Non-steroidal anti-inflammatory drugs might also be pro-inflammatory by increasing tumor necrosis factor

Electroacupuncture alleviates intestinal inflammation and barrier dysfunction by activating dopamine in a rat model of intestinal ischaemia

BACKGROUND

To investigate whether the mechanism underlying the anti-inflammatory effects of electroacupuncture (EA) at ST36 involves dopamine (DA) and its receptor and whether it is mediated by the vagus nerve in a rat model of intestinal ischaemia-reperfusion (I/R) injury.

METHODS

Rats were subjected to gut ischaemia for 30 min and then received EA for 30 min with or without abdominal vagotomy or intraperitoneal administration of butaclamol (D1 receptor antagonist) or spiperone (D2 receptor antagonist). Plasma levels of DA and tumour necrosis factor (TNF)-α were assessed 1 or 4 h after reperfusion. Myeloperoxidase (MPO) activity and malondialdehyde (MDA) content in intestinal tissues were assessed using enzyme-linked immunosorbent assay (ELISA) kits. Intestinal tissue injury was assessed by observation of the pathological lesions and permeability to 4 kDa fluorescein isothiocyanate (FITC)-dextran.

RESULTS

EA significantly increased levels of DA and lowered levels of TNF-α. EA also inhibited intestinal levels of MPO and MDA and intestinal tissue injury and decreased intestinal permeability to FITC-dextran. Abdominal vagotomy and intraperitoneal administration of butaclamol (but not spiperone) inhibited the effects of EA.

CONCLUSION

These findings suggest that EA at ST36 could attenuate intestinal I/R-induced inflammatory injury and that the underlying mechanism may involve EA-induced increases in levels of DA, mediated by the vagus nerve and D1 receptors.

The Relationship Between Nonsteroidal Anti-inflammatory Drug Use and Age-related Macular Degeneration

PURPOSE

To describe the relationship between the incidence of age-related macular degeneration (AMD) and nonsteroidal anti-inflammatory drug (NSAIDs) use.

DESIGN

Prospective cohort study.

METHODS

This study consisted of participants in the California Men's Health Study. Those who completed surveys in 2002-2003 and 2006 were included. Men who self-reported use of aspirin, ibuprofen, naproxen, valdecoxib, celecoxib, and/or rofecoxib at least 3 days per week were considered NSAID users. Patients were categorized as non-users, former users, new users, or longer-term users based on survey responses. NSAID use was also categorized by type: any NSAIDs, aspirin, and/or non-aspirin NSAIDs. Age, race/ethnicity, smoking status, education, income, alcohol use, and Charlson comorbidity index score were included in the multivariate analysis as risk factors for AMD.

RESULTS

A total of 51 371 men were included. Average follow-up time was 7.4 years. There were 292 (0.6%) and 1536 (3%) cases of exudative and nonexudative AMD, respectively. Longer-term use of any NSAID was associated with lower risk of exudative AMD (hazard ratio [HR] 0.69, 95% confidence interval [CI] 0.50-0.96, P = .029). New users of any NSAIDs (HR = 0.79, 95% CI 0.68-0.93, P = .0039) and aspirin (HR = 0.82, 95% CI 0.70-0.97, P = .018) had a lower risk of nonexudative AMD, although this trend did not persist in longer-term users. The relationship between exudative or nonexudative AMD and the remaining categories of NSAID use were not significant.

CONCLUSION

The overall impact of NSAIDs on AMD incidence is small; however, the lower risk of exudative AMD in longer-term NSAID users may point to a protective effect and deserves further study as a possible mechanism to modulate disease risk.

Protective effects of indomethacin and cyclophosphamide but not of infliximab on liver metabolic changes caused by adjuvant-induced arthritis

In the study, indomethacin, cyclophosphamide, and infliximab were administered to adjuvant-induced arthritic rats to determine if they were able to prevent the abnormalities caused by arthritis on hepatic metabolism. The drugs were administered to arthritic rats, and at the clinical onset of arthritis (day 14 after adjuvant injection), the livers were perfused to evaluate gluconeogenesis, ureagenesis, oxygen uptake, L: -lactate, pyruvate, and ammonia release from L: -alanine. The effects of the drugs on body weight gain and the signs of arthritis (paw edema, appearance of secondary lesions, and weights of lymphoid tissues) were also evaluated. Cyclophosphamide could completely prevent liver metabolic changes and the inflammatory response. Indomethacin restored ureagenesis, minimized the decrease in gluconeogenesis, and exerted a partially beneficial effect on inflammatory reactions. Infliximab did not improve arthritis-induced liver metabolic alterations or inflammatory responses. These results suggest the participation of prostaglandins, but not TNF-α, on arthritis-induced liver metabolic alterations.

