Investigation of the protective effect of cilostazol on acute lung injury-mediated inflammation and in silico molecular modelling studies of inflammatory signalling pathway: a repurposing study.

Acute lung injury i.e. ALI and its serious form acute respiratory distress syndrome (ARDS) are incurable medical conditions associated with significant global mortality and morbidity. The objective of the present research was to repurpose cilostazol, an antiplatelet drug with anti-inflammatory, antioxidant and antiapoptotic effect, as a potential approach for treatment of ALI. Its multifaceted effects make it promising candidate but its mechanism against ALI remains elusive. Hence it is needed to elucidate its mechanism of action to revealed its therapeutic potential and improve its clinical outcomes. This study investigated the potential inflammatory therapeutic targets of cilostazol with its protective effect against lipopolysaccharide (LPS)-induced ALI. We have identified 10 inflammatory target proteins of cilostazol i.e. PDK1, RAC1, PTK6, KDR, EGFR, endothelin-I, caspase-3, TNF-α, NF-κB1/BTK, a TLR/IRAK4 by molecular docking and validated by in vivo evaluation to demonstrate its therapeutic efficacy. In vivo experiment was performed in two sets; first to determine cellular inflammation by analysing the biomarkers in both lung homogenate and bronchoalveolar fluid and second set to study lung edema with dexamethasone as a standard. Additionally, respiratory parameters, related mRNA expressions and histopathology was evaluated. Our results, molecular docking showed that cilostazol binds to identified inflammatory target proteins with the same binding affinity as that of experimental inhibitors. In vivo, downregulated oxidative stress, and inflammation i.e. attenuated the pulmonary edema and vascular leakage, release of inflammatory mediators i.e. IL-6, TNF-α, NO, C-reactive protein (CRP), lactate dehydrogenase (LDH) myeloperoxidase (MPO), Krebs von den Lungen 6 (KL-6), and the recruitment of inflammatory cells; downregulated the m-RNA gene expressions of tumour necrosis factor alpha (TNF-α), nuclear factor kappa B( NF-kB), Toll-like receptor 4 (TLR4), Janus kinase/signal transducer, and activator of transcription 3 (JAK and STAT3); and improved total lung capacity in LPS-challenged rats. These findings revealed the cilostazol's efficacy as promising therapeutic agent for ALI by inhibiting the NF-κB/TLR4/JAK-STAT3 signalling pathway.