Abstract
Purpose :
Transient receptor potential vanilloid 1 (TRPV1) is a cation channel that plays a role in nociception, inflammation, and nerve growth. In the cornea, TRPV1 is expressed in nerves, contributing to neurotrophic signaling, which is essential for nerve regeneration. The changes in the anatomical expression of TRPV1 after a Benzalkonium chloride (BAK) cornea injury were characterized using newly generated TRPV1-cre-td-Tomato mice.
Methods :
We generated a transgenic mouse that contains Td tomato expression under the TRPV1 promoter. For this, the TRPV1-IRES-cre knock-in mice (B6.129-Trpv1tm1(cre)Bbm/J, Jackson Labs #017769) were crossed with Ai14-tdTomato mice (B6.Cg-Gt(ROSA)26Sortm14(CAG-tdTomato)Hze/J, strain # 007914) resulting in red fluorescently labelled endogenous TRPV1 nerves. Male and female TRPV1-IRES-Cre x Ai14-tdTomato mice (8-12 weeks old) were subjected to 30-minute instillation of a 0.01% BAK solution dissolved in artificial tears. Corneal epithelium damage was evaluated using fluorescein staining and slit lamp imaging. Mice were euthanized at days 3, 7, 14, and 28 with corneas collected and trigeminal ganglia isolated for light sheet imaging (LSM) and immunostaining. For LSM dissected corneas were mounted on 1% agarose and imaged on a Zeiss LSM7 microscope. For immunostaining corneas or TG neurons were incubated in a blocking buffer for 1 hour at RT followed by anti B3 tubulin or anti-TRPV1 antibodies. Samples were imaged using an AxioObserver fluorescent microscope.
Results :
Our TRPV1-IRES-Cre x Ai14-tdTomato mouse showed strong expression of endogenous TRPV1 in the nerve terminals and the neuronal cell bodies of the TG. Our studies show that injured mice euthanized over 28 days showed differential expression of TRPV1 in both cornea and isolated neuronal TGs. In current analysis of BAK-treated mice, TRPV1 expression is variable and this could be due to the nerve fragmentation observed with the full disappearance of nerve terminals and trunks in this chronic injury model.
Conclusions :
Our findings suggest that this transgenic mouse could be useful to trace and determine the anatomic recovery of TRPV1 after corneal injury. BAK-induced corneal injury leads to nerve fragmentation and variable expression of the TRPV1 in corneal nerves. Ongoing studies aim to determine the functional recovery of TRPV1 after corneal injury.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.