Rapamycin Augments the NMDA-Mediated TNF Suppression of MRSA-Stimulated RAW264.7 Murine Macrophages

Rapamycin Augmentation of Chronic Ketamine as a Novel Treatment for Complex Regional Pain Syndrome

This case report describes the dramatic clinical response of refractory chronic complex regional pain syndrome to combined immunomodulatory treatment. Ketamine and rapamycin markedly minimized pain historically associated with suicidal behavior, increased baseline activity, and allowed for a reduction in palliative polypharmacy. The piecewise mechanism of action is unclear given multiple postulated targets, such as microglia, astroglia, T-regulatory cells, B-regulatory cells, or neurons. Relevant laboratory and genetic information may allow the application of this treatment to other affected individuals.

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

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.

Rapamycin unbalances the polarization of human macrophages to M1

Plasticity is a hallmark of macrophages, and in response to environmental signals these cells undergo different forms of polarized activation, the extremes of which are called classic (M1) and alternative (M2). Rapamycin (RAPA) is crucial for survival and functions of myeloid phagocytes, but its effects on macrophage polarization are not yet studied. To address this issue, human macrophages obtained from six normal blood donors were polarized to M1 or M2 in vitro by lipopolysaccharide plus interferon-γ or interleukin-4 (IL-4), respectively. The presence of RAPA (10 ng/ml) induced macrophage apoptosis in M2 but not in M1. Beyond the impact on survival in M2, RAPA reduced CXCR4, CD206 and CD209 expression and stem cell growth factor-β, CCL18 and CCL13 release. In contrast, in M1 RAPA increased CD86 and CCR7 expression and IL-6, tumour necrosis factor-α and IL-1β release but reduced CD206 and CD209 expression and IL-10, vascular endothelial growth factor and CCL18 release. In view of the in vitro data, we examined the in vivo effect of RAPA monotherapy (0·1 mg/kg/day) in 12 patients who were treated for at least 1 month before islet transplant. Cytokine release by Toll-like receptor 4-stimulated peripheral blood mononuclear cells showed a clear shift to an M1-like profile. Moreover, macrophage polarization 21 days after treatment showed a significant quantitative shift to M1. These results suggest a role of mammalian target of rapamycin (mTOR) into the molecular mechanisms of macrophage polarization and propose new therapeutic strategies for human M2-related diseases through mTOR inhibitor treatment.