The Role of β-Carotene in Colonic Inflammation and Intestinal Barrier Integrity

Abstract

Background: Carotenoids are naturally occurring pigments accounting for the brilliant colors of fruits and vegetables. They may display antioxidant and anti-inflammatory properties in humans besides being precursors to vitamin A. There is a gap of knowledge in examining their role within colonic epithelial cells. We proposed to address this research gap by examining the effects of a major dietary carotenoid, β-carotene, in the in vitro epithelial cell model.Methods: We examined the function of β-carotene in the lipopolysaccharide (LPS)/toll-like receptor 4 (TLR4) signaling pathway. We conducted western blotting assays to evaluate expressions of TLR4 and its co-receptor, CD14. We also examined NF-κB p65 subunit protein levels in the model system. Furthermore, we studied the impact of β-carotene on the tight junction proteins, claudin-1, and occludin. We further carried out immunocytochemistry experiments to detect and visualize claudin-1 expression.Results: β-Carotene reduced LPS-induced intestinal inflammation in colonic epithelial cells. β-Carotene also promoted the levels of tight junction proteins, which might lead to enhanced barrier function.Conclusions: β-Carotene could play a role in modulating the LPS-induced TLR4 signaling pathway and in enhancing tight junction proteins. The findings will shed light on the role of β-carotene in colonic inflammation and also potentially in metabolic disorders since higher levels of LPS might induce features of metabolic diseases.

Micronutrient Improvement of Epithelial Barrier Function in Various Disease States: A Case for Adjuvant Therapy

“…In Caco-2 cell layers challenged by endotoxin, pretreatment with Vitamin A significantly offset the ensuant TER reduction and reduced the decrease of occludin, claudin-1 and ZO-1 expression produced by endotoxin [ 336 ]. A similar finding was made in the HT-29 model with LPS and Vitamin A [ 337 ]. Similarly, Caco-2 cell layers made leaky (decreased TER) by exposure to Clostridium difficile toxin A were less leaky in the presence of Vitamin A [ 338 ].…”

Identification of promising nutraceuticals against filarial immune-modulatory proteins: insights from in silico and ex vivo studies

“…β-Carotene can also decrease the transcription of pro-inflammatory cytokine genes interleukin-1β (IL-1β), IL-6 and tumor necrosis factor alpha (TNF-α). 42 A reverse correlation between plasma β-carotene and C-reactive protein (CRP) has been reported earlier. 43 In LF it has been observed that CRP is over expressed in all clinical stages and the expression in chronic cases is almost double that of normal serum samples.…”

Potential role of inflammation in relation to dietary sodium and β-carotene with non-alcoholic fatty liver disease: a mediation analysis

“…If this hypothesis is true, down regulating inflammation will improve hepatic steatosis caused by high sodium intake. β-carotene, a retinol precursor and antioxidant that is found in certain fruits and vegetables, has been found to have a strong anti-inflammatory effect [15][16][17]. Our second hypothesis, accordingly, is that high dietary β-carotene intake attenuates the effects of high sodium intake on NAFLD by down regulating inflammation.…”