ABSTRACT
Background: The risk of opportunistic infection in ulcerative colitis (UC) is significantly higher than that in healthy subjects, and has adverse impact on clinical outcome. Aims: To analyze the prevalence of opportunistic intestinal infection in UC patients and explore the risk factors of UC complicated with opportunistic infection. Methods: Clinical data of patients with UC hospitalized in Peking University Third Hospital from January 2012 to December 2020 were collected retrospectively. Information on demography, clinical characteristics, laboratory, endoscopic and pathological findings, as well as the medication histories were recorded; the factors associated with opportunistic intestinal infection were analyzed using univariate and multivariate analyses. Results: A total of 275 UC patients were included, with an opportunistic intestinal infection rate of 26.2%; among which, rates of cytomegalovirus (CMV), Epstein ‑ Barr virus (EBV), fungi, Clostridium difficile, amoeba, and multiple infection were 13.5%, 14.5%, 5.1%, 1.5%, 1.1%, and 9.1%, respectively. Multivariate Logistic analysis demonstrated that severe disease activity (OR=6.517, 95% CI: 1.487‑28.552, P=0.013) and albumin <30 g/L (OR=3.895, 95% CI: 1.590 ‑ 9.544, P=0.003) were independent risk factors for CMV infection. The independent risk factors for EBV infection included severe disease activity (OR=11.260, 95% CI: 2.249‑56.382, P=0.003), albumin <30 g/L (OR=2.548, 95% CI: 1.096‑5.927, P=0.030) and C‑reactive protein (CRP) elevation (OR=1.046, 95% CI: 1.007‑1.086, P=0.019). While for intestinal fungal infection, the risk in patients with chronic relapsing type UC was lower (OR=0.278, 95% CI: 0.087‑0.886, P=0.030). Intestinal multiple infection was mainly composed of viral infection, and the independent risk factors were similar to those of CMV and EBV infection. Conclusions: Most of the opportunistic intestinal infection in UC patients is viral infection. Disease activity, inflammatory response and reduced albumin are risk factors for intestinal viral infection in UC patients, while the risk of fungal infection is only related to clinical subtyping.
ABSTRACT
OBJECTIVE@#To investigate the regulatory effect of metformin on regulatory T cells (Treg) in acidic environment.@*METHODS@#CD4 CD25 Treg cells were obtained by magnetic bead sorting. Treg and conventional T cells (Tcon) cells were cultured for 24-72 h in pH 7.4 or pH 6.7 medium, and the cell proliferation, apoptosis and Foxp3 expression were detected by flow cytometry. Real-time PCR was used to detect the expression levels of the genes related with glucose metabolism. Thirty-two C57BL/6 male mouse models bearing subcutaneous prostate cancer xenograft derived from RM-1 cells were randomized into 4 equal groups for treatment with PBS, metformin, tumor vaccine, or both metformin and the vaccine. The treatment started on the 4th day following tumor cell injection, and metformin (100 mg/kg) or PBS was administered by intraperitoneal injection on a daily basis; the vaccine was intramuscularly injected every 4 days. The tumor size was continuously monitored, and the mice were euthanized on day 25 after tumor implantation to obtain tumor and blood samples. Flow cytometry was used to detect the changes in CD4, CD8, CD4Foxp3 cell subsets in the tumor tissue and peripheral blood.@*RESULTS@#Treg cells showed significantly enhanced proliferation ( < 0.05) while the proliferation of Tcon cells was suppressed in acidic medium ( < 0.001). Treg cells cultured in acidic medium showed significantly increased expressions of OXPHOS-related genes pgc1a ( < 0.001) and cox5b ( < 0.01), which did not vary significantly in Tcon cells in acidic medium. Treg cells exhibited significantly decreased apoptosis in acidic medium ( < 0.01) with increased Foxp3 cells ( < 0.001) and intracellular alkaline levels ( < 0.01). Metformin obviously reversed the acid tolerance of Treg cells without producing significant effect on Tcon cells. In the animal experiment, both metformin ( < 0.05) and vaccine ( < 0.01) alone reduced the tumor volume, but their combined treatment more potently reduced the tumor volume ( < 0.001). Metformin alone did not obviously affect CD4 cells or CD8 cells but significantly decreased the percentage of CD4Foxp3 ( < 0.05); the vaccine alone significantly increased CD4 cells and CD8 cells ( < 0.001) and also the percentage of CD4Foxp3 cells ( < 0.05). The combined treatment, while reducing the percentage of CD4Foxp3cells to a level lower than that in the vaccine group ( < 0.01), produced the strongest effect to increase CD4 cells and CD8 cells ( < 0.01).@*CONCLUSIONS@#Metformin can inhibit the proliferation and function of regulatory T cells in an acidic environment and enhance the effect of tumor vaccine by reducing the proportion of Treg cells to achieve the anti-tumor effect.