TREM-1 is required for enhanced OpZ-induced superoxide generation following priming

Inflammatory agents, microbial products, or stromal factors pre-activate or prime neutrophils to respond to activating stimuli in a rapid and aggressive manner. Primed neutrophils exhibit enhanced chemotaxis, phagocytosis, and respiratory burst when stimulated by secondary activating stimuli. We previously reported that Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) mediates neutrophil effector functions such as increased superoxide generation, transepithelial migration, and chemotaxis. However, it is unclear whether TREM-1 is required for the process of priming itself or for primed responses to subsequent stimulation. To investigate this, we utilized in vitro and in vivo differentiated neutrophils that were primed with TNF-α and then stimulated with the particulate agonist, opsonized zymosan (OpZ). Bone marrow progenitors isolated from WT and Trem-1-/- mice were transduced with estrogen regulated Homeobox8 (ER-Hoxb8) fusion transcription factor and differentiated in vitro into neutrophils following estrogen depletion. The resulting neutrophils expressed high levels of TREM-1 and resembled mature in vivo differentiated neutrophils. The effects of priming on phagocytosis and oxidative burst were determined. Phagocytosis did not require TREM-1 and was not altered by priming. In contrast, priming significantly enhanced OpZ-induced oxygen consumption and superoxide production in WT but not Trem-1-/- neutrophils indicating that TREM-1 is required for primed oxidative burst. TREM-1-dependent effects were not mediated during the process of priming itself as priming enhanced degranulation, ICAM-1 shedding, and IL-1ß release to the same extent in WT and Trem-1-/- neutrophils. Thus, TREM-1 plays a critical role in primed phagocytic respiratory burst and mediates its effects following priming.

A single intra-articular dose of vitamin D analog calcipotriol alleviates synovitis without adverse effects in rats

1,25-dihydroxyvitamin-D3 and its derivatives have shown anti-arthritic and chondroprotective effects in experimental animal models with prophylactic dosing. The purpose of this preliminary study was to test the efficacy and safety of calcipotriol, vitamin D analog, as a treatment for a fully-developed knee arthritis in Zymosan-induced arthritis (ZIA) model. Forty 5-month-old male Sprague-Dawley rats were randomized into three arthritis groups and a non-arthritic control group with no injections (10 rats/group). A day after Zymosan (0.1 mg) had been administrated into the right knee joints, the same knees were injected with calcipotriol (0.1 mg/kg), dexamethasone (0.1 mg/kg) or vehicle in a 100 μl volume. The left control knees were injected with saline (PBS) on two consecutive days. All injections, blood sampling and measurements were performed under general anesthesia on days 0, 1, 3 and 8. Internal organs and knees were harvested on day 8 and the histology of the whole knees was assessed blinded. Joints treated with calcipotriol showed a milder histological synovitis than those treated with vehicle (p = 0.041), but there was no statistically significant difference between the dexamethasone and vehicle groups. The clinical severity of arthritis did not differ between the arthritis groups measured by body temperature, swelling of the knee, thermal imaging, clinical scoring or cytokine levels on days 1, 3 and 8. Weight loss was bigger in rats treated with dexamethasone, propably due to loss of appetite,compared to other arthritis groups on days 2-3 (p<0.05). Study drugs did not influence serum calcium ion and glucose levels. Taken together, this preliminary study shows that a single intra-articular injection of calcipotriol reduces histological grade of synovitis a week after the local injection, but dexamethasone did not differ from the vehicle. Calcipotriol may have an early disease-modifying effect in the rat ZIA model without obvious side effects.

Fever Induced by Zymosan A and Polyinosinic-Polycytidylic Acid in Female Rats: Influence of Sex Hormones and the Participation of Endothelin-1

Sex differences in the immune response can also affect the febrile response, particularly the fever induced by lipopolysaccharide (LPS). However, other pathogen-associated molecular patterns, such as zymosan A (Zym) and polyinosinic-polycytidylic acid (Poly I:C), also induce fever in male rats with a different time course of cytokine release and different mediators such as endothelin-1 (ET-1). This study investigated whether female sex hormones affect Zym- and Poly I:C-induced fever and the involvement of ET-1 in this response. The fever that was induced by Zym and Poly I:C was higher in ovariectomized (OVX) female rats compared with sham-operated female rats. Estrogen replacement in OVX females reduced Zym- and Poly I:C-induced fever. The ET_B receptor antagonist BQ788 reversed the LPS-induced fever in cycling females but not in OVX females. BQ788 did not alter the fever that was induced by Zym or Poly I:C in either cycling or OVX females. These findings suggest that the febrile response in cycling females is lower, independently of the stimulus that is inducing it and is probably controlled by estrogen. Also, ET-1 seems to participate in the febrile response that was induced by LPS in males and cycling females but not in the LPS-induced fever in OVX females. Additionally, ET-1 was not involved in the febrile response that was induced by Zym or Poly I:C in females.

Behavioral and physiological responses to intraperitoneal injection of zymosan in chicks

Zymosan is a cell wall component of the yeast Saccharomyces cerevisiae and produces severe inflammatory responses in mammals. When zymosan is peripherally injected in mammals, it induces several behavioral and physiological changes including anorexia and hyperthermia. However, to our knowledge, behavioral and physiological responses to zymosan have not yet been clarified in birds. Therefore, the purpose of the present study was to determine if intraperitoneal injection of zymosan affects food intake, voluntary activity, cloacal temperature, plasma corticosterone (CORT) and glucose concentrations, and splenic gene expression of cytokines in chicks (Gallus gallus). Intraperitoneal injection of zymosan (2.5 mg) significantly decreased food intake, voluntary activity, and plasma glucose concentration, and increased plasma CORT concentration. The injection of 0.5 mg zymosan significantly increased cloacal temperature, while 2.5 mg zymosan had a tendency to increase it. Finally, 2.5 mg zymosan significantly increased the splenic gene expression of interleukin-1β (IL-1β), IL-6, IL-8, interferon-γ, and tumor necrosis factor-like cytokine 1A. The present results suggest that zymosan would be one of components which induces nonspecific symptoms including anorexia, hypoactivity, hyperthermia, and stress responses, under fungus infection in chicks.

Anti-inflammatory and anti-arthritic activity in extract from the leaves of Eriobotrya japonica

ETHNOPHARMACOLOGICAL RELEVANCE

The Eriobotrya japonica (EJ) is a Chinese medicinal plant that is currently grown in Brazil. E. japonica leaves infusion is traditionally used in the treatment of inflammation; however, there are few scientific studies showing the effects of these properties on joint articular and persistent experimental inflammation.

AIM OF THE STUDY

The present research had objective investigation of the effect of infusion obtained from leaves of E. japonica (EJLE) on acute and persistent experimental articular inflammation.

MATERIALS AND METHODS

The Swiss mice were treated orally with EJLE and analyzed for acute pleural inflammation (30, 100, and 300 mg/kg), paw edema induced by carrageenan (100 mg/kg), acute knee inflammation induced by zymosan (100 mg/kg), and persistent inflammation induced by Complete Freund's Adjuvant (CFA) (30 and 100 mg/kg). Mechanical hyperalgesia, cold and edema were analyzed.

RESULTS

The chromatographic analysis of EJLE revealed the presence of corosolic acid, oleanolic acid, and ursolic acid. EJLE presented anti-inflammatory activity in the pleurisy model, inhibiting leukocyte migration, protein extravasation and nitric oxide production. In the articular inflammation model, EJLE reduced the number of leukocytes in the joint cavity, paw edema and hyperalgesia (4 h after induction). In the persistent inflammation model induced by CFA, the extract reduced paw edema after 11 days of mechanical and cold hyperalgesia on day 6.

CONCLUSIONS

The EJLE has anti-inflammatory and antihyperalgesic potential in models of acute and persistent experimental articular inflammation, making this infusion a new possibility for complementary treating acute or chronic articular inflammatory diseases.

Long-Lasting Anti-Inflammatory and Antinociceptive Effects of Acute Ammonium Glycyrrhizinate Administration: Pharmacological, Biochemical, and Docking Studies

The object of the study was to estimate the long-lasting effects induced by ammonium glycyrrhizinate (AG) after a single administration in mice using animal models of pain and inflammation together with biochemical and docking studies. A single intraperitoneal injection of AG was able to produce anti-inflammatory effects in zymosan-induced paw edema and peritonitis. Moreover, in several animal models of pain, such as the writhing test, the formalin test, and hyperalgesia induced by zymosan, AG administered 24 h before the tests was able to induce a strong antinociceptive effect. Molecular docking studies revealed that AG possesses higher affinity for microsomal prostaglandin E synthase type-2 compared to type-1, whereas it seems to locate better in the binding pocket of cyclooxygenase (COX)-2 compared to COX-1. These results demonstrated that AG induced anti-inflammatory and antinociceptive effects until 24-48 h after a single administration thanks to its ability to bind the COX/mPGEs pathway. Taken together, all these findings highlight the potential use of AG for clinical treatment of pain and/or inflammatory-related diseases.

