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Luciani A, Sirac C, Terryn S, Javaugue V, Prange JA, Bender S, Bonaud A, Cogné M, Aucouturier P, Ronco P, Bridoux F, Devuyst O. Impaired Lysosomal Function Underlies Monoclonal Light Chain-Associated Renal Fanconi Syndrome. J Am Soc Nephrol 2015; 27:2049-61. [PMID: 26614382 DOI: 10.1681/asn.2015050581] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/05/2015] [Indexed: 12/14/2022] Open
Abstract
Monoclonal gammopathies are frequently complicated by kidney lesions that increase the disease morbidity and mortality. In particular, abnormal Ig free light chains (LCs) may accumulate within epithelial cells, causing proximal tubule (PT) dysfunction and renal Fanconi syndrome (RFS). To investigate the mechanisms linking LC accumulation and PT dysfunction, we used transgenic mice overexpressing human control or RFS-associated κLCs (RFS-κLCs) and primary cultures of mouse PT cells exposed to low doses of corresponding human κLCs (25 μg/ml). Before the onset of renal failure, mice overexpressing RFS-κLCs showed PT dysfunction related to loss of apical transporters and receptors and increased PT cell proliferation rates associated with lysosomal accumulation of κLCs. Exposure of PT cells to RFS-κLCs resulted in κLC accumulation within enlarged and dysfunctional lysosomes, alteration of cellular dynamics, defective proteolysis and hydrolase maturation, and impaired lysosomal acidification. These changes were specific to the RFS-κLC variable (V) sequence, because they did not occur with control LCs or the same RFS-κLC carrying a single substitution (Ala30→Ser) in the V domain. The lysosomal alterations induced by RFS-κLCs were reflected in increased cell proliferation, decreased apical expression of endocytic receptors, and defective endocytosis. These results reveal that specific κLCs accumulate within lysosomes, altering lysosome dynamics and proteolytic function through defective acidification, thereby causing dedifferentiation and loss of reabsorptive capacity of PT cells. The characterization of these early events, which are similar to those encountered in congenital lysosomal disorders, provides a basis for the reported differential LC toxicity and new perspectives on LC-induced RFS.
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Affiliation(s)
- Alessandro Luciani
- Institute of Physiology, Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Christophe Sirac
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France; National Reference Center for Amyloidosis and other Monoclonal Immunoglobulin Deposition Diseases, University Hospital of Limoges, Poitiers, France
| | - Sara Terryn
- Division of Nephrology, UCL Medical School, Brussels, Belgium
| | - Vincent Javaugue
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France; Department of Nephrology, University Hospital, Poitiers University, Poitiers, France
| | - Jenny Ann Prange
- Institute of Physiology, Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Sébastien Bender
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France; Department of Nephrology, University Hospital, Poitiers University, Poitiers, France
| | - Amélie Bonaud
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France
| | - Michel Cogné
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France
| | - Pierre Aucouturier
- Department of Immunology, National Institute of Health and Medical Research Unit 938, Saint Antoine Hospital, Pierre et Marie Curie University, Paris, France
| | - Pierre Ronco
- Department of Nephrology and Dialysis, Tenon Hospital, Paris, France; Department of Immunology, National Institute of Health and Medical Research Unit 938, Saint Antoine Hospital, Pierre et Marie Curie University, Department of Nephrology and Dialysis, Tenon Hospital, Paris, France; Sorbonne Universités, UPMC University of Paris, Paris, France
| | - Frank Bridoux
- Department of Immunology, National Center for Scientific Research, Joint Research Unit 7276, University of Limoges, Limoges, France; Department of Nephrology, University Hospital, Poitiers University, Poitiers, France;
| | - Olivier Devuyst
- Institute of Physiology, Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland; Division of Nephrology, UCL Medical School, Brussels, Belgium;
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