Chronic renal transplant loss

Chronic rejection and chronic cyclosporin toxicity in renal allografts

Recent evidence indicates that growth factors are critically important in both chronic rejection and chronic cyclosporin A toxicity, suggesting that these two entities share a common pathophysiological pathway, leading to progressive allograft failure. Here, Manuel Pascual and colleagues discuss the relevance of growth factors to chronic allograft nephropathy, and the implications for therapy in view of the great choice of immunosuppressive drugs now available.

Histologic features of chronic allograft nephropathy revealed by protocol biopsies in kidney transplant recipients

BACKGROUND

The aim of the present study was to describe the histologic features disclosed by protocol kidney transplant biopsies in patients who experienced neither acute rejection nor acute renal failure during the 2 years after transplantation.

METHODS

We studied 10 recipients of HLA-identical kidneys from living-related donors and 31 recipients of cadaveric kidneys. They were selected because, during the 2 years after transplantation, they did not experience clinical acute or chronic rejection, their renal function was normal and stable, and they underwent a protocol kidney biopsy at 3 months and at 2 years after transplantation.

RESULTS

Histologic chronic allograft nephropathy was present in 25% of patients at 3 months and in 50% at 2 years, but was absent in the recipients of HLA-identical kidneys. Histologic worsening was associated with increased donor age, the presence of asymptomatic grade I acute rejection at 3 months, and an increased cyclosporine trough level.

CONCLUSIONS

Protocol biopsies contribute important information that could be used to improve the prophylaxis of chronic allograft nephropathy.

Tolerance induction ameliorates allograft vasculopathy in rat aortic transplants. Influence of Fas-mediated apoptosis

Based on successful induction of donor-specific unresponsiveness by alloantigenic stimulation in several animal models of acute rejection, we hypothesized that similar immune manipulations would also inhibit the evolution of chronic rejection and transplant vasculopathy. To induce immune tolerance, DA rats received a PVG heart allograft and were immunosuppressed with cyclosporine for 30 d. At day 100 the animals were challenged with a PVG aortic allograft after either 1 or 18 h of cold ischemia. 8 wk after the aortic transplantation, the grafts were investigated for morphological changes, infiltrating cells, apoptosis, and Fas-Fas ligand expression. Control allografts showed advanced transplant arteriosclerosis, whereas tolerance-induced aortic allografts displayed reduced neointimal formation, less medial atrophy, fewer apoptotic cells, and fewer Fas- and FasL-expressing cells. Prolonged ischemic storage time did not profoundly alter the morphological changes of the allografts. Fas expression was found in T cells, macrophages, vascular smooth muscle cells, and endothelial cells, whereas FasL was expressed mainly by T cells and macrophages. FasL mRNA expression was evident throughout the entire allograft wall. In conclusion, induction of allospecific tolerance can effectively prevent transplant arteriosclerosis. Cold ischemia damage does not abrogate the beneficial effect of tolerance, but creates a separate identity of mainly endothelial lesions. Furthermore, Fas-mediated apoptosis appears to be involved in the pathological lesions seen in chronic rejection.

Long-term improvement in renal function after cyclosporine reduction in renal transplant recipients with histologically proven chronic cyclosporine nephropathy

BACKGROUND

Chronic cyclosporine (CsA) nephropathy, which has been unequivocally documented in recipients of heart, heart-lung, liver, or bone marrow transplants, as well as in nontransplant situations, usually results in a progressive deterioration of renal function. In this study, we assessed the potential reversibility of chronic CsA nephropathy in renal transplant recipients.

PATIENTS AND METHODS

Twenty-three renal transplant patients with biopsy-proven CsA nephropathy associated with long-term CsA administration (27+/-4 months) were followed up for more than 2 years after CsA reduction (18/23 patients) or withdrawal (5/23 patients) and addition of azathioprine. Changes in effective renal plasma flow and glomerular filtration rate were assessed before and 2 years after CsA reduction, whereas serum creatinine, proteinuria, blood pressure, and CsA concentrations were monitored up to 5 years.

RESULTS

At 2-year follow-up, glomerular filtration rate increased from 40+/-3 to 47+/-4 (P<0.05) and effective renal plasma flow from 217+/-23 to 244+/-24 ml/min/1.73 m2 (NS). Mean arterial pressure significantly decreased from 98.7+/-2.9 to 93.1+/-2.7 mmHg (P<0.05). There was no significant change in renal vascular resistance, filtration fraction, or albumin excretion. A significant decrease in serum creatinine was also observed during the whole follow-up (73+/-6.5 months). CsA reduction was followed by only one episode of acute reversible rejection; chronic rejection developed in three patients 2 years or later after CsA reduction.

