Upon activation, brain microglial cells release proinflammatory mediators, such as TNF␣, which may play an important role in eliciting neuroinflammatory processes causing brain damage. As cannabinoids have been reported to exert anti-inflammatory and neuroprotective actions in the brain, we here examined the effect of both synthetic and endogenous cannabinoids on TNF␣ release elicited by bacterial endotoxin lypopolysaccharide (LPS) in cultured microglia. Exposure of primary cultures of rat cortical microglial cells to LPS significantly stimulated TNF␣ mRNA expression and release. The endogenous cannabinoids anandamide and 2-arachidonylglycerol (2-AG), as well as the synthetic cannabinoids (ϩ)WIN 55,212-2, CP 55,940, and HU210, inhibited in a concentration-dependent manner (1-10 M) the LPS-induced TNF␣ release. Unlike the high-affinity cannabinoid receptor agonist (ϩ)WIN 55,212-2, the low-affinity stereoisomer (Ϫ)WIN 55,212-2 did not exert any significant inhibition on TNF␣ release. Given this stereoselectivity, the ability of (ϩ)WIN 55,212-2 to inhibit LPS-induced TNF␣ release from microglia is most likely receptor-mediated. By RT-PCR we found that the two G i/o protein-coupled cannabinoid receptors (type 1 and 2) are both expressed in microglial cultures. However, selective antagonists of type 1 (SR141716A and AM251) and type 2 (SR144528) cannabinoid receptors did not affect the effect of (ϩ)WIN 55,212-2. Consistent with this finding is the observation that the ablative effect of (ϩ)WIN 55,212-2 on LPS-evoked release of TNF␣ was not sensitive to the G i/o protein inactivator pertussis toxin. In addition, the cAMP elevating agents dibutyryl cAMP and forskolin both abolished LPS-induced TNF␣ release, thus rendering unlikely the possibility that (ϩ)WIN 55,212-2 could ablate TNF␣ release through the inhibition of adenylate cyclase via the G i -coupled cannabinoid receptors type 1 and 2. In summary, our data indicate that both synthetic and endogenous cannabinoids inhibit LPS-induced release of TNF␣ from microglial cells. By showing that such effect does not appear to be mediated by either CB receptor type 1 or 2, we provide evidence suggestive of the existence of yet unidentified cannabinoid receptor(s) in brain microglia. GLIA 41: 161-168, 2003.

BackgroundThe transient receptor potential ankyrin 1 (TRPA1) channel, localized to airway sensory nerves, has been proposed to mediate airway inflammation evoked by allergen and cigarette smoke (CS) in rodents, via a neurogenic mechanism. However the limited clinical evidence for the role of neurogenic inflammation in asthma or chronic obstructive pulmonary disease raises an alternative possibility that airway inflammation is promoted by non-neuronal TRPA1.Methodology/Principal FindingsBy using Real-Time PCR and calcium imaging, we found that cultured human airway cells, including fibroblasts, epithelial and smooth muscle cells express functional TRPA1 channels. By using immunohistochemistry, TRPA1 staining was observed in airway epithelial and smooth muscle cells in sections taken from human airways and lung, and from airways and lung of wild-type, but not TRPA1-deficient mice. In cultured human airway epithelial and smooth muscle cells and fibroblasts, acrolein and CS extract evoked IL-8 release, a response selectively reduced by TRPA1 antagonists. Capsaicin, agonist of the transient receptor potential vanilloid 1 (TRPV1), a channel co-expressed with TRPA1 by airway sensory nerves, and acrolein or CS (TRPA1 agonists), or the neuropeptide substance P (SP), which is released from sensory nerve terminals by capsaicin, acrolein or CS), produced neurogenic inflammation in mouse airways. However, only acrolein and CS, but not capsaicin or SP, released the keratinocyte chemoattractant (CXCL-1/KC, IL-8 analogue) in bronchoalveolar lavage (BAL) fluid of wild-type mice. This effect of TRPA1 agonists was attenuated by TRPA1 antagonism or in TRPA1-deficient mice, but not by pharmacological ablation of sensory nerves.ConclusionsOur results demonstrate that, although either TRPV1 or TRPA1 activation causes airway neurogenic inflammation, solely TRPA1 activation orchestrates an additional inflammatory response which is not neurogenic. This finding suggests that non-neuronal TRPA1 in the airways is functional and potentially capable of contributing to inflammatory airway diseases.

