Influence of dimethylfumarate on experimental HSV-1 necrotizing keratitis.

Background: This study was performed to investigate the influence of fumaric acid esters on the course of herpes stromal keratitis (HSK).
Methods: The corneas of BALB/c mice were inoculated with 105 plaque-forming units of herpes simplex virus 1 (HSV-1, KOS strain). Groups of mice were treated intraperitoneally with phosphate buffered saline (PBS) (control mice), or with dimethylfumarate (DMF) at 15 mg/kg of body weight dissolved in PBS daily for 28 days pre-infection and for 14 days post-infection. The course of HSV-1 keratitis was studied clinically. Corneal sections were examined for inflammatory cell infiltration. The numbers of CD3, GR-1, CD11b and F4/80-expressing cells infiltrating the corneas were analyzed by immunohistochemistry.
Results: On day 14 after HSV infection, 72% of the mice in the control group had severe HSK. The development of HSK was reduced by DMF treatment in the DMF group (22%) (P=0.004). The total number of inflammatory cells and infiltration of polymorphonuclear-neutrophils (PMNs) were reduced in the corneas of DMF-treated mice. Compared to the PBS-treated mice, numbers of CD3, CD11b, GR-1 and F4/80-positive cells were reduced in the DMF group of mice.
Conclusions: The course of experimental herpes stromal keratitis can be improved with systemic fumaric acid ester treatment. The improvement of keratitis correlates with a reduced corneal infiltration of T cells and mononuclear cells.