The biology of CSF-1 and its receptor

Bone marrow Adipoq-lineage progenitors are a major cellular source of M-CSF that dominates bone marrow macrophage development, osteoclastogenesis, and bone mass

M-CSF is a critical growth factor for myeloid lineage cells, including monocytes, macrophages, and osteoclasts. Tissue-resident macrophages in most organs rely on local M-CSF. However, it is unclear what specific cells in the bone marrow produce M-CSF to maintain myeloid homeostasis. Here, we found that Adipoq-lineage progenitors but not mature adipocytes in bone marrow or in peripheral adipose tissue, are a major cellular source of M-CSF, with these Adipoq-lineage progenitors producing M-CSF at levels much higher than those produced by osteoblast lineage cells. The Adipoq-lineage progenitors with high CSF1 expression also exist in human bone marrow. Deficiency of M-CSF in bone marrow Adipoq-lineage progenitors drastically reduces the generation of bone marrow macrophages and osteoclasts, leading to severe osteopetrosis in mice. Furthermore, the osteoporosis in ovariectomized mice can be significantly alleviated by the absence of M-CSF in bone marrow Adipoq-lineage progenitors. Our findings identify bone marrow Adipoq-lineage progenitors as a major cellular source of M-CSF in bone marrow and reveal their crucial contribution to bone marrow macrophage development, osteoclastogenesis, bone homeostasis, and pathological bone loss.

Exploring the "gene-protein-metabolite" network of coronary heart disease with phlegm and blood stasis syndrome by integrated multi-omics strategy

Background: According to the theory of traditional Chinese medicine, phlegm and blood stasis (PBS) is the pathological basis for coronary heart disease (CHD). This study aimed to explore the biological basis of PBS syndrome in CHD. Methods: Using a strategy that integrated RNA-seq, DIA-based proteomics, and untargeted metabolomics on 90 clinic samples, we constructed a "gene-protein-metabolite" network for CHD-PBS syndrome. We expanded the sample size and validated the differential genes and metabolites in the network through enzyme-linked immunosorbent assay. Results: Our findings revealed that the "gene-protein-metabolite" network of CHD-PBS syndrome included 33 mRNAs, four proteins, and 25 metabolites. JNK1, FOS, CCL2, CXCL8, PTGS2, and CSF1 were all poorly expressed in the PBS group during the sequencing stage, whereas arachidonic acid (AA) was highly expressed. During the validation stage, JNK1, AP-1, CCL2, and CXCL8 were poorly expressed, whereas PTGS2, CSF1, and AA were highly expressed. The area under the receiver operating curve was as follows: CSF1 [0.9635, 95%CI (0.9295, 0.9976)] >JNK1 [0.9361, 95% CI (0.8749, 0.9972)] >CXCL8 [0.8953, 95% CI (0.8222, 0.9684)] > CCL2 [0.8458, 95% CI (0.7676, 0.9241)] >AP-1 [0.7884, 95%CI (0.6869, 0.8899)]. The logistic regression model composed of CSF1 and JNK1 showed the greatest diagnostic value and significance for PBS syndrome. Conclusion: PBS syndrome is characterized by low levels of FOS, AP-1, CCL2, CXCL8, and JNK1 and elevated levels of PTGS2 and CSF1, implying that the AA metabolism is abnormal and that the JNK/AP-1 pathway is inhibited. PBS syndromes, as a subtype of CHD, may have unique molecular changes. Background. Globally, coronary heart disease (CHD) is the leading cause of death, and this would likely continue until 2030 (Mirzaei et al., 2009, 95, 740-746). According to the disease course, CHD can be classified as chronic stable CHD (or chronic coronary syndrome) and acute coronary syndrome (ACS) (Katus et al., 2017; Knuuti, 2019). Although stable CHD is not as lethal as ACS, it has a varied incidence range and patients with CHD have prolonged angina. Some symptoms of stable angina are alleviated with pharmacological therapy, but it cannot eliminate recurrent angina (Rousan et al., 2017). The clinical outcomes were not significantly improved in patients who underwent revascularization compared with those who received optimal pharmacological therapy (Shaw et al., 2008; Antman and Braunwald, 2020). A bottleneck appears to exist in CHD treatment, and traditional Chinese medicine (TCM) can act as a favorable complement. Because of its individualized treatment approach, TCM is widely practiced in eastern civilizations (Teng et al., 2016). TCM has become a principal complement in western countries (Wieland et al., 2013). Like "disease" is used in western medicine, "syndrome" is used in TCM to comprehend anomalous human conditions on the basis of patients' symptoms, tongue, and pulse (Li et al., 2012). On the basis of disease-syndrome diagnose, a TCM doctor can subclassify CHD patients into various categories, such as phlegm and blood stasis (PBS) syndrome, cold congealing and Qi stagnation syndrome, and Qi stagnation and blood stasis syndrome. PBS syndrome has recently emerged as a hot research topic in the TCM field. Objective diagnosis, expert consultations, and efficacy evaluation scales have been developed for PBS syndrome (Ren et al., 2020; Liu et al., 2021; Zheng et al., 2022). The concept of "omics" originates from the genome. It refers to the vocabulary generated by biological molecules at different levels to describe high-sequence molecular biological data resources (Dai and Shen, 2022). RNA, protein, and metabolites decipher the essence of complex etiologies, and the integration of transcriptomics, proteomics, and metabolomics are becoming a promising research mode (Pan et al., 2022). Multi-omics studies have revealed the biological characteristics of APOE transgenic mice, bronchopulmonary dysplasia, and plant tolerant to heavy metals (Singh et al., 2016; Lal et al., 2018; Mohler et al., 2020). Over the past few years, many academic achievements related to CHD-PBS syndrome have been accrued in the single-omic area. For example, Zhou identified the differential metabolites between PBS syndrome and Qi and Yin deficiency syndrome by using the urine samples of 1072 volunteers. Some of the specific metabolites of PBS syndrome are pyroglutamic acid, glutaric acid, glucose, mannitol, and xanthine (Zhou et al., 2019). Li's metabolomic study suggested that valine, leucine, isoleucine, and glycerol phospholipid metabolism could represent PBS syndrome (Zheng et al., 2022). Although some progress has been made in the understanding of PBS syndrome in CHD through the studies conducted, some issues still exist, such as a single-omics level, a lack of in-depth research, an inability to verify each other's research results, and a lack of validation of research conclusions. Overall, a systematic description of the biological foundation of PBS syndrome is lacking. Thus, the present study utilizes system biology methodologies and constructs a multi-omics network by integrating differential genes, proteins, and metabolites to systematically and comprehensively reveal the biological basis of CHD-PBS syndrome. The current study explored 1) the characteristics of the transcriptome, proteome, and metabolome for CHD-PBS syndrome; 2) the "gene-protein-metabolite" network based on differential genes (DGs), differential proteins (DPs), and differential metabolites (DMs); 3) the key biological process and metabolic pathway most related to PBS syndrome; and 4) quantitative results and the diagnostic potential of biomarkers for PSB syndrome. Materials and methods. Multi-omics sequencing, bioinformatics analysis, and clinical validation research strategy. We collected the blood samples from healthy subjects as well as CHD patients with PBS and non-phlegm and blood stasis (NPBS) syndrome to compare the differences between them by subjecting the samples to the transcriptome, proteome, and metabolomics analyses. Bioinformatics analysis identified differential molecules as well as related biological processes and pathways. Next, the "gene-protein-metabolite" network was constructed using the MetaboAnalyst database, String database, and Cytoscape software. We selected molecules with strong centrality and biological association as potential PBS syndrome biomarkers and recruited more volunteers for further validation by enzyme-linked immunosorbent assay (ELISA). Finally, the ROC curve was utilized to assess the level and diagnostic efficacy of various molecules (Figure 1).

