Fabrizio Facchinetti

Cannabinoids ablate release of TNFα in rat microglial cells stimulated with lypopolysaccharide

Upon activation, brain microglial cells release proinflammatory mediators, such as TNFα, 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 TNFα release elicited by bacterial endotoxin lypopolysaccharide (LPS) in cultured microglia. Exposure of primary cultures of rat cortical microglial cells to LPS significantly stimulated TNFα mRNA expression and release. The endogenous cannabinoids anandamide and 2‐arachidonylglycerol (2‐AG), as well as the synthetic cannabinoids (+)WIN 55,212‐2, CP 55,940, and HU210, inhibited in a concentration‐dependent manner (1–10 μM) the LPS‐induced TNFα release. Unlike the high‐affinity cannabinoid receptor agonist (+)WIN 55,212‐2, the low‐affinity stereoisomer (−)WIN 55,212‐2 did not exert any significant inhibition on TNFα release. Given this stereoselectivity, the ability of (+)WIN 55,212‐2 to inhibit LPS‐induced TNFα release from microglia is most likely receptor‐mediated. By RT‐PCR we found that the two Gi/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 (+)WIN 55,212‐2. Consistent with this finding is the observation that the ablative effect of (+)WIN 55,212‐2 on LPS‐evoked release of TNFα was not sensitive to the Gi/o protein inactivator pertussis toxin. In addition, the cAMP elevating agents dibutyryl cAMP and forskolin both abolished LPS‐induced TNFα release, thus rendering unlikely the possibility that (+)WIN 55,212‐2 could ablate TNFα release through the inhibition of adenylate cyclase via the Gi‐coupled cannabinoid receptors type 1 and 2. In summary, our data indicate that both synthetic and endogenous cannabinoids inhibit LPS‐induced release of TNFα 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.

Transient Receptor Potential Ankyrin 1 Channel Localized to Non-Neuronal Airway Cells Promotes Non-Neurogenic Inflammation

Background The 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 Findings By 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. Conclusions Our 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.

α,β-Unsaturated aldehydes contained in cigarette smoke elicit IL-8 release in pulmonary cells through mitogen-activated protein kinases

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 alpha,beta-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 microM each) found in CSE and fully prevented by 1 mM alpha,beta-unsaturated aldehydes scavengers N-acetylcysteine (NAC) or sodium 2-mercaptoethanesulfonate. Neither the saturated aldehyde acetaldehyde nor H(2)O(2) 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 alpha,beta-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.

1-(3′,4′-Dichloro-2-fluoro[1,1′-biphenyl]-4-yl)-cyclopropanecarboxylic Acid (CHF5074), a Novel γ-Secretase Modulator, Reduces Brain β-Amyloid Pathology in a Transgenic Mouse Model of Alzheimer's Disease without Causing Peripheral Toxicity

Some nonsteroidal anti-inflammatory drugs has been shown to allosterically modulate the activity of γ-secretase, the enzymatic complex responsible for the formation of β-amyloid (Aβ). 1-(3′,4′-Dichloro-2-fluoro[1,1′-biphenyl]-4-yl)-cyclopropanecarboxylic acid (CHF5074) is a new γ-secretase modulator, devoid of anticyclooxygenase (COX) and Notch-interfering activities in vitro. We evaluated the effects of chronic CHF5074 treatment on brain Aβ pathology in Tg2576 transgenic mice. Twenty-eight animals of 9.5 to 10.5 months of age received CHF5074-medicated diet (375 ppm) or standard diet for 17 weeks. Compared with controls, CHF5074 treatment significantly reduced the area occupied by plaques and the number of plaques in cortex (–52.2 ± 5.6%, p = 0.0003 and –48.9 ± 6.6%, p = 0.0004, respectively) and hippocampus (–76.7 ± 6.4%, p = 0.004 and –66.2 ± 10.3%, p = 0.037, respectively). Biochemical analysis confirmed the histopathological measures, with CHF5074-treated animals showing reduced total brain Aβ40 (–49.2 ± 9.2%, p = 0.017) and Aβ42 (–43.5 ± 9.7%, p = 0.027) levels. In a human neuroglioma cell line expressing Swedish mutated form of amyloid precursor protein (H4swe), CHF5074 reduced Aβ42 and Aβ40 secretion, with an IC50 of 3.6 and 18.4 μM, respectively, values consistent with those measured in the brain of the CHF5074-treated Tg2576 mice (6.4 ± 0.4 μM). At 5 μM, no effects were observed on Notch intracellular cleavage in human embryonic kidney 293swe cells. CHF5074 was well tolerated by Tg2576 mice. No abnormal findings were observed upon histopathological examination of the gastrointestinal tract, indicating the absence of COX-related toxicity. Semiquantitative histochemical evaluation of goblet cells in the ileum of vehicle- and CHF5074-treated animals yielded similar results, suggesting no effects on Notch pathway. CHF5074 is therefore a promising therapeutic agent for Alzheimers disease.

CHF5074, a novel γ-secretase modulator, attenuates brain β-amyloid pathology and learning deficit in a mouse model of Alzheimer's disease

Background and purpose:  We evaluated the effects of 1‐(3′,4′‐dichloro‐2‐fluoro[1,1′‐biphenyl]‐4‐yl)‐cyclopropanecarboxylic acid (CHF5074), a new γ‐secretase modulator, on brain β‐amyloid pathology and spatial memory in transgenic mice expressing the Swedish and London mutations of human amyloid precursor protein (hAPP).

