Positive and Negative Regulation of the IL-27 Receptor during Lymphoid Cell Activation

Study the mRNA level of IL-27/IL-27R pathway molecules in kidney transplant rejection

BACKGROUND

Renal transplantation stands as the sole remedy for individuals afflicted with end-stage renal diseases, and safeguarding them from transplant rejection represents a vital, life-preserving endeavor posttransplantation. In this context, the impact of cytokines, notably IL-27, assumes a critical role in managing immune responses aimed at countering rejection. Consequently, this investigation endeavors to explore the precise function of IL-27 and its associated cytokines in the context of kidney transplant rejection.

METHODS

The study involved the acquisition of blood samples from a cohort of participants, consisting of 61 individuals who had undergone kidney transplantation (comprising 32 nonrejected patients and 29 rejected patients), and 33 healthy controls. The expression levels of specific genes were examined using SYBR Green Real-time PCR. Additionally, the evaluation encompassed the estimation of the ROC curve, the assessment of the relationship between certain blood factors, and the construction of protein-protein interaction networks for the genes under investigation.

RESULTS

Significant statistical differences in gene expression levels were observed between the rejected group and healthy controls, encompassing all the genes examined, except for TLR3 and TLR4 genes. Moreover, the analysis of the Area Under the Curve (AUC) revealed that IL-27, IL-27R, TNF-α, and TLR4 exhibited greater significance in discriminating between the two patient groups. These findings highlight the potential importance of IL-27, IL-27R, TNF-α, and TLR4 as key factors for distinguishing between individuals in the rejected group and those in the healthy control group.

CONCLUSIONS

In the context of kidney rejections occurring within the specific timeframe of 2 weeks to 2 months post-transplantation, it is crucial to emphasize the significance of cytokines mRNA level, including IL-27, IL-27R, TNF-α, and TLR4, in elucidating and discerning the diverse immune system responses. The comprehensive examination of these cytokines' mRNA level assumes considerable importance in understanding the intricate mechanisms underlying kidney rejection processes during this critical period.

Differential regulation of lineage-determining transcription factor expression in innate lymphoid cell and adaptive T helper cell subsets

CD4 T helper (Th) cell subsets, including Th1, Th2 and Th17 cells, and their innate counterparts innate lymphoid cell (ILC) subsets consisting of ILC1s, ILC2s and ILC3s, display similar effector cytokine-producing capabilities during pro-inflammatory immune responses. These lymphoid cell subsets utilize the same set of lineage-determining transcription factors (LDTFs) for their differentiation, development and functions. The distinct ontogeny and developmental niches between Th cells and ILCs indicate that they may adopt different external signals for the induction of LDTF during lineage commitment. Increasing evidence demonstrates that many conserved cis-regulatory elements at the gene loci of LDTFs are often preferentially utilized for the induction of LDTF expression during Th cell differentiation and ILC development at different stages. In this review, we discuss the functions of lineage-related cis-regulatory elements in inducing T-bet, GATA3 or RORγt expression based on the genetic evidence provided in recent publications. We also review and compare the upstream signals involved in LDTF induction in Th cells and ILCs both in vitro and in vivo. Finally, we discuss the possible mechanisms and physiological importance of regulating LDTF dynamic expression during ILC development and activation.

Glycometabolism-related gene signature of hepatocellular carcinoma predicts prognosis and guides immunotherapy

Hepatocellular carcinoma (HCC) is a severe cancer endangering human health. We constructed a novel glycometabolism-related risk score to predict prognosis and immunotherapy strategies in HCC patients. The HCC data sets were obtained from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) database, and the glycometabolism-related gene sets were obtained from the Molecular Signature Database. The least absolute contraction and selection operator (LASSO) regression model was used to construct a risk score based on glycometabolism-related genes. A simple visual nomogram model with clinical indicators was constructed and its effectiveness in calibration, accuracy, and clinical value was evaluated. We also explored the correlation between glycometabolism-related risk scores and molecular pathways, immune cells, and functions. Patients in the low-risk group responded better to anti-CTLA-4 immune checkpoint treatment and benefited from immune checkpoint inhibitor (ICI) therapy. The study found that glycometabolism-related risk score can effectively distinguish the prognosis, molecular and immune-related characteristics of HCC patients, and may provide a new strategy for individualized treatment.

Structure of the IL-27 quaternary receptor signaling complex

Interleukin 27 (IL-27) is a heterodimeric cytokine that functions to constrain T cell-mediated inflammation and plays an important role in immune homeostasis. Binding of IL-27 to cell surface receptors, IL-27Rα and gp130, results in activation of receptor-associated Janus Kinases and nuclear translocation of Signal Transducer and Activator of Transcription 1 (STAT1) and STAT3 transcription factors. Despite the emerging therapeutic importance of this cytokine axis in cancer and autoimmunity, a molecular blueprint of the IL-27 receptor signaling complex, and its relation to other gp130/IL-12 family cytokines, is currently unclear. We used cryogenic-electron microscopy to determine the quaternary structure of IL-27, composed of p28 and Epstein-Barr Virus-Induced 3 (Ebi3) subunits, bound to receptors, IL-27Rα and gp130. The resulting 3.47 Å resolution structure revealed a three-site assembly mechanism nucleated by the central p28 subunit of the cytokine. The overall topology and molecular details of this binding are reminiscent of IL-6 but distinct from related heterodimeric cytokines IL-12 and IL-23. These results indicate distinct receptor assembly mechanisms used by heterodimeric cytokines with important consequences for targeted agonism and antagonism of IL-27 signaling.

IL-27 induces IFN/STAT1-dependent genes and enhances function of TIGIT+ HIVGag-specific T cells

HIV-specific T cells have diminished effector function and fail to control/eliminate the virus. IL-27, a member of the IL-6/IL-12 cytokine superfamily has been shown to inhibit HIV replication. However, whether or not IL-27 can enhance HIV-specific T cell function is largely unknown. In the present manuscript, we investigated the role of IL-27 signaling in human T cells by evaluating the global transcriptional changes related to the function of HIV-specific T cells. We found that T cells from people living with HIV (PLWH), expressed higher levels of STAT1 leading to enhanced STAT1 activation upon IL-27 stimulation. Observed IL-27 induced transcriptional changes were associated with IFN/STAT1-dependent pathways in CD4 and CD8 T cells. Importantly, IL-27 dependent modulation of T-bet expression promoted IFNγ secretion by TIGIT+HIVGag-specific T cells. This new immunomodulatory effect of IL-27 on HIV-specific T cell function suggests its potential therapeutic use in cure strategies.

An Insight Into Systemic Immune Response in Leishmania donovani Mediated Atypical Cutaneous Leishmaniasis in the New Endemic State of Himachal Pradesh, India

Leishmaniasis continues to afflict known and newer endemic sites despite global efforts towards its control and elimination. In this regard, the emergence of newer endemic sites with unusual disease formats is recognized wherein Leishmania donovani complex classically known to cause visceral disease is demonstrated to cause cutaneous manifestation. In this context, atypical cutaneous leishmaniasis (CL) cases caused by L. donovani genetic variants from the newer endemic state of Himachal Pradesh (HP) in India are beginning to be understood in terms of parasite determinants. The atypical CL manifestation further needs to be explored to define host immune correlates with a possible role in driving the unusual disease progression. In the given study, we performed comprehensive systemic-immune profiling of the atypical CL patients from the study area in HP, India, in comparison with the classical visceral leishmaniasis (VL) patients from the northeast region of India. The systemic immune response was studied using ELISA-based assessment of Th1, Th2, Th17, Treg, and Th22 specific plasma cytokine expression pattern and parasite-specific total serum IgG/IgG subclasses. The specified immune correlates are known to exhibit heterogeneous association with the different infecting parasite species, infection load, and co-lateral host immunopathology in classical CL and VL. In the atypical CL patient group, altered expression of IL-10 emerged as the key finding that could potentially fine-tune the Th1/Th17/Th22 effector cytokine axis towards a localized cutaneous manifestation. A reduced expression of IL-10 along with a high IFN-γ/IL-10 ratio as a readout of effective parasite killing defined atypical cutaneous outcome. In contrast, high circulatory IL-10 levels and a depressed IFN-γ/IL-10 ratio were seen in classical VL patients in line with an ineffective parasite-killing cytokine response. Overall, the study highlights new knowledge on host immune correlates in terms of cytokine expression pattern and IgG subclasses that underline atypical disease manifestation such that L. donovani, a generally visceralizing parasite species cause skin localized cutaneous lesions.

