Antibodies directed against alloantigens are implicated in the pathogenesis of several immune reactions complicating transplantation. In particular, this humoral response unfavorably affects the ...outcome of solid organ transplantation, and it has been hypothesized to be responsible for some of the clinical manifestations related to graft-versus-host disease (GVHD). In detail, the presence of antibodies against donor cells is a contraindication to kidney transplantation because of the risk of hyperacute rejection. In the effort to expand the donor pool, trials of allograft transplantation across HLA-sensitization have been conducted by means of strategies including pre-transplant plasmapheresis, intravenous immunoglobulins (Ig), anti-B cell monoclonal antibodies and splenectomy, associated with high-intensity immunosuppressive regimens. These measures have proved only partially successful in preventing humoral rejection in high-risk patients. Thus, the development of new therapeutic tools able to blunt alloantibody production could be a welcomed implementation to existing protocols. Mesenchymal stem cells (MSC) have been demonstrated to possess immunomodulatory capacity, since they induce T-cell hyporesponsiveness in vitro, prolong survival of skin graft in a primate model, and seem to decrease GVHD incidence and severity in humans given hematopoietic stem cell transplantation.
To verify whether MSC may exert an inhibitory effect on antibody production, we stimulated B-cell-enriched peripheral blood mononuclear cells (PBMC) obtained from healthy controls (n=9) or sensitized prospective kidney recipients (n=5) in a mixed lymphocyte culture (MLC) against irradiated HLA-disparate stimulator PBMC (controls) or stimulators cells bearing HLA antigens matched with the positive cross-match (patients). Antibody production in the absence or in the presence of third-party allogeneic MSC (responder:MSC ratio:4:1) was then evaluated by ELISA. We found that the addition of MSC at the beginning of MLC considerably inhibited IgG and IgM production (median fold-decrease of IgG production: controls, 7; patients, 5; median fold-decrease of IgM production: controls, 17; patients, 4). Our preliminary findings indicate that third-party MSC are able to suppress antibody production in vitro, and may therefore help to overcome a positive cross-match in sensitized transplant recipients. These results may also contribute to partly explain the mechanism at the basis of the favourable effect played by MSC in patients with GVHD.
Summary
We report the 1‐year results with a triple immunosuppressive regimen in pediatric recipients of a first kidney transplant, in order to evaluate its safety and efficacy in the prevention of ...acute rejection and in the reduction of steroid side effects. The immunosuppression is as follows: (i) basiliximab (20 mg if body weight >30 kg; 10 mg if <30 kg) is given pretransplant and at day 4; (ii) tacrolimus (Tac) is administered in order to obtain blood trough levels of 10–20 and 5–10 ng/ml during and after the first 2 months post‐transplant, respectively; (iii) steroids are tapered during the first 6 months and then replaced by mycophenolate mofetil (depending on previous rejection episodes, infection status and the result of a routine biopsy) at a dosage of 4–600 mg/m2 body surface area. Fifty‐three children (median age 13 years, range 2–20) have entered this protocol. One‐year patient and kidney survival are 100% and 94% respectively. During the first year a total of nine rejections in seven patients (13% of the cohort study) occurred, all but one responsive to steroids. Renal function was satisfactory throughout the first year (mean CrCl was 63.8 ± 18 and 60.9 ± 15.5 ml/min/1.73 m2 at 6 and 12 months respectively). Subclinical signs of rejection were absent in more than 80% of biopsies (grade I Banff) at 6 months (n = 47); at the 12th month biopsy (n = 42) score I was stable in 20 patients (16 after stopping steroids) and had worsened in eight biopsies (six after stopping steroids). Major complications were insulin‐dependent diabetes in three (5.6%) children with the need of insulin for a mean of 3 months; transient hyperglycemia (11 patients), treated with a dietary regimen, symptomatic viral infections (in 11 patients: two parvovirus B19, three cytomegalovirus and two Epstein–Barr virus systemic infections, three interstitial pneumonia, two BK nephritis). Tac doses more than 0.3–0.4 mg/kg/day are at significantly higher risk of viral infection. In conclusion, this immunosuppressive regimen is associated with a low percentage of clinical (13%) and subclinical rejections, but with a relatively high number of infections, prevented by a reduction in Tac doses (<0.3 mg/kg/day) during the first 2 months after transplantation. The assessment of steroid withdrawal needs a longer follow‐up.
