Interleukin-22: a potential immunomodulatory molecule in the lung

Proteomic aptamer analysis reveals serum biomarkers associated with disease mechanisms and phenotypes of systemic sclerosis

Background

Systemic sclerosis (SSc) is an autoimmune connective tissue disease that affects multiple organs, leading to elevated morbidity and mortality with limited treatment options. The early detection of organ involvement is challenging as there is currently no serum marker available to predict the progression of SSc. The aptamer technology proteomic analysis holds the potential to correlate SSc manifestations with serum proteins up to femtomolar concentrations.

Methods

This is a two-tier study of serum samples from women with SSc (including patients with interstitial lung disease - ILD - at high-resolution CT scan) and age-matched healthy controls (HC) that were first analyzed with aptamer-based proteomic analysis for over 1300 proteins. Proposed associated proteins were validated by ELISA first in an independent cohort of patients with SSc and HC, and selected proteins subject to further validation in two additional cohorts.

Results

The preliminary aptamer-based proteomic analysis identified 33 proteins with significantly different concentrations in SSc compared to HC sera and 9 associated with SSc-ILD, including proteins involved in extracellular matrix formation and cell-cell adhesion, angiogenesis, leukocyte recruitment, activation, and signaling. Further validations in independent cohorts ultimately confirmed the association of specific proteins with early SSc onset, specific organ involvement, and serum autoantibodies.

Conclusions

Our multi-tier proteomic analysis identified serum proteins discriminating patients with SSc and HC or associated with different SSc subsets, disease duration, and manifestations, including ILD, skin involvement, esophageal disease, and autoantibodies.

T cells in idiopathic pulmonary fibrosis: crucial but controversial

Idiopathic pulmonary fibrosis (IPF) has been extensively studied in recent decades due to its rising incidence and high mortality. Despite an abundance of research, the mechanisms, immune-associated mechanisms, of IPF are poorly understood. While defining immunopathogenic mechanisms as the primary pathogenesis is controversial, recent studies have verified the contribution of the immune system to the fibrotic progression of IPF. Extensive evidence has shown the potential role of T cells in fibrotic progression. In this review, we emphasize the features of T cells in IPF and highlight the controversial roles of different subtypes of T cells or even two distinct effects of one type of T-cell in diverse settings, and multiple chemokines and cell products are discussed. Furthermore, we discuss the potential development of treatments targeting the immune molecules of T cells and the feasibility of immune therapies for IPF in clinical practice.

Astegolimab or Efmarodocokin Alfa in Patients With Severe COVID-19 Pneumonia: A Randomized, Phase 2 Trial

OBJECTIVES

Severe cases of COVID-19 pneumonia can lead to acute respiratory distress syndrome (ARDS). Release of interleukin (IL)-33, an epithelial-derived alarmin, and IL-33/ST2 pathway activation are linked with ARDS development in other viral infections. IL-22, a cytokine that modulates innate immunity through multiple regenerative and protective mechanisms in lung epithelial cells, is reduced in patients with ARDS. This study aimed to evaluate safety and efficacy of astegolimab, a human immunoglobulin G2 monoclonal antibody that selectively inhibits the IL-33 receptor, ST2, or efmarodocokin alfa, a human IL-22 fusion protein that activates IL-22 signaling, for treatment of severe COVID-19 pneumonia.

DESIGN

Phase 2, double-blind, placebo-controlled study (COVID-astegolimab-IL).

SETTING

Hospitals.

PATIENTS

Hospitalized adults with severe COVID-19 pneumonia.

INTERVENTIONS

Patients were randomized to receive IV astegolimab, efmarodocokin alfa, or placebo, plus standard of care. The primary endpoint was time to recovery, defined as time to a score of 1 or 2 on a 7-category ordinal scale by day 28.

MEASUREMENTS AND MAIN RESULTS

The study randomized 396 patients. Median time to recovery was 11 days (hazard ratio [HR], 1.01 d; p = 0.93) and 10 days (HR, 1.15 d; p = 0.38) for astegolimab and efmarodocokin alfa, respectively, versus 10 days for placebo. Key secondary endpoints (improved recovery, mortality, or prevention of worsening) showed no treatment benefits. No new safety signals were observed and adverse events were similar across treatment arms. Biomarkers demonstrated that both drugs were pharmacologically active.

CONCLUSIONS

Treatment with astegolimab or efmarodocokin alfa did not improve time to recovery in patients with severe COVID-19 pneumonia.

Lack of Association of Polymorphisms in IL22 and IL22RA1 Genes with Fibrosis Severity in Patients with Chronic Hepatitis C

The IL-22 pathway has been shown to play an important role in the pathogenesis of liver fibrosis. However, little is known about the role of single-nucleotide polymorphisms (SNPs) in IL-22-related genes in relation to the severity of liver fibrosis. This study aimed to investigate the association of polymorphisms in IL22 and IL22RA1 genes with the severity of liver fibrosis in patients with chronic hepatitis C. A total of 326 patients (165 with mild fibrosis and 161 with severe fibrosis) were included. Four SNPs in IL22 (rs1179251, rs2227473, rs1012356, and rs2227485) and two in IL22RA1 (rs4648936 and rs3795299) were evaluated by real-time PCR. No significant association was observed between the polymorphisms studied and the severity of liver fibrosis. The SNPs rs1179251, rs2227473, rs1012356, and rs2227485 in IL22 and rs4648936 and rs3795299 in IL22RA1 may not be involved in the pathogenesis of liver fibrosis in patients with chronic hepatitis C.

Characterization of Mycobacterium tuberculosis-Specific Th22 Cells and the Effect of Tuberculosis Disease and HIV Coinfection

The development of a highly effective tuberculosis (TB) vaccine is likely dependent on our understanding of what constitutes a protective immune response to TB. Accumulating evidence suggests that CD4+ T cells producing IL-22, a distinct subset termed "Th22" cells, may contribute to protective immunity to TB. Thus, we characterized Mycobacterium tuberculosis-specific Th22 (and Th1 and Th17) cells in 72 people with latent TB infection or TB disease, with and without HIV-1 infection. We investigated the functional properties (IFN-γ, IL-22, and IL-17 production), memory differentiation (CD45RA, CD27, and CCR7), and activation profile (HLA-DR) of M. tuberculosis-specific CD4+ T cells. In HIV-uninfected individuals with latent TB infection, we detected abundant circulating IFN-γ-producing CD4+ T cells (median, 0.93%) and IL-22-producing CD4+ T cells (median, 0.46%) in response to M. tuberculosis The frequency of IL-17-producing CD4+ T cells was much lower, at a median of 0.06%. Consistent with previous studies, IL-22 was produced by a distinct subset of CD4+ T cells and not coexpressed with IL-17. M. tuberculosis-specific IL-22 responses were markedly reduced (median, 0.08%) in individuals with TB disease and HIV coinfection compared with IFN-γ responses. M. tuberculosis-specific Th22 cells exhibited a distinct memory and activation phenotype compared with Th1 and Th17 cells. Furthermore, M. tuberculosis-specific IL-22 was produced by conventional CD4+ T cells that required TCR engagement. In conclusion, we confirm that Th22 cells are a component of the human immune response to TB. Depletion of M. tuberculosis-specific Th22 cells during HIV coinfection may contribute to increased risk of TB disease.

IL-22 regulates inflammatory responses to agricultural dust-induced airway inflammation

IL-22 is a unique cytokine that is upregulated in many chronic inflammatory diseases, including asthma, and modulates tissue responses during inflammation. However, the role of IL-22 in the resolution of inflammation and how this contributes to lung repair processes are largely unknown. Here, we tested the hypothesis that IL-22 signaling is critical in inflammation resolution after repetitive exposure to agricultural dust. Using an established mouse model of organic dust extract-induced lung inflammation, we found that IL-22 knockout mice have an enhanced response to agricultural dust as evidenced by an exacerbated increase in infiltrating immune cells and lung pathology as compared to wild-type controls. We further identified that, in response to dust, IL-22 is expressed in airway epithelium and in Ym1+ macrophages found within the parenchyma in response to dust. The increase in IL-22 expression was accompanied by increases in IL-22 receptor IL-22R1 within the lung epithelium. In addition, we found that alveolar macrophages in vivo as well as THP-1 cells in vitro express IL-22, and this expression is modulated by dust exposure. Furthermore, subcellular localization of IL-22 appears to be in the Golgi of resting THP1 human monocytes, and treatment with dust extracts is associated with IL-22 release into the cytosolic compartment from the Golgi reservoirs during dust extract exposure. Taken together, we have identified a significant role for macrophage-mediated IL-22 signaling that is activated in dust-induced lung inflammation in mice.

