letter to the editor
complicated as this biomarker is expressed in patients with CKD in the absence of any kidney injury.5 Furthermore there is a negative correlation between serum NGAL concentration and kidney function.5,6 We believe that the variability in the ranges of our serum NGAL measurements reflects our recruitment of patients with a wide spectrum of baseline renal dysfunction. Finally, they asked us to provide a cutoff range for serum NGAL. Currently there is no established NGAL cutoff value for diagnosing AKI in patients with preexisting CKD.7 It would therefore be inappropriate to use any cutoff values in our study cohort and so we cannot categorize our patients using NGAL. 1.
2.
3.
4.
5.
6.
7.
Xue FS, Liu GP, Sun C et al. Assessing protective effect of remote ischemic preconditioning on acute kidney injury after coronary artery bypass graft surgery. Kidney Int 2015; 88: 1195. Gallagher S, Jones D, Kapur A et al. Remote ischemic preconditioning has a neutral effect on the incidence of kidney injury after coronary artery bypass graft surgery. Kidney Int 2015; 87: 473–481. De Santo L, Romano G, Della Corte A et al. Preoperative anemia in patients undergoing coronary artery bypass grafting predicts acute kidney injury. J Thorac Cardiovasc Surg 2009; 138: 965–970. Ng R, Chew S, Liu W et al. Identification of modifiable risk factors for acute kidney injury after coronary artery bypass graft surgery in an Asian population. J Thorac Cardiovasc Surg 2014; 147: 1356–1361. Bolignano D, Lacquaniti A, Coppolino G et al. Neutrophil gelatinaseassociated lipocalin reflects the severity of renal impairment in subjects affected by chronic kidney disease. Kidney Blood Press Res 2008; 31: 255–258. Xiang D, Zhang H, Bai J et al. Clinical application of neutrophil gelatinaseassociated lipocalin in the revised chronic kidney disease classification. Int J Clin Exp Pathol 2014; 7: 7172–7181. Haase-Fielitz A, Haase M, Devarajan P. Neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury: a critical evaluation of current status. Ann Clin Biochem 2014; 51: 335–351.
Sean M. Gallagher1,2,3, R. Andrew Archbold1,3, Dan A. Jones1,2,3, Andrew Wragg1,3, Rakesh Uppal2,3,4 and Muhammad M. Yaqoob2,3,5 1 Department of Cardiology, Barts Health NHS Trust, London, UK; 2William Harvey Research Institute, Queen Mary University, London, UK; 3NIHR Cardiovascular Biomedical Research Unit, London Chest Hospital, London, UK; 4Department of Cardiothoracic Surgery, Barts Health NHS Trust, London, UK and 5Department of Nephrology, Barts Health NHS Trust, London, UK Correspondence: Muhammad M. Yaqoob, Department of Translational Medicine and Therapeutics, William Harvey Research Institute, John Vane Building, Charterhouse Square, London EC1M 6BQ, UK. E-mail: [email protected]
Kidney International (2015) 88, 1195–1196; doi:10.1038/ki.2015.263
Cell-based immunosuppression in kidney transplantation: the value of non-human primate studies To the Editor: In their review, Hutchinson and Geissler1 present a well-argued case for testing immunoregulatory cellbased immunosuppression in early-phase (phase I/II) clinical
1196
trials in renal transplantation. Extensive rodent studies have documented the potential of innate and adaptive regulatory immune cells to prolong allograft survival and induce transplant tolerance. Limited reports have demonstrated the feasibility of delivering such regulatory cells in human hematopoietic stem cell or organ transplantation. The significant barriers faced when translating these approaches to the clinic can be addressed in outbred non-human primates (NHPs) that have immune systems and histories of immune exposures similar to humans. These models have allowed rigorous pre-clinical assessment of the most promising tolerogenic strategies2 (e.g., donor bone marrow-induced mixed chimerism3) that have been applied in clinical renal transplantation. Three recent NHP studies demonstrate the safety and efficacy of regulatory immune cell-based therapy in renal transplantation. Thus, ex-vivo expanded, donor antigenspecific regulatory T cells prolong major histocompatibility complex-mismatched kidney allograft survival in monkeys when combined with anti-thymocyte globulin and low-dose sirolimus.4 Renal transplant rejection can also be safely prevented in cyclosporine and cyclophosphamide-treated monkeys and donor-specific tolerance induced by a single post-transplant (day 13) infusion of anergic (regulatory) T cells.5 Furthermore, infusion of (donor-derived) regulatory dendritic cells to prospective renal allograft recipients a week before transplant, together with costimulation blockade and sirolimus, safely prolongs graft survival, without evidence of host sensitization.6 These NHP studies underscore the potential safety and efficacy of innate or adaptive regulatory immune cell therapy in robust pre-clinical models and provide additional justification for testing these cell products in phase I/II trials in kidney transplantation.
