Production of IL-1 and its receptor antagonist is regulated differently by IFN-gamma and IL-4 in human monocytes and alveolar macrophages

The Impact of Cytokines in Coronary Atherosclerotic Plaque: Current Therapeutic Approaches

Coronary atherosclerosis is a chronic pathological process that involves inflammation together with endothelial dysfunction and lipoprotein dysregulation. Experimental studies during the past decades have established the role of inflammatory cytokines in coronary artery disease, namely interleukins (ILs), tumor necrosis factor (TNF)-α, interferon-γ, and chemokines. Moreover, their value as biomarkers in disease development and progression further enhance the validity of this interaction. Recently, cytokine-targeted treatment approaches have emerged as potential tools in the management of atherosclerotic disease. IL-1β, based on the results of the CANTOS trial, remains the most validated option in reducing the residual cardiovascular risk. Along the same line, colchicine was also proven efficacious in preventing major adverse cardiovascular events in large clinical trials of patients with acute and chronic coronary syndrome. Other commercially available agents targeting IL-6 (tocilizumab), TNF-α (etanercept, adalimumab, infliximab), or IL-1 receptor antagonist (anakinra) have mostly been assessed in the setting of other inflammatory diseases and further testing in atherosclerosis is required. In the future, potential targeting of the NLRP3 inflammasome, anti-inflammatory IL-10, or atherogenic chemokines could represent appealing options, provided that patient safety is proven to be of no concern.

Are there differences in lipid peroxidation and immune biomarkers between major depression and bipolar disorder: Effects of melancholia, atypical depression, severity of illness, episode number, suicidal ideation and prior suicide attempts

BACKGROUND

There is evidence that major depression (MDD) and bipolar disorder (BD) are accompanied by activated immune & oxidative (I&O) pathways.

METHODS

To compare I&O biomarkers between MDD and BD we assessed serum levels of thiobarbituric acid reactive substances (TBARS; a lipid peroxidation marker), soluble interleukin-2 receptor (sIL-2R), sIL-6R, IL-α, sIL-1R antagonist (sIL-1RA), tumor necrosis factor receptor 60kDa/80kDa (sTNFR60/R80) in 114 MDD and 133 BD patients, and 50 healthy controls. We computed z-unit weighted indices reflecting the 5 cytokine receptor levels (zCytR), cell-mediated immunity (zCMI) and I&O pathways (zCMI+TBARS).

RESULTS

There are no significant differences in biomarkers between MDD and BD. BD/MDD with atypical features is characterized by increased sIL-6R and TBARS, whereas melancholia is associated with higher TBARS and lower sTNFR60 levels. Severity of illness, as measured with the Hamilton Depression Rating Scale, is correlated with increased sIL-6R, sTNFR80, TBARS, zCytR and zCMI+TBARS. The number of episodes the year prior to blood sampling is positively associated with sTNFR80, TBARS, zCMI, zCMI+TBARS, while number of hospitalizations is positively associated with sIL-1RA. Prior suicidal attempts are associated with increased sIL-1RA, IL-1α, zCMI, TBARS and zCMI+TBARS, while TBARS is associated with current suicidal ideation.

CONCLUSIONS

There are no I&O biomarker differences between MDD and BD. Atypical depression is associated with increased IL-6 trans-signaling and lipid peroxidation. Severity of depression, number of episodes and suicidal attempts are associated with activated I&O pathways. Increased TBARS is the single best predictor of BD/MDD, atypical depression, melancholia and current suicidal ideation.

Lipid Peroxidation and Immune Biomarkers Are Associated with Major Depression and Its Phenotypes, Including Treatment-Resistant Depression and Melancholia

To examine immune-inflammatory and oxidative (I&O) biomarkers in major depression (MDD) and its related phenotypes, we recruited 114 well-phenotyped depressed patients and 50 healthy controls and measured serum levels of interleukin (IL)-1α, soluble IL-1 receptor antagonist (sIL-1RA), soluble IL-2 receptor (sIL-2R), soluble IL-6 receptor (sIL-6R), soluble tumor necrosis factor receptor 60 and 80 kDa (sTNF-R1/R2), and thiobarbituric acid reactive substances (TBARS). Obtained results indicate that MDD is characterized by increased sIL-1RA, sTNF-R1, and TBARS concentrations. Melancholic depression is associated with increased sIL-6R but lowered IL-1α levels. A current episode of depression is accompanied by significantly increased sIL-6R compared to the remitted state. Treatment-resistant depression (TRD) is accompanied by increased sIL-6R and TBARS but lowered sTNF-R2 levels compared to non-TRD patients. These immune markers are not significantly correlated with Hamilton Depression Rating Scale (HDRS), Montgomery-Asberg Depression Scale (MADRS), number episodes, or age at onset. Our findings show that increased sIL-1RA, sTNF-R1, and TBARS levels may be trait markers of depression, while increased sIL-6R levels may be a state marker of melancholia and an acute phase of depression. MDD is accompanied by increased lipid peroxidation and simultaneous activation of immune pathways, and the compensatory anti-inflammatory reflex system (CIRS). TRD is characterized by highly increased oxidative stress and probably increased TNFα and IL-6 trans-signalling. Novel treatments for major depression should target oxidative stress pathways, while new treatments for TRD should primary target lipid peroxidation and also activated immune-inflammatory pathways.