Distinct Expression Patterns of Interleukin-22 Receptor 1 on Blood Hematopoietic Cells in SARS-CoV-2 Infection

The new pandemic virus SARS-CoV-2 is characterized by uncontrolled hyper-inflammation in severe cases. As the IL-22/IL-22R1 axis was reported to be involved in inflammation during viral infections, we characterized the expression of IL-22 receptor1, IL-22 and IL-22 binding protein in COVID-19 patients. Blood samples were collected from 19 non-severe and 14 severe patients on the day they presented (D0), at D14, and six months later, and from 6 non-infected controls. The IL-22R1 expression was characterized by flow cytometry. Results were related to HLA-DR expression of myeloid cells, to plasma concentrations of different cytokines and chemokines and NK cells and T lymphocytes functions characterized by their IFN-γ, IL-22, IL-17A, granzyme B and perforin content. The numbers of IL-22R1⁺ classical, intermediate, and non-classical monocytes and the proportions of IL-22R1⁺ plasmacytoid DC (pDC), myeloid DC1 and DC2 (mDC1, mDC2) were higher in patients than controls at D0. The proportions of IL-22R1⁺ classical and intermediate monocytes, and pDC and mDC2 remained high for six months. High proportions of IL-22R1⁺ non-classical monocytes and mDC2 displayed HLA-DR^high expression and were thus activated. Multivariate analysis for all IL-22R1⁺ myeloid cells discriminated the severity of the disease (AUC=0.9023). However, correlation analysis between IL-22R1⁺ cell subsets and plasma chemokine concentrations suggested pro-inflammatory effects of some subsets and protective effects of others. The numbers of IL-22R1⁺ classical monocytes and pDC were positively correlated with pro-inflammatory chemokines MCP-1 and IP-10 in severe infections, whereas IL-22R1⁺ intermediate monocytes were negatively correlated with IL-6, IFN-α and CRP in non-severe infections. Moreover, in the absence of in vitro stimulation, NK and CD4⁺ T cells produced IFN-γ and IL-22, and CD4⁺ and CD8⁺ T cells produced IL-17A. CD4⁺ T lymphocytes also expressed IL-22R1, the density of its expression defining two different functional subsets. In conclusion, we provide the first evidence that SARS-CoV-2 infection is characterized by an abnormal expression of IL22R1 on blood myeloid cells and CD4⁺ T lymphocytes. Our results suggest that the involvement of the IL-22R1/IL-22 axis could be protective at the beginning of SARS-CoV-2 infection but could shift to a detrimental response over time.

Chronic Inflammation as the Underlying Mechanism of the Development of Lung Diseases in Psoriasis: A Systematic Review

Psoriasis is a systemic inflammatory disease caused by dysfunctional interactions between the innate and adaptive immune responses. The systemic inflammation in psoriasis may be associated with the development of comorbidities, including lung diseases. In this review, we aimed to provide a summary of the evidence regarding the prevalence of lung diseases in patients with psoriasis and the potential underlying mechanisms. Twenty-three articles published between March 2010 and June 2021 were selected from 195 initially identified records. The findings are discussed in terms of the prevalence of asthma, chronic obstructive pulmonary disease, interstitial lung disease, obstructive sleep apnea, pulmonary hypertension, and sarcoidosis in psoriasis. A higher prevalence of lung diseases in psoriasis has been confirmed in asthma, chronic obstructive pulmonary disease, obstructive sleep apnea, and pulmonary hypertension. These conditions are important as they are previously unrecognized causes of morbidity and mortality in psoriasis. The development of lung diseases in patients with psoriasis can be explained by several mechanisms, including common risk factors, shared immune and molecular characteristics associated with chronic inflammation, as well as other mechanisms. Understanding the prevalence of lung diseases in psoriasis and their underlying mechanisms can help implement appropriate preventative and therapeutic strategies to address respiratory diseases in patients with psoriasis.

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.

Molecular Response to Nanopatterned Implants in the Human Jaw Bone

Implant surface modification by nanopatterning is an interesting route for enhancing osseointegration in humans. Herein, the molecular response to an intentional, controlled nanotopography pattern superimposed on screw-shaped titanium implants is investigated in human bone. When clinical implants are installed, additional two mini-implants, one with a machined surface (M) and one with a machined surface superimposed with a hemispherical nanopattern (MN), are installed in the posterior maxilla. In the second-stage surgery, after 6-8 weeks, the mini-implants are retrieved by unscrewing, and the implant-adherent cells are subjected to gene expression analysis using quantitative polymerase chain reaction (qPCR). Compared to those adherent to the machined (M) implants, the cells adherent to the nanopatterned (MN) implants demonstrate significant upregulation (1.8- to 2-fold) of bone-related genes (RUNX2, ALP, and OC). No significant differences are observed in the expression of the analyzed inflammatory and remodeling genes. Correlation analysis reveals that older patient age is associated with increased expression of proinflammatory cytokines (TNF-α and MCP-1) on the machined implants and decreased expression of pro-osteogenic factor (BMP-2) on the nanopatterned implants. Controlled nanotopography, in the form of hemispherical 60 nm protrusions, promotes gene expressions related to early osteogenic differentiation and osteoblastic activity in implant-adherent cells in the human jaw bone.

Role of interleukins in the pathogenesis of pulmonary fibrosis

Interleukins, a group of cytokines participating in inflammation and immune response, are proved to be involved in the formation and development of pulmonary fibrosis. In this article, we reviewed the relationship between interleukins and pulmonary fibrosis from the clinical, animal, as well as cellular levels, and discussed the underlying mechanisms in vivo and in vitro. Despite the effects of interleukin-targeted treatment on experimental pulmonary fibrosis, clinical applications are lacking and unsatisfactory. We conclude that intervening in one type of interleukins with similar functions in IPF may not be enough to stop the development of fibrosis as it involves a complex network of regulation mechanisms. Intervening interleukins combined with other existing therapy or targeting interleukins affecting multiple cells/with different functions at the same time may be one of the future directions. Furthermore, the intervention time is critical as some interleukins play different roles at different stages. Further elucidation on these aspects would provide new perspectives on both the pathogenesis mechanism, as well as the therapeutic strategy and drug development.

A Double Edged Sword Role of Interleukin-22 in Wound Healing and Tissue Regeneration

Wound healing and tissue regeneration is an intricate biological process that involves repair of cellular damage and maintenance of tissue integrity. Cascades involved in wound healing and tissue regeneration highly overlap with cancer causing pathways. Usually, subsequent tissue damage events include release of a number of cytokines to accomplish post-trauma restoration. IL-22 is one of the cytokines that are immediately produced to initiate immune response against several tissue impairments. IL-22 is a fundamental mediator in inflammation, mucous production, protective role against pathogens, wound healing, and tissue regeneration. However, accumulating evidence suggests pivotal role of IL-22 in instigation of various cancers due to its pro-inflammatory and tissue repairing activity. In this review, we summarize how healing effects of IL-22, when executed in an uncontrollable fashion can lead to carcinogenesis.

