Baicalin Inhibits Cell Proliferation and Inflammatory Cytokines Induced by Tumor Necrosis Factor α (TNF-α) in Human Immortalized Keratinocytes (HaCaT) Human Keratinocytes by Inhibiting the STAT3/Nuclear Factor kappa B (NF-κB) Signaling Pathway.

BACKGROUND Baicalin is a flavone isolated from the root of Scutellaria baicalensis and is used in traditional Chinese medicine. Psoriasis is a persistent and recurrent chronic inflammatory skin disease that is characterized by inflammation and increased proliferation of keratinocytes. This study aimed to investigate the effects of baicalin on HaCaT immortalized human keratinocytes in vitro and the molecular mechanisms involved. MATERIAL AND METHODS HaCaT keratinocytes were cultured in increasing concentrations of baicalin at 6.25 µM, 12.5 µM, and 25 µM. The in vitro model of psoriasis was established using HaCaT cells treated with tumor necrosis factor-alpha (TNF-alpha). The MTT assay was used to asses cell viability and apoptosis. Western blot was used to measure the expression of Bcl-2, Bax, pro-caspase-3, and cleaved caspase-3, and enzyme-linked immunosorbent assay (ELISA) was performed to detect inflammatory cytokines. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the levels of STAT3 and p65 mRNA. RESULTS Baicalin reduced cell viability and induced apoptosis of HaCaT human keratinocytes in a dose-dependent manner. Increased cell viability and the expression of inflammatory cytokines by HaCaT cells induced by TNF-alpha were significantly inhibited by baicalin. Baicalin significantly inhibited the activation of the STAT3/NF-kappaB pathway in HaCaT cells stimulated by TNF-alpha. CONCLUSIONS Baicalin inhibited the proliferation and expression of inflammatory cytokines in HaCaT immortalized human keratinocytes in vitro through the inhibition of the STAT3/NF-kappaB signaling pathway.

Legacy and novel brominated flame retardants in indoor dust from Beijing, China: Occurrence, human exposure assessment and evidence for PBDEs replacement.

Levels of legacy brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), hexabromocyclododecane isomers (HBCDs) and polybrominated diphenyl ethers (PBDEs), and six currently used novel BFRs were determined in house dust and office dust collected from a community in Beijing, China. This is the first study where the three kinds of legacy BFRs and novel BFRs were all measured in dust samples from China. HPLC-MS/MS was used for the detection of TBBPA and HBCDs, and the other BFRs were tested on a GC-NCI/MS. Decabromodiphenyl ethane (DBDPE), PBDEs, HBCD and TBBPA were found to be the main BFRs in the dust samples, with median levels of 709, 241, 199 and 26.7ng/g dust, respectively. Due to the high density of electronic equipment used in offices, levels of BFRs in office dust were found to be higher than those in house dust. DBDPE, as a replacement of PBDEs, was the predominant BFR, and the median level of DBDPE was not only several orders of magnitude higher than that of other novel BFRs but also 3 to 27 times higher than that of the three legacy BFRs, indicating that the consumption pattern of BFRs in the Chinese market has shifted from PBDEs to PBDE alternatives. Median estimated daily intakes (EDIs) of BFRs through dust ingestion for adults (>20years) and toddlers (<2years) were in the range of 2.8×10-5-0.201ng/kg body weight (bw)/day and 5.7×10-4-2.52ng/kg bw/day, respectively. The body burden of BFRs for toddlers was far higher than that for adults; however, a comparison between EDIs and threshold values suggested that daily intakes of BFRs for both adults and toddlers were unlikely to raise significant health concerns.