Targeting IL-6 for the treatment of rheumatoid arthritis: Phase II investigational drugs

Role of interleukin-6-mediated inflammation in the pathogenesis of inflammatory bowel disease: focus on the available therapeutic approaches and gut microbiome

Inflammatory bowel disease (IBD) is considered a chronic inflammatory and multifactorial disease of the gastrointestinal tract. Crohn's disease (CD) and ulcerative colitis (UC) are two types of chronic IBD. Although there is no accurate information about IBD pathophysiology, evidence suggests that various factors, including the gut microbiome, environment, genetics, lifestyle, and a dysregulated immune system, may increase susceptibility to IBD. Moreover, inflammatory mediators such as interleukin-6 (IL-6) are involved in the immunopathogenesis of IBDs. IL-6 contributes to T helper 17 (Th17) differentiation, mediating further destructive inflammatory responses in CD and UC. Moreover, Th1-mediated responses participate in IBD, and the antiapoptotic IL-6/IL-6 receptor (IL-6R)/signal transducer and activator of transcription 3 (STAT3) signals are responsible for preserving Th1 cells in the site of inflammation. It has been revealed that fecal bacteria isolated from UC-active and UC-remission patients stimulate the hyperproduction of several cytokines, such as IL-6, tumor necrosis factor-α (TNF-α), IL-10, and IL-12. Given the importance of the IL-6/IL-6R axis, various therapeutic options exist for controlling or treating IBD. Therefore, alternative therapeutic approaches such as modulating the gut microbiome could be beneficial due to the failure of the target therapies so far. This review article summarizes IBD immunopathogenesis focusing on the IL-6/IL-6R axis and discusses available therapeutic approaches based on the gut microbiome alteration and IL-6/IL-6R axis targeting and treatment failure.

Emerging therapies for juvenile arthritis: agents in early clinical trials

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory rheumatic condition in childhood. The management of JIA has been revolutionized thanks to the development of new powerful drugs and the possibility to conduct controlled clinical trials with support from legislative initiatives and availability of international collaborative networks. Trials are still needed in children because we now have new drugs related to specific JIA category.

AREAS COVERED

The review is centered on the latest achievements in the field, focusing on new investigational drugs which are currently or have been recently tested for JIA treatment, encompassing agents in early phase of clinical development.

EXPERT OPINION

Despite the tremendous improvement witnessed in the field of JIA treatment in the past 20 years, there are still many unmet needs to be prioritized. Studies on disease pathogenesis will hopefully help in the identification of new treatment targets for individual JIA categories, that could possibly favor a stricter disease control and contribute to solve the issue of refractory JIA. Novel strategies aimed at the prevention of the risk of long-term joint damage are also desirable, as well as the discovery of predictive biomarkers for treatment efficacy and safety in the individual patient.

Neuroprotective and anti-inflammatory effect of pectolinarigenin, a flavonoid from Amazonian Aegiphila integrifolia (Jacq.), against lipopolysaccharide-induced inflammation in astrocytes via NFκB and MAPK pathways

Neurodegenerative diseases affect millions of people worldwide. Regardless of the underlying cause, neuroinflammation is the greatest risk factor for developing any of these disorders. Pectolinarigenin (PNG) is an active flavonoid with several biological properties, anti-metastatic and anti-inflammatory activity. This study investigate the biological effects of PNG in macrophage and astrocyte cultures, with focus on elucidating the molecular mechanisms involved in the PNG activity. J774A.1 murine macrophage or cerebral cortex primary astrocytes primary cultures were treated with different concentration of PNG (1-160 μM) and the inflammatory process was stimulated by LPS (1 μg/ml) and the effect of PNG in different inflammatory markers were determined. PNG did not affect astrocyte or macrophage viability. Moreover, this flavonoid reduced NO• release in macrophages, attenuated astrocyte activation by preventing the overexpression of glial fibrillary acidic protein, and decreased the release of inflammatory mediators, IL-1β and IL-6 induced by LPS by the glial cell, as well as enhanced basal levels of IL-10. In addition, PNG suppressed NFκB, p38MAPK and ERK1/2 phosphorylation in astrocytes culture induced by LPS. The results show clear evidence that this novel flavonoid protects astrocytes against LPS-induced inflammatory toxicity. In conclusion, PNG presents neuroprotective and anti-inflammatory property through the inhibition of inflammatory signaling pathways.

