Kazuaki Yamanaka

Adipose tissue-derived stem cells suppress acute cellular rejection by TSG-6 and CD44 interaction in rat kidney transplantation.

Background In addition to its abundance and easy accessibility, adipose tissue yields more potent immunoregulatory stem cells (adipose tissue-derived stem cells, ADSCs) than does bone marrow. However, the beneficial effects of ADSCs on alloreactivity are scarcely known. This study evaluated the beneficial effects of ADSCs in rat kidney transplantation and analyzed the underlying molecular mechanism. Methods Dark Agouti rat kidneys were transplanted into Lewis rats. Autologous ADSCs (2×106) were injected through the left renal artery of the donors before the nephrectomy (ADSCs group). Graft survival, histologic changes, and the expression of several cytokines and proteins were assessed. In an in vitro experiment, the immunosuppressive capacity of ADSCs was tested in a mixed lymphocyte reaction. Results Histologic findings of the ADSCs group revealed a reduced rejection grade, whereas the number of infiltrated CD4+/CD8+ T cells was also significantly decreased as compared to the control. Relative to these findings, injection of ADSCs led to a significantly prolonged mean graft survival compared with the control. In vitro, autologous ADSCs dose-dependently suppressed alloreactive lymphocytes. Moreover, ADSCs increased the level of tumor necrosis factor-inducible gene 6 protein (TSG-6) in mixed lymphocyte reaction, which has an anti-inflammatory capacity. Recombinant TSG-6 markedly suppressed alloreactive T cells through downregulating CD44, which may lead to the suppression of T-cell activation and infiltration into allografts. Conclusion Our findings clearly showed that ADSCs attenuated acute rejection by secreting TSG-6 as well as through direct cell interaction. These findings contribute to the clinical application of these cells in solid organ transplantation.

Depression of Complement Regulatory Factors in Rat and Human Renal Grafts Is Associated with the Progress of Acute T-Cell Mediated Rejection

Background The association of complement with the progression of acute T cell mediated rejection (ATCMR) is not well understood. We investigated the production of complement components and the expression of complement regulatory proteins (Cregs) in acute T-cell mediated rejection using rat and human renal allografts. Methods We prepared rat allograft and syngeneic graft models of renal transplantation. The expression of Complement components and Cregs was assessed in the rat grafts using quantitative real-time PCR (qRT-PCR) and immunofluorescent staining. We also administered anti-Crry and anti-CD59 antibodies to the rat allograft model. Further, we assessed the relationship between the expression of membrane cofactor protein (MCP) by immunohistochemical staining in human renal grafts and their clinical course. Results qRT-PCR results showed that the expression of Cregs, CD59 and rodent-specific complement regulator complement receptor 1-related gene/protein-y (Crry), was diminished in the rat allograft model especially on day 5 after transplantation in comparison with the syngeneic model. In contrast, the expression of complement components and receptors: C3, C3a receptor, C5a receptor, Factor B, C9, C1q, was increased, but not the expression of C4 and C5, indicating a possible activation of the alternative pathway. When anti-Crry and anti-CD59 mAbs were administered to the allograft, the survival period for each group was shortened. In the human ATCMR cases, the group with higher MCP expression in the grafts showed improved serum creatinine levels after the ATCMR treatment as well as a better 5-year graft survival rate. Conclusions We conclude that the expression of Cregs in allografts is connected with ATCMR. Our results suggest that controlling complement activation in renal grafts can be a new strategy for the treatment of ATCMR.

The benefits of cancer screening in kidney transplant recipients: a single‐center experience

The frequency of malignancy is increasing in kidney transplant recipients. Posttransplant malignancy (PTM) is a major cause of long‐term graft survival inhibition. In this study, we evaluated the frequency and prognosis of PTM at our center and examined the efficacy of cancer screening. Between 1972 and 2013, 750 patients were followed‐up at our center. Annual physical examinations and screenings were performed to detect PTM. We investigated the detail of two distinctive cancer groups: screening‐detected cancers and symptom‐detected cancers. Seventy‐seven PTM were identified during the follow‐up period. The mean age at the initial PTM detection was 43.6 ± 12.8 years. The mean interval from transplantation to cancer diagnosis was 134.5 ± 11.3 months. Among the 77 patients, posttransplant lymphoproliferative disease (PTLD) was the most common cancer (19.5%, 15/77), followed by renal cell carcinoma (15.6%, 12/77). Of the cancer cases, 46.8% (36/77) were detected via screening. The most frequently screening‐detected cancer was renal cell carcinoma of the native kidney and breast cancer (22.2%, 8/36). However, it was difficult to detect PTLD, urothelial carcinoma, and colorectal cancer via screening. Interestingly, Cox proportional regression analyses revealed nonscreened recipients to be a significant prognostic factor for PTM (P < 0.001). This study is the first to report that appropriate screening tests play a key role in early PTM diagnosis and lead to reduce the mortality rate in kidney transplant recipients. These findings support the provision of long‐term appropriate screening for kidney transplant recipients.

Immunohistochemical features of BK virus nephropathy in renal transplant recipients

BK virus nephropathy (BKVN) is one of the factors that reduces renal graft function after transplantation. However, BKVN and rejection present similar pathological findings, as both are accompanied by cellular infiltration to the interstitium and tubulitis, thus they are difficult to distinguish for diagnosis and medical treatment. In the present study, we examined immunohistochemical pathological features of BKVN in four cases treated in our hospital from 2007 to 2010. Common immunohistological finding is that tubulitis in these cases was primarily EMA and 34βE12‐positive and existed predominantly from the collecting duct to the distal convoluted tubule. The majority of infected cells existed in EMA and 34βE12‐positive tubules, which were also located mainly from the collecting duct to the distal tubule. In addition, a large number of SV40‐positive infected cells were similarly seen. Dylon staining clearly revealed eosinophils. We concluded that the main pathological features of BKVN are the presence of tubulitis and infected cells predominantly from the collecting duct to distal tubule and the appearance of eosinophils.

