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

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.

Development of a multiplex microbead-based immunoassay for quantitative analysis of mouse immune checkpoint proteins

Immune checkpoint protein research plays a significant role in improving antitumor immune response as well as achieving a deeper understanding of the immune system and the disease states of inflammation, sepsis, and autoimmunity. Various mouse models have contributed to the clinical successes of immune checkpoint inhibitor immunotherapies and the understanding of checkpoint molecule-related inflammatory processes. Here we report the assay verifications and applications of a newly developed Luminex bead-based mouse immune-oncology checkpoint protein multiplex immunoassay for the quantitative profiling of 28 mouse immune checkpoint molecules and immune regulators (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/CD137L/TNFSF9, CD137/4-1BB, 5’-NT/CD73, BCA-1/CXCL-13, CD25/IL-2Rα, Granzyme B, E-cadherin, Galectin-1, Galectin-3, IFNγ, IL-10, TLR-2, and TNFα). We present quantitative protein biomarker profiling of mouse serum/plasma samples and conditioned media and lysates from mouse tumor cell lines, including LLC, B16-F10, MCA205, ID8, MB49, AT3, CT-2A, and YUMM1.7, as well as DC2.4 (dendritic cell line), C2C12 (myoblast cell line), and bEnd.3 (endothelial cell line). Our results demonstrate that this mouse immune checkpoint protein multiplex immunoassay is a powerful research tool for the quantitation of key immune regulator proteins and has potential application in biomarker discovery and translational research.

Simultaneous Measurement of 67 Non-Human Primate Immunological, Metabolic and Hormonal Biomarkers using Luminex® xMAP® Technology

Immunology, metabolic, and pituitary biomarker research in non-human primates (NHP) is essential for the study of several diseases and biological regulation. To meet this need, we developed three NHP MILLIPLEX® multiplex panels: 12-plex NHP Metabolic Hormone, 7-plex NHP Pituitary Panel 1, and our new 48-plex NHP Cytokine/Chemokine Panel A for the simultaneous measurement of picogram levels of 67 immune, metabolic and hormone factors, in small volumes of serum, plasma or cell culture samples using Luminex® xMAP® technology. Serum from in vivo LPS-challenged animals (n=2 cynomolgus, n=2 rhesus) demonstrated increased levels of 19 cytokines/chemokines with peak elevated levels at 1 hr for 4 analytes (e.g. IL-10, TNFα), at 3 hr for 11 analytes (e.g. IL-6, IFNγ) and at 8 hr (e.g. Fractalkine, I-TAC). Metabolic markers, GIP and GLP-1 (active) in rhesus, also increased significantly at 8 hr and 3 hr, respectively (p<0.02). Significant differences between fasted and fed serum sample values (n=5 cynomolgus, n=5 rhesus) were found for several metabolic markers, including C-peptide, GIP, Insulin and PP, which increased with feeding (P<0.05). In cynomolgus, I-TAC and IP-10 significantly increased after feeding (P<0.003). Testing healthy serum samples from three additional NHP species (African green monkey (n=5), baboon (n=5), chimpanzee (n=5)) exhibited overall sample detectability of 89%, 77%, and 64% for the MILLIPLEX®Cytokine/Chemokine Panel A, Pituitary, and Metabolic multiplex panels, respectively. Thus, the MILLIPLEX®NHP Metabolic Hormone, NHP Pituitary Panel 1 and our latest and largest NHP panel, the 48-plex NHP Cytokine/Chemokine Panel A, are valuable tools for profiling 67 biomarkers in 5 NHP species for disease research.

Analysis of soluble immune checkpoint proteins using quantitative multiplex microbead-based immunoassays

