Effects of anti-tumour necrosis factor, interleukin-10 and antibiotic therapy in the indometacin-induced bowel inflammation rat model

BACKGROUND: The administration of indometacin to rats increases intestinal permeability and induces inflammatory pathology of the small bowel. This represents a potential model for Crohn's disease. AIMS: To analyse the pathogenic role of T cells, tumour necrosis factor and bacterial flora in indometacin-induced changes in small bowel permeability and inflammation. METHODS: Rats were given indometacin, 13 mg/kg, on day 1 and day 2. The effects of antibiotic (metronidazole, aztreonam and amoxicillin/clavulanic acid), anti- tumour necrosis factor and interleukin-10 therapy were evaluated. The parameters used were weight change, serum haemoglobin, chromium-51 ethylenediaminetetra-acetate permeability and macro-and microscopic score on day 5. Results in conventionally harboured rats were compared with those in T-cell-free rats. Additional in vitro experiments were carried out to test the effect of metronidazole on tumour necrosis factor production. RESULTS: Indometacin administration resulted in small bowel ulcers and inflammation, independently of T cells. Metronidazole was more potent than amoxicillin/clavulanic acid and anti-tumour necrosis factor in improving the indometacin-induced small bowel inflammation. Only part of the efficacy was through improvement of increased intestinal permeability. Aztreonam and interleukin-10 had no effect. Metronidazole also suppressed in vitro lipopolysaccharide-induced tumour necrosis factor production, suggesting a therapeutic effect of this drug through the inhibition of tumour necrosis factor. CONCLUSIONS: These data implicate anaerobic bacteria and tumour necrosis factor production, but not T cells, as essential elements of the pathogenesis of indometacin-induced small bowel inflammation. Tumour necrosis factor is also involved in the change in intestinal permeability. Metronidazole was the most efficacious drug in this model, probably because it suppressed anaerobic bacteria and directly inhibited tumour necrosis factor production.     

Tumour necrosis factor antagonists and inflammatory bowel diseases: a national practice survey

Background  Although the use of tumour necrosis factor (TNF) antagonists is increasingly codified, several unresolved issues remain.
Aim  To conduct a French national survey on TNF antagonists use in inflammatory bowel disease (IBD).
Methods  A postal questionnaire was sent to all French gastroenterologists among whom 450 prescribe TNF antagonists for IBD. Only anti-TNF prescribers were invited to respond.
Results  A total of 333 questionnaires could be analysed, which represented a rate of survey completeness of 74%. Scheduled maintenance infliximab treatment was prescribed by 92% of gastroenterologists. In Crohn's disease in remission after 1 year of TNF antagonists, 77.4% of physicians continued treatment. In luminal Crohn's disease, 97% of hospital practitioners introduced infliximab as first-line anti-TNF therapy vs. 78% of physicians with nonhospital activity ( P  = 0.002); only 22.5% of gastroenterologists opted for adalimumab as first-line therapy. In Crohn's disease in remission after 6 months of azathioprine in combination with infliximab, 63.8% of practitioners discontinued azathioprine. In case of pregnancy during anti-TNF treatment, 35.1% of physicians discontinued therapy at the time of conception and did not administer anti-TNF therapy during pregnancy.
Conclusions  The attitudes of French gastroenterologists generally reflect the recommendations regarding the use of anti-TNF and concomitant immunosuppressive therapy in IBD.     

Relationships between tumour necrosis factor, eicosanoids and platelet-activating factor as mediators of endotoxin-induced shock in mice.

