Interleukin-12

Review article: latent tuberculosis in patients with inflammatory bowel diseases receiving immunosuppression-risks, screening, diagnosis and management

BACKGROUND

One quarter of the world's population has latent tuberculosis infection (LTBI). Systemic immunosuppression is a risk factor for LTBI reactivation and the development of active tuberculosis. Such reactivation carries a risk of significant morbidity and mortality. Despite the increasing global incidence of inflammatory bowel disease (IBD) and the use of immune-based therapies, current guidelines on the testing and treatment of LTBI in patients with IBD are haphazard with a paucity of evidence.

AIM

To review the screening, diagnostic practices and medical management of LTBI in patients with IBD.

METHODS

Published literature was reviewed, and recommendations for testing and treatment were synthesised by experts in both infectious diseases and IBD.

RESULTS

Screening for LTBI should be performed proactively and includes assessment of risk factors, an interferon-gamma releasing assay or tuberculin skin test and chest X-ray. LTBI treatment in patients with IBD is scenario-dependent, related to geographical endemicity, travel and other factors. Ideally, LTBI therapy should be used prior to immune suppression but can be applied concurrently where urgent IBD medical treatment is required. Management is best directed by a multidisciplinary team involving gastroenterologists, infectious diseases specialists and pharmacists. Ongoing surveillance is recommended during therapy. Newer LTBI therapies show promise, but medication interactions need to be considered. There are major gaps in evidence, particularly with specific newer therapeutic approaches to IBD.

CONCLUSIONS

Proactive screening for LTBI is essential in patients with IBD undergoing immune-suppressing therapy and several therapeutic strategies are available. Reporting of real-world experience is essential to refining current management recommendations.

Cytokines in Abdominal Aortic Aneurysm: Master Regulators With Clinical Application

Abdominal aortic aneurysm (AAA) is a potentially life-threatening disorder with a mostly asymptomatic course where the abdominal aorta is weakened and bulged. Cytokines play especially important roles (both positive and negative) among the molecular actors of AAA development. All the inflammatory cascades, extracellular matrix degradation and vascular smooth muscle cell apoptosis are driven by cytokines. Previous studies emphasize an altered expression and a changed epigenetic regulation of key cytokines in AAA tissue samples. Such cytokines as IL-6, IL-10, IL-12, IL-17, IL-33, IL-1β, TGF-β, TNF-α, IFN-γ, and CXCL10 seem to be crucial in AAA pathogenesis. Some data obtained in animal studies show a protective function of IL-10, IL-33, and canonical TGF-β signaling, as well as a dual role of IL-4, IFN-γ and CXCL10, while TNF-α, IL-1β, IL-6, IL-12/IL-23, IL-17, CCR2, CXCR2, CXCR4 and the TGF-β noncanonical pathway are believed to aggravate the disease. Altogether data highlight significance of cytokines as informative markers and predictors of AAA. Pathologic serum/plasma concentrations of IL-1β, IL-2, IL-6, TNF-α, IL-10, IL-8, IL-17, IFN-γ, and PDGF have been already found in AAA patients. Some of the changes correlate with the size of aneurysms. Moreover, the risk of AAA is associated with polymorphic variants of genes encoding cytokines and their receptors: CCR2 (rs1799864), CCR5 (Delta-32), IL6 (rs1800796 and rs1800795), IL6R (rs12133641), IL10 (rs1800896), TGFB1 (rs1800469), TGFBR1 (rs1626340), TGFBR2 (rs1036095, rs4522809, rs1078985), and TNFA (rs1800629). Finally, 5 single-nucleotide polymorphisms in gene coding latent TGF-β-binding protein (LTBP4) and an allelic variant of TGFB3 are related to a significantly slower AAA annual growth rate.

Correlation between Cerebrospinal Fluid IL-12 Levels and Severity of Encephalopathy in Children

The roles of cytokines in the cerebrospinal fluid (CSF) of patients with acute encephalopathy remain unclear and controversial. In this study, the profiles of 26 cytokines and others were determined in 17 children with infection-associated neurological complications. Interleukin (IL)-12 levels were found to be high in a few of the patients. A comparison of the IL-12 levels in the CSF of patients demonstrated that IL-12 (p70) is almost always increased in those with encephalopathy. Levels of IL-12 in the CSF were highly correlated with the levels of PDGF-bb and IL-RA. IL-12 levels were found to be weakly correlated with IFN-γ levels, and strongly correlated with VEGF levels. These results demonstrate that IL-12 levels may affect the clinical symptoms of pediatric patients with encephalopathy.

SCIMP is a transmembrane non-TIR TLR adaptor that promotes proinflammatory cytokine production from macrophages

Danger signals activate Toll-like receptors (TLRs), thereby initiating inflammatory responses. Canonical TLR signalling, via Toll/Interleukin-1 receptor domain (TIR)-containing adaptors and proinflammatory transcription factors such as NF-κB, occurs in many cell types; however, additional mechanisms are required for specificity of inflammatory responses in innate immune cells. Here we show that SCIMP, an immune-restricted, transmembrane adaptor protein (TRAP), promotes selective proinflammatory cytokine responses by direct modulation of TLR4. SCIMP is a non-TIR-containing adaptor, binding directly to the TLR4-TIR domain in response to lipopolysaccharide. In macrophages, SCIMP is constitutively associated with the Lyn tyrosine kinase, is required for tyrosine phosphorylation of TLR4, and facilitates TLR-inducible production of the proinflammatory cytokines IL-6 and IL-12p40. Point mutations in SCIMP abrogating TLR4 binding also prevent SCIMP-mediated cytokine production. SCIMP is, therefore, an immune-specific TLR adaptor that shapes host defence and inflammation.

Toll-like receptors engage TIR domain-containing adaptors to control proinflammatory gene expression in response to pathogens and tissue damage. Here the authors show that the non-TIR domain-containing transmembrane protein SCIMP is a previously unrecognized TLR adaptor expressed by macrophages.

Inflammatory Biomarkers Profile as Microenvironmental Expression in Keratoconus

Keratoconus is a degenerative disorder with progressive stromal thinning and transformation of the normal corneal architecture towards ectasia that results in decreased vision due to irregular astigmatism and irreversible tissue scarring. The pathogenesis of keratoconus still remains unclear. Hypotheses that this condition has an inflammatory etiopathogenetic component apart from the genetic and environmental factors are beginning to escalate in the research domain. This paper covers the most relevant and recent published papers regarding the biomarkers of inflammation, their signaling pathway, and the potentially new therapeutic options in keratoconus.

Efficacy and safety of ustekinumab treatment in elderly patients with psoriasis

The ratio of the elderly among psoriasis patients has been increasing. However, satisfactory long-term management of psoriasis for the elderly is challenging because of the more frequent presence of comorbidities, and the higher risk of adverse events from systemic therapeutic agents than younger patients. The use of ustekinumab (UST) appears to be an appropriate systemic treatment because it is considered less likely to cause adverse events than other systemic treatments, as well as necessitating fewer hospital visits. Our retrospective study aimed to evaluate the efficacy and safety profile of UST in elderly patients with psoriasis. The study included 24 patients aged over 65 years (range, 65-88 years; mean, 73.1 years) with moderate to severe plaque psoriasis with impaired quality of life. Efficacy and safety were assessed over a 1-year period using the Psoriasis Area and Severity Index (PASI) and the Dermatology Live Quality Index (DLQI). The efficacy was evaluated by the proportion of subjects who achieved ≥75% reduction in PASI score (PASI 75). PASI 75 responses were 56.5% at week 16, 59.1% at week 28, and 60.0% at week 52. None of the patients developed any serious infection during the 1-year treatment. The mean DLQI score at weeks 0, 16, 28, and 52 was 7.8 ± 6.0, 2.5 ± 3.4, 1.4 ± 1.7, and 1.2 ± 1.7, respectively. UST showed sufficient efficacy for elderly patients with psoriasis without any serious infection over the 1-year treatment. Our results suggest that UST is the preferable agent for the treatment of elderly patients with psoriasis.