Reshaping nanobodies for affinity purification on protein a

Nanobodies (Nbs) are 15 kDa recombinant, single-domain, antigen-specific fragments derived from heavy-chain only antibodies (HCAbs) occurring naturally in species of Camelidae. The beneficial properties of Nbs make them suitable tracers for diagnostic and therapeutic purposes. Whereas Nbs with a terminal hexa-histidine tag (His-tag) are easily purified via immobilized metal affinity chromatography, previous studies revealed a negative impact of the His-tag on the biodistribution of Nb-based tracers. Thus, it is important to develop alternative purification methods for Nbs without a His-tag. Protein A (SpA), a surface protein of Staphylococcus aureus, binds the Fc-region of IgG molecules and also to a lesser extent human heavy chain family-3 variable (VH) regions. Nbs also belong to this VH family, although many fail to be recognized by SpA. Here it is demonstrated that non-SpA binding Nbs can be mutagenized for purification by SpA affinity chromatography and that these Nb variants retain their thermostability and antigen affinity, while biodistribution remains unaffected.

Phytol, a Chlorophyll Component, Produces Antihyperalgesic, Anti-inflammatory, and Antiarthritic Effects: Possible NFκB Pathway Involvement and Reduced Levels of the Proinflammatory Cytokines TNF-α and IL-6

Phytol is a diterpene constituent of chlorophyll and has been shown to have several pharmacological properties, particularly in relation to the management of painful inflammatory diseases. Arthritis is one of the most common of these inflammatory diseases, mainly affecting the synovial membrane, cartilage, and bone in joints. Proinflammatory cytokines, such as TNF-α and IL-6, and the NFκB signaling pathway play a pivotal role in arthritis. However, as the mechanisms of action of phytol and its ability to reduce the levels of these cytokines are poorly understood, we decided to investigate its pharmacological effects using a mouse model of complete Freund's adjuvant (CFA)-induced arthritis. Our results showed that phytol was able to inhibit joint swelling and hyperalgesia throughout the whole treatment period. Moreover, phytol reduced myeloperoxidase (MPO) activity and proinflammatory cytokine release in synovial fluid and decreased IL-6 production as well as the COX-2 immunocontent in the spinal cord. It also downregulated the p38MAPK and NFκB signaling pathways. Therefore, our findings demonstrated that phytol can be an innovative antiarthritic agent due to its capacity to attenuate inflammatory reactions in joints and the spinal cord, mainly through the modulation of mediators that are key to the establishment of arthritic pain.

Drug delivery to macrophages: A review of targeting drugs and drug carriers to macrophages for inflammatory diseases

Macrophages play a key role in defending against foreign pathogens, healing wounds, and regulating tissue homeostasis. Driving this versatility is their phenotypic plasticity, which enables macrophages to respond to subtle cues in tightly coordinated ways. However, when this coordination is disrupted, macrophages can aid the progression of numerous diseases, including cancer, cardiovascular disease, and autoimmune disease. The central link between these disorders is aberrant macrophage polarization, which misguides their functional programs, secretory products, and regulation of the surrounding tissue microenvironment. As a result of their important and deterministic roles in both health and disease, macrophages have gained considerable attention as targets for drug delivery. Here, we discuss the role of macrophages in the initiation and progression of various inflammatory diseases, summarize the leading drugs used to regulate macrophages, and review drug delivery systems designed to target macrophages. We emphasize strategies that are approved for clinical use or are poised for clinical investigation. Finally, we provide a prospectus of the future of macrophage-targeted drug delivery systems.

The Role of Monocytes and Macrophages in Autoimmune Diseases: A Comprehensive Review

Monocytes (Mo) and macrophages (Mϕ) are key components of the innate immune system and are involved in regulation of the initiation, development, and resolution of many inflammatory disorders. In addition, these cells also play important immunoregulatory and tissue-repairing roles to decrease immune reactions and promote tissue regeneration. Several lines of evidence have suggested a causal link between the presence or activation of these cells and the development of autoimmune diseases. In addition, Mo or Mϕ infiltration in diseased tissues is a hallmark of several autoimmune diseases. However, the detailed contributions of these cells, whether they actually initiate disease or perpetuate disease progression, and whether their phenotype and functional alteration are merely epiphenomena are still unclear in many autoimmune diseases. Additionally, little is known about their heterogeneous populations in different autoimmune diseases. Elucidating the relevance of Mo and Mϕ in autoimmune diseases and the associated mechanisms could lead to the identification of more effective therapeutic strategies in the future.