Interaction Effects of Season of Birth and Cytokine Genes on Schizotypal Traits in the General Population

Literature suggests that the effect of winter birth on vulnerability to schizophrenia might be mediated by increased expression of proinflammatory cytokines due to prenatal infection and its inadequate regulation by anti-inflammatory factors. As the response of the immune system depends on genotype, this study assessed the interaction effects of cytokine genes and season of birth (SOB) on schizotypy measured with the Schizotypal Personality Questionnaire (SPQ-74). We searched for associations of IL1B rs16944, IL4 rs2243250, and IL-1RN VNTR polymorphisms, SOB, and their interactions with the SPQ-74 total score in a sample of 278 healthy individuals. A significant effect of the IL4 X SOB interaction was found, p = 0.007 and η² = 0.028. We confirmed this effect using an extended sample of 373 individuals. Homozygotes CC born in winter showed the highest SPQ total score and differed significantly from winter-born T allele carriers, p = 0.049. This difference was demonstrated for cognitive-perceptual and disorganized but not interpersonal dimensions. The findings are consistent with the hypothesis that the cytokine genes by SOB interaction can influence variability of schizotypal traits in the general population. The IL4 T allele appeared to have a protective effect against the development of positive and disorganized schizotypal traits in winter-born individuals.

Cross-species evidence for the role of interleukin-33 in depression risk

Extensive evidence highlights the role of inflammatory processes in major depressive disorder (MDD). However, most studies have examined a consistent set of inflammatory cytokines and there is evidence that other immune-derived products may play a role in MDD. In this article, we present data from 3 complimentary studies that support the role of a novel cytokine, interleukin-33 (IL-33), in depression risk. First, we show that a 2-SNP haplotype in the IL-33 gene (rs11792633 and rs7044343) moderated the link between women's history of childhood abuse and their history of recurrent MDD (rMDD), such that the link between childhood abuse and rMDD was stronger among women with fewer copies of the protective IL-33 CT haplotype. Second, linking these findings to differences in circulating cytokine levels, we show in a separate sample that those with a history of rMDD had higher peripheral levels of IL-33 and IL-1β compared with women with a single MDD episode or no history of MDD. Third, providing initial evidence of brain regions underlying these effects using archival rat brain tissue, we show that an acute stressor increased IL-33 expression in the paraventricular nucleus of the hypothalamus and, to a lesser extent, the prefrontal cortex, key brain regions underlying stress response and emotion regulation. These findings provide converging support for the potential role of IL-33 in risk for recurrent MDD. (PsycINFO Database Record

Smoking enhances the proinflammatory effects of nucleotides on cytokine release from human lung

Nucleotides have effects on immune cells which are complex but generally proinflammatory, and have been suggested to play a role in smoking-related lung diseases. However, there have been no studies directly measuring functional responses to nucleotides in human lungs taken from smokers. We used fragments of post mortem human lung from smokers and non-smokers, incubated them with a range of nucleotides (4–1000 µM) in the presence of lipopolysaccharide (LPS; 10 µg/ml) for 24 hours and measured cytokines (IL-1β, IFNγ, IL-17, TNFα, IL-6, IL-8, IL-2 and IL-10) in the supernatants using multiplex immunoassays. Although the basal cytokine levels in the smokers were generally higher in the smokers than the non-smokers, there were no significant differences in either the basal release or the LPS-stimulated release of any of the cytokines when lungs from smokers and non-smokers were compared. There were no significant effects of ATP, ADP, AMP, UTP, α,β-methylene-ATP, P¹, P⁴-diATP, 2-methylthio-ATP or Bz-ATP on the release of cytokines from the lungs. However, the stable ATP analogue ATPγS increased the release of IL-1β and IFNγ, and the effect was greatly increased in lungs from smokers. In non-smokers but not in smokers ATPγS increased the release of IL-17. Overall these results clearly demonstrate for the first time that in normal human lung a stable ATP analogue can enhance LPS-induced pro-inflammatory cytokine release, and that these effects are greatly altered by a prior history of smoking. This provides strong support for the suggestion that nucleotides are involved in the pathogenesis of smoking-related diseases.

IFN-γ-activated lymphocytes boost nitric oxide production in grass carp monocytes/macrophages

