OBJECTIVETo observe the effect of intestinal trefoil factor (ITF) combined with mucin on immune function of intestinal epithelial cells (IEC) after being treated with burn rat serum.

METHODSThe rat IEC-6 cell lines were divided into control group (C, cultured in DEME medium containing 10% calf serum), burn control group (BC, cultured in DEME medium containing 10% burn rat serum), burn serum + ITF group (B + I, cultured in DEME medium containing 10% burn rat serum and 25 microg/mL ITF), burn serum + mucin group (B + M, cultured in DEME medium containing 10% burn rat serum and 250 microg/mL mucin), and burn serum + ITF + mucin group (B + I + M, cultured in DEME medium containing 10% burn rat serum, 25 microg/mL ITF, and 250 microg/mL mucin) according to the random number table. Meanwhile, 200 microL suspension of E. coli with density of 1 x 10(8) CFU/mL was added to each culture. At post culture minute (PCM) 15, 30 and post culture hour (PCH) 1, 2, 3, the number of bacteria adherent to IEC-6 was counted after Wright-Giemsa staining, and cell survival rate was calculated after trypan blue staining, with 20 samples in each group at each time point. (2) Other samples of IEC-6 cells without addition of E. coli were divided into BC, B + I, B + M, and B + I + M groups with the same treatment as above. The supernatant contents of IL-6, IL-8, and TNF-alpha were determined by radioimmunoassay at PCH 3, 6, 12, 24, 48, with 6 samples in each group at each time point. Data were processed with t test.

RESULTS(1) Compared with that in C group, count of adherent bacteria to IEC-6 in BC group at each time point was significantly increased (with t values from 2.947 to 8.149, P values all below 0.01). Compared with those in BC group, the counts in B + I, B + M, B + I + M groups at the major time points were significantly decreased (with t values from -4.733 to -2.180, P < 0.05 or P < 0.01). (2) Compared with that in C group, cell survival rate in BC group at each time point was obviously lowered (with t values from -4.126 to -2.363, P values all below 0.05). Cell survival rates in B + I and B + M groups at some time points were significantly elevated as compared with those in BC group (with t values from 2.120 to 3.423, P < 0.05 or P < 0.01). Cell survival rate in B + I + M group at PCM 15 and PCH 3 was respectively (96.7 +/- 2.4)% and (84.0 +/- 6.7)%, which was respectively higher than that in B + I and B + M groups [(94.5 +/- 3.1)%, t = 2.507, P < 0.05; (77.1 +/- 8.2)%, t = 2.934, P < 0.01]. (3) The contents of TNF-alpha in supernatant of B + I + M group at PCH 6, 12, 24, 48 were significantly lower than those in the other 3 groups (with t values from -6. 914 to -2.889, P < 0.05 or P < 0.01). The contents of IL-6 in supernatant of B + I + M group at some time points were significantly lower than those in the other 3 groups (with t values from -7. 657 to -2.580, P < 0.05 or P < 0.01). The contents of IL-8 in supernatant of B + I + M group at PCH 6, 12, 24, 48 were significantly lower than those in BC and B + M groups (with t values from - 8.802 to - 3.640, P values all below 0.01), and those in B + I + M group at PCH 12, 24 were lower than those in B + I group (with t value respectively -2.786, -2.740, P value all below 0.05).

CONCLUSIONSITF can maintain immune function and homeostasis of IEC, prevent bacterial adherence, decrease cell death rate, and reduce release of inflammatory mediators. The effect can be strengthened with addition of mucin.