Activators of tissue proteolysis including Stachybotrys microspora triprenyl
phenol (SMTP)-7 are a new class of agents that are expected to be effective for amelioration of chronic tissue destructive diseases. The present study was performed to examine whether
SMTP-7 is effective for the amelioration or protection of early-stage
IgA nephropathy (IgAN) induced by
nivalenol (NIV) in female BALB/c mice. In Experiment 1, mice were administered NIV at 24 ppm in diet for 8 weeks, and during the NIV treatment, they were intraperitoneally injected with
SMTP-7 (10 mg/kg) three times a week. In Experiment 2, mice were injected similarly with
SMTP-7 during the last 4 weeks of a 16-week NIV treatment. Immunofluorescence analysis revealed an inhibitory effect of
SMTP-7 on the glomerular deposition of
IgA in Experiment 1; however, it was ineffective in Experiment 2. On the other hand,
SMTP-7 did not affect the serum concentration of
IgA in both experiments. These results suggest that
SMTP-7 has a potential to decrease the progression of IgAN induced by NIV through inhibition of local accumulation of
IgA in the glomerular mesangium, while it was ineffective for suppression of
IgA production. On the other hand,
SMTP-7 was found to be ineffective for already deposited
IgA, suggesting that
SMTP-7 may not be effective for ameliorating advanced IgAN.