1. The toxicity of intravenous recombinant human tumour necrosis factor (rhTNF), a TNF fragment (TNF114-130), endotoxin and combinations of rhTNF or TNF114-130 were tested in mice. Neither rhTNF nor TNF114-130 was lethal alone, but when combined with a non-lethal dose of endotoxin, rhTNF provoked dose-dependent mortality, as did higher doses of endotoxin alone. 2. Both the toxicity and the vasopermeability changes induced by endotoxin alone were blocked by the platelet-activating factor (PAF) antagonist BN52021, indomethacin or the dual cyclo-oxygenase/lipoxygenase inhibitor BW755C. 3. The lethality of the combined low dose endotoxin/rhTNF challenge was unaffected by pretreatment with BN52021, indomethacin or BW755C, or by treatment at 6 h intervals with BN52021 or BW755C. 4. The results of these studies suggest that TNF, a putative, early mediator of septic or endotoxin shock, cannot by itself mimic all of the effects of bacterial endotoxin in the model used in this study. Apparently, TNF works synergistically with other mediators whose release is stimulated by endotoxin. 5. The results also suggest that the mechanism of shock production by the rhTNF/endotoxin combination in mice is not dependent on the early stimulation of eicosanoid or PAF synthesis by rhTNF.     

Intestinal inflammation and seizure susceptibility: understanding the role of tumour necrosis factor‐α in a rat model

Objectives The aim of the study was to evaluate the correlation between colitis and susceptibility to seizures. Methods Colitis was induced in Wistar rats by a single intracolonic administration of trinitrobenzene sulfonic acid (TNBS; 20 mg in 35% ethanol). The control group were given intracolonic vehicle. One group of rats with colitis were treated with thalidomide (150 mg/kg p.o.) daily for 14 days. The other colitis group received vehicle only. On day 15, seizure susceptibility was tested by administration of pentylenetetrazole (40 mg/kg i.p.). Colonic tissue was collected for estimation of morphological score, and malondialdehyde, superoxide dismutase, catalase and glutathione peroxidase. Tumour necrosis factor (TNF)‐α levels were measured in serum and brain samples. Key findings The colitis group showed a significant increase in seizure score and reduction in onset time compared with the control group. Thalidomide was protective against seizures, resulting in decreased seizure score and significantly delaying the onset of seizures. Thalidomide also provided significant protection against TNBS‐induced colonic damage in terms of morphological and histological score and levels of lipid peroxidation, superoxide dismutase, catalase and glutathione peroxidase in colonic tissue. The level of TNF‐α in serum was also reduced significantly whereas brain TNF‐α level was reduced but not significantly. Conclusions TNBS‐induced colitis increased seizure susceptibility to a subconvulsive dose of pentylenetetrazole; the immunomodulator thalidomide was protective.     

Lipopolysaccharide activates nuclear factor kappaB in rat intestine: role of endogenous platelet-activating factor and tumour necrosis factor

1. We examined the effect of lipopolysaccharide (LPS), a cell wall constituent of Gram negative bacteria, on nuclear factor kappaB (NF-kappaB) activation in the intestine and the roles of endogenous platelet-activating factor (PAF), tumour necrosis factor-alpha (TNF) and neutrophils. We also compared the time course of NF-kappaB activation in response to PAF and LPS. 2. Ileal nuclear extracts from LPS (8 mg kg(-1), IV)-injected rats were assayed for NF-kappaB-DNA-binding activity and identification of the subunits. Some rats were pretreated with WEB2170 (a PAF receptor antagonist), anti-TNF antibody, or anti-neutrophil antiserum. NF-kappaB p65 was localized by immunohistochemistry. An additional group was challenged with PAF (2 microg kg(-1), IV) for comparison. 3. LPS activates intestinal NF-kappaB, both as p50-p50 and p50-p65 dimers within 15 min, and the effect peaks at 2 h. The effect is slower and more sustained than that of PAF, which peaks at 30 min. Activated NF-kappaB was immunolocalized within epithelial and lamina propria cells. LPS effect was reduced by 41, 37 and 44%, respectively, in animals pretreated with WEB2170, anti-TNF antibody, or anti-neutrophil antiserum (P<0.05). 4. LPS activates intestinal NF-kappaB in vivo and neutrophil activation is involved in its action. The LPS effect is mediated by both endogenous PAF and TNF.     

