Properties of 7ND-CCL2 are modulated upon fusion to Fc.

7ND, a truncated version of the chemokine MCP-1/CCL2 lacking amino acids 2-8, is a potent antagonist of CCR2. In contrast to CCL2, 7ND is an obligate monomer. Similar to other chemokines, the in vivo half-life of 7ND is very short and its use as an antagonist in disease models is thus limited. We therefore constructed a 7ND-Fc fusion protein to extend the half-life of 7ND and overcome its limitations as a potential therapeutic antagonist. When we tested the properties of the fusion molecule in vitro, we found to our surprise that 7ND-Fc, in contrast to 7ND, produced a distinct, albeit small, chemotactic response in THP-1 cells, and a robust chemotactic response in L1.2 cells stably transfected with CCR2. To test whether this unexpected observation might be due to the bivalency of 7ND-Fc stemming from the dimeric nature of Fc fusions, we produced a heterodimeric Fc fusion which displays only one 7ND moiety, using a technology called strand exchange of engineered CH3 domains (SEED). The monovalent construct had properties equivalent to the parent 7ND. Furthermore, partial agonist activity appears to depend on receptor density as well as the signaling pathway examined. However, we were able to show that 7ND-Fc, but not 7ND alone, has antagonistic activity in experimental autoimmune encephalomyelitis, a murine model of multiple sclerosis.

Experimental infection with Schistosoma mansoni in CCR5-deficient mice is associated with increased disease severity, as CCR5 plays a role in controlling granulomatous inflammation.

The plasma level of the chemokine CCL3 is elevated in patients with chronic severe schistosomiasis mansoni. We have previously shown that CCL3(-/-) mice with experimental infection showed diminished pathology and worm burden compared to those of wild-type (WT) mice. To elucidate further the role of CC chemokines during schistosomiasis mansoni infection, we evaluated the course of infection in C57BL/6J mice deficient in CCR5, one of the receptors for CCL3. The CCR5 deficiency proved to be remarkably deleterious to the host, since mortality rates reached 70% at 14 weeks postinfection in CCR5(-/-) mice and 19% in WT mice. The increased lethality was not associated with an increased parasite burden, since similar numbers of eggs and adult worms were found in mice from both groups. Liver granulomas of chronically infected CCR5(-/-) mice were larger and showed greater numbers of cells and collagen deposition than liver granulomas from WT mice. This was associated with higher levels of production of intereleukin-5 (IL-5), IL-13, CCL3, and CCL5 in infected CCR5(-/-) mice than in infected WT mice. Moreover, at 8 weeks after infection, just before changes in pathology and mortality, the numbers of FoxP3-positive cells were lower in liver granulomas of CCR5(-/-) mice than in WT mice. In conclusion, the CCR5 deletion is deleterious to mice infected with Schistosoma mansoni, and this is associated with enhanced fibrosis and granulomatous inflammation.

Phosphoinositide 3-kinase γ plays a critical role in bleomycin-induced pulmonary inflammation and fibrosis in mice.

PI3Kγ is central in signaling diverse arrays of cellular functions and inflammation. Pulmonary fibrosis is associated with pulmonary inflammation, angiogenesis, and deposition of collagen and is modeled by instillation of bleomycin. The role of PI3Kγ in mediating bleomycin-induced pulmonary inflammation and fibrosis in mice and potential mechanisms involved was investigated here. WT or PI3Kγ KO mice were instilled with bleomycin and leukocyte subtype influx, cytokine and chemokine levels, and angiogenesis and tissue fibrosis evaluated. The activation of lung-derived leukocytes and fibroblasts was evaluated in vitro. The relevance of PI3Kγ for endothelial cell function was evaluated in HUVECs. PI3Kγ KO mice had greater survival and weight recovery and less fibrosis than WT mice after bleomycin instillation. This was associated with decreased production of TGF-ß(1) and CCL2 and increased production of IFN-γ and IL-10. There was reduced expression of collagen, fibronectin, α-SMA, and von Willebrand factor and decreased numbers and activation of leukocytes and phosphorylation of AKT and IκB-α. PI3Kγ KO mice had a reduced number and area of blood vessels in the lungs. In vitro, treatment of human endothelial cells with the PI3Kγ inhibitor AS605240 decreased proliferation, migration, and formation of capillary-like structures. AS605240 also decreased production of collagen by murine lung-derived fibroblasts. PI3Kγ deficiency confers protection against bleomycin-induced pulmonary injury, angiogenesis, and fibrosis through the modulation of leukocyte, fibroblast, and endothelial cell functions. Inhibitors of PI3Kγ may be beneficial for the treatment of pulmonary fibrosis.