CONCLUSIONS

These data suggest that CsA nephropathy participates in graft dysfunction in a small group of renal transplant recipients. In addition, graft dysfunction may be reversible when CsA dosage is reduced early after diagnosis of chronic CsA nephropathy.

Recipient body surface area as a predictor of posttransplant renal allograft evolution

BACKGROUND

The aim of the present study was to analyze whether minor differences in recipient body surface area have any predictive value on renal allograft evolution.

METHODS

For this study, we considered 236 pairs of recipients who received a kidney from the same donor at our center between March 1985 and December 1995. Pairs in whom at least one patient presented any of the following events were excluded: graft loss during the first year of follow-up, diabetes mellitus, noncompliance with treatment, chronic pyelonephritis, and recurrent or de novo glomerulonephritis. Recipients of each pair were classified as large or small according to their body surface area (BSA). The percentage difference of BSA in each pair was calculated, and two cohorts of pairs were defined: BSA difference < or = 10% (n=76 pairs) and BSA difference >10% (n=70 pairs).

RESULTS

The large recipients of the cohort with a BSA difference >10% showed a higher incidence of posttransplant delayed graft function (22/70 vs. 12/70, P=0.075), hypertension at 1 year of follow-up (51/70 vs. 35/70, P=0.006), and a higher serum creatinine level at 1-year follow-up (173 vs. 142 micromol/L, P=0.003), whereas in the cohort with a BSA difference < or = 10%, posttransplant evolution in large and small recipients was not different. Multivariate analysis showed that recipient BSA was an independent predictor of delayed graft function, posttransplant hypertension, and serum creatinine at 1-year follow-up.

CONCLUSIONS

Relatively small differences in recipient BSA influence renal allograft evolution. Consequently, our data support that recipient size should be taken into consideration for renal allograft allocation.

Mechanisms and management of acute renal allograft rejection

We used RT-PCR for the molecular characterization of human renal graft rejection. The studies showed that intragraft display of mRNA encoding cytotoxic attack molecule granzyme B, and immunoregulatory cytokines IL-10 or IL-2 are correlates of acute rejection, and intrarenal expression of TGF-1 mRNA, of chronic rejection. The current immunosuppressive protocol involves the use of multiple drugs, each directed at a discrete site in the T-cell activation cascade and each with distinct side effects. The immunosuppressants can be classified as inhibitors of: transcription (CsA, tacrolimus); nucleotide synthesis (azathioprine, mycophenolate mofetil, and mizoribine); growth factor signal transduction (sirolimus); and differentiation (DSG). Polyclonal antibodies and monoclonal antibodies directed at cell surface proteins are quite effective as induction therapy or anti-rejection drugs.

[Immunologic, alloantigen-dependent factors in chronic graft rejection]

BACKGROUND

The pathogenesis of chronic renal allograft rejection is still speculative. Amongst other factors immune-mediated graft injury is proposed. Since the allo-antigen is specifically recognized by the variable (V) alpha and beta chains of the T-cell receptor, a restricted T-cell repertoire might support the notion of allo-antigen involvement in chronic rejection.

METHODS

By the means of semiquantitative polymerase chain reaction the V beta families 1-20 were assessed in allograft biopsies with histologically confirmed chronic and acute rejection. At the same time the V beta repertoire was analyzed in PBMC.

RESULT

The intragraft V beta repertoire was limited to 1 to 3 dominant V beta families in chronic and acute rejection. The response was highly individual and did not correlate to the type or degree of HLA mismatches. The T-cell repertoire in PBMC was polyclonal and did not reflect the immune response in the graft.

CONCLUSION

The finding of a restricted V beta repertoire in both forms of rejection might indicate an immunological basis not only for acute, but also for ongoing chronic rejection. Tailor-made antibodies against the dominant V beta clones might provide a tool for selective immunosuppression in both entities of rejection targeting only those T cells which were activated by allo-antigens.

Low dose angiotensin converting enzyme inhibition and glomerular permselectivity in renal transplant recipients

In this study, we determined the fractional clearance of neutral polydisperse dextrans (theta D) and monodisperse dextran sulfate (theta DS) to describe glomerular size and charge selectivity in 25 renal transplant recipients with proteinuria. Thirteen were treated with low dose lisinopril for six months (group 1) and 12 patients without ACE inhibitor therapy formed group 2. Mean arterial blood pressure was stable (group 1, 112 +/- 4; group 2, 109 +/- 2 mm Hg at baseline and after 6 months) whereas creatinine clearance, glomerular filtration rate and renal plasma flow decreased nonsignificantly but were comparable at any time. Lisinopril treatment lowered filtration fraction (22 +/- 2 vs. 19 +/- 2%, P = 0.07) whereas no change was seen in group 2 (20 +/- 2%). The fractional protein excretion (mg urinary protein per day/ml creatinine clearance per day) was stable in group 1, but significantly increased in group 2. The same pattern was found for theta D larger than 56 A. theta DS was stable and consistently elevated in both groups at any time. We conclude that low dose ACE inhibitor treatment in proteinuric renal transplant recipients stabilizes glomerular size selectivity independently of its systemic hemodynamic effects.

