Macrophage specificity of three anti-CD68 monoclonal antibodies (KP1, EBM11, and PGM1) widely used for immunohistochemistry and flow cytometry

Forced Hepatic Overexpression of CEACAM1 Curtails Diet-Induced Insulin Resistance

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates insulin sensitivity by promoting hepatic insulin clearance. Liver-specific inactivation or global null-mutation of Ceacam1 impairs hepatic insulin extraction to cause chronic hyperinsulinemia, resulting in insulin resistance and visceral obesity. In this study we investigated whether diet-induced insulin resistance implicates changes in hepatic CEACAM1. We report that feeding C57/BL6J mice a high-fat diet reduced hepatic CEACAM1 levels by >50% beginning at 21 days, causing hyperinsulinemia, insulin resistance, and elevation in hepatic triacylglycerol content. Conversely, liver-specific inducible CEACAM1 expression prevented hyperinsulinemia and markedly limited insulin resistance and hepatic lipid accumulation that were induced by prolonged high-fat intake. This was partly mediated by increased hepatic β-fatty acid oxidation and energy expenditure. The data demonstrate that the high-fat diet reduced hepatic CEACAM1 expression and that overexpressing CEACAM1 in liver curtailed diet-induced metabolic abnormalities by protecting hepatic insulin clearance.

The human cytomegalovirus lytic cycle is induced by 1,25-dihydroxyvitamin D3 in peripheral blood monocytes and in the THP-1 monocytic cell line

Human cytomegalovirus (HCMV) resides in a latent form in hematopoietic progenitors and undifferentiated cells within the myeloid lineage. Maturation and differentiation along the myeloid lineage triggers lytic replication. Here, we used peripheral blood monocytes and the monocytic cell line THP-1 to investigate the effects of 1,25-dihydroxyvitamin D3 on HCMV replication. Interestingly, 1,25-dihydroxyvitamin D3 induces lytic replication marked by upregulation of HCMV gene expression and production of infectious virus. Moreover, we demonstrate that the effects of 1,25-dihydroxyvitamin D3 correlate with maturation/differentiation of the monocytes and not by directly stimulating the MIEP. These results are somewhat surprising as 1,25-dihydroxyvitamin D3 typically boosts immunity to bacteria and viruses rather than driving the infectious life cycle as it does for HCMV. Defining the signaling pathways kindled by 1,25-dihydroxyvitamin D3 will lead to a better understanding of the underlying molecular mechanisms that determine the fate of HCMV once it infects cells in the myeloid lineage.

CD68 expression is a discriminative feature of indolent cutaneous CD8-positive lymphoid proliferation and distinguishes this lymphoma subtype from other CD8-positive cutaneous lymphomas

BACKGROUND

Indolent cutaneous CD8+ lymphoid proliferation is a recently described rare entity among cutaneous T-cell lymphomas that typically presents with solitary skin lesions at acral sites. Separation from otherwise aggressive T-cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental to avoid unnecessary harmful treatment. However, up to now, no reliable discriminative marker has been identified.

OBJECTIVES

Motivated by these diagnostic quandaries, we have analyzed a large series of archived formalin-fixed paraffin-embedded (FFPE) specimens of atypical CD8+ cutaneous infiltrates with clear-cut diagnosis and clinical follow-up (n = 44) including five cases of indolent CD8+ lymphoid proliferation by using immunohistochemistry with the aim of obtaining markers predictive of subtype assignment.

RESULTS

We identified exclusive expression of CD68 by lymphoma cells within the subgroup of indolent CD8+ lymphoid proliferation (5/5 cases). Specific CD68 expression in this entity was confirmed by the application of several monoclonal antibodies (KP1, PG-M1, KiM1P) against the CD68 molecule available for FFPE tissue. In contrast, none of the infiltrates of the other CD8+ cutaneous lymphoma entities stained positive for CD68 (0/39).

CONCLUSIONS

Based on these observations, we suggest CD68 as a new discriminative marker which is helpful in distinguishing indolent CD8+ lymphoid proliferation from other CD8+ cutaneous lymphomas in ambiguous cases.

Advances in pathology of diabetes from pancreatic islets to neuropathy--a tribute to Paul Langerhans

There emerges a world epidemic of diabetes, afflicting over 3.8 billion people globally. The socio-economic burden of this disorder is tremendous and there is an urgent need to solve the problems incurred from this disorder and to establish an efficient way of prevention and treatment. Fundamental pathology of diabetes has been too diverse to reach a simple etiology and the mechanisms of how the lesions specific to diabetes develop are yet to be clear. Nevertheless, there has been slow but significant advancement in the understanding of the disease based on characterization of the salient features of pathological lesions in human diabetic subjects. Progressive decline of islet β cells associated with increased α cell volume density was found to account for clinical manifestation of hypoinsulinemia and hyperglucagonemia in type 2 diabetes. Concurrently, signs of complications represented by distal nerve fiber loss in the skin commences from the beginning of this disease. Thus the pathological studies disclosed the major attributes in this disorder targeting the islet of pancreas and epidermal nerve, both of which were discovered by Paul Langerhans more than 140 years ago. In this review, I attempt to summarize the progress in pathology of diabetes which Langerhans opened this field.

The immunophenotype of antigen presenting cells of the mononuclear phagocyte system in normal human liver--a systematic review

The mononuclear phagocytic system (MPS), comprised of monocytes, macrophages, and dendritic cells, is essential in tissue homeostasis and in determining the balance of the immune response through its role in antigen presentation. It has been identified as a therapeutic target in infectious disease, cancer, autoimmune disease and transplant rejection. Here, we review the current understanding of the immunophenotype and function of the MPS in normal human liver. Using well-defined selection criteria, a search of MEDLINE and EMBASE databases identified 76 appropriate studies. The majority (n=67) described Kupffer cells (KCs), although the definition of KC differs between sources, and little data were available regarding their function. Only 10 papers looked at liver dendritic cells (DCs), and largely confirmed the presence of the major dendritic cell subsets identified in human blood. Monocytes were thoroughly characterized in four studies that utilized flow cytometry and fluorescent microscopy and highlighted their prominent role in liver homeostasis and displayed subtle differences from circulating monocytes. There was some limited evidence that liver DCs are tolerogenic but neither liver dendritic cell subsets nor macrophages have been thoroughly characterized, using either multi-colour flow cytometry or multi-parameter fluorescence microscopy. The lobular distribution of different subsets of liver MPS cells was also poorly described, and the ability to distinguish between passenger leukocytes and tissue resident cells remains limited. It was apparent that further research, using modern immunological techniques, is now required to accurately characterize the cells of the MPS in human liver.

