Recurrent immunoglobulin A nephropathy after renal transplantation: a significant contributor to graft loss

BACKGROUND

Although most transplanted patients with underlying IgA nephropathy (IgAN) develop histological recurrence, its clinical relevance is considered low.

METHODS

We performed a single-center analysis of 61 renal transplant patients with IgAN.

RESULTS

Forty-four percent of the patients showed a stable graft function. Progressive graft dysfunction apparently due to recurrent IgAN occurred in 23% of the patients (16% required dialysis). Five patients were retransplanted, and three again developed dialysis-dependent renal failure apparently due to recurrent IgAN. In 20% of the patients, chronic transplant dysfunction was due to other reasons, whereas no reason was identified in 13% of the patients. Neither findings before transplantation, the ACE genotype, the type of immunosuppression, nor the course after transplantation predicted transplant dysfunction due to recurrent IgAN. Follow-up after transplantation was longer in the group with dysfunction due to recurrent disease than in the group with dysfunction due to chronic rejection or in the stable group.

CONCLUSION

Recurrent IgAN is a clinically relevant problem in renal transplant patients. Its importance may have been underestimated in the past due to inadequate lengths of follow-up.

Reactive oxygen species and antioxidant defense in puromycin aminonucleoside glomerulopathy

Results from several radical scavenger studies indirectly suggested an involvement of reactive oxygen species in the pathogenesis of puromycin aminonucleoside glomerulopathy. In this study, generation of reactive oxygen species was examined directly in glomeruli isolated from rats in the acute phase of puromycin aminonucleoside nephrosis and related to the changes in the glomerular antioxidant defense. Five and nine days after puromycin aminonucleoside injection, gross proteinuria, reduced creatinine clearances, and typical changes of glomerular morphology were present. Levels of reactive oxygen species were increased eightfold in glomeruli isolated 15 min after puromycin aminonucleoside injection, returned to baseline levels on days 1 and 5 after injection, and rose again to 14-fold on day 9 after injection, as determined by chemiluminescence with luminol. Further analysis of increased glomerular radical generation, using the chemiluminescence enhancer lucigenin and different radical scavengers, suggested a predominant involvement of hydroxyl radical and hydrogen peroxide in the initial increase in reactive oxygen species 15 min after puromycin aminonucleoside. Nine days after induction of nephrosis, primarily superoxide anion and hydroxyl radical were found to contribute to increased reactive oxygen species. Despite oxidative stress, antioxidant enzymes were not induced in the course of nephrosis. On the contrary, catalase and glutathione peroxidase activities declined 9 d after puromycin aminonucleoside injection. The results indicate that a transient increase in glomerular reactive oxygen species is sufficient to induce the oxidative glomerular injury observed in this model and that the glomerulus may not necessarily respond to oxidative stress with an induction of antioxidant enzymes.

Beta 2-microglobulin associated amyloidosis: a vanishing complication of long-term hemodialysis?

Beta 2-microglobulin associated amyloidosis (A beta 2m amyloidosis) is considered an inevitable complication of chronic hemodialysis, particularly in hemodialysis with cellulose based membranes. We performed a single center study to assess the prevalence of A beta 2m amyloidosis in 1988 versus 1996. Randomly selected patients, studied in 1988, were matched for time on hemodialysis (mean 71 months, range 3 to 207) and age (mean 51 years, range 22 to 80) with patients of the 1996 population. Compared to 1988 patients, the 1996 patients exhibited a lower prevalence of carpal tunnel syndrome (7 of 43 in 1988 vs. 1 of 43 in 1996; P < 0.001) and radiological evidence of A beta 2m amyloidosis (13 of 34 patients vs. 3 of 34 patients positive; P < 0.001; and 33 of 272 possible sites affected in 1988 vs. 7 of 272 sites in 1996 patients; P < 0.05). Compared to the 1988 population, the 1996 population exhibited significantly lower serum aluminum levels, lower average serum creatinine (but not urea) levels, more frequent therapy with erythropoietin, less home hemodialysis, longer hemodialysis time using high-flux synthetic dialysis membranes (mean of 13% vs. 6% of the total hemodialysis time in the 1988 group), and more frequent usage of reverse osmosis water plus bicarbonate buffer for dialysate preparation. We conclude that the prevalence and severity of A beta 2m amyloidosis unexpectedly decreased by about 80% in our center between 1988 and 1996. Given the relatively short times spent on high flux hemodialysis in both groups, increased beta 2-microglobulin removal is unlikely to account for this phenomenon. Rather, other factors, for example, dialysate composition and purity, may be involved.

