High-throughput bioprinted 3D cultures for probing host-pathogen interactions in bioinspired microenvironments

Area of Science:

• Biotechnology
• Immunology
• Biomaterials Science

Background:

• The immune cell microenvironment critically regulates immune cell function and fate.
• Three-dimensional (3D) culture systems offer insights into immune responses within tissue-mimicking environments.
• Current 3D models often lack high-throughput capabilities, hindering broad application in host-pathogen interaction studies.

Purpose of the Study:

• To establish a high-throughput macrophage-bacteria co-culture model mimicking lung tissue stiffness.
• To investigate how varying microenvironment stiffness affects macrophage behavior and response to bacterial infection.
• To provide a platform for studying host-pathogen interactions and developing therapeutic strategies.

Main Methods:

• Utilized bioprinting to encapsulate and differentiate human THP-1 monocytes into macrophages within synthetic extracellular matrices (ECMs).
• Fabricated ECMs with defined polymer and peptide bioinks in a 96-well plate format to mimic healthy (compliant) and diseased (stiff) lung tissue stiffness.
• Assessed macrophage viability, immunocompetence (phenotype, phagocytosis, response to stimuli), and gene expression.
• Studied the immune response of macrophages to *Pseudomonas aeruginosa* infection in different stiffness conditions.

Main Results:

• Macrophages maintained viability and immunocompetence in the 3D culture system.
• Macrophages in stiffer (fibrosis-inspired) ECMs showed higher basal expression of inflammation and fibrosis genes compared to compliant (healthy lung-inspired) ECMs.
• In response to *P. aeruginosa*, macrophages in stiff microenvironments exhibited altered cytokine secretion (decreased IL-6/IL-1β, increased IL-10/TNF-α) compared to compliant environments.

Conclusions:

• The developed high-throughput 3D model effectively mimics lung tissue stiffness and allows for controlled study of host-pathogen interactions.
• Microenvironment stiffness significantly influences macrophage immune responses, including gene expression and cytokine profiles during bacterial infection.
• This platform facilitates understanding of bacterial infections and aids in identifying potential therapeutic strategies.