Osteopontin and protein kinase C regulate PDLIM2 activation and STAT1 ubiquitination in LPS-treated murine macrophages

Long Noncoding RNA GAS5 Regulates Macrophage Polarization and Diabetic Wound Healing

A central feature of diabetic (Db) wounds is the persistence of chronic inflammation, which is partly due to the prolonged presence of proinflammatory (M1) macrophages. Using in vivo and in vitro analyses, we have tested the hypothesis that long noncoding RNA GAS5 is dysregulated in Db wounds. We have assessed the contribution of GAS5 to the M1 macrophage phenotype, as well as the functional consequences of knocking down its expression. We found that expression of GAS5 is increased significantly in Db wounds and in cells isolated from Db wounds. Hyperglycemia induced GAS5 expression in macrophages in vitro. Overexpression of GAS5 in vitro promoted macrophage polarization toward an M1 phenotype by upregulating signal transducer and activator of transcription 1. Of most significance in our judgment, GAS5 loss-of-function enhanced Db wound healing. These data indicate that the relative level of long noncoding RNA GAS5 in wounds plays a key role in the wound healing response. Reductions in the levels of GAS5 in wounds appeared to enhance healing by promoting transition of M1 macrophages to M2 macrophages. Thus, our results suggest that targeting long noncoding RNA GAS5 may provide a therapeutic intervention for correcting impaired Db wound healing.

Osteopontin contributes to effective neutrophil recruitment, IL-1β production and apoptosis in Aspergillus fumigatus keratitis

Fungal keratitis is a major cause of corneal ulcers, resulting in significant visual impairment and blindness. A phosphorylated glycoprotein secreted by immunocompetent cells, osteopontin (OPN) mediates cluster formation of the host fungal receptors and enhances the phagocytosis and clearance of pathogenic fungi. However, whether OPN production and function occurs in fungal keratitis is unknown. OPN expression in Aspergillus fumigatus keratitis patient corneas was assessed by quantitative polymerase chain reaction (qRT-PCR) and immunofluorescence. Human neutrophils, THP-1 macrophages and corneal epithelial cells (HCECs) stimulated with A. fumigatus were utilized for in vitro experiments. Mouse models of A. fumigatus keratitis were developed by intrastromal injection for in vivo experiments. Using siRNAs, neutralizing antibodies, recombinant proteins and inhibitors, the production and role of OPN in A. fumigatus infection was assessed by clinical evaluation, qRT-PCR, immunofluorescence, western blotting and bioluminescence image acquisition. We observed increased corneal OPN expression in A. fumigatus keratitis patients and mouse models compared to controls. OPN production in response to A. fumigatus infection was dependent on LOX-1 and Erk1/2. Compared to controls, OPN knockdown impaired proinflammatory cytokine IL-1β production, which was dependent on 4E-BP1. OPN knockdown decreased myeloperoxidase levels, and resulted in decreased neutrophil recruitment, higher fungal load and increased apoptosis in mouse A. fumigatus keratitis. Our results indicate that OPN is a critical component of the antifungal immune response and is essential for effective neutrophil recruitment, inflammatory cytokine production and apoptosis in A. fumigatus keratitis.