Abstract 5080: Age- and pregnancy-related impact on soluble immune checkpoint protein profiles in mice as analyzed by a novel multiplex immunoassay

Abstract

Abstract Immune checkpoint proteins are key regulators of the immune system and drug targets of cancer immunotherapy. There is extensive literature on the use of various types of mouse models for biomarker discovery and drug testing. Only a few studies have examined the association between soluble immune checkpoint proteins and the immune status. Following the development of multiplex immunoassay panels for profiling human co-inhibitory and co-stimulatory immune checkpoint proteins, here we report the development of a novel magnetic bead-based Luminex multiplex assay for the quantitative detection of 28 mouse immune checkpoint proteins and immune regulators in 25 μL of sample (PD-1, PD-L1, PD-L2, CTLA-4/CD152, TIM-3, LAG-3, B7-H2/ICOSL, B7-H3/CD276, BTLA, GITR, HVEM, CD27, CD40, CD80/B7-1, CD226/DNAM-1, 4-1BBL/TNFSF9, CD137/4-1BB, 5’-NT/CD73, BCA-1/CXCL13, CD25/IL-2Rα, Granzyme B, E-cadherin, Galectin-1, Galectin-3, IFNγ, IL-10, TLR-2, and TNFα). Immune function declines with age, while the incidence of cancer rises. In this study, we examined age-related serum samples by quantitative profiling soluble checkpoint proteins from young (age of 8-month-old, n=8) and old-aged mice (48-month-old, n=8) of C57BL/6 strain. A significant age effect was observed on the levels of soluble checkpoint proteins in mouse serum samples tested. Comparing with the young mice, decreased levels of circulating HVEM, Granzyme B, LAG-3, PD-L1, CD73, B7-H2, CD25, and CD27; and increased levels of circulating TIM-3, PD-1, PD-L2, CD40, Galectin-3, IL-10, BCA-1, and TLR-2 were observed in aged C57BL/6 mice (Mann Whitney test, P value <0.05). The immune system also changes during pregnancy. We used the similar multiplex array approach to profile the soluble checkpoint proteins in non-pregnant (n=16) and pregnant CD-1 mice (n=9). Significant decreased levels of soluble LAG-3, B7-H2, B7-H3, CD25, CD27, and Galectin-1; and significant increase of soluble CD137, Galectin-3, and CD73 expression levels were detected in the serum samples of pregnant mice, as compared to the samples from the non-pregnant mice (Mann Whitney test, P value <0.05). Altogether, using bead-based quantitative multiplex analysis, our results demonstrate that the changes on circulating immune checkpoint protein profiles occur in the immunologic adaptations with age and during pregnancy in mice. Citation Format: Wen-Rong Lie, Christine Kornmeier, Ling Zeng, James Hoberg. Age- and pregnancy-related impact on soluble immune checkpoint protein profiles in mice as analyzed by a novel multiplex immunoassay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5080.