Endogenous gamma interferon, tumor necrosis factor, and interleukin-6 in Staphylococcus aureus infection in mice.

The production and roles of endogenous gamma interferon (IFN-gamma), tumor necrosis factor (TNF), and interleukin-6 (IL-6) in both lethal and nonlethal infections of Staphylococcus aureus were investigated in mice. In the case of nonlethal infection, although no bacteria were detected in the bloodstreams, bacteria that colonized and proliferated persistently for 3 weeks were found in the kidneys. All mice given lethal injections died within 7 days, and large numbers of bacteria were detected in the bloodstreams, spleens, and kidneys. The first peaks of IFN-gamma, TNF, and IL-6 were observed in the bloodstreams and spleens of the mice with nonlethal and lethal infections within 24 h. Thereafter, in the nonlethal cases, IFN-gamma, TNF, and IL-6 peaked again in the spleens and kidneys during the period of maximum growth of bacteria in the kidneys, although only IL-6 was detected in the sera. In contrast, in the case of lethal infection, the titers of IFN-gamma and IL-6 in the sera and TNF in the kidneys peaked before death. Effects of in vivo administration of monoclonal antibodies (MAbs) against IFN-gamma and TNF on the fates of S. aureus-infected mice were studied. In the nonlethal infections, anti-TNF alpha (anti-TNF-alpha) MAb-treated mice, but not anti-IFN-gamma MAb-treated mice, died as a result of worsening infection, suggesting that endogenous TNF plays a protective role in host resistance to S. aureus infection. In the mice that received lethal doses, injection of anti-TNF-alpha MAb accelerated death. However, although injection of anti-IFN-gamma MAb inhibited host resistance of the infected mice early in infection, most of the animals survived the lethal infection by injection of anti-IFN-gamma MAb, suggesting that endogenous IFN-gamma plays a detrimental role in S. aureus infection. Thus, this study demonstrated that IFN-gamma and TNF play different roles in S. aureus infection.     

Assessment of interleukin-12, gamma interferon, and tumor necrosis factor alpha secretion in sera from mice fed with dietary lipids during different stages of Listeria monocytogenes infection

Recent experimental observations have determined that long-chain n-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) production in the sera of mice fed these diets and challenged with Listeria monocytogenes were determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-gamma, which appear to play an important role in the reduction of host resistance to L. monocytogenes infection. In addition, an efficient elimination of L. monocytogenes was observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-alpha production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-gamma production before L. monocytogenes infection represents the most relevant event that corroborates the impairment of immune resistance by n-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase of L. monocytogenes infection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group.     

Interaction of interleukin-6, tumour necrosis factor and interleukin-1 during Listeria infection.

Injected recombinant interleukin-6 (IL-6), tumour necrosis factor (TNF) and IL-1 all protect mice against experimental infection with Listeria monocytogenes. We have therefore investigated the interaction of these cytokines during infection. Treatment with recombinant (r)IL-6 enhanced TNF production by spleen cells during the first 2 days of infection. Anti-TNF antibody could totally abolish the protective effect of rIL-6, while the optimal protective function of TNF could not be achieved when IL-6 was neutralized by anti-IL-6 antibody. IL-1 induced a high level of IL-6 in the serum a short time after its administration, and neutralization of IL-6 totally abolished the protective function of rIL-1. The results thus provide further evidence for the complexity of cytokine interaction.     

Endogenous tumor necrosis factor alpha is required for enhanced antimicrobial activity against Toxoplasma gondii and Listeria monocytogenes in recombinant gamma interferon-treated mice.

In vitro studies have shown that macrophages stimulated with recombinant gamma interferon (rIFN-gamma) produce tumor necrosis factor alpha (TNF-alpha), which in an autocrine fashion activates these cells. The aim of the present study was to determine whether endogenously formed TNF-alpha also is required for rIFN-gamma-induced macrophage activation and enhanced antimicrobial activity in vivo. After an intraperitoneal injection of rIFN-gamma into CBA/J mice, their peritoneal macrophages released enhanced amounts of NO2- and inhibited the intracellular proliferation of Toxoplasma gondii. Injection of neutralizing antibodies against TNF-alpha simultaneously with the rIFN-gamma completely inhibited both the release of NO2- by macrophages and their toxoplasmastatic activity. Similar results were observed after intraperitoneal injection of a competitive inhibitor of L-arginine, NG-monomethyl-L-arginine, together with rIFN-gamma, demonstrating that in vivo L-arginine-derived reactive nitrogen intermediates are essential for the induction of toxoplasmastatic activity. Intravenous injection of rIFN-gamma inhibited the growth of Listeria monocytogenes in the livers and spleens of mice; this effect was abrogated by antibodies against TNF-alpha. Intravenous injection of a large dose of rTNF-alpha resulted in a decrease in the number of bacteria in the liver and spleen, but an injection of rIFN-gamma and rTNF-alpha did not result in enhanced inhibition of the proliferation of L. monocytogenes. Together, the results of the present study are the first to demonstrate that endogenous TNF-alpha is required in vivo for the expression of macrophage activation with respect to the release of reactive nitrogen intermediates and toxoplasmastatic activity and for enhanced listericidal activity in the livers and spleens of mice stimulated with rIFN-gamma.     