Side effects such as cutaneous vasculitis, which occur during prolonged levamisole treatment, may discourage the utilization of the drug in relapsing nephrotic syndrome. We describe a child who ...developed disseminated vasculitis during prolonged treatment with levamisole. The acute phase was characterized by hepatosplenomegaly, hemolytic anemia, IgM anticardiolipin and p-antineutrophil cytoplasmic antibodies. One month after withdrawal of therapy all symptoms had disappeared and tests normalized. This case report, together with other reports on cutaneous vasculitis, suggest caution and close monitoring during prolonged levamisole therapy.
In this study, we examined the progression of chronic Adriamycin (ADR) nephropathy in mild leukopenic rats and tried to define the possible relationship between tubulointerstitial lesions and ...proteinuria in this model. Chronic ADR nephropathy was induced by 2 doses of ADR (2 mg/kg) in 32 Sprague-Dawley rats. Eight of these were randomly assigned to cyclophosphamide treatment (50 mg/kg), given intravenously every week, to keep the blood leukocyte count constantly lower than 5,000/mm3. Serial parameters were followed for 16 weeks including clearance studies with iothalamate and p-aminohippurate and the analysis of urinary protein composition by: (a) an enzymatic assay for beta-glucosidase; (b) specific ELISA using antibodies against rat albumin and RBP, and finally (c) two-dimensional electrophoresis. ADR-treated rats rapidly (within 2 weeks) developed massive proteinuria which was in constant increment throughout the disease evolution in each single component (i.e., high and low molecular weight proteinuria, enzymuria) and developed renal insufficiency. At week 8, in ADR rats, glomerulosclerosis was mild whereas tubulointerstitial infiltrates predominated, characterized mainly by CD4+ T lymphocytes while CD8+ T lymphocytes were inconspicuous, and macrophages were only occasionally present. All such alterations had worsened after 16 weeks when the tubulointerstitial infiltration was associated with marked interstitial fibrosis and tubular atrophy. Leukopenia induced by cyclophosphamide was in all cases associated with a net amelioration of renal histopathology reducing tubulointerstitial infiltrates (by 40%) and glomerulosclerosis (33 +/- 5 vs. 52.2 +/- 7.5% sclerotic glomeruli) and also ameliorated glomerular filtration indexes (Cl 780 +/- 40 vs. 447 +/- 66 microliters/min/kg-1). In spite of these differences, albuminuria and urinary-retinol-binding protein were comparable at weeks 4, 8 and 16 in this group, while urinary beta-glucosidase was decreased at week 16 (p < 0.001) in cyclophosphamide-treated rats. No other qualitative changes in urinary proteins were detectable by 2-dimensional electrophoresis during the disease development. We concluded that chronic leukopenia prevents interstitial cellular infiltration by lymphocytes, interstitial fibrosis and slows down the decline of renal function typical of chronic ADR nephropathy. Glomerulosclerosis is also reduced in leukopenic rats without any appreciable changes in the urinary excretion of high molecular weight proteins deriving from the glomerulus. Finally, the improvement in tubulointerstitial alteration is associated with the reduction in urinary lysosomal enzymes. Tubulointerstitial alterations are implicated with a prominent role in the progression towards renal failure in chronic ADR glomerulopathy.
: Although both immunologic and non‐immunologic components may cause kidney allograft chronic rejection (KGCR), also referred to as chronic allograft nephropathy (CAN), its pathogenesis is largely ...not yet understood. To explore relevant immunologic mechanisms occurring in KGCR, we have analyzed in surgically removed KG the transcription of the following cytokine and apoptotic molecule genes: interleukin (IL)‐2, IL‐3, IL‐4, IL‐5, IL‐6, IL‐10, tumor necrosis factor (TNF)‐α, IFN‐γ, FAS, and FAS‐L. Semiquantitative RT‐PCR was used and KG explants were obtained from two groups of transplanted patients. Group 1 was represented by CR/CAN KG, removed for: (a) superimposed symptoms of acute lesions (SAL) due to tapering or suspension of immunosuppression (subgroup 1a, eight cases); (b) causes other than SAL (two cases, subgroup 1b). Group 2 comprised explanted kidneys with no CR/CAN (three cases – vascular thrombosis, intrarenal hemorrhage and vascular thrombosis). The results showed that in group 1 IL‐ 6 was detectable in seven of 10, IL‐10 in six of 10, IFN‐γ in five of 10, and IL‐3 in four of 10 cases with a variable pattern of reciprocal association. IL‐2 and TNF‐α were represented in one of 10 cases only. Particularly, in the subgroup 1b IL‐10 was never detected. Among the most represented cytokines of group 1, IL‐10 as well as IL‐3 were never found in group 2. The peculiar expression of IL‐10 and IL‐3 and partially IL‐6 seems to support the hypothesis that a Th2 pattern predominantly characterizes KGCR, thus indicating that Th2 cytokines, likely produced by different intragraft cell types including T cells, macrophages and natural killer (NK) cells, may represent an important component in the pathogenesis of this process. Moreover, IL‐10 seems to exquisitely characterize a group of CR/CAN kidney grafts more prone to immunologic assaults.
