Temporal Regulation of Rapamycin on Memory CTL Programming by IL-12

Abstract

Mammalian target of rapamycin (mTOR) is a master regulator of cell growth. Recent reports have defined its important role in memory cytotoxic T lymphocyte (CTL) differentiation in infections and memory programming. We report that rapamycin regulated memory CTL programming by IL-12 to a similar level in a wide range of concentrations, and the enhanced memory CTLs by rapamycin were functional and provided similar protection against Listeria Monocytogenes challenge compared to the control. In addition, rapamycin-experienced CTLs went through substantially enhanced proliferation after transfer into recipients. Furthermore, the regulatory function of rapamycin on CD62L expression in memory CTLs was mainly contributed by the presence of rapamycin in the first 24-hr of stimulation in vitro, whereas the effective window of rapamycin on the size of memory CTLs was determined between 24 to 72 hrs. In conclusion, rapamycin regulates IL-12-driven programming of CTLs to a similar level in a wide range of concentrations, and regulates the phenotype and the size of memory CTLs in different temporal windows.

Transcriptome profiling of CTLs regulated by rapamycin using RNA-Seq

“…1B), consistent with recent reports (Li et al 2011; Rao et al 2010). To further study the underlying molecular mechanisms of rapamycin in this regulation, naïve OT-I cells were purified and subsequently stimulated by 3 signals (antigen, costimulation and interleukin-12) in the presence or absence of rapamycin, as described previously (Li et al 2011). Stimulated cells were harvested 3 days after in vitro stimulation, and RNA was purified from these samples.…”

“…The upregulation of CXCL10 and CD62L by rapamycin suggests that the memory programming, is not only regulating survival, but also directing the CTLs where to migrate, which is consistent with previous reports (Li et al 2011; Rao et al 2010). The central memory phenotype of the rapamycin regulated memory CTLs may keep most of them in circulating the secondary lymphoid tissues (Obar and Lefrancois 2010), whereas the effector memory CTLs reside in the tissues (Jameson and Masopust 2009).…”

“…There were 14 genes upregulated by rapamycin (Table S2), including CD62L (Araki et al 2011; Li et al 2011), which is an important marker for central memory CTL and directs the migration of immune cells to secondary lymphoid tissues (Obar and Lefrancois 2010). Another adhesion molecule, CXCL10, was also enhanced by rapamycin.…”

“…Rapamycin enhances memory CTL programming (Li et al 2011; Rao et al 2010), which could be related to mTORC1(Zeng et al 2013). Using high throughput sequencing, we were able to find only 128 genes that were significantly altered by rapamycin, and most of them were inhibited, which is consistent with the function of mTOR in cell growth and proliferation (Araki et al 2009; Chi 2012; Hara et al 2002).…”

“…Recently, inhibition of mTOR in mice was reported to enhance memory CTL generation during infections through suppressing mTORC1 or modulating cell metabolisms (Araki et al 2009; Pearce et al 2009). Inhibition of mTOR using rapamycin during CTL activation leads to increased memory programming (Li et al 2011; Rao et al 2010), which is related to increased memory CTL precursors and their survival (Rao et al 2010), and increased expansion (Li et al 2011). However, how rapamycin regulates this memory CTL programming has not been evaluated on a global level.…”