Prostaglandins mediate zymosan-induced sickness behavior in mice

Previous studies have demonstrated that zymosan, a cell wall component of the yeast Saccharomyces cerevisiae, induces inflammation in experimental models. However, few studies have evaluated the potential of zymosan to induce sickness behavior, a central motivational state that allows an organism to cope with infection. To determine whether zymosan administration results in sickness behavior, mice were submitted to the forced swim (FST) and open field (OFT) tests 2, 6, and 24 h after treatment with zymosan (1, 10, or 100 mg/kg). Additionally, to evaluate the possible relationship between zymosan-induced sickness behavior and prostaglandin synthesis, mice were pretreated with the cyclooxygenase inhibitors indomethacin (10 mg/kg) and nimesulide (5 mg/kg) and the glucocorticoid drug dexamethasone (1 mg/kg). Zymosan induced time-dependent decreases in locomotor activity in the OFT, and an increase in immobility in the FST, and increased plasma levels of corticosterone at 2 h. Pretreatment with indomethacin, nimesulide, or dexamethasone blocked zymosan-induced behavioral changes in both the FST and OFT at 2 h post administration. These findings confirm previous observations that zymosan induces sickness behavior. Furthermore, our results provide new evidence that prostaglandin synthesis is necessary for this effect, as anti-inflammatory drugs that inhibit prostaglandin synthesis attenuated zymosan-induced behavioral changes.

CCL5 Promotes Resolution-Phase Macrophage Reprogramming in Concert with the Atypical Chemokine Receptor D6 and Apoptotic Polymorphonuclear Cells

The engulfment of apoptotic polymorphonuclear cells (PMN) during the resolution of inflammation leads to macrophage reprogramming culminating in reduced proinflammatory and increased anti-inflammatory mediator secretion. The atypical chemokine receptor D6/ACKR2 is expressed on apoptotic PMN and plays an important role in regulating macrophage properties during and after engulfment. In this study, we found that the inflammatory chemokine CCL5 is mostly retained (75%) during the resolution of zymosan A peritonitis in mice. Moreover, this chemokine is secreted by resolution-phase macrophages (2.5 ng/ml) and promotes their reprogramming in vivo in D6+/+ mice (2-fold increase in IL-10/IL-12 ratio) but not their D6-/- counterparts. In addition, CCL5 enhanced macrophage reprogramming ex vivo exclusively when bound to D6+/+ apoptotic PMN. Signaling through p38MAPK and JNK in reprogrammed macrophages was enhanced by CCL5-bound apoptotic PMN (3.6-4 fold) in a D6-dependent manner, and was essential for reprogramming. Thus, CCL5 exerts a novel proresolving role on macrophages when acting in concert with apoptotic PMN-expressed D6.

HMGB1 Inhibition During Zymosan-Induced Inflammation: The Potential Therapeutic Action of Riboflavin

Sepsis, also known as systemic inflammatory response syndrome, is a life-threatening condition caused by a pathogenic agent and leading to multiple organ dysfunction syndrome. One of the factors responsible for the excessive intensification of the inflammatory response in the course of inflammation is high-mobility group protein B1 (HMGB1). HMG-1 is a nuclear protein which, after being released to the intercellular space, has a highly pro-inflammatory effect and acts as a late mediator of lethal damage. The purpose of this study was to examine whether the anti-inflammatory action of riboflavin is accompanied by inhibition of HMGB1 release during peritoneal inflammation and zymosan stimulation of macrophages. Peritonitis was induced in male BALB/c and C57BL/6J mice via intraperitoneal injection of zymosan (40 mg/kg). RAW 264.7 macrophages were activated with zymosan (250 µg/ml). Riboflavin (mice, 50 mg/kg; RAW 264.7, 25 µg/ml) was administered 30 min before zymosan, simultaneously with, or 2, 4, 6 h after zymosan. Additionally, mRNA expression of HMGB1 and its intracellular and serum levels were evaluated. The research showed that riboflavin significantly reduces both the expression and the release of HMGB1; however, the effect of riboflavin was time-dependent. The greatest efficacy was found when riboflavin was given 30 min prior to zymosan, and also 2 and 4 h (C57BL/6J; RAW 264.7) or 4 and 6 h (BALB/c) after zymosan. Research showed that riboflavin influences the level of HMGB1 released in the course of inflammation; however, further study is necessary to determine its mechanisms of action.

Immunomodulatory effect of cathelicidins in response to a β-glucan in intestinal epithelial cells from rainbow trout

The aim of the present study was to characterize intestinal immune mechanisms involved in the response to β-glucans in rainbow trout. Among the immune effectors regulated in response to immunostimulants, host defense peptides (HDPs) are abundantly expressed in epithelial linings, suggesting their important role in the mucosal immune response. Therefore, the immunomodulatory properties of expressed HDPs in the epithelial intestinal cells of rainbow trout in response to the β-glucan, zymosan, were assessed. The results showed that zymosan increased the production of the HDP, cathelicidin, and the cytokine, IL-1β, in the intestinal epithelial RTgutGC cell line at the transcript and protein levels. Thus, cathelicidin-2 variants were produced and were shown to (i) induce the production of IL-1β in RTgutGC cells and (ii) display a synergic effect with zymosan in IL-1β upregulation. Importantly, the colocalization of both rtCATH-2 and IL-1β was detected in the intestinal epithelial cells of rainbow trout fed with a 0.3% zymosan-supplemented diet. We propose that trout cathelicidins are expressed by intestinal epithelial cells and exert immunomodulatory effects to improve the local intestinal immune response triggered by immunostimulants.

Oral immunostimulation of the oyster Ostrea edulis: Impacts on the parasite Bonamia ostreae

Bioactive compounds were orally administered to the native European oyster Ostrea edulis to evaluate the immune response and the progression of infection of the protozoan parasite Bonamia ostreae. The immunostimulants lipopolysaccharide and zymosan directly administrated to the water column induced an increase in lysozyme activity and the percentage of granulocytes in naïve oysters over a period of 7 days. In another set of experiments, zymosan and curdlan were microencapsulated in alginate and also administered to the water column to naïve and B. ostreae infected O. edulis. Oyster mortality, prevalence and intensity of infection and several immune parameters were evaluated up to 28 days post-administration. Lysozyme activity, nitric oxide production and the expression of galectin, lysozyme and superoxide dismutase increased after 24 h in both infected and uninfected oysters. Zymosan immunostimulated oysters displayed a decrease in the prevalence of B. ostreae infection not attributed to mortalities but which could be associated to the enhanced ability of immunostimulants to evoke an enhanced immune response in the oysters and reduce infection.

Carp neutrophilic granulocytes form extracellular traps via ROS-dependent and independent pathways

Neutrophil extracellular traps (NETs) have recently been described as an important innate defense mechanism that leads to immobilization and killing of invading pathogens. NETs have been identified in several species, but the mechanisms involved in NET formation and their role in infection have not been well determined yet. Here we show that upon in vitro stimulation with different immunostimulants of bacterial, fungal or viral origin, carp neutrophilic granulocytes rapidly release NET structures. We analyzed the composition of these structures and the kinetics of their formation by confocal microscopy, by quantifying the levels of extracellular DNA and the release of enzymes originating from neutrophilic granules: myeloperoxidase, neutrophil elastase and matrix metalloproteinase 9 (MMP-9). Profiles of NET release by carp neutrophils as well as their enzyme composition are stimulus- and time-dependent. This study moreover provides evidence for a stimulus-dependent selective requirement of reactive oxygen species in the process of NET formation. Collectively the results support an evolutionary conserved and strictly regulated mechanism of NET formation in teleost fish.

[Effect of opioid peptides on oxygen-dependent microbicidity of peripheral blood neutrophils]

Investigation ofopioid peptide effect on the production of reactive oxygen species by neutrophils in non-fractionated leukocyte suspension and in purified fraction of peripheral blood neutrophils is disclosed in this work. It was determined that selective delta- and micro-agonists of peptide origin stimulated the spontaneous and suppressed 15 mkg/ml zymosan-induced LDCL (luminol-dependent chemiluminescence) reaction of neutrophils in leukocyte suspension. beta-endorphin was found to render less marked suppressive action on 15 mkg/ml zymosan-induced LDCL, and delta2-agonist deltorphin 2 promoted 15 mkg/ml zymosan-induced LDCL only toward the 25 minutes of the experiment. beta-endorphin and selective d- and m- agonists did not affect the spontaneous and suppressed 15 mkg/ml and 150 mkg/ml zymosan-induced neutrophil LDCL. Therefore, opioid peptides play essential role in the process of direct and indirect regulation of oxygen-dependent system of neutrophil granulocyte bactericidal activity.

