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Background: Avian pathogenic E. coli (APEC) can cause localized or systemic infections, collectively known as avian colibacillosis, resulting in huge economic losses to poultry industry globally per year. In addition, increasing evidence indicates that long non-coding RNAs (lncRNAs) play a critical role in regulating host inflammation in response to bacterial infection. However, the role of lncRNAs in the host response to APEC infection remains unclear. Results: Here, we found 816 differentially expressed (DE) lncRNAs and 1,798 DE mRNAs in APEC infected chicken macrophages by RNAseq. The identified DE lncRNA-mRNAs were involved in Toll like receptor signaling pathway, VEGF signaling pathway, fatty acid metabolism, phosphatidylinositol signaling system, and other types of O-glycan biosynthesis. Furthermore, we found the novel lncRNA TCONS_00007391 as an important immune regulator in APEC infection was able to regulate the inflammatory response by directly targeting CD86. Conclusion: These findings provided a better understanding of host response to APEC infection and also offered the potential drug targets for therapy development against APEC infection. [ABSTRACT FROM AUTHOR]

Avian pathogenic E. coli (APEC) is a common pathogen in the poultry industry, which can cause substantial economic losses. Recently, emerging evidence showed that miRNAs were involved in various viral and bacterial infections. To elucidate the role of miRNAs in chicken macrophages in response to APEC infection, we attempted to investigate the miRNAs expression pattern upon APEC infection via miRNA-seq, and to identify the molecular mechanism of the important miRNAs by using RT-qPCR, western blotting, dual-luciferase reporter assay, and CCK-8. The results showed that a total of 80 differentially expressed (DE) miRNAs were identified in comparison of APEC vs. wild-type group, which corresponded to 724 target genes. Moreover, the target genes of the identified DE miRNAs were mainly significantly enriched in the MAPK signalling pathway, autophagy-bird, mTOR signalling pathway, ErbB signalling pathway, Wnt signalling pathway, and TGF-beta signalling pathway. Remarkably, gga-miR-181b-5p is able to participate in host immune and inflammatory responses against APEC infection via targeting of TGFBR1 to modulate the activation of TGF-beta signalling pathway. Collectively, this study provides a perspective of miRNA expression patterns in chicken macrophages upon APEC infection. These findings provide insight into miRNAs against APEC infection, and gga-miR-181b-5p might be a potential target for treating APEC infection. [ABSTRACT FROM AUTHOR]

Background: Receptor interacting serine/threonine kinase 2 (RIP2), ubiquitous in many tissue/cell types, is the key regulator of immune and inflammatory responses for many diseases, including avian pathogenic E. coli (APEC), which causes a wide variety of localized or systemic infections. However, the molecular mechanisms by which RIP2 drives its transcriptional program to affect immune and inflammatory response upon APEC infection remains poorly understood. Results: In this study, RNA-seq and bioinformatics analyses were used to detect gene expression and new direct/indirect RIP2 targets in the treatments of wild type HD11 cells (WT), RIP2 knockdown cells (shRIP2), APEC stimulation cells (APEC), and RIP2 knockdown cells combined with APEC infection (shRIP2 + APEC). The results revealed that a total of 4691 and 2605 differentially expressed genes (DEGs) were screened in shRIP2 + APEC vs. APEC and shRIP2 vs. WT, respectively. Functional annotation analysis showed that apoptosis, MAPK, p53, Toll-like receptor, and Nod-like receptor signaling pathways were involved in APEC-induced RIP2 knockdown HD11 cells. By analyzing the enriched pathway and gene networks, we identified that several DEGs, including HSP90AB1, BID, and CASP9 were targeted by RIP2 upon APEC infection. Conclusion: As a whole, this study can not only provide data support for constructing gene networks of RIP2 knockdown with APEC challenge but also provide new ideas for improving the immune and inflammatory response. [ABSTRACT FROM AUTHOR]

