Expansion of Fcγ Receptor IIIa-Positive Macrophages, Ficolin 1-Positive Monocyte-Derived Dendritic Cells, and Plasmacytoid Dendritic Cells Associated With Severe Skin Disease in Systemic Sclerosis

OBJECTIVE

In this study, we sought a comprehensive understanding of myeloid cell types driving fibrosis in diffuse cutaneous systemic sclerosis (dcSSc) skin.

METHODS

We analyzed the transcriptomes of 2,465 myeloid cells from skin biopsy specimens from 12 dcSSc patients and 10 healthy control subjects using single-cell RNA sequencing. Monocyte-derived dendritic cells (mo-DCs) were assessed using immunohistochemical staining and immunofluorescence analyses targeting ficolin-1 (FCN-1).

RESULTS

A t-distributed stochastic neighbor embedding analysis of single-cell transcriptome data revealed 12 myeloid cell clusters, 9 of which paralleled previously described healthy control macrophage/DC clusters, and 3 of which were dcSSc-specific myeloid cell clusters. One SSc-associated macrophage cluster, highly expressing Fcγ receptor IIIA, was suggested on pseudotime analysis to be derived from normal CCR1+ and MARCO+ macrophages. A second SSc-associated myeloid population highly expressed monocyte markers FCN-1, epiregulin, S100A8, and S100A9, but was closely related to type 2 conventional DCs on pseudotime analysis and identified as mo-DCs. Mo-DCs were associated with more severe skin disease. Proliferating macrophages and plasmacytoid DCs were detected almost exclusively in dcSSc skin, the latter clustering with B cells and apparently derived from lymphoid progenitors.

CONCLUSION

Transcriptional signatures in these and other myeloid populations indicate innate immune system activation, possibly through Toll-like receptors and highly up-regulated chemokines. However, the appearance and activation of myeloid cells varies between patients, indicating potential differences in the underlying pathogenesis and/or temporal disease activity in dcSSc.

Immune Checkpoint Inhibitor-Induced Thyroiditis Is Associated with Increased Intrathyroidal T Lymphocyte Subpopulations

Background: Immune checkpoint inhibitors (ICIs) frequently cause thyroid dysfunction but their underlying mechanism remains unclear. We have previously demonstrated increased circulating natural killer (NK) cells and human leukocyte antigen (HLA)-DR surface expression on inflammatory intermediate CD14⁺CD16⁺ monocytes in programmed cell death protein-1 (PD-1) inhibitor-treated patients. This study characterizes intrathyroidal and circulating immune cells and class II HLA in ICI-induced thyroiditis. Methods: This is a single-center prospective cohort study of 10 patients with ICI-induced thyroiditis by flow cytometry of thyroid fine needle aspirates (n = 9) and peripheral blood (n = 7) as compared with healthy thyroid samples (n = 5) and healthy volunteer blood samples (n = 44); HLA class II was tested in n = 9. Results: ICI-induced thyroiditis samples demonstrated overall increased T lymphocytes (61.3% vs. 20.1%, p = 0.00006), CD4^-CD8^- T lymphocytes (1.9% vs. 0.7%, p = 0.006), and, as a percent of T lymphocytes, increased CD8⁺T lymphocytes (38.6% vs. 25.7%; p = 0.0259) as compared with healthy thyroid samples. PD-1 inhibitor-induced thyroiditis had increased CD4⁺PD1⁺ T lymphocytes (40.4% vs. 0.8%; p = 0.021) and CD8⁺PD1⁺ T lymphocytes (28.8% vs. 1.5%; p = 0.038) in the thyroid compared with the blood. Circulating NK cells, certain T lymphocytes (CD4⁺CD8⁺, CD4^-CD8^- T, gamma-delta), and intermediate monocytes were increased in ICI-induced thyroiditis. Six patients typed as HLA-DR4-DR53 and three as HLA-DR15. Conclusions: ICI-induced thyroiditis is a T lymphocyte-mediated process with intra-thyroidal predominance of CD8⁺ and CD4^-CD8^- T lymphocytes. The HLA haplotypes may be involved but need further evaluation. These findings expand the limited understanding of ICI-induced thyroiditis, which could be further translated to guide immunomodulatory therapies for advanced thyroid cancer.

Elevated MicroRNA-326 Levels Regulate the IL-23/IL-23R/Th17 Cell Axis in Hashimoto's Thyroiditis by Targeting a Disintegrin and Metalloprotease 17

Background: MicroRNAs (miRNAs) are a class of critical epigenetic regulators involved in several autoimmune diseases. Our previous study reported an miR-326-induced increase in T helper (Th) 17 cells in a mouse model of Hashimoto's thyroiditis (HT), but the pathogenic effect of miR-326 in HT patients has not been verified. The goal of the present study was to explore the pathogenic role of miR-326 and its underlying molecular mechanism in HT patients. Methods: A total of 58 HT patients and 55 normal controls were enrolled in this study. We examined whether Th17 cells and miR-326 were aberrantly altered in the peripheral blood mononuclear cells (PBMCs) of HT patients with flow cytometry and real-time polymerase chain reaction. Levels of membrane interleukin (IL)-23R (mIL-23R) were determined by flow cytometry and Western blot to explore the critical role of mIL-23R in the development of Th17 cells. Isolated CD3⁺ T cells were used to further investigate the ectodomain shedding of mIL-23R by a disintegrin and metalloprotease (ADAM17). Furthermore, miR-326 inhibitor and mimics were transfected into PBMCs derived from HT patients and healthy controls to verify the regulation of ADAM17 by miR-326. Results: We observed elevated miR-326 levels in the PBMCs of HT patients compared with those in the PBMCs of healthy controls. Consistent with IL-23-induced STAT3 overactivation, substantially more HT patient-derived PBMCs differentiated into Th17 cells under polarization culture conditions, which may, at least in part, have resulted from enhanced mIL-23R levels. Furthermore, ADAM17, an ectodomain sheddase of mIL-23R, was targeted and negatively regulated by miR-326. Inhibiting ADAM17 might attenuate the ectodomain shedding of mIL-23R. Conclusions: Our findings suggest that the effect of miR-326 on the IL-23/IL-23R/Th17 cell axis in HT patients might be partially due to the targeting of ADAM17.

Anti-commensal IgG Drives Intestinal Inflammation and Type 17 Immunity in Ulcerative Colitis

Inflammatory bowel disease is a chronic, relapsing condition with two subtypes, Crohn's disease (CD) and ulcerative colitis (UC). Genome-wide association studies (GWASs) in UC implicate a FCGR2A variant that alters the binding affinity of the antibody receptor it encodes, FcγRIIA, for immunoglobulin G (IgG). Here, we aimed to understand the mechanisms whereby changes in FcγRIIA affinity would affect inflammation in an IgA-dominated organ. We found a profound induction of anti-commensal IgG and a concomitant increase in activating FcγR signaling in the colonic mucosa of UC patients. Commensal-IgG immune complexes engaged gut-resident FcγR-expressing macrophages, inducing NLRP3- and reactive-oxygen-species-dependent production of interleukin-1β (IL-1β) and neutrophil-recruiting chemokines. These responses were modulated by the FCGR2A genotype. In vivo manipulation of macrophage FcγR signal strength in a mouse model of UC determined the magnitude of intestinal inflammation and IL-1β-dependent type 17 immunity. The identification of an important contribution of IgG-FcγR-dependent inflammation to UC has therapeutic implications.

UC-1V150, a potent TLR7 agonist capable of activating macrophages and potentiating mAb-mediated target cell deletion

Toll-like receptors (TLR) are critical mediators of the immune system with their activation linked to infection, inflammation and the pathogenesis of immune diseases including autoimmunity and cancer. For this reason, over the last 2 decades, TLR and their associated signalling pathways have been targeted therapeutically to enhance innate and adaptive immunity. Several TLR ligands, both endogenous and synthetic are at various phases of clinical testing, and new ligands are continually emerging. Agonists of TLR7 are known immune response modifiers, simultaneously stimulating several cell types, resulting in immune cell activation and cytokine and chemokine release. The immune stimulating properties of the TLR7 agonist Imiquimod has also been exploited for use in the treatment of malignant superficial tumours of the skin. Here, we investigated a novel TLR7 agonist UC-1V150 and demonstrate it activates both human and mouse myeloid cells in vitro and in vivo, to deliver potent FcγR-mediated engulfment of opsonized target cells.

