Liu Junyan

Vα24-Invariant NKT Cells from Patients with Allergic Asthma Express CCR9 at High Frequency and Induce Th2 Bias of CD3+ T Cells upon CD226 Engagement

We have demonstrated that Vα24+Vβ11+ invariant (Vα24+i) NKT cells from patients with allergic asthma express CCR9 at high frequency. CCR9 ligand CCL25 induces chemotaxis of asthmatic Vα24+i NKT cells but not the normal cells. A large number of CCR9-positive Vα24+i NKT cells are found in asthmatic bronchi mucosa, where high levels of Th2 cytokines are detected. Asthmatic Vα24+i NKT cells, themselves Th1 biased, induce CD3+ T cells into an expression of Th2 cytokines (IL-4 and IL-13) in cell-cell contact manner in vitro. CD226 are overexpressed on asthmatic Vα24+i NKT cells. CCL25/CCR9 ligation causes directly phosphorylation of CD226, indicating that CCL25/CCR9 signals can cross-talk with CD226 signals to activate Vα24+i NKT cells. Prestimulation with immobilized CD226 mAb does not change ability of asthmatic Vα24+i NKT cells to induce Th2-cytokine production, whereas soluble CD226 mAb or short hairpin RNA of CD226 inhibits Vα24+i NKT cells to induce Th2-cytokine production by CD3+ T cells, indicating that CD226 engagement is necessary for Vα24+i NKT cells to induce Th2 bias of CD3+ T cells. Our results are providing with direct evidence that aberration of CCR9 expression on asthmatic Vα24+i NKT cells. CCL25 is first time shown promoting the recruitment of CCR9-expressing Vα24+i NKT cells into the lung to promote other T cells to produce Th2 cytokines to establish and develop allergic asthma. Our findings provide evidence that abnormal asthmatic Vα24+i NKT cells induce systemically and locally a Th2 bias in T cells that is at least partially critical for the pathogenesis of allergic asthma.

CC chemokine ligand 25 enhances resistance to apoptosis in CD4+ T cells from patients with T-cell lineage acute and chronic lymphocytic leukemia by means of livin activation.

We investigated CD4 and CD8 double-positive thymocytes, CD4+ T cells from typical patients with T-cell lineage acute lymphocytic leukemia (T-ALL) and T cell lineage chronic lymphocytic leukemia (T-CLL), and MOLT4 T cells in terms of CC chemokine ligand 25 (CCL25) functions of induction of resistance to tumor necrosis factor α (TNF-α)–mediated apoptosis. We found that CCL25 selectively enhanced resistance to TNF-α–mediated apoptosis in T-ALL and T-CLL CD4+ T cells as well as in MOLT4 T cells, but CD4 and CD8 double-positive thymocytes did not. One member protein of the inhibitor of apoptosis protein (IAP) family, Livin, was selectively expressed in the malignant cells at higher levels, particularly in T-ALL CD4+ T cells, in comparison with the expression in CD4 and CD8 double-positive thymocytes. After stimulation with CCL25 and apoptotic induction with TNF-α, the expression levels of Livin in these malignant cells were significantly increased. CCL25/thymus-expressed chemokine (TECK), by means of CC chemokine receptor 9 (CCR9) ligation, selectively activated Livin to enhance resistance to TNF-α–mediated apoptosis in c-jun-NH2-kinase 1 (JNK1) kinase-dependent manner. These findings suggested differential functions of CCR9/CCL25 in distinct types of cells. CD4 and CD8 double-positive thymocytes used CCR9/CCL25 for migration, homing, development, maturation, selection, cell homeostasis, whereas malignant cells, particularly T-ALL CD4+ T cells, used CCR9/CCL25 for infiltration, resistance to apoptosis, and inappropriate proliferation.

Different Neurotropic Pathogens Elicit Neurotoxic CCR9- or Neurosupportive CXCR3-Expressing Microglia

What mechanism that determines microglia accomplishing destructive or constructive role in CNS remains nebulous. We report here that intracranial priming and rechallenging with Toxoplasma gondii in mice elicit neurotoxic CCR9+Irg1+ (immunoresponsive gene 1) microglia, which render resistance to apoptosis and produce a high level of TNF-α; priming and rechallenging with lymphocytic choriomeningitis virus elicit neurosupportive CXCR3+Irg1− microglia, which are sensitive to apoptosis and produce a high level of IL-10 and TGF-β. Administration of CCR9 and/or Irg1 small interfering RNA alters the frequency and functional profiles of neurotoxic CCR9+Irg1+ and neurosupportive CXCR3+Irg1− microglia in vivo. Moreover, by using a series of different neurotropic pathogens, including intracellular parasites, chronic virus, bacteria, toxic substances, and CNS injury to intracranially prime and subsequent rechallenge mice, the bi-directional elicitation of microglia has been confirmed as neurotoxic CCR9+Irg1+ and neurosupportive CXCR3+Irg1− cells in these mouse models. These data suggest that there exist two different types of microglia, providing with a novel insight into microglial involvement in neurodegenerative and neuroinflammatory pathogenesis such as Alzheimer’s disease and AIDS dementia.

