No abstract

There has been lack of the uniform standard for establishment of animal immunodepressive models induced by cyclophosphamide (CTX), and the information about the immunosuppressive effect of CTX on peripheral blood lymphocyte subsets in rodents. Here we describe a CTX-induced mouse model and try to establish a feasible immunosuppressive model for studying the fungal pathogenicity. Balb/c mice received two intraperitoneal injections of different CTX doses (50-200 mg/kg) at 2-day intervals. Peripheral whole blood collected at different time-points before and after CTX injection was used to detect white blood cells (WBCs), lymphocytes and their subsets by automated hematology analyzer and flow cytometry, respectively. WBCs and lymphocytes in all groups except CTX50 (50 mg/kg CTX) group commenced to decrease in a dose-dependent manner on day 1, reached the nadir on day 4, rebounded on day 10, and declined again on day 17 after CTX treatment. Low dose (50 mg/kg) CTX produced no obvious change of percentage of CD3(+), CD4(+) and CD8(+) T cells and CD19(+) cells, but high doses (100 or 150 mg/kg) yielded a significant decrease of CD3(+) and CD4(+) cells on day 4 and CD19(+) cells on day 10, and increase of CD8(+) cells on day 4. The CD4(+)/CD8(+) ratio decreased on day 4, followed by a rebound thereafter when treated with 3 different doses of CTX. The results indicate that two intraperitoneal injections of CTX at 150 mg/kg at 2-day intervals may establish good immunosuppressive models of Balb/c mice for studying the fungal pathogenicity.

The symptoms of vaginal candidiasis exacerbate in the second half of the menstrual cycle in the premenopausal women when the serum estradiol level is elevated. Estradiol has been shown to inhibit Th17 differentiation and production of antifungal interleukin-17 (IL-17) cytokines. However, little is known about the mechanisms. In the present study, we used mouse splenocytes and found that estradiol inhibited Th17 differentiation through down-regulation of Rorγt mRNA and protein expression. Estradiol activated ERα to recruit repressor of estrogen receptor activity (REA) and form ERα/REA complex. This complex bound to three estrogen response element (ERE) half-sites on the Rorγt promoter region to suppress Rorγt expression. Estradiol induced Rea mRNA and protein expression in mouse splenocytes. Using Rea siRNA to knockdown Rea expression enhanced Rorγt expression and Th17 differentiation. On the other hand, histone deacetylase (HDAC) 1 and 2 bound to the three ERE half-sites, independent of estradiol. HDAC inhibitor MS-275 dose- and time-dependently increased Rorγt expression, and subsequently enhanced Th17 differentiation. In 15 healthy premenopausal women, high serum estradiol levels are correlated with low RORγT mRNA levels and high REA mRNA levels in the vaginal lavage. These results demonstrate that estradiol up-regulates REA expression and recruits REA via ERα to the EREs on the RORγT promoter region, thus inhibiting RORγT expression and Th17 differentiation. This study suggests that the estradiol-ERα-REA axis may be a feasible target in the management of recurrent vaginal candidiasis.