Disruption of inflammatory signals by cytokine-targeted therapies for inflammatory bowel diseases

Non-coding DNA in IBD: from sequence variation in DNA regulatory elements to novel therapeutic potential

Genome-wide association studies have identified over 200 loci associated with IBD. We and others have recently shown that, in addition to variants in protein-coding genes, the majority of the associated loci are related to DNA regulatory elements (DREs). These findings add a dimension to the already complex genetic background of IBD. In this review we summarise the existing evidence on the role of DREs in IBD. We discuss how epigenetic research can be used in candidate gene approaches that take non-coding variants into account and can help to pinpoint the essential pathways and cell types in the pathogenesis of IBD. Despite the increased level of genetic complexity, these findings can contribute to novel therapeutic options that target transcription factor binding and enhancer activity. Finally, we summarise the future directions and challenges of this emerging field.

Challenges in treating patients with inflammatory bowel disease and concurrent viral hepatitis infection

Inflammatory bowel diseases (IBD) require long-term administration of immunomodulatory treatments to maintain disease remission. Due to the high worldwide prevalence of hepatitis B (HBV) or C (HCV) virus infections, presence of concurrent hepatitis can be a relevant clinical issue to manage when treating IBD. Areas covered: The paper summarizes epidemiological data about IBD and HBV/HCV infection and reviews current knowledge about the natural history of HBV and HCV in the IBD setting, concentrating on risk of hepatitis reactivation during immunosuppressive treatment. Most updated recommendations for management of HBV and HCV infections in IBD patients are discussed. Expert commentary: The development of new drugs for IBD with different molecular targets and the availability of potent and efficacious antiviral drugs for HBV and HCV will simplify management of hepatitis infection in IBD patients in the near future.

Inhibition of G-Protein βγ Signaling Decreases Levels of Messenger RNAs Encoding Proinflammatory Cytokines in T Cell Receptor-Stimulated CD4(+) T Helper Cells

Background: Inhibition of G-protein βγ (Gβγ) signaling was found previously to enhance T cell receptor (TCR)-stimulated increases in interleukin 2 (IL-2) mRNA in CD4⁺ T helper cells, suggesting that Gβγ might be a useful drug target for treating autoimmune diseases, as low dose IL-2 therapy can suppress autoimmune responses. Because IL-2 may counteract autoimmunity in part by shifting CD4⁺ T helper cells away from the Type 1 T helper cell (TH1) and TH17 subtypes towards the TH2 subtype, the purpose of this study was to determine if blocking Gβγ signaling affected the balance of TH1, TH17, and TH2 cytokine mRNAs produced by CD4⁺ T helper cells.

Methods: Gallein, a small molecule inhibitor of Gβγ, and siRNA-mediated silencing of the G-protein β₁ subunit (Gβ₁) were used to test the effect of blocking Gβγ on mRNA levels of cytokines in primary human TCR-stimulated CD4⁺ T helper cells.

Results: Gallein and Gβ₁ siRNA decreased interferon-γ (IFN-γ) and IL-17A mRNA levels in TCR-stimulated CD4⁺ T cells grown under TH1-promoting conditions. Inhibiting Gβγ also decreased mRNA levels of STAT4, which plays a positive role in TH1 differentiation and IL-17A production. Moreover, mRNA levels of the STAT4-regulated TH1-associated proteins, IL-18 receptor β chain (IL-18Rβ), mitogen-activated protein kinase kinase kinase 8 (MAP3K8), lymphocyte activation gene 3 (LAG-3), natural killer cell group 7 sequence (NKG7), and oncostatin M (OSM) were also decreased upon Gβγ inhibition. Gallein also increased IL-4, IL-5, IL-9, and IL-13 mRNA levels in TCR-stimulated memory CD4⁺ T cells grown in TH2-promoting conditions.

Conclusions: Inhibiting Gβγ to produce these shifts in cytokine mRNA production might be beneficial for patients with autoimmune diseases such as rheumatoid arthritis (RA), Crohn’s disease (CD), psoriasis, multiple sclerosis (MS), and Hashimoto’s thyroiditis (HT), in which both IFN-γ and IL-17A are elevated.

