Higher Donor Age and Severe Microvascular Inflammation Are Risk Factors for Chronic Rejection After Treatment of Active Antibody-Mediated Rejection.

Recent developments in intensive desensitization protocols have enabled kidney transplantation in human leukocyte antigen (HLA)-sensitized recipients. However, cases of active antibody-mediated rejection (AABMR), when they occur, are difficult to manage, graft failure being the worst-case scenario. We aimed to assess the impact of our desensitization and AABMR treatment regimen and identify risk factors for disease progression. Among 849 patients who underwent living-donor kidney transplantation between 2014 and 2021 at our institution, 59 were diagnosed with AABMR within 1 year after transplantation. All patients received combination therapy consisting of steroid pulse therapy, intravenous immunoglobulin, rituximab, and plasmapheresis. Multivariable analysis revealed unrelated donors and preformed donor-specific antibodies as independent risk factors for AABMR. Five-year death-censored graft survival rate was not significantly different between patients with and without AABMR although 27 of 59 patients with AABMR developed chronic AABMR (CABMR) during the study period. Multivariate Cox proportional hazard regression analysis revealed that a donor age greater than 59 years and microvascular inflammation (MVI) score (g + ptc) ≥4 at AABMR diagnosis were independent risk factors for CABMR. Our combination therapy ameliorated AABMR; however, further treatment options should be considered to prevent CABMR, especially in patients with old donors and severe MVI.

Outcomes of kidney transplantation in recipients with SARS-cov-2 infection: a 282-case single-center experience in Japan.

BACKGROUND: The coronavirus disease 2019, caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has become a global epidemic. There are concerns regarding the severity of SARS-CoV-2 infections in kidney transplant (KTx) recipients. However, there is limited data on how the epidemic has affected the treatment and prognosis of these patients. Therefore, we aimed to report the changes in the treatment and outcomes of KTx recipients infected with SARS-CoV-2 during each wave at our institution. METHODS: A total of 282 KTx recipients who were infected with SARS-CoV-2 during the study period were followed up at Tokyo Women's Medical University between March 2020 and August 2022. We investigated the outcomes and treatments of infected KTx recipients. RESULTS: Nineteen (6.7%) patients showed severe outcomes, including eight SARS-CoV-2 infection-related deaths. Risk factors associated with severe outcomes included underlying conditions, such as diabetes mellitus, heart disease, and liver disease (odds ratios, 2.09, 2.88, and 5.52, respectively). Treatment strategies changed throughout the epidemic in response to changes in the SARS-CoV-2 variants. Antiviral drugs were gradually administered as soon as they were approved for use. CONCLUSIONS: Treatment strategies for KTx recipients were gradually established over the course of the epidemic. Although the proportion of infected KTx recipients decreased compared to that of the general population throughout the epidemic, many patients still followed a severe course.

The medical cost and outcome of desensitization protocol in kidney transplantation recipients with high immunological risks.

BACKGROUND: Kidney transplantation is a well-established alternative in renal replacement therapy. Compared with hemodialysis, low-immunological-risk kidney transplantation can reduce the medical treatment costs associated with end-stage renal disease. However, there are few reports on whether high-immunological-risk kidney transplantation reduces the financial burden on governments. We investigated the medical costs of high-immunological-risk kidney transplantation in comparison with the cost of hemodialysis in Japan. METHODS: We compared the medical costs of high-immunological-risk kidney transplantation with those of hemodialysis. 15 patients who underwent crossmatch-positive and/or donor-specific antibody-positive kidney transplantations between 2020 and 2021 were enrolled in this study. The patients received intravenous immunoglobulin, plasmapheresis, and rituximab as desensitizing therapy. RESULTS: Acute antibody-mediated rejection was detected in nine (60%) recipients, while there were no indications of graft function deterioration during the follow-up. For each patient, the transplant hospitalization cost was 38 428 ± 8789 USD. However, the cumulative costs were 59 758 ± 10 006 USD and 79 781 ± 16 366 USD, at 12 and 24 months, respectively. Compared with hemodialysis (34 286 USD per year), high-immunological-risk kidney transplantation tends to be expensive in the first year, but the cost is likely to be lower than that of hemodialysis after 3 years. CONCLUSIONS: Although kidney transplantation is initially expensive compared with hemodialysis, the medical cost becomes advantageous after 3 years even in kidney transplant recipients with high immunological risk.