Old and New Players of Inflammation and Their Relationship With Cancer Development

Pathogens or genotoxic agents continuously affect the human body. Acute inflammatory reaction induced by a non-sterile or sterile environment is triggered for the efficient elimination of insults that caused the damage. According to the insult, pathogen-associated molecular patterns, damage-associated molecular patterns, and homeostasis-altering molecular processes are released to facilitate the arrival of tissue resident and circulating cells to the injured zone to promote harmful agent elimination and tissue regeneration. However, when inflammation is maintained, a chronic phenomenon is induced, in which phagocytic cells release toxic molecules damaging the harmful agent and the surrounding healthy tissues, thereby inducing DNA lesions. In this regard, chronic inflammation has been recognized as a risk factor of cancer development by increasing the genomic instability of transformed cells and by creating an environment containing proliferation signals. Based on the cancer immunoediting concept, a rigorous and regulated inflammation process triggers participation of innate and adaptive immune responses for efficient elimination of transformed cells. When immune response does not eliminate all transformed cells, an equilibrium phase is induced. Therefore, excessive inflammation amplifies local damage caused by the continuous arrival of inflammatory/immune cells. To regulate the overstimulation of inflammatory/immune cells, a network of mechanisms that inhibit or block the cell overactivity must be activated. Transformed cells may take advantage of this process to proliferate and gradually grow until they become preponderant over the immune cells, preserving, increasing, or creating a microenvironment to evade the host immune response. In this microenvironment, tumor cells resist the attack of the effector immune cells or instruct them to sustain tumor growth and development until its clinical consequences. With tumor development, evolving, complex, and overlapping microenvironments are arising. Therefore, a deeper knowledge of cytokine, immune, and tumor cell interactions and their role in the intricated process will impact the combination of current or forthcoming therapies.

Immune exhaustion in chronic Chagas disease: Pro-inflammatory and immunomodulatory action of IL-27 in vitro

In chronic Chagas disease, Trypanosoma cruzi-specific T-cell function decreases over time, and alterations in the homeostatic IL-7/IL-7R axis are evident, consistent with a process of immune exhaustion. IL-27 is an important immunoregulatory cytokine that shares T-cell signaling with IL-7 and other cytokines of the IL-12 family and might be involved in the transcriptional regulation of T-cell function. Here, we evaluated the expression and function of IL-27R in antigen-experienced T cells from subjects with chronic Chagas disease and assessed whether in vitro treatment with IL-27 and IL-7 might improve T. cruzi-specific polyfunctional T-cell responses. In vitro exposure of PBMCs to T. cruzi induced a downregulation of IL-27R in CD4+ T cells and an upregulation in CD8+ T cells in subjects without heart disease, while IL-27R expression remained unaltered in subjects with more severe clinical stages. The modulation of IL-27R was associated with functional signaling through STAT3 and STAT5 and induction of the downstream genes TBX21, EOMES and CXCL9 in response to IL-27. In vitro treatment of PBMCs with IL-27 and IL-7 improved monofunctional and polyfunctional Th1 responses, accompanied by the induction of IL-10 and Bcl-2 expression in subjects without heart disease but did not improve those in subjects with cardiomyopathy. Our findings support the process of desensitization of the IL-27/IL-27R pathway along with disease severity and that the pro-inflammatory and immunomodulatory mechanisms of IL-27 might be interconnected.

A critical role for Th17 cell-derived TGF-β1 in regulating the stability and pathogenicity of autoimmune Th17 cells

Pathogenic conversion of Th17 cells into multifunctional helper T cells or Th1 cells contributes to the pathogenesis of autoimmune diseases; however, the mechanism regulating the plasticity of Th17 cells remains unclear. Here, we found that Th17 cells expressed latent TGF-β1 in a manner dependent on autocrine TGF-β1. By employing IL-17-producing cell-specific Tgfb1 conditional knockout and fate-mapping systems, we demonstrated that TGF-β1-deficient Th17 cells are relatively susceptible to becoming IFN-γ producers through IL-12Rβ2 and IL-27Rα upregulation. TGF-β1-deficient Th17 cells exacerbated tissue inflammation compared to TGF-β1-sufficient Th17 cells in adoptive transfer models of experimental autoimmune encephalomyelitis and colitis. Thus, TGF-β1 production by Th17 cells provides an essential autocrine signal for maintaining the stability and regulating the pathogenicity of Th17 cells in vivo.

Interleukin-27 as a Diagnostic Biomarker for Patients with Sepsis: A Meta-Analysis

Background

The present study was aimed to investigate the value of blood interleukin-27 (IL-27) as a diagnostic biomarker of sepsis.

Methods

We searched PubMed, EMBASE, the Cochrane Library, and the reference lists of relevant articles. All studies published up to October 21, 2020, which evaluated the accuracy of IL-27 levels for the diagnosis of sepsis were included. All the selected papers were assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). We used a bivariate random effects model to estimate sensitivity, specificity, diagnostic odds ratios (DOR), and a summary receiver operating characteristic curve (SROC). Deeks' funnel plot was used to illustrate the potential presence of publication bias.

Results

This meta-analysis included seven articles. The pooled sensitivity, specificity, and DOR were 0.85 (95% CI, 0.72-0.93), 0.72 (95% CI, 0.42-0.90), and 15 (95% CI, 3-72), respectively. The area under the summary receiver operating characteristic curve was 0.88 (95% CI, 0.84-0.90). The pooled I² statistic was 96.05 for the sensitivity and 96.65 for the specificity in the heterogeneity analysis. Deeks' funnel plot indicated no publication bias in this meta-analysis (P = 0.07).

Conclusions

The present results showed that IL-27 is a reliable diagnostic biomarker of sepsis, but it should be investigated in combination with other clinical tests and results.

The IL-27/IL-27R axis is altered in CD4+ and CD8+ T lymphocytes from multiple sclerosis patients

Objectives

Pro‐ and anti‐inflammatory properties have been attributed to interleukin‐27 (IL‐27). Nevertheless, the impact of this cytokine on chronic inflammatory diseases such as multiple sclerosis (MS) remains ill‐defined. We investigated the biology of IL‐27 and its specific receptor IL‐27Rα in MS patients.

Methods

Levels of IL‐27 and its natural antagonist (IL‐27‐Rα) were measured by ELISA in biological fluids. CD4⁺ and CD8⁺ T lymphocytes were isolated from untreated relapsing–remitting MS patients and healthy donors. Transcriptome‐wide analysis compared T‐cell subsets stimulated or not with IL‐27. Expression of the IL‐27Rα, key immune factors, STAT phosphorylation and cytokine production was assessed by flow cytometry.

Results

We observed elevated levels of IL‐27 in the serum and cerebrospinal fluid of MS patients compared with controls. Moreover, we show that specific IL‐27‐mediated effects on T lymphocytes are reduced in MS patients including the induction of PD‐L1. IL‐27‐triggered STAT3 signalling pathway is enhanced in CD4⁺ and CD8⁺ T lymphocytes from MS patients. Elevated IL‐27Rα levels in serum from MS patients are sufficient to impair the capacity of IL‐27 to act on immune cells. We demonstrate that shedding of IL‐27Rα by activated CD4⁺ T lymphocytes from MS patients contributes to the increased IL‐27Rα peripheral levels and consequently can dampen the IL‐27 responsiveness.

Conclusion

Our work identifies several mechanisms that are altered in the IL‐27/IL‐27R axis in MS patients, especially in T lymphocytes. Our results underline the importance of characterising the biology of cytokines in human patients prior to design new therapeutics.

The IL-27 receptor regulates TIGIT on memory CD4+ T cells during sepsis

Sepsis is a leading cause of morbidity and mortality associated with significant impairment in memory T cells. These changes include the upregulation of co-inhibitory markers, a decrease in functionality, and an increase in apoptosis. Due to recent studies describing IL-27 regulation of TIGIT and PD-1, we assessed whether IL-27 impacts these co-inhibitory molecules in sepsis. Based on these data, we hypothesized that IL-27 was responsible for T cell dysfunction during sepsis. Using the cecal ligation and puncture (CLP) sepsis model, we found that IL-27Rα was associated with the upregulation of TIGIT on memory CD4⁺ T cells following CLP. However, IL-27 was not associated with sepsis mortality.