CD14+CD16+ monocytes in coronary artery disease and their relationship to serum TNF-α levels

Monocytes play a central role in the inflammatory disease atherosclerosis. CD14+CD16+ monocytes are considered proinflammatory monocytes, as they have an increased capacity to produce proinflammatory cytokines, such as TNF-α, and are elevated in various inflammatory diseases. We hypothesized that patients with coronary artery disease (CAD) have increased levels of CD14+CD16+ monocytes, and that CD14+CD16+ monocytes are associated with inflammation markers. We investigated CD14+CD16+ monocytes in 247 patients with CAD and 61 control subjects using flow cytometry. In addition serum concentrations of TNF-α, IL-6, and Hs-CRP were assessed. Patients with CAD had higher levels of CD14+CD16+ monocytes than controls (13.6% versus 11.4%; p<0.001). Logistic regression analysis including quartiles of CD14+CD16+ monocytes showed that CD14+CD16+ monocytes were associated with prevalence of CAD (OR 4.9, 95% CI 2.5–19.1, for subjects in the fourth quartile in comparison to subjects in the first quartile). The association between CD14+CD16+ monocytes and CAD remained independently significant after adjustment for most potential confounders (OR 5.0, 95% CI 1.2-20.0). Serum concentrations of TNF-α were elevated in subjects within the highest quartiles of CD14+CD16+ monocytes (p=0.018). Our study showed that increased numbers of CD14+CD16+ monocytes are associated with coronary atherosclerosis and TNF-α. In accordance, recent animal studies suggest a possibly important role of these monocytes in the development of atherosclerosis.

FCGR2C Polymorphisms Associated with HIV-1 Vaccine Protection Are Linked to Altered Gene Expression of Fc-γ Receptors in Human B Cells

The phase III Thai RV144 vaccine trial showed an estimated vaccine efficacy (VE) to prevent HIV-1 infection of 31.2%, which has motivated the search for immune correlates of vaccine protection. In a recent report, several single nucleotide polymorphisms (SNPs) in FCGR2C were identified to associate with the level of VE in the RV144 trial. To investigate the functional significance of these SNPs, we utilized a large scale B cell RNA sequencing database of 462 individuals from the 1000 Genomes Project to examine associations between FCGR2C SNPs and gene expression. We found that the FCGR2C SNPs that associated with vaccine efficacy in RV144 also strongly associated with the expression of FCGR2A/C and one of them also associated with the expression of Fc receptor-like A (FCRLA), another Fc-γ receptor (FcγR) gene that was not examined in the previous report. These results suggest that the expression of FcγR genes is influenced by these SNPs either directly or in linkage with other causal variants. More importantly, these results motivate further investigations into the potential for a causal association of expression and alternative splicing of FCGR2C and other FcγR genes with the HIV-1 vaccine protection in the RV144 trial and other similar studies.

Development and Characterization of Monoclonal Antibodies Specific for Mouse and Human Fcγ Receptors

FcγRs are key regulators of the immune response, capable of binding to the Fc portion of IgG Abs and manipulating the behavior of numerous cell types. Through a variety of receptors, isoforms, and cellular expression patterns, they are able to fine-tune and direct appropriate responses. Furthermore, they are key determinants of mAb immunotherapy, with mAb isotype and FcγR interaction governing therapeutic efficacy. Critical to understanding the biology of this complex family of receptors are reagents that are robust and highly specific for each receptor. In this study, we describe the development and characterization of mAb panels specific for both mouse and human FcγR for use in flow cytometry, immunofluorescence, and immunocytochemistry. We highlight key differences in expression between the two species and also patterns of expression that will likely impact on immunotherapeutic efficacy and translation of therapeutic agents from mouse to clinic.

Correlation of the expression of CD32 and CD180 receptors on CLL cells and MEC1 cell line

Chronic Lymphocytic Leukemia (CLL) presents with clonal expansion and accumulation of CD5+CD19+CD23+ cells in peripheral lymphoid organs and tissues and in bone marrow. CLL is supposedly driven by exogenous and/or endogenous (auto)antigen(s) and there is increasing evidence that CLL cells receive microenvironmental signals which support their growth, survival and expansion in vivo. We have previously shown that powerful signals are received by CLL cells through CD180 orphan toll-like receptor. Additional accessory signals could be generated through FcγRII (CD32), since both are expressed on CLL cells as well as on control B cells. Here we studied correlation of the expression of CD32 and CD180 on CLL cells as well as on MEC1 cell line. Peripheral blood mononuclear cells (PBMC) from CLL patients and age-matched healthy volunteers were separated, stained with appropriate antibodies to CD19, CD32 and CD180 and analysed by flow cytometry. CD32 and CD180 expression on MEC1 cells was studied at different time-points. The data was statistically analysed using the Mann-Whitney non-parametrical test. Our data indicates that expression of CD32 is significantly increased on CLL cells compared to control B cells as well as in long-term MEC1 cell culture. In contrast, CD180 expression on MEC1 cells significantly decreased throughout 0-96h of MEC1 cell culture. We have recently shown that CD180 ligation can redirect sIgM-mediated signaling from pro-survival to pro-apoptotic. This data indicates that a drop in the expression of CD180 on cycling CLL cells might lead to a weakening of this effect and enhance further survival and expansion of CLL cells in proliferative centres of lymphoid tissues. Since MEC1 cells are derived from a CLL patient with mutated IGVH genes (M-CLL) negative correlation between CD180 and CD32 expression on cycling MEC1 cells could be limited to M-CLL.

Role of the exogenous HCV core protein in the interaction of human hepatocyte proliferation and macrophage sub-populations

BACKGROUND

The core protein of hepatitis C virus (HCV) is found in the cytoplasm and nuclei of infected cells, including hepatocytes and other cells in the liver. The core protein could be secreted as well. Resident liver macrophages are dependent on the tissue micro-environment and external stimuli to differentiate M1 and M2 hypotypes with distinct functions, and increased expression of the nuclear transcription factor STAT3 was seen in M2-polarized macrophages. In contrast to proinflammatory M1 macrophages, M2 macrophages serve beneficial roles in chronic inflammation, immunosuppression, and tumorigenesis.

METHODS

Monocyte-derived human macrophage line (mTHP-1) was treated with the exogenous HCV core protein. Next, the mTHP-1 culture supernatant or cell pellets were added to culture media of normal human liver cell line (L02).

RESULTS

Only the culture supernatant stimulated L02 cells proliferation, which was associated with phosphorylated ERK expression. Core protein activated mTHP-1 cells showed enhanced pro- and anti-inflammatory cytokines secretion, which was accompanied by high expression of phosphorylated NF-κB105 and NF-κB65. However, phosphorylated STAT1, and STAT3, which are normally associated with M1 and M2 macrophage polarization, and cell surface expression of CD206, CD14, CD16, and CD86, were unaltered. A transwell co-culture system showed that only in mTHP-1 co-cultured with L02 in the presence of exogenous core protein, were higher levels of phosphorylated STAT3 and CD206 seen.

CONCLUSIONS

We showed L02 cells proliferation was accelerated by the culture supernatant of mTHP-1 cells treated with the exogenous HCV core protein. The exogenous core protein mediated the interaction between macrophages and hepatocytes in co-culture, which enhanced the expression of phosphorylated STAT3 and CD206 in macrophages.

Respiratory syncytial virus persistence in macrophages upregulates Fcgamma receptors expression

Viruses can persist in differentiated cells (i.e., macrophages) over long periods of time, altering host cells functions but not inducing their death. We had previously reported that, in early passages (14–40) of a murine macrophage-like cell line persistently infected with respiratory syncytial virus (RSV) (MɸP), FcγR-mediated phagocytosis and expression of FcγRIIB/RIII on the cell membrane were increased with respect to mock-infected macrophages (MɸN). In this work, we explored the mechanism underlying such effects. Increases in FcγR expression and FcγR-mediated phagocytosis are preserved after more than 87 passages of the persistently infected culture. We analyzed the expression of FcγR isoforms at both mRNA and protein levels, and found out that RSV persistence distinctly affects the expression of FcγR isoforms. We also observed that the increase in FcγRs expression results neither from soluble factors (cytokines) or viral products released by the infected cells, nor from an increase in the rate of FcγR internalization. Our results suggest that RSV persistence in macrophages induce intracellular effects that have an impact on FcγRs gene expression at both mRNA and protein levels, and that the characteristics of RSV persistence were preserved for over 87 passages.

Upregulation of CD11b on eosinophils in aspirin induced asthma

BACKGROUND

Although a challenge test using non-steroidal anti-inflammatory drugs (NSAIDs) is crucial for diagnosis of aspirin-induced asthma (AIA), it also has drawbacks in terms of possible side effects. Therefore, alternative in-vitro diagnostic methods for AIA are awaited.

METHODS

Nineteen stable non-AIA patients (9 males and 10 females; mean age, 49.4 ± 4.8 years), and 20 AIA patients (9 males and 11 females; mean age, 51.1 ± 4.8 years) were enrolled in this study. CD11b and CD16 expressions on the peripheral-blood granulocytes after administration of aspirin and different concentrations of PGE2 in vitro were examined using flowcytometry.

RESULTS

Aspirin induced a significant increase in CD11b expression on eosinophils (CD16 negative granulocytes) in 19 AIA patients and one non-AIA patient. Increase in CD11b expression on eosinophils by aspirin administration was suppressed by PGE2 in a dose-dependent manner.

CONCLUSIONS

The measurement of CD11b expression on peripheral-blood eosinophils showed very high sensitivity and specificity of (-95%) in diagnosing AIA. Although this method requires laboratory facilities for flowcytometry, it may be very useful in diagnosis of AIA without side effects. In addition, PGE2 may be involved in regulation of CD11b expression on eosinophils by aspirin administration.

