The lower incidence of rosacea in the elderly may be a result of an aging-related impaired immune response, according to a new study published in the journal Immunity, Inflammation and Disease.¹

Noting that epidemiological studies show that the incidence of rosacea peaks between the ages of 30 and 50, the researchers reported similar findings in 8,340 individuals free of systemic diseases from the Xiangya Hospital in Changsha, China. The highest incidence of rosacea at 4.5% was in the 25-44.9 age group, they said, followed by a notable decline to 2.9% in those 45 to 64.9 years old, and 0.9% in those aged 65 and older.

To further investigate this trend, they injected the cathelicidin LL37 – a factor in the innate immune response thought to contribute to rosacea by inducing inflammation and promoting blood vessel growth – to induce these characteristic rosacea responses in mice. Where the skin of younger mice aged 2 months displayed pronounced rosacea‐like features that escalated with successive doses, the skin of older mice, aged 20 months, showed milder redness (erythema), lighter coloration and reduced area involvement.

In addition, the researchers analyzed mouse keratinocyte (MK) samples treated with LL37 in vitro for a variety of characteristic disease-related molecules found in rosacea patients, including KLK-5, CAMP, TLR2, TNF-α, MMP-9, and MMP-2. They found that LL37 significantly increased the levels of these factors in the MK samples from young mice, which exceeded the levels observed in samples from the aged mice.

“These findings indicate a compromised ability of the aging immune system to mount effective responses to pathogens and external stimuli,” the researchers said.

Reference:

1. Long J, Deng Z, Chen M, Tangxiele L. Impaired angiogenesis and Th1/Th17 polarization: a possible explanation for the decreased incidence of rosacea in the aged. Immun Inflamm Dis 2024 Dec18;12(12):e70108. doi: 10.1002/iid3.70108.