# Effect of yeast probiotic Saccharomyces boulardii cell wall extract on Aspergillus fumigatus allergenicity in A549 cells

## TL;DR

This study shows that a yeast probiotic extract can reduce the allergenic effects of a fungus linked to respiratory allergies.

## Contribution

The novel contribution is demonstrating that Saccharomyces boulardii cell wall extract reduces Aspergillus fumigatus allergenicity and inflammatory cytokine expression in lung cells.

## Key findings

- S. boulardii cell wall extract reduced A. fumigatus protease activity and Asp f1 gene expression.
- The extract downregulated IL-13 and IL-17 expression in A549 cells exposed to A. fumigatus conidia.
- Results suggest S. boulardii could be a candidate for treating Aspergillus-related allergies and asthma.

## Abstract

Interest in probiotic use for respiratory allergies has increased. In this regard, the present study aimed to evaluate the effect of cell wall
extract of Saccharomyces boulardii on Aspergillus fumigatus as an allergenic fungus and its effectiveness in reducing inflammatory cytokines
in A549 cells sensitized with A. fumigatus conidia.

Cell wall of S. boulardii was prepared and challenged by A. fumigatus conidia at various concentrations. Secretory protease activity was tested using the Casein method.
The A. fumigatus allergen 1 (Asp f1) gene expression was calculated by quantitative real-time polymerase chain reaction (qRT-PCR).
In another experiment, qRT-PCR was used to examine gene expression of interleukin 13 and interleukin 17 by A549 lung epithelial cells exposed to A. fumigatus conidia
and treated with different concentrations of S. boulardii cell wall extract.

Saccharomyces boulardii cell wall extract significantly reduced the protease activity of A. fumigatus at concentrations of 10 and 20 mg/ml (P<0.05).
The Asp f1 gene expression was significantly down-regulated in each concentration of S. boulardii cell wall extract (P<0.05). Aspergillus fumigatus conidia
upregulated the expression of IL-13 and IL-17 in A549 cells, and S. boulardii cell wall extract could downregulate the expression of the mentioned cytokines
at concentrations of 10 and 20 mg/ml (P<0.05).

According to the results, it can be concluded that S. boulardii cell wall extract could be a candidate for IL-13- and IL-17-induced Aspergillus-mediated allergy and asthma therapies.
Nevertheless, future studies need to be conducted on the safety of S. boulardii cell wall extract in vivo and its effects on other arms of allergic hypersensitivity.