|AFFILIATIONS||Professor of Vision Science and Optometry, Infectious Diseases & Immunity, and Microbiology|
|RESEARCH||Our epithelial surfaces are normally resistant to infection. Therefore, researchers who study infectious disease in vivo commonly resort to use of models that deliberately compromise the target tissue (or otherwise bypass barriers) so that disease can be enabled and studied. These infection models have led to a plethora of important information about factors involved in pathology and/or its resolution when disease is initated. However, other models are needed to study barriers to infection, or early events that occur prior to disease initiation when it occurs in the absence of overt injury.In our laboratory, we have developed novel in vivo and in vitro methods for studying defenses during health using the eye and the opportunistic bacterium Pseudomonas aeruginosa as models. We have also advanced imaging technologies that enable us to see into the living epithelium to observe what bacteria do and how the tissue responds in either resistant or susceptible states. Using these methods, and employing array/knockout/knockdown technologies, we have identified specific factors that modulate the ability of bacteria to penetrate the ocular surface epithelium. The data show that pathogen recognition systems are involved in resistance, and suggest that bacterial adaptation in vivo contributes to pathogenesis. Studies aimed at understanding early interactions between microbes and the ocular surface prior to disease initiation have potential for development of novel methods to prevent (rather than simply treat) infection of the eye or other sites.|
P. aeruginosa utilizes the type III secreted toxin ExoS to avoid acidified compartments within epithelial cells. Heimer SR, Evans DJ, Stern ME, Barbieri, JT, Yahr T, Fleiszig SMJ. PLoS One, in press.
Surfactant Protein D Contributes to Ocular Defense against Pseudomonas aeuruginosa in a Murine Model of Dry Eye Disease. Heimer SR, Evans DJ, Mun JJ, Stern ME, Fleiszig SMJ. PLoS One. 2013 Jun 6;8(6):e65797. Print 2013.
Why does the healthy cornea resist Pseudomonas aeruginosa infection? Evans DJ, Fleiszig SMJ. Am J Ophthalmol. 2013 Jun;155(6):961-970.e2. Epub 2013, Apr 17. 2013.
MicroRNA-762 is upregulated in human corneal epithelial cells in response to tear fluid and Pseudomonas aeruginosa antigens and negatively regulates the expression of host defense genes encoding RNase7 and ST2. Mun JJ, Tam C, Evans DJ, Fleiszig SMJ. PLoS One. 2013;8(2):e57850. Epub 2013, Feb 28. 2013.
Association between cytotoxic and invasive Pseudomonas aeruginosa and clinical outcome in bacterial keratitis. Borkar DS, Fleiszig SMJ, Leong C, Lalitha P, Srinivasan M, Ghanekar AA, Tam CA, Li WY, Zegans ME, McLeod SD, Lietman TM, Acharya NR. JAMA Ophthalmol. 2013 Feb;131(2):147-53, 2013.
Microbial keratitis: Could contact lens material affect disease pathogenesis? Evans DJ, Fleiszig SMJ. Eye & Contact Lens. 72-77, 39, 2013.
Cytokeratins mediate epithelial innate defense through their antimicrobial properties. Tam C, Mun JJ, Evans DJ, Fleiszig SMJ. J Clin Invest. 122 (10) 3665-3677, 2012.
Translocon-independent intracellular replication by Pseudomonas aeruginosa requires the ADP-ribosylation domain of ExoS. Hrintenko V, Evans DJ, Fleiszig SMJ. Microbes Infect 14:1366-73, 2012.
Adenylate cyclase activity of Pseudomonas aeruginosa ExoY can mediate bleb-niche formation in epithelial cells and contributes to virulence. Hritonenko V, Mun JJ, Tam C, Simon N, Barbieri JT, Evans DJ, Fleiszig SMJ. Microb Pathog, 51: 305-312, 2011.
3D quantitative imaging of unprocessed live tissue reveals epithelial defense against bacterial adhesion and subsequent traversal requires MyD88. Tam CA, LeDue J, Mun JJ, Herzmark P, Robey EA, Evans DJ, Fleiszig SMJ. PLoS ONE, 6(8): e24008, 2011.
Pseudomonas aeruginosa association with anionic hydrogel surfaces in the presence of aqueous divalent-cation salts. Tran VB, Sung YS, Fleiszig SMJ, Evans DJ, Radke CJ. Dynamics of J Colloid and Interface Science, 362: 58-66, 2011.
