title: Effects of rhein on intestinal epithelial tight junction in IgA nephropathy.
abstract: OBJECTIVE
  To investigate the effects of rhein on intestinal epithelial tight junction proteins in rats with IgA nephropathy (IgAN).
  
  
  METHODS
  Twenty-eight female Sprague-Dawley rats were randomly divided into four groups (7 per group): Control, IgAN, Rhein-treated, and Rhein-prevented. Bovine serum albumin, lipopolysaccharide and CCl4 were used to establish the rat model of IgA nephropathy. The Rhein-treated group was given rhein from week 7 until the rats were sacrificed. The Rhein-prevented group was given rhein from week 1. Animals were sacrificed at the end of week 10. We observed the changes in the intestinal epithelial tight junctions using transmission electron microscopy, and expression of intestinal epithelial tight junction proteins zona occludens protein (ZO)-1 and occludin by immunofluorescence using laser confocal microscopy. Changes in mRNA and protein expression of ZO-1 and occludin were measured by reverse transcriptase polymerase chain reaction and Western blotting. The ratio of urinary lactulose/mannitol was measured by high performance liquid chromatography (HPLC) for assessing the intestinal permeability.
  
  
  RESULTS
  In the control group, the tight junctions lied between epithelial cells on the top of the outer side of the cell membrane, and appeared in dense dotted crystal structures, the neighboring cells were binded tightly with no significant gap, and the tight junction protein ZO-1 and occludin were evenly distributed in the intestinal epithelial cells at the top of the junction. Compared with the control group, in the IgAN group, the structure of the tight junction became obscured and the dotted crystal structures had disappeared; the fluorescence of ZO-1 and occludin was uneven and weaker (5.37 ± 1.27 vs 10.03 ± 1.96, P < 0.01; 4.23 ± 0.85 vs 12.35 ± 4.17, P < 0.01); the mRNA expression of ZO-1 and occludin decreased (0.42 ± 0.19 vs 0.92 ± 0.24, P < 0.01; 0.40 ± 0.15 vs 0.97 ± 0.25, P < 0.01); protein expression of ZO-1 and occludin was decreased (0.85 ± 0.12 vs 1.98 ± 0.43, P < 0.01; 0.72 ± 0.15 vs 1.38 ± 0.31, P < 0.01); and the ratio of urinary lactulose/mannitol increased (3.55 ± 0.68 vs 2.72 ± 0.21, P < 0.01). In the Rhein-prevented and Rhein-treated groups, compared with the IgAN group, the intestinal epithelial tight junctions were repaired; fluorescence of ZO-1 and occludin was stronger (11.16 ± 3.52 and 8.81 ± 2.30 vs 5.37 ± 1.27, P < 0.01; 10.97 ± 3.40 and 9.46 ± 2.40 vs 4.23 ± 0.85, P < 0.01); mRNA of ZO-1 and occludin increased (0.81 ± 0.17 and 0.64 ± 0.16 vs 0.42 ± 0.19, P < 0.01; 0.82 ± 0.22 and 0.76 ± 0.31 vs 0.40 ± 0.15, P < 0.01); protein expression of ZO-1 and occludin was increased (2.07 ± 0.41 and 1.57 ± 0.23 vs 0.85 ± 0.12, P < 0.01; 1.34 ± 0.21 and 1.15 ± 0.17 vs 0.72 ± 0.15, P < 0.01); and the ratio of urinary lactulose/mannitol decreased (2.83 ± 0.43 and 2.87 ± 0.18 vs 3.55 ± 0.68, P < 0.01).
  
  
  CONCLUSIONS
  Rhein can enhance the expression of ZO-1 and occludin, repair damaged tight junctions, and protect the intestinal barrier.
authors.affiliation: Graduate School, Medical College of Nanchang University, Nanchang 330006, Jiangxi Province, China.
authors.forename: Sheng-Nan
authors.initials: SN
authors.lastname: Peng
authors.forename: Hui-Hong
authors.initials: HH
authors.lastname: Zeng
authors.forename: Ai-Xiang
authors.initials: AX
authors.lastname: Fu
authors.forename: Xiao-Wen
authors.initials: XW
authors.lastname: Chen
authors.forename: Qing-Xian
authors.initials: QX
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005922:Glomerulonephritis, IGA / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007792:Lactulose / Q000652:urine; D008358:Mannose / Q000652:urine; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D010539:Permeability; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013997:Time Factors; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000880:Anthraquinones; D062793:Occludin; C568987:Ocln protein, rat; D012333:RNA, Messenger; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D007792:Lactulose; D008358:Mannose; C020491:rhein
keywords: IgA nephropathy; Intestine; Rat; Rhein; Tight junction