[The kidneys, ageing and transplantation]. / Ledviny, stárnutí a transplantace.

The discrepancy between the increasing number of patients listed for kidney transplantation and limited cadaver donor sources has led the transplant community towards indication of elderly people as potential kidney donors. Based on clinical data, the kidney grafts explanted from aged donors have limited survival rates compared with younger ones. The donor age has been also implicated as the important alloantigen-independent risk factor for later onset of chronic allograft neprohopathy called chronic rejection. In this review we focused on some pathophysiological aspects of kidney aging and on the fate of transplanted kidney removed from elderly donors.

Ureteroneocystostomy contributes to late functional and morphological changes in rat kidney transplants.

PURPOSE: We investigated whether the surgical technique used to reconstruct the ureter has an impact on the late function of kidney transplants by comparing ureteroneocystostomy and ureteroureterostomy. To rule out alloantigeneic mediated effects on late graft dysfunction kidney transplants were performed in a syngeneic model. MATERIALS AND METHODS: Rat kidney isografts were transplanted with simultaneous ureteroneocystostomy or ureteroureterostomy. Unilaterally nephrectomized rats served as controls. Eight weeks after transplantation intrapelvic pressure was measured during baseline diuresis, and after intravesical and intrapelvic infusion. Albuminuria was determined monthly until sacrifice at week 52. Histomorphological analysis included the degree of glomerulopathy, tubular atrophy, interstitial fibrosis and intimal hyperplasia. CD4+- and CD8+ T cells, and macrophages were identified using immunohistochemical testing. RESULTS: Eight weeks after transplantation intrapelvic pressure during baseline diuresis and after intrapelvic infusion was significantly increased in rats with ureteroneocystostomy versus those with ureterostomy and unilateral nephrectomy, whereas intravesical infusion did not change the pressure in any group. During followup albuminuria after ureteroureterostomy did not differ from that after unilateral nephrectomy. In contrast, albuminuria significantly increased after ureteroneocystostomy from week 36 onward. At week 52 the ureter and kidney after ureteroureterostomy and unilateral nephrectomy had a normal appearance, whereas all ureters were dilated after ureteroneocystostomy. Nevertheless, 6 of the 8 kidneys in the ureteroneocystostomy group had a normal appearance. However, histomorphological findings in rats with transplants and ureterovesical anastomosis demonstrated significantly more interstitial fibrosis, CD8+ T cells and macrophages than isografts ureteroureterostomy. CONCLUSIONS: As a surgical technique for restoring the urinary tract after kidney transplantation, ureteroneocystostomy contributes to the development of long-term functional and histological renal changes. Partial obstruction may be the cause of this renal impairment.

Transplantation of a single kidney per se does not lead to late graft dysfunction.

In unraveling the pathogenesis of chronic transplant dysfunction (CTD), non-alloantigen specific factors, as ischemia/reperfusion and renal mass have been suggested to play a role in the process. The aim of the present study was to investigate the effect of the transplantation procedure per se on the development of CTD in a syngeneic kidney transplant model in the rat. Kidney transplantation was performed with the BN rat as donor and recipient, the recipient kidneys having been removed. Unilaterally nephrectomized (UNx) and native BN rats served as controls. Renal function was determined monthly (proteinuria and glomerular filtration rate/100 g body weight; GFR). The follow-up period was until 52 weeks post-transplantation. Histomorphological analysis of CTD according to the BANFF criteria was carried out. Immunohistochemical staining was performed to identify infiltrating cells (CD4, CD8, and ED1) and the expression of MHC class II and ICAM-1. Isografts had a minor, constant proteinuria during follow-up, which did not differ from that of UNx: 27 +/- 10 vs. 29 +/- 2 mg/24 h at week 52. Unilateral nephrectomy led to a significant reduction of the GFR, which was about 80% of that of native rats. The GFR of isografts did not differ from that of UNx rats. Histomorphology of renal isografts was comparable to UNx and native kidneys; some glomerulopathy and tubular atrophy leading to a total BANFF-score of 2.6 +/- 0.5. In native BN kidneys, few CD4+ cells and ED-1+macrophages (mphi) were found; MHC class II was constitutively expressed on the proximal tubules and ICAM-1 on the glomeruli and peritubular capillaries. UNx-kidneys showed a similar pattern. Isografts had significantly more CD4+ cells and Mphi, mainly localized in the glomeruli, and a more intense ICAM-1 expression in the glomeruli and interstitium. Transplantation of one kidney in itself does not lead to CTD.

