Overexpression of SGLT2 in the kidney of a P. gingivalis LPS-induced diabetic nephropathy mouse model.

BACKGROUND: The overexpression of sodium-glucose cotransporter 2 (SGLT2) in diabetic kidneys has been reported. It has also been established that the diabetic glomerular endothelium expresses the toll-like receptors TLR2 and TLR4. The present study aims to examine the renal SGLT2 induction by the TLR2/4 ligand Porphyromonas (P.) gingivalis lipopolysaccharide (Pg-LPS) in mouse diabetic nephropathy. METHODS: Immunohistochemical study and tissue RT-PCR analyses were performed on mouse kidneys in streptozotocin (STZ)-induced diabetic ICR mice (STZ-ICR), in healthy ICR mice administered Pg-LPS (LPS-ICR), and in diabetic ICR mouse kidneys with Pg-LPS-induced nephropathy (LPS-STZ). RESULTS: In the quantitative analysis of blood sugar levels, the mean time to reach 600 mg/dl was shorter in the LPS-STZ than in the STZ-ICR kidneys. The rise in blood glucose levels was significantly steeper in the LPS-STZ than in the STZ-ICR kidneys. According to these data the LPS-STZ model suggests a marked glucose intolerance. The expression of SGLT2 was significantly stronger in the whole of the renal parenchyma of the LPS-STZ than in the LPS-ICR or in the STZ-ICR. The expression of SGLT2 was observed both in the renal tubules and around the renal tubules, and in the glomeruli of the LPS-STZ kidneys. In the analysis by tissue real-time PCR and cell ELISA, the expression of the SGLT2 gene and protein was significantly stronger in the LPS-STZ than in the LPS-ICR or in the STZ-ICR. There were no differences in the renal SGLT2 production in the LPS-ICR and the STZ-ICR kidneys. CONCLUSIONS: Abnormally high renal expression of SGLT2 occurs in diabetic kidneys with P. gingivalis LPS. Periodontitis may be an exacerbating factor in diabetic nephropathy as well as in diabetes.

Immunohistochemical study for the expression of leukocyte adhesion molecules, and FGF23 and ACE2 in P. gingivalis LPS-induced diabetic nephropathy.

OBJECTIVE: The present study aims to examine the expression of leukocyte adhesion molecules and renal metabolic factors in diabetic mouse kidneys with periodontal pathogen Pg-LPS-induced nephropathy. BACKGROUND: We recently reported that the glomerular endothelium expresses toll-like receptor (TLR)2 and TLR4 in diabetic environments and TLR2/4 ligand Porphyromonas (P.) gingivalis lipopolysaccharides (Pg-LPS) induce nephropathy in diabetic mice. It is thought that Pg-LPS promotes the chronic inflammation with the overexpression of leukocyte adhesion molecules and renal-specific metabolic enzymes by the recognition of Pg-LPS via TLR in the diabetic kidneys. There have been no reports of the effects of periodontopathic bacteria on the expression of leukocyte adhesion molecules and the accumulation of physiologically active substances in the kidney. METHODS: The immunohistochemical investigation was performed on diabetic mouse kidney with Pg-LPS-induced nephropathy 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 streptozotocin (STZ)-induced diabetic ICR mice (STZ-ICR), or in healthy ICR mice administered Pg-LPS (LPS-ICR). However, in diabetic ICR mouse kidneys with Pg-LPS-induced nephropathy (LPS-STZ) the expression of VCAM-1 and the accumulation of FGF23 were observed in renal tubules and glomeruli, and the expression of E-selectin was observed in renal parenchyma and glomeruli. The angiotensin-converting enzyme 2 (ACE2) was detected in the proximal tubules but not in other regions of ICR, STZ-ICR, or LPS-ICR. In LPS-STZ ACE2 was detected both in renal tubules as well as in glomeruli. The Mac-1 and podoplanin-positive cells increased in the renal parenchyma with diabetic condition and there was the distribution of a large number of Mac-1-positive cells in LPS-STZ. CONCLUSIONS: The Pg-LPS may induce diabetic renal inflammation such as glomerulosclerosis and tubulitis with infiltration of Mac-1/podoplanin positive macrophages via glomerular overexpression of VCAM-1 and E-selectin, resulting in accumulation of both ACE2 and FGF23 which were unmetabolized with the inflammation-induced kidney damage under the diabetic condition. Periodontitis may be a critical factor in the progress of nephropathy in diabetic patients.

The promotion of nephropathy by Porphyromonas gingivalis lipopolysaccharide via toll-like receptors.

BACKGROUND: Recently, we reported that toll-like receptor (TLR)2 and TLR4 localized on the glomerular endothelium in the glomeruli of streptozotocin (STZ)-induced type 1 diabetic mice and high fat diet feed-induced type 2 diabetic mice, and that periodontal pathogen Porphyromonas gingivalis LPS (Pg-LPS) administration lowered the survival rate of diabetic mice. The present study aims to examine the effect of TLR4 blocking on the suppression of Pg-LPS-induced diabetic nephropathy. METHODS: The survival rate and morphological/biochemical features for streptozotocin-induced diabetic mice with Pg-LPS and TLR4 blocker eritoran administration were investigated by reporter gene assay, urine and blood analysis, immunohistochemistry, and real time-PCR. RESULTS AND CONCLUSIONS: All of the diabetic mice administered Pg-LPS were euthanized within the survival period of almost all of the diabetic mice. The blood urea nitrogen and creatinine, expression of TLR2 and TGF-b, and type 1 collagen accumulation, in the diabetic mice increased significantly with the Pg-LPS administration. In spite of the limited TLR4 activation with Pg-LPS, the TLR4 blocker eritoran decreased blood urea nitrogen and creatinine, and raised the survival rate of the Pg-LPS-administered diabetic mice slightly. The high expression levels of TLR2, TGF-b, and type 1 collagen in Pg-LPS-administered diabetic mice decreased with eritoran. Nuclear STAT3 which enhances TLR2 expression was detected in the TLR2-expressing glomeruli of diabetic mice. The TLR2 and STAT3 gene expression increased by the Pg-LPS administration but decreased with eritoran. These may suggest that Pg-LPS-induced diabetic nephropathy is mainly dependent on TLR2 signaling on glomerular endothelial cells, and that TLR4 blocker eritoran may play a role to slow the progress of diabetic nephropathy.