Targeting nanomedicines in the treatment of Crohn's disease: focus on certolizumab pegol (CDP870)

The role of inflammation in autoimmune disease: a therapeutic target

Autoimmune diseases (AIDs) are immune disorders whose incidence and prevalence are increasing year by year. AIDs are produced by the immune system's misidentification of self-antigens, seemingly caused by excessive immune function, but in fact they are the result of reduced accuracy due to the decline in immune system function, which cannot clearly identify foreign invaders and self-antigens, thus issuing false attacks, and eventually leading to disease. The occurrence of AIDs is often accompanied by the emergence of inflammation, and inflammatory mediators (inflammatory factors, inflammasomes) play an important role in the pathogenesis of AIDs, which mediate the immune process by affecting innate cells (such as macrophages) and adaptive cells (such as T and B cells), and ultimately promote the occurrence of autoimmune responses, so targeting inflammatory mediators/pathways is one of emerging the treatment strategies of AIDs. This review will briefly describe the role of inflammation in the pathogenesis of different AIDs, and give a rough introduction to inhibitors targeting inflammatory factors, hoping to have reference significance for subsequent treatment options for AIDs.

TNF-α Modulation of Intestinal Tight Junction Permeability Is Mediated by NIK/IKK-α Axis Activation of the Canonical NF-κB Pathway

Tumor necrosis factor (TNF)-α, a key mediator of intestinal inflammation, causes an increase in intestinal epithelial tight junction (TJ) permeability by activating myosin light chain kinase (MLCK; official name MYLK3) gene. However, the precise signaling cascades that mediate the TNF-α-induced activation of MLCK gene and increase in TJ permeability remain unclear. Our aims were to delineate the upstream signaling mechanisms that regulate the TNF-α modulation of intestinal TJ barrier function with the use of in vitro and in vivo intestinal epithelial model systems. TNF-α caused a rapid activation of both canonical and noncanonical NF-κB pathway. NF-κB-inducing kinase (NIK) and mitogen-activated protein kinase kinase-1 (MEKK-1) were activated in response to TNF-α. NIK mediated the TNF-α activation of inhibitory κB kinase (IKK)-α, and MEKK1 mediated the activation of IKK complex, including IKK-β. NIK/IKK-α axis regulated the activation of both NF-κB p50/p65 and RelB/p52 pathways. Surprisingly, the siRNA induced knockdown of NIK, but not MEKK-1, prevented the TNF-α activation of both NF-κB p50/p65 and RelB/p52 and the increase in intestinal TJ permeability. Moreover, NIK/IKK-α/NF-κB p50/p65 axis mediated the TNF-α-induced MLCK gene activation and the subsequent MLCK increase in intestinal TJ permeability. In conclusion, our data show that NIK/IKK-α/regulates the activation of NF-κB p50/p65 and plays an integral role in the TNF-α-induced activation of MLCK gene and increase in intestinal TJ permeability.

Comprehensive review: antitumor necrosis factor agents in inflammatory bowel disease and factors implicated in treatment response

Antitumor necrosis factor α (anti-TNF) agents have dramatically influenced management of refractory inflammatory bowel disease (IBD). However, not all patients respond to treatment and some lose response or become intolerant over time. Immunogenicity, a well established phenomenon with anti-TNF agents, may have important clinical implications in patients with IBD. A comprehensive review of available evidence demonstrating how drug concentrations, immunogenicity, and other factors influence outcomes with anti-TNF agents was performed. PubMed, EMBASE, Biosis, Dialog, and Conference Papers Index were searched from 1 January 1995 to 7 April 2012 to identify clinical trials in adult and pediatric patients with IBD treated with anti-TNF agents for Crohn's disease or ulcerative colitis. Data on serum drug levels and immunogenicity and their relationship with clinical efficacy and safety outcomes were extracted and examined. Serum infliximab concentrations correlated with clinical efficacy and treatment outcomes in patients with IBD; this relationship is less well characterized with adalimumab and certolizumab pegol concentrations. In multiple studies, the presence and level of antibodies to infliximab correlated with loss of clinical efficacy and increased risk of infusion reactions. The incidence and clinical impact of antibody formation with adalimumab or certolizumab in IBD is becoming evident as more data become available. Current, enzyme-linked immunosorbent assay based anti-TNF antibody assays are suboptimal in that results are often inconclusive and comparisons between agents cannot be made. Measurement of anti-TNF agent drug concentrations and assessment of immunogenicity has the potential to positively impact clinical decision making during anti-TNF therapy for IBD. As assays are optimized, it is expected that the clinical impact of these determinations will be better characterized.

