TGF-beta regulation of human macrophage scavenger receptor CD163 is Smad3-dependent

Heterogeneity of Phenotypic and Functional Changes to Porcine Monocyte-Derived Macrophages Triggered by Diverse Polarizing Factors In Vitro

Swine are attracting increasing attention as a biomedical model, due to many immunological similarities with humans. However, porcine macrophage polarization has not been extensively analyzed. Therefore, we investigated porcine monocyte-derived macrophages (moMΦ) triggered by either IFN-γ + LPS (classical activation) or by diverse "M2-related" polarizing factors: IL-4, IL-10, TGF-β, and dexamethasone. IFN-γ and LPS polarized moMΦ toward a proinflammatory phenotype, although a significant IL-1Ra response was observed. Exposure to IL-4, IL-10, TGF-β, and dexamethasone gave rise to four distinct phenotypes, all antithetic to IFN-γ and LPS. Some peculiarities were observed: IL-4 and IL-10 both enhanced expression of IL-18, and none of the "M2-related" stimuli induced IL-10 expression. Exposures to TGF-β and dexamethasone were characterized by enhanced levels of TGF-β2, whereas stimulation with dexamethasone, but not TGF-β2, triggered CD163 upregulation and induction of CCL23. Macrophages stimulated with IL-10, TGF-β, or dexamethasone presented decreased abilities to release proinflammatory cytokines in response to TLR2 or TLR3 ligands: IL-10 showed a powerful inhibitory activity for CXCL8 and TNF release, whereas TGF-β provided a strong inhibitory signal for IL-6 production. While our results emphasized porcine macrophage plasticity broadly comparable to human and murine macrophages, they also highlighted some peculiarities in this species.

Comparative Phenotypic and Functional Analyses of the Effects of IL-10 or TGF-β on Porcine Macrophages

Simple Summary

Macrophages play a central role in innate immune response to both infectious and non-infectious stressors. They respond to different agonists modifying their phenotype and functions. In humans and mice, the regulatory cytokines IL-10 or TGF-β are both known to drive macrophage polarization into an anti-inflammatory phenotype, referred to as M2c. However, the immune systems of animal species each have their own peculiarities and the M2c subsets has never been investigated in pigs. A deep knowledge of the porcine immune system is required to design vaccines or control strategies against pathogens, which are a major constraint to pork production. Due to anatomical, physiological, and immunological similarities, swine are attracting increasing attention as a model for human diseases. To better characterize porcine macrophages, we evaluated the effects of IL-10 or TGF-β on the phenotype and function of monocyte-derived macrophages. Both cytokines downregulated the expression of MHC II DR and CD14. IL-10, but not TGF-β, statistically significantly reduced the ability of macrophages to respond to Toll-like receptor 2 (TLR2) or TLR4 agonists. Whilst these data suggest differentiation to an M2c-like immunosuppressive phenotype, the responses, and differences between IL-10 and TGF-β also reveals species-specific differences.

Abstract

Macrophages are phagocytic cells involved in maintaining tissue homeostasis and defense against pathogens. Macrophages may be polarized into different functionally specialized subsets. M2c macrophages arise following stimulation with IL-10 or TGF-β and mediate anti-inflammatory and tissue repair functions. M2c macrophages remain poorly characterized in the pig, thus we investigated the impact of these regulatory cytokines on porcine monocyte-derived macrophages (moMΦ). The phenotype and functionality of these cells was characterized though confocal microscopy, flow cytometry, ELISA, and RT-qPCR. Both cytokines induced CD14 and MHC II DR down-regulation and reduced IL-6, TNF-α, and CD14 expression, suggestive of an anti-inflammatory phenotype. Interestingly, neither IL-10 or TGF-β were able to trigger IL-10 induction or release by moMΦ. Differences between these cytokines were observed: stimulation with IL-10, but not TGF-β, induced up-regulation of both CD16 and CD163 on moMΦ. In addition, IL-10 down-regulated expression of IL-1β and IL-12p40 4h post-stimulation and induced a stronger impairment of moMΦ ability to respond to either TLR2 or TLR4 agonists. Overall, our results provide an overview of porcine macrophage polarization by two immunosuppressive cytokines, revealing differences between IL-10 and TGF-β, and reporting some peculiarity of swine, which should be considered in translational studies.

Molecular differences between arterial and venous grafts in the first year after coronary artery bypass grafting

Despite commonly used for coronary artery bypass surgery, saphenous vein (SV) grafts have significantly lower patency rates in comparison to internal thoracic artery (ITA) grafts, which might be due to the structural characteristics of the vessel wall but also due to differences in oxidative stress adaptation and molecular signaling and regulation. This human post mortem study included a total of 150 human bypass grafts (75 SV grafts and 75 ITA grafts) obtained from 60 patients divided into five groups due to the time period of implantation: group 1: baseline group without grafting; group 2: 1 day; group 3: > 1 day-1 week; group 4: > 1 week-1 month; group 5: > 1 month-1 year. Pieces of 3 mm length were fixed with formaldehyde, dehydrated, wax embedded, cut into sections of 3 µm thickness, and histologically and immunohistochemically examined. Over the whole time period, we observed a lower neointima formation and a better preserved media in ITA grafts with a higher percentage of TNF-α, PDGFR-α, and VEGF-A in nearly all vessel wall layers, a higher amount of MMP-7, MMP-9, EGFR, and bFGF positive cells in SV grafts and a timely different peak not only between ITA and SV grafts but also within the various vessel wall layers of both graft types. Since most of the examined growth factors, growth factor receptors and cytokines are regulated by MAPKs, our results suggest an activation of different pathways in both vessel graft types immediately after bypass grafting.