It is well known that IFN-γ is a prime activator of nitric oxide (NO) production by monocytes/macrophages in mammals and fish. In parallel, whether IFN-γ-activated lymphocytes are associated with NO production remains unclear. In this study, grass carp monocytes/macrophages and lymphocytes from head kidney were isolated and effects of recombinant grass carp IFN-γ (rgcIFN-γ) on NO releases by these two cell populations were determined. Results showed that rgcIFN-γ time- and dose-dependently increased NO production by monocytes/macrophages but not lymphocytes, which are consistent with the findings in mammals. Interestingly, rgcIFN-γ displayed a greater stimulation on NO production in the co-cultures of monocytes/macrophages and lymphocytes when compared with that in the culture of monocytes/macrophages alone. Furthermore, the media harvested from rgcIFN-γ-treated lymphocytes were effective in boosting NO release in monocytes/macrophages. These data suggest that secretions from rgcIFN-γ-treated lymphocytes may be involved in the NO release by monocytes/macrophages. To address this hypothesis, effect of rgcIFN-γ on the gene expression of inflammatory cytokines in grass carp lymphocytes was examined, showing that it consistently stimulated the mRNA expression of grass carp TNF-α and IL-1β but not IFN-γ. Furthermore, treatment of rgcIFN-γ combined with recombinant grass carp IL-1β (rgcIL-1β) induced a NO production by monocytes/macrophages, which was significantly higher than those induced by either cytokine alone. It provides the evidence that the cytokines secreted by the activated lymphocytes may facilitate the NO production by monocytes/macrophages. Taken together, our findings point out a new mechanism for the involvement of IFN-γ-activated lymphocytes in the NO production by monocytes/macrophages in fish. This knowledge not only strengthens the role of IFN-γ in immune system but also provides the evidence for the existence of a close relationship between lymphocytes and monocytes/macrophages in fish.

Sorafenib perpetuates cellular anticancer effector functions by modulating the crosstalk between macrophages and natural killer cells

Alternatively polarized macrophages (Mϕ) shape the microenvironment of hepatocellular carcinoma (HCC) and temper anticancer immune responses. We investigated if sorafenib alters the HCC microenvironment by restoring classical macrophage polarization and triggering tumor-directed natural killer (NK) cell responses. In vivo experiments were conducted with sorafenib (25 mg/kg)-treated C57BL/6 wildtype as well as hepatitis B virus (HBV) and lymphotoxin transgenic mice with and without HCC. Monocyte-derived Mϕ or tumor-associated macrophages (TAM) isolated from HCC tissue were treated with sorafenib (0.07-5.0 μg/mL) and cocultured with autologous NK cells. Mϕ and NK cell activation was analyzed by flow cytometry and killing assays, respectively. Cytokine and growth factor release was measured by enzyme-linked immunosorbent assay. Short-term administration of sorafenib triggered activation of hepatic NK cells in wildtype and tumor-bearing mice. In vitro, sorafenib sensitized Mϕ to lipopolysaccharide, reverted alternative Mϕ polarization and enhanced IL12 secretion (P = 0.0133). NK cells activated by sorafenib-treated Mϕ showed increased degranulation (15.3 ± 0.2% versus 32.0 ± 0.9%, P < 0.0001) and interferon-gamma (IFN-γ) secretion (2.1 ± 0.2% versus 8.0 ± 0.2%, P < 0.0001) upon target cell contact. Sorafenib-triggered NK cell activation was verified by coculture experiments using TAM. Sorafenib-treated Mϕ increased cytolytic NK cell function against K562, Raji, and HepG2 target cells in a dose-dependent manner. Neutralization of interleukin (IL)12 or IL18 as well as inhibition of the nuclear factor kappa B (NF-κB) pathway reversed NK cell activation in Mϕ/NK cocultures.

CONCLUSION

Sorafenib triggers proinflammatory activity of TAM and subsequently induces antitumor NK cell responses in a cytokine- and NF-κB-dependent fashion. This observation is relevant for HCC therapy, as sorafenib is a compound in clinical use that reverts alternative polarization of TAM in HCC. (HEPATOLOGY 2013;57:2358-2368).

Targeting IL-1 in depression

INTRODUCTION

Depression is associated with inflammation, Th1 and Th17 responses, oxidative and nitrosative stress (O&NS), autoimmune responses against neoantigenic determinants, and neuroprogression (i.e., neurodegeneration, impaired plasticity and reduced neurogenesis). These pathways involve increased monocytic activation and interleukin-1 (IL-1) levels.

AREAS COVERED

This review will highlight the putative role of IL-1 in depression and the potential use of IL-1 signaling blockade as a treatment of depression. Electronic databases, i.e., Scopus, PUBMED and Google Scholar were employed using keywords: depression, depressive-like, interleukin-1, and interleukin-1 receptor antagonist (IL-1RA).

EXPERT OPINION

Ample studies show that depression is accompanied by increased levels of IL-1 and IL-1RA, which attenuates the pro-inflammatory activities of IL-1. In some, but not all studies, antidepressant treatment decreased IL-1β levels. In translational models, IL-1β administration elicits depressive-like behaviors, neuroinflammation and neuroprogression, whereas treatment with IL-1RA yields antidepressant-like effects and attenuates neuroprogression. Anakinra, an IL-1RA, targets not only IL-1 signaling, but also Th1, Th17, O&NS and neuroprogressive pathways and therefore may be advanced to clinical Phase-II trials in depression due to medical conditions associated with an elevated IL-1/IL-1RA ratio.