CD28-b7 blockade in organ dysfunction secondary to cold ischemia/reperfusion injury

Ischemic injury to cadaver organs is a major risk factor for development of chronic organ dysfunction. We have recently shown that the B7 costimulatory pathway plays a critical role in early organ dysfunction developing after renal cold ischemia/reperfusion injury. We extended these observations to investigate the role of this pathway in the development and progression of chronic organ dysfunction following such injury. Uninephrectomized rats which underwent cold ischemia/reperfusion injury developed progressive proteinuria as compared to uninephrectomized controls. Animals treated with CTLA4Ig, which blocks B7 costimulation, starting on the day of injury had significantly better long-term survival and developed significantly less proteinuria than control animals treated with control Ig. RT-PCR analysis of kidney tissue showed significant reduction in expression of activation and inflammatory cytokines, chemoattractants, and growth factors, as compared to controls. Delaying administration of CTLA4Ig for one week, but not four weeks, after injury was still effective in ameliorating development of progressive proteinuria. Interestingly, selective blockade of B7-1 by a mutant form of CTLA4Ig had no effect on early or chronic organ dysfunction. These findings indicate the long-term functional and molecular consequences of experimental cold ischemia/reperfusion injury, and suggest that B7-2 is critical in the development of organ dysfunction following ischemic injury, even in the absence of alloantigen.

Indirect allorecognition of major histocompatibility complex allopeptides in human renal transplant recipients with chronic graft dysfunction

BACKGROUND

It has been suggested that T cells primed by processed donor major histocompatibility complex antigen (the "indirect" pathway of allorecognition) may be responsible for mediating chronic allograft rejection. The purpose of this study was to develop a clinically useful assay to study the occurrence of indirect allorecognition during chronic rejection in humans.

METHODS

A panel of 20 mer peptides corresponding to the hypervariable regions of HLA-DRB1*0101, DRB1*1501, and DRB1*0301 were synthesized. Lymphocytes obtained from renal allograft recipients were cocultured with these peptides. Proliferation was assayed by DNA incorporation of [3H]thymidine, and positive proliferation was defined by a statistically significant increase in counts per minute over background with a minimum stimulation index of 2. The precursor frequency of allopeptide reactive T cells was determined by limiting dilution analysis.

RESULTS

Lymphocytes from 82% of patients who were mismatched for at least one of the three DR molecules and had chronic allograft dysfunction specifically proliferated to the mismatched allopeptides (n=11). Proliferation was seen in only 6% of control subjects (2/33, P<0.0001). The proliferative response was low grade and was best detected on day 7-8 of culture in vitro. The precursor frequency of peptide-specific T cells was more than 10-fold higher compared with controls (P<0.001).

CONCLUSIONS

These data demonstrate for the first time that T cells of patients with chronic graft dysfunction are primed to recognize and respond to specific donor-derived major histocompatibility complex allopeptides. Our results support the hypothesis that T cells primed via the indirect pathway of allorecognition may be important mediators of chronic rejection and provide the rationale to develop specific therapeutic strategies to prevent or interrupt this process.

Synthetic MHC class I peptide prolongs cardiac survival and attenuates transplant arteriosclerosis in the Lewis-->Fischer 344 model of chronic allograft rejection

BACKGROUND

A synthetic peptide corresponding to residues 75-84 of the alpha1 domain of HLA-B7 molecule (HLA-B7.75-84 [Allotrap]) inhibits cytotoxic T cell function in vitro and, when combined with subtherapeutic doses of cyclosporine (CsA), prolongs allogeneic cardiac survival. We now report the effects of HLA-B7.75-84 in the Lewis --> Fischer 344 rat model of chronic cardiac allograft rejection.

METHODS

Animals were treated with CsA (5 mg/kg/day s.c.) alone or with CsA plus alternate-day HLA-B7.75-84 (20 mg/kg/day i.p.) for 30 days. Allografts harvested at day 100 were evaluated by histology and immunohistology.

