(E)-2(R)-[1(S)-(Hydroxycarbamoyl)-4-phenyl-3-butenyl]-2'-isobutyl-2'-(methanesulfonyl)-4-methylvalerohydrazide (Ro 32-7315), a selective and orally active inhibitor of tumor necrosis factor-alpha convertase

Challenge model of TNFα turnover at varying LPS and drug provocations

A mechanism-based biomarker model of TNF_α-response, including different external provocations of LPS challenge and test compound intervention, was developed. The model contained system properties (such as k_t, k_out), challenge characteristics (such as k_s, k_LPS, K_m, LPS, S_max, SC₅₀) and test-compound-related parameters (I_max, IC₅₀). The exposure to test compound was modelled by means of first-order input and Michaelis–Menten type of nonlinear elimination. Test compound potency was estimated to 20 nM with a 70% partial reduction in TNF_α-response at the highest dose of 30 mg·kg⁻¹. Future selection of drug candidates may focus the estimation on potency and efficacy by applying the selected structure consisting of TNF_α system and LPS challenge characteristics. A related aim was to demonstrate how an exploratory (graphical) analysis may guide us to a tentative model structure, which enables us to better understand target biology. The analysis demonstrated how to tackle a biomarker with a baseline below the limit of detection. Repeated LPS-challenges may also reveal how the rate and extent of replenishment of TNF_α pools occur. Lack of LPS exposure-time courses was solved by including a biophase model, with the underlying assumption that TNF_α-response time courses, as such, contain kinetic information. A transduction type of model with non-linear stimulation of TNF_α release was finally selected. Typical features of a challenge experiment were shown by means of model simulations. Experimental shortcomings of present and published designs are identified and discussed. The final model coupled to suggested guidance rules may serve as a general basis for the collection and analysis of pharmacological challenge data of future studies.

The affinity, intrinsic activity and selectivity of a structurally novel EP2 receptor agonist at human prostanoid receptors

BACKGROUND AND PURPOSE

Prostanoid EP₂ receptor agonists exhibit several activities including ocular hypotension, tocolysis and anti-inflammatory activity. This report describes the affinity and selectivity of a structurally novel, non-prostanoid EP₂ receptor agonist, PGN-9856, and its therapeutic potential.

EXPERIMENTAL APPROACH

The pharmacology of a series of non-prostanoid EP₂ receptor agonists was determined according to functional and radioligand binding studies, mostly using human recombinant prostanoid receptor transfectants. The selectivity of PGN-9856, as the preferred compound, was subsequently determined by using a diverse variety of non-prostanoid target proteins. The therapeutic potential of PGN-9856 was addressed by determining its activity in relevant primate cell, tissue and disease models.

KEY RESULTS

PGN-9856 was a selective and high affinity (pKi ≥ 8.3) ligand at human recombinant EP₂ receptors. In addition to high affinity binding, it was a potent and full EP₂ receptor agonist with a high level of selectivity at EP₁ , EP₃ , EP₄ , DP, FP, IP and TP receptors. In cells overexpressing human recombinant EP₂ receptors, PGN-9856 displayed a potency (pEC₅₀ ≥ 8.5) and a maximal response (increase in cAMP) comparable to that of the endogenous agonist PGE₂ . PGN-9856 exhibited no appreciable affinity (up 10 μM) for a range of 53 other receptors, ion channels and enzymes. Finally, PGN-9856 exhibited tocolytic, anti-inflammatory and long-acting ocular hypotensive properties consistent with its potent EP₂ receptor agonist properties.

CONCLUSIONS AND IMPLICATIONS

PGN-9856 is a potent, selective and efficacious prostanoid EP₂ receptor agonist with diverse potential therapeutic applications: tocolytic, anti-inflammatory and notably anti-glaucoma.

ADAM19: A Novel Target for Metabolic Syndrome in Humans and Mice

Obesity is one of the most prevalent metabolic diseases in the Western world and correlates directly with insulin resistance, which may ultimately culminate in type 2 diabetes (T2D). We sought to ascertain whether the human metalloproteinase A Disintegrin and Metalloproteinase 19 (ADAM19) correlates with parameters of the metabolic syndrome in humans and mice. To determine the potential novel role of ADAM19 in the metabolic syndrome, we first conducted microarray studies on peripheral blood mononuclear cells from a well-characterised human cohort. Secondly, we examined the expression of ADAM19 in liver and gonadal white adipose tissue using an in vivo diet induced obesity mouse model. Finally, we investigated the effect of neutralising ADAM19 on diet induced weight gain, insulin resistance in vivo, and liver TNF-α levels. Significantly, we show that, in humans, ADAM19 strongly correlates with parameters of the metabolic syndrome, particularly BMI, relative fat, HOMA-IR, and triglycerides. Furthermore, we identified that ADAM19 expression was markedly increased in the liver and gonadal white adipose tissue of obese and T2D mice. Excitingly, we demonstrate in our diet induced obesity mouse model that neutralising ADAM19 therapy results in weight loss, improves insulin sensitivity, and reduces liver TNF-α levels. Our novel data suggest that ADAM19 is pro-obesogenic and enhances insulin resistance. Therefore, neutralisation of ADAM19 may be a potential therapeutic approach to treat obesity and T2D.

An improved fluorescent substrate for assaying soluble and membrane-associated ADAM family member activities

A fluorescent resonance energy transfer substrate with improved sensitivity for ADAM17, -10, and -9 (where ADAM represents a disintegrin and metalloproteinase) has been designed. The new substrate, Dabcyl-Pro-Arg-Ala-Ala-Ala-Homophe-Thr-Ser-Pro-Lys(FAM)-NH2, has specificity constants of 6.3 (±0.3) × 10(4) M(-1) s(-1) and 2.4 (±0.3) × 10(3) M(-1) s(-1) for ADAM17 and ADAM10, respectively. The substrate is more sensitive than widely used peptides based on the precursor tumor necrosis factor-alpha (TNF-alpha) cleavage site, PEPDAB010 or Dabcyl-Ser-Pro-Leu-Ala-Gln-Ala-Val-Arg-Ser-Ser-Lys(FAM)-NH2 and Mca-Pro-Leu-Ala-Gln-Ala-Val-Dpa-Arg-Ser-Ser-Arg-NH2. ADAM9 also processes the new peptide more than 18-fold better than the TNF-alpha-based substrates. The new substrate has a unique selectivity profile because it is processed less efficiently by ADAM8 and MMP1, -2, -3, -8, -9, -12, and -14. This substrate provides a unique tool in which to assess ADAM17, -10, and -9 activities.