Convergence of IL-1beta and VDR activation pathways in human TLR2/1-induced antimicrobial responses

Antimicrobial effector mechanisms are central to the function of the innate immune response in host defense against microbial pathogens. In humans, activation of Toll-like receptor 2/1 (TLR2/1) on monocytes induces a vitamin D dependent antimicrobial activity against intracellular mycobacteria. Here, we report that TLR activation of monocytes triggers induction of the defensin beta 4 gene (DEFB4), requiring convergence of the IL-1β and vitamin D receptor (VDR) pathways. TLR2/1 activation triggered IL-1β activity, involving the upregulation of both IL-1β and IL-1 receptor, and downregulation of the IL-1 receptor antagonist. TLR2/1L induction of IL-1β was required for upregulation of DEFB4, but not cathelicidin, whereas VDR activation was required for expression of both antimicrobial genes. The differential requirements for induction of DEFB4 and cathelicidin were reflected by differences in their respective promoter regions; the DEFB4 promoter had one vitamin D response element (VDRE) and two NF-κB sites, whereas the cathelicidin promoter had three VDREs and no NF-κB sites. Transfection of NF-κB into primary monocytes synergized with 1,25D3 in the induction of DEFB4 expression. Knockdown of either DEFB4 or cathelicidin in primary monocytes resulted in the loss of TLR2/1-mediated antimicrobial activity against intracellular mycobacteria. Therefore, these data identify a novel mechanism of host defense requiring the induction of IL-1β in synergy with vitamin D activation, for the TLR-induced antimicrobial pathway against an intracellular pathogen.

Molecular characterization, expression and functional analysis of goldfish (Carassius aurutus L.) interferon gamma

We report on the characterization and functional analysis of IFNgamma of the goldfish. Quantitative analysis indicated the highest expression of goldfish IFNgamma in the spleen, with lower expressions in brain, gill, kidney, heart, intestine and muscle. An increase in IFNgamma expression was observed in kidney leukocytes following stimulation with PHA, PolyI:C and during mixed leukocyte reaction. IFNgamma was expressed in different goldfish immune cell populations and this expression was upregulated in several of these populations following treatment of cells with recombinant goldfish TNFalpha-2. A recombinant form of goldfish IFNgamma (rgIFNgamma) was produced and functionally analyzed. The rgIFNgamma primed goldfish macrophages and neutrophils for enhanced respiratory burst responses and increased the phagocytic and nitric oxide responses of macrophages. Furthermore, treatment of goldfish macrophages with rgIFNgamma induced increased expression of several proinflammatory genes including TNFalpha-1, TNFalpha-2, IL-beta-1, IL-beta-2, IL-12-p35, IL-12-p40, RSAD-2 (=viparin), CXCL-8 (=IL-8), CCL-1, iNOS A and B and IFNgamma, and decreased the expression of TLR-3, while the expression of TGFbeta remained unchanged. Our results indicate that IFNgamma is a central proinflammatory cytokine of teleosts.

Diminished monocyte function in microfilaremic patients with lymphatic filariasis and its relationship to altered lymphoproliferative responses

Antigen-specific hyporesponsiveness to filarial antigens is a phenomenon observed in patent infection with lymph-dwelling filarial parasites of humans. This phenomenon has been attributed to a multitude of factors, one of which is altered monocyte function. To examine the role played by monocytes in filarial infection, we assessed the responses of monocytes obtained from normal and filarial parasite-infected individuals to both crude filarial antigen and purified recombinant filarial antigen WbSXP-1 and attempted to relate these to the altered lymphoproliferative responses seen in filarial infection. Monocytes from microfilaremic (MF) patients demonstrated an inability to respond to lipopolysaccharide compared to monocytes from endemic normal persons or from lymphedema patients. Indeed, interleukin 1beta (IL-1beta) production was severely limited, a finding that did not extend to monocyte responses to filarial antigens. Serum from MF patients reduced adherence and spreading of normal monocytes, a finding not seen with serum from the other clinical groups. Interestingly, there was a significant correlation between the production of IL-1beta and adherence. Moreover, the levels of spontaneous production of IL-1beta correlated with high levels of spontaneous secretion of IL-10. The effects observed were not a result of diminished viability or alteration in the expression of the cell surface markers CD14 and HLA-DR. These data suggest that monocyte function is dampened in MF patients, a finding which could alter lymphoproliferative responses during patent infection.

Inflammatory cytokines and antigen presenting cell activation

Immune responses are stimulated in response to threats against health. In animals, defense against infectious agents, particularly rapidly growing viruses and bacteria, requires an immediate response to limit growth and dissemination, and then stimulation of a more prolonged, specific immunity to prevent re-infection. The process by which animals meet the dual needs of an immediate response to danger and initiation of long-term protection is substantially influenced by inflammatory cytokines produced primarily by macrophages and professional antigen presenting cells (APCs). Inflammatory cytokines mobilize the immune system in response to danger and increase the efficiency of an immune response as effectors of APC function. Here we review the evidence for the involvement of inflammatory cytokines in immune induction and as mediators of APC activity, with a particular emphasis on swine and on the induction of immunity at mucosal surfaces. The vast majority of infections occur at mucosal surfaces of the enteric, respiratory and reproductive tracts, and induction of protective immunity at these sites is particularly challenging. Induction of immunity at mucosal surfaces of the small intestine is greatly facilitated by the oral adjuvant, cholera toxin (CT). CT potentiates inflammatory cytokine and costimulatory molecule expression in macrophages, and stimulates humoral and cell-mediated immune responses both locally and systemically. These observations are consistent with the hypothesis that activation of APCs is a key step in the induction of antigen-specific immunity, and that inflammatory cytokine expression is a hallmark of activated APC function. The efficacy of vaccine adjuvants, particularly in the context of mucosal immunity, may be determined by their ability to induce a controlled inflammatory response in gut-associated lymphoid tissue, characterized by the expression of various costimulatory molecules and inflammatory cytokines. Thus, elucidation of the patterns of inflammatory cytokine expression and features of APC activation will help to facilitate the rational development of more efficacious vaccines.

