Interleukin-12 (IL-12), a heterodimeric cytokine produced by activated monocytes and dendritic cells, plays a crucial role in regulating interferon (IFN)-γ production and in the generation of IFN–γ–producing T helper 1 (Th1) cells. Here we show that the IL-12 receptor (IL12R) β2 subunit, a recently cloned binding and signal transducing component of the IL-12R, is expressed on human Th1 but not Th2 clones and is induced during differentiation of human naive cells along the Th1 but not the Th2 pathway. IL-12 and type I but not type II interferons induce expression of the IL-12R β2 chain during in vitro T cell differentiation after antigen receptor triggering. The selective expression and regulation of the IL-12R β2 subunit may help to understand the basis of Th1/Th2 differentiation and may provide therapeutic options for altering the Th1/Th2 balance in several immuno-pathological conditions such as autoimmune diseases and allergies.

Triggering receptor expressed on myeloid cells 2 (TREM-2) is a membrane-bound receptor expressed by microglia and macrophages. Engagement of TREM-2 on these cells has been reported to reduce inflammatory responses and, in microglial cells, to promote phagocytosis. TREM-2 function is critical within the CNS, as its genetic deficiency in humans causes neurodegeneration with myelin and axonal loss. Blockade of TREM-2 worsened the mouse model for multiple sclerosis. In the present study, a soluble form of TREM-2 protein has been identified by immunoprecipitation and by ELISA. Soluble TREM-2 protein (sTREM-2) was detected in human CSF, and was compared among subjects with relapsing-remitting multiple sclerosis (RR-MS; n = 52), primary progressive multiple sclerosis (PP-MS; n = 21), other inflammatory neurologic diseases (OIND; n = 19), and non-inflammatory neurologic diseases (NIND; n = 41). Compared to NIND subjects, CSF sTREM-2 levels were significantly higher in RR-MS (P = 0.004 by ANOVA) and PP-MS (P < 0.001) subjects, as well as in OIND (P < 0.001) subjects. In contrast, levels of sTREM-2 in blood did not differ among the groups. Furthermore, TREM-2 was detected on a subset of CSF monocytes by flow cytometry, and was also highly expressed on myelin-laden macrophages in eight active demyelinating lesions from four autopsied multiple sclerosis subjects. The elevated levels of sTREM-2 in CSF of multiple sclerosis patients may inhibit the anti-inflammatory function of the membrane-bound receptor suggesting sTREM-2 to be a possible target for future therapies.

The triggering receptor expressed on myeloid cell type 1 (TREM-1) is a cell surface molecule that has been identified on both human and murine polymorphonuclear neutrophils and mature monocytes. The activation of TREM-1 in the presence of microbial components amplifies the inflammatory response and may be responsible for the hyperresponsiveness observed during the initial stage of sepsis. To investigate the effect of the modulation of the TREM-1 pathway during experimental murine sepsis, we used analogue synthetic peptides derived from the extracellular moiety of TREM-1. The TREM-1 ligand was expressed on both peritoneal and peripheral neutrophils during experimental peritonitis in mice. The TREM-1 peptides inhibited the recognition by TREM-1 of its ligand and protected endotoxinic mice from death. In septic rats, the TREM-1 peptides improved the hemodynamic status, attenuated the development of lactic acidosis, modulated the production of such proinflammatory cytokines as tumor necrosis factor alpha and interleukin-1␤, and improved survival. The protective effect of these peptides on arterial pressure could partly be explained by a decreased production of nitric oxide. These data suggest that in vivo modulation of TREM-1 might be a suitable therapeutic tool for the treatment of sepsis.