Sirukumab for the treatment of rheumatoid arthritis: update on sirukumab, 2018

INTRODUCTION

Interleukin-6 (IL-6) is well-known for its pro-inflammatory properties, has been proven to target a wide range of cells in the joint, and has been implicated in extra-articular and articular manifestations in rheumatoid arthritis (RA). Tocilizumab (TCZ) is now widely used in patients with active RA and a number of additional agents that target the IL-6 pathways are under development, including sirukumab (SRK). Areas covered: SRK is an IgG1κ human anti-IL-6 monoclonal antibody which binds to IL-6 and prevents IL-6-mediated downstream effects. Initial trial results in phase-III studies in patients with RA seemed promising, showing improved results in patients with moderate-to-severe RA. Data derive from the phase-II study and the various SIRROUND studies (phase III). Expert commentary: The available data show that SRK50 mg every 4 weeks or 100 mg every 2 weeks will be effective in treating the RA population, with clinical improvements as early as week 2 and sustained over time. The adverse-event profile seems to be similar to TCZ, except for an increased mortality post open-label studies due to infections and cardiovascular events, our knowledge of which will be deepened with post-marketing surveillance and registry data.

Ontology and Function of Fibroblast-Like and Macrophage-Like Synoviocytes: How Do They Talk to Each Other and Can They Be Targeted for Rheumatoid Arthritis Therapy?

Fibroblast-like synoviocytes (FLS) and macrophage-like synoviocytes (MLS) are the two main cellular components of the synovium. It has been widely reported that FLS and MLS play essential roles in the joint pathology of rheumatoid arthritis (RA). Although various studies have analyzed both human and animal tissues and have shown that both cell types are involved in different stages of RA, ontology, and specific functions of both cell populations and their interactions are not well understood. In this review, we will summarize recent research on FLS and MLS in RA and focus on the development and function of two predominant synovial cell types. In addition, we will discuss the communication between FLS or MLS and highlight potential treatments for RA that involve synoviocytes.

IL-6 secreted by cancer-associated fibroblasts promotes epithelial-mesenchymal transition and metastasis of gastric cancer via JAK2/STAT3 signaling pathway

Cancer-associated fibroblasts (CAFs), as the activated fibroblasts in tumor stroma, are important modifiers of tumor progression. However, the molecular mechanisms underlying the tumor-promoting properties of CAFs in gastric cancer remain unclear. Here, we show that CAFs isolated from gastric cancer produce significant amounts of interleukin-6 (IL-6). CAFs enhances the migration and EMT of gastric cancer cells through the secretion of IL-6 that activates Janus kinase 2/signal transducers and activators of transcription (JAK2/STAT3) pathway in gastric cancer cells, while deprivation of IL-6 using a neutralizing antibody or inhibition of JAK/STAT3 pathway with specific inhibitor AG490 markedly attenuates these phenotypes in gastric cancer cells induced by CAFs. Moreover, silencing IL-6 expression in CAFs or inhibiting JAK2/STAT3 pathway in gastric cancer cells impairs tumor peritoneal metastasis induced by CAFs in vivo. Taken together, these results suggest that CAFs in the tumor microenvironment promote the progression of gastric cancer through IL-6/JAK2/STAT3 signaling, and IL-6 targeted therapy could be a complementary approach against gastric cancer by exerting their action on stromal fibroblasts.

