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Expression of the activating CD94/NKG2C killer lectin-like receptor (KLR) specific for HLA-E was analyzed in peripheral blood lymphocytes (PBLs) from healthy adult blood donors; the expression of other natural killer (NK) cell receptors (ie, CD94/NKG2A, KIR, CD85j, CD161, NKp46, NKp30, and NKG2D) was also studied. Human cytomegalovirus (HCMV) infection as well as the HLA-E and killer immunoglobulin-like receptor (KIR) genotypes were considered as potentially relevant variables associated with CD94/NKG2C expression. The proportion of NKG2C ؉ lymphocytes varied within a wide range (<0.1% to 22.1%), and a significant correlation (r ‫؍‬ 0.83; P < .001) between NKG2C ؉ NK and T cells was noticed. The HLA-E genotype and the number of activating KIR genes of the donors were not significantly related to the percentage of NKG2C ؉ lymphocytes. By contrast, a positive serology for HCMV, but not for other herpesviruses (ie, Epstein-Barr and herpes simplex), turned out to be strongly associated (P < specifically recognize HLA class I molecules and are expressed by natural killer and T-cell subsets. 1-4 Single cells 2 bear variable combinations of these natural killer cell receptors (NKRs), presumably resulting from stochastic gene activation/silencing events that take place during their maturation. 5 The diversity of NKRs observed in different individuals is in part genetically determined, because distinct KIR haplotypes include variable sets of genes. 1 On the other hand, there is evidence that microbial infections may also influence the NKR repertoire. In this regard, murine cytomegalovirus (MCMV) promotes an expansion of NK cells bearing the Ly49H receptor specific for the m157 viral glycoprotein, 6 which plays a crucial role in the immune response to infection. [7][8][9] Moreover, increased proportions of CD8 ϩ T cells with an effector/ memory phenotype bearing inhibitory NKRs (ie, CD94/NKG2A) have been observed in mice infected by different viruses 10-12 as well as in human immunodeficiency virus (HIV)-infected patients. 13 CD94, NKG2A, and NKG2C are C-type lectins encoded at the NK gene complex (NKC) in human chromosome 12. 14 Surface expression of NKG2A/C molecules requires their covalent assembly with CD94. 4,15,16 The CD94/NKG2A heterodimer constitutes an inhibitory receptor that recruits the protein tyrosine phosphatase containing SH2 domain-1 (SHP-1) through the immunoreceptor tyrosine-based inhibitory motif (ITIM)-bearing NKG2A subunit, whereas CD94/NKG2C is coupled to a tyrosine kinase activation pathway through the DAP12 adapter. 17,18 In human beings, both NKRs specifically recognize HLA-E, which presents peptides derived from the signal sequences of other HLA class I molecules [19][20][21][22] ; HLA-E allotypes contain either an Arg (HLA-E R107 ) or a Gly (HLA-E G107 ) at position 107. 23 The biologic relevance of such structural dimorphism remains unclear, but it may affect surface expression levels of the class Ib molecule 24,25 and its interaction with CD94/NKG2 receptors. 26 A number of studies have addre...