ACE gene polymorphism and long-term renal graft function.

OBJECTIVES: The long-term outcome of transplanted kidneys has not changed substantially and only a minority of grafts survives more than 15 yr. The aim of this study was to determine the influence of ACE gene polymorphism on long-term outcome after renal transplantation. DESIGN AND METHODS: Using PCR, we evaluated ACE I/D gene polymorphism in a group of patients with long-term graft function (LTF) over 15 yr and compared it with control groups of transplant recipients and population sample. RESULTS: The distribution of genotypes in the LTF group differed from transplant controls (p < 0.05). Moreover, DD homozygotes in the LTF group had better creatinine clearance (DD: 1.1 +/- 0.3, ID: 0.96 +/- 0.3, II: 0.76 +/- 0.3 mL/s; p < 0.05). There were no differences in genotype distribution between transplant and population samples. CONCLUSIONS: Results of our study have demonstrated a possible connection between the DD variant of ACE I/D gene polymorphism and excellent long-term graft function.

[Chronic renal allograft rejection. Part 2. Therapeutic possibilities] . / Chronická rejekce renálního allostepu. Cást 2. Terapeutické moznosti.

Chronic rejection represents an important cause of renal allograft loss in the long term follow up. New insights into etiopathogenesis of the chronic rejection offer possibilities for experimental therapy. Novel immunosuppressants, such as mycophenolic acid, tacrolimus or rapamycin as well as lipid lowering drugs, angiotensin-converting enzyme inhibitors or AT-1 receptor blockers, may reduce of effects the risk factors on the progression of chronic rejection. In the future, gene therapy may offer additional possibilities to prevent chronic rejection. This review deals with possibilities of prevention of the chronic renal allograft rejection based on experimental evidences and current therapeutic concepts and puts these options into a rational perspective.

Late graft dysfunction after prolonged cold ischemia of the donor kidney: inhibition by cyclosporine.

BACKGROUND: The present study was devised to elucidate the influence of prolonged cold ischemia on the development of chronic transplant dysfunction (CTD) in kidney isografts (Brown Norway-->Brown Norway; BN-->BN) and in kidney allografts (BN-->Wistar Agouti/ Rij [WAG]) under temporary cyclosporine (CsA) therapy. METHODS: To induce ischemic injury, BN donor kidneys were preserved for 24 hr in 4 degrees C University of Wisconsin solution before transplantation. Renal function (proteinuria), histomorphology according to the BANFF criteria for CTD, and infiltrating cells were assessed. Grafts were examined both early at days 2, 3, 6, and 10, and late at week 26 (allografts) or at week 52 (isografts). RESULTS: Nonischemic isografts preserved a normal function and morphology. Ischemic isografts developed a progressive proteinuria over time and demonstrated significantly more glomerulopathy with macrophage (Me) infiltration and intimal hyperplasia than nonischemic controls at week 52. During the initial 10 days, there was an increased infiltration of MHC class II+ cells, predominantly CD4+ cells and Mphi, coinciding with up-regulated intercellular adhesion molecule-1 expression. CsA treatment in ischemic isografts inhibited infiltration of MHC II+ cells in the early stage, which was accompanied by significantly less renal damage at week 52 compared with untreated controls (proteinuria: 59+/-8 vs. 134+/-19 mg/24 hr; BANFF score: 2.8+/-0.4 vs. 4.3+/-1.0). Under CsA therapy, 24-hr cold ischemia of the allograft affected neither the onset or progress of proteinuria, nor the histomorphology (BANFF score: 7.8+/-2.4 vs. 7.3+/-1.9). In both ischemic and nonischemic allografts, intercellular adhesion molecule-1 expression and mononuclear cell infiltration (CD4, CD8, Mphi was abundantly present during the first 10 days and function deteriorated rapidly. CONCLUSIONS: Prolonged cold ischemia plays a role in the induction of CTD, but its deleterious effect can be successfully inhibited by CsA. Therefore, the alloantigeneic stimulus is the overriding component in the multifactorial pathogenesis of CTD.

