Hallgrimur Benediktsson

Reproducibility of the banff classification of renal allograft pathology : inter- and intraobserver variation

The present study was undertaken to investigate the inter- and intraobserver variation in use of the scoring system for glomerulitis, vasculitis, interstitial inflammation, tubulitis and arteriolar hyalinosis that is an essential part of the recently proposed Banff classification of renal allograft biopsies. Seventy-seven biopsies done less than 90 days after transplantation were included. The scoring was done blindly by five pathologists on biopsies stained with H&E and PAS. The volume fraction of interstitial inflammation was estimated. Spearman rank correlation coefficient and kappa values were used for the evaluation of reproducibility. The results of both inter- and intraobserver variability showed a good correlation and reasonable kappa values for vasculitis, interstitial inflammatory infiltration, and tubulitis. Less-good correlation was found for glomerulitis and arteriolar hyalinosis. The interobserver kappa score for grading of the rejection severity was 0.40 overall but 0.56 when only presence or absence of acute rejection was considered and 0.66 for presence or absence of vasculitis. Weighted kappa values for interobserver vasculitis score and rejection grading were 0.58 and 0.55, respectively. A strong association existed between the volume fraction of interstitial inflammation and the semiquantitative scoring for interstitial inflammation. In conclusion, the good correlations for the key elements in the grading of the allograft biopsies in the present classification system, confirmed the utility of the defined criteria for grading rejection. More precisely defined criteria or simplification of the scoring system are needed for glomerulitis and arteriolar hyalinosis--parameters not used in the diagnosis of 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.

Antibody Response Against Perlecan and Collagen Types IV and VI in Chronic Renal Allograft Rejection in the Rat

Chronic rejection is the leading cause of late renal transplant failure. Various structural lesions are observed in grafts undergoing chronic rejection including glomerular basement membrane (GBM) duplications. The well-established Fisher (F344) to Lewis (LEW) rat renal transplant model for chronic rejection was used to assess the presence and role of the humoral immune response against graft antigens during chronic rejection. LEW recipients of F344 allografts develop transplant glomerulopathy and produce IgG1 antibodies directed against F344 GBM preparations that are detectable 3 weeks after transplantation. Glomerular IgG1 deposition was observed that in vitro co-localized with a rabbit anti-rat GBM antiserum in rejecting F344 grafts; elution experiments of isolated glomeruli yielded IgG1 antibodies reactive in vitro with F344 GBM, but not LEW GBM. Prevention of acute rejection by transient treatment of the recipients with cyclosporin A completely abrogated the production of anti-GBM antibodies. Using proteomic techniques we identified the antigens recognized by the LEW posttransplant sera as being the heparan sulfate proteoglycan perlecan and the alpha1 chain of collagen type VI in association with the alpha5 chain of collagen type IV. In conclusion, LEW recipients of F344 kidney grafts produce IgG1 antibodies against donor type perlecan and alpha1(VI)/alpha5(IV) collagen and develop transplant glomerulopathy. These data implicate an important role for the humoral immune response in the development of glomerulopathy during chronic rejection.

Histopathologic features aid in predicting risk for progression of IgA nephropathy.

BACKGROUND AND OBJECTIVES IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide. Accurately identifying patients who are at risk for progressive disease is challenging. The extent to which histopathologic features improves prognostication is uncertain. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We studied a retrospective cohort with biopsy-proven IgAN in Calgary, Canada. Renal biopsies were reviewed by a nephropathologist with histopathologic data abstracted using a standardized form. The primary outcome was the composite of doubling of serum creatinine, ESRD, or death. Spline models defined significant levels of interstitial fibrosis, glomerulosclerosis, hypertension, proteinuria, and creatinine. The prognostic significances of clinical and histopathologic parameters were determined using Cox proportional hazards models. RESULTS Data from 146 cases were available for analysis with a median follow-up of 5.8 years. Greater than 25% interstitial fibrosis, >40% glomerular sclerosis, and a systolic BP >150 mmHg were risk thresholds. In univariable analyses, baseline creatinine, proteinuria, systolic BP, glomerular sclerosis, interstitial fibrosis, and crescentic disease were predictors of the primary outcome. In multivariable models adjusted for clinical characteristics, interstitial fibrosis (hazard ratio [HR]2.7; 95% confidence interval [CI] 1.2 to 6.0), glomerular sclerosis (HR 2.6; 95% CI 1.2 to 4.5), and crescents (HR 2.4; 95% CI 1.2 to 5.1) remained independent predictors of the primary outcome and significantly improved model fit compared with clinical characteristics alone. CONCLUSIONS Baseline histopathologic parameters are independent predictors of adverse outcomes in IgAN even after taking into consideration clinical characteristics. Relatively small degrees of interstitial fibrosis confer an increased risk for progressive IgAN.

Glomerular deposition of C1q and anti-C1q antibodies in mice following injection of antimouse C1q antibodies.

Anti‐C1q autoantibodies are present in the serum of patients with different autoimmune diseases such as systemic lupus erythematosus (SLE). The occurrence of these autoantibodies correlates with renal involvement. In the present study we examined whether injection of rabbit antimouse C1q antibodies in mice leads to deposition in kidneys. Injection of healthy mice with a single dose of rabbit IgG antimouse C1q antibodies resulted in deposition of both C1q and IgG anti‐C1q in glomeruli. The pattern of deposition observed in the glomeruli of mice injected with antimouse C1q antibodies both at 24 h and 2 weeks was both glomerular basement membrane (GBM)‐associated and mesangial. Injection of control IgG did not have a detectable effect on circulating C1q levels, and no deposition of either C1q or rabbit IgG was seen at 24 h. The deposition of rabbit antimouse C1q and C1q in glomeruli resulted in complement activation, as assessed by C3 deposition, and influx of leucocytes associated with albuminuria in some, but not all mice. In none of the control mice was albuminuria observed. This report is the first to show that anti‐C1q antibodies deposit in the healthy glomerulus together with autologous C1q. This deposition is stable for at least 2 weeks, causes complement activation, leucocyte influx and can lead to mild albuminuria.

