Comparison of two human organoid models of lung and intestinal inflammation reveals Toll-like receptor signalling activation and monocyte recruitment.
OBJECTIVES: The activation of immune responses in mucosal tissues is a key factor for the development and sustainment of several pathologies including infectious diseases and autoimmune diseases. However, translational research and personalized medicine struggle to advance because of the lack of suitable preclinical models that successfully mimic the complexity of human tissues without relying on in vivo mouse models. Here we propose two in vitro human 3D tissue models, deprived of any resident leukocytes, to model mucosal tissue inflammatory processes. METHODS: We developed human 3D lung and intestinal organoids differentiated from induced pluripotent stem cells to model mucosal tissues. We then compared their response to a panel of microbial ligands and investigated their ability to attract and host human primary monocytes. RESULTS: Mature lung and intestinal organoids incorporated epithelial (EpCAM+) and mesenchymal (CD73+) cells which responded to toll-like receptor stimulation by releasing pro-inflammatory cytokines and expressing tissue inflammatory markers including MMP9, COX2 and CRP. When added to the organoid culture, primary human monocytes migrated towards the organoids and began to differentiate to an “intermediate-like” phenotype characterised by increased levels of CD14 and CD16. CONCLUSION: We show that human mucosal organoids exhibit proper immune functions and successfully mimic an immunocompetent tissue micro-environment able to host patient-derived immune cells. Our experimental setup provides a novel tool to tackle the complexity of immune responses in mucosal tissues which can be tailored to different human pathologies. Overall design: mRNA transcriptome of human lung and intestinal organoids treated with LPS or Poly(I:C)