Changes in the amount of reduced glutathione and activity of antioxidant enzymes in chosen mouse organs influenced by zymosan and melatonin administration

Reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSHPx) are vital components of the antioxidative barrier in animal cells. It is suggested more often now that the effectiveness of the protection of cells against the oxidative stress caused by the inflammation process depends on the amount of GSH and the activity of SOD, CAT and GSHPx. That is why the effect of zymosan A (40 mg/kg body mass) and the combined treatment with zymosan A (at the same dose) and melatonin (50 mg/kg body mass) on the amount of GSH in the blood and the amount of GSH and activity of SOD, CAT and GSHPx in the brain, liver and kidneys of male mice was estimated. Animals (n = 108) were decapitated after 3, 6 and 24 hours since the moment of the administration of only zymosan A, and combined zymosan A and after one hour melatonin. After the injection of zymosan A it was found that the amount of GSH is significantly lower after 3 and 6 hours in the blood and studied organs. The administration of zymosan A, followed by the administration of melatonin limited the decrease in the amount of this tripeptide in the same time. Simultaneously, the decrease in the amount of GSH in the studied organs was accompanied by a similar decrease in the activity of SOD, CAT and GSHPx after the injection of only zymosan A and a limited decrease in the activity after the administration of both zymosan A and melatonin. It is suggested that a decreased content of GSH and a decrease in the activity of the studied antioxidative enzymes is caused by the oxidative stress accompanying the inflammation process.

Protective effect of chloral hydrate against lipopolysaccharide/D-galactosamine-induced acute lethal liver injury and zymosan-induced peritonitis in mice

In recent years, certain anesthetics have been shown to have protective effects against acute inflammation in experimental animals, an observation that may yield new options for adjunctive treatment of acute inflammation. In this study, we investigated the effects of chloral hydrate (CH) on the acute inflammatory response in BALB/c mice using lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced acute lethal liver injury and zymosan A-induced peritonitis models. The survival of mice following LPS/D-GalN treatment was significantly improved by a single injection with chloral hydrate, which could be administered simultaneously or as late as 3 h after challenge with LPS/D-GalN; liver injury was also attenuated. A sharp rise in serum levels of MCP-1, IL-6 and TNF-alpha was attenuated or delayed after chloral hydrate treatment. Furthermore, the mechanism by which chlorate hydrate inhibits inflammation was associated with an attenuated increase in nuclear factor kappaB (NF-kappaB) activity in NF-kappaB-RE-luc mice upon LPS/D-GalN treatment. In mice with acute peritonitis, leukocyte number and protein concentration in peritoneal exudates peaked with a 16 h lag, and serum levels of MCP-1, IL-6 and TNF-alpha were significantly lower at certain time points in the chloral hydrate-treated group compared to those in the normal saline (NS)-treated control group. In addition, chloral hydrate treatment in vitro attenuated the upregulation of TNF-alpha and IL-6 by peritoneal macrophages and NF-kappaB activity in RAW264.7 cells stimulated with LPS, suggesting that monocytes/macrophages may be a target of chloral hydrate. These results indicate that chloral hydrate has a protective effect against LPS/D-GalN-induced acute lethal liver injury in mice, which may be associated with an inhibition of NF-kappaB activity and delays in proinflammatory cytokine production. However, this phenomenon was not associated with levels of serum corticosterone. Chloral hydrate also attenuated the inflammatory response in zymosan A-induced acute peritonitis, a model of mild inflammation. In conclusion, treatment with only a single injection of chloral hydrate could significantly attenuate acute inflammation in mice treated with LPS/D-GalN and zymosan A. These effects are also likely associated with the inhibition of NF-kappaB activity.

Imaging cyclooxygenase-2 (Cox-2) gene expression in living animals with a luciferase knock-in reporter gene

The cyclooxygenase-2 (Cox-2) gene plays a role in a variety of normal and pathophysiological conditions. Expression of the Cox-2 gene is induced in a broad range of cells, in response to many distinct stimuli. The ability to monitor and quantify Cox-2 expression noninvasively in vivo may facilitate a better understanding of the role of Cox-2, both in normal physiology and in different diseases. We generated a "knock-in" mouse in which the firefly luciferase reporter enzyme is expressed at the start site of translation of the endogenous Cox-2 gene. Correlation of luciferase and Cox-2 expression was confirmed in heterozygous Cox-2luc/+ mouse embryonic fibroblasts isolated from the knock-in mouse. In an acute sepsis model, following injection of interferon gamma and endotoxin, ex vivo imaging and Western blotting demonstrated coordinate Cox-2 and luciferase induction in multiple organs. Using both paw and air pouch inflammation models, we can monitor repeatedly localized luciferase expression in the same living mouse. Cox-2luc/+ knock-in mice should provide a valuable tool to analyze Cox-2 expression in many disease models.

Involvement of LTB4 in zymosan-induced joint nociception in mice: participation of neutrophils and PGE2

Leukotriene B4 (LTB4) mediates different inflammatory events such as neutrophil migration and pain. The present study addressed the mechanisms of LTB4-mediated joint inflammation-induced hypernociception. It was observed that zymosan-induced articular hypernociception and neutrophil migration were reduced dose-dependently by the pretreatment with MK886 (1-9 mg/kg; LT synthesis inhibitor) as well as in 5-lypoxygenase-deficient mice (5LO(-/-)) or by the selective antagonist of the LTB(4) receptor (CP105696; 3 mg/kg). Histological analysis showed reduced zymosan-induced articular inflammatory damage in 5LO(-/-) mice. The hypernociceptive role of LTB4 was confirmed further by the demonstration that joint injection of LTB4 induces a dose (8.3, 25, and 75 ng)-dependent articular hypernociception. Furthermore, zymosan induced an increase in joint LTB4 production. Investigating the mechanism underlying LTB4 mediation of zymosan-induced hypernociception, LTB4-induced hypernociception was reduced by indomethacin (5 mg/kg), MK886 (3 mg/kg), celecoxib (10 mg/kg), antineutrophil antibody (100 mug, two doses), and fucoidan (20 mg/kg) treatments as well as in 5LO(-/-) mice. The production of LTB4 induced by zymosan in the joint was reduced by the pretreatment with fucoidan or antineutrophil antibody as well as the production of PGE2 induced by LTB4. Therefore, besides reinforcing the role of endogenous LTB4 as an important mediator of inflamed joint hypernociception, these results also suggested that the mechanism of LTB4-induced articular hypernociception depends on prostanoid and neutrophil recruitment. Furthermore, the results also demonstrated clearly that LTB4-induced hypernociception depends on the additional release of endogenous LTs. Concluding, targeting LTB4 synthesis/action might constitute useful therapeutic approaches to inhibit articular inflammatory hypernociception.

Nonspecific immunotherapy with intratumoral lipopolysaccharide and zymosan A but not GM-CSF leads to an effective anti-tumor response in subcutaneous RG-2 gliomas

PURPOSE

Nonspecific stimulation of cells of the immune system may be useful in generating an anti-tumor response for a variety of cancers and may work synergistically with currently available cytotoxic therapies. In this study we examined the response of syngeneic rat gliomas to treatment with several nonspecific stimulators of dendritic cells and macrophages alone or in combination with radiation therapy.

EXPERIMENTAL DESIGN

RG-2 gliomas were implanted subcutaneously and treated with intratumoral (IT) injections of the toll-like receptor (TLR) ligands lipopolysaccharide (LPS) and zymosan A (ZymA) and the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF). Combination treatment with IT LPS and single-fraction external beam radiotherapy (EBRT) was also evaluated.

RESULTS

Treatment with IT LPS and ZymA delayed tumor growth compared to saline controls. Multiple doses of both substances were superior to single doses, and led to complete tumor regression in 71% (LPS) and 50% (ZymA) of animals. GM-CSF showed no anti-tumor effects in this study. Combinations of IT LPS and EBRT appeared to have a synergistic effect in delaying tumor growth. Rechallenge studies and IT LPS treatment of RG-2 tumors in nude rats suggested the importance of T cells in this treatment paradigm.

CONCLUSIONS

Direct IT treatment with the TLR ligands LPS and ZymA are effective in generating an anti-tumor response. These treatments may synergize with cytotoxic therapies such as EBRT, and appear to require T cells for a successful outcome.

