[Show abstract][Hide abstract] ABSTRACT: Although many relevant immune reactions are initiated in the lymph nodes, this compartment has not been systematically studied
in humans. Analyses have been performed on immune cells derived from tonsils, but as this tissue is most often inflamed, generalization
of these data is difficult. Here, we analyzed the phenotype and function of the human CD4+ T-cell subsets and lineages in paired resting lymph node and peripheral blood samples. Naive, central memory cells and effector
memory cells as well as Th1, Th2, Th17 and Treg cells were equally represented in both compartments. On the other hand, cytotoxic CD4+ T cells were strikingly absent in the lymph nodes. CXCR5+CD4+ T cells, representing putative follicular Th (Tfh) cells were over-represented in lymph nodes and expressed higher levels of Tfh markers than their peripheral blood counterparts.
Compared with the circulating pool, lymph-node-derived CXCR5+CD4+ T cells were superior in providing help to B cells. Thus, functionally competent Tfh cells accumulate in resting human lymph
nodes, providing a swift induction of naive and memory antibody responses upon antigenic challenge.
Full-text · Article · Nov 2013 · International Immunology
[Show abstract][Hide abstract] ABSTRACT: Background:
Postoperative surgical site infection (SSI) can be considered a frequent complication of hand-assisted laparoscopic donor nephrectomy (HALDN). Since 2007, our center used routinely a gentamicin-containing collagen sponge (GCCS) when closing the wound. The effect of GCCS on SSI is not elucidated clearly. In this retrospective cohort study, we assessed the effects of GCCS on SSI after HALDN.
Between December 2004 and November 2007, we treated 100 patients without GCCS, and from November 2007 to July 2010, there were 100 patients with GCCS placed after HALDN. A SSI was defined as an incisional infection that required an intervention such as opening of the site or antibiotic treatment within 90 days after surgery.
Implantation of a GCCS resulted in a statistically significant reduction in the SSI rate, from 6% to 0 (p=0.01). All infections occurred in the Pfannenstiel incision site. There was no significant difference between the groups in the creatinine concentration after three months.
The use of gentamicin-containing collagen sponges reduces the risk of SSI significantly after HALDN without compromising kidney function.
No preview · Article · Aug 2013 · Surgical Infections
[Show abstract][Hide abstract] ABSTRACT: Background:
Whether or not to remove a failed renal graft has been the subject of much debate. One reason for a cautious approach to graft removal is its high morbidity and mortality rates. We analyzed the morbidity, mortality, and risk factors of transplant nephrectomy at our center.
Material and methods:
We included 157 cases of transplant nephrectomy in 143 patients, performed between January 2000 and May 2012 at the Academic Medical Center, Amsterdam. Patient data were collected retrospectively.
A total of 32 surgical complications occurred after transplant nephrectomy (20%) and 16 patients needed surgical re-intervention (10%). Hemorrhage and infection are the most frequent causes of surgical complications (14%). The mortality rate was 3.2%. There were no significant differences in characteristics and timing of transplant nephrectomy between the group with surgical complications and the group without. A total of 59 re-transplantations were performed in 57 patients (38%).
Transplant nephrectomy is associated with high morbidity and mortality rates. We found no significant risk factors for surgical complications following transplant nephrectomy and no significant association between timing of transplant nephrectomy and surgical complications. Steps to reduce these complications need further investigation.
[Show abstract][Hide abstract] ABSTRACT: Background:
In renal transplant recipients, mammalian target of rapamycin (mTOR) inhibitors have been reported to protect against cytomegalovirus (CMV) disease. Here, we questioned whether mTOR inhibitors specifically influence human CMV-induced T-cell responses.
We studied renal transplant recipients treated with prednisolone, cyclosporine A (CsA), and mycophenolate sodium (MPS) for the first 6 months after transplantation followed by double therapy consisting of prednisolone/everolimus, which is an mTOR inhibitor (P/EVL; n=10), prednisolone/CsA (P/CsA; n=7), or prednisolone/MPS (P/MPS; n=9). All patients were CMV-IgG positive before transplantation. CMV reactivation was detectable in the first 6 months after transplantation and not thereafter. None of the patients included in this study suffered from CMV disease. Both CD27CD8 and CD27CD28CD4 effector-type T-cell counts, known to be associated with CMV infection, were measured before transplantation and at 6 and 24 months after transplantation. Additionally, we determined both number and function of CMV-specific CD8 T cells at these time points.
