Targeting M2 Macrophages with a Novel NADPH Oxidase Inhibitor

ROS in cancer cells play a key role in pathways regulating cell death, stemness maintenance, and metabolic reprogramming, all of which have been implicated in resistance to chemo/ immunotherapy. Adjusting ROS levels to reverse the resistance of cancer cells without impairing normal cell functions is a new therapeutic avenue. In this paper, we describe new inhibitors of NADPH oxidase (NOX), a key enzyme in many cells of the tumor microenvironment. The first inhibitor, called Nanoshutter-1, NS1, decreased the level of tumor-promoting "M2" macrophages differentiated from human blood monocytes. NS1 disrupted the active NADPH oxidase-2 (NOX2) complex at the membrane and in the mitochondria of the macrophages, as shown by confocal microscopy. As one of the characteristics of tumor invasion is hypoxia, we tested whether NS1 would affect vascular reactivity by reducing ROS or NO levels in wire and pressure myograph experiments on isolated blood vessels. The results show that NS1 vasodilated blood vessels and would likely reduce hypoxia. Finally, as both NOX2 and NOX4 are key proteins in tumors and their microenvironment, we investigated whether NS1 would probe these proteins differently. Models of NOX2 and NOX4 were generated by homology modeling, showing structural differences at their C-terminal NADPH site, in particular in their last Phe. Thus, the NADPH site presents an unexploited chemical space for addressing ligand specificity, which we exploited to design a novel NOX2-specific inhibitor targeting variable NOX2 residues. With the proper smart vehicle to target specific cells of the microenvironment as TAMs, NOX2-specific inhibitors could open the way to new precision therapies.

Design, Synthesis, and Evaluation of Novel Pyruvate Dehydrogenase Kinase Inhibitors

AIMS

The present work describes the synthesis and the biological evaluation of novel compounds acting as pyruvate dehydrogenase kinase (PDK) inhibitors. These drugs should become a new therapeutic approach for the treatment of pathologies improved by the control of the blood lactate level.

METHODS

Four series of compounds belonging to N-(4-(N-alkyl/aralkylsulfamoyl)phenyl)-2- methylpropanamides and 1,2,4-benzothiadiazine 1,1-dioxides were prepared and evaluated as PDK inhibitors.

RESULTS

The newly synthesized N-(4-(N-alkyl/aralkylsulfamoyl)phenyl)-2-methylpropanamides structurally related to previously reported reference compounds 4 and 5 were found to be potent PDK inhibitors (i.e. 10d: IC₅₀ = 41 nM). 1,2,4-Benzothiadiazine 1,1-dioxides carrying a (methyl/ trifluoromethyl)-propanamide moiety at the 6-position were also designed as conformationally restricted ring-closed analogues of N-(4-(N-alkyl/aralkylsulfamoyl)phenyl)-2-hydroxy-2-methylpropanamides. Most of them were found to be less potent than their ring-opened analogues. Interestingly, the best choice of hydrocarbon side chain at the 4-position was the benzyl chain, providing 11c (IC₅₀ = 3.6 μM) belonging to "unsaturated" 1,2,4-benzothiadiazine 1,1-dioxides, and 12c (IC₅₀ = 0.5 μM) belonging to "saturated' 1,2,4-benzothiadiazine 1,1-dioxides.

CONCLUSION

This work showed that ring-closed analogues of N-(4-(N-alkyl/aralkylsulfamoyl) phenyl)- 2-hydroxy-2-methylpropanamides were less active as PDK inhibitors than their corresponding ring-opened analogues. However, the introduction of a bulkier substituent at the 4-position of the 1,2,4-benzothiadiazine 1,1-dioxide core structure, such as a benzyl or a phenethyl side chain, was allowed, opening the way to the design of new inhibitors with improved PDK inhibitory activity.

