IL-12: the role of p40 versus p75

Cytokines as Potential Therapeutic Targets and their Role in the Diagnosis and Prediction of Cancers

The death rate from cancer is declining as a result of earlier identification and more advanced treatments. Nevertheless, a number of unfavourable adverse effects, including prolonged, long-lasting inflammation and reduced immune function, usually coexist with anti-cancer therapies and lead to a general decline in quality of life. Improvements in standardized comprehensive therapy and early identification of a variety of aggressive tumors remain the main objectives of cancer research. Tumor markers in those with cancer are tumor- associated proteins that are clinically significant. Even while several tumor markers are routinely used, they don't always provide reliable diagnostic information. Serum cytokines are promising markers of tumor stage, prognosis, and responsiveness to therapy. In fact, several cytokines are currently proposed as potential biomarkers in a variety of cancers. It has actually been proposed that the study of circulatory cytokines together with biomarkers that are particular to cancer can enhance and accelerate cancer diagnosis and prediction, particularly via blood samples that require minimal to the absence of invasion. The purpose of this review was to critically examine relevant primary research literature in order to elucidate the role and importance of a few identified serum cytokines as prospective therapeutic targets in oncological diseases.

IL-12p40 deletion aggravates lipopolysaccharide-induced cardiac dysfunction in mice

Background

Cardiac dysfunction is one of the most common complications of sepsis and is associated with the adverse outcomes and high mortality of sepsis patients. IL-12p40, the common subunit of IL-12 and IL-23, has been shown to be involved in a variety of inflammation-related diseases, such as psoriasis and inflammatory bowel disease. However, the role of IL-12p40 in lipopolysaccharide (LPS)-induced cardiac dysfunction remains obscure. This study aimed to explore the role of IL-12p40 in LPS-induced cardiac dysfunction and its potential mechanisms.

Methods

In this study, mice were treated with LPS and the cardiac expression of IL-12p40 was determined. Then, IL-12p40–/– mice were used to detect the role and mechanisms of IL-12p40 in LPS-induced cardiac injury. In addition, monocytes were adoptively transferred to IL-12p40–/– mice to explore their effects on LPS-induced cardiac dysfunction.

Results

The results showed that cardiac IL-12p40 expression was significantly increased after treated with LPS. In addition, IL-12p40 deletion significantly aggravated LPS-induced cardiac dysfunction, evidenced by the increased serum levels of cardiomyocyte injury markers and heart injury scores, as well as by the deteriorated cardiac function. Moreover, IL-12p40 deletion increased LPS-induced monocyte accumulation and cardiac expression of inflammatory cytokines, as well as enhanced the activation of the NF-κB and MAPK pathways. Furthermore, adoptive transfer WT mouse monocytes to IL-12p40−/− mice alleviated LPS-induced cardiac dysfunction and decreased the phosphorylation of p65.

Conclusion

IL-12p40 deletion significantly aggravated LPS-induced cardiac injury and cardiac dysfunction in mice by regulating the NF-κB and MAPK signaling pathways, and this process was related to monocytes. Therefore, IL-12p40 show a protective role in SIC, and IL-12p40 deficiency or anti-IL-12p40 monoclonal antibodies may be detrimental to patients with SIC.

Macrophage-like Cells Are Responsive to Titania Nanotube Intertube Spacing-An In Vitro Study

With the introduction of a new interdisciplinary field, osteoimmunology, today, it is well acknowledged that biomaterial-induced inflammation is modulated by immune cells, primarily macrophages, and can be controlled by nanotopographical cues. Recent studies have investigated the effect of surface properties in modulating the immune reaction, and literature data indicate that various surface cues can dictate both the immune response and bone tissue repair. In this context, the purpose of the present study was to investigate the effects of titanium dioxide nanotube (TNT) interspacing on the response of the macrophage-like cell line RAW 264.7. The cells were maintained in contact with the surfaces of flat titanium (Ti) and anodic TNTs with an intertube spacing of 20 nm (TNT20) and 80 nm (TNT80), under standard or pro-inflammatory conditions. The results revealed that nanotube interspacing can influence macrophage response in terms of cell survival and proliferation, cellular morphology and polarization, cytokine/chemokine expression, and foreign body reaction. While the nanostructured topography did not tune the macrophages’ differentiation into osteoclasts, this behavior was significantly reduced as compared to flat Ti surface. Overall, this study provides a new insight into how nanotubes’ morphological features, particularly intertube spacing, could affect macrophage behavior.

A Combination of GM-CSF and Released Factors from Gamma-Irradiated Tumor Cells Enhances the Differentiation of Macrophages from Bone Marrow Cells and Their Antigen-Presenting Function and Polarization to Type 1

Granulocyte-macrophage colony-stimulating factor (GM-CSF) promotes dendritic cell differentiation from precursors, and consequently, enhances the antigen presentation process and adaptive immune responses. With such functions, GM-CSF has been used as immunotherapy in combination with radiotherapy for cancer treatment to augment the survival and activity of immune cells. However, an immune-suppressive tumor microenvironment may cause anergy of T cells. It has also been reported that GM-CSF contributes to the development of myeloid-derived suppressor cells from the precursors. In this study, to analyze the combined effect of GM-CSF and released factors from cancer cells after gamma-ray irradiation on bone marrow cell differentiation and dynamics, we established an in vitro culture system using mouse bone marrow cells, GM-CSF, and conditioned medium from gamma ray irradiated mouse melanoma B16 cells at 24 Gy. We analyzed the gene expression changes of the bone marrow-derived cells on day 6. The results showed that GM-CSF dose-dependently enhanced the differentiation of macrophages from bone marrow cells, their antigen-presenting function and polarization to type I. The results implied the induced macrophages from the bone marrow may potentially contribute to tumor immune responses in a systemic manner when GM-CSF is boosted during photon-beam radiation therapy.

Used dental implant healing abutments elicit immune responses: A comparative analysis of detoxification strategies

PURPOSE

To determine if healing abutments (HA) can be "decontaminated" using four strategies available in clinical settings and compare the detoxification efficacy by quantifying residual biomaterial and capacity to elicit an inflammatory response in-vitro.

MATERIALS AND METHODS

Forty HA collected from subjects following intraoral use were randomly distributed into four test groups (A-D): A: autoclave only, B: ultrasonic bath plus autoclave, C: prophy-jet plus autoclave, and D: Scrub sponge plus autoclave. New, sterile HA: group E (Control). Residual protein concentration was determined by Micro BCA assay and stained with Phloxine B for macroscopic examination. HA were placed in human CD14+ monocyte derived-macrophage (mo-Mφ) cultures and supernatant collected at 4, 24, 48, and 5 days to analyze cytokine profiles using multiplex bead assay.

RESULTS

Test groups showed visible differences in "decontamination" levels compared to control. Groups C and D showed most effective debris removal and lowest residual protein concentration. Multiplex assay showed marked induction of pro-inflammatory cytokines by groups A and B and to a significantly lower level by groups C and D.

CONCLUSION

HA were not entirely "decontaminated" using common methods available relative to new, sterile HA and were capable of stimulating an immune response.

IL-12p40 gene expression in lung and hilar lymph nodes of MPS-resistant pigs

Mycoplasma pneumonia of swine (MPS) is caused by Mycoplasma hyopneumoniae (M.hp) and is a common chronic respiratory disease of pigs. Recently, a genetically selected variant of the Landrace pig (Miyagino L2) has a lower incidence of pulmonary MPS lesions. We investigated the pathological and immunological characteristics of MPS resistance in these pigs (n = 24) by comparing with the normal landrace pig (control: n = 24). The pathological MPS lung lesion score in MPS-selected landrace pigs was significantly lower than in the control. The gene expression of interleukin (IL)-12p40, which acts as a chemoattractant and a component of the bioactive cytokines IL-12 and IL-23, was significantly higher at the hilar lymph nodes, lung, and spleen in MPS-selected landrace pigs than in control landrace pigs, and these were negatively correlated with the macroscopic MPS lung lesion score. In summary, we demonstrate that resistance against MPS in Miyagino L2 pigs is associated with IL-12p40 up-regulation, in comparison with normal landrace pigs without the MPS vaccine. In addition, a comparative study of macroscopic MPS lung lesions and IL-12p40 gene expression in lung and hilar lymph nodes may lead to beneficial selection traits for the genetic selection for MPS resistance in pigs.

