In Vitro Immunomodulatory Effect of Food Supplement from Aloe vera

Abstract

Food industries typically use Aloe vera as concentrated (100× to 200×) and dried powders in their final products. These powders are obtained by extrusion of Aloe inner leaf gel (ILG) or Aloe whole leaf (WLP); the juice is filtered through diatomaceous earth and activated carbon before spray drying at temperatures below 70 °C. In another process, Aloe inner leaf gel was dried at ~80 °C and mashed to a powder rich in high molecular weight fibres and soluble polysaccharides (ILF). In contrast to ILG and WLP, the ILF sample was cytotoxic for the human intestinal cell line Caco-2 (CC₅₀ = 1 g/l), even at concentrations below the recommended dose for human consumption. At lower concentrations (250 mg/l) with LPS challenged macrophage-like THP-1 cells decreased by 40% the release of the anti-inflammatory cytokine IL-10, whereas the release of the proinflammatory cytokine IL-1β increased by 35% (compared to untreated but challenged macrophage-like THP-1 cells). Unexpectedly, under the same conditions, the less cytotoxic ILG and WLP, both samples with a lower fibre content, significantly increased (up to 2.4 times) the release of IL-10, while the concentration of IL-1β remained unaltered and of TNFα decreased by 35%. Even more interesting is that a treatment of the ILF sample with activated carbon reduced its cytotoxicity and increased the IL-10 release (3.1 times). Based on these results, we suggest applying an activated carbon treatment on Aloe-starting products, which have high fibre content and have received high temperature treatment, in order to reduce their cytotoxicity and improve their immunomodulatory properties.

Figure 1

Metabolic activity (WST-1) of Caco-2 after 4 h exposure to differently treated Aloe-starting products and estimation of the cytotoxic concentration CC₅₀: ILG (dotted circle), ILF (square), ILF-c (up triangle), ILF-f (down triangle), and ILF-ac (dotted diamond). Values are expressed as mean ± 1.96∗SEM (n = 4).

Figure 2

Trypan blue stained cells with compromised membrane are blue: differentiated THP-1 (a). Differentiated THP-1 challenged with 1 μg/ml LPS and additionally exposed to 2 g/l (0.2×) WLP (b), 1 g/l (0.2×) ILG (c), and 25 mg/l (0.005×) ILF (d), respectively.

Figure 3

Trypan blue stained cells with compromised membrane are blue: differentiated THP-1 cells after being challenged for 24 h with 1 μg/ml LPS (a). Cells additionally exposed to 10 g/l (1×) WLP (b), 5 g/l (1x) ILG (c), and 5 g/l (1×) ILF (d), respectively.

Figure 4

Trypan blue stained cells with compromised membrane are blue: differentiated THP-1 cells challenged with 1 μg/ml LPS and additionally exposed to 1 g/l (0.2×) ILF (a) and 1 g/l (0.2×) ILF-ac, respectively.

Figure 5

Changes in TNFα release after 24 h from differentiated THP-1 cells induced by a treatment with different Aloe vera products and LPS stimulation (left columns) compared to that without LPS stimulation (right columns). 1x refers to the recommended concentration for human consumption: control without Aloe vera treatment (black), WLP (grey), ILG (light grey), ILF (rhombus patterned), and ILF-ac (horizontally lined) columns. Values are expressed as mean ± 1.96∗SEM (n = 3).

Figure 6

Changes in IL-1β release after 24 h from differentiated THP-1 cells induced by a treatment with different Aloe vera products and LPS stimulation (left columns) compared to that without LPS stimulation (right columns). 1x refers to the recommended concentration for human consumption: control without Aloe vera treatment (black), WLP (grey), ILG (light grey), ILF (rhombus patterned), and ILF-ac (horizontally lined) columns. Values are expressed as mean ± 1.96∗SEM (n = 3).

Figure 7

Changes in IL-10 release after 24 h from differentiated THP-1 cells induced by a treatment with different Aloe vera products and LPS stimulation (left columns) compared to that without LPS stimulation (right columns). 1x refers to the recommended concentration for human consumption: control without Aloe vera treatment (black), WLP (grey), ILG (light grey), ILF (rhombus patterned), and ILF-ac (horizontally lined) columns. Values are expressed as mean ± 1.96∗SEM (n = 3).