Inhibition of the IL-6 signaling pathway: a strategy to combat chronic inflammatory diseases and cancer

Biologics that inhibit the Th17 pathway and related cytokines to treat inflammatory disorders

INTRODUCTION

Advances in the understanding of TNF-α and IL-17 synergistic functions have recently led to the concept that patients who do not respond or who respond inadequately to TNF-α inhibitors may have IL-17-driven diseases, opening up the way for a new class of therapeutic development: Th17-inhibitors. Areas covered: In this review, the authors discuss the central role that the IL-23/Th17 axis plays in the pathogenesis of several inflammatory diseases, such as psoriasis, highlighting its position as a relevant therapeutic target. In particular, the authors start by giving a brief historical excursus on biologic agent development up until the success of TNF-α inhibitors, and continue with an overview of IL12/23 pathway inhibition. Next, they describe Th17 cell biology, focusing on the role of IL-17 in host defense and in human immune-inflammatory diseases, discussing the use and side effects of IL-17 inhibitors. Expert opinion: The IL-23/Th17 signaling pathway plays a central role in the pathogenesis of several inflammatory diseases, such as psoriasis. Recent data has demonstrated that biologics neutralizing IL-17 (ixekizumab, secukinumab) or its receptor (brodalumab) are highly effective with a positive safety profile in treating moderate to severe psoriasis, offering new treatment possibilities, especially for patients who do not respond adequately to anti-TNF-α therapies.

Targeting interlukin-6 to relieve immunosuppression in tumor microenvironment

Immunotolerance is one of the hallmarks of malignant tumors. Tumor cells escape from host immune surveillance through various mechanisms resulting in tumor progression and therapeutic resistance. Interlukin-6 is a proinflammatory cytokine involved in many physiological and pathological processes by integrating with multiple intracellular signaling pathways. Aberrant expression of interlukin-6 is associated with the growth, metastasis, and chemotherapeutic resistance in a wide range of cancers. Interlukin-6 exerts immunosuppressive capacity mostly by stimulating the infiltrations of myeloid-derived suppressor cells, tumor-associated neutrophils, and cancer stem-like cells via Janus-activated kinase/signal transducer and activator of transcription 3 pathway in tumor microenvironment. On this foundation, blockage of interlukin-6 signal may provide potential approaches to novel therapies. In this review, we introduced interlukin-6 pathways and summarized molecular mechanisms related to interlukin-6-induced immunosuppression of tumor cell. We also concluded recent clinical studies targeting interlukin-6 as an immune-based therapeutic intervention in patients with cancer.

Clinical response to non-surgical periodontal treatment in patients with interleukin-6 and interleukin-10 polymorphisms

Background

Genetic polymorphisms are commonly associated with altered transcriptional activity and possibly make individuals more susceptible to periodontal disease development, increased disease severity and poor treatment outcome. The study aimed to determine the effect of Interleukin-6 (IL-6) -572 G/C (rs1800796) and IL-10 -592 C/A (rs1800872) polymorphisms on the outcomes of non-surgical periodontal therapy in a Caucasian population.

Material and Methods

Sixty-eight patients with chronic periodontal disease were grouped according to their genotype: IL-6, IL-10, IL-6 and IL-10 susceptible (SCP) and non-susceptible (NSCP). All individuals were clinically evaluated at the first visit, and blood sample were collected from patients after checking the inclusion and exclusion criteria of the study. All patients received non-surgical periodontal therapy from a single-blinded periodontist. Clinical periodontal measurements were repeated 45 days after therapy.

Results

This population mean aged 47.63 years included 52.2% females and 58.2% non-smokers. Following DNA separation and genotyping, 65.7% of patients were homozygous carriers of the IL-6 - 572G; 49.3% were carriers of the IL-10 -592A- allele (AA and CA genotypes); and 35.8% carried SCP genotypes for both polymorphisms. The clinical parameters after therapy were not associated with the genotype status. The multiple logistic regression analysis did not show any statistically significant association between the genotypes and the variables tested.

Conclusions

Within the limitations of this longitudinal study, it can be suggested that IL-6 -572 G/C and IL-10 -592 C/A polymorphisms as well as their combination do not influence the outcome of nonsurgical periodontal therapy in Caucasian patients diagnosed with chronic periodontal disease.

Key words:Gene polymorphism, genetics, interleukins, periodontal disease, treatment outcome.

Predictive value of salivary microRNA-320a, vascular endothelial growth factor receptor 2, CRP and IL-6 in Oral lichen planus progression

INTRODUCTION

MicroRNA (miRNA) 320a and vascular endothelial growth factor receptor 2 (VEGFR-2) expression as the angiogenic biomarkers might be therapeutic targets in Oral lichen planus (OLP). IL-6 and C-reactive protein (CRP) could be prognostic in OLP, dysplastic OLP and Oral squamous cell carcinoma (OSCC). Therefore, their salivary detections as the noninvasive tools were aimed in this study.

MATERIALS AND METHODS

Histopathologic examinations were carried out to distinguish the patients with dysplastic OLP and OSCC. Salivary microRNA expression analysis was performed using RT-qPCR. IL-6 and CRP levels were also measured in saliva via ELISA method. VEGFR-2 expression in various sections was evaluated using immunohistochemistry.

RESULTS

A significant decrease in salivary microRNA-320a in dysplastic OLP and OSCC but not in OLP without dysplasia was found. VEGFR-2 visualization confirmed the increasing angiogenic process in these cases. A significant increase in IL-6 level was detected in cases with OLP, dysplastic OLP and OSCC. CRP levels also showed a significant increase in dysplastic OLP and OSCC. A positive correlation between IL-6 and CRP levels was found.

CONCLUSION

Identification of the salivary microRNA-320a and hs-CRP might provide a convenient noninvasive predictive tool for dysplastic OLP, whereas IL-6 could be a diagnostic and therapeutic target in both OLP without dysplasia and dysplastic OLP cases.

Susceptibility to chronic inflammation: an update

Chronic inflammation is defined by the persistence of inflammatory processes beyond their physiological function, resulting in tissue destruction. Chronic inflammation is implicated in the progression of many chronic diseases and plays a central role in chronic inflammatory and autoimmune disease. As such, this review aims to collate some of the latest research in relation to genetic and environmental susceptibilities to chronic inflammation. In the genetic section, we discuss some of the updates in cytokine research and current treatments that are being developed. We also discuss newly identified canonical and non-canonical genes associated with chronic inflammation. In the environmental section, we highlight some of the latest updates and evidence in relation to the role that infection, diet and stress play in promoting inflammation. The aim of this review is to provide an overview of the latest research to build on our current understanding of chronic inflammation. It highlights the complexity associated with chronic inflammation, as well as provides insights into potential new targets for therapies that could be used to treat chronic inflammation and consequently prevent disease progression.

