Ibuprofen: new explanation for an old phenomenon

Ibuprofen inhibits human sweet taste and glucose detection implicating an additional mechanism of metabolic disease risk reduction

BACKGROUND AND PURPOSE

The human sweet taste receptor, TAS1R2-TAS1R3, conveys sweet taste in the mouth and may help regulate glucose metabolism throughout the body. Ibuprofen and naproxen are structurally similar to known inhibitors of TAS1R2-TAS1R3 and have been associated with metabolic benefits. Here, we determined if ibuprofen and naproxen inhibited TAS1R2-TAS1R3 responses to sugars in vitro and their elicited sweet taste in vivo, in humans under normal physiological conditions, with implications for effects on glucose metabolism.

EXPERIMENTAL APPROACH

Human psychophysical taste testing and in vitro cellular calcium assays in HEK293 cells were performed to determine the effects of ibuprofen and naproxen on sugar taste signalling.

KEY RESULTS

Ibuprofen and naproxen inhibited the sweet taste of sugars and non-nutritive sweeteners in humans, dose-dependently. Ibuprofen reduced cellular signalling of sucrose and sucralose in vitro with heterologously expressed human TAS1R2 (hTAS1R2)-TAS1R3 in human kidney cells. To mirror internal physiology, low concentrations of ibuprofen, which represent human plasma levels after a typical dose, inhibit the sweet taste and oral detection of glucose at concentrations nearing post-prandial plasma glucose levels.

CONCLUSION AND IMPLICATIONS

Ibuprofen and naproxen inhibit activation of TAS1R2-TAS1R3 by sugar in humans. Long-term ibuprofen intake is associated with preserved metabolic function and reduced risk of metabolic diseases such as Alzheimer's, diabetes and colon cancer. In addition to its anti-inflammatory properties, we present here a novel pathway that could help explain the associations between metabolic function and chronic ibuprofen use.

Redesigning Ibuprofen for Improved Oral Delivery and Reduced Side Effects

Ibuprofen (IBP) is one of the most widely used nonsteroidal anti-inflammatory drugs (NSAIDs). Being well-known for its efficacy, long history of use, and reduced adverse events compared to other NSAIDs, IBP is authorized as an analgesic and antipyretic drug. IBP's mechanism of action consists of inhibiting cyclooxygenases, which are crucial oxidoreductases in prostaglandin synthesis and generation of inflammation and pain. However, despite being effective and relatively safe, IBP can still induce a dose-dependent toxicity which manifests mainly in the gastrointestinal system as ulcerations and altered mucosal blood flow and cytotoxicity characterized by mitochondrial dysfunction and increased membrane permeability in enterocytes and hepatocytes. Therefore, ongoing research is performed to improve the IBP's activity and treatment outcome, and one way to achieve such improvements is through reducing IBP's toxicity by designing less harmful but still effective novel IBP conjugates. The aim of this review is to summarize the latest achievements with IBP conjugation techniques that created such valuable IBP formulations less toxic than but as effective as the parent drug.

Defining Metabolic and Nonmetabolic Regulation of Histone Acetylation by NSAID Chemotypes

Nonsteroidal anti-inflammatory drugs (NSAIDs) are well-known for their effects on inflammatory gene expression. Although NSAIDs are known to impact multiple cellular signaling mechanisms, a recent finding is that the NSAID salicylate can disrupt histone acetylation, in part through direct inhibition of the lysine acetyltransferase (KAT) p300/CBP. While salicylate is a relatively weak KAT inhibitor, its CoA-linked metabolite is more potent; however, the ability of NSAID metabolites to inhibit KAT enzymes biochemically and in cells remains relatively unexplored. Here we define the role of metabolic and nonmetabolic mechanisms in inhibition of KAT activity by NSAID chemotypes. First, we screen a small panel of NSAIDs for biochemical inhibition of the prototypical KAT p300, leading to the finding that many carboxylate-containing NSAIDs, including ibuprofen, are able to function as weak inhibitors. Assessing the inhibition of p300 by ibuprofen-CoA, a known NSAID metabolite, reveals that linkage of ibuprofen to CoA increases its biochemical potency toward p300 and other KAT enzymes. In cellular studies, we find that carboxylate-containing NSAIDs inhibit histone acetylation. Finally, we exploit the stereoselective metabolism of ibuprofen to assess the role of its acyl-CoA metabolite in regulation of histone acetylation. This unique strategy reveals that formation of ibuprofen-CoA and histone acetylation are poorly correlated, suggesting metabolism may not be required for ibuprofen to inhibit histone acetylation. Overall, these studies provide new insights into the ability of NSAIDs to alter histone acetylation, and illustrate how selective metabolism may be leveraged as a tool to explore the influence of metabolic acyl-CoAs on cellular enzyme activity.

A network integration approach for drug-target interaction prediction and computational drug repositioning from heterogeneous information

The emergence of large-scale genomic, chemical and pharmacological data provides new opportunities for drug discovery and repositioning. In this work, we develop a computational pipeline, called DTINet, to predict novel drug-target interactions from a constructed heterogeneous network, which integrates diverse drug-related information. DTINet focuses on learning a low-dimensional vector representation of features, which accurately explains the topological properties of individual nodes in the heterogeneous network, and then makes prediction based on these representations via a vector space projection scheme. DTINet achieves substantial performance improvement over other state-of-the-art methods for drug-target interaction prediction. Moreover, we experimentally validate the novel interactions between three drugs and the cyclooxygenase proteins predicted by DTINet, and demonstrate the new potential applications of these identified cyclooxygenase inhibitors in preventing inflammatory diseases. These results indicate that DTINet can provide a practically useful tool for integrating heterogeneous information to predict new drug-target interactions and repurpose existing drugs.Network-based data integration for drug-target prediction is a promising avenue for drug repositioning, but performance is wanting. Here, the authors introduce DTINet, whose performance is enhanced in the face of noisy, incomplete and high-dimensional biological data by learning low-dimensional vector representations.