Zidovudine-Based Treatments Inhibit the Glycosylation of ADAM17 and Reduce CD163 Shedding From Monocytes

BACKGROUND

sCD163, a biomarker of monocyte-macrophage activation, has been identified as a predictor of all-cause mortality in treated HIV-infected individuals. Nevertheless, little is known about whether different antiretroviral drugs differentially regulate sCD163 levels and monocyte activation.

METHODS

A total of 123 patients receiving zidovudine (ZDV)-based (n = 55) or tenofovir disoproxil fumarate (TDF)-based (n = 68) antiretroviral regimens were enrolled, and their viral loads, CD4 counts, as well as plasma sCD163 and sCD14 levels were quantified. Twenty-eight (14 in each group) patients donated additional blood samples for flow cytometry and gene expression analyses using purified monocytes. THP-1 cultures were also used to investigate the effect of ZDV on ADAM17, which is responsible for CD163 shedding.

RESULTS

As compared to the TDF-treated group, the ZDV-treated group had lower plasma sCD163 levels and higher CD163 expression on CD14++CD16 monocytes. Five metabolic-inflammatory genes exhibited significantly different expression levels between purified monocytes of the ZDV and TDF groups (IL-6, 2.90-fold lower in ZDV group, P < 0.001; iNOS, 1.81-fold higher; CX3CR1, 1.72-fold lower; MIP-1β, 1.10-fold lower; and PPARγ-1, 1.36-fold higher, P < 0.05). Moreover, we show that ZDV treatment increases the surface expression of CD163 in cultured THP-1 cells, accompanied by the inhibition of glycosylation and surface expression of ADAM17.

CONCLUSIONS

Compared with TDF treatment, ZDV treatment causes lower plasma sCD163 levels, probably by inhibiting the glycosylation of ADAM17 and CD163 shedding. Our results show that ZDV functions as an ADAM17 inhibitor in vivo and extend our understanding of its immune-modulatory effects and adverse effects.

MicroRNA networks associated with active systemic juvenile idiopathic arthritis regulate CD163 expression and anti-inflammatory functions in macrophages through two distinct mechanisms

Systemic juvenile idiopathic arthritis (SJIA) is a severe childhood arthropathy with features of autoinflammation. Monocytes and macrophages in SJIA have a complex phenotype with both pro- and anti-inflammatory properties that combine features of several well characterized in vitro conditions used to activate macrophages. An important anti-inflammatory phenotype is expression of CD163, a scavenger receptor that sequesters toxic pro-inflammatory complexes that is highly expressed in both active SJIA and macrophage activation syndrome (MAS). CD163 is most strongly up-regulated by IL-10 (M(IL-10)), and not by other conditions that reflect features seen in SJIA monocytes such as M(LPS+IC). MicroRNA plays key roles in integrating cellular signals such as those in macrophage polarization, and as such we hypothesize microRNAs regulate macrophage functional responses in SJIA including CD163 expression. We find that 2 microRNAs previously found to be elevated in active SJIA, miR-125a-5p and miR-181c, significantly reduced macrophage CD163 expression through 2 distinct mechanisms. Neither microRNA was elevated in M(IL-10) with robust CD163 expression, but were instead induced in M(LPS+IC) where they restricted CD163 mRNA expression. Mir-181 species directly targeted CD163 mRNA for degradation. In contrast, miR-125a-5p functions indirectly, as transcriptome analysis of miR-125a-5p overexpression identified "cytokine-cytokine receptor interactions" as the most significantly repressed gene pathway, including decreased IL10RA, required for IL-10-mediated CD163 expression. Finally, overexpression of miR-181c inhibited CD163 anti-inflammatory responses to hemoglobin or high mobility group box 1 (HMGB1) complexes. Together, these data show that microRNA utilizes multiple mechanisms to integrate well-characterized polarization phenotypes and regulate macrophage functional properties seen in SJIA.

Potential role of IL-37 in atherosclerosis

IL-37 is a member of the IL-1 family, but unlike most other members of this family of cytokines, it has wide-ranging anti-inflammatory properties. Initially shown to bind IL-18 binding protein and prevent IL-18-mediated inflammation, its known role has been expanded to include distinct pathways, both intracellular involving the transcription factor Smad3, and extracellular via binding to the orphan receptor IL-1R8. A number of recent publications investigating the role of IL-37 in atherosclerosis and ischemic heart disease have revealed promising therapeutic value of the cytokine. Although research concerning the role of IL-37 and its mechanism in atherosclerosis is relatively scant, there are a number of well-known atherosclerotic processes that this cytokine can mediate with the potential of modulating the disease progression itself. This review will probe in detail the effects of IL-37 on important pathological processes such as inflammation, dysregulated lipid metabolism, and apoptosis, by analyzing existing data as well as exploring the potential of this cytokine to influence these properties.

