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Sustained macrophage reprogramming is required for CD8+ T cell–dependent long-term tumor eradication

Publication . Jardim, Carolina; Bica, Marta; Reis-Sobreiro, Mariana; Mota, Afonso Teixeira da; Lopes, Raquel; Ferreira-Pinto, Miguel Alexandre; Sousa, Neuza S.; Mensurado, Sofia; Boekhoff, Henning; Scolaro, Tommaso; Reugebrink, Maud; Gonçalves-Sousa, Natacha; Kubo, Hiroshi; Leites, Elvira; Morais, Vanessa A.; Silva-Santos, Bruno; Barbosa-Morais, Nuno; Serre, Karine

Tumor-associated macrophages (TAM) exhibit a dual role in tumor progression and antitumor immunity. However, understanding the functional states and molecular mechanisms of antitumor TAMs remains a challenge. Herein, we show that intratumoral administration of a combination of agonists against TLR3 and CD40 [hereafter termed myeloid cell treatment (MCT)] reprogrammed TAMs in situ to adopt a protective antitumor phenotype in an orthotopic mouse breast cancer model, and that this led to tumor regression. Single-cell RNA sequencing of TAMs from different tumor stages and after MCT revealed a transient antitumor TAM phenotype, present at 12 hours after MCT and characterized by markers such as inducible nitric oxide synthase and CD38, which was replaced by TAMs coexpressing tumor-limiting and tumor-promoting features by 72 hours after MCT. Maintenance of antitumor TAMs required repeated MCT administration, and this promoted the activation of CD8+ T cells and long-term tumor eradication. Mechanistically, reactive oxygen species and TNF-α were pivotal in TAM-mediated tumor control. Our findings uncover the vulnerability of transient TAM reprogramming and show that it can be overcome by repeated MCT administrations to sustain efficient antitumor immune responses.

2025Journal article

Open access

Immunopathology and Trypanosoma congolense parasite sequestration cause acute cerebral trypanosomiasis

Publication . De Niz, Mariana; Silva Pereira, Sara; Serre, Karine; Ouarné, Marie; Coelho, Joana E; Franco, Claudio; Figueiredo, Luisa M.

Trypanosoma congolense causes a syndrome of variable severity in animals in Africa. Cerebral trypanosomiasis is a severe form, but the mechanism underlying this severity remains unknown. We developed a mouse model of acute cerebral trypanosomiasis and characterized the cellular, behavioral, and physiological consequences of this infection. We show large parasite sequestration in the brain vasculature for long periods of time (up to 8 hr) and extensive neuropathology that associate with ICAM1-mediated recruitment and accumulation of T cells in the brain parenchyma. Antibody-mediated ICAM1 blocking and lymphocyte absence reduce parasite sequestration in the brain and prevent the onset of cerebral trypanosomiasis. Here, we establish a mouse model of acute cerebral trypanosomiasis and we propose a mechanism whereby parasite sequestration, host ICAM1, and CD4+ T cells play a pivotal role.

2022Journal article

Open access