Oxidized Polyunsaturated Fatty Acids Promote Colitis and Colitis-Associated Tumors in Mice
Overview
This study demonstrates that oxidized polyunsaturated fatty acids (PUFAs), but not unoxidized PUFAs, exacerbate colitis severity and promote colitis-associated colorectal cancer in murine models. The effects are mediated through Toll-like receptor 4 (TLR4) signaling and alterations in gut microbiota.
Background
Inflammatory bowel disease (IBD) is a chronic intestinal inflammation linked to increased colorectal cancer risk. Epidemiological data suggest high PUFA intake correlates with higher IBD incidence, but the role of oxidized versus unoxidized PUFA remains unclear. PUFAs are prone to oxidation during food processing and storage, generating oxidized compounds that may influence disease development. This study investigates the differential impact of unoxidized and oxidized PUFAs on colitis and tumorigenesis using mouse models.
Data Highlights
Parameter
Unoxidized PUFA Diet
Oxidized PUFA Diet
Peroxide Value (PV) of Oils
Low (purified corn oil)
~10 mEq/kg (oxidized corn oil)
Colitis Severity (DSS and IL-10 KO models)
No significant increase
Significant increase
Colitis-Associated Tumor Development
No promotion
Exacerbated tumorigenesis
Intestinal Barrier Dysfunction
Not observed
Increased dysfunction and bacterial translocation
Effect in TLR4 Knockout Mice
Not applicable
No promotion of colitis
Effect in Germ-Free Mice
Not applicable
No promotion of colitis
Key Findings
Dietary oxidized PUFA at human-relevant consumption levels increases colitis severity in DSS-induced and IL-10 knockout mouse models.
Oxidized PUFA exacerbates colitis-associated colorectal tumor development, whereas unoxidized PUFA does not promote tumorigenesis.
Oxidized PUFA worsens intestinal barrier dysfunction, leading to increased bacterial translocation.
The pro-colitic effects of oxidized PUFA require Toll-like receptor 4 (TLR4) signaling, as TLR4 knockout mice are protected.
Oxidized PUFA alters gut microbiota diversity and composition; germ-free mice do not develop colitis upon oxidized PUFA exposure.
Clinical Implications
These findings suggest that oxidized PUFAs, commonly present in stored or processed foods, may be a modifiable dietary risk factor for IBD and colitis-associated colorectal cancer. Clinicians should consider the oxidative status of dietary fats when advising patients with or at risk for IBD. Regulatory policies and food industry standards may need revision to limit oxidized PUFA levels in food products to reduce IBD risk.
Conclusion
Oxidized polyunsaturated fatty acids promote colitis and colitis-associated tumorigenesis in mice through mechanisms dependent on TLR4 signaling and gut microbiota alterations. This highlights the importance of considering lipid oxidation in dietary risk assessments for inflammatory bowel disease.
References
Human Studies on PUFA Intake and IBD Risk
European Prospective Investigation into Cancer and Nutrition (EPIC) Study
Prior Study on Unoxidized PUFA and Colitis in IL-10−/− Mice
by Weicang Wang, Yuxin Wang, Katherine Z Sanidad, Yige Wang, Jianan Zhang, Wenqi Yang, Quancai Sun, Ipek Bayram, Renhua Song, Haixia Yang, David Johnson, Heather L Sherman, Daeyoung Kim, Lisa M Minter, Justin J-L Wong, Melody Y Zeng, Eric A Decker, Guodong Zhang