Soluble membrane receptors, interleukin 6, procalcitonin and C reactive protein as prognostic markers in patients with severe sepsis and septic shock

Background

The objective of this study was to explore the diagnostic and prognostic value of soluble triggering receptor expressed on myeloid cell 1 (sTREM-1), soluble cluster of differentiation 14 (sCD14), soluble cluster of differentiation 163 (sCD163), interleukin-6 (IL-6), procalcitonin (PCT), and C-reactive protein (CRP) serum levels for patients with severe sepsis and septic shock in an intensive care unit (ICU).

Methods

Fifty patients admitted at the ICU with the diagnosis of severe sepsis or septic shock were studied. SOFA and APACHE II scores as well as serum biomarkers were measured at days 0, 2 and 5. The influence of these variables on 28-day mortality was analyzed. Twenty healthy individuals served as controls.

Results

Baseline serum concentrations of sTREM-1, sCD163, IL-6 and PCT correlated with SOFA score. Only sTREM-1 levels correlated with APACHE II score. The 28-day mortality rate for all patients was 42%. The absence of risk factors for infection, presence of septic shock, baseline values of sCD14 and decrease of PCT and IL-6 from baseline to day 5 were variables associated to mortality in the univariate analysis. The unique independent factor associated to mortality in the multivariate analysis was a decrease of PCT higher than 50% from days 0 to 5.

Conclusions

Serum levels of sTREM-1 are correlated with the severity of sepsis. A 50% decrease of PCT was the unique variable associated with survival in the multivariate analysis.

Regulation of Innate and Adaptive Immunity by TGFβ

Immune regulation by cytokines is crucial in maintaining immune homeostasis, promoting responses to infection, resolving inflammation, and promoting immunological memory. Additionally, cytokine responses drive pathology in immune-mediated disease. A crucial cytokine in the regulation of all aspects of an immune response is transforming growth factor beta (TGFβ). Although best known as a crucial regulator of T cell responses, TGFβ plays a vital role in regulating responses mediated by virtually every innate and adaptive immune cell, including dendritic cells, B cells, NK cells, innate lymphoid cells, and granulocytes. Here, we review our current knowledge of how TGFβ regulates the immune system, highlighting the multifunctional nature of TGFβ and how its function can change depending on location and context of action.

Scavenger Receptor CD163 and Its Biological Functions

CD163 is a member of scavenger receptor super family class B of the first subgroup. It is mapped to the region p13 on chromosome 12. Five different isoforms of CD163 have been described, which differ in the structure of their cytoplasmic domains and putative phosporylation sites. This scavenger receptor is selectively expressed on cells of monocytes and macrophages lineage exclusively. CD163 immunological function is essentially homeostatic. It also has other functions because participates in adhesion to endothelial cells, in tolerance induction and tissues regeneration. Other very important function of CD163 is the clearance of hemoglobin in its cell-free form and participation in anti-inflammation in its soluble form, exhibiting cytokine-like functions. We review the biological functions of CD163 which have been discovered until now. It seems apparent from this review that CD163 scavenger receptor can be used as biomarker in different diseases and as a valuable diagnostic parameter for prognosis of many diseases especially inflammatory disorders and sepsis.

Characterization of the Leukocyte Response in Acute Vocal Fold Injury

Macrophages location in the superficial layer of the vocal fold (VF) is not only at the first line of defense, but in a place of physiologic importance to voice quality. This study characterizes and compares macrophage function in two models of acute injury. Porcine VF injuries were created bilaterally by either surgical biopsy or lipopolysaccharide (LPS) (1.5μg/kg) injection. Animals were sacrificed at 1- or 5-day post LPS or 3-, 7-, or 23-days post-surgical injury (n = 3/time/ injury). Flow cytometry characterized immunophenotypes and RT-PCR quantified cytokine gene expression. Uninjured VF were used as controls. Post-surgical and LPS injury, SWC9+/SWC3- cells identified as hi SLA-DR+ (p<0.05) compared to controls along with hi CD16+ expression at 1-day and 3-days respectively compared to all other time points (p<0.05). Surgical injuries, SWC9+/SWC3- cells exhibited hi CD163+ (p<0.05) at 3-days along with upregulation in TNFα and TGFβ1 mRNA compared to 23-days (p<0.05). No measurable changes to IL–12, IFNγ, IL–10, IL–4 mRNA post-surgery. LPS injuries induced upregulation of TNFα, IL–12, IFNγ, IL–10, and IL–4 mRNA at 1- and 5-days compared to controls (p<0.05). Higher levels of IL–10 mRNA were found 1-day post-LPS compared to 5-days (p<0.05). No changes to CD163 or CD80/86 post-LPS were measured. Acute VF injuries revealed a paradigm of markers that appear to associate with each injury. LPS induced a regulatory phenotype indicated by prominent IL–10 mRNA expression. Surgical injury elicited a complex phenotype with early TNFα mRNA and CD163+ and persistent TGFβ1 transcript expression.

