Zymosan In Mice Research Articles

The Tea and Polysaccharide Fractions of Ximenia americana Stem Barks Inhibits Inflammatory Parameters Induced by Zymosan in Mice

Ximenia americana or “ameixa-do-sertão” is a plant used in the folk medicine of Northeast-Brazil in inflammatory and painful processes. The literature has shown anti-inflammatory and antinociceptive activities for the aqueous or hydroalcoholic extracts and polysaccharide fractions of X. americana stem barks. This study investigated the anti-inflammatory effect of polysaccharide fractions and tea prepared from X. americana stem barks in mice models of paw edema and peritonitis induced by zymosan. Tea (50,100, 150 mg/kg; p.o.) and polysaccharide fractions (FI, FII: 1 mg/kg; i.v.), containing carbohydrate (44.8, 25.0, 44.4%) and polyphenols (28.3, 0.78, 1.50%), respectively, were administered 1 h before zymosan (500 mg; s.c. or i.p). FT-IR analysis of the tea showed bands indicating C=O and C-O groups vibration, typical of phenolic compounds. Zymosan-induced paw edema (AUC: 355.0 ± 38.1) was inhibited by the tea by 38% (100 mg/kg) and 36% (150 mg/kg). FI and FII reduced the edema by 47% (933.8 ± 158.1 AUC) and 30% (1263 ± 124.8 AUC), respectively. Zymosan i.p. induced hypernociception (4.7 ± 0.3 g) and increased the peritoneal leukocyte migration (10979 ± 1475 cells/ml). FII increased by 66% the nociceptive threshold (13.87 ±1.59 g) and reduced by 63% leukocyte migration (3993 ± 439.1 cells/ml). FII decreased plasma protein by 64% (92.6 ± 4.5 vs. zymosan: 119.6 ± 5.4 mg/ml) and MDA by 63% (57.5 ± 3.5 vs. zymosan: 88.9 ± 6.3 mg/ml). The tea, containing polysaccharides and polyphenols, and polysaccharide fractions FI/FII of X. americana barks possess antiinflammatory effect in mice models of acute inflammation induced by zymosan.

Inhibition of spinal p38 MAPK prevents articular neutrophil infiltration in experimental arthritis via sympathetic activation.

The central nervous system controls the innate immunity by modulating efferent neuronal networks. Recently, we have reported that central brain stimulation inhibits inflammatory responses. In the present study, we investigate whether spinal p38 mitogen-activated protein kinase (MAPK) affects joint inflammation in experimental arthritis. Firstly, we observed that intra-articular administration of zymosan in mice induces the phosphorylation of the spinal cord p38 MAPK. In addition, we demonstrated that spinal p38 MAPK inhibition with intrathecal injection of SB203580, a conventional and well-characterized inhibitor, prevents knee joint neutrophil recruitment, edema formation, experimental score and cytokine production. This local anti-inflammatory effect was completely abolished with chemical sympathectomy (guanethidine) and beta-adrenergic receptors blockade (nadolol). In conclusion, our results suggest that pharmacological strategies involving the modulation of spinal p38 MAPK circuit can prevent joint inflammation via sympathetic networks and beta-adrenoceptors activation.

Zymosan-Induced Peritonitis: Effects on Cardiac Function, Temperature Regulation, Translocation of Bacteria, and Role of Dectin-1.

Zymosan-induced peritonitis is a model commonly used to study systemic inflammatory response syndrome and multiple organ dysfunction syndrome. However, effects of zymosan on cardiac function have not been reported. We evaluated cardiac responses to zymosan in mice and the role of β-glucan and dectin-1 in mediating these responses. Temperature and cardiac function were evaluated before and after intraperitoneal (i.p.) injection of zymosan (100 or 500 mg/kg) or saline. Chronotropic and dromotropic functions were measured using electrocardiograms (ECGs) collected from conscious mice. Cardiac inotropic function was determined by echocardiography. High-dose zymosan caused a rapid and maintained hypothermia along with visual signs of illness. Baseline heart rate (HR) was unaffected but HR variability (HRV) increased, and there was a modest slowing of ventricular conduction. High-dose zymosan also caused prominent decreases in cardiac contractility at 4 and 24 h. Because zymosan is known to cause gastrointestinal tract pathology, peritoneal wash and blood samples were evaluated for bacteria at 24 h after zymosan or saline injection. Translocation of bacterial occurred in all zymosan-treated mice (n = 3), and two had bacteremia. Purified β-glucan (50 and 125 mg/kg, i.p.) had no effect on temperature or ECG parameters. However, deletion of dectin-1 modified the ECG responses to high-dose zymosan; slowing of ventricular conduction and the increase in HRV were eliminated but a marked bradycardia appeared at 24 h after zymosan treatment. Zymosan-treated dectin-1 knockout mice also showed hypothermia and visual signs of illness. Fecal samples from dectin-1 knockout mice contained more bacteria than wild types, but zymosan caused less translocation of bacteria. Collectively, these findings demonstrate that zymosan-induced systemic inflammation causes cardiac dysfunction in mice. The data suggest that dectin-1-dependent and -independent mechanisms are involved. Although zymosan treatment causes translocation of bacteria, this effect does not have a major role in the overall systemic response to zymosan.

