Novel IL27p28/IL12p40 cytokine suppressed experimental autoimmune uveitis by inhibiting autoreactive Th1/Th17 cells and promoting expansion of regulatory T cells

Vorinostat Modulates the Imbalance of T Cell Subsets, Suppresses Macrophage Activity, and Ameliorates Experimental Autoimmune Uveoretinitis

The purpose of the study was to investigate the anti-inflammatory efficiency of vorinostat, a histone deacetylase inhibitor, in experimental autoimmune uveitis (EAU). EAU was induced in female C57BL/6J mice immunized with interphotoreceptor retinoid-binding protein peptide. Vorinostat or the control treatment, phosphate-buffered saline, was administrated orally from 3 days before immunization until euthanasia at day 21 after immunization. The clinical and histopathological scores of mice were graded, and the integrity of the blood-retinal barrier was examined by Evans blue staining. T helper cell subsets were measured by flow cytometry, and the macrophage functions were evaluated with immunohistochemistry staining and immunofluorescence assays. The mRNA levels of tight junction proteins were measured by qRT-PCR. The expression levels of intraocular cytokines and transcription factors were examined by western blotting. Vorinostat relieved both clinical and histopathological manifestations of EAU in our mouse model, and the BRB integrity was maintained in vorinostat-treated mice, which had less vasculature leakage and higher mRNA and protein expressions of tight junction proteins than controls. Moreover, vorinostat repressed Th1 and Th17 cells and increased Th0 and Treg cells. Additionally, the INF-γ and IL-17A expression levels were significantly decreased, while the IL-10 level was increased by vorinostat treatment. Furthermore, due to the reduced TNF-α level, the macrophage activity was considerably inhibited in EAU mice. Finally, transcription factors, including STAT1, STAT3, and p65, were greatly suppressed by vorinostat treatment. Our data suggest that vorinostat might be a potential anti-inflammatory agent in the management of uveitis and other autoimmune inflammatory diseases.

IL-27-induced modulation of autoimmunity and its therapeutic potential

Interleukin-27 (IL-27) is a new member of the IL-12 family. It is produced by activated antigen-presenting cells and plays an important role in the regulation of CD4+ T cell differentiation and immune response. IL-27 activates multiple signaling cascades, including the JAK-STAT and p38 MAPK pathways. Several studies have revealed that IL-27 promotes the differentiation of Th1 and Tr1, but inhibits Th2, Th17, and Treg cells. However, a few studies have shown an opposite effect on certain T cell subsets, such as Treg. IL-27 displays both pro- and anti- inflammatory activities in different autoimmune diseases. Here, we have discussed the role of IL-27 in rheumatoid arthritis, multiple sclerosis, colitis, lupus, psoriasis, type 1 diabetes, and uveitis. Most of this information is derived from experimental models of these autoimmune diseases. The mechanistic basis of the dual role of IL-27 in inflammation and autoimmunity is still not fully defined. In general, the pro-/anti-inflammatory activity of IL-27 is influenced by the underlying immune effector pathways, the phase of the disease, the presence or absence of counter-regulatory cytokines/T cell subsets, and the tissue/cell type under study. Despite a spectrum of outcomes in various autoimmune diseases, mostly anti-inflammatory and immunomodulatory effects of IL-27 have been observed in this category of diseases. Accordingly, IL-27 represents a novel, promising target/agent for the treatment of autoimmune diseases.

IL-Y, a synthetic member of the IL-12 cytokine family, suppresses the development of type 1 diabetes in NOD mice