Pregnancy Complications and Impact on Kidney Allograft After Kidney Transplantation in IgA Nephropathy.

Pregnancy in kidney transplantation (KT) recipients has been challenging because of the high risk of maternal, fetal, and renal complications. Although patients with immunoglobulin A nephropathy (IgAN)-chronic kidney disease (CKD) are at a high risk for hypertension in pregnancy (HIP), the maternal risk in KT recipients with IgAN as the etiology remains unclear. We retrospectively reviewed the medical records of pregnant KT recipients who delivered at our hospital. The incidence of maternal and fetal complications and the impact on kidney allografts between the group with IgAN as the primary kidney disease and the group with other primary diseases were compared. The analysis included 73 pregnancies in 64 KT recipients. The IgAN group had a higher incidence of HIP than the non-IgAN group (69% vs. 40%, p = 0.02). IgAN as primary kidney disease and interval from transplantation to conception were associated with HIP (OR 3.33 [1.11-9.92], p = 0.03, OR 0.83 [0.72-0.96], p < 0.01, respectively). The 20-year graft survival or prevention of CKD stage 5 in group with IgAN was lower than that in the group with other primary disease (p < 0.01). KT recipients should be informed of the risk of HIP and possibility of long-term worsening of postpartum renal function.

Role of Fractalkine-CX3CR1 Axis in Acute Rejection of Mouse Heart Allografts Subjected to Ischemia Reperfusion Injury.

Transplantation outcomes are affected by the increase in rejection associated with ischemia reperfusion injury (IRI). Fractalkine (FKN), a chemokine for recruitment of CX3CR1+ leukocytes, contributes to the pathogenesis of various inflammatory diseases. Herein, we evaluated the importance of the FKN-CX3CR1 axis during IRI-related rejections using a mouse heterotopic heart transplantation model. FKN expression and graft survival was compared between wild-type C57BL/6 recipients transplanted with BALB/c hearts preserved for 8 (WT-IRI) and 0.5 h (WT-control) at 4°C. Graft survival of WT-IRI was shorter than that of WT-control. FKN was expressed on the vascular endothelium in WT-IRI allografts, but minimally in WT-control. The role of the FKN-CX3CR1 axis in IRI-related rejection was directly investigated using the transplant model with CX3CR1-deficient recipients (CX3CR1 KO-IRI) or treatment with anti-mouse FKN monoclonal antibodies. Graft survival of CX3CR1 KO-IRI was longer than that of WT-IRI; antibody treatment prolonged graft survival. The contribution of CX3CR1+ monocytes to IRI-related rejection was evaluated by adoptive transfer to CX3CR1 KO-IRI. Adoptive transfer of CX3CR1+ monocytes attenuated the effect of prolonged graft survival in CX3CR1 KO-IRI. Overall, the FKN-CX3CR1 axis plays a major role during IRI-related rejection; its blockade has the potential to improve the outcomes of deceased donor transplantation.

Impact of donor-related arteriosclerosis in pretransplant biopsy on long-term outcome of living-kidney transplantation: A propensity score-matched cohort study.

OBJECTIVES: To compare the long-term outcome and complications of living-kidney grafts with arteriosclerosis to those without abnormal findings diagnosed using pretransplant graft biopsy, and to assess the impact of the arteriosclerosis in living-donor kidneys. METHODS: The influence of arteriosclerosis in pretransplant biopsy on long-term outcomes and complications was evaluated in both unmatched (n = 1351, without arteriosclerosis n = 788 vs with arteriosclerosis n = 563) and propensity score-matched cohorts (n = 984, without arteriosclerosis n = 492 vs with arteriosclerosis n = 492) of adults who underwent living-kidney transplant. RESULTS: In both the unmatched and matched cohort, there was no significant difference in patient and death-censored graft survival at 10 years between the without arteriosclerosis and with arteriosclerosis groups. The with arteriosclerosis group had a higher incidence rate of overall rejection than did the without arteriosclerosis group in both the unmatched (P = 0.026) and matched (P = 0.060) cohorts. The with arteriosclerosis group had significantly higher chronic antibody-mediated rejection than did the without arteriosclerosis group (P = 0.006) in the unmatched cohort. The with arteriosclerosis group had a significantly lower estimated glomerular filtration rate in recipients, but there was no significant difference after matching. The incidence rates of calcineurin inhibitor nephrotoxicity and post-transplant anemia were significantly higher in the with arteriosclerosis group than in the without arteriosclerosis group in both the unmatched and matched cohorts. Long-term postoperative kidney function of living donors was lower in the with arteriosclerosis group. CONCLUSIONS: Kidney graft with arteriosclerosis might affect the incidence of rejection, complications and postoperative kidney function of donors. Long-term careful observation is required for both the recipients who received grafts with arteriosclerosis and the donors who had kidneys with arteriosclerosis.

