The Biocontrol Fungus Trichoderma stromaticum Downregulates Respiratory Burst and Nitric Oxide in Phagocytes and IFN-Gamma and IL-10

Abstract

Trichoderma stromaticum, a biocontrol agent of the cacao witches' broom pathogen Moniliophthora perniciosa, has been used in Brazil as part of the integrated pest management of cacao. At the present time, little is known about the effects of T. stromaticum on the modulation of in vitro or in vivo immune responses. The present study examined the interaction of T. stromaticum spores with cellular and molecular components of the immune system following intranasal sensitization of mice. Our results showed that T. stromaticum spores prevented the expression and production of inflammatory mediators in macrophages stimulated with interferon (IFN)-γ plus lipopolysaccharide (LPS) and neutrophils stimulated with phorbol myristate 13-acetate (PMA). Quantitative polymerase chain reaction (qPCR) assays revealed that T. stromaticum spores inhibited the expression of dectin-1 and Toll-like-receptor (TLR)2/TLR4. Intranasal injection of BALB/c mice and subsequent challenge with spores of T. stromaticum induced a discrete inflammatory response in the lungs. Interestingly, the spores inhibited local and systemic production of the regulatory IL-10 and proinflammatory IFN-γ cytokines. In addition the spores presented an antiproliferative effect on spleen cells. These findings showed that the biopesticide T. stromaticum may exert immunosuppressive effects in vitro and in vivo.

Acknowledgments

The authors are indebted to Dr. Alan Pomella for providing the T. stromaticum strain ALF64 and to Dr. Aline Oliveira da Conceição for critical reading of the article. We also appreciate the technical assistance provided by Candice M. B. Santos, Cristiano Villela Dias, Tania Barth, and Dr. Myrian Morato Duarte. This work was supported by grants (APRO267/2005) from FAPESB (the State of Bahia Research Foundation). E.R.A.F. is a recipient of a master's degree fellowship from FAPESB; T.U.M. was supported by FAPEMIG (the State of Minas Gerais Research Foundation). A.M.C.F. and N.M.S. are recipients of research fellowships from CNPq (National Council for Scientific and Technological Development, Brasília, Brazil).