Phenotypic and functional activation of hyporesponsive KIRnegNKG2Aneg human NK-cell precursors requires IL12p70 provided by Poly(I:C)-matured monocyte-derived dendritic cells

NK cell education: Physiological and pathological influences

Natural killer (NK) cells represent a critical defense against viral infections and cancers. NK cells require integration of activating and inhibitory NK cell receptors to detect target cells and the balance of these NK cell inputs defines the global NK cell response. The sensitivity of the response is largely defined by interactions between self-major histocompatibility complex class I (MHC-I) molecules and specific inhibitory NK cell receptors, so-called NK cell education. Thus, NK cell education is a crucial process to generate tuned effector NK cell responses in different diseases. In this review, we discuss the relationship between NK cell education and physiologic factors (type of self-MHC-I, self-MHC-I allelic variants, variant of the self-MHC-I-binding peptides, cytokine effects and inhibitory KIR expression) underlying NK cell education profiles (effector function or metabolism). Additionally, we describe the broad-spectrum of effector educated NK cell functions on different pathologies (such as HIV-1, CMV and tumors, among others).

Tim-3/Galectin-9 signaling pathway is involved in the cytokine changes in mice with alveolar echinococcosis

BACKGROUND

Tim-3/Galectin-9 is involved in the immune escape of many pathogens. However, the role of Tim-3/Galectin-9 in persistent infection of Echinococcus multilocularis (Em), which is related to immune escape, is still unclear.

OBJECTIVE

To investigate the role of Tim-3/Galectin-9 and related cytokines in mice with persistent infection of Em.

METHODS

Em infection model was established by injecting the protoscoleces. Serum was collected at days 2, 8, 30, 60, 90, 180 and 270 after infection. Lymphocytes were isolated from liver tissue samples with Ficoll. Tim-3 + CD4 + T percentage was analyzed by flow cytometry. CD4 + T cells were isolated from liver tissues of Em infected mice and cultured in vitro. The mRNA levels of Tim-3, Galectin-9, IFN-γ and IL-4 were detected by qRT-PCR. Cytokine levels in serum and culture supernatant (IFN-γ and IL-4) were analyzed by cytometric bead array.

RESULTS

The expression of Tim-3 and Galectin-9 mRNA significantly increased after 30 days of infection, reached peak on day 90, and then decreased slightly on days 180-270. The expression of IFN-γ mRNA, increased on day 2 and 8 after infection, slightly decreased on days 30-60, and obvious decreased on days 90-270, but were still higher than those of the control group. The expression of IL-4 mRNA gradually increased along with the time of infection. In serum of Em infected mice, level of IFN-γ peaked at day 30 and then gradually decreased; whereas IL-4 level peaked at day 90 and then gradually decreased. In vitro experiment found that Tim-3/Galectin-9 directly caused the changes in the levels of IFN-γ and IL-4.

CONCLUSIONS

Tim-3/Galectin-9 signaling pathway may be involved in the development of persistent infection of Em by regulating the production of Th1 and Th2 cytokines.

Characterization and Manipulation of the Crosstalk Between Dendritic and Natural Killer Cells Within the Tumor Microenvironment

Cellular therapy has entered the daily clinical life with the approval of CAR T cell therapeutics and dendritic cell (DCs) vaccines in the US and the EU. In addition, numerous other adoptive cellular products, including natural killer (NK) cells, are currently evaluated in early phase I/ II clinical trials for the treatment of cancer patients. Despite these promising accomplishments, various challenges remain to be mastered in order to ensure sustained therapeutic success. These include the identification of strategies by which tumor cells escape the immune system or establish an immunosuppressive tumor microenvironment (TME). As part of the innate immune system, DCs and NK cells are both present within the TME of various tumor entities. While NK cells are well known for their intrinsic anti-tumor activity by their cytotoxicity capacities and the secretion of pro-inflammatory cytokines, the role of DCs within the TME is a double-edged sword as different DC subsets have been described with either tumor-promoting or -inhibiting characteristics. In this review, we will discuss recent findings on the interaction of DCs and NK cells under physiological conditions and within the TME. One focus is the crosstalk of various DC subsets with NK cells and their impact on the progression or inhibition of tumor growth. In addition, we will provide suggestions to overcome the immunosuppressive outcome of the interaction of DCs and NK cells within the TME.

Targeting JAK2 reduces GVHD and xenograft rejection through regulation of T cell differentiation

Janus kinase 2 (JAK2) signal transduction is a critical mediator of the immune response. JAK2 is implicated in the onset of graft-versus-host disease (GVHD), which is a significant cause of transplant-related mortality after allogeneic hematopoietic cell transplantation (allo-HCT). Transfer of JAK2^-/- donor T cells to allogeneic recipients leads to attenuated GVHD yet maintains graft-versus-leukemia. Th1 differentiation among JAK2^-/- T cells is significantly decreased compared with wild-type controls. Conversely, iTreg and Th2 polarization is significantly increased among JAK2^-/- T cells. Pacritinib is a multikinase inhibitor with potent activity against JAK2. Pacritinib significantly reduces GVHD and xenogeneic skin graft rejection in distinct rodent models and maintains donor antitumor immunity. Moreover, pacritinib spares iTregs and polarizes Th2 responses as observed among JAK2^-/- T cells. Collectively, these data clearly identify JAK2 as a therapeutic target to control donor alloreactivity and promote iTreg responses after allo-HCT or solid organ transplantation. As such, a phase I/II acute GVHD prevention trial combining pacritinib with standard immune suppression after allo-HCT is actively being investigated (https://clinicaltrials.gov/ct2/show/NCT02891603).

Human Dendritic Cells Mitigate NK-Cell Dysfunction Mediated by Nonselective JAK1/2 Blockade

Janus kinase (JAK) inhibitors have achieved positive responses in myeloproliferative neoplasms, but at the expense of decreased natural killer (NK) cell numbers and compromised function. Selective JAK2 inhibition may also have a role in preventing and treating graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Although JAK inhibitors can impair monocyte-derived dendritic cell (moDC) activation and function and suppress effector T-cell responses, the effects on NK cells and the relevant mechanisms remain undefined. Using common γ_c cytokines and distinct human dendritic cell (DC) subtypes, we compared the effects of a JAK2-specific (TG101348) with a less selective JAK1/2 (ruxolitinib) inhibitor on NK-cell activation and function. Ruxolitinib treatment completely blocked IL2, IL15, and DC-mediated STAT5 phosphorylation, along with the capacity of NK cells to secrete IFNγ or lyse NK cell-sensitive targets. Only NK-cell proliferation stimulated by moDCs resisted ruxolitinib treatment. In contrast, TG101348 treatment of stimulated NK cells resulted in far less functional compromise. TG101348 completely inhibited only soluble IL15-mediated STAT5 phosphorylation, which Langerhans-type DCs (LCs), presenting membrane-bound IL15 in trans, could salvage. These results demonstrate that ruxolitinib's nonselective inhibition of JAK1/2 results in profound NK-cell dysfunction by blocking downstream pSTAT5, hence providing a persuasive rationale for the development of selective JAK2 inhibitors for immunotherapeutic applications. Cancer Immunol Res; 5(1); 52-60. ©2016 AACR.