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Perillaldehyde Ameliorates Aspergillus fumigatus Keratitis by Activating the Nrf2/HO-1 Signaling Pathway and Inhibiting Dectin-1-Mediated Inflammation.

ABSTRACT: Purpose:The purpose of this study was to investigate the therapeutic effect of perillaldehyde (PAE) on Aspergillus fumigatus (A. fumigatus) keratitis. Methods:Human corneal epithelial cells (HCECs) were pretreated with PAE and stimulated with A. fumigatus mycelium. C57BL/6 mice were infected with A. fumigatus and treated with or without PAE 1 day after infection. Clinical scores, PCR, ELISA, and Western blotting were used to detect the expression of pro-inflammatory mediators, dendritic cell-associated c-type lectin-1 (Dectin-1), nuclear factor (erythroid-derived 2) like 2 (Nrf2), and heme oxygenase (HO-1). Nrf2 expression in HCECs pretreated with PAE was observed by immunofluorescence. NIMP-R14 protein expression and localization in mouse corneas were observed by immunofluorescence staining after treatment with PAE. Corneal colony counting, time-kill tests, and mycelial transformation inhibition tests were used to evaluate the antifungal effect of PAE. Results:C57BL/6 mice treated with PAE at 1 day after infection had a lower clinical score and decreased IL-1?, TNF-?, IL-6, Dectin-1, and MPO levels. PAE treatment significantly reduced neutrophil recruitments to the corneal stroma. Compared with the DMSO-treated group, PAE treatment significantly decreased mRNA and protein levels of pro-inflammatory cytokines and Dectin-1 in HCECs. PAE pretreatment before A. fumigatus stimulation obviously elevated the mRNA and protein levels of components of the Nrf2/HO-1 axis. HCECs pretreated with PAE before infection showed a weakened ability to inhibit inflammation in the presence of brusatol (BT; an Nrf2 inhibitor) or ZnPP (an HO-1 inhibitor). PAE treatment significantly reduced the fungal load of C57BL/6 mouse corneas and inhibited fungal growth in vitro. Conclusions:These data proved that PAE may ameliorate A. fumigatus keratitis by activating the Nrf2/HO-1 signaling pathway and inhibiting the Dectin-1 mediated inflammatory response and neutrophil recruitment. Furthermore, PAE exerts direct fungicidal activity on A. fumigatus.

SUBMITTER: Fan Y

PROVIDER: S-EPMC7415897 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Perillaldehyde Ameliorates Aspergillus fumigatus Keratitis by Activating the Nrf2/HO-1 Signaling Pathway and Inhibiting Dectin-1-Mediated Inflammation.

Fan Yiqun Y Li Cui C Peng Xudong X Jiang Nan N Hu Liting L Gu Lingwen L Zhu Guoqiang G Zhao Guiqiu G Lin Jing J

Investigative ophthalmology & visual science 20200601 6

<h4>Purpose</h4>The purpose of this study was to investigate the therapeutic effect of perillaldehyde (PAE) on Aspergillus fumigatus (A. fumigatus) keratitis.<h4>Methods</h4>Human corneal epithelial cells (HCECs) were pretreated with PAE and stimulated with A. fumigatus mycelium. C57BL/6 mice were infected with A. fumigatus and treated with or without PAE 1 day after infection. Clinical scores, PCR, ELISA, and Western blotting were used to detect the expression of pro-inflammatory mediators, den ...[more]

PMID: 32579678

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Project description:Aspergillus species are a major worldwide cause of corneal ulcers, resulting in visual impairment and blindness in immunocompetent individuals. To enhance our understanding of the pathogenesis of Aspergillus keratitis, we developed a murine model in which red fluorescent protein (RFP)-expressing A. fumigatus (Af293.1RFP) conidia are injected into the corneal stroma, and disease progression and fungal survival are tracked over time. Using Mafia mice in which c-fms expressing macrophages and dendritic cells can be induced to undergo apoptosis, we demonstrated that the presence of resident corneal macrophages is essential for production of IL-1beta and CXCL1/KC, and for recruitment of neutrophils and mononuclear cells into the corneal stroma. We found that beta-glucan was highly expressed on germinating conidia and hyphae in the cornea stroma, and that both Dectin-1 and phospho-Syk were up-regulated in infected corneas. Additionally, we show that infected Dectin-1(-/-) corneas have impaired IL-1beta and CXCL1/KC production, resulting in diminished cellular infiltration and fungal clearance compared with control mice, especially during infection with clinical isolates expressing high beta-glucan. In contrast to Dectin 1(-/-) mice, cellular infiltration into infected TLR2(-/-), TLR4(-/-), and MD-2(-/-) mice corneas was unimpaired, indicating no role for these receptors in cell recruitment; however, fungal killing was significantly reduced in TLR4(-/-) mice, but not TLR2(-/-) or MD-2(-/-) mice. We also found that TRIF(-/-) and TIRAP(-/-) mice exhibited no fungal-killing defects, but that MyD88(-/-) and IL-1R1(-/-) mice were unable to regulate fungal growth. In conclusion, these data are consistent with a model in which beta-glucan on A.fumigatus germinating conidia activates Dectin-1 on corneal macrophages to produce IL-1beta, and CXCL1, which together with IL-1R1/MyD88-dependent activation, results in recruitment of neutrophils to the corneal stroma and TLR4-dependent fungal killing.

