How Do Lipid Metabolic Pathways Contribute to Inflammation?
The body's ability to mount, sustain, and crucially switch off inflammation depends on a vast well-managed economy of lipids. At the centre of that system sits the peroxisome, a tiny organelle whose lipid-metabolic role turns out to be a powerful lever on inflammation.
The Peroxisome: A Small Organelle with an Outsized Role
Peroxisomes are membrane-bound compartments found in virtually every cell of the body. They perform lipid-processing reactions that no other organelle can, breaking down lipids that would otherwise accumulate to toxic levels, and producing specialized lipids the cell cannot make anywhere else.
The Lipid Metabolic Reactions Only Peroxisomes Can PerformLipids are far more than stored energy, they are structural components, signaling molecules, and precursors for a wide range of bioactive compounds.
Several key lipid reactions occur exclusively in peroxisomes:
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Beta-oxidation of very-long-chain fatty acids (VLCFAs). VLCFAs cannot be broken down by mitochondria; peroxisomes shorten them step by step.
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Alpha-oxidation of branched-chain fatty acids such as phytanic acid, a dietary lipid methyl branch blocks conventional breakdown.
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Bile acid synthesis, essential for digesting dietary fats.
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Processing of polyunsaturated fatty acids (PUFAs) and turnover of eicosanoids, a family of lipid signals.
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Synthesis of ether phospholipids (plasmalogens) and the final step in producing docosahexaenoic acid (DHA), an omega-3 fatty acid vital to the brain and retina.
Many of these same lipids double as immune signals, which places peroxisomes squarely at the interface of metabolism and inflammation. Inflammation is protective in short, controlled bursts, but damaging when it fails to resolve. Peroxisomal lipid handling helps keep that balance through three interlocking mechanisms.
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Clearing Lipotoxic and Pro-Inflammatory Species.
When VLCFA beta-oxidation fails, the accumulating fatty acids are anything but inert. They are lipotoxic: they destabilize membranes, drive oxidative stress, and engage innate immune pathwyas, including Toll-like receptor signaling that activates NF-κB, a master transcriptional switch for inflammatory genes.
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Supplying Pro-Resolving Lipid Mediators
DHA produced in peroxisomes is the substrate for specialized pro-resolving mediators, molecules such as resolvins, protectins, and maresins that actively terminate inflammation once a threat has passed. With fewer peroxisomes, a cell loses part of its capacity not just to avoid inflammation, but to actively shut it down.
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Buffering Oxidative Stress
Plasmalogens act as endogenous antioxidants, absorbing reactive molecules that would otherwise damage the cell. Their loss shifts cells toward a more oxidized, pro-inflammatory state.
Where Inflammation & Peroxisomal Lipid Metabolism meet
Inside Our Research
Our work has established that peroxisomal metabolism is required for inflammatory processes across distinct cell types and tissues.
Macrophages: Gatekeepers of the First-Line Response
Macrophages engulf and destroy microbes through phagocytosis. We found that peroxisomes are essential for this process, a requirement conserved from fruit flies to mice. Without functional peroxisomes, macrophages could neither generate the normal burst of reactive oxygen and nitrogen species used to attack pathogens, nor resolve that burst afterward; reactive species instead remained chronically elevated. Because these signals also drive cytoskeletal remodeling and downstream NF-κB activation, the cells failed both to engulf bacteria and to switch on their antimicrobial gene program. Tellingly, supplying peroxisome-derived lipids, including DHA, restored their phagocytic capacity, pointing directly to the lipids as the missing link.
Microglia: A Fatty-Acid Link to Brain Inflammation
Microglia are the immune cells of the central nervous system. We demonstrated a direct connection between disrupted fatty-acid breakdown and neuroinflammation: microglia lacking key VLCFA beta-oxidation machinery (ABCD1, ABCD2, or ACOX1) produced elevated reactive oxygen and nitrogen species even at baseline, overreacted to immune stimulation, and secreted factors that triggered the death of neighboring neurons and oligodendrocytes. This helps explain the early neurodegenerative events in X-linked adrenoleukodystrophy (X-ALD), a severe peroxisomal disorder.
The Intestine: Barrier Integrity and Immune Balance
In the gut, epithelial cells with dysfunctional peroxisomes accumulate free fatty acids and hydrogen peroxide, triggering Tor-dependent autophagy, tissue damage, microbial imbalance (dysbiosis), and a weakened immune response. We further showed that peroxisomal cholesterol metabolism regulates Hippo/YAP signaling to maintain the intestinal barrier, a process disrupted in Crohn's disease. These findings align with mounting evidence that peroxisome-derived PUFAs such as EPA and DHA feed both the pro-resolving and pro-inflammatory lipid-mediator pools.
The Bigger Picture: A Metabolic Control Point for Inflammation
Taken together, these studies reveal peroxisomes as a hidden control point for inflammation. By governing the cell's lipids and reactive-species signaling, they help the immune system escalate when necessary and stand down once the danger has passed. By mapping precisely how peroxisomal lipids and reactive species shape this response, our research aims to establish peroxisomal lipid metabolism as a therapeutic target for regulating inflammation, and the many diseases in which it goes awry.
Peroxisome-Mediated Metabolism Is Required for Immune Response to Microbial Infection.
Modulation of the cell membrane lipid milieu by peroxisomal β-oxidation induces Rho1 signaling to trigger inflammatory responses
Impaired peroxisomal beta-oxidation in microglia triggers oxidative stress and impacts neurons and oligodendrocytes
Peroxisome Injury in Multiple Sclerosis: Protective Effects of 4-Phenylbutyrate in CNS-Associated Macrophages