The Immunomodulatory and Anti-Inflammatory Role of Polyphenols

Abstract

This review offers a systematic understanding about how polyphenols target multiple inflammatory components and lead to anti-inflammatory mechanisms. It provides a clear understanding of the molecular mechanisms of action of phenolic compounds. Polyphenols regulate immunity by interfering with immune cell regulation, proinflammatory cytokines’ synthesis, and gene expression. They inactivate NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) and modulate mitogen-activated protein Kinase (MAPk) and arachidonic acids pathways. Polyphenolic compounds inhibit phosphatidylinositide 3-kinases/protein kinase B (PI3K/AkT), inhibitor of kappa kinase/c-Jun amino-terminal kinases (IKK/JNK), mammalian target of rapamycin complex 1 (mTORC1) which is a protein complex that controls protein synthesis, and JAK/STAT. They can suppress toll-like receptor (TLR) and pro-inflammatory genes’ expression. Their antioxidant activity and ability to inhibit enzymes involved in the production of eicosanoids contribute as well to their anti-inflammation properties. They inhibit certain enzymes involved in reactive oxygen species ROS production like xanthine oxidase and NADPH oxidase (NOX) while they upregulate other endogenous antioxidant enzymes like superoxide dismutase (SOD), catalase, and glutathione (GSH) peroxidase (Px). Furthermore, they inhibit phospholipase A2 (PLA2), cyclooxygenase (COX) and lipoxygenase (LOX) leading to a reduction in the production of prostaglandins (PGs) and leukotrienes (LTs) and inflammation antagonism. The effects of these biologically active compounds on the immune system are associated with extended health benefits for different chronic inflammatory diseases. Studies of plant extracts and compounds show that polyphenols can play a beneficial role in the prevention and the progress of chronic diseases related to inflammation such as diabetes, obesity, neurodegeneration, cancers, and cardiovascular diseases, among other conditions.

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“…PGE 2 is an effective suppressor of TNF‐α production by the inflammatory cells . Also, it was demonstrated that IND increased NF‐κB, as disclosed also in our immunohistochemical findings, with subsequent stimulation of the production of the pro‐inflammatory cytokines as TNF‐α and IL‐1β . Another prospective explanation for the increased levels of TNF‐α and IL‐1β, is that the increased mitochondrial fission, by IND, might be a cause of increased production of pro‐inflammatory cytokines via increased ROS production and NF‐κB expression, these also were explored in our results.…”

Antidiabetic Properties of Curcumin I: Evidence from In Vitro Studies

“…Polyphenols have been established to have antioxidant properties [22] and possess a variety of other specific biological effects. Therefore, these components have the potential to prevent diseases through mechanisms that are dependent and independent of their antioxidant properties [23][24][25].…”

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“…Several polyphenols such as curcumin, quercetin, and catechins exhibit their effects on the balance between secretion of pro-inflammatory and anti-inflammatory cytokines. They inhibit the release of pro-inflammatory cytokines and activate anti-inflammatory cytokines' production [52]. However, curcumin has shown the ability to inhibit the production of TNF-α and some pro-inflammatory interleukins such as IL-1 and IL-6, while increasing the production of anti-inflammatory IL-10 [49,53,54].…”