Novel functions of grass carp three p40 isoforms as modulators of Th17 signature cytokine expression in head kidney leukocytes

Interleukin (IL)-12p40, a component of IL-12 and IL-23, can be secreted as monomer and homodimer in mammals. Our previous study has proved the existence of natural three p40 isoforms and their proinflammatory properties in grass carp. In the present study, we unexpectedly found that recombinant grass carp p40a/b/c (rgcp40a, rgcp40b and rgcp40c) were able to enhance the mRNA levels of grass carp il-17a/f1 (gcil-17a/f1) in a dose- and time-dependent manner in head kidney leukocytes (HKLs). In agreement with these findings, the enzyme-linked immunosorbent assay (ELISA) showed that rgcp40a, rgcp40b and rgcp40c markedly stimulated gcIl-17a/f1 secretion from the HKLs. Together with their stimulatory effects on grass carp gcil-22 and gcil-26 expression, our data suggested their potential to mediate Th17-like response in grass carp. To support this notion, we investigated the underlying mechanisms for the regulation of rgcp40 isoforms on gcil-17a/f1 expression, and found that three rgcp40 isoforms significantly induced the activation of Erk, Jnk and Stat3 pathways in a time-dependent oscillation in the same cell model. Moreover, three rgcp40 isoforms-induced gcil-17a/f1 mRNA expression was suppressed by the inhibition on Erk, Jnk and Stat3 pathways, suggesting the signaling pathways in the p40 isoforms-mediating il-17a/f1 transcription. These studies for the first time proved the involvement of three gcp40 isoforms in mediating Th17 signature cytokine expression in fish immune cells, therefore providing new insights into the roles of p40 in teleost immunity.

Production and functional insights into the potential regulation of three isoforms of grass carp p40 subunit in inflammation

The p40 subunit is known as a component of Interleukin (IL)-12 and IL-23. In mammals, p40 can be secreted as a monomer or homodimer and acts independently to mediate cellular responses. Recently, three p40 paralogues were isolated and identified from grass carp and other fish species, but whether they exist independently as well as their functional consequences and significance remain unclear. In the present study, using grass carp as the model, we for the first time demonstrated the existence of natural fish p40a, p40b and p40c (gcp40a, gcp40b and gcp40c) mainly as a monomer in culture supernatant of head kidney leukocytes (HKLs). Particularly, their excessive secretion induced by various immune stimuli suggests possible involvement of free p40s in fish immune responses. To define their functions, recombinant grass carp p40a/b/c (rgcp40a, rgcp40b and rgcp40c) were prepared by Pichia pastoris expression system, and they possessed the activities to enhance the secretion of pro-inflammatory cytokines including Il-1β and tumor necrosis factor-α (Tnf-α) in grass carp HKLs. These pro-inflammatory properties of p40 isoforms prompted us to investigate their roles during the inflammatory process. In line with this, in vivo study revealed the pathogenic effect of rgcp40a on intestinal inflammation, whereas gcp40a polyclonal antibodies remarkably ameliorated Aeromonas hydrophila-induced intestinal histopathological changes. Taken together, our results uncover the biological significance of free p40s in teleost, and provide new clue for targeting fish intestinal inflammation.

Cytokines: Key Determinants of Resistance or Disease Progression in Visceral Leishmaniasis: Opportunities for Novel Diagnostics and Immunotherapy

Leishmaniasis is a parasitic disease of humans, highly prevalent in parts of the tropics, subtropics, and southern Europe. The disease mainly occurs in three different clinical forms namely cutaneous, mucocutaneous, and visceral leishmaniasis (VL). The VL affects several internal organs and is the deadliest form of the disease. Epidemiology and clinical manifestations of VL are variable based on the vector, parasite (e.g., species, strains, and antigen diversity), host (e.g., genetic background, nutrition, diversity in antigen presentation and immunity) and the environment (e.g., temperature, humidity, and hygiene). Chemotherapy of VL is limited to a few drugs which is expensive and associated with profound toxicity, and could become ineffective due to the parasites developing resistance. Till date, there are no licensed vaccines for humans against leishmaniasis. Recently, immunotherapy has become an attractive strategy as it is cost-effective, causes limited side-effects and do not suffer from the downside of pathogens developing resistance. Among various immunotherapeutic approaches, cytokines (produced by helper T-lymphocytes) based immunotherapy has received great attention especially for drug refractive cases of human VL. Therefore, a comprehensive knowledge on the molecular interactions of immune cells or components and on cytokines interplay in the host defense or pathogenesis is important to determine appropriate immunotherapies for leishmaniasis. Here, we summarized the current understanding of a wide-spectrum of cytokines and their interaction with immune cells that determine the clinical outcome of leishmaniasis. We have also highlighted opportunities for the development of novel diagnostics and intervention therapies for VL.

Cutting Edge: Quantitative Determination of CD40L Threshold for IL-12 and IL-23 Production from Dendritic Cells

Early secretion of IL-12 by mouse dendritic cells (DCs) instructs T cells to make IFN-γ. However, only activated, but not naive T cells are able to license DCs for IL-12 production. We hypothesized that it might be due to different levels of CD40L expression on the surface of these cells, as CD40 signals are required for IL-12 production. Using quantitative cell-free systems incorporating CD40L in lipid bilayers combined with total internal reflection fluorescence microscopy and flow cytometry, we show that as low as ∼200 CD40L molecules/μm2 in combination with IL-4 is sufficient to induce IL-12 production by DCs. Remarkably, CD40L alone is adequate to induce IL-23 secretion by DCs. Thus, although activated T cells have somewhat higher levels of CD40L, it is the combination of CD40L and the cytokines they secrete that licenses DCs and influences the effector class of the immune response.

Subnanometer Gold Clusters Adhere to Lipid A for Protection against Endotoxin-Induced Sepsis

Endotoxicity originating from a dangerous debris (i.e., lipopolysaccharide, LPS) of Gram-negative bacteria is a challenging clinical problem, but no drugs or therapeutic strategies that can successfully address this issue have been identified yet. In this study, we report a subnanometer gold cluster that can efficiently block endotoxin activity to protect against sepsis. The endotoxin blocker consists of a gold nanocluster that serves as a flakelike substrate and a coating of short alkyl motifs that act as an adhesive to dock with LPS by compacting the intramolecular hydrocarbon chain-chain distance ( d-spacing) of lipid A, an endotoxicity active site that can cause overwhelming cytokine induction resulting in sepsis progression. Direct evidence showed the d-spacing values of lipid A to be decreased from 4.19 Å to either 3.85 or 3.54 Å, indicating more dense packing densities in the presence of subnanometer gold clusters. In terms of biological relevance, the concentrations of key pro-inflammatory NF-κB-dependent cytokines, including plasma TNF-α, IL-6, and IL-1β, and CXC chemokines, in LPS-challenged mice showed a noticeable decrease. More importantly, we demonstrated that the treatment of antiendotoxin gold nanoclusters significantly prolonged the survival time in LPS-induced septic mice. The ultrasmall gold nanoclusters could target lipid A of LPS to deactivate endotoxicity by compacting its packing density, which might constitute a potential therapeutic strategy for the early prevention of sepsis caused by Gram-negative bacterial infection.

Ureaplasma Species Differentially Modulate Pro- and Anti-Inflammatory Cytokine Responses in Newborn and Adult Human Monocytes Pushing the State Toward Pro-Inflammation

