Improved Isolation Optimizes Downstream Application of Extracellular Vesicles Derived from Mycobacterium tuberculosis

Area of Science:

• Microbiology
• Immunology
• Neuroscience

Background:

• Mycobacterium tuberculosis (Mtb) secretes extracellular vesicles (EVs) involved in host-pathogen interactions.
• Effective isolation of Mtb EVs is crucial for understanding their role in tuberculosis pathogenesis.
• Existing isolation methods vary in efficiency and the characterization of Mtb EV components.

Purpose of the Study:

• To compare the effectiveness of different methods for isolating Mtb EVs.
• To investigate the interaction of Mtb EVs with host cells, specifically macrophages.
• To determine if Mtb EVs can breach the blood-brain barrier and induce neuroinflammation.

Main Methods:

• Comparison of exosome isolation kit (EI), differential centrifugation (DC), and ultrafast-isolation system (EXODUS) for Mtb EV isolation.
• Analysis of Mtb EV components using the EXODUS method.
• Macrophage (RAW264.7) internalization assays and TLR2 signaling pathway analysis.
• In vivo studies assessing Mtb EV translocation across the blood-brain barrier and subsequent neuroinflammation.

Main Results:

• The exosome isolation kit (EI) yielded higher EV numbers than DC or EXODUS.
• EXODUS revealed a greater abundance of H37Rv components within EVs compared to DC and EI.
• Mtb EVs were internalized by macrophages, activating TLR2 signaling and inducing IL-6 and TNF-α.
• Mtb EVs crossed the blood-brain barrier, reaching the brain within 12 hours and causing sustained neuroinflammation for up to 6 days.

Conclusions:

• Different Mtb EV isolation techniques impact yield and component analysis.
• Mtb EVs play a significant role in macrophage activation and inflammatory responses.
• Mtb EVs can transmigrate the blood-brain barrier, contributing to Mtb-induced neuroinflammation.
• These findings provide insights into Mtb pathogenesis and potential therapeutic targets.