CXCL13/CXCR5 Interaction Facilitates VCAM-1-Dependent Migration in Human Osteosarcoma

Osteosarcoma is the most common primary tumor of the skeletal system and is well-known to have an aggressive clinical outcome and high metastatic potential. The chemokine (C-X-C motif) ligand 13 (CXCL13) plays a vital role in the development of several cancers. However, the effect of CXCL13 in the motility of osteosarcoma cells remains uncertain. Here, we found that CXCL13 increases the migration and invasion potential of three osteosarcoma cell lines. In addition, CXCL13 expression was upregulated in migration-prone MG-63 cells. Vascular cell adhesion molecule 1 (VCAM-1) siRNA and antibody demonstrated that CXCL13 promotes migration via increasing VCAM-1 production. We also show that CXCR5 receptor controls CXCL13-mediated VCAM-1 expression and cell migration. Our study identified that CXCL13/CXCR5 axis facilitate VCAM-1 production and cell migration in human osteosarcoma via the phospholipase C beta (PLCβ), protein kinase C α (PKCα), c-Src, and nuclear factor-κB (NF-κB) signaling pathways. CXCL13 and CXCR5 appear to be a novel therapeutic target in metastatic osteosarcoma.

CXCL13 blockade attenuates lupus nephritis of MRL/lpr mice

The chemokine CXC ligand 13 protein (CXCL13) is reported to closely related to the disease activity and severity of systemic lupus erythematosus (SLE), moreover, the level of CXCL13 was markedly raised in kidney tissues of lupus nephritis (LN) patients. The aim of the present study was to explore whether the blockade of CXCL13 has therapeutic effects on murine LN. MRL/lpr mice received 50μg anti-CXCL13 neutralizing antibody or isotype IgG by intraperitoneal injection everyday for six weeks, and renal damage of each group was determined. Our results showed that the blockade of CXCL13 significantly reduced urine protein, serum creatinine, and dramatically attenuated renal pathology injury. Treatment with anti-CXCL13Ab also reduced serum anti-dsDNA level, renal immune complex deposition as well as inflammatory cytokines secretion. Meanwhile, Th17/Treg ratio in spleens of MRL/lpr mice was significantly decreased by the blocking of CXCL13. These findings suggested that CXCL13 may be a promising target for the therapy of LN.

Interruption of CXCL13-CXCR5 axis increases upper genital tract pathology and activation of NKT cells following chlamydial genital infection

BACKGROUND

Regulation of immune responses is critical for controlling inflammation and disruption of this process can lead to tissue damage. We reported that CXCL13 was induced in fallopian tube tissue following C. trachomatis infection. Here, we examined the influence of the CXCL13-CXCR5 axis in chlamydial genital infection.

METHODOLOGY AND PRINCIPAL FINDINGS

Disruption of the CXCL13-CXCR5 axis by injecting anti-CXCL13 Ab to BALB/c mice or using Cxcr5-/- mice increased chronic inflammation in the upper genital tract (UGT; uterine horns and oviducts) after Chlamydia muridarum genital infection (GT). Further studies in Cxcr5-/- mice showed an elevation in bacterial burden in the GT and increased numbers of neutrophils, activated DCs and activated NKT cells early after infection. After resolution, we noted increased fibrosis and the accumulation of a variety of T cells subsets (CD4-IFNγ, CD4-IL-17, CD4-IL-10 & CD8-TNFα) in the oviducts. NKT cell depletion in vitro reduced IL-17α and various cytokines and chemokines, suggesting that activated NKT cells modulate neutrophils and DCs through cytokine/chemokine secretion. Further, chlamydial glycolipids directly activated two distinct types of NKT cell hybridomas in a cell-free CD1d presentation assay and genital infection of Cd1d-/- mice showed reduced oviduct inflammation compared to WT mice. CXCR5 involvement in pathology was also noted using single-nucleotide polymorphism analysis in C. trachomatis infected women attending a sub-fertility clinic. Women who developed tubal pathology after a C. trachomatis infection had a decrease in the frequency of CXCR5 SNP +10950 T>C (rs3922).

CONCLUSIONS/SIGNIFICANCE

These experiments indicate that disruption of the CXCL13-CXCR5 axis permits increased activation of NKT cells by type I and type II glycolipids of Chlamydia muridarum and results in UGT pathology potentially through increased numbers of neutrophils and T cell subsets associated with UGT pathology. In addition, CXCR5 appears to contribute to inter-individual differences in human tubal pathology following C. trachomatis infection.

CXCL13 expression in Chlamydia trachomatis infection of the female reproductive tract

Chlamydia trachomatis is the most common cause of acute salpingitis worldwide. The socioeconomic impact of sexually transmitted infections (STI) caused by C. trachomatis is considerable. The purpose of this study was to investigate secretion of a unique chemokine, CXCL13, during the inflammatory process in human fallopian tube tissue in response to infection with C. trachomatis. We employed two models for our experiments: archived fallopian tube paraffin sections from known cases of salpingitis of unknown etiology and human fallopian tube organ culture established from fresh fallopian tube biopsies subsequently infected in vitro with C. trachomatis serovar E. We used immunohistochemistry, microarray analysis and cytometric bead array to study these specimens. In both models, we found that the fallopian tissue infected with C. trachomatis expressed CXCL13 and other characteristics of tertiary lymphoid tissue. In addition, we found that CXCL13 was expressed in multiple cell types, including endothelial cells, demonstrating a mechanism for the lymphoid aggregation seen in fallopian tube tissue during salpingitis and infection with C. trachomatis.

CCL19 and CXCL13 synergistically regulate interaction between B cell acute lymphocytic leukemia CD23+CD5+ B Cells and CD8+ T cells

Interacting with T cells, cytokine-producing B cells play a critical protective role in autoimmune diseases. However, the interaction between malignant B and T cells remains to be fully elucidated. In a previous study, we have reported that ligation of CCL19-CCR7 and CXCL13-CXCR5 activates paternally expressed gene 10 (PEG10), resulting in an enhancement of apoptotic resistance in B-cell acute lymphocytic leukemia (B-ALL) CD23+CD5+ B cells. Here, we report that B-ALL CD23+CD5+ B cells produce IL-10 at high level, which can be further elevated by costimulation with CCL19 and CXCL13. CCL19/CXCL13-activated B-ALL CD23+CD5+ B cells, in turn, increase IL-10 expression in syngeneic CD8+ T cells in a B cell-derived IL-10-dependent manner and requiring a cell-cell contact. IL-10 secreted from B-ALL CD23+CD5+ B cells in vitro impairs tumor-specific CTL responses of syngeneic CD8+ T cells. The impairment of cytotoxicity of syngeneic CD8+ T cells is escalated by means of CCL19/CXCL13-induced up-regulation of IL-10 from B-ALL CD23+CD5+ B cells. Moreover, using a short hairpin RNA to knockdown PEG10, we provide direct evidence that increased expression of PEG10 in B-ALL CD23+CD5+ B cells is involved in malignant B-T cell interaction, contributing to the up-regulation of IL-10 expression, as well as to the impairment of cytotoxicity of syngeneic CD8+ T cells. Thus, malignant B-ALL CD23+CD5+ B cells play an immunoregulatory role in controlling different inflammatory cytokine expressions. IL-10 may be one of the critical cellular factors conferring B-ALL CD23+CD5+ B cells to escape from host immune surveillance.