138 - Inflammatory Generation and Pro-Resolving Signaling Actions of Conjugated Nitro-Linoleic Acid

Inflammatory responses result in the activation of pro-oxidant enzymes such as the inducible isoform of nitric oxide synthase (iNOS) and NAPDH oxidases, leading to the generation of the nitrating species nitrogen dioxide (●NO2). Conjugated linoleic acid is a primary substrate for biological nitration in the gastric compartment giving rise to the formation of conjugated nitro-linoleic acid (NO2-CLA). Herein we show that macrophage activation leads to NO2-CLA formation both in vitro and in vivo, as determined by selective reaction monitoring analysis using isotopically labeled internal standards and confirmed by high resolution mass spectrometry. CLA nitration by activated RAW264.7 cells results not only in the dose- and time-dependent formation of the parent NO2-CLA compound but also in the generation of secondary electrophilic and non-electrophilic β-oxidation metabolites. The formation of two positional NO2-CLA isomers with different metabolization rates but similar signaling potency was also observed. Addition of either mixed or pure NO2-CLA positional isomers to cells in culture led to antioxidant response element (ARE) activation and to dose-dependent expression of Nrf2-regulated genes. Similarly, NO2-CLA also attenuated TNF-α mediated NF-κB response element activation and decreased iNOS expression and pro-inflammatory cytokine release in LPS/IFN-γ activated RAW264.7 cells. To test the physiological relevance of these observations, a mouse zymosan A peritonitis model that promotes CLA nitration was utilized. Animals were administered vehicle, CLA or synthetic NO2-CLA and then polymorphonuclear cell (PMN) recruitment and clearance from the peritoneal cavity was monitored. Both synthetic and in situ CLA-derived NO2-CLA led to decreased recruitment and enhanced PMN clearance, which coincided with higher expression of Nrf2-dependent genes in peritoneal cells. Our work demonstrates that NO2-CLA generation might constitute an endogenous adaptive mechanism capable of modulating the severity of the inflammatory response by favoring resolution and inducing the expression of both cytoprotective and antioxidant genes.

The effects of agmatine on acute peritoneal inflammatory injury and neutrophil infiltration induced by zymosan in mice