Respiratory Barrier as a Safeguard and Regulator of Defense Against Influenza A Virus and Streptococcus pneumoniae

The primary function of the respiratory system of gas exchange renders it vulnerable to environmental pathogens that circulate in the air. Physical and cellular barriers of the respiratory tract mucosal surface utilize a variety of strategies to obstruct microbe entry. Physical barrier defenses including the surface fluid replete with antimicrobials, neutralizing immunoglobulins, mucus, and the epithelial cell layer with rapidly beating cilia form a near impenetrable wall that separates the external environment from the internal soft tissue of the host. Resident leukocytes, primarily of the innate immune branch, also maintain airway integrity by constant surveillance and the maintenance of homeostasis through the release of cytokines and growth factors. Unfortunately, pathogens such as influenza virus and Streptococcus pneumoniae require hosts for their replication and dissemination, and prey on the respiratory tract as an ideal environment causing severe damage to the host during their invasion. In this review, we outline the host-pathogen interactions during influenza and post-influenza bacterial pneumonia with a focus on inter- and intra-cellular crosstalk important in pulmonary immune responses.

Interleukin-22 regulates interferon lambda expression in a mice model of pseudomonas aeruginosa pneumonia

BACKGROUND

Interleukin (IL)-22 is a cytokine involved in tissue protection and repair following lung pathologies. Interferon (IFN)-λ cytokines displayed similar properties during viral infection and a synergy of action between these two players has been documented in the intestine. We hypothesize that during Pseudomonas aeruginosa challenge, IL-22 up-regulates IFN-λ and that IFN-λ exhibits protective functions during Pseudomonas aeruginosa acute pneumonia model in mice.

METHODS

Using an in vitro human alveolar epithelial cell line A549, we assessed the ability of IL-22 to enhance IFN-λ expression during infection. IFN-λ protective function was evaluated in an acute mouse pneumonia model.

RESULTS

We first demonstrated in murine lungs that only type-II alveolar cells express IL-22 receptor and that IL-22 treatment of A549 cell line up-regulates IFN-λ expression. In a murine acute pneumonia model, IL-22 administration maintained significant IFN-λ levels in the broncho-alveolar fluids whereas IL-22 neutralization abolished IFN-λ up-regulation. In vivo administration of IFN-λ during Pseudomonas aeruginosa pneumonia improves mice outcome by dampening neutrophil recruitment and decreasing epithelium damages.

DISCUSSION

We show here that IL-22 regulates IFN-λ levels during Pseudomonas aeruginosa pneumonia.

Targeting the IL-22/IL-22BP axis enhances tight junctions and reduces inflammation during influenza infection

The seasonal burden of influenza coupled with the pandemic outbreaks of more pathogenic strains underscore a critical need to understand the pathophysiology of influenza injury in the lung. Interleukin-22 (IL-22) is a promising cytokine that is critical in protecting the lung during infection. This cytokine is strongly regulated by the soluble receptor IL-22-binding protein (IL-22BP), which is constitutively expressed in the lungs where it inhibits IL-22 activity. The IL-22/IL-22BP axis is thought to prevent chronic exposure of epithelial cells to IL-22. However, the importance of this axis is not understood during an infection such as influenza. Here we demonstrate through the use of IL-22BP-knockout mice (il-22ra2-/-) that a pro-IL-22 environment reduces pulmonary inflammation during H1N1 (PR8/34 H1N1) infection and protects the lung by promoting tight junction formation. We confirmed these results in normal human bronchial epithelial cells in vitro demonstrating improved membrane resistance and induction of the tight junction proteins Cldn4, Tjp1, and Tjp2. Importantly, we show that administering recombinant IL-22 in vivo reduces inflammation and fluid leak into the lung. Taken together, our results demonstrate the IL-22/IL-22BP axis is a potential targetable pathway for reducing influenza-induced pneumonia.

MUC1 as a target for CAR-T therapy in head and neck squamous cell carinoma

The modification of chimeric antigen receptor (CAR) endowing T cells with tumor‐specific cytotoxicity induces antitumor immunity. However, the structural characteristics of solid tumors, the loss of specific antigens, and the strong immunosuppressive environment are challenges to treat solid tumors with CAR‐T therapy. The purpose of our study was to find and verify the potentials of CAR‐T therapies for patients with head and neck squamous cell carcinoma (HNSCC). First, we selected MUC1 as our research target and verified its differential expression in cancer tissues and adjacent non‐neoplastic tissues (ANNT). Next, we constructed a second‐generation CAR and validated the cytotoxic function in vitro. In our study, we found that exogenous addition human IL22 recombinant protein could increase the MUC1 expression and enhance the function of T cells. In addition, we constructed a fourth‐generation CAR that secretes IL22. Finally, we verified the antitumor function of two different CAR‐T cells in vitro and in vivo, respectively. CAR‐MUC1‐IL22 T cells were found to have a stronger and more effective cytotoxic function against MUC1 + HNSCC cells. Taken together, these results demonstrate the potential effectiveness of CAR‐T in the treatment of patients with HNSCC and provide evidence‐based of MUC1 + CAR‐T therapy.

IL-22 Confers EGFR-TKI Resistance in NSCLC via the AKT and ERK Signaling Pathways

Background: The efficacy of an EGFR-targeted treatment strategy for non-small cell lung cancer (NSCLC) is reduced by drug resistance. IL-22 enhances tumor growth and induces chemotherapy resistance in human lung cancer cells. The present study elucidated the IL-22-induced mechanism underlying EGFR-tyrosine kinase inhibitor (TKI) resistance in NSCLC.

Methods: The plasma and tissues of patients who received EGFR-TKIs were utilized to determine the association between IL-22 expression and gefitinib efficacy. The IL-22 effect on the EGFR/ERK/AKT pathways in NSCLC HCC827 and PC-9 cells was determined using the CCK-8 assay, western blot, and flow cytometric analysis. A PC-9 xenograft model of IL-22 exposure was established. Gefitinib was administered to mice in combination with IL-22 or vehicle.

Results: We showed that IL-22 expression was higher in the EGFR-TKI-resistant group compared to EGFR-TKI-sensitive group. IL-22 expression was associated with EGFR-TKI efficacy in plasma. Additional treatment of IL-22 induced gefitinib resistance and reduced apoptosis in PC-9 and HCC827 cell lines. Furthermore, we showed that the effects of IL-22 attributed to p-ERK, p-EGFR, and p-AKT up-regulation. IL-22 neutralizing antibody completely abrogated the effects of IL-22 on apoptosis and AKT/EGFR/ERK signaling. Finally, we showed that IL-22 enhanced tumor growth and induced gefitinib resistance in the PC-9 xenograft model. Moreover, compared with gefitinib alone, the combination of IL-22 and gefitinib led to an increase in Ki67-positive staining and a reduction in TUNEL staining.

Conclusions: Our findings indicate that IL-22 plays a role in tumor progression and EGFR-TKI resistance in NSCLC. Thus, IL-22 might serve as a novel biomarker to overcome resistance of EGFR-TKI.

IL-18/IL-18BP and IL-22/IL-22BP: Two interrelated couples with therapeutic potential

Interleukin (IL)-18 and IL-22 are key components of cytokine networks that play a decisive role in (pathological) inflammation, host defense, and tissue regeneration. Tight regulation of cytokine-driven signaling, inflammation, and immunoactivation is supposed to enable nullification of a given deleterious trigger without mediating overwhelming collateral tissue damage or even activating a cancerous face of regeneration. In fact, feedback regulation by specific cytokine opponents is regarded as a major means by which the immune system is kept in balance. Herein, we shine a light on the interplay between IL-18 and IL-22 and their opponents IL-18 binding protein (IL-18BP) and IL-22BP in order to provide integrated information on their biology, pathophysiological significance, and prospect as targets and/or instruments of therapeutic intervention.

Moving target: shifting the focus to pulmonary sarcoidosis as an autoimmune spectrum disorder

Despite more than a century of research, the causative agent(s) in sarcoidosis, a heterogeneous granulomatous disorder mainly affecting the lungs, remain(s) elusive. Following identification of genetic factors underlying different clinical phenotypes, increased understanding of CD4⁺ T-cell immunology, which is believed to be central to sarcoid pathogenesis, as well as the role of B-cells and other cells bridging innate and adaptive immunity, contributes to novel insights into the mechanistic pathways influencing disease resolution or chronicity. Hopefully, new perspectives and state-of-the-art technology will help to shed light on the still-elusive enigma of sarcoid aetiology. This perspective article highlights a number of recent advances in the search for antigenic targets in sarcoidosis, as well as the main arguments for sarcoidosis as a spectrum of autoimmune conditions, either as a result of an external (microbial) trigger and/or due to defective control mechanisms regulating the balance between T-cell activation and inhibition.