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Numbers of IL-27Rα⁺ memory T cells are decreased following cecal ligation and puncture

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TIGIT is expressed on more IL-27Rα⁺ versus IL-27Rα⁻ memory CD4⁺ T cells during sepsis

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Il27ra^−/− and WT T cells exhibit similar effector function and apoptosis during sepsis

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IL-27 signaling does not impact sepsis mortality

The immunomodulatory potentials of interleukin-27 in airway allergies

Allergic airway disorders such as asthma and allergic rhinitis are mainly caused by inhaled allergen-induced improper activation and responses of immune and non-immune cells. One important response is the production of IL-27 by macrophages and dendritic cells (DCs) during the early stage of airway allergies. IL-27 exerts powerful modulatory influences on the cells of innate immunity [eg neutrophils, eosinophils, mast cells, monocytes, macrophages, dendritic cells (DCs), innate lymphoid cells (ILCs), natural killer (NK) cells and NKT cells)] and adaptive immunity (eg Th1, Th2, Th9, Th17, regulatory T, CD8⁺ cytotoxic T and B cells). The IL-27-mediated signalling pathways may be modulated to attenuate asthma and allergic rhinitis. In this review, a comprehensive discussion concerning the roles carried out by IL-27 in asthma and allergic rhinitis was provided, while evidences are presented favouring the use of IL-27 in the treatment of airway allergies.

IL-27 Regulated CD4+IL-10+ T Cells in Experimental Sjögren Syndrome

Interleukin 27 (IL-27) plays diverse immune regulatory roles in autoimmune disorders and promotes the generation of IL-10–producing CD4⁺ T cells characterized by producing the immunosuppressive cytokine IL-10. However, whether IL-27 participates in pathological progress of Sjögren syndrome (SS) through regulating CD4⁺IL-10⁺ T cells remains unknown. Here we aimed to explore the potential role of IL-27 and CD4⁺IL-10⁺ T cells in the pathogenesis of SS. The IL-27 gene knockout non-obese diabetic (Il-27^−/−NOD) mice were generated and injected with exogenous IL-27. Exogenous injection of IL-27 and neutralization of IL-27 with anti–IL-27 antibody in NOD mice were performed. The histopathologic changes in submandibular glands, lacrimal glands and lung, salivary flow rate, and percentages of CD4⁺IL-10⁺ T cells were determined. And, ovalbumin-immunized C57L/B6 mice were injected with IL-27 to detect the percentage of CD4⁺IL-10⁺ T cells. In vitro, splenic naive T cells from C57L/B6 mice were cultured with IL-27 for 4 days to induce the differentiation of CD4⁺IL-10⁺ T cells. In addition, IL-27, IL-10, and CD4⁺IL-10⁺ T cells were determined in health control and SS patients. The results showed that Il-27^−/−NOD mice had more severe disease and lower level of CD4⁺IL-10⁺ T cells than control mice. And IL-27 promoted the generation and differentiation of CD4⁺IL-10⁺ T cells in vivo and in vitro significantly. In agreement with the findings in the SS-like mice, patients with SS showed lower levels of IL-27, IL-10, and CD4⁺IL-10⁺ T cells. Our findings indicated that IL-27 deficiency aggravated SS by regulating CD4⁺IL-10⁺ T cells. Targeting IL-27 and CD4⁺IL-10⁺ T cells may be a novel therapy for patients with SS.

Interleukin-27 Functional Duality Balances Leishmania Infectivity and Pathogenesis

IL-27 is a cytokine that exerts diverse effects on the cells of innate and adaptive immune systems. Chiefly expressed in macrophages and dendritic cells during the early phase of Leishmania infection, IL-27 contributes to the protection against L. major infection but suppresses the protective Th1 response against L. donovani, L. infantum, L. amazonensis and L. braziliensis infections, suggesting its functional duality. During the late stage of Leishmania infection, IL-27 limits the immunopathogenic reactions and tissue damages. Herein, we analyze the mechanism of the functional duality of IL-27 in the resistance or susceptibility to Leishmania infection, prompting IL-27 for anti-Leishmanial therapy.

The contribution from interleukin-27 towards rheumatoid inflammation: insights from gene expression

We aimed to assess expression of genes encoding the heterodimeric IL-27 cytokine and constituent subunits of the Il-27 receptor in rheumatoid arthritis (RA), including in extra-articular, subcutaneous rheumatoid nodules. Comparing between nodules and joint synovia, significantly elevated expression of IL27A within nodules, and comparable IL27B expression, identified nodules as a significant source of IL-27 in RA. T-lymphocytes were the main source of IL27RA transcript, and IL27RA expression correlated with a number of plasma cytokines, as well as tissue TNF expression in both nodules and RA synovia. In synovia, correlations between IL27A, IL27RA IL17A and CD21L expression, and significantly elevated expression of the genes encoding IL-27, associated the presence of IL-27 with B cell-dominated synovial inflammation. Impact from nodule derived IL-27 on systemic or synovial inflammation in RA remains unknown and further study of these implications is required. Our study raises questions regarding the appropriate circumstances for the blockade or administration of IL-27 as a potential therapeutic adjunct in RA.

The clinical significance of IL-6 s and IL-27 s in Bronchoalveolar lavage fluids from children with mycoplasma pneumoniae pneumonia

Background

IL-6 was associated with the severity of mycoplasma pneumoniae pneumonia (MPP). But the relationship between IL-27 and MPP was unknown.

Methods

Ninety-eight patients with MPP < 14 years old were enrolled in this study and divided into groups by severity (mild cases and severe cases), infection types (MP single infection group and MP mixed infection group) and DNA loads (low MP DNA loads group and high MP DNA loads group), respectively. Fifteen children with foreign bodies in bronchus were also enrolled as control. IL-6 s and IL-27 s in bronchoalveolar lavage fluids (BALFs) from these children were measured by ELISA.

Results

There were significant differences in IL-6 s of BALFs from patients between mild cases and severe cases, MP single infection group and MP mixed infection group, and low MP DNA loads group and high MP DNA loads group, respectively (P < 0.05). Compared with IL-6 s of BALFs from control, IL-6 s in BALFs from the 6 patient groups were significantly higher (P < 0.05). IL-27 s in BALFs from MP mixed infection group were significantly lower than those from MP single infection group and control (P < 0.05) respectively.

Conclusion

IL-6 was firmly associated with MPP and had potential application in clinical practice while IL-27 was not related to MP infection.

IL-27 and autoimmune rheumatologic diseases: The good, the bad, and the ugly

The footprint of cytokines is evident in almost every biological process, such as development, as well as the pathogenesis of the different diseases, immune responses to pathogens, etc. These small proteins are categorized into different functional classes; for instance, they can play a pro-inflammatory or anti-inflammatory role in different situations, or they can confer a polarization to the immune system. Interleukin (IL)-27 is a member of the IL-12 family. Antigen-presenting cells are the primary source of IL-27 production, which exerts its effects by bindings to the IL-27 receptor expressed on the surface of target cells. Interaction of IL-27 and IL-27 receptor leads to activation of the JAK-STAT and p38 MAPK signaling pathways. Most studies focused on the inflammatory effects of this cytokine, but gradually anti-inflammatory effects were also revealed for this cytokine, which changed the traditional perception of the function of this cytokine. The functionality of IL-27 in the pathogenesis of rheumatic diseases has been attributed to a double-blade sword. Hence, novel therapeutic approaches have been devised targeting IL-12 family that has been accompanied with promising results. In this review, we focused on the inflammatory and anti-inflammatory properties of IL-27 in different autoimmune rheumatologic diseases and its plausible therapeutic potentials.