• CircWWP2 was created by back-splicing of exons 2 to 4 of the WWP2 gene. • Overexpression of circWWP2 can promote the LPS induced cellular injury via decreasing cell viability, increasing NO product and pro-inflammatory cytokines. • Thirteen miRNAs were identified to interact with circWWP2 , which potentially target 3,264 genes. • The target genes were enriched in the pathways of lysosomes, IgA-producing intestinal immune networks for IgA production, and Notch signaling pathway. CircRNA, a non-coding RNA, is an ideal biomarker and a suitable potential therapeutic target for various disease due to its high stability, species conservation and cell/tissue specificity. Our previous study has found a circular RNA WWP2 (circWWP2) was significantly decreased in chicken macrophages during bacterial infection. However, the function of circWWP2 in chicken macrophages remains unclear. In this study, it was demonstrated that circWWP2 was a stable circular RNA created by back-splicing of exons 2 to 4 of WWP2 via PCR amplification, Sanger sequencing, RNase R exonuclease digestion, and RT-qPCR. Moreover, bioinformatics analysis showed circWWP2 could interact with 13 miRNAs and target 3,264 genes, which were significantly enriched in lysosomes, IgA-producing intestinal immune networks for IgA production, and Notch signaling pathway. Furthermore, CCK8 and RT-qPCR indicated that overexpression of circWWP2 could promote lipopolysaccharide (LPS)-induced cellular injury by decreasing cell viability and increasing the expression levels of pro-inflammatory cytokines and pro-apoptosis genes, and NO production. CircWWP2 may exert a potential target for the treatment of bacterial infection. Further experiments are necessary to validate the specific mechanism that circWWP2 regulates LPS induced cellular immune responses. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNA) originate from back-splicing events that link a downstream 5'splice site to an upstream 3′ splice site. Circular RNA has been shown to be involved in gene expression, interacting with microRNA and RNA binding proteins to affect transcription, splicing, translation, and other processes. However, little is known about the potential function of chicken circRNAs that trigger the pathogenesis. In a previous study, a circular RNA DNAJB6 (circDNAJB6) was identified as a typical covalently closed circular RNA that is abundant in chicken macrophages upon bacterial infection. It was identified that circDNAJB6 was formed by reverse splicing of exons 2 to 5 of the DNAJB6 gene by PCR amplification, Sanger sequencing, and RNase R exonuclease treatment. Moreover, circDNAJB6 had ability to exacerbate the lipopolysaccharides (LPS) induced cellular injury via reducing cell viability, increasing NO product and pro-inflammatory cytokines. In addition, bioinformatic analysis showed that five miRNAs were identified to interact with circDNAJB6 , potentially targeting 75 genes, which were significantly enriched in the pathways of autophagy-animal and MAPK signaling. This study has provided and broadened a better understanding the function of circDNAJB6 , which may exert potential biomarkers and act as potential targets for the treatment of bacterial infection. • CircDNAJB6 was formed by reverse splicing of exons 2 to 5 of the DNAJB6 gene. • CircDNAJB6 can exacerbate the LPS induced cellular injury via increasing NO product and pro-inflammatory cytokines. • Five miRNAs were identified to interact with circDNAJB6 , which potentially target 75 genes. • The target genes were enriched in the pathways of autophagy-animal and MAPK signaling. [ABSTRACT FROM AUTHOR]

Avian pathogenic E. coli (APEC) has been detected to cause many acute and chronic diseases, resulting in huge economic losses to the poultry industry. Previous experiments have identified the effect of receptor interacting serine/threonine kinase 2 (RIP2) gene in APEC infection. Moreover, increasing evidence indicates that long noncoding RNAs (lncRNAs) play important roles in the anti-bacteria responses. However, little is known about the functions of lncRNAs, especially related to RIP2 , in response to APEC. Therefore, we tried to reveal lncRNAs potentially involved in the immune and inflammatory response against APEC infection, with a particular focus on those possibly correlated with RIP2. A total of 1856 and 1373 differentially expressed (DE) lncRNAs were identified in knockdown of RIP2 cells following APEC infection (shRIP2+APEC) vs. APEC and shRIP2 vs. wild type cells (WT), respectively, which were mainly enriched in lysosome, phagosome, NOD-like receptor signaling pathway, TGF-beta signaling pathway. Significantly, TCONS_00009695 regulated by RIP2 could directly alter the expression of target BIRC3 to modulate cytokines and to participate in immune and inflammatory response against APEC infection. Our findings aid to a better understanding of host responses to APEC infection and provide new directions for understanding the potential association between lncRNAs and APEC pathogenesis. • LncRNAs were involved in host immune response against APEC infection and RIP2 regulation. • 1,856 and 1,373 DE lncRNAs were identified in shRIP2 + APEC vs. APEC and shRIP2 vs. WT, respectively. • Those lncRNAs were mainly enriched in lysosome, phagosome, NOD-like receptor signaling pathway. • LncT9695 regulated by RIP2 can participate in cellular immune response by modulating BIRC3. [ABSTRACT FROM AUTHOR]