Endotoxin-mediated delayed islet graft function is associated with increased intra-islet cytokine production and islet cell apoptosis

Thierry Berney, R. Damaris Molano, Pierre Cattan, Antonello Pileggi, Caterina Vizzardelli, Robert Oliver, Camillo Ricordi, Luca Inverardi

Research output: Contribution to journalArticlepeer-review

121 Scopus citations

Abstract

Background. Primary nonfunction resulting in immediate graft loss is responsible for the failure of a large number of islet transplants. Evidence is accumulating to single out endotoxin contamination of the various reagents needed for islet isolation as a major cause of early graft loss. Methods. Islets isolated with endotoxin-containing (400 endotoxin units/ml) collagenase type V and "endotoxin-free" (3.1 endotoxin units/ml) Liberase™ were compared. Graft function was assessed using a syngeneic murine model of marginal islet mass transplantation. Pro-inflammatory cytokine production by islets was measured by ELISA in culture supernatants, and quantitative reverse transcriptase-PCR. Islet cell apoptosis was measured using the annexin assay. Results. Graft function was significantly delayed when islets were isolated with endotoxin-containing collagenase. Addition of endotoxin to the Liberase™ solution similarly delayed graft function. After 18 hr in culture, collagenase-isolated islets released higher amounts of proinflammatory cytokines compared with Liberase™-isolated islets (interleukin-6: 2185±1174 pg/ml vs. 520±201 pg/ml; tumor necrosis factor-α: 304±298 pg/ml vs. 0; IL-1β: 12.5 pg/ml±12.5 vs. 0). This observation correlated with higher cytokine mRNA expression in collagenase-isolated islets. The percentage of apoptotic islet cells immediately after isolation was 17.2%±9.4 in collagenase-isolated islets and 7.1%±2.1 in Liberaser™-isolated islets. Conclusions. We propose that endotoxin contamination is the primum movens of a chain of events that involves intra-islet cytokine production and release and islet cell apoptosis, and endotoxin contamination can ultimately lead to primary nonfunction in vivo. This emphasizes the fact that using endotoxin-free reagents during isolation is a key factor for successful islet transplantation.

Original languageEnglish (US)
Pages (from-to)125-132
Number of pages8
JournalTransplantation
Volume71
Issue number1
StatePublished - Jan 15 2001

ASJC Scopus subject areas

  • Transplantation

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