IFN-gamma downregulates interleukin-4 functional activity on monocytes by multiple mechanisms

Interleukin-4 (IL-4) has potent anti-inflammatory properties on monocytes and suppresses lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha) and IL-1beta production. Culture with interferon (IFN-gamma) alters human monocyte responses to IL-4 by multiple mechanisms. As previously published, IFN-gamma reduced IL-4-activated signal transducer and activator of transcription-6 (STAT-6). This correlated with an inability of IL-4 to suppress LPS-induced TNF-alpha but not IL-1beta production. A second mechanism, apparent some 48 h after exposure to IFN-gamma, involved a significant suppression of IL-4 receptor (IL-4R) expression at the cell surface, and this correlated with the loss of additional functional responses to IL-4, including IL-4-induced suppression of LPS-induced IL-1beta production. This study identified a further role of IFN-gamma on IL-4 responses, including reduced IL-4R surface expression by human monocytes. Increased release of soluble gammac from IFN-gamma-treated monocytes provides an additional mechanism by which IFN-gamma may control the functional activity of IL-4. This study characterizes further the opposing effects of the type 1 and type 2 cytokine regulatory systems.

Immunological circumvention of multiple organ metastases of multidrug resistant human small cell lung cancer cells by mouse-human chimeric anti-ganglioside GM2 antibody KM966

serum against SBC-3/DOX cells to a similar extent compared with parental SBC-3 cells. Pretreatment of human effector cells with various cytokines induced further enhancement of the KM966-dependent ADCC against SBC-3/DOX cells. Intravenous injection of SBC-3 or SBC-3/DOX cells into natural killer (NK) cell-depleted severe combined immunodeficient (SCID) mice developed metastases in multiple organs (liver, kidneys and lymph nodes). Interestingly, SBC-3/DOX cells produced metastases more rapidly than SBC-3 cells, suggesting more aggressive phenotype of SBC-3/DOX cells than their parental cells in vivo. Systemic treatment with KM966, given on days 2 and 7, drastically inhibited the formation of multiple-organ metastases produced by both SBC-3 and SBC-3/DOX cells, indicating that KM966 can eradicate metastasis by SCLC cells irrespective of MDR phenotype. These findings suggest that the mouse-human chimeric KM966 targets the GM2 antigen, and might be useful for the immunological circumvention of multiple-organ metastases of refractory SCLC.

Toll-like receptor 4-deficient mice have reduced bone destruction following mixed anaerobic infection

C3H/HeJ mice have an impaired ability to respond to lipopolysaccharide (LPS) due to a mutation in the gene that encodes Toll-like receptor 4 (TLR4). The effect of TLR4 deficiency on host responses to endodontic infections is unknown. In the present study, we compared periapical bone destruction, sepsis, and inflammatory cytokine production in LPS-hyporesponsive C3H/HeJ and wild-type control C3H/HeOuJ mice. The mandibular first molars of both strains were subjected to pulpal exposure and infection with a mixture of four anaerobic pathogens, Prevotella intermedia, Fusobacterium nucleatum, Streptococcus intermedius, and Peptostreptococcus micros. At sacrifice on day 21, TLR4-deficient C3H/HeJ mice had significantly reduced periapical bone destruction compared to wild-type C3H/HeOuJ mice (P < 0.001). The decreased bone destruction in C3H/HeJ correlated with reduced expression of the bone resorptive cytokines interleukin 1alpha (IL-1alpha) (P < 0.01) and IL-1beta (P < 0.05) as well as the proinflammatory cytokine IL-12 (P < 0.05). No significant differences were seen in the levels of gamma interferon, tumor necrosis factor alpha (TNF-alpha), or IL-10 between the two strains. The expression of IL-1alpha, IL-1beta, TNF-alpha, IL-10, and IL-12 were all significantly reduced in vitro in macrophages from both TLR4-deficient C3H/HeJ and C57BL/10ScNCr strains, compared to wild-type controls. Notably, the responses of TLR4-deficient macrophages to both gram-positive and gram-negative bacteria were similarly reduced. Neither C3H/HeJ nor C3H/HeOuJ mice exhibited orofacial abscess development or infection dissemination as determined by splenomegaly or cachexia. We conclude that intact TLR function mediates increased proinflammatory responses and bone destruction in response to mixed anaerobic infections.