Mechanisms involved in the anti-inflammatory action of inhaled tea tree oil in mice

Tea tree oil (TTO) is well known as an antimicrobial and immunomodulatory agent. In the present study we confirmed the anti-inflammatory properties of TTO and investigated the involvement of the hypothalamic-pituitary-adrenal (HPA) axis in the immunomodulatory action of TTO administered by inhalation. Sexually mature, 6-8-week-old, C(57)BI(10) x CBA/H (F(1)) male mice were used. One group of animals was injected intra-peritoneally (ip) with Zymosan to elicit peritoneal inflammation and was then submitted to four sessions of TTO inhalation (15 mins each). Some of the mice were simultaneously injected ip with Antalarmin, a CRH-1 receptor antagonist, to block HPA axis functions. Twenty-four hours after the injections the mice were killed by CO(2) asphyxia, and peritoneal leukocytes (PTLs) were isolated and counted. Levels of reactive oxygen species (ROS) and cyclooxygenase (COX) activity in PTLs were assessed by fluorimetric and colorimetric assays, respectively. The results obtained show that sessions of TTO inhalation exert a strong anti-inflammatory influence on the immune system stimulated by Zymosan injection, while having no influence on PTL number, ROS level, and COX activity in mice without inflammation. The HPA axis was shown to mediate the anti-inflammatory effect of TTO; Antalarmin abolished the influence of inhaled TTO on PTL number and their ROS production in mice with experimental peritonitis, but it had no effect on these parameters in mice without inflammation.

Analgesia induced by perineural clonidine is enhanced in persistent neuritis

Alpha 2-adrenoceptors are concentrated near sites of peripheral nerve injury or inflammation, primarily on immune cells, and their activation reduces inflammation and hypersensitivity to tactile stimuli. These results were obtained during acute inflammation, but the efficacy of alpha2-adrenoceptor stimulation in persistent inflammation has not been tested. Here, we show that perineural injection of the alpha2-adrenoceptor agonist, clonidine, reduces hypersensitivity in persistent sciatic neuritis with an onset more rapid than acute neuritis. Perineural clonidine reduces microglial activation in the spinal cord in persistent, but not acute neuritis, and does not change the number of spinal neurons with phosphorylated transcription factor, cyclic adenosine monophosphate response element binding protein. These data support treatment strategies with alpha2-adrenoceptor agonists in persistent neuritis.

Mast cell-expressed complement receptor, not TLR2, is the main detector of zymosan in peritonitis

The in vitro macrophage response to zymosan has been attributed to Toll-like receptor 2 (TLR2). Whether TLR2 is obligatory for the zymosan-induced in vivo response has not been assessed. The importance of this question is underscored by the fact that zymosan activates complement in a cell-independent manner. We have investigated whether the in vitro observation of TLR2 as the dominant zymosan receptor on macrophages would translate to an experimental peritonitis model in vivo. We have treated mice with zymosan, resulting in significant leukocyte (primarily neutrophil) accumulation in the peritoneum at 4 h. Zymosan-mediated leukocyte recruitment was TLR2 independent, but was predominantly dependent on the complement components, C3 and C5a with a minor contribution from LTB4. Peritoneal neutrophilia was 50% mast cell dependent and this defect was reproduced using C5a receptor (C5aR)-deficient mast cells in mast cell-deficient mice, suggesting that C5aR is responsible for mast cell activation following zymosan challenge. By 24 h, the response to zymosan involved primarily monocyte recruitment and was C3 and C5aR independent. Taken together, these studies indicate that the in vivo inflammatory response to zymosan does not necessarily mimic the TLR2 dependence observed in vitro, and that complement plays a dominant role in early, but not late, zymosan-mediated peritonitis.

Neutrophils-derived peroxynitrite contributes to acute hyperalgesia and cell influx in zymosan arthritis

We investigated the contribution of neutrophils to joint hyperalgesia and peroxynitrite formation in zymosan arthritis. Rats received 1 mg zymosan intra-articular, and joint hyperalgesia was measured using the rat knee-joint articular incapacitation test. After 6 h, joint exudates were collected by aspiration for the assessment of cell influx, myeloperoxidase activity, and nitrite (as an index of nitric oxide formation) levels. Nitrotyrosine content, used as an index of peroxynitrite formation, was measured in joint exudates, using enzyme-linked immunosorbent assay. A group of rats was rendered neutropenic through the administration of a rabbit anti-rat neutrophil antibody (2 ml kg(-1), i.p.) 30 min before injection of 1 mg zymosan intra-articular. Other groups received uric acid (100 or 250 mg kg(-1), i.p.), the peroxynitrite scavenger, 30 min before 1 mg zymosan intra-articular. Controls received the vehicle. The significant inhibition of joint hyperalgesia in neutropenic animals was associated to significantly decreased cell influx, myeloperoxidase activity, nitric oxide, and nitrotyrosine levels in the joint exudates, as compared to naive rats. Uric acid administration inhibited both hyperalgesia and cell influx, as compared to controls. Neutrophils are involved in both nitric oxide and peroxynitrite formation in zymosan arthritis, thereby contributing to acute joint hyperalgesia. Scavenging of reactive nitrogen species (e.g. peroxynitrite) inhibits neutrophil migration and joint hyperalgesia in the acute phase of zymosan arthritis in rats.

A second form of collagenous lectin from the tunicate, Styela plicata

This study characterised a 90 kDa lectin from an invertebrate chordate, the tunicate Styela plicata. One- and two-dimensional electrophoresis showed that the apparent molecular weight of this protein is maintained under both reducing and non-reducing conditions, suggesting that its native form is a monomer. The 90 kDa lectin was localised within a single type of hemocyte (morula cells), but was secreted from those cells when tunicates were challenged with the inflammatory elicitor, zymosan. Functional studies showed that the 90 kDa protein binds to galactose-based sugars in a divalent cation-dependent manner. Amino acid composition analysis and N-terminal amino acid sequencing indicated that the 90 kDa lectin is related to a previously characterised, collagenous lectin from S. plicata, splic43. However, peptide mass fingerprinting identified numerous differences between the two proteins. This suggests that the 90 kDa molecule represents a novel protein that is involved in host defence.

Cloning and characterisation of a serine proteinase from the haemocytes of mud crab Scylla serrata

A serine proteinase (SP) cDNA was cloned from the haemocytes of mud crab Scylla serrata using oligonucleotide primers and RT-PCR. Both 3'- and 5'-regions were isolated by rapid amplification of cDNA end (RACE) method. Analysis of the nucleotide sequence revealed that the cDNA clone has an open reading frame of 1,131 bp encoding a protein of 376 amino acids. The calculated molecular mass of the SP mature protein is 39.54 kDa with an estimated pI of 5.37. The C-terminal half of S. serrata SP is composed of a trypsin-like domain, with a sequence similar to that of other invertebrate and vertebrate SP domain. The typical catalytic triad of SP required for functional activity (His150, Asp217 and Ser331) was conserved in the polypeptide sequence. Sequence comparison showed that SP deduced amino acid has an overall similarity of 55%, 51% and 50% to SP deduced amino acid from spiny lobster Panulirus argus, horseshoe crab Tachypleus tridentatus and crayfish Pacifastaus leniusculus, respectively. The SP was strongly expressed in haemocytes, but was weakly expressed in heart, eyestalk and antennules. The SP transcript decreased significantly for the S. serrata following 3 days exposure to pH 9.5. However, the SP transcript increased significantly 24 h post-zymosan injection.

Efficient Immunization and Cross-Priming by Vaccine Adjuvants Containing TLR3 or TLR9 Agonists Complexed to Cationic Liposomes

Complexing TLR9 agonists such as plasmid DNA to cationic liposomes markedly potentiates their ability to activate innate immunity. We therefore reasoned that liposomes complexed with DNA or other TLR agonists could be used as effective vaccine adjuvants. To test this hypothesis, the vaccine adjuvant effects of liposomes complexed to TLR agonists were assessed in mice. We found that liposomes complexed to nucleic acids (liposome-Ag-nucleic acid complexes; LANAC) were particularly effective adjuvants for eliciting CD4(+) and CD8(+) T cell responses against peptide and protein Ags. Notably, LANAC containing TLR3 or TLR9 agonists effectively cross-primed CD8(+) T cell responses against even low doses of protein Ags, and this effect was independent of CD4(+) T cell help. Ag-specific CD8(+) T cells elicited by LANAC adjuvants were functionally active and persisted for long periods of time in tissues. In a therapeutic tumor vaccine model, immunization with the melanoma peptide trp2 and LANAC adjuvant controlled the growth of established B16 melanoma tumors. In a prophylactic vaccine model, immunization with the Mycobacterium tuberculosis protein ESAT-6 with LANAC adjuvant elicited significant protective immunity against aerosol challenge with virulent M. tuberculosis. These results suggest that certain TLR agonists can be combined with cationic liposomes to produce uniquely effective vaccine adjuvants capable of eliciting strong T cell responses against protein and peptide Ags.

