The relationship between immune imbalance and intestinal barrier dysfunction in patients with severe intra-abdominal infections

Objective To investigate the relationship between the change in regulatory T lymphocyte (Treg) in the peripheral blood and intestinal barrier dysfunction in the patients who suffered multiple organ dysfuction syndrome (MODS) induced by severe intra-abdominal infections. Methods Forty-six patients with severe intra-abdominal infections were enrolled in this study, and they were divided into four groups according to their first day acute physiology and chronic health evaluationⅡ (APACHEⅡ) scores: mild group (8-10, 13 cases), medium group (11-15, 17 cases), severe group (16-20, 10 cases) and extremely severe group (≥21, 6 cases). The therapeutic strategy was the same in all groups based on the "guideline of the severe sepsis and septic shock". The levels of endotoxin (ET), human leucocyte antigen-DR (HLA-DR) and the CD4+CD25+Treg in the peripheral blood, and lactulose/mannitol (L/M) ratio in the urine were determined on 1st, 3rd and 7th day after treatment. Finally, the mortality rate at 28 days and the length of stay in surgical intensive care unit (SICU) were recorded. Results In 46 patients, the average length of stay in SICU were (11.06±5.40) days, and the mortality rate at 28 days was 13.04%. But the mortality of the patients in severe and extremely severe groups was higher than other groups (all P<0.05). The levels of L/M ratio and ET began to lower in 7 days in mild group and medium group (all P<0.05), and in severe and extremely severe groups, these two indexes were decreased at first, but increased on 7th day. Moreover, the HLA-DR of mild and medium groups showed a tendency of elevation, but monocytic HLA-DR expression was depressed and circulating Treg markedly elevated in the critically ill patients (all P<0.05). There was a significant positive correlation between Treg and L/M ratio on 1, 3, 7 days [correlation coefficients (r)=0.749, 0.870, 0.910, respectively, all P<0.01]. Conclusion An increase in intestinal permeability and a greater degree of immunosuppression are observed during severe intra-abdominal infections. This change becomes more severe coinciding with the degree of seriousness of the patients. This condition is improved in mild and medium grade patients in 7 days, but no improvement is found in severe patients, and it gets worse in the extremely severe patients in 7 days. These data support the concept that severe immunological imbalance occurred in the patients with severe intra-abdominal infections, and it is associated with intestinal barrier dysfunction and endotoxemia. Key words: intra-abdominal infection ;  immune imbalance ;  intestinal barrier dysfunction ;  regulatory T lymphocyte ;  human leukocyte antigen-DR ;