Protection of mice against Listeria monocytogenes infection by recombinant human tumor necrosis factor alpha.

Recombinant human tumor necrosis factor alpha (rHuTNF-alpha) administered intravenously to mice resulted in enhanced resistance to a lethal challenge infection of Listeria monocytogenes given 24 h later. The observed protection was lost following treatment of the rHuTNF-alpha preparations with rabbit polyclonal antibody rHuTNF-alpha but not with normal rabbit immunoglobulin G.     

Endogenous tumor necrosis factor (cachectin) is essential to host resistance against Listeria monocytogenes infection.

During a sublethal murine infection with Listeria monocytogenes cells, tumor necrosis factor (TNF) activity was detectable in neither sera nor spleen homogenates at any stage of the infection when a bioassay with L-929 cells (less than 4 U/ml) was used. However, injecting the mice with an immunoglobulin fraction obtained from a rabbit hyperimmunized with recombinant murine TNF-alpha resulted in acceleration of listeriosis. When 1 mg of anti-TNF antibody was injected per mouse, all the mice died from listeriosis, even though the infectious dose was sublethal for the untreated controls. The antigen-specific elimination of the bacterium from the spleens and livers of anti-TNF antibody-treated mice was delayed, depending on the dose of the antibody injected. Endogenous TNF seemed to be produced early in infection, because suppression of antilisterial resistance was significant when a single injection of anti-TNF antibody was given between day zero and day 2 of infection. The effect of endogenous TNF on antilisterial resistance was due to neither regulation of alpha interferon (IFN-alpha) and IFN-gamma production nor induction of IFN-beta subtype 1 (IFN-beta 1), because anti-TNF antibody treated-mice produced normal levels of IFN-alpha and IFN-gamma in the bloodstream during infection and administration of monoclonal anti-murine IFN-beta 1 antibody had no effect on the development of listeriosis. Alternatively, the listericidal activity of peritoneal macrophages of L. monocytogenes-infected mice could be abrogated by injection of anti-TNF antibody in vivo. These results suggest that the lower level of TNF is produced endogenously in mice that received L. monocytogenes infection and that it plays an essential role in the host defense against L. monocytogenes infection.     

Interactions between endogenous gamma interferon and tumor necrosis factor in host resistance against primary and secondary Listeria monocytogenes infections.

Intravenous injection of rat anti-mouse gamma interferon (IFN-gamma) monoclonal antibody as well as rabbit anti-mouse tumor necrosis factor (TNF) antibody into mice which had received a sublethal infection with Listeria monocytogenes cells resulted in acceleration of listeriosis. Endogenous IFN-gamma seemed to be produced early in infection, because suppression of antilisterial resistance was significant when a single injection of anti-IFN-gamma monoclonal antibody was given on day 0 or day 1 of infection. Production of TNF but not of IFN-gamma in the bloodstream early in infection was inhibited by administration of anti-IFN-gamma monoclonal antibody. The suppressive effect of anti-IFN-gamma and anti-TNF antibodies on antilisterial resistance was not augmented by simultaneous administration of these antibodies. On the other hand, in the secondary infection, simultaneous administration of anti-IFN-gamma and anti-TNF antibodies, but not of either of these antibodies alone, into L. monocytogenes-immune mice resulted in high mortality and explosive multiplication of bacterial cells in the spleens and livers. These results suggest that endogenously produced IFN-gamma and TNF are both essential to the host defense against L. monocytogenes infection and that these cytokines might act by different modes between the primary infection and the secondary infection.     

Recombinant murine gamma interferon induces enhanced resistance to Listeria monocytogenes infection in neonatal mice.

