Ginette Lajoie

Outcome of kidney transplantation from high-risk donors is determined by both structure and function.

METHOD Despite the need to expand the donor pool, it is unclear what parameters should be used. The value of donor renal pathology and calculated creatinine clearance (CrCl) in determining recipient outcome was assessed in 57 kidney transplants from 34 donors in whom pretransplant renal biopsies were performed because of age > or =60, hypertension, and/or vascular disease. We retrospectively compared clinical outcomes in these recipients and 57 control recipients selected to have the same baseline demographics but receiving transplants from low risk donors who were significantly younger (32+/-13.9 vs. 61+/-7.3 years) and lighter weight (71+/-18.1 vs. 84+/-20.2 kg) than the high-risk donors (P<.001 for both). RESULTS Recipients of high-risk kidneys had a higher incidence of delayed graft function, defined by a <10% fall in serum creatinine (Cr) in the first 24 hr, (56% vs. 30%, P<.01), a higher incidence of rejection (60% vs. 37%, P = .02) and a higher Cr level (197+/-64 vs. 144+/-54 micromol/L at 18 months, P<.005). Graft and patient survival were similar; 12% and 5% vs. 91% and 9% in high-risk vs. control groups, respectively (P = NS). Donor renal pathology was scored 0-3 (none to severe disease) in four areas: glomerulosclerosis, interstitial fibrosis, tubular atrophy, and vascular disease. A donor vessel score of 3/3 was associated with a 100% incidence of delayed graft function and a mean 1-year Cr level of 275+106 micromol/L (compared with 43% and 192+54 micromol/L in those with lower vessel scores, P<.05). Calculated donor CrCl <100 ml/min was associated with higher recipient Cr levels at 1 year, 240+/-95 micromol/L vs. 180+/-54 micromol/L in recipients of kidneys from donors with CrCl levels >100 ml/min (P<.05). The mean 1-year Cr level was 320+/-102 micromol/L in recipients with both a vascular score of 3/3 and a donor CrCl <100 ml/min and 184+/-63 micromol/L in those with neither factor (P = .001). CONCLUSION Calculated donor CrCl and donor vascular pathology predict recipient graft function and may be helpful in selecting high-risk donors for single kidney transplantation.

Colocalization of Expansion of the Splenic Marginal Zone Population with Abnormal B Cell Activation and Autoantibody Production in B6 Mice with an Introgressed New Zealand Black Chromosome 13 Interval

Polyclonal B cell activation is a prominent feature of the lupus-prone New Zealand Black (NZB) mouse strain. We have previously demonstrated linkage between a region on NZB chromosome 13 and increased costimulatory molecule expression on B cells. In this study we have produced C57BL/6 congenic mice with an introgressed homozygous NZB interval extending from ∼24 to 73 cM on chromosome 13 (denoted B6.NZBc13). We show that B6.NZBc13 female mice not only have enhanced B cell activation but also share many other B cell phenotypic characteristics with NZB mice, including expansion of marginal zone and CD5+ B cell populations, increased numbers of IgM ELISPOTs, and increased serum levels of total IgM and IgM autoantibodies. In addition these mice have increased T cell activation, increased numbers of germinal centers, mild glomerulonephritis, and produce high-titer IgM and IgG anti-chromatin Abs. Male B6.NZBc13 mice have a less pronounced cellular phenotype, lacking expansion of the marginal zone B cell population and IgG anti-chromatin Ab production, indicating the presence of gender dimorphism for this locus. Thus, we have identified a genetic locus that recapitulates with fidelity the B cell phenotypic abnormalities in NZB mice, and we demonstrate that this locus is sufficient to induce an autoimmune phenotype. The data provide further support to the contention that immune abnormalities leading to altered B cell activation and selection contribute to the development of autoimmunity in NZB mice.

Angiomyolipoma: Immunohistochemical and Ultrastructural Study of 14 Cases

Angiomyolipoma (AML) is a mesenchymal neoplasm of unclear histogenesis. In addition to varying amounts of smooth muscle, adipose tissue, and blood vessels, it contains a population of clear or pale eosinophilic epithelioid cells often arranged around blood vessels. Various phenotypes of AML have been described: leiomyoma-like, lipoma-like, epithelioid, and atypical. AMLs show consistent immunopositivity for HMB-45. This has been associated with the ultrastructural observation of melanosome-like structures in rare instances. In the present study, 14 AMLs from 13 patients were analyzed by electron microscopy and immunohistochemistry to determine the appearance and nature of cells composing AMLs. Overlap between cell types (spindle smooth muscle cells, epithelioid cells, and adipocytes) was found by both electron microscopy and immunohistochemistry. Melanosomes were found in 7 tumors. The cell of origin remains mysterious. Nevertheless, the study demonstrates that the AML is likely derived from a single cell that shares homology with the pericyte.