Assessment of long-term risks for living related kidney donors by 24-h blood pressure monitoring and testing for microalbuminuria

Our aim was to assess the long-term risks for kidney donors of developing arterial hypertension and hypertension-associated diseases or hyperfiltration injury of the remaining solitary kidney. We conducted a cross-sectional study in which 29 donors who were nephrectomized at our center between October 1973 and March 1990 were enrolled. At the time of evaluation median age was 54 (37-70) yr. Since kidney donation an average time interval of 11.1 +/- 3.8 yr had elapsed. Body weight, casual blood pressure, S-creatinine and proteinuria were recorded. In 28/29 donors 24-h blood pressure monitoring was performed; all 29 were tested for microalbuminuria (MAU). The patient history was checked for treatment with antihypertensives, coronary heart disease and diabetes mellitus. From all 29 kidney donors surveyed up to 19.8 yr none developed marked renal insufficiency: median S-creatinine was 1.0 mg/dl (range 0.7-1.6), only 3 donors had a S-creatinine > 1.3 mg/dl. Glomerular filtration rate (GFR) decreased in an age-dependent manner. While all donors had been normotensive without an antihypertensive treatment at time of nephrectomy, actually 29% proved to be hypertensive with average values > 130/80 mmHg in the 24-h assessment. 5/29 donors received antihypertensives, 3 of whom nevertheless were hypertensive. Day-night profile was lost in 2 patients. After donation one patient developed coronary heart disease. 7/29 donors (24%) displayed positive testing for MAU, furthermore one had proteinuria (approx. 300 mg/l). MAU was associated in one case with slightly elevated S-creatinine (1.3 mg/dl) and in 3 cases with arterial hypertension. In the long-term course living related kidney donors do not seem to be at risk for developing hypertensive disorders more often than the general population. The prevalence of MAU in the 29 cases studied was higher than so far described for healthy subjects. This may reflect subclinical hyperfiltration damage of the glomerulus. Progressive renal insufficiency with clinical relevant function loss of the remaining solitary organ, however, was not observed up to 19.8 yr after kidney donation.

Cationic dextran induces mesangioproliferative nephritis in rats independent of glomerular IgA deposition

BACKGROUND

Dextran-induced mesangioproliferative glomerulonephritis in mice and, as recently reported, in rats is used as a model of IgA nephropathy. The pathogenetic role of the glomerular IgA deposits in this model, however, is unclear since IgG is often deposited in parallel.

METHODS

Lewis rats were immunized with cationic DEAE-dextran. Following this, rats received 5 x/week i.v. injections of 3 mg DEAE-dextran each, from days 20 to 80 and were then followed until day 120.

RESULTS

Rats developed transient proteinuria (range 63-152 mg/24 h) and haematuria on day 80. Renal biopsies obtained at days 60, 80, 100 and 120 showed mild to severe mesangioproliferative changes at days 80 and 100 which did not persist at day 120. Electron-microscopy revealed mesangial immune deposits, signs of endothelial activation and vacuoles in mesangial cells and podocytes. Compared to normal, age-matched controls, in the nephritic rats significant (P < 0.05) increases were noted for glomerular total cellularity, alpha-smooth-muscle actin expression (a marker of activated mesangial cells), monocyte/macrophage counts, and matrix proteins. Using three different antibodies, no evidence of glomerular IgA deposition was detected at any time point. In contrast, glomerular IgG, IgM, C3, and occasional small C5b-9 deposits were present in nephritic rats. Circulating IgG but not IgA anti-dextran antibodies could be demonstrated in nephritic rats.

CONCLUSIONS

The data confirm that mesangioproliferative glomerulonephritis can be induced in rats by immunization and chronic challenge with cationic dextran. Our data also show that in rats glomerular IgG deposition rather than IgA, appears to play an important pathogenetic role in this mesangioproliferative glomerulonephritis model.

