Targeting interleukin-6 in inflammatory autoimmune diseases and cancers

Novel investigational drugs targeting IL-6 signaling for the treatment of depression

INTRODUCTION

Elevated levels of IL-6 have been implicated in the pathophysiology and treatment of major depressive disorder (MDD). Convergent evidence suggests that IL-6 primarily mediates proinflammatory functions via the soluble IL-6 receptor/trans-signaling, and anti-inflammatory functions via a transmembrane receptor (IL-6R). A targeted approach to selectively inhibit IL-6 trans-signaling may offer putative antidepressant effects.

AREAS COVERED

This review addresses three primary domains. The first focuses on the biological role of IL-6 within inflammation and its signal transduction pathways. The second addresses the potential contributions of IL-6 to the pathophysiology of MDD, and the mechanisms that may mediate these effects. Finally, the article outlines the therapeutic benefits of incorporating anti-inflammatory properties into the pharmacological treatment of MDD, and proposes inhibition of IL-6 signaling as a viable treatment strategy.

EXPERT OPINION

To improve drug development for the treatment of MDD, there is a critical need to identify promising targets. Target identification will require guidance from a strategic framework such as The Research Domain Criteria, and convincing evidence relating known targets to brain function under both physiological and pathological conditions. Although current evidence provides rationale for administering anti-IL-6 treatments in MDD, further studies confirming safety, target affinity and therapeutic benefits are warranted.

Cytokines as therapeutic targets in rheumatoid arthritis and other inflammatory diseases

The human immune system involves highly complex and coordinated processes in which small proteins named cytokines play a key role. Cytokines have been implicated in the pathogenesis of a number of inflammatory and autoimmune diseases. Cytokines are therefore attractive therapeutic targets in these conditions. Anticytokine therapy for inflammatory diseases became a clinical reality with the introduction of tumor necrosis factor (TNF) inhibitors for the treatment of severe rheumatoid arthritis. Although these therapies have transformed the treatment of patients with severe inflammatory arthritis, there remain significant limiting factors: treatment failure is commonly seen in the clinic; safety concerns remain; there is uncertainty regarding the relevance of immunogenicity; the absence of biomarkers to direct therapy decisions and high drug costs limit availability in some healthcare systems. In this article, we provide an overview of the key efficacy and safety trials for currently approved treatments in rheumatoid arthritis and review the major lessons learned from a decade of use in clinical practice, focusing mainly on anti-TNF and anti-interleukin (IL)-6 agents. We also describe the clinical application of anticytokine therapies for other inflammatory diseases, particularly within the spondyloarthritis spectrum, and highlight differential responses across diseases. Finally, we report on the current state of trials for newer therapeutic targets, focusing mainly on the IL-17 and IL-23 pathways.

Targeting dendritic cell function during systemic autoimmunity to restore tolerance

Systemic autoimmune diseases can damage nearly every tissue or cell type of the body. Although a great deal of progress has been made in understanding the pathogenesis of autoimmune diseases, current therapies have not been improved, remain unspecific and are associated with significant side effects. Because dendritic cells (DCs) play a major role in promoting immune tolerance against self-antigens (self-Ags), current efforts are focusing at generating new therapies based on the transfer of tolerogenic DCs (tolDCs) during autoimmunity. However, the feasibility of this approach during systemic autoimmunity has yet to be evaluated. TolDCs may ameliorate autoimmunity mainly by restoring T cell tolerance and, thus, indirectly modulating autoantibody development. In vitro induction of tolDCs loaded with immunodominant self-Ags and subsequent cell transfer to patients would be a specific new therapy that will avoid systemic immunosuppression. Herein, we review recent approaches evaluating the potential of tolDCs for the treatment of systemic autoimmune disorders.

Interleukin-6 deficiency corrects nephritis, lymphocyte abnormalities, and secondary Sjögren's syndrome features in lupus-prone Sle1.Yaa mice

OBJECTIVE

To assess disease features in Sle1.Yaa mice with genetic interleukin-6 (IL-6) deficiency.

METHODS

Sera and tissues were collected from C57BL/6 (B6), Sle1.Yaa, and Sle1.Yaa.IL-6(-/-) mice and analyzed for various features of disease. Using serum samples, autoantibody specificities were determined by enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence, cytokine production was analyzed by Luminex and ELISA, and levels of blood urea nitrogen were determined by ELISA. Renal, lung, and salivary gland tissue sections were evaluated for pathologic changes. Lymphocyte phenotypes, including CD4+ T cell cytokine production, and those of follicular and extrafollicular T helper subsets, germinal center B cells, and plasma cells, were determined using flow cytometry.