Modeling and design of challenge tests: Inflammatory and metabolic biomarker study examples

Given the complexity of pharmacological challenge experiments, it is perhaps not surprising that design and analysis, and in turn interpretation and communication of results from a quantitative point of view, is often suboptimal. Here we report an inventory of common designs sampled from anti-inflammatory, respiratory and metabolic disease drug discovery studies, all of which are based on animal models of disease involving pharmacological and/or patho/physiological interaction challenges. The corresponding data are modeled and analyzed quantitatively, the merits of the respective approach discussed and inferences made with respect to future design improvements. Although our analysis is limited to these disease model examples, the challenge approach is generally applicable to the vast majority of pharmacological intervention studies. In the present five Case Studies results from pharmacodynamic effect models from different therapeutic areas were explored and analyzed according to five typical designs. Plasma exposures of test compounds were assayed by either liquid chromatography/mass spectrometry or ligand binding assays. To describe how drug intervention can regulate diverse processes, turnover models of test compound-challenger interaction, transduction processes, and biophase time courses were applied for biomarker response in eosinophil count, IL6 response, paw-swelling, TNFα response and glucose turnover in vivo. Case Study 1 shows results from intratracheal administration of Sephadex, which is a glucocorticoid-sensitive model of airway inflammation in rats. Eosinophils in bronchoalveolar fluid were obtained at different time points via destructive sampling and then regressed by the mixed-effects modeling. A biophase function of the Sephadex time course was inferred from the modeled eosinophil time courses. In Case Study 2, a mouse model showed that the time course of cytokine-induced IL1β challenge was altered with or without drug intervention. Anakinra reversed the IL1β induced cytokine IL6 response in a dose-dependent manner. This Case Study contained time courses of test compound (drug), challenger (IL1β) and cytokine response (IL6), which resulted in high parameter precision. Case Study 3 illustrates collagen-induced arthritis progression in the rat. Swelling scores (based on severity of hind paw swelling) were used to describe arthritis progression after the challenge and the inhibitory effect of two doses of an orally administered test compound. In Case Study 4, a cynomolgus monkey model for lipopolysaccharide LPS-induced TNFα synthesis and/or release was investigated. This model provides integrated information on pharmacokinetics and in vivo potency of the test compounds. Case Study 5 contains data from an oral glucose tolerance test in rats, where the challenger is the same as the pharmacodynamic response biomarker (glucose). It is therefore convenient to model the extra input of glucose simultaneously with baseline data and during intervention of a glucose-lowering compound at different dose levels. Typically time-series analyses of challenger- and biomarker-time data are necessary if an accurate and precise estimate of the pharmacodynamic properties of a test compound is sought. Erosion of data, resulting in the single-point assessment of drug action after a challenge test, should generally be avoided. This is particularly relevant for situations where one expects time-curve shifts, tolerance/rebound, impact of disease, or hormetic concentration-response relationships to occur.

TNF and TNF-receptors: From mediators of cell death and inflammation to therapeutic giants - past, present and future

Tumor Necrosis Factor (TNF), initially known for its tumor cytotoxicity, is a potent mediator of inflammation, as well as many normal physiological functions in homeostasis and health, and anti-microbial immunity. It also appears to have a central role in neurobiology, although this area of TNF biology is only recently emerging. Here, we review the basic biology of TNF and its normal effector functions, and discuss the advantages and disadvantages of therapeutic neutralization of TNF - now a commonplace practice in the treatment of a wide range of human inflammatory diseases. With over ten years of experience, and an emerging range of anti-TNF biologics now available, we also review their modes of action, which appear to be far more complex than had originally been anticipated. Finally, we highlight the current challenges for therapeutic intervention of TNF: (i) to discover and produce orally delivered small molecule TNF-inhibitors, (ii) to specifically target selected TNF producing cells or individual (diseased) tissue targets, and (iii) to pre-identify anti-TNF treatment responders. Although the future looks bright, the therapeutic modulation of TNF now moves into the era of personalized medicine with society's challenging expectations of durable treatment success and of achieving long-term disease remission.

Matrix metalloproteinase inhibition lowers mortality and brain injury in experimental pneumococcal meningitis

Pneumococcal meningitis (PM) results in high mortality rates and long-lasting neurological deficits. Hippocampal apoptosis and cortical necrosis are histopathological correlates of neurofunctional sequelae in rodent models and are frequently observed in autopsy studies of patients who die of PM. In experimental PM, inhibition of matrix metalloproteinases (MMPs) and/or tumor necrosis factor (TNF)-converting enzyme (TACE) has been shown to reduce brain injury and the associated impairment of neurocognitive function. However, none of the compounds evaluated in these studies entered clinical development. Here, we evaluated two second-generation MMP and TACE inhibitors with higher selectivity and improved oral availability. Ro 32-3555 (Trocade, cipemastat) preferentially inhibits collagenases (MMP-1, -8, and -13) and gelatinase B (MMP-9), while Ro 32-7315 is an efficient inhibitor of TACE. PM was induced in infant rats by the intracisternal injection of live Streptococcus pneumoniae. Ro 32-3555 and Ro 32-7315 were injected intraperitoneally, starting at 3 h postinfection. Antibiotic (ceftriaxone) therapy was initiated at 18 h postinfection, and clinical parameters (weight, clinical score, mortality rate) were recorded. Myeloperoxidase activities, concentrations of cytokines and chemokines, concentrations of MMP-2 and MMP-9, and collagen concentrations were measured in the cerebrospinal fluid. Animals were sacrificed at 42 h postinfection, and their brains were assessed by histomorphometry for hippocampal apoptosis and cortical necrosis. Both compounds, while exhibiting disparate MMP and TACE inhibitory profiles, decreased hippocampal apoptosis and cortical injury. Ro 32-3555 reduced mortality rates and cerebrospinal fluid TNF, interleukin-1β (IL-1β) and collagen levels, while Ro 32-7315 reduced weight loss and cerebrospinal fluid TNF and IL-6 levels.