Mechanisms of vaccine adjuvanticity at mucosal surfaces

The vast majority of pathogens invade via mucosal surfaces, including those of the intestine. Vaccination directly on these surfaces may induce local protective immunity and prevent infection and disease. Although vaccine delivery to the gut mucosa is fraught with obstacles, immunization can be enhanced using adjuvants with properties specific to intestinal immunity. In this review, we present three general mechanisms of vaccine adjuvant function as originally described by Freund, and we discuss these principles with respect to intestinal adjuvants in general and to the prototypical mucosal adjuvant, cholera toxin. The key property of intestinal adjuvants is to induce an immunogenic context for the presentation of the vaccine antigen. The success of oral vaccine adjuvants is determined by their ability to induce a controlled inflammatory response in the gut-associated lymphoid tissues, characterized by the expression of various costimulatory molecules and cytokines. An understanding of the specific molecular mechanisms of adjuvanticity in the gut will allow the rational development of safe and effective oral vaccines.

Interferons inhibit activation of STAT6 by interleukin 4 in human monocytes by inducing SOCS-1 gene expression

Interferons (IFNs) inhibit induction by IL-4 of multiple genes in human monocytes. However, the mechanism by which IFNs mediate this inhibition has not been defined. IL-4 activates gene expression by inducing tyrosine phosphorylation, homodimerization, and nuclear translocation of the latent transcription factor, STAT6 (signal transducer and activator of transcription-6). STAT6-responsive elements are characteristically present in the promoters of IL-4-inducible genes. Because STAT6 activation is essential for IL-4-induced gene expression, we examined the ability of type I and type II IFNs to regulate activation of STAT6 by IL-4 in primary human monocytes. Pretreatment of monocytes with IFN-beta or IFN-gamma, but not IL-1, IL-2, macrophage colony-stimulating factor, granulocyte/macrophage colony-stimulating factor, IL-6, or transforming growth factor beta suppressed activation of STAT6 by IL-4. This inhibition was associated with decreased tyrosine phosphorylation and nuclear translocation of STAT6 and was not evident unless the cells were preincubated with IFN for at least 1 hr before IL-4 stimulation. Furthermore, inhibition by IFN could be blocked by cotreatment with actinomycin D and correlated temporally with induction of the JAK/STAT inhibitory gene, SOCS-1. Forced expression of SOCS-1 in a macrophage cell line, RAW264, markedly suppressed trans-activation of an IL-4-inducible reporter as well as IL-6- and IFN-gamma-induced reporter gene activity. These findings demonstrate that IFNs inhibit IL-4-induced activation of STAT6 and STAT6-dependent gene expression, at least in part, by inducing expression of SOCS-1.

Presence and potent immunosuppressive role of interleukin-10 in malignant pleural effusion due to lung cancer

The presence and possible role of interleukin (IL)-10 were examined in malignant pleural effusion due to lung cancer. In 37 out of 55 cases examined, IL-10 was detectable in pleural effusion and the mean level with standard error was 62.1+/-12.1 pg/ ml. Spontaneous and lipopolysaccharide-induced production of anti-tumor cytokines such as IL-1beta and tumor necrosis factor (TNF)-alpha, by pleural macrophages, obtained from five patients with malignant pleurisy, were suppressed by IL-10. These findings suggest that IL-10 is present in the tumor-growing site and acts as a suppressive factor of local anti-tumor immunity in humans.

Role of macrophage cytokines in mucosal adjuvanticity

Delivery of protein antigens to the GALT can result in immunity or oral tolerance depending on the circumstances of the encounter. One mechanism by which mucosal adjuvants can affect these circumstances is by the induction of macrophage cytokines, including IL-1 and IL-12. These cytokines can directly affect the immune response by their effects on antigen-specific T cells and by the induction of IFN-gamma by T cells or NK cells. This IFN-gamma also activates macrophages to up-regulate MHC or costimulatory molecules and by further inducing IL-1 and IL-12. In effect, mucosal adjuvants function both directly and indirectly as activators of antigen presenting cells, resulting in stimulation of the immune response to coincidental antigens. Our studies in swine have shown CT is a potent mucosal adjuvant for CT-B. CT also increased IL-1 and IL-12 mRNA in cultured macrophages, especially after activation with IFN-gamma. The effect of CT on the secretion of bioactive IL-12 protein is currently being investigated. While the mucosal adjuvanticity of CT involves a variety of mechanisms, these findings suggest a role for the induction of the macrophage cytokines IL-1 and IL-12.

Interleukin-4 inhibits spontaneous sleep in rabbits

Proinflammatory cytokines, including interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha, are involved in sleep regulation. IL-4 is an antiinflammatory cytokine that inhibits proinflammatory cytokine production. The hypothesis that IL-4 should attenuate sleep was studied by determining the effects of IL-4 on rabbit spontaneous sleep. Thirty-six rabbits were used. Four doses of IL-4 (0.25, 2.5, 25, and 250 ng) were injected intracerebroventricularly during the rest (light) period. One dose of IL-4 (25 ng) was injected during the active (dark) cycle. Appropriate time-matched control injections of saline were done in the same rabbits on different days. The three highest doses of IL-4 significantly inhibited spontaneous non-rapid eye movement sleep if IL-4 was given during the light cycle. The highest dose of IL-4 (250 ng) also significantly decreased rapid eye movement sleep. On the other hand, IL-4 administered at dark onset had no effect on sleep. The sleep inhibitory properties of IL-4 provide additional evidence for the hypothesis that a brain cytokine network is involved in the regulation of physiological sleep.

