Experimental study on the possibility of treatment of some hemorrhagic fevers

After intracerebral challenge with 100 PFU of Lassa virus (strain Josiah), all infected mice (CBA/calac) died (control group). Production of pro-inflammatory cytokines (IL-1beta, TNF-alpha) significantly increased in the blood of these mice during the infection. For neutralization of increasing concentrations of these cytokines recombinant IL-1RA was used intraperitonealy at a dose 100 microg kg(-1), everyday, within 5 days from the third day after the challenge. Injections of IL-1RA decreased the concentration of IL-1beta and TNF-alpha and resulted in survival of all infected mice (treatment group). Marburg fever (strain Popp) caused in guinea pigs by 5 LD(50) of virus lead to the significant increase of TNF-alpha in the animal's blood and caused a lethal outcome (control group). Treatment of infected guinea pigs by IL-1RA or anti-TNF serum decreased the concentration of TNF-alpha and resulted in survival of half of the animals (treatment group). For the treatment recombinant IL-1RA was used at a dose 100 microg kg(-1), intramuscularly, everyday, within 6 days from the third day after the challenge or anti-TNF serum, intramuscularly 0.5 ml (2000 U ml(-1); 1 U of the antiserum neutralises 0.03 ng of TNF-alpha), everyday, within 6 days from the third day after the challenge.     

Differential induction of TGF-beta regulates proinflammatory cytokine production and determines the outcome of lethal and nonlethal Plasmodium yoelii infections

Transforming growth factor-beta is an essential moderator of malaria-induced inflammation in mice. In this study, we show that the virulence of malaria infections is dependent upon the cellular source of TGF-beta and the timing of its production. C57BL/6 mice infected with a nonlethal (Py17X) strain of Plasmodium yoelii produce TGF-beta from 5 days postinfection; this correlates with resolution of parasitemia, down-regulation of TNF-alpha, and full recovery. In contrast, infection with the lethal strain Py17XL induces high levels of circulating TGF-beta within 24 h; this is associated with delayed and blunted IFN-gamma and TNF-alpha responses, failure to clear parasites, and 100% mortality. Neutralization of early TGF-beta in Py17XL infection leads to a compensatory increase in IL-10 production, while simultaneous neutralization of TGF-beta and IL-10R signaling leads to up-regulation of TNF-alpha and IFN-gamma, prolonged survival in all, and ultimate resolution of infection in 40% of Py17XL-infected animals. TGF-beta production can be induced in an Ag-specific manner from splenocytes of infected mice, and by cross-linking surface CTLA-4. CD25(+) and CD8(+) cells are the primary source of TGF-beta following Py17X stimulation of splenocytes, whereas Py17XL induces significant production of TGF-beta from adherent cells. In mice immunized against Py17XL, the early TGF-beta response is inhibited and is accompanied by significant up-regulation of IFN-gamma and TNF-alpha and rapid resolution of challenge infections.     

Pneumocystis carinii infection sensitizes lung to radiation-induced injury after syngeneic marrow transplantation: role of CD4+ T cells

A murine model of bone marrow transplant (BMT)-related lung injury was developed to study how infection sensitizes lung to the damaging effects of total body irradiation (TBI) at infectious and TBI doses that individually do not cause injury. Mice infected with Pneumocystis carinii exhibited an asymptomatic, rapid, and transient influx of eosinophils and T cells in bronchoalveolar lavage fluid (BALF). In contrast, mice infected with P. carinii 7 days before receiving TBI and syngeneic BMT (P. carinii/TBI mice) exhibited severe pulmonary dysfunction, surfactant aggregate depletion, and surfactant activity reductions at 17 days post-BMT. BALF from P. carinii/TBI mice contained a disproportionate initial influx of CD4(+) T cells (CD4(+):CD8(+) ratio of 2.7) that correlated with progressive lung injury (from 8 to 17 days post-BMT). Levels of TNF-alpha in BALF were significantly increased in P. carinii/TBI mice compared with mice given either insult alone, with peak values found at 11 days post-BMT. In vivo depletion of CD4(+) T cells in P. carinii/TBI mice abrogated pulmonary dysfunction and reduced TNF-alpha levels in BALF, whereas depletion of CD8(+) T cells did not affect lung compliance or TNF-alpha. Lung injury was not attributable to direct P. carinii damage, since CD4-depleted P. carinii/TBI mice that exhibited no injury had higher average lung P. carinii burdens than either mice given P. carinii alone or undepleted P. carinii/TBI mice. Together, these results indicate that P. carinii infection can sensitize the lung to subsequent TBI-mediated lung injury via a process dependent on non-alloreactive CD4(+) T cells.     

