Research Article: RNA-seq profiles of chicken type II pneumocyte in response to Escherichia coli infection

Date Published: June 5, 2019

Publisher: Public Library of Science

Author(s): Lu-Yuan Peng, Zhen-Qiang Cui, Zong-Mei Wu, Ben-Dong Fu, Peng-Fei Yi, Hai-Qing Shen, Selvakumar Subbian.


Avian pathogenic Escherichia coli (APEC) causes great economic loss to the poultry industry worldwide. Chicken type II pneumocytes (CP II cells) secrete surfactants and modulate lung immunity to decrease the infection of the invading pathogen. Nevertheless, the pathogenesis of CP II cells to APEC infection remains poorly understood. Therefore, we conducted global gene expression profiling of CP II cells after APEC-O78 infection to explore the host-pathogen interaction. The differentially expressed genes of CP II cells to APEC infection were characterized by RNA-seq with EB-seq algorithm. In consequence, the mRNA of 18996 genes was identified, and CP II cells responded to APEC infection with marked changes in the expression of 1390 genes. Among them, there are 803 down-regulated mRNAs and 587 up-regulated mRNAs. The KEGG prediction and Gene Ontology terms analysis revealed that the major enriched pathways were related to NF-κB signaling pathway, apoptosis pathway, tight junction, and cytokine-cytokine receptor interaction and other pathways. We adopted qRT-PCR to verify the validity of the selected gene expression. The fold induction of qPCR was similar to the RNA-seq results. These results provide a better understanding of the pathogenesis of APEC, especially apoptosis pathway involved in APEC infection.

Partial Text

Avian pathogenic Escherichia coli (APEC) remains one of the major endemic disease disturbing the global poultry industry [1]. Autologous vaccines only have good efficacy on limited serotype-specific protection, so far diverse serogroups have been linked with disease, particularly O1, O2 and O78 [2]. A recent study showed that the most predominant serogroups were O78 (35.8%) and O2 (14.4%) in eastern China farms [3]. Chickens, turkeys, ducks etc. have currently been shown to be infected with APEC. Furthermore, there are evidences that APEC may lead to extraintestinal infections in humans [4–7].

In recent years, research about bacteria-host interactions were rapidly increasing. However, most reports concentrate on studying gene expression profile in immunologically related tissues and cell such as spleen, bursa, HD11 macrophages, and leukocyte [18–20, 25]. To the best of our knowledge, the current is the first report about the remarked differential responses of CP II cells to the infection of APEC-O78. After infection of APEC-O78, 1390 differentially expressed genes were identified in the CP II cells. These top 15 up-regulated biological process terms included regulation of Toll signaling pathway, apoptotic process, and intracellular signal transduction. Although any significant up-regulation in the mRNA levels of Toll-like receptor (TLR) 1–7 and TLR9 was not found in this study, we found that some genes involved in TLR4 and TLR9 pathways were up-regulated. The up-regulated genes of TLR4 pathways might be related to endotoxin stimulation. In clinical studies, TLR9 agonists had a good effect on the treatment of pathogenic infections, allergies and malignant neoplasms[26].