Imatinib stimulates prostaglandin E2 and attenuates cytokine release via EP4 receptor activation

Impact of Imatinib on reducing the painful crisis in patients with sickle cell disease

INTRODUCTION

Sickle cell disease (SCD) is a common hemoglobinopathy worldwide that causes painful crises and hospitalization of patients. These attacks decrease survival and cause chronic end-organ damage in these patients.

HYPOTHESIS

For this reason, finding new treatment approaches could be helpful.

METHOD

In this study, Imatinib was applied as a mast cell inhibitor to reduce pain crises in these patients. Seven patients resistant to hydroxyurea and folic acid treatment and who had at least four painful crises per year with hospitalization were enrolled in this study with treatment with Imatinib (100 mg, twice daily). Subsequently, the number and duration of hospitalizations, analgesic requirement, the severity of chronic pain, and changes in the hematological parameters of these patients were evaluated before and after the treatment.

RESULTS

The data showed that the total number of hospitalizations and the entire duration of hospitalizations were reduced 16 times after treatment with Imatinib, without apparent changes in hematological parameters. Also, the demand for pethidine, tramadol, and nonsteroidal anti-inflammatory drugs (NSAIDs) was reduced in all patients. The average reduction in chronic pain was over 70%.

CONCLUSION

This study demonstrates that treatment with Imatinib in patients with SCD or sickle cell anemia (SCA) may be a suitable therapeutic option for reducing painful crises.

Immunomodulation and endothelial barrier protection mediate the association between oral imatinib and mortality in hospitalised COVID-19 patients

BACKGROUND

Imatinib reduced 90-day mortality in hospitalised coronavirus disease 2019 (COVID-19) patients in a recent clinical trial, but the biological effects that cause improved clinical outcomes are unknown. We aimed to determine the biological changes elicited by imatinib in patients with COVID-19 and what baseline biological profile moderates the effect of imatinib.

METHODS

We undertook a secondary analysis of a randomised, double-blind, placebo-controlled trial of oral imatinib in hospitalised, hypoxaemic COVID-19 patients. Mediating effects of changes in plasma concentration of 25 plasma host response biomarkers on the association between randomisation group and 90-day mortality were studied by combining linear mixed effect modelling and joint modelling. Moderation of baseline biomarker concentrations was evaluated by Cox regression modelling. We identified subphenotypes using Ward's method clustering and evaluated moderation of these subphenotypes using the aforementioned method.

RESULTS

332 out of 385 participants had plasma samples available. Imatinib increased the concentration of surfactant protein D (SP-D), and decreased the concentration of interleukin-6, procalcitonin, angiopoietin (Ang)-2/Ang-1 ratio, E-selectin, tumour necrosis factor (TNF)-α, and TNF receptor I. The effect of imatinib on 90-day mortality was fully mediated by changes in these biomarkers. Cluster analysis revealed three host response subphenotypes. Mortality benefit of imatinib was only present in the subphenotype characterised by alveolar epithelial injury indicated by increased SP-D levels in the context of systemic inflammation and endothelial dysfunction (hazard ratio 0.30, 95% CI 0.10-0.92).

CONCLUSIONS

The effect of imatinib on mortality in hospitalised COVID-19 patients is mediated through modulation of innate immune responses and reversal of endothelial dysfunction, and possibly moderated by biological subphenotypes.

NF-κB Signaling and Inflammation-Drug Repurposing to Treat Inflammatory Disorders?

Simple Summary

Since its first description 35 years ago, the transcription factor NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells) has been shown to be a key mediator of immune cell responses to inflammatory mediators, oxidative stress and genotoxic injury. Dysregulated NF-κB signalling drives inflammation in inflammatory disorders such as multiple sclerosis, rheumatoid arthritis or inflammatory bowel disease. Thus, re-establishing the appropriate regulation of NF-κB activity seems like a promising approach to treat inflammatory diseases. Current anti-inflammatory drugs have many, often serious, side effects. Thus, there is an unmet clinical need for safe and effective anti-inflammatory medicines that both decrease inflammatory mediator production and enhance endogenous anti-inflammatory and prorepair pathways. So far, traditional de novo drug discovery has fallen short of satisfying this need. Drug repurposing is a cost- and time-effective alternative to de novo drug development for the identification of novel applications and has already resulted in the identification of effective anti-inflammatories in the ongoing COVID-19 pandemic. In this paper we critically review NF-κB as a potential target for the development of anti-inflammatory drugs with an emphasis on drug repurposing as a strategy to identify new approaches to treat inflammatory diseases.