Monocytic MDSCs regulate macrophage-mediated xenogenic cytotoxicity.

BACKGROUND Xenotransplantation is considered to be one of the most attractive strategies for overcoming the worldwide shortage of organs. However, many obstructions need to be overcome before it will achieve clinical use in patients. One such obstacle is the development of an effective immunosuppressive strategy. We previously reported that myeloid-derived suppressor cells (MDSCs), a heterogeneous population of progenitor and immature myeloid cells, suppress xenogenic CTL-mediated cytotoxicity. Because of their heterogeneous nature, MDSC can function via several suppressive mechanisms that disrupt both innate and adaptive immunity. Since macrophages play a pivotal role in the rejection of a xenograft, in this study, we evaluated the suppressive effects of MDSC against macrophage-mediated xenogenic rejection. MATERIALS AND METHODS To evaluate the effect of monocyte-derived MDSCs on xenogenic immune reactions, a CFSE(carboxyfluorescein diacetate, succinimidyl ester)assay was employed to assess cytotoxicity. RESULTS While, in the absence of activation, primed MDSCs had no detectable effect on macrophage-induced cytotoxicity against SEC cells, LPS-activated MDSCs were found to significantly suppress xenogenic cytotoxicity. A CFSE cytotoxicity assay revealed that MDSCs significantly suppressed macrophage-induced cytotoxicity. Furthermore, an indoleamine 2,3 dioxygenase (IDO) inhibitor, 1-methyl tryptophan (1-MT), abolished the MDSC-induced suppression of macrophage-mediated xeno-rejection, indicating that MDSCs may suppress macrophage-mediated cytotoxicity in an IDO-dependent manner. CONCLUSION These findings indicate that MDSCs have great potential for immunosuppressing macrophage-mediated xeno-rejection.

Risk factors and incidence for lipid abnormalities in kidney transplant patients.

BACKGROUND Lipid abnormalities (LA) are related to an increased risk for cardiovascular diseases in kidney transplantation patients. PATIENTS AND METHODS Multivariable logistic regression models were used to estimate the risk of LA associated with potential risk factors, including immunosuppressant use, patient background characteristics, and laboratory data. RESULTS In total, 386 patients who were undergoing kidney transplantation were included in the study. Statins were prescribed to 43% of patients. The LA composite outcome was defined as statin use and/or low density lipoprotein cholesterol level ≥120 mg/dL, and 229 patients (59.3%) developed LA as a result. LA was significantly related to everolimus, corticosteroid, age, and estimated glomerular filtration ratio in the multiple logistic regression analysis. The odds ratios were 2.264, 3.119, 1.186, and 0.870, respectively. Mycophenolate mofetil, mizoribine, azathioprine, cyclosporine (CYA), tacrolimus, proteinuria, body mass index, and male sex were not related to LA. DISCUSSION CYA influenced lipid metabolism but was not related to LA in our study. The mean post transplantation period was 8.4 years, and the CYA dose decreased over time. The CYA blood concentration was 70.0 ng/mL, which is relatively low, but it decreased the susceptibility to LA. Serum lipid levels were well controlled by statins, and the estimated glomerular filtration rate was maintained stably. CONCLUSIONS Everolimus and corticosteroid use, as well as a lower estimated glomerular filtration rate and higher age, were significant risk factors for LA. CYA is known for its adverse LA effects, but it was not a significant risk factor for LA in patients undergoing maintenance phase kidney transplantation.

Early diagnosis and treatment of breast cancer in Japanese kidney transplant recipients: a single center experience

BackgroundThe incidence of malignancies in kidney transplant recipients is increasing. Breast cancer is a common malignancy after kidney transplantation and can be more aggressive in kidney transplant recipients than in the general population. In this study, we evaluated the incidence and prognosis of breast cancer in kidney transplant recipients.FindingsBetween 1993 and 2013, 750 kidney transplant patients were followed-up at our center. Since 1999, annual physical examination, mammography, and breast ultrasonography have been performed for such patients. Diagnostic studies, including core needle or mammotome biopsy, were performed for suspected malignancies. Patients with malignant neoplasm were administered the appropriate treatment and followed-up to assess tumor response and symptoms.Nine patients were diagnosed with breast cancer during the follow-up period. The mean age at the initial detection of the breast cancer was 47.7 ± 8.4 years. The mean interval from transplantation to diagnosis was 148.7 ± 37.1 months. Of the 9 patients, 8 were detected through the screening test; 7 were treated with breast conservative surgery and 1 was treated with modified radical mastectomy. The cancer stages were 0 (n = 2), I (n = 6), and II (n = 1). The incidence of breast cancer tended to be unchanged with time between transplantation and diagnosis, inconsistent with the increase in the duration of immunosuppression.ConclusionAnnual screening tests are crucial in the early diagnosis of breast cancer. Early treatment of breast cancer can result in an excellent prognosis in kidney transplant recipients.

The impact on graft survival of interstitial inflammation in borderline change of allograft kidneys.

In kidney transplantation cases, borderline change (BL) can lead to a progressive course. However, factors related to outcome and the progress of BL are not well defined. In this study, we focused specifically on interstitial inflammation as a factor influencing outcome after diagnosis of BL.