The modulatory role played by TNF-alpha and IL-1 beta in the inflammatory responses induced by carrageenan in the mouse model of pleurisy

We describe here the modulation caused by intrapleural (i.pl.) injection of the cytokines TNF-alpha and IL-1beta and their specific antibodies in the early (4 h) and late (48 h) inflammatory responses caused by injection of carrageenan (Cg) into the mouse pleural cavity. The antibodies against TNF-alpha and IL-1beta, when injected 30 min prior to Cg, reduced, in a graded and significant manner, both exudation and cell migration in the early (4 h) phase, while they potentiated or had no effect in the late (48 h) phase of Cg response. The natural IL-1 receptor antagonist IL-1RA, given 30 min prior to Cg, reduced the exudation by about 50% and abolished the total and differential cell migration in the early (4 h) and late (48 h) phases of the Cg responses. The i.pl. injection of TNF-alpha or IL-1beta, 5 min prior to Cg, caused graded increase in the exudation of the early (4 h) and late (48 h) phases of the Cg-induced inflammatory responses. In contrast, these treatments markedly reduced the total and differential cell migration at 4 h, while having little or no effect on the late (48 h) phase of the Cg pleurisy. These findings extend previous results and demonstrate that the pro-inflammatory cytokines TNF-alpha and IL-1beta have a critical role in controlling both cell migration and exudation caused by injection of Cg in the mouse pleural cavity. Together, these findings may be relevant to the understanding of the mechanisms involved in airway inflammatory responses.     

Effects of methotrexate upon inflammatory parameters induced by carrageenan in the mouse model of pleurisy

BACKGROUND: The model of pleurisy induced by carrageenan exhibits a biphasic response (4 and 48 h) and permits the quantification of exudate, cell migration and certain enzymes such as myeloperoxidase (MPO) and adenosine-deaminase (ADA) that are markers of activated leukocytes. AIMS: The present study evaluates whether there exists, in the pleurisy model, a significant inhibition of ADA and MPO enzymes, leukocyte kinetics and other markers of inflammation [nitric oxide (NO) levels, exudation] caused by methotrexate treatment by the intraperitoneal (i.p.) route. METHODS: The pleurisy was induced by carrageenan (1%) in mice, and the parameters were analyzed 4 and 48 h after. RESULTS: After the induction of inflammation (4 h), methotrexate (20 mg/kg, i.p., 24 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), NO levels and MPO activity (p < 0.01), but not ADA activity and fluid leakage (p > 0.05). Regarding the second phase of pleurisy (48 h), methotrexate (40 mg/kg, i.p., 0.5 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), fluid leakage, NO levels (p < 0.01), and ADA and MPO activity (p < 0.05). CONCLUSIONS: These findings support the evidence that the acute administration of methotrexate has an important systemic anti-inflammatory activity in the studied inflammatory model. This effect was due to a significant inhibition on both neutrophil and mononuclear cells, being less marked in relation to exudation 48 h after. In relation to the enzymes studied and to NO levels, the findings support the evidence that methotrexate inhibits both enzymes (MPO and ADA) from leukocytes at the site of injury, thus reflecting the activation of both neutrophils and lymphocytes, respectively. Furthermore, the inhibiting effect on NO in both phases of pleurisy induced by carrageenan (4 and 48 h) indicates that methotrexate acts on constitutive and/or inducible NO synthases by means of different cells of the pleural cavity.     

Role of IL-6 in the pleurisy and lung injury caused by carrageenan.

