Anti-asthmatic effect of nafamostat is associated with modulated expression of pro-inflammatory genes, reduced eosinophil infiltration and attenuated airway hyperreactivity

Asthma is typically characterized by an imbalance between the expression of proteases and of inhibitors capable of neutralizing such enzymes. Hence, an attractive option for intervening with asthma could be to interfere with asthma-associated proteases. In this study, we exploited this option by assessing the impact of nafamostat, a serine protease inhibitor with known capacity to neutralize mast cell tryptase, on the manifestations of airway responses in a house dust mite (HDM)-based model of experimental asthma. Our findings reveal that nafamostat efficiently suppressed the airway hyperreactivity in HDM-sensitized mice, which was accompanied by a profound reduction in the infiltration of eosinophils and lymphocytes to the airways, and also by suppression of the levels of proinflammatory compounds within the airway lumen.Further, nafamostat caused a marked reduction of eosinophil inflammation in the lung tissue, and we also show that nafamostat had a dampening impact on goblet cell hyperplasia and smooth muscle layer thickening in the lungs of HDM-sensitized animals. To obtain deeper insight into the mechanism by which nafamostat affects parameters of allergic airway inflammation, a transcriptomic analysis was conducted. This analysis revealed, as expected, that the HDM sensitization caused an upregulated expression of numerous proinflammatory genes. Further, the transcriptomic analysis showed that nafamostat suppressed the levels of multiple proinflammatory genes, with a particular impact on genes related to asthma. Altogether, this study provides extensive insight into the ameliorating effect of nafamostat on experimental asthma, and our findings can thereby provide a basis for the further evaluation of nafamostat as a potential therapeutic agent in human asthma. Mice were lightly anesthetized with isoflurane and the anesthetized mice were instilled with 10 mg of house dust mite (HDM) extract reconstituted in 30 ml PBS (Dermatophagoides pteronyssinus) intranasally twice a week for three weeks. Control mice received 30 ml PBS via the intranasal route. To investigate the efficacy of nafamostat on asthmatic features, nafamostat (20 mg/kg in 3% acetic acid in PBS) were administered thirty minutes before each PBS and/or HDM instillation via the intraperitoneal route. 24 hr mice were euthanized and the left lung was snap frozen and the upper portion of the left lung lobes from separate experiments were grounded in liquid nitrogen, and RNA was extracted using the Qiagen RNeasy® plus mini kit. cDNA libraries were created and amplified using the Ion AmpliSeq™ Transcriptome Mouse Gene Expression Kit (Life Technologies, Carlsbad, CA) following the protocol of the manufacturer; the sequencing was performed on an Ion S5™ XL Sequencer *** Submitter declares that raw data are no longer available. ***