Engineered endosymbionts that alter mammalian cell surface marker, cytokine and chemokine expression

• Published in: Communications biology Vol. 5; no. 1; p. 888
• Main Authors: Madsen, Cody S., Makela, Ashley V., Greeson, Emily M., Hardy, Jonathan W., Contag, Christopher H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.08.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 13; 13/21; 13/31; 14; 14/19; 38; 45; 631/326/88; 631/61/2297; 64; 82; 82/80; Bacillus subtilis; Biology; Biomedical and Life Sciences; Cell surface; Chemokines; Cytokines; Cytoplasm; Endosymbionts; GATA-3 protein; Gene expression; Genomes; Immune response; Inflammation; KLF4 protein; Life Sciences; Listeria monocytogenes; Listeriolysin O; Macrophages; Mammalian cells; Monocytes; Operons; Phenotypes; Protein transport; Stat1 protein; Surface markers; Transcription factors
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-022-03851-6

Developing modular tools that direct mammalian cell function and activity through controlled delivery of essential regulators would improve methods of guiding tissue regeneration, enhancing cellular-based therapeutics and modulating immune responses. To address this challenge, Bacillus subtilis was developed as a chassis organism for engineered endosymbionts (EES) that escape phagosome destruction, reside in the cytoplasm of mammalian cells, and secrete proteins that are transported to the nucleus to impact host cell response and function. Two synthetic operons encoding either the mammalian transcription factors Stat-1 and Klf6 or Klf4 and Gata-3 were recombined into the genome of B. subtilis expressing listeriolysin O (LLO) from Listeria monocytogenes and expressed from regulated promoters. Controlled expression of the mammalian proteins from B. subtilis LLO in the cytoplasm of J774A.1 macrophage/monocyte cells altered surface marker, cytokine and chemokine expression. Modulation of host cell fates displayed some expected patterns towards anti- or pro-inflammatory phenotypes by each of the distinct transcription factor pairs with further demonstration of complex regulation caused by a combination of the EES interaction and transcription factors. Expressing mammalian transcription factors from engineered intracellular B. subtilis as engineered endosymbionts comprises a new tool for directing host cell gene expression for therapeutic and research purposes. The establishment of non-pathogenic engineered endosymbionts through B. subtilis is presented, with the aim of delivering mammalian transcription factors to the host cell for therapeutics and research.