Effects of therapeutic agents on the inflammatory and fibrogenic factors in IgA nephropathy

It is desirable in the treatment of IgA nephropathy (IgAN) to prevent the downstream events after the immune response has involved the glomerulus. We and others observed that IgA itself could directly activate mesangial cells to produce monocyte chemotactic peptide-1 (MCP-1), interleukin-6 (IL-6) and transforming growth factor-beta (TGF-beta) and this was suppressed by the treatment with steroid or angiotensin receptor blocker (ARB). It was shown in mesangial cells that the increased expression of TGF-beta and plasminogen activator inhibitor-1 induced by angiotensin II was suppressed by the treatment with ARB, calcium channel blocker (CCB), spironolactone or peroxisome proliferator-activated-receptor-gamma (PPAR-gamma) agonist. It was well known in the patients with IgAN that renal or intraglomerular TGF-beta 1 gene expression was increased. Interestingly, treatment with angiotensin-converting enzyme (ACE) inhibitors induced significantly lower renal TGF-beta 1 gene expression in patients with IgAN. It was reported in several studies that urinary levels of IL-6, IL-8, MCP-1 or TGF-beta were increased in patients with IgAN. The increase was suppressed by the treatment with steroid, ARB or ACE inhibitor. More effective agents are necessary to ameliorate pathogenetic abnormalities and so to prevent the progression of IgAN.