Chondroitin sulfate intake inhibits the IgE-mediated allergic response by down-regulating Th2 responses in mice

Abstract

Chondroitin sulfate (CS) was administered orally to BALB/c mice immunized intraperitoneally with ovalbumin (OVA) and/or dinitrophenylated OVA. The titers of antigen-specific IgE and IgG1 in mouse sera were determined. The antigen-specific IgE production by mice fed ad libitum with CS was significantly inhibited. We also examined the effect of feeding CS on immediate-type hypersensitivity. One hour after antigen stimulation, the ears of mice fed with CS swelled less than those of the control mice. Furthermore, the rise in serum histamine in the mice fed with CS under active systemic anaphylaxis was significantly lower than that in the controls. We next examined the pattern of cytokine production by splenocytes from mice followed by re-stimulation with OVA in vitro. The splenocytes from the mice fed with CS produced less interleukin (IL)-5, IL-10, and IL-13 than those from the control group. In contrast, the production of interferon-gamma and IL-2 by the splenocytes of mice fed with CS was not significantly different from those in the control mice. In addition, the production of transforming growth factor-beta from the splenocytes of mice fed with CS was significantly higher than that of the control mice. Furthermore, we showed that the percentages of CD4(+) cells, CD8(+) cells, and CD4(+)CD25(+) cells in the splenocytes of mice fed with CS are significantly higher than those of the control. These findings suggest that oral intake of CS inhibits the specific IgE production and antigen-induced anaphylactic response by up-regulating regulatory T-cell differentiation, followed by down-regulating the Th2 response.

FIGURE 1. ¹H NMR spectrum of CS recorded in ²H₂O at 333 K

The peaks are labeled according to the main corresponding residues in the structure and the resonating proton. The height of the NHCOCH₃ peak has been reduced to one-third to be in scale.

FIGURE 2. Effects of CS on the serum antigen-specific antibody titer in secondary immune response

Bars represent mean values ± S.D. of five mice. CS (400 mg/kg/day) was administered by gavage from the first immunization to 7 days after the second immunization.

FIGURE 3. Effects of CS on the serum antigen-specific antibody titer in secondary immune response

Bars represent mean values ± S.D. of 10 mice. CS was administered orally ad libitum from 7 days before the first immunization to 7 days after the second immunization. Asterisks indicate the significance of difference from the control value (**, p < 0.01; *, p < 0.05).

FIGURE 4. Effects of CS on the immunized mice ear swelling responses 1 h after epicutaneous challenge with picryl chloride

Bars represent mean values ± S.D. of five mice (ten ears). CS was administered orally ad libitum from the first immunization. *, p < 0.05 compared with control (saline).

FIGURE 5. Effect of CS on the serum histamine concentrations in the OVA-challenged mice

Serum samples were collected after 10-min intraperitoneal administration of OVA. Bars represent mean values ±S.D. of four mice. CS was orally ad libitum administered from the first immunization to the time of the active systemic anaphylaxis test. Mice were challenged with 1 mg of antigen. Asterisks indicate the significance of difference from the control value (**, p< 0.01; *, p < 0.05).

FIGURE 6. Effects of CS administration on the cytokineproduction of splenocytes in vitro

BALB/cmice (n=5) were intraperitoneally injected on days 0 and 10 with 20μg of OVA and 2mg of Al(OH)₃ at a total volume of 400μl, and CS was orally ad libitum administered from 7 days before first immunization to 7 days after the second immunization. Splenocytes (5.0×10⁶ cells/ml)were collected on day 18 and were co-cultured with OVA (final, 100μg/ml). The amounts of cytokines in the supernatant were measured by enzyme-linked immunosorbent assay. Asterisks indicate the significance of difference from the control value (**, p<0.01; *, p<0.05). Bars represent mean values (±S.D.) for six wells.

FIGURE 7. Expression of CD4 and CD25 on splenocytes from the BALB/c mice

Splenocytes were isolated from the control group (a) and the CS group (b). The histograms are representatives of five independent experiments.