Induction of leukocyte adhesion molecules and renal physiologically active molecules in Porphyromonas gingivalis lipopolysaccharide-induced diabetic nephropathy

Background We recently reported that the glomerular endothelium expresses toll-like receptor (TLR)2 and TLR4 in diabetic environments and established that the TLR2 ligand Porphyromonas (P.) gingivalis lipopolysaccharides (LPS) induces nephropathy in diabetic mice. It is thought that P. gingivalis LPS promotes the chronic inflammation with the overexpression of leukocyte adhesion molecules and renal-specific metabolic enzymes by the recognition of P. gingivalis LPS via TLR in the diabetic kidneys. The present study aims to examine the expression of leukocyte adhesion molecules and renal metabolic factors in mouse kidneys with periodontal pathogen P. gingivalis LPS-induced diabetic nephropathy that was recently established. Methods The immunohistochemical investigation was performed on mouse kidney with P. gingivalis LPS-induced diabetic nephropathy model with glomerulosclerosis in glomeruli. Results There were no vessels which expressed vascular cell adhesion molecule-1 (VCAM-1), E-selectin, or fibroblast growth factor (FGF) 23 in diabetic mice, or in healthy mice administered P. gingivalis LPS. However, in diabetic mouse kidneys with P. gingivalis LPS-induced nephropathy the expression of VCAM-1 and the accumulation of FGF23 were established in renal tubules and glomeruli, and the expression of E-selectin was established in renal parenchyma and glomeruli. The angiotensin-converting enzyme 2 (ACE2) was detected in the proximal tubules but not in other regions including not in distal tubules of diabetic mice without LPS, and not in healthy mice administered P. gingivalis LPS. In diabetic mouse kidneys with P. gingivalis LPS-induced nephropathy ACE2 was detected both in renal tubules as well as in glomeruli. The macrophage-1 (Mac-1) and podoplanin-positive cells increased in the renal parenchyma with diabetic condition and there was accumulation in P. gingivalis LPS-induced diabetic nephropathy. As the expression of VCAM-1 and E-selectin is upregulated in glomeruli, tubules, and intertubular capillaries, it is thought that the inflammatory infiltration of the monocyte-macrophage lineage promoted in kidneys with P. gingivalis LPS-induced the diabetic nephropathy. Conclusions P. gingivalis LPS may progressively accelerate the development of the renal inflammatory environment in LPS-accumulated glomeruli with the macrophage infiltration via the renal expression of VCAM-1 and E-selectin, and with ACE2 overexpression and FGF23 accumulation. Periodontitis may be a critical factor in the progress of nephropathy in diabetic patients.