Biomedical subjects

Anja Fuchs

Publications and source records attributed to Anja Fuchs.

7 recordsLinked to original sources

PubMed2015

Transcriptional programs define molecular characteristics of innate lymphoid cell classes and subsets.

The recognized diversity of innate lymphoid cells (ILCs) is rapidly expanding. Three ILC classes have emerged, ILC1, ILC2 and ILC3, with ILC1 and ILC3 including several subsets. The classification of some subsets is unclear, and it remains controversial whether natural killer (NK) cells and ILC1 cells are distinct cell types. To address these issues, we analyzed gene expression in ILCs and NK cells from mouse small intestine, spleen and liver, as part of the Immunological Genome Project. The results showed unique gene-expression patterns for some ILCs and overlapping patterns for ILC1 cells and NK cells, whereas other ILC subsets remained indistinguishable. We identified a transcriptional program shared by small intestine ILCs and a core ILC signature. We revealed and discuss transcripts that suggest previously unknown functions and developmental paths for ILCs.

Animals↗

PubMed2006

The role of NK cell recognition of nectin and nectin-like proteins in tumor immunosurveillance.

Natural killer (NK) cells have important functions in the innate immunity to tumors. Recognition of tumor cells by NK cells is mediated by the interaction of activating and inhibitory NK cell receptors with ligands expressed on the tumor target. In addition, NK cell-target cell interactions require the engagement of adhesion molecules that stabilize the cell-cell conjugate. Recently, several novel NK cell receptors have been reported to regulate NK cell adhesion and activation through interaction with ligands of the nectin and nectin-like (Necl) family of adhesion molecules. We here review current knowledge on these receptors, CD226, CD96 and CRTAM, and their role in tumor immunosurveillance.

Animals↗

PubMed2006

CpG-induced tyrosine phosphorylation occurs via a TLR9-independent mechanism and is required for cytokine secretion.

Toll-like receptors (TLRs) recognize molecular patterns preferentially expressed by pathogens. In endosomes, TLR9 is activated by unmethylated bacterial DNA, resulting in proinflammatory cytokine secretion via the adaptor protein MyD88. We demonstrate that CpG oligonucleotides activate a TLR9-independent pathway initiated by two Src family kinases, Hck and Lyn, which trigger a tyrosine phosphorylation-mediated signaling cascade. This cascade induces actin cytoskeleton reorganization, resulting in cell spreading, adhesion, and motility. CpG-induced actin polymerization originates at the plasma membrane, rather than in endosomes. Chloroquine, an inhibitor of CpG-triggered cytokine secretion, blocked TLR9/MyD88-dependent cytokine secretion as expected but failed to inhibit CpG-induced Src family kinase activation and its dependent cellular responses. Knock down of Src family kinase expression or the use of specific kinase inhibitors blocked MyD88-dependent signaling and cytokine secretion, providing evidence that tyrosine phosphorylation is both CpG induced and an upstream requirement for the engagement of TLR9. The Src family pathway intersects the TLR9-MyD88 pathway by promoting the tyrosine phosphorylation of TLR9 and the recruitment of Syk to this receptor.

Actin Cytoskeleton↗

PubMed2005

Paradoxic inhibition of human natural interferon-producing cells by the activating receptor NKp44.

Natural killer (NK) cell-mediated cytotoxicity is triggered by multiple activating receptors associated with the signaling adaptor protein DNAX activation protein 12/killer cell-activating receptor-associated protein (DAP12/KARAP). Here, we show that one of these receptors, NKp44, is present on a subset of natural interferon-producing cells (IPCs) in tonsils. NKp44 expression can also be induced on blood IPCs after in vitro culture with interleukin 3 (IL-3). Crosslinking of NKp44 does not trigger IPC-mediated cytotoxicity but, paradoxically, inhibits interferon alpha (IFN-alpha) production by IPCs in response to cytosine-phosphate-guanosine (CpG) oligonucleotides. We find that IPCs in tonsils are in close contact with CD8+ T cells and demonstrate that a subset of memory CD8+ T cells produces IL-3. Therefore, IL-3-mediated induction of NKp44 on IPCs may be an important component of the ongoing crosstalk between the innate and adaptive immune response that allows memory CD8+ T cells to control the IPC response to virus.

CD8-Positive T-Lymphocytes↗

PubMed2004

Adhesion of human T cells to antigen-presenting cells through SIRPbeta2-CD47 interaction costimulates T-cell proliferation.

Signal-regulatory proteins (SIRPs) are transmembrane glycoproteins belonging to the immunoglobulin (Ig) superfamily that are expressed in the immune and central nervous systems. SIRPalpha binds CD47 and inhibits the function of macrophages, dendritic cells, and granulocytes, whereas SIRPbeta1 is an orphan receptor that activates the same cell types. A recently identified third member of the SIRP family, SIRPbeta2, is as yet uncharacterized in terms of expression, specificity, and function. Here, we show that SIRPbeta2 is expressed on T cells and activated natural killer (NK) cells and, like SIRPalpha, binds CD47, mediating cell-cell adhesion. Consequently, engagement of SIRPbeta2 on T cells by CD47 on antigen-presenting cells results in enhanced antigen-specific T-cell proliferation.

CD47 Antigen↗

PubMed2004

Cutting edge: CD96 (tactile) promotes NK cell-target cell adhesion by interacting with the poliovirus receptor (CD155).

The poliovirus receptor (PVR) belongs to a large family of Ig molecules called nectins and nectin-like proteins, which mediate cell-cell adhesion, cell migration, and serve as entry receptors for viruses. It has been recently shown that human NK cells recognize PVR through the receptor DNAM-1, which triggers NK cell stimulation in association with beta(2) integrin. In this study, we show that NK cells recognize PVR through an additional receptor, CD96, or T cell-activated increased late expression (Tactile). CD96 promotes NK cell adhesion to target cells expressing PVR, stimulates cytotoxicity of activated NK cells, and mediates acquisition of PVR from target cells. Thus, NK cells have evolved a dual receptor system that recognizes nectins and nectin-like molecules on target cells and mediates NK cell adhesion and triggering of effector functions. As PVR is highly expressed in certain tumors, this receptor system may be critical for NK cell recognition of tumors.

Animals↗

PubMed2004

NK cell and DC interactions.

Recent interest has focused on interactions between natural killer (NK) cells and dendritic cells (DCs). In vitro and in vivo studies have demonstrated various effects of NK-DC interactions, including activation and cytokine production, maturation of DCs and NK-cell lysis of certain autologous DCs. These interactions are important during an immune response in vivo, however, it remains unclear where in the body NK cells and DCs might interact and whether observed in vitro crosstalk between these cell types happens in vivo. We propose evidence for at least two potential locations of in vivo interactions for human NK cells and DCs, including sites of inflammation and lymph nodes.

Animals↗