MicroRNA-22 negatively regulates LPS-induced inflammatory responses by targeting HDAC6 in macrophages

Area of Science:

• Molecular Biology
• Immunology
• Biochemistry

Background:

• Histone deacetylase 6 (HDAC6) dysregulation is implicated in various diseases, including cancer and inflammatory conditions.
• Understanding the molecular mechanisms controlling inflammatory responses in macrophages is crucial for disease management.

Purpose of the Study:

• To investigate the regulatory role of microRNA-22 (miR-22) in controlling HDAC6-mediated expression of pro-inflammatory cytokines.
• To elucidate the specific molecular interactions between miR-22, HDAC6, and inflammatory signaling pathways in macrophages stimulated with lipopolysaccharide (LPS).

Main Methods:

• Utilized luciferase reporter assays to confirm miR-22 targeting of HDAC6.
• Employed miR-22 mimics and inhibitors to modulate miR-22 levels in LPS-stimulated macrophages.
• Assessed the impact of miR-22 modulation on HDAC6 expression, NF-κB and AP-1 activation, and pro-inflammatory cytokine (TNF-α, IL-1β, IL-6) production.

Main Results:

• LPS stimulation increased HDAC6 and decreased miR-22 expression in macrophages.
• miR-22 directly targets the 3'UTR of HDAC6, inhibiting its expression.
• miR-22 mimic transfection suppressed LPS-induced HDAC6 expression, NF-κB/AP-1 activation, and pro-inflammatory cytokine release, while miR-22 inhibition exacerbated these effects.

Conclusions:

• miR-22 acts as a negative regulator of LPS-induced pro-inflammatory cytokine production in macrophages.
• The mechanism involves miR-22 targeting of HDAC6, leading to the suppression of the NF-κB and AP-1 signaling pathways.
• These findings highlight the miR-22/HDAC6 axis as a potential therapeutic target for inflammatory diseases.