Intestinal epithelial cells of Japanese flounder (Paralichthys olivaceus) as an in vitro model for studying intestine immune function based on transcriptome analysis.

Japanese flounder (Paralichthys olivaceus) is an economically crucial marine species, but diseases like hemorrhagic septicemia caused by Edwardsiella tarda have resulted in significant economic losses. E. tarda infects various hosts, and its pathogenicity in fish is not fully understood. Lipopolysaccharides (LPS) are components of the outer membrane of Gram-negative bacteria and are representative of typical PAMP molecules that cause activation of the immune system. The PoIEC cell line is a newly established intestinal epithelial cell line from P. olivaceus. In order to investigate whether it can be used as an in vitro model for studying the pathogenesis of E. tarda and LPS stimulation, we conducted RNA-seq experiments for the PoIECs model of E. tarda infection and LPS stimulation. In this study, transcriptome sequencing was carried out in the PoIEC cell line after treatment with LPS and E. tarda. A total of 62.52G of high-quality data from transcriptome sequencing results were obtained in nine libraries, of which an average of 87.96% data could be aligned to the P. olivaceus genome. Data analysis showed that 283 and 414 differentially expressed genes (DEGs) in the LPS versus Control (LPS-vs-Con) and E. tarda versus Control groups (Et-vs-Con), respectively, of which 60 DEGs were shared in two comparation groups. The GO terms were predominantly enriched in the extracellular space, inflammatory response, and cytokine activity in the LPS-vs-Con group, whereas GO terms were predominantly enriched in nucleus and positive regulation of transcription by RNA polymerase II in the Et-vs-Con group. KEGG analysis revealed that three immune-related pathways were co-enriched in both comparison groups, including the Toll-like receptor signaling pathway, C-type lectin receptor signaling pathway, and Cytokine-cytokine receptor interaction. Five genes were randomly screened to confirm the validity and accuracy of the transcriptome data. These results suggest that PoIEC cell line can be an ideal in vitro model for studies of marine fish gut immunity and pathogenesis of Edwardsiellosis.

[Anti-angiogenesis effect of AMD3100 in oxygen-induced retinopathy mice].

OBJECTIVE: To observe the inhibition of neovascularisation in the oxygen-induced retinopathy (OIR) mice by a stromal cell-derived factor 1 (SDF-1) antagonist. METHODS: Experimental study. Fifty-eight 7-day-old C57BL/6 mice were divided into 3 groups randomly, the control group (n = 17), the test group (n = 17) and the medication group (n = 24). According to the dosage of AMD3100, the medication group (n = 24) were divided into low dose group, high dose group, low dose control group, and high dose control group (each group n = 6). Each group (19-day-old) was sacrificed to perform ADPase staining, paraffin sections and immunohistochemical staining (anti-VEGF and anti-SDF-1). The average positive staining area percentage (APSAP) was measured as the outcomes and processed with the Students' t-test. RESULTS: Real-time PCR showed expression of both VEGF mRNA (0.080 ± 0.022 vs. 0.123 ± 0.032) and SDF-1 mRNA (0.731 ± 0.099 vs.0.544 ± 0.108) in retinas from the control group and test group, respectively. The expression of these factors in the test group was significantly higher (t = 2.488, P = 0.038;t = 2.864, P = 0.021). The number of neovascular endothelial nuclear that broke through the retinal internal limiting membrane in the paraffin section in the high dose group and the low dose group was significantly less than that in the self-control group (t = -9.507, P = 0.000; t = -10.761, P = 0.000). The appearance of ADPase staining sections in the medication group was more similar to the simple control group than that of the test group. Immunohistochemical staining sections showed that VEGF and SDF-1 expressed in neuroepithelial cells in each group. APSAP in the high dose group and the low dose group was significantly lower than that in the self-control group (VEGF: t = -7.249, P = 0.000; t = -9.02, P = 0.000; SDF-1: t = -5.246, P = 0.000; t = -5.216, P = 0.000). CONCLUSION: These results indicate that AMD3100 block the SDF-1 receptor to reduce the effect of SDF-1, decrease the production of VEGF protein and inhibite neovascularization.