Evaluation of the impact of conventional immunosuppressant on the establishment of murine transplantation tolerance - an experimental study.

Regulatory T cells (Tregs) play a significant role in immune tolerance. Since Treg function deeply depends on Interleukin-2 signaling, calcineurin inhibitors could affect their suppressive potentials, whereas mammalian target of rapamycin (mTOR) inhibitors may have less impact, as mTOR signaling is not fundamental to Treg proliferation. We previously reported a novel mixed hematopoietic chimerism induction regimen that promotes Treg proliferation by stimulating invariant natural killer T cells under CD40 blockade. Here, we use a mouse model to show the impact of tacrolimus (TAC) or everolimus (EVL) on the establishment of chimerism and Treg proliferation in the regimen. In the immunosuppressive drug-dosing phase, peripheral blood chimerism was comparably enhanced by both TAC and EVL. After dosing was discontinued, TAC-treated mice showed gradual graft rejection, whereas EVL-treated mice sustained long-term robust chimerism. Tregs of TAC-treated mice showed lower expression of both Ki67 and cytotoxic T lymphocyte antigen-4 (CTLA-4), and lower suppressive activity in vitro than those of EVL-treated mice, indicating that TAC negatively impacted the regimen by interfering with Treg proliferation and activation. Our results suggest that the usage of calcineurin inhibitors should be avoided if utilizing the regimen to induce Tregs in vivo for the establishment of mixed hematopoietic chimerism.

Two cases of kidney transplantation-associated thrombotic microangiopathy successfully treated with eculizumab.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is relatively rare and requires immediate intervention to avoid irreversible organ damage or death; however, consensus regarding the treatment approach is lacking. Atypical haemolytic uraemic syndrome (aHUS) is a rare disease caused by dysregulation of the alternative complement pathway resulting in TMA. aHUS is histologically similar to TA-TMA; approximately 60% of TA-TMA patients have complement dysregulation. Eculizumab, a humanized anti-C5 monoclonal antibody, inhibits terminal membrane-attack complex formation and TMA progression. Eculizumab has been successfully used to treat aHUS post-transplant. We present two cases of kidney TA-TMA due to unknown causes, suspected antibody-mediated rejection, or calcineurin inhibitor (CNI)-related toxicity that developed on day 1 or 2 post-kidney transplantation. Low platelet count and haemoglobin level with red cell fragments were detected. Despite steroid pulse, plasma exchange (PE), and intravenous immunoglobulin therapy, TA-TMA did not improve; therefore, eculizumab was administered despite no genetic testing. Laboratory data, including renal function, improved immediately. TA-TMA treatment primarily involves PE initiation or CNI discontinuation; eculizumab can be used to safely treat TA-TMA and then be ceased in the short term. Therefore, eculizumab administration might be beneficial for kidney TA-TMA as early as the diagnosis of refractory to PE.

A case of recurrent focal segmental glomerulosclerosis after kidney transplantation associated with variant conversion in the Columbia classification.