The impact of inflammation on respiratory plasticity

Breathing is a vital homeostatic behavior and must be precisely regulated throughout life. Clinical conditions commonly associated with inflammation, undermine respiratory function may involve plasticity in respiratory control circuits to compensate and maintain adequate ventilation. Alternatively, other clinical conditions may evoke maladaptive plasticity. Yet, we have only recently begun to understand the effects of inflammation on respiratory plasticity. Here, we review some of common models used to investigate the effects of inflammation and discuss the impact of inflammation on nociception, chemosensory plasticity, medullary respiratory centers, motor plasticity in motor neurons and respiratory frequency, and adaptation to high altitude. We provide new data suggesting glial cells contribute to CNS inflammatory gene expression after 24h of sustained hypoxia and inflammation induced by 8h of intermittent hypoxia inhibits long-term facilitation of respiratory frequency. We also discuss how inflammation can have opposite effects on the capacity for plasticity, whereby it is necessary for increases in the hypoxic ventilatory response with sustained hypoxia, but inhibits phrenic long term facilitation after intermittent hypoxia. This review highlights gaps in our knowledge about the effects of inflammation on respiratory control (development, age, and sex differences). In summary, data to date suggest plasticity can be either adaptive or maladaptive and understanding how inflammation alters the respiratory system is crucial for development of better therapeutic interventions to promote breathing and for utilization of plasticity as a clinical treatment.

The Effect of Ibuprofen on Cytokine Production by Mononuclear Cells from Schizophrenic Patients

The existence of a restrained inflammatory state in schizophrenic individuals posed the question whether anti-inflammatory drugs may exert antipsychotic effects. Therefore, the effect of ibuprofen (IB) on cytokine production by human peripheral blood mononuclear cells (PBMC) from schizophrenic patients was examined and compared to that of healthy subjects. PBMC from 25 schizophrenic patients and 24 healthy volunteers were incubated for 24 h with lipopolysaccharide (LPS) in the absence or presence of various concentrations of IB. The levels of IL-1β, IL-6, TNF-α, IL-10 and IL-1ra in the supernatants were tested applying ELISA kits. The secretion of TNF-α by cells from schizophrenic patients was significantly lower compared with controls. IB caused stimulation of TNF-α and IL-6 production by cells of the two groups and enhanced IL-1β secretion by cells from schizophrenic patients. IB inhibited IL-1ra and IL-10 generation by cells from the two groups. Without IB, IL-1ra secretion was negatively correlated with the disease severity, while 200 μg/ml of IB positively correlated with the PANSS total score. IL-10 production was positively correlated with the PANSS positive subscale score both in the absence or presence of IB. The findings suggest that the effect of IB on the production of inflammatory cytokines may benefit the health of schizophrenic patients.

Effect of antipyretic analgesics on immune responses to vaccination

While antipyretic analgesics are widely used to ameliorate vaccine adverse reactions, their use has been associated with blunted vaccine immune responses. Our objective was to review literature evaluating the effect of antipyretic analgesics on vaccine immune responses and to highlight potential underlying mechanisms. Observational studies reporting on antipyretic use around the time of immunization concluded that their use did not affect antibody responses. Only few randomized clinical trials demonstrated blunted antibody response of unknown clinical significance. This effect has only been noted following primary vaccination with novel antigens and disappears following booster immunization. The mechanism by which antipyretic analgesics reduce antibody response remains unclear and not fully explained by COX enzyme inhibition. Recent work has focused on the involvement of nuclear and subcellular signaling pathways. More detailed immunological investigations and a systems biology approach are needed to precisely define the impact and mechanism of antipyretic effects on vaccine immune responses.

Ibuprofen Blunts Ventilatory Acclimatization to Sustained Hypoxia in Humans

Ventilatory acclimatization to hypoxia is a time-dependent increase in ventilation and the hypoxic ventilatory response (HVR) that involves neural plasticity in both carotid body chemoreceptors and brainstem respiratory centers. The mechanisms of such plasticity are not completely understood but recent animal studies show it can be blocked by administering ibuprofen, a nonsteroidal anti-inflammatory drug, during chronic hypoxia. We tested the hypothesis that ibuprofen would also block the increase in HVR with chronic hypoxia in humans in 15 healthy men and women using a double-blind, placebo controlled, cross-over trial. The isocapnic HVR was measured with standard methods in subjects treated with ibuprofen (400mg every 8 hrs) or placebo for 48 hours at sea level and 48 hours at high altitude (3,800 m). Subjects returned to sea level for at least 30 days prior to repeating the protocol with the opposite treatment. Ibuprofen significantly decreased the HVR after acclimatization to high altitude compared to placebo but it did not affect ventilation or arterial O₂ saturation breathing ambient air at high altitude. Hence, compensatory responses prevent hypoventilation with decreased isocapnic ventilatory O₂-sensitivity from ibuprofen at this altitude. The effect of ibuprofen to decrease the HVR in humans provides the first experimental evidence that a signaling mechanism described for ventilatory acclimatization to hypoxia in animal models also occurs in people. This establishes a foundation for the future experiments to test the potential role of different mechanisms for neural plasticity and ventilatory acclimatization in humans with chronic hypoxemia from lung disease.

Central mediators involved in the febrile response: effects of antipyretic drugs

Fever is a complex signal of inflammatory and infectious diseases. It is generally initiated when peripherally produced endogenous pyrogens reach areas that surround the hypothalamus. These peripheral endogenous pyrogens are cytokines that are produced by leukocytes and other cells, the most known of which are interleukin-1β, tumor necrosis factor-α, and interleukin-6. Because of the capacity of these molecules to induce their own synthesis and the synthesis of other cytokines, they can also be synthesized in the central nervous system. However, these pyrogens are not the final mediators of the febrile response. These cytokines can induce the synthesis of cyclooxygenase-2, which produces prostaglandins. These prostanoids alter hypothalamic temperature control, leading to an increase in heat production, the conservation of heat, and ultimately fever. The effect of antipyretics is based on blocking prostaglandin synthesis. In this review, we discuss recent data on the importance of prostaglandins in the febrile response, and we show that some endogenous mediators can still induce the febrile response even when known antipyretics reduce the levels of prostaglandins in the central nervous system. These studies suggest that centrally produced mediators other than prostaglandins participate in the genesis of fever. Among the most studied central mediators of fever are corticotropin-releasing factor, endothelins, chemokines, endogenous opioids, and substance P, which are discussed herein. Additionally, recent evidence suggests that these different pathways of fever induction may be activated during different pathological conditions.