Complexed plasma elastase as an in vivo marker for leukocyte activation in antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

It has been postulated that antineutrophil cytoplasmic antibody (ANCA)-induced degranulation of primed granulocytes and monocytes is involved in the pathogenesis of ANCA-associated vasculitis. Since elastase is the major lysosomal protein released during leukocyte degranulation, we investigated cell activation in vivo in patients with ANCA-associated vasculitis by determining complexed plasma elastase levels.

METHODS

Plasma elastase complexed with alpha1-antitrypsin was measured in 20 patients with ANCA-associated vasculitis, using an immunoactivation assay. In parallel, C-reactive protein (CRP) and ANCA levels were determined and clinical disease activity was assessed.

RESULTS

Complexed elastase levels were significantly elevated in patients with ANCA-associated vasculitis who had not received immunosuppressive therapy (mean +/- SD 71.5 +/- 22.6 microg/liter), compared with healthy volunteers (12.2 +/- 11.4 microg/liter; P < 0.001). Elastase decreased significantly after 2 weeks (46.5 +/- 26.8 microg/liter; P < 0.01) and further after 8-10 weeks of immunosuppressive treatment (28.1 +/- 13.4 microg/liter; P < 0.02), in correlation with decreasing vasculitis activity. Concomitantly, ANCA titers and CRP levels decreased.

CONCLUSION

These data support the theory that, by the release of lysosomal proteinases, leukocyte activation may be involved in the pathogenesis of ANCA-associated vasculitis. In addition, plasma elastase may be used as a marker for disease activity.

Risk of renal cell carcinoma after kidney transplantation

Between December 1968 and July 1995, 2372 renal transplant recipients were seen regularly in our outpatient clinic. 154 patients (6.5%) of these subsequently developed a malignant tumor. One of the most frequently observed malignancies was a renal cell carcinoma in the native kidneys, found in 12 patients (7.8%; i.e. 0.5% of the total population), two of them with analgesic nephropathy and one with adult polycystic kidney disease. So-called acquired cystic kidney disease of the native kidneys was found in 73% of the patients with renal cell carcinoma. In the patients with renal cell carcinoma the median age at transplantation was 43.9 (39-55) yr. The median time from onset of end-stage renal failure and from transplantation to the appearance of the tumor amounted to 117.3 (43-206) and 75.8 (5-164) months, respectively. Despite nephrectomy, four patients died of the cancer (6-57 months). As a consequence we suggest a regular sonographic screening of the native kidneys twice a year in all renal transplant patients. As in dialysis patients, the main risk factors for the development of renal cell carcinoma seem to be so-called acquired cystic disease of the native kidneys and the underlying renal disease, such as analgesic nephropathy, and obviously not the immunosuppressive regimen after transplantation.

Usefulness of procalcitonin for differentiation between activity of systemic autoimmune disease (systemic lupus erythematosus/systemic antineutrophil cytoplasmic antibody-associated vasculitis) and invasive bacterial infection

OBJECTIVE

To investigate whether the determination of serum procalcitonin (PCT) in systemic autoimmune disease will help to discriminate invasive infection from highly active underlying disease.

METHODS

Three hundred ninety-seven serum samples, from 18 patients with systemic lupus erythematosus (SLE) and 35 patients with systemic antineutrophil cytoplasmic antibody-associated vasculitis (AAV), were analyzed. Clinical disease activity was assessed by the Systemic Lupus Activity Measure in SLE patients and by the Birmingham Vasculitis Activity Score in AAV patients. Procalcitonin concentrations were determined in parallel with concentrations of neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP). Additionally, serum creatinine values were obtained.

RESULTS

In 321 of the 324 samples from the 42 patients with autoimmune disease but without systemic infection, serum PCT levels were within the normal range (i.e., <0.5 ng/ml), whereas the values for neopterin, IL-6, and CRP were elevated in patients with active underlying disease. All 16 systemic infections occurred in 11 patients with AAV, and were associated with PCT levels that were markedly elevated, to a mean +/- SD of 1.93 +/- 1.19 ng/ml. No correlation between the degree of renal impairment and PCT concentrations was seen.

CONCLUSION

PCT may serve as a useful marker for the detection of systemic bacterial infection in patients with systemic autoimmune disease.