Expression of choline and acetylcholine transporters in synovial tissue and cartilage of patients with rheumatoid arthritis and osteoarthritis

Increasing evidence is showing that the non-neuronal cholinergic system plays an important role in the pathology of rheumatoid arthritis (RA). Choline transport into the cell is the rate-limiting step for the synthesis of acetylcholine (ACh), which can be released directly or in vesicles from the cell. However, in the human joint little is known about choline import or the release of ACh from the cell. Thus, we analyze the expression of members of the organic cation transporter (OCT), of the newly discovered choline transporter-like (CTL) family and of classical neuronal components such as the high-affinity choline transporter (CHT1) and the vesicular ACh transporter (VAChT) in the synovium and cartilage of the human hip joint from patients with osteoarthritis (OA) and RA. OCT1, OCT3 and OCTN1 and all members of the CTL family were expressed in synovial and cartilage samples. The expression of CTL1 and CTL2 was localized in synovial macrophages and fibroblasts. CHT1 mRNA expression was detectable only in the synovium, whereas VAChT was completely absent in all samples. Therefore, in the human joint, choline transport into the cell and the release of ACh seems to be mediated mainly by members of the OCT and CTL family. Expression of transporters appears not to be influenced by the pathological state, as no differences have been detected between joints from OA or RA patients. Importantly, however, all necessary components for choline import and the release of non-neuronal ACh are present in the human joint.

Impairment of high-density lipoprotein resistance to lipid peroxidation and adipose tissue inflammation in obesity complicated by obstructive sleep apnea

CONTEXT

Obstructive sleep apnea (OSA) complicates morbid obesity and is associated with increased cardiovascular disease incidence. An increase in the circulating markers of chronic inflammation and dysfunctional high-density lipoprotein (HDL) occur in severe obesity.

OBJECTIVE

The objective of the study was to establish whether the effects of obesity on inflammation and HDL dysfunction are more marked when complicated by OSA.

DESIGN AND PATIENTS

Morbidly obese patients (n = 41) were divided into those whose apnea-hypoapnea index (AHI) was more or less than the median value and on the presence of OSA [OSA and no OSA (nOSA) groups]. We studied the antioxidant function of HDL and measured serum paraoxonase 1 (PON1) activity, TNFα, and intercellular adhesion molecule 1 (ICAM-1) levels in these patients. In a subset of 19 patients, we immunostained gluteal sc adipose tissue (SAT) for TNFα, macrophages, and measured adipocyte size.

RESULTS

HDL lipid peroxide levels were higher and serum PON1 activity was lower in the high AHI group vs the low AHI group (P < .05 and P < .0001, respectively) and in the OSA group vs the nOSA group (P = .005 and P < .05, respectively). Serum TNFα and ICAM-1 levels and TNFα immunostaining in SAT increased with the severity of OSA. Serum PON1 activity was inversely correlated with AHI (r = -0.41, P < .03) in the OSA group. TNFα expression in SAT directly correlated with AHI (r = 0.53, P < .03) in the subset of 19 patients from whom a biopsy was obtained.

CONCLUSION

Increased serum TNFα, ICAM-1, and TNFα expression in SAT provide a mechanistic basis for enhanced inflammation in patients with OSA. Decreased serum PON1 activity, impaired HDL antioxidant function, and increased adipose tissue inflammation in these patients could be a mechanism for HDL and endothelial dysfunction.

Association of low numbers of CD206-positive cells with loss of ICC in the gastric body of patients with diabetic gastroparesis

BACKGROUND

There is increasing evidence for specific cellular changes in the stomach of patients with diabetic (DG) and idiopathic (IG) gastroparesis. The most significant findings are loss of interstitial cells of Cajal (ICC), neuronal abnormalities, and an immune cellular infiltrate. Studies done in diabetic mice have shown a cytoprotective effect of CD206+ M2 macrophages. To quantify overall immune cellular infiltrate, identify macrophage populations, and quantify CD206+ and iNOS+ cells. To investigate associations between cellular phenotypes and ICC.

METHODS

Full thickness gastric body biopsies were obtained from non-diabetic controls (C), diabetic controls (DC), DG, and IG patients. Sections were labeled for CD45, CD206, Kit, iNOS, and putative human macrophage markers (HAM56, CD68, and EMR1). Immunoreactive cells were quantified from the circular muscle layer.

KEY RESULTS

Significantly fewer ICC were detected in DG and IG tissues, but there were no differences in the numbers of cells immunoreactive for other markers between patient groups. There was a significant correlation between the number of CD206+ cells and ICC in DG and DC patients, but not in C and IG and a significant correlation between iNOS+ cells and ICC in the DC group, but not the other groups. CD68 and HAM56 reliably labeled the same cell populations, but EMR1 labeled other cell types.

CONCLUSIONS & INFERENCES

Depletion of ICC and correlation with changes in CD206+ cell numbers in DC and DG patients suggests that in humans, like mice, CD206+ macrophages may play a cytoprotective role in diabetes. These findings may lead to novel therapeutic options, targeting alternatively activated macrophages.

Islet amyloid with macrophage migration correlates with augmented β-cell deficits in type 2 diabetic patients

AIMS

Islet amyloid is a hallmark in type 2 diabetic subjects, but its implication in clinical features and development of islet pathology is still unclear.

METHODS

From 118 autopsy cases with type 2 diabetes, 26 cases with islet amyloid deposition (DA+) were selected. Twenty diabetic subjects without obvious amyloid deposition (DA-) matched for the age and diabetes duration and 20 non-diabetic subjects (ND) served for comparison. We examined the severity of amyloid deposition and its relationships with population of endocrine cells, expression of cell damage markers or macrophage infiltration. Correlation of clinical profile with islet pathology was also sought on the subset of the investigated patients.

RESULTS

β-Cell volume density was nearly 40% less in DA+ and 20% less in DA- when compared to ND. Severity of amyloid deposition correlated with reduced volume densities of β-cell and α-cell, and increased body mass index (BMI), but not with duration of diabetes, age or HbA1c. Amyloid-rich islets contained an increased number of macrophages mixed with β-cells with oxidative stress-related DNA damage, characterized by γH2AX expression, and suppressed (pro)insulin mRNA expression.

CONCLUSIONS

In Japanese type 2 diabetic patients, islet amyloid was more common with severe β-cell loss and high BMI, associated with macrophage infiltration.

Effects of CD14 macrophages and proinflammatory cytokines on chondrogenesis in osteoarthritic synovium-derived stem cells

We investigated the effects of CD14 macrophages and proinflammatory cytokines on chondrogenic differentiation of osteoarthritic synovium-derived stem cells (SDSCs). Osteoarthritic synovial fluid was analyzed for interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Levels of stem cell surface markers in osteoarthritic SDSCs were evaluated using flow cytometry. CD14-negative cells were obtained using magnetically activated cell sorting. We compared chondrogenic potentials between whole cells and CD14-negative cells in CD14(low) cells and CD14(high) cells, respectively. To assess whether nuclear factor-κB (NF-κB) and CCAAT/enhancer-binding protein β (C/EBPβ) modulate IL-1β-induced alterations in chondrogenic potential, we performed small interfering RNA transfection. We observed a significant correlation between the CD14 ratio in osteoarthritic SDSCs and IL-1β and TNF-α in osteoarthritic synovial fluid. Phenotypic characterization of whole cells and CD14-negative cells showed no significant differences in levels of stem cell markers. mRNA expression of type II collagen was higher in CD14-negative cell pellets than in whole cell pellets. Immunohistochemical staining indicated higher levels of type II collagen in the CD14-negative cell pellets of CD14(high) cells than in whole cell pellets of CD14(high) cells. As expected, IL-1β and TNF-α significantly inhibited the expression of chondrogenic-related genes in SDSCs, an effect which was antagonized by knockdown of NF-κB and C/EBPβ. Our results suggest that depletion of CD14(+) synovial macrophages leads to improved chondrogenic potential in CD14(high) cell populations in osteoarthritic SDSCs, and that NF-κB (RelA) and C/EBPβ are critical factors mediating IL-1β-induced suppression of the chondrogenic potential of human SDSCs.