Background:Ureaplasma species have been associated with chorioamnionitis and preterm birth and have been implicated in the pathogenesis of neonatal short and long-term morbidity. However, being mostly commensal bacteria, controversy remains on the pro-inflammatory capacity of Ureaplasma. Discussions are ongoing on the incidence and impact of prenatal, perinatal, and postnatal infection. The present study addressed the impact of Ureaplasma isolates on monocyte-driven inflammation. Methods: Cord blood monocytes of term neonates and adult monocytes, either native or LPS-primed, were cultured with Ureaplasma urealyticum (U. urealyticum) serovar 8 (Uu8) and Ureaplasma parvum serovar 3 (Up3). Using qRT-PCR, cytokine flow cytometry, and multi-analyte immunoassay, we assessed mRNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-8, IL-12p40, IL-10, and IL-1 receptor antagonist (IL-1ra) as well as Toll-like receptor (TLR) 2 and TLR4. Results: Uu8 and Up3 induced mRNA expression and protein release of TNF-α, IL-1β and IL-8 in term neonatal and adult monocytes (p < 0.01 and p < 0.05). Intracellular protein expression of TNF-α, IL-1β and IL-8 in Ureaplasma-stimulated cells paralleled those results. Ureaplasma-induced cytokine levels did not significantly differ from LPS-mediated levels except for lower intracellular IL-1β in adult monocytes (Uu8: p < 0.05). Remarkably, ureaplasmas did not induce IL-12p40 response and promoted lower amounts of anti-inflammatory IL-10 and IL-1ra than LPS, provoking a cytokine imbalance more in favor of pro-inflammation (IL-1β/IL-10, IL-8/IL-10 and IL-8/IL-1ra: p < 0.01, vs. LPS). In contrast to LPS, both isolates induced TLR2 mRNA in neonatal and adult cells (p < 0.001 and p < 0.05) and suppressed TLR4 mRNA in adult monocytes (p < 0.05). Upon co-stimulation, Uu8 and Up3 inhibited LPS-induced intracellular IL-1β (p < 0.001 and p < 0.05) and IL-8 in adult monocytes (p < 0.01), while LPS-induced neonatal cytokines were maintained or aggravated (p < 0.05). Conclusion: Our data demonstrate a considerable pro-inflammatory capacity of Ureaplasma isolates in human monocytes. Stimulating pro-inflammatory cytokine responses while hardly inducing immunomodulatory and anti-inflammatory cytokines, ureaplasmas might push monocyte immune responses toward pro-inflammation. Inhibition of LPS-induced cytokines in adult monocytes in contrast to sustained inflammation in term neonatal monocytes indicates a differential modulation of host immune responses to a second stimulus. Modification of TLR2 and TLR4 expression may shape host susceptibility to inflammation.

IL-12p40/IL-10 Producing preCD8α/Clec9A+ Dendritic Cells Are Induced in Neonates upon Listeria monocytogenes Infection

Infection by Listeria monocytogenes (Lm) causes serious sepsis and meningitis leading to mortality in neonates. This work explored the ability of CD11c^high lineage DCs to induce CD8⁺ T-cell immune protection against Lm in mice before 7 days of life, a period symbolized by the absence of murine IL-12p70-producing CD11c^highCD8α⁺ dendritic cells (DCs). We characterized a dominant functional Batf3-dependent precursor of CD11c^high DCs that is Clec9A⁺CD205⁺CD24⁺ but CD8α^- at 3 days of life. After Lm-OVA infection, these pre-DCs that cross-present Ag display the unique ability to produce high levels of IL-12p40 (not IL-12p70 nor IL-23), which enhances OVA-specific CD8⁺ T cell response, and regulatory IL-10 that limits OVA-specific CD8⁺ T cell response. Targeting these neonatal pre-DCs for the first time with a single treatment of anti-Clec9A-OVA antibody in combination with a DC activating agent such as poly(I:C) increased the protection against later exposure to the Lm-OVA strain. Poly(I:C) was shown to induce IL-12p40 production, but not IL-10 by neonatal pre-DCs. In conclusion, we identified a new biologically active precursor of Clec9A⁺ CD8α^- DCs, endowed with regulatory properties in early life that represents a valuable target to augment memory responses to vaccines.

Lm is a gram-positive food-borne pathogen that is the ethiological agent of listeriosis, a worldwide disease reported most frequently in developed countries. It can cause spontaneous septic abortions, fatal meningitis or encephalitis in immunocompromised and pregnant individuals. The murine model of systemic Lm infection has been demonstrated as a useful model to understand host resistance to intracellular pathogens. Neonates are highly susceptible to infections such as Lm, and display low responses to vaccines requiring IFN-γ producing T cells. In the present study, we characterized in murine neonates a precursor of conventional dendritic cells that is able to produce IL-12p40 and IL-10 cytokines and to modulate the development of the adaptive immune response, more particularly the CD8⁺ T cell response upon exposure to Lm. By targeting Lm-associated antigens to these conventional dendritic cell precursors in neonates, we succeeded to confer a partial protection to a lethal dose of Lm at the adult stage. Our study provides new insights into our understanding of the innate immune response to infections in early life and will help to design new vaccine strategies in newborns.

Inflammation and Elevation of Interleukin-12p40 in Patients with Schizophrenia

Schizophrenia is a serious mental illness with chronic symptoms and significant impairment in psychosocial functioning, which suggests that it likely has neurodegenerative characteristics. Inflammatory markers such as pro-inflammatory cytokines are well-known etiological contributors for psychiatric disorders, including schizophrenia. Although, the role of inflammation in schizophrenia is becoming evident, the number of studies in this area is relatively scarce, especially in Lebanon, and increased procedural thoroughness is needed. Cytokines play a key role in the activation of the immune system and strongly influence neurotransmission. Previous investigation of plasma levels showed dysregulation of interleukin (IL)-12. However, genotypical variations of this interleukin have not been investigated for patients with schizophrenia yet. Thus, in this paper, we aimed to compute and assess IL-12p40 levels in the sera of individuals with schizophrenia from different provinces in Lebanon and compare it to controls. Healthy subjects comprised 60 individuals with a male/female (M/F) ratio of 31/29, whereas patients with schizophrenia consisted of 63 subjects with an M/F ratio of 30/33. The mean age for healthy controls was 30 years, whereas that for patients with schizophrenia was 35 years. A standardized enzyme-linked immunosorbent assay (ELISA) technique was used to measure the concentration of IL-12p40 in all collected sera (n = 123). The mean IL-12p40 levels in patients with schizophrenia were significantly higher than in healthy controls (p = 0.002). Healthy females had a significantly higher concentration of IL-12p40 than healthy males (p = 0.009). Female patients with schizophrenia had significantly higher concentrations of IL-12p40 than their male counterparts (p < 0.001), healthy females (p = 0.018), and healthy males (p < 0.001), respectively. Male patients with schizophrenia had significantly higher concentrations of IL-12p40 than healthy males (p = 0.023). The study's results suggest that IL-12p40 has a putative role as a potential marker in schizophrenia and that its elevation may participate in its pathogenesis. IL-12p40 may be included in a panel to be evaluated in the sera of patients with schizophrenia and an appreciation of its independent function is important for improving our understanding of both protective and pathogenic immune responses. Future research should aim to assess this interleukin and understand its role in other mental illnesses that share a similar etiology to schizophrenia.

IL-12p40 Homodimer Ameliorates Experimental Autoimmune Arthritis

IL-23 is the key cytokine that induces the expansion of Th17 cells. It is composed of p19 and p40 subunits of IL-12. The p40 subunit binds competitively to the receptor of IL-23 and blocks its activity. Our aim was to assess the preventive and therapeutic effect of the IL-12p40 homodimer (p40)2 subunit in autoimmune arthritis animal models. In the current study, using IL-1R antagonist-knockout mice and a collagen-induced arthritis model, we investigated the suppressive effect of (p40)2 on inflammatory arthritis. We demonstrated that the recombinant adenovirus-expressing mouse (p40)2 model prevented the development of arthritis when given before the onset of arthritis. It also decreased the arthritis index and joint erosions in the mouse model if transferred after arthritis was established. (p40)2 inhibited the production of inflammatory cytokines and Ag-specific T cell proliferation. It also induced CD4(+)CD25(+)Foxp3 regulatory T (Treg) cells in vitro and in vivo, whereas the generation of retinoic acid receptor-related organ receptor γt and Th17 cells was suppressed. The induction of Treg cells and the suppression of Th17 cells were mediated via activated STAT5 and suppressed STAT3. Our data suggest that (p40)2 suppressed inflammatory arthritis successfully. This could be a useful therapeutic approach in autoimmune arthritis to regulate the Th17/Treg balance and IL-23 signaling.

Making many from few: IL-12p40 as a model for the combinatorial assembly of heterodimeric cytokines

How dendritic cells (DCs) gather information from the local milieu at a site of infection or injury and communicate this to influence adaptive immunity is not well understood. We and others have reported that soon after microbial encounter, DCs secrete the p40 subunit of IL-12, by itself, in a monomeric form. Based on recent data that this p40 monomer subsequently associates with p35 released from other cells to generate functional IL-12, we proposed that p40 can function as a DC-derived probe which samples the composition of the local milieu by looking for other binding partners. In this opinion, we discuss how such a sampling function might generate an elaborate combinatorial "code" of heterodimeric cytokines, capable of conveying location-specific information to cells downstream of DC activation, including NK and T cells.