The IL-12 family of heterodimeric cytokines, consisting of IL-12, IL-23, IL-27, and IL-35, has important roles in regulating the immune response. IL-12 family members are comprised of a heterodimer consisting of α and β chains: IL-12 (p40 and p35), IL-23 (p40 and p19), IL-27 (Ebi3 and p28), and IL-35 (Ebi3 and p35). Given the combinatorial nature of the IL-12 family, we generated adenoviral vectors expressing two putative IL-12 family members not yet found naturally, termed IL-X (Ebi3 and p19) and IL-Y (p40 and p28), as single-chain molecules. Single chain IL-Y (scIL-Y), but not scIL-X, was able to stimulate significantly a unique cytokine/chemokine expression profile as well as activate STAT3 in mice, in part, through a pathway involving IL-27Rα in splenocytes. Adenoviral-mediated, intratumoral delivery of scIL-Y increased tumor growth in contrast to the anti-tumor effects of scIL-12 and scIL-23. Similarly, treatment of prediabetic NOD mice by intravenous injection of Ad.scIL-Y prevented the onset of hyperglycemia. Analysis of cells from Ad.scIL-Y-treated NOD mice demonstrated that scIL-Y reduced expression of inflammatory mediators such as IFN-γ. Our data demonstrate that a novel, synthetic member of the IL-12 family, termed IL-Y, confers unique immunosuppressive effects in two different disease models and thus could have therapeutic applications.

Topical administration of a suppressor of cytokine signaling-1 (SOCS1) mimetic peptide inhibits ocular inflammation and mitigates ocular pathology during mouse uveitis

Uveitis is a diverse group of potentially sight-threatening intraocular inflammatory diseases and pathology derives from sustained production of pro-inflammatory cytokines in the optical axis. Although topical or systemic steroids are effective therapies, their adverse effects preclude prolonged usage and are impetus for seeking alternative immunosuppressive agents, particularly for patients with refractory uveitis. In this study, we synthesized a 16 amino acid membrane-penetrating lipophilic suppressor of cytokine signaling 1 peptide (SOCS1-KIR) that inhibits JAK/STAT signaling pathways and show that it suppresses and ameliorates experimental autoimmune uveitis (EAU), the mouse model of human uveitis. Fundus images, histological and optical coherence tomography analysis of eyes showed significant suppression of clinical disease, with average clinical score of 0.5 compared to 2.0 observed in control mice treated with scrambled peptide. We further show that SOCS1-KIR conferred protection from ocular pathology by inhibiting the expansion of pathogenic Th17 cells and inhibiting trafficking of inflammatory cells into the neuroretina during EAU. Dark-adapted scotopic and photopic electroretinograms further reveal that SOCS1-KIR prevented decrement of retinal function, underscoring potential neuroprotective effects of SOCS1-KIR in uveitis. Importantly, SOCS1-KIR is non-toxic, suggesting that topical administration of SOCS1-Mimetics can be exploited as a non-invasive treatment for uveitis and for limiting cytokine-mediated pathology in other ocular inflammatory diseases including scleritis.

Gene Expression Profiling in Peripheral Blood Cells and Synovial Membranes of Patients with Psoriatic Arthritis

Background

Psoriatic arthritis (PsA) is an inflammatory arthritis whose pathogenesis is poorly understood; it is characterized by bone erosions and new bone formation. The diagnosis of PsA is mainly clinical and diagnostic biomarkers are not yet available. The aim of this work was to clarify some aspects of the disease pathogenesis and to identify specific gene signatures in paired peripheral blood cells (PBC) and synovial biopsies of patients with PsA. Moreover, we tried to identify biomarkers that can be used in clinical practice.

Methods

PBC and synovial biopsies of 10 patients with PsA were used to study gene expression using Affymetrix arrays. The expression values were validated by Q-PCR, FACS analysis and by the detection of soluble mediators.

Results

Synovial biopsies of patients showed a modulation of approximately 200 genes when compared to the biopsies of healthy donors. Among the differentially expressed genes we observed the upregulation of Th17 related genes and of type I interferon (IFN) inducible genes. FACS analysis confirmed the Th17 polarization. Moreover, the synovial trascriptome shows gene clusters (bone remodeling, angiogenesis and inflammation) involved in the pathogenesis of PsA. Interestingly 90 genes are modulated in both compartments (PBC and synovium) suggesting that signature pathways in PBC mirror those of the inflamed synovium. Finally the osteoactivin gene was upregulared in both PBC and synovial biopsies and this finding was confirmed by the detection of high levels of osteoactivin in PsA sera but not in other inflammatory arthritides.