RESULTS

IL-6 deficiency not only ameliorated autoantibody production and renal disease in this model, but also effectively reduced inflammation of lungs and salivary glands. Furthermore, IL-6 deficiency abrogated differentiation of Th1 and extrafollicular T helper cells, germinal center B cells, and plasma cells in the spleen and eliminated renal T cells with IL-17, interferon-γ, and IL-21 production potential.

CONCLUSION

Our findings highlight IL-6-mediated T cell aberrations in Yaa-driven autoimmunity and support the concept of therapeutic IL-6/IL-6 receptor blockade in systemic lupus erythematosus and Sjögren's syndrome by impairing the production of autoantibodies and lymphocytic infiltration of the kidneys, lungs, and salivary glands.

The structure of human interleukin-11 reveals receptor-binding site features and structural differences from interleukin-6

Interleukin (IL)-11 is a multifunctional member of the IL-6 family of cytokines. Recombinant human IL-11 is administered as a standard clinical treatment for chemotherapy-induced thrombocytopaenia. Recently, a new role for IL-11 signalling as a potent driver of gastrointestinal cancers has been identified, and it has been demonstrated to be a novel therapeutic target for these diseases. Here, the crystal structure of human IL-11 is reported and the structural resolution of residues previously identified as important for IL-11 activity is presented. While IL-11 is thought to signalviaa complex analogous to that of IL-6, comparisons show important differences between the two cytokines and it is suggested that IL-11 engages GP130 differently to IL-6. In addition to providing a structural platform for further study of IL-11, these data offer insight into the binding interactions of IL-11 with each of its receptors and the structural mechanisms underlying agonist and antagonist variants of the protein.

A clinical perspective on the role of chronic inflammation in gastrointestinal cancer

Chronic inflammation has been identified as an important risk factor for the development of malignancy, and knowledge about its molecular and cellular mechanisms is increasing. Several chronic inflammatory diseases of the gastrointestinal tract are important as risk factors for malignancy and have been studied in detail. In this review, we summarize important molecular mechanisms in chronic inflammation and highlight established and potential links between chronic inflammation and gastrointestinal cancer. In addition, we present the role of chronic inflammation in numerous tumors within the gastrointestinal tract as well as the relevant pathways or epidemiologic observations linking the pathogenesis of these tumors to inflammation.

Interleukin-6: a villain in the drama of pancreatic cancer development and progression

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a poor prognosis and little treatment options. The development and progression of the disease is fostered by inflammatory cells and cytokines. One of these cytokines is interleukin-6 (IL-6), which plays an important role in a wide range of biologic activities.

DATA SOURCES

A systematic search of PubMed was performed to identify relevant studies using key words such as interleukin-6, inflammatory cytokines, inflammation and pancreatic cancer or PDAC. Articles related to IL-6 and pancreatic cancer were systematically reviewed.

RESULTS

IL-6 is elevated in the serum of pancreatic cancer patients and correlates with cachexia, advanced tumor stage and poor survival. Its expression is enhanced by hypoxia and proteins involved in pancreatic cancer development like Kras, mesothelin or ZIP4. IL-6 in turn contributes to the generation of a pro-tumorigenic microenvironment and is probably involved in angiogenesis and metastasis. In experimental mouse models of PDAC, IL-6 was important for the development and progression of precursor lesions.

CONCLUSION

IL-6 emerges as a key player in pancreatic cancer development and progression, and hence should be considered as a new therapeutic target.

Low incidence of IL6ST (gp130) mutations in exon 6 in lung cancer of a Chinese cohort

Lung cancer is an inflammation-associated epithelial carcinoma. A highly active interleukin 6 (IL-6)/glycoprotein 130 (gp130)/signal transducer and activator of transcription 3 (STAT3) pathway has been identified in a subset of primary lung cancer and closely correlated with tumor progression and poor prognosis. In a previous study, the frequent occurrence of somatic gain-of-function mutations was observed in the gp130-encoding IL6ST gene in exon 6 in 60% of inflammatory hepatocellular adenomas. Prompted by this finding, we assessed 110 Chinese lung carcinomas using PCR and direct DNA sequencing but found no somatic mutation of IL6ST in exon 6. However, one new potential germline missense mutation c.599C>G was identified in one adenocarcinoma that harbors wild-type epidermal growth factor receptor and KRAS. Protein modeling analysis showed that this mutation might not affect the gp130 protein conformation. Moreover, activated STAT3 was observed in most of the lung tumor tissues at a higher level than that in matched normal lung tissues. In conclusion, the c.599C>G mutation may be a new single nucleotide polymorphism of IL6ST, but mutations in exon 6 of this gene are not apparently common genetic variations occurring and leading to constitutive activation of STAT3 in lung cancer.