Immune niches orchestrated by intestinal mesenchymal stromal cells lining the crypt-villus

The mammalian intestine is an organ that can be spatially defined by two axes: longitudinal and vertical. Such anatomical structure ensures the maintenance of a relatively immuno-quiescent and proliferation-promoting crypt for intestinal stem cell differentiation while actively warding off the invading intestinal microbes at the villus tip during digestion and nutrient absorption. Such behavior is achieved by the fine coordination among intestinal epithelial cells, intestinal mesenchymal stromal cells and tissue-resident immune cells like myeloid cells and lymphocytes. Among these cell types resided in the colon, intestinal mesenchymal stromal cells are considered to be the essential link between epithelium, vasculature, neuronal system, and hematopoietic compartment. Recent advancement of single cell and spatial transcriptomics has enabled us to characterize the spatial and functional heterogeneity of intestinal mesenchymal stromal cells. These studies reveal distinctive intestinal mesenchymal stromal cells localized in different regions of the intestine with diverse functions including but not limited to providing cytokines and growth factors essential for different immune cells and epithelial cells which predict niche formation for immune function from the villus tip to the crypt bottom. In this review, we aim to provide an overall view of the heterogeneity of intestinal mesenchymal stromal cells, the spatial distribution of these cells along with their interaction with immune cells and the potential regulatory cytokine profile of these cell types. Summarization of such information may enrich our current understanding of the immuno-regulatory functions of the newly identified mesenchymal stromal cell subsets beyond their epithelial regulatory function.

Neutrophil and Macrophage Cell Surface Colony-Stimulating Factor 1 Shed by ADAM17 Drives Mouse Macrophage Proliferation in Acute and Chronic Inflammation

Macrophages are prominent cells in acute and chronic inflammatory diseases. Recent studies highlight a role for macrophage proliferation post-monocyte recruitment under inflammatory conditions. Using an acute peritonitis model, we identify a significant defect in macrophage proliferation in mice lacking the leukocyte transmembrane protease ADAM17. The defect is associated with decreased levels of macrophage colony-stimulating factor 1 (CSF-1) in the peritoneum and is rescued by intraperitoneal injection of CSF-1. Cell surface CSF-1 (csCSF-1) is one of the substrates of ADAM17. We demonstrate that both infiltrated neutrophils and macrophages are major sources of csCSF-1. Furthermore, acute shedding of csCSF-1 following neutrophil extravasation is associated with elevated expression of iRhom2, a member of the rhomboid-like superfamily, which promotes ADAM17 maturation and trafficking to the neutrophil surface. Accordingly, deletion of hematopoietic iRhom2 is sufficient to prevent csCSF-1 release from neutrophils and macrophages and to prevent macrophage proliferation. In acute inflammation, csCSF-1 release and macrophage proliferation are self-limiting due to transient leukocyte recruitment and temporally restricted csCSF-1 expression. In chronic inflammation, such as atherosclerosis, the ADAM17-mediated lesional macrophage proliferative response is prolonged. Our results demonstrate a novel mechanism whereby ADAM17 promotes macrophage proliferation in states of acute and chronic inflammation.

A novel miR17/protein tyrosine phosphatase-oc/EphA4 regulatory axis of osteoclast activity

Information about the molecular mechanisms leading to the activation of the osteoclast is relatively limited. While there is compelling evidence that the signaling mechanisms of Src and integrin β₃ are essential for osteoclast activation, the regulation of these two signaling mechanisms is not fully understood. In this review, evidence supporting a novel regulatory axis of osteoclast activation that plays an upstream regulatory role in both the Src and integrin β₃ signaling during osteoclast activation is discussed. This regulatory axis contains three unique components: a structurally unique transmembrane protein-tyrosine phosphatase, PTP-oc, EphA4, and miR17. In the first component, PTP-oc activates the Src signaling through dephosphorylation of the inhibitory tyr-527 of Src. This in turn activates the integrin β₃ signaling, enhances the JNK2/NFκB signaling, promotes the ITAM/Syk signaling, and suppresses the ITIM/Shp1 signaling; the consequence of which is activation of the osteoclast. In the second component, EphA4 inhibits osteoclast activity by suppressing the integrin β₃ signaling. PTP-oc relieves the suppressive actions of EphA4 by directly dephosphorylating EphA4. In the third component, PTP-oc expression is negatively regulated by miR17. Accordingly, suppression of miR17 during osteoclast activation upregulates the PTP-oc signaling and suppresses the EphA4 signaling, resulting in the activation of the osteoclast. This regulatory axis is unique, in that each of the three components acts to exert suppressive action on their respective immediate downstream inhibitory step. Because the final downstream event is the EphA4-mediated inhibition of osteoclast activation, the overall effect of this mechanism is the stimulation of osteoclast activity.

Differential prognostic impact of interleukin-34 mRNA expression and infiltrating immune cell composition in intrinsic breast cancer subtypes

Interleukin-34 (IL-34) is a ligand for the CSF-1R and has also two additional receptors, PTPRZ1 and syndecan-1. IL-34 plays a role in innate immunity, inflammation, and cancer. However, the role of IL-34 in breast cancer is still ill-defined. We analyzed IL-34 mRNA expression in breast cancer cell lines and breast cancer patients and applied established computational approaches (CIBERSORT, ESTIMATE, TIMER, TCIA), to analyze gene expression data from The Cancer Genome Atlas (TCGA). Expression of IL-34 was associated with a favorable prognosis in luminal and HER2 but not basal breast cancer patients. Gene expression of CSF-1 and CSF-1R was strongly associated with myeloid cell infiltration, while we found no or only weak correlations between IL-34, PTPRZ1, syndecan-1 and myeloid cells. In vitro experiments showed that tyrosine phosphorylation of CSF-1R, ERK, and FAK and cell migration are differentially regulated by IL-34 and CSF-1 in breast cancer cell lines. Collectively, our data suggest that correlation of IL-34 gene expression with survival is dependent on the molecular breast cancer subtype. Furthermore, IL-34 is not associated with myeloid cell infiltration and directly regulates breast cancer cell migration and signaling.

Does niche competition determine the origin of tissue-resident macrophages?

Most tissue-resident macrophages are derived from embryonic precursors but, under certain circumstances, circulating monocytes can differentiate into self-maintaining tissue-resident macrophages that resemble their embryonic counterparts. In this Opinion article, we propose that distinct macrophage precursors have an almost identical potential to develop into resident macrophages but they compete for a restricted number of niches. The tight regulation of the niche ensures that monocytes do not differentiate into macrophages when the niche is full but that these cells can differentiate efficiently into macrophages when the niche is available. Imprinting by the niche would be the dominant factor conferring macrophage identity and self-maintenance capacity, rather than origin as was previously proposed.

Cytokine and chemokine alterations in tissue, CSF, and plasma in early presymptomatic phase of experimental allergic encephalomyelitis (EAE), in a rat model of multiple sclerosis

BACKGROUND

Experimental allergic encephalomyelitis (EAE) is the most commonly used experimental animal model for human multiple sclerosis (MS) that has been used so far to study the acute and remission-relapsing phases of the disease. Despite the vast literature on neuroinflammation onset and progression in EAE, important questions are still open regarding in particular the early asymptomatic phase between immunization and clinical onset.

METHODS

In this study, we performed a time-course investigation of neuroinflammation and demyelination biomarkers in the spinal cord (SC), cerebrospinal fluid (CSF), and blood in EAE induced in dark agouti (DA) female rats compared to the controls and adjuvant-injected rats, using high-throughput technologies for gene expression and protein assays and focusing on the time-course between immunization, clinical onset (1, 5, 8 days post-immunization (DPI)), and progression (11 and 18 DPI). The expression profile of 84 genes related to T cell activation/signaling, adaptive immunity, cytokine/chemokine inflammation, demyelination, and cellular stress were analyzed in the tissue; 24 cytokines were measured in the CSF and plasma.

RESULTS

The macrophage colony-stimulating factor (CSF1) was the first up-regulated protein as far as 1 DPI, not only in blood but also in CSF and SC. A treatment with GW2580, a selective CSF1R inhibitor, slowed the disease progression, significantly reduced the severity, and prevented the relapse phase. Moreover, both pro-inflammatory (IL-1β, TNF-α) and anti-inflammatory cytokines (IL-5, IL-10, VEGF) were up-regulated starting from 8 DPI. Myelin genes were down-regulated starting from 8 DPI, especially MAL, MBP, and PMP22 while an opposite expression profile was observed for inflammation-related genes, such as CXCL11 and CXCL10.

CONCLUSIONS

This early cytokine and chemokine regulation indicates that novel biomarkers and therapeutic options could be explored in the asymptomatic phase of EAE. Overall, our findings provide clear evidence that CSF1R signaling regulates inflammation in EAE, supporting therapeutic targeting of CSF1R in MS.

