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Kumar KJS, Vani MG, Wang SY. Limonene protects human skin keratinocytes against UVB-induced photodamage and photoaging by activating the Nrf2-dependent antioxidant defense system. ENVIRONMENTAL TOXICOLOGY 2022; 37:2897-2909. [PMID: 36063024 DOI: 10.1002/tox.23646] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Long term exposure to solar ultraviolet B (UVB) radiation is one of the primary factors of premature skin aging and is referred to as photoaging. Also, mammalian skin exposed to UVB triggers an increase in production of α-melanocyte-stimulating hormone (α-MSH), which is critically involved in the pathogenesis of hyperpigmentary skin diseases. This study investigated the protective effect of limonene on UVB-induced photodamage and photoaging in immortalized human skin keratinocytes (HaCaT) in vitro. Initially, we determined cell viability and levels of reactive oxygen species (ROS) in UVB-irradiated HaCaT cells. Pretreatment with limonene increased cell viability followed by inhibition of intracellular ROS generation in UVB-irradiated HaCaT cells. Interestingly, the antioxidative activity of limonene was directly correlated with an increase in expression of endogenous antioxidants, including heme oxygenase 1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO-1), and γ-glutamylcysteine synthetase (γ-GCLC), which was associated with enhanced nuclear translocation and activation of NF-E2-related factor-2 (Nrf2). Indeed, Nrf2 knockdown reduced limonene's protective effects. Additionally, we observed that limonene treatment inhibited UVB-induced α-MSH secretion followed by inhibition of proopiomelanocortin (POMC) via suppression of p53 transcriptional activation. Moreover, limonene prevented UVB-mediated depletion of tight junction regulatory proteins, including occludin and zonula occludens-1. On the other hand, limonene treatment significantly decreased matrix metalloproteinase-2 levels in UVB-irradiated HaCaT cells. Based on these results, limonene may have a dermato-protective effect in skin cells by activating the Nrf2-dependent cellular antioxidant defense system.
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Affiliation(s)
- K J Senthil Kumar
- Bachelor Program of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - M Gokila Vani
- Department of Forestry, National Chung Hsing University, Taichung, Taiwan
| | - Sheng-Yang Wang
- Department of Forestry, National Chung Hsing University, Taichung, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
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Liu J, Chen J, Xu B, Lin L, Liu S, Ma X, Liu J. 3,4,5-O-tricaffeoylquinic acid with anti-radiation activity suppresses LPS-induced NLRP3 inflammasome activation via autophagy in THP-1 macrophages. Mol Immunol 2022; 147:187-198. [PMID: 35633614 DOI: 10.1016/j.molimm.2022.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/09/2022] [Accepted: 05/18/2022] [Indexed: 10/18/2022]
Abstract
Damage to normal tissues caused by excessive ionizing radiation (IR) exposure is the major side effect of radiotherapy. Several recent studies have shown that IR-induced damage to tissues leads to a systemic immune response and NLRP3 inflammasome activation in immune cells. 3,4,5-O-tricaffeoylquinic acid (tCQA), extracted from the natural plant Azolla imbricata, relieves inflammation and has radioprotective function. Here, we aimed to investigate the inhibitory effect and molecular mechanism of tCQA on IR-induced NLRP3 inflammasome activation. First, the results of ELISA and qPCR assays showed that tCQA has anti-inflammatory effects in THP-1 cell line and healthy human peripheral blood mononuclear cells. Western blotting and ELISA suggested tCQA could inhibit NF-κB/MAPK signaling pathway, NLRP3 expression and the secretion of IL-1β in lipopolysaccharide (LPS)-stimulated THP-1 macrophages. Then, flow cytometry, LDH assay and western blotting demonstrated that tCQA could inhibit LPS- and nigericin-induced Caspase-1 activation and gasdermin D cleavage, thereby suppressing inflammatory cell death. Furthermore, we found that the autophagy inhibitor chloroquine, not the proteasome inhibitor MG132, could counteract the promoting effect of tCQA on NLRP3 degradation and the inhibitory effect on cell death. Western blotting and autophagosome staining results suggested tCQA could significantly enhance LPS-induced autophagic flux in macrophages and ATG5/ATG7 knockdown reverses the inhibitory effect of tCQA on NLRP3 expression and Caspase-1 activation, indicating that tCQA induces NLRP3 degradation via autophagy. Finally, THP-1 macrophages and BALB/c mice were irradiated with 137Cs γ-rays and tCQA could inhibit IR-induced NLRP3 inflammasome activation both in vitro and in vivo. To conclude, tCQA controls inflammation and NLRP3 inflammasome activation in vitro via NF-κB/MAPK signaling pathway and autophagy, meanwhile inhibits IR-induced NLRP3 inflammasome activation in vivo. Overall, our study provides an experimental and theoretical basis for the application of tCQA as a radioprotectant in clinical radiotherapy.
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Affiliation(s)
- Jiajun Liu
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Jingyun Chen
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Baixue Xu
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Long Lin
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China
| | - Shaoqun Liu
- Key Laboratory of Whole-period Monitoring and Precise Intervention of Digestive Cancer (SMHC), Minhang Hosipital & AHS, Fudan University, Shanghai, 201199, PR China; Department of Surgery, Minhang Hospital, Fudan University, Shanghai, 201199, PR China.
| | - Xiaoying Ma
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China.
| | - Jianwen Liu
- State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, PR China.
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