Collaborating with the enemy: function of macrophages in the development of neoplastic disease

Due to the profile of released mediators (such as cytokines, chemokines, growth factors, etc.), neoplastic cells modulate the activity of immune system, directly affecting its components both locally and peripherally. This is reflected by the limited antineoplastic activity of the immune system (immunosuppressive effect), induction of tolerance to neoplastic antigens, and the promotion of processes associated with the proliferation of neoplastic tissue. Most of these responses are macrophages dependent, since these cells show proangiogenic properties, attenuate the adaptive response (anergization of naïve T lymphocytes, induction of Treg cell formation, polarization of immune response towards Th2, etc.), and support invasion and metastases formation. Tumor-associated macrophages (TAMs), a predominant component of leukocytic infiltrate, "cooperate" with the neoplastic tissue, leading to the intensified proliferation and the immune escape of the latter. This paper characterizes the function of macrophages in the development of neoplastic disease.

A WKYMVm-containing combination elicits potent anti-tumor activity in heterotopic cancer animal model

The development of efficient anti-cancer therapy has been a topic of intense interest for several decades. Combined administration of certain molecules and immune cells has been shown to be an effective form of anti-cancer therapy. Here, we examined the effects of administering an immune stimulating peptide (WKYMVm), 5-fluoro-uracil (5-FU), and mature dendritic cells (mDCs) against heterotopic cancer animal model. Administration of the triple combination strongly reduced tumor volume in CT-26-inoculated heterotopic cancer animal model. The induced anti-tumor activity was well correlated with FAS expression, caspase-3 activation, and cancer cell apoptosis. The triple combination treatment caused recruitment of CD8 T lymphocytes and natural killer (NK) cells into the tumor. The production of two cytokines, IFN-γ and IL-12, were strongly stimulated by administration of the triple combination. Depletion of CD8 T lymphocytes or NK cells by administration of anti-CD8 or anti-asialoGM1 antibody inhibited the anti-tumor activity and cytokine production of the triple combination. The triple combination strongly inhibited metastasis of colon cancer cells in a heterotopic cancer animal model as well as in a metastatic cancer animal model, and enhanced the survival rate of the mice model. Adoptive transfer of CD8 T lymphocytes and NK cells further increased the survival rate. Taken together, we suggest that the use of triple combination therapy of WKYMVm, 5-FU, and mDCs may have implications in solid tumor and metastasis treatment.

Impaired TLR-2 expression and TLR-2-mediated cytokine secretion in macrophages from patients with atopic dermatitis

BACKGROUND

In many patients with atopic dermatitis (AD), the disease is complicated by their enhanced susceptibility to bacterial skin infections, especially with Staphylococcus aureus. The pattern recognition receptor toll-like receptor (TLR)-2 recognizes components of S. aureus, for example, lipoteichoic acid (LTA) and peptidoglycan (PGN) and, therefore, might be crucial in the pathogenesis and flare-ups of AD.

OBJECTIVE

To investigate TLR-2 expression and cytokine secretion in macrophages from patients with AD compared to healthy controls upon TLR-2 stimulation with PGN, LTA and Pam3Cys.

METHODS

Macrophages were cultivated from highly purified peripheral blood monocytes of AD patients and nonatopic healthy controls and stimulated with PGN, LTA and Pam3Cys in a time and dose-dependent manner. Afterwards, TLR-2 expression and cytokine secretion were measured on protein and mRNA level. TLR-1 and TLR-6 expression were investigated on the mRNA level. Immunohistochemical stainings from punch biopsies were performed to investigate TLR-2 expression in skin macrophages.

RESULTS

We could clearly show that macrophages from patients with AD expressed significantly less TLR-2, whereas the expression pattern of TLR-1 and TLR-6 were not altered. Macrophages had a reduced capacity to produce pro-inflammatory cytokines such as IL-6, IL-8 and IL-1beta after stimulation with TLR-2 ligands.

CONCLUSION

Our findings clearly show an impaired TLR-2 expression and functional differences of TLR-2-mediated effects on macrophages of AD patients compared to healthy controls which might contribute to the enhanced susceptibility to skin infections with S. aureus in AD.

Dysregulation of toll-like receptor-2 (TLR-2)-induced effects in monocytes from patients with atopic dermatitis: impact of the TLR-2 R753Q polymorphism

BACKGROUND

Atopic dermatitis (AD) is often complicated by an enhanced susceptibility to bacterial skin infections, especially with Staphylococcus aureus. Toll-like receptors (TLR), especially TLR-2 recognizes cell wall components of S. aureus, e.g. lipoteichoic acid (LTA) and peptidoglycan (PGN). A heterozygous TLR-2 R753Q polymorphism occurs in a frequency of 11.5% in adult AD patients and has been shown to be associated with a severe phenotype of AD.

METHODS

The aim of this study was to investigate the impact of TLR-2 agonists (LTA, PGN and Pam3Cys) on cytokine production in human monocytes from AD patients with the TLR-2 R753Q polymorphism compared with that of AD patients with 'wild type' TLR-2 and control individuals to elucidate the functional role of the TLR-2 R753Q polymorphism.

RESULTS

Monocytes from AD patients with the TLR-2 R753Q mutation produced significantly more IL-6 and IL-12 compared with that of AD patients with nonmutated TLR-2 upon stimulation with TLR-2 agonists.

CONCLUSION

We show for the first time functional differences in TLR-2 responsiveness of monocytes from AD patients with the TLR-2 R753Q mutation compared with wild type AD patients in a ligand-dependent manner.

CLINICAL IMPLICATION

Our data support the emerging concept that AD patients have a dysbalance in innate and acquired immunity. TLR-2 may be essential in the pathogenesis and maintenance of AD and may be involved in the enhanced susceptibility to skin infections with S. aureus and in a higher inflammatory response in patients with AD carrying the TLR-2 polymorphism.

Apoptotic cells protect mice against lipopolysaccharide-induced shock

LPS is a main causative agent of septic shock. There is a lack of effective therapies. In vitro studies have shown that uptake of apoptotic cells actively inhibits the secretion by activated macrophages (Mphi) of proinflammatory mediators such as TNF-alpha and that such uptake increases the antiinflammatory and immunosuppressive cytokine TGF-beta. We therefore investigated the protective effect of apoptotic cells against LPS-induced endotoxic shock in mice. The current report is the first study to demonstrate that administration of apoptotic cells can protect mice from LPS-induced death, even when apoptotic cells were administered 24 h after LPS challenge. The beneficial effects of administration of apoptotic cells included 1) reduced circulating proinflammatory cytokines, 2) suppression of polymorphonuclear neutrophil infiltration in target organs, and 3) decreased serum LPS levels. LPS can quickly bind to apoptotic cells and these LPS-coated apoptotic cells can be recognized and cleared by Mphi in a CD14/thrombospondin/vitronectin receptor-dependent manner, accompanied with suppression of TNF-alpha and enhancement of IL-10 expression by LPS-activated Mphi. Apoptotic cells may therefore have therapeutic potential for the treatment of septic shock.