Role of ADAM-17, p38 MAPK, cathepsins, and the proteasome pathway in the synthesis and shedding of fractalkine/CX₃ CL1 in rheumatoid arthritis

OBJECTIVE

To evaluate the mechanism of fractalkine (FKN)/CX3 CL1 synthesis and shedding in rheumatoid arthritis synovial fibroblasts (RASFs) and in rat adjuvant-induced arthritis (AIA).

METHODS

The effect of tumor necrosis factor α (TNFα) and/or interferon-γ (IFNγ) on FKN synthesis and shedding in human RASFs was determined over time by immunostaining, quantitative reverse transcription-polymerase chain reaction, and Western blotting. The role of protease enzymes and signaling pathways was evaluated using chemical inhibitors and small interfering RNA (siRNA). The activity of 20S proteasome in the lysates and the DNA binding of NF-κB/p65 in the nuclear fractions were evaluated. The in vivo relevance of these findings was examined in rat AIA.

RESULTS

In RASFs, stimulation with the combination of TNFα and IFNγ induced cellular expression of FKN within 24 hours. Activation of ADAM-17, but not ADAM-10, partly mediated the proteolytic shedding and release of soluble FKN (sFKN) following TNFα/IFNγ stimulation for 24-72 hours. Compared with control siRNA, ADAM-17 siRNA markedly inhibited TNFα/IFNγ-induced sFKN production (by ∼33%). TNFα/IFNγ-induced sFKN release was markedly suppressed by inhibitors of ADAM-17, p38 MAPK, proteasome, or cathepsin inhibitor but not by inhibitors of caspase 3 or calpain. TNFα/IFNγ-induced proteasome activity also correlated with rapid degradation of IκBα and p38 MAPK phosphorylation. In vivo findings showed increased FKN expression in the joints of rats with AIA, which correlated with increased expression of ADAM-17 and phospho-p38 MAPK.

CONCLUSION

Our results provide new understanding of the role of ADAM-17, p38 MAPK, cathepsins, and the proteasome pathway in FKN expression and shedding. Regulating these pathways may suppress FKN-mediated inflammation and tissue destruction.

Unlike for human monocytes after LPS activation, release of TNF-α by THP-1 cells is produced by a TACE catalytically different from constitutive TACE

BACKGROUND

Tumor necrosis factor-alpha (TNF-α) is a pro-inflammatory cytokine today identified as a key mediator of several chronic inflammatory diseases. TNF-α, initially synthesized as a membrane-anchored precursor (pro-TNF-α), is processed by proteolytic cleavage to generate the secreted mature form. TNF-α converting enzyme (TACE) is currently the first and single protease described as responsible for the inducible release of soluble TNF-α.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we demonstrated the presence on THP-1 cells as on human monocytes of a constitutive proteolytical activity able to cleave pro-TNF-α. Revelation of the cell surface TACE protein expression confirmed that the observed catalytic activity is due to TACE. However, further studies using effective and innovative TNF-α inhibitors, as well as a highly selective TACE inhibitor, support the presence of a catalytically different sheddase activity on LPS activated THP-1 cells. It appears that this catalytically different TACE protease activity might have a significant contribution to TNF-α release in LPS activated THP-1 cells, by contrast to human monocytes where the TACE activity remains catalytically unchanged even after LPS activation.

CONCLUSIONS/SIGNIFICANCE

On the surface of LPS activated THP-1 cells we identified a releasing TNF-α activity, catalytically different from the sheddase activity observed on human monocytes from healthy donors. This catalytically-modified TACE activity is different from the constitutive shedding activity and appears only upon stimulation by LPS.

Therapeutic approaches for tumor necrosis factor inhibition

Tumor necrosis factor (TNF) consists of an inflammatory cytokine essential for homeostasis and organism defense. Despite its physiological relevance, both increased biosynthesis and release of TNF lead to the exacerbation of inflammatory and oxidative responses, which are related to the pathogenesis of a host of diseases of an inflammatory, autoimmune and/or infectious nature. In this context, effective therapeutic approaches for the modulation of TNF have been the focus of research efforts. Approximately one million individuals worldwide have been treated with biotechnological inhibitors of this cytokine, the so-called anti-TNF biopharmaceuticals. However, given the high risk of infection and the limitations related to cost and administration routes, new therapeutic approaches aimed at biological targets that directly or indirectly modulate the production and/or activation of TNF appear promising alternatives for the discovery of new anti-inflammatory and immunomodulatory orally active drugs and are therefore discussed in this paper.

Vascular Dysfunction in Brain Hemorrhage: Translational Pathways to Developing New Treatments from Old Targets

Hemorrhagic stroke which is a form of stroke that affects 20% of all stroke patients is a devastating condition for which new treatments must be developed. Current treatment methods are quite insufficient to reduce long term morbidity and high mortality rate, up to 50%, associated with bleeding into critical brain structures, into ventricular spaces and within the subarachnoid space. During the last 10-15 years, significant advances in the understanding of important mechanisms that contribute to cell death and clinical deficits have been made. The most important observations revolve around a key set of basic mechanisms that are altered in brain bleeding models, including activation of membrane metalloproteinases, oxidative stress and both inflammatory and coagulation pathways. Moreover, it is now becoming apparent that brain hemorrhage can activate the ischemic stroke cascade in neurons, glial cells and the vascular compartment. The activation of multiple pathways allows comes the opportunity to intervene pharmacologically using monotherapy or combination therapy. Ultimately, combination therapy or pleiotropic compounds with multi-target activities should prove to be more efficacious than any single therapy alone. This article provides a comprehensive look at possible targets for small molecule intervention as well as some new approaches that result in metabolic down-regulation or inhibition of multiple pathways simultaneously.