TGF-β1, but not bone morphogenetic proteins, activates Smad1/5 pathway in primary human macrophages and induces expression of proatherogenic genes

Macrophages are responsible for the control of inflammation and healing, and their malfunction results in cardiometabolic disorders. TGF-β is a pleiotropic growth factor with dual (protective and detrimental) roles in atherogenesis. We have previously shown that in human macrophages, TGF-β1 activates Smad2/3 signaling and induces a complex gene expression program. However, activated genes were not limited to known Smad2/3-dependent ones, which prompted us to study TGF-β1-induced signaling in macrophages in detail. Analysis of Id3 regulatory sequences revealed a novel enhancer, located between +4517 and 4662 bp, but the luciferase reporter assay demonstrated that this enhancer is not Smad2/3 dependent. Because Id3 expression is regulated by Smad1/5 in endothelial cells, we analyzed activation of Smad1/5 in macrophages. We demonstrate here for the first time, to our knowledge, that TGF-β1, but not BMPs, activates Smad1/5 in macrophages. We show that an ALK5/ALK1 heterodimer is responsible for the induction of Smad1/5 signaling by TGF-β1 in mature human macrophages. Activation of Smad1/5 by TGF-β1 induces not only Id3, but also HAMP and PLAUR, which contribute to atherosclerotic plaque vulnerability. We suggest that the balance between Smad1/5- and Smad2/3-dependent signaling defines the outcome of the effect of TGF-β on atherosclerosis where Smad1/5 is responsible for proatherogenic effects, whereas Smad2/3 regulate atheroprotective effects of TGF-β.

Liver myofibroblasts up-regulate monocyte CD163 expression via PGE2 during hepatitis B induced liver failure

Background

Although patients with liver failure exhibit a generalized inflammatory-imbalance status, substantial evidence indicates that this immunosuppressive or anti-inflammatory state may be deleterious. Increased expression of CD163 (known to be involved in several anti-inflammatory functions of the immune system) in patients with liver failure is significantly correlated with a fatal outcome. However, little is known of the regulatory mechanisms that influence the expression of CD163.

Methods

We assessed the expression of CD163 on monocytes from both circulating cells and the liver tissues of patients with hepatitis B induced liver failure using flow cytometry and isolated the myofibroblasts from diseased livers. The ability of human liver myofibroblasts to regulate CD163 expression on monocytes was studied in vitro.

Results

We showed that CD163⁺ monocytes were enriched primarily in diseased livers and that they were associated with liver myofibroblasts in the same area. Accordingly, liver myofibroblasts were significantly superior to normal skin fibroblasts in inducing the expression of CD163 on monocytes in vitro. Moreover, we found that liver myofibroblasts triggered the activation of monocytes by secreting PGE2. Inhibition of PGE2 production in liver myofibroblasts using NS-398 markedly reduced CD163 expression in vitro.

Conclusion

These results suggest that liver myofibroblasts play a direct role in regulating the expression of CD163 on monocytes in human liver tissues and thereby may regulate monocyte function during hepatitis B induced liver failure.

Phenotypic profile of alternative activation marker CD163 is different in Alzheimer's and Parkinson's disease

Background

Microglial activation is a pathological feature common to both Alzheimer’s and Parkinson’s diseases (AD and PD). The classical activation involves release of pro-inflammatory cytokines and reactive oxygen species. This is necessary for maintenance of tissue homeostasis and host defense, but can cause bystander damage when the activation is sustained and uncontrolled. In recent years the heterogeneous nature of microglial activation states in neurodegenerative diseases has become clear and the focus has shifted to alternative activation states that promote tissue maintenance and repair. We studied the distribution of CD163, a membrane-bound scavenger receptor found on perivascular macrophages. CD163 has an immunoregulatory function, and has been found in the parenchyma in other inflammatory diseases e.g. HIV-encephalitis and multiple sclerosis. In this study, we used immunohistochemistry to compare CD163 immunoreactivity in 31 AD cases, 27 PD cases, and 16 control cases. Associations of microglia with pathological hallmarks of AD and PD were investigated using double immunofluorescence.

Results

Parenchymal microglia were found to be immunoreactive for CD163 in all of the AD cases, and to a lesser extent in PD cases. There was prominent staining of CD163 immunoreactive microglia in the frontal and occipital cortices of AD cases, and in the brainstem of PD cases. Many of them were associated with Aß plaques in both diseases, and double staining with CD68 demonstrates their phagocytic capability. Leakage of fibrinogen was observed around compromised blood vessels, raising the possibility these microglia might have originated from the periphery.

Conclusions

Increase in microglia’s CD163 immunoreactivity was more significant in AD than PD, and association of CD163 immunoreactive microglia with Aβ plaques indicate microglia’s attraction towards extracellular protein pathology, i.e. extracellular aggregates of Aβ as compared to intracellular Lewy Bodies in PD. Double staining with CD163 and CD68 might point towards their natural inclination to phagocytose plaques. Fibrinogen leakage and compromise of the blood brain barrier raise the possibility that these are not resident microglia, but systemic macrophages infiltrating the brain.