Engineered recombinant ovomucoid third domain can modulate allergenic response in Balb/c mice model

IgE-mediated allergic reactions to egg white are a serious health problem and ovomucoid being the dominant egg white allergen has been on focus in the past decade. Engineered hypoallergens with reduced reactivity for IgE antibodies are being examined to modulate the allergic response and develop prophylactic allergen vaccines. In this study, we evaluated the immunomodulatory effect of a genetic variant of the third domain of ovomucoid (GMFA) which showed reduced IgE binding with egg allergic patient's sera in comparison to the native form of the third domain of ovomucoid (DIII) in a murine model system. Balb/c mice were injected intraperitoneally with DIII and GMFA antigens. Allergen-specific serum IgG, IgG1, IgG2a, and IgE responses were evaluated using enzyme-linked immunosorbent assay. Splenocyte cytokine levels in the medium of the cultured cells were examined by ELISA and levels of IL-4, INF-gamma, and IL-12 (p70) cytokines were quantified. Neutralization with anti-IL-12 monoclonal antibody was assayed and cytokine levels with respect to GMFA mutant antigen stimulation were measured. GMFA mutant form was found to have significantly reduced levels of specific IgE when compared to the DIII suggesting a mutation-induced abrogation of the IgE binding epitope in mice. The increase in IgG2a levels in GMFA together with the decline of IgE and IgG1 points to a shift from a Th2 response to a Th1 dominated response. The cytokine profile showed a modulation of anti-allergic Th1 phenotype in GMFA from a proallergic Th2 response observed with DIII. Low levels of IL-4 and increased levels of INF-gamma and IL-12 were observed and anti-IL-12 monoclonal antibody restored the levels of IL-4 and suppressed levels of INF-gamma and IL-12 in the GMFA sensitized group. These results indicate that GMFA has a marked suppressive effect on the allergic response of ovomucoid and caused a shift towards a Th1 pathway, thereby modulating the Th1/Th2 cytokine balance and could be used as a potential hypoallergenic candidate for allergen-immunotherapy in the treatment of egg white allergy.

Association between nucleated red blood cells in blood and the levels of erythropoietin, interleukin 3, interleukin 6, and interleukin 12p70

The appearance of nucleated red blood cells (NRBC) in the circulation is associated with a variety of severe diseases, and indicates a relatively poor prognosis. Whether a malfunction of the bone marrow leads to this phenomenon is as unknown as the possible role that cytokines could play in this process. We analyzed erythropoietin, interleukin (IL)-3, IL-6, and IL-12p70 in the blood of 301 patients with circulating NRBCs. Two hundred fifty NRBC-negative patients served as controls. Multiple logistic regression revealed a significant association between the appearance of NRBCs in the blood and erythropoietin (odds ratio, 1.017; 95% confidence limits, 1.007-1.027; P < 0.001), IL-3 (odds ratio, 1.293; 95% confidence limits, 1.180-1.417; P < 0.001), IL-6 (odds ratio, 1.138; 95% confidence limits, 1.016-1.275; P < 0.05), and age (odds ratio, 1.019; 95% confidence limits, 1.009-1.030; P < 0.001), respectively. Gender and IL-12p70 were not significantly associated with the appearance of NRBC in the blood. To estimate the RBC production in the bone marrow, the increase in the reticulocyte concentration in blood was measured. The reticulocyte concentration in NRBC-positive patients was 69 +/- 2/nL, which was significantly higher than in NRBC-negative patients (60 +/- 2/nL; P < 0.01). Taken together, NRBC could be a marker that sums up hypoxic and inflammatory injuries. Thus, generally, the appearance of NRBC in blood is a valid parameter to identify patients at high mortal risk. Moreover, the increased number of reticulocytes in the blood of NRBC-positive patients may indicate that the appearance of NRBC is not associated with disturbed bone marrow function as far as the erythropoiesis is concerned.

Isolation and characterization of a novel immunomodulatory alpha-glucan-protein complex from the mycelium of Tricholoma matsutake in basidiomycetes

Tricholoma matsutake, a high-class edible mushroom in Japan, has been reported to have excellent biological activities, but difficulty in cultivating the fruit bodies and limited bulk availability have restricted detailed studies. We have developed a method of culturing in tanks, enabling the bulk supply of the mycelia. The preparation (CM6271) exerts modulative effects on the immune competence of mice and rats. In this study, a sodium hydroxide extract of CM6271 was defatted followed by fractionation with a combination of ion exchange chromatography and gel filtration in order to identify the components involved in the expression of the activity, and a single peak fraction (MPG-1) was obtained with reversed phase chromatography. MPG-1 was a glycoprotein (sugar:protein ratio, 94.3:5.7) with a relative molecular mass of 360 kDa, and the sugar moiety contained about 90% glucose. NMR spectra and methylation analysis revealed that the alpha-1,4-linkage was the predominant glucan linkage with alpha-1,6- and alpha-1,2-linkages in the minority. The amino acid composition in the protein moiety was rich in glutamine, alanine, asparagine, leucine, glycine, valine, serine, threonine, isoleucine, and proline. MPG-1 was resistant to degradation with amylase or protease. The oral administration of MPG-1 promoted, in a dose-dependent manner, the recovery of the mouse natural killer cell activity and serum IL-12 level that had been reduced by the loading of restraint stress. The dose of MPG-1 (25 mg/kg) required for the expression of the effect decreases to 1/12 of that of CM6271 (300 mg/kg). Furthermore, MPG-1 formed a complex with TGF-beta1 in vitro, modulating the biological activity of TGF-beta1 by binding to its active form. These results indicate that the mycelium of T. matsutake contains a novel alpha-glucan-protein complex with immunomodulatory activities.

The effects of thyroid hormones on circulating markers of cell-mediated immune response, as studied in patients with differentiated thyroid carcinoma before and during thyroxine withdrawal

OBJECTIVE

To address the influence of thyroid hormones on circulating markers of cell-mediated immune response in an in vivo human model.

SUBJECTS AND DESIGN

Twenty-two patients with stage I differentiated thyroid carcinoma were studied on the last day of thyroxine suppressive treatment, 4-7 days after withdrawal, and the day before whole body scanning. Three patients were excluded because of residual disease. Twenty euthyroid individuals served as controls. Serum thyrotrophin and thyroid hormones were measured by an immunometric assay, circulating cytokines by enzyme-linked immuno-sorbent assay and lymphoid populations by flow cytometry.

RESULTS

Thyroid function in patients changed from subclinical or mild hyperthyroidism at the first visit, to a situation of normal circulating levels of free thyroxine and triiodothyronine at the second, ending in a state of overt hypothyroidism. Thyroxine suppressive treatment in patients increased serum interleukin-18 concentrations (IL-18, mean+/-s.d., 280+/-122 vs 183+/-106 pg/ml, F = 3.192, P = 0.029), soluble interleukin-2 receptor levels (sIL-2R, 4368+/-1480 vs 2564+/-846 pg/ml, F = 21.324, P < 0.001), and the percentage of natural killer (NK) cells in peripheral blood (15.9+/-8.6 vs 10.5+/-3.6%, F = 4.977, P = 0.004) compared with controls. After thyroxine withdrawal, serum levels of IL-18, sIL-2R and the percentage of NK cells decreased progressively.

CONCLUSION

Our present results suggest that thyroid hormones modulate the cell-mediated immune response in humans.