Conclusions

We describe the first analysis of the trancriptome in paired synovial tissue and PBC of patients with PsA. This study strengthens the hypothesis that PsA is of autoimmune origin since the coactivity of IFN and Th17 pathways is typical of autoimmunity. Finally these findings have allowed the identification of a possible disease biomarker, osteoactivin, easily detectable in PsA serum.

Interleukin-35 Inhibits Endothelial Cell Activation by Suppressing MAPK-AP-1 Pathway

Vascular response is an essential pathological mechanism underlying various inflammatory diseases. This study determines whether IL-35, a novel responsive anti-inflammatory cytokine, inhibits vascular response in acute inflammation. Using a mouse model of LPS-induced acute inflammation and plasma samples from sepsis patients, we found that IL-35 was induced in the plasma of mice after LPS injection as well as in the plasma of sepsis patients. In addition, IL-35 decreased LPS-induced proinflammatory cytokines and chemokines in the plasma of mice. Furthermore, IL-35 inhibited leukocyte adhesion to the endothelium in the vessels of lung and cremaster muscle and decreased the numbers of inflammatory cells in bronchoalveolar lavage fluid. Mechanistically, IL-35 inhibited the LPS-induced up-regulation of endothelial cell (EC) adhesion molecule VCAM-1 through IL-35 receptors gp130 and IL-12Rβ2 via inhibition of the MAPK-activator protein-1 (AP-1) signaling pathway. We also found that IL-27, which shares the EBI3 subunit with IL-35, promoted LPS-induced VCAM-1 in human aortic ECs and that EBI3-deficient mice had similar vascular response to LPS when compared with that of WT mice. These results demonstrated for the first time that inflammation-induced IL-35 inhibits LPS-induced EC activation by suppressing MAPK-AP1-mediated VCAM-1 expression and attenuates LPS-induced secretion of proinflammatory cytokines/chemokines. Our results provide insight into the control of vascular inflammation by IL-35 and suggest that IL-35 is an attractive novel therapeutic reagent for sepsis and cardiovascular diseases.

Association between Smoking and Uveitis: Results from the Pacific Ocular Inflammation Study

PURPOSE

To assess whether cigarette smoking is associated with the development of uveitis in a population-based setting.

DESIGN

Retrospective, population-based, case-control study.

PARTICIPANTS

Patients aged ≥ 18 years who were seen at a Kaiser Permanente Hawaii clinic between January 1, 2006, and December 31, 2007. Analysis included 100 confirmed incident uveitis cases, 522 randomly selected controls from the general Kaiser Hawaii population, and 528 randomly selected controls from the Kaiser Hawaii ophthalmology clinic.

METHODS

International Classification of Diseases, 9th revision (ICD-9), diagnosis codes were used to identify possible uveitis cases. A uveitis fellowship-trained ophthalmologist then conducted individual chart review to confirm case status. Multivariate logistic regression models were used to evaluate the association between smoking and uveitis, adjusting for age, sex, race, and socioeconomic status.

MAIN OUTCOME MEASURES

Development of uveitis.

RESULTS

Current smokers had a 1.63 (95% confidence interval [CI], 0.88-3.00; P = 0.12) and 2.33 (95% CI, 1.22-4.45; P = 0.01) times greater odds of developing uveitis compared with those who never smoked using the general and ophthalmology control groups, respectively. The association was even stronger with noninfectious uveitis, which yielded odds ratios of 2.10 (95% CI, 1.10-3.99; P = 0.02) and 2.96 (95% CI, 1.52-5.77; P = 0.001) using the general and ophthalmology control groups, respectively.

CONCLUSIONS

Cigarette smoking is significantly associated with new-onset uveitis within a population-based setting. The association was stronger for noninfectious uveitis. Given the well-established risks of smoking with regard to other inflammatory disorders, these results reaffirm the importance of encouraging patients to avoid or cease smoking.