Model-Based Characterization of Inflammatory Gene Expression Patterns of Activated Macrophages

Macrophages are cells with remarkable plasticity. They integrate signals from their microenvironment leading to context-dependent polarization into classically (M1) or alternatively (M2) activated macrophages, representing two extremes of a broad spectrum of divergent phenotypes. Thereby, macrophages deliver protective and pro-regenerative signals towards injured tissue but, depending on the eliciting damage, may also be responsible for the generation and aggravation of tissue injury. Although incompletely understood, there is emerging evidence that macrophage polarization is critical for these antagonistic roles. To identify activation-specific expression patterns of chemokines and cytokines that may confer these distinct effects a systems biology approach was applied. A comprehensive literature-based Boolean model was developed to describe the M1 (LPS-activated) and M2 (IL-4/13-activated) polarization types. The model was validated using high-throughput transcript expression data from murine bone marrow derived macrophages. By dynamic modeling of gene expression, the chronology of pathway activation and autocrine signaling was estimated. Our results provide a deepened understanding of the physiological balance leading to M1/M2 activation, indicating the relevance of co-regulatory signals at the level of Akt1 or Akt2 that may be important for directing macrophage polarization.

Macrophages are essential cells of the immune system and indispensable for a defense against bacterial infection. They reside as resting, immune modulatory cells in several tissues of the human body where they continuously sense inputs from their local environment. They react to stimuli such as toxins, injury or bacterial products in a process termed macrophage activation or polarization. For example, the bacterial component lipopolysaccharide induces so-called classical activation of macrophages into the M1 phenotype that secretes a number of inflammatory cytokines and chemokines leading to killing of bacteria and resolution of inflammation. Another prominent phenotype of macrophages is the M2 polarization state that is associated with wound healing and tissue regeneration. Unbalanced activation of macrophages is implicated in a number of diseases. An improved knowledge and extensive characterization of these macrophages as well as the factors determining their phenotypes will improve the understanding of the role of macrophages in disease progression.

FLT1 signaling in metastasis-associated macrophages activates an inflammatory signature that promotes breast cancer metastasis

Although the link between inflammation and cancer initiation is well established, its role in metastatic diseases, the primary cause of cancer deaths, has been poorly explored. Our previous studies identified a population of metastasis-associated macrophages (MAMs) recruited to the lung that promote tumor cell seeding and growth. Here we show that FMS-like tyrosine kinase 1 (Flt1, also known as VEGFR1) labels a subset of macrophages in human breast cancers that are significantly enriched in metastatic sites. In mouse models of breast cancer pulmonary metastasis, MAMs uniquely express FLT1. Using several genetic models, we show that macrophage FLT1 signaling is critical for metastasis. FLT1 inhibition does not affect MAM recruitment to metastatic lesions but regulates a set of inflammatory response genes, including colony-stimulating factor 1 (CSF1), a central regulator of macrophage biology. Using a gain-of-function approach, we show that CSF1-mediated autocrine signaling in MAMs is downstream of FLT1 and can restore the tumor-promoting activity of FLT1-inhibited MAMs. Thus, CSF1 is epistatic to FLT1, establishing a link between FLT1 and inflammatory responses within breast tumor metastases. Importantly, FLT1 inhibition reduces tumor metastatic efficiency even after initial seeding, suggesting that these pathways represent therapeutic targets in metastatic disease.

Colony stimulating factor-1 receptor signaling networks inhibit mouse macrophage inflammatory responses by induction of microRNA-21

Macrophage polarization between the M2 (repair, protumorigenic) and M1 (inflammatory) phenotypes is seen as a continuum of states. The detailed transcriptional events and signals downstream of colony-stimulating factor 1 receptor (CSF-1R) that contributes to amplification of the M2 phenotype and suppression of the M1 phenotype are largely unknown. Macrophage CSF-1R pTyr-721 signaling promotes cell motility and enhancement of tumor cell invasion in vitro. Combining analysis of cellular systems for CSF-1R gain of function and loss of function with bioinformatic analysis of the macrophage CSF-1R pTyr-721-regulated transcriptome, we uncovered microRNA-21 (miR-21) as a downstream molecular switch controlling macrophage activation and identified extracellular signal-regulated kinase1/2 and nuclear factor-κB as CSF-1R pTyr-721-regulated signaling nodes. We show that CSF-1R pTyr-721 signaling suppresses the inflammatory phenotype, predominantly by induction of miR-21. Profiling of the miR-21-regulated messenger RNAs revealed that 80% of the CSF-1-regulated canonical miR-21 targets are proinflammatory molecules. Additionally, miR-21 positively regulates M2 marker expression. Moreover, miR-21 feeds back to positively regulate its own expression and to limit CSF-1R-mediated activation of extracellular signal-regulated kinase1/2 and nuclear factor-κB. Consistent with an anti-inflammatory role of miRNA-21, intraperitoneal injection of mice with a miRNA-21 inhibitor increases the recruitment of inflammatory monocytes and enhances the peritoneal monocyte/macrophage response to lipopolysaccharide. These results identify the CSF-1R-regulated miR-21 network that modulates macrophage polarization.

Myelopoietic efficacy of orlistat in murine hosts bearing T cell lymphoma: implication in macrophage differentiation and activation

Orlistat, an inhibitor of fatty acid synthase (FASN), acts as an antitumor agent by blocking de novo fatty acid synthesis of tumor cells. Although, myelopoiesis also depends on de novo fatty acid synthesis, the effect of orlistat on differentiation of macrophages, which play a central role in host’s antitumor defence, remains unexplored in a tumor-bearing host. Therefore, the present investigation was undertaken to examine the effect of orlistat administration on macrophage differentiation in a T cell lymphoma bearing host. Administration of orlistat (240 mg/kg/day/mice) to tumor-bearing mice resulted in a decline of tumor load accompanied by an augmentation of bone marrow cellularity and survival of bone marrow cells (BMC). The expression of apoptosis regulatory caspase-3, Bax and Bcl2 was modulated in the BMC of orlistat-administered tumor-bearing mice. Orlistat administration also resulted in an increase in serum level of IFN-γ along with decreased TGF-β and IL-10. BMC of orlistat-administered tumor-bearing mice showed augmented differentiation into macrophages accompanied by enhanced expression of macrophage colony stimulating factor (M-CSF) and its receptor (M-CSFR). The macrophages differentiated from BMC of orlistat-administered mice showed characteristic features of M₁ macrophage phenotype confirmed by expression of CD11c, TLR-2, generation of reactive oxygen species, phagocytosis, tumor cell cytotoxicity, production of IL-1,TNF-α and nitric oxide. These novel findings indicate that orlistat could be useful to support myelopoesis in a tumor-bearing host.

Cloning and expression analysis of grouper (Epinephelus coioides) M-CSFR gene post Cryptocaryon irritans infection and distribution of M-CSFR(+) cells

The M-CSF/M-CSFR system plays a central role in the cell survival, proliferation, differentiation and maturation of the monocyte/macrophage lineage. In present study, we cloned the sequence of the M-CSFR cDNA from the orange-spotted grouper (Epinephelus coioides). Sequence analysis reveals that ten cysteines in the extracellular immunoglobulin-like (Ig-like) domains of EcM-CSFR are conserved in fish and mammals, its nine possible N-glycosylation sites are conserved in fish but not mammals, 7 of 8 identified mammal M-CSFR intracellular autophosphorylation tyrosine sites was found in EcM-CSFR. Real-time PCR showed that the constitutive expression level of EcM-CSFR was the highest in the spleen, less in the gill, kidney, head kidney and liver, least in the blood, skin, gut and thymus. A rabbit anti-EcM-CSFR polyclonal antibody against the recombinant EcM-CSFR extracellular domain was developed and it was efficient in labeling the monocytes and macrophages isolated from the head kidney. Immunochemistry analysis showed that M-CSFR(+) cells located in all tested paraffin-embedded tissues and M-CSFR(+) cell centres with the characteristic of melano-macrophage centres(MMCs) was found in the spleen, head kidney, kidney, gut and liver. All these results indicate the widespread distribution of macrophages in grouper tissues and its importance in fish immune system. In Crytocaryon irritans infected grouper, EcM-CSFR was transient up-regulated and rapidly down-regulated in skin, gill, head kidney and spleen. The possible activation mechanism of macrophage via EcM-CSFR signal transduction in the fish anti-C. irritans infection was discussed.