In the present study we used IL-6 knockout mice (IL-6KO) to evaluate the role of IL-6 in the inflammatory response caused by injection of carrageenan into the pleural space. Compared with carrageenan-treated IL-6 wild-type (IL-6WT) mice, carrageenan-treated IL-6KO mice exhibited a reduced degree of pleural exudation and polymorphonuclear cell migration. Lung myeloperoxidase activity and lipid peroxidation were significantly reduced in IL-6KO mice compared with those in IL-6WT mice treated with carrageenan. Immunohistochemical analysis for nitrotyrosine and poly(A)DP-ribose polymerase revealed a positive staining in lungs from carrageenan-treated IL-6WT mice. No positive staining for nitrotyrosine or PARS was found in the lungs of the carrageenan-treated IL-6KO mice. Staining of lung tissue sections obtained from carrageenan-treated IL-6WT mice with an anti-cyclo-oxygenase-2 Ab showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in the macrophages of the inflamed lungs from carrageenan-treated IL-6WT mice. The intensity and degree of the staining for cyclo-oxygenase-2 and inducible nitric oxide synthase were markedly reduced in tissue sections obtained from carrageenan-treated IL-6KO mice. Most notably, the degree of lung injury caused by carrageenan was also reduced in IL-6KO mice. Treatment of IL-6WT mice with anti-IL-6 (5 microg/day/mouse at 24 and 1 h before carrageenan treatment) also significantly attenuated all the above indicators of lung inflammation. Taken together, our results clearly demonstrate that IL-6KO mice are more resistant to the acute inflammation of the lung caused by carrageenan injection into the pleural space than the corresponding WT mice.     

Myeloperoxidase and adenosine-deaminase levels in the pleural fluid leakage induced by carrageenan in the mouse model of pleurisy

BACKGROUND: Although myeloperoxidase (MPO) and adenosine-deaminase (ADA) levels are markers of activated leukocytes, both enzymes have not been currently addressed in inflammation models. AIMS: This study evaluates whether the concentrations of these enzymes are significantly correlated with the content of leukocytes in a pleurisy model. METHODS: The pleurisy was induced by carrageenan (1%) in mice, and the parameters analyzed 4 and 48 h after. RESULTS: After the induction of inflammation (4h), MPO and ADA levels peaked in parallel to neutrophils (p<0.01). Regarding the second phase of pleurisy (48 h), the highest concentrations of ADA were detected in parallel to the highest levels of mononuclears (p<0.01). At this time, MPO levels and neutrophils remained elevated, although at lower levels than those found at 4 h. A significant positive correlation was found among neutrophiLs and MPO, and mononuclears and ADA (p<0.01). CONCLUSIONS: These findings support the evidence that both enzymes are markers of the inflammatory process, and provide new tools for a better understanding of the immunoregulatory pathways that occur in inflammation.     

Implication of glucocorticoid in anti-inflammatory effects of Ro5-4864 in mouse pleurisy induced by carrageenan

Mouse pleurisy induced by carrageenan is used to determine the mechanism of anti-inflammatory action of 7-chloro-5-(4-chlorophenyl)-1,3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2 (Ro5-4864). Pre-treatment with Ro5-4864 inhibits different inflammatory parameters, such as neutrophil influx, MPO activity and NO levels in the early phase (4 h), as well as mononuclear cells and ADA activity in the late phase (48 h) of pleurisy. dl-Aminoglutethimide, inhibitor of steroidal synthesis, reverted the effect of Ro5-4864 on these different inflammatory parameters. Our results suggest that anti-inflammatory action of Ro5-4864 may be partly due to its capacity to inhibit leukocyte migration, as well as leukocyte activation and formation of NO by a mechanism dependent on glucocorticoids.     

Effects of anti-inflammatory drugs upon nitrate and myeloperoxidase levels in the mouse pleurisy induced by carrageenan.

The effects of several drugs (terfenadine, bradykinin B2 receptor antagonists: HOE 140, NPC 17731, diacerein, indomethacin, meloxicam, nabumetone, and dexamethasone) upon myeloperoxidase and nitrate levels were analyzed in an inflammation model characterized by biphasic peaks (4 and 48 h) of cell migration and of fluid leakage. Myeloperoxidase levels were significantly higher only in the first phase (4 h; median and range; 537.5; 323.6-683.7 mU/ml; P < 0.01), whereas increased mean nitrate levels were detected in both phases (4 h: 19.0; 6.2-32 microM and 48 h: 13.7; 8.9-17.8 microM; P < 0.01). Enhancement of both cell migration and myeloperoxidase levels, 4 h after pleurisy induction, was effectively inhibited by all studied drugs. All of them, except diacerein also inhibited exudation. At this time, nabumetone and diacerein also significantly reduced nitrate levels (P < 0.01). Regarding the second phase (48 h), although dexamethasone, diacerein, and terfenadine decreased either cell migration or exudation, no drugs caused any change in the levels of nitrate. These results indicate that the degree of inhibition of the tested drugs upon the parameters studied do not match, suggesting that differences in these effects may certainly interfere with their efficacy.     