Prognostic modeling of the immune-centric transcriptome reveals interleukin signaling candidates contributing to differential patient outcomes

Immunotherapy is a promising advancement in the treatment of non-small-cell lung carcinoma (NSCLC), although much of how lung tumors interact with the immune system in the natural course of disease remains unknown. We investigated the impact of the expression of immune-centric genes and pathways in tumors on patient survival to reveal novel candidates for immunotherapeutic research. Tumor transcriptomes and detailed clinical characteristics were obtained from patients with NSCLC who were participants of either the Inflammation, Health and Lung Epidemiology (INHALE) (discovery, N = 280) or The Cancer Genome Atlas (TCGA) Lung (replication, N = 1026) studies. Expressions of 2253 genes derived from 48 major immune pathways were assessed for association with patient prognosis using a multivariable Cox model and pathway effects were assessed with an in-house implementation of the Gene Set Enrichment Analysis (GSEA) algorithm. Prognosis-guided gene and pathway analysis of immune-centric expression in tumors revealed significant survival enrichments across both cohorts. The 'Interleukin Signaling' pathway, containing 430 genes, was found to be statistically and significantly enriched with prognostic signal in both the INHALE (P = 0.008) and TCGA (P = 0.039) datasets. Subsequent leading-edge analysis identified a subset of genes (N = 23) shared between both cohorts, driving the pathway enrichment. Cumulative expression of this leading-edge gene signature was a strong predictor of patient survival [discovery: hazard ratio (HR) = 1.59, P = 3.0 × 10-8; replication: HR = 1.29, P = 7.4 × 10-7]. These data demonstrate the impact of immune-centric expression on patient outcomes in NSCLC. Furthermore, prognostic gene effects were localized to discrete immune pathways, of which Interleukin Signaling had the greatest impact on overall survival and the subset of genes driving these effects have promise for future therapeutic intervention.

IL-22: An Underestimated Player in Natural Resistance to Tuberculosis?

Approximately 10% of individuals latently infected with Mycobacterium tuberculosis (Mtb) develop active tuberculosis (TB) during their lifetime. Although it is well recognized that T-helper 1 immune responses are crucial for containing latent TB infection, the full array of host factors conferring protective immunity from TB progression are not completely understood. IL-22 is produced by cells of the innate and adaptive immune system including innate lymphoid cells, and natural killer cells as well as T lymphocytes (Th1, Th17, and Th22) and binds to its cognate receptor, the IL-22R1, which is expressed on non-hematopoietic cells such as lung epithelial cells. However, recent studies suggest that Mtb induces expression of the IL-22R1 on infected macrophages and multiple studies have indicated a protective role of IL-22 in respiratory tract infections. Reduced concentrations of circulating IL-22 in active TB compared to latent TB and decreased percentages of Mtb-specific IL-22 producing T cells in TB patients compared to controls designate this cytokine as a key player in TB immunology. More recently, it has been shown that in type 2 diabetes (T2D) and TB co-morbidity serum IL-22 concentrations are further reduced compared to TB patients without co-morbidities. However, whether a causative link between low IL-22 and increased susceptibility to TB and disease severity of TB exists remains to be established. This review summarizes the contribution of IL-22, a potentially under-appreciated key player in natural resistance to TB, at the interface between the immune response to Mtb and the lung epithelium.

IL22 Promotes Kras-Mutant Lung Cancer by Induction of a Protumor Immune Response and Protection of Stemness Properties

Somatic KRAS mutations are the most common oncogenic variants in lung cancer and are associated with poor prognosis. Using a Kras-induced lung cancer mouse model, CC-LR, we previously showed a role for inflammation in lung tumorigenesis through activation of the NF-κB pathway, along with induction of interleukin 6 (IL6) and an IL17-producing CD4+ T-helper cell response. IL22 is an effector molecule secreted by CD4+ and γδ T cells that we previously found to be expressed in CC-LR mice. IL22 mostly signals through the STAT3 pathway and is thought to act exclusively on nonhematopoietic cells with basal IL22 receptor (IL22R) expression on epithelial cells. Here, we found that higher expression of IL22R1 in patients with KRAS-mutant lung adenocarcinoma was an independent indicator of poor recurrence-free survival. We then showed that genetic ablation of Il22 in CC-LR mice (CC-LR/IL22KO mice) caused a significant reduction in tumor number and size. This was accompanied by significantly lower tumor cell proliferation, angiogenesis, and STAT3 activation. Il22 ablation was also associated with significant reduction in lung-infiltrating inflammatory cells and expression of protumor inflammatory cytokines. Conversely, this was accompanied with increased antitumor Th1 and cytotoxic CD8+ T-cell responses, while suppressing the protumor immunosuppressive T regulatory cell response. In CC-LR/IL22KO mice, we found significantly reduced expression of core stemness genes and the number of prototypical SPC+CCSP+ stem cells. Thus, we conclude that IL22 promotes Kras-mutant lung tumorigenesis by driving a protumor inflammatory microenvironment with proliferative, angiogenic, and stemness contextual cues in epithelial/tumor cells. Cancer Immunol Res; 6(7); 788-97. ©2018 AACR.

The Role of Immune and Inflammatory Cells in Idiopathic Pulmonary Fibrosis

The contribution of the immune system to idiopathic pulmonary fibrosis (IPF) remains poorly understood. While most sources agree that IPF does not result from a primary immunopathogenic mechanism, evidence gleaned from animal modeling and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. This review will synthesize the available data regarding the complex role of professional immune cells in IPF. The role of innate immune populations such as monocytes, macrophages, myeloid suppressor cells, and innate lymphoid cells will be discussed, as will the activation of these cells via pathogen-associated molecular patterns derived from invading or commensural microbes, and danger-associated molecular patterns derived from injured cells and tissues. The contribution of adaptive immune responses driven by T-helper cells and B cells will be reviewed as well. Each form of immune activation will be discussed in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

Allergic Rhinitis and Its Relationship with IL-10, IL-17, TGF-β, IFN-γ, IL 22, and IL-35

BACKGROUND

We aimed in our study to research the role of new cytokines such as IL-35, IL-22, and IL-17 that may form a target for novel treatment approaches.

METHODS

IL-10, IL-17, TGF-β, IFN-γ, IL-22, and IL-35 serum levels of allergic rhinitis (AR) patients were measured using ELISA method. Allergic sensitization was demonstrated by the skin prick test. Patients only with olive tree sensitivity were evaluated for seasonal AR (SAR). Patients only with mite sensitivity were included in the study for perennial AR (PAR). AR clinic severity was demonstrated by the nasal symptom scores (NSS).

RESULTS

In total, 65 AR patients (patient group), having 31 PAR and 34 SAR patients, and 31 healthy individuals (control group) participated in the study. Cytokine levels between the patient group and the control group were compared; IL-17 (p = 0.038), IL-22 (p = 0.001), and TGF-β (p = 0.031) were detected as high in the patient group, and IFN-γ (p < 0.001) was detected as low in the patient group. When correlation analysis was made between age, gender, prick test result, NSS, AR duration, and cytokine levels in the patient group, a negative correlation was detected only between IFN-γ (p = 0.032/r = -0.266) level and NSS.

CONCLUSIONS

Accompanied by the literature information, these results made us think that T cell subgroups and cytokines have an important role in AR immunopathogenesis. It is thought that future studies to be conducted relating to this subject will form new targets in treatment.