Neonatal mice within 24 h of birth were highly susceptible to intraperitoneal infection with Listeria monocytogenes. The 50% lethal dose of bacterial cells was 6.3 X 10(1) CFU for neonates and 3.2 X 10(6) CFU for adult mice. A single injection of recombinant murine gamma interferon (rMuIFN-gamma) protected neonatal mice from simultaneous challenge with a lethal dose of L. monocytogenes cells. The rMuIFN-gamma effect was dose dependent: protection was consistently observed in mice treated with rMuIFN-gamma at doses of more than 4 X 10(2) U (0.1 microgram of protein) per mouse. Bacterial growth in the spleens and livers of rMuIFN-gamma-treated neonates was significantly suppressed in comparison with that in the nontreated controls. The infected neonatal mice showed acquired antilisterial resistance against secondary intravenous infection after 4 weeks of age, and this resistance was significantly augmented in mice that had been treated with rMuIFN-gamma.     

Induction of alpha/beta interferon and gamma interferon in mice infected with Listeria monocytogenes during pregnancy.

Alpha/beta interferon (IFN-alpha/beta) was induced in the bloodstream of mice 48 h after intravenous infection with Listeria monocytogenes, whereas IFN-gamma was induced in the bloodstream 6 h after stimulation with specific antigen on day 5 of infection in virgin mice. In contrast, no IFN-alpha/beta or IFN-gamma was produced in the bloodstream of pregnant mice after L. monocytogenes infection. However, unusual acid-labile IFN-alpha/beta instead of IFN-gamma was produced in some of the pregnant mice in response to specific antigen. The bacterial growth in the organs of pregnant mice in the early stage of infection was normal, but resulted in the delay of T-cell-dependent elimination of bacteria from the organs of pregnant animals in the late stage, and numerous bacteria were detected in both the placenta and the fetus. The significance of the IFN system induced by L. monocytogenes infection in pregnant mice is discussed.     

Activation of tuberculostatic macrophage functions by gamma interferon, interleukin-4, and tumor necrosis factor.

The capacity of the cytokines gamma interferon (IFN-gamma), interleukin-4 (IL-4), and tumor necrosis factor (TNF) to activate tuberculostatic functions in murine bone marrow-derived macrophages (BMM phi) was investigated. In confirmation of earlier findings, IFN-gamma rendered BMM phi capable of inhibiting subsequent infection with Mycobacterium bovis. In contrast, IL-4 and TNF failed to inhibit mycobacterial growth. However, in already infected BMM phi, tuberculostasis was induced by subsequent stimulation with IL-4. Although TNF alone was ineffective, it showed synergy with IFN-gamma in the stimulation of tuberculostasis. Our data suggest that not only IFN-gamma but also IL-4 and TNF participate in the control of mycobacterial growth.     

Inhibition of type 2,5'-deiodinase by tumor necrosis factor alpha, interleukin-6 and interferon gamma in human thyroid tissue.

The effects of tumor necrosis factor alpha (TNFalpha), interleukin-6 (IL-6) and interferon gamma (IFNgamma) were studied on the activity of type 2,5'-deiodinase and on the binding of [125I] T(4) to proteins in human thyroid cytosolic (supernatant) and membrane (pellet) fractions. The activity of thyroid type 2,5'-deiodinase was measured by iodothyronine outer ring deiodinase assay. The binding of [125I] T(4) to the proteins of thyroid cytosolic and membrane fractions was determined by autoradiography. The results showed that thyroid type 2,5'-deiodinase activity could be detected also in the cytosolic fraction, not only in the membrane. TNFalpha, IL-6 and IFNgamma could inhibit the type 2 deiodinase activity in vitro. The dose-dependent binding of [125I] T(4) to the proteins of 29, 66 and 200 kDa could be observed both in the cytosolic and membrane fractions. TNFalpha and IFNgamma inhibited the binding of [125I] T(4) to the two characteristic proteins of type 2,5'-deiodinase, to proteins of 29 and/or 200 kDa, both in the cytosolic and membrane fractions. We conclude that TNFalpha, IL-6 and IFNgamma can inhibit the activity of type 2,5'-deiodinase. Furthermore, TNFalpha and IFNgamma can still also decrease the binding of [125I] T(4) to the enzyme in vitro. It can be suggested that the increased level of these cytokines can be one of the reasons in the induction of the clinical symptoms in nonthyroidal illness associated with low levels of T(3).     

Evidence that endogenous gamma interferon is produced early in Listeria monocytogenes infection.

