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Pathogenic mucorales: Deciphering their cell wall polysaccharidome and immunostimulatory potential

Summary

Mucormycosis is a serious fungal infection that primarily affects people with weak immune systems and carries high mortality rates. Researchers studied three common mucormycosis-causing fungi to understand how their outer cell layers interact with the human immune system. They found that all three fungi trigger strong inflammatory responses, which may explain why the disease is so damaging. This research helps us better understand how these infections work and could lead to improved treatments or vaccines.

Background

Mucormycosis is an emerging life-threatening infection caused by pathogenic filamentous fungi of the Order Mucorales, with significantly high mortality in immunocompromised patients. The fungal cell wall, composed of polysaccharides, is the first component to interact with the host immune system. Understanding the cell wall composition and immunomodulatory properties of pathogenic Mucorales species is crucial for better disease management.

Objective

To characterize the cell wall organization, composition, and immunostimulatory potential of three prevalent pathogenic Mucorales species: Rhizopus arrhizus, Mucor circinelloides, and Lichtheimia corymbifera. The study aimed to identify surface-exposed polysaccharides and determine how these cell wall components interact with the human immune system.

Results

All three Mucorales species displayed surface-exposed mannans and species-specific β-1,3-glucan distribution on germ-tubes. Gas chromatography revealed glucose as the major fibrillar polysaccharide, with species-dependent amorphous components. The cell walls contained β-1,3-glucan, β-1,6-glucan, and amylase-digestible glucan. Stimulation of immune cells with spores or cell wall polysaccharides resulted in release of pro-inflammatory cytokines regardless of species.

Conclusion

The three pathogenic Mucorales species exhibit common and species-specific cell wall compositions with differential polysaccharide exposure during germination. Their cell wall polysaccharides are highly pro-inflammatory, suggesting that excessive inflammation may contribute to the immunopathology of mucormycosis. These findings establish a foundation for understanding the cell wall glycobiology and immunobiology of pathogenic Mucorales.
  • Published in:Virulence,
  • Study Type:Laboratory Research Study,
  • Source: PMID: 40621682, DOI: 10.1080/21505594.2025.2528079
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