Journal of Tea Science Research, 2025, Vol.15, No.1, 30-37 http://hortherbpublisher.com/index.php/jtsr 32 NF-κB and phosphorylated ERK/JNK in macrophages, as well as suppressing inflammatory signaling (Wei et al., 2024). 3.3 Modulation of cytokine expression Tea extracts down-regulate the production of the key pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6, and enzymes COX-2 and iNOS. Suppression was observed in both in vitro and in vivo models, and the formulated combination of tea had enhanced inhibition of these cytokines (Rhee et al., 2018; Dehzad et al., 2025) (Figure 1). Figure 1 The tea extract downregulated the expression of a variety of key pro-inflammatory cytokines (Adopted from Dehzad et al., 2025) 3.4 Influence on immune cell functions Tea modulates immune cell polarization and function. Jing Si Herbal Tea, for example, changes macrophage polarization from the pro-inflammatory M1 to anti-inflammatory M2 phenotype, which inhibits inflammatory reactions in LPS-induced models (Wei et al., 2024). This immunomodulation is critical for controlling overactive inflammation. 3.5 Gut microbiota modulation and anti-inflammatory effects While there is little direct evidence in the provided papers, tea polyphenols are said to influence gut microbiota composition that secondarily modulates systemic inflammation. It is a topic that is still under research, and recent findings support that consumption of tea, modulation of microbiota, and reduced inflammatory markers are interrelated (Rhee et al., 2018). 4 Advances in Experimental and Clinical Studies on the Anti-inflammatory Effects of Tea 4.1 In vitro studies: molecular and cellular inflammation models Various in vitro studies have shown that green and black tea extracts inhibit protein denaturation and downregulate inflammatory markers in cell culture. Green tea and black tea extracts, for example, inhibited protein (albumin) denaturation concentration dependently with higher efficacy being shown by green tea, which presumably is due to the fact that it is rich in more flavonoids (Chatterjee et al., 2012). Other studies using RAW264.7 macrophage cells revealed that tea extracts suppress the secretion of nitric oxide (NO) and inhibit inflammatory enzyme key players, validating their cellular level anti-inflammatory activity (Oliveira et al., 2017; Wei et al., 2024) (Figure 2). Other pairings, such as with white tea and peppermint, were found to have synergistic effect on reducing pro-inflammatory cytokines and inhibiting NF-κB and MAPK pathways (Xia et al., 2020). 4.2 Animal studies: Validation in acute and chronic inflammation models Anti-inflammatory activity of tea has been verified in animal studies in vivo. For instance, decoction of green tea significantly inhibited inflammation in rats with acute models of inflammation, and its activities were as good as standard anti-inflammatory drugs like indomethacin (Chattopadhyay et al., 2012). Preparations of herbal teas, such as Shangqingyin, have also exhibited reduced formation of granuloma and edema in rodent models, showing activity in both acute and chronic inflammation (Tu et al., 2017). The combination of white tea and peppermint also facilitated additional anti-inflammatory outcomes in animal models (Li, 2024).
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