Light Emitting Diode Photobiomodulation Enhances Oxidative Redox Capacity in Murine Macrophages Stimulated with Bothrops jararacussu Venom and Isolated PLA2s.

Photobiomodulation therapy associated with conventional antivenom treatment has been shown to be effective in reducing the local effects caused by bothropic venoms in preclinical studies. In this study, we analyzed the influence of photobiomodulation using light emitting diode (LED) on the oxidative stress produced by murine macrophages stimulated with Bothrops jararacussu venom and it isolated toxins BthTX-I and BthTX-II. Under LED treatment, we evaluated the activity of the antioxidant enzymes catalase, superoxide dismutase, and peroxidase as well as the release of hydrogen peroxide and the enzyme lactate dehydrogenase. To investigate whether NADPH oxidase complex activation and mitochondrial pathways could contribute to hydrogen peroxide production by macrophages, we tested the effect of two selective inhibitors, apocynin and CCCP3, respectively. Our results showed that LED therapy was able to decrease the production of hydrogen peroxide and the liberation of lactate dehydrogenase, indicating less cell damage. In addition, the antioxidant enzymes catalase, superoxide dismutase, and peroxidase increased in response to LED treatment. The effect of LED treatment on macrophages was inhibited by CCCP3, but not by apocynin. These findings show that LED photobiomodulation treatment protects macrophages, at least in part, by reducing oxidative stress caused B. jararacussu venom and toxins.

Photobiomodulation induces murine macrophages polarization toward M2 phenotype.

Photobiomodulation using light-emitting diode (LED) treatment has analgesic and anti-inflammatory effects which can be an effective therapeutic associated with serum therapy for local treatment of snakebites. Here we explored the effects of LED treatment on isolated macrophage under Bothrops jararacussu venom. Results showed that LED induced IL-6 and TNF-α genes down-regulation and, TGF and ARG1 genes up-regulation which indicates a polarization of macrophages to an M2 phenotype contributing to both tissue repair and resolution of inflammation.

Effect of light emitting diode photobiomodulation on murine macrophage function after Bothrops envenomation.

Several reports have suggested that photobiomodulation, owing to its analgesic, anti-inflammatory, and healing effects, may be an effective therapeutic option for local effects of snakebites when the availability and accessibility of conventional serum therapy are inefficient and far from medical care centers. Although there have been studies that demonstrate the application of photobiomodulation in the treatment of local adverse events due to snakebites from snakes of the genus Bothrops, its role in the activation of leukocytes, particularly macrophages, has not been evaluated. Here, we assessed the effect of light-emitting diode (LED) treatment on macrophage activation induced by B. jararacussu venom (BjV). LED treatment caused an increase in the viability of macrophages incubated with BjV. This treatment reduced reactive oxygen species (ROS) and nitric oxide (NO) production by macrophages after incubation with BjV. However, LED treatment did not interfere with IL-1ß and IL-10 production by macrophages after incubation with BjV. In conclusion, this study showed that LED treatment has the potential to be used in combination with conventional serum therapy to prevent or minimize the progression of local to severe symptoms after Bothrops envenomation.

Pulmonary mechanic and lung histology injury induced by Crotalus durissus terrificus snake venom.

In the present work we investigated the effects of Crotalus durissus terrificus venom (CdtV) on the pulmonary mechanic events [static and dynamic elastance, resistive (DeltaP1) and viscoelastic pressures (DeltaP2)] and histology after intramuscular injection of saline solution (control) or venom (0.6 microg/g). The static and dynamic elastance values were increased significantly after 3 h of venom inoculation, but were reduced at control values in the other periods studied. The DeltaP1 values that correspond to the resistive properties of lung tissue presented a significant increase after 6h of CdtV injection, reducing to basal levels 12h after the venom injection. In DeltaP2 analysis, correspondent to viscoelastic components, an increase occurred 12 h after the venom injection, returning to control values at 24 h. CdtV also caused an increase of leukocytes recruitment (3-24 h) to the airways wall as well as to the lung parenchyma. In conclusion, C. durissus terrificus rattlesnake venom leads to lung injury which is reverted, after 24 h of inoculation.

Role of cyclooxygenases in oedema-forming activity of bothropic venoms.

