Changes in intestinal mucosal immune barrier in rats with endotoxemia.
OBJECTIVE
To investigate the dysfunction of the immunological barrier of the intestinal mucosa during endotoxemia and to elucidate the potential mechanism of this dysfunction.


METHODS
Male Wistar rats were randomly distributed into two groups: control group and lipopolysaccharide (LPS) group. Endotoxemia was induced by a single caudal venous injection of LPS. Animals were sacrificed in batches 2, 6, 12 and 24 h after LPS infusion. The number of microfold (M)-cells, dendritic cells (DCs), CD4(+) T cells, CD8(+) T cells, regulatory T (Tr) cells and IgA(+) B cells in the intestinal mucosa were counted after immunohistochemical staining. Apoptotic lymphocytes were counted after TUNEL staining. The levels of interleukin (IL)-4, interferon (IFN)-gamma and forkhead box P3 (Foxp3) in mucosal homogenates were measured by ELISA. The secretory IgA (sIgA) content in the total protein of one milligram of small intestinal mucus was detected using a radioimmunological assay.


RESULTS
This research demonstrated that LPS-induced endotoxemia results in small intestinal mucosa injury. The number of M-cells, DCs, CD8(+) T cells, and IgA(+) B cells were decreased while Tr cell and apoptotic lymphocyte numbers were increased significantly. The number of CD4(+) T cells increased in the early stages and then slightly decreased by 24 h. The level of IL-4 significantly increased in the early stages and then reversed by the end of the study period. The level of IFN-gamma increased slightly in the early stages and then decreased markedly by the 24 h time point. Level of Foxp3 increased whereas sIgA level decreased.


CONCLUSIONS
Mucosal immune dysfunction forms part of the intestinal barrier injury during endotoxemia. The increased number and function of Tr cells as well as lymphocyte apoptosis result in mucosal immunodeficiency.
Liu
Chong
C
Department of Critical Care Medicine, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing 100050, China.
Li
Ang
A
Weng
Yi-Bing
YB
Duan
Mei-Li
ML
Wang
Bao-En
BE
Zhang
Shu-Wen
SW
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D019446:Endotoxemia / Q000139:chemically induced / Q000276:immunology*; D051858:Forkhead Transcription Factors / Q000276:immunology; D018928:Immunity, Mucosal / Q000276:immunology*; D007070:Immunoglobulin A / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology; D008297:Male; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013601:T-Lymphocytes / Q000276:immunology
D051858:Forkhead Transcription Factors; C500522:Foxp3 protein, rat; D007070:Immunoglobulin A; D008070:Lipopolysaccharides; D007371:Interferon-gamma