To investigate the protective effect of agmatine (AGM) against peritoneal inflammatory response and neutrophil (PMN) infiltration induced by zymosan (ZYM) in mice. Thirty-six adult male C57BL/6 mice were randomly divided into sham group, model group, and AGM treatment group. Peritonitis model was reproduced by intra-peritoneal injection of 1 mg/mL ZYM (0.5 mL), while equivalent phosphate buffer saline (PBS) was given to sham group. 200 mg/kg AGM was injected into peritoneal cavity after ZYM challenge in AGM treatment group. Six mice in each group were sacrificed at 2 hours and 6 hours, respectively, after reproduction of the model. Blood sample and peritoneal lavage fluid (PLF) were collected. The levels of keratinocyte-derived chemokine (KC), macrophage inflammatory protein 2 (MIP-2), tumor necrosis factor-α (TNF-α), interleukins-6 (IL-6) in serum and PLF were determined by enzyme linked immunosorbent assay (ELISA). The number of leukocytes and PMN in PLF were determined by hemocytometer and flow cytometry, respectively. Compared with sham group, all serum and PLF levels of KC, MIP-2, TNF-α and IL-6 were greatly elevated at 2 hours after ZYM injection in model group, while AGM treatment could dramatically reduce the levels of the above-mentioned cytokines in serum and PLF as compared with those of the model group [serum KC (ng/L): 990.7±137.9 vs. 2 053.2±262.7, MIP-2 (ng/L): 642.2±124.4 vs. 1 369.7±146.5, TNF-α (ng/L): 608.6±38.1 vs. 1 044.7±101.0, IL-6 (ng/L): 1 058.2±129.1 vs. 1 443.3±190.1; PLF KC (ng/L): 7 462.3±839.6 vs. 12 723.5±1 515.7, MIP-2 (ng/L): 1 570.8±193.4 vs. 3 471.4±384.7, TNF-α (ng/L): 1 115.8±156.7 vs. 1 499.2±231.2, IL-6 (ng/L): 2 646.5±223.2 vs. 3 126.7±291.4; all P < 0.05]. The expressions of KC, MIP-2 and TNF-α at 6 hours were significantly lower than those at 2 hours in model group and AGM treatment group, but IL-6 levels were further increased. The levels of KC and MIP-2 in serum and PLF at 6 hours were decreased to the levels of sham group. At 6 hours after the reproduction of the model, the number of total inflammatory cells and PMN of PLF in the model group was significantly higher than those of the sham group. In contrast, AGM notably lowered the number of inflammatory cells and PMN in peritoneal fluid after ZYM attack [total inflammatory cells (×109/L): 14.7±1.1 vs. 2.0±0.4, 10.1±1.2 vs. 14.7±1.1; PMN (×109/L): 11.37±1.22 vs. 0.18±0.05, 7.69±0.57 vs. 11.37±1.22, all P < 0.05]. AGM can effectively alleviate acute peritoneal inflammatory injury induced by ZYM, mainly through reducing the secretion of inflammatory mediators and chemokines, and inhibiting the infiltration of leukocytes and neutrophils.

Role of Serotonin in MODS: Deficiency of Serotonin Protects Against Zymosan-Induced Multiple Organ Failure in Mice.

Zymosan-induced multiple organ dysfunction syndrome (MODS) is a multifactorial pathology that involves the deterioration of function of several organs. 5-Hydroxytryptamine (5-HT) is a small monoamine molecule that is primarily known for its role as a neurotransmitter. Previous studies have shown that 5-HT could serve as an important inflammatory mediator in the peripheral immune system. In the present study, we investigated the effect of 5-HT on the development of non-septic shock caused by zymosan in mice. Tryptophan hydroxylase 1-knockout mice (TPH1, leading to the absence of 5-HT), TPH1 + 5-hydroxytryptophan (precursor of 5-HT) treatment mice, wild-type (TPH1) mice, and wild-type plus p-chlorophenylalanine (PCPA, TPH1 inhibitor) treatment mice received zymosan intraperitoneally at a dose of 500 mg/kg. Organ failure and systemic inflammation in the mice were assessed 18 h after the administration of zymosan. Deficiency of 5-HT caused a significant reduction of the 1) peritoneal exudate formation, 2) neutrophil infiltration, 3) MODS, 4) nitrosative stress, and 5) cytokine formation. In addition, at the end of the observation period (7 days), deficiency of 5-HT in the mice was shown to be able to alleviate the severe illness characterized as systemic toxicity, significant loss of body weight, and high mortality caused by zymosan. In conclusion, the lack of 5-HT by genetic knockout or by pharmacologic inhibition of the TPH1 enzyme significantly attenuated zymosan-induced MODS.

Regulatory T Cells Are Protective in Systemic Inflammation Response Syndrome Induced by Zymosan in Mice

Systemic inflammation response syndrome (SIRS) is a key and mainly detrimental process in the pathophysiology of multiple organ dysfunction syndrome. The balance of pro-inflammation and anti-inflammation controls the initiation and development of SIRS. However, the endogenous counterregulatory immune mechanisms that are involved in the development of SIRS are not well understood. CD4+CD25+Foxp3 (forkhead box P3)+ regulatory T lymphocytes (Treg cells) play a key role in the immunological balance of the body. Thus, our aim was to investigate the contribution of these key immunomodulators (Treg cells) to the immune dysfunction that is observed in zymosan-induced SIRS in mice. We first evaluated the level of Treg cells in the lung of mice 6 h, 1 d, 2 d, 3 d, 5 d, and 7 d after the injection of zymosan or normal saline by western blot, real-time PCR and flow cytometry. We found that the number of Treg cells and the levels of the Treg cell-related transcription factor (Foxp3) and cytokines (IL-10) in the zymosan-treated group significantly decreased on day 1 and day 2 and significantly increased on day 5 compared with the NS-treated group. In the next experiment, the mice were injected with 200 μg of anti-CD25 mAb (clone PC61) to deplete the Treg cells and then injected with zymosan 2 days later. The number of Treg cells decreased by more than 50% after the injection of the PC61 mAb. In addition, the expression of the anti-inflammatory cytokine IL-10 also decreased. Moreover, the depletion of the Treg cells profoundly increased the mice'mortality and the degree of lung tissue injury. In conclusion, Treg cells tend to play a protective role in pathogenesis of the zymosan-induced generalized inflammation, and IL-10 signaling is associated with their immunomodulatory effect.

