Autoantibody-producing RP105(-) B cells, from patients with systemic lupus erythematosus, showed more preferential expression of BCMA compared with BAFF-R than normal subjects.

OBJECTIVE: B cells lacking RP105 produce autoantibodies in patients with SLE. Expression of B-cell activating factor (BAFF) binding receptors (BBRs) and survival of RP105(-) B cells from SLE patients were examined. METHODS: Detection of difference of gene expression between RP105(-) and RP105(+) B cells was done by DNA microarrays. Surface expression was confirmed by flow cytometry. The contribution of BAFF, a proliferation-inducing ligand (APRIL) and monomers/trimers of sCD40L to survival of RP105(-) and RP105(+) B cells was examined. RESULTS: Gene expression of B-cell maturation antigen (BCMA) was different among BBRs in RP105(-) and RP105(+) B cells in SLE. Preferential expression of BCMA on RP105(-) B cells was confirmed compared with RP105(+) B cells by flow cytometry, although BAFF receptor (BAFF-R) expression on RP105(-) B cells was significantly lower. Additionally, relative ratios of BCMA/BAFF-R expression on RP105(-) B cells were increased significantly in SLE patients compared with normal subjects. Stimulation by sCD40L decreased the number of surviving RP105(-) and RP105(+) B cells in vitro. RP105(+) B cells were not rescued from sCD40L-induced cell death by BAFF and/or APRIL. In contrast, either BAFF or APRIL maintained the survival of RP105(-) B cells due to avoidance of cell death. Activated RP105(-) B cells reduced BAFF-R and increased BCMA levels. CONCLUSIONS: RP105(-) B cells from SLE patients showed more preferential expression of BCMA compared with BAFF-R than normal subjects, and were possibly regulated by BAFF/APRIL. Our results provide a new insight of BCMA and their ligands in B cells from SLE patients.

Expression profile analysis of aorta-gonad-mesonephros region-derived stromal cells reveals genes that regulate hematopoiesis.

The aorta-gonad-mesonephros (AGM) region is involved in the generation and maintenance of the first definitive hematopoietic stem cells (HSCs). A mouse AGM-derived cell line, AGM-S3, was shown to support the development of HSCs. To elucidate the molecular mechanisms regulating early hematopoiesis, we obtained subclones from AGM-S3, one of which was hematopoiesis supportive (S3-A9) and the other one of which was non-supportive (S3-A7), and we analyzed their gene expression profiles by gene chip analysis. In the present study, we found that Glypican-1 (GPC1) was highly expressed in the supportive subclone AGM-S3-A9. Over-expression of GPC1 in non-supportive cells led to the proliferation of progenitor cells in human cord blood when cocultured with the transfected-stromal cells. Thus, GPC1 may have an important role in the establishment of a microenvironment that supports early events in hematopoiesis.

Oxidized galectin-1 advances the functional recovery after peripheral nerve injury.

Oxidized galectin-1 has been shown to promote axonal regeneration from transected-nerve sites in an in vitro dorsal root ganglion (DRG) explant model as well as in in vivo peripheral nerve axotomy models. The present study provides evidence that oxidized galectin-1 advances the restoration of nerve function after peripheral nerve injury. The sciatic nerve of adult rats was transected and the distal nerve was frozen after being sutured into a proximal site with four epineurial stitches. An osmotic pump delivered oxidized galectin-1 peripherally to the surgical site. Functional recovery was assessed by measurement of the degree of toe spread of the hind paw for 3 months after the sciatic nerve lesion. The recovery curves of toe spread in the test group showed a statistically significant improvement of functional recovery after day 21 by the application of oxidized recombinant human galectin-1 (rhGAL-1/Ox) compared to the control group. This functional recovery was supported by histological analysis performed by light microscopic examination. The regenerating myelinated fibers at the site 21 mm distal to the nerve-transected site were quantitatively examined at 100 days after the operation. The frequency distribution of myelinated fiber diameters showed that exogenous rhGAL-1/Ox increased the number and diameter of regenerating myelinated fibers; the number of medium-sized (6-11 microm in diameter) fibers increased significantly (P<0.05). These results indicate that oxidized galectin-1 promotes the restoration of nerve function after peripheral nerve injury. Thus, rhGAL-1/Ox may be a factor for functional restoration of injured peripheral nerves.

Plasmacytoid dendritic cells: from specific surface markers to specific cellular functions.

We have recently described a panel of monoclonal antibodies (mAb), that recognize two novel leukocyte surface antigens, BDCA-2 and BDCA-4. BDCA-2 is a novel type II C-type lectin specifically expressed by plasmacytoid dendritic cells (PDCs) that can internalize antigen for presentation to T cells. Furthermore, signaling via BDCA-2 may play a role in switching from interferon (IFN)-alpha/beta-controlled to interleukin (IL)-12-controlled immune response pathways, as triggering of BDCA-2 potently inhibits secretion of IFN-alpha/beta by PDCs and thereby promotes IL-12 p70 production in PDCs and other cells. Viruses may exploit this switch to escape innate antiviral immunity, but it may be beneficial for patients with systemic lupus erythematosus (SLE) if induced, for instance by anti BDCA-2 mAb treatment. BDCA-4 is shown here to be identical to neuropilin-1 (NP-1), a neuronal receptor for the axon guidance factors belonging to the class-3 semaphorin subfamily, and a receptor on endothelial and tumor cells for vascular endothelial growth factor (VEGF-A). In blood and bone marrow, BDCA-4/NP-1 is exclusively expressed on PDCs, but in tonsils also on a few other cells, primarily follicular B helper memory T cells (T(FH)).

CD52 is a novel costimulatory molecule for induction of CD4+ regulatory T cells.

We previously reported that 4C8 monoclonal antibody (mAb) provides a costimulatory signal to human CD4+ T cells and consequently induces regulatory T (Treg) cells, which are hypo-responsive and suppress the polyclonal response of bystander CD4+ cells in a contact-dependent manner. In this study, we identified the antigen of 4C8 mAb as CD52. Costimulation with Campath-1H, a humanized anti-CD52 mAb, also induced Treg cells. Anti-CD52-induced Treg cells suppressed the proliferation of both CD4+ and CD8+ T cells provided with polyclonal or allogeneic stimulation. When Treg cells were induced from Staphylococcal enterotoxin B (SEB) treated cells, they suppressed the response to SEB more efficiently than that to another superantigen, SEA. Furthermore, anti-CD52-induced Treg cells could be expanded by culture with IL-2 followed by CD52-costimulation, and co-injection of expanded Treg cells suppressed lethal xenogeneic graft versus host disease (GvHD) reactions in SCID mice caused by human peripheral blood mononuclear cells (PBMCs).