Antibodies to dietary antigens in IgA nephropathy

It has been postulated that IgA NP is caused by mesangial deposition of IgA-containing immune complexes formed by IgA polymers (pIgA) which are overproduced in response to antigens presented at mucosal surfaces. The intestinal mucosa is one possible source of this pIgA. To test whether antibodies to dietary antigens might be involved in the pathogenesis of IgA NP, we measured IgG and IgA serum antibody activities to gluten, a gluten fraction called glyc-gli, alpha-lactalbumin, beta-lactoglobulin, casein and ovalbumin in 54 patients with IgA NP by an enzyme-linked immunosorbent assay (ELISA). The IgA activities to gluten antigens and alpha-lactalbumin were significantly increased in IgA NP compared with a group of 40 age-matched healthy controls. In a previous study we found that 4 out of 12 patients with IgA NP and gastrointestinal complaints had subtotal villous atrophy; this indicated that many patients with IgA NP have altered intestinal permeability which may lead to activation of their intestinal immune system. Taken together our results showed a relation between the intestinal humoral immune system and IgA NP and indicated that antibodies to dietary antigens in some patients may be directly involved in the pathogenesis of IgA NP.     

Treatment of symptomatic transplant glomerulopathy with rituximab

Kidney transplant glomerulopathy (TG) has a poor outcome as there are no known effective therapies. Therefore, we investigated whether rituximab therapy (RTx) could halt progression of established TG. Fourteen kidney-transplant patients (nine of whom were men), with median age of 54 (range: 30–74) years, of whom seven had biologic markers for HCV infection, underwent a kidney biopsy (KB) at 118 months post-transplant because of impaired allograft function, associated with albuminuria (95–13430 mg/day), within nephrotic-range albuminuria in seven patients. KBs showed no evidence of acute cellular rejection but showed TG. Donor-specific anti-HLA antibodies were present in six cases. When diagnosis of TG was made, patients were placed on rituximab therapy (RTx) (2–4 injections of 375 mg/m² week), and other concurrent immunosuppression treatments were not modified. By last follow up post-RTx (30 months), seven (50%) patients had lost their kidney within 6–26 months and the other seven had stable creatinine (182 vs. 161 μmol/l; NS), and albuminuria had decreased from 2660 to 500 mg/day ( P  = 0.03). There was prolonged B-cell lymphopenia (from 71 to 0/mm³) whereas immunoglobulin G, A, M levels remained stable, and four patients (28.5%) experienced severe infectious complications. We conclude that long-term RTx in kidney-transplant patients with TG is associated with allograft function/stabilization in 50% of cases.     

Impact of HLA antibodies on transplant glomerulopathy

The influence of humoral rejection on the development of chronic allograft nephropathy (CAN) is controversial, especially in relation to transplant glomerulopathy. The aim of our study was to analyse the influence of anti-HLA antibodies on the development of transplant glomerulopathy (cg0, cg1, cg2, and cg3; Banff'97). We selected all renal transplants patients from 1975 to 2003 who had a functioning graft for at least 6 months and a clinically indicated graft biopsy with CAN and chronic glomerular changes (case group). We studied the presence of anti-HLA antibodies (Ab) in the last serum taken while the graft was functioning and divided them into three groups according to the severity of glomerular lesions. We also selected 52 contemporary and comparable cases without transplant glomerulopathy (control group). A total of 77 case had transplant glomerulopathy: 39 cg1, 29 cg2, and 9 cg3. Pretransplant Ab titers and number of previous blood transfusions were higher among the subgroup with the most severe glomerulopathy. Patients who developed posttransplant anti-HLA Ab more frequently showed transplant glomerulopathy. Serum creatinine and proteinuria were higher among cases with chronic glomerulopathy, and more grafts were lost in that group. Thus, the presence of HLA-Ab is a key factor in the development of transplant glomerulopathy and chronic allograft rejection.     

