[Amniotic membrane transplantation improves herpetic keratitis by local and not by systemic effects]

The immune mediated HSV-1 stromal keratitis (HSK) rapidly improves after amniotic membrane transplantation (AMT). This study investigated whether AMT modulates the T cell response and whether the anti-inflammatory action of AMT is due to local or systemic effects.

Corneas of BALB/c mice were infected with 10(5) (PFU) of HSV-1. Animals with ulcerating keratitis on day 14 post-infection were divided into 4 groups: group 1 ( n=12): right eye AMT;group 2 ( n=12): right eye tarsorrhaphy; group 3 ( n=8): right eye tarsorrhaphy, left eye AMT;group 4 ( n=8): both eyes tarsorrhaphy. The mice were examined for clinical signs of HSV keratitis after 2 days. Corneal sections were studied histologically and the inflammatory cell infiltration was studied by immunohistochemical staining. DTH response and the HSV-specific 3H-thymidin-uptake were compared between the groups.

Compared to group 2, ulceration and stromal inflammation was profoundly improved in group 1 ( p<0.01). The corneas in the AMT mice had fewer inflammatory cells, CD3+,CD4+ and CD8+ cells than the control mice ( p<0.01). There were no significant differences between groups 1 and 2 with respect to the delayed type hypersensitivity reaction (DTH response) and the HSV-specific 3H-thymidin uptake. AMT or tarsorrhaphy on the left eyes in groups 3 and 4 had no influence on the course of keratitis or the T cell response.

Ulcerating herpetic keratitis markedly improves after AMT. Our observations indicate that this is caused predominantly by local and not by systemic AMT-related effects.