Anti-oxidant and anti-apoptotic effects of luteolin on mice peritoneal macrophages stimulated by angiotensin II

PURPOSE

Luteolin, a plant flavonoid, can be found in a variety of plants and possesses anti-tumorigenic, anti-mutagenic, anti-oxidant and anti-inflammatory properties. However, the protective effects of luteolin on mice peritoneal macrophages stimulated by Angiotensin II (Ang II) have not been fully elucidated.

METHODS AND RESULTS

Mice peritoneal macrophages were confirmed to be strongly positive for the macrophage marker CD68. Cell viability was tested after cells were pretreated with different concentrations of luteolin (6.25, 12.5 and 25μM) and stimulated by Ang II. Luteolin not only significantly increased the viability of macrophages in the presence of Ang II, but also decreased the apoptotic rate, up-regulated Bcl-2 expression, and down-regulated Bax expression, thereby raising the ratio of Bcl-2 to Bax. In addition, luteolin pretreatment significantly increased the activity of SOD and reduced the levels of malondialdehyde (MDA), which was up-regulated in the presence of Ang II. This protective effect was also seen with Vitamin E (VitE) pretreatment, which was used as a standard control in this study.

CONCLUSIONS

These data clearly demonstrate that luteolin suppresses Ang II-directed oxidative stress and apoptosis on mice peritoneal macrophages.

Lutheran/basal cell adhesion molecule accelerates progression of crescentic glomerulonephritis in mice

Migration of circulating leukocytes from the vasculature into the surrounding tissue is an important component of the inflammatory response. Among the cell surface molecules identified as contributing to leukocyte extravasation is VCAM-1, expressed on activated vascular endothelium, which participates in all stages of leukocyte–endothelial interaction by binding to leukocyte surface expressed integrin VLA-4. However, not all VLA-4-mediated events can be linked to VCAM-1. A novel interaction between VLA-4 and endothelial Lutheran (Lu) blood group antigens and basal cell adhesion molecule (BCAM) proteins has been recently shown, suggesting that Lu/BCAM may have a role in leukocyte recruitments in inflamed tissues. Here, we assessed the participation of Lu/BCAM in the immunopathogenesis of crescentic glomerulonephritis. High expression of Lu/BCAM in glomeruli of mice with rapidly progressive glomerulonephritis suggests a potential role for the local expression of Lu/BCAM in nephritogenic recruitment of leukocytes. Genetic deficiency of Lu/BCAM attenuated glomerular accumulation of T cells and macrophages, crescent formation, and proteinuria, correlating with reduced fibrin and platelet deposition in glomeruli. Furthermore, we found a pro-adhesive interaction between human monocyte α4β1 integrin and Lu/BCAM proteins. Thus, Lu/BCAM may have a critical role in facilitating the accumulation of monocytes and macrophages, thereby exacerbating renal injury.

Osteal macrophages support physiologic skeletal remodeling and anabolic actions of parathyroid hormone in bone

Cellular subpopulations in the bone marrow play distinct and unexplored functions in skeletal homeostasis. This study delineated a unique role of osteal macrophages in bone and parathyroid hormone (PTH)-dependent bone anabolism using murine models of targeted myeloid-lineage cell ablation. Depletion of c-fms(+) myeloid lineage cells [via administration of AP20187 in the macrophage Fas-induced apoptosis (MAFIA) mouse model] reduced cortical and trabecular bone mass and attenuated PTH-induced trabecular bone anabolism, supporting the positive function of macrophages in bone homeostasis. Interestingly, using a clodronate liposome model with targeted depletion of mature phagocytic macrophages an opposite effect was found with increased trabecular bone mass and increased PTH-induced anabolism. Apoptotic cells were more numerous in MAFIA versus clodronate-treated mice and flow cytometric analyses of myeloid lineage cells in the bone marrow showed that MAFIA mice had reduced CD68(+) cells, whereas clodronate liposome-treated mice had increased CD68(+) and CD163(+) cells. Clodronate liposomes increased efferocytosis (clearance of apoptotic cells) and gene expression associated with alternatively activated M2 macrophages as well as expression of genes associated with bone formation including Wnt3a, Wnt10b, and Tgfb1. Taken together, depletion of early lineage macrophages resulted in osteopenia with blunted effects of PTH anabolic actions, whereas depletion of differentiated macrophages promoted apoptotic cell clearance and transformed the bone marrow to an osteogenic environment with enhanced PTH anabolism. These data highlight a unique function for osteal macrophages in skeletal homeostasis.

Human and mouse neuroinflammation markers in Niemann-Pick disease, type C1

Niemann-Pick disease, type C1 (NPC1) is an autosomal recessive lipid storage disorder in which a pathological cascade, including neuroinflammation occurs. While data demonstrating neuroinflammation is prevalent in mouse models, data from NPC1 patients is lacking. The current study focuses on identifying potential markers of neuroinflammation in NPC1 from both the Npc1 mouse model and NPC1 patients. We identified in the mouse model significant changes in expression of genes associated with inflammation and compared these results to the pattern of expression in human cortex and cerebellar tissue. From gene expression array analysis, complement 3 (C3) was increased in mouse and human post-mortem NPC1 brain tissues. We also characterized protein levels of inflammatory markers in cerebrospinal fluid (CSF) from NPC1 patients and controls. We found increased levels of interleukin 3, chemokine (C-X-C motif) ligand 5, interleukin 16 and chemokine ligand 3 (CCL3), and decreased levels of interleukin 4, 10, 13 and 12p40 in CSF from NPC1 patients. CSF markers were evaluated with respect to phenotypic severity. Miglustat treatment in NPC1 patients slightly decreased IL-3, IL-10 and IL-13 CSF levels; however, further studies are needed to establish a strong effect of miglustat on inflammation markers. The identification of inflammatory markers with altered levels in the cerebrospinal fluid of NPC1 patients may provide a means to follow secondary events in NPC1 disease during therapeutic trials.

Macrophages accumulate in the gut mucosa of untreated HIV-infected patients

BACKGROUND

Mucosal macrophages are involved in the maintenance of epithelial barrier integrity and the elimination of invading pathogens. Although an intestinal barrier defect and microbial translocation are hallmarks of human immunodeficiency virus (HIV) infection, recent data on gut mucosal macrophages in HIV infection are sparse.

METHODS

Treatment-naive and treated HIV-infected patients and healthy controls were studied for frequencies and functional parameters of blood monocytes and macrophages in duodenal mucosa.

RESULTS

We found mucosal enrichment of macrophages in untreated HIV infection associated with reduced monocyte counts in blood and increased monocyte expression of the gut-homing molecule integrin β7. Increased CCR2 density on integrin β7-expressing monocytes and mucosal secretion of CCL2 suggest that CCR2/CCL2-chemotaxis is involved in enhanced trafficking of blood monocytes to the gut. Secretion of macrophage-related proinflammatory molecules interleukin 1β, CCL5, CXCL9, and CXCL10 was increased in the gut mucosa of untreated patients. Moreover, mucosal macrophages of untreated patients showed reduced phagocytic activity.

