Discovery, optimization, and pharmacological characterization of novel heteroaroylphenylureas antagonists of C-C chemokine ligand 2 function

Role of chemokine receptor 2 in rheumatoid arthritis: A research update

Rheumatoid arthritis (RA) is a multisystemic and inflammatory autoimmune disease characterized by joint destruction. The C-C motif chemokine receptor 2 (CCR2) is mainly expressed in monocytes and T cells, initiating their migration to sites of inflammation, ultimately leading to cartilage damage and bone destruction. CCR2 has long been considered a prospective target for treating autoimmune diseases. However, clinical studies on inhibitors or neutralizing antibodies against CCR2 in RA have exhibited limited efficacy. Recent evidence indicates that CCR2 may play different roles in RA. Hence, a comprehensive understanding regarding the role of CCR2 may facilitate the development of targeted drugs and provide novel insights for improving CCL2-mediated inflammatory diseases. This review summarizes the biological characteristics of CCR2, the related signaling pathways, and recent developments in CCR2-targeting therapeutics.

Role of the CCL2-CCR2 axis in cardiovascular disease: Pathogenesis and clinical implications

The CCL2-CCR2 axis is one of the major chemokine signaling pathways that has received special attention because of its function in the development and progression of cardiovascular disease. Numerous investigations have been performed over the past decades to explore the function of the CCL2-CCR2 signaling axis in cardiovascular disease. Laboratory data on the CCL2-CCR2 axis for cardiovascular disease have shown satisfactory outcomes, yet its clinical translation remains challenging. In this article, we describe the mechanisms of action of the CCL2-CCR2 axis in the development and evolution of cardiovascular diseases including heart failure, atherosclerosis and coronary atherosclerotic heart disease, hypertension and myocardial disease. Laboratory and clinical data on the use of the CCL2-CCR2 pathway as a targeted therapy for cardiovascular diseases are summarized. The potential of the CCL2-CCR2 axis in the treatment of cardiovascular diseases is explored.

Discovery of Novel Pyrazolo[3,4-b] Pyridine Derivatives with Dual Activities of Vascular Remodeling Inhibition and Vasodilation for the Treatment of Pulmonary Arterial Hypertension

Current pulmonary arterial hypertension (PAH) therapeutic strategies mainly focus on vascular relaxation with less emphasis on vascular remodeling, which results in poor prognosis. Hence, dual pathway regulators with vasodilation effect via soluble guanylate cyclase (sGC) stimulation and vascular remodeling regulation effect by AMP-activated protein kinase (AMPK) inhibition provide more advantages and potentialities. Herein, we designed and synthesized a series of novel pyrazolo[3,4-b] pyridine derivatives based on sGC stimulator and AMPK inhibitor scaffolds. In vitro, 2 exhibited moderate vasodilation activity and higher proliferation and migration suppressive effects compared to riociguat. In vivo, 2 significantly decreased right ventricular systolic pressure (RVSP), attenuated pulmonary artery medial thickness (PAMT), and right ventricular hypertrophy (RVH) in hypoxia-induced PAH rat models (i.g.). Given the unique advantages of significant vascular remodeling inhibition and moderate vascular relaxation based on the dual pathway regulation, we proposed 2 as a promising lead for anti-PAH drug discovery.

The Angiotensin Receptor Blocker Losartan Suppresses Growth of Pulmonary Metastases via AT1R-Independent Inhibition of CCR2 Signaling and Monocyte Recruitment

Inflammatory monocytes have been shown to play key roles in cancer metastasis through promotion of tumor cell extravasation, growth, and angiogenesis. Monocyte recruitment to metastases is mediated primarily via the CCL2-CCR2 chemotactic axis. Thus, disruption of this axis represents an attractive therapeutic target for the treatment of metastatic disease. Losartan, a type I angiotensin II receptor (AT1R) antagonist, has been previously shown to have immunomodulatory actions involving monocyte and macrophage activity. However, the exact mechanisms accounting for these effects have not been fully elucidated. Therefore, we investigated the effects of losartan and its primary metabolite on CCL2-mediated monocyte recruitment and CCR2 receptor function using mouse tumor models and in vitro human monocyte cultures. We show, in this study, that losartan and its metabolite potently inhibit monocyte recruitment through the noncompetitive inhibition of CCL2-induced ERK1/2 activation, independent of AT1R activity. Studies in experimental metastasis models demonstrated that losartan treatment significantly reduced the metastatic burden in mice, an effect associated with a significant decrease in CD11b⁺/Ly6C⁺-recruited monocytes in the lungs. Collectively, these results indicate that losartan can exert antimetastatic activity by inhibiting CCR2 signaling and suppressing monocyte recruitment and therefore suggest that losartan (and potentially other AT1R blocker drugs) could be repurposed for use in cancer immunotherapy.