Characterization of an IL-12 p40/p35 Truncated Fusion Protein That can Inhibit the Action of IL-12

Interleukin-12 (IL-12), a potent inducer of interferon gamma (IFNγ), is a heterodimeric protein consisting of p40 and p35 subunits whose expression is regulated independently. IL-12 is part of a cytokine family (currently consisting of IL-12, IL-23, IL-27, and IL-35) that can have profoundly different immunologic effects, despite sharing subunits. In constructing a single-chain fusion of p40 and p35, we discovered an insert corresponding to an intron in the gene encoding the p35 subunit that would result in a truncated form of p35 if translated. To test its possible role, we constructed, expressed, and analyzed fusions of p40 with the full-length or the truncated form of p35. The fusion protein containing the truncated p35 did not stimulate the proliferation of the IL-12-responsive cell line CTLL-2 nor did it induce IFNγ or the chemokine IFNγ-inducible protein 10 (IP-10, CXCL10) or monokine induced by IFNγ (MIG, CXCL9) from spleen cells. In striking contrast, the full-length IL-12 p40/p35 fusion induced robust responses in both assays. Moreover, the truncated IL-12 fusion protein inhibited the action of the full-length IL-12 p40/p35 fusion in the proliferation assay and also blocked the induction of IFNγ. These findings raise the possibility that alternative splicing may provide an additional regulatory mechanism for IL-12.

Inflammatory cytokines in allergy and rhinosinusitis

PURPOSE OF REVIEW

Cytokines are involved in initiating and perpetuating the host immune response to allergens and also modulating the mucosal cellular milieu characteristic of chronic rhinosinusitis. This paper reviews the current state of knowledge regarding the most relevant cytokines in allergy and rhinosinusitis and highlights recent findings in the literature.

RECENT FINDINGS

Chronic rhinosinusitis with nasal polyps is characterized by a type 2 T helper cell cytokine polarization, whereas chronic rhinosinusitis without nasal polyps has a type 1 T helper cell cytokine expression pattern. Targeted therapies against specific cytokines such as interleukin-5 have shown promise in treating allergic diseases. Genetic polymorphisms in cytokines and their receptors have been shown to confer susceptibility to asthma and allergy. Transforming growth factor-beta has been found to have proinflammatory and anti-inflammatory effects in the nose and paranasal sinuses and appears to have a role in airway remodeling.

SUMMARY

Cytokines drive the immune system's response to allergen exposure and participate in sinonasal mucosal inflammatory conditions. Although the roles of individual cytokines in atopic disease and rhinosinusitis are becoming clearer, future studies will need to build on our knowledge of cytokine functions by focusing on therapeutic approaches to quieting the immune system and dampening the inflammatory cascade.

Effects of CHO-expressed recombinant lactoferrins on mouse dendritic cell presentation and function

Lactoferrin (LF), a natural iron-binding protein, has previously demonstrated effectiveness in enhancing the Bacillus Calmette-Guérin (BCG) tuberculosis vaccine. This report investigates immune modulatory effects of Chinese hamster ovary (CHO) cell-expressed recombinant mouse and human LFs on mouse bone marrow-derived dendritic cells (BMDCs), comparing homologous and heterologous functions. BCG-infected BMDCs were cultured with LF, and examined for class II presentation molecule expression. Culturing of BCG-infected BMDCs with either LF decreased the class II molecule-expressing population. Mouse LF significantly increased the production of IL-12p40, IL-1β and IL-10, while human LF-treated BMDCs increased only IL-1β and IL-10. Overlaying naïve CD4 T-cells onto BCG-infected BMDCs cultured with mouse LF increased IFN-γ, whereas the human LF-exposed group increased IFN-γ and IL-17 from CD4 T cells. Overlay of naïve CD8 T cells onto BCG-infected BMDCs treated with mouse LF increased the production of IFN-γ and IL-17, while similar experiments using human LF only increased IL-17. This report is the first to examine mouse and human recombinant LFs in parallel experiments to assess murine DC function. These results detail the efficacy of the human LF counterpart used in a heterologous system to understand LF-mediated events that confer BCG efficacy against Mycobacterium tuberculosis challenge.

Cytokine expression provides clues to the pathophysiology of Gulf War illness and myalgic encephalomyelitis

Gulf War illness (GWI) is a chronic disease of unknown etiology characterized by persistent symptoms such as cognitive impairment, unexplained fatigue, pervasive pain, headaches, and gastrointestinal abnormalities. Current reports suggest that as many as 200,000 veterans who served in the 1990-1991 Persian Gulf War were afflicted. Several potential triggers of GWI have been proposed including chemical exposure, toxins, vaccines, and unknown infectious agents. However, a definitive cause of GWI has not been identified and a specific biological marker that can consistently delineate the disease has not been defined. Myalgic encephalomyelitis (ME) is a disease with similar and overlapping symptomology, and subjects diagnosed with GWI typically fit the diagnostic criteria for ME. For these reasons, GWI is often considered a subgroup of ME. To explore this possibility and identify immune parameters that may help to understand GWI pathophysiology, we measured 77 serum cytokines in subjects with GWI and compared these data to that of subjects with ME as well as healthy controls. Our analysis identified a group of cytokines that identified ME and GWI cases with sensitivities of 92.5% and 64.9%, respectively. The five most significant cytokines in decreasing order of importance were IL-7, IL-4, TNF-α, IL-13, and IL-17F. When delineating GWI and ME cases from healthy controls, the observed specificity was only 33.3%, suggesting that with respect to cytokine expression, GWI cases resemble control subjects to a greater extent than ME cases across a number of parameters. These results imply that serum cytokines are representative of ME pathology to a greater extent than GWI and further suggest that the two diseases have distinct immune profiles despite their overlapping symptomology.

Free IL-12p40 monomer is a polyfunctional adaptor for generating novel IL-12-like heterodimers extracellularly

IL-12p40 partners with the p35 and p19 polypeptides to generate the heterodimeric cytokines IL-12 and IL-23, respectively. These cytokines play critical and distinct roles in host defense. The assembly of these heterodimers is thought to take place within the cell, resulting in the secretion of fully functional cytokines. Although the p40 subunit alone can also be rapidly secreted in response to inflammatory signals, its biological significance remains unclear. In this article, we show that the secreted p40 monomer can generate de novo IL-12-like activities by combining extracellularly with p35 released from other cells. Surprisingly, an unbiased proteomic analysis reveals multiple such extracellular binding partners for p40 in the serum of mice after an endotoxin challenge. We biochemically validate the binding of one of these novel partners, the CD5 Ag-like glycoprotein, to the p40 monomer. Nevertheless, the assembled p40-CD5L heterodimer does not recapitulate the biological activity of IL-12. These findings underscore the plasticity of secreted free p40 monomer, suggesting that p40 functions as an adaptor that is able to generate multiple de novo composites in combination with other locally available polypeptide partners after secretion.

Detection of Mycobacterium avium subspecies paratuberculosis in patients with Crohn's disease is unrelated to the presence of single nucleotide polymorphisms rs2241880 (ATG16L1) and rs10045431 (IL12B)

Mycobacterium avium subspecies paratuberculosis (MAP) has been controversially linked with Crohn's disease (CD). Detection of MAP in CD has been highly variable, and one explanation might be the genetic heterogeneity of this syndrome. Many of the single nucleotide polymorphisms (SNPs) linked with CD are contained within genes that are associated with bacterial handling in general, and some are specifically implicated in susceptibility to mycobacterial disease. We tested a cohort of IBD patients (n = 149) to determine whether the presence of MAP was associated with a selection of these SNPs. Blood samples from CD patients (n = 84), ulcerative colitis (UC, n = 65) patients and healthy controls (n = 55) were examined for the presence of MAP and SNPs in ATG16L1, IL12B, NOD2/CARD15, NKx2-3, IL23R and IRGM. Statistical analysis was then used to determine whether there was any association between the presence of MAP and these SNPs. MAP, rs2241880 (ATG16L1) and rs10045431 (IL12B) were found to be significantly associated with CD. The presence of MAP was not related to the status of the SNPs in ATG16L1 or IL12B. We have found no evidence for the contribution of these SNPs to the presence of MAP in CD patients.