Interleukin-5 modulates interleukin-8 secretion in eosinophilic inflammation.

Serum and BALF (bronchoalveolar lavage fluid) IL-8 levels and serum levels were investigated in Toxocara canis infected guinea-pigs and the role of IL-5 as a modulator of cytokine secretion was studied. Serum levels increased early in infected animals, exceeding control levels 4 h after infection, peaked between days 6 and 18, and continued to exceed control levels after 48 days of infection. Serum and BALF IL-8 levels showed the same profile as blood eosinophilia, increasing 6 days post-infection and peaking between days 18 and 24. Treatment of infected animals with anti-IL-5 Ab suppressed eosinophilia with a parallel increase in blood IL-8 levels, whereas no change was found in levels. To support our in vivo observation we carried out experiments in vitro using guinea-pig LPS-stimulated adherent peritoneal cells which release large amounts of IL-8 into the supernatants. When rIL-5 was added to LPS-stimulated cells, 65% inhibition of IL-8 release into the supernatants was observed. Pre-incubation of cells with anti-IL-5 Ab prevented the inhibition of IL-8 release into the supernatants induced by rIL-5. Our results demonstrate for the first time that TNF-alpha and IL-8 are released concomitant with or after IL-5 in the eosinophilic inflammation induced by T. canis. Moreover, in addition to showing that IL-5 is fundamental for the induction of blood eosinophilia, the present results suggest that this cytokine may play a new biological role by acting as modulator of IL-8 secretion.     

Toll-like receptor 4 mediates innate immune responses to Haemophilus influenzae infection in mouse lung.

Toll-like receptors (TLRs) have been implicated in the regulation of host responses to microbial Ags. This study characterizes the role of TLR4 in the innate immune response to intrapulmonary administration of Haemophilus influenzae in the mouse. Two different strains of mice efficiently cleared aerosolized H. influenzae concurrent with a brisk elaboration of IL-1beta, IL-6, TNF-alpha, macrophage-inflammatory protein (MIP)-1alpha, and MIP-2 in bronchoalveolar lavage and a corresponding mobilization of intrapulmonary neutrophils. Congenic strains of mice deficient in TLR4 demonstrated a substantial delay in clearance of H. influenzae with diminished IL-1beta, IL-6, TNF-alpha, MIP-1alpha, and MIP-2 in bronchoalveolar lavage and a notable absence of intrapulmonary neutrophils. In TLR4-expressing animals, but not TLR4-deficient animals, TNF-alpha and MIP-1alpha expression was up-regulated in epithelial cells of the conducting airway in response to H. influenzae which was preceded by an apparent activation of the NF-kappaB pathway in these cells based on the findings of decreased overall IkappaB and an increase in its phosphorylated form. This study demonstrates a critical role of TLR4 in mediating an effective innate immune response to H. influenzae in the lung. This suggests that the airway epithelia might contribute to sensing of H. influenzae infection and signaling the innate immune response.     

IL-10 limits parasite burden and protects against fatal myocarditis in a mouse model of Trypanosoma cruzi infection

Chagas' disease is a zoonosis prevalent in Latin America that is caused by the protozoan Trypanosoma cruzi. The immunopathogenesis of cardiomyopathy, the main clinical problem in Chagas' disease, has been extensively studied but is still poorly understood. In this study, we systematically compared clinical, microbiologic, pathologic, immunologic, and molecular parameters in two mouse models with opposite susceptibility to acute myocarditis caused by the myotropic Colombiana strain of T. cruzi: C3H/HeSnJ (100% mortality, uncontrolled parasitism) and C57BL/6J (<10% mortality, controlled parasitism). T. cruzi induced differential polarization of immunoregulatory cytokine mRNA expression in the hearts of C57BL/6J versus C3H/HeSnJ mice; however, most differences were small. The difference in IL-10 expression was exceptional (C57BL/6J 8.7-fold greater than C3H/HeSnJ). Consistent with this, hearts from infected C57BL/6J mice, but not C3H/HeSnJ mice, had a high frequency of total IL-10-producing CD8(+) T cells and both CD4(+) and CD8(+) subsets of IFN-γ(+)IL-10(+) double-producing T cells. Furthermore, T. cruzi infection of IL-10(-/-) C57BL/6J mice phenocopied fatal infection in wild-type C3H/HeSnJ mice with complete loss of parasite control. Adoptive transfer experiments indicated that T cells were a source of protective IL-10. Thus, in this system, IL-10 production by T cells promotes T. cruzi control and protection from fatal acute myocarditis.     