CONCLUSIONS

These data suggest a role for gut mucosal macrophages in HIV immune pathogenesis: infiltrated macrophages in the intestinal mucosa may promote local inflammation and tissue injury, whereas their low phagocytic activity prevents the efficient elimination of luminal antigens that cross the damaged intestinal barrier.

Ultrathin sP(EO-stat-PO) hydrogel coatings are biocompatible and preserve functionality of surface bound growth factors in vivo

Hydrogel coatings prepared from reactive star shaped polyethylene oxide based prepolymers (NCO-sP(EO-stat-PO)) minimize unspecific protein adsorption in vitro, while proteins immobilized on NCO-sP(EO-stat-PO) coatings retain their structure and biological function. The aim of the present study was to assess biocompatibility and the effect on early osseointegrative properties of a NCO-sP(EO-stat-PO) coating with additional RGD-peptides and augmentation with bone morphogenetic protein-4 (BMP) used on a medical grade high-density polyethylene (HDPE) base under in vivo circumstances. For testing of biocompatibility dishes with large amounts of bulk NCO-sP(EO-stat-PO) were implanted subcutaneously into 14 Wistar rats. In a second set-up functionalization of implants with ultrathin surface layers by coating ammonia-plasma treated HDPE with NCO-sP(EO-stat-PO), functionalization with linear RGD-peptides, and augmentation with RGD and BMP-4 was analyzed. Therefore, implants were placed subcutaneously in the paravertebral tissue and transcortically in the distal femur of another 14 Wistar rats. Both tests revealed no signs of enhanced inflammation of the surrounding tissue analyzed by CD68, IL-1ß-/TNF-α-antibody staining, nor systemic toxic reactions according to histological analysis of various organs. The mean thickness of the fibrous tissue surrounding the femoral implants was highest in native HDPE-implants and tended to be lower in all NCO-sP(EO-stat-PO) modified implants. Micro-CT analysis revealed a significant increase of peri-implant bone volume in RGD/BMP-4 coated samples. These results demonstrate that even very low amounts of surface bound growth factors do have significant effects when immobilized in an environment that retains their biological function. Hence, NCO-sP(EO-stat-PO)-coatings could offer an attractive platform to improve integration of orthopedic implants.

Regulation of inflammation-associated olfactory neuronal death and regeneration by the type II tumor necrosis factor receptor

BACKGROUND

Olfactory loss is a debilitating symptom of chronic rhinosinusitis. To study the impact of inflammation on the olfactory system, the inducible olfactory inflammation (IOI) transgenic mouse was created in which inflammation can be turned on and off within the olfactory epithelium. In this study, the type II tumor necrosis factor (TNF) receptor (TNFR2) was knocked out, and the effect on the olfactory loss phenotype was assessed.

METHODS

IOI mice were bred to TNFR2 knockout mice to yield progeny IOI mice lacking the TNFR2 receptor (TNFR2(-/-) ). TNF-α expression was induced within the olfactory epithelium for 6 weeks to generate chronic inflammation. Olfactory function was assayed by electro-olfactogram (EOG), and olfactory tissue was processed for histology and immunohistochemical staining.

RESULTS

Compared to IOI mice with wild-type TNFR2, IOI mice lacking the TNFR2 demonstrated similar levels of inflammatory infiltration and enlargement of the subepithelial layer. However, IOI-TNFR2(-/-) mice differed markedly in that the neuronal layer was largely preserved and active progenitor cell proliferation was present. Odorant responses were maintained in the IOI-TNFR2(-/-) mice, in contrast to IOI mice.

CONCLUSION

TNFR2 is the minor receptor for TNF-α, but appears to play an important role in mediating TNF-induced disruption of the olfactory system. This finding suggests that neuronal death and inhibition of proliferation in CRS may be mediated by TNFR2 on olfactory neurons and progenitor cells. Further studies are needed to elucidate the subcellular pathways involved and develop novel therapies for treating olfactory loss in the setting of CRS.

Identification of CD68(+) neutrophil granulocytes in in vitro model of acute inflammation and inflammatory bowel disease

CD-68 is widely regarded as a selective marker for human monocytes and macrophages and is commonly used in human pathology studies. The purpose of this study was to investigate the expression of CD-68 in human peripheral blood mononuclear cells (PBMCs), neutrophil granulocytes (NGs) and in inflamed intestinal tissue samples for comparison. PBMCs and NGs were isolated from heparinized human blood samples. Intestinal biopsies were obtained during routine endoscopic procedures from patients with inflammatory bowel disease (IBD), e.g. ulcerative colitis and Crohn's disease. Gene and protein expression was analyzed by real-time RT-PCR, Western blot and immunohistochemistry. Both PBMCs and NGs preparations contained cells that were positive for CD-68 and either neutrophil elastase (NE), or myeloperoxidase (MPO). CD-68(+)/NE(-)/MPO(-) cells were regarded as monocytes. CD-68 mRNA expression was detected in PBMCs and NGs preparations. With Western blot and by performing immunoprecipitation of cell lysate, we could clearly detect CD-68 in NGs, U-937, THP-1, Hep-G2, Jurkat cells and PBMCs. Identification of inflammatory cells in acutely inflamed colonic mucosa obtained from patients with IBD revealed a strong accumulation of CD-68(+)/MPO(+) cells compared to normal colonic mucosa. The uptake of the marker by phagocytosis was excluded by performing a double staining with CD-163/NE and CD-163/MPO in PBMCs, NGs cultures and in inflamed colonic mucosa. These results identify CD-68(+) NGs in peripheral blood and inflamed colonic mucosa. CD-68 is not only a marker for the macrophages-monocytes but also for NGs.

Changes of lysosomes in the earliest stages of the development of atherosclerosis

One of hypotheses of atherosclerosis is based on a presumption that the zones prone to the development of atherosclerosis contain lysosomes which are characterized by enzyme deficiency and thus, are unable to dispose of lipoproteins. The present study was undertaken to investigate the characteristics and changes of lysosomes in the earliest stages of the development of atherosclerosis. Electron microscopic immunocytochemistry revealed that there were certain changes in the distribution of CD68 antigen in lysosomes along the ‘normal intima-initial lesion-fatty streak’ sequence. There were no significant changes found in the key mRNAs encoding for the components of endosome/lysosome compartment in initial atherosclerotic lesions, but in fatty streaks, the contents of EEA1 and Rab5a mRNAs were found to be diminished while the contents of CD68 and p62 mRNAs were increased, compared with the intact tissue. The study reinforces a view that changes occurring in lysosomes play a role in atherogenesis from the very earlier stages of the disease.