RESULTS

HLA-B7.75-84 plus CsA prolonged allograft survival (75% of allografts survived >90 days) compared with CsA alone (27% of allografts survived >90 days) (P<0.05). Histologic examination of control allografts showed dense cellular infiltrates and moderate transplant arteriosclerosis (>75% of arteries showed 10-20% occlusion). Infiltrating leukocytes consisted of macrophages (>75% cells), T cells (10-20%), and rare natural killer cells (<5%). Cell activation was shown by expression of major histocompatibility complex class II antigens (>75%), interleukin (IL) 2 receptor (5-10%), and staining for IL-2 (approximately 5% of intragraft mononuclear cells), interferon-gamma (5-10%) and tumor necrosis factor-alpha (approximately 20%). Leukocytes and vessels also showed labeling for the fibrogenic cytokine, transforming growth factor-beta, and all vessels showed dense deposition of IgG (IgG2a, IgG2b) and C3. The addition of HLA-B7.75-84 decreased overall cellularity (P<0.01) without affecting the composition of the infiltrate, but completely prevented transplant arteriosclerosis, diminished myocardial injury, and abrogated expression of IL-2R, IL-2, interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta. HLA-B7.75-84 also blunted the humoral response, which resulted in a predominance of vascular deposition of the non-complement-fixing IgG2c isotype and a concomitant decrease in C3.

CONCLUSIONS

Therapy with synthetic class I major histocompatibility complex peptide (HLA-B7.75-84) attenuates key histologic features of graft arteriosclerosis, in association with inhibition of multiple cytokines and growth factors and modulation of host alloantibody responses in vivo, which is of interest since Allotrap is currently undergoing clinical trials.

Cell-mediated cytotoxicity: a predictor of chronic rejection in pediatric HLA haploidentical renal transplants

BACKGROUND

Recipient antidonor cytotoxic T-cell activity has been associated with graft loss and acute rejection in renal allograft recipients. The role of immunologic mechanisms in the development of chronic graft rejection is controversial. We analyzed all living related renal transplants performed at Children's Hospital (Boston, MA) from 1983 to 1995 to assess whether cell-mediated cytotoxicity, determined in vitro and measured before transplantation, was predictive of chronic rejection.

METHODS

Eighty-three patients were studied retrospectively. Fifty-seven patients with one haplotype-matched renal transplants from living related donors were studied to determine the association between cell-mediated lympholysis (CML) level, acute rejection, chronic rejection, and graft failure. Acute rejection was defined by the decision to treat. Chronic rejection was defined by histology and/or the absolute serum creatinine value using an increasing serum creatinine level >1.0 mg/dl for children less than 3, a creatinine level >1.5 mg/dl for children between 3 and 10 years of age, and a creatinine level >2.0 mg/dl for children above 10 years of age. Return to dialysis or retransplantation was considered graft failure.

RESULTS

Of the 57 haploidentical patients, there were 33 males and 24 females. The mean age at transplant was 11.1 years (SD=6.7). Twelve patients developed chronic rejection, 24 patients developed acute rejection, and 7 patients had graft failure. Pretransplant cytotoxic T lymphocyte activity was associated with chronic rejection (P=0.001) and graft failure (P=0.013) but only marginally with acute rejection (P=0.058). Controlling for age and sex, Cox's proportional hazards model revealed that CML level was predictive of time to chronic rejection (P<0.01) but not acute rejection (P=0.11). It was estimated that every 1-unit increase in CML level raises the monthly risk of chronic rejection by 7%. Ten children received HLA-identical kidneys from their siblings. There were no episodes of chronic rejection after 5 years. Two patients with high CML levels had episodes of acute rejection; both patients responded to treatment.

CONCLUSION

Our data demonstrate an association between pretransplant cell-mediated cytotoxicity and the occurrence of chronic rejection in living related one-haploidentical renal transplants in pediatric patients.

T-cell costimulatory blockade in experimental chronic cardiac allograft rejection: effects of cyclosporine and donor antigen

Chronic rejection is a T cell-dependent process and blockade of the CD28-B7 T-cell costimulatory activation pathway by the fusion protein CTLA4Ig has been shown to prevent the development of accelerated graft arteriosclerosis in a rat model of chronic cardiac allograft rejection. The effectiveness of T-cell costimulatory blockade at preventing chronic allograft rejection in a clinically relevant model in combination with cyclosporine therapy has not been investigated. Using the well-established LEW into F334 heterotopic cardiac allograft model, we show that when cyclosporine is administered in combination with CTLA4Ig, it abrogates the previously demonstrated protective effect of CTLA4Ig in preventing chronic allograft rejection. Long-term surviving allografts from animals treated with a combination of cyclosporine and CTLA4Ig had a mean vascular luminal occlusion of 42.2%, affecting more than 90% of graft vessels due to accelerated arteriosclerosis. This was associated with up-regulation of intragraft expression of mRNA for CD4, the costimulatory molecule B7, the T-cell cytokine interferon-gamma, monocyte chemoattractant protein-1, and the fibrogenic growth factor transforming growth factor-beta; all have been previously shown to be associated with development of chronic rejection in this model. In comparison, the addition of donor splenocytes to the combination of CTLA4Ig and cyclosporine therapy protocol significantly reduced the amount of arteriosclerosis; mean vascular luminal occlusion was 11.3%, affecting approximately 50% of vessels. This was associated with decreased intragraft expression of CD4, B7, interferon-gamma, monocyte chemoattractant protein-1, and transforming growth factor-beta. These data indicate that the mechanism of action of CTLA4Ig in attenuating chronic rejection is cyclosporine sensitive, and that strategies implying combination of CTLA4Ig and cyclosporine may not be clinically desirable. Administration of donor antigen may be necessary if CTLA4Ig and cyclosporine are to be combined, to prevent the process of chronic rejection.

