Mammalian target of rapamycin (mTOR) regulates TLR3 induced cytokines in human oral keratinocytes

Recent studies implicate the mammalian target of rapamycin (mTOR) pathway in the control of inflammatory responses following Toll-like receptor (TLR) stimulation in myeloid cells but its role in non-myeloid cells such as human keratinocytes is unknown Here we show that TLR3 signaling can Induce robust cytokine secretion including interleukin 1 beta (IL-1 beta) tumor necrosis factor alpha (TNF alpha) IL-12p70 and interferon beta (IFN-beta) and our data reveal for the first time that inhibiting mTOR with rapamycin suppresses these TLR3 induced responses but actually enhances bioactive IL-12p70 production in human oral keratinocytes Rapamycin inhibited the phosphorylation of the 70-kDa ribosomal protein 56 kinase (p70S6K) and the 4E binding protein 1 (4EBP-1) and suppressed the mitogen activated protein kinase (MAPK) pathway by decreasing phosphorylation of c-Jun N-terminal kinase (JNK) We also show that TLR3 induces Interferon regulatory factor 3 (IRF3) activation by Akt via an mTOR-p70S6K-4EBP1 pathway Furthermore we provide evidence that Poly I C Induced expression of IL-1 beta TNF alpha IL-12p70 and IFN-beta was blocked by JNK inhibitor SP600125 TLR3 preferentially phosphorylated IKK alpha through mTOR to activate nuclear factor kappa beta (NF-kappa B) in human oral keratinocytes Taken together these data demonstrate p70S6K p4EBP1 JNK NF-kappa B and IRF3 are involved in the regulation of inflammatory mediators by TLR3 via the mTOR pathway mTOR is a novel pathway modulating TLR3 induced inflammatory and antiviral responses in human oral keratinocytes (C) 2010 Elsevier Ltd All rights reserved