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Pseudomonas aeruginosa infection augments inflammation through miR-301b repression of c-Myb-mediated immune activation and infiltration.

ABSTRACT: MicroRNAs (miRNAs) play critical roles in various biological processes, including cell proliferation, development and host defence. However, the molecular mechanism for miRNAs in regulating bacterial-induced inflammation remains largely unclear. Here, we report that miR-301b augments pro-inflammatory response during pulmonary infection, and caffeine suppresses the effect of miR-301b and thereby augments respiratory immunity. LPS treatment or Pseudomonas aeruginosa infection induces miR-301b expression via a TLR4/MyD88/NF-?B pathway. Importantly, caffeine decreases miR-301b expression through negative regulation of the cAMP/PKA/NF-?B axis. Further, c-Myb is identified as a target of miR-301b, which positively modulates anti-inflammatory cytokines IL-4 and TGF-?1, but negatively regulates pro-inflammatory cytokines MIP-1? and IL-17A. Moreover, repression of miR-301b results in increased transcription of c-Myb and elevated levels of neutrophil infiltration, thereby alleviating infectious symptoms in mice. These findings reveal miR-301b as a new controller of inflammatory response by repressing c-Myb function to inhibit the anti-inflammatory response to bacterial infection, representing a novel mechanism for balancing inflammation.

SUBMITTER: Li X

PROVIDER: S-EPMC5061341 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Pseudomonas aeruginosa infection augments inflammation through miR-301b repression of c-Myb-mediated immune activation and infiltration.

Li Xuefeng X He Sisi S Li Rongpeng R Zhou Xikun X Zhang Shuang S Yu Min M Ye Yan Y Wang Yongsheng Y Huang Canhua C Wu Min M

Nature microbiology 20160808 10

MicroRNAs (miRNAs) play critical roles in various biological processes, including cell proliferation, development and host defence. However, the molecular mechanism for miRNAs in regulating bacterial-induced inflammation remains largely unclear. Here, we report that miR-301b augments pro-inflammatory response during pulmonary infection, and caffeine suppresses the effect of miR-301b and thereby augments respiratory immunity. LPS treatment or Pseudomonas aeruginosa infection induces miR-301b expr ...[more]

PMID: 27670114

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Project description:BackgroundIsoliquiritigenin (ISL), a natural flavonoid isolated from the root of licorice (Glycyrrhiza uralensis), has shown various pharmacological properties including anti-oxidant, anti-inflammatory and anti-cancer activities. MicroRNAs (miRNAs), a class of small non-coding RNAs, have been reported as post-transcriptional regulators with altered expression levels in melanoma. This study aims to investigate the anti-melanoma effect of ISL and its potential mechanism.MethodsWe investigated the effect of ISL on the proliferation and apoptosis of melanoma cell lines with functional assays, such as CCK-8 assay, colony formation assay and flow cytometry. The protein level of apoptosis related genes were measured by western blotting. High-throughput genome sequencing was used for screening differentially expressed miRNAs of melanoma cell lines after the treatment of ISL. We performed functional assays to determine the oncogenic role of miR-301b, the most differentially expressed miRNA, and its target gene leucine rich repeats and immunoglobulin like domains 1 (LRIG1), confirmed by bioinformatic analysis, luciferase reporter assay, western blotting and immunohistochemical assay in melanoma. Immunocompromised mouse models were used to determine the role of miR-301b and its target gene in melanoma tumorigenesis in vivo. The relationship between miR-301b and LRIG1 was further verified in GEO data set and tissue specimens.ResultsFunctional assays indicated that ISL exerted significant growth inhibition and apoptosis induction on melanoma cells. MiR-301b is the most differentially expressed miRNA after the treatment of ISL and significantly downregulated. The suppressive effect of ISL on cell growth is reversed by ectopic expression of miR-301b. Intratumorally administration of miR-301b angomir enhances the inhibitory effect of ISL on tumor growth in vivo. Bioinformatic analysis showed that miR-301b may target LRIG1, miR-301b suppresses the luciferase activity of reporter constructs containing 3'UTR of LRIG1 as well as the expression level of LRIG1. And the anti-cancer effect of ISL is mitigated when LRIG1 is silenced in vivo and in vitro. Analysis of the melanoma samples obtained from patients shows that LRIG1 is negatively correlated with miR-301b.ConclusionsISL may inhibit the proliferation of melanoma cells by suppressing miR-301b and inducing its target LRIG1.

Project description:BackgroundAmong patients with cystic fibrosis (CF), females have worse pulmonary function and survival than males, primarily due to chronic lung inflammation and infection with Pseudomonas aeruginosa (P. aeruginosa). A role for gender hormones in the causation of the CF "gender gap" has been proposed. The female gender hormone 17?-estradiol (E2) plays a complex immunomodulatory role in humans and in animal models of disease, suppressing inflammation in some situations while enhancing it in others. Helper T-cells were long thought to belong exclusively to either T helper type 1 (Th1) or type 2 (Th2) lineages. However, a distinct lineage named Th17 is now recognized that is induced by interleukin (IL)-23 to produce IL-17 and other pro-inflammatory Th17 effector molecules. Recent evidence suggests a central role for the IL-23/IL-17 pathway in the pathogenesis of CF lung inflammation. We used a mouse model to test the hypothesis that E2 aggravates the CF lung inflammation that occurs in response to airway infection with P. aeruginosa by a Th17-mediated mechanism.ResultsExogenous E2 caused adult male CF mice with pneumonia due to a mucoid CF clinical isolate, the P. aeruginosa strain PA508 (PA508), to develop more severe manifestations of inflammation in both lung tissue and in bronchial alveolar lavage (BAL) fluid, with increased total white blood cell counts and differential and absolute cell counts of polymorphonuclear leukocytes (neutrophils). Inflammatory infiltrates and mucin production were increased on histology. Increased lung tissue mRNA levels for IL-23 and IL-17 were accompanied by elevated protein levels of Th17-associated pro-inflammatory mediators in BAL fluid. The burden of PA508 bacteria was increased in lung tissue homogenate and in BAL fluid, and there was a virtual elimination in lung tissue of mRNA for lactoferrin, an antimicrobial peptide active against P. aeruginosa in vitro.ConclusionsOur data show that E2 increases the severity of PA508 pneumonia in adult CF male mice, and suggest two potential mechanisms: enhancement of Th17-regulated inflammation and suppression of innate antibacterial defences. Although this animal model does not recapitulate all aspects of human CF lung disease, our present findings argue for further investigation of the effects of E2 on inflammation and infection with P. aeruginosa in the CF lung.

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Pseudomonas aeruginosa infection augments inflammation through miR-301b repression of c-Myb-mediated immune activation and infiltration.

Publications

Pseudomonas aeruginosa infection augments inflammation through miR-301b repression of c-Myb-mediated immune activation and infiltration.

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