Interleukin 12 (IL-12) family cytokines: Role in immune pathogenesis and treatment of CNS autoimmune disease

Cytokines play crucial roles in coordinating the activities of innate and adaptive immune systems. In response to pathogen recognition, innate immune cells secrete cytokines that inform the adaptive immune system about the nature of the pathogen and instruct naïve T cells to differentiate into the appropriate T cell subtypes required to clear the infection. These include Interleukins, Interferons and other immune-regulatory cytokines that exhibit remarkable functional redundancy and pleiotropic effects. The focus of this review, however, is on the enigmatic Interleukin 12 (IL-12) family of cytokines. This family of cytokines plays crucial roles in shaping immune responses during antigen presentation and influence cell-fate decisions of differentiating naïve T cells. They also play essential roles in regulating functions of a variety of effector cells, making IL-12 family cytokines important therapeutic targets or agents in a number of inflammatory diseases, such as the CNS autoimmune diseases, uveitis and multiple sclerosis.

The IL-6/gp130/STAT3 signaling axis: recent advances towards specific inhibition

Interleukin-6 has long been recognized as a prototypic pro-inflammatory cytokine that is involved in the pathogenesis of all inflammatory diseases. Activation of the gp130 homodimer by IL-6 leads to the initiation of Jak/STAT signaling, a pathway that is often constitutively switched on in inflammatory malignancies. However, a plethora of studies in the last decade has convincingly shown that only signaling via the soluble IL-6R (trans-signaling) accounts for the deleterious effects of IL-6, whereas classic signaling via the membrane-bound receptor is essential for the regenerative and anti-bacterial effects of IL-6 (classic signaling). In this review, we highlight recent developments in the field of IL-6 research, and specifically focus on advances towards a safe and specific inhibition of IL-6 trans-signaling.

Interleukin-27 in T cell immunity

Interleukin (IL)-27, a member of IL-12/IL-23 heterodimeric family of cytokines, has pleiotropic properties that can enhance or limit immune responses. IL-27 acts on various cell types, including T cells, B cells, macrophages, dendritic cells, natural killer (NK) cells and non-hematopoietic cells. Intensive studies have been conducted especially on T cells, revealing that various subsets of T cells respond uniquely to IL-27. IL-27 induces expansion of Th1 cells by activating signal transducer and activator of transcription (STAT) 1-mediated T-bet signaling pathway. On the other hand, IL-27 suppresses immune responses through inhibition of the development of T helper (Th) 17 cells and induction of IL-10 production in a STAT1- and STAT3-dependent manner. IL-27 is a potentially promising cytokine for therapeutic approaches on various human diseases. Here, we provide an overview of the biology of IL-27 related to T cell subsets, its structure, and production mechanism.

IL-30 (IL27p28) attenuates liver fibrosis through inducing NKG2D-rae1 interaction between NKT and activated hepatic stellate cells in mice

Chronic hepatic diseases, such as cirrhosis, hepatocellular carcinoma, and virus-mediated immunopathogenic infections, affect billions of people worldwide. These diseases commonly initiate with fibrosis. Owing to the various side effects of antifibrotic therapy and the difficulty of diagnosing asymptomatic patients, suitable medication remains a major concern. To overcome this drawback, the use of cytokine-based sustained therapy might be a suitable alternative with minimal side effects. Here, we studied the therapeutic efficacy and potential mechanisms of interleukin (IL)-30 as antifibrosis therapy in murine liver fibrosis models. CCl4 or 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) 0.1% (wt/wt) Purina 5015 Chow (LabDiet, St. Louis, MO) was fed for 3 weeks to induce liver fibrosis. Either control vector (pCtr) or pIL30 was injected hydrodynamically once per week. A significant decrease in collagen deposition and reduced expression of alpha-smooth muscle actin (α-SMA) protein indicated that IL-30-based gene therapy dramatically reduced bridging fibrosis that was induced by CCl4 or DDC. Immunophenotyping and knockout studies showed that IL-30 recruits natural-killer-like T (NKT) cells to the liver to remove activated hepatic stellate cells (HSCs) significantly and ameliorate liver fibrosis. Both flow cytometric and antibody-mediated neutralization studies showed that liver NKT cells up-regulate the natural killer group 2, member D (NKG2D) ligand and bind with the NKG2D ligand, retinoic acid early inducible 1 (Rae1), and positively activated HSCs to ameliorate liver fibrosis. Furthermore, adoptive transfer of liver NKT cells in T-cell-deficient mice showed reduction of fibrosis upon IL-30 administration.

