Epithelial cells along the mucosal surface provide the front line of host defense against pathogen infection in the gastrointestinal (Gl) tract. Because of the importance of Toll-like receptor (TLR) signaling in the initiation and regulation of Gl mucosal immunity, the overall objective of this application is to better understand the molecular mechanisms by which TLR signaling coordinates Gl epithelial antimicrobial defense. Our preliminary studies demonstrate that microbial challenge stimulates exosome release from the apical side of cultured Gl epithelial monolayers in a TLR4-dependent manner. Released exosomes shuttle a variety of antimicrobial peptides and display antimicrobial activity ex vivo. Moreover, activation of TLR4/NF-?B signaling causes alterations in expression of microRNAs (miRNAs), small non-coding miRNAs that regulate gene expression at the posttranscriptional level. Selected TLR4-responsive miRNAs may target effector molecules that regulate the exocytotic process and, thus, are potentially involved in TLR4-mediated exosome release. Based on these exciting novel preliminary data, we propose to test the hypothesis that the release of exosomes from epithelial cells is regulated by TLR signaling with the involvement of miRNA- mediated gene regulation at the posttranscriptional level, and that it contributes to TLR-mediated Gl epithelial antimicrobial defense. We will use in vitro and in vivo infection models and complementary biochemical, molecular, and morphologic approaches to test four interrelated Specific Aims: i) The TLR signaling pathway regulates release of apical exosomes from epithelial cells in response to microbial challenge;ii) TLR signaling stimulates exosome release from epithelial cells through the IKK/SNAP-23- associated exocytotic process with the involvement of miRNA-mediated posttranscriptional regulation;iii) TLR signaling regulates exosomal shuttling of antimicrobial peptides;and iv) epithelial exosomes contribute to TLR-mediated epithelial antimicrobial defense. The proposal is conceptually innovative as it tests new concepts regarding TLR-mediated mucosal antimicrobial defense. The information obtained from this study should provide a rational basis for the design and implementation of new therapeutic strategies.
The proposed research will study the role of epithelial cell-derived apical exosomes and miRNA-mediated posttranscriptional gene regulation in TLR-associated epithelial antimicrobial immune responses. The overall goal is to elucidate the molecular mechanisms by which TLR signaling coordinates epithelial antimicrobial defense and provide a basis for the identification of novel new targets for therapeutic intervention.
|Hu, Guoku; Gong, Ai-Yu; Wang, Yang et al. (2016) LincRNA-Cox2 Promotes Late Inflammatory Gene Transcription in Macrophages through Modulating SWI/SNF-Mediated Chromatin Remodeling. J Immunol 196:2799-808|
|Checkley, William; White Jr, A Clinton; Jaganath, Devan et al. (2015) A review of the global burden, novel diagnostics, therapeutics, and vaccine targets for cryptosporidium. Lancet Infect Dis 15:85-94|
|Xie, Hongguan; Lei, Ningfei; Gong, Ai-Yu et al. (2014) Cryptosporidium parvum induces SIRT1 expression in host epithelial cells through downregulating let-7i. Hum Immunol 75:760-5|
|Zhou, Rui; Feng, Yaoyu; Chen, Xian-Ming (2014) Non-coding RNAs in epithelial immunity to Cryptosporidium infection. Parasitology 141:1233-43|
|Hu, Guoku; Gong, Ai-Yu; Roth, Amanda L et al. (2013) Release of luminal exosomes contributes to TLR4-mediated epithelial antimicrobial defense. PLoS Pathog 9:e1003261|
|Zhou, Rui; Gong, Ai-Yu; Chen, Dongqing et al. (2013) Histone deacetylases and NF-kB signaling coordinate expression of CX3CL1 in epithelial cells in response to microbial challenge by suppressing miR-424 and miR-503. PLoS One 8:e65153|
|Hu, Guoku; Drescher, Kristen M; Chen, Xian-Ming (2012) Exosomal miRNAs: Biological Properties and Therapeutic Potential. Front Genet 3:56|
|Zhao, Jian; Gong, Ai-Yu; Zhou, Rui et al. (2012) Downregulation of PCAF by miR-181a/b provides feedback regulation to TNF-Ã½Ã½-induced transcription of proinflammatory genes in liver epithelial cells. J Immunol 188:1266-74|
|Zhou, Rui; Gong, Ai-Yu; Eischeid, Alex N et al. (2012) miR-27b targets KSRP to coordinate TLR4-mediated epithelial defense against Cryptosporidium parvum infection. PLoS Pathog 8:e1002702|
|Zhou, Rui; Li, Xiaoqing; Hu, Guoku et al. (2012) miR-16 targets transcriptional corepressor SMRT and modulates NF-kappaB-regulated transactivation of interleukin-8 gene. PLoS One 7:e30772|
Showing the most recent 10 out of 11 publications