Neuropeptides, New Ligands of SARS-CoV-2 Nucleoprotein, a Potential Link between Replication, Inflammation and Neurotransmission

This work identifies new ligands of the nucleoprotein N of SARS-CoV-2 by in silico screening, which used a new model of N, built from an Alphafold model refined by molecular dynamic simulations. The ligands were neuropeptides, such as substance P (1-7) and enkephalin, bound at a large site of the C-terminal or associated with the N-terminal β-sheet. The BA4 and BA5 Omicron variants of N also exhibited a large site as in wt N, and an increased flexibility of the BA5 variant, enabling substance P binding. The binding sites of some ligands deduced from modeling in wt N were assessed by mutation studies in surface plasmon resonance experiments. Dynamic light scattering showed that the ligands impeded RNA binding to N, which likely inhibited replication. We suggest that the physiological role of these neuropeptides in neurotransmission, pain and vasodilation for cholecystokinin and substance P could be altered by binding to N. We speculate that N may link between viral replication and multiple pathways leading to long COVID-19 symptoms. Therefore, N may constitute a "danger hub" that needs to be inhibited, even at high cost for the host. Antivirals targeted to N may therefore reduce the risk of brain fog and stroke, and improve patients' health.

Distinction between 2'- and 3'-Phosphate Isomers of a Fluorescent NADPH Analogue Led to Strong Inhibition of Cancer Cells Migration

Specific inhibition of NADPH oxidases (NOX) and NO-synthases (NOS), two enzymes associated with redox stress in tumor cells, has aroused great pharmacological interest. Here, we show how these enzymes distinguish between isomeric 2′- and 3′-phosphate derivatives, a difference used to improve the specificity of inhibition by isolated 2′- and 3′-phosphate isomers of our NADPH analogue NS1. Both isomers become fluorescent upon binding to their target proteins as observed by in vitro assay and in vivo imaging. The 2′-phosphate isomer of NS1 exerted more pronounced effects on NOS and NOX-dependent physiological responses than the 3′-phosphate isomer did. Docking and molecular dynamics simulations explain this specificity at the level of the NADPH site of NOX and NOS, where conserved arginine residues distinguished between the 2′-phosphate over the 3′-phosphate group, in favor of the 2′-phosphate.

Design of Light-Sensitive Triggers for Endothelial NO-Synthase Activation

A specific light trigger for activating endothelial Nitric Oxide-Synthase (eNOS) in real time would be of unique value to decipher cellular events associated with eNOS activation or to generate on demand cytotoxic levels of NO at specific sites for cancer research. We previously developed novel tools called nanotriggers (NT), which recognized constitutive NO-synthase, eNOS or neuronal NOS (nNOS), mainly via their 2’ phosphate group which is also present in NADPH in its binding site. Laser excitation of NT1 bound to eNOS triggered recombinant NOS activity and released NO. We recently generated new NTs carrying a 2’ or 3’ carboxylate group or two 2’ and 3’ carboxylate moieties replacing the 2’ phosphate group of NADPH. Among these new NT, only the 3’ carboxylate derivative released NO from endothelial cells upon laser activation. Here, Molecular Dynamics (MD) simulations showed that the 3’ carboxylate NT formed a folded structure with a hydrophobic hub, inducing a good stacking on FAD that likely drove efficient activation of nNOS. This NT also carried an additional small charged group which increased binding to e/nNOS; fluorescence measurements determined a 20-fold improved affinity upon binding to nNOS as compared to NT1 affinity. To gain in specificity for eNOS, we augmented a previous NT with a “hook” targeting variable residues in the NADPH site of eNOS. We discuss the potential of exploiting the chemical diversity within the NADPH site of eNOS for reversal of endothelial dysfunction in cells and for controlled generation of cytotoxic NO-derived species in cancer tissues.

Identification and pharmacological characterization of succinate receptor agonists

BACKGROUND AND PURPOSE

The succinate receptor (formerly GPR91 or SUCNR1) is described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho)physiological processes, the function of succinate receptors has remained ill-defined because no pharmacological tools were available. We report on the discovery of the first family of potent synthetic agonists.

EXPERIMENTAL APPROACH

We screened a library of succinate analogues and analysed their activity on succinate receptors. Also, we modelled a pharmacophore and a binding site for this receptor. New agonists were identified based on the information provided by these two approaches. Their activity was studied in various bioassays, including measurement of cAMP levels, [Ca²⁺ ]_i mobilization, TGF-α shedding and recruitment of arrestin 3. The in vivo effects of activating succinate receptors with these new agonists was evaluated on rat BP.

KEY RESULTS

We identified cis-epoxysuccinic acid and cis-1,2-cyclopropanedicarboxylic acid as agonists with an efficacy similar to that of succinic acid. Interestingly, cis-epoxysuccinic acid was 10- to 20-fold more potent than succinic acid on succinate receptors. For example, cis-epoxysuccinic acid reduced cAMP levels with a pEC₅₀  = 5.57 ± 0.02 (EC₅₀  = 2.7 μM), compared with succinate pEC₅₀  = 4.54 ± 0.08 (EC₅₀  = 29 μM). The rank order of potency of the three agonists was the same in all in vitro assays. Both cis-epoxysuccinic and cis-1,2-cyclopropanedicarboxylic acid were as potent as succinate in increasing rat BP.