Subsets of human type 2 macrophages show differential capacity to produce reactive oxygen species

Reactive oxygen species (ROS) produced by macrophages have recently been shown to have immunosuppressive properties and induce regulatory T cells. Here we investigated the ROS producing capacity of well-defined human Mph2 subsets and studied the contribution of ROS in the Mph-T cell interaction. Mph were generated from monocytes using M-CSF (Mph2), IL-4 (Mph2a), or IL-10 (Mph2c). Upon PMA stimulation, Mph2 and Mph2c showed a high ROS producing capacity, whereas this was low for Mph2a. Mph2 and Mph2c displayed a reduced T cell stimulatory capacity compared to Mph2a. Addition of the ROS inhibitor DPI decreased the T cell proliferation and IFN-γ production. When testing directly on Mph, DPI dose-dependently decreased the IL-10 and IL-12p40 production of CD40L-stimulated Mph2 subsets. In conclusion, the ROS producing capacity is different among human Mph type-2 subsets. In all cases, DPI suppressed T cell proliferation and cytokine production, indicating a ROS-dependent mechanism of T cell activation.

The Hedgehog inhibitor suppresses the function of monocyte-derived dendritic cells from patients with advanced cancer under hypoxia

Immunotherapy using monocyte derived dendritic cells (Mo-DCs) from cancer patients has been developed; however, the Mo-DCs regularly studied have been derived from non-cancer bearing donors or mice, and evaluated in normoxic conditions. In the present study, we investigated the effects of Hedgehog (Hh) inhibitors which are being developed as molecular target drugs for cancer on the functions of Mo-DCs derived from patients with advanced cancer when cultured in a tumor-like hypoxic environment. Mo-DC induction, migration, chemotaxis, phagocytosis, maturation, IL-12 p40 or p70 secretion and the allogeneic lymphocyte stimulation activity of Mo-DCs from patients with advanced cancer were all significantly inhibited by the Hh inhibitor, cyclopamine under hypoxic conditions. Our results suggest that Hh signaling plays an important role in the maintenance and function of Mo-DCs derived from patients with advanced cancer when cultured under hypoxic conditions.

Multiplex protein profiling of bronchoalveolar lavage in idiopathic pulmonary fibrosis and hypersensitivity pneumonitis

CONTEXT:

Idiopathic pulmonary fibrosis (IPF) and chronic hypersensitivity pneumonitis (HP) are diffuse parenchymal lung diseases characterized by a mixture of inflammation and fibrosis, leading to lung destruction and finally death.

AIMS:

The aim of this study was to compare different pathophysiological mechanisms, such as angiogenesis, coagulation, fibrosis, tissue repair, inflammation, epithelial damage, oxidative stress, and matrix remodeling, in both disorders using bronchoalveolar lavage (BAL).

METHODS:

At diagnosis, patients underwent bronchoscopy with BAL and were divided into three groups: Control (n = 10), HP (n = 11), and IPF (n = 11), based on multidisciplinary approach (clinical examination, radiology, and histology): Multiplex searchlight technology was used to analyze 25 proteins representative for different pathophysiological processes: Eotaxin, basic fibroblast growth factor (FGFb), fibronectin, hepatocyte growth factor (HGF), interleukine (IL)-8, IL-12p40, IL-17, IL-23, monocyte chemotactic protein (MCP-1), macrophage-derived chemokine (MDC), myeloperoxidase (MPO), matrix metalloproteinase (MMP)-8, MMP-9, active plasminogen activating inhibitor 1 (PAI-1), pulmonary activation regulated chemokine (PARC), placental growth factor (PlGF), protein-C, receptor for advanced glycation end products (RAGE), regulated on activation normal T cells expressed and secreted (RANTES), surfactant protein-C (SP-C), transforming growth factor-β1 (TGF-β1), tissue inhibitor of metalloproteinase-1 (TIMP-1), tissue factor, thymic stromal lymphopoietin (TSLP), and vascular endothelial growth factor (VEGF).

RESULTS:

All patients suffered from decreased pulmonary function and abnormal BAL cell differential compared with control. Protein levels were increased in both IPF and HP for MMP-8 (P = 0.022), MMP-9 (P = 0.0020), MCP-1 (P = 0.0006), MDC (P = 0.0048), IL-8 (P = 0.013), MPO (P = 0.019), and protein-C (P = 0.0087), whereas VEGF was decreased (P = 0.0003) compared with control. HGF was upregulated in HP (P = 0.0089) and active PAI-1 was upregulated (P = 0.019) in IPF compared with control. Differences in expression between IPF and HP were observed for IL-12p40 (P = 0.0093) and TGF-β1 (P = 0.0045).

CONCLUSIONS:

Using BAL, we demonstrated not only expected similarities but also important differences in both disorders, many related to the innate immunity. These findings provide new clues for further research in both disorders.

Cerebrospinal fluid IL-12p40, CXCL13 and IL-8 as a combinatorial biomarker of active intrathecal inflammation

Diagnosis and management of the neuroinflammatory diseases of the central nervous system (CNS) are hindered by the lack of reliable biomarkers of active intrathecal inflammation. We hypothesized that measuring several putative inflammatory biomarkers simultaneously will augment specificity and sensitivity of the biomarker to the clinically useful range. Based on our pilot experiment in which we measured 18 inflammatory biomarkers in 10-fold concentrated cerebrospinal fluid (CSF) derived from 16 untreated patients with highly active multiple sclerosis (MS) we selected a combination of three CSF biomarkers, IL-12p40, CXCL13 and IL-8, for further validation.Concentrations of IL-12p40, CXCL13 and IL-8 were determined in a blinded fashion in CSF samples from an initial cohort (n = 72) and a confirmatory cohort (n = 167) of prospectively collected, untreated subjects presenting for a diagnostic work-up of possible neuroimmunological disorder. Diagnostic conclusion was based on a thorough clinical workup, which included laboratory assessment of the blood and CSF, neuroimaging and longitudinal follow-up. Receiver operating characteristic (ROC) curve analysis in conjunction with principal component analysis (PCA), which was used to combine information from all three biomarkers, assessed the diagnostic value of measured biomarkers.Each of the three biomarkers was significantly increased in MS and other inflammatory neurological disease (OIND) in comparison to non-inflammatory neurological disorder patients (NIND) at least in one cohort. However, considering all three biomarkers together improved accuracy of predicting the presence of intrathecal inflammation to the consistently good to excellent range (area under the ROC curve = 0.868-0.924).Future clinical studies will determine if a combinatorial biomarker consisting of CSF IL-12p40, CXCL13 and IL-8 provides utility in determining the presence of active intrathecal inflammation in diagnostically uncertain cases and in therapeutic development and management.

MCP-1-induced protein-1, an immune regulator

MCP-1-induced protein-1 (MCPIP1) is a newly identified protein that is crucial to immune regulation. Mice lacking MCPIP1 gene suffer from severe immune disorders, and most of them cannot survive longer than 12 weeks. Considerable progress has been made in revealing the mechanism underlying the immune regulatory function of MCPIP1. MCPIP1 can act as an RNase to promote the mRNA degradation of some inflammatory cytokines, such as IL-6 and IL-1. Pre-microRNAs are also confirmed to be the substrate of MCPIP1 RNase. The structure of MCPIP1 N-terminal conserved domain shows a PilT N-terminus-like RNase structure, further supporting the notion that MCPIP1 has RNase activity. MCPIP1 can also deubiquitinate TNF receptor-associated factor family proteins, which are known to mediate immune and inflammatory responses. In this review, we summarize recent progress on the immune regulatory role of MCPIP1 and discuss the mechanisms underlying its function.

Susceptibility of peritoneal macrophage from different species of neotropical primates to ex vivo Leishmania (L.) infantum chagasi-infection

This study examined the susceptibility of peritoneal macrophage (PM) from the Neotropical primates: Callithrix jacchus, Callithrix penicillata, Saimiri sciureus, Aotus azarae infulatus and Callimico goeldii to ex vivo Leishmania (L.) infantum chagasi-infection, the etiological agent of American visceral leishmaniasis (AVL), as a screening assay for evaluating the potential of these non-human primates as experimental models for studying AVL. The PM-susceptibility to infection was accessed by the PM-infection index (PMI) at 24, 72 h and by the mean of these rates (FPMI), as well as by the TNF-α, IL-12 (Capture ELISA) and Nitric oxide (NO) responses (Griess method). At 24h, the PMI of A. azarae infulatus (128) was higher than those of C. penicillata (83), C. goeldii (78), S. sciureus (77) and C. jacchus (55). At 72h, there was a significant PMI decrease in four monkeys: A. azarae infulatus (128/37), C. penicillata (83/38), S. sciureus (77/38) and C. jacchus (55/12), with exception of C. goeldii (78/54). The FPMI of A. azarae infulatus (82.5) and C. goeldii (66) were higher than C. jacchus (33.5), but not higher than those of C. penicillata (60.5) and S. sciureus (57.5). The TNF-a response was more regular in those four primates which decreased their PMI at 24/72 h: C. jacchus (145/122 pg/mL), C. penicillata (154/130 pg/mL), S. sciureus (164/104 pg/mL) and A. azarae infulatus (154/104 pg/mL), with exception of C. goeldii (38/83 pg/mL). The IL-12 response was mainly prominent in A. infulatus and C. goeldii which presented the highest FPMI and, the NO response was higher in C. goeldii, mainly at 72 h. These findings strongly suggest that these New World primates have developed a resistant innate immune response mechanism capable of controlling the macrophage intracellular growth of L. (L.) i. chagasi-infection, which do not encourage their use as animal model for studying AVL.