The role of eicosanoids in cyclosporine nephrotoxicity in the rat

Nephrotoxicity is the most troublesome complication of cyclosporine (CSA) therapy. The present study was designed to investigate the effects of chronic treatment with CSA on the 24-hr urinary excretion of prostanoids (PGs) and thromboxane (Tx) and on the renal function in the absence or presence of indomethacin. CSA administration to Wistar rats (20 mg/kg/day, i.p.) for 14 days caused a significant increase in plasma creatinine, blood urea nitrogen (BUN), urine osmolality, fractional excretion of sodium and potassium and a reduction in creatinine clearance (CCr) and urine volume. These changes were associated with a significant reduction in urinary excretion of PGE2 (21.1 +/- 3.3 vs 33.0 +/- 2.5 ng/24 hr) and PGF2 alpha (13.4 +/- 1.4 vs 27.9 +/- 3.8 ng/24 hr) and an increase in TxB2 (12.1 +/- 3.0 vs 4.6 +/- 0.5 ng/24 hr), and 6-keto PGF1 alpha (56.2 +/- 7.7 vs 27.7 +/- 1.9 ng/24 hr). However, the synthesis of TxB2 and 6-keto PGF1 alpha by renal medullary and cortical slices prepared from CSA treated rats was not different from values obtained for vehicle treatment. In contrast, PGE2 synthesis by cortical slices prepared from the CSA group was increased. A single injection of indomethacin (10 mg/kg) to vehicle and CSA treated rats resulted in a significant reduction in PGs and TxB2 excretion. This, was associated with a further reduction in CCr (0.81 +/- 0.06 vs 1.03 +/- 0.04 ml/min) and an increase in BUN (38.5 +/- 5.2 vs 28.2 +/- 1.4 mg%) only in the CSA group. We suggest that the vasodilating PGs attenuate the renal toxic effects induced by CSA.     

Effect of cholera toxin on the production of eicosanoids by rat jejunum.

1 Cholera toxin injected i.v. into rats stimulated the production of prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and LTC4 by segments of jejunum, but it had no effect when added to the tissue in vitro. 2 Pretreatment of the animals with the compound BW 755C reduced the increased production of PGE2, LTB4 and LTC4 by i.v. cholera toxin. Pretreatment with indomethacin reduced the production of PGE2. 3 These findings are consistent with the hypothesis that arachidonate metabolites are involved in the diarrhoea induced by cholera toxin.     

Possible participation of intracellular platelet-activating factor in tumor necrosis factor-alpha production by rat peritoneal macrophages.

Stimulation of rat peritoneal macrophages by thapsigargin (46.1 nM) increased levels of tumor necrosis factor-alpha and prostaglandin E2 in the conditioned medium. Platelet-activating factor (PAF) was not detected in the conditioned medium, but the level of cell-associated PAF was increased transiently by thapsigargin. The PAF receptor antagonists such as E6123 ((S)-(+)-6-(2-chlorophenyl)-3-cyclopro-panecarbonyl-8,11-dim ethyl-2,3,4,5-tetrahydro-8 H-pyrido[4',3':4,5]thieno [3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine), L-652,73 1 (2,5-bis(3,4,5-trimethoxyphenyl) tetrahydrofuran) and CV-6209 (2-[N-acetyl-N-(2-methoxy-3-octadecyl-carbamoyloxy propoxycarbonyl)aminomethyl]-1-ethylpyridinium chloride) inhibited thapsigargin-induced production of tumor necrosis factor-alpha. The cyclooxygenase inhibitor indomethacin inhibited prostaglandin E2 production, and further enhanced thapsigargin-induced tumor necrosis factor-alpha production in parallel with further increase in cell-associated PAF production. The enhancement of tumor necrosis factor-alpha production induced by thapsigargin plus indomethacin was also inhibited by E6123, L-652,731 and CV-6209. However, exogenously added PAF up to 100 nM did not stimulate production of tumor necrosis factor-alpha. The level of tumor necrosis factor-alpha mRNA was increased by thapsigargin, but was lowered by the PAF receptor antagonist E6123, suggesting that the inhibition of tumor necrosis factor-alpha production by the PAF receptor antagonist is induced at the level of mRNA for tumor necrosis factor-alpha. These findings suggested that concurrently produced cell-associated PAF in thapsigargin-stimulated macrophages up-regulates production of tumor necrosis factor-alpha by acting as an intracellular signaling molecule and the PAF receptor antagonists might penetrate into the cells and antagonize the action of intracellular PAF.     