An analysis of transplant glomerulopathy and thrombotic microangiopathy in kidney transplant biopsies

Glomerular diseases of the transplanted kidney are the most important cause of poor long‐ term outcome. The estimation of the magnitude of this problem and an elucidation of pathogenic mechanism is essential for improvement of graft survival. This study from the Indian subcontinent aims (i) to determine the incidence of transplant glomerulopathy (TG) and thrombotic microangiopathy (TMA) in a large cohort of indicated renal transplant biopsies, (ii) to evaluate the histological and ultrastructural features of TG and TMA, and (iii) to assess the relationship between the two glomerular lesions. Of a total of 1792 indication renal transplant biopsies received over 5 years (2006–2010), 266 biopsies (of 249 patients) had significant glomerular pathology and were further analyzed along with immunofluorescence, electron microscopy (EM), and C4d immunohistochemistry. TG is the most common glomerular lesion followed by TMA seen in 5.97% and 5.08% of allograft biopsies, respectively, which constitutes 40.23% and 34.2% of biopsies with significant glomerular lesions. Pathologic antibody‐mediated rejection (AMR) is associated with both TG and TMA in 71% and 46.5%, respectively. A coexistent TG was found in 18.4% of biopsies with TMA. Endothelial swelling with subendothelial widening, a feature of TMA, is also seen in early TG by EM. Our findings support the concept that TG evolves from a smoldering TMA of various causes.     

Acute transplant glomerulopathy with monocyte rich infiltrate

Acute transplant glomerulopathy refers to alloimmune mediated endothelial injury and glomerular inflammation that typically occurs early post-kidney transplantation. We report a case of a 48-year old woman with end stage renal disease from lupus nephritis who developed an unexplained rise in serum creatinine 2 months after renal transplant. As immunosuppression, she received alemtuzumab induction followed by a tacrolimus, mycophenolate mofetil and prednisone maintenance regimen. Her biopsy revealed severe glomerular endothelial injury associated with monocyte/macrophage-rich infiltrate in addition to mild acute tubulointerstitial cellular rejection. We briefly discuss acute transplant glomerulitis, its pathology and association with chronic/overt transplant glomerulopathy, C4d negative antibody-mediated rejection and the significance of monocytes in rejection. We also postulate that alemtuzumab induction may have contributed to the unusual pattern of monocyte-rich transplant glomerulitis.     

Detection of alloantibodies against non-HLA antigens in kidney transplantation by flow cytometry

The presence of alloantibodies against human leucocyte antigen (HLA)-I and HLA-II antigens has been associated with hyperacute and accelerated graft rejections. However, occasionally these rejections occur in patients without donor-specific anti-HLA antibodies, suggesting the presence of other antigenic complexes that are shared by the graft and other cell populations. Usually, these antibodies are not routinely studied and their role in graft rejection is poorly understood. For this reason, we tested, by flow cytometry, the presence of panel-reactive alloantibodies (PRA) using different cell populations in 30 pre-transplant sera of kidney graft recipients. The patients studied had or had not hyperacute and accelerated rejection episodes (HARE) and did not have alloantibodies against HLA of their specific donors. We found that IgG and IgM alloantibodies directed against HLA-I antigens, different to the HLA-I antigens of the specific donors, as well as IgG against endothelium/monocyte antigens, IgM against platelets, and IgM against T cells are significantly associated with HARE, independently of the percentage of PRA. Our findings suggest that the detection of antibodies by flow cytometry against non-major histocompatibilty complex antigens may be useful as a pre-transplant crossmatch in living related donor kidney transplants to diminish the incidence of HARE.     

The clinical impact of chronic transplant glomerulopathy in cyclosporine era

BACKGROUND: The clinical impact of chronic transplant glomerulopathy (CTG) on the outcome of kidney allograft receiving calcineurin inhibitors (CNIs) remains uncertain. A retrospective study of renal transplant recipients at Ospedale Maggiore of Milan was undertaken to evaluate the clinical outcome of patients with CTG. METHODS: Among 666 biopsies taken at least 6 months after transplantation (Tx) in 498 transplant patients treated with CNIs, 28 cases (5.6%) of chronic transplant glomerulopathy (CTG) were identified and their clinical features at Tx, at follow-up and graft survival were compared with those of 56 controls transplanted in the same period and with kidney functioning 12 months after Tx. Clinical characteristics at biopsy and at 1 year after Tx were similar in the two groups. RESULTS: After diagnosis graft function deteriorated in 22 patients (78.5%), while it remained stable in 6. Graft loss developed in 92 % of patients with proteinuria >2.5 g/day and in 33 % of those with lower proteinuria (P<0.005). In cases with more severe CTG the rate of graft loss was higher, though not significantly. Graft survival at 10 years was 48% in patients with CTG and 88% in controls (P<0.0001). CONCLUSIONS: The incidence and clinical course of CTG do not seem to be modified by CNI-based immunosuppression. The evolution is unpredictable but the severity of glomerulopathy and proteinuria at follow-up are associated with progression to graft failure. Patients with CTG have a graft survival significantly worse than that of the general population of transplanted patients.     

