Daiki Iwami

Purified Eicosapentaenoic Acid Induces Prolonged Survival of Cardiac Allografts and Generates Regulatory T Cells

Fish oil, which is rich in eicosapentaenoic acid (EPA), has been found to have immunomodulatory effects. We examined whether administration of purified EPA affected survival of fully mismatched murine cardiac allografts. Hearts from C57BL/10 (H‐2b) mice were transplanted into CBA (H‐2k) recipients treated with one intraperitoneal dose of purified EPA the day of transplantation. Untreated CBA recipients and recipients given 0.1 g/kg of EPA rejected C57BL/10 hearts (median survival time [MST], 8 and 13 days, respectively). With a 1.0 g/kg dose of EPA, graft survival was markedly prolonged (MST >100 days). To determine whether regulatory cells were generated, naïve mice (secondary recipients) underwent adoptive transfer of splenocytes from EPA‐treated primary recipients and cardiac allograft transplantation. Adoptive transfer of whole, CD4+ and CD4+CD25+ splenocytes from EPA‐treated recipients induced indefinite survival in secondary recipients. Flow cytometry showed that the CD4+CD25+ cells were Foxp3+. In reverse transcriptase‐polymerase chain reaction (RT‐PCR) studies, the expression of peroxisome proliferator‐activated receptor γ (PPARγ) mRNA was upregulated by EPA treatment. A PPARγ antagonist abrogated the prolongation of graft survival induced by EPA treatment (MST, 13 days). Thus, in our model, purified EPA induced prolonged survival of fully mismatched cardiac allografts and generated regulatory T cells dependent on PPARγ activation.

Immunomodulatory effects of eicosapentaenoic acid through induction of regulatory T cells

Dietary intake of omega-3 polyunsaturated fatty acids (PUFAs) has been found to affect inflammation and metabolism, and many researchers have shown that omega-3 PUFAs provide benefits in immunologic and metabolic disorders. These effects were assumed to result mainly from a modification in the production of inflammatory mediators and the suppression of inflammatory leukocytes. Among PUFAs, eicosapentaenoic acid (EPA), a component of fish oil, apparently has the most potent effect. Recently, much research has focused on regulatory T cells (Tregs) as controllers of immune responses not only to self-antigens but also to non-self-antigens, including donor alloantigens. Therefore, induction of antigen-specific Tregs may be an attractive strategy for managing autoimmune diseases and transplant rejection. Peroxisome proliferator-activated receptor γ (PPARγ), a ligand-activated nuclear receptor that regulates lipid and glucose metabolism, can be activated by thiazolidinediones, fatty acids, and eicosanoids, including EPA. PPARγ was recently found to have immunoregulatory effects, and a PPARγ agonist inhibited immune responses in a rat model of autoimmune disease. Furthermore, in a murine model, one high dose of purified EPA given the day of transplantation induced marked prolongation of cardiac allograft survival in a dose-dependent manner. These findings suggest that EPA induced Tregs by means of a PPARγ-dependent mechanism. This review describes the immunomodulatory effects of PUFAs, especially EPA, and summarizes recent research that may have implications for the development of therapies for autoimmune diseases and transplant rejection that are based on induction of Tregs.

Induction of regulatory T cells and indefinite survival of fully allogeneic cardiac grafts by ursodeoxycholic acid in mice.

