Stachybotrys chartarum alters surfactant-related phospholipid synthesis and CTP:cholinephosphate cytidylyltransferase activity in isolated fetal rat type II cells.

Stachybotry chartarum, a fungal contaminant of water-damaged buildingscommonlygrowsondampcellulose-containingmaterials. It produces a complex array of mycotoxins. Their mechanisms of action on the pulmonary system are not entirely clear. Previous studiessuggestsporeproductsmaydepressformationofdisaturated phosphatidylcholine (DSPC), the major surface-active component of pulmonary surfactant (PS). If S. chartarum can indeed affect formation of this phospholipid, then mold exposure may be a significant issue for pulmonary function in both mature lung and developing fetal lung. To address this possibility, fetal rat type II cells, the principal source of DSPC, were used to assess effects of S. chartarum extract on formation of DSPC. Isolated fetal rat lung type II cells prelabeled with 3 H-choline and incubated with spore extract showed decreased incorporation of 3 H-choline into DSPC. The activity of CTP:cholinephosphate cytidylyltransferase (CPCT), the rate-limiting enzyme in phosphatidylcholine synthesis was reduced by approximately 50% by a 1:10 dilution of spore extract. Two different S. chartarum extracts (isolates from S. chartarum (Cleveland) and S. chartarum (Hawaiian)) wereusedtocompareactivityofCPCTinthepresenceofphosphatidylglycerol (PG), a known activator. PG produced an approximate two-fold increase in CPCT activity. The spore isolate from Hawaii did not alter enzyme activity. S. chartarum (Cleveland) eliminated the PG-induced activation of CPCT. These results support previous observations that mold products alter PS metabolism and may pose a risk in developing lung, inhibiting surfactant synthesis. Different isolates of the same species of fungus are not equivalent in terms of potential exposure risks.