Murine oviduct epithelial cell cytokine responses to Chlamydia muridarum infection include interleukin-12-p70 secretion

Epithelial cells play an important role in host defense as sentinels for invading microbial pathogens. Chlamydia trachomatis is an intracellular bacterial pathogen that replicates in reproductive tract epithelium. Epithelial cells lining the reproductive tract likely play a key role in triggering inflammation and adaptive immunity during Chlamydia infections. For this report a murine oviduct epithelial cell line was derived in order to determine how epithelial cells influence innate and adaptive immune responses during Chlamydia infections. As expected, oviduct epithelial cells infected by Chlamydia muridarum produced a broad spectrum of chemokines, including CXCL16, and regulators of the acute-phase response, including interleukin-1alpha (IL-1alpha), IL-6, and tumor necrosis factor alpha. In addition, infected epithelial cells expressed cytokines that augment gamma interferon (IFN) production, including IFN-alpha/beta and IL-12-p70. To my knowledge this is the first report of a non-myeloid/lymphoid cell type making IL-12-p70 in response to an infection. Equally interesting, infected epithelial cells significantly upregulated transforming growth factor alpha precursor expression, suggesting a mechanism by which they might play a direct role in the pathological scarring seen as a consequence of Chlamydia infections. Data from these in vitro studies predict that infected oviduct epithelium contributes significantly to host innate and adaptive defenses but may also participate in the immunopathology seen with Chlamydia infections.

Immobilization of rolling NK cells on platelet-borne P-selectin under flow by proinflammatory stimuli, interleukin-12, and leukotriene B4

Recruitment of leukocytes from bloodstream to extrahematic sites is tightly regulated by a variety of adhesion molecules that are expressed on the leukocytes and the vessel walls. In this manuscript, we describe the interactions between natural killer (NK) cells and activated, autologous platelets under physiologic flow. We found that surface-adherent human platelets are capable of recruiting human NK cells from flow and that this recruitment is characterized by an initial tethering followed by a rolling phase. Both phases were dependent on the adhesion molecule P-selectin and its counter-ligand on the NK cells (P-selectin glycoprotein ligand 1). Activation of rolling NK cells with inflammatory mediators commonly found in atherosclerotic plaques (interleukin-12 and leukotriene B4) causes immediate cessation of the rolling process and conversion to stationary adhesion. Blocking antibodies to the adhesion molecules membrane-activated complex-1 and leukocyte function antigen-1 inhibited this conversion. Our data suggest that platelets deposited at sites of vascular injury may provide an alternative substrate to endothelial cells for initial recruitment of NK cells to the vessel wall. This may result in extravasation of the NK cells if the appropriate chemotactic signal is applied. These data implicate the P-selectin and integrin family of adhesion molecules in the recruitment of NK cells to atherosclerotic sites.

Truncated thioredoxin: physiological functions and mechanism

Human cytosolic thioredoxin (Trx), which is the 12-kDa protein disulfide reductase with the Cys-Gly-Pro-Cys active site and a key component of cellular redox biochemistry and regulation, acts as cocytokine upon leaderless secretion. A 10-kDa C-terminally truncated thioredoxin (Trx80) comprising the 80 or 84 N-terminal amino acids is also secreted and present in plasma, where it originally was purified and identified as eosinophilic cytotoxicity enhancing factor. Recombinant Trx80 was discovered to be a potent mitogenic cytokine that stimulates growth of resting human peripheral blood mononuclear cells (PBMC) in a synthetic medium, an effect that Trx lacks. Trx80 is very different from Trx because it is a dimer lacking reductase activity and the cytokine activity is not dependent on the Cys residues of the Trx active-site motif. The primary targets of Trx80 in PBMC are monocytes that are activated to proliferate and increase expression of CD14, CD40, CD54, and CD86. Trx80 induces secretion of interleukin (IL)-12 in CD40+ monocytes from PBMC. Trx80 and IL-2 together were strongly synergistic to induce secretion of interferon-gamma in PBMC. Trx80 is a potent cytokine for monocytes directing the immune system to a Th1 response via IL-12 production.

Induction of an antitumor immunological response by an intratumoral injection of dendritic cells pulsed with genetically engineered Semliki Forest virus to produce interleukin-18 combined with the systemic administration of interleukin-12

OBJECT

The aim of this study was to investigate further immunogene treatment of malignant brain tumor to improve its therapeutic efficacy.

METHODS

Intratumoral dendritic cells pulsed with Semliki Forest virus (SFV)-interleukin-18 (IL-18) and/or systemic IL-12 were injected into mice bearing the B16 brain tumor. To study the immune mechanisms involved in tumor regression, we monitored the growth of implanted B16 brain tumor cells in T cell-depleted mice and IFNgamma-neutralized mice. To analyze the protective immunity created by tumor inoculation, B16 cells were injected into the left thighs of mice that had received an inoculation, and tumor growth was monitored. The local delivery of dendritic cells pulsed with IL-18 bound by SFV combined with the systemic administration of IL-12 enhanced the induction of the T helper type 1 response from tumor-specific CD4+ and CD8+ T cells and natural killer cells as well as antitumor immunity. Interferon-gamma is partly responsible for this IL-18-mediated antitumor immunity. Furthermore, the protective immunity is mediated mainly by CD8+ T cells.

CONCLUSIONS

Immunogene therapy that combines the local administration of dendritic cells pulsed with IL-18 bound by SFV and the systemic administration of IL-12 may be an excellent candidate for the development of a new treatment protocol. A self-replicating SFV system may therefore open a novel approach for the treatment of malignant brain tumor.

Truncated thioredoxin (Trx80) exerts unique mitogenic cytokine effects via a mechanism independent of thiol oxido-reductase activity

Recently we discovered that a naturally occurring C-terminally truncated thioredoxin (Trx80) is a potent mitogenic cytokine stimulating IL-12 production from CD40(+) monocytes. To further characterise Trx80 we have engineered cysteine to serine mutants of Trx80 corresponding to the active site cysteines of Trx (Trx80SGPS) and to the structural cysteine at position 72 (Trx80C72S). Trx80SGPS and Trx80C72S retained the cell stimulatory activity of Trx80 and increased peripheral blood mononuclear cell (PBMC) proliferation three- to five-fold in vitro (P<0.01, n=18). Both Trx80SGPS and Trx80C72S significantly stimulated IL-12 and IFN-gamma secretion from PBMCs in the same manner as Trx80 (P<0.01, n=9 and 10). The previously described Trx80 dimer is caused by non-covalent interactions, and not by any intermolecular disulphide bonds.

Administration of interleukin-12 and -18 enhancing the antitumor immunity of genetically modified dendritic cells that had been pulsed with Semliki forest virus-mediated tumor complementary DNA

OBJECT

Immunogene therapy for malignant gliomas was further investigated in this study to improve its therapeutic efficacy.

METHODS

Dendritic cells (DCs) were isolated from bone marrow and pulsed with phosphate-buffered saline or Semliki Forest virus (SFV)-mediated 203 glioma complementary (c)DNA with or without systemic administration of interleukin (IL)-12 and IL-18 to treat mice bearing the 203 glioma. To study the immune mechanisms involved in tumor regression, the authors investigated tumor growth of an implanted 203 glioma model in T cell subset-depleted mice and in interferon (IFN) gamma-neutralized mice. To examine the protective immunity produced by tumor inoculation, a repeated challenge of 203 glioma cells was given by injecting the cells into the left thighs of surviving mice and the growth of these cells was monitored. The authors demonstrated that the combined administration of SFV-cDNA, IL-12, and IL-18 produced significant antitumor effects against the growth of murine glioma cells in vivo and also can induce specific antitumor immunity. The synergic effects of the combination of SFV-cDNA, IL-12, and IL-18 in vivo were also observed to coincide with markedly augmented IFN-gamma production. The antitumor effects of this combined therapy are mediated by CD4+ and CD8+ T cells and by NK cells. These results indicate that the use of IL-18 and IL-12 in DC-based immunotherapy for malignant glioma is beneficial.

CONCLUSIONS

Immunogene therapy combined with DC therapy, IL-12, and IL-18 may be an excellent candidate in the development of a new treatment protocol. The self-replicating SFV system may therefore provide a novel approach for the treatment of malignant gliomas.

