Differential Role of Rapamycin and Torin/KU63794 in Inflammatory Response of 264.7 RAW Macrophages Stimulated by CA-MRSA.

Rebekah K H Shappley,Thomas Spentzas

doi:10.1155/2014/560790

Abstract

Background. Rapamycin suppresses the RAW264.7 macrophage mediated inflammatory response but in lower doses induces it. In the present study, we tested the suppression of the inflammatory response in the presence of mTOR 1 and 2 inhibitors, Torin and KU63794. Methods. RAW264.7 cells were stimulated for 18 hrs with 106 to 107 CFU/mL inocula of community-acquired- (CA-) MRSA isolate, USA400 strain MW2, in the presence of Vancomycin. Then, in sequential experiments, we added Torin, KU63794, and Rapamycin alone and in various combinations. Supernatants were collected and assayed for TNF, IL-1, IL-6, INF, and NO. Results. Rapamycin induces 10–20% of the inflammatory cascade at dose of 0.1 ng/mL and suppresses it by 60% at dose of 10 ng/mL. The induction is abolished in the presence of Torin KU63794. Torin and KU63794 are consistently suppressing cytokine production 50–60%. Conclusions. There is a differential response between Rapamycin (mTOR-1 inhibitor) and Torin KU63794 (mTOR 1 and 2 inhibitors). Torin and KU63794 exhibit a dose related suppression. Rapamycin exhibits a significant induction-suppression biphasic response. Knowledge of such response may allow manipulation of the septic inflammatory cascade for clinical advantages.

Highlights

Sequential cytokine release from macrophages propels the inflammatory response in infection
Rapamycin works by binding cytosolic FK-binding protein 12 (FKBP12) and together these form a complex that binds the mTOR complex 1 [10,11,12,13,14,15]. mTORC1 is a serine/threonine phosphokinase which functions as a redox sensor, regulates cell growth and proliferation [16]
There exist two mTORC1 and 2 inhibitors: KU63794 and Torin; their role is not clear, it appears to exhibit more complete mTORC inhibition than Rapamycin [19, 20]. This study explores their role in inflammatory cascade in comparison to Rapamycin action

Summary

Introduction

Sequential cytokine release from macrophages propels the inflammatory response in infection. Previous studies by our group have shown that inhibition of mTOR by Rapamycin has a dose-dependent biphasic response on TNF secretion [7]. Rapamycin may act on mTOR2 but it is not clear how this pathway influences the inflammatory cascade [17]. Rapamycin suppresses the RAW264.7 macrophage mediated inflammatory response but in lower doses induces it. We tested the suppression of the inflammatory response in the presence of mTOR 1 and 2 inhibitors, Torin and KU63794. Rapamycin exhibits a significant induction-suppression biphasic response. Knowledge of such response may allow manipulation of the septic inflammatory cascade for clinical advantages

Methods

Results

Discussion

Conclusion