Role of CCL3/MIP-1alpha and CCL5/RANTES during acute Trypanosoma cruzi infection in rats.

Chagas' disease is caused by Trypanosoma cruzi infection and is characterized by chronic fibrogenic inflammation and heart dysfunction. Chemokines are produced during infection and drive tissue inflammation. In rats, acute infection is characterized by intense myocarditis and regression of inflammation after control of parasitism. We investigated the role of CCL3 and CCL5 during infection by using DNA vaccination encoding for each chemokine separately or simultaneously. MetRANTES treatment was used to evaluate the role of CCR1 and CCR5, the receptors for CCL3 and CCL5. Vaccination with CCL3 or CCL5 increased heart parasitism and decreased local IFN-gamma production, but did not influence intensity of inflammation. Simultaneous treatment with both plasmids or treatment with MetRANTES enhanced cardiac inflammation, fibrosis and parasitism. In conclusion, chemokines CCL3 and CCL5 are relevant, but not essential, for control of T. cruzi infection in rats. On the other hand, combined blockade of these chemokines or their receptors enhanced tissue inflammation and fibrosis, clearly contrasting with available data in murine models of T. cruzi infection. These data reinforce the important role of chemokines during T. cruzi infection but suggest that caution must be taken when expanding the therapeutic modulation of the chemokine system in mice to the human infection.

The flavonoid dioclein reduces the production of pro-inflammatory mediators in vitro by inhibiting PDE4 activity and scavenging reactive oxygen species.

Reactive oxygen species, cytokines and chemokines produced at inflammatory sites are pivotal events in the progression of many diseases. Flavonoids are well-known for their antioxidant and anti-inflammatory activities. Here, we investigated the effects of the flavonoid dioclein on the production of mediators of inflammation in vitro and possible underlying mechanisms. Murine macrophages were pretreated with dioclein, rolipram, a PDE4 (cyclic nucleotide phosphosdiesterase type 4) inhibitor, or butylated hydroxytoluene (BHT), an antioxidant, and then activated with LPS or LPS/IFN-gamma. The concentration of TNF-alpha, IL-6, CXCL1/KC, CCL2/JE, and nitric oxide (NO) was determined on culture supernatants. To evaluate potential mechanisms of action, dioclein was tested for inhibition of PDE4 activity and for antioxidant properties by chemiluminescence assays. Dioclein was efficient in reducing the production of cytokines, chemokines and NO in a concentration-dependent manner (from 5 to 50muM). Dioclein was more effective than BHT and rolipram, while having similar inhibitory effects to the combination of BHT plus rolipram. Dioclein inhibited PDE4 activity with an approximate IC(50) of 16.8+/-1.4muM and strongly reduced the concentration of reactive oxygen species in cell and cell-free systems, being more effective than the standard antioxidant BHT. The flavonoid dioclein possesses significant antioxidant and PDE4 inhibitory activity, showing that the substance may have substantial advantages over mechanisms of action already described for many flavonoids. Such effects account for the anti-inflammatory effects of dioclein, mainly by reducing the concentration of mediators of inflammation, such as cytokines, chemokines and reactive oxygen species by macrophages.

Role of the chemokines CCL3/MIP-1 alpha and CCL5/RANTES in sponge-induced inflammatory angiogenesis in mice.