Early protocol renal allograft biopsies and graft outcome

To evaluate whether biopsies performed early after transplantation in stable grafts can predict graft failure due to chronic transplant nephropathy, a protocol biopsy was performed at three months in 98 patients treated with antilymphocytic antibodies, cyclosporine and prednisone. Patients were followed for 58 +/- 16 months. Histological diagnosis according to the Banff schema were: normal (N = 41), borderline changes (N = 12), chronic transplant nephropathy (CTN; N = 30), CTN associated to borderline changes (N = 11) and acute rejection (N = 4). Biopsies displaying acute rejection were not considered for statistical analysis. Since clinical characteristics of patients displaying CTN either with or without tubulitis were not different, biopsies were grouped as presence or absence of CTN. Patients displaying CTN had an increased incidence of acute rejection before performing biopsy (24.3 vs. 3.9%, P = 0.003), a higher mean cyclosporine level until biopsy (242 +/- 74 vs. 214 +/- 59 ng/ml, P = 0.049) and a lower actuarial graft survival (80.5% vs. 94.4%, P = 0.024). We conclude that early protocol biopsies are useful to detect patients at risk of losing their graft due to chronic transplant nephropathy.

Molecular executors of cell death--differential intrarenal expression of Fas ligand, Fas, granzyme B, and perforin during acute and/or chronic rejection of human renal allografts

Two distinct cytolytic pathways have been characterized: one in which the interaction between the Fas antigen and its ligand results in apoptosis, and another in which the pore forming protein perforin and the serine protease granzyme B contribute to DNA fragmentation and cell death. We investigated intrarenal expression of these molecular executors of cell death in light of the potential participation of cytolytically active cellular elements in the antiallograft repertory. Reverse transcriptase-polymerase chain reaction was used to identify intrarenal expression of Fas antigen, Fas ligand, granzyme B and perforin in eighty human renal allograft biopsies; mRNA display was correlated with the Banff histological diagnosis of renal allografts. Our studies demonstrate that: (1) intrarenal expression of Fas ligand mRNA and of granzyme B mRNA are correlates of acute but not chronic rejection; (2) Fas ligand mRNA is not detectable in allografts in the absence of rejection; (3) intrarenal coexpression of members of each lytic pathway (Fas ligand and Fas, granzyme B, and perforin) and that of both pathways (e.g., Fas ligand and granzyme B) are correlates of acute rejection; and (4) a direct correlation exists between the histological severity of acute rejection and intrarenal coexpression of mRNA encoding Fas ligand, Fas, granzyme B, and perforin. Our studies identify, for the first time, the differential expression of the two major lytic pathways in acute and chronic allograft rejection and suggest that specific therapy directed at the cytotoxic attack molecules might be efficacious in the prevention and/or treatment of acute rejection.

Antihypertensive drug treatment in chronic renal allograft rejection in the rat. Effect on structure and function

To gain insight into the contribution of immunologic and hemodynamic factors in the progressive demise of structure and function in chronic renal allograft dysfunction, we studied the histological changes, the immunostainable glomerular anionic sites, and glomerular capillary hydrostatic pressures of rat renal allografts with chronic rejection. Recipient animals were left untreated, received 8 weeks of treatment with the immunosuppressive drug cyclosporine, or received antihypertensive drugs consisting of the combination of reserpine, hydralazine and hydrochlorothiazide, the angiotensin-converting enzyme inhibitor cilazapril, or the angiotensin II receptor blocker L-158,809. Grafts in untreated recipients developed chronic interstitial inflammation, as well as vascular and glomerular lesions consistent with chronic rejection. These lesions were associated with immunohistochemical loss of the negatively charged heparan sulfate proteoglycan side chain. All treatment regimens decreased the systemic and glomerular capillary pressures and were associated with no loss of function, decreased proteinuria, and a tendency to improved graft function. Cyclosporine prevented all histological manifestations of rejection, and antihypertensive drugs decreased the extent of glomerular mesangiolysis and glomerulosclerosis; L-158,809 and cilazapril also inhibited graft atherosclerosis and tubular atrophy. We conclude that chronic rejection is primarily an immune-mediated process, but hemodynamic and angiotensin II-mediated effects may play a pivotal role in the expression of immune-mediated lesions.

