Activated inflammatory infiltrate in HSV-1-infected corneas without herpes stromal keratitis.
OBJECTIVE
To investigate herpes stromal keratitis (HSK) immunopathology by studying HSV-1-infected corneas that fail to develop HSK.


METHODS
Plaque assay quantified HSV-1 in the tear film of infected mice. FACS analysis enumerated corneal leukocytic infiltrate and characterized infiltrate phenotypically after staining for activation and regulatory T cell (Treg) markers and for markers of antigen-presenting cell (APC) maturation. Treg cells were depleted in vivo using anti-CD25 mAb. Luminex analysis quantified the amount of cytokines and chemokines expressed in corneal tissue homogenate.


RESULTS
Infected corneas without HSK exhibited a pronounced leukocytic infiltrate containing a significantly higher proportion and nearly identical absolute number of activated CD4+ T cells 15 days after infection when compared with those with HSK. Moreover, the frequency and absolute number of regulatory CD4+ T cells (Tregs) was lower in nondiseased corneas, and Treg depletion did not influence HSK incidence. The frequency of mature, immunogenic DCs and the ratio of mature DCs to CD4+ T cells were nearly identical in corneas with and without HSK. The authors observed a reduced population of neutrophils and reduced expression of neutrophil chemoattractants MIP-1beta and keratinocyte chemoattractant and the neutrophil-attracting cytokine IL-6 in corneas without HSK.


CONCLUSIONS
These findings demonstrate that HSV-1-infected corneas can retain clarity in the presence of a substantial secondary leukocytic infiltrate, that activated CD4+ T cells, while necessary, are not sufficient for HSK development, that susceptibility to HSK is not determined by Tregs, and that clinical disease correlates with the accumulation of a critical mass of neutrophils through chemoattraction.
Divito
Sherrie J
SJ
Graduate Program in Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
Hendricks
Robert L
RL
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D054407:Chemokine CCL4 / Q000378:metabolism; D003319:Corneal Stroma / Q000276:immunology* / Q000821:virology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D018259:Herpesvirus 1, Human / Q000502:physiology*; D016849:Keratitis, Herpetic / Q000276:immunology* / Q000821:virology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
C496535:Ccl4 protein, mouse; D054407:Chemokine CCL4; D016207:Cytokines