Fungal β-Glucans Shape Innate Immune Responses in Human Peripheral Blood Mononuclear Cells (PBMCs): An In Vitro Study on PRR Regulation, Cytokine Expression, and Oxidative Balance

Fungi are ubiquitous organisms that are capable of transient or persistent colonization in humans. Their polymorphic nature and complex host-mycobiome interactions remain incompletely understood. Emerging evidence highlights the role of resident fungi in modulating immune responses and adapting to host changes, which can trigger a shift from commensalism to parasitism, particularly in immunocompromised individuals. This study evaluated the effects of two major β-glucans-zymosan and curdlan-on the expression of pattern recognition receptors (<i>Dectin1</i>, <i>Dectin2</i>, <i>TLR2</i>, <i>TLR4</i>) in human peripheral blood mononuclear cells (PBMCs). It also examined their impact on reactive oxygen species (ROS) production, cytokine/chemokine gene expression, and antioxidant enzyme expression. Both β-glucans significantly increased the mRNA levels of all tested receptors and enhanced ROS generation. Curdlan downregulated key antioxidant enzymes (<i>SOD1</i>, <i>CAT</i>, <i>GPX1</i>), while zymosan markedly upregulated <i>SOD1</i>. These findings demonstrate that the β-glucans zymosan and curdlan have a substantial influence on PBMC reactivity and oxidative stress responses. Further studies are needed to deepen our understanding of host-fungal interactions and their implications in health and disease.