Cytokine Imbalance as a Common Mechanism in Both Psoriasis and Rheumatoid Arthritis

Psoriasis (PS) and rheumatoid arthritis (RA) are immune-mediated inflammatory diseases. Previous studies showed that these two diseases had a common pathogenesis, but the precise molecular mechanism remains unclear. In this study, RNA sequencing of peripheral blood mononuclear cells was employed to explore both the differentially expressed genes (DEGs) of 10 PS and 10 RA patients compared with those of 10 healthy volunteers and the shared DEGs between these two diseases. Bioinformatics network analysis was used to reveal the connections among the shared DEGs and the corresponding molecular mechanism. In total, 120 and 212 DEGs were identified in PS and RA, respectively, and 31 shared DEGs were identified. Bioinformatics analysis indicated that the cytokine imbalance relevant to key molecules (such as extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), tumor necrosis factor (TNF), colony-stimulating factor 3 (CSF3), interleukin- (IL-) 6, and interferon gene (IFNG)) and canonical signaling pathways (such as the complement system, antigen presentation, macropinocytosis signaling, nuclear factor-kappa B (NF-κB) signaling, and IL-17 signaling) was responsible for the common comprehensive mechanism of PS and RA. Our findings provide a better understanding of the pathogenesis of PS and RA, suggesting potential strategies for treating and preventing both diseases. This study may also provide a new paradigm for illuminating the common pathogenesis of different diseases.

IL-6 promotes M2 macrophage polarization by modulating purinergic signaling and regulates the lethal release of nitric oxide during Trypanosoma cruzi infection

The production of nitric oxide (NO) is a key defense mechanism against intracellular pathogens but it must be tightly controlled in order to avoid excessive detrimental oxidative stress. In this study we described a novel mechanism through which interleukin (IL)-6 mediates the regulation of NO release induced in response to Trypanosoma cruzi infection. Using a murine model of Chagas disease, we found that, in contrast to C57BL/6 wild type (WT) mice, IL-6-deficient (IL6KO) mice exhibited a dramatic increase in plasma NO levels concomitant with a significantly higher amount of circulating IL-1β and inflammatory monocytes. Studies on mouse macrophages and human monocytes, revealed that IL-6 decreased LPS-induced NO production but this effect was abrogated in the presence of anti-IL-1β and in macrophages deficient in the NLRP3 inflammasome. In accordance, while infected WT myocardium exhibited an early shift from microbicidal/M1 to anti-inflammatory/M2 macrophage phenotype, IL6KO cardiac tissue never displayed a dominant M2 macrophage profile that correlated with decreased expression of ATP metabolic machinery and a lower cardiac parasite burden. The deleterious effects of high NO production-induced oxidative stress were evidenced by enhanced cardiac malondialdehyde levels, myocardial cell death and mortality. The survival rate was improved by the treatment of IL-6-deficient mice with a NO production-specific inhibitor. Our data revealed that IL-6 regulates the excessive release of NO through IL-1β inhibition and determines the establishment of an M2 macrophage profile within infected heart tissue.

Somatostatin receptor targeted liposomes with Diacerein inhibit IL-6 for breast cancer therapy

Selective targeting to the tumor niche remains a major challenge in successful cancer therapy. Somatostatin receptor 2 (SSTR2) is overexpressed in breast cancer cells thus making this receptor an attractive target for selective guidance of ligand-conjugated drug liposomes to the tumor site. In this study, a synthetic somatostatin analogue (SST) was used as SSTR2 targeting agent and Diacerein was employed as therapeutic molecule. Diacerein loaded liposomes (DNL) were prepared and they were further decorated with the synthetic and stable analogue of somatostatin (SST-DNL). Fabricated liposomes were nano-size in range and biocompatible. SST-DNL displayed significantly better anti-tumor efficacy as compared to free Diacerein (DN) and DNL in breast cancer models. Enhanced apoptosis in breast cancer cells was detected in SST-DNL treated groups as monitored by cell cycle analysis and changes in expression level of apoptotic/anti-apoptotic proteins Bcl-2, Bax, cleaved Caspase 3 and PARP. SST-DNL more effectively inhibited the oncogenic IL-6/IL-6R/STAT3/MAPK/Akt signalling pathways as compared to DN or DNL in cancer cells. In addition, SST-DNL effectively suppressed angiogenesis and cancer cell invasion. In vivo tumor growth in a MDA-MB-231 mouse xenograft model was significantly suppressed following SST-DNL treatment. In xenograft model, immunohistochemistry of Ki-67 and CD-31 indicated that SST-DNL improved the anti-proliferative and anti-angiogenic impacts of Diacerein. In vivo pharmacokinetic studies in rats showed enhanced circulation time in the DNL or SST-DNL treated groups as compared to free DN. Considering all of these findings, we conclude that SST-DNL provides a novel strategy with better efficacy for breast cancer therapy.

Hall of Fame among Pro-inflammatory Cytokines: Interleukin-6 Gene and Its Transcriptional Regulation Mechanisms

Pro-inflammatory cytokines that are generated by immune system cells and mediate many kinds of immune responses are kinds of endogenous polypeptides. They are also the effectors of the autoimmune system. It is generally accepted that interleukin (IL)-4, IL-6, IL-9, IL-17, and tumor necrosis factor-α are pro-inflammatory cytokines; however, IL-6 becomes a protagonist among them since it predominately induces pro-inflammatory signaling and regulates massive cellular processes. It has been ascertained that IL-6 is associated with a large number of diseases with inflammatory background, such as anemia of chronic diseases, angiogenesis acute-phase response, bone metabolism, cartilage metabolism, and multiple cancers. Despite great progress in the relative field, the targeted regulation of IL-6 response for therapeutic benefits remains incompletely to be understood. Therefore, it is conceivable that understanding mechanisms of IL-6 from the perspective of gene regulation can better facilitate to determine the pathogenesis of the disease, providing more solid scientific basis for clinical treatment translation. In this review, we summarize the candidate genes that have been implicated in clinical target therapy from the perspective of gene transcription regulation.

The effects of polysaccharides from the root of Angelica sinensis on tumor growth and iron metabolism in H22-bearing mice

The crude polysaccharide was obtained from the root of Angelica sinensis (AS) to investigate its effect on tumor growth and iron metabolism in H22-bearing mice. In our study, we showed that Angelica sinensis polysaccharide (ASP) was mainly composed of arabinose, glucose and galactose in a molar ratio of 1:1:1.75, with a molecular weight of 80,900 Da and a sugar content of 88.0%. Animal experimental results revealed that three doses of ASP all had anti-tumor effects with inhibition ratios of 27.11%, 31.65% and 37.05%. With respect to iron metabolism, the mean levels of serum hepcidin, interleukin-6 (IL-6), ferritin, transferrin (Tf), transferrin receptor 1 (TfR1) and transferrin receptor 2 (TfR2) in H22-bearing mice were promoted, and serum iron concentration decreased significantly. After treatment with ASP, these iron-related indicators recovered in different degrees. The findings suggested that the anti-tumor activity of ASP may be affected by its regulation on iron metabolism in H22-bearing mice.