CONCLUSIONS AND IMPLICATIONS

We describe new agonists at succinate receptors that should facilitate further research on this understudied receptor.

Structural Insights into 5-HT1A/D4 Selectivity of WAY-100635 Analogues: Molecular Modeling, Synthesis, and in Vitro Binding

The resurgence of interest in 5-HT1A receptors as a therapeutic target requires the existence of highly selective 5-HT1A ligands. To date, WAY-100635 has been the prototypical antagonist of these receptors. However, this compound also has significant affinity for and activity at D4 dopamine receptors. In this context, this work was aimed at better understanding the 5-HT1A/D4 selectivity of WAY-100635 and analogues from a structural point of view. In silico investigations revealed two key interactions for the 5-HT1A/D4 selectivity of WAY-100635 and analogues. First, a hydrogen bond only found with the Ser 7.36 of D4 receptor appeared to be the key for a higher D4 affinity for newly synthesized aza analogues. The role of Ser 7.36 was confirmed as the affinity of aza analogues for the mutant D4 receptor S7.36A was reduced. Then, the formation of another hydrogen bond with the conserved Ser 5.42 residue appeared to be also critical for D4 binding.

Enhancing a CH-π Interaction to Increase the Affinity for 5-HT1A Receptors

An electrostatic interaction related to a favorable position of the distal phenyl ring and a phenylalanine residue in the binding pocket would explain the higher 5-HT1A affinity of a 4-phenyl-1,2,3,6-tetrahydropyridine (THP) analogue compared to the corresponding 4-phenylpiperazine analogue. To explore a possible reinforcement of this interaction to increase the affinity for 5-HT1A receptors, different 4-substituted-phenyl analogues were synthesized and tested. The most important increase of affinity is obtained with two electron-donating methyl groups in positions 3 and 5.

Lung deposition and pharmacokinetics of nebulized cyclosporine in lung transplant patients

BACKGROUND

Inhaled cyclosporine (CsA) is being investigated as a prophylaxis for lung transplant rejection. Lung deposition and systemic exposure of nebulized CsA in lung transplant patients was evaluated as part of the Phase 3 cyclosporine inhalation solution (CIS) trial (CYCLIST).

METHODS

Ten patients received 300 mg of CIS (62.5 mg/mL CsA in propylene glycol) admixed with 148 MBq of Tc-DTPA (technetium-99m bound to diethylenetriaminepentaacetic acid) administered using a Sidestream(®) disposable jet nebulizer. Deposition was assessed using a dual-headed gamma camera. Blood samples were collected over a 24-hr time period after aerosol dosing and analyzed for CsA levels. A pharmacokinetic analysis of the resulting blood concentration versus time profiles was performed.

RESULTS

The average total deposited dose was 53.7 ± 12.7 mg. Average pulmonary dose was 31.8 ± 16.3 mg, and stomach dose averaged 15.5 ± 11.1 mg. Device performance was consistent, with breathing maneuvers influencing dose variation. Predose coaching with five of 10 patients reduced stomach deposition (22.6 ± 11.2 vs. 8.3 ± 5.2 mg; p=0.03). Blood concentrations declined quickly from a maximum of 372 ± 140 ng/mL to 15.3 ± 9.7 ng/mL at 24 hr post dose. Levels of AUC(0-24) [area under the concentration vs. time curve from 0 to 24 hr] averaged 1,493 ± 746 ng hr/mL. On a three times per week dose regimen, this represents <5% of the weekly systemic exposure of twice per day oral administration.

CONCLUSIONS

Substantial doses of CsA can be delivered to the lungs of lung transplant patients by inhaled aerosol. Systemic levels are small relative to typical oral CsA administration.