Aberration of CCR7+ CD8+ memory T cells from patients with systemic lupus erythematosus: an inducer of T helper type 2 bias of CD4+ T cells

Chemokine receptors are important in the entry of leucocytes into the inflammatory sites of systemic lupus erythematosus (SLE). CCR7+ and CCR7– memory T cells exert different functions in homing, cytokine production and cytotoxicity. To determine whether differential expression and functions of the CCR7 occur in SLE patients, we examined CCR3, CCR4, CCR5, CCR7 and CCR9 on CD4+ and CD8+ T cells from normal and SLE subjects. Flow cytometry, real‐time quantitative reverse transcription polymerase chain reactions and Northern blotting were used to detect the expression of chemokine receptors and cytokines; a chemotaxis assay was used to detect their functions. CD4+ T‐cell stimulation with syngeneic CCR7+ CD8+ CD45RO+ T cells and dendritic cells (including transwell chambers) was used to induce cytokine expression. We demonstrated that CCR7 was selectively, frequently and functionally expressed on CD8+ (94·8%) but not on CD4+ (16·1%) T cells from patients with active SLE, whereas this phenomenon was not seen in normal subjects and in those whose SLE was inactive. CCR7+ CD8+ CD45RO+ memory T cells from patients with active SLE, themselves T helper type 2 (Th2) biased, were inducers of Th2 bias in CD4+ T cells in a cell–cell contact manner in vitro, meanwhile, the cells from both normal subjects and those whose SLE was inactive drove CD4+ T cells into a regulatory T‐cell‐derived cytokine pattern. Our findings might provide new clues to understanding the functions of CCR7+ CD8+ CD45RO+‘central’ memory T cells in autoimmue diseases (such as SLE). We suggest that in the case of active SLE, CCR7+ central memory T cells were able to enter peripheral blood and inflammatory sites from secondary lymphoid organs, were continuously expressing CCR7, and interacted with dendritic cells and functioned as CCR7–‘effector’ memory T cells, which were described in normal humans.

Selectively frequent expression of CXCR5 enhances resistance to apoptosis in CD8 + CD34 + T cells from patients with T-cell-lineage acute lymphocytic leukemia

We investigated CD4+CD34+, CD8+CD34+, CD4+CD34−, and CD8+CD34− T cells from cord blood and from typical patients with T-cell-lineage acute lymphocytic leukemia and T-cell-lineage chronic lymphocytic leukemia in terms of expression and functions of CXCR5/CXCL13. We found that CXCR5 was selectively frequently expressed on T-cell-lineage acute (chronic) lymphocytic leukemia (T-ALL) CD8+CD34+ T cells, but not on T-ALL CD4+CD34+, CD4+CD34−, and CD8+CD34− T cells. CXCR5 was rarely expressed on all types of CD34+ and CD34− CB or T-CLL T cells. CXCL13/B cells attracting chemokine 1 induced significant resistance to TNF-α-mediated apoptosis in T-ALL CD8+CD34+ T cells, instead of induction of chemotactic and adhesive responsiveness. A proliferation-inducing ligand expression in T-ALL CD8+CD34+ T cells was upregulated by CXCL13/BCA-1 (B-cell attracting chemokine 1). The CXCR5/CXCL13 pair by means of activation of APRIL (A proliferation-inducing ligand) induced resistance to apoptosis in T-ALL CD8+CD34+ T cells in livin-dependent manner. In this process, cell–cell contact in culture was necessary. Based on our findings, we suggested that there were differential functions of CXCR5/CXCL13 in distinct types of cells. Normal lymphocytes, especially naïve B and T cells, utilized CXCR5/CXCL13 for migration, homing, maturation, and cell homeostasis, as well as secondary lymphoid tissue organogenesis. Meanwhile, certain malignant cells took advantages of CXCR5/CXCL13 for infiltration, resistance to apoptosis, and inappropriate proliferation.

Highly up-regulated CXCR3 expression on eosinophils in mice infected with Schistosoma japonicum

CXCR3, predominately expressed on memory/activated T cells, is a receptor for both interferon‐γ inducible protein‐10/CXC ligand 10 (CXCL10) and monokine induced by interferon‐γ/CXCL9. We reported here that CXCR3 was highly up‐regulated on infiltrating eosinophils in Schistosoma japonicum egg‐induced granuloma in the mouse liver. It was also highly and functionally up‐regulated on peritoneal exudate eosinophils in mice infected with S. japonicum. The phenomena were demonstrated at protein and mRNA levels using immunohisto‐ and immunocytochemistry evaluation of biopsy, flow cytometry and real‐time quantitative reverse transcriptase–polymerase chain reaction technique, and verified by Northern blotting and chemotaxis assay in vitro. We also found that CCR3 expression on the infiltrating and peritoneal exudate cells was significantly decreased, CXCR4 expression was unchanged during the 42‐day period of infection. We screened mRNA expression levels of the all known chemokine receptors in purified peritoneal exudate eosinophils and liver granuloma dominated by eosinophils. CXCR3 was highly and functionally up‐regulated on peritoneal exudate eosinophils in mice infected with S. japonicum, meanwhile CCR3 was significantly and functionally down‐regulated in these cells. The findings could lead to a better understanding of the chemokine receptor expression pattern of eosinophils at inflamed tissue sites caused by parasites. These could be also crucial for establishing a therapeutic strategy for eosinophilic inflammation via intervention in chemokine actions.

Heterologous expression ofMycobacterium tuberculosis Ag85B inPichia pastoris

The DNA fragment encoding matureMycobacterium tuberculosis major secretory protein Ag85B was inserted into thePichia pastoris secretory expression vector pHBM905A, under the control of theAOX1 promoter. The recombinant plasmid pHBM905A-85B linearized bySal I was introduced intoPichia pastoris strain GS115 by PEG1000 transformation method. After phenotype screening and PCR identification, the resulting GS115-pHBM905A-85B strain was cultivated and induced with methanol. The recombinant Ag85B protein in secreted form was attained with molecular weight of 35×103 approximately detected by SDS-PAGE and Western blot. ELISA experiment proved that the protein had good antigen specificity. Secretory expression of recombinantM. tuberculosis Ag85B inP. pastoris will open a door to mass production of the protein in heterologous host and allow ready evaluation of its immunological function.