Usefulness of procalcitonin for differentiation between activity of systemic autoimmune disease (systemic lupus erythematosus/systemic antineutrophil cytoplasmic antibody-associated vasculitis) and invasive bacterial infection

OBJECTIVE

To investigate whether the determination of serum procalcitonin (PCT) in systemic autoimmune disease will help to discriminate invasive infection from highly active underlying disease.

METHODS

Three hundred ninety-seven serum samples, from 18 patients with systemic lupus erythematosus (SLE) and 35 patients with systemic antineutrophil cytoplasmic antibody-associated vasculitis (AAV), were analyzed. Clinical disease activity was assessed by the Systemic Lupus Activity Measure in SLE patients and by the Birmingham Vasculitis Activity Score in AAV patients. Procalcitonin concentrations were determined in parallel with concentrations of neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP). Additionally, serum creatinine values were obtained.

RESULTS

In 321 of the 324 samples from the 42 patients with autoimmune disease but without systemic infection, serum PCT levels were within the normal range (i.e., <0.5 ng/ml), whereas the values for neopterin, IL-6, and CRP were elevated in patients with active underlying disease. All 16 systemic infections occurred in 11 patients with AAV, and were associated with PCT levels that were markedly elevated, to a mean +/- SD of 1.93 +/- 1.19 ng/ml. No correlation between the degree of renal impairment and PCT concentrations was seen.

CONCLUSION

PCT may serve as a useful marker for the detection of systemic bacterial infection in patients with systemic autoimmune disease.

Elevated vascular angiotensin converting enzyme mediates increased neointima formation after balloon injury in spontaneously hypertensive rats

OBJECTIVE

To measure the effect of hypertension on neointima formation after balloon injury of rat aorta and its association with the local angiotensin converting enzyme (ACE) concentration. Balloon angioplasty of the thoracic aorta using a 2 French Fogarty catheter was performed in spontaneously hypertensive rats (SHR) and normotensive Sprague-Dawley (SD) rats.

RESULTS

The injured aortic wall of SHR had already significantly higher ACE concentrations than did the uninjured aortic wall of normotensive SD rats (media: 729 +/- 37 dpm/mm2 in SHR versus 496 +/- 38 dpm/mm2 in SD rats, P < 0.01; intima: 83 +/- 5 dpm/mm2 versus 68 +/- 6 dpm/mm2 in SD rats, P < 0.01). Fourteen days after injury of the aorta the hypertensive rats had significantly higher neointima: media ratios than did the normotensive rats (0.83 +/- 0.09 versus 068 +/- 0.01, P < 0.01). This was associated with a significant increase in vascular media and neointima ACE concentrations in SHR (media 965 +/- 25 dpm/mm2, neointima 614 +/- 48 dpm/mm2) compared with those in normotensive SD rats after balloon angioplasty (media 669 +/- 23 dpm/mm2, neointima 287 +/- 33 dpm/mm2, P < 0.01). ACE inhibitor treatment with 10 mg/kg body weight lisinopril daily for 14 days by gavage reduced neointima proliferation in hypertensive and normotensive rats (neointima: media ratio: 0.35 +/- 0.02 for SHR, P < 0.01, versus untreated SHR with balloon injury; 0.28 +/- 0.01 for SD, P < 0.01, versus untreated SD rats with balloon injury). This was associated with significant vascular media ACE inhibition (SHR 149 +/- 9 dpm/mm2; SD rats 118 +/- 7 dpm/mm2; P < 0.01 versus untreated controls with balloon injury) and neointima ACE inhibition (SHR 73 +/- 4 dpm/mm2, SD rats 63 +/- 7 dpm/mm2, P < 0.01, versus untreated controls with balloon injury), but also lowered the blood pressure in SHR significantly (to 148 +/- 5 mmHg, P < 0.01, versus untreated SHR with balloon injury). When this drop in blood pressure was prevented by feeding the rats a high-salt diet (SHR with ACE inhibitor plus high salt-diet group blood pressure 193 +/- 3 mmHg, P = 0.57, versus untreated SHR) hypertension per se without the local ACE increase (ACE concentration in SHR with ACE inhibitor high-salt diet rats' media 167 +/- 10 dpm/mm2 and neointima 81 +/- 9 dpm/mm2) had only a mild effect on neointima formation after balloon angioplasty (neointima: media ratio 0.4 +/- 0.01 for SHR with ACE inhibitor plus high-salt diet versus 0.35 +/- 0.02 for SHR with ACE inhibitor plus normal-salt diet P < 0.05). Treatment with 10 mg/kg body weight angiotensin II subtype 1 receptor antagonist losartan potassium daily for 14 days by gavage was associated with a reduction in neointima formation similar to that observed with the ACE inhibitor both for SHR and for SD rats (neointima: media ratio 0.32 +/- 0.04 for SHR with losartan, 0.27 +/- 0.03 for SD rats with losartan; P < 0.01, versus untreated controls with balloon injury) suggesting that ACE inhibitor prevented neointima formation, at least in part by, reducing the local production of angiotensin II.

