Pollen from the Cryptomeria japonica (Japanese cedar) tree lowers the skin's barrier function by causing evaporation of moisture and inhibiting oil secretions, researchers said.
The findings, which were reported by a joint research group affiliated with the Shiseido Life Science Research Center and the Japan Science and Technology Agency, among other institutions, make it clear that Japanese cedar pollen not only affects the eyes and nose, but is also part of a mechanism causing skin damage.
Research group members said that when the Japanese cedar pollen protein antigen Cryj1 -- which is a cause of allergies -- was applied to cultured skin whose outermost epidermal layer had been removed using cellophane tape, far higher levels of moisture evaporation were seen as compared with samples that had been dabbed with water.
Normally, the peeling off of the outermost epidermal layer of skin results in oily secretions, and a consequent recovery of the skin's barrier function. In the case of the Cryj1 sample, however, secretions of oil were found to be scant.
A lack of moisture and oils causes the skin to dry out, thereby worsening inflammation. The findings are reportedly the first in the world to specifically identify a mechanism of a compromised skin barrier function, which damages skin.
"Even individuals with healthy skin experience lower skin barrier functioning from stress and other causes," noted Shiseido Life Science Research Center chief researcher Mitsuhiro Denda.
He added, "If (the Cryj1) protein gets into the skin and decreases the skin barrier function even further, it is possible that a negative spiral could be unleashed, whereby inflammation worsens, itchiness increases, scratching ensues, and the inflammation then becomes chronic."
"Pollen that has made its way onto the skin should be washed off as soon as possible," Denda says. He also points toward the "importance of protecting the skin through a regimen of care."