Antibody-dependent cell lysis by NK cells is preserved after sarcoma-induced inhibition of NK cell cytotoxicity

Osteosarcoma and Ewing's sarcoma tumor cells are susceptible to IL15-induced or antibody-mediated cytolytic activity of NK cells in short-term cytotoxicity assays. When encountering the tumor environment in vivo, NK cells may be in contact with tumor cells for a prolonged time period. We explored whether a prolonged interaction with sarcoma cells can modulate the activation and cytotoxic activity of NK cells. The 40 h coculture of NK cells with sarcoma cells reversibly interfered with the IL15-induced expression of NKG2D, DNAM-1 and NKp30 and inhibited the cytolytic activity of NK cells. The inhibitory effects on receptor expression required physical contact between NK cells and sarcoma cells and were independent of TGF-β. Five days pre-incubation of NK cells with IL15 prevented the down-regulation of NKG2D and cytolytic activity in subsequent cocultures with sarcoma cells. NK cell FcγRIIIa/CD16 receptor expression and antibody-mediated cytotoxicity were not affected after the coculture. Inhibition of NK cell cytotoxicity was directly linked to the down-regulation of the respective NK cell-activating receptors. Our data demonstrate that the inhibitory effects of sarcoma cells on the cytolytic activity of NK cells do not affect the antibody-dependent cytotoxicity and can be prevented by pre-activation of NK cells with IL15. Thus, the combination of cytokine-activated NK cells and monoclonal antibody therapy may be required to improve tumor targeting and NK cell functionality in the tumor environment.

Lymphotoxin α1β2 expression on B cells is required for follicular dendritic cell activation during the germinal center response

CD19-deficient mice were used as a model to study follicular dendritic cell (FDC) activation because these mice have normal numbers of FDC-containing primary follicles, but lack the ability to activate FDCs or form GCs. It was hypothesized that CD19 expression is necessary for B-cell activation and upregulation of membrane lymphotoxin (mLT) expression, which promotes FDC activation. Using VCAM-1 and FcγRII/III as FDC activation markers, it was determined that the adoptive transfer of CD19(+) wild-type B cells into CD19-deficient hosts rescued GC formation and FDC activation, demonstrating that CD19 expression on B cells is required for FDC activation. In contrast, CD19(+) donor B cells lacking mLT were unable to induce VCAM-1 expression on FDCs, furthermore FcγRII/III upregulation was impaired in FDCs stimulated with mLT-deficient B cells. VCAM-1 expression on FDCs, but not FcγRII/III, was rescued when CD19-deficient B cells expressing transgenic mLT were cotransferred into recipient mice with CD19(+) , mLT-deficient B cells, suggesting that FDC activation requires the CD19-dependent upregulation of mLT on activated B cells. Collectively, these data demonstrate that activated B cells are responsible for the initiation of FDC activation resulting in a microenvironment supportive of GC development and maintenance.

Evaluation of CD64 expression on neutrophils as an early indicator of neonatal sepsis

BACKGROUND

Enhanced neutrophil CD64 (nCD64) expression is likely to be useful in diagnosis of neonatal sepsis. This study evaluated the diagnostic efficacy of nCD64 expression as an early indicator of neonatal sepsis.

METHODS

Sixty neonates (culture positive, 24; negative, 36) with suspected sepsis and 30 controls were studied prospectively. CD64 expression was evaluated flow cytometrically on neutrophils and monocytes. Mean and median nCD64 expression, mean and median monocyte CD64/nCD64 (M/N CD64) ratios were computed. Results were correlated with blood culture and other conventional indices of sepsis.

RESULTS

The sick neonates had significantly higher mean and median nCD64 expression compared with controls. Monocyte CD64 values did not differ significantly among the groups. Both mean and median M/N CD64 ratios were significantly lower in the former group. Culture-positive neonates had significantly higher mean and median nCD64 values and significantly lower mean and median M/N CD64 ratios than clinically indistinguishable but culture-negative neonates. Both groups were significantly different with respect to these indices from normal controls. Median M/N CD64 ratio was the best discriminant by virtue of highest area under the receiver operator characteristic curve (0.903), with sensitivity and specificity of 91.7% and 88.9%, respectively. Conventional indices were inferior, both singly and in combination.

CONCLUSIONS

Enhanced nCD64 reported as median M/N CD64 ratio is a highly sensitive marker of culture-positive neonatal sepsis. It additionally identifies a separate group among culture-negative sick neonates and may be useful to guide antibiotic administration especially in these neonates.

The unique cytoplasmic domain of human FcγRIIIA regulates receptor-mediated function

Ligand specificity characterizes receptors for Abs and many other immune receptors, but the common use of the FcR γ-chain as their signaling subunit challenges the concept that these receptors are functionally distinct. We hypothesized that elements for specificity might be determined by the unique cytoplasmic domain (CY) sequences of the ligand-binding α-chains of γ-chain-associated receptors. Among Fcγ receptors, a protein kinase C (PKC) phosphorylation consensus motif [RSSTR], identified within the FcγRIIIa (CD16A) CY by in silico analysis, is specifically phosphorylated by PKCs, unlike other FcRs. Phosphorylated CD16A mediates a more robust calcium flux, tyrosine phosphorylation of Syk, and proinflammatory cytokine production, whereas nonphosphorylatable CD16A is more effective at activation of the Gab2/PI3K pathway, leading to enhanced degranulation. S100A4, a specific protein-binding partner for CD16A-CY newly identified by yeast two-hybrid analysis, inhibits phosphorylation of CD16A-CY by PKC in vitro, and reduction of S100A4 levels in vivo enhances receptor phosphorylation upon cross-linking. Taken together, PKC-mediated phosphorylation of CD16A modulates distinct signaling pathways engaged by the receptor. Calcium-activated binding of S100A4 to CD16A, promoted by the initial calcium flux, attenuates the phosphorylation of CY, and, acting as a molecular switch, may both serve as a negative feedback on cytokine production pathways during sustained receptor engagement and favor a shift to degranulation, consistent with the importance of granule release following conjugate formation between CD16A(+) effector cells and target cells. This switch mechanism points to new therapeutic targets and provides a framework for understanding novel receptor polymorphisms.

Macrophage polarization induced by neuropeptide methionine enkephalin (MENK) promotes tumoricidal responses

The aim of this study is to investigate macrophages polarization induced by methionine enkephalin (MENK) that promotes tumoricidal responses in vivo and in vitro. Both phenotypic and functional activities of macrophages were assessed by the quantitative analysis of key surface molecules on macrophages with flow cytometry, immunofluorescent staining, and the production of cytokines with enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction. Our results showed that MENK could down-regulate the expression of CD206 and the production of arginase-1 (the markers of alternatively activated (M2) macrophage) in tumor-associated macrophages in vivo, meanwhile it could significantly up-regulate the expression of CD64, MHC-II, and the production of induced nitric oxide synthase (the markers of classically activated (M1) macrophages). Furthermore, the studies on bone marrow-derived macrophages treated with MENK (10(-12) M) in vitro had demonstrated that MENK could markedly increase tumoricidal activity. MENK could also enhance the release of reactive oxidant species and the production of interleukin-12p40, tumor necrosis factor-α, while decrease the production of interleukin-10. In conclusion, MENK could effectively induce M2 macrophages polarizing to M1 macrophages, sequentially to modulate the Th1 responses of the host immune system. Our results suggest that MENK might have great potential as a new therapeutic agent for cancer.

[Preparation and function of human soluble FcγRIIb]

AIM

To detect the concentration of soluble FcγRIIb in blood sera of SLE patients and healthy controls, then to obtain recombinant human soluble FcγRIIb protein (husFcγRIIb) in Escherichia coli (E.coli) and examine its binding capability with immune complexes (IC) and its effect on IgM secretion by B cells.

METHODS

The concentration of husFcγRIIb in blood sera of SLE patients and healthy controls was detected by ELISA. E.coli BL21, containing pET-sFcγRIIb, was stimulated by IPTG to induce husFcγRIIb expression, and then husFcγRIIb protein was purified by Ni-NTA agarose bead system. The IC-binding ability of husFcγRIIb was detected by ELISA. Furthermore, B cells were sorted by immune magnetic bead from human peripheral blood and challenged by different stimulators under the condition of husFcγRIIb or not for 10 d, then the concentration of IgM in supernatant was detected by ELISA.

RESULTS

The concentration of husFcγRIIb in the serum of SLE patients was lower than that in the controls (P<0.05). The recombinant husFcγRIIb protein was successfully expressed and purified with M(r); being 41 500. It could combine with IC and the absorption became higher with the increasing concentration of IC. After 10-day stimulation on the B cells, the titer of IgM between SPA and SPA+husFcγRIIb groups was not significantly different (P>0.05), and the titer was higher in SPA+anti-IgM group than SPA group (P<0.01). Interestingly, the titer of IgM in SPA+husFcγRIIb+anti-IgM group was lower than SPA+anti-IgM group (P<0.01), SPA group (P<0.01) and SPA+husFcγRIIb group (P<0.01).