OBJECTIVE: We examined the potential contribution of CCL3 and CCL5 to inflammatory angiogenesis in mice. METHODS: Polyester-polyurethane sponges were implanted in mice and blood vessel counting and hemoglobin, myeloperoxidase and N-acetylglucosaminidase measurements used as indexes for vascularization, neutrophil and macrophage accumulation, respectively. RESULTS: CCL3 and CCL5 were expressed throughout the observation period. Exogenous CCL3 enhanced angiogenesis in WT, but angiogenesis proceeded normally in CCL3(-/-) mice, suggesting that endogenous CCL3 is not critical for sponge-induced angiogenesis in mice. CCL5 expression was detected at day 1, but levels significantly increased thereafter. Exogenous CCL5 reduced angiogenesis in WT mice possible via CCR5 as CCL5 was without an effect in CCR5(-/-) mice. Treatment of WT with the CCR1/CCR5 antagonist, Met-RANTES, prevented neutrophil and macrophage accumulation, but enhanced sponge vascularization. CONCLUSION: Thus, endogenous CCL3 appears not to play a role in driving sponge-induced inflammatory angiogenesis in mice. The effects of CCL5 were anti-angiogenic and appeared to be mediated via activation of CCR5.

Role of the chemokine receptor CXCR2 in bleomycin-induced pulmonary inflammation and fibrosis.

Pulmonary fibrosis is characterized by chronic inflammation and excessive collagen deposition. Neutrophils are thought to be involved in the pathogenesis of lung fibrosis. We hypothesized that CXCR2-mediated neutrophil recruitment is essential for the cascade of events leading to bleomycin-induced pulmonary fibrosis. CXCL1/KC was detected as early as 6 hours after bleomycin instillation and returned to basal levels after Day 8. Neutrophils were detected in bronchoalveolar lavage and interstitium from 12 hours and peaked at Day 8 after instillation. Treatment with the CXCR2 receptor antagonist, DF2162, reduced airway neutrophil transmigration but led to an increase of neutrophils in lung parenchyma. There was a significant reduction in IL-13, IL-10, CCL5/RANTES, and active transforming growth factor (TGF)-beta(1) levels, but not on IFN-gamma and total TGF-beta(1,) and enhanced granulocyte macrophage-colony-stimulating factor production in DF2162-treated animals. Notably, treatment with the CXCR2 antagonist led to an improvement of the lung pathology and reduced collagen deposition. Using a therapeutic schedule, DF2162 administered from Days 8 to 16 after bleomycin reduced pulmonary fibrosis and levels of active TGF-beta(1) and IL-13. DF2162 treatment reduced bleomycin-induced expression of von Willebrand Factor, a marker of angiogenesis, in the lung. In vitro, DF2162 reduced the angiogenic activity of IL-8 on human umbilical vein endothelial cells. In conclusion, we show that CXCR2 plays an important role in mediating fibrosis after bleomycin instillation. The compound blocks angiogenesis and the production of pro-angiogenic cytokines, and decreases IL-8-induced endothelial cell activation. An effect on neutrophils does not appear to account for the major effects of the blockade of CXCR2 in the system.

The role of chemokines in controlling granulomatous inflammation in Schistosoma mansoni infection.

Chemokines are a superfamily of low-molecular-weight cytokines that were initially described for their chemoattractant activity. It is now clear chemokines have several other activities that modulate immune processes. Chemokines appear to play a role in the pathogenesis of several inflammatory diseases. The role of chemokines and their receptors in mediating granulomatous inflammation induced by Schistosoma mansoni egg antigens presented in particulate manner have been studied in detail. Much less is known of the role of chemokines in mediating inflammation during the course of S. mansoni infection. Our studies in mice suggest a relevant role for the chemokine CCL3 and the receptor CCR5 in the pathogenesis of experimental S. mansoni infection. Absence of CCL3 is associated with decrease in granuloma size, fibrosis and parasite load. In humans, levels of CCL3 in plasma associate with disease severity and may be useful for diagnostic purposes. In contrast, absence of CCR5 is associated with enhanced lethality, granuloma size and fibrosis. It is suggested that the balance of chemokine production and chemokine receptor activation are important determinants of the fate of infection in experimental animals and humans.