Inhibition of the inflammatory cytokine tumor necrosis factor-alpha with etanercept provides protection against lethal H1N1 influenza infection in mice

INTRODUCTION

Factors implicated in influenza-mediated morbidity and mortality include robust cytokine production (cytokine storm), excessive inflammatory infiltrates, and virus-induced tissue destruction. Tumor necrosis factor-alpha (TNF-α) is an important pro-inflammatory cytokine present during influenza infection, but it is unclear whether direct inhibition of TNF-α can elicit protection against influenza infection.

METHODS

In this study, the commercially available TNF-α inhibitor etanercept was used to inhibit TNF-α induced by lethal A/FM/1/47 (H1N1) influenza virus infection of mice. The effects of TNF-α inhibition on mouse survival, pathologic changes, immune cell infiltration, inflammatory cytokine secretion, Toll-like receptor expression, and activation of the NF-κB (nuclear factor kappa B) signaling pathway were evaluated.

RESULTS

The intranasal delivery of etanercept provided significant protection against mortality (30% of mice survived up to 14 days after infection) in mice treated with etanercept. In contrast, no survivors were found beyond 6 days in mice treated with saline after lethal challenge with H1N1 influenza virus. It was observed that etanercept significantly reduced inflammatory cell infiltration (for example, macrophages and neutrophils), inflammatory cytokine secretion (for example, interleukin-6, TNF-α, and interferon gamma), and expression of Toll-like receptors (TLR-3, TLR-4, and TLR-7). Etanercept also downregulated and inhibited the cascade proteins of the NF-κB signaling pathway (for example, MyD88, TRIF, NF-κB, and p65), as well as enhanced host control of virus replication.

CONCLUSIONS

These findings indicate that etanercept, by blocking TNF-α, can significantly downregulate excessive inflammatory immune responses and provide protection against lethal influenza infection, making its use a novel strategy for controlling severe influenza-induced viral pneumonia.

NS6180, a new K(Ca) 3.1 channel inhibitor prevents T-cell activation and inflammation in a rat model of inflammatory bowel disease

BACKGROUND AND PURPOSE

The K(Ca) 3.1 channel is a potential target for therapy of immune disease. We identified a compound from a new chemical class of K(Ca) 3.1 inhibitors and assessed in vitro and in vivo inhibition of immune responses.

EXPERIMENTAL APPROACH

We characterized the benzothiazinone NS6180 (4-[[3-(trifluoromethyl)phenyl]methyl]-2H-1,4-benzothiazin-3(4H)-one) with respect to potency and molecular site of action on K(Ca) 3.1 channels, selectivity towards other targets, effects on T-cell activation as well as pharmacokinetics and inflammation control in colitis induced by 2,4-dinitrobenzene sulfonic acid, a rat model of inflammatory bowel disease (IBD).

KEY RESULTS

NS6180 inhibited cloned human K(Ca) 3.1 channels (IC(50) = 9 nM) via T250 and V275, the same amino acid residues conferring sensitivity to triarylmethanes such as like TRAM-34. NS6180 inhibited endogenously expressed K(Ca) 3.1 channels in human, mouse and rat erythrocytes, with similar potencies (15-20 nM). NS6180 suppressed rat and mouse splenocyte proliferation at submicrolar concentrations and potently inhibited IL-2 and IFN-γ production, while exerting smaller effects on IL-4 and TNF-α and no effect on IL-17 production. Antibody staining showed K(Ca) 3.1 channels in healthy colon and strong up-regulation in association with infiltrating immune cells after induction of colitis. Despite poor plasma exposure, NS6180 (3 and 10 mg·kg(-1) b.i.d.) dampened colon inflammation and improved body weight gain as effectively as the standard IBD drug sulfasalazine (300 mg·kg(-1) q.d.).

CONCLUSIONS AND IMPLICATIONS

NS6180 represents a novel class of K(Ca) 3.1 channel inhibitors which inhibited experimental colitis, suggesting K(Ca) 3.1 channels as targets for pharmacological control of intestinal inflammation.

