Diacetyloxyl derivatization of the fibroblast growth factor inhibitor dobesilate enhances its anti-inflammatory, anti-angiogenic and anti-tumoral activities

Study protocol for assessment of the efficacy of calcium dobesilate versus placebo on SARS-CoV-2 viral load in outpatients with COVID-19 (CADOVID study): a randomised, placebo-controlled, double-blind, monocentric phase II trial

INTRODUCTION

SARS-CoV-2 mainly infects respiratory endothelial cells, which is facilitated through its spike protein binding to heparan sulphate. Calcium dobesilate (CaD) is a well-established, widely available vasoactive and angioprotective drug interacting with heparan sulphate, with the potential to interfere with the uptake of SARS-CoV-2 by epithelial cells. The CADOVID trial aims to evaluate the efficacy and safety of CaD in reducing the SARS-CoV-2 viral load in non-hospitalised adult patients diagnosed with COVID-19, confirmed by a positive SARS-CoV-2 PCR, including its efficacy to reduce the impact of persistent COVID-19 symptoms.

METHODS AND ANALYSIS

This is a randomised, placebo-controlled, double-blind, monocentric phase II trial. Enrolment began in July 2022. A total of 74 adult patients will be randomly allocated to the CaD arm or the placebo group with a 1:1 ratio, respectively. Participants in the intervention arm will receive two capsules of CaD 500 mg two times per day and the placebo arm will receive two matching capsules of mannitol 312.5 mg two times per day, with a treatment period of 7 days for both arms, followed by a 77-day observational period without treatment administration. Participants will be asked to complete secured online questionnaires using their personal smartphone or other electronic device. These include a COVID-19 questionnaire (assessing symptoms, temperature measurement, reporting of concomitant medication and adverse events), a COVID-19 persistent symptoms' questionnaire and the Short Form 12-Item (SF-12) survey. SARS-CoV-2 PCR testing will be performed on nasopharyngeal swabs collected on days 1, 4, 8 and 21. The primary endpoint is the reduction from baseline of SARS-CoV-2 viral load determined by RT-PCR at day 4.

ETHICS AND DISSEMINATION

This trial has received approval by the Geneva Regional Research Ethics Committee (2022-00613) and Swissmedic (701339). Dissemination of results will be through presentations at scientific conferences and publication in scientific journals.

TRIAL REGISTRATION NUMBER

NCT05305508; Clinicaltrials.gov; Swiss National Clinical Portal Registry (SNCTP 000004938).

Calcium dobesilate reduces SARS-CoV-2 entry into endothelial cells by inhibiting virus binding to heparan sulfate

Recent reports demonstrate that SARS-CoV-2 utilizes cell surface heparan sulfate as an attachment factor to facilitate the initial interaction with host cells. Heparan sulfate interacts with the receptor binding domain of SARS-CoV-2 spike glycoprotein, and blocking this interaction can decrease cell infection. We and others reported recently that the family of compounds of 2,5-dihydroxyphenylic acid interferes with the binding of the positively charged groove in growth factor molecules to negatively charged cell surface heparan sulfate. We hypothesized that Calcium Dobesilate (CaD)-calcium salt of 2,5-dihydroxyphenylic acid-may also interfere with the binding of SARS-CoV-2 spike protein to heparan sulfate. Using lentiviral SARS-CoV-2 spike protein pseudotyped particles we show that CaD could significantly reduce pseudovirus uptake into endothelial cells. On the contrary, CaD did not affect cell infection with VSVG-expressing lentivirus. CaD could also prevent retention of SARS-CoV-2 spike protein in ex vivo perfused mouse kidney. Using microfluidic culture of endothelial cells under flow, we show that CaD prevents spike protein interaction with heparan sulfate glycocalyx. Since CaD has no adverse side effects and is approved in humans for other medical indications, our findings can rapidly translate into clinical studies.

Calcium Dobesilate Modulates PKCδ-NADPH Oxidase- MAPK-NF-κB Signaling Pathway to Reduce CD14, TLR4, and MMP9 Expression during Monocyte-to-Macrophage Differentiation: Potential Therapeutic Implications for Atherosclerosis