The venoms of Bothrops asper (BaV) and Bothrops jararaca (BjV), two of the most medically important poisonous snakes of Latin America, cause pronounced oedema in the victims through poorly understood mechanisms. In the present study, we examined the possible role of cyclooxygenases (COX) in the genesis of mouse paw oedema caused by BaV and BjV injections. BaV at 2.5 microg/paw and BjV at 0.75 microg/paw induced significant oedema that persisted for up to 6h following subplantar injection. Treatment with indomethacin (2 mg/kg), rofecoxib, (10 mg/kg), or dexamethasone (2 mg/kg) significantly reduced the BaV- and BjV-induced oedema formation. Treatment with SC-560 (30 mg/kg) significantly reduced the oedema formation induced by BjV but had no effect on that induced by BaV. Both venoms induced significant increases in the levels of prostaglandin E(2) (PGE(2)) and the expression of COX-1 and COX-2 in paw tissue. The peak of oedema formation and PGE(2) release correlated with marked expression of COX-2 in the paw tissue. These results demonstrate that injection of BaV and BjV results in a rapid increase in oedema formation that is, at least partially, mediated by arachidonic acid metabolites formed by COX-2. In the case of BjV, COX-1-derived prostanoids also appear to contribute significantly to the inflammatory changes.

Beneficial Effects of Applying Low-Level Laser Therapy to Surgical Wounds After Bariatric Surgery.

BACKGROUND: Bariatric surgery is a successful method for weight loss in cases of morbid obesity; however, as an invasive procedure, surgical complications may occur. Low-level laser therapy (LLLT) has been increasingly used due to its effectiveness in controlling the inflammatory response, accelerating tissue repair, and reducing pain. The objective of this study was to investigate photobiomodulation effects after bariatric surgery and determine the laser actions during the inflammatory process, wound healing (clinical observation), and analgesia. METHODS: This study was a randomized, placebo-controlled, clinical trial in which 85 patients underwent Roux en-Y gastric bypass (RYGB) by conventional techniques (i.e., open surgery). Patients were divided into two groups and were irradiated with LLLT at 10 different points through the surgical scar in three sessions of applications: the laser group (laser-on) consisted of 43 patients who received the CW diode laser (MMOptics), while the placebo group (laser-off) consisted of 42 patients who were treated by the same protocol but with a disabled laser. Temperature was measured by a digital thermometer in both groups, and pain was evaluated using the visual analogue scale for pain. Biochemical analysis and digital images were used to document and evaluate the inflammatory response as well as tissue repair process at the surgical wound site. RESULTS: Patients in the laser group demonstrated diminished wound temperature as erythrocyte sedimentation rate (ESR) compared with the placebo group, indicating better inflammatory process control as well as improved wound healing and reduced pain. CONCLUSIONS: LLLT applied with the described protocol led to a decrease by biochemical markers and wound temperature compared with the placebo, which indicated that LLLT was able to control the inflammatory process; in addition, seroma and pain were reduced and cicatrization was improved by this preventive procedure.

Inflammatory events induced by Lys-49 and Asp-49 phospholipases A2 isolated from Bothrops asper snake venom: role of catalytic activity.

The inflammatory events induced in the peritoneal cavity of mice by two PLA2s isolated from Bothrops asper snake venom were investigated. MT-III, an Asp-49 catalytically active enzyme and MT-II, a catalytically inactive Lys-49 variant induced increase in vascular permeability. Inhibition of enzymatic activity of MT-III with p-bromophenacyl bromide reduced this effect. MT-III induced a larger neutrophil infiltrate than MT-II. This activity was significantly reduced after inhibition of catalytic activity. Reduction in the number of neutrophils was observed when antibodies against L-selectin, CD18 or LFA-1 were used, suggesting the involvement of these adhesion molecules in the effects of both PLA2s. There was no effect with antibodies against ICAM-1 and PECAM-1. Increase in the levels of LTB4 and TXA2, as well as of IL-1, IL-6 and TNF-alpha, were observed in the peritoneal exudates induced by MT-III. MT-II did not enhance levels of eicosanoids but increased those of cytokines. It is concluded that both PLA2s induce inflammatory events in this model. Since MT-III exerts a stronger proinflammatory effect, the enzymatic phospholipid hydrolysis may be relevant for these phenomena. However, the fact that MT-II induced inflammation suggests that molecular regions distinct from the catalytic site elicit inflammatory events perhaps by interacting with specific cell membrane acceptors.

Comparison of the neurotoxic and myotoxic effects of Brazilian Bothrops venoms and their neutralization by commercial antivenom.