Central mediators involved in the febrile response: effects of antipyretic drugs

Fever is a complex signal of inflammatory and infectious diseases. It is generally initiated when peripherally produced endogenous pyrogens reach areas that surround the hypothalamus. These peripheral endogenous pyrogens are cytokines that are produced by leukocytes and other cells, the most known of which are interleukin-1β, tumor necrosis factor-α, and interleukin-6. Because of the capacity of these molecules to induce their own synthesis and the synthesis of other cytokines, they can also be synthesized in the central nervous system. However, these pyrogens are not the final mediators of the febrile response. These cytokines can induce the synthesis of cyclooxygenase-2, which produces prostaglandins. These prostanoids alter hypothalamic temperature control, leading to an increase in heat production, the conservation of heat, and ultimately fever. The effect of antipyretics is based on blocking prostaglandin synthesis. In this review, we discuss recent data on the importance of prostaglandins in the febrile response, and we show that some endogenous mediators can still induce the febrile response even when known antipyretics reduce the levels of prostaglandins in the central nervous system. These studies suggest that centrally produced mediators other than prostaglandins participate in the genesis of fever. Among the most studied central mediators of fever are corticotropin-releasing factor, endothelins, chemokines, endogenous opioids, and substance P, which are discussed herein. Additionally, recent evidence suggests that these different pathways of fever induction may be activated during different pathological conditions.

Influence of temperature on thyroid hormone signaling and endocrine disruptor action in Rana (Lithobates) catesbeiana tadpoles

Thyroid hormones (THs) are essential for normal growth, development, and metabolic control in vertebrates. Their absolute requirement during amphibian metamorphosis provides a powerful means to detect and assess the impact of environmental contaminants on TH signaling in the field and laboratory. As poikilotherms, frogs can experience considerable temperature fluctuations. Previous work demonstrated that low temperature prevents precocious TH-dependent induction of metamorphosis. However, a shift to a permissive higher temperature allows resumption of the induced metamorphic program regardless of whether or not TH remains. We investigated the impact of temperature on the TH-induced gene expression programs of premetamorphic Rana (Lithobates) catesbeiana tadpoles following a single injection of 10pmol/g body wet weight 3,3',5-triiodothyronine (T3). Abundance profiles of several T3-responsive mRNAs in liver, brain, lung, back skin, and tail fin were characterized under permissive (24°C), nonpermissive (5°C), or temperature shift (5-24°C) conditions. While responsiveness to T3 was retained to varying degrees at nonpermissive temperature, T3 modulation of thibz occurred in all tissues at 5°C suggesting an important role for this transcription factor in initiation of T3-dependent gene expression programs. Low temperature immersion of tadpoles in water containing 10nM T3 and the nonsteroidal anti-inflammatory drug, ibuprofen, or the antimicrobial agent, triclosan, perturbed some aspects of the gene expression programs of tail fin and back skin that was only evident upon temperature shift. Such temporal uncoupling of chemical exposure and resultant biological effects in developing frogs necessitates a careful evaluation of environmental temperature influence in environmental monitoring programs.

Effects of acute exposure to the non-steroidal anti-inflammatory drug ibuprofen on the developing North American Bullfrog (Rana catesbeiana) tadpole

A variety of pharmaceutical chemicals can represent constituents of municipal effluent outflows that are dispersed into aquatic receiving environments worldwide. Increasingly, there is concern as to the potential of such bioactive substances to interact with wildlife species at sensitive life stages and affect their biology. Using a combination of DNA microarray, quantitative real-time polymerase chain reaction, and quantitative nuclease protection assays, we assessed the ability of sub-lethal and environmentally relevant concentrations of ibuprofen (IBF), a non-steroidal anti-inflammatory agent and prevalent environmental contaminant, to function as a disruptor of endocrine-mediated post-embryonic development of the frog. While the LC50 of IBF for pre-metamorphic Rana catesbeiana tadpoles is 41.5 mg/L (95% confidence interval: 32.3-53.5 mg/L), exposure to concentrations in the ppb range elicited molecular responses both in vivo and in organ culture. A nominal concentration of 15 μg/L IBF (actual = 13.7 μg/L) altered the abundance of 26 mRNA transcripts within the liver of exposed pre-metamorphic R. catesbeiana tadpoles within 6 d. IBF-treated animals demonstrated subsequent disruption of thyroid hormone-mediated reprogramming in the liver transcriptome affecting constituents of several metabolic, developmental, and signaling pathways. Cultured tadpole tail fin treated with IBF for 48 h also demonstrated altered mRNA levels at drug concentrations as low as 1.5 μg/L. These observations raise the possibility that IBF may alter the post-embryonic development of anuran species in freshwater environs, where IBF is a persistent or seasonal pollutant.

In vitro evaluation of S-(+)-ibuprofen as drug candidate for intra-articular drug delivery system

Intra-articular drug delivery systems (DDSs) are envisaged as interesting alternative to locally release non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to reduce pain in patients with osteoarthritis. The present study examines the efficacy of S-(+)-ibuprofen on cartilage degradation as drug candidate for DDS loading. Humeral cartilage and joint capsule explants were collected from healthy sheep shoulder joints and they were cultured in mono- or in co-culture for 13 days with LPS in combination with S-(+)-ibuprofen at 50 µM and 1 mM. S-(+)-ibuprofen (50 µM) blocked prostaglandins production in LPS-activated explants but did not reduce cartilage degradation. By contrast, 1 mM S-(+)-ibuprofen treatment of cartilage explants reduced nitric oxide synthesis by 51% (p = 0.0072), proteoglycans degradation by 35% (p = 0.0114) and expression of serum amyloid protein - the main protein induced upon LPS challenge - by 44% (p < 0.0001). On contrary, in presence of synovial membrane, the protective effects of S-(+)-ibuprofen on cartilage damages were significantly diminished. At 1mM, S-(+)-ibuprofen reduced the cell lysis during culture of cartilage and joint capsule either in mono- or in co-culture. This study performed on sheep explants shows that 1 mM S-(+)-ibuprofen inhibited cartilage degradation via a mechanism independent of cyclooxygenase inhibition. Reduction of prostaglandins synthesis at 50 µM in all treatment groups and reduction of cartilage degradation observed at 1 mM suggest that S-(+)-ibuprofen could be considered as a promising drug candidate for the loading of intra-articular DDS.

