Brain globins in physiology and pathology.

Globins are globular proteins for either transport or storage of oxygen which are critical for cellular metabolism. Four globins have been identified in rodent and human brains. Among them, neuroglobin, cytoglobin and hemoglobin chains are constitutively expressed in normal brain, while myoglobin is only expressed in some neurological disorders. Studies on the molecular structure, expression and functional features of these brain globins indicated that they may play crucial roles in maintenance of neural cell survival and activity, including neurons and astrocytes. Their regulation in neurological disorders may help thoroughly understand initiation and progression of ischemia, Alzheimer's disease and glioma, etc. Elucidation of the brain globin functions might remarkably improve medical strategies that sustain neurological homeostasis and treat neurological diseases. Here the expression pattern and functions of brain globins and their involvement in neurological disorders are reviewed.

Timing and dose regimens of marrow mesenchymal stem cell transplantation affect the outcomes and neuroinflammatory response after ischemic stroke.

AIMS: Intravenous transplantation of bone marrow mesenchymal stem cells (BMSCs) had been documented to improve functional outcome after ischemic stroke. However, the timing and appropriate cell number of transplantation to achieve better outcome after an episode of stroke remain further to be optimized. METHODS: To determine the optimal conditions, we transplanted different concentrations of BMSCs at different time points in a rat model of ischemic stroke. Infarction volume and neurological behavioral tests were performed after ischemia. RESULTS: We found that transplantation of BMSCs at 3 and 24 h, but not 7 days after focal ischemia, significantly reduced the lesion volume and improved motor deficits. We also found that transplanted cells at 1 × 10(6) to 10(7) , but not at 1 × 10(4) to 10(5) , significantly improved functional outcome after stroke. In addition to inhibiting macrophages/microglia activation in the ischemic brain, BMSC transplantation profoundly reduced infiltration of gamma delta T (γδT) cells, which are detrimental to the ischemic brain, and significantly increased regulatory T cells (Tregs), along with altered Treg-associated cytokines in the ischemic brain. CONCLUSIONS: Our data suggest that timing and cell dose of transplantation determine the therapeutic effects after focal ischemia by modulating poststroke neuroinflammation.

Growth-factor receptor-bound protein-2 (Grb2) signaling in B cells controls lymphoid follicle organization and germinal center reaction.

Grb2 (growth-factor receptor-bound protein-2) is a signaling adaptor that interacts with numerous receptors and intracellular signaling molecules. However, its role in B-cell development and function remains unknown. Here we show that ablation of Grb2 in B cells results in enhanced B-cell receptor signaling; however, mutant B cells do not form germinal centers in the spleen after antigen stimulation. Furthermore, mutant mice exhibit defects in splenic architecture resembling that observed in B-cell-specific lymphotoxin-ß-deficient mice, including disruption of marginal zone and follicular dendritic cell networks. We find that grb2(-/-) B cells are defective in lymphotoxin-ß expression. Although lymphotoxin can be up-regulated by chemokine CXCL13 and CD40 ligand stimulation in wild-type B cells, elevation of lymphotoxin expression in grb2(-/-) B cells is only induced by anti-CD40 but not by CXCL13. Our results thus define Grb2 as a nonredundant regulator that controls lymphoid follicle organization and germinal center reaction. Loss of Grb2 has no effect on B-cell chemotaxis to CXCL13, indicating that Grb2 executes this function by connecting the CXCR5 signaling pathway to lymphotoxin expression but not to chemotaxis.

Apoptosis in human germinal centre B cells by means of CC chemokine receptor 3 expression induced by interleukin-2 and interleukin-4.

BACKGROUND: CC chemokine receptor 3 (CCR3), expressed on some inflammatory cells, is a member of the chemokine receptor family. Its ligand is eotaxin/CCL11. In this research, we studied the expression and function of CCR3 induced by interleukin-2 (IL-2) and interleukin-4 (IL-4) on human germinal centre (GC) B cells. METHODS: Cells isolated from human tonsils were stimulated with IL-2 or/and IL-4 followed by bonding with eotaxin/CCL11. Flow cytometry was used to detect expression of CCR3 on GC B cells and apoptosis of GC B cells. Real time quantitative reverse transcription polymerase chain reaction and Northern blot assays were used to analyse the CCR3 mRNA expressed in the GC B cells. Chemotaxis and adhesion assays were used to determine the effect of eotaxin/CCL11 ligand bonded to CCR3 on GC B cells. RESULTS: There was no CCR3 expression on human freshly isolated GC B cells. The combination IL-2 and IL-4 could upregulate CCR3 mRNA and protein expression on GC B cells. Eotaxin could not induce GC B cell chemotaxis and adhesion but triggered apoptosis of GC B cells. CONCLUSION: IL-2 and IL-4 together induced expression of CCR3 on GC B cells, and the receptor acted as a death receptor.