Abstract
Purpose: To investigate the potential immune-enhancing effects of fourteen natural plant extracts on mouse macrophage RAW 264.7 cells.Methods: Fourteen plant extracts from 7 different plants were tested on RAW 264.7 cells to determine their immunostimulant activities. Methylthiazolydiphenyltetrazolium bromide (MTT) and Griess assays were performed to evaluate cell viability and nitric oxide (NO) production, respectively. Then, immune related proteins were measured by western blot analysis, while cytokines and phagocytic activity were determined by enzyme-linked immunosorbent assay (ELISA) method.Results: Among the 14 plant extracts, the hot water extract of Agastache rugose was selected based on the screening results on NO production. The hot water extract of A. rugose significantly increased NO production in a concentration-dependent manner without any cytotoxicity. In addition, the expression levels of proteins (iNOS and COX-2) and cytokines (TNF-α, IL-1β, IL-6 and IL-12) closely related to immune reaction were also significantly upregulated. Furthermore, phagocytic activity of RAW 264.7 cells significantly increased following treatment with A. rugosa.Conclusion: The hot water extract of A. rugosa exhibits significant immune-stimulant activity. Therefore, A. rugosa can be used as a natural resource for immune enhancement or dietary supplement.Keywords: Immune enhancing activity, Macrophage polarization, Natural plant extracts, Agastache rugosa, RAW 264.7
Highlights
The immune system is responsible for protection against infections of bacteria, viruses and fungi [1]
The aim of this study is to investigate the immune-enhancing effects of natural product extracts with a focus on the polarization of the rodent macrophage, RAW 264.7 cells
All plant extracts except 20 and 100 μg/mL of hot water extract of Angelica Kiusiana and 100 μg/mL of 80 % ethanol extract of A. rugosa did not show any toxicity as relative cell viability was over 80% compared to vehicle treated group (Figure 1)
Summary
The immune system is responsible for protection against infections of bacteria, viruses and fungi [1]. Macrophage is one of the representatives of innate immune cells which perform first line defense during infection initiates [2,3]. Macrophage is ubiquitously found in almost all tissues and plays an important role in immune reactions like phagocytosis [4,5]. Macrophage has various functions including the production of inflammatory mediators such as nitric oxide, prostaglandins. A proper immune reaction could prevent pathologic and cancerous assault. The causes of immune suppression include stress, environmental toxin, sedentary lifestyle, inadequate sleep, alcohol and tobacco abuse, cortisone, chemotherapy, antibiotics, other drug therapy and infection [11]
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