Date of Award
Doctor of Philosophy (PhD)
Clifford S. Deutschman
Background: Sepsis, a fatal syndrome of dysregulated inflammation, is the leading cause of death in the critically ill. The lung is the organ most often injured, developing into Acute Respiratory Distress Syndrome (ARDS). However, both sepsis and ARDS predispose patients to immobility and debilitating neuromuscular weakness. Interventions that limit the extent of lung injury would provide both direct and indirect benefit. The cecal ligation and double puncture (2CLP) rodent model of sepsis mimics the ARDS and immobility features of the human syndrome. An endogenous mediator that protects cells from injury is Heat Shock Protein 70 (HSP70). 2CLP eliminates HSP70 abundance in the lung and is associated with ARDS. We hypothesized that delivering an HIV-1 Tat-HSP70 fusion protein to enhance HSP70 abundance in lung cells would protect against lung injury and as an indirect benefit improve locomotion. Methods: Tat-HSP70 was injected into the trachea of Sprague-Dawley rats made septic by 2CLP (2CLP-Tat-HSP70). Controls included unoperated, sham operated, and 2CLP-phosphate buffered saline (PBS) treated rats. Immunoassays were used to examine the abundance of HSP70, Myeloperoxidase (MPO), Cytokine-Induced Neutrophil Chemoattractant-1 (CINC-1), Macrophage Inflammatory Protein-2 (MIP-2) and Interleukin-6 (IL-6) in lung tissue. Rodent locomotor assessment was measured with telemetry. We used descriptive analysis to describe histologic lung findings. Results: (1) Relative to 2CLP-PBS rats, HSP70 treatment significantly increased HSP70 protein abundance in 2CLP-Tat-HSP70 rats and in histologically normal and abnormal lung regions, at 24 and 48 hr, (2) Relative to 2CLP-PBS rats, we observed decreased histologic lung injury in 2CLP-Tat-HSP70 rats at 24 and 48 hr, (3) Relative to 2CLP-PBS rats at similar time-points, abundance of MIP-2 at 24 hr and MPO at 48 hr were significantly decreased in 2CLP-Tat-HSP70 rats, (4) We were unable to detect a difference in abundance of CINC-1, IL-6 and in locomotion in 2CLP-Tat-HSP70 rats, (5) Relative to 2CLP-PBS rats, Tat-HSP70 improved survival following 2CLP at 48 hr. Conclusion: Intratracheal Tat-HSP70 increased lung HSP70 abundance, reduced lung injury as indicated by lung histology, MIP-2 and MPO abundance. Future studies designed to optimize the use of Tat-HSP70 as a treatment for lung injury secondary to sepsis will be explored.
Lyons, Mary Melanie, "Use of Tat-Hsp70 Fusion Protein to Attenuate Sepsis-Induced Lung Injury in Rodents With Acute Respiratory Distress Syndrome Caused by Cecal Ligation and Double Puncture (2clp)" (2013). Publicly Accessible Penn Dissertations. 775.