Inhibition of Macrophage Migration Inhibitory Factor Ameliorates Ocular Pseudomonas aeruginosa-Induced Keratitis

Abstract

Pseudomonas aeruginosa causes severe sight-threatening corneal infections, with the inflammatory response to the pathogen being the major factor resulting in damage to the cornea that leads to loss of visual acuity. We found that mice deficient for macrophage migration inhibitory factor (MIF), a key regulator of inflammation, had significantly reduced consequences from acute P. aeruginosa keratitis. This improvement in the outcome was manifested as improved bacterial clearance, decreased neutrophil infiltration, and decreased inflammatory responses when P. aeruginosa-infected MIF knock out (KO) mice were compared to infected wild-type mice. Recombinant MIF applied to infected corneas restored the susceptibility of MIF deficient mice to P. aeruginosa-induced disease, demonstrating that MIF is necessary and sufficient to cause significant pathology at this immune privileged site. A MIF inhibitor administered during P. aeruginosa-induced infection ameliorated the disease-associated pathology. MIF regulated epithelial cell responses to infection by enhancing synthesis of proinflammatory mediators in response to P. aeruginosa infection and by promoting bacterial invasion of corneal epithelial cells, a correlate of virulence in the keratitis model. Our results uncover a host factor that elevates inflammation and propagates bacterial cellular invasion, and further suggest that inhibition of MIF during infection may have a beneficial therapeutic effect.

Homotrimeric Macrophage Migration Inhibitory Factor (MIF) Drives Inflammatory Responses in the Corneal Epithelium by Promoting Caveolin-rich Platform Assembly in Response to Infection

“…Our recent findings were supportive of the concept that targeting MIF could have therapeutic benefits in reducing inflammatory damage during bacterial keratitis, using a model of bacterial keratitis in mice induced by scratch injury, representative of corneal trauma, demonstrating that inhibiting MIF in the presence of antibiotic treatment was protective during acute infection induced by P. aeruginosa (8). Here, we extended our understanding of the molecular basis for the role of MIF in the pathogenesis of keratitis by examining whether different oligomeric forms of MIF exist in vivo.…”

“…Although the molecular mechanisms underlying MIF-triggered inflammation are only partially elucidated, the significance of MIF-dependent pathways in tissue damage are based on the finding that MIF-deficient mice develop milder corneal damage from P. aeruginosa-induced keratitis, characterized by reduced bacterial levels and neutrophil infiltration and decreased overall inflammatory responses (8). These observations suggest that inhibition of MIF may be therapeutically beneficial in states of acute ocular inflammation (8).…”

Human Corneal MicroRNA Expression Profile in Fungal Keratitis

“…33 Furthermore, inhibition of MIF has been shown to reduce the consequences of bacterial keratitis in mice, suggesting that it may have therapeutic effects. 46 Here, we report an inverse correlation in the expression of miR-451a and MIF in infected corneas, which may have physiological . Relative expression levels of miR-cornea-3p, miR-cornea-5p, and the target gene EGR3 in keratitis (n ¼ 6) compared to donor corneas (n ¼ 6).…”

TSP-1 Deficiency Alters Ocular Microbiota: Implications for Sjögren's Syndrome Pathogenesis

“…[10][11][12][13][14][15] Briefly, bone marrow was isolated from hindquarters by flushing the femurs and tibias with 10 mL sterile phosphatebuffered saline (PBS) per mouse. This PBS suspension was run through a 70-mm cell strainer and the cell pellet recollected with a subsequent 10-min centrifugation at 600g.…”

“…The assay was carried out as described by Gadjeva et al 15 and Dwyer and Gadjeva. 17 Briefly, 1 · 10 6 PMNs for each genotypic condition were resuspended in HBSS supplemented with Ca 2 + and Mg 2 + (HBSS +/ + ; GIBCO) to support complement activation 18 and incubated with target bacteria at multiplicity of infection and 25% autologous serum (extracted pericardially and purified with a microtainer) as a source of opsonins.…”