Marked enhancement of antitumor immune responses in mouse brain tumor models by genetically modified dendritic cells producing Semliki Forest virus-mediated interleukin-12

OBJECT

The authors evaluated dendritic cell (DC)-based immunotherapy for malignant brain tumor to improve its therapeutic efficacy.

METHODS

Dendritic cells were isolated from bone marrow and pulsed with phosphate-buffered saline, Semliki Forest virus (SFV)-LacZ, retrovirus vector GCsap-interleukin (IL)-12, and SFV-IL-12, respectively, to treat mice bearing brain tumors of the B16 cell line. The results indicated that therapeutic immunization with DCs pulsed with SFV-IL-12 prolonged the survival of mice with established tumors. Semliki Forest virus induced apoptosis in DCs, which in turn facilitated the uptake of apoptotic cells by other DCs, thus providing a potential mechanism for enhanced immunogenicity.

CONCLUSIONS

Therapy with DCs that have been pulsed with SFV-mediated IL-12 may be an excellent step in the development of new cancer vaccines. Intratumorally injected DCs that have been transiently transduced with IL-12 do not require pulsing of a source of tumor antigens to induce tumor regression.

Effect of risperidone on serum cytokines

A variety of cytokines are dysregulated in schizophrenia, and some antipsychotic drugs effect cytokines. In order to examine the effect of risperidone on plasma cytokines, we measured the serum level of IL-1b, IL-2, IL-6, IL-12, and INF-g during acute states of illness, and after 4 weeks of treatment with risperidone in 19 schizophrenic patients. The patients' psychopathology was assessed by PANSS. Plasma IL-12 levels increased significantly after 4 weeks of treatment (p = .002). Plasma IL-b, IL-2, IL-6, and INF-g levels were not significantly different before and after treatment. There were no significant correlations between the changes in cytokine levels and the changes in PANSS scores. Increased IL-12 may contribute to activation of immune responses during treatment with risperidone. IL-12 may play an important role in immune responses related to neuropsychiatry.

Systemic macrophage activation in locally-induced experimental arthritis

Local and systemic macrophage activation was examined during the course of monoarticular murine antigen-induced arthritis (AIA), induced by systemic immunization and subsequent local induction. The levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, IL-12p70, and nitric oxide (NO) were determined in joints, sera, and supernatants of peritoneal macrophages (the latter unstimulated or stimulated ex vivo with LPS/IFN-gamma). In comparison with normal mice, systemic immunization (day 0) was associated to significant rise of TNF-alpha in serum, IL-1beta in the joints, IL-6 in unstimulated macrophages and IL-12p70 in stimulated macrophages. Local induction led to a further significant increase of: (i) TNF-alpha, IL-1beta, and IL-6 in the joints; and (ii) IL-1beta, and IL-6 in sera and stimulated macrophages during acute and/or early chronic AIA (days 1 to 7). Unstimulated macrophages showed increased NO release (day 3), while stimulated macrophages significantly increased secretion of IL-12p70 (day 1). In late chronic AIA (day 21), cytokine/NO expression returned to immunization levels or below at all sites; solely IL-1beta in the joints remained significantly above normal levels. Therefore, the prevalently local AIA model is characterized by a mixture of local and systemic activation of the mononuclear phagocyte system (MPS). While systemic MPS activation preceding arthritis induction can be attributed to systemic immunization, further systemic activation during arthritis appears an integral pathogenetic component of AIA.

Viruses and autoimmune disease--two sides of the same coin?

Some viruses have the ability to modulate the development of autoimmune diseases. Virus infections have long been associated with the exacerbation of autoimmune disease, however, there is also evidence that viruses can actually protect against autoimmune disease. Several experimental models have been developed to investigate how some virus infections can prime for and trigger autoimmunity whereas others ameliorate the pathway leading to clinical disease. It is possible that the type I interferons, via interleukin 12, provide the link between viruses and autoimmunity.

Role of interleukin-12 and stat-4 in the regulation of airway inflammation and hyperreactivity in respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a respiratory pathogen that can cause significant morbidity in infants and young children. Interestingly, the majority of children who acquire a RSV infection do not exhibit severe symptoms. Development of a Th1 response has been associated with resolution of symptoms in viral infections and may explain mild RSV illness. The current study investigated the cytokine response observed in mild disease in C57BL/6 mice that had low airway resistance and mucus production with little pulmonary inflammation. RSV infection in these mice was accompanied by a fourfold increase in interleukin-12(IL-12). Treatment of RSV-infected mice with anti-IL-12 resulted in an increase in airway hyperreactivity, mucus production, and airway inflammation (eosinophilia). Since IL-12 activation is dependent on Stat-4-mediated intracellular signal transduction, similar experiments were performed in Stat-4 deficient mice and demonstrated similar results to those obtained from anti-IL-12 treated mice. Again, there was an increase in airway hyperreactivity and mucus production, and goblet cell hypertrophy. These studies support the importance of IL-12 in the immune response to RSV infection resulting in resolution of disease and protection from inappropriate inflammatory responses.

Plasma levels of viro-immunological markers in HIV-infected and non-infected Ethiopians: correlation with cell surface activation markers

Cross-sectional studies were conducted to measure soluble viral and immunological markers in plasma in order to determine the prognostic value of these markers for HIV disease progression in Ethiopians and to see their association with cell surface markers in HIV-1-infected and noninfected Ethiopians. Whole blood samples were collected from 52 HIV-1-negative Ethiopians, 32 HIV-1-positive Ethiopians with absolute CD4(+) T-cell count >200/microl whole blood and no AIDS defining conditions, and 39 HIV-positive Ethiopians with CD4(+) T-cell count <200/microl and/or AIDS defining conditions. Plasma levels of b(2)-microglobulin (b(2)m), soluble CD27 (sCD27), soluble tumor necrosis factor alpha receptor type II (sTNFR-II), IgG, IgA, IGE, and IL12 were elevated in HIV-1-infected individuals. The plasma levels of sTNFR-II, sCD27, b(2)m, IL12, and IgG were inversely correlated with numbers of CD4(+) T-cells, the proportion of naïve (CD45RA(+)CD27(+)) CD8(+) T-cells, and the proportion of CD8(+) T-cells expressing CD28 (CD8(+)CD28(+)) were positively correlated with the proportions of activated (HLA-DR(+)CD38(+)) CD4(+) T-cells, as well as activated (HLA-DR(+)CD38(+)) CD8(+) T-cells. A strong positive correlation was also observed when soluble immune markers were compared to each other. Multivariate regression analyses of soluble markers with numbers of CD4(+) T-cells showed that sCD27 is the best independent marker for CD4(+) T-cell decline in the HIV-1-infected Ethiopians. Our results indicate that measurement of soluble immune markers, which is relatively easy to perform, could be a good alternative to the quantification of T-cell subsets for monitoring HIV-1 disease progression in places where there is no facility for flow cytometric measurements.

A longitudinal analysis of cytotoxic T lymphocyte precursor frequencies to the hepatitis B virus in chronically infected patients

Individuals with acute hepatitis B virus (HBV) infection characteristically mount a strong, multispecific cytotoxic T lymphocyte (CTL) response that is effective in eradicating virus. In contrast, this response in chronic carriers is usually weak or undetectable. Since it is generally acknowledged that HBV pathogenesis is immune-mediated, the occurrence of episodes of active liver disease in many carriers suggests that these individuals can mount active CTL responses to HBV. To see whether the detection of circulating CTLs is related to these flare episodes, we have determined the CTL precursor (CTLp) frequencies to HLA-A2-restricted viral peptides in seven patients over a 12-24-month period of their disease. Limiting dilution analyses (LDA) were performed longitudinally to five epitopes comprising the viral capsid (HBc), envelope (HBs) and polymerase (pol) proteins. Assays were performed against a mixture of peptides, or against each individual peptide, to measure overall CTL activity and the multispecificity of the responses, respectively. Since two of the patients were treated with recombinant human interleukin-12 (rHuIL-12) at the time, with one individual achieving complete disease remission a year later after being treated with interferon-alpha, we were also able to examine the effects of these cytokines on HBV cytotoxicity. Our results indicate that weak but detectable CTL responses do occur in chronic carriers which are generally associated with disease flares, although CTLps were also seen occasionally during minimal disease activity. The range of specificities varied between individuals and within each individual during the course of the disease. Finally, we also provide evidence that CTL reactivity is stimulated following treatment with certain cytokines, but is dependent on the time of administration.