Systemic cytokine response in murine anthrax

Systemic pro-inflammatory cytokine release has been previously implicated as a major death-causing factor in anthrax, however, direct data have been absent. We determined the levels of IL-1 beta, IL-6 and TNF-alpha in serum of mice challenged with virulent (Ames) or attenuated (Sterne) strains of Bacillus anthracis. More than 10-fold increase in the IL-1beta levels was detected in Ames-challenged Balb/c mice, in contrast to more susceptible C57BL/6 mice, which showed no IL-1beta response. Balb/c mice have also responded with higher levels of IL-6. The A/J mice demonstrated IL-1beta and IL-6 systemic response to either Ames or Sterne strain of B. anthracis, whereas no increase in TNF-alpha was detected in any murine strain. We used RT-PCR for gene expression analyses in the liver which often is a major source of cytokines and one of the main targets in infectious diseases. A/J mice challenged with B. anthracis (Sterne) showed increased gene expression for Fas, FasL, Bax, IL-1 beta, TNF-alpha, TGF-beta, MIP-1alpha, KC and RANTES. These data favour the hypothesis that apoptotic cell death during anthrax infection causes chemokine-induced transmigration of inflammatory cells to vitally important organs such as liver. Administration of caspase inhibitors z-VAD-fmk and ac-YVAD-cmk improved survival in Sterne-challenged mice indicating a pathogenic role of apoptosis in anthrax.     

Infectivity of hepatic strain Klebsiella pneumoniae in diabetic mice

Besides urinary tract infection (UTI) and pneumonia, increased severe liver abscesses caused by Klebsiella pneumoniae (KP), especially in diabetic patients, have been observed in infections acquired in hospitals. This indicates that different KP strains with higher virulence have emerged in recent years. Our goal was to investigate the infectivity of KP isolates in mice from liver abscess or UTI patients. Mice were injected with streptozotocin to induce diabetes. Male ICR mice were infected with KpU1 (UTI strain CG3 for survival experiment only) and KpL1 (liver abscess strain CG5) by tail-vein injection of 5 x 10(4) colony-forming units (CFU) bacterial suspension. The mice survival rates, cytokine level by enzyme-linked immunosorbent assay (ELISA), and bacterial presence in liver tissue by Giemsa stain were examined. The survival rates for the KpL1-infected animals were 28% and 0% in normal and diabetic groups, respectively, whereas, for the KpU1-infected mice, the rates were 100% and 75% during a 30-day observation. Nonsurviving KpL1-infected mice showed > 10(5) bacteria/ml blood and the bacteria appeared in the liver sinus area and inside liver cells. The KpL1-infected mice showed a tendency to increase the blood interleukin 1beta (IL-1beta) level in both nondiabetic and diabetic groups, whereas the tumor necrosis factor-alpha (TNF-alpha) level was significantly decreased in the KpL1-infected diabetic mice (P = 0.002). In conclusion, the KP strain from liver abscess showed a greater virulence in mice than the KP from UTI and was more virulent in diabetic than in nondiabetic mice. The infection with KP from liver abscess significantly decreased the blood TNF-alpha level in diabetes mellitus (DM) mice and the blood IL-1beta level tended to increase in both infected nondiabetic and diabetic groups. High blood bacterial count and appearance of bacteria in liver sinus and cells usually contribute to death of the animals.     