Modulation of epithelial immunity by mucosal fluid. Mun JJ, Tam C, Evans DJ, Fleiszig SMJ. Scientific Reports: 1,8; 2011.
Role of defensins in corneal epithelial barrier function against Pseudomonas aeruginosa traversal. Augustin DK, Heimer SR, Tam C, Li WY, Le Due JM, Evans DJ, Fleiszig SM. Infect Immun. 2011 Feb;79(2):595-605.
Factors Impacting Corneal Epithelial Barrier Function against Pseudomonas aeruginosa Traversal. Alarcon I, Tam C, Mun JJ, Ledue J, Evans DJ, Fleiszig SM. Invest Ophthalmol Vis Sci. 2011 Mar 14;52(3):1368-77.
The ADP-ribosylation domain of Pseudomonas aeruginosa ExoS is required for membrane bleb niche formation and bacterial survival within epithelial cells. Angus AA, Evans DJ, Barbieri JT, Fleiszig SM. Infect Immun. 2010 Nov;78(11):4500-10.
Pathogenesis of contact lens-associated microbial keratitis. Fleiszig SM, Evans DJ. Optom Vis Sci. 2010 Apr;87(4):225-32.
The impact of inoculation parameters on the pathogenesis of contact lens-related infectious keratitis. Tam C, Mun JJ, Evans DJ, Fleiszig SM. Invest Ophthalmol Vis Sci. 2010 Jun;51(6):3100-6.
Role of the corneal epithelial basement membrane in ocular defense against Pseudomonas aeruginosa. Alarcon I, Kwan L, Yu C, Evans DJ, Fleiszig SM. Infect Immun. 2009 Aug;77(8):3264-71.
Clearance of Pseudomonas aeruginosa from a healthy ocular surface involves surfactant protein D and is compromised by bacterial elastase in a murine null-infection model. Mun JJ, Tam C, Kowbel D, Hawgood S, Barnett MJ, Evans DJ, Fleiszig SM. Infect Immun. 2009 Jun;77(6):2392-8.
The role of twitching motility in Pseudomonas aeruginosa exit from and translocation of corneal epithelial cells. Alarcon I, Evans DJ, Fleiszig SM. Invest Ophthalmol Vis Sci. 2009 May;50(5):2237-44.
Pathogenic phenotype and genotype of Pseudomonas aeruginosa isolates from spontaneous canine ocular infections. Ledbetter EC, Mun JJ, Kowbel D, Fleiszig SM. Invest Ophthalmol Vis Sci. 2009 Feb;50(2):729-36.
Expression of surfactant protein D in human corneal epithelial cells is upregulated by Pseudomonas aeruginosa. Ni M, Tam C, Verma A, Ramphal R, Hawgood S, Evans DJ, Fleiszig SM. FEMS Immunol Med Microbiol. 2008 Nov;54(2):177-84.
Pseudomonas aeruginosa induces membrane blebs in epithelial cells, which are utilized as a niche for intracellular replication and motility. Angus AA, Lee AA, Augustin DK, Lee EJ, Evans DJ, Fleiszig SM. Infect Immun. 2008 May;76(5):1992-2001.
Mutation of the phospholipase catalytic domain of the Pseudomonas aeruginosa cytotoxin ExoU abolishes colonization promoting activity and reduces corneal disease severity. Tam C, Lewis SE, Li WY, Lee E, Evans DJ, Fleiszig SM. Exp Eye Res. 2007 Dec;85(6):799-805.
Life at the front: dissecting bacterial-host interactions at the ocular surface. Evans DJ, McNamara NA, Fleiszig SM. Ocul Surf. 2007 Jul;5(3):213-27. Review.
Human tear fluid protects against Pseudomonas aeruginosa keratitis in a murine experimental model. Kwong MS, Evans DJ, Ni M, Cowell BA, Fleiszig SM. Infect Immun. 2007 May;75(5):2325-32.
The Glenn A. Fry award lecture 2005. The pathogenesis of contact lens-related keratitis. Fleiszig SM. Optom Vis Sci. 2006 Dec;83(12):866-73.
Type III secretion-dependent modulation of innate immunity as one of multiple factors regulated by Pseudomonas aeruginosa RetS. Zolfaghar I, Evans DJ, Ronaghi R, Fleiszig SM. Infect Immun. 2006 Jul;74(7):3880-9.
Actin cytoskeleton disruption by ExoY and its effects on Pseudomonas aeruginosa invasion. Cowell BA, Evans DJ, Fleiszig SM. FEMS Microbiol Lett. 2005 Sep 1;250(1):71-6.