Therapeutic uses of heparinoids in renal disease patients

Sulfated glycosaminoglycans in bladder tissue and urine of rats after acute exposure to paraoxon and cyclophosphamide

Glycosaminoglycans (GAGs) in the urine of Wistar rats, and on the surface of the epithelium and lamina propria of the bladder, were quantitatively assessed before and after acute intoxication with paraoxon or cyclophosphamide. Paraoxon was administered subcutaneously (s.c.) twice with an interval of 1h to a final dose of 275mg/kg; cyclophosphamide was administered intraperitoneally (i.p.) with a single dose of 100mg/kg or to a final dose of 240mg/kg (three times per 80mg/kg every 12h). GAGs on the surface of the epithelium and lamina propria of the urinary bladder of rats were quantitatively determined by Alcian blue dye staining. GAGs in the urine were determined spectrophotometrically with 1-9-dimethyl methylene blue. By 48-96h after intoxication with either paraoxon or cyclophosphamide, statistically significant increases in the concentration of GAGs were obtained both for the tissues of the bladder and the urine of rats. Cyclophosphamide, in contrast to paraoxon, caused the development of hemorrhagic cystitis in the animals. The synthesis of GAGs is considered to be compensatory response to the toxic xenobiotics.

Membranoproliferative glomerulonephritis type II (dense deposit disease): an update

Membranoproliferative glomerulonephritis type II (MPGN II) is a rare disease characterized by the deposition of abnormal electron-dense material within the glomerular basement membrane of the kidney and often within Bruch's membrane in the eye. The diagnosis is made in most patients between the ages of 5 and 15 yr, and within 10 yr, approximately half progress to end-stage renal disease, occasionally with the late comorbidity of visual impairment. The pathophysiologic basis of MPGN II is associated with the uncontrolled systemic activation of the alternative pathway (AP) of the complement cascade. In most patients, loss of complement regulation is caused by C3 nephritic factor, an autoantibody directed against the C3 convertase of the AP, but in some patients, mutations in the factor H gene have been identified. For the latter patients, plasma replacement therapy prevents renal failure, but for the majority of patients, there is no proven effective treatment. The disease recurs in virtually all renal allografts, and a high percentage of these ultimately fail. The development of molecular diagnostic tools and new therapies directed at controlling the AP of the complement cascade either locally in the kidney or at the systemic level may lead to effective treatments for MPGN II.

Pharmacological management of membranous nephropathy

When steroids and immunosuppressive drugs were the only available pharmacological agents used to treat membranous nephropathy, nephrologists were polarized into two groups, those supporting therapy on the basis of the results achieved in controlled trials and those opposed to therapy who contended that the side-effects of therapy were too severe to consider in a disease with a relatively benign course. These two groups are drawing closer as treatments with lesser side-effects emerge. The demonstration that proteinuria accelerates progressive kidney failure in all renal diseases led to a major focus on control of proteinuria. Angiotensin-converting enzyme inhibitors, diuretics and angiotensin II receptor antagonists all play a role. Older methods of treatment that reduce proteinuria are being resurrected. A major development is the demonstration in a randomized study that cyclosporin A is effective in membranous nephropathy. Therefore, although there has been no major recent breakthrough or novel therapeutic agent used in membranous nephropathy, a range of new methods of controlling proteinuria provide some compromise between therapeutic enthusiasm and conservative management in this common disorder.

New Aspects of the Treatment of Nephrotic Syndrome

Abstract.The nephrotic syndrome, caused by glomerulonephritis, diabetes mellitus, or amyloidosis, is still a therapeutic challenge. Newer therapeutic approaches may be sought in the fields of immunosuppression, nonspecific supportive measures, heparinoid administration, and removal of a supposed glomerular basement membrane toxic factor. In immunosuppression, the newer drugs now used in organ transplantation (cyclosporine, tacrolimus, and mycophenolate mofetil) can also be used in the treatment of glomerulonephritis. In nonspecific supportive treatment, angiotensin II receptor antagonists are now used in addition to angiotensin-converting enzyme inhibitors. Positive effects of hydroxymethylglutaryl coenzyme A reductase inhibitors on the nephrotic syndrome have not yet been proven. Cyclooxygenase II inhibitors must be tested but probably have too many renal side effects, similar to those of nonsteroidal anti-inflammatory drugs. Heparinoids or glycosaminoglycans serve as polyanions and thus have protective effects on the negative charge of the glomerular basement membrane. They can now be administered as oral medications. The removal of a supposed glomerular basement membrane toxic factor that induces proteinuria has been attempted for 20 yr and now is usually performed using immunoadsorption. Especially in cases of recurrent nephrotic syndrome after renal transplantation for patients with glomerulonephritis, this approach has been successful in decreasing proteinuria, although in most cases its effect is not lasting but must be continuously renewed.

Pentosan polysulfate treatment reduces cyclosporine-induced nephropathy in salt-depleted rats

BACKGROUND

Long-term cyclosporine (CsA) treatment leads to a decreased glomerular filtration rate, hyalinosis of afferent arterioles, and striped cortical tubulo-interstitial fibrosis. We showed previously that pentosan polysulfate (SP54) prevented the development of microvascular and interstitial lesions in mouse models of progressive glomerulosclerosis. In this study, we examined the effect of pentosan polysulfate on the development of CsA nephropathy.

METHODS

Pair-fed Sprague-Dawley rats were fed a low-sodium (0.03%) diet and received CsA (15 mg/kg, subcutaneously, in olive oil)/5% glucose, pentosan polysulfate (10 mg/kg, subcutaneously in 5% glucose) plus CsA, olive oil/pentosan polysulfate, or olive oil/5% glucose for 30 days. Creatinine clearance (CrCl) was determined at three time points. Afferent arteriolar lesions, glomerular volume, and tubulo-interstitial lesions were quantitated. RNA was extracted from cortex.

RESULTS

Severe lesions were found in the CsA group. A reduction in the number of affected arterioles (32%) and the degree of chronic tubulo-interstitial lesions (44%) was found in pentosan polysulfate/CsA-treated rats. A 20% decrease in glomerular volume was found in CsA rats, but not in pentosan polysulfate/CsA-treated rats. Pentosan polysulfate treatment did not prevent the CsA-induced decrease in CrCl (approximately 30%) at 4 weeks. CsA did not affect cortical endothelial or neuronal nitric-oxide synthase or mRNA levels, but there was small increase in neuronal nitric-oxide synthase mRNA levels in the pentosan polysulfate/CsA-treated group.

CONCLUSIONS

Pentosan polysulfate reduced structural renal lesions in CsA-treated, salt-depleted Sprague-Dawley rats.