Antitubercular specific activity of ibuprofen and the other 2-arylpropanoic acids using the HT-SPOTi whole-cell phenotypic assay

OBJECTIVES

Lead antituberculosis (anti-TB) molecules with novel mechanisms of action are urgently required to fuel the anti-TB drug discovery pipeline. The aim of this study was to validate the use of the high-throughput spot culture growth inhibition (HT-SPOTi) assay for screening libraries of compounds against Mycobacterium tuberculosis and to study the inhibitory effect of ibuprofen (IBP) and the other 2-arylpropanoic acids on the growth inhibition of M tuberculosis and other mycobacterial species.

METHODS

The HT-SPOTi method was validated not only with known drugs but also with a library of 47 confirmed anti-TB active compounds published in the ChEMBL database. Three over-the-counter non-steroidal anti-inflammatory drugs were also included in the screening. The 2-arylpropanoic acids, including IBP, were comprehensively evaluated against phenotypically and physiologically different strains of mycobacteria, and their cytotoxicity was determined against murine RAW264.7 macrophages. Furthermore, a comparative bioinformatic analysis was employed to propose a potential mycobacterial target.

RESULTS

IBP showed antitubercular properties while carprofen was the most potent among the 2-arylpropanoic class. A 3,5-dinitro-IBP derivative was found to be more potent than IBP but equally selective. Other synthetic derivatives of IBP were less active, and the free carboxylic acid of IBP seems to be essential for its anti-TB activity. IBP, carprofen and the 3,5-dinitro-IBP derivative exhibited activity against multidrug-resistant isolates and stationary phase bacilli. On the basis of the human targets of the 2-arylpropanoic analgesics, the protein initiation factor infB (Rv2839c) of M tuberculosis was proposed as a potential molecular target.

CONCLUSIONS

The HT-SPOTi method can be employed reliably and reproducibly to screen the antimicrobial potency of different compounds. IBP demonstrated specific antitubercular activity, while carprofen was the most selective agent among the 2-arylpropanoic class. Activity against stationary phase bacilli and multidrug-resistant isolates permits us to speculate a novel mechanism of antimycobacterial action. Further medicinal chemistry and target elucidation studies could potentially lead to new therapies against TB.

The effects of ibuprofen on sepsis parameters in preterm neonates

AIM

To examine the effects of ibuprofen used for patent ductus arteriosus (PDA) treatment on the production of the proinflammatory cytokines C-reactive protein (CRP) and interleukin 6 (IL-6) in preterm septic newborns.

METHODS

Patients with acute phase reactant elevation were divided into two groups according to receiving ibuprofen (Group I, n=51) or not (Group II, n=38). Course of sepsis was evaluated by CRP and IL-6 levels.

RESULTS

CRP and IL-6 levels at the time of diagnosis were not different between two groups [16±9.1 vs 16.4±13.2mg/dL (p=0.43) for CRP and 124±82 vs 119±73mg/dL (p=0.517) for IL-6, respectively]. Similarly, they were statistically insignificant between the groups at the 2nd or 3rd days of ibuprofen treatment [14.3±7.7 vs 13.7±5.9mg/dL (p=0.21) for CRP and 83±46 vs 86±37mg/dL (p=0.29) for IL-6, respectively]. However, CRP and IL6 levels showed significant difference between groups in the following days; 6.03±3.8 vs 9.1±4.9mg/dL (p=0.025) for CRP and 42±33.1 vs 58.9±27.1mg/dL (0.011) for IL-6 on 4th or 5th days of treatment and 2.3±3.2 vs 4.1±2.3mg/dL (p=0.032) for CRP and 16.1±12.4 vs 21.3±16.8mg/dL (p=0.016) for IL-6, on 7th to 10th days of treatment, respectively.

CONCLUSIONS

IL-6 and CRP may decrease in infants receiving ibuprofen treatment more than infants who do not receive it. This decrease should be considered at the time of caring a preterm infant with both sepsis and PDA after ibuprofen treatment.

Ibuprofen blocks time-dependent increases in hypoxic ventilation in rats

Recently, inflammatory processes have been shown to increase O(2)-sensitivity of the carotid body during chronic sustained hypoxia [Liu, X., He, L., Stensaas, L., Dinger, B., Fidone, S., 2009. Adaptation to chronic hypoxia involves immune cell invasion and increased expression of inflammatory cytokines in rat carotid body. Am. J. Physiol. Lung Cell Mol. Physiol. 296, L158-L166]. We hypothesized that blocking inflammation with ibuprofen would reduce ventilatory acclimatization to hypoxia by blocking such increases in carotid body O(2) sensitivity. We tested this in conscious rats treated with ibuprofen (4mg/kg IP daily) or saline during acclimatization to hypoxia ( [Formula: see text] for 7 days). Ibuprofen blocked the increase in hypoxic ventilation observed in chronically hypoxic rats treated with saline; ibuprofen had no effects on ventilation in normoxic control rats. Ibuprofen blocked increases in inflammatory cytokines (IL-1β, IL-6) in the brainstem with chronic hypoxia. The data supports our hypothesis and further analysis indicates that ibuprofen also blocks inflammatory processes in the central nervous system contributing to ventilatory acclimatization to hypoxia. Possible mechanisms linking inflammatory and hypoxic signaling are reviewed.

