Background: Glomerular crescents play an important role in progressive glomerular injury. The lesions consist of epithelial cells, macrophages and deposits of fibrin and extracellular matrix. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) are members of chemokine subfamilies. MCP-1 and MIP-2 are potent chemoattractant leukocyte cytokines, and they may be involved in crescent formation. Thrombin participates in fibrin formation. We hypothesized that thrombin stimulates the production of MCP-1 and MIP-2 by glomerular epithelial cells (GECs).
Methods: Cultured rat GECs from the 19th to the 24th passage were used. We incubated GECs with or without thrombin to examine the effect of thrombin on the production of MCP-1 and MIP-2. The levels of MCP-1 and MIP-2 were measured in the cell supernatants by enzyme-linked immunosorbent assay (ELISA). The mRNA expressions of MCP-1 and MIP-2 were analysed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). We also examined the inhibitory effect of argatroban, a synthetic thrombin inhibitor, and prednisolone in the production of MCP-1 and MIP-2 stimulated by thrombin.
Results: Thrombin stimulated the production of MCP-1 and MIP-2 in a dose- and time-dependent manner. Thrombin also enhanced the mRNA expressions of MCP-1 and MIP-2 in the GECs. The stimulating effect of thrombin on the production of MCP-1 and MIP-2 was inhibited by the addition of argatroban or prednisolone.
Conclusions: We demonstrated a novel role of thrombin: it stimulates the production of MCP-1 and MIP-2 by GECs. It is clinically important that the inhibition of these chemokines leads to the improvement of crescentic glomerulonephritis. Anti-thrombin drugs and prednisolone may be useful in treating crescentic glomerulonephritis.