Urinary TNF-alpha Excretion Research Articles

Localization of renal oxidative stress and inflammatory response after lithotripsy

OBJECTIVE To determine if the acute renal oxidative stress and inflammation after extracorporeal shock wave lithotripsy (ESWL), thought to be mediated by ischaemia, is most severe in the portion of the kidney within the focal zone of the lithotripter, and if these effects result primarily from ischaemic injury. MATERIALS AND METHODS Pigs (7-8-weeks old) received either 2000 shock waves at 24 kV to the lower-pole calyx of one kidney or unilateral renal ischaemia for 1 h. A third group (sham) received no treatment. Timed urine and blood samples were taken for analysis of lipid peroxidation and the inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). At 4 h after treatment, kidneys were removed and samples of cortex and medulla were frozen for analysis of cytokines and heme oxygenase-1 (HO-1). RESULTS ESWL did not affect urinary excretion of malondialdehyde, but did elicit an eight-fold induction of HO-1 in the portion of the renal medulla within the focal zone of the lithotripter (F2), while remaining unchanged elsewhere in the treated kidney. There was no induction of HO-1 in renal tissue after ischaemia-reperfusion. Urinary excretion of TNF-alpha increased from the lithotripsy-treated kidney by 1 h after treatment, but was unaffected by ischaemia-reperfusion. As with the HO-1 response after lithotripsy, IL-6 increased only in the renal medulla at F2. By contrast, ischaemia-reperfusion increased IL-6 in all samples from the treated kidney. CONCLUSION These findings show that the acute oxidative stress and inflammatory responses to ESWL are localized to the renal medulla at F2. Furthermore, the differing patterns of markers of injury for ESWL and ischaemia-reperfusion suggest that ischaemia is not the principal cause of the injury response after ESWL.

Association of tumor necrosis factor-α with early target organ damage in newly diagnosed patients with essential hypertension

To investigate the relationship between inflammatory parameters [high-sensitivity C-reactive protein (hs-CRP), serum tumor necrosis factor-alpha (TNF-alpha) and urinary TNF-alpha] with subclinical cardiac and renal markers of early target organ damage (TOD) in essential hypertension. Preclinical TOD [left ventricular hypertrophy (LVH) and microalbuminuria (MAB)] was evaluated in 40 newly diagnosed never-treated patients with essential hypertension. Serum and urinary TNF-alpha and hs-CRP were measured as inflammatory parameters. Twenty-one BMI-matched and sex-matched normotensive, healthy individuals were included as control group. The serum levels of hs-CRP and the urinary TNF-alpha excretion were higher in hypertensive patients with MAB, whereas patients with LVH presented higher levels of urinary TNF-alpha. The only difference between hypertensive patients without TOD and healthy controls was the higher urinary excretion of TNF-alpha. Partial correlation analysis showed a significant association between urinary albumin excretion (UAE) and systolic blood pressure (r=0.62, P<0.0001), hs-CRP (r=0.64, P<0.001), urinary TNF-alpha (r=0.55, P=0.001) and Cornell product (r=0.33, P<0.05), whereas the Cornell product was related to UAE (r=0.34, P<0.05), urinary TNF-alpha (r=0.45, P<0.01), and hs-CRP (r=0.32, P<0.05). Multiple regression analysis demonstrated that the parameters independently correlated with UAE were mean blood pressure, Cornell product, hs-CRP and urinary TNF-alpha (adjusted R2=0.77, P<0.001), whereas UAE, urinary TNF-alpha and hs-CRP were independently correlated with Cornell product (adjusted R2=0.66, P<0.001). Multiple logistic regression analysis with TOD as the dependent variable showed that hs-CRP [2.24 (1.17-4.28), P<0.05] and urinary TNF-alpha [1.21 (1.02-1.44), P<0.05] were independently related to TOD. Urinary TNF-alpha is independently correlated with UAE and Cornell product in essential hypertension, suggesting that inflammation may participate in the development of TOD. In addition, urinary excretion of TNF-alpha might be an early marker of preclinical TOD in hypertensive patients. Finally, these results may be a basis to study the effect of the blockade of TNF-alpha activity on the development and progression of TOD in essential hypertension.

Cyclosporin A (CsA) modulates the glomerular production of inflammatory mediators and proteoglycans in experimental nephrosis.