The venoms of some Bothrops species produce neuromuscular blockade in avian and mammalian nerve-muscle preparations in vitro. In this study, we compared the neuromuscular activities (myotoxicity and neurotoxicity) of venoms from several Brazilian species of Bothrops (B. jararaca, B. jararacussu, B. moojeni, B. erythromelas and B. neuwiedi) in chick isolated biventer cervicis muscle preparations and examined their neutralization by commercial antivenom. All of the venoms (50-200 microg/ml, n = 3 - 7 each) induced long-lasting, concentration-dependent muscle contracture and twitch-tension blockade, and also inhibited the muscle responses to acetylcholine and KCl. Preincubation of the venoms (200 microg/ml) with bothropic antivenom (0.2 ml) for 30 min at 37 degrees C prevented the twitch-tension blockade to different extents, with the protection varying from 0.5% (B. neuwiedi) to 88% (B. moojeni). Complete protection against the neuromuscular action of B. neuwiedi venom was observed only with a mixture of bothropic and crotalic antivenoms. The venoms caused either high (B. jararacussu, B. neuwiedi and B. moojeni) or low (B. jararaca and B. erythromelas) creatine kinase release. Morphologically, myonecrosis was greatest with B. jararacussu venom (98-100% of fibers damaged) and least with B. jararaca venom (74% damage). The extent of neutralization by bothropic antivenom was B. jararaca (93%)>B. erythromelas (65.8%)>B. moojeni (30.7%)>B. neuwiedi (20%)>B. jararacussu (no neutralization). Despite this variation in neutralization, enzyme-linked immunosorbent assays indicated similar immunoreactivities for the venoms, although immunoblots revealed quantitative variations in the bands detected. These results show that Bothrops venoms produce varying degrees of neuromuscular blockade in chick nerve-muscle preparations. The variable protection by antivenom against neuromuscular activity indicates that the components responsible for the neuromuscular action may differ among the venoms.

Pharmacological evidence for a presynaptic action of venoms from Bothrops insularis (jararaca ilhoa) and Bothrops neuwiedi (jararaca pintada).

Whereas the presynaptic action of Crotalus durissus terrificus venom is well-established, Bothrops venoms have historically been considered to have only postsynaptic and muscular effects. However, some studies have also suggested a presynaptic action for these venoms. In this work, we used chick biventer cervicis preparations to compare the presynaptic actions of two Bothrops venoms (B. insularis and B. neuwiedi) with that of C. d. terrificus venom. At 10 microg/ml, all venoms produced irreversible blockade of the twitch tension responses, with no reduction in acetylcholine (ACh)-induced contractures and only a slight decrease in potassium induced-contractures. The times (in min) required to produce 50% neuromuscular blockade (C. d. terrificus: 16.3+/-0.7, n = 8; B. insularis: 30.0+/-1.9, n = 5; B. neuwiedi: 42.0+/-2.0, n = 8; mean +/- SEM) were significantly different among the venoms (p < 0.01). Lowering the temperature at which the experiments were done (from 37 to 24 degrees C) prevented neuromuscular blockade by the three venoms, indicating that enzyme activity may be involved in this response. At concentrations capable of causing complete neuromuscular blockade, creatine kinase release remained close to levels seen in control preparations incubated with Krebs solution alone (500-1200 IU/l). Commercial crotalic antivenom, but not bothropic antivenom, protected against the neuromuscular blockade caused by B. insularis and B. neuwiedi venoms. These observations indicate that bothropic venoms may contain components which act presynaptically in a manner similar to C. d. terrificus venom, and that at low venom concentrations a direct action on skeletal muscle does not contribute to this presynaptic neurotoxicity.

Analgesic Effect of Light-Emitting Diode (LED) Therapy at Wavelengths of 635 and 945 nm on Bothrops moojeni Venom-Induced Hyperalgesia.

Envenoming induced by Bothrops snakes is characterized by drastic local tissue damage involving hemorrhage, myonecrosis and proeminent inflammatory and hyperalgesic response. The most effective treatment is antivenom therapy, which is ineffective in neutralizing the local response. Herein, it was evaluated the effectiveness of light-emitting diode (LED) at wavelengths of 635 and 945 nm in reducing inflammatory hyperalgesia induced by Bothrops moojeni venom (BmV) in mice, produced by an subplantar injection of BmV (1 µg). Mechanical hyperalgesia and allodynia were assessed by von Frey filaments at 1, 3, 6 and 24 h after venom injection. The site of BmV injection (1.2 cm(2) ) was irradiated by LEDs at 30 min and 3 h after venom inoculation. Both 635 nm (110 mW, fluence of 3.76 J/cm(2) and 41 s of irradiation time) and 945 nm (120 mW, fluence of 3.8 J/cm(2) and 38 s of irradiation time) LED inhibited mechanical allodynia and hyperalgesia of mice alone or in combination with antivenom treatment, even when the symptoms were already present. The effect of phototherapy in reducing local pain induced by BmV should be considered as a novel therapeutic tool for the treatment of local symptoms induced after bothropic snake bites.