The sneaking ligand approach for cell type-specific modulation of intracellular signalling pathways

Small molecules interfering with intracellular signalling pathways are used in the treatment of multiple diseases including RA. However, small molecules usually affect signalling in most cell types, not only in those which need to be targeted. This general inhibition of signalling pathways causes often adverse effects, which could be avoided by cell type-specific inhibitors. For cell-type specific modulation of signal transduction, we developed the sneaking ligand fusion proteins (SLFPs). SLFPs contain three domains: (1) the binding domain mediating cell type-specific targeting and endocytosis; (2) the endosomal release sequence releasing the effector domain into the cytoplasm; (3) the effector domain modulating signalling. Using our SLFP NF-kappaB inhibitor termed SLC1 we demonstrated that cell-type-specific modulation of intracellular signalling pathways is feasible, that endothelial NF-kappaB activation is critical for arthritis and peritonitis and that SLFPs help to identify disease-relevant pathways in defined cell types. Hence, SLFPs may improve risk-benefit ratios of therapeutic interventions.

Immune Mechanisms and Novel Targets in Rheumatoid Arthritis

Significant progress has been made in understanding the pathophysiology of rheumatoid arthritis. It is widely recognized that early institution of treatment is one of the best predictive factors for response to therapy. Several novel approaches are currently being investigated and several novel biologics are in various stages of development. With advances in the fields of proteomics, genomics, and metabolomics, specific phenotypes of the disease can be better identified and specific therapies for particular phases of the disease and specific patients will allow for improved control of this condition.

Probiotic bacteria: a viable adjuvant therapy for relieving symptoms of rheumatoid arthritis

The burgeoning use of probiotics has proliferated during the past two decades. However, the effect of probiotic administration for either the prevention or treatment of rheumatoid arthritis (RA) has been investigated in a limited number of studies. Randomized controlled clinical trials have provided evidences that specific probiotics supplementation exhibit anti-inflammatory effects, help to increase daily activities and alleviate symptoms in patients with RA. Therefore, using probiotic bacteria as an adjuvant therapy may be considered as a promising treatment option for RA. This review summarizes the available data about the therapeutic and preventive effect of probiotics in RA, together with probiotic supplement as a possible therapy in clinical treatment.

Association of IL-6 polymorphisms with chronic obstructive pulmonary disease risk: meta-analysis of genetic association, gene expression and expression quantitative trait locus analysis

Aim: IL-6 might play an important role in the mechanism of chronic obstructive pulmonary disease (COPD). This study assessed the relationship of rs1800796 and rs1800797 of IL-6 with COPD. Materials & methods: We conducted meta-analysis and gene expression analysis using published datasets to examine the associations between IL-6 SNPs and COPD. Results: rs1800796 was significantly associated with COPD, yielding a pooled odds ratio of 0.52 (95% CI: 0.33–0.84; p = 0.007), and showed cis-expression quantitative trait locus associations (p = 0.02148). Differential gene expression analysis found that IL-6 was upregulated in COPD cases compared with controls. The associations of rs1800797 with COPD were not significant. Conclusion: The findings showed that rs1800796 was associated with COPD in Europeans and might affect COPD risk through disturbing IL-6 gene expression.

Flavonoids as Cytokine Modulators: A Possible Therapy for Inflammation-Related Diseases

High levels of cytokines, such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6, are associated with chronic diseases like rheumatoid arthritis, asthma, atherosclerosis, Alzheimer's disease and cancer; therefore cytokine inhibition might be an important target for the treatment of these diseases. Most drugs used to alleviate some inflammation-related symptoms act by inhibiting cyclooxygenases activity or by blocking cytokine receptors. Nevertheless, these drugs have secondary effects when used on a long-term basis. It has been mentioned that flavonoids, namely quercetin, apigenin and luteolin, reduce cytokine expression and secretion. In this regard, flavonoids may have therapeutical potential in the treatment of inflammation-related diseases as cytokine modulators. This review is focused on current research about the effect of flavonoids on cytokine modulation and the description of the way these compounds exert their effect.

