Despite the capability of extracellular vesicles (EVs) derived from Gram-negative and Gram-positive bacteria to induce potent anti-tumour responses, large-scale production of bacterial EVs remains as a hurdle for their development as novel cancer immunotherapeutic agents. Here, we developed manufacturing processes for mass production of Escherichia coli EVs, namely, outer membrane vesicles (OMVs). By combining metal precipitation and size-exclusion chromatography, we isolated 357 mg in total protein amount of E. coli OMVs, which was equivalent to 3.93 × 1015 particles (1.10 × 1010 particles/μg in total protein amounts of OMVs) from 160 L of the conditioned medium. We show that these mass-produced E. coli OMVs led to complete remission of two mouse syngeneic tumour models. Further analysis of tumour microenvironment in neoantigen-expressing tumour models revealed that E. coli OMV treatment causes increased infiltration and activation of CD8+ T cells, especially those of cancer antigen-specific CD8+ T cells with high expression of TCF-1 and PD-1. Furthermore, E. coli OMVs showed synergistic anti-tumour activity with anti-PD-1 antibody immunotherapy, inducing substantial tumour growth inhibition and infiltration of activated cancer antigen-specific stem-like CD8+ T cells into the tumour microenvironment. These data highlight the potent anti-tumour activities of mass-produced E. coli OMVs as a novel candidate for developing next-generation cancer immunotherapeutic agents.
© 2023 The Authors. Journal of Extracellular Vesicles published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles.

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.
© 2022, Silva Pereira, De Niz et al.

Trypanosoma congolense causes a syndrome of variable severity in animals in sub-Saharan Africa. Cerebral trypanosomiasis is an acute form, but the mechanism underlying this severity remains unknown . We developed a mouse model of cerebral trypanosomiasis with T. congolense strain 1/148 and characterized the cellular, behavioral and physiological consequences of this infection. Using in vivo imaging, we show large parasite sequestration in the brain vasculature for long periods of time (up to 8 hours), that results in extensive brain damage partly caused by ICAM1-mediated recruitment and accumulation of T cells. Antibody-mediated ICAM1 blocking and lymphocyte absence reduce parasite sequestration in the brain and prevent the onset of cerebral trypanosomiasis. Here, we establish a new mouse model of cerebral trypanosomiasis and we propose a mechanism whereby parasite sequestration, host ICAM1, and T cells play a pivotal role.