CONCLUSION

The concentration of husFcγRIIb in the serum of SLE patients is lower than that in the healthy controls. The recombinant husFcγRIIb protein can combine with IC and inhibit IgM antibody secretion by B cells.

Dengue virus infection-enhancing activity in serum samples with neutralizing activity as determined by using FcγR-expressing cells

BACKGROUND

Progress in dengue vaccine development has been hampered by limited understanding of protective immunity against dengue virus infection. Conventional neutralizing antibody titration assays that use FcγR-negative cells do not consider possible infection-enhancement activity. We reasoned that as FcγR-expressing cells are the major target cells of dengue virus, neutralizing antibody titration assays using FcγR-expressing cells that determine the sum of neutralizing and infection-enhancing activity, may better reflect the biological properties of antibodies in vivo.

METHODS AND FINDINGS

We evaluated serum samples from 80 residents of a dengue endemic country, Malaysia, for neutralizing activity, and infection-enhancing activity at 1∶10 serum dilution by using FcγR-negative BHK cells and FcγR-expressing BHK cells. The serum samples consisted of a panel of patients with acute DENV infection (31%, 25/80) and a panel of donors without acute DENV infection (69%, 55/80). A high proportion of the tested serum samples (75%, 60/80) demonstrated DENV neutralizing activity (PRNT(50)≥10) and infection-enhancing activity. Eleven of 18 serum samples from patients with acute secondary DENV infection demonstrated neutralizing activity to the infecting serotype determined by using FcγR-negative BHK cells (PRNT(50)≥10), but not when determined by using FcγR-expressing cells.

CONCLUSION

Human serum samples with low neutralizing activity determined by using FcγR-negative cells showed DENV infection-enhancing activity using FcγR-expressing cells, whereas those with high neutralizing activity determined by using FcγR-negative cells demonstrate low or no infection-enhancing activity using FcγR-expressing cells. The results suggest an inverse relationship between neutralizing antibody titer and infection-enhancing activity, and that neutralizing activity determined by using FcγR-expressing cells, and not the activity determined by using FcγR-negative cells, may better reflect protection to DENV infection in vivo.

Detection and significance of blood neutrophil CD64 expression as a diagnostic marker in bacterial meningitis in children

Appropriate, rapid and reliable laboratory tests are essential for the diagnosis and therapy of acute bacterial meningitis especially in children. The purpose of this study was to evaluate the diagnostic value of flowcytometric detection of CD64 surface marker on blood neutrophils in diagnosis of acute bacterial meningitis. Our work included 132 (74 males and 58 females) patients with suspected meningitis, whose ages ranged from 2 months to 11 year. Patients were subjected to full clinical examination, complete blood count (CBC), cerebrospinal fluid (CSF) chemical and bacteriological analysis and detection of CD64 surface marker on blood neutrophils (CD64+ leucocytes). Based on the microbial culture results, patients were classified into bacterial meningitis group I (44) and non bacterial meningitis group II (88). The most prevalent isolates were Streptococcus pneumoniae (23) followed by H. influenzae (9) and N. meningitidis (6). Flowcytometry results indicated that the mean percentage of neutrophil CD64+ expression in bacterial meningitis (71.38 +/- 7.11) was significantly higher compared to culture negative meningitis (48.63 +/- 14.55) and controls (4.37 +/- 13.5). Flowcytometric assessment of neutrophil CD64 expression could serve as a reliable laboratory tool for detection of bacterial meningitis and may be a useful adjunct in differentiating bacterial and non bacterial meningitis.

[Pioglitazone, an activator of PPAR-gamma, reduces the expression of kB nuclear factor and inhibits apoptosis in mononuclear cells of peripheral blood in vitro]

In order to examine the impact of PPAR-gamma activator on the expression of kB nuclear transcription factor and apoptosis, the peripheral blood mononuclear cells (PBMC) were incubated with pioglitazone at concentrations 10, 30 and 100 MM. Expression of NF-kB in CD64+ cells was evaluated by flow cytometry using monoclonal antibodies. The development of apoptosis was evaluated using annexin V and propidium iodide. Activation of PPAR-y resulted in a reduction of the number of CD64+ cells and expression of the maximum levels of these receptors. We also obesrved a dose-dependent decrease of NF-kB concentration in PBMC suspension and in CD64+ cells. While analyzing the apoptosis, the reduction of apoptotic cells (reduction of AnV+PI+ cells) has been observed. The results obtained allow to prove that PPAR-gamma activation participates in the PBMC apoptosis regulation and in the expression of transcriptional factor NF-kB. Our results indicate for the involvement of PPAR-gamma in the regulation of NF-kB activity which plays one of the most significant roles in the inflammation realization, oncogenesis, and so on.

Immunophenotypic characterization of human monocyte subsets: possible implications for cardiovascular disease pathophysiology

OBJECTIVES

Monocytes include several subsets with different and sometimes divergent roles in immunity, atherogenesis and reparative processes.

OBJECTIVES

We aimed to perform detailed immunophenotypic and functional characterization of human monocyte subsets.

PATIENTS/METHODS

Analysis of surface markers of blood and bone marrow monocyte subsets and functional characterization of blood monocyte subsets in healthy volunteers was performed using flow cytometry.

RESULTS

In the present study, we show the presence of three subsets which could be unequivocally distinguished by surface expression of CD14, CD16 and CCR2 as CD14(+)CD16(-)CCR2(+) (Mon1), CD14(+)CD16(+)CCR2(+) (Mon2) and CD14(low)CD16(+)CCR2(-) (Mon3) subsets. In comparison with the classic Mon1, the Mon2 subset had the highest expression of Tie2, CXCR4, CD163, CD115, receptors to inter-cellular adhesion molecule-1 (ICAM-1), vascular endothelial growth factor (VEGF), and the highest surface levels of apolipoprotein B and ferritin. In contrast, Mon3 had maximal expression of VCAM-1 receptors and CD204. The Mon2 and Mon3 subsets had significantly lower activity of the NFκB pathway than Mon1. Mon1 and Mon2 had similar phagocytic activity, which was significantly higher compared with Mon3. All three subsets were present in bone marrow, although the relative proportion of Mon2 in bone marrow was about 2.5-fold higher compared with that seen in blood. Significant differences in cytokine production in response to endotoxin stimulation were observed between the three monocyte subsets.

CONCLUSION

Given their immunophenotypic similarity, the newly characterized Mon2 population may represent the previously reported pluripotent progenitor/pro-angiogenic monocytes.

CIN85 modulates the down-regulation of Fc gammaRIIa expression and function by c-Cbl in a PKC-dependent manner in human neutrophils

We previously described a non-classical mechanism that arrests FcγRIIa signaling in human neutrophils once engaged by immune complexes or opsonized pathogens. The engagement of FcγRIIa leads to its ubiquitination by the ubiquitin ligase c-Cbl and degradation by the proteasome. Herein, we further examined some of the events regulating this novel pathway. The adaptor protein CIN85 was described in other systems to be involved in the regulation of the c-Cbl-dependent pathway. We found that CIN85 is expressed in human neutrophils and that it translocates like c-Cbl from the cytosol to the plasma membrane following receptor cross-linking. CIN85 was also recruited to the same subset of high density detergent-resistant membrane fractions in which stimulated FcγRIIa partitioned with c-Cbl. The integrity of these microdomains is essential to the FcγRIIa degradation process because the cholesterol-depleting agent methyl-β-cyclodextrin inhibits this event. Silencing the expression of CIN85 by siRNA in dibutyryl cyclic AMP-differentiated PLB 985 cells prevented FcγRIIa degradation and increased IgG-mediated phagocytosis. Confocal microscopy revealed that the presence of CIN85 is essential to the proper sorting of FcγRIIa during endocytosis. We also provide direct evidence that CIN85 is a substrate of serine/threonine kinase PKCs. Classical PKCs positively regulate FcγRIIa ubiquitination and degradation because these events were inhibited by Gö6976, a classical PKC inhibitor. We conclude that the ubiquitination and degradation of stimulated FcγRIIa mediated by c-Cbl are positively regulated by the adaptor protein CIN85 in a PKC-dependent manner and that these events contribute to the termination of FcγRIIa signaling.

Fc-glycosylation influences Fcγ receptor binding and cell-mediated anti-HIV activity of monoclonal antibody 2G12

Interactions between the Fc segment of IgG and FcγRs on a variety of cells are likely to play an important role in the anti-HIV activity of Abs. Because the nature of the glycan structure on the Fc domain is a critical determinant of Fc-FcγR binding, proper Fc glycosylation may contribute to Ab-mediated protection. We have generated five different glycoforms of the broadly HIV-1-neutralizing mAb 2G12 in wild-type and glycoengineered plants and Chinese hamster ovary cells. Plant-derived 2G12 exhibited highly homogeneous glycosylation profiles with a single dominant N-glycan species. Using flow cytometry with FcγR-expressing cell lines, all 2G12 glycoforms demonstrated similar binding to FcγRI, FcγRIIa, and FcγRIIb. In contrast, two glycoforms derived from glycoengineered plants that lack plant-specific xylose and core α1,3-fucose, and instead carry human-like glycosylation with great uniformity, showed significantly enhanced binding to FcγRIIIa compared with Chinese hamster ovary or wild-type plant-derived 2G12. Using surface plasmon resonance, we show that binding of 2G12 to FcγRIIIa is markedly affected by core fucose, irrespective of its plant-specific α1,3 or mammalian-type α1,6 linkage. Consistent with this finding, 2G12 glycoforms lacking core fucose (and xylose) mediated higher antiviral activity against HIV-1 or simian immunodeficiency virus as measured by Ab-dependent cell-mediated virus inhibition. This is, to our knowledge, the first demonstration that specific alterations of Fc glycosylation can improve antiviral activity. Such alterations may result in better immunotherapeutic reagents. Moreover, biasing vaccine-induced immune responses toward optimal Fc glycosylation patterns could result in improved vaccine efficacy.