Inflammatory markers in coronary artery disease

Coronary artery disease (CAD) is one of the most common manifestations of atherosclerosis. Inflammation is considered one of the major processes that contribute to atherogenesis. Inflammation plays an important role not only on the initiation and progression of atherosclerosis but also on plaque rupture, an event that leads to acute vascular events. Various biomarkers express different pathways and pathophysiologic mechanisms of cardiovascular disease, and inflammatory biomarkers express different parts of the atherogenic process, regarding the initiation and progression of atherosclerosis or the destabilization of the atherosclerotic plaque. Therefore, inflammatory biomarkers may prove to be useful in the detection, staging, and prognosis of patients with CAD. Furthermore, the fact that inflammatory processes are essential steps in the course of the disease offers future therapeutic targets for the interruption of the atherogenic process or for the management of acute events.

Autocrine CSF-1 and CSF-1 receptor coexpression promotes renal cell carcinoma growth

Renal cell carcinoma is increasing in incidence but the molecular mechanisms regulating its growth remain elusive. Coexpression of the monocytic growth factor colony-stimulating factor (CSF)-1 and its receptor CSF-1R on renal tubular epithelial cells (TEC) will promote proliferation and antiapoptosis during regeneration of renal tubules. Here, we show that a CSF-1-dependent autocrine pathway is also responsible for the growth of renal cell carcinoma (RCC). CSF-1 and CSF-1R were coexpressed in RCCs and TECs proximally adjacent to RCCs. CSF-1 engagement of CSF-1R promoted RCC survival and proliferation and reduced apoptosis, in support of the likelihood that CSF-1R effector signals mediate RCC growth. In vivo CSF-1R blockade using a CSF-1R tyrosine kinase inhibitor decreased RCC proliferation and macrophage infiltration in a manner associated with a dramatic reduction in tumor mass. Further mechanistic investigations linked CSF-1 and epidermal growth factor signaling in RCCs. Taken together, our results suggest that budding RCC stimulates the proximal adjacent microenvironment in the kidney to release mediators of CSF-1, CSF-1R, and epidermal growth factor expression in RCCs. Furthermore, our findings imply that targeting CSF-1/CSF-1R signaling may be therapeutically effective in RCCs.

Gab2 promotes colony-stimulating factor 1-regulated macrophage expansion via alternate effectors at different stages of development

Colony-stimulating factor 1 (CSF-1) receptor (CSF-1R, or macrophage CSF receptor [M-CSFR]) is the primary regulator of the proliferation, survival, and differentiation of mononuclear phagocytes (MNPs), but the critical CSF-1 signals for these functions are unclear. The scaffold protein Gab2 is a major tyrosyl phosphoprotein in the CSF-1R signaling network. Here we demonstrate that Gab2 deficiency results in profoundly defective expansion of CSF-1R-dependent MNP progenitors in the bone marrow, through decreased proliferation and survival. Reconstitution and phospho-flow studies show that downstream of CSF-1R, Gab2 uses phosphatidylinositol 3-kinase (PI3K)-Akt and extracellular signal-regulated kinase (Erk) to regulate MNP progenitor expansion. Unexpectedly, Gab2 ablation enhances Jun N-terminal protein kinase 1 (JNK1) phosphorylation in differentiated MNPs but reduces their proliferation; inhibition of JNK signaling or reduction of JNK1 levels restores proliferation. MNP recruitment to inflammatory sites and the corresponding bone marrow response is strongly impaired in Gab2-deficient mice. Our data provide genetic and biochemical evidence that CSF-1R, through Gab2, utilizes different effectors at different stages of MNP development to promote their expansion.

Adaptor protein Lnk inhibits c-Fms-mediated macrophage function

The M-CSFR (c-Fms) participates in proliferation, differentiation, and survival of macrophages and is involved in the regulation of distinct macrophage functions. Interaction with the ligand M-CSF results in phosphorylation of tyrosine residues on c-Fms, thereby creating binding sites for molecules containing SH2 domains. Lnk is a SH2 domain adaptor protein that negatively regulates hematopoietic cytokine receptors. Here, we show that Lnk binds to c-Fms. Biological and functional effects of this interaction were examined in macrophages from Lnk-deficient (KO) and WT mice. Clonogenic assays demonstrated an elevated number of M-CFUs in the bone marrow of Lnk KO mice. Furthermore, the M-CSF-induced phosphorylation of Akt in Lnk KO macrophages was increased and prolonged, whereas phosphorylation of Erk was diminished. Zymosan-stimulated production of ROS was increased dramatically in a M-CSF-dependent manner in Lnk KO macrophages. Lastly, Lnk inhibited M-CSF-induced migration of macrophages. In summary, we show that Lnk binds to c-Fms and can blunt M-CSF stimulation. Modulation of levels of Lnk in macrophages may provide a unique therapeutic approach to increase innate host defenses.

Role of protein-tyrosine phosphatases in regulation of osteoclastic activity

Osteoclasts, the primary cell type mediating bone resorption, are multinucleated, giant cells derived from hematopoietic cells of monocyte-macrophage lineage. Osteoclast activity is, in a large part, regulated by protein-tyrosine phosphorylation. While information about functional roles of several protein-tyrosine kinases (PTK), including c-Src, in osteoclastic resorption has been accumulated, little is known about the roles of protein-tyrosine phosphatases (PTPs) in regulation of osteoclast activity. Recent evidence implicates important regulatory roles for four PTPs (SHP-1, cyt-PTP-epsilon, PTP-PEST, and PTPoc) in osteoclasts. Cyt-PTP-epsilon, PTP-PEST, and PTP-oc are positive regulators of osteoclast activity, while SHP-1 is a negative regulator. Of these PTPs in osteoclasts, only PTP-oc is a positive regulator of c-Src PTK through dephosphorylation of the inhibitory phosphotyrosine-527 residue. Although some information about mechanisms of action of these PTPs to regulate osteoclast activity is reviewed in this article, much additional work is required to provide more comprehensive details about their functions in osteoclasts.

Colony stimulating factor-1 (CSF-1) in pregnancy

Uterine growth factors appear to play a role in the regulation of pregnancy. One of these, colony stimulating factor-1 (CSF-1), synthesized by the uterine epithelium under the control of female sex steroids, has been shown to have important functions both before implantation and during the formation of the placenta. In the female reproductive tract the CSF-1 receptor, the product of the c-fms proto-oncogene, is expressed in decidual cells, trophoblasts and macrophages, indicating that these cells are the primary targets for CSF-1. This article reviews the biology of CSF-1 during gestation as well as the possible involvement of CSF-1 and its receptor in the aetiology of gynaecological tumours.

Targeting stromal-cancer cell interactions with siRNAs

Tumors are composed of both malignant and normal cells, including fibroblasts, endothelial cells, mesenchymal stem cells, and inflammatory immune cells such as macrophages. These various stromal components interact with cancer cells to promote growth and metastasis. For example, macrophages, attracted by colony-stimulating factor-1 (CSF-1) produced by tumor cells, in turn produce various growth factors such as vascular endothelial growth factor, which supports the growth of tumor cells and their interaction with blood vessels leading to enhanced tumor cell spreading. The activation of autocrine and paracrine oncogenic signaling pathways by stroma-derived growth factors and cytokines has been implicated in promoting tumor cell proliferation and metastasis. Furthermore, matrix metalloproteinases (MMPs) derived from both tumor cells and the stromal compartment are regarded as major players assisting tumor cells during metastasis. Collectively, these recent findings indicate that targeting tumor-stroma interactions is a promising strategy in the search for novel treatment modalities in human cancer. This chapter summarizes our current understanding of the tumor microenvironment and highlights some potential targets for therapeutic intervention with small interfering RNAs.