CONCLUSIONS

Highly target-specific liver NKT cells selectively remove activated HSCs through an NKG2D-Rae1 interaction to ameliorate liver fibrosis after IL-30 treatment.

Identification and characterisation of the IL-27 p28 subunits in fish: Cloning and comparative expression analysis of two p28 paralogues in Atlantic salmon Salmo salar

Interleukin (IL)-27 is an IL-6/IL-12 family member with pro-inflammatory and anti-inflammatory properties. It is a heterodimeric cytokine composed of an α-chain p28 and a β-chain Ebi3 (Epstein-Barr virus induce gene 3). The p28 subunit can also be secreted as a monomer and function as IL-30 that acts as an inhibitor of IL-27 signalling. At present, the p28 gene has only been described in mammals. Thus, for the first time outwith mammals, we have identified seven p28 molecules in six divergent teleost fish species, Atlantic salmon, two cichlids, two cyprinids and a yellowtail. The fish p28 molecules have higher similarities to mammalian p28 than other IL-6/12 family members. Critical residues involved in the interaction with Ebi3 and the receptor gp130 are highly conserved. The prediction that these are true orthologues is supported by phylogenetic and synteny analysis. Two p28 paralogues (p28a and p28b) sharing 72% aa identity have been identified and characterised in Atlantic salmon. There are multiple upstream ATGs in the 5'-UTR and ATTTA motifs in the 3'-UTR of both cDNA sequences, suggesting regulation at the post-transcriptional and translational level. Both salmon p28 genes are highly expressed in immune relevant tissues, such as thymus, gills, spleen and head kidney. Conversely salmon Ebi3 is highly expressed in other organs, such as liver and caudal kidney. The expression of p28 but not Ebi3 was induced by PAMPs and recombinant cytokines in head kidney cells, and in spleen by Poly I:C challenge in vivo. The dissociation of the expression and modulation of p28 and Ebi3 suggest that both p28 and Ebi3 may be secreted alone or with other partners.

Th17 pathway-mediated immunopathogenesis of schizophrenia: mechanisms and implications

Schizophrenia is a highly complex and severe neuropsychiatric disorder with an unknown etiopathology. Evidence for a dysregulated immune system in both the risk for and progression of schizophrenia has recently been overwhelming. Importantly, chronic low-grade inflammation both in the periphery and central nervous system has been shown to contribute predominantly to the pathogenesis of schizophrenia in a subset of individuals. Inflammation in the central nervous system is mediated by a range of proinflammatory cytokines, resident immune cells such as microglia, and brain infiltrating peripheral immunocompetent cells, such as T lymphocytes. Recently, Th17 cells, a subset of T helper cells have emerged as crucial players in mucosal defense against infections. It is linked to atopic, inflammatory, and autoimmune disorders. The risk factors/mechanisms leading to low-grade inflammation in schizophrenia are diverse and include infectious agents, stress, trauma, environmental toxins, genetic vulnerability, physical inactivity, obesity, poor diet, and sleep disruption. Herein, we propose that fetal programming of cellular immune components driven by intrauterine adversity can lead to the generation of long-lasting effector/memory Th17 cells. Th17 cells can disrupt the blood-brain barrier, infiltrate the central nervous system, and, along with other cytokines and microglia, lead to neuroprogression through neuroinflammation in schizophrenia.

