Immunomodulatory effects of bioactive polysaccharides from Pleurotus pulmonarius on LPS-stimulated THP-1 human macrophages

Edible mushrooms represent valuable reservoirs of bioactive compounds with significant potential for pharmaceutical and nutraceutical applications. Their immunomodulatory effects have been linked to various nutraceutical and therapeutic benefits. This study investigates the immunostimulatory effects of soluble polysaccharides from Pleurotus pulmonarius (PPp) on THP-1 macrophages. Initial assays revealed high carbohydrate and beta-glucan content in PP soluble extracts. Isolated soluble Pleurotus pulmonarius polysaccharides (PPp) induced dose-dependent (10-80 mu g/mL) proliferation of THP-1 cells and upregulated expression of TNF-alpha, IL-1 beta, and IL-6 genes. Additionally, PPp inhibited nitric oxide (NO) production (15%-45%), downregulated inducible Nitric Oxide Synthase (iNOS) gene expression (33%-83%), and suppressed Programmed Cell Death-Ligand 1 (PD-L1) gene expression (69-95%) in LPS-stimulated THP-1 human macrophages. These findings suggest that soluble Pleurotus pulmonarius polysaccharides (PPp) modulates signaling pathways, balancing NO generation and iNOS expression in LPS-stimulated macrophages, signifies the ability of soluble Pleurotus pulmonarius polysaccharides (PPp) to regulate immunity level by polarizing LPS-stimulated macrophages. This study significantly contributes to advancing our understanding of Pleurotus pulmonarius polysaccharides' immunomodulatory properties, offering insights into the nutraceutical value of Pleurotus pulmonarius (PP) as a promising functional food.