Abstract
Sepsis and sepsis-induced lung injury remain a leading cause of death in intensive care units. We identified protein kinase C-δ (PKCδ) as a critical regulator of the acute inflammatory response and demonstrated that PKCδ inhibition was lung-protective in a rodent sepsis model, suggesting that targeting PKCδ is a potential strategy for preserving pulmonary function in the setting of indirect lung injury. In this study, whole-body organ biodistribution and pulmonary cellular distribution of a transactivator of transcription (TAT)–conjugated PKCδ inhibitory peptide (PKCδ-TAT) was determined following intratracheal (IT) delivery in control and septic [cecal ligation and puncture (CLP)] rats to ascertain the impact of disease pathology on biodistribution and efficacy. There was negligible lung uptake of radiolabeled peptide upon intravenous delivery [<1% initial dose (ID)], whereas IT administration resulted in lung retention of >65% ID with minimal uptake in liver or kidney (<2% ID). IT delivery of a fluorescent-tagged (tetramethylrhodamine-PKCδ-TAT) peptide demonstrated uniform spatial distribution and cellular uptake throughout the peripheral lung. IT delivery of PKCδ-TAT at the time of CLP surgery significantly reduced PKCδ activation (tyrosine phosphorylation, nuclear translocation and cleavage) and acute lung inflammation, resulting in improved lung function and gas exchange. Importantly, peptide efficacy was similar when delivered at 4 hours post-CLP, demonstrating therapeutic relevance. Conversely, spatial lung distribution and efficacy were significantly impaired at 8 hours post-CLP, which corresponded to marked histopathological progression of lung injury. These studies establish a functional connection between peptide spatial distribution, inflammatory histopathology in the lung, and efficacy of this anti-inflammatory peptide.
Footnotes
- Received April 1, 2015.
- Accepted August 3, 2015.
This work was supported in part by the National Institutes of Health [Grants HL111552 to L.E.K. and 5T32-HL007777 to M.J.M.] and the Department of Defense/Office of Naval Research [Grants N00014-12-1-0597 and ONR N00014-12-1-0810 to M.R.W.].
L.E.K. is listed as an inventor on U.S. patent 8,470,766 entitled “Novel Protein Kinase C Therapy for the Treatment of Acute Lung Injury,” which is assigned to Children's Hospital of Philadelphia and the University of Pennsylvania.
- Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics
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