Immunomodulatory Effects of Edible and Medicinal Mushrooms and Their Bioactive Immunoregulatory Products

Abstract

Mushrooms have been valued as food and health supplements by humans for centuries. They are rich in dietary fiber, essential amino acids, minerals, and many bioactive compounds, especially those related to human immune system functions. Mushrooms contain diverse immunoregulatory compounds such as terpenes and terpenoids, lectins, fungal immunomodulatory proteins (FIPs) and polysaccharides. The distributions of these compounds differ among mushroom species and their potent immune modulation activities vary depending on their core structures and fraction composition chemical modifications. Here we review the current status of clinical studies on immunomodulatory activities of mushrooms and mushroom products. The potential mechanisms for their activities both in vitro and in vivo were summarized. We describe the approaches that have been used in the development and application of bioactive compounds extracted from mushrooms. These developments have led to the commercialization of a large number of mushroom products. Finally, we discuss the problems in pharmacological applications of mushrooms and mushroom products and highlight a few areas that should be improved before immunomodulatory compounds from mushrooms can be widely used as therapeutic agents.

Medicinal Mushrooms: Bioactive Compounds, Use, and Clinical Trials

“…The best known and most abundant are α- and β-glucans. Heteroglycans, peptidoglycans, and polysaccharide–protein complexes also contribute to biological activity [ 7 , 8 , 9 ]. They are primarily responsible for immunomodulatory effects due to their ability to bind to specific cell wall receptors and stimulate specific immune responses.…”

“…High terpenoid contents are found in mushrooms belonging to the genus Ganoderma P. Karst. [ 2 , 7 , 9 ].…”

“…Some of them are known for their characteristic and marked immunomodulatory effect. These proteins are indicated as fungal immunomodulatory proteins (FIPs) whose mechanisms of action can be diverse [ 2 , 9 ]. Proteins also include lectins, which bind reversibly to mono- and oligosaccharides with high specificity, recognizing and interacting with various carbohydrates and proteoglycans on the cell surface.…”

“…They are involved in many biological activities, such as innate immunity and cell-to-cell interaction, and their immunomodulatory mechanism varies depending on the origin of the compound. They also have immunomodulatory, antitumor, and antiproliferative properties [ 7 , 9 ].…”

“…In addition to all this, numerous other factors often limit the validity of the clinical studies conducted to date, even in the case of promising results. They often involve too small a sample (among other things, the enormous variability in sample size makes it difficult to compare the various studies), or lack a control or placebo group, or the two groups compared are numerically very different, there is a very frequent lack of replication, adverse events are poorly reported or investigated, the statistical methods are deficient, and the results are poorly described in various respects [ 5 , 6 , 9 , 66 ].…”