Sequential polarization and imprinting of type 1 T-helper lymphocytes by interferon-γ and interleukin-12

Differentiation of naive T lymphocytes into type I T helper (Th1) cells requires interferon-γ and interleukin-12. It is puzzling that interferon-γ induces the Th1 transcription factor T-bet, whereas interleukin-12 mediates Th1 cell lineage differentiation. We use mathematical modeling to analyze the expression kinetics of T-bet, interferon-γ, and the IL-12 receptor β2 chain (IL-12Rβ2) during Th1 cell differentiation, in the presence or absence of interleukin-12 or interferon-γ signaling. We show that interferon-γ induced initial T-bet expression, whereas IL-12Rβ2 was repressed by T cell receptor (TCR) signaling. The termination of TCR signaling permitted upregulation of IL-12Rβ2 by T-bet and interleukin-12 signaling that maintained T-bet expression. This late expression of T-bet, accompanied by the upregulation of the transcription factors Runx3 and Hlx, was required to imprint the Th cell for interferon-γ re-expression. Thus initial polarization and subsequent imprinting of Th1 cells are mediated by interlinked, sequentially acting positive feedback loops of TCR-interferon-γ-Stat1-T-bet and interleukin-12-Stat4-T-bet signaling

Low-Density Granulocytes Are a Novel Immunopathological Feature in Both Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Objective: To investigate whether low-density granulocytes (LDGs) are an immunophenotypic feature of patients with multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD). Methods: Blood samples were collected from 20 patients with NMOSD and 17 patients with MS, as well as from 15 patients with Systemic Lupus Erythematosus (SLE) and 23 Healthy Donors (HD). We isolated peripheral blood mononuclear cells (PBMCs) with density gradient separation and stained the cells with antibodies against CD14, CD15, CD16, and CD45, and analyzed the cells by flow cytometry or imaging flow cytometry. We defined LDGs as CD14-CD15(high) and calculated their share in total PBMC leukocytes (CD45+) as well as the share of CD16(hi) LDGs. Clinical data on disease course, medication, and antibody status were obtained. Results: LDGs were significantly more common in MS and NMOSD than in HDs, comparable to SLE samples (median values HD 0.2%, MS 0.9%, NMOSD 2.1%, SLE 4.3%). 0/23 of the HDs, but 17/20 NMOSD and 11/17 MS samples as well as 13/15 SLE samples had at least 0.7 % LDGs. NMOSD patients without continuous immunosuppressive treatment had significantly more LDGs compared to their treated counterparts. LDG nuclear morphology ranged from segmented to rounded, suggesting a heterogeneity within the group. Conclusion: LDGs are a feature of the immunophenotype in some patients with MS and NMOSD