Cardiac allograft atherosclerosis in the rat. The effect of histocompatibility factors, cyclosporine, and an angiotensin-converting enzyme inhibitor.

Cardiac transplant atherosclerosis is thought to result from immune-mediated vessel wall injury. The present experiments were designed to test whether CsA alone or in combination with the ACE-inhibitor cilazapril has any effect on graft atherosclerosis in a rat cardiac transplant model. Cardiac grafts were transplanted heterotopically into either syngeneic or allogeneic recipients and followed by daily palpation; long-surviving grafts were removed after 100 days and the extent and degree of atherosclerosis was assessed using computerized morphometry. Atherosclerosis was more extensive in grafts removed from untreated allogeneic recipients compared with syngeneic recipients; CsA treatment increased the extent of atherosclerosis in syngeneic transplants. The extent and degree of vascular occlusion in allogeneic grafts from recipients treated with 15 mg/kg of CsA every other day was not different from that in grafts removed from recipients that received initially higher CsA doses. Cilazapril had no effect on the extent of graft atherosclerosis but decreased the degree of luminal narrowing in grafts from CsA-treated recipients significantly. Some grafts showed neovascularization in the subendocardial region adjacent to organized intraventricular clots, suggesting the release of angiogenic factors from such clots; such growth factors may contribute to the atherosclerotic vessel wall reaction in this model. We conclude that CsA promotes the development of graft atherosclerosis in heterotopically transplanted syngeneic cardiac grafts in the rat. We furthermore found that cilazapril has a beneficial effect on the degree of atherosclerosis in CsA-treated recipients.

Glomerular capillary pressures in long-surviving rat renal allografts.

Many renal transplants undergo gradual deterioration in structure and function in the months or years after transplantation. The processes that underlie this progressive decline have not been defined, and may include immunological and nonimmunological mechanisms. The present experiments were designed to investigate the glomerular capillary hydrostatic pressure in long-surviving rat renal transplants with or without chronic rejection. Stop-flow glomerular pressures were measured in F344 renal allografts with chronic rejection, syngeneic F344 grafts, and long-surviving syngeneic and allogeneic LEW grafts without chronic rejection; control measurements were done in nontransplanted intact animals or after subtotal renal ablation. Renal ablation or transplantation resulted in increased glomerular pressure in F344 but not LEW kidneys; the glomerular pressure in syngeneic F344 grafts was not different

Peritubular capillary basement membrane reduplication in allografts and native kidney disease: A clinicopathologic study of 278 consecutive renal specimens

Background. An association has been found between transplantglomerulopathy (TG) and reduplication of peritubular capillary basementmembranes (PTCR). Although such an association is of practical and theoreticalimportance, only one prospective study has tried to confirmit. Methods. We examined 278 consecutive renal specimens (from 135transplants and 143 native kidneys) for ultrastructural evidence of PTCR. Inaddition to renal allografts with TG, we also examined grafts with acuterejection, recurrent glomerulonephritis, chronic allograft nephropathy andstable grafts (“protocol biopsies”). Native kidney specimensincluded a wide range of glomerulopathies as well as cases of thromboticmicroangiopathy, malignant hypertension, acute interstitial nephritis, andacute tubularnecrosis. Results. We found PTCR in 14 of 15 cases of TG, in 7 transplantbiopsy specimens without TG, and in 13 of 143 native kidney biopsy specimens.These 13 included cases of malignant hypertension, thrombotic microangiopathy,lupus nephritis, Henoch-Schonlein nephritis, crescentic glomerulonephritis,and cocaine-related acute renal failure. Mild PTCR in allografts without TGdid not predict renal failure or significant proteinuria after follow-upperiods of between 3 months and 1year. Conclusions. We conclude that in transplants, there is a strongassociation between well-developed PTCR and TG, while the significance of mildPTCR and its predictive value in the absence of TG is unclear. PTCR alsooccurs in certain native kidney diseases, though the association is not asstrong as that for TG. We suggest that repeated endothelial injury, includingimmunologic injury, may be the cause of this lesion both in allografts andnativekidneys.

Pathology services in developing countries A challenge

T practice of pathology in the developing world— where the majority of the earth’s population lives— presents special challenges for the Western-trained physician accustomed to the high standard of living, long life expectancy, and predictable disease patterns that are prevalent in the developed world. This health care gap will inevitably widen even further as sophistication of technology in our pathology laboratories increases by leaps and bounds, our ability to fine-tune diagnoses is honed, and as medicine becomes more personalized, while many developing countries struggle to provide even the most basic pathology services. This has inspired many pathologists and health professionals to attempt to bridge the gap. Several important such initiatives exist in the United States and Canada, as well as in many other developed countries. However, the situation on the ground is frequently complex, and such efforts may encounter challenges that cover the spectrum from the educational and cultural, to the economic and political. This may be especially daunting for pathologists who are highly trained to perform specialized and sophisticated analyses on problems that relate to the individual patient, to particular diseases, or to pathobiologic phenomena. Our training prepares us less well to deal with societal issues such as those that face the developing world. These challenges are not unique to pathologists or indeed to physicians. The developed world has long struggled with both the practical and the theoretical aspects of aid, and great efforts have been made in this regard. It is estimated that

FK778, a powerful new immunosuppressant, effectively reduces functional and histologic changes of chronic rejection in rat renal allografts.

2.3 trillion has been spent on various aid