Decoding the Role of Interleukin-30 in the Crosstalk Between Cancer and Myeloid Cells

In the last few years, a new actor hit the scene of the tumor microenvironment, the p28 subunit of interleukin (IL)-27, known as IL-30. Its molecular structure allows it to function as an autonomous cytokine and, alternatively, to pair with other subunits to form heterodimeric complexes and enables it to play different, and not fully elucidated, roles in immunity. However, data from the experimental models and clinical samples, suggest IL-30′s engagement in the relationship between cancer and myeloid cells, which fosters the tumor microenvironment and the cancer stem cell niche, boosting the disease progression. Activated myeloid cells are the primary cellular source and one of the targets of IL-30, which can also be produced by cancer cells, especially, in aggressive tumors, as observed in the breast and prostate. This review briefly reports on the immunobiology of IL-30 and related cytokines, by comparing mouse and human counterparts, and then focuses on the mechanisms whereby IL-30 amplifies intratumoral myeloid cell infiltrate and triggers a vicious cycle that worsens immunosuppression in the tumor microenvironment (TME) and constitutes a real threat for a successful immunotherapeutic strategy.

IL-27 Counteracts Neuropathic Pain Development Through Induction of IL-10

Neuroimmune–glia interactions have been implicated in the development of neuropathic pain. Interleukin-27 (IL-27) is a cytokine that presents regulatory activity in inflammatory conditions of the central nervous system. Thus, we hypothesized that IL-27 would participate in the neuropathic pain process. Here, we found that neuropathic pain caused by peripheral nerve injury (spared nerve injury model; SNI), was enhanced in IL-27-deficient^(−/−) mice, whereas nociceptive pain is similar to that of wild-type mice. SNI induced an increase in the expression of IL-27 and its receptor subunit (Wsx1) in the sensory ganglia and spinal cord. IL-27 receptor was expressed mainly in resident macrophage, microglia, and astrocytes of the sensory ganglia and spinal cord, respectively. Finally, we identify that the antinociceptive effect of IL-27 was not observed in IL-10^−/− mice. These results provided evidence that IL-27 is a cytokine produced after peripheral nerve injury that counteracts neuropathic pain development through induction of the antinociceptive cytokine IL-10. In summary, our study unraveled the role of IL-27 as a regulatory cytokine that counteracts the development of neuropathic pain after peripheral nerve damage. In conclusion, they indicate that immunotherapies based on IL-27 could emerge as possible therapeutic approaches for the prevention of neuropathic pain development after peripheral nerve injury.

IL-27, IL-30, and IL-35: A Cytokine Triumvirate in Cancer

The role of the immune system in anti-tumor immunity cannot be overstated, as it holds the potential to promote tumor eradication or prevent tumor cell escape. Cytokines are critical to influencing the immune responses and interactions with non-immune cells. Recently, the IL-12 and IL-6 family of cytokines have accumulated newly defined members each with specific immune functions related to various cancers and tumorigenesis. There is a need to better understand how cytokines like IL-27, IL-30, and IL-35 interact with one another, and how a developing tumor can exploit these interactions to enhance immune suppression. Current cytokine-based immunotherapies are associated with cytotoxic side effects which limits the success of treatment. In addition to this toxicity, understanding the complex interactions between immune and cancer cells may be one of the greatest challenges to developing a successful immunotherapy. In this review, we bring forth IL-27, IL-30, and IL-35, “sister cytokines,” along with more recent additions to the IL-12 family, which serve distinct purposes despite sharing structural similarities. We highlight how these cytokines function in the tumor microenvironment by examining their direct effects on cancer cells as well their indirect actions via regulatory functions of immune cells that act to either instigate or inhibit tumor progression. Understanding the context dependent immunomodulatory outcomes of these sister cytokines, as well as their regulation within the tumor microenvironment, may shed light onto novel cancer therapeutic treatments or targets.

IL-17, IL-27, and IL-33: A Novel Axis Linked to Immunological Dysfunction During Sepsis

Sepsis is a major cause of morbidity and mortality worldwide despite numerous attempts to identify effective therapeutics. While some sepsis deaths are attributable to tissue damage caused by inflammation, most mortality is the result of prolonged immunosuppression. Ex vivo, immunosuppression during sepsis is evidenced by a sharp decrease in the production of pro-inflammatory cytokines by T cells and other leukocytes and increased lymphocyte apoptosis. This allows suppressive cytokines to exert a greater inhibitory effect on lymphocytes upon antigen exposure. While some pre-clinical and clinical trials have demonstrated utility in targeting cytokines that promote lymphocyte survival, this has not led to the approval of any therapies for clinical use. As cytokines with a more global impact on the immune system are also altered by sepsis, they represent novel and potentially valuable therapeutic targets. Recent evidence links interleukin (IL)-17, IL-27, and IL-33 to alterations in the immune response during sepsis using patient serum and murine models of peritonitis and pneumonia. Elevated levels of IL-17 and IL-27 are found in the serum of pediatric and adult septic patients early after sepsis onset and have been proposed as diagnostic biomarkers. In contrast, IL-33 levels increase in patient serum during the immunosuppressive stage of sepsis and remain high for more than 5 months after recovery. All three cytokines contribute to immunological dysfunction during sepsis by disrupting the balance between type 1, 2, and 17 immune responses. This review will describe how IL-17, IL-27, and IL-33 exert these effects during sepsis and their potential as therapeutic targets.

The Immunobiology of the Interleukin-12 Family: Room for Discovery

The discovery of interleukin (IL)-6 and its receptor subunits provided a foundation to understand the biology of a group of related cytokines: IL-12, IL-23, and IL-27. These family members utilize shared receptors and cytokine subunits and influence the outcome of cancer, infection, and inflammatory diseases. Consequently, many facets of their biology are being therapeutically targeted. Here, we review the landmark discoveries in this field, the combinatorial biology inherent to this family, and how patient datasets have underscored the critical role of these pathways in human disease. We present significant knowledge gaps, including how similar signals from these cytokines can mediate distinct outcomes, and discuss how a better understanding of the biology of the IL-12 family provides new therapeutic opportunities.

IL-27 Promotes Human Placenta-Derived Mesenchymal Stromal Cell Ability To Induce the Generation of CD4+IL-10+IFN-γ+ T Cells via the JAK/STAT Pathway in the Treatment of Experimental Graft-versus-Host Disease

Human mesenchymal stromal cells (MSCs) harbor immunomodulatory properties to induce the generation of suppressive T cells. MSCs have been successfully used in treating graft-versus-host disease (GVHD) accompanied by abundant inflammatory cytokines such as IL-27. This study investigated the effects of IL-27 on the human placenta-derived MSCs (hPMSCs) to induce generation of CD4⁺IL-10⁺IFN-γ⁺ T cells in vitro and in the humanized xenogenic GVHD NOD/SCID model. The results showed that the percentages of CD4⁺IL-10⁺IFN-γ⁺ T cells were significantly increased in activated human PBMC from both healthy donors and GVHD patients with hPMSCs and in the liver and spleen of hPMSC-treated GVHD mice, and the level of CD4⁺IL-10⁺IFN-γ⁺ T cells in the liver was greater than that in the spleen in hPMSC-treated GVHD mice. The serum level of IL-27 decreased and the symptoms abated in hPMSC-treated GVHD. Further, in vitro results showed that IL-27 promoted the regulatory effects of hPMSCs by enhancing the generation of CD4⁺IL-10⁺IFN-γ⁺ T cells from activated PBMC. Activation occurred through increases in the expression of programmed death ligand 2 (PDL2) in hPMSCs via the JAK/STAT signaling pathway. These findings indicated that hPMSCs could alleviate GVHD mice symptoms by upregulating the production of CD4⁺IL-10⁺IFN-γ⁺ T cells in the spleen and liver and downregulating serum levels of IL-27. In turn, the ability of hPMSCs to induce the generation of CD4⁺IL-10⁺IFN-γ⁺ T cells could be promoted by IL-27 through increases in PDL2 expression in hPMSCs. The results of this study will be of benefit for the application of hPMSCs in clinical trials.

IL-27 and TCR Stimulation Promote T Cell Expression of Multiple Inhibitory Receptors

Inhibitory receptors (IR) are a diverse group of cell surface molecules that modulate T cell activation, but there are gaps in our knowledge of the cell-extrinsic factors that regulate their expression. The present study found that in vivo overexpression of IL-27 in mice led to increased T cell expression of PD-L1, LAG-3, TIGIT, and TIM-3. In vitro, TCR stimulation alone promoted expression of multiple IRs, whereas IL-27 alone induced expression of PD-L1. However, the combination of intermediate TCR stimulation and IL-27 resulted in synergistic induction of LAG-3, CTLA-4, and TIGIT. In vivo, infection with Toxoplasma gondii resulted in parasite-specific effector T cells that expressed high levels of IR, and at local sites of infection where IL-27 production was highest, IL-27 was required for maximal effector cell expression of PD-L1, LAG-3, CTLA-4, and TIGIT. Together, these results affirm the critical role of TCR signals in the induction of IR expression but find that during infection, IL-27 promotes T cell expression of IR.