IntroductionHuman cytomegalovirus (HCMV) infection generally follows a subclinical course, but may lead to severe disorders in immunocompromised individuals and is a main cause of infectious congenital diseases. HCMV remains latent in immunocompetent hosts, undergoing occasional reactivation. 1 Studies in murine models revealed that an effective defense against CMV requires the participation of natural killer (NK) and T cells. 2,3 Detection of antibodies and CD8 ϩ T lymphocytes specific for HCMV antigens allow an assessment of the adaptive immune response to the pathogen. 4,5 To escape from CD8 ϩ T cells, HCMV inhibits the expression of human leukocyte antigen (HLA) class I molecules and interferes with antigen presentation using a set of glycoproteins (US2, US3, US6, US10, and US11) whose genes are clustered within the unique short (US) region of the virus genome. [6][7][8] The loss of HLA class I molecules in HCMV-infected cells impairs the engagement of inhibitory receptors and prompts the activation of NK cell effector functions; reciprocally, the virus has developed several strategies to evade NK-mediated recognition. 9 The nature of receptor-ligand interactions involved in the NK cell response to CMV-infected cells is incompletely understood. In strains of mice expressing the Ly49H receptor, NK cell functions are triggered upon recognition of the m157 mouse CMV (MCMV) glycoprotein, becoming essential to control replication; 10,11 by contrast, human activating NK cell receptors (NKRs) specific for HCMV molecules have not been identified. The involvement of activating killer immunoglobulin (Ig)-like receptors (KIRs) and natural cytotoxicity receptors (NCRs; ie, NKp46, NKp30, and NKp44) in the response to HCMV is uncertain. The interaction of the pp65 HCMV tegument protein with NKp30 has been reported to inhibit rather than to activate NK cell functions. 12 The ability of the UL16 HCMV molecule to interfere with the surface expression of NKG2D ligands, [13][14][15] and the evidence that similar evasion mechanisms operate in MCMV infection, 16,17 support an important role for this killer lectinlike receptor (KLR) in the antiviral defense. 18 Recently, the UL141 HCMV molecule has been shown to inhibit the expression in infected cells of CD155, a ligand for the DNAM-1 stimulating receptor. 19 HCMV may also escape NK-mediated surveillance by keeping inhibitory receptors for HLA class I molecules engaged. The viral UL18 molecule binds with high affinity to the ILT2 (CD85j) inhibitory receptor, 20,21 though its role in immune evasion has not been precisely elucidated. 9 On the other hand, HLA-E appears constitutively resistant to the action of US2 and US11, 22 and it also becomes refractory to the action of US6 when bound to a peptide from the leader sequence of the HCMV UL40 protein. 23 For personal use only. on May 10, 2018. by guest www.bloodjournal.org From interfere with the NK cell response by engaging the inhibitory CD94/NKG2A KLR. 25 We recently reported 26 that healthy HCMV-seropositive individuals display...

An increasing number of studies show how changes in intracellular metabolic pathways alter tumor and immune cell function. However, little information about metabolic changes in other cell types, including synovial fibroblasts, is available. In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) are the most common cell type at the pannus–cartilage junction and contribute to joint destruction through their production of cytokines, chemokines, and matrix-degrading molecules and by migrating and invading joint cartilage. In this review, we show that these cells differ from healthy synovial fibroblasts, not only in their marker expression, proto-oncogene expression, or their epigenetic changes, but also in their intracellular metabolism. These metabolic changes must occur due to the stressful microenvironment of inflamed tissues, where concentrations of crucial nutrients such as glucose, glutamine, and oxygen are spatially and temporally heterogeneous. In addition, these metabolic changes will increase metabolite exchange between fibroblast and other synovial cells, which can potentially be activated. Glucose and phospholipid metabolism as well as bioactive lipids, including sphingosine-1-phosphate and lysophosphatidic acid, among others, are involved in FLS activation. These metabolic changes likely contribute to FLS involvement in aspects of immune response initiation or abnormal immune responses and strongly contribute to joint destruction.

Cirrhosis is the end result of chronic liver disease. Hepatic stellate cells (HSC) are believed to be the major source of collagenproducing myofibroblasts in cirrhotic livers. Portal fibroblasts, bone marrow-derived cells, and epithelial to mesenchymal transition (EMT) might also contribute to the myofibroblast population in damaged livers. Fibroblast-specific protein 1 (FSP1, also called S100A4) is considered a marker of fibroblasts in different organs undergoing tissue remodeling and is used to identify fibroblasts derived from EMT in several organs including the liver. The aim of this study was to characterize FSP1-positive cells in human and experimental liver disease. FSP1-positive cells were increased in human and mouse experimental liver injury including liver cancer. However, FSP1 was not expressed by HSC or type I collagenproducing fibroblasts. Likewise, FSP1-positive cells did not express classical myofibroblast markers, including αSMA and desmin, and were not myofibroblast precursors in injured livers as evaluated by genetic lineage tracing experiments. Surprisingly, FSP1-positive cells expressed F4/80 and other markers of the myeloid-monocytic lineage as evaluated by double immunofluorescence staining, cell fate tracking, flow cytometry, and transcriptional profiling. Similar results were obtained for bone marrow-derived and peritoneal macrophages. FSP1-positive cells were characterized by increased expression of COX2, osteopontin, inflammatory cytokines, and chemokines but reduced expression of MMP3 and TIMP3 compared with Kupffer cells/macrophages. These findings suggest that FSP1 is a marker of a specific subset of inflammatory macrophages in liver injury, fibrosis, and cancer.tumor microenvironment