The role of macrophage migration inhibitory factor in the cascade of events leading to reperfusion-induced inflammatory injury and lethality.

Ischemia and reperfusion (I/R) injury is associated with a systemic inflammatory response, characterized by intense tumor necrosis factor (TNF)-alpha production and TNF-alpha-dependent tissue injury. Macrophage migration inhibitory factor (MIF) is a potent proinflammatory cytokine that may induce TNF-alpha release and play an important role in innate immune and inflammatory responses. The aim of this work was to assess whether MIF was involved the inflammatory cascade and injury that follows intestinal I/R. To this end, wild-type (WT) and MIF-deficient (MIF(-/-)) mice underwent 60 minutes of ischemia followed by 60 minutes of reperfusion, after which they were culled for the assessment of inflammatory parameters. I/R was accompanied by an increase in circulating levels of MIF and an increase of vascular permeability, hemorrhage, and production of TNF-alpha in the intestine and lungs. The latter parameters were markedly suppressed in reperfused MIF(-/-) mice, and this was associated with decreased lethality (80% in WT versus 20% in MIF(-/-) mice). Interestingly, the reperfusion-associated neutrophil accumulation in the intestine and lungs was similar in WT and MIF(-/-) mice. Leukocytes isolated from lungs of MIF(-/-) mice were less activated, as assessed by their response to zymosan in a luminol-enhanced chemiluminescence assay. In conclusion, our results suggest that MIF plays an important role in the cascade of events leading to TNF-alpha production and reperfusion-induced tissue injury and lethality in mice.

ST2, an IL-1R family member, attenuates inflammation and lethality after intestinal ischemia and reperfusion.

Ischemia reperfusion injury is characterized by local and systemic inflammation leading to considerable mortality. Previously, we have reported that soluble T1/ST2 (sST2), a member of the IL-1 receptor gene family, inhibits LPS-induced macrophage proinflammatory cytokine production. Here, we report the therapeutic effect of sST2-Fc in a murine model of intestinal ischemia reperfusion-induced injury. Administration of sST2-Fc fusion protein i.v., 10 min before reperfusion, reduced the production of TNF-alpha dose-dependently in the intestine and in the lungs. The sST2-Fc treatment with the highest dose (100 mug) resulted in inhibited vascular permeability, neutrophilia, and hemorrhage in the intestine and the lungs compared with controls treated with normal IgG. This was associated with down-regulated tissue levels of proinflammatory cytokines, markedly reduced serum TNF-alpha levels, and increased survival of mice from the sST2-Fc-treated group after ischemia and reperfusion injury. The beneficial effect of sST2-Fc treatment was associated with elevated IL-10 production in intestine and lung. sST2-Fc was not able to prevent the inflammatory response associated with intestinal ischemia and reperfusion in IL-10-deficient mice, suggesting that sST2 exerts its anti-inflammatory effect in a IL-10-dependent manner. These results also demonstrate that sST2-Fc may provide a novel, complementary approach in treating ischemic reperfusion injury.

The role of chemokines in Schistosoma mansoni infection: insights from human disease and murine models

Chemokines are a superfamily of low-molecular-weight cytokines that were initially described for their chemoattractant activity. It is now clear chemokines have several other activities that modulate immune processes. More than 50 chemokines ligands and at least 19 receptors have been described to date. Depending on the number of N-terminal cysteine residues, chemokines are grouped in the subfamilies CXC, CC, C or CX3C. A growing body of evidence suggests a role for chemokines in the pathogenesis of several inflammatory diseases. Our studies involving mice and humans infected with Schistosoma mansoni suggest an important role of the chemokine CCL3 and its receptors (CCR1 and CCR5) in the pathogenesis of severe schistosomiasis. We suggest that the differential activation of CCR1 or CCR5 during the course of schistosomiasis may dictate the outcome of the disease.

A DNA vaccine encoding CCL4/MIP-1beta enhances myocarditis in experimental Trypanosoma cruzi infection in rats.