Induction of a therapeutic antitumor immunological response by intratumoral injection of genetically engineered Semliki Forest virus to produce interleukin-12

OBJECT

The authors investigated immunogene therapy for malignant glioma to determine whether its therapeutic efficacy could be improved.

METHODS

Four groups of 203-glioma-bearing mice were treated with injections of phosphate-buffered saline, Semliki Forest virus (SFV)-LacZ, retrovirus vector DFG-interleukin (IL)-12, and SFV-IL12, respectively. The results indicated that therapeutic immunization with SFV-IL12 prolonged the survival of mice with established tumors. Semliki Forest virus induces apoptotic death to glioma cells, which facilitates the uptake of apoptotic cells by dendritic cells, providing a potential mechanism for enhanced immunogenicity.

CONCLUSIONS

Immunogene therapy with IL-12 via SFV may be an excellent candidate for the development of new cancer vaccines.

Induction of histidine decarboxylase, the histamine-forming enzyme, in mice by interleukin-12

Interleukin (IL)-12, a potent antitumour cytokine, has inflammatory side effects. We examined the effect of IL-12 on the histamine-forming enzyme, histidine decarboxylase (HDC). When injected intraperitoneally into C3H/HeN mice, IL-12 exhibited antitumour activity against squamous epithelial tumour cells (NR-S1 cells). At doses that produced this antitumour activity, IL-12 also enhanced HDC activity in the lung, liver, spleen and bone marrow. Compared with that induced by IL-1, the elevation of HDC activity induced by IL-12 was low and slow. However, daily injections of IL-12, but not of IL-1, produced a cumulative effect on HDC activities, an accumulation of exudate in the thorax, and death. Antagonists of H1 and H2 receptors and an inhibitor of HDC all failed to prevent the pulmonary exudation and death. These results suggest that IL-12 is an inflammatory cytokine capable of stimulating the synthesis of histamine, but that histamine itself may be not the direct cause of the pulmonary exudation and/or lethality induced by IL-12.

IL-10 is induced in the reperfused myocardium and may modulate the reaction to injury

Reperfusion of the ischemic myocardium is associated with a dramatic inflammatory response leading to TNF-alpha release, IL-6 induction, and subsequent neutrophil-mediated cytotoxic injury. Because inflammation is also an important factor in cardiac repair, we hypothesized the presence of components of the inflammatory reaction with a possible role in suppressing acute injury. Thus, we investigated the role of IL-10, an anti-inflammatory cytokine capable of modulating extracellular matrix biosynthesis, following an experimental canine myocardial infarction. Using our canine model of myocardial ischemia and reperfusion, we demonstrated significant up-regulation of IL-10 mRNA and protein in the ischemic and reperfused myocardium. IL-10 expression was first detected at 5 h and peaked following 96-120 h of reperfusion. In contrast, IL-4 and IL-13, also associated with suppression of acute inflammation and macrophage deactivation, were not expressed. In the ischemic canine heart, CD5-positive lymphocytes were the predominant source of IL-10 in the myocardial infarct. In the absence of reperfusion, no significant induction of IL-10 mRNA was noted. In addition, IL-12, a Th1-related cytokine associated with macrophage activation, was not detected in the ischemic myocardium. In vitro experiments demonstrated late postischemic cardiac-lymph-induced tissue inhibitor of metalloproteinases (TIMP)-1 mRNA expression in isolated canine mononuclear cells. This effect was inhibited when the incubation contained a neutralizing Ab to IL-10. Our findings suggest that lymphocytes infiltrating the ischemic and reperfused myocardium express IL-10 and may have a significant role in healing by modulating mononuclear cell phenotype and inducing TIMP-1 expression.

Monocyte IL-10 production during respiratory syncytial virus bronchiolitis is associated with recurrent wheezing in a one-year follow-up study

Respiratory syncytial virus (RSV) bronchiolitis is associated with subsequent recurrent wheezing episodes. To determine whether cytokine responses during infection can be of predictive value for the development of recurrent wheezing, we performed a follow-up study in 50 hospitalized children with RSV bronchiolitis. Monocyte and lymphocyte cytokine responses in vitro were studied during the acute phase of disease, and again during the convalescent phase, 3 to 4 wk later. Monocyte cytokine responses, including interleukin-10 (IL-10), were measured in whole blood cultures, stimulated with lipopolysaccharide and interferon-gamma (LPS + IFN-gamma). In addition, T-cell cytokine responses, including IFN-gamma and IL-4 production, were measured in whole-blood cultures stimulated with phytohemagglutinin (PHA) or alphaCD2 + alphaCD28. Cytokine responses were analyzed in relation to the development of recurrent episodes of wheezing, documented by parents in a diary during a 1-yr follow-up period. IL-10 responses during the acute phase of RSV bronchiolitis were comparable to those in healthy control subjects. During the convalescent phase, IL-10 responses were significantly increased in patients as compared with those in healthy control subjects (p < 0.001). At follow-up, 27 children (58%) had recurrent episodes of wheezing. IL-10 levels, measured during the convalescent phase, were significantly higher in patients who developed recurrent wheezing during the year after RSV bronchiolitis than in patients without recurrent episodes of wheezing (p = 0.006). Moreover, IL-10 responses during the convalescent phase correlated significantly with the number of wheezing episodes (r = 0.42, n = 46, p = 0.004). Interestingly, no association was found between IFN-gamma responses, IL-4 responses, or IFNgamma/IL-4 ratios and recurrent wheezing. We conclude that monocyte IL-10 responses in vitro upon stimulation with nonspecific stimuli may have predictive value for the development of recurrent wheezing after RSV bronchiolitis. Moreover, our results indicate that not only allergen-driven Th2 cytokine responses can lead to asthmatic symptoms but also virus-induced changes in cytokine responses may result in asthmatic symptoms.

Suppression of Interleukin-12 Production by Human Monocytes After Preincubation With Lipopolysaccharide

Interleukin-12 (IL-12) is a potent proinflammatory and immunoregulatory cytokine skewing T lymphocytes to express a type 1 cytokine pattern. Optimal expression of IL-12 mRNA and bioactivity in vitro requires specific priming of monocytes by interferon-γ (IFN-γ) or granulocyte-macrophage colony-stimulating factor (GM-CSF) before lipopolysaccharide (LPS) stimulation. We show here for the first time that the production of IL-12 by IFN-γ– or GM-CSF–primed human monocytes can be completely suppressed by preincubation with LPS (fromEscherichia coli Serotype 055:B5) for 6 to 24 hours before the priming procedure. A dose-dependent suppression of IL-12p70 was measured on the levels of intracellular cytokine production and cytokine secretion. mRNA studies on the expression of p40 and p35 showed an LPS-induced downregulation of both subunits. The results of several different experimental approaches suggest that IL-12 downregulation was not due to endogenous IL-10, IL-4, prostaglandin E2 (PGE2), tumor necrosis factor- (TNF-), or nitric oxide (NO) production induced by LPS. Moreover, preincubation of monocytes with LPS did not lead to a downregulation of the CD14 antigen, which is an LPS receptor. LPS preincubation in this experimental setting did not result in a general hyporesponsiveness of the monocytes, as IL-6 production as well as IFN-γ–induced upregulation of CD54 did not decline. Downregulation of IL-12 was not due to changes in mRNA stability. These findings show that the immunoregulatory important cytokine, IL-12, underlies itself a complex regulation.