Synthesis and biological evaluation of novel phthalazinone derivatives as topically active phosphodiesterase 4 inhibitors

Inhibitors of phosphodiesterase 4 (PDE4) are an important class of anti-inflammatory drug that act by inhibiting the production of proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha). We have synthesized and evaluated a series of 2-substituted phthalazinone derivatives as PDE4 inhibitors. Structure-activity relationship studies led to the identification of benzylamine-substituted phthalazinones as potent PDE4 inhibitors that also suppressed TNF-alpha production by whole rat blood cells. The most potent of these, when topically administered, were effective in a mouse model of dermatitis.

High shed antigen levels within tumors: an additional barrier to immunoconjugate therapy

Shedding of cell surface antigens is an important biological process that is used by cells to modulate responses to signals in the extracellular environment. Because antibody-based therapies of cancer target cell surface antigens, it is important to understand more about the shedding process and how it affects tumor responses to this type of therapy. Up to now most attention has been focused on measuring the concentration of shed antigens in the blood and using these to determine the presence of a tumor and as a measure of response. The recent finding that the concentration of the tumor antigen mesothelin is extremely high within the interstitial space of tumors, where it can block antibody action, and that the concentration of shed mesothelin within the tumor is lowered by chemotherapy has important implications for the successful treatment of solid tumors by immunoconjugates and whole antibodies.

Three-dimensional extracellular matrix culture models of EGFR signalling and drug response

Three-dimensional extracellular matrix culture, on substrata such as Matrigel, restores many aspects of the differentiated state to non-malignant cells from a variety of tissues. We have adapted these techniques to study EGFR (epidermal growth factor receptor) signalling and drug response in breast cancer cell lines. EGFR-dependent breast cancer cell lines undergo a striking reversion of the malignant phenotype upon treatment with inhibitors targeting the receptor, or downstream signalling intermediates such as mitogen-activated protein kinase and PI3K (phosphoinositide 3-kinase). Using this approach, we have recently reported that EGFR signalling in breast cancer can be effectively inhibited by blocking the activity of a key protease, TACE [TNFalpha (tumour necrosis factor alpha)-converting enzyme], which regulates the bioavailability of EGFR ligands. These results suggest a new way to target EGFR signalling in tumours of the breast and other epithelial tissues and underline the value of three-dimensional extracellular matrix culture models for exploring cancer-relevant signalling processes ex vivo.

Tackling EGFR signaling with TACE antagonists: a rational target for metalloprotease inhibitors in cancer

TNF-alpha converting enzyme (TACE/ADAM17) is a transmembrane metalloprotease that plays a key role in the cleavage and mobilization of receptor ligands that are initially synthesized as membrane-tethered precursors. For many years, attention has focused on the role of TACE-dependent TNF-alpha cleavage in arthritis and, more recently, it has become apparent that TACE also plays an important role in regulating epidermal growth factor receptor activity in several tumor types. This review presents the background to these findings and a rationale for the continued development of TACE inhibitors for the treatment of epidermal growth factor receptor-dependent epithelial tumors.

Advances in hemorrhagic stroke therapy: conventional and novel approaches

Treatments for spontaneous intracerebral, thrombolytic-induced and intraventricular hemorrhages (IVH) are still at the preclinical or early clinical investigational stages. There has been some renewed interest in the use of surgical evacuation surgery or thrombolytics to remove hematomas, but these techniques can be used only for specific types of brain bleeding. The STICH (Surgical Trial in Intracerebral Haemorrhage) clinical trials should provide some insight into the potential for such techniques to counteract hematoma-induced damage and subsequently, morbidity and mortality. More recently, clinical trials (ATACH [Antihypertensive Treatment in Acute Cerebral Hemorrhage] and INTERACT [Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial]) have begun testing whether or not regulating blood pressure affects the well-being of hemorrhage patients, but the findings thus far have not conclusively demonstrated a positive result. More promising trials, such as the early stage CHANT (Cerebral Hemorrhagic And NXY-059 Treatment) and the late stage FAST (Factor VIIa for Acute Hemorrhagic Stroke Treatment), have addressed whether or not manipulating oxidative stress and components of the blood coagulation cascade can achieve an improved prognosis following spontaneous hemorrhages. However, CHANT was halted prematurely because although it showed that the spin trap agent NXY-059 was safe, it also demonstrated that the drug was ineffective in treating acute ischemic stroke. In addition, the recombinant activated factor VII FAST trial recently concluded with only modestly positive results. Despite a beneficial effect on the primary end point of reducing hemorrhage volume, controlling the coagulation cascade with recombinant factor VIIa did not decrease the mortality rate. Consequently, Novo Nordisk has abandoned further development of the drug for the treatment of intracerebral hemorrhaging. Even though progress in hemorrhage therapy that successfully reduces the escalating morbidity and mortality rate associated with brain bleeding is slow, perseverance and applied translational drug development will eventually be productive. The urgent need for such therapy becomes more evident in light of concerns related to uncontrolled high blood pressure in the general population, increased use of blood thinners by the elderly (e.g., warfarin) and thrombolytics by acute ischemic stroke patients, respectively. The future of drug development for hemorrhage may require a multifaceted approach, such as combining drugs with diverse mechanisms of action. Because of the substantial benefit of factor VIIa in reducing hemorrhage volume, it should be considered as a prime drug candidate included in combination therapy as an off-label use if the FAST trial proves that the risk of thromboembolic events is not increased with drug administration. Other promising drugs that may be considered in combination include uncompetitive NMDA receptor antagonists (such as memantine), antioxidants, metalloprotease inhibitors, statins and erythropoietin analogs, all of which have been shown to reduce hemorrhage and behavioral deficits in one or more animal models.

