MicroRNA-103 and microRNA-190 negatively regulate NF-κB-mediated immune responses by targeting IL-1R1 in Miichthys miiuy

Plasma MiR-190 is a potential clinical biomarker for acute respiratory distress syndrome in children and its regulatory role in ARDS cell models by targeting KLF15

BACKGROUND

The present research aimed to investigate the clinical value of plasma miR-190 in children with acute respiratory distress syndrome (ARDS) and the impact of miR-190 on LPS-induced ARDS cell models.

METHODS

The plasma miR-190 levels were measured using real-time quantitative reverse transcription PCR (RT-qPCR). LPS-treated human pulmonary microvascular endothelial cells (HPMECs) were established and then transfected with miR-190 mimic, inhibitor, or miR-negative controls. The levels of inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA). The effects of miR-190 on HPMEC proliferation and apoptosis were evaluated by CCK-8 assay and flow cytometry. The regulation of KLF15 by miR-190 was detected by luciferase report assay.

RESULTS

The plasma miR-190 expression was increased in ARDS children and it was positively related to the severity and 28 day-survival. Plasma miR-190 could distinguish ARDS children from healthy children. Inhibition of miR-190 increased LPS-induced HPMEC cell proliferation and decreased cell apoptosis and inflammatory cytokines IL-6, IL-1β, and TNF-α. KLF15 was a direct target of miR-190.

CONCLUSION

Increased plasma miR-190 may be a clinical diagnostic and prognostic predictor for ARDS children. Inhibition of miR-190 may improve LPS-induced ARDS by increasing cell proliferation, inhibiting cell apoptosis and inflammatory response by targeting KLF15.

miR-190 restores the innate immune homeostasis of Drosophila by directly inhibiting Tab2 in Imd pathway

The Drosophila Imd pathways are well-known mechanisms involved in innate immunity responsible for Gram-negative (G-) bacterial infection. The intensity and durability of immunity need to be finely regulated to keep sufficient immune activation meanwhile avoid excessive immune response. In this study, we firstly demonstrated that miR-190 can downregulate the expression levels of antimicrobial peptides (AMPs) in the Imd immune pathway after Escherichia coli infection using the miR-190 overexpression flies and the miR-190KO/+ flies. Secondly, miR-190 overexpression significantly reduces while miR-190 KO increases Drosophila survival rates upon lethal Enterobacter cloacae infection. Thirdly, we further demonstrated that miR-190 negatively regulates innate immune responses by directly targeting both RA/RB and RC isoforms of Tab2. In addition, the dynamic expression pattern of AMPs (Dpt, AttA, CecA1), miR-190 and Tab2 in the wild-type flies reveals that miR-190 play an important role in Drosophila immune homeostasis restoration at the late stage of E. coli infection. Collectively, our study reveals that miR-190 can downregulate the expression of AMPs by targeting Tab2 and promote immune homeostasis restoration in Drosophila Imd pathway. Our study provides new insights into the regulatory mechanism of animal innate immune homeostasis.

Identification and Characterization of Immune-Associated MicroRNAs in Silver Carp (Hypophthalmichthys molitrix) Responding to Aeromonas veronii and LPS Stimulation

The ubiquitous Gram-negative bacterial pathogen Aeromonas veronii (A. veronii) can easily cause inflammatory reactions in aquatic organisms, resulting in high mortality and huge economic losses. MicroRNAs (miRNAs) participate in immune regulation and have certain conserved properties. MiRNAs are involved in the immune responses of a variety of teleost fish infected with bacteria, whereas there is no related report in silver carp (Hypophthalmichthys molitrix). Therefore, we identified the expression profiles of miRNA in silver carp stimulated by A. veronii and LPS. Among them, the quantity of differentially expressed miRNAs (DEmiRNAs) obtained in the silver carp challenge group was 73 (A. veronii) and 90 (LPS). The GO enrichment and analysis of KEGG pathways have shown that the predicted target genes are mainly associated with lipid metabolism and the immune response in silver carp. This indicates the possibility that miRNAs play a role in regulating immune-related pathways. In addition, a total of eight DEmiRNAs validated the accuracy of the sequencing result via quantitative real-time PCR (qRT-PCR). Finally, we selected the silver carp head kidney macrophage cells (HKCs) as model cells and proved that miR-30b-5p can regulate the inflammatory response in silver carp HKCs. This study lays the foundation for exploring miRNA regulation in silver carp during pathogenic bacterial infection. In addition, it provides a reference for the future development of non-coding RNA antibacterial drugs.