Suppression of Interleukin-12 Production by Human Monocytes After Preincubation With Lipopolysaccharide

Interleukin-12 (IL-12) is a potent proinflammatory and immunoregulatory cytokine skewing T lymphocytes to express a type 1 cytokine pattern. Optimal expression of IL-12 mRNA and bioactivity in vitro requires specific priming of monocytes by interferon-γ (IFN-γ) or granulocyte-macrophage colony-stimulating factor (GM-CSF) before lipopolysaccharide (LPS) stimulation. We show here for the first time that the production of IL-12 by IFN-γ– or GM-CSF–primed human monocytes can be completely suppressed by preincubation with LPS (fromEscherichia coli Serotype 055:B5) for 6 to 24 hours before the priming procedure. A dose-dependent suppression of IL-12p70 was measured on the levels of intracellular cytokine production and cytokine secretion. mRNA studies on the expression of p40 and p35 showed an LPS-induced downregulation of both subunits. The results of several different experimental approaches suggest that IL-12 downregulation was not due to endogenous IL-10, IL-4, prostaglandin E2 (PGE2), tumor necrosis factor- (TNF-), or nitric oxide (NO) production induced by LPS. Moreover, preincubation of monocytes with LPS did not lead to a downregulation of the CD14 antigen, which is an LPS receptor. LPS preincubation in this experimental setting did not result in a general hyporesponsiveness of the monocytes, as IL-6 production as well as IFN-γ–induced upregulation of CD54 did not decline. Downregulation of IL-12 was not due to changes in mRNA stability. These findings show that the immunoregulatory important cytokine, IL-12, underlies itself a complex regulation.

Interleukin-12 is detectable in sera of patients with multiple sclerosis - association with chronic progressive disease course?

Multiple sclerosis (MS) is widely accepted as a systemic T- cell-mediated autoimmune disease with a T-helper type-1 (TH-1) profile of cytokine production. We addressed the question whether interleukin-12 (IL-12), as a central mediator of TH-1-cell activities, is detectable in sera of MS patients, and if there is any association with disease activity. We analysed 171 sera of patients with MS and meningitis, and healthy controls. IL-12 p40 protein was detectable at low levels in MS patients (median 43 pg/ml) and controls (median 49 pg/ml). Analysing different disease courses and activities, a significant elevation in stable primary progressive MS cases compared with controls (median 66 pg/ml) was found. IL-12 p40 protein was not detectable in cerebrospinal fluid probes of 10 patients. We conclude that the function of IL-12 in MS depends on expression and degradation of the different proteins. These could act proinflammatory as well as limiting the disease process.

Interleukin-12 enhances antifungal activity of human mononuclear phagocytes against Aspergillus fumigatus: implications for a gamma interferon-independent pathway

The potential of recombinant human interleukin-12 (IL-12) to enhance the capacity of human monocytes (MNC) to elicit an oxidative burst and damage hyphae of Aspergillus fumigatus was investigated. Incubation of peripheral blood mononuclear cells (PBMC) from healthy adults with 10 to 100 ng of IL-12/ml at 37 degrees C for 2 to 3 days enhanced the production of superoxide anion (O2-) in response to phorbol myristate acetate (PMA) (P = 0.04) and unopsonized A. fumigatus hyphae (P = 0.03) and further enhanced hyphal damage (P = 0.009). Anti-gamma interferon (anti-IFN-gamma) blocked secretion of IFN-gamma by IL-12-treated PBMC but did not inhibit IL-12-induced O2- production by these cells in response to PMA. In addition, IL-12-treated elutriated MNC secreted no IFN-gamma or tumor necrosis factor alpha but exhibited enhanced O2- production compared to controls (P = 0.013). These findings demonstrate that IL-12 augments oxidative antifungal activities of MNC via an IFN-gamma-independent route, suggesting a novel pathway of IL-12 action in antifungal defense.

C5a Suppresses the Production of IL-12 by IFN-γ-Primed and Lipopolysaccharide-Challenged Human Monocytes

IL-12 is a key mediator of the immune response, skewing T lymphocytes toward a type 1 cytokine pattern. Priming with IFN-γ or GM-CSF is required for expression of IL-12p70 by cells in which IL-12 is inducible by bacterial products such as LPS. We here show for the first time that the production of bioactive IL-12 by human monocytes can be significantly suppressed by C5a if applied to IFN-γ-primed monocytes before LPS stimulation. There was a dose-dependent suppression by IL-12 (p70) on the levels of intracellular cytokine production and cytokine secretion. mRNA studies consistently showed a reduction of IL-12p40 and IL-12p35 expression by stimulation in the presence of C5a. The results of several different experimental approaches suggest that IL-12 down-regulation was not due to endogenous IL-10, IL-4, or PGE2 production induced by C5a. Moreover, stimulation of IFN-γ-primed monocytes with C5a did not lead to a down-regulation of the CD14 Ag, which is an LPS receptor. These findings show that the anaphylatoxin C5a has the capacity to directly interact with the complex regulation of IL-12.

Molecular design of conjugated tumor necrosis factor-alpha: synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha

We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic polymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the terminal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino groups of TNF-alpha and carboxyl group of PVP. In vitro specific bioactivity of PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-alpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were coupled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity among the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-fold higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor activity of MPVP- TNF-alpha was more than 5-fold stronger than that MPEG- TNF-alpha which had the highest anti-tumor activity among PEG-conjugated TNF-alphas examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflammation, while no side effects were observed following i.v. administration of MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was about 80 and 3-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TNF-alpha (122 min), respectively. These results suggested that PVP is a useful polymeric modifier for increasing the anti-tumor activity of PVP.

Granulocyte and natural killer activity in the elderly

The deterioration of the immune system in ageing, 'immunosenescence', is thought to contribute to increased morbidity and mortality from infections and possibly autoimmune diseases and cancer. The most profound changes involve effector and immunoregulatory T-cell functions. Immunosenescence appears also to be related to changes in non specific immunity as well. In the present study we have assessed superoxide production, chemotaxis and the expression of the apoptosis-related molecule APO1/Fas (CD95) on neutrophils (PMN) from young and old subjects. Furthermore, we have measured the basal natural killer (NK) activity of young and elderly subjects and we have compared the number of CD16+ cells found in these two groups. We observed a significant decrease age-related both of formation of O2- and chemotaxis whereas no significant correlation between age and the expression of CD95 on granulocyte membrane was demonstrated, suggesting that an increase age-related of CD95-linked apoptosis of PMN should be not an important determinant in the decreased PMN function. We also observed a significant correlation between age and NK activity. The decreased NK cell function was not due to a decreased number of NK cells in effector cell preparations since the number of CD16+ cells was significantly increased in old subjects. In conclusion, our results show that in the elderly there is also a deficit of the aspecific immunity that might play a role in the pathogenic mechanisms of the immunosenescence.

