ABSTRACT
The outbreak of coronavirus disease 19 (COVID-19), caused by the recently identified coronavirus named SARS-CoV-2, is leading patients to death (mortality: ∼7%) because of cytokine storm. COVID-19 induces excessivesecretion of proinflammatory cytokines and chemokines accompanied by the disruption of the bronchi and alveoli, which could ultimately develop into permanent lung impairments such as pulmonary fibrosis. To regulate theuncontrolled expression of proinflammatory cytokines/chemokines, improved cell-permeable nuclear import inhibitor(iCP-NI) has been developed by fusing sequence-optimized hydrophobic cell-penetrating peptide (CPP), namelyadvanced macromolecule transduction domain (aMTD) with nuclear localization signal (NLS) of stress responsivetranscription factors (SRTFs: NF-κB, STAT1/3, AP-1, and NFAT). Intracellularly delivered NLS is supposed tosuppress expression of proinflammatory cytokines/chemokines by inhibiting transport of SRTFs from cytoplasm intonucleus. iCP-NI regulated expression of cytokines (TNF-α: -79%, IL-6: -91%, IL-12: -110% and IL-10: +574%) andchemokines (MCP-1: -89%) in bronchoalveolar lavage fluids (BALFs) from RNA virus infection mimetic pneumonitisanimals that were induced with inhalation of RNA structure molecule, poly I:C. iCP-NI also significantly decreasedpulmonary fibrosis (-61%) in bleomycin-induced pulmonary fibrosis animals. Moreover, iCP-NI protected leukocytes(CD3+ T cell: 100%, CD4+/CD3+ T cell: 96%, B220+ B cell: 85%, CD45+ macrophage: 100%) and reducedapoptotic splenocytes (-97%) in staphylococcal enterotoxin B (SEB) and poly I:C-induced acute pneumonitisanimals. These results suggest that iCP-NI has potential as a novel therapeutic measurement for inflammationcaused by various infectious diseases including COVID-19 accompanied with cytokine storm and severe sepsis.