Carboxymethyl Cellulose as a Food Emulsifier: Are Its Days Numbered?

Abstract

Carboxymethyl cellulose use in industry is ubiquitous. Though it is recognized as safe by the EFSA and FDA, newer works have raised concerns related to its safety, as in vivo studies showed evidence of gut dysbiosis associated with CMC's presence. Herein lies the question, is CMC a gut pro-inflammatory compound? As no work addressed this question, we sought to understand whether CMC was pro-inflammatory through the immunomodulation of GI tract epithelial cells. The results showed that while CMC was not cytotoxic up to 25 mg/mL towards Caco-2, HT29-MTX and Hep G2 cells, it had an overall pro-inflammatory behavior. In a Caco-2 monolayer, CMC by itself increased IL-6, IL-8 and TNF-α secretion, with the latter increasing by 1924%, and with these increases being 9.7 times superior to the one obtained for the IL-1β pro-inflammation control. In co-culture models, an increase in secretion in the apical side, particularly for IL-6 (692% increase), was observed, and when RAW 264.7 was added, data showed a more complex scenario as stimulation of pro-inflammatory (IL-6, MCP-1 and TNF-α) and anti-inflammatory (IL-10 and IFN-β) cytokines in the basal side was observed. Considering these results, CMC may exert a pro-inflammatory effect in the intestinal lumen, and despite more studies being required, the incorporation of CMC in foodstuffs must be carefully considered in the future to minimize potential GI tract dysbiosis.

Keywords: IL-6; IL-8; TNF-α; carboxymethyl cellulose; co-culture inflammation model; gut inflammation.

Figure 1

Cytotoxicity profile of CMC against the selected cell lines. Different letters represent the statistically significant differences (p < 0.05) found between concentrations for each cell line.

Figure 2

Relative percentage of cytokine production in the Caco-2 monolayer model in the tested conditions. Different letters represent the statistically significant differences (p < 0.05) found between conditions for each cytokine.

Figure 3

Hep G2 systemic cytotoxicity co-culture model. (a) Co-culture model membrane stability in the percentage of the initial TEER value. * Represents the statistically significant differences (p < 0.05) found between conditions in each sampling point. (b) Cytotoxicity profile of the evaluated samples against Hep G2 in the basolateral side of the co-culture model. The dotted line represents the 30% cytotoxicity limit as defined by the ISO 10993-5:2009 standard (ISO, 2009). Different letters represent the statistically significant differences (p < 0.05) found for each condition between sampling times. * Represents the statistically significant differences (p < 0.05) found between the test conditions and the blank (media) control.

Figure 4

RAW co-culture model quality control parameters. (a) Co-culture model membrane stability in the percentage of the initial TEER value. * Represents the statistically significant differences (p < 0.05) found between conditions in each sampling point. (b) Cytotoxicity profile of the evaluated samples against the RAW in the basolateral side of the co-culture model. The dotted line represents the 30% cytotoxicity limit as defined by the ISO 10993-5:2009 standard [37]. Different letters represent the statistically significant differences (p < 0.05) found for each condition between sampling times. * Represents the statistically significant differences (p < 0.05) found between the test conditions and the blank (media) control.

Figure 5

Cytokine production in the RAW complex co-culture model apical side by the Caco-2/HT29-MTX membrane. Different letters represent the statistically significant differences (p < 0.05) found between conditions for each cytokine.

Figure 6

Cytokine production in the RAW complex co-culture model basolateral compartment produced by RAW cells and detected by 13-analyte mouse multiplex panel. Different letters represent the statistically significant differences (p < 0.05) found between conditions for each cytokine.