Activation of Apoptosis in a βB1-CTGF Transgenic Mouse Model

Abstract

To reveal the pathomechanisms of glaucoma, a common cause of blindness, suitable animal models are needed. As previously shown, retinal ganglion cell and optic nerve degeneration occur in βB1-CTGF mice. Here, we aimed to determine possible apoptotic mechanisms and degeneration of different retinal cells. Hence, retinae were processed for immunohistology (n = 5–9/group) and quantitative real-time PCR analysis (n = 5–7/group) in 5- and 10-week-old βB1-CTGF and wildtype controls. We noted significantly more cleaved caspase 3+ cells in βB1-CTGF retinae at 5 (p = 0.005) and 10 weeks (p = 0.02), and a significant upregulation of Casp3 and Bax/Bcl2 mRNA levels (p < 0.05). Furthermore, more terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL+) cells were detected in transgenic mice at 5 (p = 0.03) and 10 weeks (p = 0.02). Neurofilament H staining (p = 0.01) as well as Nefh (p = 0.02) and Tubb3 (p = 0.009) mRNA levels were significantly decreased at 10 weeks. GABAergic synapse intensity was lower at 5 weeks, while no alterations were noted at 10 weeks. The glutamatergic synapse intensity was decreased at 5 (p = 0.007) and 10 weeks (p = 0.01). No changes were observed for bipolar cells, photoreceptors, and macroglia. We conclude that apoptotic processes and synapse loss precede neuronal death in this model. This slow progression rate makes the βB1-CTGF mice a suitable model to study primary open-angle glaucoma.

Hypoxic Processes Induce Complement Activation via Classical Pathway in Porcine Neuroretinas

“…RT-qPCR analyses were carried out with SYBR Green I protocol on PikoReal 96 (Thermo Fisher) [ 42 ]. A plate layout with duplicates for each cDNA and primer was created in advance.…”

Cytokine and Complement Response in the Glaucomatous βB1-CTGF Mouse Model

“…While the IOP was not altered in 5- and 10-week-old βB1-CTGF mice, elevated IOP was accompanied by an apoptotic loss of RCGs in 15-week-old animals ( Reinehr et al, 2019b ). Furthermore, more apoptotic RGCs and TUNEL + apoptotic cells were already noted in 5- and 10-week-old transgenic mice ( Weiss et al, 2021 ). The relation of apoptotic cells and complement activation should be investigated more precisely in future studies.…”

“…The used βB1-CTGF and wildtype (WT) animals in this study had a CD1 background ( Reinehr et al, 2019b ; Weiss et al, 2021 ). All animals were bred in-house at the animal facility at the Ruhr-University Bochum.…”

“…However, the contribution of the complement system in the transgenic βB1-CTGF mouse model has not been investigated yet. Previous studies showed that in these transgenic mice, IOP elevation is accompanied by a degeneration of optic nerve axons and apoptotic RGC loss making it a reliable model for primary open-angle glaucoma (POAG) ( Junglas et al, 2012 ; Reinehr et al, 2019b ; Weiss et al, 2021 ). Particularly, already at the ages of 5 and 10 weeks, more cleaved caspase 3 + RGCs and TUNEL + apoptotic cells were detected in the transgenic βB1-CTGF mice.…”

“…Particularly, already at the ages of 5 and 10 weeks, more cleaved caspase 3 + RGCs and TUNEL + apoptotic cells were detected in the transgenic βB1-CTGF mice. This was accompanied by a loss of retinal neurofilament H in 10-week-old mice ( Weiss et al, 2021 ).…”