Cytokine and chemokine ligand expression in cutaneous lupus erythematosus

There is increasing evidence that cytokines as well as chemokines are important players in the pathogenesis of lupus erythematosus (LE). We aimed to compare cytokine and chemokine profiles in different types of cutaneous LE. We investigated lesional mRNA and protein expression of various cytokines and chemokines in patients with chronic discoid LE (CDLE, n=15), subacute cutaneous LE (SCLE, n=11), and lupus erythematosus tumidus (LET, n=21). TNF-α, INF-γ, TGF-β, IL-6, IL-10, IL-12p40, CXCL9, and CXCL10 mRNA expression were significantly increased in SCLE when compared to CDLE. Moreover, LET also showed significantly increased mRNA expression of TNF-α, TGF-β, IL-10, IL-12p40 and CXCL9, as compared to CDLE. In all LE subtypes, CXCL9 and CXCL10 mRNA expression significantly correlated with INF-γ mRNA expression, as indicated by r-values ranging from 0.71 - 0.87. Immunohistochemistry for TNF-α, INF-γ, and IL-10 gave support to our RT-PCR results. In conclusion, our results suggest that T helper 1, as well as T helper 2 cytokines are differentially expressed in CDLE, SCLE, and LET. Compared to CDLE, the highest cytokine and chemokine ligand profiles are found in SCLE followed by LET. Our correlation studies also support the importance of an IFN-driven inflammation in cutaneous LE.