ACKNOWLEDGMENTS
The authors’ work is supported by National Institutes of Health (NIH) research grants as part of the NIH NHP Transplantation Tolerance Cooperative Study Group sponsored by the NIAID and NIDDK. 1.
Hutchinson JA, Geissler EK. Now or never? The case for cell-based immunosuppression in kidney transplantation. Kidney Int 2015; 87: 1116–1124. 2. Kean LS, Gangappa S, Pearson TC et al. Transplant tolerance in nonhuman primates: progress, current challenges and unmet needs. Am J Transplant 2006; 6: 884–893. 3. Kawai T, Cosimi AB, Sachs DH. Preclinical and clinical studies on the induction of renal allograft tolerance through transient mixed chimerism. Curr Opin Organ Transplant 2011; 16: 366–371. 4. Ma A, Qi S, Song L et al. Adoptive transfer of CD4+CD25+ regulatory cells combined with low-dose sirolimus and anti-thymocyte globulin delays acute rejection of renal allografts in Cynomolgus monkeys. Int Immunopharmacol 2011; 11: 618–629. 5. Bashuda H, Kimikawa M, Seino K et al. Renal allograft rejection is prevented by adoptive transfer of anergic T cells in nonhuman primates. J Clin Invest 2005; 115: 1896–1902. 6. Ezzelarab MB, Zahorchak AF, Lu L et al. Regulatory dendritic cell infusion prolongs kidney allograft survival in nonhuman primates. Am J Transplant 2013; 13: 1989–2005.
Kidney International (2015) 88, 1195–1199
letter to the editor
Mohamed B. Ezzelarab1, David K.C. Cooper1 and Angus W. Thomson1,2 1 Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA and 2 Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA Correspondence: Angus W. Thomson, Department of Surgery or Department of Immunology, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, W1540 BST, 200 Lothrop Street, Pittsburgh, Pennsylvania, USA. E-mail: [email protected]
Kidney International (2015) 88, 1196–1197; doi:10.1038/ki.2015.262
4.
Ezzelarab MB, Zahorchak AF, Lu L et al. Regulatory dendritic cell infusion prolongs kidney allograft survival in nonhuman primates. Am J Transplant 2013; 13: 1989–2005. 5. Salmikangas P, Flory E, Reinhardt J et al. Regulatory requirements for clinical trial and marketing authorisation application for cell-based medicinal products. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2010; 53: 24–29. 6. Pruss A, Garritsen H. Advanced therapy medicinal products - a multiple challenge. Transfus Med Hemother 2013; 40: 384–385. 7. Hutchinson JA, Geissler EK. Now or never? The case for cell-based immunosuppression in kidney transplantation. Kidney Int 2015; 87: 1116–1124.
