In vitro anti-inflammatory effects of curcumin on mast cell-mediated allergic responses via inhibiting FcεRI protein expression and protein kinase C delta translocation

Abstract

Allergy is a hypersensitivity reaction when exposed to certain environmental substances. It shows high relation between immunoglobulin E (IgE) binding to a specific receptor (FcεRI), pro-inflammatory cytokines, and mediators with allergic inflammation responses. Curcumin is a yellow pigment isolated from the turmeric. Curcumin possesses antioxidant and anti-inflammatory properties as well as exhibits significant chemopreventive activity. This study was aimed to investigate the in vitro assessment of the regulation of curcumin on allergic inflammatory responses on rat basophil leukemia (RBL)-2H3 and human pre-basophils (KU812) cell lines. Curcumin showed the activity against histamine and β-hexosaminidase releases from both IgE-mediated and A23187-induced cells degranulation. The morphological observation also confirmed that curcumin inhibits cells degranulation. IgE-mediated allergic responses and significantly induced mast cells intracellular reactive oxygen species (ROS) production. Curcumin reduced ROS production from IgE-mediated or A23187-induced cells degranulation. Curcumin also successfully reduced FcεRI expressions and some pro-inflammatory cytokines, such as interleukin (IL)-4 and IL-13. Furthermore, curcumin inhibited protein kinase C (PKC)-δ translocation from cytosolic to particulate. These results suggested that curcumin can alleviate both the IgE-mediated and calcium ionosphere A23187-stimulated allergic responses through reducing the release of the allergic mediators.

Keywords: Allergic responses; Curcumin; Degranulation; Immunoglobulin E; Protein kinase C.

Fig. 1

Effects of curcumin on cells viability. a 2 × 10⁵ cells/mL of RBL-2H3 cells were co-cultured with curcumin for short-term; b 5 × 10⁵ cells/mL of KU812 cells were co-cultured with curcumin for 24 h. Data are shown as the mean ± standard deviation (SD) of three independent experiments

Fig. 2

Morphological observation of curcumin suppressed IgE-mediated degranulation on RBL-2H3 cells. Normal, unstimulated group

Fig. 3

Morphological observation of curcumin suppressed A23187-induced degranulation on RBL-2H3 cells. Normal, unstimulated group

Fig. 4

Effects of curcumin on histamine release of RBL-2H3 cells. a IgE-mediated and b A23186-induced histamine releases. Data are shown as the mean ± standard deviation (SD) of three independent experiments. N, normal (unstimulated) group; PC; positive control (untreated, 0 µM) groups

Fig. 5

The β-hexosaminidase releases stimulated by anti-DNP IgE/DNP-BSA on RBL-2H3 cells. a Optimal concentration curve; b after treated by curcumin. Data are shown as the mean ± standard deviation (SD) of three independent experiments. N, normal (unstimulated) group; PC; positive control (untreated, 0 µM) groups

Fig. 6

The β-hexosaminidase releases stimulated by A23187 on RBL-2H3 cells. a The optimal concentration of A23187; b after treated by curcumin. Data are shown as the mean ± standard deviation (SD) of three independent experiments. N, normal (unstimulated) group; PC; positive control (untreated, 0 µM) groups

Fig. 7

Effect of curcumin on reactive oxygen species (ROS) production in RBL-2H3 cells. a Anti-DNP IgE/DNP-BSA-triggered and b A23187-triggered ROS production; c catalase activity. Data are shown as the mean ± standard deviation (SD) of three independent experiments. N, normal (unstimulated) group

Fig. 8

Effects of curcumin on the gene expression of IL-4 and IL-13 mRNAs in KU812 cells. a RT-PCR bands; b IL-4 expression; and c IL-13 expression. Different letter (A, B) and (a–d) indicate the significant difference (P < 0.0001). N, Normal (unstimulated) group; PC, positive control (untreated, 0 µM) group

Fig. 9

Effects of curcumin on the expression of FcεRI mRNAs in KU812 cells. a Treated for 12 h and b 24 h; c immunoblot analysis of the expression the cellular FcεRI α chain protein. Different letter (A, B) and (a–d) indicate the significant deference at P < 0.005 and P < 0.0001, respectively. Data are shown as the mean ± standard deviation (SD) of three independent experiments. Control, untreated (0 µM) group

Fig. 10

Effect of curcumin on PKC-δ translocation induced by antigen in RBL-2H3 cells