Preventative tracheal administration of interleukin-27 attenuates allergic asthma by improving the lung Th1 microenvironment

BACKGROUND

Interleukin-27 (IL-27) modulates CD4+ T-cell differentiation and function. The aim of this study is to investigate the effect and molecular mechanisms of IL-27 on the development of asthma.

METHODS

IL-27 was intranasally administered in an ovalbumin-induced asthma model, and lung mononuclear cells and different Th cell classes were detected by fluorescence-activated cell sorting. The effect and mechanisms of IL-27 on human bronchial epithelial (HBE) cells were investigated by measuring changes in chemotactic factors, cytokines, transcription factors, and signaling pathways.

RESULTS

We found that intranasal administration of IL-27 could attenuate airway inflammation and hyperresponsiveness, upregulate the type 1 T helper (Th1)-T memory (Tm) cells and regulatory T (Treg) cells subgroups of lung tissue lymphocytes, and diminish the levels of type 2 T helper (Th2) cytokines. IL-27 upregulated the expression of C-C motif chemokine ligand 2 (CCL2), CCL3, and CCL4 in HBE cells and promoted the production of chemotactic factors to attract monocyte recruitment. Recruited monocytes secondarily secreted IL-27 to influence HBE cells in a positive feedback cycle. After IL-27 intervention, signal transducer and activator of transcription 1 (STAT1) phosphorylation increased, while STAT4 and STAT6 phosphorylation declined.

CONCLUSIONS

Preventative intranasal administration of IL-27 can recruit more IL-27-secreted monocytes to the airway and change the different T-cell classes in lung. The improved Th1 environment helps to alleviate Th2-mediated allergic asthma by repairing the STAT1 pathway but not the STAT4 pathway.

Induction of Tolerogenic Dendritic Cells by Endogenous Biomolecules: An Update

The importance of microenvironment on dendritic cell (DC) function and development has been strongly established during the last two decades. Although DCs with general tolerogenic characteristics have been isolated and defined as a particular sub-population, it is predominantly their unequivocal biological plasticity, which allows for unparalleled responsiveness to environmental ques and shaping of their tolerogenic characteristics when interacting with tolerance-inducing biomolecules. Dendritic cells carry receptors for a great number of endogenous factors, which, after ligation, can importantly influence the development of their activation state. For this there is ample evidence merely by observation of DC characteristics isolated from various anatomical niches, e.g., the greater immunosuppressive potential of DCs isolated from intestine compared to conventional blood DCs. Endogenous biomolecules present in these environments most likely play a major role as a determinant of their phenotype and function. In this review, we will concisely summarize in what way various, tolerance-inducing endogenous factors influence DC biology, the development of their particular tolerogenic state and their subsequent actions in context of immune response inhibition and induction of regulatory T cells.

The TLR7 ligand R848 prevents mouse graft-versus-host disease and cooperates with anti-interleukin-27 antibody for maximal protection and regulatory T-cell upregulation

In spite of considerable therapeutic progress, acute graft-versus-host disease still limits allogeneic hematopoietic cell transplantation. We recently reported that mouse infection with nidovirus lactate dehydrogenase elevating virus impairs disease in non-conditioned B6D2F1 recipients of parental B6 spleen cells. As this virus activates TLR7, we tested a pharmacological TLR7 ligand, R848, in this model and observed complete survival if donor and recipients were treated before transplantation. Mixed lymphocyte culture performed 48 h after R848-treatment of normal mice demonstrated that both T-cell allo-responsiveness and antigen presentation by CD11b⁺ and CD8α⁺ dendritic cells were inhibited. These inhibitions were dependent on IFNAR-1 signaling. In the B6 to B6D2F1 transplantation model, R848 decelerated, but did not abrogate, donor T-cell implantation and activation. However, it decreased interferon-gamma, tumor necrosis factor-alpha and interleukin-27 while upregulating active transforming growth factor-beta 1 plasma levels. In addition, donor and recipient Foxp3⁺ regulatory T-cell numbers were increased in recipient mice and their elimination compromised disease prevention. R848 also strongly improved survival of lethally irradiated BALB/c recipients of B6 hematopoietic cells and this also correlated with an upregulation of CD4 and CD8 Foxp3⁺ regulatory T cells that could be further increased by inhibition of interleukin-27. The combination of anti-interleukin-27p28 mono -clonal antibody and R848 showed strong synergy in preventing disease in the B6 to B6D2F1 transplantation model when recipients were sublethally irradiated and this also correlated with upregulation of regulatory T cells. We conclude that R848 modulates multiple aspects of graft-versus-host disease and offers potential for safe allogeneic bone marrow transplantation that can be further optimized by inhibition of interleukin-27.

Influenza infection directly alters innate IL-23 and IL-12p70 and subsequent IL-17A and IFN-γ responses to pneumococcus in vitro in human monocytes

IMPORTANCE

Influenza virus is highly contagious and poses substantial public health problems due to its strong association with morbidity and mortality. Approximately 250,000-500,000 deaths are caused by seasonal influenza virus annually, and this figure increases during periods of pandemic infections. Most of these deaths are due to secondary bacterial pneumonia. Influenza-bacterial superinfection can result in hospitalisation and/or death of both patients with pre-existing lung disease or previously healthy individuals. The importance of our research is in determining that influenza and its component haemagglutinin has a direct effect on the classic pneumococcus induced pathways to IL-17A in our human ex vivo model. Our understanding of the mechanism which leaves people exposed to influenza infection during superinfection remain unresolved. This paper demonstrates that early infection of monocytes inhibits an arm of immunity crucial to bacterial clearance. Understanding this mechanism may provide alternative interventions in the case of superinfection with antimicrobial resistant strains of bacteria.

Soluble interleukin-27 receptor alpha is a valuable prognostic biomarker for acute graft-versus-host disease after allogeneic haematopoietic stem cell transplantation

Acute graft-versus-host disease (aGVHD) is a major life-threatening complication after allogeneic haematopoietic stem cell transplantation. Interleukin-27 receptor alpha (IL-27Rα) is a co-receptor of IL-27, an inflammatory cytokine that possesses extensive immunological functions. It has been reported that IL-27Rα can exist in its soluble form (sIL-27Rα) in human serum and can function as a natural IL-27 antagonist. In this study, we examined serum sIL-27Rα levels and evaluated their prognostic value in aGVHD. A total of 152 subjects were prospectively recruited and separated into the training group (n = 72) and the validation group (n = 80). Serum sIL-27Rα at neutrophil engraftment was measured by ELISA. In the training set, a cut-off value of sIL-27Rα = 59.40 ng/ml was identified to predict grade II–IV aGVHD (AUC = 0.735, 95% CI 0.618–0.853, P = 0.001). Cumulative incidences of grade II–IV aGVHD (P = 0.004), relapse rate (P = 0.008), and non-relapse mortality (P = 0.008) in patients with low serum sIL-27Rα (≥59.40 ng/ml) were significantly higher than those of patients with high serum sIL-27Rα (<59.40 ng/ml). Multivariate analysis confirmed that low sIL-27Rα level (HR = 2.83 95% CI 1.29–6.19, P < 0.01) was an independent risk factor for predicting grade II-IV aGVHD. In addition, serum sIL-27Rα was positively correlated with IL-27 (R = 0.27, P = 0.029), IL-10 (R = 0.37, P = 0.0015) and HGF (R = 0.27, P = 0.0208), but was negatively correlated with TNFR1 (R = −0.365, P = 0.0022) and ST2 (R = −0.334, P = 0.0041), elafin (R = −0.29, P = 0.0117), and REG3α (R = −0.417, P = 0.0003). More importantly, the threshold value of sIL-27Rα was then validated in an independent cohort of 80 patients (AUC = 0.790, 95% CI 0.688–0.892, P < 0.001). Taken together, our findings suggested that serum sIL-27Rα at neutrophil engraftment maybe a valuable prognostic biomarker in predicting the incidence of moderate-to-severe aGVHD.