CONCLUSION

Neointima formation after balloon angioplasty in SHR is increased compared with that in normotensive SD rats. This is due mainly to there being a higher degree of activation of the renin-angiotensin system in the aorta of the SHR before and after balloon injury compared with that in normotensive SD rats measured in terms of the increased vascular ACE concentrations. Blood pressure alone had only a moderate effect on neointima formation.

Renal transplantation for patients with autoimmune diseases: single-center experience with 42 patients

BACKGROUND

In patients with autoimmune diseases such as vasculitis or systemic lupus erythematosus (SLE), end-stage renal disease develops in a high percentage of patients, and kidney transplantation has become a therapeutic option. However, only limited data about the prognosis and outcome after kidney transplantation are available.

METHODS

Long-term graft survival and graft function of renal transplant recipients with SLE, Wegener's granulomatosis, microscopic polyangiitis, Goodpasture's syndrome, and Henoch-Schonlein purpura were evaluated in a single center. In addition, the incidence of renal and extrarenal relapses and the impact of the immunosuppressive therapy on the course of the autoimmune disease were studied.

RESULTS

Renal transplant recipients with autoimmune diseases such as vasculitis and SLE had a patient survival rate (94% after 5 years) and a graft survival rate (65% after 5 years) comparable to those of patients with other causes of end-stage renal disease (patient survival 88% and graft survival 71% after 5 years). Graft losses due to the underlying disease were rare. Extrarenal relapses occurred in three patients with Wegener's granulomatosis, one patient with microscopic polyangiitis, and three patients with SLE, but were less frequent compared with the period with chronic dialysis therapy. Autoantibody levels in patients with SLE, Wegener's granulomatosis, or microscopic polyangiitis did not seem to influence the outcome.

CONCLUSIONS

Renal transplantation should be offered to patients with autoimmune diseases. Follow-up should include the short-term control of renal and extrarenal disease activity.

Treatment of experimental mesangioproliferative glomerulonephritis with non-anticoagulant heparin: therapeutic efficacy and safety

Treatment with conventional heparin is effective in experimental mesangioproliferative glomerulonephritis. However, the long-term effects and safety of this therapy, in particular in the presence of mesangiolysis, have not been assessed. In addition, this therapy has been hampered by bleeding complications. In the present study, therefore, we investigated the long-term effects of a short course of non-anticoagulant (NA) heparin treatment in the anti-Thy 1.1 mesangioproliferative glomerulonephritis, in which early immune-mediated mesangiolysis subsequently leads to mesangial hyperproliferation. Rats received continuous ip NA-heparin or vehicle during the active mesangioproliferative phase (Days 2 to 9; early treatment) or during the early resolution phase (Days 10 to 17; late treatment). Whereas NA-heparin in the early treatment group did not affect the glomerular macrophage, lymphocyte, or platelet influx, it did lead to significantly decreased glomerular cellularity, mesangial cell proliferation, alpha-smooth muscle actin, desmin expression (ie, markers of activated mesangial cells), and matrix accumulation as well as to persistent mesangiolytic lesions including microaneurysms. Despite this latter finding, at Day 120, NA-heparin-treated rats of the early treatment group showed significantly better renal function and less proteinuria and glomerulosclerosis than vehicle-infused rats. In contrast, late therapy with NA-heparin neither accelerated resolution of the nephritis or otherwise affected the course of the disease. We conclude that transient NA-heparin therapy is effective in mesangioproliferative glomerulonephritis, both acutely and long term, when it is initiated during the active phase of the disease. Also, NA-heparin therapy is safe even in glomerular diseases accompanied by mesangiolysis.