The number of total CD8 T cells, CD27CD8 T cells, and CD28CD4 T cells increased significantly after switch to therapy with P/EVL but not after switch to P/CsA or P/MPS. Specifically, CMV-specific CD8 T-cell counts significantly increased after switch to therapy with P/EVL. Furthermore, the mTOR inhibitor sirolimus strongly inhibited alloresponses in vitro, whereas it did not affect CMV-specific responses.
We observed a significant increase in (CMV-specific) effector-type CD8 and CD4 T-cell counts in everolimus-treated patients. These findings may at least in part explain the reported low incidence of CMV-related pathology in everolimus-treated patients.
[Show abstract][Hide abstract] ABSTRACT: Viral infection in the kidney is characterized by tubular injury induced directly by the virus and/or by cytotoxic lymphocytes. Previously, we found that human tubular epithelial cells express Toll-like receptor 3 (TLR3), melanoma differentiation-associated gene 5 (MDA5), and retinoic acid-inducible gene-I (RIG-I), all sensors of double-stranded RNA (dsRNA) and potent inducers of antiviral activity. Here, we demonstrate increased expression of these three dsRNA sensors in kidney transplant biopsies during cytomegalovirus or BK virus infection. In primary tubular epithelial cells, dsRNA sensor activation induced the production of pro-inflammatory TNF-α and antiviral IFN-β. Notably, dsRNA also enhanced the expression of pro-apoptotic proteins; however, dsRNA alone did not cause cell death due to the expression of anti-apoptotic proteins. The dsRNA sensitized tubular epithelial cells to apoptosis induced by an agonistic antibody against the Fas receptor (CD95), an apoptotic pathway that eliminates infected cells. These findings indicate that tubular epithelial cells require at least two signals to undergo apoptosis, which can help preserve tubular integrity even under inflammatory conditions. Thus, sensors of viral dsRNA promote antiviral, pro-inflammatory, and pro-apoptotic responses in tubular epithelial cells, which may orchestrate the control of viral infection in the kidney.Kidney International advance online publication, 30 May 2012; doi:10.1038/ki.2012.206.
Full-text · Article · May 2012 · Kidney International
[Show abstract][Hide abstract] ABSTRACT: Phenotypic characterization of T and B lymphocytes allows the discrimination of functionally different subsets. Here, we questioned whether changes in peripheral lymphocyte subset distribution reflect specific clinical and histopathological entities after renal transplantation. Sixty-five renal transplant recipients with either histologically proven (sub)clinical acute rejection or chronic allograft dysfunction, or without abnormalities were studied for their peripheral lymphocyte subset composition and compared with 15 healthy control individuals. Naive, memory and effector CD8(+) T-cell counts were measured by staining for CD27, CD28 and CD45RO/RA. In addition, we studied the CD25(+) CD4(+) T-cell population for its composition regarding regulatory Foxp3(+) CD45RO(+) CD127(-) cells and activated CD45RO(+) CD127(+) cells. Naive, non-switched and switched memory B cells were defined by staining for IgD and CD27. We found a severe decrease in circulating effector-type CD8(+) T cells in recipients with chronic allograft dysfunction at 5 years after transplantation. Percentages of circulating CD25(+) CD127(low) CD4(+) regulatory T cells after transplantation were reduced, but we could not detect any change in the percentage of CD127(+) CD45RO(+) CD4(+) activated T cells in patients at any time or condition after renal transplantation. Regardless of clinical events, all renal transplant recipients showed decreased total B-cell counts and a more differentiated circulating B-cell pool than healthy individuals. The changes in lymphocyte subset distribution probably reflect the chronic antigenic stimulation that occurs in these transplant recipients. To determine the usefulness of lymphocyte subset-typing in clinical practice, large cohort studies are necessary.
[Show abstract][Hide abstract] ABSTRACT: Interleukin-17 (IL-17) plays an important role in the regulation of cellular and humoral immune responses. Recent studies suggest a role for IL-17 in transplantation. Our study investigated whether quantifying IL-17+ cells in renal transplant biopsies during acute rejection could have additional prognostic value for better stratifying patients at risk for nonresponsiveness to anti-rejection therapy and future graft dysfunction. Forty-nine renal biopsies with acute rejection were double immunostained and quantitatively analyzed for IL-17 and CD3 (IL-17+ T-lymphocytes), tryptase (IL-17+ mast cells) or CD15 (IL-17+ neutrophils). Total IL-17+ cell count correlated with total percentage of inflamed biopsy and estimated GFR during rejection. Most IL-17+ cells were mast cells and neutrophils. We could hardly find any IL-17+ T-lymphocytes. IL-17+ mast cells correlated with interstitial fibrosis/tubular atrophy (IF/TA). None of the IL-17+ cell counts had an additional prognostic value for response to anti-rejection treatment. Multivariate analysis correcting for C4d positivity and time from transplantation to biopsy showed that total IL-17+ cell count independently predicts graft dysfunction at the last follow-up, which was validated in an independent cohort of 48 renal biopsies with acute rejection. We conclude that intragraft IL-17+ cell count during acute allograft rejection could have an additional value for predicting late graft dysfunction.
