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Introduction: Macrophages and monocytes are main players in innate immunity. The relevance of mononuclear phagocyte infiltrates on clinical outcomes remains to be determined in native kidney diseases., Methods: Our cross-sectional study included 324 patients with diagnostic renal biopsies comprising 17 disease entities and normal renal tissues for comparison. All samples were stained for CD68 + macrophages. Selected groups were further subtyped for CD14 + monocytes and CD163 + alternatively activated macrophages. Using precise pixel-based digital measurements, we quantified cell densities as positively stained areas in renal cortex and medulla as well as whole renal tissue. Laboratory and clinical data of all cases at the time of biopsy and additional follow-up data in 158 cases were accessible., Results: Biopsies with renal disease consistently revealed higher CD68 + -macrophage densities and CD163 + -macrophage densities in cortex and medulla compared to controls. High macrophage densities correlated with impaired renal function at biopsy and at follow-up in all diseases and in diseases analyzed separately. High cortical CD68 + -macrophage densities preceded shorter renal survival, defined as requirement of permanent dialysis. CD14 + monocyte densities showed no difference compared to controls and did not correlate with renal function., Conclusion: Precise quantification of macrophage densities in renal biopsies may contribute to risk stratification to identify patients with high risk for end-stage renal disease (ESRD) and might be a promising therapeutic target in renal disease., (© 2022 Published by Elsevier Inc. on behalf of the International Society of Nephrology.)

Background: Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment., Methods: The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232., Findings: The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT., Interpretation: Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression., Funding: The 7th EU Framework Programme., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Transplantation is invariably associated with ischemia-reperfusion injury (IRI), inflammation and rejection. Resultant cell death has morphological features of necrosis but programmed cell death has been synonymous with apoptosis until pathways of regulated necrosis (RN) have been described. The best-studied RN pathway, necroptosis, is triggered by perturbation of caspase-8-mediated apoptosis and depends on receptor-interacting protein kinases 1 and 3 (RIPK1/RIPK3) as well as mixed linage kinase domain like to form the necroptosome. The release of cytosolic content and cell death-associated molecular patterns (CDAMPs) can trigger innate and promote adaptive immune responses. Thus, the form of cell death can substantially influence alloimmunity and graft survival. Necroptosis is a key element of IRI, and RIPK1 interference by RN-specific inhibitors such as necrostatin-1 protects from IRI in kidney, heart and brain. Necroptosis may be a general mechanism in response to other forms of inflammatory organ injury, and will likely emerge as a promising target in solid organ transplantation. As second-generation RIPK1 and RIPK3 inhibitors become available, clinical trials for the prevention of delayed graft function and attenuation of allograft rejection-mediated injury will emerge. These efforts will accelerate upon further identification of critical necroptosis-triggering receptor(s)., (© Copyright 2013 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Loss of kidney function in renal ischemia/reperfusion injury is due to programmed cell death, but the contribution of necroptosis, a newly discovered form of programmed necrosis, has not been evaluated. Here, we identified the presence of death receptor-mediated but caspase-independent cell death in murine tubular cells and characterized it as necroptosis by the addition of necrostatin-1, a highly specific receptor-interacting protein kinase 1 inhibitor. The detection of receptor-interacting protein kinase 1 and 3 in whole-kidney lysates and freshly isolated murine proximal tubules led us to investigate the contribution of necroptosis in a mouse model of renal ischemia/reperfusion injury. Treatment with necrostatin-1 reduced organ damage and renal failure, even when administered after reperfusion, resulting in a significant survival benefit in a model of lethal renal ischemia/reperfusion injury. Unexpectedly, specific blockade of apoptosis by zVAD, a pan-caspase inhibitor, did not prevent the organ damage or the increase in urea and creatinine in vivo in renal ischemia/reperfusion injury. Thus, necroptosis is present and has functional relevance in the pathophysiological course of ischemic kidney injury and shows the predominance of necroptosis over apoptosis in this setting. Necrostatin-1 may have therapeutic potential to prevent and treat renal ischemia/reperfusion injury.

