Induction of cellular and molecular immunomodulatory pathways by vitamin A and flavonoids

Abstract

Introduction A detailed study of reports on the immunomodulatory properties of vitamin A and select flavonoids may pave the way for using these natural compounds or compounds with similar structures in novel drug and vaccine designs against infectious and autoimmune diseases and cancers. Areas Covered Intracellular transduction pathways, cellular differentiation and functional immunomodulatory responses have been reviewed. The reported studies encompass in vitro, in vivo preclinical and clinical studies that address the role of Vitamin A and select flavonoids in induction of innate and adaptive B and T cell responses, including TH1, TH2 and Treg. Expert Opinion While the immunomodulatory role of vitamin A, and related compounds, is well-established in many preclinical studies, its role in humans has begun to gain wider acceptance. In contrast, the role of flavonoids is mostly controversial in clinical trials, due to the diversity of the various classes of these compounds, and possibly due to the purity and the selected doses of the compounds. However, current preclinical and clinical studies warrant further detailed studies of these promising immuno-modulatory compounds.

Vitamin A or E and a catechin synergize as vaccine adjuvant to enhance immune responses in mice by induction of early interleukin‐15 but not interleukin‐1β responses

“…This is the first study in which the combination of vitamins A and E and a catechin synergistically enhanced not only B‐cell responses, but also Th1, Th2 and CD8 + T‐cell responses, in the absence of select innate, pro‐inflammatory responses. Studies on the immunomodulatory properties of vitamins and flavonoids are gaining momentum . Although in a previous publication we had used retinoic acid and catechin hydrate to generate NIDS, in the current study, we successfully replaced catechin hydrate with EGCG, and retinoic acid with RP, because of their low cost for large‐scale manufacturing.…”

“…The immunomodulatory roles of the various vitamins and flavonoids remain controversial as although some studies suggest that some vitamins and flavonoids enhance immunity, other studies, using the same compounds, show that they in fact suppress immunity . Specifically, immunomodulation by vitamins A and D includes both up‐ and down‐regulation of certain immune responses, varying by the type of immune response, pathogen and host …”

Antifatigue Effect of Luteolin‐6‐C‐Neohesperidoside on Oxidative Stress Injury Induced by Forced Swimming of Rats through Modulation of Nrf2/ARE Signaling Pathways

“…Previous studies reported that phytochemicals such as antioxidants absorbed from tea, fruit, and medicinal plants could not only reduce free radical formation and scavenge free radicals but also possess considerable antifatigue activity [14]. Flavonoids from plants are considered to be one of the most effective groups of phytochemicals due to their wide range of pharmacological activities, such as antioxidative, anti-inflammatory, immunomodulatory, antidiabetic, and antitumor effects [15–18]. Flavonoids have also been widely studied as a new group of natural antifatigue substances; many studies have revealed that flavonoid supplementation enhanced the endurance exercise performance of fatigued rats by reducing their muscle fatigue [19, 20].…”

Comparative Safety and Efficacy Profile of a Novel Oil in Water Vaccine Adjuvant Comprising Vitamins A and E and a Catechin in Protective Anti-Influenza Immunity

“…The immunomodulatory properties of each of the components of NIDS have been discussed extensively in two recent reviews [10,11]. Moreover, the adjuvant effect of the NIDS has been demonstrated in two recent publications, in which NIDS was shown to enhance adaptive CD4+ TH, CD8+ IFNγ+, and B cell antibody responses [8,9].…”