx8 iv) and in the experimental diabetes model CR4056 was administered at 6-60mg/kg po. In the CCI mononeuropathy model CR4056 was administered at 10-80 mg/kg po. Nerve conduction velocity (NCV), dynamic, Randall-Selitto, plantar and von Frey tests were used to assess the effect of CR4056. Results: After 8 weeks of treatment, Btz induced a severe reduction in NCV and this impairment was not reversed by CR4056. The behavioral assessment showed a significant mechanical allodynia in rats treated wit Btz for 8 wks and the daily administration of CR4056 significantly reduced this condition. This effect was persistent along the entire period of administration after Btz withdrawal (2 weeks). In the models of streptozotocin-induced diabetes and CCI, treatment with CR4056 significantly attenuated mechanical and thermal hyperalgesia, while CR4056 had no effect on mechanical allodynia in both experimental models. Conclusions: These results promote the use of CR4056 as a potential treatment in the chronic neuropathic pain therapy.
Heme is a prosthetic group in a large number of essential proteins that have a pivotal role in ox... more Heme is a prosthetic group in a large number of essential proteins that have a pivotal role in oxygen transport, storage and electron shuttling. High amounts of free heme are associated with pathological states. Recently, it has been suggested that activation of Toll-like receptor 4 (TLR4) is one of the ways in which the ‘danger signal’ of free heme is detected. Here, we examine the biochemical basis of the modulation of the TLR4 pathway by hemin (iron(III)-protoporphyrin IX) and its metabolic, oxidated derivative coprohemin (iron(III)-coproporphyrin I). High concentrations of hemin (50 μM) triggered TLR4-mediated IL-8 production in the human HEK293/TLR4 cell line in the absence of the co-receptors CD14 and MD-2; the latter an essential co-receptor for TLR4 activation by endotoxin. Hemin and endotoxin have additive effects when co-administrated to HEK/TLR4 cells, suggesting that hemin and endotoxin activate TLR4 by different mechanisms. Coprohemin, in contrast to hemin, is unable to...
Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the co... more Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol−ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.
The antiin¯ammatory activity of synthetic cannabinoid nabilone in the rat model of carrageenanind... more The antiin¯ammatory activity of synthetic cannabinoid nabilone in the rat model of carrageenaninduced acute hindpaw in¯ammation was compared with that of the endocannabinoid palmitoylethanolamide and the nonsteroidal antiin¯ammatory drug indomethacin. 2 Preliminary experiments in rats used a tetrad of behavioural tests, speci®c for tetrahydrocannabinol-type activity in the CNS. These showed that the oral dose of nabilone 2.5 mg kg 71 had no cannabinoid psychoactivity. 3 Intraplantar injection of carrageenan (1% w v 71) elicited a time-dependent increase in paw volume and thermal hyperalgesia. 4 Nabilone (0.75, 1.5, 2.5 mg kg 71 , p.o.), given 1 h before carrageenan, reduced the development of oedema and the associated hyperalgesia in a dose-related manner. Nabilone 2.5 mg kg 71 , palmitoylethanolamide 10 mg kg 71 and indomethacin 5 mg kg 71 , given p.o. 1 h before carrageenan, also reduced the in¯ammatory parameters in a time-dependent manner. 5 The selective CB 2 cannabinoid receptor antagonist {N-[(1S)-endo-1,3,3-trimethyl bicyclo [2.2.1]heptan-2yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide} (SR 144528), 3 mg kg 71 p.o. 1 h before nabilone and palmitoylethanolamide, prevented the anti-oedema and antihyperalgesic eects of the two cannabinoid agonists 3 h after carrageenan. 6 Our ®ndings show the antiin¯ammatory eect of nabilone and con®rm that of palmitoylethanolamide indicating that these actions are mediated by an uncharacterized CB 2-like cannabinoid receptor.
The antinociceptive properties of cannabinoids in persistent pain are not fully elucidated. We in... more The antinociceptive properties of cannabinoids in persistent pain are not fully elucidated. We investigated the effect of repeated treatment with the synthetic cannabinoid receptor agonist WIN 55,212-2 on the neuropathic pain induced in rats by chronic constriction of the sciatic nerve. WIN 55,212-2 administered daily throughout the development of neuropathy reversed the hyperalgesia, at a dose (0.1 mg kg À1 , s.c.) that had no effect on the nociceptive responses of either paw contralateral to the sciatic ligation or of animals subjected to sham surgery. At 14 days after injury, the levels of mediators known to be involved in neuropathic pain, such as prostaglandin E2, NO and the neuronal NOS, were increased. Repeated treatment with WIN 55,212-2 abolished these increases. In the light of the current clinical need for neuropathic pain treatments, these findings indicate that cannabinoid agonists, at doses devoid of psychoactive effects, could constitute important compounds for the development of new analgesics.