Lipopolysaccharide-activated dendritic cells: "exhausted" or alert and waiting?

LPS-activated dendritic cells (DCs) are thought to follow a set program in which they secrete inflammatory cytokines (such as IL-12) and then become refractory to further stimulation (i.e., "exhausted"). In this study, we show that mouse DCs do indeed lose their responsiveness to LPS, but nevertheless remain perfectly capable of making inflammatory cytokines in response to signals from activated T cells and to CD40-ligand and soluble T cell-derived signals. Furthermore, far from being rigidly programmed by the original activating stimulus, the DCs retained sufficient plasticity to respond differentially to interactions with Th0, Th1, Th2, and Th17 T cells. These data suggest that LPS activation does not exhaust DCs but rather primes them for subsequent signals from T cells.

Interleukin-12p40 modulates human metapneumovirus-induced pulmonary disease in an acute mouse model of infection

The mechanisms that regulate the host immune response induced by human metapneumovirus (hMPV), a newly-recognized member of the Paramyxoviridae family, are largely unknown. Cytokines play an important role in modulating inflammatory responses during viral infections. IL-12p40, a known important mediator in limiting lung inflammation, is induced by hMPV and its production is sustained after the resolution phase of infection suggesting that this cytokine plays a role in the immune response against hMPV. In this work, we demonstrated that in mice deficient in IL-12p40, hMPV infection induced an exacerbated pulmonary inflammatory response and mucus production, altered cytokine response, and decreased lung function. However, hMPV infection in these mice does not have an effect on viral replication. These results identify an important regulatory role of IL-12p40 in hMPV infection.

Characterization of monocyte-derived dendritic cells from patients with active and treated paracoccidioidomycosis

Cellular immune responses are a significant defence mechanism in human paracoccidioidomycosis (PCM), an endemic mycosis in Latin America; however, little is known about the role of dendritic cells (DCs) in human PCM. We investigated monocyte-derived DCs from patients with treated (TP) and active PCM (AP) compared with healthy non-PCM donors (CO). DCs from the TP group showed higher expression of HLA-DR, CD86 and DC-SIGN compared with CO, whereas AP showed similar expression to CO. Production of IL-10 was downregulated by TNF-α in all groups and lower levels were observed in untreated DCs from AP compared with CO. Conversely, IL-12p40 was significantly upregulated in the DCs of the TP group. TNF-α-activated DCs from the CO group produced significantly lower levels of IL-12p40 when differentiated from magnetic-sorted monocytes (MACS) compared with adhered monocyte-derived DCs. This comparison in the TP group revealed similar levels of IL-12p40, suggesting a T cell-independent increase in the production of IL-12p40. Higher expression of surface molecules with increased IL-12p40 may indicate a better activation of DCs after the treatment of PCM. Our findings suggest that DCs may be crucial in the protective response to Paracoccidioides brasiliensis and that in vitro-generated DCs might be useful in enhancing antifungal immunity, especially during active PCM.

T cell–independent restimulation of FVIII-specific murine memory B cells is facilitated by dendritic cells together with toll-like receptor 7 agonist

Memory B cells are involved in long-term maintenance of antibody-dependent immunologic disorders. Therefore, it is essential to understand how the restimulation of FVIII-specific memory B cells in hemophilia A with FVIII inhibitors is regulated. We asked whether concurrent activation of the innate immune system by an agonist for toll-like receptor (TLR) 7 is able to facilitate the differentiation of FVIII-specific memory B cells in the absence of T-cell help. TLR7 recognizes single-stranded RNA as contained in RNA viruses such as influenza, Sendai, and Coxsackie B viruses. Our results indicate that highly purified murine memory B cells do not differentiate into FVIII-specific antibody-secreting cells in the presence of FVIII and the TLR7 agonist when cultured in the absence of CD4+ T cells. However, CD11c+ dendritic cells facilitate the T cell–independent differentiation of FVIII-specific memory B cells but only in the presence of FVIII and the TLR7 agonist. In contrast to T cell–dependent restimulation, the antibody response after T cell–independent restimulation of FVIII-specific memory B cells is skewed toward IgG2a, an antibody subclass that is efficient in activating the complement system and in inducing Fc-receptor–mediated effector functions, both are required for effective immune responses against pathogens.

Antigen-activated T cells induce IL-12p75 production from dendritic cells in an IFN-γ-independent manner

The addition of IL-12p75 to naïve CD4(+) T cells promotes their differentiation towards a TH1-type cytokine pattern. Dendritic cells stimulated by LPS generate IL-12p75, but only if the environment also contains IFN-γ. Thus, it appears that IFN-γ is needed to start the response that will result in further production of IFN-γ. We previously reported that paradoxically DCs produce IL-12p75 only after engaging primed, but not naïve T cells. This study examines the mechanism by which primed T cells trigger IL-12p75 secretion and asks whether this induction is also dependent on the presence of IFN-γ. Here, we show that, in contrast to LPS, primed T cells induce IL-12p75 in an IFN-γ-independent manner. Addition of rIFN-γ to cocultures of naïve T cells with DCs did not induce IL-12p75. Moreover, antigen-activated CD4(+) T cells from wild type or IFN-γ-deficient mice both initiated IL-12p75 production from DCs. Surprisingly, we found that synergies between three T-cell-derived factors - CD40 Ligand, IL-4 and GM-CSF - were necessary and sufficient for IL-12p75 production. These results suggest that there are at least two distinct pathways for IL-12p75 production in vivo. Furthermore, the T-cell-dependent pathway of IL-12p75 production employs molecules that are not classically associated with a TH1-type response.

Human breast tumor cells express IL-10 and IL-12p40 transcripts and proteins, but do not produce IL-12p70

IL-10 transcripts were expressed in 14/15 primary breast adenocarcinomas and in 5/8 established breast tumor lines. Immunohistochemistry and immunoprecipitation from lysates and supernatants revealed that established breast tumor lines produced IL-10 protein. Immunohistochemistry revealed that IL-10 is localized to tumor cells of primary breast adenocarcinomas and to occasional infiltrating MNC. Established breast tumor cell lines expressed IL-12p40 transcripts (6/8) and protein (4/7) and IL-12p35 transcripts (6/7). Using two sandwich ELISAs, specific, respectively, for IL-12p40 and IL-12p70 proteins, we demonstrated that established breast tumor cell lines produce IL-12p40 monomer/homodimer, but not IL-12p70. Positive staining for IL-12p70 in primary breast adenocarcinomas was found only in MNC infiltrating the tumor while tumor cells were negative. IL-12p40 homodimer/monomer inhibit as antagonists IL-12 or IL-23, although they may also act as agonists and positive regulators. Also, primary breast adenocarcinomas (15/15) and established breast tumor cell lines (6/8) expressed TGF-β1 transcripts. IL-10, IL-12p40 and TGF-β1 may inhibit substantially the anti-tumor immune response.