Smoking cigarettes is the major risk factor for chronic obstructive pulmonary disease (COPD). COPD is a condition associated with chronic pulmonary inflammation, characterized by macrophage activation, neutrophil recruitment, and cell injury. Many substances contained in cigarette smoke, including reactive oxygen species (ROS), have been proposed to be responsible for the inflammatory process of COPD. However, this issue remains unsettled. By gas chromatography/mass spectrometry (GC/MS) we show that acrolein and crotonaldehyde, two alpha,beta-unsaturated aldehydes, are contained in aqueous cigarette smoke extract (CSE) at micromolar concentrations and mimic CSE in evoking the release of the neutrophil chemoattractant IL-8 and of the pleiotropic inflammatory cytokine TNF-alpha from the human macrophagic cell line U937. In addition, acrolein (10-30 microM) released IL-8 also from cultured human alveolar macrophages and THP-1 macrophagic cells. 4-hydroxy-2-nonenal (30-100 microM), an endogenous alpha,beta-unsaturated aldehyde that is abundant in lungs of patients with COPD, stimulated the release of IL-8 from U937 cells, whereas the saturated aldehyde, acetaldehyde, was ineffective. CSE-evoked IL-8 release was remarkably (> 80%) inhibited by N-acetyl-cysteine (0.1-3 mM) or glutathione monoethyl ester (1-3 mM). Both compounds, by forming covalent adducts (Michael adducts), completely removed unsaturated aldehydes from CSE. Our data demonstrate that alpha,beta-unsaturated aldehydes are major mediators of cigarette smoke-induced macrophage activation, and suggest that they might contribute to pulmonary inflammation associated with cigarette smoke.

Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD), a syndrome characterized by pulmonary neutrophil infiltration, chronic inflammation, and progressive tissue destruction. We examined here the acute effect of aqueous cigarette smoke extract (CSE) and of two α,β-unsaturated aldehydes (acrolein and crotonaldehyde) contained in CSE in cultured normal human lung fibroblasts and small airway epithelial cells. By examining a panel of 19 cytokines and chemokines, we found that IL-8 release was elevated by CSE as well as by acrolein, whereas other inflammatory mediators were mostly unaffected. CSE-evoked IL-8 release was mimicked by acrolein and crotonaldehyde at concentrations (3–60 μM each) found in CSE and fully prevented by 1 mM α,β-unsaturated aldehydes scavengers N-acetylcysteine (NAC) or sodium 2-mercaptoethanesulfonate. Neither the saturated aldehyde acetaldehyde nor H2O2 evoked IL-8 release. In addition, CSE or crotonaldehyde upregulated the release of IL-8 from alveolar macrophages from both COPD patients and healthy nonsmokers, indicating that this is a response common to cells involved in lung inflammation. CSE-evoked IL-8 release was accompanied by increased phosphorylation of p38 MAPK and ERK1/2. CSE-evoked p38 and ERK1/2 phosphorylation was mimicked by acrolein and inhibited by NAC. IL-8 release elicited by both acrolein and CSE was blocked by pharmacological inhibition of p38 and ERK1/2 phosphorylation. In summary, our data show that α,β-unsaturated aldehydes-evoked phosphorylation of p38 and ERK1/2 underlies IL-8 release elicited by CSE, thus shedding light on the mechanisms through which cigarette smoke can initiate inflammation in the lung.

