Brain death-induced inflammatory activity in human pancreatic tissue: a case-control study

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 834-867-Islet Biology
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-860
Daisy Crispim*1, Tatiana Helena Rech2, Jakeline Rheinheimer2, Sabrina Barkan2, Alessandro B Osvaldt2 and Cristiane Bauermann Leitão2
1Clinical Hospital from Porto Alegre, Porto Alegre, Brazil, 2Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
Introduction: Long-term insulin independence after islet transplantation depends on the engraftment of a large number of pancreatic islets. The yield of pancreatic islet from brain-dead donors is negatively affected by the up-regulation of proinflammatory cytokines, such as TNF, IL-6, IL-1β and IFN-γ. Brain death (BD) is also believed to increase the expression of tissue factor (TF), which further contributes to a low rate of islet engraftment.

Objective: To compare plasma levels and pancreatic gene expression of proinflammatory cytokines (TNF, IL-6, IL-1β and IFN-γ) and TF between brain-dead organ donors and control subjects who undergone therapeutic pancreatectomy.

Methods: This study comprised 17 brain-dead patients (cases) and 20 control patients. From each subject, it was collect an aliquot of peripheral blood and a biopsy of pancreatic tissue. Plasma TNF, IL-6, IL-1β, IFN-γ and TF were measured using commercial ELISA kits. Gene expressions of these cytokines and TF were evaluated by RT-qPCR on pancreatic tissue samples. Protein quantifications were performed by immunohistochemistry in paraffin-embedded pancreas sections.

Results: Brain-dead patients had higher plasma concentrations of TNF and IL-6 in comparison to controls [TNF: 12.3ng/ml (0.1-23.6) vs. 3.8ng/ml (3.4-6.62), P=0.02; IL6: 1127.1ng/ml (355.7-4571.6) vs. 92.8ng/ml (55.3-262.6), P<0.0001]. The groups had similar TNF, IL-6, IL-1β, and IFN-γ mRNA levels in pancreatic tissue. However, RT-qPCR revealed significant up-regulation of TF mRNA expression in control patients as compared to brain-dead patients [control 1.38-fold (0.7-2.0) vs. brain-dead 0.39-fold (0.1-1.2), P=0.037]. Immunohistochemical analyses showed that brain-dead patients had increased TNF protein levels compared to controls (16.81 ± 5.2 pixels vs. 11.57 ± 4.93 pixels; P<0.005), in agreement with the results obtained for plasma TNF levels (r=0.451; P=0.014). Moreover, TNF protein was widely distributed in all pancreatic tissue, including islets. IL-6 and IL-1β proteins were identified in both ductal cells and islet cells, but no significant difference was observed between cases and controls. IFN-γ and TF proteins were minimally observed in pancreatic tissue and were present with similar amounts in case and control groups.  

Conclusion: BD induces inflammatory activity evidenced by the up-regulation of TNF in plasma and pancreatic tissue. Blocking the expression of key inflammatory mediators in brain-dead donors should be evaluated as a new approach to improve the outcomes of islet transplantation.

Nothing to Disclose: DC, THR, JR, SB, ABO, CBL

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Financial support: CNPq, FAPERGS, FIPE-HCPA.