J. Cameron Millar
My research efforts within the North Texas Eye Research Institute (NTERI) are dedicated to the investigation and further development of the mouse as a useful model for the study of aqueous humor dynamics and primary open-angle glaucoma (POAG). Areas of expertise include studies (in living animals) of: aqueous humor dynamics, intraocular pressure measurement, generation and development of transgenic models of POAG using viral vectors, visualization of the eye using spectral domain ocular coherence tomography (SD-OCT), and electroretinography. Projects currently under way include an investigation, using 5XFAD mice (which express five familial Alzheimer’s Disease (AD) mutations) into a possible connection between AD and POAG I also routinely interact with other NTERI members in a multi-disciplinary manner.
1. A possible association between primary open-angle glaucoma (POAG) and Alzheimer’s disease (AD)
A possible association between primary open-angle glaucoma (POAG) and Alzheimer’s disease (AD) is being studied in transgenic mice (5XFAD mice) that express five familial Alzheimer mutations (human amyloid precursor protein (APP) with Swedish mutations (K670N/M671L) at the β-secretase cleavage site and two FAD associated mutations (I716V/V717I) at the γ-secretase cleavage site, and human PS1 with the M146V and L286V mutations under control of mouse Thy-1 promoter). 5XFAD mice develop Aβ plaque deposition at 2 months and cognitive deficits and neurodegeneration at 4-6 months of age. We have found that 5XFAD mice exhibit significant disturbance in intraocular pressure (IOP) and corresponding changes in aqueous outflow facility compared with controls from age ~3 months onwards. At age ~6 months onwards they accumulate amyloid beta (Ab) in their retinal pigment epithelium and chamber angles, and at age ~10 months they exhibit severe thinning of their retinas and significant loss of retinal ganglion cells (RGCs). Their mean pattern electroretinography (PERG) amplitudes (a measure of RGC function) also diminish accordingly.
Millar, J.C., Webber, H.C., Phan T.N., Neubauer, S. & Clark, A.F. Primary open-angle glaucoma and Alzheimer’s disease: is there an association in 5XFAD mice? Invest. Ophthalmol. Vis. Sci. 57: 2016 ARVO (Accepted for presentation at ARVO meeting, Seattle, Washington, USA 2016).
2.The Use of Lentiviral Vectors as Anterior Segment Gene Transducing Agents in the Mouse are Under Investigation
Recently, we injected copGFP HIV and FIV vectors into mouse eyes and studied expression of fluorescence and immunogenicity, according to the following methodology: Naïve BALB/cJ and C3H/HeJ mice, 8-9 weeks (♀) were each divided into 2 cohorts (N = 5 animals/cohort). One cohort of BALB/cJ and C3H/HeJ animals received (OS only) an intravitreal (IVT) injection (1.336´106 ifu/2μL injection bolus) of FIV vector (pSIF1-H1-siLuc-copGFP). The other cohort of BALB/cJ and C3H/HeJ animals received (OS only) an IVT injection of HIV vector (pSIH1-H1-siLuc-copGFP (8.7´106 ifu/2μL injection bolus)). From Day = 6 following injection, eyes were examined twice/week for fluorescence, and by ophthalmoscopy. On Day = 40, animals were sacrificed and eyes processed for histology. Lentivrus-injected eyes in C3H/HeJ animals showed significant fluorescence in the chamber angle, starting at Day = 9 (HIV) and Day = 20 (FIV), which persisted to sacrifice. FIV-injected eyes in BALB/cJ animals showed marginal fluorescence, starting at Day = 9. HIV-injected eyes in BALB/cJ animals showed no fluorescence. No immunogenicity was seen. In both HIV and FIV-injected C3H/HeJ eye sections, fluorescence was seen in the trabecular meshwork (TM). In FIV-injected BALB/cJ eyes, marginal fluorescence was seen in the TM. Injected eyes also showed marginal fluorescence in retina and lens. In HIV-injected BALB/cJ eyes, no fluorescence was seen. No evidence of inflammatory infiltrates was seen. We conclude that lentiviral vectors are able to yield sustained transgene expression in C3H/HeJ mice TM following IVT injection, without promoting immunogenicity.
Millar, J.C., Holder, M. & Clark, A.F. Investigation of lentiviral vectors as anterior segment gene transducing agents in the mouse. J. Ocul. Pharmacol. Ther. 2015 (Accepted for presentation at AOPT meeting, Charleston, South Carolina, USA 2015).