Interleukin-35 induces regulatory B cells that suppress autoimmune disease

Interleukin 10-producing regulatory B-cells (Breg-cells) suppress autoimmune diseases while aberrant elevation of Breg-cells prevents sterilizing immunity, promotes carcinogenesis and cancer metastasis by converting resting CD4⁺ T-cells to regulatory T-cells (Tregs). It is therefore of interest to discover factors that induce Breg-cells. Here we show that IL-35 induces Breg-cells in-vivo and promotes their conversion to a unique Breg subset that produces IL-35 (IL-35⁺Breg). Treatment of mice with IL-35 conferred protection from uveitis and mice lacking IL-35 or defective in IL-35-signaling produced less Breg-cells and developed severe uveitis. Ex-vivo generated Breg-cells also suppressed uveitis by inhibiting pathogenic Th17/Th1 while promoting Tregs expansion. We further show that IL-35 induced the conversion of human B-cells into Breg-cells and suppressed uveitis by activating STAT1/STAT3 through IL-35-Receptor comprising IL-12Rβ2/IL-27Rα subunits. Discovery that IL-35 converts human B-cells into Breg-cells, allows ex-vivo production of autologous Breg-cells for immunotherapy and investigating Breg/IL-35⁺Breg cells roles in autoimmune diseases and cancer.

Distinct from its canonical effects, deletion of IL-12p40 induces cholangitis and fibrosis in interleukin-2Rα(-/-) mice

The IL-12 family modulates T cell mediated autoimmune diseases and GWAS in PBC have suggested a critical role of IL-12 and its subunits in modulating portal inflammation. We have taken advantage of an aggressive model of portal inflammation and colitis in IL-2Rα(-/-) mice to study the specific role of IL-12 and, in particular, the immunobiology of p40(-/-)IL-2Rα(-/-) mice. Colonies of IL-2Rα(+/-), IL-2Rα(-/-) and p40(-/-)IL-2Rα(-/-) mice were studied for the natural history of immunopathology in liver and colon using histology and immunohistochemistry. Further, to focus on mechanisms, liver, spleen and mesenteric lymph node flow cytometry was employed to identify specific phenotypes; cytokine analysis on inflammatory cell populations was compared between groups. Finally, Real-Time PCR was used to focus on the genes involved in hepatic fibrosis. Surprisingly, p40(-/-)IL-2Rα(-/-) mice manifest more severe portal inflammation and bile duct damage, including signs of portal hypertension and liver fibrosis, but a significant reduction in colitis. Indeed, p40(-/-)IL-2Rα(-/-) mice reveal a profound hepatic CD8(+) T cell infiltrate, whose major component are effector memory cells as well as enhanced hepatic Th1 but reduced Th17 responses. These observations were confirmed by Real-Time PCR analysis of fibrosis-related genes in the liver. Distinct from its canonical effects, IL-12p40 plays a critical role in autoimmune cholangitis, including hepatic fibrosis. These data take on striking significance for any proposed human trials that modulate the IL-12p40 pathway in human PBC.

Understanding autoimmunity in the eye: from animal models to novel therapies

In recent years considerable headway has been made on understanding the mechanisms underlying inflammatory diseases of the eye. This includes the role of the innate vs. adaptive arms of the immune systems in disease, the concept that distinct immune pathways can drive end-organ pathology, and the role as well as limitations of immune privilege in controlling the innate and adaptive effector responses that lead to eye pathology and loss of vision. These insights have largely been derived from basic studies in established and in newly developed animal models of uveitis. The increased understanding of disease mechanisms has the potential to guide development of rational therapies for human uveitis. Many novel biologics currently in use or being evaluated have been developed, or validated, in animal models of autoimmune and inflammatory disease, including experimental uveitis. Paradoxically, and fueled in part by dwindling research budgets, a campaign has been gathering momentum against use of animal models in preclinical research, as being poorly representative of responses in humans. Given the extensive genetic similarity between humans and laboratory rodents as revealed by the Human, Mouse and Rat Genome Projects, and the finding that almost all known disease-associated genes have orthologs in mice and rats, perhaps the problem is our still-insufficient understanding of mechanisms and inadequate knowledge of species differences, resulting in poor choice of models, rather than in an inherent unsuitability of animal models to represent human disease.