Cytokine expression in the intestine of rainbow trout (Oncorhynchus mykiss) during infection with Aeromonas salmonicida

Gene expression of a number of cytokines in the intestine of rainbow trout (Oncorhynchus mykiss) was investigated after challenge with a pathogenic strain of Aeromonas salmonicida. Fish were exposed to A. salmonicida by immersion in a bacterial suspension (bath challenge) and tissue samples of the distal and proximal intestine were collected at days 0, 2, 4, 6 and 8 post-exposure. Head kidney tissue was also collected to assess the effect in a systemic immune tissue. A classic profile of pro-inflammatory cytokine upregulation was observed in the proximal intestine of fish infected by bath challenge, as determined by semi-quantitative RT-PCR. Expression of IL-1beta, IL-8, TNF-alpha and IFN-gamma was increased in the proximal intestine. TGF-beta was significantly decreased in the distal intestine. In the head kidney, infection with A. salmonicida by bath challenge caused decreased expression levels of IL-1beta, IL-8, TNF-alpha and TGF-beta. The results are discussed in the context of potential immune mechanisms in the gut to prevent infection.     

Airway epithelial NF-kappaB activation modulates asbestos-induced inflammation and mucin production in vivo

To investigate the role of bronchiolar epithelial NF-kappaB activity in the development of inflammation and fibrogenesis in a murine model of asbestos inhalation, we used transgenic (Tg) mice expressing an IkappaBalpha mutant (IkappaBalphasr) resistant to phosphorylation-induced degradation and targeted to bronchial epithelium using the CC10 promoter. Sham and chrysotile asbestos-exposed CC10-IkappaBalphasr Tg(+) and Tg(-) mice were examined for altered epithelial cell proliferation and differentiation, cytokine profiles, lung inflammation, and fibrogenesis at 3, 9, and 40 days. KC, IL-6 and IL-1beta were increased (p < or = 0.05) in bronchoalveolar lavage fluid (BALF) from asbestos-exposed mice, but to a lesser extent (p < or = 0.05) in Tg(+) vs Tg(-) mice. Asbestos also caused increases in IL-4, MIP-1beta, and MCP-1 in BALF that were more elevated (p < or = 0.05) in Tg(+) mice at 9 days. Differential cell counts revealed eosinophils in BALF that increased (p < or = 0.05) in Tg(+) mice at 9 days, a time point corresponding with significantly increased numbers of bronchiolar epithelial cells staining positively for mucus production. At all time points, asbestos caused increased numbers of distal bronchiolar epithelial cells and peribronchiolar cells incorporating the proliferation marker, Ki-67. However, bronchiolar epithelial cell and interstitial cell labeling was diminished at 40 days (p < or = 0.05) in Tg(+) vs Tg(-) mice. Our findings demonstrate that airway epithelial NF-kappaB activity plays a role in orchestrating the inflammatory response as well as cell proliferation in response to asbestos.     

Expression of inflammatory markers in pig amnion after intraamniotic infection with nonpathogenic or enteropathogenic<Emphasis Type="Italic">Escherichia coli</Emphasis>

The pig amnion was in vivo intraamniotically infected with E. coli for 10 h at 80-85 d of gestation either with the nonpathogenic O86 strain or enteropathogenic O55 strain. TNF-alpha, IL-10, IL-1beta and IFN-gamma were determined in amniotic fluids by ELISA, the expression of cytokines and some other inflammatory markers was determined by immunohistochemistry. Intraamniotic infection induced high levels of TNF-alpha in amniotic fluids which correlated with bacterial virulence whereas IL-10 was induced only by O86. The IL-1beta level did not increase significantly and was expressed in all infected membranes. IFN-gamma was negligible or absent. TNF-alpha, IL-12p40, calprotectin, HSP65 and gp91phox were found by immunohistochemistry only in amnion membranes infected with the enteropathogenic strain 055.     

Cold stress-induced modulation of inflammatory responses and intracerebral cytokine mRNA expression in acute murine toxoplasmosis