Abstract

NF-κB is a central mediator of inflammation, response to DNA damage and oxidative stress. As a result of its central role in so many important cellular processes, NF-κB dysregulation has been implicated in the pathology of important human diseases. NF-κB activation causes inappropriate inflammatory responses in diseases including rheumatoid arthritis (RA) and multiple sclerosis (MS). Thus, modulation of NF-κB signaling is being widely investigated as an approach to treat chronic inflammatory diseases, autoimmunity and cancer. The emergence of COVID-19 in late 2019, the subsequent pandemic and the huge clinical burden of patients with life-threatening SARS-CoV-2 pneumonia led to a massive scramble to repurpose existing medicines to treat lung inflammation in a wide range of healthcare systems. These efforts continue and have proven to be controversial. Drug repurposing strategies are a promising alternative to de novo drug development, as they minimize drug development timelines and reduce the risk of failure due to unexpected side effects. Different experimental approaches have been applied to identify existing medicines which inhibit NF-κB that could be repurposed as anti-inflammatory drugs.

Monocytes and Macrophages Serve as Potent Prostaglandin D2 Sources during Acute, Non-Allergic Pulmonary Inflammation

Acute respiratory inflammation, most commonly resulting from bacterial or viral infection, is one of the leading causes of death and disability worldwide. The inflammatory lipid mediator prostaglandin D₂ (PGD₂) and its rate-limiting enzyme, hematopoietic PGD synthase (hPGDS), are well-known drivers of allergic pulmonary inflammation. Here, we sought to investigate the source and role of hPGDS-derived PGD₂ in acute pulmonary inflammation. Murine bronchoalveolar monocytes/macrophages from LPS- but not OVA-induced lung inflammation released significant amounts of PGD₂. Accordingly, human monocyte-derived macrophages expressed high basal levels of hPGDS and released significant levels of PGD₂ after LPS/IFN-γ, but not IL-4 stimulation. Human peripheral blood monocytes secreted significantly more PGD₂ than monocyte-derived macrophages. Using human precision-cut lung slices (PCLS), we observed that LPS/IFN-γ but not IL-4/IL-13 drive PGD₂ production in the lung. HPGDS inhibition prevented LPS-induced PGD₂ release by human monocyte-derived macrophages and PCLS. As a result of hPGDS inhibition, less TNF-α, IL-6 and IL-10 could be determined in PCLS-conditioned medium. Collectively, this dataset reflects the time-dependent release of PGD₂ by human phagocytes, highlights the importance of monocytes and macrophages as PGD₂ sources and suggests that hPGDS inhibition might be a potential therapeutic option for acute, non-allergic lung inflammation.

Selective inhibition of prostaglandin D2 biosynthesis in human mast cells to overcome need for multiple receptor antagonists: Biochemical consequences

BACKGROUND

The major mast cell prostanoid PGD₂ is targeted for therapy of asthma and other diseases, because the biological actions include bronchoconstriction, vasodilation and regulation of immune cells mediated by three different receptors. It is not known if the alternative to selectively inhibit the biosynthesis of PGD₂ affects release of other prostanoids in human mast cells.

OBJECTIVES

To determine the biochemical consequences of inhibition of the hematopoietic prostaglandin D synthase (hPGDS) PGD₂ in human mast cells.

METHODS

Four human mast cell models, LAD2, cord blood derived mast cells (CBMC), peripheral blood derived mast cells (PBMC) and human lung mast cells (HLMC), were activated by anti-IgE or ionophore A23187. Prostanoids were measured by UPLC-MS/MS.

RESULTS

All mast cells almost exclusively released PGD₂ when activated by anti-IgE or A23187. The biosynthesis was in all four cell types entirely initiated by COX-1. When pharmacologic inhibition of hPGDS abolished formation of PGD₂ , PGE₂ was detected and release of TXA₂ increased. Conversely, when the thromboxane synthase was inhibited, levels of PGD₂ increased. Adding exogenous PGH₂ confirmed predominant conversion to PGD₂ under control conditions, and increased levels of TXB₂ and PGE₂ when hPGDS was inhibited. However, PGE₂ was formed by non-enzymatic degradation.

CONCLUSIONS

Inhibition of hPGDS effectively blocks mast cell dependent PGD₂ formation. The inhibition was associated with redirected use of the intermediate PGH₂ and shunting into biosynthesis of TXA₂ . However, the levels of TXA₂ did not reach those of PGD₂ in naïve cells. It remains to determine if this diversion occurs in vivo and has clinical relevance.