The protective effects of agmatine in zymosan induced acute lung injury in mice

To examine the protective effects of agmatine (AGM) administration on zymosan (ZYM)-induced inflammatory response and acute lung injury (ALI) in mice. 32 adult male C57BL/6 mice were randomly divided into four groups (n=8 each) to receive i. p. administration of:() phosphate buffer saline (PBS, 0. 5 ml); © AGM (200 mg/kg); © ZYM (500 mg/kg)+PBS (0.5 ml),and ® AGM (200 mg/kg)-ZYM (500 mg/kg). Blood samples and peritoneal exudates were collected from the animals 12 hours after drug administration for concentration of tumor necrosis factor-a (TNF-a),interleukin-6 (IL-6) and nitric oxide (NO) by enzyme linked immunosorbent assay (ELISA). Lung tissue samples were also collected at the same time for histological examination, and determination of tissue content of TNF-a, IL-6, myeloperoxidase (MPO) activity and nuclear factor-KB p65 (NF-cB p65) DNA-binding activity. 12 hours after ZYM injection, the treated mice became lethargic, their activity and water consumption were both reduced, AGM greatly improved the general status, activity, and water consumption in treated mice, while attenuated the increase of TNF-a (ng/L: 252. 6+ 32. 1 vs. 421. 7- 76. 7, 295. 7 ± 78. 6vs. 592. 0 ± 84. 3, both P<0. 05) , IL-6 (ng/L: 2 198. 8 281.8 vs. 4 725. 3 615.4, 19 829. 3 ± 3 647. Ovs. 47 751. 3 ± 5 264.8, both P<0. 05) and NO (pmol/L: 33. 2 ± 4. 3 vs. 50. 2 ± 5. 2, 14.0 ± 3. 6 vs. 45.4 ± 5. 2, both P<0. 05) in serum and peritoneal exudates caused by ZYM. AGM also attenuated the increase of TNF-a (ng/L: 245. 7 ± 39. 1 vs. 378. 3 ± 67. 6, P<0. 05), IL-6 (ng/L: 810. 3 ± 175. 6 vs. 1 172. 4 ± 203.3,P <0. 05), MPO activity (ng/mg: 24. 9 4. 4 vs. 37. 3 5.8, P< 0. 05) and NF-iB p65 optical density(absorbance value: 0. 272 + 0. 029 vs. 0. 347 ± 0. 037, P 0.05) in the lung tissue seen in ZYM treated animals. There was no significant difference between normal PBS and AGM treated group in all the indexes examined. Histological examination demonstrated that ZYM treated animals had severe inflammatory reaction in lung tissues (manifested as vasodilatation and neutrophils infiltration) and AGM significantly reduced such injury. AGM can attenuate the ALI and inflammation induced by ZYM in mice.

A Cell-penetrating Peptide Suppresses Inflammation by Inhibiting NF-κB Signaling

Nuclear factor-κB (NF-κB) is a central regulator of immune response and a potential target for developing anti-inflammatory agents. Mechanistic studies suggest that compounds that directly inhibit NF-κB DNA binding may block inflammation and the associated tissue damage. Thus, we attempted to discover peptides that could interfere with NF-κB signaling based on a highly conserved DNA-binding domain found in all NF-κB members. One such small peptide, designated as anti-inflammatory peptide-6 (AIP6), was characterized in the current study. AIP6 directly interacted with p65 and displayed an intrinsic cell-penetrating property. This peptide demonstrated significant anti-inflammatory effects in vitro and in vivo. In vitro, AIP6 inhibited the DNA-binding and transcriptional activities of the p65 NF-κB subunit as well as the production of inflammatory mediators in macrophages upon stimulation. Local administration of AIP6 significantly inhibited inflammation induced by zymosan in mice. Collectively, our results suggest that AIP6 is a promising lead peptide for the development of specific NF-κB inhibitors as potential anti-inflammatory agents.