Emerging Therapies for Rheumatoid Arthritis

Diverse strategies to develop novel treatments for rheumatoid arthritis which specifically target those patients who do not respond to available medications, including biologics, are currently being explored. New potential therapeutic approaches which may become available as part of standard therapeutic regimens include the propagation of regulatory T cells and-in the future-of regulatory B cells. New biologic disease-modifying antirheumatic drugs (b-DMARDs) against interleukin-17 and -6, granulocyte-macrophage colony-stimulating factor, and complement component 5 are now standard components of clinical treatment programs. In addition, recent data indicate that bispecific monoclonal antibody therapies may be more effective than monoclonal antibody monotherapies. It is also becoming apparent that the use of more toxic b-DMARDs against B cells, a therapeutic strategy already being applied in the treatment of hematological diseases, may also be efficacious for treating B cell-mediated autoimmune diseases. Undoubtedly, more small molecules will be developed in the future, and combination therapies with, for example, kinase inhibitors and b-DMARDs, will most likely be tested. Finally, immunoproteasome inhibitors will become available for patients with B cell-mediated autoimmunities, which are refractory to currently available treatment options. The new and exciting extension of current treatment options for rheumatoid arthritis, biosimilars, will not be discussed in this review as details on these agents are available in recently published reports.

Novel Immunotherapeutic Avenues for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease. It leads to irreversible joint damage, physical handicap, and reduced life expectancy. The past two decades have seen considerable therapeutic advances with the development of biologic treatments to block proinflammatory cytokines or modulate lymphocyte function, followed by the development of small molecules to target intracellular signaling. Nevertheless, only a minority of patients can achieve disease remission, especially long term, warranting further investigation into newer therapeutic options. Targeting single proinflammatory pathways may not be sufficient, as suggested by variable results with T helper (Th)-17-related cytokine blockade. Multilevel information from 'omics' techniques along with data from mechanistic studies might facilitate the identification of pivotal checkpoints in RA disease pathogenesis and the subsequent development of new effective treatments.

IL-6 Plays a Crucial Role in HBV Infection

Interleukin-6 (IL-6), a cytokine mainly produced by activated monocytes, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-6 in regulating immunity to infections are currently being defined. Remarkably, IL-6-mediated cellular and humoral immune responses play a crucial role in determining the outcome of viral infection. This article reviews the current knowledge on the critical role of IL-6 in hepatitis B virus (HBV) infection. As a competent intermediary, IL-6 derived from activated monocytes plays an important role in promoting lymphocytes responses that are essential for effective viral control. However, as a mediator of inflammation, IL-6 is also involved in the development of HBV-induced liver cirrhosis and exacerbating liver injury. Overall, the current data point to IL-6 as an immunoregulatory cytokine in HBV infection. Immunotherapeutic strategies aimed at optimizing the beneficial effects of IL-6 in HBV infection may prove to be an ordeal in the future, as they should foster the strengths of IL-6 while circumventing potential drawbacks.

Anti-DR5 mAb inhibits proliferation of human fibroblast-like synovial cells and reduces their cytokine secretion in vitro

BACKGROUND

We have previously reported that anti-death receptor 5 (DR5) monoclonal antibody (mAb) is therapeutically effective in the treatment of rheumatoid arthritis (RA) in a collagen-induced arthritis rat model. However, the molecular mechanism and the effect of anti-DR5 mAb on proapoptotic genes and cytokine secretion in the human fibroblast-like synovial cells (FLS) requires further clarification. This study may provide new evidence for the application of anti-DR5 mAb as a treatment for RA.

METHODS

Human FLS were isolated from patients with RA and were treated with anti-DR5 mAb. An MTT assay and flow cytometry were used to detect the induction of apoptosis in vitro. Cytokine secretion by the FLS was detected using the enzyme-linked immunosorbent assay. The mRNA expression was assessed by reverse transcription polymerase chain reaction, and the protein expression was analyzed by Western blot. The apoptotic pathway was investigated further using a caspase inhibition assay.

RESULTS

Anti-DR5 mAb-induced apoptosis in human RA FLS in vitro. The protein expressions of caspase-8, -3, and -9 were decreased in human anti-DR5 mAb-treated FLS in a dose-dependent manner through exposure to a caspase inhibitor, indicating that anti-DR5 mAb induction of apoptosis is through the caspase pathway. Decreased levels of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were detected after treatment with anti-DR5 mAb in vitro.

CONCLUSION

Anti-DR5 mAb may induce apoptosis in human FLS through the caspase pathway and through decreased secretions of TNF-α and IFN-γ.

Where are we heading to in pharmacological IBD therapy?