Tumor necrosis factor-α is involved in thrombolytic-induced hemorrhage following embolic strokes in rabbits

The present study assessed whether tumor necrosis factor-alpha (TNFalpha) is involved in hemorrhage following large clot embolism-induced ischemia in New Zealand white rabbits by intracisternally administering either TNFalpha or a goat-anti-rabbit-TNFalpha antibody following a stroke. The first aim of the study showed that TNFalpha administration increased stroke-induced hemorrhage incidence to 53.3% from 18.5% (an increase of 188%) in the control group and also increased hemorrhage volume by 87% (p<0.05). The second aim showed that administration of tissue plasminogen activator (tPA) using a standard dose of 3.3 mg/kg increased hemorrhage incidence in rabbits to 76.5% from 18.5% (an increase of 314%) and this effect was reversed by administration of an anti-TNFalpha antibody. In the tPA-anti-TNFalpha antibody group, the absolute hemorrhage rate was 38.8% and the hemorrhage volume was 98% of control. In conclusion, following an embolic stroke, TNFalpha administration increased the incidence and volume of hemorrhage and an anti-TNFalpha antibody counteracted tPA-induced hemorrhage. The results suggest that TNFalpha may either be directly or indirectly involved in vascular damage following an embolic stroke. Moreover, TNFalpha may mediate some of the detrimental effects of tPA on the vascular compartment. Based upon our studies, TNFalpha receptor antagonists or TNFalpha processing inhibitors should be further pursued as targets for the treatment of hemorrhagic stroke as adjuvant treatment for stroke patients receiving thrombolytic treatment.

Pharmacokinetics and pharmacodynamics of DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)), a potent and selective inhibitor of tumor necrosis factor alpha-converting enzyme in rodents, dogs, chimpanzees, and humans

DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)) is a potent and selective inhibitor of tumor necrosis factor (TNF)-alpha-converting enzyme (TACE). It significantly inhibits lipopolysaccharide-induced soluble TNF-alpha production in blood from rodents, chimpanzee, and human, with IC(50) values ranging from 17 to 100 nM. In rodent models of endotoxemia, DPC 333 inhibited the production of TNF-alpha in a dose-dependent manner, with an oral ED(50) ranging from 1.1 to 6.1 mg/kg. Oral dosing of DPC 333 at 5.5 mg/kg daily for 2 weeks in a rat collagen antibody-induced arthritis model suppressed the maximal response by approximately 50%. DPC 333 was distributed widely to tissues including the synovium, the site of action for antiarthritic drugs. Pharmacokinetic and pharmacodynamic studies in chimpanzee revealed a systemic clearance of 0.4 l/h/kg, a V(ss) of 0.6 l/kg, an oral bioavailability of 17%, and an ex vivo IC(50) for the suppression of TNF-alpha production of 55 nM (n = 1). In a phase I clinical trial with male volunteers after single escalating doses of oral DPC 333, the terminal half-life was between 3 and 6 h and the ex vivo IC(50) for suppressing TNF-alpha production was 113 nM. Measurement of the suppression of TNF-alpha production ex vivo may serve as a good biomarker in evaluating the therapeutic efficacy of TACE inhibitors. Overall, the pharmacological profiles of DPC 333 support the notion that suppression of TNF-alpha with TACE inhibitors like DPC 333 may provide a novel approach in the treatment of various inflammatory diseases including rheumatoid arthritis, via control of excessive TNF-alpha production.

TACE: a new target in epidermal growth factor receptor dependent tumors

Soluble proteins play vital roles in mediating intercellular communication. Many of these proteins are secreted as freely soluble molecules, but an important class of signaling proteins are first synthesized and presented at the cell surface as transmembrane precursor proteins. Unlike classically secreted proteins, many of these molecules are regulated at an additional level, requiring proteolytic cleavage for activity. This review focuses on a subset of these proteins, which are cleaved by tumor necrosis factor alpha-converting enzyme (TACE)/ADAM17, and on their role in cancer.

Structure-based design of TACE selective inhibitors: manipulations in the S1'-S3' pocket

A series of beta-sulfonyl hydroxamate TACE inhibitors, bearing a butynylamino or a butynyloxy P1' group, was designed and synthesized. Of the compounds investigated, 22 has excellent potency against isolated TACE enzyme, shows good selectivity over MMP-2 and MMP-13, and oral activity in an in vivo mouse model of TNF-alpha production.

A rat pharmacokinetic/pharmacodynamic model for assessment of lipopolysaccharide-induced tumor necrosis factor-alpha production

INTRODUCTION

Tumor necrosis factor-alpha (TNFalpha) participates in many inflammatory processes. TNFalpha modulators show beneficial effects for the treatment of many diseases including rheumatoid arthritis. The purpose of this study was to validate a rat pharmacokinetic/pharmacodynamic (PK/PD) model for rapid assessment of drug candidates that intended to interrupt TNFalpha synthesis or release.

METHODS

Rats received intravenous (IV) or oral administrations of test article or dose vehicle, followed by LPS challenge. Plasma levels of test article and TNFalpha were determined. The areas under the concentration-time curves (AUC(drug) and AUC(TNFalpha)) were calculated. The overall percentage of inhibition on TNFalpha release in vivo was calculated by comparing AUC(TNFalpha) of the test article treated group against that for the vehicle control group.

RESULTS

The dosing vehicles tested in this study did not increase plasma TNFalpha level. At IV dose of up to 100 microg/kg, LPS did not alter the pharmacokinetics of the compound tested. Using a selective TNFalpha converting enzyme (TACE) inhibitor as model compound, this PK/PD model demonstrated its ability to correlate plasma test article concentration with its biological activity of lowering the LPS-induced TNFalpha plasma levels in vivo.

DISCUSSION

A rat PK/PD model for evaluation of the effect of drug candidates on LPS-induced TNFalpha synthesis and/or release has been investigated. This model provides integrated information on pharmacokinetics and in vivo potency of the test articles.

Targeting TACE-dependent EGFR ligand shedding in breast cancer

The ability to proliferate independently of signals from other cell types is a fundamental characteristic of tumor cells. Using a 3D culture model of human breast cancer progression, we have delineated a protease-dependent autocrine loop that provides an oncogenic stimulus in the absence of proto-oncogene mutation. Targeting this protease, TNF-alpha-converting enzyme (TACE; also referred to as a disintegrin and metalloproteinase 17 [ADAM17]), with small molecular inhibitors or siRNAs reverted the malignant phenotype in a breast cancer cell line by preventing mobilization of 2 crucial growth factors, TGF-alpha and amphiregulin. We show that TACE-dependent ligand shedding was prevalent in a series of additional breast cancer cell lines and, in all cases examined, was amenable to inhibition. Using existing patient outcome data, we demonstrated a strong correlation between TACE and TGFA expression in human breast cancers that was predictive of poor prognosis. Tumors resulting from inappropriate activation of the EGFR were common in multiple tissues and were, for the most part, refractory to current targeted therapies. The data presented here delineate the molecular mechanism by which constitutive EGFR activity may be achieved in tumor progression without mutation of the EGFR itself or downstream pathway components and suggest that this important oncogenic pathway might usefully be targeted upstream of the receptor.