[Clinical value of CD64 expression in adults with measles complicating bacterial pneumonia]

OBJECTIVE

To study the clinical value of expression of peripheral blood neutrophil CD64 in adults with measles complicating pneumonia.

METHODS

106 patients were divided into two groups by clinical manifestation and bacteria study: measles complicating bacterial pneumonia group and measles complicating viral pneumonia, using flow cytometry determination of CD64, C-reactive protein (CRP) and white blood cell (WBC) count.

RESULTS

The expression of CD64 in the bacterial pneumonia group with eruptive stage was (32.15 +/- 11.07) MFI, which was significantly higher than that in the group of with recovery stage (10.6 +/- 3.23) MFI (P < 0.01) and viral pneumonia (9.55 +/- 3.48) MFI (P < 0.01). These markers were considered positive if CD64 > or = 8.5 MFI, CRP > or = 10 mg/L and WBC > or = 9.05 x 10(9)/L. Their sensitivity was 78.12%, 80.48% and 59.37%. Their specificity was 76.19% ,67.67% and 64.28%. Their accuracy rate was 77.35%, 74.52%, 61.32%; CD64 has a positive relationship with CRP.

CONCLUSION

Compared to CRP, expression of peripheral blood neutrophil CD64 can be a better marker in the early diagnosis of patients with measles complicating bacterial pneumonia and as one of the indicators of disease conditions.

Hexabromocyclododecane decreases tumor-cell-binding capacity and cell-surface protein expression of human natural killer cells

Hexabromocyclododecane (HBCD) is a flame retardant that decreases the lytic function of human natural killer (NK) cells. NK cells defend against tumor cells and virally infected cells. Thus, HBCD has the potential to increase cancer incidence and viral infections. NK cells must bind to their targets for lysis to occur. Thus, concentrations of HBCD that decrease lytic function were examined for their ability to alter NK binding to tumor targets. Levels of HBCD that caused a loss of binding function were examined for effects on expression of cell surface proteins needed for binding. NK cells exposed to HBCD for 24 h, 48 h or 6 days or to HBCD for 1 h followed by 24 h, 48 h or 6 days in HBCD-free media were examined for binding function and cell surface protein expression. The results indicated that exposure of NK cells to 10 microM HBCD for 24 h (which caused a greater than 90% loss of lytic function) caused a very significant decrease in NK cell binding function (70.9%), and in CD16 and CD56 cell-surface protein expression (57.8 and 24.6% respectively). NK cells exposed to 10 microM HBCD for 1 h followed by 24 h in HBCD-free media (which caused a 89.3% loss of lytic function) showed decreased binding function (79.2%), and CD 16 expression (48.1%). Results indicate that HBCD exposures decreased binding function as well as cell-surface marker expression in NK cells and that these changes may explain the losses of lytic function induced by certain HBCD exposures.

Strategies to rescue mesenchymal stem cells (MSCs) and dental pulp stem cells (DPSCs) from NK cell mediated cytotoxicity

BACKGROUND

The aim of this paper is to study the function of allogeneic and autologous NK cells against Dental Pulp Stem Cells (DPSCs) and Mesenchymal Stem Cells (MSCs) and to determine the function of NK cells in a three way interaction with monocytes and stem cells.

METHODOLOGY/PRINCIPAL FINDINGS

We demonstrate here that freshly isolated untreated or IL-2 treated NK cells are potent inducers of cell death in DPSCs and MSCs, and that anti-CD16 antibody which induces functional split anergy and apoptosis in NK cells inhibits NK cell mediated lysis of DPSCs and MSCs. Monocytes co-cultured with either DPSCs or MSCs decrease lysis of stem cells by untreated or IL-2 treated NK cells. Monocytes also prevent NK cell apoptosis thereby raising the overall survival and function of NK cells, DPSCs or MSCs. Both total population of monocytes and those depleted of CD16(+) subsets were able to prevent NK cell mediated lysis of MSCs and DPSCs, and to trigger an increased secretion of IFN-gamma by IL-2 treated NK cells. Protection of stem cells from NK cell mediated lysis was also seen when monocytes were sorted out from stem cells before they were added to NK cells. However, this effect was not specific to monocytes since the addition of T and B cells to stem cells also protected stem cells from NK cell mediated lysis. NK cells were found to lyse monocytes, as well as T and B cells.

CONCLUSION/SIGNIFICANCE

By increasing the release of IFN-gamma and decreasing the cytotoxic function of NK cells monocytes are able to shield stem cells from killing by the NK cells, resulting in an increased protection and differentiation of stem cells. More importantly studies reported in this paper indicate that anti-CD16 antibody can be used to prevent NK cell induced rejection of stem cells.

Bispecific anti-HER2 and CD16 single-chain antibody production prolongs the use of stem cell-like cell transplantation against HER2-overexpressing cancer

Humanized antibodies vary and have certain effects, but they are expensive and require repeated administration. We developed cells which constantly express a humanized antibody, and we performed anticancer humanized antibody therapy involving cell transplantation. Genes with the same amino acid sequence as that of the variable region of trastuzumab (Herceptin) as the humanized anti-HER2 monoclonal antibody were produced by overlap-PCR and were connected to the anti-human CD16 antibody [anti-HER2+anti-CD16 single-chain antibody (anti-HER2+CD16 scAb)]. For transplantation, stem cell-like cells that are immunologically tolerant and do not transform into cancer [mouse embryo fibroblast cell line C3H10T1/2 (10T1/2)] were used. The antibody was incorporated into 10T1/2 (antibody-expressing cells) using the pMX-IRES-EGFP retroviral vector. Cell supernatants and human monocytes were exposed to the human breast cancer strain HTB131 expressing HER2, and the in vitro antibody-dependent cell-mediated cytotoxicity (ADCC) effects were evaluated. After the transplantation of antibody-expressing and HTB131 cells into SCID mice, human monocytes were intermittently administered, and the in vivo ADCC effects were evaluated. We found that the ex vivo dead cell rate was 15.4% for Herceptin, 5.6% for anti-HER2+CD16 scAb, 1.5% for anti-CD16 scAb, and 2.1% for the control, demonstrating the antitumor effects of anti-HER2+CD16 scAb. In an antibody-expressing cell transplantation model, the inhibitory effects of this antibody on HTB131 cell establishment were observed. In conclusion, the establishment of breast cancer cells in the peritoneum was inhibited by the transplantation of antibody-expressing cells. Since this method requires cell transplantation only once, the drug cost may be reduced.

[Immune response in patients with HCV infection on the south of western Siberia]

The aim of the study was to investigate the features of immune response in patients with HCV infection on the South of Western Siberia.

MATERIALS

The 130 patients with different genotips of HCV infection were investigated (95 men and 35 women).

RESULTS

On the territory of the South of Western Siberia the 1 and 3 genotips of HCV infection were present especially in young men and women and 1b subtype was dominated. In patients with 1 and 3 genotips of HCV infection was occurred the massive inflammatory response with intensive necrotic proinflammatory cytokins damages of the liver tissue and high cirrotic occurring in young age.

Brucella melitensis, B. neotomae and B. ovis elicit common and distinctive macrophage defense transcriptional responses

Brucella spp. establish an intracellular replicative niche in macrophages, while macrophages attempt to eliminate the bacteria by innate defense mechanisms. Brucella spp. possess similar genomes yet exhibit different macrophage infections. Few B. melitensis and B. neotomae enter macrophages with intracellular adaptation occurring over 4-8 hr. Conversely, B. ovis are readily ingested by macrophages and exhibit a persistent plateau of infection. Evaluating early macrophage interaction with Brucella spp. allows discovery of host entry and intracellular translocation mechanisms. Microarray analysis of macrophage transcriptional response following a 4 hr infection by different Brucella spp. revealed common macrophage genes altered in expression compared to uninfected macrophages. Macrophage infection with three different Brucella spp. provokes a common innate immune theme with increased transcript levels of chemokines and defense response genes and decreased transcript levels of GTPase signaling and cytoskeletal function that may affect trafficking of Brucella containing vesicles. For example, transcript levels of genes associated with chemotaxis (IL-1beta, MIP-1alpha), cytokine regulation (Socs3) and defense (Fas, Tnf) were increased, while transcript levels of genes associated with vesicular trafficking (Rab3d) and lysosomal associated enzymes (prosaposin) were decreased. Genes with altered macrophage transcript levels among Brucella spp. infections may correlate with species specific host defenses and intracellular survival strategies. Depending on the infecting Brucella species, gene ontology categorization identified genes differentially involved in cell growth and maintenance, endopeptidase inhibitor activity and G-protein mediated signaling. Examples of decreased gene expression in B. melitensis infection but not other Brucella spp. were growth arrest (Gas2), immunoglobulin receptor (FcgammarI) and chemokine receptor (Cxcr4) genes, suggesting opposing effects on intracellular functions.