Chagas' disease, caused by Trypanosoma cruzi, is a major cause of cardiovascular disease in Latin America. Exacerbated inflammation disproportional to parasite load characterizes chronic myocardial lesions in chagasic patients. Chemokines and their receptors are expected to account for the renewed inflammatory processes after the inoculation of the parasite, but their potential unique functions are far from being clear. Herein, we evaluated the effect of a DNA vaccine encoding CCL4/MIP-1beta, a CC-chemokine, in T. cruzi-elicited myocarditis in rats. Holtzman rats were given intramuscularly cardiotoxin and the CCL4/MIP-1beta DNA-containing plasmid (100microg) was delivered in this muscular site four times. Fourteen days after last immunization, animals were inoculated with a myotropical CL-Brener T. cruzi clone. Peak of parasitism was observed at day 15 after infection, preceding the peak of myocardial inflammation at day 20. Myocarditis was still intense at day 30, but the inflammatory infiltrates showed a more focal distribution. The expression of CCL2/MCP-1 and CCL4/MIP-1beta correlated closely with the kinetics of myocardial inflammation. The CCL4/MIP-1beta DNA vaccine induced an increase of the levels of the anti-CCL4/MIP-1beta observed in T. cruzi-infected animals. This was associated with an exacerbation of myocardial inflammation and fibrosis, although alterations in parasitemia and myocardial parasitism were not observed. Our data suggest that CCL4/MIP-1beta plays a role in preventing excessive inflammation and pathology rather than in controlling parasite replication.

Expression of IL-4 receptor on non-bone marrow-derived cells is necessary for the timely elimination of Strongyloides venezuelensis in mice, but not for intestinal IL-4 production.

In rodents and in humans, Strongyloides infection induces an immune response which is predominantly Th2 in nature. In an attempt to understand the role of the IL-4R/STAT6 signaling pathway, the pathway activated by the Th2 cytokines IL-4 and IL-13, in the induction of protection during Strongyloides venezuelensis infection, we have carried out experiments in mice lacking the IL-4Ralpha chain. Experiments were also carried out in STAT6 (STAT6(-/-)) and IL-12-deficient (IL-12(-/-)) mice for comparison. There was enhancement of IL-13 and abolition of IFN-gamma production in the small intestine of 7 day-infected IL-12(-/-) animals but worm elimination proceeded with very similar kinetics to those of wild-type mice. In IL-4Ralpha- or STAT6-deficient mice, there was a delay in parasite elimination and a large number of S. venezuelensis adult worms was still present in the small intestine 14 days after infection. Moreover, IgE production was completely abolished in IL-4Ralpha- or STAT6-deficient mice but tissue eosinophilia was normally induced by the parasite infection in deficient mice. Bone marrow transfer experiments showed that worm elimination occurred when a functional IL-4 receptor was present only in non-bone marrow-derived cells but not when IL-4R was only expressed in bone marrow cells. The induction of IL-4, but not IL-13, occurred independently of IL-4R. We believe these results are the first direct evidence that the mechanism responsible for the timely elimination of S. venezuelensis is dependent on the activation of IL-4R and STAT6. Moreover, a functional protective response is dependent on the expression of IL-4Ralpha on non-bone marrow-derived cells.

The role of chemokines in Schistosoma mansoni infection: insights from human disease and murine models.

Chemokines are a superfamily of low-molecular-weight cytokines that were initially described for their chemoattractant activity. It is now clear chemokines have several other activities that modulate immune processes. More than 50 chemokines ligands and at least 19 receptors have been described to date. Depending on the number of N-terminal cysteine residues, chemokines are grouped in the subfamilies CXC, CC, C or CX3C. A growing body of evidence suggests a role for chemokines in the pathogenesis of several inflammatory diseases. Our studies involving mice and humans infected with Schistosoma mansoni suggest an important role of the chemokine CCL3 and its receptors (CCR1 and CCR5) in the pathogenesis of severe schistosomiasis. We suggest that the differential activation of CCR1 or CCR5 during the course of schistosomiasis may dictate the outcome of the disease.

Norepinephrine, dopamine and dexamethasone modulate discrete leukocyte subpopulations and cytokine profiles from human PBMC.