Nimesulide-induced antipyresis in rats involves both cyclooxygenase-dependent and independent mechanisms

This study evaluates the antipyretic activity of nimesulide, a cyclooxygenase (COX-2) selective inhibitor in rats. The effects of nimesulide on lipopolysaccharide (LPS)-induced cerebrospinal prostaglandin E(2) (PGE(2)) and prostaglandin F(2alpha) (PGF(2alpha)) and on plasma tumor necrosis factor-alpha (TNF-alpha) levels were also evaluated. Male Wistar rats received an i.p. injection of LPS, or i.c.v. injections of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), TNF-alpha, macrophage inflammatory protein-1alpha (MIP-1alpha), arachidonic acid, PGE(2), PGF(2alpha), corticotrophin-releasing factor (CRF) or endothelin-1 (ET-1). Nimesulide or indomethacin administered i.p 30 min prior LPS, IL-1beta, IL-6, TNF-alpha or arachidonic acid reduced the febrile response and PGE(2) or PGF(2alpha) levels in LPS-febrile rats but did not modify PGE(2)-induced fever. Nimesulide, but not indomethacin, reduced the fever induced by MIP-1alpha, PGF(2alpha), CRF or ET-1. Plasma TNF-alpha levels in LPS-treated rats were also reduced by nimesulide. These findings confirm that the antipyretic effect of nimesulide differs from the antipyretic scenario with the non-selective cyclooxygenase blocker indomethacin. Additional mechanisms, including inhibition of increased plasma TNF-alpha, may contribute to its antipyretic activity in rats.

Modulation of autocrine TNF-alpha-stimulated matrix metalloproteinase 9 (MMP-9) expression by mitogen-activated protein kinases in THP-1 monocytic cells

Matrix metalloproteinase 9 (MMP-9) is implicated in various physiological processes by its ability to degrade the extracellular matrix (ECM) and process multiple regulatory proteins. Normally, MMP-9 expression is tightly controlled in cells. Sustained or enhanced MMP-9 secretion, however, has been demonstrated to contribute to the pathophysiology of numerous diseases, including arthritis and tumor progression, rendering this enzyme a major target for clinical interventions. Here we show that constitutive MMP-9 secretion was abrogated in THP-1 monocytic leukemia cells by addition of neutralizing antibodies against tumor necrosis factor alpha (TNF-alpha) or TNF receptor type 1 (TNF-R1), as well as by inhibition of TNF-alpha converting enzyme (TACE). This indicates that MMP-9 production in these cells is maintained by autocrine stimulation, with TNF-alpha acting via TNF-R1. To investigate the intracellular signaling routes involved in MMP-9 gene transcription, cells were treated with different inhibitors of major mitogen-activated protein kinase (MAPK) pathways. Interruption of the extracellular signal-regulated kinase pathway 1/2 (ERK1/2) using PD98059 significantly downregulated constitutive MMP-9 release. In contrast, blockage of p38 kinase activity by addition of SB203580 or SB202190, as well as inhibition of c-Jun N-terminal kinase (JNK) using L-JNK-I1, clearly augmented MMP-9 expression and secretion by an upregulation of ERK1/2 phosphorylation. Moreover, exogenously added TNF-alpha augmented MMP-9 synthesis and secretion in THP-1 cells via enhancement of ERK1/2 activity. Taken together, our results indicate that ERK1/2 activity plays a pivotal role in TNF-alpha-induced MMP-9 production and demonstrate its negative modulation by p38 and JNK activity. These findings suggest ERK1/2 rather than p38 and JNK as a reasonable target to specifically block MMP-9 expression using MAPK inhibitors in therapeutic applications.

Acetylenic TACE inhibitors. Part 3: Thiomorpholine sulfonamide hydroxamates

A series of thiomorpholine sulfonamide hydroxamate TACE inhibitors, all bearing propargylic ether P1' groups, was explored. In particular, compound 5h has excellent in vitro potency against isolated TACE enzyme and in cells, oral activity in a model of TNF-alpha production and a collagen-induced arthritis model, was selected as a clinical candidate for the treatment of RA.

Targeting matrix metalloproteases to improve cutaneous wound healing

Wound repair is a physiological event in which tissue injury initiates a repair process leading to restoration of structure and function of the tissue. Cutaneous wound repair can be divided into a series of overlapping phases including formation of fibrin clot, inflammatory response, granulation tissue formation incorporating re-epithelialisation and angiogenesis and finally, matrix formation and remodelling. Matrix metalloproteases (MMPs) are a family of neutral proteases that play a vital role throughout the entire wound healing process. They regulate inflammation, degrade the extracellular matrix (ECM) to facilitate the migration of cells and remodel the new ECM. However, excessive MMP activity contributes to the development of chronic wounds. Selective control of MMP activity may prove to be a valuable therapeutic approach to promote healing of chronic ulcers. Recent evidence indicates that the anticoagulant, activated protein C may be useful in the treatment of non-healing wounds by preventing excessive protease activity through inhibition of inflammation and selectively increasing MMP-2 activity to enhance angiogenesis and re-epithelialisation.

The TNF alpha converting enzyme (TACE/ADAM17) is expressed in the atherosclerotic lesions of apolipoprotein E-deficient mice: possible contribution to elevated plasma levels of soluble TNF alpha receptors

TNF alpha converting enzyme (TACE) critically regulates the inflammatory processes as it releases from the cell surface several transmembrane proteins, including TNFalpha (TNF) and its receptors TNFR1 and TNFR2. We investigated the expression of TACE in atherosclerotic lesions of apolipoproteinE-deficient (apoE (-/-)) mice. Five-week-old apoE(-/-) male mice were fed a high-fat diet and examined at 5, 10, 15 and 25 weeks of age. A group of wild-type C57BL/6 mice (WT) fed the high-fat diet for 25 weeks was included. In apoE(-/-) mice, lesions progressed with time in both aortic sinus and arch, in which TACE immunostaining also increased particularly between 5 and 15 weeks. TACE expression was also observed in human atherosclerotic plaques. The plasma levels of soluble TNFR1 and TNFR2 rose with atherosclerosis. In the 25-week-old WT mice, no lesions were observed and the plasma levels of TNFRs were 17% of those of age-matched apoE(-/-) mice. Incubated aortas of 25-week-old apoE(-/-) mice released much higher amounts of sTNF and sTNFRs than did aortas of 5-week-old apoE(-/-) mice or 25-week-old WT mice. Active TACE was expressed at the surface of macrophages isolated from apoE(-/-) mice. In conclusion, TACE expression is associated with lesions in atherosclerosis-prone sites. Our data suggest that atherosclerotic lesions-expressing TACE may contribute to the elevated levels of circulating sTNFRs.