It has been suggested that the generation of toxic radicals plays an important role in toxicity by Adriamycin (ADR) on cancer cell lines and in vivo. We have examined the role of free radicals in ...determining toxicity and resistance to ADR of rat glomerular epithelial cells in culture; this method provides a good model for analyzing the mechanisms responsible for ADR experimental nephrosis in rats. Three points were established: a) the intra- or extracellular site of ADR toxicity; b) the role of the superoxide anion and of the hydroxyl radical in determining intra- and-extracellular cytotoxicity; and c) the implication of oxido-reduction cycling as a potential route for ADR semiquinone transformation. Free ADR was found to induce the same inhibition of 3Hthymidine incorporation into DNA as ADR bound to an agarose macroporous bed which prevents the intracellular incorporation of the drug. Specific scavenging of free radical activity by the enzymes catalase and Superoxide dismutase, the hydroxyl radical inhibitors dimethyl sulfoxide and dimethylthiourea (DMTU) and by chelation of intracellular free iron with deferoxamine produced only a partial restoration of 3Hthymidine incorporation into DNA, which was maximal for DMTU (30% of normal incorporation). DMTU treatment was unsuccessful in preventing the extracellular cytostatic effect of ADR. Finally, glomerular epithelial cell killing ($^{51}Cr-release$method) by 5-iminodaunorubicin, an ADR analogue with a modified quinone function that prohibits oxido-reduction cycling, was higher than unmodified ADR. These results indicate that ADR may exert its cytotoxic effects on glomerular epithelial cells by interaction at the cell surface, whereas the intracellular compartment, principally DNA, does not seem to be the target of ADR effects. They also suggest that the free radicals are in part responsible for ADR intracellular cytotoxicity, but other mechanisms should also be hypothesized. Finally, the participation of the ADR semiquinone radical in oxido-reduction cycling seems not important for the induction of the cellular damage.
: The putative mechanisms of proteinuria in idiopathic focal glomerulosclerosis and of its post‐transplant recurrence are discussed. It is proposed that a balance between circulating factors with ...permeability activity on glomeruli and putative inhibitors play a key role. The characterization of inductors is currently in progress; most inhibitors appear to be apolipoproteins (mainly apoJ and apo E) but we cannot exclude other substances. The goal is now to evaluate the concentration of both inducers and inhibitors of glomerular permeability in vivo. Permeability activity in plasma of patients with FSGS with and without recurrence of the disease may be evaluated by an in vitro functional essay with isolated glomeruli. Published data on permeability activity evaluated with this method in different proteinuric states gave, however, controversial results and this test cannot be readily considered of clear clinical utility.
Only the definitive characterization and quantification in vivo of the different molecules that play a role in FSGS may furnish adequate answer.
Autosomal recessive nephronophthisis (NPH) is a renal disorder histologically characterized by tubulointerstitial lesions that are, in some cases, associated with extrarenal manifestations such as ...tapeto-retinal degeneration or liver fibrosis. The disease is usually pauci-symptomatic in an early phase but invariably evolves to end-stage renal failure in childhood or early adulthood. The recent discovery of the
NPHP1 gene (nephrocystin) has prompted research into putative genotype-phenotype correlations. We screened a population of 68 Italian children (10 multiplex families, 47 sporadic cases) with a clinical and histopathologic picture of NPH and found a large homozygous deletion at 2q13 involving nephrocystin in 30 cases, and heterozygous deletion associated with new point mutations at exons 15 (Tyr518Ter) and 17 (Arg585Ter) of the gene in two other cases. The remaining 36 children had no apparent molecular defects of nephrocystin. In spite of this genetic heterogeneity, the two groups, with and without detectable molecular defects of nephrocystin, showed similar renal defects and comparable cumulative survival considering the start of dialysis as an end-point. The unique difference observed was a less frequent requirement of dialysis in NPH1 patients with pure renal form. Finally, tapeto-retinal degeneration was associated with renal lesions in seven cases presenting deletion of the nephrocystin gene and in five sporadic cases without molecular defects. These data show that a molecular defect of nephrocystin is involved in approximately 50% of patients with NPH, and another 50% require further molecular characterization. Research therefore should now be aimed at characterizing a new locus. In spite of the molecular heterogeneity, NPH in children presents similar renal and extrarenal manifestations, thus suggesting the involvement of common pathological routes.
PDF
