Proximal tubular angiotensinogen in renal biopsy suggests nondipper BP rhythm accompanied by enhanced tubular sodium reabsorption.

OBJECTIVES: The renal capacity for sodium excretion is impaired by a reduction in the glomerular ultrafiltration coefficient and by enhancement of the fractional tubular sodium reabsorption (FRNa), leading to a nondipper circadian blood pressure (BP) rhythm. Angiotensin II in the systemic circulation can be easily filtered across the glomerular capillary walls and stimulates renal proximal tubular angiotensinogen (PT-AGT) production, leading to the activation of intrarenal angiotensin II, which is known to augment the FRNa in animal models. METHODS: We performed an immunohistochemical investigation to determine the contribution of PT-AGT to enhancement of FRNa and the nondipper circadian BP rhythm in 40 consecutive patients with primary IgA nephropathy (IgAN). RESULTS: Immunostaining for PT-AGT was increased in the IgAN patients compared with control individuals (P = 0.04), and correlated directly with the FRNa (r = 0.39, P = 0.01) and the night/day ratio of BP (r = 0.38, P = 0.02), but not creatinine clearance (r = -0.008, P = 0.9). The night/day ratio of BP was determined by both creatinine clearance (r = -0.36, P = 0.03) and FRNa (r = 0.47, P = 0.006). CONCLUSION: Tubular sodium reabsorption is stimulated by intrarenal angiotensin II, as indicated by PT-AGT, and contributes to the genesis of the nondipper BP rhythm. Further studies are needed to evaluate whether or not treatment to prevent sodium retention is useful for patients who exhibit increased PT-AGT in renal biopsies.

A case report of recurrence of mixed cryoglobulinemic glomerulonephritis in a renal transplant recipient.

Recurrence of glomerulonephritis (GN) is one of the major risk factors of long-surviving renal graft dysfunction. Cryoglobulinemic glomerulonephritis of hepatitis-C virus (HCV)-negative patient is a rare cause of end-stage renal disease. There is little case report of recurrent cryoglobulinemic glomerulonephritis in negative HCV recipients after renal transplantation. We represent a renal allograft recipient of an interesting recurrent cryoglobulinemic glomerulonephritis. The patient was diagnosed with mixed cryoglobulinemic glomerulonephritis by kidney biopsy at the age of 32 . He had no HCV, HBV nor liver dysfunction. He received immunosuppressive therapy, however, was introduced to hemodialysis treatment after 13 yr. He received a cadaveric renal transplantation at the age of 50, and immunosuppressive treatment was started with ciclosporin, prednisolone and mycophenolate mofetil (MMF). Four yr after transplantation, he developed fever and purpura of lower limbs. His serum creatinine level did not increase, however, proteinuria, hematuria, hypocomplementemia, positive rheumatoid factor and mixed cryoglobulinemia were noted. Detailed analysis failed to reveal the composition of mixed cryoglobulinemia. The renal allograft biopsy showed membranoproliferative-type GN with monocyte and polynuclear leukocyte accumulation of capillary loops and small cellular crescent. Immunofluorescent study showed C3, IgG and IgM deposition of mesangial and capillary pattern. Regardless of steroid pulse therapy, hypocomplementemia and positive rheumatoid factor did not improve. Ten yr after transplantation, he was affected by cellulitis and sepsis. Afterward, rising of serum creatinine and nephrotic range proteinuria developed. The allograft biopsy revealed advanced cryoglobulinemic glomerulonephritis with characteristic vascular lesions. Electron microscopy showed organized subendothelial deposits compatible with cryoglobulinemic glomerulonephritis and proteinaceous thrombus in arteriole.

A case of acute rejection with adenovirus infection after ABO-incompatible kidney transplantation.

We report clinical and histopathologic findings of a case of acute rejection with adenovirus infection after kidney transplantation. A 63-yr-old woman with end-stage renal disease caused by lupus nephritis received an ABO-incompatible living kidney transplantation from her husband. On the 7th post-operative day (POD), she had fever, hematuria, and bladder irritation. Although she was treated with an antibiotic, the symptoms were not improved. We diagnosed adenovirus infection as positive with the urine shell vial method and blood PCR analysis. Cyclophosphamide was interrupted and immunoglobulin therapy was performed. However, urine output decreased and serum creatinine levels increased. An episode biopsy was performed on POD 20. We diagnosed acute antibody-mediated rejection. She was treated with plasma exchange for acute rejection and antiviral drug (rivabirin) for active adenovirus infection. However, the renal graft dysfunction was deemed irreversible and the renal graft was removed on POD 34. The graftectomy specimen showed acute rejection and acute tubular necrosis with adenovirus infection.

Prophylactic treatment of antibody-mediated rejection with high-dose mizoribine and pharmacokinetic study.