Effects of IL-10 and age on IL-6, IL-1beta, and TNF-alpha responses in mouse skeletal and cardiac muscle to an acute inflammatory insult.

Exaggerated proinflammatory cytokine responses can be observed with aging, and reduced levels of the anti-inflammatory cytokine IL-10 may contribute to these responses. IL-10 can reduce IL-6, IL-1beta, and TNF-alpha expression in nonmuscle tissues; however, no studies have examined the combined effects of IL-10 and age on cytokine responses in skeletal and cardiac muscle. These experiments tested the hypothesis that the absence of IL-10, in vivo, is associated with greater IL-6, TNF-alpha, and IL-1beta responses to an inflammatory challenge in skeletal and cardiac muscle and that aging exaggerates these responses. We compared IL-6, IL-1beta, and TNF-alpha mRNA and protein levels in skeletal and cardiac muscle of young (4 mo) and mature (10-11 mo) wild-type (IL-10(+/+)) and IL-10 deficient (IL-10(-/-)) mice following LPS. Skeletal and cardiac IL-6 mRNA and protein were elevated by LPS for IL-10(+/+) and IL-10(-/-) mice with greater responses in the IL-10(-/-) mice (P < 0.01). In skeletal muscle these effects were greater in mature than young mice (P < 0.01). IL-1beta mRNA and protein responses to LPS were greater in cardiac muscle of young but not mature IL-10(-/-) mice compared with IL-10(+/+) (P < 0.01). However, IL-1beta responses were greater in mature than young mice, but only in IL-10(+/+) groups (P < 0.05). The absence of IL-10 was associated with higher TNF-alpha protein levels in cardiac muscle (P < 0.05). The results provide the first in vivo evidence that the absence of IL-10 is associated with a greater IL-6 response to LPS in skeletal and cardiac muscles, and in skeletal muscle aging further exaggerates these responses.     

The monoacylglycerol lipase inhibitor JZL184 suppresses inflammatory pain in the mouse carrageenan model

AimThe present study tested whether the selective monoacylglycerol lipase (MAGL) inhibitor JZL184 would reduce allodynia and paw edema in the carrageenan test.Main methodsThe anti-edematous and anti-allodynic effects of JZL184 were compared to those of PF-3845, an inhibitor of fatty acid amide hydrolase (FAAH), and diclofenac, a non-selective cyclooxygenase inhibitor. Cannabinoid receptor involvement in the anti-edematous and anti-allodynic effects of JZL184 was evaluated by administration of the respective CB₁ and CB₂ receptor antagonists rimonabant and SR144528 as well as with CB₁(?/?) and CB₂(?/?) mice. JZL184 (1.6, 4, 16, or 40 mg/kg) was administered for six days to assess tolerance.Key findingsJZL184 administered before or after carrageenan significantly attenuated carrageenan-induced paw edema and mechanical allodynia. Complementary genetic and pharmacological approaches revealed that the anti-allodynic effects of JZL184 required both CB₁ and CB₂ receptors, but only CB₂ receptors mediated its anti-edematous actions. Importantly, both the anti-edematous and anti-allodynic effects underwent tolerance following repeated injections of high dose JZL184 (16 or 40 mg/kg), but repeated administration of low dose JZL184 (4 mg/kg) retained efficacy.SignificanceThese results suggest that the MAGL inhibitor JZL184 reduces inflammatory nociception through the activation of both CB₁ and CB₂ receptors, with no evidence of tolerance following repeated administration of low doses.     