Interleukin-6 suppression reduces tumour self-seeding by circulating tumour cells in a human osteosarcoma nude mouse model

Tumour self-seeding by circulating tumour cells (CTCs) enhances tumour progression and recurrence. Previously, we demonstrated that tumour self-seeding by CTCs occurs in osteosarcoma and revealed that interleukin-6 (IL-6) may promote CTC attraction. Here, we investigated the underlying mechanisms of IL-6 in tumour self-seeding by CTCs. IL-6 suppression inhibited in vitro cell proliferation, migration, and invasion. In addition, rhIL-6 activated the Janus-activated kinase/signal transducers and activators of transcription 3 (JAK/STAT3) and mitogen-activated protein kinase/extracellular-signal regulated kinase1/2 (MAPK/ERK1/2) pathways in vitro. Both pathways increased cell proliferation, but only the JAK/STAT3 pathway promoted migration. Suppressing IL-6 inhibited in vivo tumour growth and metastasis. IL-6 suppression or JAK/STAT3 pathway inhibition reduced CTC seeding in primary tumours. Collectively, IL-6 promotes tumour self-seeding by CTCs in a nude mouse model. This finding may provide a novel strategy for future therapeutic interventions to prevent osteosarcoma progression and recurrence.

RAID3--An interleukin-6 receptor-binding aptamer with post-selective modification-resistant affinity

Aptamers are an emerging class of highly specific targeting ligands. They can be selected in vitro for a large variety of targets, ranging from small molecules to whole cells. Most aptamers selected are nucleic acid-based, allowing chemical synthesis and easy modification. Although their properties make them interesting drug candidates for a broad spectrum of applications and an interesting alternative to antibodies or fusion proteins, they are not yet broadly used. One major drawback of aptamers is their susceptibility to abundant serum nucleases, resulting in their fast degradation in biological fluids. Using modified nucleic acids has become a common strategy to overcome these disadvantages, greatly increasing their half-life under cell culture conditions or even in vivo. Whereas pre-selective modifications of the initial library for aptamer selection are relatively easy to obtain, post-selective modifications of already selected aptamers are still generally very labor-intensive and often compromise the aptamers ability to bind its target molecule. Here we report the selection, characterization and post-selective modification of a 34 nucleotide (nt) RNA aptamer for a non-dominant, novel target site (domain 3) of the interleukin-6 receptor (IL-6R). We performed structural analyses and investigated the affinity of the aptamer to the membrane-bound and soluble forms (sIL-6R) of the IL-6R. Further, we performed structural analyses of the aptamer in solution using small-angle X-ray scattering and determined its overall shape and oligomeric state. Post-selective exchange of all pyrimidines against their 2'-fluoro analogs increased the aptamers stability significantly without compromising its affinity for the target protein. The resulting modified aptamer could be shortened to its minimal binding motif without loss of affinity.

Increased Gustatory Response Score in Obesity and Association Levels with IL-6 and Leptin

Background. The aim of this study was to investigate the relationship between the circulating IL-6 and leptin levels with taste alteration in young obese patients. Methods. A retrospective case-control study was conducted in thirty obese patients and thirty age- and sex-matched healthy controls. Results. Circulating levels of IL-6 and leptin were significantly increased in obese patients than in controls. However, catalase and ORAC levels were significantly decreased in obese patients compared to controls. Additionally, obese participants had high scores for the detection of fats (gustatory response scores [GRS]; p < 0.001). Moreover, IL-6 and leptin were strongly associated with GRS alteration among patients with GRS 4 (resp., OR =17.5 [95% CI, 1.56–193.32; p = 0.007]; OR = 16 [95% CI, 1.69–151.11; p = 0.006]). For the Mantel-Haenszel common odds ratio estimate (MH OR), IL-6 and leptin were strongly associated with obesity, in patients with either GRS 4 or GRS > 4 (resp., MH OR = 8.77 [95% CI, 2.06–37.44; p = 0.003]; MH OR = 5.76 [95% CI, 1.64–20.24; p = 0.006]). Conclusions. In a low grade inflammation linked to obesity, taste alteration is associated with high levels of IL-6 and leptin.

Elevated interleukin-6 expression levels are associated with intervertebral disc degeneration

The present study aimed to investigate whether serum interleukin-6 (IL-6) expression levels were associated with the onset and progression of intervertebral disc degeneration (IDD). A comprehensive meta-analysis of the scientific literature from numerous electronic databases was performed, in order to obtain published studies associated with the topic of interest. Relevant case-control studies that had previously assessed a correlation between IL-6 expression levels and IDD were identified using predetermined inclusion and exclusion criteria. The STATA version 12.0 software was used for statistical analysis of the extracted data. A total of 112 studies were initially retrieved, with eight studies meeting the inclusion criteria. These contained a total of 392 subjects, of which 263 were patients with IDD and 129 were healthy controls. A meta-analysis of the eight studies demonstrated that serum IL-6 protein expression levels may be associated with IDD, and this was irrespective of IDD subtype (bulging, protrusion, or sequestration). Notably, serum expression levels of the IL-6 protein were upregulated in intervertebral disc (IVD) protrusion tissue, as compared with normal IVD tissue; thus suggesting that IL-6 may have an important role in the pathophysiological process of IDD.

IL-6 mediates the signal pathway of JAK-STAT3-VEGF-C promoting growth, invasion and lymphangiogenesis in gastric cancer

Gastric cancer shows the highest invasive and metastasis features, especially lymph metastasis, which is closely associated with poor prognosis of gastric cancer. Although there is evidence that interleukin-6 (IL-6) can promote gastric cancer progression, the underlying specific mechanisms and the mechanisms of gastric cancer lymphangiogenesis are largely unknown. In the present study, we explore whether IL-6 could promote the proliferation and invasion activity of gastric cancer cells, and whether IL-6 mediating VEGF-C production affected the lymphangiogenesis in gastric cancer cells. Our results revealed that IL-6 and its receptors (IL-6 and gp130) are broadly expressed in various gastric cancer cell lines including SGC-7901, MGC, MKN-28 and AGS. Exogenous IL-6 increased the ability of gastric cancer cell proliferation and invasion, which could be weakened by AG490. in addition, exogenous IL-6 promoted the VEGF-C production of gastric cancer cells and the lymphangiogenesis of HDLECs. As we expected, AG490 was able to reduce these effects. Western blot analysis showed that IL-6 increased JKA, STAT3, p-STAT3 and VEGF-C protein levels in the gastric cancer cells. However, the JKA, STAT3, p-STAT3 and VEGF-C protein expression levels were inhibited by AG490. Our data suggested that IL-6 mediates the singnal pathway of JAK-STAT3-VEGF-C promoting the growth, invasion and lymphangiogenesis in gastric cancer. Thus, IL-6 and its related signal pathways may be a promising target for treatment of gastric cancer growth and lymphangiogenesis.