Melanoma inhibition by cyclooxygenase inhibitors: role of interleukin-6 suppression, a putative mechanism of action, and clinical implications

Melanoma progression is often associated with supranormal levels of interleukin-6 (IL-6). Il-6 is an important growth factor for many cases of melanoma. A recent case report by Lejeune et al. [Melanoma Res 2006;16:263-265] of remission of an advanced melanoma during treatment with the cyclooxygenase, (COX) inhibitor rofecoxib can be explained by rofcoxib-mediated lowering of tumor-produced Il-6. Several examples of rofecoxib's ability to lower Il-6 in humans have been published recently in other settings, and many reports indicate that other commonly used COX inhibitors like aspirin, diclofenac, etodolac, indomethacin, naproxen, and many others, also lower Il-6 in humans. These studies are reviewed. The likely mechanism of COX inhibition leading to Il-6 lowering is due to the tendency for Il-6 levels to be controlled by intracellular cyclic adenosine monophosphate (cAMP). Adenylate cyclase is the rate-limiting enzyme in cAMP synthesis. Because adenylate cyclase activity is allosterically enhanced when it binds prostaglandin E, the latter increases Il-6. COX inhibition lowers prostaglandin E levels. This lowers intracellular cAMP levels. Lower cAMP results in lower Il-6 synthesis, lower levels of a required growth factor. Controlled studies are needed to define the role of COX inhibitors in melanoma treatment.

A new chapter opens in anti-inflammatory treatments: the antidepressant bupropion lowers production of tumor necrosis factor-alpha and interferon-gamma in mice

In a wide range of human diseases of inflammatory nature like Crohn's disease, pathology is mediated in part by pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF) or interferon-gamma. We show here that a commonly used generic antidepressant bupropion, in wide use worldwide to treat depression in humans for a decade now, profoundly lowers levels of TNF, interferon-gamma, and interleukin-1 beta in vivo, in a mouse lipopolysaccharide (LPS) induced inflammation model. Mice challenged with an otherwise lethal dose of LPS were protected by bupropion and levels of the anti-inflammatory cytokine interleukin-10 were increased. Previous data in rodents and humans indicate antidepressant effects of bupropion are mediated by its weak reuptake inhibition of norepinephrine and dopamine. Concordant with this, TNF suppression by bupropion in our mouse LPS model was largely abrogated by beta-adrenergic or dopamine D1 receptor antagonists but not by a D2 antagonist. TNF synthesis is controlled by an inverse relationship with intracellular cyclic adenosine monophosphate (cAMP) and stimulation of either beta-adrenoreceptors or D1 dopaminergic receptors result in increased cAMP but stimulation of D2 receptors lowers cAMP. We conclude that bupropion may suppress TNF synthesis by mediating increased signaling at beta-adrenoreceptors and D1 receptors, resulting in increased cAMP that inhibits TNF synthesis. Bupropion is well tolerated also in non-psychiatric populations and has less risk with long term use than current anti-inflammatory, immunosuppressive or TNF suppressive treatments such as prednisone, azathioprine, infliximab, or methotrexate. New anti-inflammatory treatments are needed. We believe a new chapter in antiinflammatory, TNF lowering treatment of disease has been opened. Bupropion's use for this in humans should be explored.

Effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs on the production of reactive oxygen species by activated rat neutrophils

The release of reactive oxygen specie (ROS) by activated neutrophil is involved in both the antimicrobial and deleterious effects in chronic inflammation. The objective of the present investigation was to determine the effect of therapeutic plasma concentrations of non-steroidal anti-inflammatory drugs (NSAIDs) on the production of ROS by stimulated rat neutrophils. Diclofenac (3.6 microM), indomethacin (12 microM), naproxen (160 microM), piroxicam (13 microM), and tenoxicam (30 microM) were incubated at 37 masculineC in PBS (10 mM), pH 7.4, for 30 min with rat neutrophils (1 x 10(6) cells/ml) stimulated by phorbol-12-myristate-13-acetate (100 nM). The ROS production was measured by luminol and lucigenin-dependent chemiluminescence. Except for naproxen, NSAIDs reduced ROS production: 58 +/- 2% diclofenac, 90 +/- 2% indomethacin, 33 +/- 3% piroxicam, and 45 +/- 6% tenoxicam (N = 6). For the lucigenin assay, naproxen, piroxicam and tenoxicam were ineffective. For indomethacin the inhibition was 52 +/- 5% and diclofenac showed amplification in the light emission of 181 +/- 60% (N = 6). Using the myeloperoxidase (MPO)/H2O2/luminol system, the effects of NSAIDs on MPO activity were also screened. We found that NSAIDs inhibited both the peroxidation and chlorinating activity of MPO as follows: diclofenac (36 +/- 10, 45 +/- 3%), indomethacin (97 +/- 2, 100 +/- 1%), naproxen (56 +/- 8, 76 +/- 3%), piroxicam (77 +/- 5, 99 +/- 1%), and tenoxicam (90 +/- 2, 100 +/- 1%), respectively (N = 3). These results show that therapeutic levels of NSAIDs are able to suppress the oxygen-dependent antimicrobial or oxidative functions of neutrophils by inhibiting the generation of hypochlorous acid.