The effects of a physical stressor, cold water stress (CWS), within the central nervous system were investigated in the acute phase of infection with Toxoplasma gondii. Female BALB/c mice were subjected to CWS for 5 min each day for 8 days prior to oral infection with 20 cysts of the low virulent ME 49 strain. Animals were killed at 10-day intervals to detect inflammation, gliosis, and expression of intracerebral cytokine mRNAs. Zones of inflammation were detected by Nissl staining and gliosis by immunoreactivity to glial fibrillary acidic protein. Larger zones of inflammation and reactive astrogliosis were consistently observed in mice subjected to CWS and infected (CWS +INF) compared to control infected (INF) mice. Expression of interleukin (IL)-1beta, IL-2, IL-12, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and inducible nitric oxide synthase (iNOS) were decreased in CWS+INF mice at 10 days postinoculation (PI), followed by a gradual increase after day 20 PI. This was in contrast to increased expression of these cytokines at 10 days PI in INF mice with a gradual decline thereafter. Inflammation and astrogliosis in CWS+INF mice were associated with an increased expression of IL-1beta, IL-6, IL-12, and TNF-alpha between 20 and 30 days PI. These findings correlated with the continuous gene expression of tachyzoite surface antigen (SAG)-1 mRNA in CWS+INF mice compared to its sharp decline in INF mice after 20 days PI. These results suggest that CWS delays regulation and control of intracerebral Toxoplasma gondii during acute infection in BALB/c mice by decreasing the early expression of IFN-gamma, IL-2, TNF-alpha, iNOS, IL-1beta, and IL-12, while increasing the expression of IL-6, a counterregulatory cytokine.     

Toll-like receptor-2, but not Toll-like receptor-4, is essential for development of oviduct pathology in chlamydial genital tract infection

The roles of Toll-like receptor (TLR) 2 and TLR4 in the host inflammatory response to infection caused by Chlamydia trachomatis have not been elucidated. We examined production of TNF-alpha and IL-6 in wild-type TLR2 knockout (KO), and TLR4 KO murine peritoneal macrophages infected with the mouse pneumonitis strain of C. trachomatis. Furthermore, we compared the outcomes of genital tract infection in control, TLR2 KO, and TLR4 KO mice. Macrophages lacking TLR2 produced significantly less TNF-alpha and IL6 in response to active infection. In contrast, macrophages from TLR4 KO mice consistently produced higher TNF-alpha and IL-6 responses than those from normal mice on in vitro infection. Infected TLR2-deficient fibroblasts had less mRNA for IL-1, IL-6, and macrophage-inflammatory protein-2, but TLR4-deficient cells had increased mRNA levels for these cytokines compared with controls, suggesting that ligation of TLR4 by whole chlamydiae may down-modulate signaling by other TLRs. In TLR2 KO mice, although the course of genital tract infection was not different from that of controls, significantly lower levels of TNF-alpha and macrophage-inflammatory protein-2 were detected in genital tract secretions during the first week of infection, and there was a significant reduction in oviduct and mesosalpinx pathology at late time points. TLR4 KO mice responded to in vivo infection similarly to wild-type controls and developed similar pathology. TLR2 is an important mediator in the innate immune response to C. trachomatis infection and appears to play a role in both early production of inflammatory mediators and development of chronic inflammatory pathology.     

A kinetic study of immune mediators in the lungs of mice infected with influenza A virus.

We investigated a broad spectrum of immunoactive mediators in a mouse model of influenza. ICR mice (4-5 wk old) that were infected with a 10 LD50 dose of influenza A/PR8/34 virus died after 6 days without evidence of bacterial superinfection. Maximal virus titers were reached by day 2 postinfection, whereas the multifocal pneumonia with mononuclear cell infiltration reached its maximum at the end of infection. We measured the cytokines IL-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-6, IFN-gamma, TNF-alpha, granulocyte (G)/macrophage (M)-CSF, G-CSF, M-CSF, and the lipid mediators leukotriene B4 and platelet-activating factor in the cellfree bronchoalveolar lavage fluid of mice during infection. We found an early increase of IL-1 alpha, IL-1 beta, IL-6, TNF-alpha, GM-CSF, IFN-gamma, and leukotriene B4. Levels of these factors peaked between 36 h and day 3 postinfection, with the exception of IL-6 that remained at elevated levels throughout infection. G-CSF and M-CSF increased slowly and reached a maximum by day 5 postinfection. We were unable to detect IL-2, IL-3, or IL-4. PAF remained at the same level throughout infection. Our results suggest that lung-resident cells, and possibly the alveolar macrophages, participate actively in the onset of the inflammatory response against the invading virus. The inability to detect the T cell products IL-2, IL-3, and IL-4 was unexpected considering the role of T cells in the elimination of the virus in infected mice. Our observation confirms thus earlier findings about the inability of specific T cell clones to elicit an unspecific antiviral effect.     