Immunopathogenesis of porcine reproductive and respiratory syndrome in the respiratory tract of pigs

Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) impairs local pulmonary immune responses by damaging the mucociliary transport system, impairing the function of porcine alveolar macrophages and inducing apoptosis of immune cells. An imbalance between pro- and anti-inflammatory cytokines, including tumour necrosis factor-α and interleukin-10, in PRRS may impair the immune response of the lung. Pulmonary macrophage subpopulations have a range of susceptibilities to different PRRSV strains and different capacities to express cytokines. Infection with PRRSV decreases the bactericidal activity of macrophages, which increases susceptibility to secondary bacterial infections. PRRSV infection is associated with an increase in concentrations of haptoglobin, which may interact with the virus receptor (CD163) and induce the synthesis of anti-inflammatory mediators. The balance between pro- and anti-inflammatory cytokines modulates the expression of CD163, which may affect the pathogenicity and replication of the virus in different tissues. With the emergence of highly pathogenic PRRSV, there is a need for more information on the immunopathogenesis of different strains of PRRS, particularly to develop more effective vaccines.

α(1)-Acid glycoprotein up-regulates CD163 via TLR4/CD14 protein pathway: possible protection against hemolysis-induced oxidative stress

CD163, a scavenger receptor that is expressed at high levels in the monocyte-macrophage system, is a critical factor for the efficient extracellular hemoglobin (Hb) clearance during hemolysis. Because of the enormous detrimental effect of liberated Hb on our body by its ability to induce pro-inflammatory signals and tissue damage, an understanding of the molecular mechanisms associated with CD163 expression during the acute phase response is a central issue. We report here that α(1)-acid glycoprotein (AGP), an acute phase protein, the serum concentration of which is elevated under various inflammatory conditions, including hemolysis, up-regulates CD163 expression in both macrophage-like differentiated THP-1 (dTHP-1) cells and peripheral blood mononuclear cells in a time- and concentration-dependent manner. Moreover, the subsequent induction of Hb uptake was also observed in AGP-treated dTHP-1 cells. Among representative acute phase proteins such as AGP, α(1)-antitrypsin, C-reactive protein, and haptoglobin, only AGP increased CD163 expression, suggesting that AGP plays a specific role in the regulation of CD163. Consistently, the physiological concentrations of AGP induced CD163, and the subsequent induction of Hb uptake as well as the reduction of oxidative stress in plasma were observed in phenylhydrazine-induced hemolytic model mice, confirming the in vivo role of AGP. Finally, AGP signaling through the toll-like receptor-4 (TLR4) and CD14, the common innate immune receptor complex that normally recognizes bacterial components, was identified as a crucial stimulus that induces the autocrine regulatory loops of IL-6 and/or IL-10 via NF-κB, p38, and JNK pathways, which leads to an enhancement in CD163 expression. These findings provide possible insights into how AGP exerts anti-inflammatory properties against hemolysis-induced oxidative stress.

TGF-β inhibits the uptake of modified low density lipoprotein by human macrophages through a Smad-dependent pathway: a dominant role for Smad-2

The anti-atherogenic cytokine, TGF-β, plays a key role during macrophage foam cell formation by modulating the expression of key genes involved in the control of cholesterol homeostasis. Unfortunately, the molecular mechanisms underlying these actions of TGF-β remain poorly understood. In this study we examine the effect of TGF-β on macrophage cholesterol homeostasis and delineate the role of Smads-2 and ‐3 during this process. Western blot analysis showed that TGF-β induces a rapid phosphorylation-dependent activation of Smad-2 and ‐3 in THP-1 and primary human monocyte-derived macrophages. Small interfering RNA-mediated knockdown of Smad-2/3 expression showed that the TGF-β-mediated regulation of key genes implicated in the uptake of modified low density lipoproteins and the efflux of cholesterol from foam cells was Smad-dependent. Additionally, through the use of virally delivered Smad-2 and/or Smad-3 short hairpin RNA, we demonstrate that TGF-β inhibits the uptake of modified LDL by macrophages through a Smad-dependent mechanism and that the TGF-β-mediated regulation of CD36, lipoprotein lipase and scavenger receptor-A gene expression was dependent on Smad-2. These studies reveal a crucial role for Smad signaling, particularly Smad-2, in the inhibition of foam cell formation by TGF-β through the regulation of expression of key genes involved in the control of macrophage cholesterol homeostasis.

Surfing the data tsunami, a bioinformatic dissection of the proangiogenic monocyte

In this review we compare expression studies on monocyte subsets as an example to show the integrated possibilities of molecular databases and bioinformatic analysis tools. Monocytes have been recognized as cells with great plasticity and differentiation potential that play a pivotal role in revascularization processes, i.e. angiogenesis and arteriogenesis. To gain more insight in the relevant developmental programs, we compared the full-genome mRNA expression profiles of several distinct human monocyte subpopulations previously identified based on surface marker expression. These included classical and non-classical, M1 and M2 macrophages, circulating angiogenic cells (CAC), and non-monocyte-derived endothelial colony-forming cells (ECFC). Their transcriptional profiles revealed distinct and overlapping gene expression signatures and pathways reminiscent of utilization of transcription factors driving polarization into the different monocytic phenotypes. Hierarchical cluster analysis revealed that CAC are most related to M2 macrophages and unstimulated macrophages, and to a lesser extent to classical monocytes, and are quite distinct from M1 macrophages and ECFC. Analysis of the promoter region of CAC-expressed genes suggests that in particular the ETS family of transcription factors is important in CAC development. These analyses show the power of combining multiple datasets with existing databases on biological knowledge, to interpret full genome expression data.