Cytomegalovirus infection complicating renal transplantation and its relationship to acute transplant glomerulopathy

The incidence of cytomegalovirus (CMV) infection was established, using laboratory criteria, in 298 patients receiving 362 renal allografts (164/298 = 55%). The incidence of CMV infection did not differ between azathioprine/prednisolone-treated and cyclosporine-treated patients (55% vs. 57% NS). The use of antithymocyte globulin (ATG) increased the incidence of CMV infection (78% vs. 51%: P less than 0.01). Donor and recipient CMV status, known for 116 allografts, did not correlate with the incidence of CMV infection (recipient CMV-positive = 50%; recipient CMV-negative = 54%: NS). CMV infection was responsible for 8 patients' deaths (2.7% mortality). Thirty-three patients with acute transplant glomerulopathy were identified (11%). There was no correlation between acute transplant glomerulopathy and CMV infection. Glomerulopathy was associated with poor graft survival (22/33 patients with a graft survival of less than 6 months). Thus CMV infection, although a common complication of renal transplantation with significant morbidity and mortality, is not closely associated with acute transplant glomerulopathy. Further, the lack of correlation of donor-recipient CMV serologic status with graft outcome limits the usefulness of pretransplantation donor screening.     

Recurrence from primary and secondary glomerulopathy after renal transplant

Glomerulonephritis is the primary cause of end-stage renal failure in 30-50% of kidney transplant recipients and recurrence of the initial disease is an important determinant of long-term graft outcome after transplantation. Although renal transplantation remains the best treatment option for patients with end stage renal diseases in most cases, diagnosis and management of recurrences of glomerulopathies are critical for the optimization and improvement of long-term kidney transplant graft survival and provide a unique opportunity to explore the pathogenesis of native kidney disease. This review aims to update knowledge for a large panel of recurrent primary and secondary glomerulonephritis after kidney transplantation, excluding diabetic nephropathy including primary focal and segmental glomerulosclerosis, membranous nephropathy, IgA nephropathy, membranoproliferative glomerulonephritis, lupus, vasculitis but also less usual secondary nephropathy related to sarcoidosis, AA and AL amyloidosis, monoclonal immunoglobulin deposition disease, and fibrillary glomerulonephritis.     

Collagenofibrotic glomerulopathy in a kidney transplant recipient: A first report

Collagenofibrotic glomerulopathy (CG) is a rare disease characterized by the deposition of collagen type 3 fibrils in the glomeruli. Patients may have proteinuria, hematuria, and/or renal dysfunction. CG is considered a progressive disease with variable rates of progression. The definitive diagnosis is made by electron microscopy with the presence of characteristic subendothelial and mesangial curved, comma-like, banded collagen type 3 fibers of 40–65 nm periodicity. We are reporting the first case of CG in a kidney transplant recipient with kidney disease of unknown cause.     

Detection of non-HLA antigens: effect of lymphocyte priming and amplification signals.

We studied three potential mechanisms that might account for the difficulty in detecting non-HLA antigenic disparities between HLA-identical siblings: (1) a low frequency of antigen-reactive cells; (2) the failure of antigen recognition to trigger proliferation or cytotoxicity; and (3) the development of suppressor cells or factors. In vitro sensitization was used to increase the frequency of antigen-reactive cells. Allogeneic lymphocytes or supernatants from mixed lymphocyte cultures were used to provide nonspecific proliferative signals. Neither approach was successful in facilitating the detection of proliferation or cytotoxicity between HLA-identical siblings. Furthermore, we found no evidence for the development of antigen-specific suppressor cells or factors. These data indicate that other mechanisms must underlie the difficulty in detecting non-HLA antigens in vitro.