Attenuation of Pseudomonas aeruginosa infection by INP0341, a salicylidene acylhydrazide, in a murine model of keratitis

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen and a major cause of corneal infections worldwide. The bacterium secretes several toxins through its type III secretion system (T3SS) to subvert host immune responses. In addition, it is armed with intrinsic as well as acquired antibiotic resistance mechanisms that make treatment a significant challenge and new therapeutic interventions are needed. Type III secretion inhibitors have been studied as an alternative or in accompaniment to traditional antibiotics to inhibit virulence of bacteria. In this study, INP0341, a T3SS inhibitor, inhibited cytotoxicity by P. aeruginosa toward human corneal epithelial cells (HCEC) at 100 μM without affecting bacterial growth in the liquid media. An increased expression of antimicrobial peptides and reactive oxygen species generation was also observed in cells exposed to P. aeruginosa in the presence of INP0341. Furthermore, INP0341 efficiently attenuated corneal infection by P. aeruginosa in an experimental model of murine keratitis as evident from corneal opacity, clinical score and bacterial load. Thus, INP0341 appears to be a promising candidate to treat corneal infection caused by P. aeruginosa and can be further considered as an alternative therapeutic intervention.

Molecular Targets and Strategies for Inhibition of the Bacterial Type III Secretion System (T3SS); Inhibitors Directly Binding to T3SS Components

“…Many SAs have also been shown to modulate the expression or genetic regulation of T3SS components and effectors – a possible explanation for the disparity in phenotypic results. Although these inhibitors, like INP0341 [ 264 ], have shown recent successes in vitro and in vivo, they were excluded from this review as they have yet to be shown as direct inhibitors of the T3SS.…”

Recombinant IL ‐22 promotes protection in a murine model of Aspergillus flavus keratitis and mediates host immune responses in human corneal epithelial cells

“…Quantitative PCR was done on ABI PRISM 7900HT Sequence Detection System (Applied Biosystems, Grand Island, NY) using the SYBR Green PCR Master Mix (Thermo Scientific, Waltham, MA). The primers used have been described earlier (Sharma et al, 2018; Sharma, Elofsson, & Roy, 2020). Relative quantities of mRNA expression of respective genes were normalised using the 2 −ΔΔct method using GAPDH as the housekeeping gene.…”

Alternative Therapeutic Interventions: Antimicrobial Peptides and Small Molecules to Treat Microbial Keratitis

“…( Felise et al, 2008 ). Recently Sharma et al (2020 ) have shown that INP0341, a salicyledene acylhydrazide that blocks T3SS, effectively inhibits Pseudomonas infection in a murine model of keratitis. The salicyledene acylhydrazides block the T3SS in several pathogens, including Y. pseudotuberculosis ( Nordfelth et al, 2005 ; Bailey et al, 2007 ), C. trachomatis ( Slepenkin et al, 2011 ) , S. enterica , and P. aeruginosa.…”