No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Abstract 2594: Chamomile (Matricaria chamomilla L.) upregulates heme oxygenase-1 through activation of ERK-Nrf2 signaling: Cytoprotective mechanism against oxidative damage
Abstract
Protection of cells from oxidative insult could be attained by directly scavenging the reactive oxygen species or more significantly by stimulating the intracellular antioxidant defense through induction of antioxidant gene expression. It has been well documented that the transcriptional activation of Nrf2 in response to oxidative stress results in increased nuclear translocation and its binding to the antioxidant response elements (AREs) found in the promoters of genes, encoding antioxidant enzymes. Studies have demonstrated that Mitogen Activated Protein Kinase (MAPK) family is important in modulating ARE driven gene expression via Nrf2 activation. In the present study, we investigated which particular MAPK family member plays an important role in the regulation of chamomile-induced Nrf2-dependent ARE activity and ARE-driven antioxidant gene expression in mouse RAW 264.7 macrophage cells. We used aqueous chamomile extract (5, 10, 20 and 40µg/mL) obtained from dried flowers with and without MAPK pharmacological inhibitors to investigate their effect on Nrf2 activation. Pretreatment of macrophages with chamomile significantly induced the expression of antioxidant gene, heme oxygenase (HO)-1 mRNA and protein in concentration and time dependent manner. Chamomile exposure increased the nuclear Nrf2 levels which correlated with Nrf2 phosphorylation and its dissociation from Keap1 in both concentration and time dependent manner. Furthermore, chamomile treatment increased the phosphorylation of ERK1/2, but not other kinases, which might result in Nrf2 phosphorylation. Treatment of macrophages with 5µM U0126 (ERK1/2 inhibitor) was able to reduce chamomile-induced ERK phosphorylation, as well as Nrf2 phosphorylation, affecting the levels of HO-1. To confirm the role of Nrf2 in the induction of HO-1, knockdown of Nrf2 using siRNA in the macrophages resulted in significant inhibition of HO-1 expression. Furthermore, chamomile protected the cells against H2O2-induced oxidative stress and this protective effect was inhibited by U0126 and ZnPP (Zinc protoporphyrin-10µM), a HO-1 inhibitor. Taken together, these data suggest that chamomile augments cellular antioxidant defense capacity through induction of HO-1 via ERK-Nrf2-ARE signaling pathway, thereby protecting the cells from oxidative stress.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2594. doi:1538-7445.AM2012-2594
Introduction
Chronic inflammation is a hallmark of chronic wounds and inflammatory skin diseases. Due to a hyperactive and prolonged inflammation triggered by proinflammatory immune cells, transitioning to the repair and healing phase is halted. T cells may exacerbate the proinflammatory milieu by secreting proinflammatory cytokines. Chamomilla recutita L. (chamomile) has been suggested for use in several inflammatory diseases, implying a capability to modulate T cells. Here, we have characterized and compared the effects of differently prepared chamomile extracts and characteristic pure compounds on the T cell redox milieu as well as on the migration, activation, proliferation, and cytokine production of primary human T cells.
Methods
Phytochemical analysis of the extracts was carried out by LC-MS/MS. Primary human T cells from peripheral blood (PBTs) were pretreated with aqueous or hydroethanolic chamomile extracts or pure compounds. Subsequently, the effects on intracellular ROS levels, SDF-1α induced T cell migration, T cell activation, proliferation, and cytokine production after TCR/CD3 and CD28 costimulation were determined. Gene expression profiling was performed using nCounter analysis, followed by ingenuity pathway analysis, and validation at protein levels.
Results
The tested chamomile extracts and pure compounds differentially affected intracellular ROS levels, migration, and activation of T cells. Three out of five differently prepared extracts and two out of three pure compounds diminished T cell proliferation. In line with these findings, LC-MS/MS analysis revealed high heterogeneity of phytochemicals among the different extracts. nCounter based gene expression profiling identified several genes related to T cell functions associated with activation and differentiation to be downregulated. Most prominently, apigenin significantly reduced granzyme B induction and cytotoxic T cell activity.
Conclusion
Our results demonstrate an anti-inflammatory effect of chamomile- derived products on primary human T cells. These findings provide molecular explanations for the observed anti-inflammatory action of chamomile and imply a broader use of chamomile extracts in T cell driven chronic inflammatory diseases such as chronic wounds and inflammatory skin diseases. Importantly, the mode of extract preparation needs to be considered as the resulting different phytochemicals can result in differential effects on T cells.
Ethnopharmacological relevance:
Chamomile (Matricaria chamomilla L.) is a popular herbal tea for the treatment of hepatitis and cholecystitis in traditional Uygur medicines.
Aim of the study:
To investigate the anti-inflammatory activity and chemical composition of M. chamomilla, and clarify its molecular mechanism.
Materials and methods:
M. chamomilla was extracted with 75% ethanol and then extracted with different solvents to obtain five fractions, namely petroleum ether fraction (EOPE), dichloromethane fraction (EOD), ethyl acetate fraction (EOEA), n-butanol fraction (EOB), and water fraction (EOW). Cytotoxicity and the effect on the nitric oxide (NO) production of RAW264.7 cells induced by LPS of the five fractions were screened, and the most active one (EOD) was selected for further investigations. The components of EOD were identified by LC-MS/MS analysis in combination with comparison of retention time and UV absorption with authentic compounds by HPLC. In addition, five most abundant compounds of EOD were isolation by column chromatography and semi-preparative HPLC and their structures were further confirmed by HRMS and NMR data analysis and comparison with data in literatures. Then the underlying anti-inflammatory mechanism of EOD were predicted through Network pharmacology using the identified compounds from EOD, and further verified by Western Blot and ELISA experiments.
Results:
EOD showed the most significant inhibition ratio against NO in RAW264.7 cells without toxicity among the tested five fractions. Thirty-seven compounds including flavonoid-O-glycoside, flavonoid aglycone, methylated flavonoid aglycone, phenolic acid, coumarin, sesquiterpene, and triterpene were identified from EOD by LC-MS/MS and comparison with authentic compounds. The five most abundant compounds in EOD were isolated and determined to be axillarin (26), tricin (30), chrysoeriol (31), centaureidin (33) and chrysosplenetin (35). IL-6, NF-κB, ERK1 and ERK2 cascade, TNF were the most important anti-inflammatory targets of EOD predicted by Network pharmacology. Western Blot and ELISA experiments revealed that EOD significantly decreased the protein expression levels of inflammatory factors (PGE2, MCP-1, IL-6, TNF-α), iNOS, COX-2, NF-κB (p-P65 and p-IκBα), MAPKs (p-p38, p-ERK and p-JNK), and increased the protein expression levels of Nrf2, HO-1 and CYP2E1. In addition, EOD blocked the p65 protein into the nucleus and promoted the nuclear translocation of Nrf2 in RAW264.7 cells induced by LPS.
Conclusion:
M. chamomilla exerted anti-inflammatory effect via NF-κB, MAPK and Nrf2/HO-1 pathways. It could be further applied as a safe anti-inflammatory agent from natural source.
ResearchGate has not been able to resolve any references for this publication.