Polyomavirus Infection and Acute Vascular Rejection in a Kidney Allograft: Coincidence or Mimicry?

During the past decade, polyoma virus (PV) infection has emerged as an important cause of graft dysfunction and failure in kidney transplant recipients. Establishing the correct diagnosis can be difficult, however, because the histologic appearance of PV infection can resemble acute cellular rejection. We report a kidney‐pancreas transplant recipient with PV infection, in whom both vascular and cellular rejection were dominant histologic features in a renal biopsy specimen. The patient was successfully managed by tapering immunosuppressive therapy, and continues to have good graft function 3 years after diagnosis of PV infection. This case highlights the spectrum of inflammatory changes associated with PV infection, and the need for caution when such changes are attributed to rejection.

Improvement in rejection of human decay accelerating factor transgenic pig-to-primate renal xenografts with administration of rabbit antithymocyte serum.

Background. Survival in pig-to-baboon kidney xenotransplantation is currently limited by acute humoral xenograft rejection (AHXR). We hypothesized that the administration of rabbit antithymocyte serum (RATS) would delay or prevent AHXR as compared with a cyclophosphamide (CyP)-based immunosuppressive regimen. Methods. Nine baboons received life-supporting heterotopic single-kidney transplants from human decay accelerating factor transgenic pigs. Immunosuppression consisted of GAS (a galactosyl &agr;-1,3-galactose analog), cyclosporine, and steroids. Group 1 (n=2) was also treated with CyP and a rapamycin derivative (RAD), group 2 (n=4) received RATS and RAD, and group 3 (n=3) received only RATS. Animals were maintained until death or sacrifice because of uncontrollable rejection or other complications. Graft histopathology was assessed at the study endpoint. Results. Mean survival was 28±11.3 days, 23±2.5 days, and 20±2.5 days for groups 1, 2, and 3 (not significant). Graft rejection was the cause of death in both CyP-treated animals. One RATS-treated animal died of rejection; the others died of infections or bleeding. Two RATS-treated animals developed posttransplant lymphoproliferative disorder, and one died of cytomegalovirus pneumonitis. Histopathology revealed severe AHXR in group 1 kidneys, involving 100±0% of the tissue examined. In contrast, AHXR was reduced in groups 2 and 3, involving 21±14% and 18±28%, respectively, of the tissue examined (P <0.01). Conclusions. Substitution of RATS for CyP was well tolerated and resulted in reduced severity of AHXR in this model. Complications seen in RATS-treated animals may be preventable through the use of standard prophylaxis for infections. Our data suggest that further studies are warranted to explore the use of antilymphocyte agents in xenotransplantation.

Clinical, Biochemical, and Pathological Features in a Patient with Plasma Cell Dyscrasia and Fanconi Syndrome

Multiple myeloma is associated with a wide array of renal diseases that include myeloma cast nephropathy, monoclonal immunoglobulin deposition disease, amyloidosis, cryoglobulinemia, tubular dysfunction, pyelonephritis, nephrocalcinosis, urate nephropathy, and infiltration by atypical plasma cells (or myeloma cells). Filtered immunoglobulin light chains may affect both the distal and, more frequently, the proximal tubule. Tubular abnormalities in patients with plasma cell dyscrasia may be more frequent than previously thought. A patient with a plasma cell dyscrasia is described, who presented with biochemical features consistent with Fanconi syndrome. Immunoelectron microscopy performed on the renal biopsy confirmed the presence of kappa light chain immunoglobulin in intracytoplasmic crystals in proximal tubular epithelial cells. This report is one of a few demonstrating the presence of light-chain immunoglobulin in intratubular crystals in a human renal biopsy obtained from a patient with a plasma cell dyscrasia and Fanconi syndrome.

Abrogation of pathogenic IgG autoantibody production in CD40L gene-deleted lupus-prone New Zealand Black mice.

New Zealand Black (NZB) mice spontaneously develop a lupus-like autoimmune disease. Since CD40-CD40L interactions are important for B cell class-switch recombination and germinal center formation, we sought to understand the impact of these interactions on the immune abnormalities in NZB CD40L gene-deleted (CD40L(-/-)) mice in vivo. NZB.CD40L(-/-) mice demonstrated abrogation of all IgG autoantibodies tested and attenuated kidney disease. However, polyclonal B cell activation in vivo and B cell proliferation and class-switching in response to TLR ligands in vitro were preserved in the absence of CD40L in NZB mice. Although, plasmacytoid dendritic cell expansion and elevated BAFF production were unaffected by the absence of CD40L, there was some evidence that IFN-α-induced gene expression was reduced in the bone marrow of NZB.CD40L(-/-) mice. Our results suggest that CD40-CD40L interactions play an important role in promoting pathogenic IgG autoantibody production and kidney disease in NZB mice.