Enhanced expression of TGFβ protein in lymphoid organs and lung, but not in serum, of pigs infected with a European field isolate of porcine reproductive and respiratory syndrome virus

Transforming growth factor β (TGFβ) is an immunomodulatory cytokine which is able to modulate the host immune response eliciting an inefficient response against pathogens. In this sense, the role of this cytokine in porcine reproductive and respiratory syndrome (PRRS) has been poorly studied and the reported results are contradictory. Thus, in the present study, the expression of TGFβ was analysed both at tissue (lymphoid organs and lung) and serum level to study its correlation with the expression of PRRS virus (PRRSV). To carry out this study, 32 pigs were inoculated with the European PRRSV field isolate 2982 and sequentially killed from 0 dpi to the end of the study (24 dpi). Blood and tissue samples were collected to determine the expression of PRRSV and TGFβ. PRRSV was detected in inoculated animals from 3 dpi until the end of the study, however TGFβ was not detected in sera from inoculated animals. Contrary, an increase of TGFβ antigen was observed both in the lymphoid organs and in the lung of PRRSV-inoculated pigs when compared with control group. Since TGFβ play a role as an immunomodulatory cytokine of the immune response and also in the differentiation of regulatory T cells (Tregs), the upregulation of the TGFβ at tissue level may play a role in the impairment of the host immune response observed during PRRS, being observed a significant correlation between PRRSV and TGFβ expression at lung level.

Efficient intracellular drug-targeting of macrophages using stealth liposomes directed to the hemoglobin scavenger receptor CD163

The hemoglobin scavenger receptor CD163 is exclusively expressed in the monocytic lineage and preferentially in tissue resident macrophages of the M2 phenotype and in macrophages in sites of inflammation and tumor growth. In the present study we have designed liposomes specifically targeting CD163 by hydrophobic linkage of CD163-binding monoclonal antibodies to polyethylene glycol-coated liposomes ('stealth liposomes'). Targeting to the endocytic CD163 protein greatly increased the uptake of liposomes in CD163 transfected cells and macrophages as visualized by confocal microscopy and flow cytometry of cells exposed to CD163 targeting liposomes loaded with calcein. Strong cytotoxic effects were seen in CD163-expressing human monocytes by using the chemotherapeutic agent doxorubicin as cargo of the liposomes. In conclusion, the use of stealth liposomes modified to recognize CD163 is a potential way to target drugs to macrophages that support inflammatory and malignant processes.

Expression of macrophage antigens by tumor cells

Macrophages are a heterogeneous cell population of the myeloid linage derived from monocytes. These cells show two different polarization states, M1 and M2 macrophages in response to different micro environmental signals. Tumor associated macrophages (TAM) represent the M2 type and promote tumor progression. These cells express antigens that more or less are specific for macrophages like: CD14, CD68, MAC387, CD163, and DAP12. In a series of recent studies it is shown that cancer cells may express these antigens and CD163, MAC387 and DAP12 may be expressed by e.g. breast cancer cells. Thus, 48% of the breast cancers expressed CD163 that is a scavenger receptor normally expressed by macrophages alone. The corresponding figure for rectal cancer is 31%. The expression of CD163 is correlated to early distant recurrence in breast cancer and local recurrence in rectal cancer and reduced survival time in both conditions. Expression of macrophage antigens in breast- and colorectal-cancers may have a prognostic relevance in clinical praxis. One explanation to these findings is that resemblance with macrophages may indicate a more invasive phenotype due to genetic exchange between the primary tumor cells and associated macrophages. This is further supported by the finding that expression of DAP12, a macrophage fusion receptor, in breast cancer is associated with an advanced tumor grade and higher rates of skeletal and liver metastases and overall shorter distant recurrence free survival. Another explanation to the changed phenotype is a genetic exchange between the cells by exosome-mediated transfer.

Expression of the macrophage antigen CD163 in rectal cancer cells is associated with early local recurrence and reduced survival time

Expression of the macrophage antigen CD163 in breast cancer cells is recently shown to be related to early distant recurrence and shortened survival. In this study, 163 patients with rectal cancer, included in the Swedish rectal cancer trial and followed up for a median of 71 months, were examined for the expression of CD163 in the primary tumors. The cancer cells expressed CD163 in the primary tumors in 23% (n = 32) of the patients. In pretreatment biopsies from 101 patients, 10 had CD163-positive cancers and these patients had earlier local recurrence (p < 0.044) and reduced survival time (p < 0.045) compared with those with CD163-negative tumors. When studying surgical specimens from 61 patients randomized to preoperative irradiation (5 x 5 Gy delivered in 1 week), it was found that 31% were CD163 positive whereas the corresponding figure was only 17% for 78 patients who were nonirradiated (p < 0.044), which tentatively may be consistent with X-rays inducing fusion. In CD163-positive tumors there was a reduced apoptotic activity as measured with the Termina deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) technique (p = 0.018). There tended also to be an increased proliferation activity measured as an expression of Ki-67 non significant (NS). It is concluded that primary rectal cancers may express CD-163, and this phenotypic macrophage trait is related to early local recurrence, shorter survival time and reduced apoptosis. Furthermore, the expression of CD163 is more common after irradiation.