Genetic susceptibility of the donor kidney contributes to the development of renal damage after syngeneic transplantation.

Solitary kidneys, especially in rats, appear vulnerable to develop functional and structural damage. However, differences in susceptibility exist between strains. It is not clear whether this is intrinsic to the kidney or due to environmental factors. Therefore, the aim of the present study was to investigate possible differences in genetic susceptibility for renal damage. By transplanting different rat donor kidneys into a normotensive, histocompatible recipient, the kidneys were exposed to the same blood pressure profiles, metabolic and hormonal environment. Kidneys from young adult hypertensive fawn-hooded (FHH) rats, a strain showing early onset renal damage, normotensive, renal damage-resistant August x Copenhagen-Irish (ACI), and (ACI x FHH) F1 donors were transplanted into male F1 recipients. The native kidneys of the recipients were removed 1 week after transplantation. The results were mutually compared and to their unilaterally nephrectomized littermates. Systolic blood pressure (SBP) and albuminuria (UaV) were determined at the time of transplantation and at 8 and 16 weeks. The histomorphologic analysis included the incidence of focal glomerulosclerosis (FGS), and determination of chronic transplant dysfunction according to the BANFF criteria. A negative impact of the transplantation technique in this syngeneic situation could not be detected as F1 transplants did not differ functionally and morphologically from their UNx controls. Transplanting an ACI kidney did not result in significant changes of SBP, UaV, and incidence of FGS compared to F1 transplants and ACI-UNx. In contrast, FHH kidneys did show a progressive increase of UaV and glomerulosclerosis and a significantly higher BANFF score, whereas the SBP did not differ from F1 transplants. The moderate hypertension seen in FHH did not travel with the kidney. Compared to the FHH-UNx rats, transplantation of a FHH kidney did significantly attenuate the increase of UaV and FGS. The susceptibility of the donor kidney appears to be an important factor in the development of chronic renal damage. This may play a role in the long-term functional changes seen after clinical renal transplantation.

Sex hormones and gender-related differences: their influence on chronic renal allograft rejection.

BACKGROUND: Renal hemodynamics and immune responses differ between males and females. Thus, sex hormones and genetically determined gender differences may determine the process of chronic rejection to some extent. METHODS: Female (F) or male (M) F344 kidneys were orthotopically transplanted into ovariectomized female Lewis recipients and were treated for 16 weeks with either estradiol, testosterone, or vehicle. RESULTS: Testosterone treatment resulted in increased urinary protein excretion independently of the donor gender, as well as extended glomerular sclerosis, interstitial fibrosis, and severe vascular lesions. Additionally, mononuclear cell infiltration was most pronounced in these animals, in parallel to an increased expression of intercellular adhesion molecule-1 (ICAM-1), fibronectin, laminin, and transforming growth factor-beta (TGF-beta) in the grafts. Estradiol treatment resulted in an improved graft function, reduced glomerular sclerosis, and a diminished cellular infiltration, in parallel to a reduced ICAM-1, fibronectin, laminin, and TGF-beta expression. In animals treated with vehicle, the gender of the donor influenced the outcome. Grafts of male origin had good graft function and histology, whereas grafts from female donors developed severe proteinuria and glomerular, interstitial, and vascular damage. CONCLUSIONS: These results suggest that a protective effect of estradiol on the progression of chronic rejection exists that is independent of donor gender. Additionally, a male kidney may benefit from the absence of testosterone, whereas the function of a female kidney deteriorates in the absence of estradiol.

[Chronic rejection of renal allografts. Part 1. Present knowledge of etiopathogenesis]. / Chronická rejekce renálního alostepu. Cást 1. Soucasné poznatky o etiopatogenezi.

Chronic rejection is the most common cause of the long term renal graft loss. It is characterized by luminal thickening and obliteration, interstitial sclerosis, glomerulosclerosis and tubular atrophy development. The pathology is still unclear. Alloantigen-dependent factors (acute rejection, HLA mismatch) and allograft-independent factors (ischaemia-reperfusion, hyperlipidaemia, hypertension, infection, nephrotoxicity, reduced nephron dose) have been implicated in the etiology of chronic rejection. As a result of these factors, endothelial cells are activated and express a variety of adhesion molecules, cytokines and growth factors. Lymphocytes and macrophages infiltrate the areas of local damage and express other cytokines and growth factors (TGF, bFGF, PDGF). In the next step, vascular smooth muscle cells proliferate and migrate from the media into the vascular intima and produce local extracellular matrix. Which factors are the most important and which mechanisms are the key for the development of chronic rejection are in the focus of ongoing research.

