Blood to skin recirculation of CD4(+) memory T cells associates with cutaneous and systemic manifestations of psoriatic disease

Blood to skin recirculation could play a role in the pathogenesis of psoriasis. To investigate this possibility we dissected the phenotype of circulating T cells in psoriasis patients, calculated the correlation the clinical parameters of the disease and performed a parallel bioinformatics analysis of gene expression data in psoriatic skin. We found that circulating CCR6(+) CD4(+) TEM and TEFF cells significantly correlated with systemic inflammation. Conversely, the percentage of CXCR3(+) CD4(+) TEM cells negatively correlated with the severity of the cutaneous disease. Importantly CLA(+) CD4(+) TCM cells expressing CCR6(+) or CCR4(+)CXCR3(+) negatively correlated with psoriasis severity suggesting recruitment to the skin compartment. This assumption was reinforced by gene expression data showing marked increase of CCR7 and CLA-encoding gene SELPLG expression in psoriatic skin and strong association of their expression. The data enlightens a role for CD4(+) T cells trafficking between blood and skin in cutaneous and systemic manifestations of psoriasis.