Project description:IntroductionLupus nephritis (LN) is a representative manifestation in systemic lupus erythematosus (SLE). Some studies have shown that myeloid-derived suppressor cells (MDSCs) play a vital role in the regulation of the SLE process. MDSC infiltration in the kidney as well as inflammation and oxidative stress provokes the acceleration and deterioration of LN. Nuclear factor E2-related factor 2 (Nrf2) is thought to be a major regulator of the antioxidant response. Baicalein is a flavonoid with known anti-inflammatory effects and antioxidant response. However, the effects of baicalein on MDSCs, inflammation, and oxidative stress are not evaluated in the development of pristane-induced LN in mice.MethodsThe renoprotective effect of baicalein was detected in a pristane-induced lupus mice model. NLRP3 inflammasome activation and NF-κB phosphorylation as well as reactive oxygen species (ROS) production and Nrf2 activation were examined. The percentages and function changes of MDSCs were measured. The possible mechanisms of the underlying effects of baicalein on ROS production and signaling pathways of Nrf2/heme-oxygenase (HO)-1, NLRP3 inflammasome, and NF-κB phosphorylation in lipopolysaccharide (LPS)-primed MDSCs were analyzed.ResultsBaicalein reduced proteinuria and attenuated renal function impairment and renal histopathology including intrinsic cell proliferation, cellular crescents, and podocyte injury as well as glomerulonephritis activity in lupus mice. Moreover, baicalein downregulated the activation of NLRP3 inflammasome and levels of ROS or NF-κB phosphorylation, and it enhanced Nrf2 activation. Of note, baicalein inhibited the expansion of MDSCs and improved the function of MDSCs in lupus mice. Through analyzing LPS-primed MDSCs in vitro, baicalein was found to exhibit cytoprotective effects coincident with the induction of Nrf2/HO-1 signaling and the suppression of the NLRP3 inflammasome.ConclusionThe data show that baicalein alleviates the symptoms of pristane-induced LN and suggest that the alleviation may be attributed to inhibition of MDSC expansion and regulation of the balance of the Nrf2/HO-1 signal and NLRP3 expression in MDSCs.

Project description:AIM:To observe the expression and role of aryl hydrocarbon receptor (AhR) in the immune response of mouse cornea infected with Aspergillus fumigatus (A. fumigatus). METHODS:Murine models of A. fumigatus keratitis were established by scraping the central epithelium of mouse cornea, daubing A. fumigatus on the cornea and covering with a contact lens. The mice were randomly divided into the control group and the A. fumigatus-infected (A.F.) group for 1, 3 and 5d respectively, which corneas were daily monitored by a slit lamp microscope and the clinical scores were also recorded timely after infection. In this study, immunofluorescence staining was used to detect the expression and localization of AhR in mouse corneas, and the mRNA and protein of AhR were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. In addition, mouse peritoneal macrophages were stimulated by A. fumigatus with or without the pretreatment of AhR antagonist CH223191 and AhR agonist FICZ, and the tumor necrosis factor alpha (TNF-α), inducible nitric oxide synthase (iNOS), interleukin-10 (IL-10) and Arg-1 mRNA were detected by RT-PCR. RESULTS:According to the results of the slit light photography, it was clearly indicated that the corneal inflammation were the most severe and the clinical score became the highest as well on the 3rd day after the infection of A. fumigatus. Contrasted with the control group, the expression of AhR in the corneal epithelial cells infected with A. fumigatus was significantly increased detected by immunofluorescence staining. AhR mainly expressed in the nucleus and cytoplasm of corneal epithelial cells. Consistent with the transcriptional level of AhR mRNA, the expression level of AhR protein reached the peak on the 3rd day after infection which was detected by Western blot. Furthermore, RT-PCR showed that CH223191 up-regulated the expression of TNF-α and iNOS and down-regulated the expression of IL-10 and Arg-1 in peritoneal macrophages; inversely, FICZ reduced the expression of TNF-α and iNOS while elevated the expression of IL-10 and Arg-1. CONCLUSION:AhR is involved in the pathogenesis of A. fumigatus keratitis and induced immune protection in anti-A. fumigatus immune response by inhibiting M1 and increasing M2 phenotype macrophage-related inflammatory factors.

Dataset Information

Perillaldehyde Ameliorates Aspergillus fumigatus Keratitis by Activating the Nrf2/HO-1 Signaling Pathway and Inhibiting Dectin-1-Mediated Inflammation.

Publications

Perillaldehyde Ameliorates Aspergillus fumigatus Keratitis by Activating the Nrf2/HO-1 Signaling Pathway and Inhibiting Dectin-1-Mediated Inflammation.

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