Assessing macrophage phenotype during tissue repair

Macrophages are thought to play important roles in tissue repair, from host defense to angiogenesis and new tissue formation. The role of macrophages in repair of different tissues is an active area of inquiry, particularly in settings of impaired healing. In this chapter, we describe methods for isolating monocyte/macrophage cell populations from damaged tissue and characterizing the phenotype of these cells. Cells are isolated from tissue by enzymatic digestion, and then monocyte/macrophage populations can be sorted by magnetic separation. The phenotype of these cells is assessed by real-time PCR, flow cytometry and ELISA. A complementary approach of assessing monocyte/macrophage phenotype by immunofluorescence staining of cryosections is also described. This combination of approaches to study the macrophage phenotypes expressed during tissue repair will lead to better understanding of the roles of macrophages in tissue repair and new therapeutic avenues for improving healing.

Inflammatory markers CD11b, CD16, CD66b, CD68, myeloperoxidase and neutrophil elastase in eccentric exercised human skeletal muscles

The aim of the present study was to investigate leucocyte markers, CD11b, CD16, CD66b, CD68, myeloperoxidase and neutrophil elastase on skeletal muscle biopsies from biceps brachii after unaccustomed eccentric exercise followed by the second bout of exercise 3 weeks later. The subjects (10 subjects received COX-2 inhibitor (Celecoxib) and 13 subjects received placebo) were divided into three categories: mild, moderate and severe effect of eccentric exercise, according to the reduction and recovery of muscle force-generating capacity after performing 70 maximal eccentric actions with elbow flexors on an isokinetic dynamometer. The results showed that the CD66b antibody was applicable for localization of neutrophils in human skeletal muscle, whereas the other studied neutrophil markers recognized also other leucocytes than neutrophils. The number of CD66b positive cells in skeletal muscle was very low and was not affected by the exercise. The macrophage marker CD68 showed reactivity also against satellite cells and fibroblast-like cells in skeletal muscle and therefore cannot be applied as a quantitative value for inflammatory cells. Skeletal muscle fibre injury, shown as dystrophin negative fibres, was observed approximately in half of the biopsies at 4 and 7 days after the first exercise bout in the categories moderate and severe effect of eccentric exercise. These subjects represent the most prominent loss in muscle force-generating capacity both at the category and the individual levels. Furthermore, deformed skeletal muscle fibres were observed in five subjects in these categories after the second bout of exercise. The present results suggest that neutrophils are not involved in skeletal muscle fibre injury and the reduction in muscle force-generating capacity after a single bout of eccentric exercise is a good indirect indicator of muscle damage in humans. Furthermore, prolonged regeneration process could be one of the reasons for impaired peripheral muscle function after high-force eccentric exercise.

Adipocyte dysfunction in a mouse model of polycystic ovary syndrome (PCOS): evidence of adipocyte hypertrophy and tissue-specific inflammation

Clinical research shows an association between polycystic ovary syndrome (PCOS) and chronic inflammation, a pathological state thought to contribute to insulin resistance. The underlying pathways, however, have not been defined. The purpose of this study was to characterize the inflammatory state of a novel mouse model of PCOS. Female mice lacking leptin and insulin receptors in pro-opiomelanocortin neurons (IR/LepR(POMC) mice) and littermate controls were evaluated for estrous cyclicity, ovarian and adipose tissue morphology, and body composition by QMR and CT scan. Tissue-specific macrophage infiltration and cytokine mRNA expression were measured, as well as circulating cytokine levels. Finally, glucose regulation during pregnancy was evaluated as a measure of risk for diabetes development. Forty-five percent of IR/LepR(POMC) mice showed reduced or absent ovulation. IR/LepR(POMC) mice also had increased fat mass and adipocyte hypertrophy. These traits accompanied elevations in macrophage accumulation and inflammatory cytokine production in perigonadal adipose tissue, liver, and ovary. These mice also exhibited gestational hyperglycemia as predicted. This report is the first to show the presence of inflammation in IR/LepR(POMC) mice, which develop a PCOS-like phenotype. Thus, IR/LepR(POMC) mice may serve as a new mouse model to clarify the involvement of adipose and liver tissue in the pathogenesis and etiology of PCOS, allowing more targeted research on the development of PCOS and potential therapeutic interventions.

Tumor-associated macrophages predict inferior outcomes in classic Hodgkin lymphoma: a correlative study from the E2496 Intergroup trial

Increased tumor-associated macrophages (TAMs) are reported to be associated with poor prognosis in classic Hodgkin lymphoma (CHL). We investigated the prognostic significance of TAMs in the E2496 Intergroup trial, a multicenter phase 3 randomized controlled trial comparing ABVD and Stanford V chemotherapy in locally extensive and advanced stage CHL. Tissue microarrays were constructed from formalin-fixed, paraffin-embedded tumor tissue and included 287 patients. Patients were randomly assigned into training (n = 143) and validation (n = 144) cohorts. Immunohistochemistry for CD68 and CD163, and in situ hybridization for EBV-encoded RNA were performed. CD68 and CD163 IHC were analyzed by computer image analysis; optimum thresholds for overall survival (OS) were determined in the training cohort and tested in the independent validation cohort. Increased CD68 and CD163 expression was significantly associated with inferior failure-free survival and OS in the validation cohort. Increased CD68 and CD163 expression was associated with increased age, EBV-encoded RNA positivity, and mixed cellularity subtype of CHL. Multivariate analysis in the validation cohort showed increased CD68 or CD163 expression to be significant independent predictors of inferior failure-free survival and OS. We demonstrate the prognostic significance of TAMs in locally extensive and advanced-stage CHL in a multicenter phase 3 randomized controlled clinical trial.

Revision joint replacement, wear particles, and macrophage polarization

Currently, younger, more active patients are being offered total joint replacement (TJR) for end-stage arthritic disorders. Despite improved durability of TJRs, particle-associated wear of the bearing surfaces continues to be associated with particulate debris, which can activate monocyte/macrophages. Activated macrophages then produce pro-inflammatory factors and cytokines that induce an inflammatory reaction that activates osteoclasts leading to bone breakdown and aseptic loosening. We hypothesized that activated macrophages in tissues harvested from revised joint replacements predominantly express an M1 pro-inflammatory phenotype due to wear-particle-associated cell activation, rather than an M2 anti-inflammatory phenotype. We further questioned whether it is possible to convert uncommitted monocyte/macrophages to an M2 phenotype by the addition of interleukin-4 (IL-4), or whether it is necessary to first pass through an M1 intermediate stage. Retrieved periprosthetic tissues demonstrated increased M1/M2 macrophage ratios compared to non-operated osteoarthritic synovial tissues, using immunohistochemical staining and Western blotting. Uncommitted monocyte/macrophages with/without polymethyl-methacrylate particles were transformed to an M2 phenotype by IL-4 more efficiently when the cells were first passed through an M1 phenotype by exposure to endotoxin. Wear particles induce a pro-inflammatory microenvironment that facilitates osteolysis; these events may potentially be modulated favorably by exposure to IL-4.