Oxidant alterations in CD16 expression are cytoskeletal induced

Oxidative stress during reperfusion of ischemia is associated with a phenotypic change in circulating monocytes from CD14++CD16- to a proinflammatory CD14+CD16+ subpopulation resulting in altered immunity and development of organ failure. However, the mechanism responsible remains unknown. We hypothesize that this phenotypic change, modeled by hydrogen peroxide exposure in vitro, is due to oxidative-induced intracellular calcium flux and distinct cytoskeletal and lipid raft changes. Peripheral blood monocytes obtained from healthy volunteers underwent 100 mM H2O2 exposure for 0 to 24 h. Selected cells were pretreated with 2 microM cytochalasin D, 1 microM lactrunculin A, or 30 microM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid for 30 min. Cells underwent fluorescence-activated cell sorter for CD14, CD16, and cytokine expression. Cellular and lipid raft CD16 expression was determined by immunoblot and confocal microscopy. H2O2 exposed monocytes underwent a rapid time-dependent increase in the surface expression of CD16 from 12.81% +/- 3.53% to 37.12% +/- 7.61% at 24 h (P = 0.001). Total cellular CD16 was not changed by H2O2, but an increase in lipid raft and decrease in intracellular CD16 expression were seen after H2O2 exposure. This increase in CD16 expression was associated with a 27% increase in intracellular TNF-alpha, an alteration in actin polymerization, and the formation of raft macrodomains. These changes induced by H2O2 were inhibited by inhibition of actin polymerization (cytochalasin D and lactrunculin A) and intracellular calcium flux [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid]. This study provides the first evidence that phenotypic alterations induced by oxidative stress during reperfusion may occur as a result of changes in cytoskeletal architecture due to calcium flux that result in lipid raft alterations rather than solely from demargination and/or production of bone marrow-derived CD16+ monocytes.

HIV-1 residual viremia correlates with persistent T-cell activation in poor immunological responders to combination antiretroviral therapy

BACKGROUND

The clinical significance and cellular sources of residual human immunodeficiency virus type 1 (HIV-1) production despite suppressive combination antiretroviral therapy (cART) remain unclear and the effect of low-level viremia on T-cell homeostasis is still debated.

METHODOLOGY/PRINCIPAL FINDINGS

We characterized the recently produced residual viruses in the plasma and short-lived blood monocytes of 23 patients with various immunological responses to sustained suppressive cART. We quantified the residual HIV-1 in the plasma below 50 copies/ml, and in the CD14(high) CD16(-) and CD16+ monocyte subsets sorted by flow cytometry, and predicted coreceptor usage by genotyping V3 env sequences. We detected residual viremia in the plasma of 8 of 10 patients with poor CD4+ T-cell reconstitution in response to cART and in only 5 of 13 patients with good CD4+ T-cell reconstitution. CXCR4-using viruses were frequent among the recently produced viruses in the plasma and in the main CD14(high) CD16(-) monocyte subset. Finally, the residual viremia was correlated with persistent CD4+ and CD8+ T-cell activation in patients with poor immune reconstitution.

CONCLUSIONS

Low-level viremia could result from the release of archived viruses from cellular reservoirs and/or from ongoing virus replication in some patients. The compartmentalization of the viruses between the plasma and the blood monocytes suggests at least two origins of residual virus production during effective cART. CXCR4-using viruses might be produced preferentially in patients on cART. Our results also suggest that low-level HIV-1 production in some patients may contribute to persistent immune dysfunction despite cART.

Neutrophil CD64 (FcγRI) expression is a specific marker of bacterial infection: A study on the kinetics and the impact of major surgery

Neutrophil CD64 expression is a diagnostic marker for the early detection of bacterial infections. The aim was to investigate the kinetics of neutrophil CD64 expression during bacterial infection and the possible impact of surgical trauma. Blood samples were collected daily during 3 d after admission for analysis by flow cytometry of the surface expressions on neutrophils and monocytes of CD64, CD16, CD32, CD11b/CD18 and CD35, and analysis of serum CRP and blood WBC. Serum concentrations of IFNgamma, G-CSF, IL-6 and IL-8 were also analysed in adults. Eight children and 19 adult patients with bacterial infections, 12 patients admitted for hip-arthroplasty because of coxarthrosis and 30 healthy adults were studied. Neutrophil CD64 was increased all 3 d after start of treatment (p<0.0001) in children and adults with bacterial infections. The postoperative increase after surgery was less than the increase seen during bacterial infections (p<0.0001). CRP, G-CSF, IL-6 and IL-8 were raised both in bacterial infections and after surgery. Our results indicate that the expression of CD64 on neutrophils is a specific sign of bacterial infections. Neutrophil expression of CD64, therefore, seems to be a promising tool for the early detection of bacterial infections even during surgery.

Increased number of CD16(+)CD56(dim) NK cells in peripheral blood mononuclear cells after allogeneic cord blood transplantation

In the present study, we investigated subpopulations of natural killer (NK) cells and the expression of stimulatory and inhibitory NK receptors after adult blood and bone marrow transplantation (BBMT) and cord blood transplantation (CBT). There were significant increases in CD16(+)CD56(dim) cell proportion and in absolute number in peripheral blood mononuclear cells (PBMC) during a period of 4-9 months after CBT compared with these in normal PBMC, cord blood (CB), and in PBMC after BBMT. Also, increased numbers of CD16(+)CD56(dim) NK cells were sustained in some patients until 4 years after CBT. This CD16(+)CD56(dim) cell subset after CBT exhibited decreased expression of NKG2A compared with that in CB and increased expression of NKG2C. Purified CD16(+)CD56(dim) cells from patients 8-9 months after CBT exhibited significantly higher levels of cytolytic activity against K562 than did purified CD16(+)CD56(bright) cells and also whole PBMC. The CD16(+)CD56(dim) cell subset with a high level of cytolytic activity significantly increased after CBT, and these cells may be responsible for NK cell-mediated immunity after CBT.

C-reactive protein stimulates superoxide anion release and tissue factor activity in vivo

C-reactive protein (CRP), the prototypic marker of inflammation, is a cardiovascular risk marker and recent in vitro studies suggest that it may promote atherogenesis. CRP promotes oxidative stress in vitro and induces tissue factor (TF) release. However, there is a paucity of data examining the effects of CRP on oxidative stress and tissue factor procoagulant activity (PCA) in vivo. Thus, we tested the effects of CRP administration on superoxide anion release and tissue factor activity and examined mechanistic pathways using a rat sterile air pouch model. Intraperitoneal administration of CRP (20mg/kg body weight) compared to human serum albumin (HuSA) increased superoxide anion release and tissue factor activity from peritoneal macrophages in vivo (p<0.01). This was confirmed using intrapouch administration of CRP (25mug/mL) compared to HuSA. Pretreatment with reactive oxygen species (ROS) scavengers or protein kinase C (PKC) inhibitor significantly abrogated CRP-induced superoxide anion release and tissue factor activity. Pretreatment with extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) inhibitors, but not p38 mitogen-activated protein kinase (p38MAPK) significantly decreased CRP-induced superoxide anion release from macrophages in vivo. CRP-induced tissue factor activity in vivo was abrogated by pretreatment with inhibitors to p38MAPK, JNK and NFkappab (nuclear factor-kappab), but not ERK. Antibodies to Fc gamma receptors, CD32 and CD64 resulted in significant reduction in CRP-induced superoxide and tissue factor activity in vivo. Thus, CRP appears to induce oxidative stress in vivo by stimulating NADPH oxidase via PKC, ERK and JNK phosphorylation, and induces tissue factor PCA in vivo via upregulation of PKC, p38MAPK, JNK, ROS and NFkappab. CRP-induced ROS appears to precede tissue factor release. These effects are abrogated by blocking Fc gamma receptors, CD32 and CD64. This in vivo demonstration provides further evidence for a role for CRP in atherothrombosis.