Innate IFN-gamma production by subsets of natural killer cells, natural killer T cells and gammadelta T cells in response to dying bacterial-infected macrophages

Interferon-gamma (IFN-gamma) activation of macrophages is a crucial step in the early innate defence against bacterial infection. This innate IFN-gamma is thought to be produced mainly by natural killer (NK) cells through activation with interleukin (IL)-12p70 secreted by macrophages and dendritic cells (DCs) that have sensed bacterial products. However, a number of reports have shown that bacterial stimuli are unable to induce macrophages and/or DCs to produce sufficient amounts of IL-12p70 unless these cells are primed by IFN-gamma. It remains, therefore, unsettled how initial IFN-gamma is produced. In a previous study, we reported a novel IFN-gamma production pathway that was associated with cell death in macrophages caused by intracellular bacteria like Listeria monocytogenes (LM) and Shigella flexneri. In this study, we showed that cell death of bone-marrow-derived macrophage (BMM) cells following in vitro infection with Staphylococcus aureus (SA), an extracellular bacterium, can also stimulate this IFN-gamma production pathway. We also unequivocally demonstrated by using BMM cells from IL-12-deficient mice that the bacterial-infected macrophage cell death-mediated IFN-gamma production can occur without IL-12 although the magnitude of the response is much smaller than that in the presence of IL-12. The enhancing effect of IL-12 on this response proved to be attributable to the negligible amounts (0.5 approximately 1.5 pg/ml) of IL-12p70 but not to the large amounts of IL-12p40 that were both secreted by SA- and LM-infected macrophages. Taken all together, we propose that macrophage cell death caused by bacteria may trigger the initial IFN-gamma production at an early stage of bacterial infection.

Role of interleukin-12 family cytokines in the cellular response to mycobacterial disease

Interleukin (IL)-12 is a multifunctional cytokine acting as a key regulator of cell-mediated immune responses through the differentiation of naïve CD4+ T cells into type 1 helper T cells (Th1) producing interferon-gamma. As our knowledge of IL-12 family members is rapidly growing, it will be important to specify their involvement in the regulation of mycobacterial infection. This article is a review of the current knowledge regarding the functions of the IL-12 family cytokines in the immune host defense system against mycobacteria. Specifically, this review aims to describe recent scientific evidence concerning the protective role of some members of the IL-12 family cytokines for the control of mycobacterial infection, as well as to summarize knowledge of the potential use of the IL-12 family members as potent adjuvants in the prevention and treatment of mycobacterial infectious diseases. In addition, recent data supporting the importance of the IL-12 family members in mycobacterial diseases in relation to Th17 function are discussed. This examination will help to improve our understanding of the immune response to mycobacterial infection and also improve vaccine design and immunotherapeutic intervention against tuberculosis.

An IL-12 DNA vaccine co-expressing Yersinia pestis antigens protects against pneumonic plague

Pneumonic plague remains problematic in endemic areas, and because it can be readily transmitted and has high mortality, the development of efficacious vaccines is warranted. To test whether stimulation of cell-mediated immunity with IL-12 will improve protective immunity against plague, we constructed two IL-12 DNA vaccines using a bicistronic plasmid encoding the protective plague epitopes, capsular (F1) antigen and virulence antigen (V-Ag) as F1-V fusion protein and V-Ag only, respectively. When applied intramuscularly, antibody responses to F1- and V-Ag were detectable beginning at week 6 after 3 weekly doses, and F1-Ag protein boosts were required to induce elevated Ab responses. These Ab responses were supported by mixed Th cell responses, and the IL-12/V-Ag DNA vaccine showed greater cell-mediated immune bias than IL-12/F1-V DNA vaccine. Following pneumonic challenge, both IL-12 DNA vaccines showed similar efficacy despite differences in Th cells simulated. These results show that IL-12 can be used as a molecular adjuvant to enhance protective immunity against pneumonic plague.

Total IL-12 levels are increased in paediatric atopic dermatitis: correlations with age and disease severity

Alterations in the immune response play an important role in the pathogenesis of atopic dermatitis (AD). We evaluated the role of Th1/Th2 cytokine imbalance in paediatric AD and its progression towards other allergic manifestations. The levels of total interleukin (IL)-12 (p70+p40), IL-12 p70 and soluble CD30 (sCD30) were measured in paediatric patients affected by AD and in age-matched, non-atopic subjects (controls). The serum levels of total IL-12 and sCD30 were higher in patients than in controls (p=0.003 and p=0.053, respectively). Total IL-12 and sCD30 were also particularly increased in patients with severe disease. Serum levels of total IL-12 were negatively correlated with patient age (p=0.001): they were significantly higher in patients younger than 30 months, as compared to age-matched controls and to older patients and controls. Total IL-12 and sCD30 production were not significantly correlated with disease outcomes (atopic march) or with a family history of atopy. Our data show that total IL-12 levels are strongly associated with Th2 activation and severe disease in children with AD. The increased production of total IL-12 at an early age might indicate a different immune modulation and suggests the possibility of new therapeutic approaches for allergic diseases, in particular AD, early in childhood.

A nasal interleukin-12 DNA vaccine coexpressing Yersinia pestis F1-V fusion protein confers protection against pneumonic plague

Previous studies have shown that mucosal application of interleukin-12 (IL-12) can stimulate elevated secretory immunoglobulin A (IgA) responses. Since possible exposure to plague is via Yersinia pestis-laden aerosols that results in pneumonic plague, arming both the mucosal and systemic immune systems may offer an added benefit for protective immunity. Two bicistronic plasmids were constructed that encoded the protective plague epitopes, capsular antigen (F1-Ag) and virulence antigen (V-Ag) as a F1-V fusion protein but differed in the amounts of IL-12 produced. When applied nasally, serum IgG and mucosal IgA anti-F1-Ag and anti-V-Ag titers were detectable beginning at week 6 after three weekly doses, and recombinant F1-Ag boosts were required to elevate the F1-Ag-specific antibody (Ab) titers. Following pneumonic challenge, the best efficacy was obtained in mice primed with IL-12(Low)/F1-V vaccine with 80% survival compared to mice immunized with IL-12(Low)/F1, IL-12(Low)/V, or IL-12(Low) vector DNA vaccines. Improved expression of IL-12 resulted in lost efficacy when using the IL-12(High)/F1-V DNA vaccine. Despite differences in the amount of IL-12 produced by the two F1-V DNA vaccines, Ab responses and Th cell responses to F1- and V-Ags were similar. These results show that IL-12 can be used as a molecular adjuvant to enhance protective immunity against pneumonic plague, but in a dose-dependent fashion.

Leishmania major: recruitment of Gr-1+ cells into draining lymph nodes during infection is important for early IL-12 and IFN gamma production

The production of interleukin-12 and interferon-gamma is a key event for controlling leishmaniasis. Here, we tested the hypothesis that after murine infection with Leishmania major, cell migration into draining lymph nodes is crucial for early production of those cytokines. We showed that inflammatory cells carrying the marker of recently migrated cells, the Gr-1 antigen, including polymorphonuclear and mononuclear cells, migrate rapidly into the site of promastigote infection and, subsequently, into draining lymph nodes. Treatment with RB6-8C5 monoclonal antibody reduced local inflammation and migration of Gr-1+ cells into the draining lymph nodes. This reduction was associated with a decrease of interleukin-12 production by draining lymph node cells from BALB/c mice but not C57BL/6 mice. Additionally, interferon-gamma was also reduced in both mouse strains after depletion of Gr-1+ cells, suggesting that these cells are important for early interleukin-12 and interferon-gamma production. Our findings suggest that recently migrated myeloid cells, more than resident cells, are the major source of the early IL-12 production after L. major infection.

Transiently, paralleled upregulation of arginase and nitric oxide synthase and the effect of both enzymes on the pathology of asthma

Changes in the expression of arginase and their association with nitrosative stress were investigated using an asthmatic model previously established in NC/Nga mice with mite extract. Mite crude extract (100 microg/day) from Dermatophagoides farinae was administered intranasally for 5 consecutive days (day 0-4), and a single challenge was performed on day 11. On day 12, upregulation of the mRNA expression of inducible types of nitric oxide synthase (iNOS) and increases in immunohistochemical staining for iNOS and nitrotyrosine were observed. However, the level of nitrite + nitrate was unchanged. An increase in enzymatic activity, upregulation of mRNA expression, and immunostaining for arginase I was detected in the lung tissue and serum. Moreover, increases in both arginase I and II were revealed by immunoblotting. Goblet cell hyperplasia in bronchial epithelial cells and increasing collagen synthesis around the bronchus were also observed. These results suggested that an increase in arginase may lead to decreased availability of arginine for nitric oxide synthase and may contribute to the remodeling of the lung.

