Decrock, Elke

Deleye, Steven

Delvaeye, Tinneke

Gon\ue7alves, Amanda

Krysko, Dmitri

Lemeire, Kelly

Leybaert, Luc

Staelens, Steven

Vandenabeele, Peter

Wyffels, Leonie

Abstract: Systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body. It is associated with the presence of pro- and anti-inflammatory cytokines in serum, including tumor necrosis factor (TNF). TNF has multiple effects and leads to cytokine production, leukocyte infiltration, blood pressure reduction and coagulation, thereby contributing to tissue damage and organ failure. A sterile mouse model of sepsis, TNF-induced SIRS, was used to visualize the temporal and spatial distribution of damage in susceptible tissues during SIRS. For this, a radiopharmaceutical agent, 99mTc-duramycin, binding to exposed phosphatidylethanolamine on dying cells, was longitudinally visualized using single photon emission computed tomography (SPECT/CT) imaging. Methods: C57Bl/6J mice were challenged with intravenous (i.v.) injections of murine TNF or vehicle, and necrostatin-1 (Nec-1) was used to interfere with cell death. Two h post vehicle- or TNF-treatment, mice received 99mTc-duramycin i.v. (35.44\ub13.80 MBq). Static whole-body 99mTc-duramycin SPECT/CT imaging was performed 2, 4 and 6 h post-tracer injection. Tracer uptake in different organs was quantified by volumes of interest analysis using PMOD software and expressed as mean Standard Uptake Value (SUVmean). After the last scan, ex vivo biodistribution was performed to validate the SPECT imaging data. Lastly, terminal deoxynucleotidyl-transferase mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining was performed to correlate the obtained results to cell death. Results: An increased 99mTc-duramycin uptake was detected in mice injected with TNF, when compared to control mice in lungs (0.55\ub10.05 vs 0.34\ub10.03), intestine (0.75\ub10.06 vs 0.56\ub10.05) and liver (1.03\ub10.09 vs 0.64\ub10.02) 4 h post TNF, and remained significantly elevated until 8 h post TNF. The imaging results were consistent with ex vivo \u3b3-counting results. Significant increased levels of tissue damage were detected via TUNEL staining in the lungs and intestine of mice injected with TNF. Interestingly, Nec-1 pretreatment conferred protection against lethal SIRS and reduced the 99mTc-duramycin-uptake in the lungs, 8 h post TNF (SUV = 0.32\ub10.04 vs 0.51\ub10.08). Conclusion: This study demonstrates that noninvasive 99mTc-duramycin SPECT imaging can be used to characterize temporal and spatial kinetics of injury and cell death in susceptible tissues during TNF-induced SIRS, making it useful for global, whole-body assessment of tissue damage during diseases associated with inflammation and injury

Institutional Repository Universiteit Antwerpen

Noninvasive whole-body imaging of phosphatidylethanolamine as a cell death marker using <tex>^{99m}Tc-duramycin$</tex> during TNF-induced SIRS

Noninvasive whole-body imaging of phosphatidylethanolamine as a cell death marker using <tex>^{99m}Tc-duramycin$</tex> during TNF-induced SIRS

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Institutional Repository Universiteit Antwerpen