According to a study performed by a team of experts at Kyoto University, human females have a considerably lower incidence of severe psoriasis and hence itch less, which is one of many things that men may be jealous of, at least when it comes to severe skin inflammation.
Hormone that lowers itching
The study’s findings were published in the ‘Journal of Allergy and Clinical Immunology.’ Now, a team of researchers has discovered that the female hormone estradiol lowers itching, and the hormone’s protective effect has created a foundation for its therapeutic potential.
“Our findings not only showed the molecular causes of sex differences in itching, but also shed fresh light on our knowledge of the physiological role of estradiol,” explains Tetsuya Honda, previously of Kyoto University.
The researchers used conditional knockout mice, or cko mice, that had their ovaries removed but were given estradiol pellets or a placebo. Compared to wild-type mice, cko animals lacking the natural ovarian hormone estradiol displayed significant skin irritation.
When these animals were administered estradiol, the synthesis of cytokines IL-17A and IL-1b in neutrophil and macrophage immune cells was reversed, resulting in reduced inflammation. In vitro, same impact was also demonstrated in human neutrophils.
The researchers were interested by how the lack of oestrogen receptors in immune cells rendered estradiol ineffective against the cytokines.
“These findings suggest that estradiol lowers psoriatic inflammation through controlling neutrophil and macrophage cells,” the author writes.