Monocyte-to-macrophage differentiation results in the secretion of various inflammatory mediators and oxidative stress molecules necessary for atherosclerosis pathogenesis. Consequently, this differentiation represents a potential clinical target in atherosclerosis. Calcium dobesilate (CaD), an established vasoactive and angioprotective drug in experimental models of diabetic microvascular complications reduces oxidative stress and inhibits inflammation via diverse molecular targets; however, its effect on monocytes/macrophages is poorly understood. In this study, we investigated the anti-inflammatory mechanism of CaD during phorbol 12-myristate 13-acetate (PMA)-induced monocyte-to-macrophage differentiation in in vitro models of sepsis (LPS) and hyperglycemia, using THP-1 monocytic cell line. CaD significantly suppressed CD14, TLR4, and MMP9 expression and activity, lowering pro-inflammatory mediators, such as IL1β, TNFα, and MCP-1. The effects of CaD translated through to studies on primary human macrophages. CaD inhibited reactive oxygen species (ROS) generation, PKCδ, MAPK (ERK1/2 and p38) phosphorylation, NOX2/p47phox expression, and membrane translocation. We used hydrogen peroxide (H2O2) to mimic oxidative stress, demonstrating that CaD suppressed PKCδ activation via its ROS-scavenging properties. Taken together, we demonstrate for the first time that CaD suppresses CD14, TLR4, MMP9, and signature pro-inflammatory cytokines, in human macrophages, via the downregulation of PKCδ/NADPH oxidase/ROS/MAPK/NF-κB-dependent signaling pathways. Our data present novel mechanisms of how CaD alleviates metabolic and infectious inflammation.

Luminescent Platinum(II) Complexes with Bidentate Diacetylide Ligands: Structures, Photophysical Properties and Application Studies

A series of platinum(II) complexes supported by terphenyl diacetylide as well as diimine or bis-N-heterocyclic carbene (NHC) ligands have been prepared. The diacetylide ligands adopt a cis coordination mode featuring non-planar terphenyl moieties as revealed by X-ray crystallographic analyses. The electrochemical, photophysical and photochemical properties of these platinum(II) complexes have been investigated. These platinum(II) diimine complexes show broad emission with peak maxima from 566 nm to 706 nm, with two of them having emission quantum yields >60% and lifetimes <2 μs in solutions at room temperature, whereas the platinum(II) diacetylide complexes having bis-N-heterocyclic carbene instead of diimine ligand display photoluminescence with quantum yields of up to 28% in solutions and excited state lifetimes of up to 62 μs at room temperature. Application studies revealed that one of the complexes can catalyze photoinduced aerobic dehydrogenation of alcohols and alkenes, and a relatively non-toxic water-soluble Pt(II) complex displays anti-angiogenic activity.

The Role of Prostaglandins in Different Types of Cancer

The prostaglandins constitute a family of lipids of 20 carbon atoms that derive from polyunsaturated fatty acids such as arachidonic acid. Traditionally, prostaglandins have been linked to inflammation, female reproductive cycle, vasodilation, or bronchodilator/bronchoconstriction. Recent studies have highlighted the involvement of these lipids in cancer. In this review, existing information on the prostaglandins associated with different types of cancer and the advances related to the potential use of them in neoplasm therapies have been analyzed. We can conclude that the effect of prostaglandins depends on multiple factors, such as the target tissue, their plasma concentration, and the prostaglandin subtype, among others. Prostaglandin D2 (PGD₂) seems to hinder tumor progression, while prostaglandin E2 (PGE₂) and prostaglandin F2 alpha (PGF_2α) seem to provide greater tumor progression and aggressiveness. However, more studies are needed to determine the role of prostaglandin I2 (PGI₂) and prostaglandin J2 (PGJ₂) in cancer due to the conflicting data obtained. On the other hand, the use of different NSAIDs (non-steroidal anti-inflammatory drugs), especially those selective of COX-2 (cyclooxygenase 2), could have a crucial role in the fight against different neoplasms, either as prophylaxis or as an adjuvant treatment. In addition, multiple targets, related to the action of prostaglandins on the intracellular signaling pathways that are involved in cancer, have been discovered. Thus, in depth research about the prostaglandins involved in different cancer and the different targets modulated by them, as well as their role in the tumor microenvironment and the immune response, is necessary to obtain better therapeutic tools to fight cancer.

Calcium dobesilate reduces VEGF signaling by interfering with heparan sulfate binding site and protects from vascular complications in diabetic mice