Activated complement C3: a potentially novel predictor of progressive IgA nephropathy

In the search for a serologic marker of disease activity, we measured concentrations of activated C3 (actC3, that is, neoantigens developing after C3 activation on breakdown products), C4-C3 complexes and soluble C5b-9 (sC5b-9) in one or two plasma samples from adult patients with IgA nephropathy (IgAN, N = 50) or Henoch-Schönlein purpura (HSP, N = 4). As controls, 20 patients with non-immune renal disease, but comparable age, degree of proteinuria, renal dysfunction and prevalence of hypertension were studied. Compared to controls, actC3 levels were elevated in 30% of the patients with IgAN and one of the HSP patients. C4-C3 complexes were elevated in only 8% of the IgAN patients, and sC5b-9 levels were within the control range in all IgAN and HSP patients. In IgAN patients with elevated actC3 levels, proteinuria and hematuria were more pronounced than in those with normal levels. Elevated plasma concentrations of actC3 at the first presentation correlated with subsequent deterioration of renal function both in patients with initially normal and already impaired renal function (r = -0.56, N = 44, P = 0.003). The five IgAN patients with elevated actC3 on both occasions of obtaining plasma showed the most rapid loss of renal function. We conclude that mainly alternative pathway complement activation can be demonstrated in patients with IgAN and HSP. In IgAN patients the presence of complement activation is associated with more severe renal disease. Further studies are warranted to examine the clinical usefulness of actC3 as a predictor of the subsequent course of IgAN.

The safety of ranitidine in over a decade of use

BACKGROUND

Ranitidine hydrochloride (Zantac) is one of the most extensively studied and widely used drugs of all time. This has provided an excellent opportunity to define its safety profile.

METHODS

Data from 189 controlled clinical trials in which more than 26,000 patients received daily doses of ranitidine for 4 weeks or more were reviewed. More than 80% of patients were treated with up to 300 mg ranitidine daily; the remaining patients received doses of up to 1200 mg daily. Eighty-seven trials were placebo controlled. Analyses of post-marketing surveillance and a database of all spontaneously reported adverse events were also evaluated.

RESULTS

Overall in the clinical trial programme adverse events were reported by 20% of those receiving ranitidine compared with 27% of those receiving placebo. The pattern of events was similar in all treatment groups with no evidence of dose-related toxicity in regimens encompassing an eightfold range of therapeutic doses. Similarly in a programme of studies designed to evaluate a dose of ranitidine of 75 mg for non-prescription (over-the-counter) use in the treatment of heartburn, ranitidine was not associated with an adverse event profile distinct from that of placebo. Analysis of spontaneously reported adverse event data allowed identification of rare idiosyncratic events.

CONCLUSIONS

Review of data from a large population of controlled clinical trials with analyses of postmarketing surveillance studies and spontaneously reported adverse events confirmed the excellent safety profile of ranitidine.

Pharmacokinetics and pharmacodynamics of ranitidine in renal impairment

OBJECTIVE

The pharmacodynamics and pharmacokinetics of ranitidine were examined in subjects with varying degrees of renal function to determine the effect of this condition on acid-antisecretory activity.

METHODS

Subjects with creatinine clearances (Ccr) ranging from 0 to 213 m1.min-1 received single 50-mg and 25-mg i.v. doses of ranitidine. This was followed by determination of serum and urine ranitidine concentrations, and continuous gastric pH monitoring for 24 h.

RESULTS

Serum ranitidine concentrations were described by a two-compartment model linked to a sigmoidal Emax model describing gastric pH. Ranitidine renal clearance, ranging from 0 to 1003 m1.min-1, correlated with CPAH (r2 = 0.707), while non-renal clearance was unaltered. Steady-state volume of distribution decreased by half in severe renal impairment. No changes in the effective concentration at half-maximal response (EC50), maximal response (Emax), or basal response (E0) were observed. Thus, renal elimination of ranitidine declined in parallel with renal function, while sensitivity to the pharmacologic effect (gastric pH elevation) was unaltered. Ranitidine was cell tolerated in these renally impaired subjects.