Inhibition of mPGES-1 attenuates efficient resolution of acute inflammation by enhancing CX3CL1 expression

Despite the progress to understand inflammatory reactions, mechanisms causing their resolution remain poorly understood. Prostanoids, especially prostaglandin E2 (PGE2), are well-characterized mediators of inflammation. PGE2 is produced in an inducible manner in macrophages (Mϕ) by microsomal PGE2-synthase-1 (mPGES-1), with the notion that it also conveys pro-resolving properties. We aimed to characterize the role of mPGES-1 during resolution of acute, zymosan-induced peritonitis. Experimentally, we applied the mPGES-1 inhibitor compound III (CIII) once the inflammatory response was established and confirmed its potent PGE2-blocking efficacy. mPGES-1 inhibition resulted in an incomplete removal of neutrophils and a concomitant increase in monocytes and Mϕ during the resolution process. The mRNA-seq analysis identified enhanced C-X3-C motif receptor 1 (CX3CR1) expression in resident and infiltrating Mϕ upon mPGES-1 inhibition. Besides elevated Cx3cr1 expression, its ligand CX3CL1 was enriched in the peritoneal lavage of the mice, produced by epithelial cells upon mPGES-1 inhibition. CX3CL1 not only increased adhesion and survival of Mϕ but its neutralization also completely reversed elevated inflammatory cell numbers, thereby normalizing the cellular, peritoneal composition during resolution. Our data suggest that mPGES-1-derived PGE2 contributes to the resolution of inflammation by preventing CX3CL1-mediated retention of activated myeloid cells at sites of injury.

COVID-19 therapy: What weapons do we bring into battle?

Urgent treatments, in any modality, to fight SARS-CoV-2 infections are desired by society in general, by health professionals, by Estate-leaders and, mainly, by the scientific community, because one thing is certain amidst the numerous uncertainties regarding COVID-19: knowledge is the means to discover or to produce an effective treatment against this global disease. Scientists from several areas in the world are still committed to this mission, as shown by the accelerated scientific production in the first half of 2020 with over 25,000 published articles related to the new coronavirus. Three great lines of publications related to COVID-19 were identified for building this article: The first refers to knowledge production concerning the virus and pathophysiology of COVID-19; the second regards efforts to produce vaccines against SARS-CoV-2 at a speed without precedent in the history of science; the third comprehends the attempts to find a marketed drug that can be used to treat COVID-19 by drug repurposing. In this review, the drugs that have been repurposed so far are grouped according to their chemical class. Their structures will be presented to provide better understanding of their structural similarities and possible correlations with mechanisms of actions. This can help identifying anti-SARS-CoV-2 promising therapeutic agents.

International Union of Basic and Clinical Pharmacology. CIX. Differences and Similarities between Human and Rodent Prostaglandin E2 Receptors (EP1-4) and Prostacyclin Receptor (IP): Specific Roles in Pathophysiologic Conditions

Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.

Inhibiting eicosanoid degradation exerts antifibrotic effects in a pulmonary fibrosis mouse model and human tissue

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease with high 5-year mortality and few therapeutic options. Prostaglandin (PG) E₂ exhibits antifibrotic properties and is reduced in bronchoalveolar lavage from patients with IPF. 15-Prostaglandin dehydrogenase (15-PGDH) is the key enzyme in PGE₂ metabolism under the control of TGF-β and microRNA 218.

OBJECTIVE

We sought to investigate the expression of 15-PGDH in IPF and the therapeutic potential of a specific inhibitor of this enzyme in a mouse model and human tissue.

METHODS

In vitro studies, including fibrocyte differentiation, regulation of 15-PGDH, RT-PCR, and Western blot, were performed using peripheral blood from healthy donors and patients with IPF and A549 cells. Immunohistochemistry, immunofluorescence, 15-PGDH activity assays, and in situ hybridization as well as ex vivo IPF tissue culture experiments were done using healthy donor and IPF lungs. Therapeutic effects of 15-PGDH inhibition were studied in the bleomycin mouse model of pulmonary fibrosis.

RESULTS

We demonstrate that 15-PGDH shows areas of increased expression in patients with IPF. Inhibition of this enzyme increases PGE₂ levels and reduces collagen production in IPF precision cut lung slices and in the bleomycin model. Inhibitor-treated mice show amelioration of lung function, decreased alveolar epithelial cell apoptosis, and fibroblast proliferation. Pulmonary fibrocyte accumulation is also decreased by inhibitor treatment in mice, similar to PGE₂ that inhibits fibrocyte differentiation from blood of healthy donors and patients with IPF. Finally, microRNA 218-5p, which is downregulated in patients with IPF, suppressed 15-PGDH expression in vivo and in vitro.

CONCLUSIONS

These findings highlight the role of 15-PGDH in IPF and suggest 15-PGDH inhibition as a promising therapeutic approach.