Yeast zymosan, a stimulus for TLR2 and dectin-1, induces regulatory antigen-presenting cells and immunological tolerance

Emerging evidence suggests critical roles for APCs in suppressing immune responses. Here, we show that zymosan, a stimulus for TLR2 and dectin-1, regulates cytokine secretion in DCs and macrophages to induce immunological tolerance. First, zymosan induces DCs to secrete abundant IL-10 but little IL-6 and IL-12(p70). Induction of IL-10 is dependent on TLR2- and dectin-1-mediated activation of ERK MAPK via a mechanism independent of the activation protein 1 (AP-1) transcription factor c-Fos. Such DCs stimulate antigen-specific CD4+ T cells poorly due to IL-10 and the lack of IL-6. Second, zymosan induces F4-80+ macrophages in the splenic red pulp to secrete TGF-beta. Consistent with these effects on APCs, injection of zymosan plus OVA into mice results in OVA-specific T cells that secrete little or no Th1 or Th2 cytokines, but secrete robust levels of IL-10, and are unresponsive to challenge with OVA plus adjuvant. Finally, coinjection of zymosan with OVA plus LPS suppresses the response to OVA via a mechanism dependent on IL-10, TGF-beta, and lack of IL-6. Together, our data demonstrate that zymosan stimulates IL-10+ IL-12(p70)- IL-6low regulatory DCs and TGF-beta+ macrophages to induce immunological tolerance. These data suggest several targets for pharmacological modulation of immune responses in various clinical settings.

Female genital tract immunization: evaluation of candidate immunoadjuvants on epithelial cell secretion of CCL20 and dendritic/Langerhans cell maturation

The female genital tract is an important site for numerous pathogens entry. Local immunization, generating specific mucosal IgA and systemic IgG, represents an interesting alternative immunization pathway. However, such a vaccine strategy needs mucosal adjuvants to obtain the best immune response. Considering that the immunization process is mainly dependent on the capture and on the transport of the antigen by Langerhans cells, we evaluated potential adjuvant molecules by analysing their effects on the CCL20 secretion by endocervical and exocervical/vaginal epithelial cells as well as on dendritic cell and Langerhans cell maturation. We demonstrated that DC-Chol and Zymosan are the most efficient mucosal candidate immunoadjuvants that generate a strong increase of CCL20 secretion by the two epithelial cell lines and the maturation of dendritic and Langerhans cells, respectively.

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

OBJECTIVE

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.

DESIGN

Prospective, randomized study.

SETTING

University-based research laboratory.

SUBJECTS

Male CD mice.

INTERVENTIONS

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.

MEASUREMENTS AND MAIN RESULTS

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.

CONCLUSIONS

This study provides evidence, for the first time, that erythropoietin attenuates the degree of zymosan-induced nonseptic shock in mice.

Inflammation and enhanced nociceptive responses to bladder distension produced by intravesical zymosan in the rat

Background

Mycotic infections of the bladder produce pain and inflammatory changes. The present study examined the inflammatory and nociceptive effects of the yeast cell wall component, zymosan, when admininstered into the urinary bladder in order to characterize this form of bladder sensitization.

Methods

Parametric analyses of the time-course (0–48 hr) and concentration (0–2% solutions) variables associated with intravesical zymosan-induced bladder inflammation were performed in female rats. Plasma extravasation of Evan's Blue dye was used as a measure of tissue inflammation. Cardiovascular and visceromotor responses to urinary bladder distension were used as measures of nociception.

Results

Zymosan-induced bladder inflammation, as indexed by plasma extravasation of Evan's Blue, was significantly greater in rats treated with either 1 or 2% solutions as compared to either 0.1 or 0.5% zymosan solutions. In time-course studies (1 – 48 hr post-treatment), 1% zymosan-induced inflammation progressively increased with time following administration, was greatest at 24 hr and began to normalize by 48 hr. In the studies of inflammation-induced changes in nociception, arterial blood pressure (ABP) and visceromotor responses to graded distension of the urinary bladder were significantly increased relative to controls 24 hr after zymosan administration.

Conclusion

These studies provide important time-course and solution concentration parameters for studies of zymosan-induced inflammation of the bladder and suggest utility of this model for the study of bladder-related pain.

Intravitreal macrophage activation enables cat retinal ganglion cells to regenerate injured axons into the mature optic nerve

In mature mammals, retinal ganglion cells (RGCs) are generally unable to regenerate injured axons into the optic nerve. Here, we report that an intravitreal injection of either of two macrophage activators, oxidized galectin-1 or zymosan, strongly enhanced the regeneration of transected RGC axons beyond an optic nerve crush site in adult cats. Using WGA-HRP as an anterograde tracer, we found that injection of either macrophage activator caused many axons to grow into the distal optic nerve when evaluated 14 days later, with the strongest effects seen after injecting 100 ng of galectin-1. Elongation continued for at least another 2 weeks. Control eyes injected with saline contained very few labeled axons extending across the crush site. Elevation of intracellular cAMP levels using forskolin also enhanced regeneration beyond the crush site to some extent, but this treatment did not augment the effect of galectin-1 any further. These results indicate that RGCs of adult cats are capable of reverting to an active growth state and at least partially overcoming an inhibitory CNS environment as a result of intravitreal macrophage activation.

Annexin 1-deficient neutrophils exhibit enhanced transmigration in vivo and increased responsiveness in vitro

The role of the endogenous anti-inflammatory mediator annexin 1 (AnxA1) in controlling polymorphonuclear leukocyte (PMN) trafficking and activation was addressed using the recently generated AnxA1 null mouse. In the zymosan peritonitis model, AnxA1 null mice displayed a higher degree (50-70%) of PMN recruitment compared with wild-type littermate mice, and this was associated with reduced numbers of F4/80+ cells. Intravital microscopy analysis of the cremaster microcirculation inflamed by zymosan (6 h time-point) indicated a greater extent of leukocyte emigration, but not rolling or adhesion, in AnxA1 null mice. Real-time analysis of the cremaster microcirculation did not show spontaneous activation in the absence of AnxA1; however, superfusion with a direct-acting PMN activator (1 nM platelet-activating factor) revealed a subtle yet significant increase in leukocyte emigration, but not rolling or adhesion, in this genotype. Changes in the microcirculation were not secondary to alterations in hemodynamic parameters. The phenotype of the AnxA1 null PMN was investigated in two in vitro assays of cell activation (CD11b membrane expression and chemotaxis): the data obtained indicated a higher degree of cellular responses irrespective of the stimulus used. In conclusion, we have used a combination of inflammatory protocols and in vitro assays to address the specific counter-regulatory role of endogenous AnxA1, demonstrating its inhibitory control on PMN activation and the consequent impact on the inflamed microcirculation.

Skeletal Muscle wasting and contractile performance in septic rats

We investigated the temporal effects of sepsis on muscle wasting and function in order to study the contribution of wasting to the decline in muscle function; we also studied the fiber-type specificity of this muscle wasting. Sepsis was induced by injecting rats intraperitoneally with a zymosan suspension. At 2 h and at 2, 6, and 11 days after injection, muscle function was measured using in situ electrical stimulation, Zymosan injection induced severe muscle wasting compared to pair-fed and ad libitum fed controls. At 6 days, isometric force-generating capacity was drastically reduced in zymosan-treated rats. We conclude that this was fully accounted fo by the reduction of muscle mas. At day 6, we also observed increased activity of the 20S proteasome in gastrocnemius but not soleus muscle from septic rats. In tibialis anterior but not in soleus, muscle wasting occurred in a fiber-type specific fashion, i.e., the reduction in cross-sectional area was significantly smaller in type 1 than type 2A and 2B/X fibers. These findings suggest that both the inherent function of a muscle and the muscle fiber-type distribution affect the responsiveness to catabolic signals.

Altered chemokine response in an animal model of multiple organ dysfunction syndrome induced by zymosan

PURPOSE

The aim of this study was to determine the monocyte chemoattractant protein-1 (MCP-1) response over time in an animal model of multiple organ dysfunction syndrome (MODS).

METHODS

On day 0, rats were randomized to receive an intraperitoneal injection of zymosan at a dose of 1 mg/g of body weight (n = 36) or vehicle (n = 9). Serum, peritoneal lavage (PL) fluid, and bronchoalveolar lavage (BAL) fluid were collected from 3 rats in the control group and 6 to 7 rats in the zymosan group at days 1, 5, and 12. Monocyte chemoattractant protein-1 concentrations were determined by enzyme-linked immunosorbent assay.