After a relatively long time of failed developments and negative clinical trials in pharmacological inflammatory bowel disease (IBD) therapy we now phase a time of a great number of successful studies and new therapy principles that will most likely make it into clinical practice. This will change the landscape of IBD therapy in future markedly. Many new therapeutic principles have been developed and old ones that seemed to have failed such as anti-sense technology suddenly now provide promising results. Some initially promising therapies will need further development or have failed such as Trichuris suis ova therapy (but not helminth therapy in general), CCR9 targeted therapies or recombinant IL-10. In contrast anti-leukocate trafficking therapies appear to be quite promising. Vedolizumab is the first in class anti-integrin antibody that was approved for the therapy of CD and UC recently. Other anti-integrin antibodies and small molecule adhesion inhibitors will most likely be approved in the next years for IBD therapy. Tofacitinib, a small molecule JAK inhibitor, is a promising candidate for the treatment of UC. Phosphatidylcholine may be a future option for patients with 5-ASA refractory UC or 5-ASA intolerance. The preliminary data for Mongersen, a Smad7 antisense oligonucleotide, are promising despite some concerns about long term effect of TGFβ induction. Anti IL6 strategies will hopefully be further evaluated keeping in mind the caveat of a lack of CRP induction in anti-IL6 treated patients. Stem cell transplantation will become an option for patients that have experienced failure of established medications. Fecal microbiota transplantation and also perhaps combined probiotic therapy is a field that will be evaluated in more detail in the near future especially for UC patients. Based on these new developments treatment algorithms need to be updated. This review will reflect these current developments and give a perspective for future IBD therapy.

Cytokine-modulating strategies and newer cytokine targets for arthritis therapy

Cytokines are the key mediators of inflammation in the course of autoimmune arthritis and other immune-mediated diseases. Uncontrolled production of the pro-inflammatory cytokines such as interferon-γ (IFN-γ), tumor necrosis factor α (TNFα), interleukin-6 (IL-6), and IL-17 can promote autoimmune pathology, whereas anti-inflammatory cytokines including IL-4, IL-10, and IL-27 can help control inflammation and tissue damage. The pro-inflammatory cytokines are the prime targets of the strategies to control rheumatoid arthritis (RA). For example, the neutralization of TNFα, either by engineered anti-cytokine antibodies or by soluble cytokine receptors as decoys, has proven successful in the treatment of RA. The activity of pro-inflammatory cytokines can also be downregulated either by using specific siRNA to inhibit the expression of a particular cytokine or by using small molecule inhibitors of cytokine signaling. Furthermore, the use of anti-inflammatory cytokines or cytokine antagonists delivered via gene therapy has proven to be an effective approach to regulate autoimmunity. Unexpectedly, under certain conditions, TNFα, IFN-γ, and few other cytokines can display anti-inflammatory activities. Increasing awareness of this phenomenon might help develop appropriate regimens to harness or avoid this effect. Furthermore, the relatively newer cytokines such as IL-32, IL-34 and IL-35 are being investigated for their potential role in the pathogenesis and treatment of arthritis.

Analysis of autoantibody profiles in osteoarthritis using comprehensive protein array concepts

Osteoarthritis (OA) is the most common rheumatic disease and one of the most disabling pathologies worldwide. To date, the diagnostic methods of OA are very limited, and there are no available medications capable of halting its characteristic cartilage degeneration. Therefore, there is a significant interest in new biomarkers useful for the early diagnosis, prognosis, and therapeutic monitoring. In the recent years, protein microarrays have emerged as a powerful proteomic tool to search for new biomarkers. In this study, we have used two concepts for generating protein arrays, antigen microarrays, and NAPPA (nucleic acid programmable protein arrays), to characterize differential autoantibody profiles in a set of 62 samples from OA, rheumatoid arthritis (RA), and healthy controls. An untargeted screen was performed on 3840 protein fragments spotted on planar antigen arrays, and 373 antigens were selected for validation on bead-based arrays. In the NAPPA approach, a targeted screening was performed on 80 preselected proteins. The autoantibody targeting CHST14 was validated by ELISA in the same set of patients. Altogether, nine and seven disease related autoantibody target candidates were identified, and this work demonstrates a combination of these two array concepts for biomarker discovery and their usefulness for characterizing disease-specific autoantibody profiles.