Rosiglitazone May Assist With Glycemic Control in the ICU

Hyperglycemia is a frequent sequela of critical illness. Rosiglitazone is an oral hypoglycemic agent of the thiazolinedione class. Thiazolinediones are known to activate peroxisome proliferator-activated receptor gamma (PPAR-gamma) that decreases inflammation in humans and decreases shock induced by zymosan in mice. Rosiglitazone can assist with hyperglycemic control in the intensive care unit (ICU). A hospital billing query identified patients prescribed rosiglitazone while in a major university ICU. Patients who received rosiglitazone as an outpatient prior to hospitalization were excluded. Glycemic control was determined by average daily blood glucose, 24-hour insulin dose, and number of patients requiring an insulin drip. Glycemic control was evaluated on days 0, 3, and 7. Student t test was used to compare means. Fisher exact testing was used to compare insulin regimen before and after starting rosiglitazone. 34 patients were identified. The average Acute Physiology and Chronic Health Evaluation (APACHE) II score was 17.2 +/- 4.4. Sixty-five percent were male, 62% were preexisting diabetics. The mean daily blood glucose was 159 +/- 30 mg/dL on day 0, 146 +/- 37 mg/dL on day 3, and 140 +/- 33 mg/dL on day 7 (P < .03 vs day 0). The mean 24-hour insulin dose was 80.6 +/- 87.9 U on day 0, 72.2 +/- 73.4 U on day 3, and 46.3 +/- 57.2 U on day 7 (P < .003 vs day 0). There was 1 major hypoglycemic event. Rosiglitazone may assist glycemic control in the ICU. Despite recent concerns of cardiac safety, further research should be done to evaluate its potential as a short-term therapeutic agent in the ICU, given its anti-inflammatory and antishock profile.

PD98059, a specific MAP kinase inhibitor, attenuates multiple organ dysfunction syndrome/failure (MODS) induced by zymosan in mice

PD98059 (MEK1 Inhibitor) has been shown to act in vivo as a highly selective inhibitor of MEK1 activation and the MAP kinase cascade. In the present study, we have investigated the effects of PD98059, on the development of non-septic shock caused by zymosan in mice. Mice received either intraperitoneally zymosan (500 mg/kg, administered i.p. as a suspension in saline) or vehicle (0.25 ml/mouse saline). PD98059 (10 mg/kg) was administered 1 and 6 h after zymosan administration i.p. Organ failure and systemic inflammation in mice was assessed 18 h after administration of zymosan and/or PD98059. Treatment of mice with PD98059 attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan. PD98059 also attenuated the lung, liver and pancreatic injury and renal dysfunction caused by zymosan as well as the increase of TNF-α and IL-1β plasma levels caused by zymosan. Immunohistochemical analysis for inducible nitric oxide synthase (iNOS), nitrotyrosine, poly(ADP-ribose) (PAR), ICAM-1, P-selectin, Bax, Bcl-2 and FAS-ligand revealed positive staining in pancreatic and intestinal tissue obtained from zymosan-injected mice. The degree of staining for nitrotyrosine, iNOS, PAR, ICAM-1, P-selectin, Bax, Bcl-2 and FAS-ligand were markedly reduced in tissue sections obtained from zymosan-injected mice, which had received PD98059. Moreover treatment of mice with PD98059 (10 mg/kg) attenuated the NF-κB activation and mitogen-activated protein kinases (MAPK) expression induced by zymosan injection. In addition, administration of zymosan caused a severe illness in the mice characterized by a systemic toxicity, significant loss of body weight and a 60% of mortality at the end of observation period. Treatment with PD98059 significantly reduced the development of systemic toxicity, the loss in body weight and the mortality (20%) caused by zymosan. This study provides evidence that PD98059 attenuates the degree of zymosan-induced non-septic shock in mice.

Absence of endogenous interleukin-10 enhanced organ dysfunction and mortality associated to zymosan-induced multiple organ dysfunction syndrome

Experimental evidence suggests that interleukin (IL)-10 plays a pivotal role in generalized inflammation. Here we investigate the effects of IL-10 gene deletion on the acute phase of the multiple organ dysfunction syndrome (MODS) caused by zymosan in the mouse. MODS was induced by zymosan administration (500 mg/kg, suspended in saline solution, i.p.) in IL-10 wild-type and knockout mice; sham groups were treated with vehicle. Mice were sacrificed 18 h after zymosan or saline administration. In another set of experiments, animals were monitored for 12 days to assess systemic toxicity and survival rate. Mice lacking IL-10 displayed increased peritoneal exudate volume and leukocytes. Also, we observed a significant increase in myeloperoxidase activity and lipid peroxidation in ileum and lung tissues, as well as augmented levels of TNF-α, IL-1β and nitrogen-derived species in the plasma. With regard to organ injury, absence of IL-10 enhanced the renal, hepatocellular and pancreatic dysfunction caused by zymosan administration. All of these parameters significantly influenced the systemic toxicity and the overall survival at 12 days, which was significantly lower in IL-10 knockout mice. Therefore, this study demonstrates that the absence of endogenous IL-10 enhances the MODS induced by zymosan in mice.