Inhibiting vascular endothelial growth factor (VEGF) is a therapeutic option in diabetic microangiopathy. However, VEGF is needed at physiological concentrations to maintain glomerular integrity; complete VEGF blockade has deleterious effects on glomerular structure and function. Anti-VEGF therapy in diabetes raises the challenge of reducing VEGF-induced pathology without accelerating endothelial cell injury. Heparan sulfate (HS) act as a co-receptor for VEGF. Calcium dobesilate (CaD) is a small molecule with vasoprotective properties that has been used for the treatment of diabetic microangiopathy. Preliminary evidence suggests that CaD interferes with HS binding sites of fibroblast growth factor. We therefore tested the hypotheses that (1) CaD inhibits VEGF signaling in endothelial cells, (2) that this effect is mediated via interference between CaD and HS, and (3) that CaD ameliorates diabetic nephropathy in a streptozotocin-induced diabetic mouse model by VEGF inhibition. We found that CaD significantly inhibited VEGF₁₆₅-induced endothelial cell migration, proliferation, and permeability. CaD significantly inhibited VEGF₁₆₅-induced phosphorylation of VEGFR-2 and suppressed the activity of VEGFR-2 mediated signaling cascades. The effects of CaD in vitro were abrogated by heparin, suggesting the involvement of heparin-like domain in the interaction with CaD. In addition, VEGF₁₂₁, an isoform which does not bind to heparin, was not inhibited by CaD. Using the proximity ligation approach, we detected inhibition of interaction in situ between HS and VEGF and between VEGF and VEGFR-2. Moreover, CaD reduced VEGF signaling in mice diabetic kidneys and ameliorated diabetic nephropathy and neuropathy, suggesting CaD as a VEGF inhibitor without the negative effects of complete VEGF blockade and therefore could be useful as a strategy in treating diabetic nephropathy.

Heparin Binding Proteins as Therapeutic Target: An Historical Account and Current Trends

The polyanionic nature and the ability to interact with proteins with different affinities are properties of sulfated glycosaminoglycans (GAGs) that determine their biological function. In designing drugs affecting the interaction of proteins with GAGs the challenge has been to generate agents with high binding specificity. The example to emulated has been a heparin-derived pentasaccharide that binds to antithrombin-III with high affinity. However, the portability of this model to other biological situations is questioned on several accounts. Because of their structural flexibility, oligosaccharides with different sulfation and uronic acid conformation can display the same binding proficiency to different proteins and produce comparable biological effects. This circumstance represents a formidable obstacle to the design of drugs based on the heparin scaffold. The conceptual framework discussed in this article is that through a direct intervention on the heparin-binding functionality of proteins is possible to achieve a high degree of action specificity. This objective is currently pursued through two strategies. The first makes use of small molecules for which in the text we provide examples from past and present literature concerning angiogenic factors and enzymes. The second approach entails the mutagenesis of the GAG-binding site of proteins as a means to generate a new class of biologics of therapeutic interest.

Haemostatic agent etamsylate in vitro and in vivo antagonizes anti-coagulant activity of heparin

Etamsylate is indicated for several anti-hemorrhagic indications in human and veterinary medicine. However, etamsylate has been shown to be effective only in specific hemorrhagic situations. Furthermore, mechanism of action of etamsylate is not known but recent research has shown its ability to inhibit heparin binding to several growth factors. We have evaluated the ability of etamsylate to interfere with the activities of heparin. Effects of etamsylate on vasodilatory activity of heparin were evaluated in rat aortic segments. Influence of etamsylate on anticoagulant activity of heparin was evaluated in vitro by determining prothrombin (PT) time and activated partial thromboplastin time (aPTT) in dog blood and in vivo by determining the interference of systemic and topical etamsylate on heparin-induced extension in bleeding time (BT) in rats. Despite failing to inhibit heparin-induced vasodilation of rat aorta, etamsylate significantly reduced the increase in aPTT caused by heparin (+30.4 ± 6.7% vs. +15.0 ± 2.8% for etamsylate at 100 µM, P < 0.05). Etamsylate also antagonized the anticoagulant effects driven by heparin in vivo since prevented the heparin-induced increase in BT when systemically (i.p.) administered (+94.6 ± 7.5% vs. +57.9 ± 9.2% at 10 mg/kg, P < 0.05, vs. +22.2 ± 16.8% at 30 mg/kg, P < 0.01). Additionally, topically applied etamsylate (125 mg/ml) significantly reduced heparin-induced BT increase (+102.5 ± 3.2% vs. +54.0 ± 5.8%, P < 0.01). These evidences show a pharmacological interference by etamsylate on heparin activities antagonizing pro-hemorrhagic effects of heparin in vitro and in vivo without inhibiting its vasodilatory properties. This ability could help to explain pharmacological effects of etamsylate and proposes its role for reversing pro-hemorrhagic states.

Improvement in the signs and symptoms of dry eye disease with dobesilate eye drops

BACKGROUND

Dry eye is a multifactor disease of the tear film and ocular surface that substantially affects quality of life.

CASE PRESENTATION

Dobesilate administered as eye drops was well tolerated and effective in treating both the objective signs and subjective symptoms of dry eye disease in this 2-week study.

CONCLUSION

To the best of our knowledge, this is the first clinical report of using dobesilate in eye drops. Dobesilate may provide a novel approach to treating drying diseases of the eye.