Photodynamic inactivation of yeast and bacteria by extracts of Alternanthera brasiliana.

This study was undertaken to evaluate the effect of Alternathera brasiliana (Amaranthaceae) extracts as photosensitizing agents in photodynamic antimicrobial therapies (PACT) against Staphylococcus aureus, Staphylococcus epidermidis and Candida dubliniensis. The crude hexane and ethanol extracts were obtained from A. brasiliana whole plant and showed absortion from 650 to 700 nm. Also, singlet molecular oxygen (1O2) production (type II photosensitization reaction) was examined, and the results show that 1,3-diphenylisobenzofuran photodegradation was greatly enhanced in the presence of the A. brasiliana extracts. One plate in each assay was irradiated while the other was not irradiated, the number of colony-forming units per milliliter (CFU/mL) was obtained, and data analyzed by the Tukey test. The chemical composition of the extracts was determined by chromatographic and spectrometric techniques; steroids, triterpenes, and flavonoids were identified. Laser irradiation alone at 685 nm using diode laser, output power of 35 mW, and energy of 28 J/cm2, or non-irradiated crude extracts in sub-inhibitory concentration did not reduce the number of CFU/mL significantly, whereas irradiated hexane and ethanol extracts, in sub-inhibitory concentrations, inhibited the growth of these microorganisms. The photoactivation of hexane and ethanol extracts of A. brasiliana, in sub-inhibitory concentrations, using red laser radiation at 685 nm had an antimicrobial effect.

Extracts from Alternanthera maritima as natural photosensitizers in photodynamic antimicrobial chemotherapy (PACT).

This study investigated the effect of photodynamic antimicrobial chemotherapy (PACT) using extracts from Alternanthera maritima on the viability of Candida dubliniensis. Human infections constitute a great health problem. Several antifungal drugs are currently available, but their uses are limited by a number of factors, such as low potency, poor solubility, microbial resistance, and drug toxicity. Therefore, the search for new and more effective antimicrobial agents and the development of alternative therapies, such as PACT, are necessary. Crude hexane and ethanol extracts of A. maritima were produced. The prepared extracts presented absorption at 650-700 nm. For bioassays, 50 microL of culture medium, 50 microL of extract (25 mg/mL) or control, and 5 microL of a suspension of the microorganism to be tested (C. dubliniensis ATCC 778157 or ATCC 777, 10(7)CFU/mL) were placed in a sterile 96-well microtiter plate (well cross section=0.38 cm(2)). The contents of each well were irradiated with a 685-nm diode laser with an output power of 35 mW, which was distributed through the well cross section yielding an energy dosage of 28 J/cm(2). In each assay (n=6), one plate was subjected to irradiation, and one was not. For each active sample, the number of colony-forming units per milliliter (CFU/mL) was obtained, and data were analyzed by the Tukey test. The chemical compositions of the extracts were determined by chromatographic and spectroscopic techniques. The results suggest inhibition of the growth of C. dubliniensis when irradiated with a diode laser in the presence of hexane and ethanol extracts from A. maritima as photosensitizers. Laser irradiation alone or crude extracts at 25mg/mL did not significantly reduce the number of CFU/mL. Steroids, triterpenes, and flavonoids were identified in the analyzed extracts. In conclusion, the photoactivation of crude hexane and ethanol extracts of A. maritima by red laser radiation at 685 nm promoted an antimicrobial effect, showing that these natural products can be used as photosensitizers in PACT.

Citrobacter rodentium infection causes iNOS-independent intestinal epithelial dysfunction in mice.