Cooperative regulation of Fc receptor gamma-chain gene expression by multiple transcription factors, including Sp1, GABP, and Elf-1

The Fc receptor gamma-chain (FcRgamma), which was first identified as a constituent of the high affinity IgE receptor, associates with various cell surface receptors to mediate intracellular signals. We identified three transcriptional enhancer elements in the 5' region of the human FcRgamma gene; one of the cis-elements was recognized by the transcription factor Sp-1 and another was recognized by GABP or Elf-1. The sequence of the other element was similar to a binding motif of the C/EBP family. Overexpression experiments showed that these transcription factors cooperatively activated the FcRgamma promoter. Furthermore, inactivation of the GABP-binding site by nucleotide substitutions as well as repression of GABPalpha expression by RNA interference reduced Sp1-mediated transactivation of the FcRgamma promoter, demonstrating that Sp1 and GABP synergistically activated the FcRgamma promoter. This synergistic activation was suggested to require physical interaction between the two transcription factors, because the Ets domain of GABPalpha was demonstrated to directly bind Sp1. On the other hand, GABP and Elf-1, whose recognition sequences overlapped, were shown to bind the FcRgamma gene with similar affinity in the context of chromatin, although Elf-1 exerted weaker enhancer activity for FcRgamma gene expression than did GABP. Both were thought to compete for binding to the element, because additional expression of Elf-1 in combination with Sp1 and GABP reduced FcRgamma promoter activity. Such functional and physical interactions among transcription factors involved in the cooperative regulation of FcRgamma gene expression as revealed in this study will become promising targets for medical applications against various immune diseases involving FcRgamma.

High synovial expression of the inhibitory FcgammaRIIb in rheumatoid arthritis

Activating Fc gamma receptors (FcγRs) have been identified as having important roles in the inflammatory joint reaction in rheumatoid arthritis (RA) and murine models of arthritis. However, the role of the inhibitory FcγRIIb in the regulation of the synovial inflammation in RA is less known. Here we have investigated synovial tissue from RA patients using a novel monoclonal antibody (GB3) specific for the FcγRIIb isoform. FcγRIIb was abundantly expressed in synovia of RA patients, in sharp contrast to the absence or weak staining of FcγRIIb in synovial biopsies from healthy volunteers. In addition, the expression of FcγRI, FcγRII and FcγRIII was analyzed in synovia obtained from early and late stages of RA. Compared with healthy synovia, which expressed FcγRII, FcγRIII but not FcγRI, all activating FcγRs were expressed and significantly up-regulated in RA, regardless of disease duration. Macrophages were one of the major cell types in the RA synovium expressing FcγRIIb and the activating FcγRs. Anti-inflammatory treatment with glucocorticoids reduced FcγR expression in arthritic joints, particularly that of FcγRI. This study demonstrates for the first time that RA patients do not fail to up-regulate FcγRIIb upon synovial inflammation, but suggests that the balance between expression of the inhibitory FcγRIIb and activating FcγRs may be in favour of the latter throughout the disease course. Anti-inflammatory drugs that target activating FcγRs may represent valuable therapeutics in this disease.

[The changes of expression and Fc-gamma-receptor's polypeptide composition of fetal small intestine enterocytes in Bos primigenius taurus L]

The expression and polypeptide composition of Fc-gamma-receptors of enterocytes from Bos primigenius taurus L. intestine at 3-, 5-, 7-, 9- month of fetal development was investigated. The results of immunobloting show similar composition of Fc-gamma-receptors extracted from apical and basolateral membranes. The proteins that bind IgG after PAAG electrophoresis and transferring on nitrocellulose were observed as 120, 87, 72 and 43 kDa polypeptide line. The changes of each polypeptide contents were related to the changes of total content of Fc-gamma-receptor proteins. The rise in concentration of Fc-gamma-receptors on apical membrane was observed from 3-rd to 7-th month of fetal development. Maximal concentration of these proteins was detected on enterocytes at 7-th month of fetal development. Fc-gamma-receptors content on basolateral side was higher than on apical side. The presence of Fc-gamma-receptors on enterocyte's membrane indicates on active recycling of these receptors on plasma membrane and reflects early development of immune system in Bos primigenius taurus L. fetus.

CD16+ monocytes produce IL-6, CCL2, and matrix metalloproteinase-9 upon interaction with CX3CL1-expressing endothelial cells

The CD16+ subset of peripheral blood monocytes (Mo) is expanded dramatically during inflammatory conditions including sepsis, HIV-1 infection, and cancer. CD16+ express high levels of CX3CR1, which mediates arrest onto CX3CL1-expressing endothelial cells (EC) under flow conditions. In contrast, attachment of CD16- Mo onto cytokine-activated EC is independent of CX3CL1. Here, we investigate the ability of CD16+ and CD16- Mo to produce proinflammatory cytokines upon interaction with CX3CL1-expressing HUVEC. We demonstrate that CD16+ but not CD16- Mo produce high levels of IL-6, CCL2, and matrix metalloproteinase (MMP)-9 when cocultured with TNF/IFN-gamma-activated HUVEC or nonactivated HUVEC expressing CX3CL1. Furthermore, supernatants from Mo cocultured with cytokine-activated HUVEC induce neuronal death in vitro. These results suggest that membrane-bound CX3CL1 stimulates production of IL-6, CCL2, and MMP-9 by CD16+ Mo, likely via engagement of CX3CR1. Thus, expansion of CD16+ Mo and their accumulation onto CX3CL1-expressing EC may result in recruitment of Mo and T cell subsets at sites of inflammation in response to CCL2, IL-6-induced cell activation and/or differentiation, and MMP-9-mediated vascular and tissue injury.

Phenotypic studies of natural killer cell subsets in human transporter associated with antigen processing deficiency

Peripheral blood natural killer (NK) cells from patients with transporter associated with antigen processing (TAP) deficiency are hyporesponsive. The mechanism of this defect is unknown, but the phenotype of TAP-deficient NK cells is almost normal. However, we noticed a high percentage of CD56^bright cells among total NK cells from two patients. We further investigated TAP-deficient NK cells in these patients and compared them to NK cells from two other TAP-deficient patients with no clinical symptoms and to individuals with chronic inflammatory diseases other than TAP deficiency (chronic lung diseases or vasculitis). Peripheral blood mononuclear cells isolated from venous blood were stained with fluorochrome-conjugated antibodies and the phenotype of NK cells was analyzed by flow cytometry. In addition, ⁵¹Chromium release assays were performed to assess the cytotoxic activity of NK cells. In the symptomatic patients, CD56^bright NK cells represented 28% and 45%, respectively, of all NK cells (higher than in healthy donors). The patients also displayed a higher percentage of CD56^dimCD16⁻ NK cells than controls. Interestingly, this unusual NK cell subtype distribution was not found in the two asymptomatic TAP-deficient cases, but was instead present in several of the other patients. Over-expression of the inhibitory receptor CD94/NKG2A by TAP-deficient NK cells was confirmed and extended to the inhibitory receptor ILT2 (CD85j). These inhibitory receptors were not involved in regulating the cytotoxicity of TAP-deficient NK cells. We conclude that expansion of the CD56^bright NK cell subtype in peripheral blood is not a hallmark of TAP deficiency, but can be found in other diseases as well. This might reflect a reaction of the immune system to pathologic conditions. It could be interesting to investigate the relative distribution of NK cell subsets in various respiratory and autoimmune diseases.

Quantification and modeling of tripartite CD2-, CD58FC chimera (alefacept)-, and CD16-mediated cell adhesion

Alefacept is a chimeric protein combining CD58 immunoglobulin-like domain 1 with human IgG1 Fc. Alefacept mediates adhesion by bridging CD2 on T cells to activating Fc receptors on effector cells, but the equilibrium binding parameters have not been determined. Alefacept mediated T cell killing by NK cells and adhesion between CD2- and CD16-expressing cells at an optimum concentration of 100 nM. We introduce novel measurements with supported planer bilayers, from which key two-dimensional and three-dimensional parameters can be determined by data fitting. Alefacept competitively inhibited cell bilayer adhesion mediated by the CD2-CD58 interaction. Alefacept mediated maximal adhesion of CD2(+) T cells to CD16B, an Fc receptor, in planar bilayers at 500 nM. A mechanistic model for alefacept-mediated cell-bilayer adhesion allowed fitting of the data and determination of two-dimensional binding parameters. These included the density of bonds in the adhesion area, which grew to maintain a consistent average bond density of 200 molecules/microm(2) and two-dimensional association constants of 3.1 and 630 microm(2) for bivalently and monovalently bound forms of alefacept, respectively. The maximum number of CD16 bound and the fit value of 4,350 CD2 per cell are much lower than the 40,000 CD2 per cell measured with anti-CD2 Fab. These results suggest that additional information is needed to correctly predict Alefacept-mediated bridge formation.

Functional role of phosphatidylcholine-specific phospholipase C in regulating CD16 membrane expression in natural killer cells

CD16, the low-affinity FcIgG receptor (FcgammaRIIIA), is predominantly expressed in human NK cells. Our recent findings indicate that CD16 expression on the outer membrane surface of NK cells is correlated with the membrane expression of phosphatidylcholine-specific phospholipase C (PC-PLC). In the present study we analyzed the trafficking of CD16 from the plasma membrane to cytoplasmic regions, after stimulation with specific mAb. The CD16 receptor is internalized, likely degraded and newly synthesized; its endocytosis is independent of ATP, but requires an integral and functional actin cytoskeleton. Antibody-mediated CD16 cross-linking results in an approximately twofold increase in PC-PLC enzymatic activity within 10 min. Analysis of PC-PLC and CD16 distribution in NK cell plasma membrane demonstrates that the proteins are physically associated and partially accumulated in lipid rafts. Pre-incubation of NK cells with a PC-PLC inhibitor, D609, causes a dramatic decrease both in CD16 receptor and PC-PLC enzyme expression on the plasma membrane. Interestingly, among phenotype PBL markers, only CD16 is strongly down-modulated by D609 treatment. CD16-mediated cytotoxicity is also reduced after D609 incubation. Taken together, these data suggest that the PC-PLC enzyme could play an important role in regulating CD16 membrane expression, the CD16-mediated cytolytic mechanism and CD16-triggered signal transduction.