Gelatinase B/MMP-9 as an inflammatory marker enzyme in mouse zymosan peritonitis: Comparison of phase-specific and cell-specific production by mast cells, macrophages and neutrophils

Neutrophil infiltration during zymosan peritonitis depends on matrix metalloproteinase-9 (MMP-9) activity as it is impaired both in MMP-9 −/− and gelatinase inhibitor-treated animals. The producer cells of MMP-9 and their relative contribution are not known. The aim of this study was to identify and compare the cellular sources, timing and intensity of MMP-9 induction by zymosan in the murine peritoneal cavity. We detected MMP-9 mRNA in unstimulated peritoneal leukocytes and its levels increased after zymosan administration. To detect MMP-9 by flow cytometry, we selected and compared two specific monoclonal antibodies. We show that MMP-9 protein was absent in control peritoneal macrophages, whereas already at 30 min of peritonitis almost all macrophages were producing the enzyme. Conversely, MMP-9 was constitutively present in unstimulated mast cells. Macrophages turned out to be prevalent MMP-9 producers in the early phase of peritonitis. During later stages macrophages kept the high expression of MMP-9 for at least 6 h of inflammation. In contrast, the early phase expression of MMP-9 by neutrophils was limited albeit the highest percentage of MMP-9 + neutrophils was observed at 2 h but absolute numbers of the MMP-9 carrying neutrophils were low at that time. In contrast, during the late phase of peritonitis neutrophils became major producers of MMP-9 as they numerously infiltrated peritoneum. In conclusion, the study reports detection of MMP-9 at the single-cell level during peritonitis, demonstrates unexpectedly fast MMP-9 expression in macrophages and reveals quantitatively phase-specific contribution of mast cells, macrophages and neutrophils.

ABCC transporter inhibition reduces zymosan-induced peritonitis

Inflammatory mediators are released from injured tissues being responsible for the first steps of inflammatory processes. Multidrug efflux transporters, members of the ATP-binding cassette (ABC) family, are ubiquitously expressed. ABCC molecules transport several endogenous substances, including leukotriene C4 (LTC4) and PGE2, which are involved in zymosan-induced inflammation. The present study investigated the role played by ABCC transporters on zymosan-induced peritonitis in mice. Most of the resident peritoneal cells were macrophages, based on their morphology and membrane-activated complex 3 expression. RT-PCR demonstrated that these cells expressed ABCC, and ABCC activity was analyzed in vivo via the s.c. injection of ABCC inhibitors [probenecid (PROB) 200 mg/kg or MK571 20 mg/kg], followed by an i.v. injection of carboxyfluorescein diacetate (CFDA), an ABCC fluorescent substrate. Both inhibitors increased CFDA accumulation, suggesting ABCC impairment. Moreover, ABCC reversors decreased zymosan-induced plasma exudation by 86.6 +/- 7.4 and 97.6 +/- 2.3%, a feature related to a diminished secretion of LTC(4) (65.1+/-11 and 47.8+/-9.9%) and PGE(2) (under basal levels). Cell migration was inhibited similarly. Furthermore, PROB and MK571 inhibited IL-1ss by 83.4 +/- 13 and 71.2 +/- 13.4% and TNF-alpha content by 47 +/- 4.5 and 28.9 +/- 0.8%, respectively. NO metabolites and reactive oxygen species production were also reduced. The present results suggest that ABCC molecules have a relevant role in the acute inflammatory response produced by zymosan in mice.