Effect of novel selective non-peptide kinin B(1) receptor antagonists on mouse pleurisy induced by carrageenan

Two novel selective non-peptide kinin B(1) receptor antagonists, the benzodiazepine antagonist and SSR240612, were evaluated in carrageenan-induced mouse pleurisy. The peptide R-715 (0.5 mg/kg, i.p.) and the non-peptide benzodiazepine (3 mg/kg, i.p.) antagonists significantly decreased cellular migration (predominantly neutrophils), without altering plasma exudation. SSR240612 (1 mg/kg, i.p.) diminished total cells and neutrophils, besides exudation. Oral administration of SSR240612 (10 mg/kg) also reduced total cell and neutrophil counts. Only the benzodiazepine antagonist inhibited the lung myeloperoxidase activity. No tested antagonist significantly altered the lung and pleural TNFalpha and IL-1beta production. We provide interesting evidence on the anti-inflammatory in vivo effects of non-peptide B(1) receptor antagonists.     

Inhibition of IL-6 and IL-10 signaling and Stat activation by inflammatory and stress pathways

The development and resolution of an inflammatory process are regulated by a complex interplay among cytokines that have pro- and anti-inflammatory effects. Effective and sustained action of a proinflammatory cytokine depends on synergy with other inflammatory cytokines and antagonism of opposing cytokines that are often highly expressed at inflammatory sites. We analyzed the effects of the inflammatory and stress agents, IL-1, TNF-alpha, LPS, sorbitol, and H(2)O(2), on signaling by IL-6 and IL-10, pleiotropic cytokines that activate the Jak-Stat signaling pathway and have both pro- and anti-inflammatory actions. IL-1, TNF-alpha, and LPS blocked the activation of Stat DNA binding and tyrosine phosphorylation by IL-6 and IL-10, but not by IFN-gamma, in primary macrophages. Inhibition of Stat activation correlated with inhibition of expression of IL-6-inducible genes. The inhibition was rapid and independent of de novo gene induction and occurred when the expression of suppressor of cytokine synthesis-3 was blocked. Inhibition of IL-6 signaling was mediated by the p38 subfamily of stress-activated protein kinases. Jak1 was inhibited at the level of tyrosine phosphorylation, indicating that inhibition occurred at least in part upstream of Stats in the Jak-Stat pathway. Experiments using Stat3 mutated at serine 727 and using truncated IL-6Rs suggested that the target of inhibition is contained within the membrane-proximal region of the cytoplasmic domain of the gp130 subunit of the IL-6 receptor and is different from the SH2 domain-containing protein-tyrosine phosphatase/suppressor of cytokine synthesis-3 docking site. These results identify a new level at which IL-1 and TNF-alpha modulate signaling by pleiotropic cytokines such as IL-6 and IL-10 and provide a molecular basis for the previously described antagonism of certain IL-6 actions by IL-1.     

Murine IL-10 gene transfer inhibits established collagen-induced arthritis and reduces adenovirus-mediated inflammatory responses in mouse liver

The effects of homologous IL-10 administration during an established autoimmune disease are controversial, given its reported immunostimulatory and immunosuppressive properties. Studies of collagen-induced arthritis have shown efficacy with repeated administrations of IL-10; however, when the EBV IL-10 homologue was administered via adenovirus gene transfer technology the results were equivocal. Therefore, the present study was undertaken to elucidate the effects of prolonged homologous IL-10 administration via adenovirus-mediated gene delivery on the progression of established arthritis. Collagen type II (CII)-immunized mice received i.v. injections of 10(7) or 10(8) PFU of an E1-deleted adenoviral vector containing the murine IL-10 gene (AdIL-10), after arthritis onset. Mice were monitored for 3 wk for disease progression, and gene transduction was assessed by quantification of serum mIL-10. CII-specific cell-mediated and humoral immune responses were analyzed by lymph node cell proliferation, cytokine production, and anti-CII Ab responses. Furthermore, because adenoviral vectors have been reported to induce organ dysfunction due to cell-mediated immune responses to the viral Ags, we have also evaluated delayed-type hypersensitivity responses and reactive hepatitis to the systemically delivered adenovirus and whether the IL-10 produced could influence those responses. Sustained suppression of autoimmune arthritis and elevated serum levels of IL-10 were achieved in our study. AdIL-10 treatment reduced cell-mediated immune reactivity, but did not affect humoral responses. Furthermore, IL-10 was able to reduce, but not totally abrogate, adenovirus-induced hepatic inflammation. These findings provide further insights into the diverse interplay of immune processes involved in autoimmune inflammation and the mechanism of cytokine immunotherapy.     