RESULTS

The authors observed a 47% mortality in the zymosan-treated rats. Monocyte chemoattractant protein-1 levels were unchanged in the serum, PL, and BAL of control animals. Both serum and PL MCP-1 were significantly higher in zymosan-treated rats on days 1 (P < .01) and 5 (P < .05) when compared with controls. By day 12, no difference between the 2 groups was observed. No significant difference was noted in BAL MCP-1.

CONCLUSIONS

Chemokines are increased systemically and locally during MODS. The fact that MCP-1 is significantly higher early in the course of MODS may suggest that this chemokine is important in the early inflammatory changes that lead to MODS later in the course of this illness.

Contact activation and down regulation of neutrophils by cellulose wound dressings can be prevented by radical scavengers

Neutrophil interaction with wound dressing materials was studied. A meshed non-woven cellulose was chosen as model dressing. Neutrophils isolated from human blood was added to the cellulose, and the production of reactive oxygen species was measured by luminol-amplified chemiluminescence. The respiratory burst response of the neutrophils was found to be activated upon contact with cellulose. The contact activation of the cells increased when the cellulose was oxidised with periodate, and decreased when the cellulose was reduced with cyanoborohydride, indicating that the activation of the respiratory burst response was due to carbonyl-induced stress. The contact activation of the respiratory burst response resulted in an inability of the neutrophils to respond to a secondary stimulation with zymosan. When radical scavenger enzymes were covalently bound to the cellulose, the contact activation was decreased and the ability to respond to stimuli was increased. Addition of the molecular scavenger glutathione (GSH) did not decrease the cell activation upon cellulose contact, but the cell showed an intact ability to respond to secondary stimuli after cellulose contact. In conclusion, the results show that the environmental redox potential effects neutrophils in a situations of clinical interest and that the addition of radical scavengers protects the neutrophils against material-induced damage resulting in preserved cell function.

A synthetic, non-peptide CXCR2 antagonist blocks MIP-2-induced neutrophil migration in mice

Non-peptide antagonists of chemokine receptors are considered an intriguing alternative for the treatment of acute and chronic diseases. Particularly the recruitment of neutrophils to inflammatory sites often causes harmful side effects and is mediated by chemokine ligands of the CXC chemokine receptor 2 (CXCR2). Hence, this receptor has been proposed as an important target for novel drugs. This study investigates the potential of the non-peptide CXCR2 antagonist SB 455821 to block neutrophil migration in mice. By using bone marrow derived neutrophils we established a migration assay which revealed SB 455821 as a potent inhibitor of macrophage inflammatory protein 2 (MIP-2)-induced neutrophil migration in vitro (IC50-20 nM). In vivo, injection of MIP-2 into the peritoneal cavities of mice markedly increased neutrophil numbers in peritoneal lavages which were reduced to control levels by co-administration of SB 455821 indicating that the compound effectively binds to the receptor under physiological conditions and exhibits biological activity in vivo. Nevertheless, using intraperitoneal injection of zymosan as a complex inflammatory stimulus, SB 455821 was unable to block neutrophil recruitment to the peritoneal cavity of mice possibly due to other chemotactic mediators overruling signals derived from CXCR2 ligands. Our data show that SB 455821 blocks MIP-2-induced neutrophil migration in vitro and after injection in mice suggesting that selective CXCR2 antagonists may be useful drugs in diseases where neutrophil accumulation plays a major role and leads to exacerbation of acute or chronic inflammations.

Neutrophil elastase (NE)-deficient mice demonstrate a nonredundant role for NE in neutrophil migration, generation of proinflammatory mediators, and phagocytosis in response to zymosan particles in vivo

Neutrophil elastase (NE) remains a controversial player in the process of leukocyte transmigration and much of this controversy stems from conflicting reports on the effects of NE inhibitors. The availability of NE-deficient mice (NE(-/-)) provides a clean and elegant tool for the study of leukocyte migration in vivo. In this study, NE(-/-) mice were used to investigate the role of NE in leukocyte migration through cremasteric venules, as observed by intravital microscopy, induced by locally administered cytokines IL-1beta and TNF-alpha and the particulate stimulus, zymosan. Although no defects in leukocyte responses induced by the cytokines were observed, zymosan-induced leukocyte firm adhesion and transmigration was suppressed in NE(-/-) mice. These responses were also inhibited in wild-type mice when zymosan was coinjected with a specific NE inhibitor. Quantification of inflammatory mediator levels in homogenates of zymosan-stimulated tissues indicated reductions in levels of IL-1beta, KC, and macrophage inflammatory protein-1alpha in NE(-/-) mice. Furthermore, phagocytosis of fluorescent zymosan particles, as observed by intravital microscopy, was diminished in NE-deficient animals. Collectively, the findings of this study indicate a nonredundant role for NE in zymosan-induced leukocyte firm adhesion and transmigration, and that this defect is associated with impaired generation of proinflammatory mediators as well as phagocytosis of zymosan particles in vivo.

Role of 5-lipoxygenase in the multiple organ failure induced by zymosan

OBJECTIVE

This study investigated the role of 5-lipoxygenase in the pathogenesis of multiple organ failure (MOF) induced by zymosan.

DESIGN

Male mice with a targeted disruption of the 5-lipoxygenase gene (5-LOKO) and littermate wild-type (WT) controls (5-LOWT) were used to evaluate the role of 5-lipoxygenase (5-LO) in the pathogenesis of MOF.

SETTING

University research laboratory.

INTERVENTIONS AND MEASUREMENTS

MOF was induced by peritoneal injection of zymosan (500 mg/kg i.p. as a suspension in saline) in 5-LOWT and in 5-LOKO mice. MOF was assessed 18 h after administration of zymosan and monitored for 12 days (for loss of body weight and mortality).

RESULTS

A severe inflammatory process induced by zymosan administration in WT mice coincided with the damage of lung and small intestine, as assessed by histological examination. Myeloperoxidase activity indicative of neutrophil infiltration and lipid peroxidation were significantly increased in zymosan-treated WT mice. Zymosan in the WT mice also induced a significant increase in the plasma level of nitrite/nitrate. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to ICAM-1 and P-selectin in the lung and intestine of zymosan-treated WT mice. In contrast, the degree of (a) peritoneal inflammation and tissue injury, (b) upregulation/expression of P-selectin and ICAM-1, and (c) neutrophil infiltration were markedly reduced in intestine and lung tissue obtained from zymosan-treated 5-LO deficient mice. Zymosan-treated 5-LOKO showed also a significantly decreased mortality.

CONCLUSIONS

These findings clearly demonstrate that 5-LO exerts a role in zymosan-induced nonseptic shock.

Effects of Low-Intensity Ultrahigh Frequency Electromagnetic Radiation on Inflammatory Processes

Low-intensity ultrahigh frequency electromagnetic radiation (42 GHz, 100 microW/cm(2)) reduces the severity of inflammation and inhibits production of active oxygen forms by inflammatory exudate neutrophils only in mice with inflammatory process. These data suggest that some therapeutic effects of electromagnetic radiation can be explained by its antiinflammatory effect which is realized via modulation of functional activity of neutrophils in the focus of inflammation.

Rosiglitazone, a ligand of the peroxisome proliferator-activated receptor-gamma, reduces the development of nonseptic shock induced by zymosan in mice

OBJECTIVE

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors that are related to retinoid, steroid, and thyroid hormone receptors. The PPAR-gamma receptor subtype appears to play a pivotal role in the regulation of cellular proliferation and inflammation. Rosiglitazone (Avandia) is a PPAR-gamma agonist (the most potent PPAR-gamma agonist of the thiazolidinedione antidiabetics). In the present study, we investigated the effects of rosiglitazone on the development of nonseptic shock caused by zymosan in mice.

DESIGN

Experimental study.

SETTING

University laboratory.

SUBJECTS

Male CD mice.

INTERVENTIONS

We investigated the effects of rosiglitazone (3 mg/kg) on the development of nonseptic shock caused by zymosan (500 mg/kg, administered intraperitoneally as a suspension in saline) in mice.