James A. Hutchinson1 and Edward K. Geissler1 1
The Authors Reply: Ezzelrab and colleagues correctly assert that non-human primate (NHP) studies have increased confidence in the likely efficacy of immunoregulatory cellbased medicinal products (CBMPs) for organ transplantation.1 However, the value of large animal models in assessing CBMP safety remains uncertain for various reasons.2 Firstly, testing CBMPs of NHP origin provides no direct evidence about safety of human CBMPs. Extrapolating safety conclusions from NHP to human CBMPs requires that the two cell products are equivalent in every respect, not only primary pharmacodynamics. Accordingly, clinical experiences with closely-related human CBMPs may be a more reliable basis for judging the probable safety of new CBMPs. Secondly, unlike efficacy studies that aim to detect particular effects, which should be large and accrue to most recipients, safety studies must be powered to detect any adverse effects, which may be small or restricted to a subset of recipients. Consider the example of allosensitisation after deliberate alloantigen exposure: Assuming a sensitisation rate of ≤ 15%,3 excluding sensitisation in NHPs treated with donor-derived CBMPs would require 418 recipients per group. Such large NHP experiments are uncommon.4 Thirdly, European Law already mandates preclinical safety testing of CBMPs comparable to that of conventional pharmaceuticals,5 making compliance challenging for academic centers and small companies.6 Any new requirement for NHP studies would severely limit CBMP development. Fourthly, the European Parliament has recently declared to, ‘move towards the ultimate goal of phasing out the use of NHP in experiments’. Hence, while we greatly appreciate the importance NHP studies in evaluating therapeutic efficacy of CBMPs and confirming mechanismsof-action, we stand by our opinion that further animal studies are unlikely to advance CBMP safety in upcoming trials.7 1.
2.
3.
Ezzelrab MB, Cooper DKC, Thomson AW. Cell-based immunosuppression in kidney transplantation: the value of nonhuman primate studies. Kidney Int 2015; 88: 1196–1197. Broichhausen C, Riquelme P, Ahrens N et al. In question: the scientific value of preclinical safety pharmacology and toxicology studies with cell-based therapies. Molecular Therapy - Methods & Clinical Development 2014; 1: 14026. Flye MW, Burton K, Mohanakumar T et al. Donor-specific transfusions have long-term beneficial effects for human renal allografts. Transplantation 1995; 60: 1395–1401.
Kidney International (2015) 88, 1195–1199
Department of Surgery, Section of Experimental Surgery, University Hospital Regensburg, Regensburg, Germany Correspondence: Edward K. Geissler, Department of Surgery, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, Regensburg 93053, Germany. E-mail: [email protected] Kidney International (2015) 88, 1197; doi:10.1038/ki.2015.265
Circulating progranulin but not renal progranulin expression is increased in renal dysfunction To the Editor: With great interest we read the manuscript by Zhou et al.1 suggesting progranulin as a protective factor against renal dysfunction in a mouse model of renal ischemia/ reperfusion injury (IRI). The authors describe decreased renal progranulin expression, as well as increased serum progranulin levels, in mice with IRI as compared to controls.1 Interestingly, circulating progranulin was increased in humans with chronic kidney disease (CKD) and acute kidney injury (AKI) in two recent studies from our group.2,3 To further assess progranulin in renal disease, progranulin expression in kidneys and circulating levels were now investigated in animal models of CKD and AKI by analyzing stored samples of our previous studies.4,5 In 20-week-old eNOS− / − C57BLKS/J db/db mice (CKD model),4 mean ± SEM progranulin plasma concentrations were significantly higher (3914.8 ± 524.6 μg/l) as compared to C57BLKS/J controls (2771.7 ± 74.6 μg/l) (P = 0.038) (Figure 1a). Interestingly, renal progranulin expression was significantly downregulated in CKD-prone mice as compared to controls (P = 0.040) (Figure 1b). In 3-month-old rats undergoing bilateral nephrectomy (AKI model),5 progranulin plasma levels were increased 24 h post-surgery in AKI rats (844.5 ± 30.8 μg/l) as compared to sham-operated animals (512.4 ± 52.9 μg/l) (Po0.001) (Figure 1c). Taking our results and the interesting study by Zhou et al.1 into consideration, progranulin expression is reduced in IRI-AKI and CKD mice. However, circulating progranulin levels are consistently increased in human and rodent models of CKD/AKI. Thus, a local rather than systemic effect of progranulin contributes to improved renal function in IRI.1 Furthermore, increased circulating progranulin in CKD/AKI might be a compensatory mechanism to limit renal deterioration. 1197
complicated as this biomarker is expressed in patients with CKD in the absence of any kidney injury.5 Furthermore there is a negative correlation between serum NGAL concentration and kidney function.5,6 We believe that the variability in the ranges of our serum NGAL measurements reflects our recruitment of patients with a wide spectrum of baseline renal dysfunction. Finally, they asked us to provide a cutoff range for serum NGAL. Currently there is no established NGAL cutoff value for diagnosing AKI in patients with preexisting CKD.7 It would therefore be inappropriate to use any cutoff values in our study cohort and so we cannot categorize our patients using NGAL. 1.