Focal segmental glomerulosclerosis commonly recurs following kidney transplantation. A 33-year-old man underwent living donor kidney transplantation. Proteinuria appeared two months after transplantation, and an episode biopsy on postoperative day 66 revealed recurrent focal segmental glomerulosclerosis lesions of the cellular variant by Columbia classification. We reviewed the native kidney biopsy and confirmed collapsing variant focal segmental glomerulosclerosis. Plasma exchange therapy was performed, and his proteinuria temporarily resolved. A second allograft biopsy performed on postoperative day 200 showed no evidence of focal segmental glomerurosclerosis. He experienced incomplete remission with a proteinuria of 0.5 g/day during the subsequent three years until his urinary protein level rose to 1.3 g/day. A third biopsy performed on postoperative day 1248 showed focal segmental glomerulosclerosis cellular variant lesions. Plasma exchange was resumed in combination with additional rituximab, but his proteinuria persisted. Intermittent plasma exchange was performed 42 times in total. However, his proteinuria continued, and his renal function gradually worsened. A fourth biopsy performed on postoperative day 2540 showed focal segmental glomerulosclerosis collapsing variant lesions with severe interstitial fibrosis and tubular atrophy. He ultimately required hemodialysis seven years after transplantation. Intensive therapy with long-term intermittent plasma exchange and rituximab suppressed proteinuria and preserved graft function for seven years, at which time graft failure occurred. We here present the clinical course and histological findings from consecutive allograft biopsies.

En bloc kidney transplantation from pediatric donors to teenage recipients: Two case reports.

Introduction: Since the implementation of the new selection criteria in 2018, kidney donations from pediatric patients have been prioritized for pediatric recipients and kidney donations from pediatric donors have increased in Japan. Herein, we present two cases of en bloc kidney transplantation. Case presentation: Case 1: A 19-year-old male patient who had been on hemodialysis for 5 years due to end-stage renal disease. After brain death, a graft from a 5-year-old boy was transplanted into the right iliac fossa. Case 2: A 19-year-old male patient, who had previously undergone a living kidney transplantation at the age of 3, received a secondary cadaveric kidney transplantation in the left iliac fossa. The graft was procured from a 17-month-old girl following cardiac death. Conclusion: This report will help surgeons perform en bloc kidney transplantation in the growing number of pediatric kidney donations, such as those in Japan.

Delayed peak antibody titers after the second dose of SARS-CoV-2 vaccine in solid organ transplant recipients: Prospective cohort study.

Poor post-vaccination production of antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a concern among solid organ transplant (SOT) recipients. Furthermore, the timing and kinetics of antibody titers after the second vaccine dose are unknown. We conducted a multicenter prospective observational study that included 614 SOT recipients: 460 kidney, 53 heart, 50 liver, 20 lung, and 31 simultaneous pancreas-kidney (SPK). The participants received two doses of the mRNA vaccine (Pfizer BNT162b2 or Moderna mRNA-1273), as indicated. Serum samples were collected before the first and second vaccinations and at 1, 3, and 6 months after the second vaccine dose, which were then assessed for SARS-CoV-2 antibodies. The overall seropositivity rate was 43% at 1 month after administration of the second vaccine dose; it gradually increased to 68% at 3 months after second dose administration and to 70% at 6 months. In addition, recipient of kidney, lung or SPK transplants had lower antibody titers at the 3- and 6-month time points than did the other recipients. SOT recipients acquired SARS-CoV-2 S-IgG antibodies slowly, and the peak titer differed significantly from that of the general population.

Kidney Transplantation After Multiple Urinary Tract Conversion with an Ileal Conduit: A Case Report.

BACKGROUND: Kidney transplantation (KTx) after urinary tract conversion surgery is extremely difficult due to several complications. In our case, KTx was performed after multiple operative procedures, including diversion urethrostomy. CASE REPORT: The patient was a 46-year-old woman with a right atrophic kidney, an ectopic opening of the left ureter, and urethral dysplasia since birth. The patient underwent a right nephrectomy, left ureteral sigmoidostomy, Stamey surgery, augmentation ileocystoplasty, and left ureteroileostomy. Thereafter, she underwent nephrostomy, ileal conduit diversion, open sigmoid colectomy, and total cystectomy because of persistent urinary incontinence, sigmoid colon cancer, and recurrent cystitis. Her renal function gradually deteriorated, and hemodialysis was initiated. Before the KTx, she underwent laparoscopic left nephrectomy, an intraperitoneal adhesion debridement, and left ileal conduit resection. We dissected the left ileal conduit in the abdominal cavity and penetrated the anorectal side of the free ileal conduit into the wall of the right side of the abdomen. Thereafter, a kidney from a living donor was transplanted into the right iliac fossa through the existing right ileal conduit when the patient was 46 years old. The allograft function was stable without rejection for 2 years. CONCLUSIONS: We report the case of a patient who underwent multiple urethral modifications followed by ileal conduit transfer and living donor KTx, which progressed without major postoperative complications.

