Agaricus brasiliensis polysaccharides stimulate human monocytes to capture Candida albicans, express toll-like receptors 2 and 4, and produce pro-inflammatory cytokines

 

Priscila Raquel Martins^1 2, Ângela Maria Victoriano de Campos Soares¹, Andrea Vanessa da Silva Pinto Domeneghini³, Márjorie Assis Golim⁴, Ramon Kaneno¹

 

1 Department of Microbiology and Immunology, Botucatu Biosciences Institute, São Paulo State University (UNESP – Univ Estadual Paulista), Botucatu, SP, Brazil.

2 Department of Pathology, Botucatu Medical School, São Paulo State University (UNESP – Univ Estadual Paulista), Botucatu, SP, Brazil.

3 Department of Pathology, Paulista Central University Center (UNICEP), São Carlos, SP, Brazil.

4 Blood Bank Division, Botucatu Medical School, São Paulo State University (UNESP – Univ Estadual Paulista), Botucatu, SP, Brazil.

 

ABSTRACT

Background

Agaricus brasiliensis is a medicinal mushroom with immunomodulatory and antitumor activities attributed to the β-glucans presented in the polysaccharide fraction of its fruiting body. Since β-glucans enhance cellular immunoresponsiveness, in this study we aimed to evaluate the effect of an acid-treated polysaccharide-rich fraction (ATF) of A. brasiliensis on the ability of human monocytes to adhere/phagocyte C. albicans yeast cells, their expression of pattern recognition receptors and their ability to produce cytokines.

 

Methods

Adhesion/phagocytosis of FITC-labeled C. albicans was evaluated by flow cytometry. Cells were incubated with specific fluorochrome-labeled antibodies for TLR2 and 4, βGR and MR and also evaluated by flow cytometry. Monocytes were cultured with ATF, and culture supernatants were collected for analysis of in vitro cytokine production by ELISA (TNF-α, IL-1β, IL-12 and IL-10).

 

Results

ATF significantly increased the adherence/phagocytosis of C. albicans by monocytes and this was associated with enhanced expression of TLR2 and TLR4, while no effect was observed on βGR or MR. Moreover, expression of TLR4 and TLR2 was associated with higher levels of in vitro production of TNF-α and IL-1, respectively. Production of IL-10 was also increased by ATF treatment, but we found no association between its production and the expression of Toll-like receptors.

 

Conclusion

Our results provided us with evidence that A. brasiliensis polysaccharides affect human monocytes probably through the modulation of Toll-like receptors.

 

Key words: Agaricus blazei; Agaricus brasiliensis; Monocytes; Pattern recognition receptors (PPR); Toll-like receptors.

 

Funding

This work was supported by the State of São Paulo Research Foundation (FAPESP – process n. 06/06925-2). PRM and AVSPD were recipients of scholarships from the National Council for Scientific and Technological Development (CNPq).

 

Received: August 18, 2016.

Revised: February 21, 2017.

Accepted: March 23, 2017.

 

Correspondence: rskaneno@yahoo.com.br

 

Authors’ contributions

PRM performed the experimental analysis and wrote the first draft of manuscript. AMVCS took part in the study design and data analysis. AVSPD standardized and helped to prepare the β-glucan extract. MAG took part in data collection and flow cytometry. RK designed and coordinated the study, analyzed data and wrote the final draft. All authors read and approved the final manuscript.

 

Competing interests

The authors declare that they have no competing interests.

 

Consent for publication

Written informed consent was obtained from all patients who were enrolled in this study.

 

Ethics approval and consent to participate

The present study was approved by the Research Ethics Committee of Botucatu Medical School of UNESP (protocol number 05/08).