MEASUREMENTS AND MAIN RESULTS

Organ failure and systemic inflammation in rats were assessed 18 hrs after administration of zymosan and/or rosiglitazone and monitored for 12 days (for loss of body weight and mortality rate). Treatment of mice with rosiglitazone (3 mg/kg intraperitoneally, 1 and 6 hrs after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan. Rosiglitazone also attenuated the lung, liver, and pancreatic injury and renal dysfunction caused by zymosan as well as the increase in myeloperoxidase activity and malondialdehyde concentrations caused by zymosan in the lung and intestine. Immunohistochemical analysis for inducible nitric oxide synthase, nitrotyrosine, and poly(adenosine diphosphate-ribose) revealed positive staining in lung and intestine tissues obtained from zymosan-treated mice. The degree of staining for nitrotyrosine, inducible nitric oxide synthase, and poly(adenosine diphosphate-ribose) was markedly reduced in tissue sections obtained from zymosan-treated mice that received rosiglitazone. To elucidate whether the protective effects of rosiglitazone are related to activation of the PPAR-gamma receptor, we also investigated the effect of a PPAR-gamma antagonist, GW 9662, on the protective effects of rosiglitazone. GW 9662 (1 mg/kg administered intraperitoneally 30 mins before treatment with rosiglitazone) significantly antagonized the effect of the PPAR-gamma agonist and thus abolished the protective effect.

CONCLUSIONS

This study provides evidence, for the first time, that rosiglitazone attenuates the degree of zymosan-induced nonseptic shock in mice.

Reactive nitrogen species scavenging, rather than nitric oxide inhibition, protects from articular cartilage damage in rat zymosan-induced arthritis

1. The contribution of nitric oxide (NO) and peroxynitrite (PN) to inflammation in a zymosan-induced (1 mg, intra-articular, i.art.) rat model of arthritis was assessed by histopathology and by measuring the glycosaminoglycan (GAG) content of the articular cartilage. 2. Progression of the chronic synovitis in zymosan-induced arthritis (ZYA) was associated with increased nitrite and nitrotyrosine (3-NT) levels in the joint exudates that paralleled a progressive loss of the GAG content. An increase in 3-NT was also observed after i.art. PN. 3. The nonselective nitric oxide synthase (NOS) inhibitor l-N(G)-nitroarginine methyl ester (25-75 mg x kg(-1)day(-1)) or the selective inducible NOS inhibitor aminoguanidine (50-100 mg x kg(-1)day(-1)) given 1 h before (prophylactic) or 3 days after (therapeutic) injection of the zymosan ameliorated the synovitis, but worsened the GAG loss, as measured at the end of the experiment (day 7). 4. The PN scavenger uric acid (100-250 mg x kg(-1) i.p. four times daily) given prophylactically until the end of the experiment (day 14), in a dose compatible with its PN scavenging activity, significantly decreased both the synovitis and the GAG loss. 5. In conclusion, PN formation is associated with cartilage damage in addition to proinflammatory activity in ZYA. NOS inhibitors and a PN scavenger were able to reduce the cellular infiltration, while displaying opposite effects on cartilage homeostasis either by enhancing or ameliorating the damage, respectively.

Deficiency of NADPH oxidase components p47phox and gp91phox caused granulomatous synovitis and increased connective tissue destruction in experimental arthritis models

Recent studies indicated that the nicotinamide dinucleotide phosphate oxidase (NADPH) oxidase-derived oxygen radicals plays a deleterious role in arthritis. To study this in more detail, gonarthritis was induced in NADPH oxidase-deficient mice. Mice received an intraarticular injection of either zymosan, to elicit an irritant-induced inflammation, or poly-L-lysine coupled lysozyme, to evoke an immune-complex mediated inflammation in passively immunized mice. In contrast to wild-type mice, arthritis elicited in both p47phox(-/-) and gp91(-/-) mice showed more severe joint inflammation, which developed into a granulomatous synovitis. Treatment with either Zileuton or cobra venom factor showed that the chemokines LTB4 and complement C3 were not the driving force behind the aggravated inflammation in these mice. Arthritic NADPH oxidase-deficient mice showed irreversible cartilage damage as judged by the enhanced aggrecan VDIPEN expression, and chondrocyte death. Furthermore, only in the absence of NADPH oxidase-derived oxygen radicals, the arthritic joints showed osteoclast-like cells, tartrate-resistant acid phosphatase (TRAP)-positive/multinucleated cells, extensive bone erosion, and osteolysis. The enhanced synovial gene expression of tumor necrosis factor-alpha, interleukin-1alpha, matrix metalloproteinase (MMP)-3, MMP-9 and receptor activator of NF-kappaB ligand (RANKL) might contribute to the aggravated arthritis in the NADPH oxidase-deficient mice. This showed that the involvement of NADPH oxidase in arthritis is probably far more complex and that oxygen radicals might also be important in controlling disease severity, and reducing joint inflammation and connective tissue damage.

[A small dose of intraperitoneal injection of zymosan induces systemic inflammatory response and multiple organ dysfunction following gut ischemia-reperfusion injury]

OBJECTIVE

To investigate the effects of a small dose of intraperitoneal injection of zymosan following gut ischemia-reperfusion injury on systemic inflammatory response and distant organ function.

METHODS

Wistar rats were randomly divided into three groups: gut ischemia-reperfusion injury (I-R) alone, intraperitoneal injection of zymosan (Z) alone, and gut ischemia-reperfusion followed by intraperitoneal injection of zymosan (M). Gut (I-R) was produced by occluding superior mesenteric artery for 60 minutes followed by gut reperfusion. A small dose(125 mg/kg) of zymosan was given intraperitoneally at 12 hours after recovery of gut blood flow.

RESULTS

Systemic inflammatory responses were found in all rats of three groups. The plasma level of tumor necrosis factor-alpha and activities of myeloperoxidase in lungs and intestines were significantly higher in animals in M group compared with those in I-R and Z groups. The incidence of multiple organ dysfunction syndrome (MODS) and mortality rate at 72 hours postinjury in two-hits group were significantly higher than those in I-R and Z group.

CONCLUSION

A small dose of intraperitoneal injection of zymosan could induce systemic inflammatory response and multiple organ dysfunction more readily when there is a precedent gut ischemia-reperfusion injury.

Modulation of Mac-1 (CD11b/CD18)-mediated adhesion by the leukocyte-specific protein 1 is key to its role in neutrophil polarization and chemotaxis

Leukocyte-specific protein 1 (LSP1) is an intracellular filamentous-actin binding protein which modulates cell motility. The cellular process in which LSP1 functions to regulate motility is not yet identified. In this study, we show that LSP1 negatively regulates fMLP-induced polarization and chemotaxis of neutrophils through its function on adhesion via specific integrins. Using LSP1-deficient (Lsp1(-/-)) mice, we show increased neutrophil migration into mouse knee joints during zymosan-induced acute inflammation, an inflammatory model in which the number of resident synoviocytes are not affected by LSP1-deficiency. In vitro chemotaxis experiments performed by time-lapse videomicroscopy showed that purified Lsp1(-/-) bone-marrow neutrophils exhibit an increased migration rate toward a gradient of fMLP as compared with wild-type neutrophils. This difference was observed when cells migrated on fibrinogen, but not fibronectin, suggesting a role for LSP1 in modulating neutrophil adhesion by specific integrins. LSP1 is also a negative regulator of fMLP-induced adhesion to fibrinogen or ICAM-1, but not to ICAM-2, VCAM-1, or fibronectin. These results suggest that LSP1 regulates the function of Mac-1 (CD11b/CD18), which binds only to fibrinogen and ICAM-1 among the substrates we tested. fMLP-induced filamentous actin polarization is also increased in the absence of LSP1 when cells were layered on fibrinogen, but not on fibronectin. Our findings suggest that the increased neutrophil recruitment in Lsp1(-/-) mice during acute inflammation derives from the negative regulatory role of LSP1 on neutrophil adhesion, polarization, and migration via specific integrins, such as Mac-1, which mediate neutrophil responses to chemotactic stimuli.

Organ damage in zymosan-induced multiple organ dysfunction syndrome in mice is not mediated by inducible nitric oxide synthase

OBJECTIVE

To examine the role of inducible nitric oxide synthase (iNOS) in the development of the multiple organ dysfunction syndrome (MODS) in a murine model by using either a selective iNOS inhibitor or iNOS knockout mice.

DESIGN

Prospective randomized laboratory study.

SETTING

Central animal laboratory and experimental laboratory.

SUBJECTS

Fifty inbred C57BL/6 mice, 39 iNOS knockout (-/-) mice, and 30 wild-type (+/+) mice, 7-9 wks old, weighing 20-25 g.

INTERVENTIONS

Mice received an aseptic intraperitoneal injection of 40 microg of lipopolysaccharide followed by zymosan at a dose of 1 mg/g of body weight 6 days later (day 0). In experiment 1, C57BL/6 mice additionally received intraperitoneal injections with 5 mg of aminoguanidine or saline every 12 hrs, from 4 days after the injection of zymosan onward. In experiment 2, both iNOS-/- mice and corresponding wild-type (iNOS+/+) mice were treated with lipopolysaccharide and zymosan.

