Persistent CMV infection correlates with disease activity and dominates the phenotype of peripheral CD8+ T cells in psoriasis.

BACKGROUND: Previously, we have reported a frequent association of active plaque psoriasis with inflammation-mediated cytomegalovirus (CMV) reactivation.
OBJECTIVES: This study aimed at characterizing the impact of CMV infection on psoriasis disease activity and peripheral cellular adaptive immune response. PATIENTS/
METHODS: Twenty nine patients with active plaque psoriasis and 29 healthy controls were analysed for CMV-serostatus, CMV-antigenaemia, frequencies of peripheral CMV-specific T cells and the immunophenotype of peripheral CD8+ T cells.
RESULTS: (i) Psoriasis severity was higher in CMV-seropositive patients and positively correlated to the severity of CMV-antigenaemia. (ii) In comparison to CMV-seropositive healthy controls, CMV-seropositive psoriasis patients showed a reduced frequency of circulating CMV-specific T cells that increased under effective antipsoriatic therapy. (iii) The immunophenotype of peripheral CD8+ T cells was dominated by CMV-seroprevalence. (iv) Selective analysis of CMV-seronegative psoriasis patients revealed a strong expansion of a - probably early activated - CD8+ T-cell population with the yet undescribed differentiation phenotype 'CD45RA-dim/CD11a-dim'. Under effective antipsoriatic therapy this population decreased in parallel to an increase of effector differentiated CD8+ T cells.
CONCLUSIONS: Taken together with our previous results of inflammation-mediated CMV reactivation in psoriasis, our data support the concept of an interactive relationship between psoriasis and CMV infection which may be mediated by peripheral CD8+ T cells.