Diacerein-mediated inhibition of IL-6/IL-6R signaling induces apoptotic effects on breast cancer

Interleukin-6 (IL-6) signaling network has been implicated in oncogenic transformations making it attractive target for the discovery of novel cancer therapeutics. In this study, potent antiproliferative and apoptotic effect of diacerein were observed against breast cancer. In vitro apoptosis was induced by this drug in breast cancer cells as verified by increased sub-G1 population, LIVE/DEAD assay, cell cytotoxicity and presence of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, as well as downregulation of antiapoptotic proteins Bcl-2 and Bcl-xL and upregulation of apoptotic protein Bax. In addition, apoptosis induction was found to be caspase dependent. Further molecular investigations indicated that diacerein instigated apoptosis was associated with inhibition of IL-6/IL-6R autocrine signaling axis. Suppression of STAT3, MAPK and Akt pathways were also observed as a consequence of diacerein-mediated upstream inhibition of IL-6/IL-6R. Fluorescence study and western blot analysis revealed cytosolic accumulation of STAT3 in diacerein-treated cells. The docking study showed diacerein/IL-6R interaction that was further validated by competitive binding assay and isothermal titration calorimetry. Most interestingly, it was found that diacerein considerably suppressed tumor growth in MDA-MB-231 xenograft model. The in vivo antitumor effect was correlated with decreased proliferation (Ki-67), increased apoptosis (TUNEL) and inhibition of IL-6/IL-6R-mediated STAT3, MAPK and Akt pathway in tumor remnants. Taken together, diacerein offered a novel blueprint for cancer therapy by hampering IL-6/IL-6R/STAT3/MAPK/Akt network.

Intracellular Dynamics and Fate of a Humanized Anti-Interleukin-6 Receptor Monoclonal Antibody, Tocilizumab

Tocilizumab (TCZ), a humanized anti-interleukin-6 (IL-6) receptor (IL-6R) monoclonal antibody, abrogates signal transducer protein gp130-mediated IL-6 signaling by competitively inhibiting the binding of IL-6 to the receptor, and shows clinical efficacy in autoimmune and inflammatory diseases. Despite accumulating evidence for therapeutic efficacy, the behavior and fate of TCZ at the cellular level remain largely unknown. To address this, we evaluated the endocytosis and intracellular trafficking of IL-6R in HeLa cells. The results of our study provide evidence that IL-6R is constitutively internalized from the cell surface by ligand or TCZ binding and the expression of gp130 in an independent manner and is targeted via endosomes without being significantly directed to the recycling pathway to, and degraded in, lysosomes. Furthermore, the cytoplasmic tail of IL-6R is required for constitutive endocytosis of the receptor, which is mediated by the clathrin and AP-2 complex. We further demonstrate that FcRn, whose function is to regulate the serum persistence of IgG, is confined primarily to early/recycling endosomes and rapidly transits between these compartments and late endosomes/lysosomes without being degraded. Importantly, the expression of FcRn induces the segregation of TCZ from IL-6R, resulting in extensive colocalization of TCZ and FcRn in IL-6R-depleted endosomal compartments. Collectively, our results suggest that FcRn can accelerate the retrieval of the internalized TCZ, not only from endosomes but also from lysosomes. Our findings provide new insight into the mechanism by which the antibody internalized into cells is rescued from lysosomal degradation and into how its serum levels are maintained.

Anti-interleukin-6 therapy through application of a monogenic protein inhibitor via gene delivery

Anti-cytokine therapies have substantially improved the treatment of inflammatory and autoimmune diseases. Cytokine-targeting drugs are usually biologics such as antibodies or other engineered proteins. Production of biologics, however, is complex and intricate and therefore expensive which might limit therapeutic application. To overcome this limitation we developed a strategy that involves the design of an optimized, monogenic cytokine inhibitor and the protein producing capacity of the host. Here, we engineered and characterized a receptor fusion protein, mIL-6-RFP-Fc, for the inhibition of interleukin-6 (IL-6), a well-established target in anti-cytokine therapy. Upon application in mice mIL-6-RFP-Fc inhibited IL-6-induced activation of the transcription factor STAT3 and ERK1/2 kinases in liver and kidney. mIL-6-RFP-Fc is encoded by a single gene and therefore most relevant for gene transfer approaches. Gene transfer through hydrodynamic plasmid delivery in mice resulted in hepatic production and secretion of mIL-6-RFP-Fc into the blood in considerable amounts, blocked hepatic acute phase protein synthesis and improved kidney function in an ischemia and reperfusion injury model. Our study establishes receptor fusion proteins as promising agents in anti-cytokine therapies through gene therapeutic approaches for future targeted and cost-effective treatments. The strategy described here is applicable for many cytokines involved in inflammatory and other diseases.

Targeting interleukin-6 for noninfectious uveitis

Interleukin-6 (IL-6) is a pleiotropic cytokine implicated in the pathogenesis of many immune-mediated disorders including several types of non-infectious uveitis. These uveitic conditions include Vogt-Koyanagi-Harada syndrome, uveitis associated with Behçet disease, and sarcoidosis. This review summarizes the role of IL-6 in immunity, highlighting its effect on Th17, Th1, and plasmablast differentiation. It reviews the downstream mediators activated in the process of IL-6 binding to its receptor complex. This review also summarizes the biologics targeting either IL-6 or the IL-6 receptor, including tocilizumab, sarilumab, sirukumab, olokizumab, clazakizumab, and siltuximab. The target, dosage, potential side effects, and potential uses of these biologics are summarized in this article based on the existing literature. In summary, anti-IL-6 therapy for non-infectious uveitis shows promise in terms of efficacy and side effect profile.

Interleukin-6 and interleukin-10 as acute kidney injury biomarkers in pediatric cardiac surgery

BACKGROUND

Children undergoing cardiac surgery may exhibit a pronounced inflammatory response to cardiopulmonary bypass (CPB). Inflammation is recognized as an important pathophysiologic process leading to acute kidney injury (AKI). The aim of this study was to evaluate the association of the inflammatory cytokines interleukin (IL)-6 and IL-10 with AKI and other adverse outcomes in children after CPB surgery.

METHODS

This is a sub-study of the Translational Research Investigating Biomarker Endpoints in AKI (TRIBE-AKI) cohort, including 106 children ranging in age from 1 month to 18 years undergoing CPB. Plasma IL-6 and IL-10 concentrations were measured preoperatively and postoperatively [day 1 (within 6 h after surgery) and day 3].

RESULTS

Stage 2/3 AKI, defined by at least a doubling of the baseline serum creatinine concentration or dialysis, was diagnosed in 24 (23%) patients. The preoperative IL-6 concentration was significantly higher in patients with stage 2/3 AKI [median 2.6 pg/mL, interquartile range (IQR) 2.6 0.6-4.9 pg/mL] than in those without stage 2/3 AKI (median 0.6 pg/mL, IQR 0.6-2.2 pg/mL) (p = 0.03). After adjustment for clinical and demographic variables, the highest preoperative IL-6 tertile was associated with a sixfold increased risk for stage 2/3 AKI compared with the lowest tertile (adjusted odds ratio 6.41, 95 % confidence interval 1.16-35.35). IL-6 and IL-10 levels increased significantly after surgery, peaking postoperatively on day 1. First postoperative IL-6 and IL-10 measurements did not significantly differ between patients with stage 2/3 AKI and those without stage 2/3 AKI. The elevated IL-6 level on day 3 was associated with longer hospital stay (p = 0.0001).