Niacin reduces plasma CETP levels by diminishing liver macrophage content in CETP transgenic mice

The anti-dyslipidemic drug niacin has recently been shown to reduce the hepatic expression and plasma levels of CETP. Since liver macrophages contribute to hepatic CETP expression, we investigated the role of macrophages in the CETP-lowering effect of niacin in mice. In vitro studies showed that niacin does not directly attenuate CETP expression in macrophages. Treatment of normolipidemic human CETP transgenic mice, fed a Western-type diet with niacin for 4 weeks, significantly reduced the hepatic cholesterol concentration (-20%), hepatic CETP gene expression (-20%), and plasma CETP mass (-30%). Concomitantly, niacin decreased the hepatic expression of CD68 (-44%) and ABCG1 (-32%), both of which are specific markers for the hepatic macrophage content. The decrease in hepatic CETP expression was significantly correlated with the reduction of hepatic macrophage markers. Furthermore, niacin attenuated atherogenic diet-induced inflammation in liver, as evident from decreased expression of TNF-alpha (-43%). Niacin similarly decreased the macrophage markers and absolute macrophage content in hyperlipidemic APOE*3-Leiden.CETP transgenic mice on a Western-type diet. In conclusion, niacin decreases hepatic CETP expression and plasma CETP mass by attenuating liver inflammation and macrophage content in response to its primary lipid-lowering effect, rather than by attenuating the macrophage CETP expression level.

Interleukin-10 spot-forming cells as a novel biomarker of chronic graft-versus-host disease

Although there are National Institutes of Health consensus criteria for the global assessment of chronic graft-versus-host disease, no validated biomarkers have been established for this disease. Furthermore, whereas the role of T cells, B cells, and dendritic cells in chronic graft-versus-host disease has been established, the contribution of monocytes has not been clearly addressed. Using an enzyme-linked immunospot assay, we measured the spot-forming cells for interferon-γ, interleukin-4, interleukin-10, and interleukin-17 in unstimulated peripheral blood of patients following allogeneic hematopoietic stem cell transplantation. Other immunological examinations, including skin biopsy, were also done. Fifty-seven patients were enrolled. Interleukin-10 spot-forming cells were evaluable for therapeutic monitoring in 16 patients with chronic graft-versus-host disease. The number of interleukin-10 spot-forming cells in patients with active chronic graft-versus-host disease was significantly higher than the number in those with no or inactive chronic graft-versus-host disease. Interleukin-10 was predominantly produced by monocytes. CD29 expression on monocytes in patients with active chronic graft-versus-host disease was elevated. The level of plasma fibronectin, a ligand of CD29, correlated with the number of interleukin-10 spot-forming cells. Immunohistochemical analysis of the skin in active chronic graft-versus-host disease showed that infiltrating CD29(+) monocytes might produce interleukin-10. A novel biomarker, interleukin-10 spot-forming cells, shows promise as both a diagnostic and prognostic indicator for chronic graft-versus-host disease, and may allow for early intervention prior to the onset of the disease. Measurement of interleukin-10 spot-forming cells would be helpful in clinical trials and in patients' management.

Macrophage-related diseases of the gut: a pathologist's perspective

The resident macrophages of the gastrointestinal tract represent the largest population of macrophages in the human body and are usually located in the subepithelial lamina propria. This strategic location guarantees a first-line defense to the huge numbers of potentially harmful bacteria and antigenic stimuli that are present in the intestinal lumen. In non-inflamed mucosa, macrophages phagocytose and kill microbes in the absence of an inflammatory response. However, in the event of an epithelial breach and/or microbial invasion, new circulating monocytes and lymphocytes will be recruited to the damaged area of the gut, which will result in the secretion of proinflammatory mediators and engage a protective inflammatory response. Although macrophages are usually not conspicuous in normal mucosal samples of the gut, they can easily be detected when they accumulate exogenous particulate material or endogenous substances or when they become very numerous. These events will mostly occur in pathologic conditions, and this review presents an overview of the diseases which are either mediated by or affecting the resident macrophages of the gut.

Determination of spatial and temporal distribution of microglia by 230nm-high-resolution, high-throughput automated analysis reveals different amyloid plaque populations in an APP/PS1 mouse model of Alzheimer's disease

One early and prominent pathologic feature of Alzheimer's disease (AD) is the appearance of activated microglia in the vicinity of developing β-amyloid deposits. However, the precise role of microglia during the course of AD is still under discussion. Microglia have been reported to degrade and clear β-amyloid, but they also can exert deleterious effects due to overwhelming inflammatory reactions. Here, we demonstrate the occurrence of developing plaque populations with distinct amounts of associated microglia using time-dependent analyses of plaque morphology and the spatial distribution of microglia in an APP/PS1 mouse model. In addition to a population of larger plaques (>700µm(2)) that are occupied by a moderate contingent of microglial cells across the course of aging, a second type of small β-amyloid deposits develops (≤400µm(2)) in which the plaque core is enveloped by a relatively large number of microglia. Our analyses indicate that microglia are strongly activated early in the emergence of senile plaques, but that activation is diminished in the later stages of plaque evolution (>150 days). These findings support the view that microglia serve to restrict the growth of senile plaques, and do so in a way that minimizes local inflammatory damage to other components of the brain.

The distribution of immunomodulatory cells in the lungs of patients with idiopathic pulmonary fibrosis

We have characterized the immune system involvement in the disease processes of idiopathic pulmonary fibrosis in novel ways. To do so, we analyzed lung tissue from 21 cases of idiopathic pulmonary fibrosis and 21 (non-fibrotic, non-cancerous) controls for immune cell and inflammation-related markers. The immunohistochemical analysis of the tissue was grouped by patterns of severity in disease pathology. There were significantly greater numbers of CD68(+) and CD80(+) cells and significantly fewer CD3(+), CD4(+), and CD45RO(+) cells in areas of relatively (histologically) normal lung in biopsy samples from idiopathic pulmonary fibrosis patients compared with controls. In zones of active disease, characterized by epithelial cell regeneration and fibrosis, there were significantly more cells expressing CD4, CD8, CD20, CD68, CD80, chemokine receptor 6 (CCR6), S100, IL-17, tumor necrosis factor-α, and retinoic acid-related orphan receptors compared with histologically normal lung areas from idiopathic pulmonary fibrosis patients. Inflammation was implicated in these active regions by the cells that expressed retinoid orphan receptor-α, -β, and -γ, CCR6, and IL-17. The regenerating epithelial cells predominantly expressed these pro-inflammatory molecules, as evidenced by co-expression analyses with epithelial cytokeratins. Macrophages in pseudo-alveoli and CD3(+) T cells in the fibrotic interstitium also expressed IL-17. Co-expression of IL-17 with retinoid orphan receptors and epithelial cytoskeletal proteins, CD68, and CD3 in epithelial cells, macrophages, and T-cells, respectively, confirmed the production of IL-17 by these cell types. There was little staining for forkhead box p3, CD56, or CD34 in any idiopathic pulmonary fibrosis lung regions. The fibrotic regions had fewer immune cells overall. In summary, our study shows participation of innate and adaptive mononuclear cells in active-disease regions of idiopathic pulmonary fibrosis lung, where the regenerating epithelial cells appear to propagate inflammation. The regenerative mechanisms become skewed to ultimately result in lethal, fibrotic restriction of lung function.