Reduction of CD68+ macrophages and decreased IL-17 expression in intestinal mucosa of patients with inflammatory bowel disease strongly correlate with endoscopic response and mucosal healing following infliximab therapy

BACKGROUND

Antibodies against tumor necrosis factor represent an effective therapy for patients with inflammatory bowel disease. Despite their successful results, the exact mechanism by which infliximab suppresses intestinal inflammation is still a matter of debate. In this study, we used a translational approach to identify the key mechanisms associated with resolution of mucosal inflammation induced by infliximab.

METHODS

A total of 16 patients with active inflammatory bowel disease (9 with Crohn's disease and 7 with ulcerative colitis) and 16 controls were enrolled in the study. Patients received infliximab infusions at 0, 2, and 6 weeks. At enrollment and at week 6, patients underwent flexible sigmoidoscopy, and biopsies were taken from the sigmoid colon. RNA was extracted, and mucosal expression of 96 immune-related genes was evaluated by qRT-PCR and confirmed by immunofluorescence microscopy on tissue. Correlation between infliximab-induced gene expression modulation and endoscopic response to therapy was calculated. Lamina propria mononuclear cell apoptosis induced by infliximab was evaluated on tissue sections by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

RESULTS

We found that infliximab-induced downregulation of macrophage and Th17 pathway genes was significantly associated with both endoscopic response to the therapy and achievement of mucosal healing. Importantly, the observed reduction of lamina propria CD68 macrophages was associated with an increased rate of macrophage apoptosis.

CONCLUSIONS

The 2 mechanisms associated with infliximab-induced resolution of intestinal inflammation are the reduction of lamina propria infiltrating CD68 macrophages and the downregulation of interleukin 17A. Moreover, the data suggest that infliximab-induced macrophage apoptosis may represent a key mechanism for the therapeutic success of anti-tumor necrosis factor antibodies.

What's the next best cytokine target in IBD?

In the gut of patients with inflammatory bowel disease (IBD), immune and nonimmune cells produce large amounts of cytokines that drive the inflammatory process leading to the tissue damage. Cytokine blockers, such as anti-tumor necrosis factor alpha (TNF-α), have been used with some success in IBD. However, not all patients respond, and the therapeutic effects wane with time, demonstrating the need for more effective and long-lasting antiinflammatory strategies. A key question is whether neutralizing other proinflammatory cytokines such as interleukin (IL)-12, IL-21, IL-27, or IL-33 will lead to a better clinical response than with anti-TNF-α antibodies. Equally, we now know that IBD-related inflammation is marked by defective production/activity of antiinflammatory cytokines, and there are strategies to correct these defects. An alternative approach is to try to target individual therapies to individual patients, to improve clinical efficacy in subsets of patients, but this has proven difficult. Here we try to evaluate the potential of each of these choices.

Concordance of preclinical and clinical pharmacology and toxicology of monoclonal antibodies and fusion proteins: soluble targets

Monoclonal antibodies (mAbs) and fusion proteins directed towards soluble targets make an important contribution to the treatment of disease. The purpose of this review was to correlate the clinical and preclinical data on the 14 currently approved mAbs and fusion proteins targeted to soluble targets. The principal sources used to gather data were: the peer reviewed Literature; European Medicines Agency 'Scientific Discussions' and United States Food and Drug Administration 'Pharmacology/Toxicology Reviews' and package inserts (United States Prescribing Information). Data on the following approved biopharmaceuticals were included: adalimumab, anakinra, bevacizumab, canakinumab, certolizumab pegol, denosumab, eculizumab, etanercept, golimumab, infliximab, omalizumab, ranibizumab, rilonacept and ustekinumab. Some related biopharmaceuticals in late-stage development were also included for comparison. Good concordance with human pharmacodynamics was found for both non-human primates (NHPs) receiving the human biopharmaceutical and mice receiving rodent homologues (surrogates). In contrast, there was limited concordance for human adverse effects in genetically deficient mice, mice receiving surrogates or NHPs receiving the human pharmaceutical. In summary, the results of this survey show that although both mice and NHPs have good predictive value for human pharmacodynamics, neither species have good predictive value for human adverse effects. No evidence that NHPs have superior predictive value was found.