Sequential changes of biochemical bone parameters after kidney transplantation.

BACKGROUND: Persistent hyperparathyroidism after renal transplantation (Rtx) has been reported in several studies. However these studies evaluated biochemical bone parameters either only during a short time period (up to 6 months) or for a longer time period, but with long intervals in between. Therefore, we prospectively evaluated biochemical bone parameters of kidney-transplant recipients at short intervals for 2 years after surgery. METHODS: Biochemical bone parameters were prospectively investigated in 129 patients 2, 3, 5, 8, 12, 18 and 24 months after Rtx. All patients received prednisone and cyclosporin A as immunosuppressive therapy, and 75 patients also received azathioprine. None of the patients was treated with calcium, phosphorus, or vitamin D preparations. RESULTS: Serum creatinine levels decreased from 166.8 +/- 5.4 mumol/l to 140.0 +/- 4.9 two years after Rtx; (data are expressed as mean +/- s.e.m.). Serum phosphorus levels increased slightly from 0.9 +/- 0.022 mmol/l to 0.98 +/- 0.025 (12 m), but remained within the lower normal range. We observed a rise in total and albumin adjusted calcium concentrations 3 months after Rtx. 52% of all patients had serum calcium levels above 2.62 mmol/l (upper normal limit in our laboratory) 3 months after renal transplantation with a gradual decrease thereafter. There was no correlation of calcium and PTH levels. We observed a significant rise in biochemical bone parameters from 2 to 5 months after renal transplantation (P < 0.001): alkaline phosphatase (AP) increased from 164.3 +/- 9.4 to 236 +/- 12.7 U/l (normal 50-180), bone specific alkaline phosphatase (BAP) rose from 17.7 +/- 1.36 to 23.2 +/- 1.7 ng/ml (normal:4-20) and osteocalcin (OC) increased from 20.2 +/- 1.5 to 26.7 +/- 1.9 ng/ml (normal 4-12). AP and BAP levels values normalized 12 months after renal transplantation, whereas OC was still above normal throughout the study period. Patients were subdivided into two groups: those with good and those with impaired graft functions. Patients with good graft function had stable serum creatinine levels (< or = 132 mumol/l or < or = 1.5 mg/dl) well below the mean serum creatinine concentration during the study period. The significant changes in AP, BAP, and OC occurred irrespective of renal function. However, patients with impaired graft function (n = 65) had significantly higher PTH-levels (70 pg/ml higher) than patients with good graft function (n = 64), P < 0.01. PTH was positively correlated with serum creatinine (r = 0.81, P < 0.001). Moreover, patients with low 25 (OH) vitamin D levels (n = 63) had significantly higher PTH concentrations (between 40 and 80 pg/ml, P < 0.01) throughout the study period compared to patients (n = 66) with a sufficient 25(OH)D supply irrespective of graft function. There was a negative correlation of 25 (OH)D levels and PTH; (r = -0.49, P < 0.001). 1,25(OH)2D3 (evaluated in 24 patients) levels increased from 46.5 +/- 6.6 to 76.9 +/- 7.6 pg/ml (normal:35-90) at 12 months. CONCLUSION: Hypercalcaemia is a common phenomenon in the early period after kidney transplantation and occurs in the presence of low normal phosphorus levels. It is most probably related to improved PTH action and 1-hydroxylation of vitamin D. The rise in biochemical bone parameters between 3 and 5 months occurs irrespective of graft function and normalization is only achieved 1 year after transplantation. PTH is constantly elevated for up to 2 years after kidney transplantation and is most probably related (a) to impaired graft function and (b) to suboptimal 25 OH vitamin D supply.

Infections and reduced functioning kidney mass induce chronic rejection in rat kidney allografts.

