An MD2-derived peptide promotes LPS aggregation, facilitates its internalization in THP-1 cells, and inhibits...

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• MD2 protein recognizes Gram-negative bacterial lipopolysaccharide (LPS).
• MD2 mediates pathogen internalization and clearance by host defense cells.
• Specific functional segments of MD2 for LPS interaction and internalization remain largely uncharacterized.

Purpose of the Study:

• To identify and characterize functional segments of MD2 involved in LPS binding and cellular internalization.
• To investigate the role of a specific MD2 peptide (MD54) in modulating LPS-induced inflammatory responses.
• To evaluate the therapeutic potential of MD54 in vivo.

Main Methods:

• Identification of a 16-residue peptide (MD54) from MD2 with heptad repeat and cationic residues.
• Design and synthesis of an MD54 analog (MMD54) for comparison.
• Assays for LPS aggregation and cellular internalization in THP-1 monocytes.
• Assessment of NF-κB translocation and pro-inflammatory cytokine production in cell lines.
• In vivo studies evaluating MD54 efficacy in a mouse model of LPS-induced inflammation.

Main Results:

• MD54, but not its analog MMD54, induced LPS aggregation and internalization in THP-1 cells.
• MD54 significantly inhibited LPS-induced NF-κB nuclear translocation and pro-inflammatory cytokine production in vitro.
• MD54 demonstrated protective effects and improved survival in mice challenged with LPS.

Conclusions:

• A short peptide (MD54) from MD2, featuring a heptad repeat sequence, effectively binds and aggregates LPS.
• MD54 facilitates LPS internalization and attenuates LPS-induced inflammatory responses both in vitro and in vivo.
• MD54 represents a potential therapeutic agent for managing Gram-negative bacterial infections and associated inflammation.