High-Dose Ibuprofen in Cystic Fibrosis

Cystic Fibrosis (CF) is the most common lethal genetic disorder in North America and Europe. Most patients succumb to progressive lung disease characterized by an exaggerated neutrophilic inflammation. In animal models of chronic infection, high-dose ibuprofen was demonstrated to reduce inflammation without hindering bacterial clearance. This led to two clinical trials, which demonstrated a benefit in slowing the progression of lung disease in CF. However, concerns about potential adverse effects have limited the use of high-dose ibuprofen in CF patients. There are a variety of potential mechanisms to account for the observed clinical benefit. A better understanding of these mechanisms could potentially lead to more targeted and better-tolerated anti-inflammatory therapies.

Neuroinflammation and memory: the role of prostaglandins

Neuroinflammation is a complex response to brain injury involving the activation of glia, release of inflammatory mediators within the brain, and recruitment of peripheral immune cells. Interestingly, memory deficits have been observed following many inflammatory states including infection, traumatic brain injury (TBI), normal aging, and Alzheimer's disease (AD). Prostaglandins (PGs), a class of lipid mediators which can have inflammatory actions, are upregulated by these inflammatory challenges and can impair memory. In this paper, we critically review the success of nonsteroidal anti-inflammatory drugs, which prevent the formation of PGs, in preventing neuroinflammation-induced memory deficits following lipopolysaccharide injection, TBI, aging, and experimental models of AD in rodents and propose a mechanism by which PGs could disrupt memory formation.

Delayed apoptosis of human monocytes exposed to immune complexes is reversed by oxaprozin: role of the Akt/IkappaB kinase/nuclear factor kappaB pathway

BACKGROUND AND PURPOSE

Monocytes-macrophages play a key role in the initiation and persistence of inflammatory reactions. Consequently, these cells represent an attractive therapeutic target for switching off overwhelming inflammatory responses. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most common drugs for the symptomatic treatment of rheumatic diseases. Their effects have been explained on the basis of cyclooxygenase (COX) inhibition. However, some of the actions of these drugs are not related to inhibition of prostaglandin synthesis.

EXPERIMENTAL APPROACH

We examined the effect of oxaprozin on apoptosis of immune complex-activated monocytes in comparison with drugs of the same class, and the signalling pathway that leads activated monocytes exposed to oxaprozin to apoptosis. In particular, we studied the activity of caspase-3, the involvement of IkappaB kinase (IKK)-nuclear factor kappaB (NF-kappaB) system and the activity of X-linked mammalian inhibitor of apoptosis protein (XIAP), Akt and mitogen-activated protein kinase (MAPK) in activated monocytes in the presence of oxaprozin.

KEY RESULTS

Immune complexes caused the inhibition of monocyte apoptosis. Oxaprozin reversed in a dose-dependent manner immune complex-induced survival of monocytes, without affecting the apoptosis of resting cells. Other NSAIDs are ineffective. The activity of oxaprozin was related to inhibition of Akt activation that, in turn, prevented p38 MAPK, IKK and NF-kappaB activation. Consistently, the inhibition of NF-kappaB activation reduced the production of the anti-apoptotic molecule XIAP, leading to uncontrolled activity of caspase 3.

CONCLUSIONS AND IMPLICATIONS

These results suggest that oxaprozin exerts its anti-inflammatory activity also through COX-independent pathways. It is likely that oxaprozin-mediated inhibition of the Akt/IKK/NF-kappaB pathway contributes to its anti-inflammatory properties.

Long-term use of nonsteroidal anti-inflammatory drugs normalizes the kinetics of gastric epithelial cells in patients with Helicobacter pylori infection via attenuation of gastric mucosal inflammation

BACKGROUND

Helicobacter pylori (H. pylori) is associated with chronic gastritis and gastric carcinogenesis. The effects of nonsteroidal anti-inflammatory drugs (NSAIDs), which exert chemopreventive effects on several cancers, on H. pylori-induced gastritis remain unknown. We investigated the effects of NSAIDs on gastric inflammation and the kinetics of gastric epithelial cells in H. pylori-induced gastritis.

METHODS

Patients with rheumatoid arthritis or osteoarthritis who took NSAIDs for more than 1 month and complained of dyspeptic symptoms were recruited for this study. Patients not on any NSAIDs were included as non-NSAID user controls. All patients underwent diagnostic testing for H. pylori infection, esophagogastroduodenoscopy, and gastric biopsies. Neutrophil infiltration into gastric mucosa, expression of inducible nitric oxide synthase (iNOS), and apoptosis and proliferation of gastric epithelial cells were evaluated by immunohistochemistry. In an in vitro study, the effects of NSAIDs on production of interleukin (IL)-8 induced by H. pylori in a gastric epithelial cell line (AGS) were determined.

RESULTS

Numbers of neutrophils infiltrating the gastric mucosa, iNOS-expressing inflammatory cells and apoptotic cells, and proliferating cells in gastric epithelium were higher in H. pylori-positive groups than H. pylori-negative groups. Among H. pyloripositive groups, these parameters were lower in NSAID users than in non-NSAID users. NSAIDs inhibited the production of IL-8 induced by H. pylori in AGS cells.

CONCLUSIONS

These findings suggest that long-term use of NSAIDs normalizes the kinetics of gastric epithelial cells in patients with H. pylori infection by attenuating gastric mucosal inflammation, which may result in prevention of the gastric carcinogenesis associated with H. pylori infection.