Palmitoylethanolamide (PEA) is an endogenous lipid that is thought to be involved in endogenous p... more Palmitoylethanolamide (PEA) is an endogenous lipid that is thought to be involved in endogenous protective mechanisms activated as a result of stimulation of inflammatory response. In spite of the well demonstrated anti-inflammatory properties of PEA, its involvement in controlling pain pathways still remains poorly characterized. On this basis, we tested the efficacy of PEA in vivo against a peculiar persistent pain, such as neuropathic one. PEA was administered i.p. to mice with chronic constriction injury of sciatic nerve (CCI) once a day for one week starting the day after the lesion. This therapeutic regimen evoked a relief of both thermal hyperalgesia and mechanical allodynia in neuropathic mice. Various selective receptor antagonists were used in order to clarify the relative contribution of cannabinoid, vanilloid and peroxisome proliferator-activated receptor to PEA-induced effects. The results indicated that CB 1 , PPARc and TRPV1 receptors mediated the antinociception induced by PEA, suggesting that the most likely mechanism might be the so-called ''entourage effect" due to the PEA-induced inhibition of the enzyme catalyzing the endocannabinoid anandamide (AEA) degradation that leads to an enhancement of its tissue levels thus increasing its analgesic action. In addition, the hypothesis that PEA might act through the modulation of local mast cells degranulation is sustained by our findings showing that PEA significantly reduced the production of many mediators such as TNFa and neurotrophic factors, like NGF. The findings presented here, in addition to prove the beneficial effects of PEA in chronic pain, identify new potential targets for analgesic medicine.
Biochemical Characterization of the Effects of the ... Mariapia Colleoni', Barbara Costal, E... more Biochemical Characterization of the Effects of the ... Mariapia Colleoni', Barbara Costal, Enzo Gori' and Angela Santagostino* 'Institute of Pharmacology. Faculty of Sciences MM FF NN, University of Milano. via Vanvitelli 32/A, 1-20129. Milano, and 'Department of Environmental and ...
Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the co... more Despite the relevance of carbohydrates as cues in eliciting specific biological responses, the covalent surface modification of collagen-based matrices with small carbohydrate epitopes has been scarcely investigated. We report thereby the development of an efficient procedure for the chemoselective neoglycosylation of collagen matrices (patches) via a thiol-ene approach, between alkene-derived monosaccharides and the thiol-functionalized material surface. Synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), Fourier transform-infrared (FT-IR), and enzyme-linked lectin assay (ELLA) confirmed the effectiveness of the collagen neoglycosylation. Preliminary biological evaluation in osteoarthritic models is reported. The proposed methodology can be extended to any thiolated surface for the development of smart biomaterials for innovative approaches in regenerative medicine.
Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyp... more Cannabidiol (CBD), a nonpsychoactive marijuana constituent, was recently shown as an oral antihyperalgesic compound in a rat model of acute inflammation. We examined whether the CBD antihyperalgesic effect could be mediated by cannabinoid receptor type 1 (CB1) or cannabinoid receptor type 2 (CB2) and/or by transient receptor potential vanilloid type 1 (TRPV1). Rats received CBD (10 mg kg À1 ) and the selective antagonists: SR141716 (N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) for CB1, SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide) for CB2 and capsazepine (CPZ) for TRPV1 receptors. The intraplantar injection of carrageenan in rats induced a time-dependent thermal hyperalgesia, which peaked at 3 h and decreased at the following times. CBD, administered 2 h after carrageenan, abolished the hyperalgesia to the thermal stimulus evaluated by plantar test. Neither SR141716 (0.5 mg kg À1 ) nor SR144528 (3 and 10 mg kg À1 ) modified the CBD-induced antihyperalgesia; CPZ partially at the lowest dose (2 mg kg À1 ) and fully at the highest dose (10 mg kg À1 ) reversed this effect. These results demonstrate that TRPV1 receptor could be a molecular target of the CBD antihyperalgesic action.
Toll-like receptors (TLRs) are the best characterized pattern recognition receptors 1 . Individua... more Toll-like receptors (TLRs) are the best characterized pattern recognition receptors 1 . Individual TLRs recruit diverse combinations of adaptor proteins, triggering signal transduction pathways and leading to the activation of various transcription factors, including nuclear factor kB, activation protein 1 and interferon regulatory factors 2 . Interleukin-2 is one of the molecules produced by mouse dendritic cells after stimulation by different pattern recognition receptor agonists 3-6 . By analogy with the events after T-cell receptor engagement leading to interleukin-2 production, it is therefore plausible that the stimulation of TLRs on dendritic cells may lead to activation of the Ca 21 /calcineurin and NFAT (nuclear factor of activated T cells) pathway. Here we show that mouse dendritic cell stimulation with lipopolysaccharide (LPS) induces Src-family kinase and phospholipase Cc2 activation, influx of extracellular Ca 21 and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. We also show that LPS-induced NFAT activation via CD14 is necessary to cause the apoptotic death of terminally differentiated dendritic cells, an event that is essential for maintaining self-tolerance and preventing autoimmunity 7,8 . Consequently, blocking this pathway in vivo causes prolonged dendritic cell survival and an increase in T-cell priming capability. Our findings reveal novel aspects of molecular signalling triggered by LPS in dendritic cells, and identify a new role for CD14: the regulation of the dendritic cell life cycle through NFAT activation. Given the involvement of CD14 in disease, including sepsis and chronic heart failure 9,10 , the discovery of signal transduction pathways activated exclusively via CD14 is an important step towards the development of potential treatments involving interference with CD14 functions.
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Papers by B. Costa