Attaching-effacing bacteria are major causes of infectious diarrhea in humans worldwide. Citrobacter rodentium is an attaching-effacing enteric pathogen that causes transmissible murine colonic mucosal hyperplasia. We characterized colonic inflammation and ion transport at 3, 7, 10, 30, and 60 d after infection of C57Bl/6 mice with C. rodentium. Macroscopic damage score was significantly increased 7 and 10 d after infection. Colonic wall thickness was increased at 7, 10, 30, and 60 d. Myeloperoxidase (MPO) activity was significantly increased at 3, 7, and 10 d and returned to control levels by days 30 and 60. The expressions of inducible nitric oxide synthase and cyclooxygenase-2 were increased by C. rodentium infection. Significant reductions in the epithelial secretory response to carbachol, but not to electrical field stimulation or forskolin, were observed at 3 and 10 d of infection. Translocation of enteric bacteria into the mesenteric lymph nodes was observed 10 d following infection. There was no difference in response to infection between animals deficient in inducible nitric oxide synthase and wild-type controls. The COX-2 inhibitor rofecoxib caused decreased wall thickness and MPO activity at day 10. However, COX-2 inhibition did not alter infection-induced changes in ion transport. Citrobacter rodentium infection causes colonic inflammation, mucosal hyperplasia, and nitric-oxide-independent epithelial dysfunction in association with increased permeability to luminal bacteria.

Predisposition to colorectal cancer in rats with resolved colitis: role of cyclooxygenase-2-derived prostaglandin d2.

Colitis markedly increases the risk of developing colon cancer, but the underlying mechanisms are not fully understood. In a rat model of colitis, alterations in epithelial secretion, proliferation, and barrier function persist long after healing has occurred. In the present study, we examined whether rats that have recovered from a bout of colitis are more susceptible to preneoplastic lesions and whether this susceptibility is mediated by cyclooxygenase (COX)-2-derived prostaglandin (PG) D2. Colitis was induced by intracolonic administration of trinitrobenzenesulfonic acid. Six weeks later, weekly treatment with the carcinogen azoxymethane was initiated. Postcolitis rats exhibited significantly more aberrant crypt foci after azoxymethane treatment than controls. The postcolitis rats also exhibited markedly increased colonic PGD2 synthesis and elevated COX-2, H-PGD synthase, and beta-catenin expression. Treatment for 1 week with a selective COX-2 inhibitor or with a selective PGD2 receptor (DP1) antagonist significantly reduced susceptibility of postcolitis rats to aberrant crypt foci development, beta-catenin expression, and mucosal thickness. The results from this animal model suggest that prolonged elevation of COX-2-derived PGD2 synthesis after resolution of colitis may contribute significantly to colitis-associated increases in colon cancer incidence. PGD2 may therefore represent a rational target for therapies directed at reducing the incidence of colitis-associated colorectal cancer.

Effects of neutrophil depletion in the local pathological alterations and muscle regeneration in mice injected with Bothrops jararaca snake venom.

In order to study the role of neutrophils in the acute local pathological alterations induced by Bothrops jararaca snake venom, and in the process of skeletal muscle regeneration that follows, an experimental model was developed in mice pretreated with either an anti-mouse granulocyte rat monoclonal immunoglobulin G, which induces a profound neutropenia, or an isotype-matched control antibody. B. jararaca venom induced prominent haemorrhage and oedema, but only a moderate myonecrosis. No significant differences were observed in the extent of local haemorrhage, oedema and myonecrosis between neutropenic and control mice, suggesting that neutrophils do not play a determinant role in the acute pathological alterations induced by B. jararaca venom in this experimental model. Moreover, no differences were observed in skeletal muscle regeneration between these two experimental groups. In both the cases, limited areas of myonecrosis were associated with a drastic damage to the microvasculature and a scarce inflammatory infiltrate, with the consequent lack of removal of necrotic debris during the first week, resulting in a poor regenerative response at this time interval. Subsequently, a similar regenerative process occurred in both groups, and by 30 days, necrotic areas were substituted by groups of small regenerating muscle fibres. It is suggested that the drastic effect exerted by B. jararaca venom in the microvasculature precludes an effective access of inflammatory cells to necrotic areas, thereby compromising an effective removal of necrotic debris; this explains the poor regenerative response observed during the first week and the fact that there were no differences between neutropenic and control mice. As neutropenia in this model lasted only 7 days, the successful regenerative process observed at 30 days is associated with revascularization of necrotic regions and with a successful removal by phagocytes of necrotic debris in both groups.

Cell adhesion molecules involved in the leukocyte recruitment induced by venom of the snake Bothrops jararaca.

