Cholesterol suppresses human iTreg differentiation and nTreg function through mitochondria-related mechanisms

Area of Science:

• Immunology
• Cardiovascular Research
• Cell Biology

Background:

• Cholesterol exacerbates inflammation in atherosclerosis (AS) by increasing IL-1β secretion from macrophages.
• The impact of cholesterol on regulatory T cells (Tregs) in AS remains poorly understood.
• This study investigates cholesterol's effects on both induced Tregs (iTregs) and natural Tregs (nTregs).

Purpose of the Study:

• To elucidate the mechanisms by which cholesterol affects Treg differentiation and function.
• To explore the role of mitochondrial reactive oxygen species (mtROS) in cholesterol-induced Treg dysfunction.
• To evaluate the therapeutic potential of targeting mtROS in cholesterol-mediated inflammation.

Main Methods:

• Flow cytometry assessed iTreg differentiation.
• Western blotting and RT-qPCR measured HIF-1α expression.
• Mitochondrial function was analyzed using TMRM/mitoSOX staining, Seahorse assays, and electron microscopy.
• Immunoregulatory capacity was evaluated via co-culture assays and ELISA.
• Reporter cell lines were generated for mechanistic studies.

Main Results:

• Cholesterol treatment suppressed iTreg differentiation and impaired nTreg immunosuppressive function.
• Cholesterol induced mtROS production, inhibiting HIF-1α degradation and Treg differentiation.
• Mitochondrial oxidative damage by cholesterol compromised nTreg function in inhibiting T cell proliferation and promoting macrophage anti-inflammatory activity.
• MitoTEMPO (MT), an mtROS scavenger, restored iTreg differentiation and protected nTregs.

Conclusions:

• Cholesterol aggravates AS inflammation by negatively impacting both iTregs and nTregs.
• mtROS play a critical role in cholesterol-induced Treg dysfunction.
• MitoTEMPO shows promise as an anti-atherogenic therapeutic agent by mitigating cholesterol's detrimental effects on Tregs.