Interleukin-22 in human inflammatory diseases and viral infections

Interleukin-22 (IL22) is one of the members of IL10 family. Elevated levels of this cytokine can be seen in diseases caused by T lymphocytes, such as Psoriasis, Rheumatoid arthritis, interstitial lung diseases. IL22 is produced by different cells in both innate and acquired immunities. Different types of T cells are able to produce IL22, but the major IL22-producing T-cell is the TCD4. TH22 cell is a new line of TCD4 cells, which differentiated from naive T cells in the presence of TNFα and IL6; 50% of peripheral blood IL22 is produced by these cells. IL22 has important functions in host defense at mucosal surfaces as well as in tissue repair. In this review, we assess the current understanding of this cytokine and focus on the possible roles of IL-22 in autoimmune diseases.

Interleukin-22 level is negatively correlated with neutrophil recruitment in the lungs in a Pseudomonas aeruginosa pneumonia model

Pseudomonas aeruginosa is a major threat for immune-compromised patients. Bacterial pneumonia can induce uncontrolled and massive neutrophil recruitment ultimately leading to acute respiratory distress syndrome and epithelium damage. Interleukin-22 plays a central role in the protection of the epithelium. In this study, we aimed to evaluate the role of interleukin-22 and its soluble receptor IL-22BP in an acute Pseudomonas aeruginosa pneumonia model in mice. In this model, we noted a transient increase of IL-22 during Pseudomonas aeruginosa challenge. Using an antibody-based approach, we demonstrated that IL-22 neutralisation led to increased susceptibility to infection and to lung damage correlated with an increase in neutrophil accumulation in the lungs. On the contrary, rIL-22 administration or IL-22BP neutralisation led to a decrease in mouse susceptibility and lung damage associated with a decrease in neutrophil accumulation. This study demonstrated that the IL-22/IL-22BP system plays a major role during Pseudomonas aeruginosa pneumonia by moderating neutrophil accumulation in the lungs that ultimately leads to epithelium protection.

Novel role for IL-22 in protection during chronic Mycobacterium tuberculosis HN878 infection

Approximately 2 billion people are infected with Mycobacterium tuberculosis (Mtb), resulting in 1.4 million deaths every year. Among Mtb-infected individuals, clinical isolates belonging to the W-Beijing lineage are increasingly prevalent, associated with drug resistance, and cause severe disease immunopathology in animal models. Therefore, it is exceedingly important to identify the immune mechanisms that mediate protection against rapidly emerging Mtb strains, such as W-Beijing lineage. IL-22 is a member of the IL-10 family of cytokines with both protective and pathological functions at mucosal surfaces. Thus far, collective data show that IL-22 deficient mice are not more susceptible to aerosolized infection with less virulent Mtb strains. Thus, in this study we addressed the functional role for the IL-22 pathway in immunity to emerging Mtb isolates, using W-Beijing lineage member, Mtb HN878 as a prototype. We show that Mtb HN878 stimulates IL-22 production in TLR2 dependent manner and IL-22 mediates protective immunity during chronic stages of Mtb HN878 infection in mice. Interestingly, IL-22-dependent pathways in both epithelial cells and macrophages mediate protective mechanisms for Mtb HN878 control. Thus, our results project a new protective role for IL-22 in emerging Mtb infections.

IL-22/IL-22R1 signaling regulates the pathophysiology of chronic rhinosinusitis with nasal polyps via alteration of MUC1 expression

BACKGROUND

IL-22 is an IL-10-family cytokine that regulates chronic inflammation. We investigated the role of IL-22 and its receptor, IL-22R1, in the pathophysiology of chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

IL-22 and IL-22R1 protein and mRNA expression in NP and in uncinate tissues (UT) from CRS and non-CRS patients was examined using immunohistochemistry and real-time PCR, respectively. Dispersed NP and UT cells were cultured with the Staphylococcus aureus exotoxins, staphylococcal enterotoxin B and alpha-toxin, following which exotoxin-induced IL-22 levels and their association with clinicopathological factors were analyzed. Effects of IL-22 on MUC1 expression and cytokine release in NP cells were also determined.

RESULTS

IL-22 and IL-22R1 in NP were mainly expressed in infiltrating inflammatory cells and in epithelial cells, respectively. IL-22 mRNA levels in NP were significantly higher than those in UTs from non-CRS patients whereas IL-22R1 levels were conversely lower in NPs. NP cells produced substantial amounts of IL-22 in response to exotoxins. Exotoxin-induced IL-22 production by NP cells significantly and negatively correlated with the degree of local eosinophilia and postoperative computed tomography (CT) score, whereas conversely it positively correlated with the forced expiratory volume in 1s (FEV1)/forced vital capacity (FVC) ratio. IL-22 significantly enhanced MUC1 mRNA expression in NP cells. IL-22-induced MUC1 mRNA levels were significantly and positively correlated with IL-22R1 mRNA levels in NPs.

CONCLUSIONS

These data suggest that imbalance of IL-22/IL-22R1 signaling regulates the pathogenesis of CRSwNP, including local eosinophilia, via alteration of MUC1 expression.

Human IL-22 binding protein isoforms act as a rheostat for IL-22 signaling

The cytokine interleukin-22 (IL-22), which is a member of the IL-10 family, is produced exclusively by immune cells and activates signal transducer and activator of transcription 3 (STAT3) in nonimmune cells, such as hepatocytes, keratinocytes, and colonic epithelial cells, to drive various processes central to tissue homeostasis and immunosurveillance. Dysregulation of IL-22 signaling causes inflammatory diseases. IL-22 binding protein (IL-22BP; encoded by IL22RA2) is a soluble IL-22 receptor, which antagonizes IL-22 activity and has genetic associations with autoimmune diseases. Humans have three IL-22BP isoforms, IL-22BPi1 to IL-22BPi3, which are generated by alternative splicing; mice only have an IL-22BPi2 homolog. We showed that, although IL-22BPi3 had less inhibitory activity than IL-22BPi2, IL-22BPi3 was more abundant in various human tissues under homeostatic conditions. IL-22BPi2 was more effective than IL-22BPi3 at blocking the contribution of IL-22 to cooperative gene induction with the inflammatory cytokine IL-17, which is often present with IL-22 in autoimmune settings. In addition, we found that IL-22BPi1 was not secreted and therefore failed to antagonize IL-22 signaling. Furthermore, IL-22BPi2 was the only isoform that was increased in abundance when myeloid cells were activated by Toll-like receptor 2 signaling or retinoic acid, a maturation factor for myeloid cells. These data suggest that the human IL-22BP isoforms have distinct spatial and temporal roles and coordinately fine-tune IL-22-dependent STAT3 responses in tissues as a type of rheostat.

Aerobic Exercise Attenuated Bleomycin-Induced Lung Fibrosis in Th2-Dominant Mice

INTRODUCTION

The aim of this study was to investigate the effect of aerobic exercise (AE) in reducing bleomycin-induced fibrosis in mice of a Th2-dominant immune background (BALB/c).

METHODS

BALB/c mice were distributed into: sedentary, control (CON), Exercise-only (EX), sedentary, bleomycin-treated (BLEO) and bleomycin-treated+exercised (BLEO+EX); (n = 8/group). Following treadmill adaptation, 15 days following a single, oro-tracheal administration of bleomycin (1.5U/kg), AE was performed 5 days/week, 60min/day for 4 weeks at moderate intensity (60% of maximum velocity reached during a physical test) and assessed for pulmonary inflammation and remodeling, and cytokine levels in bronchoalveolar lavage (BAL).

RESULTS

At 45 days post injury, compared to BLEO, BLEO+EX demonstrated reduced collagen deposition in the airways (p<0.001) and also in the lung parenchyma (p<0.001). In BAL, a decreased number of total leukocytes (p<0.01), eosinophils (p<0.001), lymphocytes (p<0.01), macrophages (p<0.01), and neutrophils (p<0.01), as well as reduced pro-inflammatory cytokines (CXCL-1; p<0.01), (IL-1β; p<0.001), (IL-5; p<0.01), (IL-6; p<0.001), (IL-13; p<0.01) and pro-fibrotic growth factor IGF-1 (p<0.001) were observed. Anti-inflammatory cytokine IL-10 was increased (p<0.001).

CONCLUSION

AE attenuated bleomycin-induced collagen deposition, inflammation and cytokines accumulation in the lungs of mice with a predominately Th2-background suggesting that therapeutic AE (15-44 days post injury) attenuates the pro-inflammatory, Th2 immune response and fibrosis in the bleomycin model.