The characterization of four monoclonal antibodies specific for mouse IL-5 and development of mouse and human IL-5 enzyme-linked immunosorbent

Four rat mAb directed against mouse IL-5 have been characterized by their ability to remove and neutralize mouse IL-5 activity in various bioassays. All four mAb absorbed IL-5 activity from solution. Although all were able to neutralize mouse IL-5 bioactivity, two were significantly more effective. These two were also able to neutralize the activity of mouse IL-5 delivered to B cells during a cognate-linked interaction with a Th cell clone. A two-site sandwich ELISA specific for mouse IL-5 was developed by using pairs of mAb. The mouse IL-5 ELISA is capable of detecting natural or mouse rIL-5 in supernatants, crude bacterial lysates, and high concentrations of mouse serum, and has a detection limit of less than 20 pg. Two of these antibodies cross-reacted with and neutralized human rIL-5, and one of these was used for development of an ELISA for human IL-5.     

TRAIL administration down-modulated the acute systemic inflammatory response induced in a mouse model by muramyldipeptide or lipopolysaccharide

The potent inducer of apoptosis TRAIL/Apo2 ligand is now under considerations in clinical trials for the treatment of different types of cancer. Since the natural history of cancer is often characterized by microbial infections, we have investigated the effect of recombinant human TRAIL in a mouse model of systemic acute inflammation of microbial origin represented by BALB/c mice treated with either bacterial muramyldipeptide (MDP) or lipopolysaccharide (LPS). When administered intraperitoneally (i.p.), these inflammatory bacterial compounds triggered a severe systemic inflammatory response within 2h, represented by body temperature elevation, increase of circulating serum amyloid-A (SAA) and of the number of leukocytes in the peritoneal cavity. Moreover, both MDP and LPS induced a significant elevation of the circulating levels of several inflammatory cytokines and chemokines. Noteworthy, pre-treatment with recombinant human TRAIL 48 and 72h before administration of either MDP or LPS, significantly counteracted all acute inflammatory responses, including the elevation of key pro-inflammatory cytokines/chemokines such as IL-1α, IL-6, G-CSF, MCP-1. These data demonstrate for the first time that TRAIL has a potent anti-inflammatory activity, which might be beneficial for the anti-tumoral activity of TRAIL.     

携带IL-10基因的双歧杆菌对溃疡性结肠炎小鼠肠道屏障功能的影响

目的 观察表达IL-10基因的双歧杆菌对溃疡性结肠炎（UC）小鼠肠道屏障功能的影响,进一步探讨转基因双歧杆菌治疗UC的相关机制。方法 25只小鼠分为空白对照组、结肠炎组（UC-blank组）、双歧杆菌治疗组（UC-bacteria组）、空质粒双歧杆菌治疗组（UC-pBBAD/X-bacteria组）和表达IL-10基因双歧杆菌治疗组（UC-BL-hIL-10-bacteria组）,每组5只。采用5% DSS诱导建立UC小鼠模型,利用前期研究已成功筛选出的可稳定表达hIL-10蛋白的BL-hIL-10菌株对小鼠进行治疗。采用HE染色评估小鼠结肠炎症情况;采用荧光定量PCR检测小鼠结肠组织Claudin1、2、4、5、7和8的表达水平;计算小鼠DAI。结果 （1）BL-hIL-10菌株可以降低UC小鼠DAI,减轻UC小鼠结肠组织炎症程度。（2）BL-hIL-10菌株能下调UC小鼠结肠组织Claudin2表达水平,同时能够上调Claudin1、4、5、7和8的表达水平。（3）UC-BL-hIL-10-bacteria组UC小鼠的治疗效果明显优于UC-bacteria组和UC-pBBAD/X-bacteria组。结论 BL-hIL-10菌株能改善UC小鼠结肠黏膜的通透性,其机制可能与其能上调Claudin1、4、5、7和8的表达水平,同时降低Claudin-2的表达水平有关。     