Ion-channel modulators: more diversity than previously thought

Ion-channel function can be modified in various ways. For example, numerous studies have shown that currents through voltage-gated ion channels are affected by pore block or modification of voltage dependence of activation/inactivation. Recent experiments performed on various ion channels show that allosteric modulation is an important mechanism for affecting channel function. For instance, in K(Ca)2 (formerly SK) channels, the prototypic "blocker" apamin prevents conduction by an allosteric mechanism, while TRPV1 channels are prevented from closing by a tarantula toxin, DkTx, through an interaction with residues located away from the selectivity filter. The recent evidence, therefore, suggests that in several ion channels, the region around the outer mouth of the pore is rich in binding sites and could be exploited therapeutically. These discoveries also suggest that the pharmacological vocabulary should be adapted to define these various actions.

Interaction of clozapine and its nitrenium ion with rat D2 dopamine receptors: in vitro binding and computational study

The interaction of diazepine analogues like clozapine or olanzapine with D2 receptor was greatly affected by a mixture of HRP/H(2)O(2) known to induce the formation of nitrenium ion. Unlike diazepine derivatives, the oxidative mixture had low impact on the affinity of oxa- and thiazepine derivatives such as loxapine, clothiapine or JL13 for the D2 receptor. Molecular docking simulations revealed a huge difference between the mode of interaction of clozapine nitrenium ion and the parent drug. Electronic and geometric changes of the tricyclic ring system caused by the oxidation appeared to prevent the compound finding the correct binding mode and could therefore explain the difference observed in binding affinities.

Dexrazoxane protects the heart from acute doxorubicin-induced QT prolongation: a key role for I(Ks)

INTRODUCTION

Doxorubicin, an anthracycline widely used in the treatment of a broad range of tumours, causes acute QT prolongation. Dexrazoxane has been shown to prevent the QT prolongation induced by another anthracycline, epirubicin, but has not yet been reported to prevent that induced by doxorubicin. Thus, the present study was designed to test whether the acute QT effects induced by doxorubicin could be blocked by dexrazoxane and to explore the mechanism. Results were compared with those obtained with a reference human ether-a-go-go (hERG) channel blocker, moxifloxacin.

METHODS

The effects of moxifloxacin (100 microM) and doxorubicin (30 microM), with or without dexrazoxane (from 3 to 30 microM), have been evaluated on the QTc interval in guinea-pig isolated hearts and on I(Kr) (rapid component of the delayed rectifier current) and I(Ks) (slow component of the delayed rectifier current) currents stably expressed in human embryonic kidney 293 cells.

RESULTS

Moxifloxacin (100 microM), a potent hERG blocker, prolonged QTc by 22%, and this effect was not prevented by dexrazoxane. Doxorubicin (30 microM) also prolonged QTc by 13%, did not significantly block hERG channels and specifically inhibited I(Ks) (IC(50): 4.78 microM). Dexrazoxane significantly reduced the doxorubicin-induced QTc prolongation and prevented doxorubicin-induced inhibition of I(Ks).

CONCLUSION AND IMPLICATIONS

Doxorubicin acutely prolonged the QT interval in guinea-pig heart by selective I(Ks) blockade. This effect was prevented by dexrazoxane. This result is important because it illustrates the danger of neglecting I(Ks) in favour of hERG screening alone, for early preclinical testing for possible induction of torsade de pointes.

Synthesis and Radioligand Binding Studies of Bis-isoquinolinium Derivatives as Small Conductance Ca2+-Activated K+ Channel Blockers

Starting from the scaffold of N-methyllaudanosine and N-methylnoscapine, which are known small conductance Ca2+-activated K+ channel blockers, original bis-isoquinolinium derivatives were synthezised and evaluated using binding studies, electrophysiology, and molecular modeling. These quaternary compounds are powerful blockers, and the most active ones have 10 times more affinity for the channels than dequalinium. The unsubstituted compounds possess a weaker affinity than the analogues having a 6,7-dimethoxy- or a 6,7,8-trimethoxy substitution. The length of the linker has no influence in the alkane derivatives. In relation to the xylene derivatives, the affinities are higher for the ortho and meta isomers. These results are well corroborated by a molecular modeling study. Finally, the most effective compounds have been tested in electrophysiological experiments on midbrain dopaminergic neurons and demonstrate the blocking potential of the apamin-sensitive after-hyperpolarization.

Amiodarone-induced bone marrow granulomas

Amiodarone hydrochloride, a class III antiarrhythmic agent used to treat supraventricular and ventricular cardiac dysrhythmias. In this report we describe two patients receiving amiodarone for atrial fibrillation who underwent bone marrow biopsies to investigate paraproteinaemia (case 1) or severe thrombocytopenia (case 2). Multiple bone marrow granulomas were found in both patients, without evidence of any other cause. In both patients the granulomas disappeared after amiodarone withdrawal, suggesting a direct association.