Adaptation to chronic hypoxia involves immune cell invasion and increased expression of inflammatory cytokines in rat carotid body

Exposure to chronic hypoxia (CH; 3-28 days at 380 Torr) induces adaptation in mammalian carotid body such that following CH an acute hypoxic challenge elicits an abnormally large increase in carotid sinus nerve impulse activity. The current study examines the hypothesis that CH initiates an immune response in the carotid body and that chemoreceptor hyperexcitability is dependent on the expression and action of inflammatory cytokines. CH resulted in a robust invasion of ED1(+) macrophages, which peaked on day 3 of exposure. Gene expression of proinflammatory cytokines, IL-1beta, TNFalpha, and the chemokine, monocyte chemoattractant protein-1, was increased >2-fold after 1 day of hypoxia followed by a >2-fold increase in IL-6 on day 3. After 28 days of CH, IL-6 remained elevated >5-fold, whereas expression of other cytokines recovered to normal levels. Cytokine expression was not restricted to immune cells. Studies of cultured type I cells harvested following 1 day of in vivo hypoxia showed elevated transcript levels of inflammatory cytokines. In situ hybridization studies confirmed expression of IL-6 in type I cells and also showed that CH induces IL-6 expression in supporting type II cells. Concurrent treatment of CH rats with anti-inflammatory drugs (ibuprofen or dexamethasone) blocked immune cell invasion and severely reduced CH-induced cytokine expression in carotid body. Drug treatment also blocked the development of chemoreceptor hypersensitivity in CH animals. Our findings indicate that chemoreceptor adaptation involves novel neuroimmune mechanisms, which may alter the functional phenotypes of type I cells and chemoafferent neurons.

Over-the-counter analgesics normalize blood glucose and body composition in mice fed a high fat diet

Type 2 diabetes (noninsulin-dependent diabetes mellitus) develops from a pre-diabetic condition that is characterized by insulin resistance and glucose intolerance, and is exacerbated by obesity. In this study, we compared the ability of over-the-counter analgesic drugs (OTCAD) [acetaminophen (APAP); ibuprofen (IBU); naproxen (NAP); aspirin (ASA)], to protect against the development of a pre-diabetic state in mice fed a high fat diet. After 10 weeks on the high fat diet, mice had normal fasting blood glucose (FBG) levels, but exhibited impaired glucose tolerance. Treatment with 20 mg OTCADs/kg body weight improved glucose tolerance, with the order of efficacy, APAP=ASA>IBU, while NAP proved ineffective. Mice fed the high fat diet also exhibited increases in weight gain associated with an increase in body fat. OTCADs prevented in part this increase in body fat, in the order of efficacy, APAP=IBU>NAP=ASA. In isolated liver mitochondria, OTCADs inhibited succinate-dependent H2O2 production, while in white adipose tissue, APAP inhibited NADPH-oxidase mediated H2O2 production and lipid peroxidation. Thus, OTCADs diminish pro-oxidant processes that might otherwise exacerbate inflammation and a pre-diabetic state. We conclude that OTCADs, especially APAP and IBU, may be valuable tools to delay or prevent the development of type 2 diabetes from a pre-diabetic condition.

Upregulation of ICAM-1 expression in bronchial epithelial cells by airway secretions in bronchiectasis

The airway epithelium participates in chronic airway inflammation by expressing adhesion molecules that mediate the transmigration of neutrophils into the inflamed airways. We hypothesize that, in patients with bronchiectasis, cytokines in their bronchial secretions enhance the expression of intercellular cell adhesion molecule (ICAM-1) in the bronchial epithelium and thus contribute to sustained recruitment of neutrophils into the inflamed airways. In the present study, we investigated the effect of bronchial secretions on the regulation of ICAM-1 in bronchial epithelial cells, and its modulation by pharmacologic agents. The expression of ICAM-1 mRNA and protein in human bronchial epithelial cells upon exposure to sputum sol from subjects with bronchiectasis were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and ELISA, respectively. Modulating effects of dexamethasone, ibuprofen, MK-663 or triptolide on ICAM-1 regulation were investigated in vitro. We demonstrated that changes in ICAM-1 expression correlated with levels of TNF-alpha in the sputum sol, and treatment of sol samples with TNF-alpha antibodies attenuated both the increase in ICAM-1 mRNA and protein. The role of TNF-alpha was further demonstrated when TNF-alpha elicited dose dependent increase in ICAM-1 expression. The sputum effect could also be suppressed dose-dependently by pre-incubation of bronchial epithelial cells with dexamethasone, ibuprofen, MK-663 or triptolide. Evidence is thus provided for the upregulation of bronchial epithelial ICAM-1 expression by airway secretions in bronchiectasis and a specific role for TNF-alpha in the secretions. The success of drug attenuation of this upregulation provides insight into possible therapeutic paradigms in the management of the disease.

Effect of Flunixin Meglumine on Cytokine Levels in Experimental Endotoxemia in Mice

In this study, effect of flunixin meglumine on serum tumour necrosis factor alpha, (TNFalpha) interleukin-1 beta and interleukin-10 levels was investigated in lipopolysaccharide-induced endotoxic mice. Healthy 273 Balb/C mice were used and divided into three equal groups. Group 1 was injected lipopolysaccharide (Escherichia coli 0111:B4, 250 microg/mouse, intraperitoneally), Group 2 was injected flunixin meglumine (2.5 mg/kg, subcutaneously), and Group 3 was injected lipopolysaccharide + flunixin meglumine. After the treatments, at 0., 1., 2., 3., 6., 12., 24th hours and 3., 5., 7., 14., 21., 28th days blood samples were taken from seven mice in each group. Serum TNFalpha, interleukin-1 beta and interleukin-10 levels were measured using commercially available kits by enzyme-linked immunoassay. Flunixin meglumine did not affect the cytokine levels in healthy animals. While lipopolysaccharide increased serum TNFalpha, interleukin-1 beta and interleukin-10 levels, flunixin meglumine inhibited increases at levels of all cytokines. As result, flunixin meglumine showed depressor effect on cytokine levels in endotoxemia and the effect may be a reason for the first chosen member of nonsteroid anti-inflammatory drug in endotoxemia.