Interleukin-22 is elevated in lavage from patients with lung cancer and other pulmonary diseases

BACKGROUND

Interleukin-22 (IL-22) is involved in lung diseases such as pneumonia, asthma and lung cancer. Lavage mirrors the local environment, and may provide insights into the presence and role of IL-22 in patients.

METHODS

Bronchoscopic lavage (BL) samples (n = 195, including bronchoalveolar lavage and bronchial washings) were analysed for IL-22 using an enzyme-linked immunosorbent assay. Clinical characteristics and parameters from lavage and serum were correlated with lavage IL-22 concentrations.

RESULTS

IL-22 was higher in lavage from patients with lung disease than in controls (38.0 vs 15.3 pg/ml, p < 0.001). Patients with pneumonia and lung cancer had the highest concentrations (48.9 and 33.0 pg/ml, p = 0.009 and p < 0.001, respectively). IL-22 concentration did not correlate with systemic inflammation. IL-22 concentrations did not relate to any of the analysed cell types in BL indicating a potential mixed contribution of different cell populations to IL-22 production.

CONCLUSIONS

Lavage IL-22 concentrations are high in patients with lung cancer but do not correlate with systemic inflammation, thus suggesting that lavage IL-22 may be related to the underlying malignancy. Our results suggest that lavage may represent a distinct compartment where the role of IL-22 in thoracic malignancies can be studied.

Expanded lung T-bet+RORγT+ CD4+ T-cells in sarcoidosis patients with a favourable disease phenotype

Disease phenotypes of pulmonary sarcoidosis are distinguished by clinical rather than immunological criteria. We aimed to characterise patterns of CD4+ T-cell lineage plasticity underlying the differences in clinical presentation and disease course between the acute form, Löfgren's syndrome, and the heterogeneous, potentially progressive “non-Löfgren” form.

33 pulmonary sarcoidosis patients and nine controls underwent bronchoscopy with bronchoalveolar lavage. CD4+ T-cell transcription factor, chemokine receptor and T-cell receptor expression, proliferation and cytokine production were assessed in the lavage fluid and peripheral blood using flow cytometry and multicolour FluoroSpot.

CD4+ T-cells simultaneously expressing the T-helper cell (Th)1 and Th17 transcriptional regulators T-bet and RORγT (T-bet+RORγT+) were identified in the lavage, but not blood, of all subjects, and to a significantly higher degree in Löfgren's patients. T-bet+RORγT+ cells proliferated actively, produced interferon (IFN)γ and interleukin (IL)-17A, co-expressed the chemokine receptors CXCR3 and CCR6, and correlated with nonchronic disease. T-cell receptor-restricted Vα2.3+Vβ22+ T-cells strongly co-expressed T-bet/RORγT and CXCR3/CCR6. Cytokine production was more heterogeneous in Löfgren's patients, with significantly higher IL-17A, IL-10, IL-22 and IL-2, but lower IFNγ.

Here we demonstrate the presence of lung T-bet+RORγT+CXCR3+CCR6+ CD4+ T-cells and Th17-associated cytokines especially in sarcoidosis patients with a favourable prognosis, suggesting a Th1/Th17-permissive environment in the lung with implications for disease resolution.

Attenuated Airway Epithelial Cell Interleukin-22R1 Expression in the Infant Nonhuman Primate Lung

Respiratory tract infections are a leading cause of morbidity and mortality in children under 5 years of age. Increased susceptibility to infection is associated with deficiencies in immunity during early childhood. Airway epithelium represents the first line of mucosal defense against inhaled pathogens. However, little is known about epithelial immune mechanisms in the maturing lung. IL-22 and its receptor IL-22R1 are important in host defense and repair of epithelial barriers. The objective of this study was to determine whether a quantitative difference in IL-22R1 exists between infant and adult airways using the rhesus macaque monkey as a model of childhood lung development. Immunofluorescence staining of tracheal tissue revealed minimal expression of IL-22R1 in epithelium at 1 month of age, with a progressive increase in fluorescence-positive basal cells through 1 year of age. Western blot analysis of tracheal lysates confirmed significant age-dependent differences in IL-22R1 protein content. Further, primary tracheobronchial epithelial cell cultures established from infant and adult monkeys showed differential IL-22R1 mRNA and protein expression in vitro. To begin to assess the regulation of age-dependent IL-22R1 expression in airway epithelium, the effect of histone deacetylase and DNA methyltransferase inhibitors was evaluated. IL-22R1 mRNA in adult cultures was not altered by 5-aza-2'-deoxycytidine or trichostatin A. IL-22R1 mRNA in infant cultures showed no change with 5-aza-2'-deoxycytidine but was significantly increased after trichostatin A treatment; however, IL-22R1 protein did not increase concurrently. These data suggest that IL-22R1 in airway epithelium is regulated, in part, by epigenetic mechanisms that are dependent on chronologic age.

Interleukin-22 promotes lung cancer cell proliferation and migration via the IL-22R1/STAT3 and IL-22R1/AKT signaling pathways

Lung cancer continues to be an enormous burden on current health care systems throughout the world, with more than a million deaths every year. Previous studies have shown that interleukin-22 (IL-22) promotes survival and resistance to chemotherapy in human lung cancer cells. However, the association of IL-22 expression with recurrence of lung cancer is still unclear. In this study, we found that expression of IL-22 was upregulated in tumor tissues and serum from patients with recurrent non-small cell lung cancer (NSCLC) as compared to primary NSCLC samples. Treatment with IL-22 promoted cell proliferation and enhanced migration and invasion in A549 and H125 cell lines. Furthermore, we revealed that phosphorylation of STAT3 and AKT was highly induced by treatment with IL-22 via IL-22R1. IL-22R1 was also consistently overexpressed in recurrent NSCLC tissues. Finally, we found that siRNA-mediated depletion of IL-22R1 completely abrogated the effects of IL-22 treatment on cell proliferation and migration activity in NSCLC cell lines. Our findings indicate that IL-22 and IL-22R1 may be novel therapeutic targets for treatment of advanced NSCLC.

IL-22 regulation of functional gene expression in salivary gland cells

TH17 cells and their associated signature cytokines, IL-17 and IL-22, are highly elevated in primary Sjögren's syndrome (pSjS). The levels of IL-22 present in sera showed significant correlations with many disease parameters, specifically hyposalivation, anti-SSB, anti-SSA/SSB, hypergammaglobulinemia and rheumatoid factor. The present study aims to examine the biological function of IL-22 on human salivary glands. To accomplish the goal, microarray analysis using the HumanHT-12 v4 Expression BeadChip was utilized to determine the biological function of IL-22. Differential expression analyses were conducted using the LIMMA package from the Bioconductor project. MTT assay, flow cytometry and Western blotting were used to identify the function of IL-22 on human salivary gland cells. Results indicate an extensive effect of IL-22 on many major molecular functions including activation of antimicrobial genes and downregulation of immune-associated pathways. Functional studies performed in-vitro using human salivary gland cells treated with IL-22 indicated a direct effect of IL-22 on cell cycling, specifically reducing cellular proliferation at the G2-M phase by activation of STAT3. These results suggest the important role of IL-22 in the salivary gland function. The present study suggests that IL-22 might be involved in regulating inflammation and controlling the cell proliferation in SjS.

IL-22, cell regeneration and autoimmunity

IL-22 as a cytokine is described with opposing pro-inflammatory and anti-inflammatory functions. Cell regeneration, tissue remodelling and balance between commensal bacteria in the gut and host immune system are considered as anti-inflammatory features of IL-22, whereas production of IL-22 from Th17 cells links this cytokine to pro-inflammatory pathways. Th17 cells and group 3 innate lymphoid cells (ILC3) are two major producers of IL-22 and both cell types express ROR-γt and Aryl hydrocarbon receptor (AhR) transcription factors. Typically, the immune system cells are the main producers of IL-22. However, targets of this cytokine are mostly non-hematopoietic cells such as hepatocytes, keratinocytes, and epithelial cells of lung and intestine. Association of IL-22 with other cytokines or transcription factors in different cell types might explain its contrasting role in health and disease. In this review we discuss the regulation of IL-22 production by AhR- and IL-23-driven pathways. A clear understanding of the biology of IL-22 will provide new opportunities for its application to improve human health involving many debilitating conditions.

