Differential IL-1β secretion by monocyte subsets is regulated by Hsp27 through modulating mRNA stability

Area of Science:

• Immunology
• Cell Biology

Background:

• Monocytes are key regulators of inflammation, with distinct subsets (classical, intermediate, non-classical) identified by CD14 and CD16 expression.
• Interleukin-1β (IL-1β) is a critical pro-inflammatory cytokine involved in immune responses and autoimmune diseases.
• Mechanisms controlling IL-1β secretion by different monocyte subsets are not fully understood.

Purpose of the Study:

• To investigate the mechanisms regulating IL-1β production in distinct human monocyte subsets.
• To identify factors contributing to the differential secretion of IL-1β by non-classical monocytes compared to other subsets.

Main Methods:

• Primary human monocytes (classical, intermediate, non-classical) were stimulated with LPS or LPS + BzATP.
• IL-1β production, LPS-sensing, caspase-1 activation, and P2X7R activity were measured.
• mRNA decay rates and the role of Hsp27 in IL-1β regulation were analyzed.

Main Results:

• Non-classical monocytes produced approximately 80% less IL-1β than intermediate or classical monocytes.
• LPS-sensing, caspase-1 activation, and P2X7R activity were comparable across monocyte subsets.
• Diminished IL-1β production in non-classical monocytes was attributed to 50% increased IL-1β mRNA decay rates, mediated by Hsp27.

Conclusions:

• Hsp27-mediated IL-1β mRNA decay is a key mechanism limiting IL-1β production in non-classical monocytes.
• The Hsp27 pathway represents a novel therapeutic target for managing conditions with dysregulated IL-1β.
• These findings advance the understanding of monocyte subset function in inflammation and disease pathogenesis.