Inflammatory and non-invasive vascular markers: the multimarker approach for risk stratification in coronary artery disease

Current thinking supports the notion that several inflammatory proteins intervene with endothelium and haemostatic factors leading to plaque formation and rupture. Of these, C-reactive protein (CRP), monocyte/macrophage colony-stimulating factor (MCSF) and interleukin-6 (IL-6) promote atherogenesis by inducing monocyte-macrophage activation, foam cell formation, platelet activation, tissue factor expression, release of other procoagulant cytokines or downregulation of atheroprotective cytokines such as interleukin 10 and transforming growth factor b-1 (TGFb-1). CRP, MSCF and IL-6 are interrelated and have been found in increased blood concentrations in CAD. Increased levels of CRP and IL-6 predict a higher cardiovascular event rate in the general population and in addition to high MCSF or low TGFb-1 predict adverse outcome in CAD patients independently of traditional risk factors. Moreover, in CAD patients, the predictive value of MCSF is additive and beyond that of CRP suggesting the need of a "multimarker approach" in assessing cardiovascular risk. Accumulating evidence supports the utility of non-invasive markers of subclinical atherosclerosis, namely carotid intimal media thickness, flow mediated dilatation of the brachial artery, augmentation index or pulse wave velocity, in the prediction of cardiovascular risk particularly in primary prevention settings. The combination of these non-invasive tests has been shown to improve their prognostic accuracy compared to each other alone. Although several therapeutic strategies like vaccination against antigens promoting atherogenesis, cyclooxygenase inhibitors, statins, and ACE inhibitors may reduce the levels of these inflammatory markers and improve the non-invasive markers of subclinical atherosclerosis, the impact on cardiovascular risk resulting from these changes is unknown. The combination of an established inflammatory marker such as CRP or a vascular marker such as IMT with novel biochemical and vascular markers of cardiovascular disease may offer additive prognostic information for adverse outcome.

Serum level of macrophage colony-stimulating factor is increased in prostate cancer patients with bone metastasis

Recent evaluation of human prostate tissues has shown predominantly high expression of the macrophage colony-stimulating factor receptor in prostatic intra-epithelial neoplasia or prostate cancer. However, the expression of its ligand, the macrophage colony-stimulating factor (M-CSF), and the biological role of this signaling in prostate cancer has not been analyzed. In this research we determined the relationship of serum M-CSF level to clinical parameters of prostate cancer progression. We measured the serum level of M-CSF in 170 patients with histologically confirmed prostatic adenocarcinoma and in 54 patients in whom prostate cancer was not detected. We also investigated the M-CSF expression in prostate cancer tissues by immunohistochemistry. The serum levels of M-CSF in bone metastatic prostate cancer patients was significantly higher than those in non-metastatic patients, while M-CSF did not differ with regards to histological grade, Gleason score or local tumor progression. M-CSF expression was detected in prostate cancer cells themselves by immunohistochemistry. These results suggest that M-CSF may have a functional role in prostate cancer progression.

Circulating colony stimulating factor-1 and breast cancer risk

Colony stimulating factor-1 (CSF1) and its receptor (CSF1-R) are important in mammary gland development and have been implicated in breast carcinogenesis. In a nested case-control study in the Nurses' Heath Study of 726 breast cancer cases diagnosed between June 1, 1992, and June 1, 1998, and 734 matched controls, we prospectively evaluated whether circulating levels of CSF1 (assessed in 1989-1990) are associated with breast cancer risk. The association varied by menopausal status (P(heterogeneity) = 0.009). CSF1 levels in the highest quartile (versus lowest) were associated with an 85% reduced risk of premenopausal breast cancer [relative risk (RR), 0.15; 95% confidence interval (95% CI), 0.03-0.85; P(trend) = 0.02]. In contrast, CSF1 levels in the highest quartile conferred a 33% increased risk of postmenopausal breast cancer (RR, 1.33; 95% CI, 0.96-1.86; P(trend) = 0.11), with greatest risk for invasive (RR, 1.45; 95% CI, 1.02-2.07; P(trend) = 0.06) and ER+/PR+ tumors (RR, 1.72; 95% CI, 1.11-2.66; P(trend) = 0.04). Thus, the association of circulating CSF1 levels and breast cancer varies by menopausal status.

M-CSF-mediated macrophage differentiation but not proliferation is correlated with increased and prolonged ERK activation

M-CSF is a cytokine essential for both the proliferation and differentiation of monocytes/macrophages. In this study, we established a new M-CSF-mediated differentiation-inducing system, and examined how the level and duration of the activation of ERK preceded M-CSF-mediated differentiation. TF-1-fms human leukemia cells rapidly proliferated in response to M-CSF. However, in the presence of a phorbol ester, TPA, TF-1-fms cells definitely switched their responsiveness to M-CSF from proliferation to differentiation, as evidenced by a more drastic morphological change and the appearance of cells with a higher level of phagocytic activity. In TF-1-fms cells expressing HIV-1 Nef protein in a conditionally active-manner, both M-CSF-mediated proliferation and M-CSF/TPA-mediated differentiation were inhibited by the activation of Nef. The Nef-active cells showed perturbed patterns of ERK activation. Under the proliferation-inducing conditions (TPA-free), parental or Nef-inactive cells showed modest ERK activation following M-CSF stimulation, whereas Nef-active cells showed an earlier and transient ERK activation, despite a decrease in their proliferation rate. Under the differentiation-inducing conditions, parental or Nef-inactive cells showed increased and prolonged ERK activation following M-CSF stimulation, whereas Nef-active cells showed transient ERK activation. These results supported the idea that the increased and prolonged ERK activation led to M-CSF-mediated macrophage differentiation but not to proliferation.

Prognostic value of C-reactive protein, fibrinogen, interleukin-6, and macrophage colony stimulating factor in severe unstable angina

BACKGROUND

Inflammatory process plays an important role in the pathogenesis of acute coronary syndromes.

HYPOTHESIS

The study was undertaken to evaluate whether admission levels of C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6). and macrophage colony stimulating factor (MCSF) can predict short-term prognosis in patients with unstable angina.

METHODS

C-reactive protein, fibrinogen, IL-6, and MCSF were measured on admission in 141 consecutive patients, aged 59 +/- 10 years, with unstable angina (Braunwald class IIIb). Patients were divided into two groups according to their in-hospital outcome: Group 1 comprised 77 patients with a complicated course (2 died, 15 developed nonfatal myocardial infarction, and 60 had recurrence of angina), and Group 2 comprised 64 patients with an uneventful course.

RESULTS

Admission median levels of CRP (8.8 vs. 3.1 mg/l, p = 0.0002). fibrinogen (392 vs. 340 mg/dl, p = 0.008), IL-6 (8.8 vs. 4.5 pg/ml, p = 0.03), and MCSF (434 vs. 307 pg/ml, p = 0.0001) were higher in Group I than in Group 2. The MCSF levels were an independent risk factor for in-hospital events, with an adjusted odds ratio for eventful in-hospital outcome of 3.3 (95% confidence interval 1-10.9, p = 0.04), and correlated with levels of IL-6 (r(s) = 0.52, p = 0.0001), CRP (r(s) = 0.43, p = 0.0001), and fibrinogen (r(s) = 0.25, p = 0.004).

CONCLUSIONS

These findings suggest that among the studied inflammatory indices only increased admission levels of MCSF are strongly and independently related with adverse short-term prognosis in patients with severe unstable angina.

The Bacillus anthracis cholesterol-dependent cytolysin, Anthrolysin O, kills human neutrophils, monocytes and macrophages

BACKGROUND

Bacillus anthracis is an animal and human pathogen whose virulence is characterized by lethal and edema toxin, as well as a poly-glutamic acid capsule. In addition to these well characterized toxins, B. anthracis secretes several proteases and phospholipases, and a newly described toxin of the cholesterol-dependent cytolysin (CDC) family, Anthrolysin O (ALO).

RESULTS

In the present studies we show that recombinant ALO (rALO) or native ALO, secreted by viable B. anthracis, is lethal to human primary polymorphonuclear leukocytes (PMNs), monocytes, monocyte-derived macrophages (MDMs), lymphocytes, THP-1 monocytic human cell line and ME-180, Detroit 562, and A549 epithelial cells by trypan blue exclusion or lactate dehydrogenase (LDH) release viability assays. ALO cytotoxicity is dose and time dependent and susceptibility to ALO-mediated lysis differs between cell types. In addition, the viability of monocytes and hMDMs was assayed in the presence of vegetative Sterne strains 7702 (ALO+), UT231 (ALO-), and a complemented strain expressing ALO, UT231 (pUTE544), and was dependent upon the expression of ALO. Cytotoxicity of rALO is seen as low as 0.070 nM in the absence of serum. All direct cytotoxic activity is inhibited by the addition of cholesterol or serum concentration as low as 10%.