The triggering receptor expressed in myeloid (TREM) cells 2, referred to with the acronym TREM2, is a single-spanning membrane receptor of an immunoglobulin/lectin-like family. The members of this family operate through the interaction with a common coupling protein, DNAX-activation protein of 12 kDa (DAP12) which upon phosphorylation induces the activation of various intracellular signalling pathways (tyrosine kinases, phospholipase Cc). Activation of other Received December 20, 2008; revised manuscript received February 11, 2009; accepted April 21, 2009. Abbreviations used: BSA, bovine serum albumin; DAP12, DNAXactivation protein; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; hHsp60, human heat shock protein 60; HRP, horseradish peroxidase; Hsp60, heat shock protein 60; PBS, phosphate-buffered saline; PLOSL, polycystic lipomembraneous osteodysplasia with sclerosing leukoencephalopathy; rHsp60, rat heat shock protein 60; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; siRNA, short interfering RNA; TREM, triggering receptor expressed in myeloid cells. AbstractTriggering receptor expressed in myeloid (TREM) cells 2, a receptor expressed by myeloid cells, osteoclasts and microglia, is known to play a protective role in bones and brain. Mutations of the receptor (or of its coupling protein, DAP12) sustain in fact a genetic disease affecting the two organs, the polycystic lipomembraneous osteodysplasia with sclerosing leukoencephalopathy (PLOSL or Nasu-Hakola disease). So far, specific agonist(s) of TREM2 have not been identified and its (their) transduction mechanisms are largely unknown. Heat shock protein 60 (Hsp60) is a mitochondrial chaperone that can also be harboured at the cell surface. By using constructs including the extracellular domain of TREM2 and the Fc domain of IgGs we have identified Hsp60 as the only TREM2-binding protein exposed at the surface of neuroblastoma N2A cells and astrocytes, and lacking in U373 astrocytoma. Treatment with Hsp60 was found to stimulate the best known TREM2-dependent process, phagocytosis, however, only in the microglial N9 cells rich in the receptor. Upon TREM2 down-regulation, the Hsp60-induced stimulation of N9 phagocytosis was greatly attenuated. Hsp60 is also released by many cell types, segregated within exosomes or shedding vesicles which might then undergo dissolution. However, the affinity of its binding (K d = 3.8 lM) might be too low for the soluble chaperone released from the vesicles to the extracellular space to induce a significant activation of TREM2. It might in contrast be appropriate for the binding of TREM2 to Hsp60 exposed at the surface of cells closely interacting with microglia. The ensuing stimulation of phagocytosis could play protective effects on the brain. Keywords: receptor binding, surface-harboured agonist, western and far-western blotting, phagocytosis, polycystic lipomembraneous osteodysplasia with sclerosing leukoencephalopathy.

Interleukin-12 (IL-12) is a key cytokine for the development of T helper type 1 (Th1) responses; however, naïve CD4 þ T cells do not express IL-12Rb2, and are therefore unresponsive to IL-12. We have examined the mechanisms that control Th1-specific expression of the human IL12Rb2 gene at early time points after T-cell stimulation.We have identified a Th1-specific enhancer element that binds signal transducer and activator of transcription 4 (STAT4) in vivo in developing Th1 but not Th2 cells. T-cell receptor (TCR) signaling induced histone hyperacetylation and recruitment of BRG1, the ATPase subunit of the SWI/SNF-like BAF chromatin remodeling complex, to the IL-12Rb2 regulatory regions and was associated with lowlevel gene transcription at the IL-12Rb2 locus. However, high-level IL-12Rb2 expression required TCR triggering in the presence of IL-12. Our results indicate a synergistic role of TCR-induced chromatin remodeling and cytokineinduced STAT4 activation to direct IL-12Rb2 expression during Th1 cell development.

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Major targets for autoantibodies associated with the development of insulin-dependent diabetes mellitus (IDDM) include tryptic fragments with a molecular mass of 37 kDa and/or 40

The last century has witnessed the emergence of several previously unknown viruses as life-threatening human pathogens. Several examples include HIV, Ebola, Lujo, and, most recently, the Middle East respiratory syndrome (MERS) and Ebola. In this study, we describe a method for the swift generation of a human-derived monoclonal antibody, known as LCA60, as a treatment for MERS infections. LCA60 antibody was generated using the Cellclone Technology from the immortalized B cells of a human donor recovering from MERS. Only four months were required from the initial screening of B cells to the development of a stable CHO cell line suitable for the production of clinical grade antibody, thereby delineating a rapid pathway for the development of antiviral therapies against emerging viruses. Currently, the LCA60 antibody is being considered for clinical development, which includes prophylaxis in individuals at risk and a treatment for severe MERS-CoV infections.