Interleukin-27R Signaling Mediates Early Viral Containment and Impacts Innate and Adaptive Immunity after Chronic Lymphocytic Choriomeningitis Virus Infection

Chronic viral infections represent a major challenge to the host immune response, and a unique network of immunological elements, including cytokines, are required for their containment. By using a model persistent infection with the natural murine pathogen lymphocytic choriomeningitis virus clone 13 (LCMV Cl13) we investigated the role of one such cytokine, interleukin-27 (IL-27), in the control of chronic infection. We found that IL-27 receptor (IL-27R) signaling promoted control of LCMV Cl13 as early as days 1 and 5 after infection and that il27p28 transcripts were rapidly elevated in multiple subsets of dendritic cells (DCs) and myeloid cells. In particular, plasmacytoid DCs (pDCs), the most potent type 1 interferon (IFN-I)-producing cells, significantly increased il27p28 in a Toll-like receptor 7 (TLR7)-dependent fashion. Notably, mice deficient in an IL-27-specific receptor, WSX-1, exhibited a pleiotropy of innate and adaptive immune alterations after chronic lymphocytic choriomeningitis virus (LCMV) infection, including compromised NK cell cytotoxicity and antibody responses. While, the majority of these immune alterations appeared to be cell extrinsic, cell-intrinsic IL-27R was necessary to maintain early pDC numbers, which, alongside lower IFN-I transcription in CD11b⁺ DCs and myeloid cells, may explain the compromised IFN-I elevation that we observed early after LCMV Cl13 infection in IL-27R-deficient mice. Together, these data highlight the critical role of IL-27 in enabling optimal antiviral immunity early and late after infection with a systemic persistent virus and suggest that a previously unrecognized positive-feedback loop mediated by IL-27 in pDCs might be involved in this process.

IMPORTANCE Persistently replicating pathogens, such as human immunodeficiency virus, hepatitis B virus, and hepatitis C virus, represent major health problems worldwide. These infections impose a long-term challenge on the host immune system, which must be heavily and continuously regulated to keep pathogen replication in check without causing fatal immunopathology. Using a persistently replicating rodent pathogen, LCMV, in its natural host, we identified the cellular sources and effects of one important regulatory pathway, interleukin-27 receptor WSX-1 signaling, that is required for both very early and late restriction of chronic (but not acute) infection. We found that WSX-1 was necessary to promote innate immunity and the development of aberrant adaptive immune responses. This not only highlights the role of IL-27 receptor signaling in regulating distinct host responses that are known to be necessary to control chronic infections, but also positions IL-27 as a potential therapeutic target for their modulation.

Differing Outcome of Experimental Autoimmune Encephalitis in Macrophage/Neutrophil- and T Cell-Specific gp130-Deficient Mice

gp130 cytokines are differentially involved in regulating the T helper (H) 17-driven pathogenesis of experimental autoimmune encephalomyelitis (EAE), the animal model of human multiple sclerosis. Interleukin (IL)-6 directly promotes the development of TH17 cells through the gp130/IL-6R complex. By contrast, IL-27 has been shown to suppress a TH17 immune response by gp130/IL-27R-alpha (α) receptor ligation. The IL-27-dependent regulation of a TH17 development could be mediated on the level of CD4 T cells. However, because IL-27 also suppresses the secretion of the TH17-driving cytokines IL-6 and IL-12/23p40 in accessory cells, TH17 immune responses may also be controlled by IL-27 on the level of macrophages and/or neutrophils. To analyze these opposing effects of gp130 engagement on the pathogenesis of EAE, we immunized CD4⁺ T cell-specific gp130-deficient (CD4cre^posgp130^loxP/loxP) and macrophage/neutrophil-specific gp130-deficient (LysMcre^posgp130^loxP/loxP) mice with the myelin-oligodendrocyte-glycoprotein peptide MOG_35-55. Whereas inflammatory immune responses, TH17 differentiation, and pathology in CD4cre^posgp130^loxP/loxP mice were mitigated, disease progression was eventually enhanced in LysMcre^posgp130^loxP/loxP mice. Exacerbated disease in MOG_35-55-immunized LysMcre^posgp130^loxP/loxP mice was associated with an elevated development of TH17 cells and increased infiltration of the central nervous system with leukocytes indicating a suppressive role of macrophage/neutrophil-gp130. To further prove IL-6 to be responsible for the control of inflammation during EAE through gp130 on macrophages/neutrophils, we immunized LysMcre^posIL-6R^loxP/loxP mice. In contrast to LysMcre^posgp130^loxP/loxP mice, neuropathology in MOG_35-55-immunized macrophage/neutrophil-specific IL-6R-deficient mice was not enhanced indicating that the alleviation of EAE through macrophage/neutrophil-gp130 is mediated independently of IL-6. Together, this different pathology in macrophage/neutrophil- and CD4 T cell-specific gp130-deficient mice suggests that gp130 cytokines modulate TH17 inflammation differentially by targeting distinct cell types.

IL-27 regulates the adherence, proliferation, and migration of MSCs and enhances their regulatory effects on Th1 and Th2 subset generations

Interleukin 27 (IL-27) regulates T cell function and is involved in inflammation. It has been reported that human placenta-derived mesenchymal stromal cells (hPMSCs) can inhibit T cell responses and attenuate inflammation reactions. However, it is unclear whether IL-27 can regulate hPMSC function. Here, we examined the effects of IL-27 upon adherence, migration, and proliferation as well as the immunomodulatory effects of hPMSCs. The results show that IL-27 receptor α chain (IL-27Rα) is expressed in hPMSCs. IL-27 at 30 ng/ml inhibited hPMSC adherence and proliferation, while the migration of hPMSCs was promoted with IL-27 at doses of 20 or 30 ng/ml, as determined with use of real-time cell analysis (RTCA). Moreover, IL-27 promoted regulatory effects of hPMSCs through enhancing Th2 and suppressing Th1 subset generation from activated T cells in human peripheral blood. IL-27 also enhanced the ability of hPMSCs to secrete IL-10 from CD4⁺T cells through increased expression levels of the programmed death ligand 1 (PDL1) in hPMSCs via the Janus kinase (JAK)/signal transducer and activator of transcription 1 (STAT1) signaling pathway. In conclusion, IL-27 has significant modulatory effects on adherence, proliferation, and migration of hPMSCs. IL-27 increased PDL1 expression levels in hPMSCs via the JAK/STAT1 pathway, which then enhanced the regulatory effects of hPMSCs upon Th1 and Th2 cell generations and IL-10 secretion from CD4⁺T cells.

Cytokine- and TCR-Mediated Regulation of T Cell Expression of Ly6C and Sca-1

Ly6C and Sca-1 (Ly6A/E) are Ly6 family GPI-anchored surface molecules that are differentially expressed by multiple immune populations. Ly6C expression has been used to distinguish short-lived effector CD4⁺ T cells from memory precursor effector cells, whereas Sca-1 has been used in the identification of CD8⁺ memory stem cells. This study examines the expression patterns of these molecules and establishes that, in vitro, IL-27, type I IFN, and IFN-γ are potent inducers of Ly6C and Sca-1 in naive mouse CD4⁺ and CD8⁺ T cells, whereas TGF-β limits their expression. The induction of Ly6C and Sca-1 by IL-27 and IFN-γ is dependent on STAT1, but not STAT3 or T-bet. In mouse splenocytes, at homeostasis, Ly6C and Sca-1 expression was not restricted to effector cells, but was also found at various levels on naive and memory populations. However, in response to infection with Toxoplasma gondii, pathogen-specific T cells expressed high levels of these molecules and in this context, endogenous IL-27 and IFN-γ were required for the expression of Ly6C but not Sca-1. Together, these findings highlight the TCR-dependent and cytokine-mediated signals that modulate T cell expression of Ly6C and Sca-1 in vitro and in vivo during infection.

