Isorhamnetin Ameliorates Aspergillus fumigatus Keratitis by Reducing Fungal Load, Inhibiting Pattern-Recognition Receptors and Inflammatory Cytokines

Abstract

Isorhamnetin is a natural flavonoid with both antimicrobial and antiinflammatory properties, but its effect on fungal keratitis (FK) remains unknown. The current study aims to investigate the antifungal and anti-inflammatory effects of isorhamnetin against mouse Aspergillus fumigatus keratitis. METHODS.In vitro, the lowest effective concentration of isorhamnetin was assessed by minimum inhibitory concentration and cytotoxicity tests in human corneal epithelial cells (HCECs) and RAW264.7 cells. The antifungal property was investigated by scanning electron microscopy and propidium iodide uptake test. The anti-inflammatory effect of isorhamnetin in HCECs and RAW264.7 cells was observed by quantitative real-time polymerase chain reaction (qRT-PCR). In the eyes of mice with A. fumigatus keratitis, FK severity was evaluated using clinical score, plate counting, histological staining and periodic acid Schiff staining. In vivo, the anti-inflammatory effect of isorhamnetin was examined by immunofluorescence staining, myeloperoxidase assay, Western blot, enzyme-linked immunosorbent assay, and qRT-PCR. RESULTS.In HCECs and RAW264.7 cells, isorhamnetin significantly inhibited A. fumigatus conidia growth and hyphae viability at 80 μg/mL without affecting cell viability. In vitro, isorhamnetin altered A. fumigatus hyphal morphology and membrane integrity. In A. fumigatus keratitis mouse model, isorhamnetin treatment alleviated the severity of FK by reducing corneal fungal load and inhibiting neutrophil recruitment. In addition, the mRNA and protein expression levels of TLR-2, TLR-4, Dectin-1, IL-1β, and tumor necrosis factor-α were significantly decreased in isorhamnetin-treated groups in vivo and in vitro. CONCLUSIONS.Isorhamnetin improves the prognosis of A. fumigatus keratitis in mice by inhibiting the growth of A. fumigatus, reducing the recruitment of neutrophils and downregulating inflammatory factors.

Efficacy of Duhuo Jisheng Decoction in Treating Ankylosing Spondylitis: Clinical Evidence and Potential Mechanisms

“…Licochalcone A can delay the progression of inflammation by inhibiting the inflammatory response and inhibiting the degradation of cartilage matrix [ 33 ]. As a direct derivative of quercetin, isorhamnetin has good anti-inflammatory, antioxidant, and antiallergic effects [ 34 , 35 ]. Experiments show that isorhamnetin can inhibit the NF- k B signaling pathway, inhibit the release of cytokines (TNF-a, IL-6, IL-1B), and alleviate inflammation [ 36 ].…”

Hinokitiol alters Gene Expression in Aspergillus fumigatus, protects against fungal keratitis by Reducing Fungal Load, LOX-1, Proinflammatory cytokines and Neutrophil Infiltration

“…Lee et al found that HK could down-regulate the inflammatory response mediated by LPS through inhibiting the expression level of TNF-α and IL-6 in primary human keratinocytes(48). Our data indicated that HK also significantly down-regulated the mRNA and protein levels of corneal pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, which could mediate the recruitment, activation and adhesion of neutrophils(49). A plentiful supply of virulence factors produced by the inflammatory cascade can damage the corneal epithelium and corneal stromal structure(50, 51).…”

Preparation of a Nanobody Specific to Dectin 1 and Its Anti-inflammatory Effects on Fungal Keratitis

“…[29][30][31] The lack of high-efficiency, lowtoxicity, and high-permeability drugs for corneal fungal infections means poor prognosis. [32][33][34] Nanobodies that naturally lack light chains are unique antibodies first found in the sera of sharks and camelids. 35 Because they possess many desirable attributes, such as small molecules, low immunogenicity, strong penetration, and high binding affinity, different types nanobodies have become novel diagnosis and treatment methods for tumors and infectious diseases.…”