IFNs Are Critical Regulators of IL-1 Receptor Antagonist and IL-1 Expression in Human Microglia

Because IL-1 is implicated in the pathogenesis of multiple sclerosis, and IFNs are known to alter disease course, we sought to determine whether IFNs can regulate the expression of IL-1 and IL-1R antagonist (IL-1Ra) in primary cultures of human microglia and astrocytes. We found that IL-1 and IL-1Ra are products of microglia but not astrocytes, and IFN-β and IFN-γ differentially modulate LPS- and cytokine-induced IL-1 and IL-1Ra. IFN-β induces IL-1Ra and augments LPS- and IL-4-induced IL-1Ra, but suppresses LPS- and IL-1-induced IL-1, shifting the balance toward the expression of the IL-1Ra. Like IFN-β, IFN-γ suppresses the expression of both LPS and IL-1-induced IL-1β. However, IFN-γ also suppresses the expression of IFN-β- and IL-4-induced IL-1Ra so that IFN-γ may enhance or suppress IL-1 activity depending on the other cytokines present. IL-4 has similar effects to IFN-β; however, other anti-inflammatory cytokines, did not regulate IL-1 or IL-1Ra in human microglia. Our data demonstrate a novel suppressive effect of IFN-β and IL-4 on IL-1 activity in human microglia, suggesting that IFN-β, a therapeutic agent used for multiple sclerosis, could have wider applications in the treatment of other central nervous system disorders in which IL-1 activity has been implicated in the pathogenesis.

Comparison of the regulations by Th2-type cytokines of the arachidonic-acid metabolic pathway in human alveolar macrophages and monocytes

The effects of a Th1-cell-associated cytokine (interferon-gamma [IFN-gamma]) and Th2-cell-associated cytokines (interleukin [IL]-4, IL-10, and IL-13) on prostaglandin (PG) production by human alveolar macrophages (AM) were examined in terms of four parameters: PGE2 synthesis, cyclooxygenase (COX) activity, and the protein and mRNA of two COX isozymes (COX-1 and COX-2). Lipopolysaccharide (LPS)-stimulated PGE2 synthesis and COX activity were suppressed significantly by IL-4, but were not affected significantly by IL-10, IL-13, or IFN-gamma. The LPS-dependent increase in COX activity in AM was attributable to COX-2 because it was inhibited by NS-398 (a COX-2-specific inhibitor). Western and Northern blot analyses revealed that the LPS-induced increases in COX-2 protein and mRNA were attenuated by IL-4 but hardly affected by IL-10, IL-13 or IFN-gamma. In contrast, COX-1 protein and mRNA were hardly detected in any of the AM preparations. In AM and monocytes from the same individuals, LPS induced the synthesis of large amounts of PGE2 and COX-2 mRNA in AM, and of lesser amounts in monocytes. IL-4, IL-10, and IL-13 significantly suppressed LPS-dependent PGE2 synthesis and COX-2 mRNA induction in monocytes, whereas only IL-4 significantly suppressed them in AM. Furthermore, 15-lipoxygenase mRNA was detectable only in monocytes incubated with LPS plus IL-4. These results suggest that IL-4 is a potent regulator of PG production in AM, and that regulation of the arachidonic-acid (AA) metabolic pathway in cells of monocyte-macrophage lineage by Th2-cell-associated cytokines depends on the stage of cell differentiation.

Modulation by interferon-gamma of the production and gene expression of IL-1 receptor antagonist in human neutrophils

In this report, we show that interferon-gamma (IFN-gamma) modulates the production of IL-1ra in activated human neutrophils. In lipopolysaccharide-stimulated cells, IFN-gamma increased the release of IL-1ra without modulating IL-1ra mRNA accumulation; under these conditions, IFN-gamma only marginally enhanced IL-1ra de novo synthesis, while IL-1ra was more efficiently secreted. In response to the formylated peptide, fMLP, neutrophils released small but significant amounts of IL-1ra, yet without an increase in IL-1ra mRNA over constitutive levels. Following IFN-gamma treatment, however, the fMLP-elicited IL-1ra production was greatly potentiated, and this was accompanied by a transient increased accumulation of IL-1ra mRNA. Finally, opsonized yeast particles were found to induce IL-1ra formation at late incubation times, and prior treatment of neutrophils with IFN-gamma moderately enhanced this response. Collectively, our results demonstrate that in neutrophils activated by different classes of agonists, IFN-gamma modulates the release of IL-1ra by acting through distinct mechanisms.