CCL3/Macrophage inflammatory protein-1α induces fever and increases prostaglandin E2 in cerebrospinal fluid of rats: Effect of antipyretic drugs

The aim of this study was to investigate whether the increase in body temperature caused by intracerebroventricular (i.c.v.) injection of recombinant mouse CCL3/MIP1alpha [C-C (two adjacent conserved cysteines) ligand 3/macrophage inflammatory protein-1alpha] constitutes solely a hyperthermic response or a true integrated fever. Additionally, we examined the effects of systemic administration of different antipyretic drugs including the glucocorticoid dexamethasone, on cerebrospinal fluid (CSF) concentration of prostaglandin (PG) E2 and on febrile response induced by CCL3/MIP1alpha. I.c.v. administration of CCL3/MIP1alpha evokes an integrated fever accompanied by a reduction in tail skin temperature and an increase in PGE2 concentration in the CSF. Dexamethasone and indomethacin markedly reduced the fever and the elevation of CSF PGE2 concentration induced by lipopolysaccharide (LPS) whereas both response evoked by i.c.v. CCL3/MIP1alpha were insensitive to this steroid. Indomethacin only blocked the PGE2 increase in the CSF whereas ibuprofen and celecoxib each blocked the fever and the elevation of CSF PGE2. In this study, we have demonstrated for the first time that CCL3/MIP1alpha evokes an integrated febrile response accompanied by an increase of PGE2 levels in the CSF. These events are dissociated, especially in animals treated with indomethacin. If PGE2 does not participate in the febrile response evoked by CCL3/MIP1alpha, the inhibition of this response by celecoxib and ibuprofen indicates additional mechanisms to the well-known inhibition of COX enzymes by these drugs. Such mechanisms do not seem to depend on cytokine synthesis and subsequent COX-2 induction.

Dual inhibitory effects of furonaphthoquinone compound on enzyme activity and lipopolysaccharide-induced expression of cyclooxygenase-2 in macrophages

2-Methyl-2-(2-methylpropenyl)-2,3-dihydronaphtho[2,3-b]furan-4,9-dione (NFD-37) is a synthetic furonaphthoquinone compound. In the present study, the NFD-37 compound was found to inhibit prostaglandin (PG) E(2) production in lipopolysaccharide (LPS)-stimulated macrophages RAW 264.7. NFD-37 compound exhibited a preferred inhibition on enzyme activity of cyclooxygenase (COX)-2 over COX-1. Further, NFD-37 compound attenuated LPS-induced synthesis of both mRNA and protein of COX-2, and suppressed LPS-induced COX-2 promoter activity in the macrophages, indicating that the furonaphthoquinone compound could down-regulate LPS-induced COX-2 expression at the transcription level. Even though COX-2 promoter behaves as a sophisticated biosensor for host defense, nuclear factor (NF)-kappaB activation has been evidenced to play a major mechanism for LPS-induced COX-2 expression in macrophages. NFD-37 compound exhibited a dose-dependent inhibitory effect on LPS-induced phosphorylation of inhibitory kappaBalpha (IkappaBalpha) protein, and subsequently inhibited IkappaBalpha degradation, DNA binding activity of NF-kappaB complex as well as NF-kappaB transcriptional activity in macrophages RAW 264.7. In another experiment, NFD-37 compound inhibited both COX-2 promoter activity and GST-IkappaBalpha phosphorylation elicited by an expression vector encoding IkappaB kinase beta. Taken together, NFD-37 compound inhibited enzyme activity of COX-2 but also suppressed COX-2 expression depending on NF-kappaB activation, and thus could provide an invaluable tool to investigate pharmacological potential in the excess PG-related disorders.

Study of interaction between ibuprofen and nicotinamide using differential scanning calorimetry, spectroscopy, and microscopy and formulation of a fast-acting and possibly better ibuprofen suspension for osteoarthritis patients

Solid-state interaction between ibuprofen and nicotinamide was studied using thermal, spectroscopic, and microscopic techniques. Solubility enhancement was calculated by high-performance liquid chromatography and suspension was found to be the suitable choice of formulation. Ibuprofen-nicotinamide binary mixtures were prepared by solvent evaporation method. Differential scanning calorimetry was used to investigate the stoichiometry and thermal properties of the complex between ibuprofen and nicotinamide. A sharp, single endotherm was observed between the melting endotherms of the individual components at a composition of 60% ibuprofen and 40% nicotinamide (w/w). Several spectroscopic techniques such as ultraviolet-visible, Fourier transform infrared, nuclear magnetic resonance, and powder X-ray diffraction were used to investigate the type of interaction between the two components. Optical microscopy was performed to observe changes with regard to particle size and crystal habit. It was concluded that the interaction that occurred was Pi donor-Pi acceptor in nature and too weak to sustain the integrity of the complex in the liquid state. The solubility of ibuprofen was enhanced by 62 times in the suspension when the concentration of nicotinamide was 13.3 mg/mL. The suspension prepared in this study has potential of being a better medication for pain relief in patients with osteoarthritis.

Dual effects of acetylsalicylic acid on mast cell degranulation, expression of cyclooxygenase-2 and release of pro-inflammatory cytokines

Several studies have demonstrated that nonsteroidal anti-inflammatory drugs, such as acetylsalicylic acid (ASA), can have inhibitory or enhancing effects on inflammatory cell function. These effects seem independent of cyclooxygenase activity and prostaglandin synthesis inhibition. Here, we examined the effect of ASA on bone marrow-derived mast cells in more detail. ASA blocked the expression of cyclooxygenase-2, the production of tumor necrosis factor-alpha and interleukin-6, and the release of granule mediators from mast cells in a concentration-dependent fashion. Concomitantly, ASA inhibited nuclear factor (NF)-kappaB activity, as well as the phosphorylation and breakdown of the inhibitory protein IkappaB-alpha. We thus propose that the anti-inflammatory effects of ASA in mast cells are due to suppression of IkappaB kinase activity, thereby inhibiting subsequent phosphorylation and degradation of IkappaB-alpha, activation of NF-kappaB, and transcription of proinflammatory cytokines. The inhibition of BMMC degranulation was independent of NF-kappaB activation, however. Interestingly, the expression of cyclooxygenase-2 was not inhibited at 1mM ASA, but was even enhanced significantly. The latter might contribute to the adverse effects of ASA in ASA-sensitive asthmatics.