Nephrosis is characterized by glomerular epithelial cell injury and a decrease in the glomerular basement membrane (GBM) proteoglycan content. Although CsA is a useful treatment for a group of patients with this disease, its mechanism of action is unclear. We have previously shown that in experimental nephrosis there is an increase in the glomerular production of tumour necrosis factor-alpha (TNF-alpha) and platelet-activating factor (PAF). Here we have studied the effect of CsA on kidney generation of TNF-alpha and PAF in puromycin aminonucleoside (PAN) nephrosis as well as on the synthesis of proteoglycans by cultured glomerular epithelial cells. Rats receiving CsA had, on day 8 of PAN injection, a significant reduction in proteinuria, blood cholesterol levels and in interstitial mononuclear cells. A diminution in glomerular production and urinary excretion of TNF-alpha and PAF was also noted. In in vitro studies, at 24 h of incubation PAF and TNF-alpha induced in glomerular epithelial cells a significant decrease in proteoglycan synthesis. Neither PAF nor TNF-alpha had any significant effect on glomerular epithelial cell proliferation. CsA alone induced a dose-response increase in proteoglycan synthesis and a slight decrease in cell proliferation. CsA also reversed the inhibitory effect of PAF and TNF-alpha on proteoglycan synthesis. However, CsA did not alter the pattern of proteoglycan production, remaining around 50% chondroitinase ABC-, 15% heparitinase-sensitive. Our results indicate that PAF and TNF-alpha could be implicated in the pathogenesis of nephrosis through the inhibition of proteoglycan synthesis by glomerular epithelial cells. The beneficial effect of CsA in nephrosis may be due to the recovery of the GBM charge selectivity caused by the normalization of glomerular PAF and TNF-alpha synthesis and the increase in proteoglycan synthesis by glomerular epithelial cells.

Effect of TNF-α inhibition on urinary albumin excretion in experimental diabetic rats

The objective is to assess the effect of TNF-alpha inhibition on urinary albumin excretion in experimental diabetic rats. Male Wistar rats, 8-week-old, were categorized into four groups, which were the control (n = 9), diabetes (n = 9), infliximab-treated diabetes (n = 10), and FR167653-treated diabetes (n = 9) groups. Diabetes was induced by intraperitoneal injection of STZ (40 mg/kg). Thereafter, infliximab was injected intraperitoneally once a month (5.5 mg/kg) and FR167653 was administered orally by mixing with the rat chow (0.08%). The effects of infliximab and FR167653 on urinary albumin excretion were observed for 12 weeks. Body weight, blood sugar, 24-h urinary TNF-alpha, and 24-h urinary albumin/creatinine ratio (Ualb/Ucr) levels were determined at 1, 4, 8, and 12 weeks after the STZ-injection. Treatment of rats with STZ caused a significant loss of body weight, as well as polyuria and hyperglycemia within 1 week, while the urinary excretions of albumin and TNF-alpha were increased. Neither infliximab nor FR167653 affected body weight or blood sugar levels, whereas both decreased urinary albumin excretion, together with a modest decrease in the urinary excretion of TNF-alpha. These results suggest a role of TNF-alpha in the pathogenesis of diabetic nephropathy and show that TNF-alpha inhibition is a potential therapeutic strategy.

Use of pentoxifylline in membranous nephropathy

Urinary TNF-alpha excretion correlates with proteinuria in patients with membranous nephropathy (MGN). Pentoxifylline suppresses or reduces the production of TNF-alpha. Between April, 1999 and August, 2000, we did a single-centre, prospective, pilot study to assess the effects of pentoxifylline (1200 mg/day) on proteinuria in patients with idiopathic MGN. Ten patients were included and treated for 6 months. Pentoxifylline significantly decreased proteinuria from 11 g/day [range 4.6-27] to 1.8 (0-10.9); p=0.001). Pentoxifylline may be a safe and effective adjunct to steroids and immunosuppressants in patients with MGN.

Cytokines and adhesion molecules in renal vasculitis and lupus nephritis.