Expression of TGF-beta 1 and matrix proteins is elevated in rats with chronic rejection

The pathogenesis of fibrosis in chronic renal allograft rejection remains unknown. Since TGF-beta 1 plays a key role in fibrogenesis, we studied a rat model of chronic allograft rejection that shows similarities to the structural lesion described in patients. We previously demonstrated an increased expression of TGF-beta 1 in human kidney biopsies with acute and chronic rejection. Recipients of renal allografts (F344-Lewis) and isografts (Lewis-Lewis) were sacrificed at 4, 8, 24 and 52 weeks. Characteristic histologic changes of chronic rejection developed in the allografts as early as four weeks and were accompanied by progressive albuminuria significant by eight weeks. Allografts showed a progressive increase in mRNA expression of TGF-beta 1 and matrix proteins during the 52 week course. Increased matrix deposition by immunofluorescence was mostly present in the interstitium and vessels early and in all kidney compartments later. The mRNA expression of plasminogen activator inhibitor, a protease inhibitor stimulated by TGF-beta 1, increased along with TGF-beta 1 and matrix proteins. These results suggest that the fibrosis of chronic renal allograft rejection is mediated, at least partly, by the dual action of TGF-beta 1 on matrix deposition and degradation.

Restricted T cell V beta repertoire in renal allografts during acute and chronic rejection

Allo-MHC specific antigen recognition might not only be involved in acute, but also in chronic rejection. The clonotypic specificity of the T-cell receptor to recognize all-MHC is located in the variable (V) alpha and beta chain. A restricted T-cell receptor repertoire could support an immunological basis for chronic rejection. The novel feature of this study is that V beta repertoire was assessed in ongoing chronic rejection before end-stage renal failure and in acute rejection. V beta s 1 to 20 were quantitated by PCR in PBMC and biopsies of rejecting renal allografts. The V beta pattern in PBMC demonstrated a polyclonal distribution. However, the intragraft V beta repertoire was restricted to 1 to 3 dominant V betas and highly individual in 9 of 12 patients. Number and type of the HLA mismatch and the time interval between transplantation and biopsy did not correlate to the V beta distribution. The individual response is attributed to genetic predisposition factors of the recipient. Therefore, the restriction of the V beta repertoire indicates allo-MHC dependent immune processes not only in acute, but also in ongoing chronic rejection. Tailor-made antibodies against dominant V betas might offer specific individual immunosuppression in treating both acute and ongoing chronic rejection.

Determinants of chronic renal allograft rejection in cyclosporine-treated recipients

We analyzed the development of chronic rejection in 511 kidney-only renal transplants in 507 patients between July 1987 and November 1994. A database was established for recipients > or = 18 years old who received cyclosporine-based immunosuppression and demonstrated graft survival for a minimum of 12 months. The 347 recipients of cadaver transplants (67.9%) and 164 recipients of live donor transplants (32.1%) were followed for 12 to 102 months (mean 51 months). Chronic rejection was diagnosed in 124 transplants (24%), with a mean time to diagnosis of 23+/-18 months (range 3-92). Risk factors were identified in a multivariate analysis using the Cox model. The impact of the timing and severity of rejection episodes was analyzed in a univariate model. The presence of chronic rejection resulted in decreased (P=0.0001) 5-year graft survival for both cadaver graft (83.7% vs. 58.2%) and live donor graft (93.2% vs. 53.1%) recipients. Significant variables for the development of chronic rejection included an acute rejection episode (P=0.0001), a black recipient (P=0.0006), donor age > or = 50 years (P=0.006), and a serum creatinine level >2.0 mg/dl by 6 months after transplantation. Severity of rejection measured by peak serum creatinine or posttreatment return to baseline was not related to chronic rejection. However, acute rejection episodes lasting for more that 5 days (P=0.03) or occurring after 6 months (P=0.001) did influence time to chronic rejection. In addition, mismatching for donor-recipient race was a significant (P=0.008) risk factor for recipients of cadaver grafts. We conclude that acute rejection is the most significant risk factor for chronic rejection, and the long-term fate of grafts may be determined as early as the first 6 months. Racial matching of donor-recipient pairs may be useful to minimize chronic rejection risk. Future advances that diminish the incidence and severity of acute rejection may have the greatest impact on long-term survival.

