Systemic IL-1β production as a consequence of corneal HSV-1 infection-contribution to the development of herpes simplex keratitis

Abstract

This study sought to identify potential therapeutic targets in herpes simplex keratitis (HSK) patients with active and inactive infection by investigating peripheral cytokine production. Peripheral blood mononuclear cells (PBMCs) and serum were prepared from healthy controls and HSK patients during active infection or following treatment (inactive infection). Serum antibody titres were determined by ELISA. Protein expression levels were analysed by Western blot. Cytokine levels were determined by multiplex ELISA. Active corneal herpes simplex virus type 1 (HSV-1) infection resulted in significantly elevated peripheral levels of IL-1β in HSK patients compared to healthy controls, and remained significantly increased following treatment. Elevated production of IL-1β in inactive patients was associated with significantly increased levels of IRF3 and STAT1, key proteins involved in promoting anti-viral immune responses. Our data suggest that inflammation persists beyond the period that it is clinically evident and that enhanced peripheral production of IL-1β may have implications for HSV-1 viral clearance in active and inactive HSK patients.

Keywords: herpes simplex keratitis; herpes simplex virus type 1; inflammation; pathogenesis; peripheral immune response.

Figure 1. Detection of anti-HSV-1 and 2 antibody titers in patients with active or inactive HSK and healthy controls

Levels of anti-HSV-1 and 2 antibodies in serum samples for patients with active or inactive HSK and healthy controls were determined by ELISA as indicated. Each symbol represents individual samples where numerical values denote index of sample ratio. All analyses were performed using GraphPad Prism 6.0 for Windows (GraphPad Software, La Jolla, CA, USA). ^aP<0.005 versus healthy controls.

Figure 2. Comparison of peripheral cytokine levels and transcription factor expression between patients with active or inactive HSK and healthy controls

A-G: Levels of cytokines in serum samples were simultaneously measured using a multiplex electrochemiluminescence assay (Meso Scale Discovery, Gaithersburg, MD, USA) and read by an Imager2400 plate reader (Meso Scale Discovery, Gaithersburg, MD, USA; n=5-6). H-I: PBMCs were isolated from HSK patients with active and inactive disease and healthy controls. Endogenous expression levels of indicated proteins were determined by Western blot (n=5). Results are presented as mean±SD. Data were deemed to be significantly different at P values less than 0.05. All analyses were performed using GraphPad Prism 6.0 for Windows (GraphPad Software, La Jolla, CA, USA). ^aP<0.00, ^bP<0.05 and ^cP<0.008 versus healthy controls.