Background. Ursodeoxycholic acid (UDCA) has been used to treat patients with cholestatic and autoimmune liver diseases. Several studies have addressed whether UDCA can inhibit graft rejection in experimental and clinical transplantation, but the results have varied. We investigated the effect of UDCA and the mechanism of its effect on alloimmune responses in a murine model of cardiac transplantation. Methods. CBA mice underwent transplantation of a C57BL/10 heart and received a single dose of UDCA. Survival times of the allografts were recorded. An adoptive transfer study was conducted to determine whether regulatory cells were generated. The effects on graft survival of adding FK506 or cyclosporine A (CyA) to UDCA treatment were assessed. Histologic, cell proliferation, and cytokine assessments were performed. Results. CBA recipients given UDCA (25 mg/kg) had indefinite allograft survival (median survival time [MST], >100 days). UDCA also suppressed proliferation of splenocytes and production of interleukin (IL)-2, IL-6, and interferon-γ, and up-regulated IL-10 production. Adoptive transfer of either whole splenocytes or CD4+ cells from UDCA-treated allograft recipients resulted in indefinite survival of allografts in naive secondary recipients (MST, >100 days). Adoptive transfer of CD4+CD25+ cells from UDCA-treated recipients significantly prolonged allograft survival in naive secondary recipients (MST, >80 days). FK506 (0.1 mg/kg/day) was compatible with the induction of indefinite allograft survival by UDCA, whereas CyA (10 mg/kg/day) abrogated the effect of UDCA. Conclusion. UDCA induced unresponsiveness to fully allogeneic cardiac allografts and generated CD4+CD25+ regulatory cells in our model. FK506, but not CyA, was compatible with UDCA treatment.

Long-term outcome of single institutional experience with conservative and surgical management for renal artery aneurysm.

BACKGROUND Spontaneous rupture risk of a renal artery aneurysm (RAA) is extremely low. Indications for surgical repair of RAA remain uncertain. OBJECTIVE Long-term outcomes of conservative therapy and surgical repair were evaluated. PATIENTS The study included 58 patients (17 males, 41 females) who were diagnosed with RAA during the last 21 years. Median age at the time of diagnosis was 62 (19-85) years, and the median follow-up 69 months (range 3-216). METHODS The patients were divided into two groups, conservative group (n = 30) who had been followed with blood pressure control, and treatment group (n = 29), who underwent an intervention. RESULTS Multiple efferent aneurysmal branches were observed in seven conservative and 16 treatment cases (P = .002). The median maximum diameter of the aneurysm was lower in the conservative than the treatment group (15 versus 25 mm, P = .005). Two conservative group cases showed increases in aneurysm size during follow-up. The hypertensive state showed essentially no change in either group during the follow-up. Renal function decreased with age similarly both in conservative and treatment groups. CONCLUSIONS Our conservative management criteria for RAA are justifiable and even too strict.

Pediatric kidney transplantation is safe and available for patients with urological anomalies as well as those with primary renal diseases

Abstract:  The aim of the current study was to evaluate long‐term outcomes of pediatric live kidney transplantation in patients with genitourinary anomalies relative to those with primary kidney diseases. The study included 35 pediatric patients who received a live kidney transplantation during the last 25 yr (28 males, six females). Median age at the time of transplantation was nine yr (range 1–15 yr), and the median follow‐up period was 151 months (range 6–239 month). The patients were divided into two groups. The urological group (n = 14) included patients with primary obstructive/reflux nephropathy. The renal group (n = 20) included patients with primary renal disorders. Differences between groups in graft survival, clinical course, and final graft function were evaluated. Original diseases represented in the urological group included five cases with primary VUR and eight cases with secondary VUR. Diseases in the renal group included eight cases with bilateral hypo‐dysplastic kidney, three cases with focal/segmental glomerular sclerosis, two cases with membranous proliferative glomerulonephritis, two cases with congenital nephrotic syndrome and five cases with other forms of chronic nephritis. Ten of 14 cases in the urological group, relative to six of 20 in the renal group, were preemptive. Median age at transplantation was 7.5 or 10 yr old, respectively, in the urological or renal group. Twelve kidney recipients in the urological group had also undergone other urinary surgeries, including upper urinary tract drainage, ureteroneocystostomy, augmentation cystoplasty, endoscopic incision of posterior‐urethral valve, urethroplasty, etc. Cumulative post‐operative complications occurred in nine or 16, respectively, in the urological or renal group. The acute rejection free and overall graft survival were similar in both groups. One patient in the urological group lost his graft while six patients in the renal group lost their grafts. Thus, the post‐transplant clinical outcome of pediatric transplantation in patients with urological anomalies is comparable to that of recipients with primary renal disease. Appropriate urinary tract reconstruction and management is essential to reduce the risk of graft dysfunction because of urinary problems.

