Immunohistochemical expression of Fibrillin-1 in idiopathic epiretinal membranes

To investigate the expression patterns of Fibrillin-1 in idiopathic epiretinal membranes (iERM) and identify Fibrillin-1-secreting cells.

iERM samples were collected via standard 27-gauge vitrectomy and subsequently subjected to flat-mount immunohistochemistry with double staining for the following markers: Fibrillin-1, glial acidic fibrillary protein (GFAP), cellular retinaldehyde-binding protein (CRALBP), retinoid isomerohydrolase RPE65 (RPE65), and α-smooth muscle actin (α-SMA).

Fibrillin-1 was detected throughout the iERM. The colocalization of Fibrillin-1 with α-SMA, CRALBP, and RPE65 suggested that myofibroblasts and retinal pigment epithelial (RPE) cells secreted Fibrillin-1. The lack of colocalization between GFAP and Fibrillin-1 indicated that GFAP-positive glial cells did not secrete Fibrillin-1. The colocalization of CRALBP and RPE65 with α-SMA indicated the transformation of RPE cells into myofibroblasts. This suggested that RPE cells transformed into myofibroblasts and secreted Fibrillin-1. The lack of colocalization between GFAP and α-SMA implied that GFAP-positive glial cells did not express α-SMA.

Fibrillin-1 is widely distributed in iERMs, and myofibroblasts were the primary sources of Fibrillin-1 secretion. Additionally, during their transformation into myofibroblasts, RPE cells secreted Fibrillin-1. GFAP-positive glial cells did not express α-SMA nor secrete Fibrillin-1.

What is known Idiopathic epiretinal membranes are a common cause of visual acuity and quality impairment. The protein and cell components of idiopathic epiretinal membrane exhibit diversity. What is new Fibrillin-1 is present throughout the idiopathic epiretinal membrane. Myofibroblasts are the most important source of Fibrillin-1 secretion. Retinal pigment epithelial cells also secrete Fibrillin-1 when transforming into myofibroblast. Glial cells do not transform to myofibroblast and do not secrete Fibrillin-1.