CONCLUSION

The lethality of rALO and native ALO on human monocytes, neutrophils, macrophages and lymphocytes supports the idea that ALO may represent a previously unidentified virulence factor of B. anthracis. The study of other factors produced by B. anthracis, along with the major anthrax toxins, will lead to a better understanding of this bacterium's pathogenesis, as well as provide information for the development of antitoxin vaccines for treating and preventing anthrax.

Langerhans cells arise from monocytes in vivo

Langerhans cells (LCs) are the only dendritic cells of the epidermis and constitute the first immunological barrier against pathogens and environmental insults. The factors regulating LC homeostasis remain elusive and the direct circulating LC precursor has not yet been identified in vivo. Here we report an absence of LCs in mice deficient in the receptor for colony-stimulating factor 1 (CSF-1) in steady-state conditions. Using bone marrow chimeric mice, we have established that CSF-1 receptor-deficient hematopoietic precursors failed to reconstitute the LC pool in inflamed skin. Furthermore, monocytes with high expression of the monocyte marker Gr-1 (also called Ly-6c/G) were specifically recruited to the inflamed skin, proliferated locally and differentiated into LCs. These results identify Gr-1(hi) monocytes as the direct precursors for LCs in vivo and establish the importance of the CSF-1 receptor in this process.

Developmental and functional significance of the CSF-1 proteoglycan chondroitin sulfate chain

The primary macrophage growth factor, colony-stimulating factor-1 (CSF-1), is homodimeric and exists in 3 biologically active isoforms: a membrane-spanning, cell-surface glycoprotein (csCSF-1) and secreted glycoprotein (sgCSF-1) and proteoglycan (spCSF-1) isoforms. To investigate the in vivo role of the chondroitin sulfate glycosaminoglycan (GAG) chain of spCSF-1, we created mice that exclusively express, in a normal tissue-specific and developmental manner, either the secreted precursor of spCSF-1 or the corresponding precursor in which the GAG addition site was mutated. The reproductive, hematopoietic tooth eruption and tissue macrophage defects of CSF-1-deficient, osteopetrotic Csf1(op)/Csf1(op) mice were corrected by transgenic expression of the precursors of either sgCSF-1 or spCSF-1. Furthermore, in contrast to the transgene encoding csCSF-1, both failed to completely correct growth retardation, suggesting a role for csCSF-1 in the regulation of body weight. However, spCSF-1, in contrast to sgCSF-1, completely resolved the osteopetrotic phenotype. Furthermore, in transgenic lines expressing different concentrations of sgCSF-1 or spCSF-1, spCSF-1 more efficiently corrected Csf1(op)/Csf1(op) defects of tooth eruption, eyelid opening, macrophage morphology, and B-cell deficiency than sgCSF-1. These results indicate an important role of the CSF-1 chondroitin sulfate proteoglycan in in vivo signaling by secreted CSF-1.

RON-regulated innate immunity is protective in an animal model of multiple sclerosis

The tyrosine kinase receptor RON and its ligand, macrophage stimulating protein (MSP), exert inhibitory effects on systemic innate immunity, but their CNS expression and impact on human neuroinflammatory diseases are unknown were RON and MSP present in human brain perivascular macrophages and microglia, but RON mRNA and protein abundance in the CNS were diminished in both MS patients and the MS animal model, experimental autoimmune encephalomyelitis (EAE). Treatment of differentiated human monocytoid cells with MSP resulted in significant reduction of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and MMP-9 mRNA levels, whereas minimal effects were observed in human astrocytes. After induction of EAE, RON knockout and heterozygote animals exhibited significantly increased CNS proinflammatory gene (TNF-alpha, MMP-12) expression compared with wild-type littermate controls, although IL-4 levels were suppressed in both RON-deficient groups. Neurological disease in RON-deficient animals showed a more rapid onset with overall worsened severity, together with exacerbated demyelination, axonal injury, and neuroinflammation after EAE induction. The proto-oncogene, c-Cbl, which modulates ubiquitylation of RON, was increased in glia in both MS brains and EAE spinal cords. Thus, the MSP-RON pathway represents a novel regulatory mechanism within the CNS by which innate immunity and its pathogenic effects could be targeted for future therapeutic interventions.

Increased circulating C-reactive protein and macrophage-colony stimulating factor are complementary predictors of long-term outcome in patients with chronic coronary artery disease

AIMS

We investigated, in a 6 year follow-up study, whether circulating levels of C-reactive protein (CRP) and macrophage colony stimulating factor (MCSF) have an independent or complementary prognostic value in patients with chronic coronary artery disease (CAD).

METHODS AND RESULTS

MCSF and CRP were measured in 100 patients with chronic CAD. Of 95 (33%) patients, 31 who completed the 6 year follow-up presented adverse events (death, myocardial infarction, and unstable angina). In multivariable analysis (including traditional risk factors and medications), the upper tertiles of MCSF (> or =814 pg/mL) and CRP (> or =2.5 mg/L) levels were independently associated with a 13- and 6-fold increase in risk of events, respectively (P<0.01). Patients with combined high CRP and MCSF had a higher absolute risk of events than patients with elevated MCSF or CRP alone (75 vs. 59 vs. 32%, respectively, P<0.01). The mean event-free time was 39, 64, and 52 months in patients with elevated MCSF, elevated CRP, and their combination, respectively.

CONCLUSION

In patients with chronic CAD, the prognostic value of MCSF is independent and complementary to that of CRP. MCSF is a particularly useful prognostic marker when CRP levels are low, but also provides additional information concerning risk and time-course of events in patients with elevated CRP.

Development of a quantitative, high-throughput cell-based enzyme-linked immunosorbent assay for detection of colony-stimulating factor-1 receptor tyrosine kinase inhibitors

Inhibitors of receptor tyrosine kinases are implicated as therapeutic agents for the treatment of many human diseases including cancer, inflammation and diabetes. Cell-based assays to examine inhibition of receptor tyrosine kinase mediated intracellular signaling are often laborious and not amenable to high-throughput cell-based screening of compound libraries. Here we describe the development of a nonradioactive, sandwich enzyme-linked immunosorbent assay (ELISA) to quantify the activation and inhibition of ligand-induced phosphorylation of the colony-stimulating factor-1 receptor (CSF-1R) in 96-well microtiter plate format. The assay involves the capture of the Triton X-100 solubilized human CSF-1R, from HEK293E cells overexpressing histidine epitope-tagged CSF-1R (CSF-1R/HEK293E), with immobilized CSF-1R antibody and detection of phosphosphorylation of the activated receptor with a phosphotyrosine specific antibody. The assay exhibited a 5-fold increase in phosphorylated CSF-1R signal from CSF-1R/HEK293E cells treated with colony-stimulating factor (CSF-1) relative to treated vector control cells. Additionally, using a histidine epitope-specific capture antibody, this method can also be adapted to quantify the phosphorylation state of any recombinantly expressed, histidine-tagged receptor tyrosine kinase. This method is a substantial improvement in throughput and quantitation of CSF-1R phosphorylation over conventional immunoblotting techniques.

Reduction of daily life ischaemia by aspirin in patients with angina: underlying link between thromboxane A2 and macrophage colony stimulating factor

OBJECTIVES

To evaluate whether aspirin reduces the incidence and frequency of daily life myocardial ischaemia in a cohort of patients with chronic stable coronary artery disease.

SETTING

Tertiary referral centre.

METHODS

60 patients with chronic stable coronary artery disease underwent 48 hour Holter monitoring to assess the incidence and frequency of daily life myocardial ischaemia. Those with myocardial ischaemia (40/60) entered a double blind, crossover trial of aspirin (300 mg/day for three weeks) versus placebo. After each treatment arm, 48 hour Holter monitoring was repeated and urinary thromboxane (Tx) B2, 11-dehydro-TxB2, plasma prothrombin fragment F1+2, macrophage colony stimulating factor (MCSF), and interleukin (IL)-6 were measured.