Interleukin-10 From Marginal Zone Precursor B-Cell Subset Is Required for Costimulatory Blockade-Induced Transplantation Tolerance.

Background Blocking CD40-CD40L costimulatory signals induces transplantation tolerance. Although B-cell depletion prevents alloantibody formation, nonhumoral functions of B cells in tolerance have not been well characterized. We investigated whether specific subsets of B cell or B cell–derived interleukin (IL)-10 contribute to tolerance. Methods Wild type C57BL/6, or B cell–specific interleukin (IL)-10−/− (CD19-Cre+/−::IL-10fl/fl) mice, received vascularized BALB/c cardiac allografts. BALB/c donor-specific splenocyte transfusion and anti-CD40L monoclonal antibody were used as tolerogen. B cells were depleted with antimouse CD20 monoclonal antibody. Various B-cell subsets were purified and characterized by flow cytometry, reverse transcription polymerase chain reaction, and adoptive transfer. Results B-cell depletion prevented costimulatory blockade-induced allogeneic tolerance. Costimulatory blockade increased IL-10 in marginal zone precursor (MZP) B cells, but not other subsets. In particular, costimulatory blockade did not change other previously defined regulatory B-cell subsets (Breg), including CD5+CD1dhi Breg or expression of TIM1 or TIM4 on these Breg or other Breg cell subsets. Costimulatory blockade also induced IL-21R expression in MZP B cells, and IL-21R+ MZP B cells expressed even more IL-10. B-cell depletion or IL-10 deficiency in B cells prevented tolerance in a cardiac allograft model, resulting in rapid acute cardiac allograft rejection. Adoptive transfer of wild type MZP B cells but not other subsets to B cell–specific IL-10 deficient mice prevented graft rejection. Conclusions CD40 costimulatory blockade induces MZP B cell IL-10 which is necessary for tolerance. These observations have implications for understanding tolerance induction and how B cell depletion may prevent tolerance.

Successful kidney transplantation ameliorates arterial stiffness in end-stage renal disease patients.

PURPOSE Successful kidney transplantation (KTx) can ameliorate bodily damage caused by end-stage renal disease (ESRD). Arterial stiffness (AS) is one of the critical factors that shorten the survival of patients due to cardiovascular events. KTx may reduce AS as well; however, this has not been investigated well. We therefore conducted a retrospective study using noninvasive pulse wave velocity (PWV), which is a useful index of aortic damage. PATIENTS AND METHODS Fifty-eight consecutive kidney recipients (34 men, 24 women) were enrolled in this study. Mean age at transplantation was 40.5 ± 12.3 years and the dialysis period was 73.1 ± 95.8 months. The brachial-ankle PWV was measured preoperatively and 6 months postoperatively. First, we investigated the relationship between the PWV and the other parameters related to AS. Second, we studied the pre- to posttransplant change in PWV to evaluate the amelioration of AS after successful KTx. RESULTS PWV showed significant positive correlations with age, systolic blood pressure (BP), diastolic BP, and abdominal aortic calcification index. After successful KTx, PWV significantly decreased (P < .01). In addition, systolic and diastolic BP significantly decreased (P < .01 and P < .05, respectively). CONCLUSION Successful KTx ameliorates AS in ESRD patients. This might explain the improved cardiovascular prognosis of ESRD patients who undergo KTx.