Human Th1 cells preferentially induce interleukin (IL)-1beta while Th2 cells induce IL-1 receptor antagonist production upon cell/cell contact with monocytes

The role of human T cells in the induction and regulation, upon cell/cell contact, of inflammatory responses by monocytic cells was investigated. The production of interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1Ra) by the monocytic THP-1 cell line was measured upon contact with either Th1 or Th2 cell clones. CD4+ T cell clones specific for purified protein derivative of Mycobacterium tuberculosis, predominantly Th1 [high interferon (IFN)-gamma and low IL-4 producers], or tetanus toxoid, predominantly Th2 (low IFN-gamma and high IL-4 producers), were generated. Cell membranes from antigen-stimulated, but not from resting T cell clones induced dose-dependent cytokine production by THP-1 cells. Th1 clones induced higher levels of IL-1beta production (484-806 pg/ml) than did Th2 clones (21-114 pg/ml). In contrast, Th1 clones induced lower levels of IL-IRa (0.9-7.8 ng/ml) than did Th2 clones (7.0-49.6 ng/ml). Similar results were obtained when T cell clones were activated by cross-linked CD3 and CD28. IL-1beta production by THP-1 cells correlated with IFN-gamma production by T cell clones but was unaffected by IFN-gamma neutralization. IL-1Ra production by THP-1 cells correlated with IL-4 production by T cells and was partially inhibited by IL-4 neutralization. These data indicate that activated Th1 and Th2 cells express different molecules on the cell surface able to induce distinct pro-inflammatory (IL-1beta) or anti-inflammatory (IL-1Ra) responses in monocytes. This differential induction of molecules with opposite effects on inflammation stresses the functional heterogeneity in CD4+ T cells.

Anti-ganglioside GM2 monoclonal antibody-dependent killing of human lung cancer cells by lymphocytes and monocytes

Ganglioside GM2 (GM2) frequently appears on the cell surface of human cancers of neuroendocrine origin. A mouse-human chimeric monoclonal antibody (mAb), KM966, against GM2 was previously found to promote the lysis of various cancer cells by human blood mononuclear cells (MNC). In this study, we analyzed the effector cells responsible for the chimeric mAb-dependent cell-mediated cytotoxicity (ADCC) against small cell lung cancer (SCLC) cells and examined the enhancing effect of various cytokines on the ADCC activity. The ADCC activity was assessed by 4-h 51Cr release assay. Highly purified lymphocytes (> 99%) and monocytes (> 90%) were separated by centrifugal elutriation from peripheral blood MNC of the same healthy donor. KM966 induced lysis of SCLC cells mediated by both lymphocytes and monocytes to similar extents, in a dose-dependent manner. Pretreatment of lymphocytes with various cytokines [interleukin (IL)-2, IL-12 and interferon-gamma] and that of monocytes with macrophage-colony-stimulating factor significantly augmented the killer activity against SCLC cells in the presence of KM966 mAb. KM966 was also effective for the lysis of non-small cell lung cancer cells in direct proportion to the GM2 expression levels. These findings suggest that combined treatment of KM966 mAb with cytokines may be therapeutically useful for in vivo killing of lung cancer cells expressing GM2 through the ADCC reaction.

Graft-versus-host disease and the Th1/Th2 paradigm

Graft-versus-host disease (GVHD) is the major complication after allogeneic bone marrow transplantation (BMT) and is initiated by alloreactive donor T cells recognizing foreign histocompatibility antigens of the host. There is now substantial experimental and clinical evidence to implicate a dysregulation of cytokine networks as a primary cause for the induction and maintenance of GVHD. In this article, current knowledge of the involvement of cytokines in GVHD is reviewed. The balance between type 1 cytokines (interleukin-2, interferon-gamma) and type 2 cytokines (interleukin-4, interleukin-10) is hypothesized to govern the extent to which a cell-mediated immune response and a systemic inflammatory response develop after allogeneic BMT. Because type 2 cytokines can inhibit the production of the proinflammatory cytokines interleukin-1 and tumor necrosis factor-alpha, a type 1 to type 2 shift in the initial response of donor T cells to host alloantigens may interrupt the cytokine cascade after allogeneic BMT and may offer a new approach to the prevention and treatment of acute GVHD. Interventions to specifically eliminate or modify the response of donor T cells to alloantigens in order to reduce GVHD may obviate the need for T cell depletion in clinical BMT and thus avoid the increased risk of relapse of malignancy and impairment of donor cell engraftment.

Regulatory effects of endogenous interleukin-1 receptor antagonist protein in immunoglobulin G immune complex-induced lung injury

IL-1 receptor antagonist (IL-1Ra) has regulatory effects on IL-1 activity both in vitro and in vivo. In the IgG immune complex model of lung injury in rats, exogenously administered human IL-1Ra suppressed neutrophil recruitment and ensuing lung injury. In this study, we sought to determine if endogenous rat IL-1Ra might regulate this lung-inflammatory response. By Northern blot analysis of lung mRNA and Western analysis of bronchoalveolar lavage (BAL) fluids, rat IL-1Ra expression was found to increase during development of inflammation in IgG immune complex-mediated alveolitis. By immunostaining, alveolar macrophages and recruited neutrophils were the apparent sources of IL-1Ra. In vivo blocking of endogenous IL-1Ra resulted in a 53% increase in lung vascular permeability and a 180% increase in BAL fluid neutrophils. In companion studies, a significant increase in IL-1beta was found, whereas no significant change in TNF-alpha activity was observed. Whereas the in vivo regulatory effects of IL-1R appear to be limited to IL-1beta, IL-10 regulates both IL-1beta and TNF-alpha in this model, reflected by a 48% increase in BAL IL-1beta in rats treated with anti-IL-10. These findings suggest that IL-1Ra is an intrinsic regulator of inflammatory injury after deposition of IgG immune complexes and that it regulates production of IL-1beta.