The interplay between the immune and neuroendocrine systems is intense, with the cross-talk between these two systems increasing during stress circumstances. Stress events culminate with hormonal pathway activation elevating the plasma levels of glucocorticoids and catecholamines. The majority of the works evaluating the effects of stress hormones on immune cells have utilized in vivo animal models or clinical studies. This work evaluates the effects of norepinephrine, dopamine, dexamethasone, and the combination of norepinephrine and dexamethasone on cellular activation and expression of immunoregulatory cytokines and chemokines by human PBMC in vitro. Norepinephrine and dopamine increased lymphocyte activation accompanied by augmented Th1 and Th2 type cytokine production. Dexamethasone reduced cell activation and decreased frequencies of cytokine producing cells and chemokine production. The action of norepinephrine together with dexamethasone resulted in immunosupression. The observed effects of hormones and neurotransmitters on leukocyte subsets likely underlie their immunomodulatory action in vivo.

Potential role of the chemokine macrophage inflammatory protein 1alpha in human and experimental schistosomiasis.

In human schistosomiasis, the concentrations of the chemokine macrophage inflammatory protein 1alpha (MIP-1alpha/CCL3) is greater in the plasma of patients with clinical hepatosplenic disease. The objective of the present study was to confirm the ability of CCL3 to detect severe disease in patients classified by ultrasonography (US) and to evaluate the potential role of CCL3 in Schistosoma mansoni-infected mice. CCL3 was measured by enzyme-linked immunosorbent assay in the plasma of S. mansoni-infected patients. CCL3-deficient mice were infected with 25 cercariae, and various inflammatory and infectious indices were evaluated. The concentration of CCL3 was higher in the plasma of S. mansoni-infected than noninfected patients. Moreover, CCL3 was greater in those with US-defined hepatosplenic than with the intestinal form of the disease. In CCL3-deficient mice, the size of the granuloma and the liver eosinophil peroxidase activity and collagen content were diminished compared to wild-type mice. In CCL3-deficient mice, the worm burden after 14 weeks of infection, but not after 9 weeks, was consistently smaller. The in vitro response of mesenteric lymph node cells to antigen stimulation was characterized by lower levels of interleukin-4 (IL-4) and IL-10. CCL3 is a marker of disease severity in infected humans, and experimental studies in mice suggest that CCL3 may be a causative factor in the development of severe schistosomiasis.

Pharmacological investigation of the nociceptive response and edema induced by venom of the scorpion Tityus serrulatus.

In this study we characterized the nociceptive response and edema induced by the venom of the scorpion Tityus serrulatus in rats and mice and carried out a preliminary pharmacological investigation of the mechanisms involved in these responses. Intraplantar injection of the venom (1 or 10mug) induced edema and a marked ipsilateral nociceptive response, characterized by thermal and mechanical allodynia and paw licking behaviour. The nociceptive response was inhibited by previous intraperitoneal administration of indomethacin (4mg/kg), dipyrone (200mg/kg), cyproheptadine (10mg/kg) or morphine (5 or 10mg/kg), but not by dexamethasone (1 or 4mg/kg) or promethazine (1 or 5mg/kg). The edema was inhibited by previous treatment with promethazine (5 or 10mg/kg) or cyproheptadine (5 or 10mg/kg), but not by indomethacin (2 or 4mg/kg), dexamethasone (1 or 4mg/kg) or cromolyn (40 or 80mg/kg). Some bioactive amines, including histamine and 5-hydroxytryptamine, were found in the venom in low concentrations. In conclusion, the nociceptive response and edema induced by the venom of T. serrulatus may result from the action of multiple mediators including eicosanoids, histamine and 5-hydroxytryptamine. These results may lead to a better understanding of the host response to potent animal toxins and also give insights into a more rational pharmacological approach to alleviate the intense pain associated with the scorpion envenomation.

Increased serum concentrations of monokine induced by interferon-gamma/CXCL9 and interferon-gamma-inducible protein 10/CXCL-10 in Sydenham's chorea patients.

