Abstract: Objective: To investigate the correlation between intestinal inflammation and the expression levels of calprotectin (S100A8/A9) in HIV-infected individuals. Methods: Fifteen AIDS patients (Group A), 15 asymptomatic HIV-infected individuals (Group B), and 10 healthy individuals (Group C) were selected, and blood, feces and intestinal tissues of them were collected. The calprotectin level was measured by ELISA, the degree of intestinal mucosal inflammation was observed through HE staining, the expression of S100A8/A9 in intestinal tissue was evaluated by immunohistochemistry and Western blotting. Results: The levels of serum and fecal calprotectin in Groups A and B were higher than those in Group C (P＜0.05), and the level of serum calprotectin in Group A was higher than that in Group B (P=0.016). HE staining showed that intestinal mucosal lesions in HIV-infected individuals were aggravated and neutrophils increased (P＜0.05). Immunohistochemistry and Western blotting showed that the expression of S100A8/A9 in intestinal tissues of Groups A and B was higher than that of Group C (P＜0.05), and the expression in Group A was higher than that in Group B. The count of CD4+T cells was negatively correlated with the expression of S100A8/A9 in serum, feces and intestinal tissues (Ps＜0.001). Conclusion: The calprotectin level in HIV-infected individuals is associated with intestinal inflammation and increases with the progression of the disease course.

Key words: HIV infection, gut inflammation, calprotectin (S100A8/A9), biomarker, CD4+ T cells