Immunohistochemical markers for tumor associated macrophages and survival in advanced classical Hodgkin's lymphoma

A subset of patients with advanced classical Hodgkin's lymphoma is refractory to standard therapies. Therefore, it is relevant to identify new biologically-based prognostic markers. Recently, tumor associated macrophages have been proposed as a factor that predicts survival, although contradictory results have also been reported. Here we analyzed four macrophage markers (CD68, CD163, LYZ, and STAT1) using immunohistochemistry and automated quantification, in two independent series of advanced classical Hodgkin's lymphoma (n=266 and 103 patients, respectively). Our results did not confirm that specific macrophage immunohistochemical markers could be used as surrogates for gene expression profiling studies. Survival analyses did not show correlation between CD163, LYZ or STAT1 and either failure-free or disease-specific survival. There was an association between CD68 and disease-specific survival, but it was not consistent in both series. In conclusion, individual tumor associated macrophage markers cannot be used to predict outcome before technical standardization and prospective validation in independent series of patients with comparable stages and treatments.

Early glial activation, synaptic changes and axonal pathology in the thalamocortical system of Niemann-Pick type C1 mice

Niemann–Pick disease type C (NPC) is an inherited lysosomal storage disease characterised by accumulation of cholesterol and glycosphingolipids. NPC patients suffer a progressive neurodegenerative phenotype presenting with motor dysfunction, mental retardation and cognitive decline. To examine the onset and progression of neuropathological insults in NPC we have systematically examined the CNS of a mouse model of NPC1 (Npc1^−/− mice) at different stages of the disease course. This revealed a specific spatial and temporal pattern of neuropathology in Npc1^−/− mice, highlighting that sensory thalamic pathways are particularly vulnerable to loss of NPC1 resulting in neurodegeneration in Npc1^−/− mice. Examination of markers of astrocytosis and microglial activation revealed a particularly pronounced reactive gliosis in the thalamus early in the disease, which subsequently also occurred in interconnected cortical laminae at later ages. Our examination of the precise staging of events demonstrate that the relationship between glia and neurons varies between brain regions in Npc1^−/− mice, suggesting that the cues causing glial reactivity may differ between brain regions. In addition, aggregations of pre-synaptic markers are apparent in white matter tracts and the thalamus and are likely to be formed within axonal spheroids. Our data provide a new perspective, revealing a number of events that occur prior to and alongside neuron loss and highlighting that these occur in a pathway dependent manner.

Activated macrophages containing tumor marker in colon carcinoma: immunohistochemical proof of a concept

The presence of carcinoembryonic antigen (CEA)-containing activated macrophages has been demonstrated in peripheral blood from patients with colorectal carcinoma. Macrophages migrate from the circulation into the tissue, phagocytose debris, and return to the bloodstream. Hence it seems likely that activated macrophages containing tumor debris, i.e., tumor marker, are present in the stroma of colorectal carcinoma. After phagocytosis, they could follow a hematogenic or lymphogenic route to the peripheral blood. The aim of this study is to assess the presence of tumor marker-containing activated macrophages in the stroma of colon carcinoma and in regional lymph nodes. From 10 cases of colon carcinoma, samples of tumor tissue and metastasis-free lymph nodes were cut in serial sections and stained for CD68 to identify macrophages and for CEA, cytokeratin, or M30 presence. Slides were digitalised and visually inspected using two monitors, comparing the CD68 stain to the tumor marker stain to evaluate the presence of tumor marker-positive macrophages. Macrophages containing tumor marker could be identified in tumor stroma and in metastasis-free regional lymph nodes. The distribution varied for the different markers, CEA-positive macrophages being most abundant. The presence of macrophages containing tumor marker in the tumor stroma and lymph nodes from patients with colon carcinoma could be confirmed in this series using serial immunohistochemistry. This finding supports the concept of activated macrophages, after phagocytosing cell debris, being transported or migrating through the lymphatic system. These results support the potential of tumor marker-containing macrophages to serve as a marker for diagnosis and follow-up of colon cancer patients.

Tumor-associated macrophages (TAMs) form an interconnected cellular supportive network in anaplastic thyroid carcinoma

BACKGROUND

A relationship between the increased density of tumor-associated macrophages (TAMs) and decreased survival was recently reported in thyroid cancer patients. Among these tumors, anaplastic thyroid cancer (ATC) is one of the most aggressive solid tumors in humans. TAMs (type M2) have been recognized as promoting tumor growth. The purpose of our study was to analyze with immunohistochemistry the presence of TAMs in a series of 27 ATC.

METHODOLOGY/PRINCIPAL FINDINGS

Several macrophages markers such as NADPH oxidase complex NOX2-p22phox, CD163 and CD 68 were used. Immunostainings showed that TAMs represent more than 50% of nucleated cells in all ATCs. Moreover, these markers allowed the identification of elongated thin ramified cytoplasmic extensions, bestowing a "microglia-like" appearance on these cells which we termed "Ramified TAMs" (RTAMs). In contrast, cancer cells were totally negative. Cellular stroma was highly simplified since apart from cancer cells and blood vessels, RTAMs were the only other cellular component. RTAMs were evenly distributed and intermingled with cancer cells, and were in direct contact with other RTAMs via their ramifications. Moreover, RTAMs displayed strong immunostaining for connexin Cx43. Long chains of interconnected RTAMs arose from perivascular clusters and were dispersed within the tumor parenchyma. When expressed, the glucose transporter Glut1 was found in RTAMs and blood vessels, but rarely in cancer cells.

CONCLUSION

ATCs display a very dense network of interconnected RTAMs in direct contact with intermingled cancer cells. To our knowledge this is the first time that such a network is described in a malignant tumor. This network was found in all our studied cases and appeared specific to ATC, since it was not found in differentiated thyroid cancers specimens. Taken together, these results suggest that RTAMs network is directly related to the aggressiveness of the disease via metabolic and trophic functions which remain to be determined.

Six-transmembrane epithelial antigen of prostate4 (STEAP4) is a tumor necrosis factor alpha-induced protein that regulates IL-6, IL-8, and cell proliferation in synovium from patients with rheumatoid arthritis

Human six-transmembrane epithelial antigen of prostate4 (STEAP4), an ortholog of mouse tumor necrosis factor-α-induced adipose-related protein (TIARP), plays a role in tumor necrosis factor (TNF)-dependent arthritis models. However, its role in rheumatoid arthritis (RA) is still obscure. This study explored such a role for STEAP4. The expressions of STEAP4, TNFα, and IL-6 were compared in synovia of RA and osteoarthritis patients. STEAP4 induction was examined in TNFα-stimulated fibroblast-like synoviocytes (FLS) in vitro. FLS (with/without TNFα stimulation) were also analyzed for IL-6 expression after STEAP4 knockdown, using siRNA or transfection with STEAP4-plasmid DNA. IL-8, cell proliferation, and apoptosis were also evaluated in STEAP4-overexpressing FLS. The expression of STEAP4 in joints correlated with TNFα expression, specifically in RA synovium. In the cultured FLS, STEAP4 protein expression was augmented by TNFα activation, and localized in endosomal/lysosomal compartments. STEAP4 downregulation by siRNA enhanced the expression of IL-6 mRNA, while STEAP4 overexpression suppressed IL-6 and IL-8 expression, inhibited cell proliferation, and induced apoptosis via caspase-3. The results indicated that human STEAP4 is regulated by TNFα in synovium, where it controls IL-6 secretion and proliferation of FLS, suggesting that STEAP4 might potentially suppress the pathogenesis of TNFα-induced arthritis such as RA.