CONCLUSIONS

Preoperative plasma IL-6 concentration is associated with the development of stage 2/3 AKI and may be prognostic of resource utilization.

Bidirectional role of IL-6 signal in pathogenesis of lung fibrosis

Background

Various signals are known to participate in the pathogenesis of lung fibrosis. Our aim was to determine which signal is predominantly mobilized in the early inflammatory phase and thereafter modulates the development of lung fibrosis.

Methods

Mice received a single dose of 3 mg/kg body weight of bleomycin (BLM) and were sacrificed at designated days post-instillation (dpi). Lung homogenates and sections from mice in the early inflammatory phase were subjected to phospho-protein array analysis and immunofluorescence studies, respectively. Bronchoalveolar lavage fluid (BALF) from mice was subjected to an enzyme-linked immunosorbent assay (EIA) for interleukin (IL)-6 and evaluation of infiltrated cell populations. The effects of endogenous and exogenous IL-6 on the BLM-induced apoptotic signal in A549 cells and type 2 pneumocytes were elucidated. In addition, the effect of IL-6-neutralizing antibody on BLM-induced lung injury was evaluated.

Results

Phospho-protein array revealed that BLM induced phosphorylation of molecules downstream of the IL-6 receptor such as Stat3 and Akt in the lung at 3 dpi. At 3 dpi, immunofluorescence studies showed that signals of phospho-Stat3 and -Akt were localized in type 2 pneumocytes, and that BLM-induced IL-6-like immunoreactivity was predominantly observed in type 2 pneumocytes. Activation of caspases in BLM-treated A549 cells and type 2 pneumocytes was augmented by application of IL-6-neutralizing antibody, a PI3K inhibitor or a Stat3 inhibitor. EIA revealed that BLM-induced IL-6 in BALF was biphasic, with the first increase from 0.5 to 3 dpi followed by the second increase from 8 to 10 dpi. Blockade of the first increase of IL-6 by IL-6-neutralizing antibody enhanced apoptosis of type 2 pneumocytes and neutrophilic infiltration and markedly accelerated fibrosis in the lung. In contrast, blockade of the second increase of IL-6 by IL-6-neutralizing antibody ameliorated lung fibrosis.

Conclusions

The present study demonstrated that IL-6 could play a bidirectional role in the pathogenesis of lung fibrosis. In particular, upregulation of IL-6 at the early inflammatory stage of BLM-injured lung has antifibrotic activity through regulating the cell fate of type 2 pneumocytes in an autocrine/paracrine manner.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0261-z) contains supplementary material, which is available to authorized users.

Analysis of the intricate relationship between chronic inflammation and cancer

Deregulated inflammatory response plays a pivotal role in the initiation, development and progression of tumours. Potential molecular mechanism(s) that drive the establishment of an inflammatory-tumour microenvironment is not entirely understood owing to the complex cross-talk between pro-inflammatory and tumorigenic mediators such as cytokines, chemokines, oncogenes, enzymes, transcription factors and immune cells. These molecular mediators are critical linchpins between inflammation and cancer, and their activation and/or deactivation are influenced by both extrinsic (i.e. environmental and lifestyle) and intrinsic (i.e. hereditary) factors. At present, the research pertaining to inflammation-associated cancers is accumulating at an exponential rate. Interest stems from hope that new therapeutic strategies against molecular mediators can be identified to assist in cancer treatment and patient management. The present review outlines the various molecular and cellular inflammatory mediators responsible for tumour initiation, progression and development, and discusses the critical role of chronic inflammation in tumorigenesis.

Inhibition of the interleukin-6 signaling pathway: a strategy to induce immune tolerance

Interleukin-6 (IL-6) is a proinflammatory cytokine that is multifunctional, with multifaceted effects. IL-6 signaling plays a vital role in the control of the differentiation and activation of T lymphocytes by inducing different pathways. In particular, IL-6 controls the balance between Th17 cells and regulatory T (Treg) cells. An imbalance between Treg and Th17 cells is thought to play a pathological role in various immune-mediated diseases. Deregulated IL-6 production and signaling are associated with immune tolerance. Therefore, methods of inhibiting IL-6 production, receptors, and signaling pathways are strategies that are currently being widely pursued to develop novel therapies that induce immune tolerance. This survey aims to provide an updated account of why IL-6 inhibitors are becoming a vital class of drugs that are potentially useful for inducing immune tolerance as a treatment for autoimmune diseases and transplant rejection. In addition, we discuss the effect of targeting IL-6 in recent experimental and clinical studies on autoimmune diseases and transplant rejection.

Expression of interleukin-6 is associated with epithelial-mesenchymal transition and survival rates in gallbladder cancer

The present study aimed to investigate the expression of interleukin‑6 (IL‑6) in gallbladder cancer (GBC) tissues and its correlation with survival rate. The association between IL‑6 and epithelial‑mesenchymal transition (EMT)‑associated markers was also examined. Using immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT‑qPCR) and western blot analysis, the protein and mRNA expression levels of IL‑6, Twist, E‑cadherin and Vimentin in 20 GBC tissues were analyzed. The IL‑6, Twist and Vimentin proteins were overexpressed in 40, 20 and 70% of the human GBC samples, respectively. The protein expression of E‑cadherin was higher in only 5% of the GBC samples. These differences were significant (P<0.05). Western blot analysis also revealed overexpression of IL‑6, Twist and Vimentin and underexpression of E‑cadherin in the GBC samples with poor differentiation, local invasion and a higher tumor‑node‑metastasis (TNM) stage (P<0.05). Higher mRNA expression levels of IL‑6, Twist and Vimentin and a reduced expression level of E‑cadherin were also demonstrated in the GBC tissues (P<0.05). The degree of differentiation, local invasion, lymph node metastasis and clinical stage were significantly associated with the mRNA expression levels of IL‑6, Twist and E‑cadherin. The increased expression levels of IL‑6 and Twist and the reduced expression of E‑cadherin correlated with shorter median survival rates (P<0.05). Line regression results revealed correlation among the mRNA expression levels of IL‑6, Twist, E‑cadherin and Vimentin. To the best of our knowledge, the present study is the first to demonstrate that IL‑6 is associated with EMT‑associated markers, tumor differentiation, local invasion, TNM stage and survival rates in GBC.

Influences of laparoscopic-assisted gastrectomy and open gastrectomy on serum interleukin-6 levels in patients with gastric cancer among Asian populations: a systematic review

BACKGROUND

To compare the effects of laparoscopic-assisted gastrectomy (LAG) and open gastrectomy (OG) on serum interleukin-6 (IL-6) levels in gastric cancer (GC) patients from Asia.

METHODS

The following scientific literature databases were searched for relevant clinical studies: PubMed, EBSCO, Ovid, Wiley, Web of Science, Cochrane library, EMBASE, WANFANG and VIP databases. The studies retrieved from database searches were screened based on stringent inclusion and exclusion criteria to select high quality cohort studies for the present meta-analysis. The data extracted from final selected studies were analyzed using STATA 12.0 software.

