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Date of Award
Anatomy and Cell Biology
Linda D. Hazlett
Corneal infection with P. aeruginosa results in corneal perforation in susceptible
B6, but not resistant BALB/c mice. This study explored their role mBD 1-4 in corneal
infection, and their potential synergy. Immunostaining and real-time RT-PCR data
demonstrated that their expression was either constitutive (mBD1 and mBD2) or
inducible (mBD3 and mBD4) in normal BALB/c and B6 corneas, and disparately
regulated in BALB/c vs B6 corneas after infection. Knock down studies using siRNA
treatment indicated that mBD2 and mBD3, but neither mBD1 nor mBD4, is required in
ocular defense. Moreover, in vivo studies demonstrated individual and combined effects
of mBD2 and mBD3 that modulate bacterial load, PMN infiltration, and production of
pro-inflammatory molecules (e.g., IFN-gamma, MIP-2, IL-1beta, TNF-alpha), iNOS, as well as TLR signaling molecules (e.g., TLR2, TLR4, MyD88) and transcription factor NF-kappaB. Most
notably, bacterial load was increased at 5 days p.i. by silencing either mBD2 or mBD3,
but was elevated at both 1 and 5 days p.i. when silencing both defensins. PMN
infiltration was increased at 1 day p.i. by silencing both defensins or mBD3, but not
mBD2 alone. iNOS expression was elevated by silencing mBD2, but reduced after
silencing mBD3 or both defensins. Additionally, cell sources of mBD2 and mBD3 in
corneal stroma were identified by dual label immunostaining after infection: PMN
produce both defensins, whereas macrophages and fibroblasts produce mBD2 but not mBD3.
Collectively, the data provide evidence that mBD2 and mBD3 together promote
resistance against corneal infection. The conclusions may be relevant to potential
treatment of other ocular diseases, in addition to P. aeruginosa keratitis.
Wu, Minhao, "Defensins In Ocular Immunity" (2010). Wayne State University Dissertations. Paper 55.