Sequential release of tumour necrosis factor, platelet activating factor and eicosanoids during endotoxin shock in anaesthetized pigs: protective effects of indomethacin.

1. The effects of indomethacin were investigated on haemodynamics, haematological and blood glucose values, and the release of tumour necrosis factor (TNF), platelet activating factor (PAF) and eicosanoids in anaesthetized pigs receiving 5 micrograms kg-1 E. coli lipopolysaccharide (LPS) over 60 min into the superior mesenteric artery. The animals were observed for an additional period of 2 h after the termination of LPS infusion. 2. Eight of the 17 animals infused with LPS and not treated with indomethacin died within 30 min after the beginning of LPS infusion (non-survivors), while the other 9 survived the experimental period of 3 h though in a state of shock (survivors). 3. No alterations were observed in plasma concentrations of PAF and eicosanoids (thromboxane B2 (TXB2), 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) and leukotriene B4 (LTB4] in non-survivors. However, a marked increase was detected in TNF release. A significant, though transient, increase in concentrations of PAF, TNF and eicosanoids occurred in the survivors. The peak in the concentrations of PAF and TXB2 preceded the maximum in TNF values in survivors. 4. Another group of 7 LPS-infused pigs was treated with indomethacin (2 mg kg-1, i.v. bolus 60 min before the start of LPS infusion, followed by a continuous infusion of 3 mg kg-1 h-1). This treatment prevented death and shock despite the high concentrations of circulating TNF and PAF. Concentrations of cyclo-oxygenase enzyme products were reduced, whereas LTB4 release was not affected. The effect of indomethacin on haemodynamic changes occurred earlier than on cyclo-oxygenase products.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tumour necrosis factor-alpha and leukotriene B(4) mediate the neutrophil migration in immune inflammation.

1. We investigated the mediators responsible for neutrophil migration induced by ovalbumin (OVA) in immunized mice and the mechanisms involved in their release. 2. OVA administration promoted dose- and time-dependent neutrophil migration in immunized, but not in non-immunized mice, which was mediated by leukotriene B(4) (LTB(4)) and tumour necrosis factor (TNF)alpha, since it was inhibited by LTB(4) synthesis inhibitor (MK 886) or by LTB(4) receptor antagonist (CP 105,696), by dexamethasone and by antiserum to TNFalpha (82, 85, 63 and 87%, respectively). Confirming TNFalpha involvement, OVA challenge in immunized p55 TNF receptor deficient mice (p55(-/-)) did not promote neutrophil migration (control: 2.90 +/- 0.68; p55(-/-): 0.92+/-0.23 x 10(6) neutrophils cavity(-1)). 3. OVA-stimulated peritoneal cells from immunized mice released a neutrophil chemotactic factor which mimicked, in naive mice, neutrophil migration induced by OVA. 4. Supernatant chemotactic activity is due to TNFalpha and LTB(4), since its release was inhibited by MK 886 (93%) and dexamethasone (90%), and significant amounts of these mediators were detected. 5. TNFalpha and LTB(4) released by OVA challenge seem to act through a sequential mechanism, since MK 886 inhibited (88%) neutrophil migration induced by TNFalpha. Moreover, peritoneal cells stimulated with TNFalpha released LTB(4). 6. CD(4)(+) T cells are responsible for TNFalpha release, because the depletion of this subset prevented the release of TNFalpha (control: 400 +/- 25; immunized: 670 +/- 40; CD(4)(+) depleted: 435 +/- 18 pg ml(-1)). 7. In conclusion, neutrophil migration induced by OVA depends on TNFalpha released by CD(4)(+) cells, which acts through an LTB(4)-dependent mechanism.     

Role of tumour necrosis factor in the induction of nitric oxide synthase in a rat model of endotoxin shock.

