The role and clinical significance of programmed cell death- ligand 1 expressed on CD19+B-cells and subsets in systemic lupus erythematosus.

BACKGROUND: Programmed cell death-1 (PD-1) and programmed death-ligand 1 (PD-L1)-targeted therapies have enhanced T-cell response and demonstrated efficacy in the treatment of multiple cancers. However, the role and clinical significance of PD-L1 expression on CD19+ B-cells and their subsets, with particular reference to systemic lupus erythematosus (SLE), have not yet been studied in detail. OBJECTIVE: The present study aimed to investigate PD-L1 expression on CD19+ B-cells and their subsets, in addition to exploring its possible role in Tfh-cell activation and B-cell differentiation in SLE. METHODS: Frequencies of CD19+ B-cells, their subsets, PD-L1 and Tfh cells in the peripheral blood of SLE patients and healthy controls (HCs) were determined using cytometry. The clinical data of SLE patients were recorded in detail, and the correlation between their laboratory parameters, clinical parameters and disease activity indices was statistically analyzed. CD19+PD-L1+B-cells and CD19+PD-L1- B-cells were sorted and cultured with a stimulant, following which the supernatants were collected for immunoglobulin G and anti-double stranded DNA detection via enzyme-linked immunosorbent assay. RESULTS: In SLE patients, CD19+B-cells and partial subgroups were enriched in peripheral blood. Also, the observed increase in the frequency of CD19+PD-L1+B-cells was significantly associated with a higher disease activity index. An in vitro culture test demonstrated that the amounts of anti-dsDNA and immunoglobulin G secreted by the CD19+PD-L1+B-cells of SLE patients and HCs were vastly different. In addition, a strong correlation existed between the frequencies of CD19+PD-L1+B-cells and defined Tfh cells of SLE patients. CONCLUSION: This study demonstrated that the expression of CD19+PD-L1+B-cells in the peripheral blood of SLE patients was abnormal, and that disease-related laboratory parameters and clinical indicators were correlated. CD19+PD-L1+B-cells were enriched and played a critical role in activating the pathogenic T-cell and B-cell responses in patients with SLE.

SCF and TLR4 ligand cooperate to augment the tumor-promoting potential of mast cells.

Mast cells may have either antitumor or tumor-promoting potential. Nevertheless, mast cells in tumor microenvironment have been found to promote tumor growth. So far the mechanisms underlying the modulation of mast cell function in tumor microenvironment remains to be fully elucidated. Here, we report that tumor-promoting potential of mast cells could be augmented by molecules released from damaged tumor cells through cooperative stimulation of stem cell factor (SCF) and ligand for Toll-like receptor 4 (TLR4). Co-simulation with SCF and TLR4 ligand inhibited mast cell degranulation, but efficiently induced the production and secretion of VEGF, PDGF, and IL-10. Although TLR4 ligand alone may induce IL-12 expression in mast cells, co-stimulation with SCF and TLR4 ligand induced the expression of IL-10, but not IL-12, in mast cells. The phosphorylation of GSK3ß was crucial for the effect of SCF and TLR4 ligand. In addition to inducing phosphorylation of GSK3ß at Ser9 through PI3K pathway, SCF and TLR4 ligand cooperated to induce phosphorylation of GSK3ß at Tyr216 by simultaneous activation of ERK and p38MAPK pathways. Both phospho-Ser9 and phospho-Tyr216 of GSK3ß were required for IL-10 expression induced by SCF/TLR4 ligand, whereas suppressive effect of SCF/TLR4 ligand on mast cell degranulation was related to phospho-Tyr216. Importantly, the effect of SCF and TLR4 ligand on mast cells could be abrogated by inhibiting phosphorylation of GSK3ß at Tyr216. These findings disclose the mechanisms underlying the modulation of mast cell function in tumor microenvironment, and suggest that inhibiting GSK3ß in mast cells will be beneficial to the treatment of cancer.

Tumor cell-released TLR4 ligands stimulate Gr-1+CD11b+F4/80+ cells to induce apoptosis of activated T cells.

