Interleukin 4 can suppress delayed-type hypersensitivity reactions, but until recently, scientists were unsure of its exact role in psoriasis.

Emmanuella Guenova, MD, from Eberhard Karls University in Germany, and colleagues reported in the Proceedings of the National Academy of Sciences results of an animal model and a study on patients that revealed how interleukin 4 (IL-4) helps against psoriasis at the molecular level and the part it plays in the immune system.

The researchers analyzed the impact of IL-4 on the regulation of IL-23 and T helper type 17 (TH17) cells in delayed-type hypersensitivity reactions (DTHRs), in mice and in patients with psoriasis and found that IL-4 selectively suppresses IL-23 transcription and secretion by cells of the innate immune system.

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They also reported on a previously unidentified “therapeutic mode of action of IL-4 in TH17-mediated inflammation, and a physiologically highly relevant approach to selectively target IL-23/TH17-dependent inflammation while sparing IL-12 and TH1 immune responses,” wrote the scientists.

These study findings confirm that the therapeutic silencing of IL-23 is a potential target for psoriasis prevention and management, along with additional TH17/IL-23–associated autoimmune diseases, according to the investigators.


  1. Guenova E. Proc Natl Acad Sci USA. 2015;112(7):2163–2168.