1. This study investigates the role of tumour necrosis factor (TNF) in the induction of nitric oxide synthase (NOS) by bacterial endotoxin (lipopolysaccharide; LPS) in a rat model of endotoxin shock. 2. In anaesthetized rats, pretreatment with a monoclonal antibody for TNF (TNFab; 20 mg kg-1, s.c., at 16 h prior to LPS) ameliorated the fall in mean arterial blood pressure (MAP) in response to LPS (2 mg kg-1, i.v.). For instance, endotoxaemia for 180 min resulted in a fall in MAP from 114 +/- 6 (control) to 84 +/- 5 mmHg (P < 0.01; n = 7). In contrast, animals pretreated with TNFab prior to LPS injection maintained significantly higher MAP when compared to LPS-control (MAP at 180 min; 118 +/- 3 mmHg; P < 0.01, n = 5). 3. Three hours of endotoxaemia was also associated with a significant reduction of the contractile effects of noradrenaline (NA) (10(-8)-10(-6) M) on the thoracic aorta ex vivo. This hyporeactivity to NA was partially restored by in vitro treatment of the vessels with NG-nitro-L-arginine methyl ester (L-NAME, 20 min, 3 x 10(-4) M). Pretreatment of rats with TNFab (20 mg kg-1; at 16 h prior to LPS) significantly (P < 0.05) attenuated the LPS-induced hyporeactivity of rat aortic rings ex vivo. L-NAME did not enhance the contractions of aortic rings obtained from TNFab pretreated LPS-rats. 4. At 180 min after LPS there was a significant elevation of the induced NOS activity in the lung (5.14 +/- 0.57 pmol citrulline mg-1 min-1, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pro-inflammatory effects of cholera toxin: role of tumor necrosis factor alpha.

Cholera toxin has been traditionally described as the one that does not induce inflammation. It has, however, potent adjuvant and immuno-modulatory activities. Since the adjuvanticity of other compounds is linked to their capacity to induce inflammation, in the present study the pro-inflammatory activity of cholera toxin was investigated. We studied this activity in the following rat models of inflammation: paw edema and neutrophil migration into the peritoneal cavity, and evaluated cholera toxin's effect on tumor necrosis factor alpha (TNF-alpha) production by mouse macrophages. We, also, explored the effects of dexamethasone (DEXA) and of two inhibitors of TNF-alpha production, thalidomide (TAL) and pentoxifylline, on paw swelling. Cholera toxin-induced significant and dose-dependent paw edema, which peaked 48 h after toxin challenge (Cholera toxin(2.5 microg): 2.39 +/- 0.22 ml). Cholera toxin B subunit did not show edematogenic activity. DEXA, TAL and pentoxifylline significantly reduced cholera toxin-induced edema (DEXA(0.5 mg/kg): 42.6% of inhibition; TAL(45 mg/kg): 36% of inhibition; pentoxifylline (45 mg/kg): 61% of inhibition). Neither cholera toxin nor its B subunit induced neutrophil migration into peritoneal cavities. Cholera toxin stimulated the release of TNF-alpha by macrophages (cholera toxin(10 microg): 11.46 +/- 0.44 UI/ml). These data provide evidences that cholera toxin exhibits significant pro-inflammatory activity. It also indicates the role of TNF-alpha upon the pathophysiology of this event based on the inhibitory action of DEXA, TAL and pentoxifylline, and on TNF-alpha secretion induced by cholera toxin.     

Tumour necrosis factor in chronic heart failure: a peripheral view on pathogenesis, clinical manifestations and therapeutic implications