2.
3.
4.
5.
6.
7.
Xue FS, Liu GP, Sun C et al. Assessing protective effect of remote ischemic preconditioning on acute kidney injury after coronary artery bypass graft surgery. Kidney Int 2015; 88: 1195. Gallagher S, Jones D, Kapur A et al. Remote ischemic preconditioning has a neutral effect on the incidence of kidney injury after coronary artery bypass graft surgery. Kidney Int 2015; 87: 473–481. De Santo L, Romano G, Della Corte A et al. Preoperative anemia in patients undergoing coronary artery bypass grafting predicts acute kidney injury. J Thorac Cardiovasc Surg 2009; 138: 965–970. Ng R, Chew S, Liu W et al. Identification of modifiable risk factors for acute kidney injury after coronary artery bypass graft surgery in an Asian population. J Thorac Cardiovasc Surg 2014; 147: 1356–1361. Bolignano D, Lacquaniti A, Coppolino G et al. Neutrophil gelatinaseassociated lipocalin reflects the severity of renal impairment in subjects affected by chronic kidney disease. Kidney Blood Press Res 2008; 31: 255–258. Xiang D, Zhang H, Bai J et al. Clinical application of neutrophil gelatinaseassociated lipocalin in the revised chronic kidney disease classification. Int J Clin Exp Pathol 2014; 7: 7172–7181. Haase-Fielitz A, Haase M, Devarajan P. Neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury: a critical evaluation of current status. Ann Clin Biochem 2014; 51: 335–351.
Sean M. Gallagher1,2,3, R. Andrew Archbold1,3, Dan A. Jones1,2,3, Andrew Wragg1,3, Rakesh Uppal2,3,4 and Muhammad M. Yaqoob2,3,5 1 Department of Cardiology, Barts Health NHS Trust, London, UK; 2William Harvey Research Institute, Queen Mary University, London, UK; 3NIHR Cardiovascular Biomedical Research Unit, London Chest Hospital, London, UK; 4Department of Cardiothoracic Surgery, Barts Health NHS Trust, London, UK and 5Department of Nephrology, Barts Health NHS Trust, London, UK Correspondence: Muhammad M. Yaqoob, Department of Translational Medicine and Therapeutics, William Harvey Research Institute, John Vane Building, Charterhouse Square, London EC1M 6BQ, UK. E-mail: [email protected]
Kidney International (2015) 88, 1195–1196; doi:10.1038/ki.2015.263
Cell-based immunosuppression in kidney transplantation: the value of non-human primate studies To the Editor: In their review, Hutchinson and Geissler1 present a well-argued case for testing immunoregulatory cellbased immunosuppression in early-phase (phase I/II) clinical
1196
trials in renal transplantation. Extensive rodent studies have documented the potential of innate and adaptive regulatory immune cells to prolong allograft survival and induce transplant tolerance. Limited reports have demonstrated the feasibility of delivering such regulatory cells in human hematopoietic stem cell or organ transplantation. The significant barriers faced when translating these approaches to the clinic can be addressed in outbred non-human primates (NHPs) that have immune systems and histories of immune exposures similar to humans. These models have allowed rigorous pre-clinical assessment of the most promising tolerogenic strategies2 (e.g., donor bone marrow-induced mixed chimerism3) that have been applied in clinical renal transplantation. Three recent NHP studies demonstrate the safety and efficacy of regulatory immune cell-based therapy in renal transplantation. Thus, ex-vivo expanded, donor antigenspecific regulatory T cells prolong major histocompatibility complex-mismatched kidney allograft survival in monkeys when combined with anti-thymocyte globulin and low-dose sirolimus.4 Renal transplant rejection can also be safely prevented in cyclosporine and cyclophosphamide-treated monkeys and donor-specific tolerance induced by a single post-transplant (day 13) infusion of anergic (regulatory) T cells.5 Furthermore, infusion of (donor-derived) regulatory dendritic cells to prospective renal allograft recipients a week before transplant, together with costimulation blockade and sirolimus, safely prolongs graft survival, without evidence of host sensitization.6 These NHP studies underscore the potential safety and efficacy of innate or adaptive regulatory immune cell therapy in robust pre-clinical models and provide additional justification for testing these cell products in phase I/II trials in kidney transplantation.