TNF-α and the development of the neonatal immune system: implications for inhibitor use in pregnancy

Inflammatory bowel diseases, Crohn's disease, and ulcerative colitis have an unpredictable course during and after pregnancy (1). There is a great deal of interest in treating moderate to severe active inflammatory bowel disease with anti-tumor necrosis factor (anti-TNF) biologics in pregnant women (2). We lack definitive information about the effects of these agents on the development of the immune system of the human fetus and the newborn baby. Anti-TNF agents fall within US Food and Drug Administration's (FDA) category B regarding fetal risk, indicating that no adequate and well-controlled studies have been conducted in pregnant or nursing women. Here, we review animal studies (of both mice and nonhuman primates) that examine the role of TNF and its inhibitors in the normal development of the immune system.

Site-specific polysialylation of an antitumor single-chain Fv fragment

Protein pharmacokinetic modulation is becoming an important tool in the development of biotherapeutics. Proteins can be chemically or recombinantly modified to alter their half-lives and bioavailability to suit particular applications as well as improve side effect profiles. The most successful and clinically used approach to date is chemical conjugation with poly(ethylene glycol) polymers (PEGylation). Here, therapeutic protein half-life can be increased significantly while retaining biological function, reducing immunogenicity and cross-reaction. Naturally occurring alternatives to such synthetic polymers could have major advantages such as lower side effects due to biodegradability and metabolism. Polysialic acid (PSA) has been investigated as a pharmacokinetic modulatory biopolymer with many successful examples in preclinical and clinical development. Single-chain Fvs (scFvs) are a choice antibody format for human therapeutic antibody discovery. Because of their small size, they are rapidly eliminated from the circulation and often are rebuilt into larger proteins for drug development and a longer half-life. Here we show that chemical polysialylation can increase the half-life of an antiplacental alkaline (PLAP) and anticarcinoembryonic antigen (CEA) scFv (F1 and MFE-23, respectively) 3.4-4.9-fold, resulting in a 10.6-15.2-fold increase in blood exposure. Amine-directed coupling of the MFE-23 scFv reduced its immunoreactivity 20-fold which was resolved by site-specific polysialylation through an engineered C-terminal thiol residue. The site-specifically polysialylated MFE-23 scFv demonstrated up to 30-fold improved tumor uptake while displaying favorable tumor:normal tissue specificity. This suggests that engineering antibody fragments for site-specific polysialylation could be a useful approach to increase the half-life for a variety of therapeutic applications.

New strategy for the extension of the serum half-life of antibody fragments

Antibody fragments can recognize their cognate antigen with high affinity and can be produced at high yields, but generally display rapid blood clearance profiles. For pharmaceutical applications, the serum half-life of antibody fragments is often extended by chemical modification with polymers or by genetic fusion to albumin or albumin-binding polypeptides. Here, we report that the site-specific chemical modification of a C-terminal cysteine residue in scFv antibody fragments with a small organic molecule capable of high-affinity binding to serum albumin substantially extends serum half-life in rodents. The strategy was implemented using the antibody fragment F8, specific to the alternatively spliced EDA domain of fibronectin, a tumor-associated antigen. The unmodified and chemically modified scFv-F8 antibody fragments were studied by biodistribution analysis in tumor-bearing mice, exhibiting a dramatic increase in tumor uptake for the albumin-binding antibody derivative. The data presented in this paper indicate that the chemical modification of the antibody fragment with the 2-(3-maleimidopropanamido)-6-(4-(4-iodophenyl)butanamido)hexanoate albumin-binding moiety may represent a general strategy for the extension of the serum half-life of antibody fragments and for the improvement of their in vivo targeting performance.

Delivery strategies to target therapies to inflammatory tissue

BACKGROUND

Inflammation plays a key role in many chronic disease processes as well as an acute role in injury and wound healing. Various cell types are recruited from the bloodstream to the inflamed site through adhesion molecules, cytokines, chemokines and others.

OBJECTIVES

This review examines many drug-targeting strategies that make use of these molecules or signaling pathways, and seeks to describe certain commonalities irrespective of the disease process or agent to be delivered.

METHODS

A survey of the literature, primarily within the last year, was performed. Search words included 'drug targeting' and 'inflammation' and of those, the scope was refined to include those studies that specifically sought to modify or ameliorate an aspect of the inflammatory process in the treatment of a disease.

RESULTS/CONCLUSION

Inflammation plays a key role in many diseases, and many similar targets (such as adhesion molecules) are the focus of the treatment of those diseases.