Abstract: Objective  To investigate the effect of oral medicinal charcoal tablets on the structure of intestinal epithelial barrier in maintenance hemodialysis patients.  Methods  Patients undergoing maintenance hemodialysis in the Nephrology Department of Hanzhong Central Hospital from December 2015 to March 2016 were selected as subjects and randomly assigned to a hemodialysis (HD) group and a medicinal charcoal tablets (MCT) group (3 tablets/time, 3 times/day for 3 consecutive months). Healthy individuals from outpatient physical examinations during the same period were selected as the control group (Control group). A monolayer cell model was constructed using Caco-2 cells. The cells were cultured with 10% mixed serum from different groups for intervention. Transepithelial electrical resistance (TEER) of Caco-2 intestinal epithelial cells was measured using a resistance meter. Cell growth and proliferation rates were assessed using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) colorimetric assay. The expression levels of tight junction proteins claudin-1, occludin, and zonula occludens-1 (ZO-1) were detected by Western blot.  Results  Serum samples were collected from 9 subjects each in the HD, MCT, and Control groups. Every 3 serum samples were pooled to create mixed serum for subsequent intervention on intestinal epithelial cells. Compared to the Control group, serum from the HD group significantly reduced TEER of intestinal epithelial Caco-2 cells after 24 h and 48 h of intervention (24 h: t =11.436, P=0.004; 48 h: t =11.587, P =0.001), inhibited cell viability and proliferation (24 h: t =10.701, P =0.007; 48 h: t =-5.295, P =0.002), and these effects were time-dependent (comparison between 24 h and 48 h in the HD group: TEER t =17.206, P<0.001; cell viability: t =10.701, P< 0.001). The expression levels of tight junction (TJ) proteins claudin-1 (t =17.962, P =0.003), occludin (t =6.824, P = 0.021), and ZO-1 (t =8.070, P =0.015) were decreased in the HD group. Compared to the Control group, serum from the MCT group also reduced TEER after different intervention times (24 h: t =-7.420, P =0.001; 48 h: t =-6.969, P =0.004) and mildly decreased cell proliferation viability (24 h:t=17.746, P=0.039; 48 h:t=-2.911, P =0.042). The expression levels of claudin-1 (t =6.346, P =0.032) and ZO-1 (t =8.356, P =0.043) were reduced, while the change in occludin expression did not reach statistical significance (t =3.897, P =0.060). Conclusions Uremia impairs intestinal epithelial barrier function. Oral medicinal charcoal tablets can mitigate the damage to intestinal epithelial tight junction structures caused by uremia.

Key words: Uremia, Intestinal epithelial barrier, Oral activated charcoal, Adsorbent, Tight junction