Alpha1-antitrypsin monotherapy prolongs islet allograft survival in mice

Islet transplantation for type 1 diabetic patients shows promising results with the use of nondiabetogenic immunosuppressive therapy. However, in addition to compromising the immune system of transplant recipients, long-term studies demonstrate that islet viability is impaired. Here, we demonstrate that, in the absence of immunosuppressive agents, monotherapy with clinical-grade human alpha1-antitrypsin (hAAT), the major serum serine-protease inhibitor, prolongs islet graft survival and normoglycemia in transplanted allogeneic diabetic mice, lasting until the development of anti-hAAT antibodies. Compared to untreated or albumin-control-treated graft recipients, which rejected islets at day 10, AAT-treated mice displayed diminished cellular infiltrates and intact intragraft insulin production throughout treatment. Using peritoneal infiltration models, we demonstrate that AAT decreases allogeneic fibroblast-elicited natural-killer-cell influx by 89%, CD3-positive cell influx by 44%, and thioglycolate-elicited neutrophil emigration by 66%. ATT also extended islet viability in mice after streptozotocin-induced beta cell toxicity. In vitro, several islet responses to IL-1beta/IFNgamma stimulation were examined. In the presence of AAT, islets displayed enhanced viability and inducible insulin secretion. Islets also released 36% less nitric oxide and 82% less macrophage inflammatory protein 1 alpha and expressed 63% fewer surface MHC class II molecules. TNFalpha release from IL-1beta/IFNgamma-stimulated islet cells was reduced by 99%, accompanied by an 8-fold increase in the accumulation of membrane TNFalpha on CD45-positive islet cells. In light of the established safety record and the nondiabetogenic potential of AAT, these data suggest that AAT may be beneficial as adjunctive therapy in patients undergoing islet transplantation.

[TNF-alpha inhibitors in inflammatory bowel disease]

Inflammatory bowel disease (IBD) is a chronic immunoinflammatory response to an stimulus that activates a chain of cellular mediators causing intestinal damage. One of the most well recognized proinflammatory mediators involved in the pathogenesis of IBD is tumor necrosis factor alpha (TNFalpha). The treatment of IBD has advanced in parallel to the improvement of the knowledge of its physiopathology, leading to the development of biological therapies. An example of this kind of treatment is the use of substances that antagonize TNFalpha, such as monoclonal antibodies infliximab, adalimumab, natalizumab, etanercept or onercept, with infliximab being the unique approved for use in IBD. Several studies have demonstrated that inhibition of TNFalpha is useful in the treatment of Crohn's disease (CD). In CD, infliximab induces the remission of relapses which are refractory to the conventional treatment, prevents more relapses and induces a closure of enterocutaneous and perianal fistula that do not respond to first line treatment. However, infliximab is not useful in ulcerative colitis. Infliximab treatment has some drawbacks, such as the development of anti-infliximab antibodies, which cause a loss of efficacy of the treatment and hypersensitivity reactions. Other reported adverse effects of infliximab are the development of autoimmunity, such as that related with antinuclear or anti-DNA antibodies, or the reactivation of infections such as tuberculosis. In fact, a screening for tuberculosis is necessary before administration of infliximab. To reduce the adverse effects due to infliximab immunogenicity, several trials with humanized or completely human agents, such as adalimumab or onercept, are under way. Until the precise stimulus that triggers IBD is identified, biological therapies have a great future and the selective antagonism of TNFalpha is already a reality.

Synthesis and SAR of diazepine and thiazepine TACE and MMP inhibitors

Potent and selective TACE and MMP inhibitors utilizing the diazepine and thiazepine ring systems were synthesized and evaluated for biological activity in in vitro and in vivo models of TNF-alpha release. Oral activity in the mouse LPS model of TNF-alpha release was seen. Efficacy in the mouse collagen induced arthritis model was achieved with diazepine 20.

Proteasome inhibition activates the transport and the ectodomain shedding of TNF-α receptors in human endothelial cells

Binding of tumor necrosis factor-α (TNF-α) to its transmembrane receptors (TNFRs) mediates proinflammatory, apoptotic and survival responses in several cell types including vascular endothelial cells. Because ectodomain shedding of cell surface molecules can be modified by proteasome activity, we studied in human endothelial cells whether the TNF-α–TNFRs axis can be regulated by the cleavage of their transmembrane forms in a proteasome-dependent manner. We show that proteasome inhibition increases the release of TNF-α and TNFRs from human endothelial cells and decreases their cellular and cell surface expression. This phenomenon involves the transient activation of mitogen-activated protein kinase p42/p44 that triggers the dispersion of TNF-α and TNFRs from their intracellular Golgi-complex-associated pool towards the plasma membrane. This results in their enhanced cleavage by TNF-α converting enzyme (TACE) because it is reduced by synthetic metalloprotease inhibitors, recombinant TIMP-3 and by a dominant negative form of TACE. In the presence of TACE inhibitor, proteasome inhibition increases the cell surface expression of TNFRs and enhances the sensitivity of these cells to the proapoptotic effect of recombinant TNF-α.

In conclusion, our data provide evidence that proteasome inhibitors increase TACE-dependent TNFR-shedding in endothelial cells, supporting the use of these molecules in inflammatory disorders. In association with TACE inhibitor, proteasome inhibitors increase the amount of TNFRs at the cell surface and enhance the sensitivity to the proapoptotic effect of TNF-α, which might be of interest in the antitumor therapy.