Effects of Nimesulide, a Selective Cyclooxygenase-2 Inhibitor, on Cardiovascular Alterations in Endotoxemia

Prostanoids and cytokines are known to play a pivotal role in the mechanisms leading to endotoxin-induced cardiovascular failure. We investigated the effect of nimesulide (NIM), a selective cyclooxygenase-2 (COX-2) inhibitor, on the cardiovascular alterations occurring during endotoxemia, and on prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) levels in endotoxemic rats. NIM significantly reduced endotoxin-induced elevation of plasma and myocardial levels of TNF-alpha, but not those of IL-1beta. Searching for the mechanism underlying the anti-TNF-alpha effect of NIM, it was found that the drug reduced nuclear factor kappa B activation through diminished nuclear levels of p-65 accompanied by a protective effect against the cardiovascular alterations and mortality seen during endotoxemia. In addition, the inhibitory effect of NIM on endotoxin-induced elevation in plasma and hypothalamic levels of PGE2 was noteworthy, and this may suggest that the large amounts of PGE2 observed during endotoxemia are mainly produced via COX-2.

Ibuprofen Inhibits Survival of Bladder Cancer Cells by Induced Expression of the p75NTR Tumor Suppressor Protein

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to reduce inflammation and as analgesics by inhibition of cyclooxygenase-2. At higher concentrations, some NSAIDs inhibit proliferation and induce apoptosis of cancer cells. Although several molecular mechanisms have been postulated to explain the anticancer effects of NSAIDs, they do not involve merely the inhibition of cyclooxygenase-2, and a more proximate initiator molecule may be regulated by NSAIDs to inhibit growth. The p75 neurotrophin receptor (p75NTR) is a proximate cell membrane receptor glycoprotein that has been identified as a tumor and metastasis suppressor. We observed that NSAID treatment of cell lines from bladder and other organs induced expression of the p75NTR protein. Of the different types of NSAIDs examined, ibuprofen was more efficacious than aspirin and acetaminophen and comparable with (R)-flurbiprofen and indomethacin in induction of p75NTR protein expression. This rank order NSAID induction of the p75NTR protein correlated with the ability of these NSAIDs to reduce cancer cell survival. To examine a mechanistic relationship between ibuprofen induction of p75NTR protein and inhibition of survival, bladder cancer cells were transfected with ponasterone A-inducible vectors that expressed a death domain-deleted (DeltaDD) or intracellular domain-deleted (DeltaICD) p75NTR product that acts as a dominant negative antagonist of the intact p75NTR protein. Expression of DeltaDD and DeltaICD rescued cells from ibuprofen inhibition of growth. These observations suggest that p75NTR is an important upstream modulator of the anticancer effects of NSAIDs and that ibuprofen induction of the p75NTR protein establishes an alternate mechanism by which ibuprofen may exert an anticancer effect.

In vitro study of regulation of IL-6 production in bronchiectasis

Persistent airway inflammation is an important pathogenetic factor in bronchiectasis, and interleukin (IL)-6 is among the mediators implicated in regulation of inflammation in bronchiectatic airways. We postulated that airway secretion with its constituents of cytokines and enzymes would provide an environment for perpetuation of inflammation in vivo. We aimed to determine the action of sputum from patients with bronchiectasis on IL-6 production from cultured normal human bronchial epithelial (NHBE) cells and its modulation by anti-inflammatory drugs in vitro. Cultures of NHBE cells were tested with (i) sputum of bronchiectatic patients, (ii) anti-tumor necrosis factor-alpha (TNF-alpha) pre-treated sputum, or (iii) recombinant human (rh)-TNF-alpha. Alternatively, NHBE cells were incubated with one of the anti-inflammatory drugs before treatment with sputum or rh-TNF-alpha. IL-6 produced into the medium was assayed by ELISA. Sputum in bronchiectasis stimulated IL-6 production from NHBE cells by 1.9 times. This was largely attributable to TNF-alpha as pre-incubation of sputum sol with anti-TNF-alpha almost neutralized the sputum effect. Apart from dexamethasone, the other drugs exerted inhibitory effects on IL-6 production. Ibuprofen suppressed sputum-stimulated IL-6 production to levels above control and effect levelled off at 50-100 microg/mi, contrasting the dose-dependent suppression to control level with MK-663 (0.1-10 microg/ml) and to sub-control levels with triptolide (20-1000 ng/ml). Our results support that sputum in bronchiectasis can stimulate IL-6 production from NHBE cells, and TNF-alpha is an important cytokine mediating the process. The suppressive effects observed with ibuprofen, triptolide and MK-663 warrant further study.

Nimesulide and diclofenac inhibit lipopolysaccharide-induced hypothermia and tumour necrosis factor-alpha elevation in rats

The effects of nimesulide and diclofenac on lipopolysaccharide (LPS)-induced rectal temperature changes and serum tumour necrosis factor (TNF)-alpha elevation were investigated in rats. LPS (Escherichia coli O111:B4; 50 microg/kg, intraperitoneally) produces a dual body temperature response, in which initial hypothermia precedes fever. Serum TNF-alpha levels rise during the initial phase of the induced hypothermia. Nimesulide, a preferential inhibitor of cyclooxygenase-2 (0.05, 0.5 or 1 mg/kg, subcutaneously) completely abolished the hypothermia, resulting in an acceleration of the fever phase. However, the peak and plateau phases of fever were not changed by nimesulide treatment. Nimesulide (0.5 mg/kg) partially prevented serum TNF-alpha elevation. The non-selective cyclooxygenase inhibitor diclofenac inhibited hypothermia at all doses tested (0.03, 0.3 or 3 mg/kg, subcutaneously) although fever was completely abolished at the 3 mg/kg dose only. Diclofenac also partially abolished the elevation in serum TNF-alpha levels, but at the highest dose only (3 mg/kg). These data suggest that nimesulide and diclofenac can preferentially inhibit LPS-induced hypothermia at doses that do not abolish fever in rats. Both these drugs also reduced elevated TNF-alpha levels, a fact which may, at least partly, explain the antihypothermic effect of nimesulide.