Malic acid (MA) has been commonly used in cosmetic products, but the safety reports in skin are sparse. To investigate the biological effects of MA in human skin keratinocytes, we investigated the potential cytotoxicity and apoptotic effects of MA in human keratinocyte cell lines (HaCaT). The data showed that MA induced apoptosis based on the observations of DAPI staining, DNA fragmentation, and sub-G1 phase in HaCaT cells and normal human epidermal keratinocytes (NHEKs). Flow cytometric assays also showed that MA increased the production of mitochondrial superoxide (mito-SOX) but decreased the mitochondrial membrane potential. Analysis of bioenergetics function with the XF 24 analyzer Seahorse extracellular flux analyzer demonstrated that oxygen consumption rate (OCR) was significantly decreased whereas extracellular acidification rate (ECAR) was increased in MA-treated keratinocytes. The occurrence of apoptosis was proved by the increased expressions of FasL, Fas, Bax, Bid, caspases-3, -8, -9, cytochrome c, and the declined expressions of Bcl-2, PARP. MA also induced endoplasmic reticulum stress associated protein expression such as GRP78, GADD153, and ATF6α. We demonstrated that MA had anti-proliferative effect in HaCaT cell through the inhibition of cell cycle progression at G0/G1, and the induction of programmed cell death through endoplasmic reticulum stress- and mitochondria-dependent pathways. Full article

Both atopic diseases and systemic lupus erythematosus (SLE) are immune disorders that may lead to physical complications or multi-system comorbidities. This population-based case-control study was designed to evaluate the risk of SLE associated with atopic diseases. Using a national insurance claims dataset in Taiwan, we identified 1673 patients newly diagnosed with SLE and 6692 randomly selected controls frequency matched for gender, age and index date. The odds ratios (OR) for SLE were calculated for associations with allergic rhinitis, allergic conjunctivitis, atopic dermatitis and asthma. The SLE patients were predominantly female (82.5%) with a mean age of 40.1 (SD = 18.2). The patients with SLE had a higher rate of atopic dermatitis (6.81% vs. 3.06%), and asthma (10.6% vs. 7.64%) was approximately 2 times more common in the patients with lupus than in those without. The patients with atopic disease (atopic dermatitis, allergic rhinitis, allergic conjunctivitis and asthma) were at a significant risk for SLE. The overall risk for SLE increased as the number of atopic diseases increased from 1.46 to 2.29, compared with—individuals without the diseases (p < 0.0001). In conclusion, this population-based case-control study demonstrates a significant relationship between atopic diseases and the risk of SLE, especially for females. Atopic dermatitis plays a stronger role than other types of atopic disease in association with SLE. Full article