Flurbiprofen, a nonsteroidal antiinflammatory drug (NSAID), has been recently described to selectively inhibit beta-amyloid(1)(-)(42) (Abeta42) secretion, the most toxic component of the senile plaques present in the brain of Alzheimer patients. The use of this NSAID in Alzheimer's disease (AD) is hampered by a significant gastrointestinal toxicity associated with cyclooxygenase (COX) inhibition. New flurbiprofen analogues were synthesized, with the aim of increasing Abeta42 inhibitory potency while removing anti-COX activity. In vitro ADME developability parameters were taken into account in order to identify optimized compounds at an early stage of the project. Appropriate substitution patterns at the alpha position of flurbiprofen allowed for the complete removal of anti-COX activity, while modifications at the terminal phenyl ring resulted in increased inhibitory potency on Abeta42 secretion. In rats, some of the compounds appeared to be well absorbed after oral administration and to penetrate into the central nervous system. Studies in a transgenic mice model of AD showed that selected compounds significantly decreased plasma Abeta42 concentrations. These new flurbiprofen analogues represent potential drug candidates to be developed for the treatment of AD.

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This study examined the pharmacologic characterization of CHF6001 [(S)-3,5-dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy) phenyl)-2-(3-(cyclopropylmethoxy)-4-(methylsulfonamido)benzoyloxy)ethyl)pyridine 1-oxide], a novel phosphodiesterase (PDE) 4 inhibitor designed for treating pulmonary inflammatory diseases via inhaled administration. CHF6001 was 7-and 923-fold more potent than roflumilast and cilomilast, respectively, in inhibiting PDE4 enzymatic activity (IC 50 5 0.026 6 0.006 nM). CHF6001 inhibited PDE4 isoforms A-D with equal potency, showed an elevated ratio of high-affinity rolipram binding site versus low-affinity rolipram binding site (i.e., .40) and displayed .20,000-fold selectivity versus PDE4 compared with a panel of PDEs. CHF6001 effectively inhibited (subnanomolar IC 50 values) the release of tumor necrosis factor-a from human peripheral blood mononuclear cells, human acute monocytic leukemia cell line macrophages (THP-1), and rodent macrophages (RAW264.7 and NR8383). Moreover, CHF6001 potently inhibited the activation of oxidative burst in neutrophils and eosinophils, neutrophil chemotaxis, and the release of interferon-g from CD4 1 T cells. In all these functional assays, CHF6001 was more potent than previously described PDE4 inhibitors, including roflumilast, UK-500,001 [2-(3,4-difluorophenoxy)-5-fluoro-N-((1S,4S)-4-(2-hydroxy-5-methylbenzamido)cyclohexyl)nicotinamide], and cilomilast, and it was comparable to GSK256066 [6-((3-(dimethylcarbamoyl)phenyl)sulfonyl)-4-((3-methoxyphenyl)amino)-8-methylquinoline-3-carboxamide]. When administered intratracheally to rats as a micronized dry powder, CHF6001 inhibited liposaccharide-induced pulmonary neutrophilia (ED 50 5 0.205 mmol/kg) and leukocyte infiltration (ED 50 5 0.188 mmol/kg) with an efficacy comparable to a high dose of budesonide (1 mmol/kg i. p.). In sum, CHF6001 has the potential to be an effective topical treatment of conditions associated with pulmonary inflammation, including asthma and chronic obstructive pulmonary disease.

The first steps in the selection process of a new anti-inflammatory drug for the inhaled treatment of asthma and chronic obstructive pulmonary disease are herein described. A series of novel ester derivatives of 1-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-(3,5-dichloropyridin-4-yl) ethanol have been synthesized and evaluated for inhibitory activity toward cAMP-specific phosphodiesterase-4 (PDE4). In particular, esters of variously substituted benzoic acids were extensively explored, and structural modification of the alcoholic and benzoic moieties were performed to maximize the inhibitory potency. Several compounds with high activity in cell-free and cell-based assays were obtained. Through the evaluation of opportune in vitro ADME properties, a potential candidate suitable for inhaled administration in respiratory diseases was identified and tested in an in vivo model of pulmonary inflammation, proving its efficacy.