Streptococcus suisSerotype 2, an Important Swine and Human Pathogen, Induces Strong Systemic and Cerebral Inflammatory Responses in a Mouse Model of Infection

Streptococcus suis, an important swine and human pathogen, causes septic shock and meningitis. The pathogenesis of both systemic and CNS infections caused by S. suis is poorly understood. A hematogenous model of infection in CD1 mice was developed to study the systemic release of cytokines during the septic shock phase and the proinflammatory events in the CNS associated with this pathogen. Using a liquid array system, high levels of systemic TNF-alpha, IL-6, IL-12, IFN-gamma, CCL2, CXCL1, and CCL5 were observed 24 h after infection and might be responsible for the sudden death of 20% of animals. Infected mice that survived the early sepsis later developed clinical signs of meningitis and exhibited lesions in the meninges and in numerous regions of the brain, such as the cortex, hippocampus, thalamus, hypothalamus, and corpus callosum. Bacterial Ags were found in association with microglia residing only in the affected zones. In situ hybridization combined with immunocytochemistry showed transcriptional activation of TLR2 and TLR3 as well as CD14, NF-kappaB, IL-1beta, CCL2, and TNF-alpha, mainly in myeloid cells located in affected cerebral structures. Early transcriptional activation of TLR2, CD14, and inflammatory cytokines in the choroid plexus and cells lining the brain endothelium suggests that these structures are potential entry sites for the bacteria into the CNS. Our data indicate an important role of the inflammatory response in the pathogenesis of S. suis infection in mice. This experimental model may be useful for studying the mechanisms underlying sepsis and meningitis during bacterial infection.

Chorionic gonadotropin can enhance innate immunity by stimulating macrophage function

Human chorionic gonadotropin (hCG) is a placental glycoprotein, mainly secreted by trophoblasts during pregnancy. Its function in endocrine regulation has been well documented, but its immunological role is still largely unclear. For a successful pregnancy, an effective innate immunity is needed to protect the mother and fetus against infection, while maintaining tolerance against the paternal antigens of the fetus. The aim of this study was to investigate the effect of hCG on the function of macrophages (Mvarphi), which are major players in the innate response. hCG treatment of IFN-gamma-primed Mvarphi resulted in increased production of NO, reactive oxygen species, IL-6 and IL-12p40, and enhanced phagocytosis of apoptotic cells. hCG treatment did not affect the induction of allogeneic T cell proliferation by IFN-gamma-primed Mvarphi. The observed effects were receptor-mediated and involved the protein kinase A signaling pathway, as indicated by blocking studies using specific inhibitors. In vivo thioglycollate-elicited Mvarphi also exhibited increased phagocytic ability upon IFN-gamma activation and hCG treatment. In conclusion, hCG enhances Mvarphi functions involved in innate immunity, while the capacity to stimulate allogeneic T cells remains unchanged.

Consequences of the natural propensity of Leishmania and HIV-1 to target dendritic cells

Recent studies have shown that both Leishmania and HIV type-1 (HIV-1) hijack dendritic cell (DC) functions to escape immune surveillance using an array of elaborate strategies. Leishmania has developed a variety of adaptations to disrupt cellular defense mechanisms, whereas HIV-1 targets DCs to achieve a more efficient dissemination. The capacity of Leishmania and HIV-1 to target DCs through a common cell-surface molecule, namely DC-SIGN (dendritic cell specific ICAM-3-grabbing non-integrin), points to a possible dangerous liaison between these two pathogens. This review explores our knowledge of how Leishmania and HIV-1 interact dynamically with DCs, and how they exploit this cell type for their reciprocal benefit.

Differential response of splenic monocytes and DC from cattle to microbial stimulation with Mycobacterium bovis BCG and Babesia bovis merozoites

Both bovine peripheral blood monocyte-derived dendritic cells (DC) and myeloid DC from afferent lymph have been described, but resident DC from other bovine tissues have not been fully characterized. The spleen as a secondary lymphoid organ is central to the innate and acquired immune response to various diseases particularly hemoprotozoan infections like babesiosis. Therefore, we developed methods to demonstrate the presence of myeloid DC from the spleen of cattle and have partially characterized a DC population as well as another myeloid cell population with monocyte characteristics. The phenotypic profile of each population was CD13+CD172a+/-CD14-CD11a-CD11b+/-CD11c+ and CD172a+CD13+/-CD14+CD11a-CD11b+/-CD11c+, respectively. The CD13+ population was found exclusively in the spleen whereas the CD172a+ population was present at the same percentage in the spleen and peripheral blood. CD13+ cells developed a typical veiled appearance when in culture for 96 h. The two cell populations differed in their ability to produce nitric oxide and had a different pattern of cytokine mRNA when stimulated with Mycobacterium bovis BCG or Babesia bovis merozoites. The data demonstrate the presence of a myeloid splenic DC with attributes consistent with an immature status.

IL-12p40: an inherently agonistic cytokine

IL-12p40 is known as a component of the bioactive cytokines interleukin (IL)-12 and IL-23 but it is not widely recognized as having intrinsic functional activity. Recent publications have altered this perception and support an independent role for IL-12p40. IL-12p40 is induced in excess over the other subunits of IL-12 and IL-23 and can exist in a monomeric or homodimeric form. Its most widely appreciated function is to provide a negative feedback loop by competitively binding to the IL-12 receptor. However, IL-12p40 acts as a chemoattractant for macrophages and promotes the migration of bacterially stimulated dendritic cells. It is associated with several pathogenic inflammatory responses such as silicosis, graft rejection and asthma but it is also protective in a mycobacterial model. An appreciation of the independent function of IL-12p40 is important for improving our understanding of both protective and pathogenic immune responses.

Interleukin-12-responding asialoGM1+CD8+ central memory-type T cells as precursor cells for interferon-gamma-producing killer T cells

While investigating CD8(+) memory T cells in unimmunized C57BL/6 mice, we found that there were unique memory-type CD8(+) T cells expressing asialoGM1 (ASGM1), CD62L and CCR7 cell surface molecules, which occupied approximately 10% of CD8(+) T cells and 35% of CD44(+) memory CD8(+) T cells. Culture of freshly isolated ASGM1(+)CD8(+) T cells with interleukin (IL)-12 plus IL-2 caused the proliferation and generation of killer T cells. Moreover, ASGM1(+)CD8(+) T cells, but not ASGM1(-)CD8(+) T cells, produced high levels of interferon (IFN)-gamma in response to IL-12 plus IL-2. Although ASGM1(+)CD8(+) T cells showed no significant responses to IL-12 alone or IL-2 alone, pulse incubation of ASGM1(+)CD8(+) T cells with IL-12 at an earlier time (0-12 h), and subsequently with IL-2 at a later time (12-24 h), caused the same levels of proliferation, killer cell generation and IFN-gamma production as when they were incubated simultaneously with IL-12 plus IL-2 for 24 h. Thus, ASGM1(+)CD8(+) T cells appeared to respond to IL-12 directly to acquire IL-2 responsiveness and differentiate into IFN-gamma-producing killer T cells. Indeed, freshly isolated ASGM1(+)CD8(+) T cells, but not ASGM1(-)CD8(+) T cells, expressed higher levels of IL-12R beta2 mRNA. The fact that IL-12 administration in vivo caused the generation of ASGM1(+)CD8(+) killer T cells in an IFN-gamma-dependent manner further indicated a physiological significance of ASGM1(+)CD8(+) central memory-type T cells in IL-12-induced immunoregulation for the therapy of tumors and infectious diseases.

A three-cell model for activation of naïve T helper cells

It is generally assumed that the activation of naïve T helper (Th) cells is the result of a two-cell interaction between the Th cell and a dendritic cell (DC) and that three signals are required. Signal one or stimulation is the recognition by the T-cell receptor (TCR) of antigenic peptides presented by major histocompatibility complex (MHC) class II molecules. Signal two or co-stimulation is mainly provided by the triggering of CD28 on the T cell by CD80 and CD86 molecules on the DC. Signal three or polarization directs T-cell differentiation into various effector phenotypes such as Th1 and Th2. Both signals, two and three, are often assumed to result from the binding of microbial products or endogenous molecular danger signals to germline-encoded receptors such as toll-like receptors (TLR) on the DC. However, recent data challenge this two-cell model by revealing that Th1 polarization requires the presence of interferon-gamma (IFN-gamma) provided by a third cell. I propose here a three-cell model for naïve Th-cell activation. In this model, delivery of signal three by the DC is dependent on help provided by other innate immune cells such as NK cells, NK T cells, gammadelta T cells, mast cells, eosinophils and basophils. The rationale behind this model is that the innate immune system has been designed by evolution to select an appropriate class of immune response to protect the host.