Depletion of cellular cholesterol and lipid rafts increases shedding of CD30

CD30, a lymphoid activation marker, is shed into the cell environment after endoproteolytic cleavage of its ectodomain. Soluble (s)CD30 is able to suppress the Th1-type immune response. Because high serum levels of sCD30 and cholesterol-lowering drugs seem to be beneficial in some Th1-type autoimmune diseases, we focused on a link between CD30 shedding and the amount of cellular cholesterol. Cholesterol depletion of human Hodgkin lymphoma- and non-Hodgkin lymphoma-derived cell lines by methyl-beta-cyclodextrin led to a down-regulation of membrane-bound CD30 and increased release of sCD30. Additionally, the cholesterol-interfering drugs lovastatin, cholesterol oxidase, and filipin increased CD30 shedding. Both the down-regulation of membrane-anchored CD30 and the release of sCD30 were dependent on metalloproteinases. Using specific inhibitors, we detected TNF-alpha converting enzyme (TACE) as the leading enzyme responsible for cholesterol-dependent CD30 shedding. A Triton X-100-based method for lipid raft isolation revealed that CD30 was partially present in lipid rafts, whereas TACE was localized in the nonraft fractions. Disintegration of lipid rafts by cholesterol depletion might therefore lead to dynamic interactions of CD30 with TACE, resulting in enhanced shedding of CD30. Our results suggest a possible role of cholesterol-dependent shedding of CD30 in the pathogenesis of immune diseases.

Identification and Characterization of 4-[[4-(2-Butynyloxy)phenyl]sulfonyl]-N-hydroxy-2,2-dimethyl-(3S)thiomorpholinecarboxamide (TMI-1), a Novel Dual Tumor Necrosis Factor-α-Converting Enzyme/Matrix Metalloprotease Inhibitor for the Treatment of Rheumatoid Arthritis

Tumor necrosis factor (TNF)-alpha is a well validated therapeutic target for the treatment of rheumatoid arthritis. TNF-alpha is initially synthesized as a 26-kDa membrane-bound form (pro-TNF) that is cleaved by a Zn-metalloprotease named TNF-alpha-converting enzyme (TACE) to generate the 17-kDa, soluble, mature TNF-alpha. TACE inhibitors that prevent the secretion of soluble TNF-alpha may be effective in treating rheumatoid arthritis (RA) patients. Using a structure-based design approach, we have identified a novel dual TACE/matrix metalloprotease (MMP) inhibitor 4-[[4-(2-butynyloxy)phenyl]sulfonyl]-N-hydroxy-2,2-dimethyl-(3S)thiomorpholinecarboxamide (TMI-1). This molecule inhibits TACE and several MMPs with nanomolar IC(50) values in vitro. In cell-based assays such as monocyte cell lines, human primary monocytes, and human whole blood, it inhibits lipopolysaccharide (LPS)-induced TNF-alpha secretion at submicromolar concentrations, whereas there is no effect on the TNF-alpha mRNA level as judged by RNase protection assay. The inhibition of LPS-induced TNF-alpha secretion is selective because TMI-1 has no effect on the secretion of other proinflammatory cytokines such as interleukin (IL)-1beta, IL-6, and IL-8. Importantly, TMI-1 potently inhibits TNF-alpha secretion by human synovium tissue explants of RA patients. In vivo, TMI-1 is highly effective in reducing clinical severity scores in mouse prophylactic collagen-induced arthritis (CIA) at 5, 10, and 20 mg/kg p.o. b.i.d. and therapeutic CIA model at 100 mg/kg p.o. b.i.d. In summary, TMI-1, a dual TACE/MMP inhibitor, represents a unique class of orally bioavailable small molecule TNF inhibitors that may be effective and beneficial for treating RA.

TACE/ADAM-17 maturation and activation of sheddase activity require proprotein convertase activity

Proprotein convertases (PCs) have been proposed to play a role in tumor necrosis factor-alpha converting enzyme (TACE) processing/activation. Using the furin-deficient LoVo cells, as well as the furin-proficient synoviocytes and HT1080 cells expressing the furin inhibitor alpha(1)-PDX, we demonstrate that furin activity alone is not sufficient for effective maturation and activation of the TACE enzyme. Data from in vitro and in vivo cleavage assays indicate that PACE-4, PC5/PC6, PC1 and PC2 can directly cleave the TACE protein and/or peptide. PC inhibition in macrophages reduced the release of soluble TNF-alpha from transmembrane pro-TNF-alpha. We therefore conclude that furin, in addition to other candidate PCs, is involved in TACE maturation and activation.

Therapeutic strategies for rheumatoid arthritis

Recent years have seen considerable advances in our understanding of both the clinical and basic-research aspects of rheumatoid arthritis. Clinical progress has come from a better recognition of the natural history of the disease, the development and validation of outcome measures for clinical trials and, consequently, innovative trial designs. In parallel, basic research has provided clues to the pathogenic events underlying rheumatoid arthritis, and advances in biotechnology have facilitated the development of new classes of therapeutics. Here, we summarize the fruits of these advances: innovative approaches to the use of existing, traditional disease-modifying antirheumatic drugs; novel agents approved very recently; and further avenues that are presently under investigation or which are of more distant promise.

Upcoming biologic agents for the treatment of rheumatic diseases

The development of biologic agents has provided rheumatologists with a variety of new and effective treatment options. The success of early biologics, especially etanercept and infliximab for the treatment of rheumatoid arthritis, has spurred research into novel targets for the management of systemic inflammatory and autoimmune diseases. In addition, existing biologics approved for use in other diseases, such as rituximab, are now under study for the treatment of new indications. This article reviews ongoing research on the treatment of rheumatic diseases with new and existing biologic agents.

Synthesis and SAR of bicyclic heteroaryl hydroxamic acid MMP and TACE inhibitors

Potent and selective bicyclic heteroaryl hydroxamic acid MMP and TACE inhibitors were synthesized by a novel convergent route. Selectivity and efficacy versus MMPs and TACE could be controlled by appropriate substitution on the scaffolds and by variation of the P1' group. Select compounds were found to be effective in in vivo models of arthritis.