M2 Macrophages-Derived Exosomes Inhibited Podocyte Pyroptosis via lncRNA AFAP1-AS1/EZH2 Axis

Area of Science:

• Nephrology
• Cell Biology
• Molecular Biology

Background:

• Macrophage infiltration is linked to podocyte injury in diabetic nephropathy (DN).
• The precise mechanisms by which macrophages influence podocyte damage in DN are not fully understood.
• This study investigates the interplay between macrophages and high glucose-induced podocyte dysfunction.

Purpose of the Study:

• To elucidate the role of macrophage-derived exosomes in high glucose-induced podocyte pyroptosis.
• To explore the underlying molecular mechanisms involving AFAP1-AS1, EZH2, and NLRP3.
• To identify potential therapeutic targets for mitigating kidney injury in DN.

Main Methods:

• Exosome identification (TEM, NTA, Western blot for CD9, CD63, CD81, Calnexin).
• Gene expression analysis (QRT-PCR for AFAP1-AS1).
• Protein analysis (Western blot for NLRP3, Cleaved caspase-1, GSDMD-N; Immunofluorescence for NLRP3/ASC co-localization).
• Functional assays (ELISA for IL-18, IL-1β; LDH assay for cytotoxicity).
• Molecular interaction studies (RNA pulldown for AFAP1-AS1/EZH2; ChIP for EZH2/H3K27me3 at NLRP3 promoter).

Main Results:

• AFAP1-AS1 expression was decreased in peripheral blood of DN patients.
• Exosomes from M2 macrophages with reduced AFAP1-AS1 exacerbated high glucose-induced podocyte pyroptosis.
• This exacerbation involved increased NLRP3 inflammasome activation (NLRP3, Cleaved caspase-1, GSDMD-N, IL-18, IL-1β, LDH).
• AFAP1-AS1 epigenetically repressed NLRP3 expression by interacting with EZH2 to regulate H3K27me3 at the NLRP3 promoter.

Conclusions:

• AFAP1-AS1, downregulated in DN patients, inhibits podocyte pyroptosis.
• Macrophage-derived exosomes carrying low AFAP1-AS1 promote DN-associated kidney injury.
• The AFAP1-AS1/EZH2/H3K27me3 pathway epigenetically regulates NLRP3, offering a novel therapeutic strategy for DN.