RESULTS

Aspirin reduced the total number and duration of ischaemic episodes from 339 to 251 and from 1765 to 1365 minutes, respectively (p < 0.01 for both). TxB2 was also reduced from 0.2 to 0.1 ng/mg creatinine, 11-dehydro-TxB2 from 3.3 to 1.3 ng/mg creatinine, F1+2 from 1.5 to 1.2 nmol/l, MCSF from 991 to 843 pg/ml, and IL-6 from 3.5 to 2.9 pg/ml (p < 0.05 for all). 11-dehydro-TxB2 excretion with and without aspirin was related to MCSF concentrations (p < 0.01), and the percentage reduction of MCSF by aspirin was related to the reduction of 11-dehydro-TxB2 (p < 0.05) and the reduction of the ischaemic burden compared with placebo (p < 0.05).

CONCLUSIONS

In patients with daily life ischaemia, aspirin reduces the incidence and frequency of ischaemic episodes as well as the systemic concentrations of haemostatic/inflammatory markers. Aspirin may prevent transient coronary flow reductions through platelet, thrombin, and cytokine inhibition.

Raised concentrations of macrophage colony stimulating factor in severe unstable angina beyond the acute phase are strongly predictive of long term outcome

OBJECTIVE

To evaluate the long term prognostic value of macrophage colony stimulating factor (MCSF), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNFalpha) measured in serum six weeks after the occurrence of unstable angina.

SUBJECTS

119 consecutive patients, mean (SD) age 58 (10) years, with severe unstable angina (Braunwald class IIIb); controls were 96 subjects of similar age and sex distribution.

DESIGN

MCSF, IL-6, and TNFalpha were measured on admission, at discharge, and six weeks later, and the patients were followed for two years. Clinical end points were: cardiac death, readmission for acute coronary syndromes, and revascularisation.

SETTING

District general hospital.

RESULTS

113 patients completed follow up, during which two died of non-cardiac causes. Of the remaining 111 patients, 39 (35.1%) had a cardiac event (two deaths, 15 revascularisations, and 22 readmissions for acute coronary syndromes). MCSF and IL-6 concentrations at six weeks were higher in patients with cardiac events than in those without (424 v 306 pg/ml, p = 0.0008, and 6.6 v 4.5 pg/ml, p = 0.01, respectively). Cytokine concentrations at six weeks were also significantly higher than in the control group. Logistic regression analysis showed that MCSF concentrations were the only independent predictors of future events, with an adjusted odds ratio for events of 4.1 (95% confidence interval 1.1 to 14.8; p = 0.03). The two year survival free of cardiac events was significantly lower in patients with MCSF concentrations in the highest tertile (values > or = 468 pg/ml) than in those with values < 468 pg/ml.

CONCLUSIONS

Increased MCSF concentrations beyond the acute phase are strongly predictive of long term outcome in patients with severe unstable angina.

Incomplete restoration of colony-stimulating factor 1 (CSF-1) function in CSF-1-deficient Csf1op/Csf1op mice by transgenic expression of cell surface CSF-1

The primary macrophage growth factor, colony-stimulating factor 1 (CSF-1), is expressed as a secreted glycoprotein or proteoglycan found in the circulation or as a biologically active cell surface glycoprotein (csCSF-1). To investigate the in vivo roles of csCSF-1, we created mice that exclusively express csCSF-1, in a normal tissue-specific and developmental manner, by transgenic expression of csCSF-1 in the CSF-1-deficient osteopetrotic (Csf1(op)/Csf1(op)) background. The gross defects of Csf1(op)/Csf1(op) mice, including growth retardation, failure of tooth eruption, and abnormal male and female reproductive functions were corrected. Macrophage densities in perinatal liver, bladder, sublinguinal salivary gland, kidney cortex, dermis, and synovial membrane were completely restored, whereas only partial or no restoration was achieved in adult liver, adrenal gland, kidney medulla, spleen, peritoneal cavity, and intestine. Residual osteopetrosis, significantly delayed trabecular bone resorption in the subepiphyseal region of the long bone, and incomplete correction of the hematologic abnormalities in the peripheral blood, bone marrow, and spleens of CSF-1-deficient mice were also found in mice exclusively expressing csCSF-1. These data suggest that although csCSF-1 alone is able to normalize several aspects of development in Csf1(op)/Csf1(op) mice, it cannot fully restore in vivo CSF-1 function, which requires the presence of the secreted glycoprotein and/or proteoglycan forms.

Expression of colony-stimulating factor 1 receptor during prostate development and prostate cancer progression

Colony-stimulating factor-1 receptor (CSF-1R) is the major regulator of macrophage development and is associated with epithelial cancers of the breast and ovary. Immunohistochemistry analysis of murine prostate development demonstrated epithelial expression of CSF-1R during the protrusion of prostatic buds from the urogenital sinus, during the prepubertal and androgen-driven proliferative expansion and branching of the gland, with a decline in older animals. Models of murine prostate cancer showed CSF-1R expression in areas of carcinoma- and tumor-associated macrophages. Several human prostate cancer cell lines and primary cultures of human prostate epithelial cells had low but detectable levels of CSF-1R. Human prostatectomy samples showed low or undetectable levels of receptor in normal glands or benign prostatic hypertrophy specimens. Staining was strongest in areas of prostatic intraepithelial neoplasia or carcinoma of Gleason histological grade 3 or 4. The activated form of the receptor reactive with antibodies specific for phosphotyrosine modified peptide sequences was observed in samples of metastatic prostate cancer. Immunohistochemistry showed strong expression of CSF-1R by macrophage lineage cells, including villous macrophages and the syncytiotrophoblast layer of placenta, Kupper cells in the liver, and histiocytes infiltrating near prostate cancers. These observations correlate CSF-1R expression with changes in the growth and development of the normal and neoplastic prostate.

Autoantibodies against granulocyte macrophage colony-stimulating factor are diagnostic for pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of phospholipids and surfactant proteins in the lung. The central role for granulocyte-macrophage colony-stimulating factor (GM-CSF) in surfactant homeostasis has been established in mice lacking the GM-CSF gene, which results in murine pulmonary alveolar proteinosis. No GM-CSF gene defect has been defined in adult patients with idiopathic PAP. Previous studies indicated that the human disease differs from the murine model by the presence of circulating, neutralizing autoantibodies against GM-CSF. Therefore, the final common pathway between the GM-CSF knockout and human PAP appears to be the deficiency of functionally active GM-CSF. In the present study, all patients with idiopathic PAP were found to have systemic and localized antibodies against GM-CSF. Anti-GM-CSF titers were a specific and sensitive marker for PAP. In addition, we present data showing that the absence of active GM-CSF is associated with enhanced levels of macrophage colony-stimulating factor, monocyte chemoattractant protein-1, and interleukin-8. These studies confirm and strengthen previous studies and support the concept that adult idiopathic PAP is an autoimmune disease defined by the presence of anti-GM-CSF. Further, using anti-GM-CSF as an indicator of pulmonary alveolar proteinosis may avoid the use of more invasive means of evaluating patients with pulmonary disease characterized by alveolar infiltrates.

Transcription factor complex formation and chromatin fine structure alterations at the murine c-fms (CSF-1 receptor) locus during maturation of myeloid precursor cells

Expression of the gene for the macrophage colony stimulating factor receptor (CSF-1R), c-fms, has been viewed as a hallmark of the commitment of multipotent precursor cells to macrophages. Lineage-restricted expression of the gene is controlled by conserved elements in the proximal promoter and within the first intron. To investigate the developmental regulation of c-fms at the level of chromatin structure, we developed an in vitro system to examine the maturation of multipotent myeloid precursor cells into mature macrophages. The dynamics of chromatin fine structure alterations and transcription factor occupancy at the c-fms promoter and intronic enhancer was examined by in vivo DMS and UV-footprinting. We show that the c-fms gene is already transcribed at low levels in early myeloid precursors on which no CSF-1R surface expression can be detected. At this stage of myelopoiesis, the formation of transcription factor complexes on the promoter was complete. By contrast, occupancy of the enhancer was acutely regulated during macrophage differentiation. Our data show that cell-intrinsic differentiation decisions at the c-fms locus precede the appearance of c-fms on the cell surface. They also suggest that complex lineage-specific enhancers such as the c-fms intronic enhancer regulate local chromatin structure through the coordinated assembly and disassembly of distinct transcription factor complexes.