Breast cancer expression of CD163, a macrophage scavenger receptor, is related to early distant recurrence and reduced patient survival

Cells of the monocyte/macrophage lineage are important for tumour cell migration, invasion and metastasis. Fusion between macrophages and cancer cells in animal models in vitro and in vivo causes hybrids with increased metastatic potential. Primary breast cancer cells were characterized for macrophage antigens to test if phenotypic resemblance to macrophages is related to early distant recurrence. Immunostaining for CD163, MAC387 and CD68 was performed in a breast cancer tissue micro array from 127 patients consequently followed up for a median of 13 years. Tumour-associated macrophages expressed all 3 antigens. The breast cancers expressed CD163 to 48%, MAC387 to 14% while CD68 was not expressed. TGF-beta staining intensity was positively related to both CD163 and MAC387 expression. Expression of CD163 in the cancer cells was compared to their DNA ploidy, Nottingham Histological Grade, TNM-stage, node state, presence of estrogen receptors and occurrence of distant metastases and survival. Cancers of a more advanced histological grade expressed CD163 to a higher extent. Cells expressing MAC387 were more common in cancers with a high proportion of CD163 positive cells. Multivariate analysis showed that expression of the macrophage antigen CD163 in breast cancer cells has a prognostic impact on the occurrence of distant metastases and reduced patient survival time.

Activation of a TGF-beta-specific multistep gene expression program in mature macrophages requires glucocorticoid-mediated surface expression of TGF-beta receptor II

Alternatively activated (M2) macrophages regulate steady state-, cancer-, and inflammation-related tissue remodeling. They are induced by Th2-cytokines and glucocorticoids (GC). The responsiveness of mature macrophages to TGF-beta, a cytokine involved in inflammation, cancer, and atherosclerosis, is currently controversial. Recently, we demonstrated that IL-17 receptor B is up-regulated in human monocyte-derived macrophages differentiated in the presence of Th2 cytokines IL-4 and TGF-beta1. In this study, we show that mature human macrophages differentiated in the presence of IL-4, and dexamethasone (M2(IL-4/GC)) but not M2(IL-4) responds to TGF-beta1 which induced a gene expression program comprising 111 genes including transcriptional/signaling regulators (ID3 and RGS1), immune modulators (ALOX5AP and IL-17 receptor B) and atherosclerosis-related genes (ALOX5AP, ORL1, APOC1, APOC2, and APOE). Analysis of molecular mechanism underlying GC/TGF-beta cooperation revealed that surface expression of TGF-betaRII was high in M2(GC) and M2(IL-4/GC), but absent from M2(IL-4), whereas the expression of TGF-betaRI/II mRNA, TGF-betaRII total protein, and surface expression of TGF-betaRIII were unchanged. GC dexamethasone was essential for increased surface expression of functional TGF-betaRII because its effect was observed also in combination with IL-13, M-CSF, and GM-CSF. Prolonged Smad2-mediated signaling observed in TGF-beta1-treated M2(IL-4/GC) was due to insufficient activity of negative feedback mechanism what can be explained by up-regulation of SIRT1, a negative regulator of Smad7, and the retention of TGF-betaRII complex on the cell surface. In summary, mature human M2 macrophages made permissive to TGF-beta by GC-induced surface expression of TGF-betaRII activate in response to TGF-beta1, a multistep gene expression program featuring traits of macrophages found within an atherosclerotic lesion.

Immunoparalysis after multiple trauma

The immunological sequelae following multiple trauma constitute an ongoing challenge in critical care management. The overall immune response to multiple trauma is a multilevel complex interdependently involving neurohormonal, cellular and haemodynamic factors. Immunoparalysis is characterised by a reduced capacity to present antigens via downregulated HLA-DR and an unbalanced monocyte-T cell interaction. Trauma-induced death of functionally conducive immune cells in the early recovery phase is significant in the emergence of posttraumatic multiple organ dysfunction or failure. Novel findings may contribute to more appropriate immunomonitoring and improved treatment. We must consider the preservation and support of immune function as the ultimate therapeutic goal, which may override the current strategy of simply antagonising excessive pro- or anti-inflammatory immune responses of the severely injured person. This review focuses on the injury-induced conduct of key immune effector cells and associated effects promoting immunoparalysis after multiple trauma.

