Endocytosis of light chains induces cytokines through activation of NF-κB in human proximal tubule cells

• Published in: Kidney international Vol. 62; no. 6; pp. 1977 - 1988
• Main Authors: Sengul, Sule, Zwizinski, Craig, Simon, Eric E., Kapasi, Aditi, Singhal, Pravin C., Batuman, Vecihi
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-12-2002; Nature Publishing
• Subjects: Biological and medical sciences; human serum albumin; interleukin-6; Interstitial nephritis; Medical sciences; monocyte chemoattractant protein-1; myeloma; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; progressive kidney disease; proteinuria; monocyte chemoattractant protein-1; myeloma; progressive kidney disease; human serum albumin; proteinuria; interleukin-6; Kidney disease; Human; Immunopathology; Urinary system disease; Cytokine; Malignant hemopathy; Serum albumin; Myeloma; Endocytosis; Renal tubule; Immunoglobulinopathy; Lymphoproliferative syndrome; Tubulointerstitial nephritis; Transcription factor NFκB; Monocyte chemoattractant protein 1
• ISSN: 0085-2538; 1523-1755
• DOI: 10.1046/j.1523-1755.2002.00660.x

Endocytosis of light chains induces cytokines through activation of NF-κB in human proximal tubule cells.
In proteinuric states increased cytokine production through endocytosis of filtered proteins by proximal tubule cells (PTCs) has been proposed as a major mechanism mediating tubulointerstitial injury and progressive kidney disease. We studied the effects of six different light chains (LCs) on the production of cytokines in cultured human PTCs.
LCs were isolated and purified from the urine of patients with myeloma and human PTCs were exposed to either LC or human serum albumin (HSA) for up to 24 hours. LC endocytosis was monitored by immunocytochemistry. Cytokines were determined by enzyme-linked immunosorbent assay (ELISA) in the supernatants and activation of nuclear factor-kappa B (NF-κB) was detected by electrophoretic mobility shift assays (EMSA) and immunocytochemistry.
Endocytosis of LCs induced the release of interleukins (IL) IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1); however, there was considerable variability among the six different LCs. In contrast, HSA had no effect on cytokine production even at very high concentrations. Removal of LC-containing media resulted in cessation of IL-6 release. LC-induced cytokine release was associated with nuclear translocation of NF-κB subunits p50 and p65, as demonstrated by both EMSA and immunocytochemistry. Inhibitors of NF-κB, aspirin and pyrrolidineditiocarbamate (PDTC) markedly suppressed LC-induced cytokine production.
LC endocytosis leads to production of inflammatory cytokines through activation of NF-κB. This may be an important mechanism of chronic tubulointerstitial inflammation process commonly seen in multiple myeloma. These findings also point out a potential role by filterable low-molecular-weight proteins, like LCs, in PTC injury during all proteinuric diseases.