Dataset Information

Imaging Tumor-Infiltrating Lymphocytes in Brain Tumors with [⁶⁴Cu]Cu-NOTA-anti-CD8 PET.

ABSTRACT:

Purpose

Glioblastoma (GBM) is the most common malignant brain tumor in adults. Various immunotherapeutic approaches to improve patient survival are being developed, but the molecular mechanisms of immunotherapy resistance are currently unknown. Here, we explored the ability of a humanized radiolabeled CD8-targeted minibody to noninvasively quantify tumor-infiltrating CD8-positive (CD8⁺) T cells using PET.

Experimental design

We generated a peripheral blood mononuclear cell (PBMC) humanized immune system (HIS) mouse model and quantified the absolute number of CD8⁺ T cells by flow cytometry relative to the [⁶⁴Cu]Cu-NOTA-anti-CD8 PET signal. To evaluate a patient-derived orthotopic GBM HIS model, we intracranially injected cells into NOG mice, humanized cohorts with multiple HLA-matched PBMC donors, and quantified CD8⁺ tumor-infiltrating lymphocytes by IHC. To determine whether [⁶⁴Cu]Cu-NOTA-anti-CD8 images brain parenchymal T-cell infiltrate in GBM tumors, we performed PET and autoradiography and subsequently stained serial sections of brain tumor tissue by IHC for CD8⁺ T cells.

Results

Nontumor-bearing NOG mice injected with human PBMCs showed prominent [⁶⁴Cu]Cu-NOTA-anti-CD8 uptake in the spleen and minimal radiotracer localization to the normal brain. NOG mice harboring intracranial human GBMs yielded high-resolution PET images of tumor-infiltrating CD8⁺ T cells. Radiotracer retention correlated with CD8⁺ T-cell numbers in spleen and tumor tissue. Our study demonstrates the ability of [⁶⁴Cu]Cu-NOTA-anti-CD8 PET to quantify peripheral and tumor-infiltrating CD8⁺ T cells in brain tumors.

Conclusions

Human CD8⁺ T cells infiltrate an orthotopic GBM in a donor-dependent manner. Furthermore, [⁶⁴Cu]Cu-NOTA-anti-CD8 quantitatively images both peripheral and brain parenchymal human CD8⁺ T cells.

SUBMITTER: Nagle VL

PROVIDER: S-EPMC8026513 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:B lymphocytes are a key pathologic feature of multiple sclerosis (MS) and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to noninvasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here, we evaluated 64Cu-rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using PET. Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of myelin oligodendrocyte glycoprotein fragment1-125 emulsified in complete Freund adjuvant. Control mice received complete Freund adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19 h after 64Cu-rituximab administration. Mice were perfused and sacrificed after the final PET scan, and radioactivity in dissected tissues was measured with a ?-counter. CNS tissues from these mice were immunostained to quantify B cells or were further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice than in controls at all evaluated time points (e.g., 1 h after injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 percentage injected dose [%ID]/g, P < 0.05). 64Cu-rituximab PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice, compared with 1.25 ± 0.08 and 2.24 ± 0.11 %ID/g for controls (P < 0.05 for all regions except striatum and thalamus at 1 h after injection). Similarly, ex vivo biodistribution results revealed notably higher 64Cu-rituximab uptake in the brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased 64Cu-rituximab uptake in CNS tissues corresponded with elevated B cells. Conclusion: B cells can be detected in the CNS of EAE mice using 64Cu-rituximab PET. Results from these studies warrant further investigation of 64Cu-rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.

Project description:Current noninvasive imaging methods for monitoring immune response were largely developed for interrogation of the local reaction. This study developed the radiotracer 64Cu-labeled anti-CD11b (64Cu-αCD11b) for longitudinal assessment of local and systemic immune response involving mobilization of CD11b+ myeloid cells by small-animal PET/CT. Methods: Acute or chronic inflammation in the ears of BALB/c mice was induced by 12-o-tetradecanoylphorbol-13-acetate. Acute lung inflammation was induced by intratracheal lipopolysaccharide inoculation. αCD11b was conjugated with p-SCN-Bn-DOTA followed by labeling with 64Cu. PET/CT and biodistribution were evaluated at different times after intravenous injection of 64Cu-αCD11b. Cell populations from bone marrow (BM) and spleen were analyzed by flow cytometry. Results: 64Cu-αCD11b was primarily taken up by BM and spleen in control mice. In comparison, 64Cu-αCD11b uptake was significantly reduced in the BM and spleen of CD11b-knockout mice, indicating that 64Cu-αCD11b selectively homed to CD11b+ myeloid cells in vivo. In mice with ear inflammation, for the local inflammatory response, 64Cu-αCD11b PET/CT revealed significantly higher 64Cu-αCD11b uptake in the inflamed ears in the acute inflammation phase than the chronic phase, consistent with markedly increased infiltration of CD11b+ cells into the inflammatory lesions at the acute phase. Moreover, imaging of 64Cu-αCD11b also showed the difference in mouse systemic response for different inflammatory stages. Compared with uptake in control mice, BM 64Cu-αCD11b uptake in mice with ear inflammation was significantly lower in the acute phase and higher in the chronic phase, reflecting an initial mobilization of CD11b+ cells from the BM to the inflammatory foci followed by a compensatory regeneration of CD11b+ myeloid cells in the BM. Similarly, in mice with lung inflammation, 64Cu-αCD11b PET/CT readily detected acute lung inflammation and recruitment of CD11b+ myeloid cells from the BM. Immunohistochemistry staining and flow cytometry results confirmed the noninvasive imaging of PET/CT. Conclusion: 64Cu-αCD11b PET/CT successfully tracked ear and pulmonary inflammation in mice and differentiated acute from chronic inflammation at the local and systemic levels. 64Cu-αCD11b PET/CT is a robust quantitative method for imaging of local and systemic immune responses.

Dataset Information

Imaging Tumor-Infiltrating Lymphocytes in Brain Tumors with [⁶⁴Cu]Cu-NOTA-anti-CD8 PET.

Purpose

Experimental design

Results

Conclusions

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Imaging Tumor-Infiltrating Lymphocytes in Brain Tumors with [64Cu]Cu-NOTA-anti-CD8 PET.

Purpose

Experimental design

Results

Conclusions

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Imaging Tumor-Infiltrating Lymphocytes in Brain Tumors with [⁶⁴Cu]Cu-NOTA-anti-CD8 PET.