Splenic sepsis in sickle cell disease

We describe two patients with sickle cell disease (SCD) who developed infections situated in the spleen. One patient had a splenic abscess and there was strong clinical evidence for an infected splenic infarct in the second patient. SCD predisposes to splenic infection because of functional hyposplenism, defective phagocyte function and splenic infarction. Splenic infections can occur in patients who might be considered to have an absent spleen and the diagnosis of splenic abscess should be considered in individuals with SCD who present with fever and abdominal pain.

Physicians' attitudes to the autopsy

The overall autopsy rate (excluding coroner's autopsies) at a large teaching district general hospital over a four year period was 16.5%, but individual rates for ten general physicians varied from 5% to 35%. During this period, the mean autopsy rate for general medicine (14%) was significantly lower than rates for cardiology (21%), geriatrics (23%) and paediatrics (36%), but similar to general surgery (13%). Autopsies were widely perceived as being of benefit to education and research, but physicians were often unaware of their value for confirming the diagnosis and for clinical audit, and over-estimated their actual autopsy rates on average by 50%. High rates (18-30%) were associated with consultants who had a definite policy regarding autopsies and had made this clear to their junior staff. Low rates (6-10%) obtained where there was no consultant policy on autopsies, and were frequently attributed by the consultant physicians to failure by their junior staff. Physicians should be more aware of the value of autopsies, and should take responsibility for increasing and monitoring autopsy requests to improve clinical audit, quality assurance and medical education.

Are granisetron and ondansetron equivalent in the clinic?

There are no published direct trials of granisetron vs. ondansetron. Difficulties exist in comparing reported trials because of differences in methodology, especially in response criteria. In this review, a comparison is made between ondansetron and granisetron by recalculating the complete response criterion for granisetron, standardising it against that in the ondansetron programme (i.e. no vomiting). Weighted means have been calculated for three areas of study. Against cisplatin-induced emesis the (weighted) mean percentage of complete responders were calculated at 64% (range 49-77%) for granisetron and 49% (range 40-55%) for ondansetron. Against moderately emetogenic stimuli, the response rates were 76% (range 68-80%) and 73% (range 60-87%) respectively. For fractionated chemotherapy the response rates were 57% and 27% for granisetron and ondansetron respectively. Although not shown by formal statistical analysis, these results suggest that a clinical advantage for granisetron may exist.

Prognostic factors in stage I non-seminomatous germ-cell testicular tumors managed by orchiectomy and surveillance: implications for adjuvant chemotherapy

Between February 1979 and March 1985, 126 patients with clinical stage I non-seminomatous germ-cell testicular tumors were entered into a surveillance study after orchiectomy. Of this group, 36 (28%) have relapsed. The prognostic significance of 13 clinical, histopathologic, and biochemical factors has been analyzed. Vascular invasion and lymphatic invasion (LI) within the primary tumor, histology, and involvement of the epididymis and rete testis were significantly associated with an increased risk of relapse. However, multiple regression analysis showed that only histology and LI were significant, independent prognostic factors. These findings provide the basis for the consideration of adjuvant chemotherapy for patients with apparent clinical stage I testicular non-seminoma who are at high risk of harboring occult metastases.

Potential errors in the estimation of coronary arterial stenosis from clinical arteriography with reference to the shape of the coronary arterial lumen

Underestimation of coronary arterial stenosis at clinical arteriography has been explained by inadequate radiological views of crescentic or slit-shaped lumens. Postmortem perfusion-fixation of the coronary arteries at physiological pressures shows that most stenotic lesions result in circular, elliptical, or D-shaped lumens. Crescentic lumens in fully distended vessels are associated only with acute mural thrombus projecting into the lumen or with massive intra-intimal thrombus and plaque fissuring. Elliptical and D-shaped lumens, however, adequately explain the clinically observed phenomenon that some stenotic lesions can be seen only in one x-ray plane and not in another. It is no longer correct to postulate a crescentic or slit-like lumen. Furthermore, not only can elliptical and D-shaped lumens result in underestimation of stenosis, they may also result in serious overestimation. Lumens need only to deviate slightly from being circular for error to be introduced into the estimation of stenosis by currently used methods. The calculation of percentage stenosis from densitometric measurements or from computerised reconstruction of the arterial lumen is, however, more accurate.