IL-27p28 Production by XCR1+ Dendritic Cells and Monocytes Effectively Predicts Adjuvant-Elicited CD8+ T Cell Responses

It is well accepted that the innate response is a necessary prerequisite to the formation of the adaptive response. This is true for T cell responses against infections or adjuvanted subunit vaccination. However, specific innate parameters with predictive value for the magnitude of an adjuvant-elicited T cell response have yet to be identified. We previously reported how T cell responses induced by subunit vaccination were dependent on the cytokine IL-27. These findings were unexpected, given that T cell responses to an infection typically increase in the absence of IL-27. Using a novel IL-27p28-eGFP reporter mouse, we now show that the degree to which an adjuvant induces IL-27p28 production from dendritic cells and monocytes directly predicts the magnitude of the T cell response elicited. To our knowledge, these data are the first to identify a concrete innate correlate of vaccine-elicited cellular immunity, and they have significant practical and mechanistic implications for subunit vaccine biology.

Cytokines in the pathogenesis of rheumatoid arthritis: new players and therapeutic targets

In recent years, the landscape of pro- and anti-inflammatory cytokines has rapidly expanded with the identification of new members proven to be involved at different extent in the pathogenesis of chronic immune mediated inflammatory diseases including rheumatoid arthritis (RA). The advance of our understanding of mediators involved in the pathogenesis of RA and in consequence, the development of novel targeted therapies is necessary to provide patients not responding to currently available strategies with novel compounds. The aim of this review article is to provide an overview on recently identified cytokines, emphasizing their pathogenic role and therapeutic potential in RA. A systematic literature review was performed to retrieve articles related to every cytokine discussed in the review. In some cases, evidence from animal models and RA patients is already consistent to move forward into drug development. In others, conflicting observation and the paucity of data require further investigations.Forty years after the discovery of IL-1, the landscape of cytokines is continuously expanding with increasing possibilities to develop novel therapeutic strategies in RA.

Protective function of interleukin 27 in colitis-associated cancer via suppression of inflammatory cytokines in intestinal epithelial cells

Numerous studies have demonstrated that inflammation contributes to a variety of cancer formation, among them, colitis-associated cancer (CAC) represents a typical inflammation-related cancer. Interleukin 27 (IL-27) has been demonstrated to play an important role in inflammation-related disease. The effect of IL-27 in intestinal inflammation is controversial and its role in CAC is not elucidated yet. In our present study, we found that IL-27 has protective function in murine model of CAC through suppression of inflammatory cytokines in intestinal epithelial cells (IECs). IL-27Rα (WSX-1) deficiency promotes the CAC development in mice, which is driven by enhanced tumor cell proliferation, more intensive myeloid-derived suppressor cells (MDSC) accumulation in colon lamina propria and higher level of inflammatory cytokines and chemokines in IECs. The levels of IL-6, TNF-α, GM-CSF and CXCL1 triggered in vitro by toll-like receptor ligands are significantly upregulated in IECs from WSX-1 KO mice. Removal of commensal microorganism through antibiotic treatment in mice to eliminate TLR ligands deprives the protective function of IL-27 on CAC tumor growth. Thus, IL-27 suppresses CAC formation through an anti-inflammation mechanism targeting IECs and in turn resists the tumorigenesis. Hence, our study explained how IL-27 exerts its anti-inflammatory function on epithelial cells to fight against chronic-inflammation-associated cancer, which might provide new insights on the potential therapeutic strategies for cancer.

Prostaglandin E2 Inhibition of IL-27 Production in Murine Dendritic Cells: A Novel Mechanism That Involves IRF1

IL-27, a multifunctional cytokine produced by APCs, antagonizes inflammation by affecting conventional dendritic cells (cDC), inducing IL-10, and promoting development of regulatory Tr1 cells. Although the mechanisms involved in IL-27 induction are well studied, much less is known about the factors that negatively impact IL-27 expression. PGE₂, a major immunomodulatory prostanoid, acts as a proinflammatory agent in several models of inflammatory/autoimmune disease, promoting primarily Th17 development and function. In this study, we report on a novel mechanism that promotes the proinflammatory function of PGE₂ We showed previously that PGE₂ inhibits IL-27 production in murine bone marrow-derived DCs. In this study, we show that, in addition to bone marrow-derived DCs, PGE₂ inhibits IL-27 production in macrophages and in splenic cDC, and we identify a novel pathway consisting of signaling through EP2/EP4→induction of cAMP→downregulation of IFN regulatory factor 1 expression and binding to the p28 IFN-stimulated response element site. The inhibitory effect of PGE₂ on p28 and irf1 expression does not involve endogenous IFN-β, STAT1, or STAT2, and inhibition of IL-27 does not appear to be mediated through PKA, exchange protein activated by cAMP, PI3K, or MAPKs. We observed similar inhibition of il27p28 expression in vivo in splenic DC following administration of dimethyl PGE₂ in conjunction with LPS. Based on the anti-inflammatory role of IL-27 in cDC and through the generation of Tr1 cells, we propose that the PGE₂-induced inhibition of IL-27 in activated cDC represents an important additional mechanism for its in vivo proinflammatory functions.

Cigarette Smoke Induction of Interleukin-27/WSX-1 Regulates the Differentiation of Th1 and Th17 Cells in a Smoking Mouse Model of Emphysema

IFN-γ-producing CD4⁺ T (Th1) cells and IL-17-producing CD4⁺ T (Th17) cells play a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the immune regulation between Th1 and Th17 cells remains unclear. Previous studies have demonstrated that interleukin-27 (IL-27)/WSX-1 exerted pro- or anti-inflammatory effects in many acute inflammatory diseases by modulating T cell-mediated immune response, but little was known about its role in chronic inflammatory disease, especially in smoking-related lung diseases. Considering IL-27 is an important regulator in T lymphocytes immune responses and was found markedly increased in patients with COPD, we hypothesized that IL-27/WSX-1 may exert immuno-regulatory effects on the differentiation of Th1 and Th17 cells in smoking-related COPD. In this study, we aimed to evaluate the expression of IL-27 in patients with COPD and explore the role of IL-27/WSX-1 on Th1 and Th17 cells differentiation in a smoking mouse model of emphysema. We found that elevated expression of IL-27 was associated with increased proportion of Th1 cells and Th17 cells in patients with COPD and demonstrated parallel findings in cigarette smoke-exposed mice. In addition, cigarette smoke exposure upregulated the expression of IL-27R (WSX-1) by naive CD4⁺ T cells in mice. In vitro, IL-27 significantly augmented the secretion of IFN-γ by naive CD4⁺ T cells via a T-bet, p-STAT1, and p-STAT3-dependent manner, but inhibited the production of IL-17 by a ROR-γt and p-STAT1-dependent way. Furthermore, anti-IL27 treatment dramatically decreased the expression of IFN-γ-producing CD4⁺ T cells in cigarette smoke-exposed mice. These findings proposed that IL-27 has functions for promoting the expression of Th1 cells but inhibiting the expression of Th17 cells in vitro and IL-27 neutralization-attenuated Th1-mediated inflammation in vivo, suggesting targeting IL-27/WSX-1 may provide a new therapeutic approach for smoking-related COPD.

High Interleukin 27 Production is Associated with Early Clinical Stage and Localized Disease in Patients with Melanoma

BACKGROUND

The immune response in patients with melanoma is an important focus of research due to the tumor's resistance and immunotherapy possibilities. IL-27 is one of the cytokines with antitumor properties. The role of IL-27 in the pathogenesis of melanoma is still unclear. The aim of this study was to examine the association between serum IL-27 levels and the clinical parameters of melanoma patients.

METHODS

The IL-27 concentration was determined by com mercial ELISA in serum samples from melanoma patients (n=72) and healthy control subjects (n=44). Patients were classified according to AJCC clinical stage, TNM stage, the length of progression-free interval (PFI) and the extent of the disease (localized or widespread).

RESULTS

Average IL-27 values were increased in patients with early stages of melanoma compared to patients with terminal stages and control values. The highest IL-27 concentration was found in stage IIa. Patients in stages III and IV had significantly lower values of IL-27 compared to control. Patients with localized melanoma and shorter PFI had insignificantly increased IL-27 levels compared to patients with widespread disease and longer PFI. Patients with metastatic disease and stage TNM4 had significantly lower average IL-27 values compared to control. Patients with high production of IL-27 (>1000 pg/mL) were most numerous in IIa AJCC stage, with initial tumor size TNM2 and in the group of patients with localized disease.