The development of chronic heart failure (CHF) includes phenotypic changes in a host of homeostatic systems so that, as the disease advances, CHF may be seen as a multi-system disorder with its origins in the heart but embracing many extra-cardiac manifestations. Immunological abnormalities are recognised in this context, in particular, changes in the expression of mediators of the innate immune response. Higher levels of the pro-inflammatory cytokine tumor necrosis factor (TNF) are found in the circulation and in the myocardium of patients with CHF than in controls, and TNF has been implicated in a number of pathophysiological processes that are thought important to the progression of CHF. Therapies directed against this cytokine therefore represent a novel approach to heart failure management. Anti-TNF strategies in CHF may target the mechanisms of immune activation, the intracellular pathways regulating TNF production, or the fate of TNF once it has been released into the circulation. Circulating endotoxin may be an important stimulus to TNF production by circulating monocytes, tissue macrophages and cardiac myocytes in CHF and efforts to limit this phenomenon are of interest. Several established pharmacological therapies for patients with CHF, including angiotensin converting enyzme inhibitors, beta-blockers, and phosphodiesterase inhibitors may modify cellular TNF production by their action on intracellular mechanisms, whereas TNF receptor fusion proteins have been developed that target circulating TNF itself. Patients with New York Heart Association class IV symptoms, those with cardiac cachexia and those with oedematous decompensation of their disease have the highest serum TNF levels and are most likely to benefit most from such a therapeutic approach.     

Depressive and cardiovascular disease comorbidity in a rat model of social stress: a putative role for corticotropin-releasing factor

Rationale

Depression is associated with medical comorbidities, particularly cardiovascular disease. However, mechanisms linking depression and cardiovascular disease remain unclear.

Objectives

This study investigated whether the rat resident?Cintruder model of social stress would elicit behavioral dysfunctions and autonomic changes characteristic of psychiatric/cardiovascular comorbidity. Furthermore, the efficacy of the corticotropin-releasing factor-1 (CRF₁) receptor antagonist, NBI-30775 (NBI), or the tricyclic antidepressant, desipramine (DMI), to prevent social stress-induced behavioral, neuroendocrine, and cardiovascular changes were evaluated.

Methods

Adult male rats were exposed to resident?Cintruder stress (seven consecutive days) and systemically administered NBI (10?mg/kg/7?days), DMI (10?mg/kg/14?days), or vehicle. The efficacy of NBI and DMI to alter the behavioral and neuroendocrine responses to social stress was assessed. Furthermore, their effects on stress-induced forced swim behavior (FST), bladder and adrenal weight, and heart rate variability (HRV) were examined.

Results

NBI, but not DMI, increased time spent in an upright, defensive posture and the latency to submit to the resident. Additionally, only NBI reduced social stress-induced adrenocorticotropic hormone and corticosterone release. Social stress increased FST immobility, caused bladder and adrenal hypertrophy, and decreased HRV. Both NBI and DMI blocked stress-induced increases in immobility during the FST. However, only NBI inhibited social stress-induced adrenal and bladder hypertrophy and decreases in heart rate variability.

Conclusions

Rat resident?Cintruder stress paradigm models aspects of psychiatric/medical comorbidity. Furthermore, the CRF system may contribute to both the behavioral response during social stress and its behavioral and autonomic consequences, offering insight into potential therapy to treat these comorbid conditions.     

Tumour necrosis factor alpha augments the release of an endothelium-dependent vasoconstrictor from human polymorphonuclear leukocytes.

We have studied the effect of cytokine priming by recombinant human tumour necrosis factor alpha (rhTNF alpha) on the release of vasoactive mediators from human polymorphonuclear leukocytes (PMNs). Supernatants of human PMNs (100 microliters, 5 x 10(7) ml, from 12 donors) relaxed precontracted rabbit aortic rings. The relaxations were preceded by a transient contraction in four experiments. In contrast, supernatants of PMNs incubated with rhTNF alpha (0.3 nM, 30 min, 37 degrees C) elicited variable vascular responses that consisted of either a sustained contraction (n = 4), a transient contraction followed by a sustained relaxation (n = 2), or a sustained relaxation only (n = 6). The vascular tone produced by the rhTNF alpha-treated PMN supernatant was significantly greater over 30 min than that produced by the control supernatant (p < 0.01). Endothelium removal prevented the PMN-induced contractions and significantly decreased the vascular tone produced by all rhTNF alpha-treated PMN supernatants (p < 0.05). The PMN supernatants had no vasoactive effect on aortic rings at resting tension. Molecular size analysis indicated that the PMN-derived contractile mediator is > 30,000 Da. These results suggest that human PMNs, primed by rhTNF alpha, release a stable endothelium-dependent vasoconstrictor that opposes the action of a stable, spontaneously released direct vasodilator.     