CONCLUSION

These data indicate that the current recommendation for renal impairment dose reduction (by two-thirds when Ccr < 50 m1-min-1) might result in under-treating moderately impaired patients, and suggests a less conservative dose reduction (by half when Ccr < 10 m1.min-1) to avoid therapeutic failure while remaining within the wide margin of safety for this drug.

Age-related glomerulosclerosis and interstitial fibrosis in Milan normotensive rats: a podocyte disease

In Milan normotensive (MNS) rats glomerulosclerosis and interstitial fibrosis develop spontaneously in the absence of hypertension. Renal changes were sequentially assessed in these rats between 2 and 10 months of age. At 10 months, rats were characterized by heavy proteinuria, increased serum creatinine, focal or global glomerulosclerosis in 51 +/- 12% of the glomeruli as well as tubulointerstitial injury involving > 25% of the section area. Cell injury in podocytes (evidenced as increased expression of desmin and by electron microscopy) and interstitial fibroblasts (increased expression of alpha-smooth muscle actin) and mild glomerular hypertrophy were witnessed as early as three to four months of age and preceded glomerulosclerosis and interstitial fibrosis. Only minor evidence of mesangial cell activation (as assessed by glomerular (de novo alpha-smooth muscle actin or type I collagen expression or increased cell proliferation) was noted throughout the observation period. Later stages of the disease were characterized by glomerular and/or tubulointerstitial macrophage influx and osteopontin expression (a chemoattractant), mild accumulation of lymphocytes, platelets, fibrinogen, as well as by a progressive accumulation of various matrix proteins. Progressive renal disease in MNS rats is thus noteworthy for the relative lack of mesangial cell activation. Rather, early podocyte damage, induced by yet unknown mechanisms, may underlie the development of glomerulosclerosis and subsequent interstitial fibrosis.

Role of interleukin-6 in mediating mesangial cell proliferation and matrix production in vivo

Mesangial cell proliferation and matrix overproduction characterize many progressive glomerular diseases. Based on currently available data, the role of interleukin-6 (IL-6) in mediating mesangial cell proliferation and matrix production is controversial. The present study attempts to clarify this issue by showing that: (1) IL-6 knock out mice develop a normal glomerular architecture and in particular a normal mesangium. (2) Mesangioproliferative glomerulonephritis induced by Habu snake venom is equally severe in IL-6 knock out mice as in control mice. (3) A continuous seven-day intraperitoneal infusion of 50 micrograms recombinant human IL-6 into rats with a prior minimal (subnephritogenic) injury to mesangial cells does not induce glomerular cell activation, cell proliferation, matrix production, leukocyte influx, platelet influx or proteinuria. (4) A continuous seven-day IL-6 infusion into rats with mesangioproliferative nephritis (anti-Thy 1.1 nephritis) increases matrix protein transcription in the absence of detectable effects on matrix protein accumulation and otherwise has no effect on the natural course of the disease. We conclude from these findings that IL-6 is not an important mediator of mesangial cell proliferation and matrix overproduction in vivo, and that currently little rationale exists to advocate anti-IL-6 therapy in mesangioproliferative disease states.

Relationship between human leukocyte antigen determinants and courses of hepatitis B virus infection in Caucasian patients with end-stage renal disease

BACKGROUND

Divergent results have been reported with regard to the relationship between the course of hepatitis B virus (HBV) infection and the human leukocyte antigen (HLA) determinants. The aim of the present study was to investigate the phenotype frequencies of HLA class-I and -II alleles in Caucasians with and without HBV infection.

METHODS

Fifty-eight patients with persistent HBV infection (group 1), 119 patients with resolved HBV infection (group 2), and 106 patients neither infected by HBV nor vaccinated against HBV (group 3) were analyzed. All patients had end-stage renal disease. HLA class-I antigens were serologically determined. For HLA class-II typing we performed DRB1, DQA1, and DQB1 genotyping using a polymerase chain reaction-sequence-specific oligonucleotide procedure.

RESULTS

Compared with group 2, group 1 showed increased frequencies of HLA-B8, DR3 (P < 0.05), A30, DQA1*0501 (P < 0.01), and a decreased frequency of HLA-B12 (P < 0.05). Decreased frequencies of HLA-B27, B40, DR13, and DQ1*0604 (P < 0.05) and an increased frequency of HLA-B35 (P < 0.05) were found in groups 1 and 2 compared with controls (group 3). None of the differences detected in the phenotype frequencies of HLA alleles were statistically significant after correction.