Blockade of T-cell costimulation prevents development of experimental chronic renal allograft rejection

Blocking CD28-B7 T-cell costimulation by systemic administration of CTLA4Ig, a fusion protein which binds B7 molecules on the surface of antigen-presenting cells, prevents rejection and induces tolerance in experimental acute allograft rejection models. We tested the effect of CTLA4Ig therapy on the process of chronic renal allograft rejection using an established experimental transplantation model. F344 kidneys were transplanted orthotopically into bilaterally nephrectomized LEW recipients. Control animals received low dose cyclosporine for 10 days posttransplantation. Administration of a single injection of CTLA4Ig on day 2 posttransplant alone or in addition to the low dose cyclosporine protocol resulted in improvement of long-term graft survival as compared with controls. More importantly, control recipients which received cyclosporine only developed progressive proteinuria by 8-12 weeks, and morphological evidence of chronic rejection by 16-24 weeks, including widespread transplant arteriosclerosis and focal and segmental glomerulosclerosis, while animals treated with CTLA4Ig alone or in addition to cyclosporine did not. Competitive reverse transcriptase-PCR and immunohistological analysis of allografts at 8, 16, and 24 weeks showed attenuation of lymphocyte and macrophage infiltration and activation in the CTLA4Ig-treated animals, as compared with cyclosporine-alone treated controls. These data confirm that early blockade of the CD28-B7 T-cell costimulatory pathway prevents later development and evolution of chronic renal allograft rejection. Our results indicate that T-cell recognition of alloantigen is a central event in initiating the process of chronic rejection, and that strategies targeted at blocking T-cell costimulation may prove to be a valuable clinical approach to preventing development of the process.

Growth factor transcripts in rat renal transplants

Locally produced cytokines and growth factors may mediate tissue remodelling processes, as observed in renal transplants exposed to ischemia or acute rejection episodes. The present study was designed to investigate mRNA transcript levels of platelet-derived growth factor (PDGF)-receptor beta, PDGF-A, PDGF-B, fibroblast growth factor-1, and transforming growth factor beta 1 in normal rat kidneys, in kidneys following contralateral nephrectomy and in renal transplants with acute or chronic rejection. Platelet-derived growth factor-receptor beta mRNA levels increased significantly in syngeneic and allogeneic transplants in the first week after transplantation and in allogeneic transplants with chronic rejection. Immunohistochemistry showed induction of PDGF-receptor beta protein expression on vascular wall cells in such grafts. Platelet-derived growth factor-A chain mRNA levels increased in day 3 allografts and in syngeneic LEW grafts, while PDGF-B chain mRNA levels showed no significant changes with transplantation. Fibroblast growth factor-1 mRNA levels were detectable in normal kidneys, tended to decrease with acute rejection, and increased significantly in chronic rejection. Transforming growth factor-beta 1 transcripts increased in acute and chronic rejection; immunohistochemistry showed predominantly glomerular localization of the transforming growth factor-beta 1 protein. We conclude that transplantation and rejection are associated with changes in the intragraft mRNA levels for several growth factors; chronic rejection is characterized by an increase in fibroblast growth factor-1 and transforming growth factor-beta 1 transcript levels.

Renal transplantation: progress and prospects

Despite encouraging and improving results, organ transplantation is still hampered by a shortage of organs, chronic transplant loss, and a changed patient population. Liberal inclusion criteria for dialysis and/or renal transplantation and the increasing unwillingness to donate organs in some countries had led to a growing imbalance between the numbers of transplantations performed and patients on waiting lists. Until now, poorly understood chronic transplant dysfunction is responsible for a still unchanged graft loss of approximately 5% per year. The patient population has changed to include more multimorbidity and an increasing number of risk factors (age, diabetes mellitus, former [failed] transplantations, or preexisting cardiovascular diseases). The recommendation for a against dialysis or transplantation has become increasingly difficult for the responsible physician. Newly developed immunosuppressant drugs, an increasing consideration regarding living organ donation, or xenotransplantation in the future may solve this dilemma. New reflections and considerations about the ethical background of transplantation medicine are necessary.