Erythropoietin reduces the development of nonseptic shock induced by zymosan in mice*

Erythropoietin is a potent stimulator of erythroid progenitor cells, and its expression is enhanced by hypoxia. In the present study, we investigated the effects of erythropoietin (1000 IU/kg subcutaneously) on the development of nonseptic shock caused by zymosan. Prospective, randomized study. University-based research laboratory. Male CD mice. Mice received either intraperitoneally zymosan (500 mg/kg, administered intraperitoneally as a suspension in saline) or vehicle (0.25 mL/mouse saline). Erythropoietin was administered at the dose of 1000 IU/kg subcutaneously, 1 and 6 hrs after zymosan administration. Organ failure and systemic inflammation in mice was assessed 18 hrs after administration of zymosan and/or erythropoietin. Treatment of mice with erythropoietin (1000 IU/kg subcutaneously, 1 and 6 hrs after zymosan administration) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan. Erythropoietin also attenuated the lung, liver, and pancreatic injury and renal dysfunction caused by zymosan as well as the increase in myeloperoxidase activity caused by zymosan in the lung and intestine. Immunohistochemical analysis for nitrotyrosine and poly(ADP-ribose) revealed positive staining in lung and intestine tissues obtained from zymosan-treated mice. The degree of staining for nitrotyrosine and poly(ADP-ribose) was markedly reduced in tissue sections obtained from zymosan-treated mice, which received erythropoietin. In addition, administration of zymosan caused severe illness in the mice characterized by a systemic toxicity, significant loss of body weight, and a 70% mortality rate at the end of observation period (7 days). Treatment with erythropoietin significantly reduced the development of systemic toxicity, the loss in body weight, and the mortality caused by zymosan. This study provides evidence, for the first time, that erythropoietin attenuates the degree of zymosan-induced nonseptic shock in mice.

Local anti-inflammatory effect and behavioral studies on new PDE4 inhibitors

Phosphodiesterase 4 (PDE4) inhibitors are effective anti-inflammatory drugs, although some adverse effects are observed in animals and humans. These effects have forced researchers to find new PDE4 inhibitors with less adverse effects. We recently reported the synthesis of novel heterocyclic-fused pyridazinones that inhibit PDE4. As a first step in the study of the anti-inflammatory properties of these compounds, we studied the effects of local administration of these pyridazinone derivatives in a mouse model of acute inflammation. We found that 6-Benzyl-3-methyl-4-phenylpyrazolo[3,4- d]pyridazin-7(6 H)-one (CC4), ethyl 6,7-dihydro-6-ethyl-3-methyl-7-oxo-4-phenyl-thieno[2,3- d]pyridazine-2-carboxylate (CC6) and ethyl 6,7-dihydro-6-ethyl-3-methyl-4-phenyl-1 H-pyrrolo[2,3- d]pyridazine-2-carboxylate (CC12) reduced the paw edema induced by zymosan in mice as rolipram (the PDE4 inhibitor prototype with anti-inflammatory activity) and indomethacin did. It is well known that rolipram locally administered induces some adverse effects such as hyperalgesia. Thus, we studied this effect after local administration of CC4, CC6 and CC12 in the formalin test. We found that CC6 induced hyperalgesic effects, whereas CC4 and CC12 did not change the nociceptive threshold. Furthermore, we found that rolipram and CC6 reduced locomotor activity, whereas CC4 and CC12 did not change locomotor performance of the mice. Since CC4 and CC12 neither affected the nociceptive threshold nor changed the locomotor performance of mice, they appear more suitable than CC6 for future studies on animals and could be developed as an anti-inflammatory drug for humans.

Differential Effects of Selective Cyclooxygenase (COX)-1 and COX-2 Inhibitors on Anorexic Response and Prostaglandin Generation in Various Tissues Induced by Zymosan

We have shown that anorexic response is induced by intraperitoneal injection of zymosan in mice, although the role of prostaglandins in this response is relatively unknown as compared with lipopolysaccharide (LPS)-induced anorexic response. Indomethacin (0.5 and 2.0 mg/kg), a non-selective cyclooxygenase (COX) inhibitor, as well as meloxicam (0.5 mg/kg), a selective COX-2 inhibitor, but not FR122047 (2.0 mg/kg), a selective COX-1 inhibitor, attenuated zymosan-induced anorexia. Zymosan injection elevated COX-2 expression in brain and liver but not in small intestine and colon. Meloxicam (0.5 mg/kg) and FR122047 treatment (2.0 mg/kg) similarly suppressed the generation of brain prostaglandin E(2) (PGE(2)) and peritoneal prostacyclin (PGI(2)) upon zymosan injection. PGE(2) generation in liver upon zymosan injection was suppressed by meloxicam (0.5 mg/kg) but not by FR122047 treatment (2.0 mg/kg). Our observations suggest that COX-2 plays an important role in zymosan-induced anorexia, which is a similar feature in LPS-induced anorexic response. However, non-selective inhibition by selective COX-1 and COX-2 inhibitors of brain PGE(2) generation upon zymosan injection does not support the role of COX-2 expressed in brain in zymosan-induced anorexic response. PGE(2) generation in liver may account for peripheral role of COX-2 in zymosan-induced anorexic response.