Histone lysine methyltransferase structure activity relationships that allow for segregation of G9a inhibition and anti-Plasmodium activity

Plasmodium falciparum HKMTs (PfHKMTs) play a key role in controlling Plasmodium gene expression and represent exciting new anti-malarial epigenetic targets. Using an inhibitor series derived from the diaminoquinazoline HKMT inhibitory chemotype, we have previously identified compounds with highly promising antimalarial activity, including irreversible asexual cycle blood stage-independent cytotoxic activity at nM concentrations, oral efficacy in in vivo models of disease, and the unprecedented ability to reactivate dormant liver stage parasites (hypnozoites). However, future development of this series will need to address host versus parasite selectivity, where inhibitory activity against human G9a is removed from the lead compounds, while maintaining potent anti-Plasmodium activity. Herein, we report an extensive study of the SAR of this series against both G9a and P. falciparum. We have identified key SAR features which demonstrate that high parasite vs. G9a selectivity can be achieved by selecting appropriate substituents at position 2, 4 and 7 of the quinazoline ring. We have also, in turn, discovered that potent G9a inhibitors can be identified by employing a 6-carbon 'Nle mimic' at position 7. Together, this data suggests that while broadly similar, the G9a and potential PfHKMT target(s) binding pockets and/or binding modes of the diaminoquinazoline analogues exhibit clear and exploitable differences. Based on this, we believe this scaffold to have clear potential for development into a novel anti-malarial therapeutic.

Pyrano-isochromanones as IL-6 inhibitors: synthesis, in vitro and in vivo antiarthritic activity

Bergenin (1), a unique fused C-glycoside isolated from Bergenia species, possesses interesting anti-inflammatory and antipain activities. To study SAR of this scaffold, first-generation derivatives were synthesized and evaluated for inhibition of lymphocyte proliferation and production of pro-inflammatory cytokines. The C-7 substituted derivatives showed inhibition of IL-6 as well as TNF-α production. Bergenin and its most potent IL-6 inhibitor derivatives 4e and 4f were then investigated in a panel of in vitro and in vivo inflammation/arthritis models. These compounds significantly decreased the expression of NF-kB and IKK-β in THP-1 cells. In in vivo study in BALB/c mice, a dose-dependent inhibition of SRBC-induced cytokines, reduction in humoral/cell-mediated immunity, and antibody titer was observed. The CIA study in DBA/1J mice indicated that compounds led to reduction in swelling of paws, cytokine levels, and anticollagen IgG1/IgG2a levels. The significant in vivo immunosuppressive efficacy of pyrano-isochromanones demonstrates the promise of this scaffold for development of next-generation antiarthritic drugs.

Role of chemokines in proteinuric kidney disorders

Experimental and human studies have shown that proteinuria contributes to the progression of renal disease. Overexposure to filtered proteins promotes the expression and release of chemokines by tubular epithelial cells, thus leading to inflammatory cell recruitment and renal impairment. This review focuses on recent progress in cellular and molecular understanding of the role of chemokines in the pathogenesis of proteinuria-induced renal injury, as well as their clinical implications and therapeutic potential.

Multi-scale optical imaging of the delayed type hypersensitivity reaction attenuated by rapamycin

Neutrophils and monocytes/macrophages (MMs) play important roles in the development of cell-mediated delayed type hypersensitivity (DTH). However, the dynamics of neutrophils and MMs during the DTH reaction and how the immunosuppressant rapamycin modulates their behavior in vivo are rarely reported. Here, we take advantage of multi-scale optical imaging techniques and a footpad DTH reaction model to non-invasively investigate the dynamic behavior and properties of immune cells from the whole field of the footpad to the cellular level. During the classic elicitation phase of the DTH reaction, both neutrophils and MMs obviously accumulated at inflammatory foci at 24 h post-challenge. Rapamycin treatment resulted in advanced neutrophil recruitment and vascular hyperpermeability at an early stage (4 h), the reduced accumulation of neutrophils (> 50% inhibition ratio) at 48 h, and the delayed involvement of MMs in inflammatory foci. The motility parameters of immune cells in the rapamycin-treated reaction at 4 h post-challenge displayed similar mean velocities, arrest durations, mean displacements, and confinements as the classic DTH reaction at 24 h. These results indicate that rapamycin treatment shortened the initial preparation stage of the DTH reaction and attenuated its intensity, which may be due to the involvement of T helper type 2 cells or regulatory T cells.