Association of interleukin-6 (-174 G/C) polymorphism with the prostate cancer risk: A meta-analysis

The aim of the present study was to determine whether the interleukin-6 (IL-6) (-174 G/C) gene polymorphism correlates with prostate cancer. A meta-analysis based on former studies was conducted and the results suggest that there was no significant association between IL-6 (-174 G/C) polymorphism and the prostate cancer risk. However, a recent study published in January 2014 showed that the GG genotype may be associated with an increased risk of prostate cancer in Caucasian subjects, whereas the CC genotype was associated with an increased risk in the African-American subjects, which was inconsistent with former studies. Databases, including PubMed, Embase, Web of Science, the Cochrane Library, Chinese Biomedical Literature Database and Wanfang database, were searched between January 1994 and March 2014 to determine the eligible IL-6 (-174 G/C) polymorphism studies and the susceptibility of the prostate cancer risk. A total of 11 studies with 10,745 cases and 13,473 controls fulfilled the inclusion criteria subsequent to assessment by two investigators. The pooled odds ratio (OR) with 95% confidence interval (95% CI) was calculated to examine the associations, and subgroup analyses were performed according to the ethnicity. Overall, no significant association was found between the IL-6 (-174 G/C) polymorphism and prostate cancer risk, whereas the subgroup analysis suggested that the association between the IL-6 (-174 G/C) polymorphism and prostate cancer was slightly significant under the homozygote (CC vs. GG: OR, 3.43; 95% CI, 1.01-11.71; P=0.049) and recessive models (CC vs.

GG/GC

OR, 3.51; 95% CI, 1.04-11.82; P=0.042) in African-American patients. However, no significant association was found in the Caucasian, Asian or mixed populations under the five genetic models by stratifying studies for ethnicity. In conclusion, the present study suggested that there was no significant association between the IL-6 (-174 G/C) polymorphism and prostate cancer risk in Caucasian and Asian patients, whereas the CC genotype may be associated with an increased risk in the African-American patients.

Interleukin-6 blockade in ocular inflammatory diseases

Interleukin-6 (IL-6) is a key cytokine featuring redundancy and pleiotropic activity. It plays a central role in host defence against environmental stress such as infection and injury. Dysregulated, persistent interleukin (IL)-6 production has been implicated in the development of various autoimmune, chronic inflammatory diseases and even cancers. Significant elevation of IL-6 has been found in ocular fluids derived from refractory/chronic uveitis patients. In experimental autoimmune uveitis models with IL-6 knock-out mice, IL-6 has shown to be essential for inducing inflammation. IL-6 blockade can suppress acute T helper type 17 (Th17) responses via its differentiation and, importantly, can ameliorate chronic inflammation. Tocilizumab, a recombinant humanized anti-IL-6 receptor antibody, has been shown to be effective in several autoimmune diseases, including uveitis. Herein, we discuss the basic biology of IL-6 and its role in development of autoimmune conditions, focusing particularly on non-infectious uveitis. It also provides an overview of efficacy and safety of tocilizumab therapy for ocular inflammatory diseases.

Cytokine inhibition in the treatment of COPD

Cytokines play an important part in many pathobiological processes of chronic obstructive pulmonary disease (COPD), including the chronic inflammatory process, emphysema, and altered innate immune response. Proinflammatory cytokines of potential importance include tumor necrosis factor (TNF)-α, interferon-γ, interleukin (IL)-1β, IL-6, IL-17, IL-18, IL-32, and thymic stromal lymphopoietin (TSLP), and growth factors such as transforming growth factor-β. The current objectives of COPD treatment are to reduce symptoms, and to prevent and reduce the number of exacerbations. While current treatments achieve these goals to a certain extent, preventing the decline in lung function is not currently achievable. In addition, reversal of corticosteroid insensitivity and control of the fibrotic process while reducing the emphysematous process could also be controlled by specific cytokines. The abnormal pathobiological process of COPD may contribute to these fundamental characteristics of COPD, and therefore targeting cytokines involved may be a fruitful endeavor. Although there has been much work that has implicated various cytokines as potentially playing an important role in COPD, there have been very few studies that have examined the effect of specific cytokine blockade in COPD. The two largest studies that have been reported in the literature involve the use of blocking antibody to TNFα and CXCL8 (IL-8), and neither has provided benefit. Blocking the actions of CXCL8 through its CXCR2 receptor blockade was not successful either. Studies of antibodies against IL-17, IL-18, IL-1β, and TSLP are currently either being undertaken or planned. There is a need to carefully phenotype COPD and discover good biomarkers of drug efficacy for each specific target. Specific groups of COPD patients should be targeted with specific anticytokine therapy if there is evidence of high expression of that cytokine and there are features of the clinical expression of COPD that will respond.