Gr-1(+)CD11b(+)F4/80(+) cells play important roles in tumor development and have a negative effect on tumor immunotherapy. So far, the mechanisms underlying the regulation of their immunosuppressive phenotype by classical and alternative macrophage activation stimuli are not well elucidated. In this study, we found that molecules from necrotic tumor cells (NTC-Ms) stimulated Gr-1(+)CD11b(+)F4/80(+) cells to induce apoptosis of activated T cells but not nonstimulated T cells. The apoptosis-inducing capacity was determined by higher expression levels of arginase I and IL-10 relative to those of NO synthase 2 and IL-12 in Gr-1(+)CD11b(+)F4/80(+) cells, which were induced by NTC-Ms through TLR4 signaling. The apoptosis-inducing capacity of NTC-Ms-stimulated Gr-1(+)CD11b(+)F4/80(+) cells could be enhanced by IL-10. IFN-gamma may reduce the apoptosis-inducing capacity of Gr-1(+)CD11b(+)F4/80(+) cells only if their response to IFN-gamma was not attenuated. However, the potential of Gr-1(+)CD11b(+)F4/80(+) cells to express IL-12 in response to IFN-gamma could be attenuated by tumor, partially due to the existence of active STAT3 in Gr-1(+)CD11b(+)F4/80(+) cells and NTC-Ms from tumor. In this situation, IFN-gamma could not effectively reduce the apoptosis-inducing capacity of Gr-1(+)CD11b(+)F4/80(+) cells. Tumor immunotherapy with 4-1BBL/soluble programmed death-1 may significantly reduce, but not abolish the apoptosis-inducing capacity of Gr-1(+)CD11b(+)F4/80(+) cells in local microenvironment. Blockade of TLR4 signaling could further reduce the apoptosis-inducing capacity of Gr-1(+)CD11b(+)F4/80(+) cells and enhance the suppressive effect of 4-1BBL/soluble form of programmed death-1 on tumor growth. These findings indicate the relationship of distinct signaling pathways with apoptosis-inducing capacity of Gr-1(+)CD11b(+)F4/80(+) cells and emphasize the importance of blocking TLR4 signaling to prevent the induction of T cell apoptosis by Gr-1(+)CD11b(+)F4/80(+) cells.

[Inhibitory effect of miR-20b on airway inflammation in asthmatic mice].

OBJECTIVE: To explore the effect of miR-20b in inhibiting airway inflammation in a mouse model of asthma. METHODS: Female BALB/c mouse models of asthma, established by sensitizing and challenging the mice with a mixture of ovalbumin and aluminum hydroxide, were subjected to intranasal instillation of 20 µg miR-20b mimics or a miR-20b scramble every 3 days. On day 49, bronchoalveolar lavage fluid (BALF) was collected from the mice to examine the counts of total cells and different cell populations; HE staining was used to observe the pathological changes of the lung tissue, and the concentration of vascular endothelial growth factor (VEGF) in BALF was detected by ELISA. RESULTS: Treatment of the asthmatic mice with miR-20b mimics decreased not only the counts of the total leukocytes, neutrophils and eosinophils in the BALF but also mucus secretion in the airway and inflammatory cell infiltration around the bronchus, and lessened thickening of the airway mucosa. Instillation with miR-20b mimics significantly reduced the concentration of VEGF in BALF from 28.55±3.42 pg/mL in the asthma model group to 18.19±3.67 pg/mL (P<0.01). CONCLUSION: MiR-20b can inhibit airway inflammation in asthmatic mice possibly by reducing the expression of VEGF.

Endothelial cell-expressed Tim-3 facilitates metastasis of melanoma cells by activating the NF-kappaB pathway.

T cell immunoglobulin and mucin domain-3 (Tim-3) is originally recognized as a receptor of Th1 cells. We found that Tim-3 could be expressed in endothelial cells after stimulation with tumor cell-released TLR4 ligand. Tim-3 expressed by endothelial cells does not function as the receptor of galectin-9, but mediates the interaction of endothelial cells with tumor cells. The engagement of endothelial cell-expressed Tim-3 with a non-galectin 9 putative receptor on B16 melanoma cells could trigger the NF-kappaB signaling pathway in B16 cells. The activated NF-kappaB not only promoted the proliferation of B16 cells, but also enhanced apoptosis resistance of B16 cells by up-regulating Bcl-2 and Bcl-xL and down-regulating Bax. Consistently, Tim-3 facilitated the survival of B16 cells in the blood stream, arrested in the lung and following invasion, resulted in more metastatic nodules in the lung. These findings suggest that endothelial cell-expressed Tim-3 increases tumor cell metastatic potential by facilitating tumor cell intravasation, survival in blood stream and extravasation. Thus, anti-inflammation or blockade of Tim-3 may contribute to the prevention of metastasis.