Intragraft TGF-beta 1 mRNA: a correlate of interstitial fibrosis and chronic allograft nephropathy

Chronic allograft nephropathy is a relentlessly progressive process and a major cause of long-term graft dysfunction and ultimate failure. Interstitial fibrosis, tubular atrophy, and glomerular and vascular lesions characterize this mechanistically unresolved disorder. Given the prominent role of TGF-beta 1 in tissue repair and in fibrosis, we have explored the hypothesis that fibrosis and chronic allograft nephropathy would be distinguished by intragraft TGF-beta 1 mRNA expression. This postulate was tested by mRNA phenotyping of RNA isolated from 127 human renal allograft biopsies. Reverse transcription assisted polymerase chain reaction was used to amplify and identify ingraft gene expression. Our investigation demonstrated a significant correlation between intragraft TGF-beta 1 mRNA display and renal allograft interstitial fibrosis and chronic allograft nephropathy. In contrast, intragraft expression of mRNA encoding immunoregulatory cytokines, IL-2, IFN-gamma, IL-4, IL-10, or cytotoxic attack molecules, granzyme B and perforin was not a correlate of interstitial fibrosis or chronic allograft nephropathy. Our studies identify, for the first time, a significant association between intragraft TGF-beta 1 mRNA expression and renal allograft interstitial fibrosis, and advance a candidate molecular mechanism for chronic allograft nephropathy.

Atubular glomeruli in patients with chronic allograft rejection

Morphometric studies were performed in 15 patients with chronic renal allograft rejection. Biopsy cores were serially sectioned so that atubular glomeruli could be identified and volumes of individual glomeruli could be measured. Control tissue was obtained from 9 cadaver donors and 8 living donors. Serial sectioning revealed that atubular glomeruli were as common as sclerotic glomeruli in chronic rejection. The prevalence of atubular glomeruli averaged 18 +/- 15% (mean +/- SD) in recipients with chronic rejection, 2 +/- 2% in cadaver donors, and 1 +/- 3% in living donors (P<0.05, recipients vs. donor groups). In comparison, the prevalence of sclerotic glomeruli averaged 19 +/- 13%, 4 +/- 7%, and 7 +/- 10% in the three groups (P<0.05 recipients vs. donor groups). Atubular glomeruli exhibited reduced mean volume (3.1 +/- 0.9 x 10(6)micron(3) vs. 4.5 +/- 1.5 x lO(6)micron(3), atubular vs. open glomeruli in recipients, P < 0.05) but could not be distinguished from open glomeruli by their appearance on single sections. Recipients with chronic rejection exhibited tubular atrophy and interstitial fibrosis with an increase in the interstitial volume fraction to 51 +/- 14% as compared with 29 +/- 6% in cadaver donors and 17 +/- 2% in living donors (P<0.05 recipients vs. donor groups). Similar interstitial expansion was observed in recipients with a high prevalence of atubular glomeruli, recipients with a high prevalence of sclerotic glomeruli, and also in four recipients in whom the predominant form of glomerular injury was transplant glomerulopathy. These results suggest that mechanisms responsible for development of atubular glomeruli are among the processes that contribute to loss of graft function in patients with chronic rejection.

HLA-identity--long-term renal graft survival, acute vascular, chronic vascular, and acute interstitial rejection

The object is analysis of the impact of acute and chronic rejection on long-term function in HLA-identical renal transplants performed from 1967 to 1995 by the Saskatchewan Renal Transplant Unit. Forty-eight grafts in 46 patients were studied, of which 39 were first and nine second grafts. Forty-two were for primary and six for secondary renal disease. Thirty-five received azathioprine/prednisone prophylaxis, and 13 received cyclosporine/prednisone with/without azathioprine. Ten-year all graft actuarial survival was 84%, 10-year actuarial graft survival in patients with primary renal disease 90%, and with subsequent graft after first HLA graft failed 97.5%, for age-matched population 98.5% (P=NS). Overall death rate was 8.7% (4/46); in secondary renal disease patients 50% (3/6); in primary renal disease patients 2.5% (1/40, P=0.004). All (9/9) HLA-identical second grafts functioned. Acute rejection with azathioprine/prednisone prophylaxis occurred in 55% (9/17) of grafts treated with <6 pre-graft blood transfusions, with the same prophylaxis but >5 units in 12% (2/16, P=0.015), and with cyclosporine prophylaxis in 13% (2/15, P=0.021). Pulse steroids alone reversed all acute rejection. Grafts failed in 6.2% (3/48), all in primary renal disease patients and one from technical one noncompliance, and one chronic rejection. Graft cost/patient/year amortized over 9 years is $3,855 and comparable dialysis cost would be $35,650; cost for all patients on dialysis for 9 years would be $11,293,320 while comparable graft cost was 1,221,418, a savings of 89.2%. Our conclusions are that HLA-identity associates with the following: (1) a 10-year actuarial survival in primary renal disease that equals that of the age-matched population, (2) uniform success in repeat grafts, (3) virtual absence of chronic rejection despite a high incidence of acute rejection in azathioprine/prednisone grafts that (4) always reversed on pulse steroids, and (5) a cost reduction for grafting of 93.2% compared with dialysis therapy.