Immune-checkpoint receptors play critical roles in immune regulations and maintenance of immune homeostasis. Recently, a series of soluble immune checkpoint proteins have been found in circulation, and are putative biomarkers in infection, cancer, and autoimmune diseases. We have developed two multiplex immuno-oncology (I/O) panels. Human I/O Checkpoint Protein Panel 1 (17-plex) consists of 17 targets: BTLA, CD27, CD28, CD40, CD80, CD86, CTLA-4, GITR, GITRL, HVEM, ICOS, LAG-3, PD-1, PD-L1, PD-L2, TIM-3, TLR-2. Human I/O Checkpoint Protein Panel 2 (31-plex) consists of 31 targets: 4-1BBL, CD73, APRIL, Arginase-1, B7-H2, B7-H3, B7-H4, B7-H5, B7-H6, BAFF, CD25, CD30, CD40L, 4-1BB, CD226, E-Cadherin, FGL1, Gal-1, Gal-3, Granulysin, Granzyme B, IDO1, MICA, MICB, Nectin-2, Nectin-4, OX40, Perforin, CD155, Siglec-7, and Siglec-9. Using these multiplex arrays, we have simultaneously quantitated the expression levels of the above 48 key immune regulators in cancer serum samples and in cell culture supernatants. Soluble checkpoint protein signatures generated from this multiplex approach revealed differential expression of sBTLA, sCD27, sCD40, sCD86, sHVEM, sPD-1, sTIM-3, sTLR-2, sCD40L, Gal-3, Gal-1, FGL1, BAFF in the colorectal or breast cancer serum samples, compared to healthy serum controls. Heatmaps demonstrate the detection of checkpoint proteins in the conditioned media collected from human tumor cell lines and stimulated PBMCs. In summary, our results demonstrate that these two multiplex immunoassays we developed are useful research tools for the simultaneous quantitation of circulating immune checkpoint proteins, as well as for its potential application in biomarker discovery and translational research.

IgG Antibodies against SARS-CoV-2 Correlate with Days from Symptom Onset, Viral Load and IL-10

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a pandemic of coronavirus disease 2019 (COVID-19). Antibody testing is essential to identify persons exposed to the virus and potentially predicting immunity. 183 COVID-19 patients (68 mechanically ventilated) and 41 controls were tested for plasma IgG, IgA and IgM against the SARS-CoV-2 S1, S2, receptor binding domain (RBD) and N proteins using the MILLIPLEX® SARS-CoV-2 Antigen Panels. COVID-19 positive patients had high levels of IgG, IgA and IgM anti-SARS-CoV-2 antibodies against viral proteins. Sensitivity of anti-S1 IgG increased from 60% to 93% one week after symptom onset. S1-IgG and S1-IgA had specificities of 98%. Ventilated COVID-19 patients had higher antibody levels than the COVID-19 patients who were not ventilated. IgG antibody levels against S1 protein had the strongest correlation to days from symptom onset. We found that patients with the highest IgG levels had the lowest viral load. Finally, there was a correlation of high plasma IL-10 with low anti-SARS-CoV-2 IgG.

IgG Antibodies against SARS-CoV-2 Correlate with Days from Symptom Onset, Viral Load and IL-10

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a pandemic of the respiratory disease coronavirus disease 2019 (COVID-19). Antibody testing is essential to identify persons exposed to the virus and potentially in predicting disease immunity. 183 COVID-19 patients (68 of whom required mechanical ventilation) and 41 controls were tested for plasma IgG, IgA and IgM against the SARS-CoV-2 S1, S2, receptor binding domain (RBD) and N proteins using the MILLIPLEX® SARS-CoV-2 Antigen Panel. Plasma cytokines were concurrently measured using the MILLIPLEX® MAP Human Cytokine/Chemokine/Growth Factor Panel A. As expected the 183 COVID-19 positive patients had high levels of IgG, IgA and IgM anti-SARS-CoV-2 antibodies against each of the viral proteins. Sensitivity of anti-S1 IgG increased from 60% to 93% one week after symptom onset. S1-IgG and S1-IgA had specificities of 98% compared to the 41 COVID-19 negative patients. The 68 ventilated COVID-19 positive patients had higher antibody levels than the 115 COVID-19 positive patients who were not ventilated. IgG antibody levels against S1 protein had the strongest positive correlation to days from symptom onset. There were no statistically significant differences in IgG, IgA and IgM antibodies against S1 based on age. We found that patients with the highest levels of anti-SARS-CoV-2 antibodies had the lowest viral load in the nasopharynx. Finally there was a correlation of high plasma IL-10 with low anti-SARS-CoV-2 antibodies. Anti-SARS-CoV-2 antibody levels, as measured by a novel antigen panel, increased within days after symptom onset, achieving > 90% sensitivity and specificity within one week, and were highest in patients who required mechanical ventilation. Antibody levels were inversely associated with viral load but did not differ as a function of age. The correlation of high IL-10 with low antibody response suggests a potentially suppressive role of this cytokine in the humoral immune response in COVID-19.

Selective heterocyclic amidine inhibitors of human inducible nitric oxide synthase

The potency and selectivity of a series of 5-hetero-2-iminohexahydroazepines were examined as inhibitors of the three human NOS isoforms. The effect of ring substitution of the 5-carbon for a heteroatom is presented. Potencies (IC(50)'s) for these inhibitors are in the low micromolar range for hi-NOS with some examples exhibiting a 500x selectivity versus hec-NOS.