A helminth immunomodulator reduces allergic and inflammatory responses by induction of IL-10-producing macrophages

The coincidence between infections with parasitic worms and the reduced prevalence of allergic disease in humans and in animal models has prompted the search for helminth molecules with antiallergic and antiinflammatory potential. We report herein that filarial cystatin, a secreted protease inhibitor of filarial nematodes, suppresses Th2-related inflammation and the ensuing asthmatic disease in a murine model of OVA-induced allergic airway responsiveness. Treatment with recombinant filarial cystatin inhibited eosinophil recruitment, reduced levels of OVA-specific and total IgE, down-regulated IL-4 production, and suppressed allergic airway hyperreactivity when applied during or after sensitization and before challenge with the allergen. Depletion of macrophages by clodronate-containing liposomes prevented the curative effects and restored the levels of infiltrating cells, IgE, and allergic airway reactivity. Blocking of IL-10 by application of anti-IL-10 receptor Abs restored the reduced number of infiltrating cells and the levels of OVA-specific IgE. In contrast, depletion of regulatory T cells by anti-CD25 Abs had only limited effects. Cystatin also modulated macrophage-mediated inflammation in a murine model of dextran sulfate sodium-induced colitis, leading to reduction of inflammatory infiltrations and epithelial damage. Our data demonstrate that treatment with a single helminth protein can exert the antiallergic effects of helminth infections.     

IL-10 modulates host responses and lung damage induced by Pneumocystis carinii infection

Host responses to Pneumocystis carinii infection mediate impairment of pulmonary function and contribute to the pathogenesis of pneumonia. IL-10 is known to inhibit inflammation and reduce the severity of pathology caused by a number of infectious organisms. In the present studies, IL-10-deficient (IL-10 knockout (KO)) mice were infected with P. carinii to determine whether the severity of pathogenesis and the efficiency of clearance of the organisms could be altered in the absence of IL-10. The clearance kinetics of P. carinii from IL-10 KO mice was significantly enhanced compared with that of wild-type (WT) mice. This corresponded to a more intense CD4(+) and CD8(+) T cell response as well as an earlier neutrophil response in the lungs of IL-10 KO mice. Furthermore, IL-12, IL-18, and IFN-gamma were found in the bronchoalveolar lavage fluids at earlier time points in IL-10 KO mice suggesting that alveolar macrophages were activated earlier than in WT mice. However, when CD4(+) cells were depleted from P. carinii-infected IL-10 KO mice, the ability to enhance clearance was lost. Furthermore, CD4-depleted IL-10 KO mice had significantly more lung injury than CD4-depleted WT mice even though the intensity of the inflammatory responses was similar. This was characterized by increased vascular leakage, decreased oxygenation, and decreased arterial pH. These data indicate that IL-10 down-regulates the immune response to P. carinii in WT mice; however, in the absence of CD4(+) T cells, IL-10 plays a critical role in controlling lung damage independent of modulating the inflammatory response.     