Plasma levels of some pro-inflammatory cytokines and soluble adhesion molecules have been suggested to be useful parameters to assess the activity of antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis and lupus nephritis. We hypothesized that the renal activity of these diseases is better reflected by the urinary excretion and fractional excretion of these molecules. Plasma levels and urinary excretion of tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, IL-8, and the soluble cell adhesion molecules sICAM-1 and sVCAM-1 were measured by enzyme-linked immunosorbent assay (ELISA) in 14 patients with ANCA-positive renal vasculitis (eight active, ANCA-A; six in remission, ANCA-R), six patients with active lupus nephritis (LN), 15 patients with IgA nephropathy (IgAN) and nine healthy subjects. Fractional excretion of selected cytokines and adhesion molecules was also calculated. Patients with ANCA-A had increased urinary excretion and fractional excretion of TNF-alpha (9.27 +/- 3.19% vs 0.58 +/- 0.02%, P < 0.01), IL-6 (120.79 +/- 65.83% vs 1.89 +/- 0.34%, P < 0.01) and increased fractional excretion of IL-8 (23.34 +/- 6.38% vs 2.56 +/- 1.07%, P < 0.01) and sVCAM-1 (0.81 +/- 0.33% vs 0.03 +/- 0.02%, P < 0.01) compared with controls. Urinary excretion of TNF-alpha and IL-6 and fractional excretion of TNFalpha, IL-6 and IL-8 were higher in ANCA-A than in ANCA-R. Patients with LN had increased plasma TNF-alpha (20.52 +/- 2.01 pg/ml vs 12.33 +/- 0.23 pg/ml, P < 0.05) and sVCAM-1 (1537.88 +/- 276.36 ng/ml vs 692.26 +/- 44.42 ng/ml, P < 0.05) and increased urinary excretion of TNF-alpha (2.81 +/- 0.51 microg/mol creat vs 0.98 +/- 0.05 microg/mol creat, P < 0.01), IL-8 (35.78 +/- 14.03 microg/mol creat vs 12.46 +/- 5.19 microg/mol creat, P < 0.05) and sVCAM-1 (48.98 +/- 20.20 microg/mol creat vs 2.92 +/- 1.35 microg/mol creat, P < 0.01) compared with controls. Patients with IgAN had, in comparison with controls only increased plasma TNF-alpha (18.10 +/- 0.57 pg/ml vs 12.33 +/- 0.23 pg/ml, P < 0.05). Urinary excretion and fractional excretion, but not plasma levels, of selected pro-inflammatory cytokines (TNF-alpha, IL-6 and IL-8) were increased in patients with active ANCA-positive renal vasculitis, but not in ANCA positive vasculitis in remission. These parameters may be useful to monitor the activity of this disease.

Adhesion molecules and urinary tumor necrosis factor-α in idiopathic membranous glomerulonephritis

Adhesion molecules are required in several physiological processes, but their altered function/expression is associated with the pathogenesis of inflammatory diseases. In the present study on idiopathic membranous glomerulonephritis (MGN) the expression of adhesion molecules (ICAM-1, VCAM-1, PECAM-1, E-selectin, LFA-1, Mac-1) was analyzed in different cellular compartments of the kidney using an indirect immunoperoxidase technique and monoclonal antibodies. Relationships between the expression of these molecules and the clinical and morphological activity of the disease and the urinary excretion of tumor necrosis factor alpha (TNF-alpha) were studied in 20 patients. The results were compared with the findings in ten normal kidneys and urinary TNF-alpha in 17 healthy subjects. The expression of adhesion molecules in glomeruli and tubules was unchanged apart from a diminished expression of VCAM-1 (P = 0.014) in glomerular parietal epithelial cells and PECAM-1 in glomerular endothelial cells (P < 0.01). Interstitial peritubular capillaries expressed significantly (P = 0.009) more E-selectin compared with the controls. The interstitial compartment had a highly increased number of cells expressing ICAM-1 in MGN (32.4 +/- 4.6 cells/high power field) compared with the controls (9.4 +/- 1.2; P < 0.001). Also, cells expressing VCAM-1 (10.2 +/- 1.6 vs. 2.8 +/- 1.9; P = 0.005). PECAM-1 (25.9 +/- 5.3 vs. 7.4 +/- 2.1; P = 0.006), and LFA-1 (20.4 +/- 3.6 vs. 8.3 +/- 1.5; P = 0.041) were increased in the interstitium. Proteinuria correlated particularly with the expression of E-selectin in peritubular capillaries (r = 0.63, P = 0.004). The number of LFA-1 expressing inflammatory cells in the interstitium correlated with peritubular capillary E-selectin (r = 0.8, P < 0.001) and interstitial ICAM-1 (r = 0.61, P = 0.009) expression, but histological alterations did not correlate with the expression of adhesion molecules. Tumor necrosis factor-alpha excretion was significantly increased in MGN (41 +/- 8 pg/mg creatinine) compared with the controls (13 +/- 2; P = 0.001), and in particular, it correlated with the interstitial expression of LFA-1 (r = 0.71, P = 0.002). This study suggests that active MGN leads not only to proteinuria but also to increased urinary TNF-alpha excretion. These may serve as triggers for the up-regulation of adhesion molecules in the peritubular capillaries and interstitial cells thus enhancing the development of the interstitial injury.