RESULTS

A total of 54 studies were initially retrieved from database searches, and 11 clinical cohort studies were eventually enrolled in this meta-analysis. The 11 selected studies contained a combined total of 767 GC patients (427 patients in LAG group and 340 patients in OG group). Meta-analysis results demonstrated that postoperative serum IL-6 levels in GC patients in LAG group was significantly lower than the OG group (SMD = -2.16, 95% CI = -3.19 ~ -1.14, P < 0.001). The difference in serum IL-6 levels between the preoperative and postoperative GC patients was significantly lower in the LAG group compared to the difference found in the OG group (SMD = -3.44, 95% CI = -4.87 ~ -2.01, P < 0.001). Subgroup analysis based on country showed that, in both Chinese and Japanese GC patients, the postoperative increase in serum IL-6 levels in LAG group were significantly lower than the increase observed in the OG group (all P < 0.05). In Korean GC patients, the postoperative increase in serum IL-6 levels was not significantly different between the LAG group and OG group (all P > 0.05).

CONCLUSION

Our results provide strong evidence that LAG is associated with significantly lower serum IL-6 levels, compared to OG. Thus, LAG carries markedly lower risk of adverse inflammatory reactions in GC patients among Asian population.

Effects of subconjunctival tocilizumab versus bevacizumab in treatment of corneal neovascularization in rabbits

PURPOSE

The aim of this study was to compare the antiangiogenic effects of subconjunctival application of bevacizumab and tocilizumab on the regression of corneal neovascularization (NV) in rabbits.

METHODS

Corneal neovascularization was induced in 48 eyes of 24 rabbits. Seven days after suture placement, the rabbits were divided into 4 groups of 6 rabbits each and treated subconjunctivally with 0.1 mL balanced salt solution (group 1), 0.1 mL tocilizumab (0.25 mg per 0.1 mL and 2.5 mg per 0.1 mL, groups 2 and 3), or 0.1 mL bevacizumab (2.5 mg per 0.1 mL) (group 4). Digital photographs of the eyes were obtained and the surface areas of corneal neovascularization were measured on days 7 and 14 after subconjunctival injections. On days 7 and 14, 3 rabbits were randomly chosen and the eyes were extracted. Half of the corneal specimens were analyzed histopathologically, and the other half were used to measure the concentrations of vascular endothelial growth factor (VEGF) and IL-6 using a multiplex bead assay, and the levels were compared with those of the controls.

RESULTS

The surface areas of induced corneal neovascularization were significantly smaller in groups 3 and 4 (2.5 mg of tocilizumab and 2.5 mg of bevacizumab) compared with the control group on days 7 and 14 (P < 0.05). Group 2 did not show significant difference from the control group on days 7 and 14. There were no differences observed in the reduced neovascularization areas in groups 3 and 4 on days 7 and 14. The concentrations of VEGF in groups 3 and 4 were significantly lower than in the control group, and IL-6 mRNA levels were significantly lower in group 3 than in the other groups (P < 0.001) on days 7 and 14. Immunohistochemical analysis confirmed the reduced expression of VEGF in all 3 experimental groups compared with the control group.

CONCLUSIONS

An antiangiogenic effect was observed after subconjunctival injection of 2.5 mg tocilizumab to an extent similar to that seen with 2.5 mg bevacizumab, which indicates that subconjunctival application of tocilizumab is effective for the inhibition of corneal neovascularization.

Aberrantly expressed Fra-1 by IL-6/STAT3 transactivation promotes colorectal cancer aggressiveness through epithelial-mesenchymal transition

The pro-inflammatory cytokine interleukin-6 (IL-6) in tumor microenvironment has been suggested to promote development and progression of colorectal cancer (CRC). However, the underlying molecular mechanisms remain elusive. In this study, we demonstrate that fos-related antigen-1 (Fra-1) plays a critical role in IL-6 induced CRC aggressiveness and epithelial-mesenchymal transition (EMT). In CRC cell lines, the expression of Fra-1 gene was found significantly upregulated during IL-6-driven EMT process. The Fra-1 induction occurred at transcriptional level in a manner dependent on signal transducer and activator of transcription 3 (STAT3), during which both phosphorylated and acetylated post-translational modifications were required for STAT3 activation to directly bind to the Fra-1 promoter. Importantly, RNA interference-based attenuation of either STAT3 or Fra-1 prevented IL-6-induced EMT, cell migration and invasion, whereas ectopic expression of Fra-1 markedly reversed the STAT3-knockdown effect and enhanced CRC cell aggressiveness by regulating the expression of EMT-promoting factors (ZEB1, Snail, Slug, MMP-2 and MMP-9). Furthermore, Fra-1 levels were positively correlated with the local invasion depth as well as lymph node and liver metastasis in a total of 229 CRC patients. Intense immunohistochemical staining of Fra-1 was observed at the tumor marginal area adjacent to inflammatory cells and in parallel with IL-6 secretion and STAT3 activation in CRC tissues. Together, this study proposes the existence of an aberrant IL-6/STAT3/Fra-1 signaling axis leading to CRC aggressiveness through EMT induction, which suggests novel therapeutic opportunities for the malignant disease.

Inflammation-induced phenoconversion of polymorphic drug metabolizing enzymes: hypothesis with implications for personalized medicine

Phenoconversion transiently converts genotypic extensive metabolizers (EMs) into phenotypic poor metabolizers (PMs) of drugs, potentially with corresponding changes in clinical response. This phenomenon, typically resulting from coadministration of medications that inhibit certain drug metabolizing enzymes (DMEs), is especially well documented for enzymes of the cytochrome P450 family. Nonclinical evidence gathered over the last two decades also strongly implicates elevated levels of some proinflammatory cytokines, released during inflammation, in down-regulation of drug metabolism, especially by certain DMEs of the P450 family, thereby potentially causing transient phenoconversion. Clinically, phenoconversion of NAT2, CYP2C19, and CYP2D6 has been documented in inflammatory conditions associated with elevated cytokines, such as human immunodeficiency virus infection, cancer, and liver disease. The potential of other inflammatory conditions to cause phenoconversion has not been studied but experimental and anecdotal clinical evidence supports infection-induced down-regulation of CYP1A2, CYP3A4, and CYP2C9 as well. Collectively, the evidence supports a hypothesis that certain inflammatory conditions associated with elevated proinflammatory cytokines may cause phenoconversion of certain DMEs. Since inflammatory conditions associated with elevated levels of proinflammatory cytokines are highly prevalent, phenoconversion of genotypic EM patients into transient phenotypic PMs may be more frequent than appreciated. Since drug pharmacokinetics, and therefore the clinical response, is influenced by DME phenotype rather than genotype per se, phenoconversion (whatever its cause) can have a significant impact on the analysis and interpretation of genotype-focused clinical outcome association studies. There is a risk that focusing on genotype alone may miss important associations between clinical outcomes and DME phenotypes, thus compromising future prospects of personalized medicine.