Simultaneous quantitative analysis of FcgammaRI (CD64) expression on neutrophils and monocytes: a new, improved way to detect infections

We performed simultaneous quantitative flow cytometric analysis of neutrophil and monocyte FcgammaRI (CD64) in 289 hospitalized febrile patients. Microbiological evaluation or clinical diagnosis confirmed bacterial (n=89) or viral (n=46) infection in 135 patients. Patient data were compared with data from 60 healthy controls. The average number of FcgammaRI on the surfaces of both neutrophils and monocytes was significantly increased in patients with febrile viral and bacterial infections, compared to healthy controls. Furthermore, we describe a novel marker of febrile infection, designated 'CD64 score point', which incorporates the quantitative analysis of FcgammaRI expressed on both neutrophils and monocytes, with 94% sensitivity and 98% specificity in distinguishing between febrile infections and healthy controls. By contrast, analysis of FcgammaRI expression on neutrophils and monocytes displayed poor sensitivity (73% and 52%) and specificity (65% and 52%) in distinguishing between bacterial and viral infections, and the levels did not differ significantly between systemic (sepsis), local, and clinically diagnosed bacterial infections. In summary, our results clearly show that the increased number of FcgammaRI on neutrophils and monocytes is a useful marker of febrile infection, but cannot be applied for differential diagnosis between bacterial and viral infections or between systemic and local bacterial infections.

Hyperexpression of FcgammaRI and Toll-like receptor 4 in the intestinal mast cells of Crohn's disease patients

We previously reported that human mast cells (MCs) express high affinity IgG receptor (FcgammaRI) and Toll-like receptor 4 (TLR4) in response to interferon (IFN)-gamma in vitro. The number of MCs is known to increase in Crohn's disease (CD) and ulcerative colitis (UC). We aimed to examine the expression and function of the receptors in these diseases by immunohistochemistry of the colonic mucosae and by in vitro experiments. The density of MCs expressing FcgammaRI, TLR4, or both proteins was significantly higher in CD than in UC or control samples. The density of TNF-alpha(+) MCs expressing FcgammaRI or TLR4 was significantly higher in CD than in control samples. LPS and IgG1 cross-linking synergistically induced a high level of TNF-alpha production in IFN-gamma-treated human MCs. Hyperexpression of FcgammaRI and TLR4 on MCs was related to the high frequency of TNF-alpha expression in CD, suggesting the activation of MCs via these receptors in vivo.

Macrophage colony-stimulating factor enhances rituximab-dependent cellular cytotoxicity by monocytes

Recent studies suggest that monocytes are the dominant effectors by which rituximab induces cell death in B-cell lymphoma. Because macrophage colony-stimulating factor (M-CSF) can enhance the cytotoxicity of monocytes, the authors examined whether this growth factor can enhance their ability to kill lymphoma cells in vitro. Monocytes derived from a healthy volunteer were cultured for 48 h in the presence or absence of M-CSF. Monocytes stimul ated with M-CSF were significantly more cytotoxic to Daudi B-cell lymphomas than unstimulated monocytes. Flow cytometry revealed that M-CSF increased monocyte expression of Fcgamma receptors III and I by 1.6- and 1.5-fold, whereas the expression of Fcgamma receptor II remained unchanged. These results suggest that pretreatment with M-CSF can improve the therapeutic efficacy of rituximab against intractable CD20(+) lymphoma.

Immune Complexes Inhibit Differentiation, Maturation, and Function of Human Monocyte-Derived Dendritic Cells

The interaction between immune complexes (IC) and the receptors for the Fc portion of IgG (FcgammaRs) triggers regulatory and effector functions in the immune system. In this study, we investigated the effects of IC on differentiation, maturation, and functions of human monocyte-derived dendritic cells (DC). When IC were added on day 0, DC generated on day 6 (IC-DC) showed lower levels of CD1a and increased expression of CD14, MHC class II, and the macrophage marker CD68, as compared with normally differentiated DC. The use of specific blocking FcgammaR mAbs indicated that the effect of IC was exerted mainly through their interaction with FcgammaRI and to a lesser extend with FcgammaRII. Immature IC-DC also expressed higher levels of CD83, CD86, and CD40 and the expression of these maturation markers was not further regulated by LPS. The apparent lack of maturation following TLR stimulation was associated with a decreased production of IL-12, normal secretion of IL-10 and CCL22, and increased production of CXCL8 and CCL2. IC-DC displayed low endocytic activity and a reduced ability to induce allogeneic T cell proliferation both at basal and LPS-stimulated conditions. Altogether, these data reveal that IC strongly affect DC differentiation and maturation. Skewing of DC function from Ag presentation to a proinflammatory phenotype by IC resembles the state of activation observed in DC obtained from patients with chronic inflammatory autoimmune disorders, such as systemic lupus erythematosus disease and arthritis. Therefore, the altered maturation of DC induced by IC may be involved in the pathogenesis of autoimmune diseases.

Altered Expression of Fc and Complement Receptors on B Cells in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by B cell hyper-reactivity, autoantibody production, immune complex (IC) deposition, and multiple organ damage. The contribution of IC and B cell-mediated changes in the pathogenesis of SLE is well established, however, the exact role of IC-binding receptors expressed on B cells, Fcgamma receptors, and complement receptors CR1 and CR2 in these pathological processes is unclear. Development of lupus-like symptoms in mice defective for the inhibitory Fc-gammaRIIb and genetic association of certain FcgammaR genes with SLE demonstrate a significant role for these receptors but reports indicating alterations of Fcgamma or complement receptor-mediated B cell functions in human SLE are relatively few. The present review highlights a selected set of data including our own discussing the significance of animal models, genetics, and functional alterations of these IC-binding receptors in the etiopathogenesis of SLE.

[Expression of Fc receptors for IgG in peripheral blood leucocytes from hepatitis C virus infected individuals]

The immune response represents a fundamental element in the control of Hepatitis C virus (HCV) infection. Viral and cellular host factors may modulate this response. In the present study, we characterized immune complexes (cryoprecipitates) isolated form HCV-infected patients and evaluated the expression of Fc receptors for IgG (FcgammaR) in peripheral blood leucocytes of these patients. Twelve HCV (+) patients and 12 healthy control individuals were selected for this study. For each group, sera samples were collected for cryoglobulins isolation and characterization and EDTA-anticoagulated venous blood samples were collected for flow cytometry analysis of FcgammaR, CD64 (FcgammaRI), CD32 (FcgammaRII) and CD16 (FcgammaRIII) expression. Presence of HCV RNA in serum and cryoprecipitates was analysed by RT-PCR. Results show that 50% of HCV-infected patients present high levels of cryoglobulins mainly constituted by IgG. Three out of 5 cryoglobulins analyzed by RT-PCR were positive for HCV-RNA. Expression of CD64 was observed mainly in monocytes (80%), CD32 in monocytes, B lymphocytes and neutrophils (> 90%) and CD16 in NK cells and neutrophils (85% and 95% respectively). No differences were observed in the percentage of FcgammaR expression when comparing HCV-infected patients with healthy controls. On the contrary, density of expression of CD32 in monocytes and neutrophils cell populations of HCV patients was significantly lower than that observed in healthy controls (p < 0.05). We concluded that low density expression of FcgammaRII in HCV-infected patients may have implications in the physiopatholgy of HCV infection.

The CD16+Monocyte Subset Is More Permissive to Infection and Preferentially Harbors HIV-1 In Vivo

HIV-1 persists in peripheral blood monocytes in individuals receiving highly active antiretroviral therapy (HAART) with viral suppression, despite these cells being poorly susceptible to infection in vitro. Because very few monocytes harbor HIV-1 in vivo, we considered whether a subset of monocytes might be more permissive to infection. We show that a minor CD16+ monocyte subset preferentially harbors HIV-1 in infected individuals on HAART when compared with the majority of monocytes (CD14highCD16-). We confirmed this by in vitro experiments showing that CD16+ monocytes were more susceptible to CCR5-using strains of HIV-1, a finding that is associated with higher CCR5 expression on these cells. CD16+ monocytes were also more permissive to infection with a vesicular stomatitis virus G protein-pseudotyped reporter strain of HIV-1 than the majority of monocytes, suggesting that they are better able to support HIV-1 replication after entry. Consistent with this observation, high molecular mass complexes of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) were observed in CD16+ monocytes that were similar to those observed in highly permissive T cells. In contrast, CD14highCD16- monocytes contained low molecular mass active APOBEC3G, suggesting this is a mechanism of resistance to HIV-1 infection in these cells. Collectively, these data show that CD16+ monocytes are preferentially susceptible to HIV-1 entry, more permissive for replication, and constitute a continuing source of viral persistence during HAART.