Immunomodulatory activity of Pleurotus pulmonarius crude extract to human monocyte against Cryptococcus neoformans

Treatment of Cryptococcus neoformans infection is still challenging due to high side effects and acquired drug resistance. Eliminating fungal infection requires monocytes and macrophages, which are weakened by the non-protective type-2 immune response induced by the pathogen. Pleurotus pulmonarius (PP) is an edible mushroom rich in bioactive molecules, particularly β-glucan. This study aimed to investigate the immunomodulatory activities of PP crude extract on monocytes and macrophages against C. neoformans.

PP was extracted using a hot aqueous method and precipitated with absolute ethanol. Glucan content was assessed by colorimetric assay. The cytotoxicity of PP crude extract was tested using an MTT assay. The immunomodulatory activities and preventive potential of PP crude extract for C. neoformans infection were investigated using human THP-1 monocyte and THP-1-derived macrophage models. Proinflammatory and anti-inflammatory cytokine production was evaluated using RT-qPCR and ELISA. Immune mechanisms related to C. neoformans clearance were studied, including phagocytosis, ROS production, macrophage polarization, and antifungal killing.

The result showed that PP crude extract contains α-glucan (14.72% w/w) and β-glucan (11.75% w/w). The immunomodulatory activities of PP crude extract on the expressions of TNFA, IL1B, IL6, and MCP1/CCL2 were observed in THP-1 cells. This finding corresponds to the significant increase in TNF-α level measured by ELISA. Moreover, PP crude extract enhanced the release of TNF-α and IL-10 from THP-1-derived macrophages. Interestingly, pre-exposure to PP crude extract elicits preventive potential for controlling C. neoformans infection. A significant increase in type 1 cytokines was observed in C. neoformans-infected monocytes and macrophages. While C. neoformans induced M2 polarization, this phenotype was attenuated in PP-trained macrophages partly through MCP1/CCL2 expression and CD206 M2 suppression. Moreover, 100 µg/mL of PP crude extract pretreatment could impair C. neoformans intracellular proliferation in THP-1-derived macrophages and upregulate ROS production.

This study highlights the immunomodulatory potential of PP crude extract as a plant-based immunomodulator to enhance protective antimicrobial responses, particularly through ROS-mediated mechanisms of antifungal immunity. These findings support its potential application in developing natural therapeutic supplements, functional foods, and trained immunity-based strategies as alternative approaches to strengthening host defense against infections.