Gene of the month: Interleukin 6 (IL-6)

The Interleukin 6 (IL-6) gene encodes the classic proinflammatory cytokine IL-6. It is also known as interferon-β2 (IFN-β2), B cell stimulatory factor-2 and hybridoma/plasmacytoma growth factor. IL-6 is a multifunctional cytokine with a central role in many physiological inflammatory and immunological processes. Due to its major role in initiation as well as resolving inflammation, deregulation of IL-6 is a mainstay of chronic inflammatory and autoimmune diseases. Additionally, IL-6 has been shown to be implicated in pathogenesis of many human malignancies. Thus, a better understanding of IL-6 and its role in various pathological conditions could enable the development of strategies to use it as a therapeutic target. This short review focuses on the structure, regulation and biological activities of IL-6. In addition we discuss the role of IL-6 in diseases with inflammatory background and cancer and also the therapeutic applications of anti-IL-6 agents.

IL-6 as a druggable target in psoriasis: focus on pustular variants

Psoriasis vulgaris (PV) is a cutaneous inflammatory disorder stemming from abnormal, persistent activation of the interleukin- (IL-)23/Th17 axis. Pustular psoriasis (PP) is a clinicopathological variant of psoriasis, histopathologically defined by the predominance of intraepidermal collections of neutrophils. Although PP pathogenesis is thought to largely follow that of (PV), recent evidences point to a more central role for IL-1, IL-36, and IL-6 in the development of PP. We review the role of IL-6 in the pathogenesis of PV and PP, focusing on its cross-talk with cytokines of the IL-23/Th17 axis. Clinical inhibitors of IL-6 signaling, including tocilizumab, have shown significant effectiveness in the treatment of several inflammatory rheumatic diseases, including rheumatoid arthritis and juvenile idiopathic arthritis; accordingly, anti-IL-6 agents may potentially represent future promising therapies for the treatment of PP.

The determinants of poor respiratory health status in adults living with human immunodeficiency virus infection

The increased longevity afforded by combination antiretroviral therapy in developed countries has led to an increased concern regarding senescence-related diseases in patients with human immunodeficiency virus (HIV) infection. Previous epidemiologic analyses have demonstrated an increased risk of chronic obstructive pulmonary disease, as well as a significant burden of respiratory symptoms in HIV-infected patients. We performed the St. George's Respiratory Questionnaire (SGRQ) in 199 HIV-positive men, and determined the predominant factors contributing to poor respiratory-related health status. In univariate analyses, worse SGRQ scores were associated with respiratory-related variables such as greater smoking pack-year history (p=0.028), lower forced expiratory volume in 1 second (FEV1) (p<0.001), and worse emphysema severity as quantified by computed tomographic imaging (p=0.017). In addition, HIV-specific variables, such as a history of plasma viral load >100,000 copies/mL (p=0.043), lower nadir CD4 cell count (p=0.040), and current CD4 cell count ≤350 cells/μL (p=0.005), as well as elevated levels of inflammatory markers, specifically plasma interleukin (IL)-6 (p=0.002) and alpha-1 antitrypsin (p=0.005) were also associated with worse SGRQ scores. In a multiple regression model, FEV1, current CD4 count ≤350 cells/μL, and IL-6 levels remained significant contributors to reduced respiratory-related health status. HIV disease activity as measured by HIV-related immunosuppression in conjunction with the triggering of key inflammatory pathways may be important determinants of worse respiratory health status among HIV-infected individuals. Limitations of this analysis include the absence of available echocardiograms, diffusion capacity and lung volume testing, and an all-male cohort due to the demographics of the clinic population.

Interleukin-6 promotes the migration and invasion of nasopharyngeal carcinoma cell lines and upregulates the expression of MMP-2 and MMP-9

Nasopharyngeal carcinoma (NPC) shows the highest invasive and metastatic features among head and neck cancers. Distant metastasis remains the predominant mode of treatment failure in NPC patients. The role of interleukin-6 (IL-6) in NPC progression is not fully understood. In this study, we explored whether IL-6 could promote the migration and invasion activity of NPC cell lines, as well as whether the effect of IL-6 on cell migration and invasion is mediated through regulating the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. Our results revealed that IL-6 and its receptors are broadly expressed in various NPC cell lines including HNE1, HONE1, CNE1, CNE1-LMP1 and 5-8F. Exogenous IL-6 enhanced cell proliferation slightly, but promoted cell migration and invasion significantly in both HNE1 and CNE1-LMP1 cell lines. In addition, an elevation in the expression of MMP-2 and MMP-9 could be induced by IL-6 stimulation. On the contrary, combining treatment with monoclonal anti-human IL-6R antibody (anti-IL-6R mAb) resulted in decreased proliferation, migration and invasion capabilities of NPC cells. Anti-IL-6R mAb also inhibited the expression of MMP-2 and MMP-9 in IL-6-stimulated HNE1 and CNE1-LMP1 cells. In summary, our data suggested that IL-6 mainly promotes the cell migration and invasion of NPC cells. The effect of IL-6 on cell migration and invasion may be mediated through regulation of the expression of MMP-2 and MMP-9. Thus, IL-6 or its related signaling pathways may be a promising target for preventing and inhibiting NPC metastasis.

Crystal structure of interleukin-6 in complex with a modified nucleic acid ligand

IL-6 is a secreted cytokine that functions through binding two cell surface receptors, IL-6Rα and gp130. Because of its involvement in the progression of several chronic inflammatory diseases, IL-6 is a target of pharmacologic interest. We have recently identified a novel class of ligands called SOMAmers (S low Off-rate Modified Aptamers) that bind IL-6 and inhibit its biologic activity. SOMAmers exploit the chemical diversity of protein-like side chains assembled on flexible nucleic acid scaffolds, resulting in an expanded repertoire of intra- and intermolecular interactions not achievable with conventional aptamers. Here, we report the co-crystal structure of a high affinity SOMAmer (K_d = 0.20 nm) modified at the 5-position of deoxyuridine in a complex with IL-6. The SOMAmer, comprised of a G-quartet domain and a stem-loop domain, engages IL-6 in a clamp-like manner over an extended surface exhibiting close shape complementarity with the protein. The interface is characterized by substantial hydrophobic interactions overlapping the binding surfaces of the IL-6Rα and gp130 receptors. The G-quartet domain retains considerable binding activity as a disconnected autonomous fragment (K_d = 270 nm). A single substitution from our diversely modified nucleotide library leads to a 37-fold enhancement in binding affinity of the G-quartet fragment (K_d = 7.4 nm). The ability to probe ligand surfaces in this manner is a powerful tool in the development of new therapeutic reagents with improved pharmacologic properties. The SOMAmer·IL-6 structure also expands our understanding of the diverse structural motifs achievable with modified nucleic acid libraries and elucidates the nature with which these unique ligands interact with their protein targets.