Dissociation of the Genetic Loci Leading to B1a and NKT Cell Expansions from Autoantibody Production and Renal Disease in B6 Mice with an Introgressed New Zealand Black Chromosome 4 Interval

Previous mapping studies have linked New Zealand Black (NZB) chromosome 4 to several lupus traits, including autoantibody production, splenomegaly, and glomerulonephritis. To confirm the presence of these traits, our laboratory introgressed homozygous NZB chromosome 4 intervals extending from either 114 to 149 Mb or 32 to 149 Mb onto the lupus-resistant C57BL/6 background (denoted B6.NZBc4S and B6.NZBc4L, respectively). Characterization of aged cohorts revealed that B6.NZBc4L mice exhibited a striking increase in splenic B1a and NKT cells in the absence of high titer autoantibody production and significant renal disease. Tissue-specific expansion of these subsets was also seen in the peritoneum and liver for B1a cells and in the bone marrow for NKT cells. Staining with CD1d tetramers loaded with an α-galactosylceramide analog (PBS57) demonstrated that the expanded NKT cell population was mainly CD1d-dependent NKT cells. The lack of both cellular phenotypes in B6.NZBc4S mice demonstrates that the genetic polymorphism(s) that result in these phenotypes are on the proximal region of NZB chromosome 4. This study confirms the presence of a locus that promotes the expansion of B1a cells and newly identifies a region that promotes CD1d-restricted NKT cell expansion on NZB chromosome 4. Taken together, the data indicate that neither an expansion of B1a cells and/nor NKT cells is sufficient to promote autoantibody production and ultimately, renal disease.

Epistatic Suppression of Fatal Autoimmunity in New Zealand Black Bicongenic Mice

Numerous mapping studies have implicated genetic intervals from lupus-prone New Zealand Black (NZB) chromosomes 1 and 4 as contributing to lupus pathogenesis. By introgressing NZB chromosomal intervals onto a non–lupus-prone B6 background, we determined that: NZB chromosome 1 congenic mice (denoted B6.NZBc1) developed fatal autoimmune-mediated kidney disease, and NZB chromosome 4 congenic mice (denoted B6.NZBc4) exhibited a marked expansion of B1a and NKT cells in the surprising absence of autoimmunity. In this study, we sought to examine whether epistatic interactions between these two loci would affect lupus autoimmunity by generating bicongenic mice that carry both NZB chromosomal intervals. Compared with B6.NZBc1 mice, bicongenic mice demonstrated significantly decreased mortality, kidney disease, Th1-biased IgG autoantibody isotypes, and differentiation of IFN-γ–producing T cells. Furthermore, a subset of bicongenic mice exhibited a paucity of CD21+CD1d+ B cells and an altered NKT cell activation profile that correlated with greater disease inhibition. Thus, NZBc4 contains suppressive epistatic modifiers that appear to inhibit the development of fatal NZBc1 autoimmunity by promoting a shift away from a proinflammatory cytokine profile, which in some mice may involve NKT cells.

Suppression of autoimmunity by CD5 + IL-10-producing B cells in lupus-prone mice

Systemic lupus erythematosus is a complex autoimmune disorder characterized by the production of pathogenic anti-nuclear antibodies. Previous work from our laboratory has shown that the introgression of a New Zealand Black-derived chromosome 4 interval onto a lupus-prone background suppresses the disease. Interestingly, the same genetic interval promoted the expansion of both Natural Killer T- and CD5+ B cells in suppressed mice. In this study, we show that ablation of NKT cells with a CD1d knockout had no impact on either the suppression of lupus or the expansion of CD5+ B cells. On the other hand, suppressed mice had an expanded population of IL-10-producing B cells that predominantly localized to the CD5+CD1dlow compartment. The expansion of CD5+ B cells negatively correlated with the frequency of pro-inflammatory IL-17 A-producing T-cells and kidney damage. Adoptive transfer with a single injection of total B cells with an enriched CD5+ compartment reduced the frequency of memory/activated, IFNγ-producing, and IL-17 A-producing CD4 T-cells but did not significantly reduce autoantibody levels. Taken together, these data suggest that the expansion of CD5+ IL-10-producing B cells and not NKT cells protects against lupus in these mice, by limiting the expansion of pro-inflammatory IL-17 A- and IFNγ-producing CD4 T-cells.