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Mitochondrial Dysfunction as a Driver of Meta-Inflammation in Aging: The Emerging Role of PDK4 in Bioenergetic
Md Riad Chowdhury1, Gui-Hwa Jeong2, In-Kyu Lee3
1Department of Biomedical Science, Graduate School, Kyungpook National University, Daegu 41944, Republic of Korea.
Abstract:
Aging is accompanied by a progressive decline in mitochondrial quality, bioenergetic flexibility, and stress resilience. Aging mitochondria are increasingly recognized as active inflammatory signaling platforms rather than passive targets of cellular damage. Excess mtROS, leaked mtDNA, defective mitophagy, altered NAD+ metabolism, and impaired pyruvate oxidation together create a cellular environment that favors persistent inflammatory activation. These signals engage NF-κB, NLRP3 inflammasome, cGAS-STING, and SASP pathways, allowing mitochondrial stress to spread from organelle dysfunction to tissue-level inflammation. Within this framework, pyruvate dehydrogenase kinase 4 (PDK4) is of particular interest because it directly controls mitochondrial pyruvate entry through inhibition of the pyruvate dehydrogenase complex. By phosphorylating and inhibiting the pyruvate dehydrogenase complex, PDK4 limits mitochondrial pyruvate oxidation and favors lactate accumulation, fatty acid utilization, and redox-inflammatory signaling. Recent work in senescent cells links PDK4-dependent lactate accumulation to NOX1-derived ROS and SASP activity, suggesting a direct route by which altered fuel handling may reinforce inflammation. Here, we review mitochondrial dysfunction as the organizing principle of age-associated meta-inflammation, discuss PDK4 as a central metabolic checkpoint, examine tissue-specific consequences in muscle, adipose tissue, brain, and kidney, and evaluate therapeutic strategies aimed at restoring mitochondrial function to suppress chronic inflammation and preserve healthspan.
Insights
Aging mitochondria trigger inflammation by releasing signals that activate inflammatory pathways. Pyruvate dehydrogenase kinase 4 (PDK4) is a key metabolic regulator that exacerbates this inflammation, highlighting potential therapeutic targets for age-related diseases.
Area of Science:
- Mitochondrial biology
- Cellular metabolism
- Inflammation and aging
Background:
- Aging leads to mitochondrial dysfunction, characterized by reduced quality, bioenergetic flexibility, and stress resilience.
- Mitochondria are now understood as active inflammatory signaling platforms, not just passive targets of damage.
- Factors like excess reactive oxygen species (ROS), leaked mitochondrial DNA (mtDNA), impaired mitophagy, altered NAD+ metabolism, and reduced pyruvate oxidation contribute to chronic inflammation.
Purpose of the Study:
- To review mitochondrial dysfunction as a central driver of age-associated meta-inflammation.
- To highlight pyruvate dehydrogenase kinase 4 (PDK4) as a critical metabolic checkpoint in this process.
- To examine tissue-specific impacts and evaluate therapeutic strategies for restoring mitochondrial function and healthspan.
Main Methods:
- Review of existing literature on mitochondrial dysfunction, inflammation, and metabolic pathways in aging.
- Analysis of the role of pyruvate dehydrogenase kinase 4 (PDK4) in regulating mitochondrial pyruvate metabolism.
- Examination of signaling pathways involved, including NF-κB, NLRP3 inflammasome, cGAS-STING, and senescence-associated secretory phenotype (SASP).
Main Results:
- Mitochondrial dysfunction promotes inflammation through various signals (mtROS, mtDNA, etc.), activating key inflammatory pathways.
- PDK4 inhibition of pyruvate dehydrogenase complex limits pyruvate oxidation, promoting lactate accumulation and inflammatory signaling.
- PDK4-dependent lactate accumulation is linked to ROS and SASP in senescent cells, reinforcing inflammation.
Conclusions:
- Mitochondrial dysfunction is a unifying principle of age-associated meta-inflammation.
- PDK4 acts as a crucial metabolic checkpoint, linking altered fuel handling to chronic inflammation.
- Targeting mitochondrial function and PDK4 may offer therapeutic strategies to combat inflammation and extend healthspan.
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