Although mizoribine (MZ), which inhibits inosine monophosphate dehydrogenase in the same way as mycophenolate mofetil, recently proved more effective when higher doses were administered than previously approved, neither the optimal dosage nor blood concentration has yet been clarified. We aimed at investigating the effect of high-doses of MZ on prevention of anti-donor antibody (Ab) production and acute Ab-mediated rejection (AMR) on the basis of the pharmacokinetic profile in a pig kidney transplantation model. Group 1 (n = 5) received cyclosporin microemulsion (6 mg/kg) and prednisolone (0.1 mg/kg). Groups 2, 3 and 4 (each n = 5) were treated, respectively, with 30, 10 and 3 mg/kg of MZ in addition to cyclosporin and prednisolone. The incidences of AMR in groups 1, 2, 3 and 4 were 5/5, 1/5, 3/5 and 5/5, respectively. Anti-donor IgG/IgM Ab levels (relative to pretransplantation levels) on day 14 in groups 1, 2, 3 and 4 were 10.3/9.3, 1.8/1.0, 2.3/1.8 and 6.5/3.5, respectively. While only 2 (28.6%) of seven pigs with Cmax > 3 microg/ml during the first 2 weeks had AMR, 7 (87.5%) of eight pigs with Cmax < 3 microg/ml elicited anti-donor Abs and experienced AMR (P = 0.0406). Effective Cmax seemed to be over 3 microg/ml at minimum. Higher doses of MZ efficiently prevented AMR. However, therapeutic drug monitoring is essential before clinical application.

Is absorption profile of cyclosporine really important for effective immunosuppression?

The clinical significance of cyclosporine (CsA) concentration 2 h postdose (C(2)) monitoring is widely recognized in organ transplantation, because C(2) value is considered to be a predictable surrogate marker of full area under the concentration-time curve (AUC), and/or a peak concentration value exhibits potent inhibition of calcineurin activity. However, the pharmacological advantage of absorption profile (AP) has not been fully elucidated. In a rat skin allotransplantation model, the authors evaluated the efficacy of AP by different dosage regimens (20, 25 or 30 mg/kg/d, once or twice daily) and routes (p.o. or i.v.), and examined whether high C(2) or AUC(0-4) is intrinsically valuable for effective immunosuppression. Graft survival was CsA dose-dependent and correlated with full AUC(0-24), rather than AP. The difference between the once and twice daily administrations did not influence full AUC(0-24) or immunosuppressive effect. Continuous intravenous infusion with flat pharmacokinetics also produced adequate immunosuppression as was observed in enteral administration at the same level of total exposure. The impact of high peak concentration in AP on immunosuppressive effect could not be found. It was suggested that AP would not have intrinsic pharmacodynamic value. However, absorption profiling was considered to be clinically useful in that C(2) value is a good surrogate marker of total exposure (AUC(0-24)).

Potential value of high-dose mizoribine as rescue therapy for ongoing acute humoral rejection.

Mizoribine (MZ) inhibits the proliferation of lymphocytes selectively via inhibition of inosine monophosphate dehydrogenase, like mycophenolate mofetil (MMF). The clinical dosage of MZ (2-5 mg/kg) is much lower than that of MMF (20-60 mg/kg). The purpose of this study was to examine whether high-dose MZ would be effective for treatment of acute humoral rejection. Renal transplantation was performed in a different pig strain combination. Group 1 (n = 2) received no treatment. Group 2 (n = 4) received cyclosporine microemulsion (6 mg/kg) and prednisolone (0.1 mg/kg) as baseline immunosuppression. Groups 3 (n = 4), 4 (n = 4) and 5 (n = 4) were additionally treated with MZ for rescue therapy, 30, 10 and 3 mg/kg, respectively, immediately after rejection was observed. All pigs developed acute vascular rejection between days 4 and 8. Complete reversal of acute rejection including reduction of elevated serum creatinine, suppression of anti-donor antibody production and pathological finding, was obtained in 3/4 (group 3), 1/4 (group 4) and 0/4 (group 5). Rescue with high-dose MZ (30 mg/kg) reversed ongoing acute humoral rejection. Such a high dose of MZ was tolerable for pigs. However, leukocytopenia was observed when MZ trough level was maintained over 10 mug/ml. Treatment with high-dose MZ would be applicable to a clinical trial, if blood level is carefully monitored.

Glomerular capillary tenascin staining in renal allografts and its correlation with capillary loop 'double contours', proteinuria and graft outcome.

