Neutrophilic skin diseases are a group of disorders characterized by intense dermal infiltration of neutrophils without infection. They include pyoderma gangrenosum, pustular psoriasis, Behçet's disease and so forth. We reported that granulocyte and monocyte adsorption apheresis (GMA) is a useful treatment modality for such refractory skin diseases.
  Microarray analysis of microRNAs (miRNAs) was performed using sera of patients with neutrophilic skin diseases before and after GMA. Several miRNAs significantly increased in patients compared to control subjects. The expression of these miRNAs decreased after apheresis, suggesting that these miRNAs might be involved in the pathogenesis of neutrophilic skin decreases. For in vitro study, we used an all-trans retinoic acid (ATRA)-induced differentiated HL-60, a human acute promyelocytic leukemia cell line. When HL-60 was treated with ATRA, the cells were differentiated to neutrophilic cells which show increased cytoplasm to nucleus ratio, increased condensated chromatin, and nuclear segmentation. The expression of above mentioned miRNAs increased during the differentiation of these cells. Moreover, miRNAs regulate proliferation of cultured keratinocytes. These data suggest that miRNAs play important role in neutrophil differentiation and proliferation of keratinocyte in neutrophilic disorder such as psoriasis and could be a marker of disease severity and response of GMA.

MicroRNA as a disease marker of neutrophilic skin disease