PT  - JOURNAL ARTICLE
AU  - Lindsey Drake
AU  - Peter Scott
TI  - Investigation into RAGE as a biomarker of the LPS-induced murine model of neuroinflammation
DP  - 2019 May 01
TA  - Journal of Nuclear Medicine
PG  - 480--480
VI  - 60
IP  - supplement 1
4099  - http://jnm.snmjournals.org/content/60/supplement_1/480.short
4100  - http://jnm.snmjournals.org/content/60/supplement_1/480.full
SO  - J Nucl Med2019 May 01; 60
AB  - 480Objectives: The Receptor for Advanced Glycation End-products (RAGE) is an inflammatory receptor found to be overexpressed in human brain tissue section from Alzheimer’s disease (AD) patients. 1 Inhibition of RAGE in APP transgenic mice decreased the deposition of amyloid-beta plaques. 2 Initial development of a PET radioligand for RAGE, [18F]RAGER, has been previously reported in rodent and nonhuman primate brain. 1 To further validate the use of RAGER for PET imaging of neuroinflammation, the well described LPS model of neuroinflammation was initiated in mice and evaluated for anti-RAGE immunoreactivity and binding to [3H]RAGER and the halted therapeutic agent [3H]Azeliragon. Methods: C57BL/6 mice were dosed with 5 mg/kg LPS (O111:B4) intraperitoneally. Animals were sacrificed at 24 h (n=4/ sex) and 14 d (n=4/ sex). Vehicle control animals (n=2/ sex/ time point) were sacrificed at the same time points. After cervical ligation, brains were divided sagittally and flash frozen. Frozen section were cut at 20 µm and thaw mounted to poly-lysine coated glass slides for use in immunohistochemical (IHC) and autoradiographic studies. To validate the model, IHC was performed with anti-IL-1β (1:300) and anti-TNFα (1:300). Experimentally, immunoreactivity to anti-RAGE (1:200) and [3H]RAGER and [3H]Azeliragon binding were evaluated. Multiple comparisons were performed in GraphPad Prism 8.0.1 using 1-way ANOVA analysis and Tukey’s multiple comparisons test. Results: In the female mice cohort, statistically significant increases of TNFα immunoreactivity at the 14 day time point and IL-1β immunoreactivity at 24 hr and 14 d compared to the vehicle control group. The male cohort had statistically significant increases of IL-1β and TNFα immunoreactivity at both time points compared to vehicle control. These two biomarkers confirmed the induction of neuroinflammation from the LPS injection. In the female LPS cohorts, there was no statistically significant difference in anti-RAGE immunoreactivity; however, the male LPS cohorts had increased RAGE expression at 24h (2.5 fold; p= 0.0019) and 14d (2.3 fold; p= 0.0064). Autoradiography results mirror the IHC findings in the female cohorts, with no significant difference in binding of either RAGE ligand. Although the male expression level of RAGE was significantly increased, a difference in total or specific binding of RAGE ligands was not quantifiable. Conclusions: To our knowledge, this is the first investigation into the role of RAGE in this inflammatory model. Despite the biochemical pathway of RAGE signaling being understood to initiate inflammatory signaling, this was only observed in the male cohort with a minimal increase (~2 fold). Immunoreactivity and binding to RAGE ligands confirmed that there was no change of RAGE expression or abundance in female mouse brain. Binding experiments with RAGE ligands demonstrated that despite a modest increase in expression in male mouse brain, a binding difference measured by autoradiography could not be quantified. References 1. Cary, B. P.; Brooks, A. F.; Fawaz, M. V.; Drake, L. R.; Desmond, T. J.; Sherman, P.; Quesada, C. A.; Scott, P. J. H., Synthesis and Evaluation of [18F]RAGER: A First Generation Small-Molecule PET Radioligand Targeting the Receptor for Advanced Glycation Endproducts. ACS Chemical Neuroscience 2016, 7 (3), 391-398. 2. Deane, R.; Singh, I.; Sagare, A. P.; Bell, R. D.; Ross, N. T.; LaRue, B.; Love, R.; Perry, S.; Paquette, N.; Deane, R. J.; Thiyagarajan, M.; Zarcone, T.; Fritz, G.; Friedman, A. E.; Miller, B. L.; Zlokovic, B. V., A multimodal RAGE-specific inhibitor reduces amyloid β-mediated brain disorder in a mouse model of Alzheimer disease. The Journal of Clinical Investigation 2012, 122 (4), 1377-1392.