Feedback between glial tumor necrosis factor-alpha and gp120 from HIV-infected cells helps maintain infection and destroy neurons

An envelope glycoprotein, gp20, of the human immunodeficiency virus (HIV) interacts with host systems to promote HIV replication. gp120 is also involved in tissue-destructive positive feedback cycles that contribute to HIV-related but non-lymphocytic-, non-immunodeficiency-related tissue-destructive morbidity. Exposure to gp120 results in tumor necrosis factor-alpha (TNF) upregulation, particularly in cells of monocyte lineage. The resultant increased TNF in the microenvironment of the TNF-producing monocyte lineage cells results in increased occupancy of TNF receptors on nearby lymphocytes, monocytes or glia in which HIV does replicate. Such TNF binding increases HIV replication. Increased replication results in increased gp120 available to bind to monocyte lineage cells, further increasing or maintaining those cells' TNF production in the face of other TNF suppressive forces. A trophic environment (TNF) for HIV replication is thereby maintained. gp120 raises cAMP levels. Increased cAMP is inherently TNF-suppressive. This is a moderating negative feedback element embedded within the larger positive feedback cycle. HIV does not effectively replicate in neurons yet many HIV infections show significant neuron loss. gp120 stimulates glia to synthesize TNF. Increased TNF stimulates HIV to replicate in the cells present in which HIV is able to replicate. TNF also damages nearby neurons. The resultant increased gp120 would further stimulate glia, and the stimulated glia's TNF would damage local neurons. Damaged neurons make factors that activate glia to upregulate TNF synthesis. These feedback cycles centering on gp120 and TNF contribute to HIV pathophysiology, neuron loss and maintenance of infection.

Mechanisms of NSAID-induced hepatotoxicity: focus on nimesulide

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with idiosyncratic hepatotoxicity in susceptible patients. The molecular mechanisms underlying this toxicity have not yet been fully elucidated. However, experimental evidence suggests that they include increased concentration of the drugs in the hepatobiliary compartment, formation of reactive metabolites that covalently modify proteins and produce oxidative stress, and mitochondrial injury. Genetic and/or acquired patient factors can either augment the pathways leading to hepatic toxicity or impede the protective and detoxifying pathways. An example is nimesulide, a selective cyclo-oxygenase-2 inhibitor widely used for the treatment of inflammatory and pain conditions, which has been recently associated with rare but serious and unpredictable adverse reactions in the liver (increases in serum aminotransferase activities, hepatocellular necrosis, and/or intrahepatic cholestasis). Similar to other drugs causing idiosyncratic hepatotoxicity, both the molecule and the patient contribute to the hazard. Here, the weakly acidic sulfonanilide drug undergoes bioreductive metabolism of the nitroarene group to reactive intermediates that have been implicated in oxidative stress, covalent binding, and mitochondrial injury. It is only in a small number of susceptible patients, however, that genetic or nongenetic factors will cause this potential toxicity to become clinically manifest. In view of the very large recipient population, the incidence of nimesulide-induced liver injury has been low (approximately 0.1 per 100,000 patients treated). Although this estimation is based on spontaneous reporting data versus sales units and needs correction due to the classical bias of this system, the type and incidence of these rare but severe hepatic adverse reactions are comparable to that of other NSAIDs.

Borage oil reduction of rheumatoid arthritis activity may be mediated by increased cAMP that suppresses tumor necrosis factor-alpha

Recent double blind studies have shown some benefit of borage oil in treatment of rheumatoid arthritis. Tumor necrosis factor-alpha has been shown to be a central mediator of inflammatory and joint destructive processes in rheumatoid arthritis. In this paper, evidence from published research is reviewed that indicates gamma linolenic acid component of borage oil increases prostaglandin E levels that increase cAMP levels that in turn suppress tumor necrosis factor-alpha synthesis. If this biochemical path of borage oil is correct then (1) concomitant non-steroidal anti-inflammatory drug use would tend to undermine borage oil effects, and (2) borage oil would be contraindicated in pregnancy given the teratogenic and labor inducing effects of prostaglandin E agonists.

Tumor necrosis factor has positive and negative self regulatory feed back cycles centered around cAMP

This paper reviews data that allow recognition of, (1) two opposing intracellular chains of events occurring subsequent to an increase in tumor necrosis factor, TNF, and (2) that these two chains have opposing effects on intracellular cyclic adenosine monophosphate, cAMP. The two chains - attenuation cycle, where TNF results in prostaglandin E mediated increased cAMP and, consequent to this, suppression of TNF levels; and an amplification cycle, where increased TNF increases intracellular cyclic adenosine phosphodiesterase, lowering cAMP, thereby raising TNF levels further. TNF is a central mediator in several inflammatory diseases. Understanding TNF control systems will allow better delineation of pathophysiology and clinical care.