Transforming growth factor-beta-regulated expression of genes in macrophages implicated in the control of cholesterol homoeostasis

The regulation of macrophage cholesterol homoeostasis is of crucial importance in the pathogenesis of atherosclerosis, an underlying cause of heart attack and stroke. Several recent studies have revealed a critical role for the cytokine TGF-beta (transforming growth factor-beta), a key regulator of the immune and inflammatory responses, in atherogenesis. We discuss here the TGF-beta signalling pathway and its role in this disease along with the outcome of our recent studies on the action of the cytokine on the expression of key genes implicated in the uptake or efflux of cholesterol by macrophages and the molecular mechanisms underlying such regulation.

Up-regulation of human monocyte CD163 upon activation of cell-surface Toll-like receptors

The hemoglobin (Hb) scavenger receptor, CD163, is a cell-surface glycoprotein that is expressed exclusively on monocytes and macrophages. It binds and internalizes haptoglobin-Hb complexes and has been implicated in the resolution of inflammation. Furthermore, the regulation of CD163 during an innate immune response implies an important role for this molecule in the host defense against infection. LPS, derived from the outer membrane of Gram-negative bacteria, activates TLR4 to cause acute shedding of CD163 from human monocytes, followed by recovery and induction of surface CD163 to higher levels than observed on untreated monocytes. We now report that the TLR2 and TLR5 agonists--Pam3Cys and bacterial flagellin--have similar effects on CD163 surface expression. Up-regulation of CD163 following treatment of human PBMC with TLR2, TLR4, and TLR5 agonists parallels increased production of IL-6 and IL-10, and neutralization of IL-6 and/or IL-10 blocks CD163 up-regulation. Furthermore, simultaneous stimulation of TLR2 or TLR5 in combination with TLR4 activation results in enhanced up-regulation of CD163. It is notable that exogenous recombinant IFN-gamma (rIFN-gamma) suppresses cell-surface, TLR-mediated IL-10 production as well as CD163 up-regulation. Sustained down-regulation of CD163 mediated by rIFN-gamma can be partially rescued with exogenous rIL-10 but not with exogenous rIL-6. This divergent regulation of CD163 by cytokines demonstrates that human monocytes react differently to infectious signals depending on the cytokine milieu they encounter. Thus, surface CD163 expression on mononuclear phagocytes is a carefully regulated component of the innate immune response to infection.

Functional expression of the CD163 scavenger receptor on acute myeloid leukemia cells of monocytic lineage

The hemoglobin-haptoglobin (Hb-Hp) scavenger receptor CD163 is a monocyte/macrophage-restricted surface antigen, whose expression is strongly up-regulated by glucocorticoids. We have previously shown that CD163 is expressed by acute myeloid leukemia (AML) cells of monocytic lineage. Herein, we expand this finding by demonstrating constitutive and glucocorticoid-enhanced CD163 expression on French-American-British M4/M5 AML cells, and leukemic blasts of other AML subtypes and normal hematopoietic progenitor cells do not express CD163. We provide evidence that the functional characteristics of CD163 are preserved on malignant cells by showing the capability of types M4/M5 blast cells to internalize Hb-Hp by a CD163-mediated mechanism. Together, our results identify CD163 as a potential target for therapeutic intervention. It is important that CD163 does not appear to be released from leukemic blasts under noninflammatory conditions, thus reducing the probability of off-target side-effects as a result of competitive binding of potential therapeutic ligands to nonmembrane-bound CD163.

Profiling of differentially expressed genes in wound margin biopsies of horses using suppression subtractive hybridization

Disturbed gene expression may disrupt the normal process of repair and lead to pathological situations resulting in excessive scarring. To prevent and treat impaired healing, it is necessary to first define baseline gene expression during normal repair. The objective of this study was to compare gene expression in normal intact skin (IS) and wound margin (WM) biopsies using suppression subtractive hybridization (SSH) to identify genes differentially expressed during wound repair in horses. Tissue samples included both normal IS and biopsies from 7-day-old wounds. IS cDNAs were subtracted from WM cDNAs to establish a subtracted (WM-IS) cDNA library; 226 nonredundant cDNAs were identified. Detection of genes previously shown to be expressed 7 days after trauma, including the pro-α2-chain of type 1 pro-collagen (COL1A2), annexin A2, the pro-α3-chain of type 6 pro-collagen, β-actin, fibroblast growth factor 7, laminin receptor 1, matrix metalloproteinase 1 (MMP1), secreted protein acidic cystein rich, and tissue inhibitor of metalloproteinase 2, supported the validity of the experimental design. A RT-PCR assay confirmed an increase or induction of the cDNAs of specific genes (COL1A2, MMP1, dermatan sulfate proteoglycan 2, cluster differentiation 68, cluster differentiation 163, and disintegrin and metalloproteinase domain 9) within wound biopsies. Among these, COL1A2 and MMP1 had previously been documented in horses; 68.8% of the cDNAs had not previously been attributed a role during wound repair, of which spermidine/spermine- N-acetyltransferase, serin proteinase inhibitor B10, and sorting nexin 9 were highly expressed and whose known functions in other processes made them potential candidates in regulating the proliferative response to wounding. In conclusion, we identified novel genes that are differentially expressed in equine wound biopsies and that may modulate repair. Future experiments must correlate changes in mRNA levels for precise molecules with spatiotemporal protein expression within tissues.