Background: Perilla frutescens (perilla) is a herbal medicine used in Japanese traditional Kampo medicine. The present study was conducted to evaluate the anti-nephritic effects of perilla in HIGA mice that spontaneously develop high levels of serum immunoglobulin A (IgA) along with mesangial IgA deposition.
Methods: A perilla decoction and its major active constituent, rosmarinic acid (RsA), were orally administrated to 10-week-old HIGA mice for 16 weeks. At study completion, we measured proteinuria and serum IgA levels and generated histological scores from kidney specimens. In addition, we measured concentrations of IgA in culture media of intestinal Peyer's patch cells and spleen cells obtained from the HIGA mice.
Results: Perilla suppressed proteinuria, proliferation of glomerular cells, serum levels of IgA, glomerular IgA and IgG depositions in HIGA mice. Cultured Peyer's patch cells and spleen cells from perilla-treated mice produced significantly less IgA than controls. Rosmarinic acid, by itself, suppressed serum IgA levels and glomerular IgA deposition in HIGA mice. Cultured spleen cells from RsA-treated mice produced less IgA than controls.
Conclusions: The perilla decoction may suppress IgA nephropathy, in part, through modulation of the intestinal mucosal immune system. These effects were caused by RsA acting synergistically with other constituents.