Article

Diabetologia

, Volume 48, Issue 9, pp 1789-1797

Expression of nephrin by human pancreatic islet endothelial cells

  • M. M. ZanoneAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino Email author 
  • , E. FavaroAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino
  • , S. DoublierAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino
  • , B. Lozanoska-OchserAffiliated withDepartments of Immunobiology and Diabetes and Internal Medicine, Guy’s, King’s and St Thomas’s School of Medicine
  • , M. C. DeregibusAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino
  • , J. GreeningAffiliated withDepartments of Immunobiology and Diabetes and Internal Medicine, Guy’s, King’s and St Thomas’s School of Medicine
  • , G. C. HuangAffiliated withDepartments of Immunobiology and Diabetes and Internal Medicine, Guy’s, King’s and St Thomas’s School of Medicine
  • , N. KleinAffiliated withDepartment of Immunobiology, Institute of Child Health
  • , P. Cavallo PerinAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino
    • , M. PeakmanAffiliated withDepartments of Immunobiology and Diabetes and Internal Medicine, Guy’s, King’s and St Thomas’s School of Medicine
    • , G. CamussiAffiliated withDepartment of Internal Medicine and Centre of Experimental Medicine (CeRMS), University of Torino

Abstract

Aims/hypothesis

The islet microcirculation has morphological characteristics resembling those of renal glomeruli. Transcription of the nephrin gene, a highly specific barrier protein of the slit diaphragm of podocyte foot processes, has been reported in the pancreas, although its cellular localisation and function remain to be defined. In this study, we purified and characterised microvascular endothelial cells (MECs) isolated from human islets and investigated the expression and distribution of nephrin on these cells.

Methods

Human islet MECs were extracted and purified using anti-CD105-coated immunomagnetic beads and their endothelial characteristics were confirmed by expression of classical endothelial markers and basal high-level expression of intercellular adhesion molecule-1 and TNF-α-inducible vascular cell adhesion molecule-1. Nephrin expression was assessed by immunofluorescence, flow cytometric analysis and western blotting on cell lysates, as well as by RT-PCR.

Results

Immunofluorescence studies detected nephrin in a fine, punctate, diffuse pattern on cultured islet MECs, and also in human pancreatic islet sections. In both cases nephrin colocalised with endothelial markers. TNF-α treatment induced a marked reduction and redistribution of the protein in one or multiple aggregates. Nephrin expression was confirmed by flow cytometry, western blotting and RT-PCR studies. In contrast, nephrin could not be detected at the protein or mRNA level in human macro- and microvascular cells from other sites.

Conclusions/interpretation

Nephrin is expressed at protein and mRNA levels in islet microendothelium, supporting the hypothesis that islet MECs exhibit distinctive morphological characteristics that indicate functional specialisation of potential pathophysiological importance.

Keywords

Adhesion molecules Endothelial cells Islets of Langerhans Nephrin