The efficacy of neutralizing monoclonal antibodies in transplant recipients with mild-to-moderate COVID-19.

INTRODUCTION: Transplant recipients (TRs) are at high risk for severe coronavirus disease 2019 (COVID-19). Neutralizing monoclonal antibodies (mAbs) are used for treating mild-to-moderate COVID-19. However, reports comparing the efficacy of COVID-19 treatment without/with mAbs in TRs are limited. We assessed the efficacy of casirivimab/imdevimab against mild-to-moderate COVID-19 in TRs. METHODS: Forty-one patients were retrospectively evaluated. The duration until defervescence, oxygen (O2) requirement ≥5 L, and neutralizing antibody levels were compared in TRs with COVID-19 without/with casirivimab/imdevimab. RESULTS: Casirivimab/imdevimab was correlated with shorter duration until defervescence and non-requirement of O2 ≥ 5 L in TRs with COVID-19 [mean: without/with: 6 vs. 2; P = 0.0002, hazard ratio (HR) = 0.3333, 95% confidence interval (CI) = 0.1763-0.6301; 15 vs. 8; P < 0.0001, HR = 0.5333, 95% CI = 0.2878-0.9883; P = 0.0377, HR = 0.1502, 95% CI = 0.02511-0.8980]. Casirivimab/imdevimab was associated with early defervescence after adjusting for sex and age (P = 0.013, HR = 0.412, 95% CI = 0.205-0.826). The antibody levels between patients without/with casirivimab/imdevimab on the day of hospitalization were not significantly different (P = 0.1055), including 13 TRs with vaccination. Antibody levels were higher in patients with casirivimab/imdevimab at 3-5 days after hospitalization than in those without, at 7-9 days after hospitalization (P < 0.0001, mean, without/with: 414.9/40000 AU/mL). CONCLUSION: Casirivimab/imdevimab was effective and increased the neutralizing antibody in TRs with mild-to-moderate COVID-19, it may contribute toward preventing the progression.

A Comparative Study on the Variation in Seropositivity Rates After 2-Dose COVID-19 Vaccination Before or After Transplant: A Single-Center Analysis.

OBJECTIVES: Many researchers have demonstrated that the seropositivity rate after SARS-CoV-2 coronavirus vaccination is lower in patients receiving oral immunosuppressants. In this article, we report on a comparative study on the seropositivity rate after 2 doses of coronavirus vaccine before or after kidney transplant. MATERIALS AND METHODS: We studied 111 recipients vaccinated after transplant, 19 patients vaccinated before transplant, and 10 healthy patients. We retrospectively measured antibody titers using preserved serum samples. The antibody testing was performed 1 month and 3 months after vaccination. The measurement was via LABScreen COVID Plus, which enables simultaneous determination of 5 coronavirus protein antigens. RESULTS: Seropositivity to coronavirus antibodies was observed in all 19 patients vaccinated before transplant (100%) and in all the 10 healthy patients (100%). Forty- six of the 111 recipients (42%) vaccinated after transplant developed seropositivity. Analyzed at each time point after vaccination, the mean fluorescence intensity of antibodies was unchanged between 1 month and 3 months after vaccination in transplant recipients who were vaccinated after transplant and developed seropositivity. On the other hand, the antibody mean fluorescence intensity in patients vaccinated before transplant was markedly lower at 3 months (posttransplant). CONCLUSIONS: All patients with renal failure who were vaccinated before transplant showed a high seropositivity rate, similar to that in healthy patients. The seropositivity rate for each of the viral fragment antibodies in patients vaccinated before transplant was maintained, as seen in healthy patients. However, in patients vaccinated before transplant who tested positive for antibody production at 1 month after vaccination,the antibody mean fluorescence intensity at 3 months after vaccination (posttransplant) was remarkedly lower than the mean fluorescence intensity at 1 month, which was probably caused by the types of immunosuppressive regimens used atthe time of transplant.

Safe Renal Transplantation to the Extraperitoneal Cavity in Children Weighing Less Than 15 kg.