IL22/IL-22R pathway induces cell survival in human glioblastoma cells

Interleukin-22 (IL-22) is a member of the IL-10 cytokine family that binds to a heterodimeric receptor consisting of IL-22 receptor 1 (IL-22R1) and IL-10R2. IL-22R expression was initially characterized on epithelial cells, and plays an essential role in a number of inflammatory diseases. Recently, a functional receptor was detected on cancer cells such as hepatocarcinoma and lung carcinoma, but its presence was not reported in glioblastoma (GBM). Two GBM cell lines and 10 primary cell lines established from patients undergoing surgery for malignant GBM were used to investigate the expression of IL-22 and IL-22R by using quantitative RT-PCR, western blotting and confocal microscopy studies. The role of IL-22 in proliferation and survival of GBM cell lines was investigated in vitro by BrdU and ELISA cell death assays. We report herein that the two subunits of the IL-22R complex are expressed on human GBM cells. Their activation, depending on exogenous IL-22, induced antiapoptotic effect and cell proliferation. IL-22 treatment of GBM cells resulted in increased levels of phosphorylated Akt, STAT3 signaling protein and its downstream antiapoptotic protein Bcl-xL and decreased level of phosphorylated ERK1/2. In addition, IL-22R subunits were expressed in all the 10 tested primary cell lines established from GBM tumors. Our results showed that IL-22R is expressed on GBM established and primary cell lines. Depending on STAT3, ERK1/2 and PI3K/Akt pathways, IL-22 induced GBM cell survival. These data are consistent with a potential role of IL-22R in tumorigenesis of GBM. Since endogenous IL-22 was not detected in all studied GBM cells, we hypothesize that IL-22R could be activated by immune microenvironmental IL-22 producing cells.

The role of the IL-22/IL-22R1 axis in cancer

Interleukin-22 (IL-22) is an IL-10 family cytokine produced by T cells and innate lymphoid cells. The IL-22 signaling pathway orchestrates mucosal immune defense and tissue regeneration through pleiotropic effects including pro-survival signaling, cell migration, dysplasia and angiogenesis. While these functions can prevent initial establishment of tumors, they can also be hijacked by aggressive cancers to enhance tumor growth and metastasis. Thus, the role of the IL-22/IL-22R1 axis in cancer is complex and context-specific. Evidence of IL-22 involvement manifests as dysregulation of IL-22 expression and signaling in patients with many common cancers including those of the gut, skin, lung and liver. Unlike other cancer-associated cytokines, IL-22 has restricted tissue specificity as its unique receptor IL-22R1 is exclusively expressed on epithelial and tissue cells, but not immune cells. This makes it an attractive target for therapy as there is potential achieve anti-tumor immunity with fewer side effects. This review summarizes current findings on functions of IL-22 in association with general mechanisms for tumorigenesis as well as specific contributions to particular cancers, and ponders how best to approach further research in the field.

Interleukins for the paediatric pulmonologist

Interleukins are critical immune modulators and since their first description in 1977, there has been a steady increase in the recognition of their roles in many paediatric respiratory diseases. This basic and clinical knowledge is now maturing into both approved and investigational therapies aimed at blocking or modifying the interleukin response. The purpose of this review is to bring up to date what is known about interleukin function in paediatric pulmonology, focusing on nine important lung conditions. This is followed by summaries about 18 interleukins which have been associated with these paediatric pulmonary conditions. Throughout, emphasis is placed on where interventions have been tested. Over the next several years, it is likely that many more treatments based on interleukin biology and function will become available and understanding the basis for these therapies will allow the practicing paediatric pulmonologist to take appropriate advantage of them.

Conventional NK cells can produce IL-22 and promote host defense in Klebsiella pneumoniae pneumonia

It was reported that host defense against pulmonary Klebsiella pneumoniae infection requires IL-22, which was proposed to be of T cell origin. Supporting a role for IL-22, we found that Il22(-/-) mice had decreased survival compared with wild-type mice after intratracheal infection with K. pneumoniae. Surprisingly, however, Rag2(-/-) mice did not differ from wild-type mice in survival or levels of IL-22 in the lungs postinfection with K. pneumoniae. In contrast, K. pneumoniae-infected Rag2(-/-)Il2rg(-/-) mice failed to produce IL-22. These data suggested a possible role for NK cells or other innate lymphoid cells in host defense and production of IL-22. Unlike NK cell-like innate lymphoid cells that produce IL-22 and display a surface phenotype of NK1.1(-)NKp46(+)CCR6(+), lung NK cells showed the conventional phenotype, NK1.1(+)NKp46(+)CCR6(-). Mice depleted of NK cells using anti-asialo GM1 showed decreased survival and higher lung bacterial counts, as well as increased dissemination of K. pneumoniae to blood and liver, compared with control-treated mice. NK cell depletion also led to decreased production of IL-22 in the lung. Within 1 d postinfection, although there was no increase in the number of lung NK cells, a subset of lung NK cells became competent to produce IL-22, and such cells were found in both wild-type and Rag2(-/-) mice. Our data suggest that, during pulmonary infection of mice with K. pneumoniae, conventional NK cells are required for optimal host defense, which includes the production of IL-22.

Interleukin-22: A Bridge Between Epithelial Innate Host Defense and Immune Cells

Interleukin-22 (IL-22), an IL-10 family cytokine, is produced by various leukocytes. The receptor of IL-22, however, is preferentially detected on peripheral tissue epithelial cells. IL-22 functions as a unique messenger from immune system to tissue epithelial cells and to regulate homeostasis of epithelia. IL-22 is able to directly enhance antimicrobial defense mechanisms in epithelial cells and to facilitate epithelial barrier repair and wound healing process. It, therefore, possesses an irreplaceable role in host defense against certain pathogens that specifically invade epithelial cells. In addition, IL-22 can help to preserve the integrity and homeostasis of various epithelial organs during infection or inflammation. The importance of its tissue-protective function is manifested in many inflammatory situations such as inflammatory bowel diseases (IBD) and hepatitis. On the other hand, as a cytokine, IL-22 is capable of induction of proinflammatory responses, especially in synergy with other cytokines. Consequently, IL-22 contributes to pathogenesis of certain inflammatory diseases for example psoriasis.

Therapeutic opportunities of the IL-22-IL-22R1 system

Interleukin-22 (IL-22) is a key effector molecule that is produced by activated T cells, including T helper 22 (TH22) cells, TH17 cells and TH1 cells, as well as subsets of innate lymphoid cells. Although IL-22 can act synergistically with IL-17 or tumour necrosis factor, some important functions of IL-22 are unique to this cytokine. Data obtained over the past few years indicate that the IL-22-IL-22 receptor subunit 1 (IL-22R1) system has a high potential clinical relevance in psoriasis, ulcerative colitis, graft-versus-host disease, certain infections and tumours, as well as in liver and pancreas damage. This Review highlights current knowledge of the biology of the IL-22-IL-22R1 system, its role in inflammation, tissue protection, regeneration and antimicrobial defence, as well as the positive and potentially negative consequences of its therapeutic modulation.

