Immunological changes in psoriasis patients under long-term treatment with fumaric acid esters: risk of Kaposi sarcoma occurrence?

BACKGROUND: Psoriasis is a chronic skin disorder. The most frequently used systemic anti-psoriatic therapy in Germany is fumaric acid esters (FAE). OBJECTIVES: We aimed to characterize immunological changes in psoriasis patients under FAE treatment. METHODS AND MATERIALS: Over 200 flow-cytometry analyses of blood from 27 psoriasis patients and histological, molecular, and serological analyses of samples from a patient who developed Kaposi sarcoma (KS) during FAE therapy were performed. RESULTS: The patients receiving FAE showed decreased CD8+ T cell counts, in particular during the first six months. The CD4+ T cell decline was less pronounced and delayed in time. In a patient with KS, we found a profound CD4 and CD8 lymphocytopenia, as well as a NK cell number reduction, although leukocyte and lymphocyte counts were within the recommended limits. The patient was HIV negative, but positive for HHV8. After cessation of FAE therapy, KS regressed. DISCUSSION: HHV8 infection and iatrogenic T cell reduction, prominently of CD8+ T cells, could have contributed to KS development in this patient. Therefore, we suggest a control of CD4+ and CD8+ T cell counts in addition to the commonly-used differential blood counts in patients with a higher HHV8 prevalence or at high risk of other latent viral infections.

Deficiency of IL-22 contributes to a chronic inflammatory disease: pathogenetic mechanisms in acne inversa.

Overexpression of the T cell cytokine IL-22 is linked to the development of some chronic diseases, but little is known about IL-22 deficiency in humans. As demonstrated in this study, acne inversa (AI; also designated as Hidradenitis suppurativa) lesions show a relative deficiency of IL-22 and IL-20, but not of IL-17A, IL-26, IFN-γ, IL-24, or IL-1ß. Moreover, AI lesions had reduced expression of membranous IL-22 and IL-20 receptors and increased expression of the natural IL-22 inhibitor, IL-22 binding protein. AI is a chronic inflammatory skin disease with prevalence up to 4% of the population and in which cutaneous bacterial persistence represents an important pathogenetic factor. Accordingly, we also found a relative deficiency of antimicrobial proteins (AMPs) in AI lesions and a positive correlation between lesional IL-22 and IL-20 versus AMP levels. IL-22, like its tissue cell downstream mediator IL-20, upregulated AMPs in reconstituted human epidermis and was critical for increased AMP levels under inflammatory conditions. The relative IL-22 deficiency in AI was not linked to lesional T cell numbers or Th22/Th1/Th17 subset markers and -inducing cytokines. However, IL-10 was highly expressed in AI lesions and correlated negatively with IL-22 expression. Moreover, IL-10 inhibited IL-22 but not IL-17 production in vitro. The IL-10 overexpression, in turn, was not associated with an elevated presence of regulatory T cells but with the enhanced presence of an IL-10-inducing cytokine. We conclude that IL-22 deficiency may contribute to the pathogenesis of certain chronic disorders as postulated in this paper for AI.