Histopathological changes and tumour necrosis factor-alpha, transforming growth factor-beta and tenascin expression in patients with primary type I membranoproliferative glomerulonephritis in remission

Hepatitis B virus X protein up-regulates tumor necrosis factor-α expression in cultured mesangial cells via ERKs and NF-κB pathways

OBJECTIVE

To investigate the effects of hepatitis B virus (HBV) X protein (HBx) on the expression of tumor necrosis factor-α (TNF-α) in glomerular mesangial cells (GMCs) and the underlying intracellular signal pathways.

METHODS

The plasmid pCI-neo-X that carries the X gene of hepatitis B virus was transfected into cultured GMCs. HBx expression in the transfected GMCs was assessed by Western-blot. TNF-α protein and mRNA were assessed by ELISA and semi-quantitative RT-PCR, respectively. Three kinase inhibitors-U0126, an inhibitor of extracellular signal-regulated kinases (ERKs); lactacystin, an inhibitor of nuclear factor-κB (NF-κB); and SB203580, a selective inhibitor of p38 MAP kinase (p38 MAPK) were used to determine which intracellular signal pathways may underlie the action of HBx on TNF-α expression in transfected GMCs.

RESULTS

A significant increase in HBx expression in pCI-neo-X transfected GMCs was detected at 36 h and 48 h, which was not affected by any of those kinase inhibitors mentioned above. A similar increase in the expression of both TNF-α protein and mRNA was also observed at 36 h and 48 h, which was significantly decreased in the presence of U0126 or lactacytin, but not SB203580.

CONCLUSIONS

HBx upregulates TNF-α expression in cultured GMCs, possibly through ERKs and NF-κB pathway, but not p38 MAPK pathway.

All-trans retinoic acid can regulate the expressions of gelatinases and apolipoprotein E in glomerulosclerosis rats

Apolipoprotein E (apoE) is an important plasma protein in cholesterol homeostasis and plays a key role in the pathogenesis of glomerulosclerosis (GS). Gelatinases include matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). The abnormal expressions of gelatinases are implicated in the pathogenesis of extracellular matrix accumulation. All-trans retinoic acid (ATRA) is an import biological agent which can play a protective role against GS. We performed this investigation to explore whether ATRA could regulate the expressions of gelatinases and apoE in the glomerulus of GS rats. 120 Wistar rats were randomly divided into three groups: sham operation group (SHO), glomerulosclerosis model group without treatment (GS) and GS model group treated with ATRA (GA). The GS disease was established by uninephrectomy and adriamycin injection. At the end of 9 and 13 weeks, the relevant samples were collected and determined. Compared with GS group at 9/13 weeks, values of 24-hour urine total protein, 24-hour urine excretion for albumin, blood urea nitrogen, serum creatinine and glomerulosclerosis index, and protein expressions of apoE, transforming growth factor-βl (TGF-β1), α-smooth muscle actin, collagen-IV and fibronectin in glomerulus and mRNA expressions of apoE and TGF-β1 in renal tissue were significantly down-regulated by ATRA (each P<0.01). However, the expressions of MMP-2 and MMP-9 (mRNA, protein and activity) were enhanced in GA group than those in GS group. In conclusion, gelatinases are associated with apoE expression, and ATRA can increase the gelatinases expressions and reduce the accumulation of apoE in glomerulus of GS rats, but the detailed mechanism needs to be elucidated in the future.

apoE expression in glomerulus and correlation with glomerulosclerosis induced by adriamycin in rats

Lipid deposition in glomerulus plays an important role in the progression of glomerulosclerosis (GS), and apolipoprotein E (apoE) is an important protein in cholesterol homeostasis. This investigation was performed to explore whether there exists an association between apoE and GS susceptibility. Eighty Wistar rats were randomly divided into two groups: sham operation group and glomerulosclerosis model group, n = 40. The GS disease in rat was induced by uninephrectomy and injecting adriamycin (5 mg/kg) through the tail vein. At the end of 9 and 13 weeks, 20 rats in each group were killed and the relative samples were collected. Serum creatinine, blood urea nitrogen, and 24-h urine protein were determined. Immunohistochemical analysis was performed on renal tissue to detect the expression of apoE, collagen IV, fibronectin, α-smooth muscle actin, and transforming growth factor-β1 in glomerulus. Real-time reverse transcription polymerase chain reaction was conducted to detect the apoE mRNA expression in renal tissue. Compared with sham operation group at the end of 9/13 weeks, glomerulosclerosis model group exhibited levels of serum creatinine, blood urea nitrogen, 24-h urine protein, and a glomerulosclerosis index that were significantly elevated ( p < 0.01), and collagen IV, fibronectin, α-smooth muscle actin, and transforming growth factor-β1 protein expression and apoE expression (protein and mRNA) were significantly upregulated (p < 0.01). In conclusion, apoE can increase the accumulation of extracellular matrix in glomerulus and may take part in the progression of GS.