Dieckol attenuates the nociception and inflammatory responses in different nociceptive and inflammatory induced mice model

Pain is the common indicator of inflammatory ailments and traumatic tissue injuries. The dieckol is an important therapeutic compound, which present in many seaweeds. The present research work was planned to assess the anti-inflammatory and anti-nociceptive actions of dieckol by using animal model. The anti-nociceptive action of dieckol was investigated by acetic acid triggered writhing, formalin provoked nociception, tail immersion test, hot-plate methods and the anti-inflammatory effects was explored by carrageenan triggered paw edema method. In the present investigation the administration of dieckol was remarkably suppressed and inhibited the acetic acid-provoked writhing, formalin-triggered nociception, tail immersion test, hot plate-provoked nociception in the experimental animals. The dieckol was significantly (p < 0.05) inhibited the carrageenan-triggered inflammation, leukocyte infiltration and diminished the formation of pro-inflammatory regulators in the experimental animals. Altogether, the dieckol was showed a potent anti-nociceptive and anti-inflammatory activity.     

IL-6 promotes acute and chronic inflammatory disease in the absence of SOCS3

The lack of expression of the suppressor of cytokine signalling-3 (SOCS3) or inactivation of the negative regulatory capacity of SOCS3 has been well documented in rheumatoid arthritis, viral hepatitis and cancer. The specific qualitative and quantitative consequences of SOCS3 deficiency on interleukin-6 (IL-6)-mediated pro- and anti-inflammatory responses remain controversial in vitro and unknown in vivo. Mice with a conditional deletion of SOCS3 in hematopoietic cells develop lethal inflammatory disease during adult life and develop gross histopathological changes during experimental arthritis, typified by elevated IL-6 levels. To clarify the nature of the IL-6 responses in vivo, we generated mice deficient in SOCS3 (SOCS3(-/Δvav)) or both SOCS3 and IL-6 (IL-6(-/-)/SOCS3(-/Δvav)), and examined responses in models of acute and chronic inflammation. Acute responses to IL-1β were lethal to SOCS3(-/Δvav) mice but not IL-6(-/-)/SOCS3(-/Δvav) mice, indicating that IL-6 was required for the lethal inflammation induced by IL-1β. Administration of IL-1β to SOCS3(-/Δvav) mice induced systemic apoptosis of lymphocytes in the thymus, spleen and lymph nodes that was dependent on the presence of IL-6. IL-6 deficiency prolonged survival of SOCS3(-/Δvav) mice and ameliorated spontaneous inflammatory disease developing during adult life. Infection of SOCS3(-/Δvav) mice with LCMV induced a lethal inflammatory response that was dependent on IL-6, despite SOCS3(-/Δvav) mice controlling viral replication. We conclude that SOCS3 is required for survival during inflammatory responses and is a critical regulator of IL-6 in vivo.     

Sequential appearance of IL-1 and IL-6 activities in rat carrageenin-induced pleurisy.

IL-1 and IL-6 activities were measured in the pleural exudate of rats during carrageenin-induced pleurisy to examine the relationship of the local production of cytokines to the inflammatory reaction. Time courses of appearance of the cytokines and inflammatory parameters in the exudate were compared. IL-1 activity and exudate volume started to increase at 1 h after the carrageenin injection, and then slightly later IL-6 activity and leukocyte number began to increase. IL-1 showed peak activity of approximately 700 U at 3 h and IL-6, of 6000 U at 5 h in the exudate, whereas exudate volume and number of polymorphonuclear leukocytes continued to increase thereafter. Furthermore, IL-6 level in the plasma of the carrageenin-injected rats showed a peak at 4 h (30 U/ml), and when rhIL-1 alpha (100,000 U) was intrapleurally injected, the more rapid increase in plasma IL-6 level was demonstrated at 1 h (30 U/ml). This latter rise was neutralized with simultaneous injection of anti-rhIL-1 alpha antibody. These facts indicate the possibility that IL-1 produced in the exudate or injected could rapidly propagate a signal to induce IL-6 production in the circulation. It took several hours to transmit an inflammatory signal that stimulated the liver to synthesize the acute-phase protein, T-kininogen. The time lag from the peak induction of IL-1 to the T-kininogen-increase in the pleurisy corresponded well to the interval for T-kininogen-increase by exogenous rhIL-1 alpha injection. These results strongly suggest that the initial inflammatory stimulus induces sequentially IL-1, IL-6, and T-kininogen production in this carrageenin inflammation.