CONCLUSIONS

High levels of IL-27 in patients with melanoma are associated with the initial stages and lo calized disease.

Interleukin-27 as a Novel Therapy for Inflammatory Bowel Disease: A Critical Review of the Literature

Inflammatory bowel disease (IBD) is an inflammatory disorder of the intestine that affects an estimated 329 per 100,000 people in the United States and is increasing in incidence within a number of cultures worldwide. Likely due to its incompletely understood pathophysiology and etiology, the standard treatments for IBD are only efficacious in subsets of patients and often do not induce lasting remission. As a result, novel therapies are needed. The success of anti-tumor necrosis factor-α treatment in a subset of patients with IBD demonstrated that therapy targeting a single cytokine could be efficacious in IBD, and clinical trials investigating the blockade of a variety of cytokines have commenced. Interleukin (IL) 27 is a relatively recently discovered type I cytokine with established roles in infectious disease, autoimmunity, and cancer in a variety of organs. IL-27 was identified as a candidate gene for IBD, and a number of studies in mouse models of IBD have demonstrated that IL-27 therapy is protective. However, in contrast to these investigations, genetic deletion of the IL-27 receptor has been shown to be protective in some mouse models of IBD. The purpose of this review is to highlight the recent literature investigating the role of IL-27 in IBD and to discuss the possible explanations for the sometimes conflicting results of these studies. Evidence supporting IL-27 therapy as a treatment for IBD will also be discussed.

Blockade of interleukin-27 signaling reduces GVHD in mice by augmenting Treg reconstitution and stabilizing Foxp3 expression

Reestablishment of competent regulatory pathways has emerged as a strategy to reduce the severity of graft-versus-host disease (GVHD), and recalibrate the effector and regulatory arms of the immune system. However, clinically feasible, cost-effective strategies that do not require extensive ex vivo cellular manipulation have remained elusive. In the current study, we demonstrate that inhibition of the interleukin-27p28 (IL-27p28) signaling pathway through antibody blockade or genetic ablation prevented lethal GVHD in multiple murine transplant models. Moreover, protection from GVHD was attributable to augmented global reconstitution of CD4⁺ natural regulatory T cells (nTregs), CD4⁺ induced Tregs (iTregs), and CD8⁺ iTregs, and was more potent than temporally concordant blockade of IL-6 signaling. Inhibition of IL-27p28 also enhanced the suppressive capacity of adoptively transferred CD4⁺ nTregs by increasing the stability of Foxp3 expression. Notably, blockade of IL-27p28 signaling reduced T-cell-derived-IL-10 production in conventional T cells; however, there was no corresponding effect in CD4⁺ or CD8⁺ Tregs, indicating that IL-27 inhibition had differential effects on IL-10 production and preserved a mechanistic pathway by which Tregs are known to suppress GVHD. Targeting of IL-27 therefore represents a novel strategy for the in vivo expansion of Tregs and subsequent prevention of GVHD without the requirement for ex vivo cellular manipulation, and provides additional support for the critical proinflammatory role that members of the IL-6 and IL-12 cytokine families play in GVHD biology.

Production of IL-27 in multiple sclerosis lesions by astrocytes and myeloid cells: Modulation of local immune responses

The mechanisms whereby human glial cells modulate local immune responses are not fully understood. Interleukin-27 (IL-27), a pleiotropic cytokine, has been shown to dampen the severity of experimental autoimmune encephalomyelitis, but it is still unresolved whether IL-27 plays a role in the human disease multiple sclerosis (MS). IL-27 contribution to local modulation of immune responses in the brain of MS patients was investigated. The expression of IL-27 subunits (EBI3 and p28) and its cognate receptor IL-27R (the gp130 and TCCR chains) was elevated within post-mortem MS brain lesions compared with normal control brains. Moreover, astrocytes (GFAP(+) cells) as well as microglia and macrophages (Iba1(+) cells) were important sources of IL-27. Brain-infiltrating CD4 and CD8 T lymphocytes expressed the IL-27R specific chain (TCCR) implying that these cells could respond to local IL-27 sources. In primary cultures of human astrocytes inflammatory cytokines increased IL-27 production, whereas myeloid cell inflammatory M1 polarization and inflammatory cytokines enhanced IL-27 expression in microglia and macrophages. Astrocytes in postmortem tissues and in vitro expressed IL-27R. Moreover, IL-27 triggered the phosphorylation of the transcription regulator STAT1, but not STAT3 in human astrocytes; indeed IL-27 up-regulated MHC class I expression on astrocytes in a STAT1-dependent manner. These findings demonstrated that IL-27 and its receptor were elevated in MS lesions and that local IL-27 can modulate immune properties of astrocytes and infiltrating immune cells. Thus, therapeutic strategies targeting IL-27 may influence not only peripheral but also local inflammatory responses within the brain of MS patients.

Interleukin-27: a novel biomarker in predicting bacterial infection among the critically ill

Introduction

A continued need exists for effective diagnostic biomarkers in bacterial sepsis among critically ill patients, despite increasing use of available biomarkers such as procalcitonin (PCT). Interleukin-27 (IL-27) has shown early promise in a recent preliminary study, exhibiting high specificity and positive predictive values for bacterial infection in critically ill children. This validation study was performed to assess the value of IL-27 in predicting bacterial infection among patients admitted to the pediatric intensive care unit and to compare its performance with that of PCT.

Methods

A single-center (n = 702) prospective study was performed comparing both IL-27 and PCT levels between bacterially infected and uninfected cohorts in the pediatric intensive care unit. Infected status was determined by a chart review by an intensivist blinded to biomarker results. Formal performance comparisons included calculations of receiver operating characteristic (ROC) curves for IL-27 and PCT individually in addition to a combination strategy using a decision tree generated by classification and regression tree (CART) methodology. Secondary analysis focusing on subjects with documented bloodstream infections was performed.

Results

The overall infection rate was 27 %. ROC curves for the primary analysis yielded areas under the curve (AUCs) of 0.64 (0.59 to 0.68) for IL-27 and 0.61 (0.56 to 0.65) for PCT. Secondary analysis defining infected status exclusively through positive blood cultures yielded AUCs of 0.75 (0.68 to 0.81) for IL-27 and 0.64 (0.57 to 0.71) for PCT, with a specificity of 95 % (92 % to 97 %) for the prior established IL-27 cut-point value of at least 5.0 ng/ml. Similar AUCs were found for the subset of immunocompromised patients. In a CART-derived analysis taking immunocompromised status into consideration, a combination of IL-27 and PCT yielded an AUC of 0.81 (0.75 to 0.86), statistically improved from either IL-27 or PCT alone.

Conclusions

Despite having a modest predictive value for infection independent of source, IL-27 may serve as a useful biomarker in estimating risk of bacterial infection among critically ill pediatric patients with bloodstream infections. In particular, among immunocompromised subjects, this diagnostic biomarker may be helpful either alone or using a combination strategy with other available biomarkers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1095-2) contains supplementary material, which is available to authorized users.

The biology of interleukin-27 reveals unique pro- and anti-inflammatory functions in immunity

Interleukin (IL)-27 is a multifaceted heterodimeric cytokine with pronounced pro- and anti-inflammatory as well as immunoregulatory functions. It consists of the two subunits p28/IL-30 and Epstein Bar virus-induced protein 3 (EBI3). EBI3 functions as a soluble α-receptor, and IL-27 can therefore directly activate its target cells through a heterodimer of glycoprotein 130 (gp130) and WSX-1. Being a heterodimeric cytokine that signals through gp130, IL-27 is either grouped into the IL-6 or the IL-12 family of cytokines. Originally identified as an IL-12-like cytokine that induces proliferation of CD4+ T cells and production of IFN-γ more than ten years ago, subsequent research revealed a much broader role of IL-27 in inflammation, cancer development and regulation and differentiation of immune cells. In this review, we summarize the current biochemical and molecular knowledge about the signal transduction of IL-27. Based on this, we highlight functional overlaps and plasticity with other cytokines and cytokine receptors of the IL-6/IL-12 superfamily, and describe the important role of IL-27 with regard to the differentiation of T cells, infections and cancer development. We further discuss IL-27 as a therapeutic target and how specific blockade of this cytokine could be achieved.