A <i>Hirsutella sinensis</i> Alcohol Extract Exerts Bidirectional Immunoregulatory Effects by Regulating Macrophage Polarization

For background, <i>Hirsutella sinensis</i>, the only anamorphic fungus considered an effective substitute for <i>Cordyceps sinensis</i>, possesses immunoregulatory properties. However, the specific mechanism underlying the immunoregulatory function of <i>Hirsutella sinensis</i> remains unclear. The purpose is to investigate the therapeutic effects of <i>Hirsutella sinensis</i> alcohol extract (HSAE) on immune dysregulation and elucidate the underlying mechanisms involved. For methods, we established inflammatory and immunosuppression models in vitro and in vivo to evaluate the bidirectional immunoregulatory function of HSAE via qRT-PCR and immunoblotting. We also studied its potential mechanism via RNA sequencing and transcriptional analysis. We further established M1 and M2 cell models to explore the effect of HSAE on M1/M2 polarization using qRT-PCR, immunoblotting, and flow cytometry. For results, our data demonstrated enhanced proliferation, phagocytosis, and antipathogenic activities of macrophages. Treatment with HSAE led to increases in the proportions of CD3⁺ and CD4⁺ immune cells in cyclophosphamide-induced immunosuppressed mice. Additionally, HSAE reduced the lipopolysaccharide (LPS)-induced expression of <i>Il1b</i>, <i>Il6</i>, <i>Ifnb1</i>, and <i>Cxcl10</i> by inhibiting the activation of the NF-κB and MAPK pathways in vitro and improved mouse survival by reducing the proportion of M1/M2 macrophages in septic mice. Finally, we found that HSAE inhibited M1 polarization by decreasing the expression of iNOS and CD86 and promoted M2 polarization by increasing the expression of ARG1 and CD206. For conclusions, our study provides evidence that HSAE has the potential to enhance immune responses and suppress excessive inflammation. These effects were realized by modulating macrophage polarization, providing novel insights into the fundamental mechanism underlying the bidirectional immunomodulatory effect of HSAE.