Protective and memory immunity to Histoplasma capsulatum in the absence of IL-10

We determined whether the absence of IL-10 in mice influenced protective and memory immunity to Histoplasma capsulatum. IL-10(-/-) mice cleared primary and secondary infection more rapidly than wild-type controls. Administration of mAb to TNF-alpha or IFN-gamma, but not GM-CSF, abrogated protection in naive IL-10(-/-) mice; mAb to TNF-alpha, but not IFN-gamma or GM-CSF, subverted protective immunity in secondary histoplasmosis. The inflammatory cell composition in IL-10(-/-) mice was altered in those given mAb to IFN-gamma or TNF-alpha. More Gr-1(+) and Mac-3(+) cells were present in lungs of IL-10(-/-) mice given mAb to IFN-gamma, and treatment with mAb to TNF-alpha sharply reduced the number of CD8(+) cells in lungs of IL-10(-/-) mice. We ascertained whether the lack of IL-10 modulated memory T cell generation or the protective function of cells. The percentage of CD3(+), CD44(high), CD62(low), and IFN-gamma(+) cells in IL-10(-/-) mice was higher than that of wild-type at day 7 but not day 21 or 49 after immunization. Fewer splenocytes from immunized IL-10(-/-) mice were required to mediate protection upon adoptive transfer into infected TCR alphabeta(-/-) mice. Hence, deficiency of IL-10 confers a salutary effect on the course of histoplasmosis, and the beneficial effects of IL-10 deficiency require endogenous TNF-alpha and/or IFN-gamma. Memory cell generation was transiently increased in IL-10(-/-) mice, but the protective function conferred by cells from these mice following immunization is strikingly more vigorous than that of wild-type.     

The effects of infection of thermal injury by Pseudomonas aeruginosa PAO1 on the murine cytokine response.

Pseudomonas aeruginosa infection, one of the major complications of burn wounds, may lead to sepsis and death. Using the Multi-Probe Template/RNase protection assay, we have compared the expression of different cytokine genes within the skin and livers of thermally injured mice infected with P. aeruginosa PAO1. Thermal injury alone enhanced or up-regulated certain cytokines, including macrophage colony-stimulating factor (M-CSF), interleukin 1 (IL-1)RI, IL-1 beta, macrophage inflammatory protein (MIP)-1 beta and MIP-2; while PAO1 challenge alone up-regulated tumour necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) expression. The combination of thermal injury plus PAO1 infection enhanced the expression of several pro-inflammatory and haematopoietic cytokines [stem cell factor (SCF), leukocyte inhibitory factor (LIF), IL-6 and TNF-alpha]; induced the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF by 5 h and the expression of additional cytokines, including TGF-beta, TNF-beta, lymphotoxin beta (LT-beta), interferon gamma (IFN-gamma), and IFN-beta by 40 h post-burn/infection. While the most intense cytokine expression occurred in the skin, the majority of cytokines tested were also expressed in the liver by 40 h post-burn/infection. These results suggest that in P. aeruginosa infection of burn wounds: (1) up-regulation of the expression of different cytokines, locally and within the livers of burned mice, is an indication of P. aeruginosa -induced sepsis; and (2) IL-6 and G-CSF play an important role in the host response mechanism.     

Passively administered pooled human immunoglobulins exert IL-10 dependent anti-inflammatory effects that protect against fatal HSV encephalitis