Pediatric renal transplantation is associated with various surgical complications due to the complexity of the technique and the often-fragile condition of patients with end-stage renal disease. We evaluated the surgical complications associated with renal transplantation via the extraperitoneal approach in pediatric recipients. This retrospective study enrolled 280 patients younger than 16 years old who underwent renal transplantation via the extraperitoneal approach: 216 patients underwent transplant placement in the iliac fossa like in adults, and 64 underwent transplant placement in the distal part of the original renal lower pole (the extraperitoneal cavity). On the basis of the Clavien-Dindo classification, 30 patients (10.7%) showed grade 2 complications and 12 patients (4.3%) showed grade 3 or higher complications. None of the patients showed gastrointestinal complications. In a Cox regression analysis, grade 2 or higher complications were significantly associated with weight less than 15 kg (P = .027) and operative times longer than 245 minutes (P = .029). Among the 49 patients weighing less than 15 kg with an allograft placed in a distal portion of the original renal lower pole, only 3 patients (6.1%) developed surgical complications. Thus, allograft placement in the extraperitoneal cavity can be performed safely in children weighing less than 15 kg.

Desensitization Regimen Consisting of High-Dose Intravenous Immunoglobulin, Plasmapheresis, and Rituximab (an Anti-CD20 Antibody), Without Eculizumab and/or Bortezomib, in 41 Highly Sensitized Kidney Transplant Recipients.

OBJECTIVES: Antibody-mediated rejection in patients with positive crossmatches can be severe and result in sudden onset of oliguria, leading to graft loss. In an attempt to prevent posttransplant oliguria, we adopted a preoperative desensitization protocol involving the use of high-dose intravenous immunoglobulin/plasmapheresis and the anti-CD20 antibody, rituximab, in 41 transplant recipients with positive crossmatch test results. MATERIALS AND METHODS: We retrospectively examined the clinical courses of the 41 kidney transplant recipients, paying special attention to renal graft function, urine volume, and changes in the titers of donor-specific antibodies. RESULTS: Four grafts were lost during an average of 4.5-year follow-up. Average graft function was excellent, with a serum creatinine level of 1.3 ± 0.4 mg/dL. Sufficient urine output, with no oliguria or anuria, was achieved postoperatively in 40 of the 41 patients. However, among the 34 patients who underwent graft biopsies, the biopsies revealed acute antibody-mediated rejection in 21 patients (62%), and chronic antibodymediated rejection in 10 patients (30%). CONCLUSIONS: The high-dose intravenous immunoglobulin treatment included in our desensitization protocol was shown to be safe and effective for achieving successful transplant outcomes and allowed the avoidance of more aggressive B-cell-targeted treatments, such as C5 inhibitors and/or proteosome inhibitors, for preventing posttransplant oliguria and anuria.

Robot-Assisted Laparoscopic Partial Nephrectomy for Allograft Renal Cell Carcinoma: A Case Report.

BACKGROUND: Nephron-sparing surgery is required for patients with kidney transplant with organ-confined renal cell carcinoma (RCC) in the allograft kidney to preserve renal function. Robot-assisted laparoscopic partial nephrectomy (RAPN) is expected to be the optimal surgical approach for these patients, as in the general population. However, RAPN for RCC arising in the allograft kidney is rarely reported. Here, we report 2 cases of patients who underwent RAPN for allograft RCC. CASE PRESENTATION: Two patients were diagnosed with RCC in the renal allograft based on enhanced computed tomography findings. Case 1 was a 69-year-old man with a 32-mm mass in the middle portion of the right iliac fossa renal allograft, and case 2 was a 55-year-old man with a 24-mm mass in the lower pole of the right iliac fossa renal allograft. In each patient, RAPN was performed for the renal mass through a transperitoneal approach, with clamping of the renal artery. No major perioperative complications occurred in either patient, negative surgical margins were achieved, and no significant changes in kidney function were observed during either surgery. Pathologic findings showed clear cell RCC in case 1 and papillary RCC in case 2. CONCLUSION: RAPN can be a feasible and effective treatment option for allograft RCC.

Combination therapy of an iNKT cell ligand and CD40-CD154 blockade establishes islet allograft acceptance in nonmyeloablative bone marrow transplant recipients.

