Inflammation is a crucial factor in the pathogenesis of numerous diseases. This study sought to evaluate the effects of thymol and carvacrol, the main components of Thymus vulgaris (thyme) essential oil, on transcription factors regulating inflammation. Lipopolysaccharide (LPS)-stimulated J774.1 mouse macrophages were examined by real time-PCR for interleukin (IL)-1b and tumor necrosis factor (TNF)-a gene expression in the presence of these compounds. Levels of inducible phospho-nuclear factor-jB (pNF-jB) p65, activator protein-1 [AP-1(c-Fos/c-Jun)], and nuclear factors of activated T-cells (NFATs) were also measured using Western blots. Levels of phosphorylation of stress-activated protein kinases (SAPKs)/c-Jun N-terminal kinase (SAPK/ JNK), signal transducer, and activator of transcription (STAT-3), p38, IjBa, and NF-jB p65, as well as total levels of IL-1b and TNFa were determined. The results indicated carvacrol significantly reduced both IL-1b and TNFa at the protein and mRNA levels; thymol also significantly reduced IL-1b expression. Western blot analyses of nuclear cell extracts revealed both agents caused significantly decreased expression of c-Fos, NFAT-1, and NFAT-2; decreased expression of c-Jun was only caused by carvacrol. Neither agent inhibited p-NF-jB p65 expression. At the protein level, carvacrol and thymol each caused decreases in inducible phospho-SAPK/JNK and phospho-STAT3 levels, whereas only carvacrol resulted in increased p-p38 levels in the total cell extract. Despite the reduction of phospho-IjBa caused by both agents, p-NF-jB p65 still increased in the presence of carvacrol. Based on these findings, it is concluded that carvacrol and thymol could contribute to reduction of inflammatory responses through modulation of the expression of JNK, STAT-3, AP-1, and NFATs.
Thymol and carvacrol, two main components of thyme, have several valuable effects on the immune system. This study aims to evaluate the effects of these components on T-helper (TH) cell responses and their subsets in mice immunized with ovalbumin. The effects of these components on: a specific in vivo immune response were evaluated by assessing changes in delayed-type hypersensitivity (DTH); ex vivo splenocyte proliferative responses were evaluated using a BrdU assay gene expression of cytokines and key transcription factors involved in T-cells subset differentiation among the mouse splenocytes were assessed using real-time polymerase chain reaction (PCR); and splenocyte cytokine formation (ex vivo) and levels of the cytokines in mouse sera were measured by ELISA. Mice treated with thymol or carvacrol had reduced DTH responses (26% and 50%, respectively) compared with control mice. Thymol and carvacrol each diminished splenocyte proliferation to nearly 65-72% of control levels (p < 0.01). These agents also led to decreased TH1 [interleukin (IL)-2, interferon (IFN)-γ)], TH2 (IL-4) and TH17 (IL-17A) levels in the splenocyte cultures and in the sera of mice but increased levels of IL-10 and transforming growth factor (TGF)-β. Treated immunized mice showed significantly reduced T-box 21 (T-bet) expression from 3.8 [± 0.3]-fold in untreated ovalbumin-immunized mice to 0.9 [± 0.4]-(thymol) and 0.8 [± 0.2]-fold (carvacrol) (p < 0.01). GATA binding protein 3 (GATA-3) expression declined from 3.4 [± 0.4]- to 0.5 [± 0.3]-fold (thymol) and 0.6 [± 0.4]-fold (carvacrol), whereas RORγc decreased from 13.4 [± 1.6]- to 1.5 [± 0.6]-fold (thymol) and 0.8 [± 0.4]-fold (carvacrol) (p < 0.001). As carvacrol and thymol each suppressed the antigen-specific immune response by reducing TH cell-related cytokines\specific transcription factors, this indicated their potential to modulate destructive immune responses attributed to T-cells over-activation.
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