HSV-1 is the leading cause of sporadic encephalitis in humans. HSV infection of susceptible 129S6 mice results in fatal encephalitis (HSE) caused by massive inflammatory brainstem lesions comprising monocytes and neutrophils. During infection with pathogenic microorganisms or autoimmune disease, IgGs induce proinflammatory responses and recruit innate effector cells. In contrast, high dose intravenous immunoglobulins (IVIG) are an effective treatment for various autoimmune and inflammatory diseases because of potent anti-inflammatory effects stemming in part from sialylated IgGs (sIgG) present at 1-3% in IVIG. We investigated the ability of IVIG to prevent fatal HSE when given 24 h post infection. We discovered a novel anti-inflammatory pathway mediated by low-dose IVIG that protected 129S6 mice from fatal HSE by modulating CNS inflammation independently of HSV specific antibodies or sIgG. IVIG suppressed CNS infiltration by pathogenic CD11b(+) Ly6C(high) monocytes and inhibited their spontaneous degranulation in vitro. FcγRIIb expression was required for IVIG mediated suppression of CNS infiltration by CD45(+) Ly6C(low) monocytes but not for inhibiting development of Ly6C(high) monocytes. IVIG increased accumulation of T cells in the CNS, and the non-sIgG fraction induced a dramatic expansion of FoxP3(+) CD4(+) T regulatory cells (Tregs) and FoxP3(-) ICOS(+) CD4(+) T cells in peripheral lymphoid organs. Tregs purified from HSV infected IVIG treated, but not control, mice protected adoptively transferred mice from fatal HSE. IL-10, produced by the ICOS(+) CD4(+) T cells that accumulated in the CNS of IVIG treated, but not control mice, was essential for induction of protective anti-inflammatory responses. Our results significantly enhance understanding of IVIG's anti-inflammatory and immunomodulatory capabilities by revealing a novel sIgG independent anti-inflammatory pathway responsible for induction of regulatory T cells that secrete the immunosuppressive cytokine IL-10 and further reveal the therapeutic potential of IVIG for treating viral induced inflammatory diseases.     

Role of IL-6 in the induction of hepatic metallothionein in mice after partial hepatectomy

Metallothioneins (MT) are induced upon partial hepatectomy (PH), possibly mediated by various cytokines. In the present study, we studied cytokine-dependent MT synthesis in partially hepatectomized IL-6 gene knock-out (GKO) mice in the remaining lobe of the liver. We focused on IL-6, TNFalpha and IL-1beta, the major cytokines thought to be involved in MT synthesis. The IL-6 GKO mice and B6J129Sv (wild-type control) mice were subjected to 70% PH or laparotomy. We found that MT was significantly decreased in IL-6 GKO mice, although PH induced hepatic MT in both strains of mice. Laparotomy induced MT in the liver of wild-type mice but not in IL-6 GKO mice. Pretreatment of IL-6 GKO mice with rIL-6 (5 microg/mouse) restored hepatic MT synthesis. Serum IL-6 level in wild-type mice was maximal at 6 h after surgery and decreased thereafter. Serum IL-1beta was the same in both strains of mice. Serum TNFalpha basal level in IL-6 GKO mice was higher than in wild-type mice. PH caused an increase in serum TNFalpha level in both strains of mice, and it was two times higher in IL-6 GKO mice than in wild-type mice at 18 h after surgery. We conclude that IL-6 plays a predominant role in hepatic MT synthesis after PH, but that IL-6 GKO mice still reserve the capacity to synthesize MT by an as yet unidentified mechanism.     

Inhibition of Nox2 oxidase activity ameliorates influenza A virus-induced lung inflammation

Influenza A virus pandemics and emerging anti-viral resistance highlight the urgent need for novel generic pharmacological strategies that reduce both viral replication and lung inflammation. We investigated whether the primary enzymatic source of inflammatory cell ROS (reactive oxygen species), Nox2-containing NADPH oxidase, is a novel pharmacological target against the lung inflammation caused by influenza A viruses. Male WT (C57BL/6) and Nox2(-/y) mice were infected intranasally with low pathogenicity (X-31, H3N2) or higher pathogenicity (PR8, H1N1) influenza A virus. Viral titer, airways inflammation, superoxide and peroxynitrite production, lung histopathology, pro-inflammatory (MCP-1) and antiviral (IL-1β) cytokines/chemokines, CD8(+) T cell effector function and alveolar epithelial cell apoptosis were assessed. Infection of Nox2(-/y) mice with X-31 virus resulted in a significant reduction in viral titers, BALF macrophages, peri-bronchial inflammation, BALF inflammatory cell superoxide and lung tissue peroxynitrite production, MCP-1 levels and alveolar epithelial cell apoptosis when compared to WT control mice. Lung levels of IL-1β were ～3-fold higher in Nox2(-/y) mice. The numbers of influenza-specific CD8+D(b)NP(366)+ and D(b)PA(224)+ T cells in the BALF and spleen were comparable in WT and Nox2(-/y) mice. In vivo administration of the Nox2 inhibitor apocynin significantly suppressed viral titer, airways inflammation and inflammatory cell superoxide production following infection with X-31 or PR8. In conclusion, these findings indicate that Nox2 inhibitors have therapeutic potential for control of lung inflammation and damage in an influenza strain-independent manner.