ACKNOWLEDGMENTS
The authors’ work is supported by National Institutes of Health (NIH) research grants as part of the NIH NHP Transplantation Tolerance Cooperative Study Group sponsored by the NIAID and NIDDK. 1.
Hutchinson JA, Geissler EK. Now or never? The case for cell-based immunosuppression in kidney transplantation. Kidney Int 2015; 87: 1116–1124. 2. Kean LS, Gangappa S, Pearson TC et al. Transplant tolerance in nonhuman primates: progress, current challenges and unmet needs. Am J Transplant 2006; 6: 884–893. 3. Kawai T, Cosimi AB, Sachs DH. Preclinical and clinical studies on the induction of renal allograft tolerance through transient mixed chimerism. Curr Opin Organ Transplant 2011; 16: 366–371. 4. Ma A, Qi S, Song L et al. Adoptive transfer of CD4+CD25+ regulatory cells combined with low-dose sirolimus and anti-thymocyte globulin delays acute rejection of renal allografts in Cynomolgus monkeys. Int Immunopharmacol 2011; 11: 618–629. 5. Bashuda H, Kimikawa M, Seino K et al. Renal allograft rejection is prevented by adoptive transfer of anergic T cells in nonhuman primates. J Clin Invest 2005; 115: 1896–1902. 6. Ezzelarab MB, Zahorchak AF, Lu L et al. Regulatory dendritic cell infusion prolongs kidney allograft survival in nonhuman primates. Am J Transplant 2013; 13: 1989–2005.
Kidney International (2015) 88, 1195–1199
letter to the editor
Mohamed B. Ezzelarab1, David K.C. Cooper1 and Angus W. Thomson1,2 1 Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA and 2 Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA Correspondence: Angus W. Thomson, Department of Surgery or Department of Immunology, Thomas E. Starzl Transplantation Institute, University of Pittsburgh School of Medicine, W1540 BST, 200 Lothrop Street, Pittsburgh, Pennsylvania, USA. E-mail: [email protected]
Kidney International (2015) 88, 1196–1197; doi:10.1038/ki.2015.262
4.
Ezzelarab MB, Zahorchak AF, Lu L et al. Regulatory dendritic cell infusion prolongs kidney allograft survival in nonhuman primates. Am J Transplant 2013; 13: 1989–2005. 5. Salmikangas P, Flory E, Reinhardt J et al. Regulatory requirements for clinical trial and marketing authorisation application for cell-based medicinal products. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2010; 53: 24–29. 6. Pruss A, Garritsen H. Advanced therapy medicinal products - a multiple challenge. Transfus Med Hemother 2013; 40: 384–385. 7. Hutchinson JA, Geissler EK. Now or never? The case for cell-based immunosuppression in kidney transplantation. Kidney Int 2015; 87: 1116–1124.