The macrophage growth factor CSF-1 in mammary gland development and tumor progression

Colony stimulating factor 1 (CSF-1), a major regulator of the mononuclear phagocytic lineage, is expressed in more than 70% of human breast cancers and its expression is correlated with poor prognosis. Studies of CSF-1 null mutant mice demonstrated that CSF-1 plays an important role in normal mammary ductal development as well as in mammary tumor progression to metastasis. CSF-1 regulates these processes through the recruitment and regulation of macrophages, cells that become associated with mammary tumors and the terminal end buds at the end of the growing ducts. This phenomenon suggests that the tumors subvert normal developmental processes to allow invasion into the surrounding stroma, a process that gives the tumor access to the vasculature and consequently the promotion of metastasis. In addition, soluble CSF-1 secreted from the tumor acts to divert antitumor macrophage responses and suppresses the differentiation of mature tumor-antigen-presenting dendritic cell This review discusses these observations in detail and attempts to fit them into a larger picture of CSF-1 and macrophage action in the regulation of normal mammary gland development and tumor progression.

Requirement of macrophages and eosinophils and their cytokines/chemokines for mammary gland development

Epithelial/mesenchymal cell interactions are necessary for proper ductal morphogenesis throughout all stages of mammary gland development. Besides the well-established stromal components, such as adipocytes and fibroblasts, the mammary stroma is also infiltrated with migrating blood cells, mostly macrophages and eosinophils. The focus of this review is on the role of macrophages and their growth factor colony-stimulating factor 1 (CSF-1) in promoting branching morphogenesis during postnatal mammary gland development through to lactation. The more restricted role of eosinophils and their chemoattractant eotaxin during pubertal ductal morphogenesis is also discussed. A possible interaction between macrophages and eosinophils in ductal morphogenesis is considered, along with the roles of other chemokines. This role of macrophages in normal development also appears to be subverted by tumors of the mammary gland to promote the escape of the tumor cells from the local environment and enhance their rate of metastasis. These data emphasize the dual role of macrophages in the promotion of epithelial growth in normal and cancer states.

Interleukin-10 contributes development of macrophage suppressor activities by macrophage colony-stimulating factor, but not by granulocyte-macrophage colony-stimulating factor

Macrophages are known to possess suppressor activities in immune responses. To determine the effects of GM-CSF and M-CSF on the expression of macrophage suppressor activities, monocyte-derived macrophages cultured with GM-CSF (GM-Mphis) were compared with those cultured with M-CSF (M-Mphis) for antigen-specific proliferation and interferon-gamma (IFN-gamma) production by lymphocytes. Both GM-Mphis and M-Mphis equally suppressed lymphocyte proliferation, but only M-Mphis suppressed IFN-gamma production in response to purified protein derivative (PPD). M-Mphis, but not GM-Mphis, released IL-10 not only in the course of macrophage differentiation but also in response to PPD after maturation to macrophages. From the results that (i) exogenous IL-10 suppressed IFN-gamma production, but not proliferation of lymphocytes, and that (ii) neutralizing antibody to IL-10 reversed suppressor activities of M-Mphis on IFN-gamma production, but not lymphocyte proliferation, it appeared that IL-10 was the major factor responsible for suppression of IFN-gamma production. Thus, these results suggest that only M-CSF augments IL-10-dependent suppressor activity of macrophages on IFN-gamma production and that both GM-CSF and M-CSF induce IL-10-independent macrophage suppressor activity on lymphocyte proliferation.

Monoclonal antibodies to vascular endothelial growth factor (VEGF) and the VEGF receptor, FLT-1, inhibit the growth of C6 glioma in a mouse xenograft

Monoclonal antibodies raised to peptide sequences of vascular endothelial growth factor (VEGF) and the VEGF receptor, FLT-1, inhibited the growth of C6 tumors growing subcutaneously in nude mice. Immunohistochemical analysis demonstrated antibody targeting of blood vessels, tumor cells, and macrophages. A control antibody demonstrated no growth inhibition or tumor uptake. An antibody to FLT- I impaired microvascular maturation and diminished the accumulation of tumor infiltrating macrophages. The antibodies demonstrated affinity for microvasculature and tumor cells in immunohistochemistry of human glioblastoma multiforme. Targeting VEGF and its receptors has potential in the treatment of tumors of the central nervous system. FLT-1 presents an attractive target due to its presence on multiple cell types.

An alternative open reading frame of the human macrophage colony-stimulating factor gene is independently translated and codes for an antigenic peptide of 14 amino acids recognized by tumor-infiltrating CD8 T lymphocytes

We show that cytotoxic T lymphocytes (CTLs) infiltrating a kidney tumor recognize a peptide encoded by an alternative open reading frame (ORF) of the macrophage colony-stimulating factor (M-CSF) gene. Remarkably, this alternative ORF, which is translated in many tumors concurrently with the major ORF, is also translated in some tissues that do not produce M-CSF, such as liver and kidney. Such a dissociation of the translation of two overlapping ORFs from the same gene is unexpected. The antigenic peptide encoded by the alternative ORF is presented by human histocompatibility leukocyte antigen (HLA)-B*3501 and has a length of 14 residues. Peptide elution indicated that tumor cells naturally present this 14 mer, which is the longest peptide known to be recognized by CTLs. Binding studies of peptide analogues suggest that it binds by its two extremities and bulges out of the HLA groove to compensate for its length.

Both src-dependent and -independent mechanisms mediate phosphatidylinositol 3-kinase regulation of colony-stimulating factor 1-activated mitogen-activated protein kinases in myeloid progenitors

Colony-stimulating factor 1 (CSF-1) supports the proliferation, survival, and differentiation of bone marrow-derived cells of the monocytic lineage. In the myeloid progenitor 32D cell line expressing CSF-1 receptor (CSF-1R), CSF-1 activation of the extracellular signal-regulated kinase (ERK) pathway is both Ras and phosphatidylinositol 3-kinase (PI3-kinase) dependent. PI3-kinase inhibition did not influence events leading to Ras activation. Using the activity of the PI3-kinase effector, Akt, as readout, studies with dominant-negative and oncogenic Ras failed to place PI3-kinase downstream of Ras. Thus, PI3-kinase appears to act in parallel to Ras. PI3-kinase inhibitors enhanced CSF-1-stimulated A-Raf and c-Raf-1 activities, and dominant-negative A-Raf but not dominant-negative c-Raf-1 reduced CSF-1-provoked ERK activation, suggesting that A-Raf mediates a part of the stimulatory signal from Ras to MEK/ERK, acting in parallel to PI3-kinase. Unexpectedly, a CSF-1R lacking the PI3-kinase binding site (DeltaKI) remained capable of activating MEK/ERK in a PI3-kinase-dependent manner. To determine if Src family kinases (SFKs) are involved, we demonstrated that CSF-1 activated Fyn and Lyn in cells expressing wild-type (WT) or DeltaKI receptors. Moreover, CSF-1-induced Akt activity in cells expressing DeltaKI is SFK dependent since Akt activation was prevented by pharmacological or genetic inhibition of SFK activity. The docking protein Gab2 may link SFK to PI3-kinase. CSF-1 induced Gab2 tyrosyl phosphorylation and association with PI3-kinase in cells expressing WT or DeltaKI receptors. However, only in DeltaKI cells are these events prevented by PP1. Thus in myeloid progenitors, CSF-1 can activate the PI3-kinase/Akt pathway by at least two mechanisms, one involving direct receptor binding and one involving SFKs.

The role of integrins in reproduction

Fertilization, implantation, and placentation are dynamic cellular events that require not only synchrony between the maternal environment and the embryo, but also complex cell-to-cell communication. This communication involves integrins, a large family of proteins involved in the attachment, migration, invasion, and control of cellular function. Over the past decade, investigators have learned that integrins participate in multiple reproductive events including fertilization, implantation, and placentation in many species. This review will describe: (i) the expression of integrins on gametes and during the establishment and development of the placenta; (ii) regulatory pathways for controlling expression of integrins in the uterus and developing placenta; (iii) the function of integrins as determined by null-mutations; and (iv) reproductive dysfunction in women related to inappropriate integrin expression in the uterus and/or placenta.