The etiology of chronic rejection of kidney allografts is unknown, although hyperfiltration, acute rejection, viral infection and initial graft ischemia have been implicated. To test whether endothelial activation may be the link between these factors and chronic rejection, the endotoxin (lipopolysaccharide-LPS), a potent activator of endothelial cells, was evaluated in an established chronic rejection model. Bilaterally nephrectomized Lewis recipients of orthotopically transplanted Fisher 344 kidneys were treated briefly with low dose cyclosporine (1.5 mg/kg/day x 10). Recipients were given a non-lethal dose of LPS (2 mg) i.p. at 8 weeks and compared to allografted controls treated with vehicle. Urine protein was measured every 4 weeks. Rats in the treated group were sacrificed at 12 and 16 weeks, control animals at 12, 16 and 24 weeks (20/group) and examined histologically. In the chronically rejecting control allografts, progressive interstitial and glomerular sclerosis and vascular intimal proliferation had become apparent by 12 weeks. Infiltration of glomeruli, particularly by macrophages (M phi), and the coincident presence of cytokines were prominent, peaking at 16 weeks. LPS treatment accelerated and intensified these changes; proteinuria was more pronounced (16 weeks: 79 mg/24 h vs. 49 mg/24 h, p < 0.05). Numbers of infiltrating M phi peaked at 12 weeks in LPS treated hosts (69 c/FV vs. 27 c/FV in untreated controls, p < 0.01), accompanied by an increased upregulation of MHC class II and cytokine expression, particularly TNF alpha and PDGF around arteries and areas of infiltration. BY 16 weeks, 35 +/- 3% of glomeruli in LPS treated recipients had become sclerotic vs. 15 +/- 6% (p < 0.05) in controls, again associated with increased expression of cytokines (PDGF, TNF alpha, TGF beta), adhesion molecules (ICAM-1) and extracellular matrix proteins. Overall, the extent of chronic rejection of grafts in LPS treated rats at 16 weeks was similar to that developing in non-treated rats at 24 weeks. Activation of graft endothelium and/or host leucocytes increased the pace of graft infiltration and the expression of cytokines and other molecules. These events accelerate the process of chronic rejection.

Infection-associated cellular activation accelerates chronic renal allograft rejection in rats.

The etiology of chronic rejection is unknown, although acute rejection, viral infection, and initial graft ischemia have been implicated. To test the effects of infections on the process of chronic rejection, we simulated bacterial infection by the administration of the endotoxin lipopolysaccharide (LPS), a potent activator of various cell types in an established rat model of chronic rejection. Lewis recipients of Fisher 344 kidneys were treated with a single dose of LPS or vehicle 8 weeks following transplantation and grafts were examined at various time points. In the chronically rejecting controls, leukocytic infiltration and the expression of cytokines peaked at 16 weeks. In LPS-treated hosts, leukocyte infiltration and cytokine expression peaked at 12 weeks. By 16 weeks, glomeruli in LPS-treated recipients had become far more sclerotic than those in controls, mimicking the changes observed in controls at 24 weeks. We conclude that infections may play an important role in the development of chronic rejection.

Binding of lymphocytes to acutely rejecting rat kidney allografts in vitro is guided by events in the graft itself rather than by sensitization of host lymphocytes.

Circulating host lymphocytes recognize, bind to, become activated by, and infiltrate engrafted allogeneic tissues. The mechanisms responsible for these early events which lead to acute immunological rejection have not been precisely defined. We have examined sequentially in vitro lymphocyte binding patterns in a kidney transplant model of acute rejection in rats and their relationship to the expression of two representative adhesion molecules, ICAM-1 and LFA-1. The extent of binding of naive, or allosensitized recipient strain LNL or PBL, or donor strain or third party cells to frozen sections of kidney allografts was not significantly different; adherence was dependent upon whether the graft was an allograft or an isograft. The pattern of lymphocyte adherence to various allograft compartments was distinct and varied with time. Within 3 days after transplantation only a few cells had bound to the frozen tissues, preferentially to vascular endothelium. By days 5 and 7, increasing numbers of cells bound primarily to tubules, as did the few cells adhering to isografts. Immunohistologically, ICAM-1 expression increased progressively during acute rejection, first on vascular endothelium, later on tubules. LFA-1+ infiltrating cells peaked more quickly. Lymphocyte binding could be inhibited (approx. 40%) by monoclonal antibodies directed against LFA-1 and ICAM-1. The results indicate that in vitro lymphocyte binding to acutely rejecting kidney transplants is directed by the allogenicity of the graft itself via upregulation of adhesion molecules rather than sensitization of the host cells.

