Abstract
Carotenoids are naturally occurring pigments in plants and are responsible for the orange, yellow, and red color of fruits and vegetables. Carrots are one of the primary dietary sources of carotenoids. The biological activities of carotenoids in higher organisms are well documented in most tissues but not the large intestine. The gastrointestinal barrier acts as a line of defense against the systemic invasion of pathogenic bacteria, especially at the colonic level. Proteins involved in tight junction assembly between epithelial cells and mucus secretion from goblet cells are essential for maintaining intestinal barrier homeostasis. A high-fat diet can cause gut impairment by inducing barrier permeability, leading to low-grade chronic inflammation via metabolic endotoxemia. Our hypothesis for this study is that the dietary intake of carotenoid-rich foods can alleviate obesity-associated gut inflammation and strengthen the intestinal barrier function. Male C57BL/6J mice were randomized to one of four experimental diets for 20 weeks (n = 20 animals/group): Low-fat diet (LFD, 10% calories from fat), high-fat diet (HFD, 45% calories from fat), HFD with white carrot powder (HFD + WC), or HFD with orange carrot powder (HFD + OC). Colon tissues were harvested to analyze the biochemical effects of carotenoids in carrots. The distal sections were subjected to isobaric labeling-based quantitative proteomics in which tryptic peptides were labeled with tandem mass tags, followed by fractionation and LC-MS/MS analysis in an Orbitrap Eclipse Tribrid instrument. High-performance liquid chromatography results revealed that the HFD+WC pellets were carotenoid-deficient, and the HFD+OC pellets contained high concentrations of provitamin A carotenoids, specifically α-carotene and β-carotene. As a result of the quantitative proteomics, a total of 4410 differentially expressed proteins were identified. Intestinal barrier-associated proteins were highly upregulated in the HFD+OC group, particularly mucin-2 (MUC-2). Upon closer investigation into mucosal activity, other proteins related to MUC-2 functionality and tight junction management were upregulated by the HFD+OC dietary intervention. Collectively, our findings suggest that carotenoid-rich foods can prevent high-fat diet-induced intestinal barrier disruption by promoting colonic mucus synthesis and secretion in mammalian organisms. Data are available via ProteomeXchange with identifier PXD054150.
Competing Interest Statement
The authors have declared no competing interest.
Abbreviations
- ACOX1
- Acyl-Coenzyme A oxidase 1
- AGR2
- Anterior gradient protein 2 homolog
- ALDH1A2
- Retinal dehydrogenase 2
- ALDH1A3
- Aldehyde dehydrogenase 3
- BCO1
- ꞵ-carotene 15,15’-dioxygenase
- CAMKK2
- Calcium/calmodulin-dependent protein kinase kinase 2
- CAT
- Catalase
- CD36
- Cluster determinant 36
- CLCA1
- Calcium-activated chloride channel regulator 1
- CLDN1
- Claudin-1
- CLDN3
- Claudin-3
- CLDN7
- Claudin-7
- CPT1A
- Carnitine O-palmitoyltransferase
- CPT2
- Choline/carnitine acyltransferase domain-containing protein
- CRP
- C-reactive protein
- DHRS
- Dehydrogenase/reductase SDR
- DRG1
- Developmentally-regulated GTP-binding protein 1
- ERK2
- Extracellular signal-regulated kinase 1
- FABP2
- Intestinal fatty acid binding protein
- FASN
- Fatty acid synthase
- FCGBP
- Iggfc-binding protein
- Fut2
- Galactoside alpha-(1,2)-fucosyltransferase 2
- GPX1
- Glutathione peroxidase 1
- HFD
- High fat diet
- HT-29
- Human adenocarcinoma colon epithelial cells
- IBD
- Inflammatory bowel disease
- IKBKB/IKK-ꞵ
- Inhibitor of kinase NF-κb subunit beta
- IL-6
- Interleukin 6
- IL1RN
- Interleukin 1 receptor antagonist
- ISX
- Intestine-specific homeobox
- JAK2
- Tyrosine-protein Janus Kinase 2
- JNK
- Jun N-terminal kinase
- KEAP1
- Kelch-like ECH associated protein
- KEGG
- Kyoto Encyclopedia of Genes and Genomes.
- KLK1
- Kallikrein-1
- LBP
- Lipopolysaccharide-binding protein
- LC-MS/MS
- Liquid Chromatography with tandem mass spectrometry
- LFD
- Low fat diet
- LPS
- Lipopolysaccharide
- MAPK
- Mitogen-activated protein kinase
- MCAM
- Mucin 18
- MPTX
- Mucosal pentraxin
- MUC-2
- Mucin-2
- MUC13
- Mucin 13
- MUC3
- Mucin 3
- MUC4
- Mucin 4
- MYD88
- Myeloid differentiation primary response 88
- NQO1
- NAD(P)H quinone dehydrogenase 1
- NF-κb
- Nuclear factor kappa-light-chain-enhancer of activated B cells
- NFKB1
- NF-κb p105 subunit
- NOS1
- Nitric oxide synthase
- OC
- Orange carrot
- OCLN
- Occludin
- PRDX1
- Peroxiredoxin-1
- RDH
- Retinol dehydrogenase
- RXRꞵ
- Retinoid X receptor beta
- SCD2
- Stearoyl-Coenzyme A desaturase 2
- SOD1
- Superoxide dismutase
- SR-B1
- Scavenger receptor class B type 1
- STAT3
- Signal transducer and activator of transcription 3
- TAB1
- Transforming growth factor- β-activated kinase 1 regulatory subunit
- TJP1
- Zonula occludens-1
- TJP2
- Zonula occludens-2
- TLR
- Toll-like receptor
- TLR4
- Toll-like receptor 4
- Tmtpro
- Tandem Mass Tag pro
- TRX1
- Thioredoxin
- WC
- White carrot
- ZG16
- Zymogen granule membrane protein 16