Effects of thyroid hormones on cardiac function in mice by inducing expression of B-cell activating factor in cardiomyocytes / 医学研究生学报

Objective　High levels of triiodothyronine (T3) can lead to hyperthyroid heart disease, but its mechanism is unclear. This study aims to investigate the effects of T3 on the expression of B-cell activating factor (BAFF) in cardiomyocytes and to explore its possible role in the pathogenesis of hyperthyroid heart disease.　Methods　Sixty healthy C57BL/6J mice were selected and randomly divided into two groups: the experimental group and the control group. The experimental group received intraperitoneal injection of T3 at 5 μg/ml, one time/d, for 42 consecutive days. The concentrations of serum T3 and tetraiodothyronine (T4) were detected by radioimmunoassay; ELISA was used to determine BAFF expression in peripheral blood, and the cardiac index and the transverse diameter of myocardial cells in each group were determined. Immunohistochemistry and Western blot were used to detect the expression of BAFF protein in myocardium and of myocardial tumor necrosis factor-α (TNF-α) protein; the expression of BAFF mRNA in myocardium was detected by Real-Time PCR; flow cytometry (FCM) was used to detect changes in the proportion of B-cells in the heart.　Results　Compared with the control group, the serum T3 concentration, cardiac index, BAFF and myocardial cell transverse diameter of the experimental group significantly increased (P<0.05), and the T4 concentration decreased (P<0.05). Under the light microscope, the cardiomyocytes of the control group were normal, while those of the experimental group were hypertrophied and disordered in structure. Compared with the control group (0.765±0.164), BAFF protein expression significantly increased in the experimental group (1.865±0.290) (P<0.05). Compared with the control group (0.537±0.089), the expression of TNF-α protein significantly increased in the experimental group (0.737±0.065) (P<0.05). Correlation analysis of T3 with BAFF gene expression in cardiomyocytes and BAFF level in peripheral blood showed that T3 was positively correlated with both the former with a correlation coefficient of 0.637 (P<0.01) and the latter with 0.778 (P<0.01). For FCM, compared with the control group [(12.40±1.09)%], the proportion of myocardial B-cells increased in the experimental group [(16.12±0.631)%] (P<0.05).　Conclusion　High concentration of T3 can promote the expression of BAFF in myocardial cells and lead to the activation of B-cells, thus increasing the inflammatory response and leading to myocardial hypertrophy.

Overexpression of Fc receptor-like 1 associated with B-cell activation during hepatitis B virus infection

The role of B cells in the pathogenesis of hepatitis B virus (HBV) infection has not been explored in depth. In the present study, the activation status of B cells from peripheral blood of healthy controls (N = 20) and patients with acute hepatitis B (AHB, N = 15) or chronic hepatitis B (CHB, N = 30) was evaluated by measuring the expression levels of B-cell activation markers CD69 and CD86, using quantitative real-time PCR and flow cytometry. Moreover, the potential mechanism underlying B-cell activation during HBV infection was further investigated by analyzing the expression profile of FCRL1, an intrinsic activation molecule of B cells. An elevation in the levels of B-cell activation markers including CD69 and CD86 was observed in the AHB patients (44.31 ± 9.27, 27.64 ± 9.26%) compared to CHB patients (30.35 ± 11.27, 18.41 ± 6.56%, P < 0.05), which was still higher than healthy controls (12.23 ± 7.84, 8.22 ± 3.43%, P < 0.05). Furthermore, the expression of FCRL1 was found to be similar to B-cell activation markers, which was highest in AHB patients (70.15 ± 17.11%), lowest in healthy donors (36.32 ± 9.98%, P < 0.05) and half-way between these levels in patients with CHB (55.17 ± 12.03%, P < 0.05). The results were positively associated with aberrant B-cell activation. These data suggest that B cells can play a role in HBV infection, and therefore more effort should be devoted to exploring their functions.

Regulation of B cell activating factor (BAFF) receptor expression by NF-kappaB signaling in rheumatoid arthritis B cells

B cells play an important role in the pathogenesis of rheumatoid arthritis (RA). High levels of B cell activating factor (BAFF) are detected in autoimmune diseases. BAFF and BAFF receptor (BAFF-R) are expressed in B and T cells of RA synovium. The study was undertaken to identify the NF-kappaB signal pathway involved in the induction of BAFF-R in human B cells. Immunohistochemical staining of NF-kappaB p65, NF-kappaB p50, BAFF, and BAFF-R was performed on sections of synovium from severe and mild RA and osteoarthritis (OA) patients. Peripheral blood mononuclear cells (PBMCs) were isolated from control and RA patients and B cells were isolated from controls. BAFF-R was analyzed by flow cytometry, realtime PCR and confocal staining after treatment with NF-kappaB inhibitors. NF-kappaB p65, NF-kappaB p50, BAFF, and BAFF-R were highly expressed in severe RA synovium relative to mild RA synovium or OA synovium. BAFF-R expression was reduced by NF-kappaB inhibitors in PBMCs and B cells from normal controls. We also showed reduction in expression of BAFF-R via inhibition of the NF-kappaB pathway in PBMCs of RA patients. BAFF/BAFF-R signaling is an important mechanism of pathogenesis in RA and that BAFF-R reduction by NF-kappaB blocking therapy is another choice for controlling B cells in autoimmune diseases such as RA.

5C5-a novel antigen restrictedly exprossed on human activated B cells / 中国免疫学杂志

Using a human activated B cell line 3D5 in immunization of mouse and as targets in screening, a hybridoma producing McAb 5C5 has been established. The antigen recognized by the McAb starts its expression on low dose anti-?-activated B cells at their G_1 phase at the 10th hour. The number of 5C5~+ cells increases with time. At the stimulation of PWM, the number of 5C5~+ cells in PBMNC also increases with time, and peaks on day 3 to 4, then docreases and comes to the background on day 7.5C5 antigen is positive on the B cell lines which can not be induced to differentiate to Ig-secre-ting cells (ISC), but negative on those being able to be driven to differentiate to ISC by BCDF. All the data indicate that 5C5 expresses at the early and mid stages, but disappears at the terminal stage of B cell activation and differentiation. 5C5 antigen does not expresses on resting B cells, resting T cells, PHA-activated T cells, monocytes, neutrophils, and the T cell and myeloid cell lines detected. Electrophoresis under both the nonreducing and reducing state for the ~(125)I-label led antigen immunoprecipi tated with McAb 5C5 shows a single band with a molecular weight of 52000, suggesting that 5C5 be a single chain cell surface protein. Since the MW of 5C5 is different from that of those B cell activation antigens reported in literature, and since ins specific expression on cell lines, 5C5 antigen might be a novel B eel I-restricted activation antigen.