Hyperviscosity syndrome: efficacy and comparison of plasma exchange by plasma separation and cascade filtration in patients with immunocytoma of Waldenström's type.

The hyperviscosity syndrome is a common problem in patients suffering from IgM paraproteinemia. In this situation cytotoxic chemotherapy alone is insufficient and additional plasma therapy is required. Until recently, conventional plasma exchange was the only plasma therapy available. While this method has proven its efficacy, it eliminates proteins unselectively. Cascade filtration, on the other hand, has been established to remove proteins as a function of their size offering the prospect of a highly selective withdrawal of macromolecules. In the work presented, the efficacy of conventional plasma exchange and cascade filtration was evaluated performing both techniques at random in cases of hyperviscosity syndrome due to immunocytoma of Waldenström's type (n = 11/group). In these patients, conventional plasma exchange decreased plasma viscosity by 48%; cascade filtration was less effective (26%), correlating with a smaller decrease of IgM (conventional plasma exchange 42% vs cascade filtration 27%). The profile of other plasma proteins studied did not change significantly with either treatment. Furthermore, we observed no differences regarding serious side-effects. In conclusion, we could not demonstrate a superior effect of cascade filtration as compared to conventional plasma exchange in the treatment of hyperviscosity syndrome.

The contribution of reduced functioning mass to chronic kidney allograft dysfunction in rats.

Chronic renal allograft dysfunction may become manifest months or years after transplantation by progressive functional deterioration associated with morphological changes that include vascular obliteration, glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Two hypotheses have evolved to explain the etiology of this process, usually described as "chronic rejection:" first, that it is primarily an antigen-dependent phenomenon influenced by continuing host alloresponsiveness; second, that nonimmunological, alloantigen-independent factors contribute to the progressive changes. Using an established model of chronic rejection of kidney transplants in rats in which the lesions progress relentlessly over time, we have determined the long-term effects of superimposing renal mass reduction on the indices of progressive allograft injury. Increasing proteinuria, a reproducible index of kidney graft dysfunction, developed after 12 weeks in all recipients of intact allografts, but was accelerated in kidneys with reduced mass, regardless of whether the organ was allogeneic or isogeneic. The coincident infiltration of macrophages and expression of cytokines and growth factors were associated with the development of glomerular sclerosis and interstitial fibrosis; such functional and morphological alterations occurred in an accelerated manner in all reduced-mass kidney allografts and isografts. Conversely, intact allografts in recipients also bearing a retained native kidney never manifested any chronic changes throughout the entire follow-up period. These findings emphasize the role of alloantigen-independent factors, particularly reduced renal mass, in the multi-factorial etiology of "chronic rejection" of kidney transplants.

Nephron supply is a major determinant of long-term renal allograft outcome in rats.

The effects of augmenting the nephron supply on indices of allograft injury were assessed in a rat model of "chronic rejection." Orthotopic renal allotransplantation into unine-phrectomized rats was followed by excision (allograft-alone group) or preservation of the remaining native kidney (allograft+native kidney group) such that the total kidney complement was either the allograft alone, or the allograft plus one retained native kidney. After 18 wk, values for GFR (1.85 +/- 0.3 ml/min) and kidney weights (2.3 +/- 0.2 g) in allograft-alone rats were far in excess of corresponding values in the allograft of allograft+native kidney rats (0.88 +/- 0.1 ml/min and 1.1 +/- 0.5 g, respectively). Proteinuria (35 +/- 2 mg/d) and allograft glomerulosclerosis (24 +/- 8%) also characterized allograft-alone but not allograft+native kidney rats, in whom glomerular structure (allograft glomerulosclerosis, 4 +/- 1%; native kidney glomerulosclerosis, 0%) and glomerular functional integrity (proteinuria 7 +/- 0.7 mg/d) were well preserved. Thus, the observed allograft protection derived from the presence of a retained recipient native kidney supports the hypothesis that a single renal allograft contains insufficient nephrons to prevent progressive renal injury, implicating nephron supply as a major determinant of long-term allograft outcome.