Cigarette smoke and its component acrolein augment IL-8/CXCL8 mRNA stability via p38 MAPK/MK2 signaling in human pulmonary cells.

Interleukin-8 (IL-8/CXCL8) is an important neutrophil chemoattractant known to be elevated in the airways of cigarette smokers and in patients with chronic obstructive pulmonary disease (COPD). We examined the acute effect of aqueous cigarette smoke extract (CSE) on IL-8 expression in primary human pulmonary cells, in particular in normal human bronchial smooth muscle cells (HBSMCs). IL-8 mRNA levels increased upon CSE exposure in a concentration- and time-dependent manner, and such an effect was accompanied by IL-8 secretion. CSE-evoked elevation of IL-8 mRNA was mimicked by its component acrolein. Both CSE and acrolein induced p38 mitogen-activated protein kinase (MAPK) phosphorylation, accompanied by the phosphorylation of MAPK-activated kinase 2 (MK2), a known downstream substrate of the p38 MAPK, both in HBSMCs and in human airway epithelial cells. Furthermore, pharmacological inhibition of p38 MAPK or MK2 strongly accelerated the decay of IL-8 mRNA levels upon stimulation with CSE or acrolein and subsequent blockade of mRNA neosynthesis with actinomycin D in pulmonary structural cells (HBSMCs and airways epithelial cells) as well as in human alveolar macrophages. Conversely, pharmacological inhibition of ERK1/2 signaling inhibited CSE-induced steady-state levels of IL-8 mRNA without affecting mRNA stability, thus suggesting inhibition at the transcriptional level. In sum, p38 MAPK/MK2 signaling is an important posttranscriptional mechanism underlying upregulation of IL-8 mRNA levels elicited by CSE and acrolein. Given the pivotal role of IL-8 in neutrophil chemotaxis and activation, our results shed light on the mechanisms through which cigarette smoke can initiate inflammation in the lung.

Acrolein effects in pulmonary cells: relevance to chronic obstructive pulmonary disease

Acrolein (2‐propenal) is a highly reactive α,β‐unsaturated aldehyde and a respiratory irritant that is ubiquitously present in the environment but that can also be generated endogenously at sites of inflammation. Acrolein is abundant in tobacco smoke, which is the major environmental risk factor for chronic obstructive pulmonary disease (COPD), and elevated levels of acrolein are found in the lung fluids of COPD patients. Its high electrophilicity makes acrolein notorious for its facile reaction with biological nucleophiles, leading to the modification of proteins and DNA and depletion of antioxidant defenses. As a consequence, acrolein results in oxidative stress as well as altered intracellular signaling and gene transcription/translation. In pulmonary cells, acrolein, at subtoxic concentrations, can activate intracellular stress kinases, alter the production of inflammatory mediators and proteases, modify innate immune response, induce mucus hypersecretion, and damage airway epithelium. A better comprehension of the mechanisms underlying acrolein effects in the airways may suggest novel treatment strategies in COPD.

Cigarette smoke and α,β-unsaturated aldehydes elicit VEGF release through the p38 MAPK pathway in human airway smooth muscle cells and lung fibroblasts.

BACKGROUND AND PURPOSE Vascular endothelial growth factor (VEGF) is an angiogenic factor known to be elevated in the sputum of asymptomatic smokers as well as smokers with bronchitis type of chronic obstructive pulmonary disease. The aim of this study was to investigate whether acute exposure to cigarette smoke extract altered VEGF production in lung parenchymal cells.

Cannabidiol, unlike synthetic cannabinoids, triggers activation of RBL‐2H3 mast cells

Cannabidiol (CBD), a prominent psychoinactive component of cannabis with negligible affinity for known cannabinoid receptors, exerts numerous pharmacological actions, including anti‐inflammatory and immunosuppressive effects, the underlying mechanisms of which remain unclear. In the current study, we questioned whether CBD modulates activation of mast cells, key players in inflammation. By using the rat basophilic leukemia mast cell line (RBL‐2H3), we demonstrate that CBD (3–10 μM) augments β‐hexosaminidase release, a marker of cell activation, from antigen‐stimulated and unstimulated cells via a mechanism, which is not mediated by Gi/Go protein‐coupled receptors but rather is associated with a robust rise in intracellular calcium ([Ca2+]i) levels sensitive to clotrimazole and nitrendipine (10–30 μM). This action, although mimicked by Δ9‐tetrahydrocannabinol (THC), is opposite to that inhibitory, exerted by the synthetic cannabinoids WIN 55,212‐2 and CP 55,940. Moreover, the vanilloid capsaicin, a full agonist of transient receptor potential channel VR1, did not affect [Ca2+]ilevels in the RBL‐2H3 cells, thus excluding the involvement of this receptor in the CBD‐mediated effects. Together, these results support existence of yet‐to‐be identified sites of interaction, i.e., receptors and/or ion channels associated with Ca2+ influx of natural cannabinoids such as CBD and THC, the identification of which has the potential to provide for novel strategies and agents of therapeutic interest.

CHF6001 I: a novel highly potent and selective phosphodiesterase 4 inhibitor with robust anti-inflammatory activity and suitable for topical pulmonary administration.

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 (IC50 = 0.026 ± 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 IC50 values) the release of tumor necrosis factor-α 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-γ from CD4+ 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 (ED50 = 0.205 μmol/kg) and leukocyte infiltration (ED50 = 0.188 μmol/kg) with an efficacy comparable to a high dose of budesonide (1 μmol/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.