| Mycotoxin Adducts on Human Serum Albumin: Biomarkers of Exposure to Stachybotrys chartarum Iwona Yike,1,3 Anne M. Distler,2 Assem G. Ziady,1 and Dorr G. Dearborn1,3 Departments of 1Pediatrics and 2Pharmacology, and 3Mary Ann Swetland Center for Environmental Health, Case Western Reserve University, Cleveland, Ohio, USA Abstract
Objective: Despite the growing body of evidence showing adverse health effects from inhalation exposure to the trichothecene-producing mold Stachybotrys chartarum, controversy remains. Currently, there are no reliable assays suitable for clinical diagnosis of exposure. We hypothesized that satratoxin G (SG) –albumin adducts may serve as biomarkers of exposure to this fungus. Design: We studied the formation of adducts of SG with serum albumin in vitro using Western blots and mass spectrometry (MS) and searched for similar adducts formed in vivo using human and animal serum. Results: Samples of purified human serum albumin that had been incubated with increasing concentrations of SG showed concentration-dependent albumin bands in Western blots developed with anti-SG antibodies. MS analysis found that as many as 10 toxin molecules can be bound in vitro to one albumin molecule. The sequencing of albumin-adduct tryptic peptides and the analysis of pronase/aminopeptidase digests demonstrated that lysyl, cysteinyl, and histidyl residues are involved in the formation of these adducts. Serum samples from three patients with documented exposure to S. chartarum similarly revealed lysine–, cysteine–, and histidine–SG adducts after exhaustive digestion, affinity column enrichment, and MS analysis. These adducts were also found in the sera from rats exposed to the spores of S. chartarum in contrast to control human subjects and control animals. Conclusions: These data document the occurrence of SG–albumin adducts in both in vitro experiments and in vivo human and animal exposures to S. chartarum. Relevance to clinical practice: SG–amino acid adducts may serve as reliable dosimeter biomarkers for detection of exposure to S. chartarum. Key words: biomarkers, satratoxin G, Stachybotrys chartarum, trichothecenes. Environ Health Perspect 114:1221–1226 (2006) . doi:10.1289/ehp.9064 available via http://dx.doi.org/ [Online 26 April 2006]
Address correspondence to D.G. Dearborn, Swetland Center for Environmental Health, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH 44106-4948 USA. Telephone: (216) 368-8521. Fax: (216) 368-4518. E-mail: dxd9@case.edu We thank C. Hoppel and M. Chance for helpful discussions and J. Gower for excellent technical assistance. This work was supported by the Swetland Endowment, the Case Provost Opportunity Fund, and National Institutes of Health Metabolic training grant T23 DK007319 (A.M.D.) . The authors declare they have no competing financial interests. Received 2 February 2006 ; accepted 26 April 2006.
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