AIMS: Islet transplantation is an effective therapeutic option for type 1 diabetes. Although maintenance immunosuppression therapy is required to prevent allogeneic rejection and recurrence of autoimmunity, long-term allograft survival has not yet been achieved partly because of its adverse effects. The induction of donor-specific immunotolerance is a promising approach for long-term allograft survival without maintenance immunosuppression therapy. We previously reported that combination therapy using a liposomal ligand for invariant natural killer T cells, RGI-2001, and anti-CD154 antibody established mixed hematopoietic chimerism for the induction of donor-specific immunotolerance. This study investigated whether the protocol could promote islet allograft acceptance in experimental diabetes. METHODS: Streptozotocin-induced diabetic BALB/c mice were transplanted with bone marrow cells from C57BL/6 donors and received combination therapy of RGI-2001 and anti-CD154 antibody after 3-Gy total body irradiation. 3 Weeks after bone marrow transplantation, islets isolated from C57BL/6 donors were transplanted under the kidney capsule. RESULTS: Mixed chimerism was established in diabetic mice receiving the tolerance induction protocol. After islet transplantation, blood glucose levels improved and normoglycemia persisted for over 100 days. Hyperglycemia recurred after islet grafts were removed. Histopathological examinations showed insulin-positive staining and absence of cellular infiltration in the islet grafts. T cells of recipients showed donor-specific hyporesponsiveness, and anti-donor antibodies were not detected. CONCLUSIONS: The tolerance induction protocol with combination therapy of RGI-2001 and anti-CD154 antibody promoted islet allograft acceptance in a mouse diabetic model. This protocol may be clinically applied to islet transplantation for type 1 diabetes mellitus.

Impact of activated invariant natural killer T cells on the expansion of regulatory T cell precursors in murine thymocytes in vitro.

Tolerance induction is a goal of clinical transplantation to prevent graft rejection without the lifelong use of immunosuppressive drugs. In a series of mouse studies, we previously reported that the establishment of mixed chimerism by treatment with a ligand for invariant natural killer T (iNKT) cells with CD40 signal blockade makes it possible to prevent allograft rejection without immunosuppressants, and this approach fails in thymectomized recipient mice. In this study, we showed that iNKT cells in murine thymocyte cultures are indispensable for the expansion of CD4+CD25+Foxp3+ regulatory T (Treg) cells as well as CD4+CD25+Foxp3- cells, which contained precursor Tregs (preTregs). After the culture of BALB/c mouse-derived thymocytes in the presence of α-galactosylceramide (α-GalCer), a representative ligand for iNKT cells, the ratio of CD4+CD25+Foxp3- preTregs to total CD4+CD8- T cells was much higher than that of CD4+CD25+Foxp3+ Treg cells, regardless of anti-CD40 L mAb treatment. The proliferation of CD4+CD25+Foxp3- cells, but not Treg cells, was significantly augmented, and the stability of Treg cells was not affected by α-GalCer. The expansion of thymocyte-derived Tregs was not inhibited by cytokine neutralization. However, in vitro thymus-derived CD4+CD25+Foxp3- cells expressed Foxp3 after IL-2 stimulation in a dose-dependent manner. These results collectively suggest that in vitro thymus-derived Treg cell expansion by α-GalCer treatment was caused by the proliferation of CD4+CD25+Foxp3- preTregs but not existing Treg cells.

Incidental detection of asymptomatic migration of Hem-o-lok clip into the bladder after laparoscopic radical prostatectomy.

Hem-o-lok clips have been widely used in laparoscopic or robot-assisted surgery. We report a case of an incidentally discovered Hem-o-lok migration into the bladder after laparoscopic radical prostatectomy. The patient was a 75-year-old man with localized prostate cancer who underwent laparoscopic radical prostatectomy in July 2009. At 3 postoperative years, follow-up ultrasonography revealed a small round mass in the bladder. No lower urinary tract symptoms were reported, and urinalysis results had never indicated hematuria or pyuria. Cystoscopy revealed a Hem-o-lok clip in the bladder, near the vesicourethral anastomotic site. We could not remove it with forceps in the outpatient clinic, so we performed the procedure again under general anesthesia and successfully removed the Hem-o-lok clip. To our knowledge, this is the first report of an asymptomatic Hem-o-lok migration into the bladder.