IL-27p28 inhibits central nervous system autoimmunity by concurrently antagonizing Th1 and Th17 responses

Central nervous system (CNS) autoimmunity such as uveitis and multiple sclerosis is accompanied by Th1 and Th17 responses. In their corresponding animal models, experimental autoimmune uveitis (EAU) and experimental autoimmune encephalomyelitis (EAE), both responses are induced and can drive disease independently. Because immune responses have inherent plasticity, therapeutic targeting of only one pathway could promote the other, without reducing pathology. IL-27p28 antagonizes gp130, required for signaling by IL-27 and IL-6, which respectively promote Th1 and Th17 responses. We therefore examined its ability to protect the CNS by concurrently targeting both effector responses. Overexpression of IL-27p28 in vivo ameliorated EAU as well as EAE pathology and reduced tissue infiltration by Th1 and Th17 cells in a disease prevention, as well as in a disease reversal protocol. Mechanistic studies revealed inhibition of Th1 and Th17 commitment in vitro and decreased lineage stability of pre-formed effectors in vivo, with reduction in expression of gp130-dependent transcription factors and cytokines. Importantly, IL-27p28 inhibited polarization of human T cells to the Th1 and Th17 effector pathways. The ability of IL-27p28 to inhibit generation as well as function of pathogenic Th1 and Th17 effector cells has therapeutic implications for controlling immunologically complex autoimmune diseases.

Bioengineering heterodimeric cytokines: turning promiscuous proteins into therapeutic agents

The interleukin 12 (IL-12) family comprises a group of heterodimeric cytokines that can cope with a great variety of immune conditions as the microenvironment demands. By sharing cytokine and receptor subunits, IL-12 (comprised of p40/p35 subunits), IL-23 (p40/p19), IL-27 (p28/EBI3), and IL-35 (p35/EBI3) represent, as a whole, a highly versatile system participating in controlling the continuum from inflammation to tolerance. Promiscuity, a peculiar feature of those cytokines, is a powerful and economic means of producing individual factors with distinct activities via different combinations of a single set of subunits. Whereas IL-12 and IL-23 have a clearly dominant immunostimulatory functional profile and IL-35 is a potent immunosuppressive agent, IL-27 can exert both adjuvant and regulatory effects, depending on the cytokine milieu. Promiscuity itself, however, may significantly hamper the therapeutic use of heterodimeric cytokines. The subunits of a recombinant cytokine, when administered in its native form, will rapidly dissociate in vivo and reassociate with alternative partners, thus generating different heterodimeric or even homodimeric molecules (i.e., p40/p40) with unwanted effects. As in other areas, bioengineering has provided a formidable tool to overcome the constraints associated with the potential use of IL-12 family cytokines. The generation of several gene constructs expressing IL-12, IL-23, IL-27, IL-35, or even the homodimer p40/p40, in their monomerized, single-chain form has allowed us to unveil the efficacy of those molecules in several experimental settings, including neoplasia, viral infection, chronic inflammation, allergy and autoimmunity. Although work is still needed to obtain an overall picture of therapeutic vs. adverse effects of individual molecules before any use in humans, the new frontiers of bioengineering are now driving the production of completely new combinations of cytokine subunits that may further extend the potential clinical use of such eclectic proteins.

Interleukin-27: balancing protective and pathological immunity

It has been more than 15 years since the identification of individual interleukin-27 (IL-27) and IL-27 receptor components. The last decade has seen the description of the signaling pathways engaged by IL-27, and an appreciation has emerged that this cytokine can modulate the intensity and duration of many classes of T cell responses. Here we provide an overview of the immunobiology of IL-27 and review advances in understanding the functions of individual IL-27 and IL-27 receptor subunits and the role of IL-27 in dictating the balance between protective and pathological immunity. Additionally, this cytokine has been proposed as a therapy to modify inflammatory conditions or to promote antitumor responses, and situations where experimental and clinical data sets implicate IL-27 in the outcome of disease are highlighted.