ZYMOSAN-INDUCED GENERALIZED INFLAMMATION: EXPERIMENTAL STUDIES INTO MECHANISMS LEADING TO MULTIPLE ORGAN DYSFUNCTION SYNDROME

Patients suffering from multiple organ dysfunction syndrome (MODS) comprise a heterogeneous population, which complicates research in its pathogenesis. Elucidation of the mechanisms involved in the development of MODS will ultimately necessitate the collection of tissue samples and the performance of invasive procedures. These requirements greatly reduce the possibilities for research in human subjects. Therefore, an animal model for MODS is a necessary and valuable tool. In the mid 1980s, the zymosan-induced generalized inflammation (ZIGI) model was introduced. Intraperitoneal injection of zymosan in mice or rats leads, in the course of 1 to 2 weeks, to increasing organ damage and dysfunction. The ZIGI model has been recognized as the one that best resembles human MODS and it has been used widely to study systemic inflammation in relation to organ failure. This review describes the ZIGI model and gives an overview of the results obtained.

CD44 and hyaluronic acid regulate in vivo iNOS expression and metalloproteinase activity in murine air-pouch inflammation

To evaluate the effects of anti-CD44 IM7.8.1 antibody, HMW-HA and LMW-HA on leukocyte migration and adhesion, and the induction of proinflammatory mediators, in mouse air-pouch inflammation induced by zymosan. Leukocytes were obtained from zymosan-air pouches after the intra-pouch injection of anti-CD44 IM7.8.1, isotype control, HMW-HA, LMW-HA or PBS. TNF-alpha, IL-1beta and iNOS mRNA were estimated in leukocytes by semi-quantitative RT-PCR. Matrix metalloproteinases (MMPs) from exudates were evaluated by zymography and Western Blot. Adhesion and migration of leukocytes were evaluated in HA-coated plates and Boyden chambers respectively. IM7.8.1 decreased iNOS mRNA levels and the activity of both MMP-9 and MMP-2 eight h after injection into zymosan air pouch while IM7.8.1, HMW-HA and LMW-HA had no effect on IL1-beta or TNF-alpha mRNA levels. Leukocytes from air pouch adhered to and migrated in vitro against both HMW-HA and LMW-HA. LMW-HA increased the number of leukocytes in the air pouch and iNOS mRNA levels as compared to PBS injection. In contrast, HMW-HA decreased leukocyte count and reduced iNOS mRNA levels. Paradoxically, the activity of both MMP-9 and MMP-2 was increased by HMW-HA and decreased by LMW-HA. Both CD44 and HA can modulate leukocyte migration and induction of proinflammatory mediators in mouse zymosan air pouch inflammation. IM7.8.1 had consistent anti-inflammatory effects, reducing iNOS, MMP-9 and MMP-2. HMW-HA and LMW-HA were able to modulate both the induction of proinflammatory mediators and leukocyte count in the air pouch.

Methylguanidine reduces the development of non septic shock induced by zymosan in mice

In the present study we evaluate the effect of methylguanidine (MG), a product of protein catabolism, in a model of acute inflammation (zymosan induced inflammation) in mice where oxyradical and nitric oxide (NO) play a crucial role. Our data show that MG, given intraperitoneally at the dose of 30 mg/Kg, inhibits the inflammatory response reducing significantly (P < 0.05) peritoneal exudates formation, mononuclear cell infiltration and histological injury in mice. Furthermore, our data suggests that there is a significant (P < 0.05) reduction in kidney, liver and pancreas injury as demonstrated by the reduction in amylase, lipase, creatinine, AST, ALT, bilirubine and alkaline phosfatase levels. MG is also able to reduce the appearance of nitrotyrosine and of the nuclear enzyme poly (adenosine diphosphate [ADP]-ribose) synthase (PARS) immunoreactivity in the inflamed intestinal and lung tissues. The histological examination revealed a significant reduction in zymosan-induced intestinal and lung damage in MG-treated mice. Taken together, the present results demonstrate that MG exerts potent anti-inflammatory effects on zymosan-induced shock.