Intestinal epithelial cells (IECs) represent the initial point of invasion for the pathogen Listeria monocytogenes however; the role of epithelial pattern recognition receptors (PRRs) engagement and subsequent inflammatory cascades remains poorly characterised. The aim of our study was to determine which PRRs are involved in initiating the immune response to L. monocytogenes in IECs. We performed a PRR siRNA library screen of 50 PRRs in the HT-29 IEC prior to infection with L. monocytogenes and then measured immune gene expression by qRT-PCR. Silencing of TLR1, TLR2, TLR10 and NLRP2 resulted in reductions in CCL20 and IL8 induction following infection, while silencing of NLRP7 and NLRP10 increased expression levels. Silencing of TLR10 gave the most significant effect and subsequent stable lentivirus knockdown of TLR10 in HT-29s yielded similar results upon infection. Similarly, silencing of TLR10 in macrophage-like THP-1 cells resulted in markedly reduced cytokine production in response to L. monocytogenes infection. Moreover, TLR10 silencing resulted in greater viability of L. monocytogenes in both THP-1 macrophages and HT-29 epithelia. Using an NF-κB reporter HEK cell line we found that TLR10 requires TLR2 for efficient NF-κB activation following L. monocytogenes infection. These data indicate a previously unknown role for TLR10 in sensing of pathogenic infection and moreover have potentially identified L. monocytogenes as a specific ligand for the orphan receptor TLR10.
- Copyright © 2013 by The American Association of Immunologists, Inc.