Induction of regulatory T cells and prolongation of survival of fully allogeneic cardiac grafts by administration of Tokishakuyaku-san in mice

BACKGROUND The Japanese herbal medicine Tokishakuyaku-san (TJ-23) has been used to treat neurodegenerative, immune, and respiratory tract diseases, as well as many gynecologic disorders, with few adverse effects. This study investigated the effect of TJ-23 on alloimmune responses in a murine model of cardiac allograft transplantation. METHODS CBA mice underwent transplantation of a C57BL/6 heart and received oral administration of 2 g/kg per day of TJ-23 or 1 of 16 other commonly used Japanese herbal medicines from the day of transplantation until 7 days afterward. An adoptive transfer study was conducted to determine whether regulatory cells were generated. Histologic and cell proliferation studies, cytokine measurements, and flow cytometry analyses were also performed. RESULTS Of the 17 herbal medicines studied, only TJ-23, given in a dose of 2 g/kg per day, induced significantly prolonged allograft survival (median survival time [MST], >100 days). TJ-23 also suppressed proliferation of splenocytes and production of interleukin-2, interleukin-6, and interferon-γ. Adoptive transfer of either whole splenocytes or CD4(+) or CD4(+) CD25(+) cells from TJ-23-treated allograft recipients resulted in indefinite survival of allografts in naive secondary recipients (MST >100 days). Flow cytometry studies showed that the CD4(+) CD25(+) forkhead/winged-helix (FOXP3)(+) regulatory cell population was increased in transplant recipients given TJ-23. CONCLUSION TJ-23 induced hyporesponsiveness to fully allogeneic cardiac allografts and generated CD4(+) CD25(+) regulatory cells in our model.

Quadruple immunosuppression with basiliximab, tacrolimus, mycophenolate mofetil and prednisone is safe and effective for renal transplantation

Abstract:  Introduction:  Recent immunosuppression with tacrolimus and mycophenolate mofetil has improved the results of renal transplantation. In this study, we analyzed the effect and safety of basiliximab as an induction therapy.

Vascular endothelial growth factor c/vascular endothelial growth factor receptor 3 signaling regulates chemokine gradients and lymphocyte migration from tissues to lymphatics.

Background Circulation of leukocytes via blood, tissue and lymph is integral to adaptive immunity. Afferent lymphatics form CCL21 gradients to guide dendritic cells and T cells to lymphatics and then to draining lymph nodes (dLN). Vascular endothelial growth factor C and vascular endothelial growth factor receptor 3 (VEGFR-3) are the major lymphatic growth factor and receptor. We hypothesized these molecules also regulate chemokine gradients and lymphatic migration. Methods CD4+ T cells were injected into the foot pad or ear pinnae, and migration to afferent lymphatics and dLN quantified by flow cytometry or whole mount immunohistochemistry. Vascular endothelial growth factor receptor 3 or its signaling or downstream actions were modified with blocking monoclonal antibodies (mAbs) or other reagents. Results Anti–VEGFR-3 prevented migration of CD4+ T cells into lymphatic lumen and significantly decreased the number that migrated to dLN. Anti–VEGFR-3 abolished CCL21 gradients around lymphatics, although CCL21 production was not inhibited. Heparan sulfate (HS), critical to establish CCL21 gradients, was down-regulated around lymphatics by anti–VEGFR-3 and this was dependent on heparanase-mediated degradation. Moreover, a Phosphoinositide 3-kinase (PI3K)&agr; inhibitor disrupted HS and CCL21 gradients, whereas a PI3K activator prevented the effects of anti–VEGFR-3. During contact hypersensitivity, VEGFR-3, CCL21, and HS expression were all attenuated, and anti-heparanase or PI3K activator reversed these effects. Conclusions Vascular endothelial growth factor C/VEGFR-3 signaling through PI3K&agr; regulates the activity of heparanase, which modifies HS and CCL21 gradients around lymphatics. The functional and physical linkages of these molecules regulate lymphatic migration from tissues to dLN. These represent new therapeutic targets to influence immunity and inflammation.