MEASUREMENTS AND MAIN RESULTS

In all animals, the injection of zymosan induced an acute peritonitis, followed by an apparent recovery. From approximately day 6 onward, animals entered the third-MODS-like-phase, indicated by weight loss, a decrease in body temperature, and significant mortality rates. Quantitative reverse transcriptase polymerase chain reaction and immunochemistry revealed a strongly increased expression of iNOS messenger RNA and iNOS protein in livers of mice in the last phase. However, neither the in vivo administration of aminoguanidine to C57BL/6 mice nor the complete absence of iNOS enzyme (iNOS-/- mice) had a beneficial effect on survival rate, body temperature, or body weight. In addition, relative lung, liver, and spleen weights and lung scores were not different between experimental groups.

CONCLUSIONS

The current results strongly argue against an essential and causative role of iNOS in the development of organ damage in our murine model of MODS.

Continuous dialysis with bicarbonate/lactate-buffered peritoneal dialysis fluids results in a long-term improvement in ex vivo peritoneal macrophage function

To circumvent the potentially negative consequences of long-term exposure to unphysiologic acidic lactate-buffered peritoneal dialysis fluids (PDF), neutral pH solutions buffered with bicarbonate/lactate have recently been introduced in phase 2 and 3 clinical trials. This study examines the longitudinal changes in peritoneal macrophage (PMØ) function in patients dialyzed continuously with either lactate (LPD; 40 mM lactate, pH 5.2)-buffered or bicarbonate/lactate (TBL; 25 mM/15 mM bicarbonate/lactate, pH 7.3)-buffered PDF. Before the study, during the run in period of a phase 3 clinical trial, all patients had been taking LPD for at least the previous 18 wk. At the beginning of the study (day 0), both constitutive and serum-treated zymosan (STZ) stimulated tumor necrosis factor alpha (TNF-alpha) synthesis were assessed in PMØ isolated from 12-h dwell effluent (with 1.36% glucose) in all patients. The patients were subsequently randomized to either continuous TBL or LPD therapy and PMØ function was assessed after further 3- and 6-mo periods in all patients. At all time points measured STZ induced a dose-dependent increase in PMØ TNF-alpha secretion (P = 0.043 versus control for doses greater than 100 microg/ml). In patients continuously dialyzed with LPD, constitutive PMØ TNF-alpha synthesis levels (mean +/- SEM, pg/10(6) PMØ per18 h, n = 5 patients) were 154 +/- 65, 261 +/- 60, and 101 +/- 99 at 0, 3, and 6 mo, respectively. Stimulated STZ (1000 microg/ml) levels were 1340 +/- 519, 1046 +/- 586, and 758 +/- 250 at 0, 3, and 6 mo, respectively. In patients dialyzed with TBL, constitutive PMØ TNF-alpha synthesis levels (pg/10(6) PMØ per 18 h, n = 5 patients) were 300 +/- 136, 106 +/- 35, and 213 +/- 62 at 0, 3, and 6 mo, respectively. Stimulated STZ (1000 microg/ml) levels were 1969 +/- 751, 1541 +/- 330, and 2670 +/- 671 at 0, 3, and 6 mo, respectively. At 6 mo, STZ-stimulated PMØ TNF-alpha synthesis was significantly higher in patients treated with TBL compared with those treated with LPD (P = 0.0035). These data suggest that in patients continuously dialyzed with a neutral pH solution, there is a long-term improvement in PMØ function compared with patients on conventional therapy. Better PMØ function suggests improved host defense status and may affect the peritoneum's susceptibility to infection and potentially reduce the negative consequences of repeated intraperitoneal inflammation on long-term membrane function.

Opsonophagocytosis versus lectinophagocytosis in human milk macrophages

Some important immunoprotective effects of human breast milk have been attributed to the presence of macrophages. We investigated the generation of superoxide anion (O2-) by monocytes and human milk macrophages after stimulation with opsonized and unopsonized zymosan in the absence and presence of mannose as an inhibitor to investigate lectinophagocytic and opsonophagocytic properties. Peripheral blood monocytes generated more O2- than human milk macrophages (417,4 + 79,1 nmol O2-/mg protein vs. 216,1 +/-15,1 nmol O2-/mg protein, p<0,05) after stimulation with opsonized zymosan. When unopsonized zymosan was used as a serum-independent stimulus monocytes generated slightly less O2- in comparison to human milk macrophages (150,8 +/- 34,5 nmol/mg protein vs. 176,1 +/- 18 nmol O2-/mg protein, p<0,05). These findings demonstrate that the proportion of opsonin-independent phagocytosis in human milk macrophages is higher than in monocytes (82% vs. 36%). When mannose was used as an inhibitor a significantly higher reduction of O2- generation occurred in human milk macrophages compared to monocytes stimulated with opsonized zymosan, whereas no difference was found when unopsonized zymosan was used. These results indicate that human milk macrophages are stimulated to a greater extent by opsonin-independent mechanisms than blood borne monocytes. As the colostrum and the intestinal environment of the neonate offers only a little amount of opsonins like complement and immunoglobulin G, such a differentiation to lectinophagocytic properties could bear a great advantage for protective functions of human milk macrophages.

The involvement of multiple protease-antiprotease systems and gut origin sepsis in zymosan-associated endothelial barrier injury and multiple organ dysfunction in rats

Multiple organ dysfunction syndrome is a dominant cause of mortality in the intensive care unit. Experimentally, a condition similar to the multiple organ dysfunction syndrome can be induced by the intraperitoneal injection of sterile zymosan. In the present study we investigate potential alterations in multiple organ functions, endothelial permeability, and antiproteinases after intraperitoneal injection of zymosan at various doses. Zymosan-induced generalized inflammation lead to endothelial barrier injury in multiple organs/tissues, a decrease in systemic arterial pressure, impaired organ function and gut defence function, and consumption of protease inhibitors, particularly the consumption of alpha2 antiplasmin. Endothelial barrier injury appears to present a dose- and organ-dependent pattern in multiple organs/tissues, and the increase in endothelial barrier permeability occurred prior to organ dysfunction. Zymosan induced the development of multiple organ dysfunction syndrome, probably initiating multiple protease-antiprotease systems, particularly the fibrinolytic system, leading to endothelial barrier injury, tissue edema, parenchymal cell damage, and eventual organ dysfunction, potentially augmented by a secondary bacterial infection.

Production of chemokines in vivo in response to microbial stimulation

Members of the chemokine gene superfamily are known to play a central role in leukocyte extravasation; however, their involvement in acute inflammation in response to micro-organisms has not yet been well studied. We have therefore investigated the role of murine macrophage-inflammatory protein (muMIP) 1alpha and muMIP-2 in the inflammatory response mounted against the bacteria Salmonella enteritidis and the Sacchromyces cerevisiae cell wall component, zymosan. Leukocyte extravasation was monitored in murine s.c. air pouches. Both agonists induced accumulation of leukocytes in a dose- and time-dependent manner, with the response peaking after 4 h and declining thereafter. The inflammatory exudate comprised mainly neutrophils; however, an increase in eosinophil accumulation was also observed in response to zymosan. The production of both muMIP-1alpha and muMIP-2 increased with time in response to both the agonists, although production was more sustained in response to the bacteria. Prior treatment of mice with neutralizing Abs against muMIP-1alpha or muMIP-2, either alone or in combination, failed to attenuate the accumulation of leukocytes in response to the agonists. In contrast, the anti-muMIP-2 Abs significantly inhibited leukocyte recruitment in response to S. enteritidis in complement-deficient mice. Taken together, these data show that while muMIP-1alpha and muMIP-2 are produced in response to phagocytosis of micro-organisms in s.c. tissue, under these circumstances components of the complement pathway appear to play a dominant role in the recruitment of neutrophils.

Dual effect of cAMP on the writhing response in mice

The intraperitoneal injection of agents that increase the intracellular level of cyclic AMP (cAMP), reduced significantly the number of writhes induced by acetic acid and zymosan in mice. However, dibutyryl cyclic AMP (Db-cAMP) induced a dual response: (a) low doses caused antinociception, and (b) a high dose potentiated the nociceptive effect of a low concentration of acetic acid. High doses of Db-cAMP also reversed the antinociceptive effect of dexamethasone and the depletion of resident peritoneal cells. We also demonstrated that a low dose of Db-cAMP, forskolin or dexamethasone inhibited the production of tumor necrosis factor-alpha and interleukin-1 beta by macrophages stimulated by zymosan. In conclusion, this study suggests that cAMP has a dual effect in the writhing model: an antinociceptive effect due to its modulatory action on resident peritoneal cells, thus, reducing the synthesis of mediators involved in the nociceptive response, and a nociceptive effect by directly sensitizing the nociceptive neuron.