CONCLUSIONS

We conclude that the susceptibility to HBV infection and the different courses of HBV infection are not strongly related to HLA status in Caucasians.

No significant influence of HLA determinants on susceptibility to hepatitis C virus infection in Caucasian patients with end-stage renal disease

In hepatitis C, both susceptibility to infection and the course of disease may depend on differences in the immune response. As the major histocompatibility complex (MHC) plays a crucial role in antigen presentation, we investigated a possible relationship between susceptibility to hepatitis C virus (HCV) infection and human leucocyte antigen (HLA) alleles. Therefore, phenotype frequencies of HLA were compared in 186 anti-HCV positive patients with end-stage renal disease (ESRD) to 328 anti-HCV negative patients with ESRD. HLA class I alleles were determined serologically and HLA class II alleles (DRB1, DQA1, DQB1) by the polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) technique. Additionally, in anti-HCV positive patients we looked for a relationship between the activity of hepatitis C (indicated by elevation of transaminases or the presence of viremia) and HLA determinants. For the three criteria (antibody status, elevation of transaminases and viremia) a significant association to HLA alleles was not found in patients with ESRD. This suggests that neither susceptibility to HCV infection nor the biochemical activity of hepatitis and HCV-RNA positivity seem to be strongly related to HLA status in Caucasian patients with end-stage renal disease.

The long-term course of hepatitis C after kidney transplantation

Patients with chronic hepatitis run the risk of developing progressive liver disease during immunosuppressive therapy after kidney transplantation. To determine the impact of chronic hepatitis C on morbidity and mortality we analyzed 162 anti-HCV positive of 1241 renal-grafted patients (prevalence 13.1%; 84.9% HCV RNA positive) regularly surveyed in our outpatient clinic between 1992 and 1994. The mean age at transplantation was 44.5 (6-69) years, and follow-up after grafting was 7.4 (0.1-23.9) years. The immunosuppressive regimen and frequency of rejection episodes in HCV-infected patients were comparable to the total population. Only 4.3% (5/117) of the anti-HCV positive, HBV negative patients living with functioning grafts developed a markedly compromised liver function. Fifteen (9.3%) of the HCV-infected patients died, but none suffered from posthepatitic cirrhosis. An additional retrospective analysis of causes of death after transplantation prior to 1992 revealed that liver disease had only been responsible for 2% of the deaths (7 of 324) in the HBsAg negative population (n= 1901). In contrast, the predominant cause of death in the HBsAg positive population (n=76) was posthepatitic cirrhosis in 58% (15 of 26). Thus, kidney transplantation in patients with replicative hepatitis C and normal liver function appears to be justified because of low early and late morbidity and mortality due to chronic liver disease. HBV infection and hemosiderosis substantially increase the risk of chronic liver disease in renal transplant recipients with hepatitis C.

Urodilatin is involved in sodium homeostasis and exerts sodium-state-dependent natriuretic and diuretic effects

Urodilatin is involved in sodium homeostasis exerts sodium-state-dependent natriuretic and diuretic cts. Eight male volunteers participated in a study consisting of three consecutive phases of 7 days each. The volunteers a sodium diet with 52, 172.6, and 347.8 mmol um/day. Sodium excretion increased from 57.4 +/- 3.7 via .8 +/- 4.6 (P < 0.001) to 322.5 +/- 10.2 mmol/24 h (P < 0.001) at the end of each sodium diet. Urinary urodilatin excretion increased from 24.8 +/- 3.0 via 35.5 +/- 9.0 (P = 0.07) to 49.0 = mol/min (P < 0.01). At the end of each diet, urodilatin was infused for 2 h at 20 ng.kg body wt-1.min-1. Natriuresis increased after low- (4.1 to 52.9 mmol/h, P < 0.001), normal (6.9 to 44.9 mmol/h, P < 0.05), and high-sodium diet (20.1 to 102.9 mmol/h, P < 0.001). Diuresis increased from 174 to 709 (P < 0.001), 395 to 1,026 (P < 0.05), and 266 to 1,339 ml/h < 0.001). The present results indicate that endogenous urodilatin plays an important role in sodium homeostasis and that renal response to exogenous urodilatin is modulated by sodium balance.