Cisplatin, a standard chemotherapeutic agent for many tumors, has an unfortunately common toxicity where almost a third of patients develop renal dysfunction after a single dose. Acute kidney injury caused by cisplatin depends on Fas-mediated apoptosis driven by Fas ligand (FasL) expressed on tubular epithelial and infiltrating immune cells. Since the role of FasL in T cells is known, we investigated whether its presence in primary kidney cells is needed for its toxic effect. We found that all cisplatin-treated wild-type (wt) mice died within 6 days; however, severe combined immunodeficiency (SCID)/beige mice (B-, T-, and natural killer-cell-deficient) displayed a significant survival benefit, with only 55% mortality while exhibiting significant renal failure. Treating SCID/beige mice with MFL3, a FasL-blocking monoclonal antibody, completely restored survival after an otherwise lethal cisplatin dose, suggesting another source of FasL besides immune cells. Freshly isolated primary tubule segments from wt mice were co-incubated with thick ascending limb (TAL) segments freshly isolated from mice expressing the green fluorescent protein (GFP) transgene (same genetic background) to determine whether FasL-mediated killing of tubular cells is an autocrine or paracrine mechanism. Cisplatin-stimulated primary segments induced apoptosis in the GFP-tagged TAL cells, an effect blocked by MFL3. Thus, our study shows that cisplatin-induced nephropathy is mediated through FasL, functionally expressed on tubular cells that are capable of inducing death of cells of adjacent tubules.

FTY720 is a novel immunomodulator being investigated for rejection prophylaxis in renal transplantation when combined with full-dose cyclosporine (CsA; FDC). This 1-year phase II study compared FTY720 plus FDC (Neoral) with FTY720 plus reduced-dose CsA (RDC) and mycophenolate mofetil (MMF) plus FDC in de novo renal transplant patients. Patients were randomized 2:2:2:1 to FTY720 5 mg plus RDC (n = 72); FTY720 2.5 mg plus RDC (n = 74); FTY720 2.5 mg plus FDC (n = 76); or MMF plus FDC (n = 39) for 12 months. CsA exposure in the RDC group was reduced on average by 50% as assessed by C(2) monitoring. The primary efficacy endpoint was the composite incidence of biopsy-proven acute rejection (BPAR), graft loss, death or premature study discontinuation. The incidences for this composite endpoint were 24% and 22%, respectively, for FTY720 5 mg plus RDC and FTY720 2.5 mg plus FDC versus 39% for MMF plus FDC. Patients receiving FTY720 2.5 mg plus RDC were discontinued from treatment due to risk of under-immunosuppression. FTY720 2.5 mg plus FDC and FTY720 5 mg plus RDC were safe and effective in de novo renal transplant patients over 12 months.

Short- and long-term rates of success after cadaveric kidney transplantation are significantly inferior to those from living related or unrelated donors. The major difference between cadaveric and living donation is brain death. In the present study we analyzed the influence of duration of brain death on short- and long-term graft function after cadaveric kidney transplantation. The interval between declaration of donor brain death and the beginning of the cold ischemia time before graft explantation was defined as duration of brain death (DBD). The influence of DBD on incidence of primary graft function and on duration of delayed kidney graft function as well as on kidney graft survival was analyzed in 1106 patients transplanted in one center and confirmed in a validation study of a second series of 752 kidney graft recipients from another transplant center. Kidney grafts harvested from donors with longer DBD (>470 min) exhibited a significantly higher incidence of primary graft function and a significantly better graft survival rate in comparison to kidneys from donors with a shorter DBD (<470 min). The tendency of these results could be confirmed in an independent validation study; however, the differences were not statistically significant. Although the dramatic hemodynamic and immunological changes in brain-dead donors may impair the quality of a potential kidney transplant, a longer duration of donor brain death did not deteriorate early and long-term kidney graft function.