It has been presumed that gamma interferon (IFN-gamma), which plays an essential role in antilisterial resistance, is produced late in Listeria monocytogenes infection. In the present study, however, IFN-gamma was detected in the bloodstreams and spleens of mice from days 1 to 4 of L. monocytogenes infection by both a double-sandwich enzyme-linked immunosorbent assay and an immunohistochemical technique, suggesting that endogenous IFN-gamma is produced early but not late in L. monocytogenes infection.     

Prevention by gamma interferon of fatal infection with Listeria monocytogenes in mice treated with cyclosporin A.

The significance of interferons (IFNs) induced by Listeria monocytogenes in the antilisterial defense mechanism was studied in mice. Cyclosporin A (CsA) had no effect on IFN-alpha production that was induced in the bloodstream after intravenous infection of mice with L. monocytogenes, whereas IFN-gamma that was induced in the bloodstreams of control mice 6 h after stimulation with specific antigen in the late phase of infection was suppressed in CsA-treated mice, depending on the dose of the drug injected. The decrease in IFN-gamma production caused an increase in bacterial growth in the spleens and livers of CsA-treated mice. Furthermore, administration of a daily dose of CsA at 80 or 100 mg/kg of body weight resulted in fatal listeriosis, even though the dose was nonlethal for normal mice. The administration of recombinant murine IFN-gamma on day 0 of L. monocytogenes infection prevented CsA-treated mice from developing fatal listeriosis and restored their ability to produce IFN-gamma in the bloodstream, in response to specific antigen in the late phase of infection.     

Increased levels of macrophage colony-stimulating factor, gamma interferon, and tumor necrosis factor alpha in sera of patients with Orientia tsutsugamushi infection.

Levels of macrophage colony-stimulating factor (nine of nine patients) and gamma interferon (six of nine patients) in serum were elevated above the range of normal in the acute phase of tsutsugamushi disease. Significant increases in levels of tumor necrosis factor alpha were observed during the convalescent phase in five patients, and they exceeded the levels observed during the acute phase. Hypercytokinemia appeared to be responsible for the emergence of the symptoms of tsutsugamushi disease.     

Role of interleukin-6 in T-cell activation during primary and secondary infection with Listeria monocytogenes.

Injection of recombinant interleukin-6 (IL-6) into mice enhances recovery from infection with Listeria monocytogenes. In this study, the role of IL-6 during primary and secondary Listeria infection was further tested. Neutralization of IL-6 by polyclonal antibody exacerbated primary infection and significantly delayed gamma interferon production by cultured spleen cells. In contrast, administration of anti-IL-6 antibody at the time of secondary infection did not affect the recovery of mice from infection or gamma interferon production, showing that activated T cells are not dependent on IL-6.     

Role of gamma interferon and tumor necrosis factor alpha in resistance to Salmonella typhimurium infection.

In mice infected with a sublethal dose of Salmonella typhimurium, the injection of an anti-gamma interferon (IFN-gamma) monoclonal antibody increased bacterial proliferation in the spleen and led to death on day 7 or 8. Depletion of both CD4+ and CD8+ T cells with monoclonal antibodies in vivo had a much less marked effect during the first week of infection than the administration of anti-IFN-gamma antibodies, suggesting that cells other than T lymphocytes participate in the production of IFN-gamma at this time. Administration of anti-tumor necrosis factor alpha (TNF-alpha) antibodies to mice infected with a sublethal dose of S. typhimurium induced the same effect as anti-IFN-gamma antibodies, while the administration of both antibodies resulted in a synergistic interaction. When mice were infected with an avirulent strain of S. typhimurium and challenged on day 7 either with a virulent strain of S. typhimurium or with Listeria monocytogenes, their resistance to reinfection was slightly depressed by anti-IFN-gamma or anti-TNF-alpha antibodies given 1 day before challenge and much more strongly depressed by the simultaneous administration of both antibodies. Taken together, these results indicate that IFN-gamma and TNF-alpha play an essential role in acquired resistance during the early phase of S. typhimurium infection.     

Human tumor necrosis factor increases the resistance against Listeria infection in mice

The resistance in mice against Listeria infection was augmented by treatment with recombinant human tumor necrosis factor (TNF). To elucidate this phenomenon, we examined the effect of TNF on macrophage activation. TNF-treated macrophages had listericidal activity in vitro and superoxide anion production. In addition, macrophage migration was inhibited in the presence of TNF. Therefore, activation of macrophages by TNF was similar to activation by macrophage-activating factor or macrophage-migration-inhibitory factor.