Comparative evaluation of recombinant protein production in different biofactories: the green perspective

In recent years, the production of recombinant pharmaceutical proteins in heterologous systems has increased significantly. Most applications involve complex proteins and glycoproteins that are difficult to produce, thus promoting the development and improvement of a wide range of production platforms. No individual system is optimal for the production of all recombinant proteins, so the diversity of platforms based on plants offers a significant advantage. Here, we discuss the production of four recombinant pharmaceutical proteins using different platforms, highlighting from these examples the unique advantages of plant-based systems over traditional fermenter-based expression platforms.

IL-6 and related cytokines as the critical lynchpins between inflammation and cancer

Inflammatory responses play pivotal roles in cancer development, including tumor initiation, promotion, progression, and metastasis. Cytokines are now recognized as important mediators linking inflammation and cancer, and are therefore potential therapeutic and preventive targets as well as prognostic factors. The interleukin (IL)-6 family of cytokines, especially IL-6 and IL-11, is highly up-regulated in many cancers and considered as one of the most important cytokine families during tumorigenesis and metastasis. This review discusses molecular mechanisms linking the IL-6 cytokine family to solid malignancies and their treatment.

Cutaneous expressions of interleukin-6 and neutrophil elastase as well as levels of serum IgA antibodies to gliadin nonapeptides, tissue transglutaminase and epidermal transglutaminase: implications for both autoimmunity and autoinflammation involvement in dermatitis herpetiformis

Introduction

Dermatitis herpetiformis (DH) seems to be a chronic immune-mediated inflammatory disease of partially known origin. In light of its known biological functions and its involvement in tissue pathology in other disease states, particularly in nickel-induced allergic contact dermatitis coexisting with DH, it would appear that the central and peripheral response by neutrophils and their mediators (e.g. neutrophil elastase – NE) in DH may be partially mediated by interleukin-6 (IL-6).

The aim of the study was to assess the role of IL -6 in DH lesions by examining the relationships between IL -6/NE cutaneous expression and levels of serum anti-nonapeptides of gliadin (npG) IgA, anti-tissue transglutaminase (tTG) immunoglobulin A (IgA), anti-epidermal transglutaminase (eTG) IgA in DH.

Material and methods

In total, 24 DH patients having IgA cutaneous deposition were studied. Immunohistochemistry on paraffin-embedded sections with quantitative digital morphometry was used to measure the intensity of IL -6 and NE cutaneous expressions. Levels of serum anti-npG IgA, anti-tTG IgA and anti-eTG IgA were evaluated with ELISA.

Results

We found no statistically significant correlation between the NE and IL -6 expression intensities. Our results revealed also a lack of correlations between NE/IL -6 expressions and levels of anti-npG IgA, anti-tTG IgA, anti-eTG IgA in DH. However, the IL -6 expression level was significantly lower than that of NE.

Conclusions

The lack of correlations suggested no substantial interactions between IL -6, NE, IgA/npG, IgA/tTG or IgA/eTG in DH. Presented results might indicate the heterogenetic nature of DH pathogenesis suggesting further that both autoimmune and autoinflammatory phenomena may be involved in DH cutaneous pathology.

Uncovering the immune tumor microenvironment in non-small cell lung cancer to understand response rates to checkpoint blockade and radiation

The study of immunology has led to breakthroughs in treating non-small cell lung cancer (NSCLC). The recent approval of an anti-PD1 checkpoint drug for NSCLC has generated much interest in novel combination therapies that might provide further benefit for patients. However, a better understanding of which combinations may (or may not) work in NSCLC requires understanding the lung immune microenvironment under homeostatic conditions and the changes in that microenvironment in the setting of cancer progression and with radiotherapy. This review provides background information on immune cells found in the lung and the prognostic significance of these cell types in lung cancer. It also addresses current clinical directions for the combination of checkpoint inhibitors with radiation for NSCLC.