Objective. Interleukin-1␤ (IL-1␤) is a key cytokine linked to the pathogenesis of acute arthritis. Caspase 1, neutrophil elastase, and chymase all process proIL-1␤ to its biologically active form. This study was undertaken to examine the potential contributions of each of these proteases in experimental models of inflammatory arthritis.Methods. Conclusion. The production of IL-1␤ by neutrophils and mast cells is not exclusively dependent on caspase 1, and other proteases can compensate for the loss of caspase 1 in vivo. These pathways might therefore compromise the caspase 1-targeted therapies in neutrophil-predominant arthritis.

In healthy blood donors, serological positivity for human cytomegalovirus (HCMV) is associated with an increased proportion of NK cells bearing the CD94/NKG2C NK cell receptor (NKR). The expression of the activating CD94/NKG2C NKR and of the inhibitory CD94/NKG2A NKR was studied in a cohort of 45 aviremic human immunodeficiency virus type 1 (HIV-1)-positive patients receiving highly active antiretroviral therapy. The proportions of NKG2C+ NK cells were significantly increased in HIV-1-positive patients (mean +/- SD, 25.9% +/- 23.0%), compared with those in 31 healthy individuals (mean +/- SD, 16.1% +/- 20.7%). Yet, the association vanished when HCMV serological status was considered in a multivariate regression model. These results support the conclusion that changes in the NKR repertoire in HIV1-positive patients are related to a concomitant HCMV infection.

Objective Up-regulation of glucose metabolism has been implicated not only in tumor cell growth but also in immune cells upon activation. However, little is known about the metabolite profile in rheumatoid arthritis (RA), particularly in fibroblast-like synoviocytes (FLS). This study was undertaken to evaluate whether changes in glucose metabolism in RA FLS could play a role in inflammation and joint damage. Methods Synovium and FLS were obtained from patients with RA and patients with osteoarthritis (OA). The rate of glycolysis after stimulation of FLS with lipopolysaccharide and platelet-derived growth factor BB was measured using glycolysis stress test technology. FLS function was evaluated using a glycolysis inhibitor, 2-deoxy-D-glucose (2-DG). After stimulation of the FLS, a migration scratch assay, MTT assay, and enzyme-linked immunosorbent assay were performed to measure the effect of 2-DG on FLS migration, viability of the FLS, and cytokine secretion, respectively. IRDye 800CW 2-DG was used to assess glucose uptake in the arthritic joints and stromal cells of mice after K/BxN mouse serum transfer. The mice were injected daily, intraperitoneally, with 3-bromopyruvate (BrPa; 5 mg/kg) to assess the effect of inhibition of glycolysis in vivo. Results Compared to human OA FLS, the balance between glycolysis and oxidative phosphorylation was shifted toward glycolysis in RA FLS. Glucose transporter 1 (GLUT1) messenger RNA (mRNA) expression correlated with baseline functions of the RA FLS. Glucose deprivation or incubation of the FLS with glycolytic inhibitors impaired cytokine secretion and decreased the rate of proliferation and migration of the cells. In a mouse model of inflammatory arthritis, GLUT1 mRNA expression in the synovial lining cells was observed, and increased levels of glucose uptake and glycolytic gene expression were detected in the stromal compartment of the arthritic mouse joints. Inhibition of glycolysis by BrPa, administered in vivo, significantly decreased the severity of arthritis in this mousemodel. Conclusion Targeting metabolic pathways is a novel approach to understanding the mechanisms of disease. Inhibition of glycolysis may directly modulate synoviocyte-mediated inflammatory functions and could be an effective treatment strategy for arthritis.