Sydenham's chorea (SC) is thought to result from the action of streptococcus-induced antibodies that cross react with basal ganglia antigens. Much less is known, however, about the involvement of cellular mechanisms in its pathogenesis. Since chemokines seem to play a role in several CNS inflammatory disorders, we sought to investigate the chemokine profile of patients with SC. Increased serum levels of CXCL9, formerly monokine induced by interferon-gamma (Mig), and CXCL10, formerly interferon-gamma-inducible protein of 10 kDa (IP-10) were demonstrated in acute SC patients, suggesting that a particular group of chemokines may be involved in SC pathogenesis.

Platelet-activating factor receptor deficiency delays elimination of adult worms but reduces fecundity in Strongyloides venezuelensis-infected mice.

We describe the parasitological kinetics and histopathological and immunological alterations in platelet-activating factor receptor-deficient (PAFR(-/-)) and wild-type mice after a single Strongyloides venezuelensis infection (subcutaneous inoculation of 500 L3 larvae). There was no difference in the numbers of worms that reached and became established in the small intestines of PAFR(-/-) and wild-type mice. However, at 12 days after infection, significantly more worms were recovered from PAFR(-/-) mice. Although PAFR(-/-) infected mice showed a delay in elimination of adult worms, worms established in the small intestine of these mice produced a significantly lower number of eggs due to a reduction in worm fecundity. There were also significant reductions in the number of circulating and tissue eosinophils and tumor necrosis factor levels in the small intestines of PAFR(-/-) mice infected for 7 days compared to the number and level in wild-type mice. Histological analysis confirmed the reduced inflammatory process and revealed that the PAFR(-/-) mice had a smaller number of goblet cells. The concentrations of the type 2 cytokines interleukin-4 (IL-4), IL-5, and IL-10 were lower in small intestine homogenates and in supernatants of antigen-stimulated lymphocytes from spleens or mesenteric lymph nodes of PAFR(-/-) mice than in the corresponding preparations from wild-type mice. Thus, in S. venezuelensis-infected PAFR(-/-) mice, decreased intestinal inflammation is associated with enhanced worm survival but decreased fecundity. We suggest that although a Th2-predominant inflammatory response decreases worm survival, the worm may use factors produced during this response to facilitate egg output and reproduction. PAFR-mediated responses appear to modulate these host-derived signals that are important for worm fecundity.

In vivo evidence for a role of protein kinase C in peripheral nociceptive processing.

1. The present study was designed to characterize the nociceptive response induced by protein kinase C (PKC) peripheral activation and to investigate if this biochemical event is important for the nociceptive response induced by formaldehyde, and bradykinin (BK). 2. Intraplantar injection of phorbol-12,13-didecanoate (PDD; 0.01, 0.1 or 1 microg), a PKC activator, but not of 4 alpha-PDD (inactive analogue), dose-dependently induced thermal hyperalgesia in rats. This response was not observed at the contralateral hindpaw. Intraplantar injection of PDD (0.01, 0.1 or 1 microg) also induced mechanical allodynia. In mice, injection of PDD (0.1 or 1 microg) into the dorsum of the hindpaw induced a spontaneous licking behaviour. 3. Intraplantar co-injection of chelerythrine (10 or 50 microg), a PKC inhibitor, attenuated the thermal hyperalgesia induced by PDD (0.1 microg) in rats. 4. The second phase of the nociceptive response induced by the injection of formaldehyde (0.92%, 20 microl) into the dorsum of mice hindpaws was inhibited by ipsi-, but not contralateral, pre-treatment with chelerythrine (1 microg). 5. Intraplantar injection of BK (10 microg) induced mechanical allodynia in rats. Ipsi- but not contralateral injection of bisindolylmaleimide I (10 microg), a PKC inhibitor, inhibited BK-induced mechanical allodynia. 6. In conclusion, this study demonstrates that PKC activation at peripheral tissues leads to the development of spontaneous nociceptive response, thermal hyperalgesia and mechanical allodynia. Most importantly, it also gives in vivo evidence that peripheral PKC activation is essential for the full establishment of the nociceptive response induced by two different inflammatory stimuli.