The role of epidermal growth factor in mucus production.

Airway hypersecretion is a serious and presently untreatable symptom of chronic inflammatory airway diseases. Recently, it has been discovered that epithelial growth factor receptor expression and activation causes mucin production in airways. An epithelial growth factor receptor pathway is implicated in mucus cell differentiation induced by various stimuli; therefore, inhibition of the epithelial growth factor receptor transduction cascade may provide effective new treatments for hypersecretory airway diseases.     

Collagenase production in the exudate of a novel adjuvant-induced air pouch inflammation model in rats.

To elucidate the role of collagenase in tissue destruction in chronic inflammation (e.g., in rheumatoid arthritis), we established a novel air pouch model in rats. Ten ml of air was injected subcutaneously on the dorsa of F344 rats, and 24 hours thereafter, Freund's complete adjuvant was injected into the air pouch. A remarkably high activity of trypsin-activated collagenase was detected dose-dependently in the pouch fluid at 8 days after the challenge injection. Concomitantly with the increase of collagenase activity, the weight of granuloma formed in the pouch decreased, suggesting that collagenase participates in the resorption of granuloma tissues.     

Cyclooxygenase-2 protein and prostaglandin E(2) production are up-regulated in a rat bladder inflammation model

Cyclooxygenase-1 and cyclooxygenase-2 mRNAs and proteins and prostaglandin E(2) production are evaluated in a rat model of inflammation in which Escherichia coli lipopolysaccharide is intraperitoneally injected or intravesically instilled into the bladder. While cyclooxygenase-1 mRNA and protein and cyclooxygenase-2 mRNA do not change in bladders treated with lipopolysaccharide, cyclooxygenase-2 protein is elevated in bladders from rats intravesically instilled with lipopolysaccharide or phosphate buffered saline (PBS) or intraperitoneally injected with lipopolysaccharide. Urinary prostaglandin E(2) levels and prostaglandin E(2) synthesis in bladder particulates are elevated by intravesical instillation and intraperitoneal injection of lipopolysaccharide. The nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine, increases prostaglandin E(2) synthesis in bladders from lipopolysaccharide intravesically instilled and intraperitoneally injected rats. Lipopolysaccharide increases prostaglandin E(2) synthesis by increasing cyclooxygenase-2 protein levels in rat bladder and prostaglandin E(2) synthesis may be further elevated by increases in nitric oxide caused by an up-regulation of inducible nitric oxide synthase (iNOS).     

A rat pharmacokinetic/pharmacodynamic model for assessment of lipopolysaccharide-induced tumor necrosis factor-alpha production

INTRODUCTION: Tumor necrosis factor-alpha (TNFalpha) participates in many inflammatory processes. TNFalpha modulators show beneficial effects for the treatment of many diseases including rheumatoid arthritis. The purpose of this study was to validate a rat pharmacokinetic/pharmacodynamic (PK/PD) model for rapid assessment of drug candidates that intended to interrupt TNFalpha synthesis or release. METHODS: Rats received intravenous (IV) or oral administrations of test article or dose vehicle, followed by LPS challenge. Plasma levels of test article and TNFalpha were determined. The areas under the concentration-time curves (AUC(drug) and AUC(TNFalpha)) were calculated. The overall percentage of inhibition on TNFalpha release in vivo was calculated by comparing AUC(TNFalpha) of the test article treated group against that for the vehicle control group. RESULTS: The dosing vehicles tested in this study did not increase plasma TNFalpha level. At IV dose of up to 100 microg/kg, LPS did not alter the pharmacokinetics of the compound tested. Using a selective TNFalpha converting enzyme (TACE) inhibitor as model compound, this PK/PD model demonstrated its ability to correlate plasma test article concentration with its biological activity of lowering the LPS-induced TNFalpha plasma levels in vivo. DISCUSSION: A rat PK/PD model for evaluation of the effect of drug candidates on LPS-induced TNFalpha synthesis and/or release has been investigated. This model provides integrated information on pharmacokinetics and in vivo potency of the test articles.