Elevated levels of interleukin-12 and interferon-gamma in patients with human T lymphotropic virus type I-associated myelopathy

The levels of interleukin-12 (IL-12) (p70 heterodimer), total IL-12 (p70 heterodimer plus p40 chains), interferon-gamma (IFN-gamma) as Th1 cytokine, and those of interleukin-4 (IL-4) and interleukin-10 (IL-10) as Th2 cytokines in sera and cerebrospinal fluid (CSF) from 22 patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) were compared with those of 22 patients with other neurological diseases (OND), including nine anti-HTLV-I-seropositive carriers. Both serum IL-12 (total and p70 heterodimer) and CSF IFN-gamma, measured by the enzyme-linked immunosorbent assay (ELISA), were significantly elevated in patients with HAM as compared to the patients with OND, including the anti-HTLV-I-seropositive carriers. Serum IFN-gamma also was significantly elevated in the HAM patients as compared to the controls. There was no significant difference in the CSF levels of IL-12 (total and p70 heterodimer) between the HAM patients and controls, whereas, for the Th2 cytokines IL-4 was detected in the CSF of four anti-HTLV-I-seropositive carriers of the 13 control patients but not in any of the patients with HAM. No significant difference was found in the serum levels of IL-4 and IL-10, nor in the CSF levels of IL-10 in the patients with HAM and in the controls. These findings indicate that in patients with HAM, the immunological balance of helper T lymphocytes between Th1 and Th2 is toward Th1 in the periphery and that Th1-mediated immunological status in the central nervous system is involved in the pathogenesis of HAM.

FLT3-Ligand Administration Inhibits Liver Metastases: Role of NK Cells

FLT3-ligand (FL) is a recently described cytokine that stimulates the proliferation and differentiation of hematopoietic progenitors both in vivo and in vitro and, when administered to mice, induces an accumulation of dendritic cells (DC) in different lymphoid and nonlymphoid organs and tissues, including the liver. We have studied the antitumor effect of FL administered alone or in combination with IL-12 in a day 3 murine liver metastasis model. FL significantly reduced the number of hepatic metastases (36.00 ± 11.00 vs 92.00 ± 10.19 in control group, p &lt; 0.05). Histologic evaluation of the livers revealed that FL induced a significant infiltration of the tumor border by lymphocytes and DC associated with increased number of apoptotic figures. Immunohistochemical analysis demonstrated that FL significantly enhanced the number of DC in the liver parenchyma and within the liver metastases, as well as the number of CD4+ and CD8+ T lymphocytes. These data support the suggestion that DC may be directly involved in the antitumor effect of FL. Interestingly, the antitumor effect of FL was greatly reduced by the NK depletion. Combination of FL and IL-12 resulted in greater antitumor efficacy than these cytokines alone. In summary, we have shown that FL has significant antitumor effect on preexisting murine C3 liver tumors that is mediated by NK cells. We have also demonstrated that the FL/IL-12 combination has an enhanced antitumor activity in the same murine tumor model.

Basic pathogenic mechanisms operating in experimental models of acute anterior uveitis

Acute anterior uveitis is a recurrent inflammatory disease of the eye that occurs commonly, is distressing for the patient, and may have potentially blinding sequelae. The pathogenesis of the disease is poorly understood, and anti-inflammatory treatment is consequently non-specific and may be associated with significant complications. Animal models are a possible key to a better understanding of this disease. In one model, rats and mice develop a relatively short-lived anterior uveal inflammation almost immediately after systemic injection of bacterial endotoxin. Accumulating evidence suggests that cytokine production by resident uveal macrophages initiates endotoxin-induced uveitis which is characterized by an infiltration of neutrophils and mononuclear cells. A second model displays features in keeping with a delayed-type hypersensitivity immune response. Experimental melanin-induced uveitis is an acute recurrent uveitis with delayed onset but extended duration, observed when rats are immunized with bovine ocular melanin. Both animal models have clinical features in common with acute anterior uveitis, although experimental melanin-induced uveitis appears to mimic the human disease more closely. Novel treatment options to target implicated inflammatory cells and molecules are currently under consideration.

Evidence for IL-12-Activated Ca2+ and Tyrosine Signaling Pathways in Human Neutrophils

The cytokine IL-12 is proposed to play a bridging role between innate and adaptive immunity. Here we demonstrate that IL-12 binds specifically to human neutrophils. This binding leads to a transient increase in 1) intracellular free calcium due to its release from membrane-enclosed stores and its influx from extracellular medium, 2) actin polymerization, and 3) tyrosine phosphorylation. IL-12 treatment also leads to a concentration-dependent increase in reactive oxygen metabolite production. The effect of IL-12 is blocked by neutralizing Abs to IL-12. Inhibition of either calcium transient or tyrosine phosphorylation causes inhibition of reactive oxygen metabolite production. However, inhibition of actin polymerization enhances IL-12-induced oxidase activation. Our data suggest 1) a direct role for IL-12 in the activation of human neutrophils, and 2) a calcium-dependent signaling pathway for IL-12.

A role for persisting antigen, antigen presentation, and ICAM-1 in increased renal graft survival after oral or portal vein donor-specific immunization

BACKGROUND

We studied the mechanism behind increased renal allotransplant survival when C3H mice received donor-specific portal vein or oral immunization with C57BL/6 cells. Both regimens lead to donor-specific increased graft survival, in association with decreased production of cytotoxic T lymphocytes and altered cytokine production from host lymphocytes (decreased interleukin [IL]-2 production; increased IL-4, IL-10, and transforming growth factor-beta).

METHODS

We examined a role for persistent donor-derived antigen, in association with host dendritic cells, as well as a role for intercellular adhesion molecule-1 (ICAM-1), in the maintenance of unresponsiveness in host C3H spleen cells to donor antigen. We investigated whether there was a cooperative interaction between donor dendritic cells (DC) and host hepatic mononuclear cells in the induction of immunoregulation in C3H cells.

RESULTS

In mice with surviving renal grafts, donor antigen, in association with host DC, induced the recall of cytotoxicity from C57BL/6 immune C3H spleen cells and IL-4 but not IL-2 production, despite the decreased cytotoxicity seen in the renal transplant recipients themselves. Fresh donor DC induced IL-2 but not IL-4 production. Blocking expression of ICAM-1 on donor grafts, either with anti-ICAM-1 monoclonal antibodies after renal grafting or using grafts from ICAM-1 "knockout" mice, led to further increased survival. Cultured C3H responder spleen cells, incubated with C57BL/6 DC and C3H hepatic cells, transferred hyporesponsiveness to C57BL/6 cells in vitro and in vivo (as assayed by survival of C57BL/6 renal allografts).

CONCLUSIONS

Our data suggest a role for ICAM-1, persistent donor antigen (on host DC), and accessory hepatic monocytes in the induction and maintenance of tolerance after portal vein immunization.

Human Eosinophils Produce Biologically Active IL-12: Implications for Control of T Cell Responses

The present study assessed the capacity of eosinophils (EOS) to synthesize the cytokine IL-12. Blood-derived, highly purified human EOS from six atopic patients and two nonatopic individuals were treated in culture with IL-4, IL-5, granulocyte-macrophage CSF, IFN-γ, TNF-α, IL-1α, RANTES, and complement 5a, respectively. The expression of both IL-12 protein and mRNAs for the p35 and p40 IL-12 subunits was strongly induced in all donors by the Th2-like cytokines IL-4 and granulocyte-macrophage CSF and was also moderately induced by TNF-α and IL-1α. IL-5 treatment resulted in IL-12 synthesis in four atopic donors and one nonatopic donor, whereas IFN-γ induced IL-12 synthesis in only two atopic donors. In contrast, RANTES exclusively induced mRNA for the p40 subunit without detectable protein release, and complement 5a had no effect on IL-12 mRNA or protein expression. EOS-derived IL-12 was biologically active, because supernatants derived from IL-4-treated EOS superinduced the Con A-induced expression of IFN-γ by a human Th1-like T cell line. This activity was neutralized by anti-IL-12 Abs. In conclusion, EOS secrete biologically active IL-12 after treatment with selected cytokines, which mainly represent the Th2-like type. Consequently, EOS may promote a switch from Th2-like to Th1-like immune responses in atopic and parasitic diseases.