Targeting interleukin-6 in inflammatory autoimmune diseases and cancers

Interleukin-6 (IL-6) is a pleiotropic cytokine with significant functions in the regulation of the immune system. As a potent pro-inflammatory cytokine, IL-6 plays a pivotal role in host defense against pathogens and acute stress. However, increased or deregulated expression of IL-6 significantly contributes to the pathogenesis of various human diseases. Numerous preclinical and clinical studies have revealed the pathological roles of the IL-6 pathway in inflammation, autoimmunity, and cancer. Based on the rich body of studies on biological activities of IL-6 and its pathological roles, therapeutic strategies targeting the IL-6 pathway are in development for cancers, inflammatory and autoimmune diseases. Several anti-IL-6/IL-6 receptor monoclonal antibodies developed for targeted therapy have demonstrated promising results in both preclinical studies and clinical trials. Tocilizumab, an anti-IL-6 receptor antibody, is effective in the treatment of various autoimmune and inflammatory conditions notably rheumatoid arthritis. It is the only IL-6 pathway targeting agent approved by the regulatory agencies for clinical use. Siltuximab, an anti-IL-6 antibody, has been shown to have potential benefits treating various human cancers either as a single agent or in combination with other chemotherapy drugs. Several other anti-IL-6-based therapies are also under clinical development for various diseases. IL-6 antagonism has been shown to be a potential therapy for these disorders refractory to conventional drugs. New strategies, such as combination of IL-6 blockade with inhibition of other signaling pathways, may further improve IL-6-targeted immunotherapy of human diseases.

Pseudomyxoma peritonei: inflammatory responses in the peritoneal microenvironment

BACKGROUND

Pseudomyxoma peritonei (PMP), a peritoneal mucinous neoplasm of appendiceal origin, is associated with inflammation and fibrosis, which is central to its biology. The significance of the microenvironment in PMP has not been well characterized.

METHODS

Immunoassays were used to measure cytokines and C-reactive protein (CRP). Forty-two cytokines were initially measured in 23 PMP ascites and 10 PMP peritoneal washings. On the basis of these results, matching serum and ascites samples were analyzed for ten relevant cytokines (n = 32) and CRP (n = 28). Immunohistochemistry was performed on formalin-fixed tissue sections. Statistical analysis was by Wilcoxon signed rank test, Mann-Whitney U-test, and bivariate analysis.

RESULTS

Serum CRP was elevated in PMP and correlated to CRP level in ascites. Interleukin (IL)-6, IL-8 (CXCL8), interferon gamma-induced protein 10 (IP-10), (CXCL10), monocyte chemotactic protein (MCP)-1 (CCL2), and macrophage inflammatory protein (MIP)-1α (CCL3) levels were grossly elevated in ascites but did not correlate with serum levels. Cytokines normally associated with infection or tissue injury (e.g., IL-1, IL-2, interferon gamma) were not elevated. Immunohistochemistry localized IL-6 to stroma, IP-10, and MCP-1 to tumor cells and IL-8 to adipose tissue. There were complex interactions among cytokines. IL-6, in particular, had many significant correlations in ascites. Serum IL-8, MIP-1β, and CRP were higher in PMP compared to controls.

CONCLUSIONS

The pattern of cytokines in PMP is distinct from infection- or injury-associated inflammation. The results support peritoneal synthesis for cytokines. CRP, IL-8, and MIP-1β are potential serum markers for PMP. IL-6 appears to play a central role in PMP biology. This study provides new details about PMP tumor biology and identifies possible therapeutic targets.

LPLUNC1 suppresses IL-6-induced nasopharyngeal carcinoma cell proliferation via inhibiting the Stat3 activation

Tumor-associated macrophage (TAM)-related chronic inflammation and interleukin-6 (IL-6) contribute to the progression of nasopharyngeal carcinoma (NPC). In this study, we characterized TAMs and IL-6 expression in 212 biopsied NPC and 119 non-tumor nasopharyngeal epithelium (NPE) tissues by tissue array. In comparison with that in the NPE tissues, more TAM infiltrates and a higher density of IL-6 expression were detected in NPC tissues, which were associated with the poor survival of NPC patients. In contrast, little or no LPLUNC1, a regulator of inflammation, expression was detected in NPC tissues, and the levels of LPLUNC1 expression in the NPC were associated negatively with the numbers of TAMs and the levels of IL-6 expression, but positively with the survival of NPC patients. Induction of LPLUNC1 overexpression in NPC cells mitigated lipopolysaccharide (LPS)-induced IL-6, IL-8, tumor necrosis factor-α and IL-1β expression or treatment of THP-1 macrophages with LPLUNC1 inhibited spontaneous and LPS-induced IL-6 expression in vitro. IL-6-promoted NPC cell proliferation in a dose- and time-dependent manner, accompanied by increasing cyclin D1 and Bcl-2 expression and the Stat3 activation, but inhibiting Bax and p21 expression. Induction of LPLUNC1 overexpression inhibited NPC cell proliferation, induced NPC cell arrest, promoted NPC cell apoptosis even after IL-6 stimulation and inhibited the growth of implanted NPC tumors in vivo, which were associated with decreasing cyclin D1 and Bcl-2 expression and the Janus kinase 2 (JAK2)/Stat3 activation, but enhancing Bax and p21 expression. These results suggest that LPLUNC1 can inhibit inflammation and NPC growth by downregulating the Stat3 pathway.

Minocycline suppresses interleukine-6, its receptor system and signaling pathways and impairs migration, invasion and adhesion capacity of ovarian cancer cells: in vitro and in vivo studies

Interleukin (IL)-6 has been shown to be a major contributing factor in growth and progression of ovarian cancer. The cytokine exerts pro-tumorigenic activity through activation of several signaling pathways in particular signal transducer and activator of transcription (STAT3) and extracellular signal-regulated kinase (ERK)1/2. Hence, targeting IL-6 is becoming increasingly attractive as a treatment option in ovarian cancer. Here, we investigated the effects of minocycline on IL-6 and its signaling pathways in ovarian cancer. In vitro, minocycline was found to significantly suppress both constitutive and IL-1β or 4-hydroxyestradiol (4-OH-E2)-stimulated IL-6 expression in human ovarian cancer cells; OVCAR-3, SKOV-3 and CAOV-3. Moreover, minocycline down-regulated two major components of IL-6 receptor system (IL-6Rα and gp130) and blocked the activation of STAT3 and ERK1/2 pathways leading to suppression of the downstream product MCL-1. In female nude mice bearing intraperitoneal OVCAR-3 tumors, acute administration (4 and 24 h) of minocycline (30 mg/kg) led to suppression of IL-6. Even single dose of minocycline was effective at significantly lowering plasma and tumor IL-6 levels. In line with this, tumoral expression of p-STAT3, p-ERK1/2 and MCL-1 were decreased in minocycline-treated mice. Evaluation of the functional implication of minocycline on metastatic activity revealed the capacity of minocycline to inhibit cellular migration, invasion and adhesion associated with down-regulation of matrix metalloproteinases (MMP)-2 and 9. Thus, the data suggest a potential role for minocycline in suppressing IL-6 expression and activity. These effects may prove to be an important attribute to the upcoming clinical trials of minocycline in ovarian cancer.