BACKGROUND: Glomerular capillary injuries result in proteinuria, previously reported to be a risk factor for renal allograft dysfunction. According to the Banff 97 Working Classification of Renal Allograft Pathology, 'double contours' in glomerular capillary loops (GC-DC) were suggested to be most specific for chronic transplant glomerulopathy. Tenascin-C (TN), a component of extracellular matrix, is known to be overexpressed in various conditions. METHODS: TN immunostaining was performed by the labeled streptavidin biotin method. The correlations between glomerular capillary TN (GC-TN) and proteinuria, and between GC-DC and GC-TN, were studied in 27 biopsies showing chronic allograft nephropathy (CAN) lesions. In 14 patients (serum creatinine <2.0 mg/dl at biopsy), graft outcome was studied. Graft function 3 years after biopsy was classified as stable or deteriorated; the term 'deteriorated' was used if serum creatinine had increased 20% over baseline, or if the patient required dialysis. RESULTS: In CAN, GC-TN correlated with GC-DC. Proteinuria in patients with intense GC-TN tended to increase during 1 year after biopsy. In graft outcome analysis, GC-TN was significantly lower in stable grafts than in deteriorated ones. Furthermore, all 3 patients demonstrating weak GC-TN without GC-DC returned to dialysis. CONCLUSION: TN immunostaining is a sensitive method to detect glomerular capillary injury with a predictive value for renal allograft dysfunction.

A case report of a renal transplant recipient developing chronic glomerular rejection with a weak antibody against anti-donor T-cell, only detected by flow-cytometry crossmatch.

The pathogenesis of antibody-mediated rejection has been investigated, but the precise mechanism of chronic glomerular rejection remains unclear. We have followed the clinicopathological course of a patient with pre-existing anti-donor antibody only detected by flow-cytometry crossmatch for over 3 years. Glomerular endothelial injuries and peculiar glomerular lesions were noted in biopsy specimen of postoperative year 3; however, both typical chronic vascular rejection lesions and peritubular capillary multilayered lesions were not revealed. We consider that the presence of weak anti-donor antibody leading early onset of acute humoral rejection played a role in the pathogenesis of early onset of chronic transplant glomerulopathy.

Complement fragment C4d deposition in peritubular capillaries in acute humoral rejection after ABO blood group-incompatible human kidney transplantation.

BACKGROUND: Acute humoral rejection (AHR) is the most important risk factor for early graft loss in ABO-incompatible (ABO-i) kidney transplantation (RTx). The pathogenesis and diagnostic criteria for AHR after ABO-i RTx remain unclear. Complement fragment C4d deposition in peritubular capillaries (PTC), which is a sensitive indicator for activation of the classical complement pathway, was studied to establish the pathologic diagnostic indicator of AHR. METHODS: Forty-four graft biopsy specimens from 19 patients with ABO-i living donors were analyzed within 90 days after RTx. Nineteen biopsy specimens with acute rejection after ABO-compatible (ABO-c) living-related RTx were used as controls. Diffuse and bright C4d deposition in PTC was considered significantly positive. RESULTS: All of 8 recipients with AHR showed significantly positive C4d in PTC in the ABO-i group, but 9 of 11 recipients without AHR were negative. In the ABO-c RTx group, 16 of 19 recipients were negative for C4d in PTC. The prevalence of C4d in PTC was significantly higher in ABO-i RTx (P<0.05). CONCLUSIONS: C4d deposition is valuable as a specific and sensitive indicator for AHR, even of mild severity, in ABO-i RTx.

Enzymatic removal of alphaGal antigen in pig kidneys by ex vivo and in vivo administration of endo-beta-galactosidase C.

Xenotransplantation using the pig as a donor species is considered to be a promising solution to the serious shortage of organ donors. Both hyperacute and acute vascular rejection (AVR) are believed to be associated with xenoreactive antibody binding to alphaGal epitopes on the pig vascular endothelial cells. Thus, suppression of this antigen-antibody reaction would appear essential for successful long-term xenograft survival. The purpose of this study was to examine the efficacy of ex vivo and in vivo administration of recombinant endo-beta-galactosidase C (EndoGalC which, in previous in vitro studies, has been proven to digest alphaGal antigens completely) on alphaGal epitopes expressed in pig kidneys. Excised pig kidneys were perfused with University of Wisconsin solution containing EndoGalC and preserved for 4 h. After cold storage, the pig kidney was transplanted into another pig. Ex vivo perfusion and cold storage with EndoGalC reduced alphaGal epitope expression on vascular endothelial cells to an undetectable level. However, alphaGal antigens began to be expressed again as early as 1 day after transplantation. The digestion of alphaGal epitopes by EndoGalC did not cause any damage to the kidney graft. EndoGalC was intravenously administered to two pigs (15 kg), without causing any serious adverse effect. Twelve hours later, >98% of alphaGal antigens on pig red blood cells (RBCs) had been digested. Immunohistochemical study revealed almost complete elimination of alphaGal expression on vascular endothelial cells of the kidney graft 4 and 8 h after in vivo administration, but reappearance within 24 h. EndoGalC was administered to a baboon after an interval of 2 months. The second administration did not result in any serious toxicity or reduction in efficacy. These results suggest that ex vivo and in vivo administration of EndoGalC is simple and useful in removing alphaGal epitopes from pig organs. As the effect of EndoGalC is temporary, multiple in vivo administrations of EndoGalC would be required to inhibit the reappearance of alphaGal epitopes. Alternatively, transgenic techniques of introducing the gene for EndoGalC into the donor organ might permanently prevent alphaGal expression.