ABSTRACT
The inflammatory protease caspase-1 is associated with the release of cytokines. An excessive number of cytokines (a "cytokine storm") is a dangerous consequence of COVID-19 infection and has been indicated as being among the causes of death by COVID-19. The anti-inflammatory drug colchicine (which is reported in the literature to be a caspase-1 inhibitor) and the corticosteroid drugs, dexamethasone and methylprednisolone, are among the most effective active compounds for COVID-19 treatment. The SERM raloxifene has also been used as a repurposed drug in COVID-19 therapy. In this study, inhibition of caspase-1 by these four compounds was analyzed using computational methods. Our aim was to see if the inhibition of caspase-1, an important biomolecule in the inflammatory response that triggers cytokine release, could shed light on how these drugs help to alleviate excessive cytokine production. We also measured the antioxidant activities of dexamethasone and colchicine when scavenging the superoxide radical using cyclic voltammetry methods. The experimental findings are associated with caspase-1 active site affinity towards these compounds. In evaluating our computational and experimental results, we here formulate a mechanism for caspase-1 inhibition by these drugs, which involves the active site amino acid Cys285 residue and is mediated by a transfer of protons, involving His237 and Ser339. It is proposed that the molecular moiety targeted by all of these drugs is a carbonyl group which establishes a S(Cys285)-C(carbonyl) covalent bond.
Subject(s)
Anti-Inflammatory Agents/pharmacology , COVID-19 Drug Treatment , Caspase 1/drug effects , Caspase Inhibitors/pharmacology , Coronavirus 3C Proteases/drug effects , Anti-Inflammatory Agents/chemistry , COVID-19/metabolism , Caspase 1/chemistry , Caspase 1/metabolism , Caspase Inhibitors/chemistry , Colchicine/chemistry , Colchicine/pharmacology , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , Coronavirus 3C Proteases/metabolism , Dexamethasone/pharmacology , Humans , Models, Molecular , Molecular Docking Simulation , Pentacyclic Triterpenes/pharmacology , Protein Interaction Domains and Motifs , Raloxifene Hydrochloride/chemistry , Raloxifene Hydrochloride/pharmacology , Viral Protease Inhibitors/chemistry , Viral Protease Inhibitors/pharmacologyABSTRACT
Compounds targeting the inflammasome-caspase-1 pathway could be of use for the treatment of inflammation and inflammatory diseases. Previous caspase-1 inhibitors were in great majority covalent inhibitors and failed in clinical trials. Using a mixed modelling, computational screening, synthesis and in vitro testing approach, we identified a novel class of non-covalent caspase-1 non cytotoxic inhibitors which are able to inhibit IL-1ß release in activated macrophages in the low µM range, in line with the best activities observed for the known covalent inhibitors. Our compounds could form the basis of further optimization towards potent drugs for the treatment of inflammation and inflammatory disorders including also dysregulated inflammation in Covid 19.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Autoimmune Diseases/drug therapy , Caspase 1/drug effects , Inflammasomes/drug effects , Inflammation/drug therapy , Serpins/chemical synthesis , Serpins/pharmacology , Tetrazoles/chemical synthesis , Tetrazoles/therapeutic use , Viral Proteins/chemical synthesis , Viral Proteins/pharmacology , COVID-19 , Cell Division/drug effects , Drug Design , Drug Evaluation, Preclinical , Humans , Interleukin-1beta/metabolism , Macrophages/drug effects , Macrophages/metabolism , Tetrazoles/pharmacology , U937 CellsABSTRACT
Thymic stromal lymphopoietin (TSLP) produced by mast cells is involved in allergic inflammation pathogenesis. Chloroquine (CQ) is known to be an anti-malarial drug; however, additional protective functions of CQ have been discovered. This study aims to clarify an anti-inflammatory effect of CQ through modulating TSLP levels using an in vitro model of phorbol myristate acetate (PMA) + A23187-activated human mast cell line (HMC-1) and an in vivo model of PMA-irritated ear edema. CQ treatment reduced the production and mRNA expression levels of TSLP in activated HMC-1 cells. CQ down-regulated caspase-1 (CASP1), MAPKs, and NF-κB levels enhanced by stimulation with PMA + A23187. Moreover, ear thickness in ear edema was suppressed following CQ treatment. CQ decreased CASP1 and NF-κB levels in the ear tissue. TSLP levels in the ear tissue and serum were reduced following CQ treatment. Collectively, the above findings elucidate that CQ inhibits the pro-inflammatory mechanisms of TSLP via the down-regulation of distinct intracellular signaling cascade in mast cells. Therefore, CQ may have protective roles against TSLP-mediated inflammatory disorders.