Current status of chemokines in the adult CNS

Chemokines - chemotactic cytokines - are small secreted proteins that attract and activate immune and non-immune cells in vitro and in vivo. It has been suggested that chemokines and their receptors play a role in the central nervous system (CNS), in addition to their well established role in the immune system. We focus here on three chemokines-CXCL12 (C-X-C motif ligand 12), CCL2 (C-C motif ligand 2), and CX3CL1 (C-X-3C motif ligand 1) - and their principal receptors - CXCR4 (C-X-C motif receptor 4), CCR2 (C-C motif receptor 2) and CX3CR1 (C-X-3C motif receptor 1), respectively. We first introduce the classification of chemokines and their G-protein coupled receptors and the main signaling pathways triggered by receptor activation. We then discuss the cellular distribution of CXCL12/CXCR4, CCL2/CCR2 and CX3CL1/CX3CR1 in adult brain and the neurotransmission and neuromodulation effects controlled by these chemokines in the adult CNS. Changes in the expression of CXCL12, CCL2 and CX3CL1 and their respective receptors are also increasingly being implicated in the pathogenesis of CNS disorders, such as Alzheimer's disease, Parkinson's disease, HIV-associated encephalopathy, stroke and multiple sclerosis, and are therefore plausible targets for future pharmacological intervention. The final section thus discusses the role of these chemokines in these pathophysiological states. In conclusion, the role of these chemokines in cellular communication may make it possible: (i) to identify new pathways of neuron-neuron, glia-glia or neuron-glia communications relevant to both normal brain function and neuroinflammatory and neurodegenerative diseases; (ii) to develop new therapeutic approaches for currently untreatable brain diseases.

Progress in the discovery of CC chemokine receptor 2 antagonists, 2009 - 2012

INTRODUCTION

CC chemokine receptor 2 (CCR2) is a key mediator of the activation and migration of inflammatory monocytes. As such, it has been investigated extensively as a target for therapeutic intervention in a diverse range of diseases.

AREAS COVERED

This article reviews both the patent and peer-reviewed literature on the discovery of CCR2 antagonists from January 2009 to December 2012. Developments have occurred within each of the major chemical families of CCR2 antagonists, and are framed in that context. As has been true historically, a number of the compound families also exhibit substantial activity against the related CC chemokine receptor 5 (CCR5), making them formally CCR2/5-dual antagonists.

EXPERT OPINION

Significant progress continues to be made in identifying novel, potent CCR2 antagonists. In addition, researchers have had success in addressing issues related to selectivity, cardiac safety, and preclinical pharmacokinetics. Establishing proof-of-concept in clinical trials remains the primary challenge for the field.

Targeting chemokines in proteinuria-induced renal disease

INTRODUCTION

Proteinuria is a common finding in glomerular diseases that contributes to the progression of chronic kidney injury. Tubular cells reabsorb the excess of albumin and other plasma proteins from the tubular lumen, triggering several pathophysiologic responses, such as overexpression of fibrogenic mediators and inflammatory chemokines. Chemokines are implicated both in the recruitment of inflammatory infiltrate and in a number of physiological and pathological processes related to protein overload.

AREAS COVERED

In recent years, the specific chemokines and their receptors and the intracellular signaling pathways involved in proteinuria-induced renal damage have been identified. This review provides an overview of the role of chemokines and their receptors in proteinuria-related renal disease and summarizes novel therapeutic approaches to restrain the progression of renal damage.

EXPERT OPINION

Inhibition of chemokine-induced biological activities is a promising therapeutic strategy in proteinuric disorders. Neutralizing antibodies and small organic molecules targeting chemokines and chemokine receptors have been proven to prevent inflammation and renal damage in experimental models of protein overload. Some of these compounds are currently being tested in human clinical trials.

The CCL2 synthesis inhibitor bindarit targets cells of the neurovascular unit, and suppresses experimental autoimmune encephalomyelitis

BACKGROUND

Production of the chemokine CCL2 by cells of the neurovascular unit (NVU) drives critical aspects of neuroinflammation. Suppression of CCL2 therefore holds promise in treating neuroinflammatory disease. Accordingly, we sought to determine if the compound bindarit, which inhibits CCL2 synthesis, could repress the three NVU sources of CCL2 most commonly reported in neuroinflammation--astrocytes, microglia and brain microvascular endothelial cells (BMEC)--as well as modify the clinical course of neuroinflammatory disease.

METHODS

The effect of bindarit on CCL2 expression by cultured murine astrocytes, microglia and BMEC was examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Bindarit action on mouse brain and spinal cord in vivo was similarly investigated by qRT-PCR following LPS injection in mice. And to further gauge the potential remedial effects of bindarit on neuroinflammatory disease, its impact on the clinical course of experimental autoimmune encephalomyelitis (EAE) in mice was also explored.

RESULTS

Bindarit repressed CCL2 expression by all three cultured cells, and antagonized upregulated expression of CCL2 in both brain and spinal cord in vivo following LPS administration. Bindarit also significantly modified the course and severity of clinical EAE, diminished the incidence and onset of disease, and evidenced signs of disease reversal.

CONCLUSION

Bindarit was effective in suppressing CCL2 expression by cultured NVU cells as well as brain and spinal cord tissue in vivo. It further modulated the course of clinical EAE in both preventative and therapeutic ways. Collectively, these results suggest that bindarit might prove an effective treatment for neuroinflammatory disease.