Full-text · Article · Jul 2011 · Transplant International
[Show abstract][Hide abstract] ABSTRACT: Pneumocystis jiroveci pneumonia (PCP) is an important cause of morbidity and mortality in renal transplant recipients (RTRs). Chemoprophylaxis with trimethoprim/sulphamethoxazole is recommended during the early post-transplantation period, but the optimal duration has not been determined and a main drawback of chemoprophylaxis is the development of resistance of the commensal faecal flora. A cluster outbreak of PCP occurred in our outpatient Renal Transplant Unit. We aimed to investigate risk factors for PCP in RTRs to determine who should receive long-term chemoprophylaxis.
In a case-control study, we investigated common demographic variables and immunological parameters. Nine PCP cases diagnosed between August 2006 and April 2007 were matched with 18 control patients, who did not develop PCP, received their transplant in the same time-period and had a similar follow-up period with a comparable immunosuppressive drug regimen.
The median time from transplantation to PCP was 19 months. We observed no significant differences in gender, age, donor type or number of rejections. In PCP cases, the median lymphocyte count just before PCP diagnosis was 0.49 (0.26-0.68), which was significantly reduced compared to the control patients after a similar follow-up period (median 1.36, 0.59-3.04, P = 0.002). This lymphocytopaenia was chronic and existed in most patients already for many months. CD4(+) T-cell counts were also significantly reduced in the PCP cases. We found no difference in the Th1, Th2 and Th17 subsets between PCP cases and control patients.
Long-term prophylactic therapy for PCP may be indicated for RTR with persistent severe lymphocytopaenia.
No preview · Article · Mar 2011 · Nephrology Dialysis Transplantation
[Show abstract][Hide abstract] ABSTRACT: While the guidelines for vaccination in renal transplant recipients recommend the use of pneumococcal polysaccharide (PPS) and tetanus toxoid (TT), their efficacy in immunocompromised renal transplant recipients is not known. Here we tested the effect of everolimus on immune responses after vaccination by measuring the capacity of 36 stable renal transplant recipients to mount cellular and humoral responses after vaccination. Twelve patients in each treatment arm received immunosuppressive therapy consisting of prednisolone (P) plus cyclosporine (CsA), mycophenolate sodium (MPA), or everolimus. Patients were vaccinated with the T-cell-dependent antigens immunocyanin and TT, and the T-cell-independent PPS. Treatment with CsA partially inhibited and MPA completely abolished the capacity to mount a primary humoral response, whereas everolimus left this largely intact. Recall responses were inhibited by MPA only. All drug combinations inhibited cellular responses against TT. In patients treated with MPA, B-cell numbers were severely reduced. Thus, combined with P, treatment with MPA completely disturbed primary and secondary humoral responses. Everolimus or CsA allowed the boosting of T-cell-dependent and -independent secondary humoral responses. Treatment with everolimus allowed a primary response.
No preview · Article · Nov 2010 · Kidney International
[Show abstract][Hide abstract] ABSTRACT: The role of CD20+ B cells in renal allograft rejection has been reappreciated. Importantly, recent studies suggest a relation between CD20+ B cell aggregates and poorer clinical outcome. In the present study, we attempted to confirm these early reports in a tightly controlled patient population and to differentiate between scattered infiltrates and clusters of B cells.
Fifty-four biopsies from renal transplant recipients with acute rejection were immunostained for CD20, CD3, and C4d. All patients received similar immunosuppressive therapy. Response to therapy was defined as a decrease in serum creatinine level within 2 weeks to 125% or less of the value before the clinically diagnosed episode of allograft rejection. Late clinical outcome was defined in creatinine clearance between 8 and 12 months after the episode of acute rejection or in graft failure.
A significant correlation was observed between interstitial infiltrates of CD20+ cells and CD3+ cells (r=0.720, P<0.001) suggesting that if B-cell infiltrates are present during rejection, they occur with T-cell infiltrates in a concurrent fashion. In contrast to previous reports, no relation was found between the number of CD20+ cells, in aggregates or in a scattered interstitial pattern, and response to conventional therapy. Remarkably, CD3+T cell aggregates did predict a favorable renal outcome.