James A. Hutchinson1 and Edward K. Geissler1 1
The Authors Reply: Ezzelrab and colleagues correctly assert that non-human primate (NHP) studies have increased confidence in the likely efficacy of immunoregulatory cellbased medicinal products (CBMPs) for organ transplantation.1 However, the value of large animal models in assessing CBMP safety remains uncertain for various reasons.2 Firstly, testing CBMPs of NHP origin provides no direct evidence about safety of human CBMPs. Extrapolating safety conclusions from NHP to human CBMPs requires that the two cell products are equivalent in every respect, not only primary pharmacodynamics. Accordingly, clinical experiences with closely-related human CBMPs may be a more reliable basis for judging the probable safety of new CBMPs. Secondly, unlike efficacy studies that aim to detect particular effects, which should be large and accrue to most recipients, safety studies must be powered to detect any adverse effects, which may be small or restricted to a subset of recipients. Consider the example of allosensitisation after deliberate alloantigen exposure: Assuming a sensitisation rate of ≤ 15%,3 excluding sensitisation in NHPs treated with donor-derived CBMPs would require 418 recipients per group. Such large NHP experiments are uncommon.4 Thirdly, European Law already mandates preclinical safety testing of CBMPs comparable to that of conventional pharmaceuticals,5 making compliance challenging for academic centers and small companies.6 Any new requirement for NHP studies would severely limit CBMP development. Fourthly, the European Parliament has recently declared to, ‘move towards the ultimate goal of phasing out the use of NHP in experiments’. Hence, while we greatly appreciate the importance NHP studies in evaluating therapeutic efficacy of CBMPs and confirming mechanismsof-action, we stand by our opinion that further animal studies are unlikely to advance CBMP safety in upcoming trials.7 1.
2.
3.
Ezzelrab MB, Cooper DKC, Thomson AW. Cell-based immunosuppression in kidney transplantation: the value of nonhuman primate studies. Kidney Int 2015; 88: 1196–1197. Broichhausen C, Riquelme P, Ahrens N et al. In question: the scientific value of preclinical safety pharmacology and toxicology studies with cell-based therapies. Molecular Therapy - Methods & Clinical Development 2014; 1: 14026. Flye MW, Burton K, Mohanakumar T et al. Donor-specific transfusions have long-term beneficial effects for human renal allografts. Transplantation 1995; 60: 1395–1401.
Kidney International (2015) 88, 1195–1199
Department of Surgery, Section of Experimental Surgery, University Hospital Regensburg, Regensburg, Germany Correspondence: Edward K. Geissler, Department of Surgery, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, Regensburg 93053, Germany. E-mail: [email protected] Kidney International (2015) 88, 1197; doi:10.1038/ki.2015.265
Circulating progranulin but not renal progranulin expression is increased in renal dysfunction To the Editor: With great interest we read the manuscript by Zhou et al.1 suggesting progranulin as a protective factor against renal dysfunction in a mouse model of renal ischemia/ reperfusion injury (IRI). The authors describe decreased renal progranulin expression, as well as increased serum progranulin levels, in mice with IRI as compared to controls.1 Interestingly, circulating progranulin was increased in humans with chronic kidney disease (CKD) and acute kidney injury (AKI) in two recent studies from our group.2,3 To further assess progranulin in renal disease, progranulin expression in kidneys and circulating levels were now investigated in animal models of CKD and AKI by analyzing stored samples of our previous studies.4,5 In 20-week-old eNOS− / − C57BLKS/J db/db mice (CKD model),4 mean ± SEM progranulin plasma concentrations were significantly higher (3914.8 ± 524.6 μg/l) as compared to C57BLKS/J controls (2771.7 ± 74.6 μg/l) (P = 0.038) (Figure 1a). Interestingly, renal progranulin expression was significantly downregulated in CKD-prone mice as compared to controls (P = 0.040) (Figure 1b). In 3-month-old rats undergoing bilateral nephrectomy (AKI model),5 progranulin plasma levels were increased 24 h post-surgery in AKI rats (844.5 ± 30.8 μg/l) as compared to sham-operated animals (512.4 ± 52.9 μg/l) (Po0.001) (Figure 1c). Taking our results and the interesting study by Zhou et al.1 into consideration, progranulin expression is reduced in IRI-AKI and CKD mice. However, circulating progranulin levels are consistently increased in human and rodent models of CKD/AKI. Thus, a local rather than systemic effect of progranulin contributes to improved renal function in IRI.1 Furthermore, increased circulating progranulin in CKD/AKI might be a compensatory mechanism to limit renal deterioration. 1197