It has been shown that Bothrops jararaca venom (BjV) induces a significant leukocyte accumulation, mainly neutrophils, at the local of tissue damage. Therefore, the role of the adhesion molecules intercellular adhesion molecule-1 (ICAM-1), LECAM-1, CD18, leukocyte function-associated antigen-1 (LFA-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1) on the BjV-induced neutrophil accumulation and the correlation with release of LTB4, TXA2, tumor necrosis factor-alpha, interleukin (IL)-1 and IL-6 have been investigated. Anti-mouse LECAM-1, LFA-1, ICAM-1 and PECAM-1 monoclonal antibody injection resulted in a reduction of 42%, 80%, 66% and 67%, respectively, of neutrophil accumulation induced by BjV (250 microg/kg, intraperitoneal) injection in male mice compared with isotype-matched control injected animals. The anti-mouse CD18 monoclonal antibody had no significant effect on venom-induced neutrophil accumulation. Concentrations of LTB(4), TXA(2), IL-6 and TNF-alpha were significant increased in the peritoneal exudates of animals injected with venom, whereas no increment in IL-1 was detected. This results suggest that ICAM-1, LECAM-1, LFA-1 and PECAM-1, but not CD18, adhesion molecules are involved in the recruitment of neutrophils into the inflammatory site induced by BjV. This is the first in vivo evidence that snake venom is able to up-regulate the expression of adhesion molecules by both leukocytes and endothelial cells. This venom effect may be indirect, probably through the release of the inflammatory mediators evidenced in the present study.

Gastritis increases resistance to aspirin-induced mucosal injury via COX-2-mediated lipoxin synthesis.

Products of cyclooxygenase (COX)-2 contribute to mucosal defense. Acetylation of COX-2 by aspirin has been shown to result in the generation of 15(R)-epi-lipoxin A4, which exerts protective effects in the stomach. In gastritis, it is possible that lipoxin A4 makes a greater contribution to mucosal defense. We tested this hypothesis in the rat, by using the iodoacetamide-induced gastritis model. Iodoacetamide was added to the drinking water for 5 days. Rats were then given aspirin, and the extent of gastric damage was blindly assessed 3 h later. Gastric 15(R)-epi-lipoxin A4 and PGE2 levels were determined. The effects of pretreatment with a selective COX-2 inhibitor, rofecoxib, and of a lipoxin receptor antagonist were assessed. Effects of aspirin and the other test drugs on leukocyte adherence within mesenteric venules were assessed by intravital microscopy. Aspirin elicited greater lipoxin synthesis in the inflamed than in the normal stomach, and there was reduced gastric damage. Rofecoxib inhibited lipoxin synthesis and exacerbated aspirin-induced damage. The lipoxin antagonist also exacerbated aspirin-induced damage. In rats with gastritis, aspirin reduced leukocyte adherence (in contrast to an increase in normal rats), and this effect was reversed by rofecoxib or by the lipoxin antagonist. These results support the notion that aspirin-triggered lipoxin synthesis via COX-2 makes an important contribution to mucosal defense in both the normal and inflamed stomach.

Aspirin, but not NO-releasing aspirin (NCX-4016), interacts with selective COX-2 inhibitors to aggravate gastric damage and inflammation.

Aceylation of cyclooxygenase (COX)-2 by aspirin can trigger the formation of 15(R)-epilipoxin A4, or aspirin-triggered lipoxin (ATL). ATL exerts protective effects in the stomach. Selective COX-2 inhibitors block ATL synthesis and exacerbate aspirin-induced gastric damage. Nitric oxide-releasing aspirins, including NCX-4016, have antiplatelet effects similar to aspirin but do not cause gastric damage. In the present study, we examined whether or not NCX-4016 triggers ATL synthesis and/or upregulates gastric COX-2 expression and the effects of coadministration of NCX-4016 with a selective COX-2 inhibitor on gastric mucosal injury and inflammation. Rats were given aspirin or NCX-4016 orally and either vehicle or a selective COX-2 inhibitor (celecoxib) intraperitoneally. Gastric damage was blindly scored, and granulocyte infiltration into gastric tissue was monitored through measurement of myeloperoxidase activity. Gastric PG and ATL synthesis was measured as was COX-2 expression. Whereas celecoxib inhibited gastric ATL synthesis and increased the severity of aspirin-induced gastric damage and inflammation, coadministration of celecoxib and NCX-4016 did not result in damage or inflammation. NCX-4016 did not upregulate gastric COX-2 expression nor did it trigger ATL synthesis (in contrast to aspirin). Daily administration of aspirin for 5 days resulted in significantly less gastric damage than that seen with a single dose, as well as augmented ATL synthesis. Celecoxib reversed this effect. In contrast, repeated administration of NCX-4016 failed to cause gastric damage, whether given alone or with celecoxib. These studies support the notion that NCX-4016 may be an attractive alternative to aspirin for indications such as cardioprotection, including in individuals also taking selective COX-2 inhibitors.