Human metapneumovirus inhibits the IL-6-induced JAK/STAT3 signalling cascade in airway epithelium

The host cytokine IL-6 plays an important role in host defence and prevention of lung injury from various pathogens, making IL-6 an important mediator in the host's susceptibility to respiratory infections. The cellular response to IL-6 is mediated through a Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signal transduction pathway. Human metapneumovirus (hMPV) is an important causative agent of viral respiratory infections known to inhibit the IFN-mediated activation of STAT1. However, little is known about the interactions between this virus and other STAT signalling cascades. Herein, we showed that hMPV can attenuate the IL-6-mediated JAK/STAT3 signalling cascade in lung epithelial cells. HMPV inhibited a key event in this pathway by impeding the phosphorylation and nuclear translocation of STAT3 in A549 cells and in primary normal human bronchial epithelial cells. Further studies established that hMPV interrupted the IL-6-induced JAK/STAT pathway early in the signal transduction pathway by blocking the phosphorylation of JAK2. By antagonizing the IL-6-mediated JAK/STAT3 pathway, hMPV perturbed the expression of IL-6-inducible genes important for apoptosis, cell differentiation and growth. Infection with hMPV also differentially regulated the effects of IL-6 on apoptosis. Thus, hMPV regulation of these genes could usurp the protective roles of IL-6, and these data provide insight into an important element of viral pathogenesis.

Interleukin-22 is frequently expressed in small- and large-cell lung cancer and promotes growth in chemotherapy-resistant cancer cells

INTRODUCTION

In lung cancer, interleukin-22 (IL-22) expression within primary tissue has been demonstrated, but the frequency and the functional consequence of IL-22 signaling have not been addressed. This study aims at analyzing the cellular effects of IL-22 on lung carcinoma cell lines and the prognostic impact of IL-22 tissue expression in lung cancer patients.

METHODS

Biological effects of IL-22 signaling were investigated in seven lung cancer cell lines by Western blot, flow cytometry, real-time polymerase chain reaction, and proliferation assays. Tumor tissue specimens of two cohorts with a total of 2300 lung cancer patients were tested for IL-22 expression by immunohistochemistry. IL-22 serum concentrations were analyzed in 103 additional patients by enzyme-linked immunosorbent assay.

RESULTS

We found the IL-22 receptor 1 (IL-22-R1) to be expressed in six of seven lung cancer cell lines. However IL-22 signaling was functional in only four cell lines, where IL-22 induced signal transducer activator of transcription 3 phosphorylation and increased cell proliferation. Furthermore, IL-22 induced the expression of antiapoptotic B-cell lymphoma 2, but did not rescue tumor cells from carboplatin-induced apoptosis. Cisplatin-resistant cell lines showed a significant up-regulation of IL-22-R1 along with a stronger proliferative response to IL-22 stimulation. IL-22 was preferentially expressed in small- and large-cell lung carcinoma (58% and 46% of cases, respectively). However, no correlation between IL-22 expression by immunohistochemistry and prognosis was observed.

CONCLUSION

IL-22 is frequently expressed in lung cancer tissue. Enhanced IL-22-R1 expression and signaling in chemotherapy-refractory cell lines are indicative of a protumorigenic function of IL-22 and may contribute to a more aggressive phenotype.

IL-22 modulates IL-17A production and controls inflammation and tissue damage in experimental dengue infection

Dengue virus (DENV), a mosquito-borne flavivirus, is a public health problem in many tropical countries. IL-22 and IL-17A are key cytokines in several infectious and inflammatory diseases. We have assessed the contribution of IL-22 and IL-17A in the pathogenesis of experimental dengue infection using a mouse-adapted DENV serotype 2 strain (P23085) that causes a disease that resembles severe dengue in humans. We show that IL-22 and IL-17A are produced upon DENV-2 infection in immune-competent mice. Infected IL-22(-/-) mice had increased lethality, neutrophil accumulation and pro-inflammatory cytokines in tissues, notably IL-17A. Viral load was increased in spleen and liver of infected IL-22(-/-) mice. There was also more severe liver injury, as seen by increased transaminases levels and tissue histopathology. γδ T cells and NK cells are sources of IL-17A and IL-22, respectively, in liver and spleen. We also show that DENV-infected HepG2 cells treated with rhIL-22 had reduced cell death and decreased IL-6 production. IL-17RA(-/-) mice were protected upon infection and IL-17A-neutralizing-Ab-treatment partially reversed the phenotype observed in IL-22(-/-) -infected mice. We suggest that disrupting the balance between IL-22 and IL-17A levels may represent an important strategy to reduce inflammation and tissue injury associated with severe dengue infection.

Interleukin-22 produced by alveolar macrophages during activation of the innate immune response

OBJECTIVE AND DESIGN

Interleukin (IL)-22 is important for mucosal host defense. Whereas previous studies focus on lymphocytes as sources of IL-22, we determined whether IL-22 is produced by inflammatory cells in the lungs other than T-lymphocytes during the activation of the innate immune response.

MATERIAL, METHODS AND TREATMENT

Inflammatory cells in the lungs of Balb/c mice were primed by endotoxin (LPS, 10 μg) or peptidoglycan (PG, 40 μg) intranasally (3 days). After CD3 + cell depletion, lung homogenates were re-stimulated 24 h with LPS (100 ng/ml), PG (10 μg/ml), IL-23 (100 ng/ml) or vehicle. Human BAL macrophages were stimulated 24 h with PG (50 μg/ml) and IL-23 (100 ng/ml) or vehicle. The release of IL-22 was measured with ELISA and intracellular IL-22 with immunostaining. For statistics, either Dunnett or Students t test method was employed (n = 3-8).

RESULTS

Re-stimulation in vitro increased concentrations of mouse IL-22 protein irrespective of priming in vivo. A majority of macrophages in mouse lung and BAL samples displayed immunostaining for IL-22. In analogy, human BAL macrophages released IL-22 protein, and a third of these cells displayed immunostaining for IL-22.

CONCLUSIONS

Alveolar macrophages can produce and release IL-22 during the activation of the innate immune response and thereby constitute a potentially important regulator of mucosal host defence in the lungs.

Patients with cystic fibrosis have inducible IL-17+IL-22+ memory cells in lung draining lymph nodes

BACKGROUND

IL-17 is an important cytokine signature of the TH differentiation pathway TH17. This T-cell subset is crucial in mediating autoimmune disease or antimicrobial immunity in animal models, but its presence and role in human disease remain to be completely characterized.

OBJECTIVE

We set out to determine the frequency of TH17 cells in patients with cystic fibrosis (CF), a disease in which there is recurrent infection with known pathogens.

METHODS

Explanted lungs from patients undergoing transplantation or organ donors (CF samples=18; non-CF, nonbronchiectatic samples=10) were collected. Hilar nodes and parenchymal lung tissue were processed and examined for TH17 signature by using immunofluorescence and quantitative real-time PCR. T cells were isolated and stimulated with antigens from Pseudomonas aeruginosa and Aspergillus species. Cytokine profiles and staining with flow cytometry were used to assess the reactivity of these cells to antigen stimulation.

RESULTS

We found a strong IL-17 phenotype in patients with CF compared with that seen in control subjects without CF. Within this tissue, we found pathogenic antigen-responsive CD4+IL-17+ cells. There were double-positive IL-17+IL-22+ cells [TH17(22)], and the IL-22+ population had a higher proportion of memory characteristics. Antigen-specific TH17 responses were stronger in the draining lymph nodes compared with those seen in matched parenchymal lungs.

CONCLUSION

Inducible proliferation of TH17(22) with memory cell characteristics is seen in the lungs of patients with CF. The function of these individual subpopulations will require further study regarding their development. T cells are likely not the exclusive producers of IL-17 and IL-22, and this will require further characterization.

Changes in CD4+ T lymphocyte subsets and clinical outcomes of hepatitis B virus infection

Various clinical manifestations may develop in people infected with hepatitis B virus (HBV), ranging from asymptomatic infection to acute severe hepatitis B. Some infections become self-limiting when the virus is cleared, while approximately 90% of children and 10% of adults become HBV carriers or patients with chronic hepatitis B, who can further develop cirrhosis and hepatocellular carcinoma. CD4⁺ T lymphocytes play a central role in anti-infection immunity and can be divided into different subsets, including Th1, Th2, Treg, Th17, Th22, Th9 and Tfh. These T lymphocyte subsets all come from the same progenitor cells (Th0), although they have particular differentiation pathway and secrete different kinds of cytokines. Furthermore, they are able to interact with each other and change into each other. Particularly, the balances of Th1/Th2 and Th17/Treg play a vital role in determining the clinical outcomes of HBV infection.