Transcriptomic Analysis Reveals Functional Interaction of mRNA-lncRNA-miRNA in Trachinotus ovatus Infected by Cryptocaryon irritans

The skin of Trachinotus ovatus is a crucial component of the mucosal immune system and serves as the primary site of infection by Cryptocaryon irritans. In order to investigate the significant role of skin in C. irritans infection, a comprehensive transcriptome analysis was conducted on skin tissues from the infection group, infection-adjacent group, and infection group compared with the infection-adjacent group (ATT_vs_PER, ADJ_vs_PER, ATT_vs_ADJ). This study identified differentially expressed long non-coding RNAs (DE lncRNAs), microRNAs (DE miRNAs), and differentially expressed genes (DEGs). The prediction of lncRNA target genes was accomplished by utilizing positional relationship (co-location) and expression correlation (co-expression) with protein-coding genes. Subsequently, functional enrichment analysis was conducted on the target genes of differentially expressed lncRNAs, revealing their involvement in signaling pathways such as tight junction, MAPK, and cell adhesion molecules. This study describes the regulatory network of lncRNA-miRNA-mRNA in T. ovatus skin tissue infected with C. irritans. Functional prediction analysis showed that differentially expressed lncRNA and miRNA may regulate the expression of immune genes such as interleukin-8 (il8) to resist the infection of C. irritans. Conducting additional research on these non-coding RNAs will facilitate a deeper understanding of their immune regulatory function in T. ovatus during C. irritans infection. The study of non-coding RNA in this study laid a foundation for revealing the molecular mechanism of the immune system of T. ovatus to respond to the infection of C. irritans. It provided a choice for the molecular breeding of Trachinotus ovatus against C. irritans.

METTL16, an evolutionarily conserved m6A methyltransferase member, inhibits the antiviral immune response of miiuy croaker (Miichthys miiuy)

Methyltransferase like-16 (METTL16) is an m6A RNA methylation transferase that is known to methylate U6 snRNA and pre-mRNA of S-adenosylmethionine synthase but has been poorly studied in fish. In this study, METTL16 was identified in miiuy croaker (Miichthys miiuy). We first performed bioinformatics analysis of the miiuy croaker METTL16 (mmiMETTL16). MmiMETTL16 and other vertebrates METTL16 have a relatively conserved MTD structural domain and gene structure, suggesting that their methylase activity may also be conservative. In healthy miiuy croaker, mmiMETTL16 was commonly expressed in the tested tissues. Expression of mmiMETTL16 in kidney, liver, and spleen tissues was significantly increased after poly(I:C) stimulation. Consistently, mmiMETTL16 was sensitive to poly(I:C) stimulation in miiuy croaker kidney cell (MKC), suggesting that METTL16 might participate in antiviral immunity. For further functional experiments, immunofluorescence of mmiMETTL16 presents in the nucleus in kidney cells. In addition, the overexpression of mmiMETTL16 could significantly increase the overall m6A level of MKC cells, which shows that the function of METTL16 as methyltransferase is conservative in miiuy croaker. Last, mmiMETTL16 can inhibit the expression of TNF-α, IFN-1, Mx1, and ISG15, suggesting that mmiMETTL16 can suppress the immune response caused by viral stimulation. In summary, studies on mmiMETTL16 will contribute to future studies on the role of METTL16 and potential mechanisms of the m6A regulation network in the teleost immune system.

Molecular characterizations, immune modulation, and antibacterial activity of interleukin-17A/F1a and interleukin-17A/F1b in common carp Cyprinus carpio

Interleukin-17 (IL-17), as a pro-inflammatory cytokine family, mediates different pro-inflammatory mediators in various cell types (e.g., epithelial cells, macrophages, endothelial cells, and fibroblasts), which play an important role in defending against pathogens. The IL-17A/F1 genes have recently been reported in fish. However, the functions of these genes are still unclear. In this study, we identified two duplicated IL-17A/F1 genes in common carp (Cyprinus carpio L.), namely, CcIL-17A/F1a and CcIL-17A/F1b. Sequence analysis showed that CcIL-17A/F1a and CcIL-17A/F1b proteins had four conserved cysteine residues, which could form two intra-chain disulfide bridges. Homology comparison displayed that the deduced amino acid sequences of CcIL-17A/F1a and CcIL-17A/F1b shared 31.1%-77.3% and 32.5%-75.7% of sequence similarity to IL-17A/F1 homologues from other fish species, respectively. The mRNA expression levels of CcIL-17A/F1a and CcIL-17A/F1b were obviously increased in gill and head-kidney of fish challenged with A. hydrophila. The recombinant protein rCcIL-17A/F1a and rCcIL-17A/F1b could enhance the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, IFN-γ, and TNF-α) and chemokines (CXCL8 and CXCL20). The 3 × Flag eukaryotic expression vectors to express protein rCcIL-17A/F1a (or rCcIL-17A/F1b) were constructed and intramuscularly injected in common carp. The rCcIL-17A/F1a (or rCcIL-17A/F1b) could be successfully expressed in vivo. Four immune-related genes, namely, CD4, CD8, TNF-α, and IgM, were also significantly induced to be expressed at higher mRNA levels compared with the control. The pretreatment with CcIL-17A/F1a or CcIL-17A/F1b could markedly increase the survival rate of common carp challenged with A. hydrophila. Our results demonstrated that CcIL-17A/F1a or CcIL-17A/F1b plays an important role in immune responses and immune defense against bacteria. CcIL-17A/F1a or CcIL-17A/F1b could also be potentially used as an immunopotentiator to prevent diseases in common carp.