Neurofibromatosis-1 heterozygosity increases microglia in a spatially and temporally restricted pattern relevant to mouse optic glioma formation and growth

Whereas carcinogenesis requires the acquisition of driver mutations in progenitor cells, tumor growth and progression are heavily influenced by the local microenvironment. Previous studies from our laboratory have used Neurofibromatosis-1 (NF1) genetically engineered mice to characterize the role of stromal cells and signals to optic glioma formation and growth. Previously, we have shown that Nf1+/- microglia in the tumor microenvironment are critical cellular determinants of optic glioma proliferation. To define the role of microglia in tumor formation and maintenance further, we used CD11b-TK mice, in which resident brain microglia (CD11b+, CD68+, Iba1+, CD45low cells) can be ablated at specific times after ganciclovir administration. Ganciclovir-mediated microglia reduction reduced Nf1 optic glioma proliferation during both tumor maintenance and tumor development. We identified the developmental window during which microglia are increased in the Nf1+/- optic nerve and demonstrated that this accumulation reflected delayed microglia dispersion. The increase in microglia in the Nf1+/- optic nerve was associated with reduced expression of the chemokine receptor, CX3CR1, such that reduced Cx3cr1 expression in Cx3cr1-GFP heterozygous knockout mice led to a similar increase in optic nerve microglia. These results establish a critical role for microglia in the development and maintenance of Nf1 optic glioma.

Measurement of macrophage growth and differentiation

This unit provides protocols for measuring the abundance and growth of macrophage precursors in agar cultures and the proliferation of isolated mature macrophages in vitro, by either direct cell counting or by DNA measurement. Methods for the immunohistochemical identification of macrophages and the determination of their proliferative status in vivo by immunofluorescence are also included. It also describes methods for characterization of macrophage differentiation through the immunofluorescence analysis of cell-surface expression of CSF-1 receptor.

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.

Differential cell reaction upon Toll-like receptor 4 and 9 activation in human alveolar and lung interstitial macrophages

Background

Investigations on pulmonary macrophages (MΦ) mostly focus on alveolar MΦ (AM) as a well-defined cell population. Characteristics of MΦ in the interstitium, referred to as lung interstitial MΦ (IM), are rather ill-defined. In this study we therefore aimed to elucidate differences between AM and IM obtained from human lung tissue.

Methods

Human AM and IM were isolated from human non-tumor lung tissue from patients undergoing lung resection. Cell morphology was visualized using either light, electron or confocal microscopy. Phagocytic activity was analyzed by flow cytometry as well as confocal microscopy. Surface marker expression was measured by flow cytometry. Toll-like receptor (TLR) expression patterns as well as cytokine expression upon TLR4 or TLR9 stimulation were assessed by real time RT-PCR and cytokine protein production was measured using a fluorescent bead-based immunoassay.

Results

IM were found to be smaller and morphologically more heterogeneous than AM, whereas phagocytic activity was similar in both cell types. HLA-DR expression was markedly higher in IM compared to AM. Although analysis of TLR expression profiles revealed no differences between the two cell populations, AM and IM clearly varied in cell reaction upon activation. Both MΦ populations were markedly activated by LPS as well as DNA isolated from attenuated mycobacterial strains (M. bovis H37Ra and BCG). Whereas AM expressed higher amounts of inflammatory cytokines upon activation, IM were more efficient in producing immunoregulatory cytokines, such as IL10, IL1ra, and IL6.

Conclusion

AM appear to be more effective as a non-specific first line of defence against inhaled pathogens, whereas IM show a more pronounced regulatory function. These dissimilarities should be taken into consideration in future studies on the role of human lung MΦ in the inflammatory response.

The number of CD68(+) (Hofbauer) cells is decreased in placentas with chorioamnionitis and with advancing gestational age

Hofbauer cells are placental macrophages found in chorionic villous stroma; they express classic monocyte/macrophage markers, such as CD68. Little is known about their participation in placental disease and immunologic interactions at the placental interface. The aim of this study was to quantify the amount of Hofbauer cells in placentas complicated, or not, by chorioamnionitis and in placentas from different gestational ages. Fifty-eight 2nd- and 3rd-trimester placentas with the histologic diagnosis of acute chorioamnionitis were compared with 42 control placentas matched according to gestational age. Immunohistochemistry evaluation was performed with a monoclonal anti-CD68 antibody. Five areas of each placenta were photographed and 5 investigators, with the help of a computerized image analysis program, independently evaluated the number of CD68(+) cells. Our results showed that there are significantly fewer CD68(+) cells per villous area in placentas diagnosed with chorioamnionitis than in those of controls (P < 0.001). Moreover, there was a significant overall decrease in the number of these cells in 3rd as compared with 2nd trimester placentas (P  =  0.02), as well as in placentas from term as compared to preterm pregnancies (P  =  0.004). Our data indicate that CD68(+) Hofbauer cells may be involved in placental infection and possibly associated with the developmental maturation of the fetoplacental unit.

Importance of CCL2-CCR2A/2B signaling for monocyte migration into spheroids of breast cancer-derived fibroblasts

A considerable fraction of tumor-associated macrophages (TAM) is located in the fibroblast-rich stromal compartment of desmoplastic breast carcinoma. We analyzed the migratory activity of blood monocytes (MO), the precursor cells of TAM, into 3-D cultures of carcinoma cells and fibroblasts from breast tumor origin. MO migration into breast tumor spheroids was highly variable: Hs578T spheroids showed high MO infiltration rates, T47D cultures were intermediate, whereas BT549, BT474 and MCF-7 spheroids were poorly infiltrated. MO infiltration was also high in tumor-derived fibroblast spheroids; however, no MO subpopulation with specific infiltrative potential was identified by CD14/CD16 expression profile. The infiltration of MO could be inhibited by pre-exposure to pertussis and cholera toxins, but only pertussis toxin, which blocks G(i) protein function, entirely inhibited MO migration. The G(i) coupled CCL2 receptor CCR2A/2B was expressed on roughly all MO. Furthermore, highly infiltrated tumor-derived fibroblast and Hs578T spheroids secreted considerable amounts of CCL2. In line with this, the infiltration of MO into fibroblast spheroids was suppressed by either addition of recombinant CCL2 to disturb the CCL2 gradient or by pre-incubation of MO with a CCR2A/2B blocking antibody. MO infiltration of Hs578T spheroids, however, could not be inhibited by CCL2 receptor blockade. Our study clearly shows that the CCL2-CCR2A/2B pathway is crucial for the recruitment of blood MO into tumor fibroblastic areas, whereas additional factors may be relevant for the migration of MO into tumor cell sites.

Flow cytometric characterization of freshly isolated and culture expanded human synovial cell populations in patients with chronic arthritis

Introduction

The synovium is a major target tissue in chronic arthritis and is intensively studied at the cellular and molecular level. The aim of this study was to develop flow cytometry for the quantitative analysis of synovial cell populations pre and post culture and to characterize mesenchymal cell populations residing in the inflammatory synovium.

Methods

Knee synovium biopsies from 39 patients with chronic arthritis and from 15 controls were treated in a short, standardized tissue digestion procedure. Stored, thawed digests were routinely analyzed with flow cytometry including live-dead staining and use of the markers CD45, CD3, CD14, CD20, CD34, CD73, CD105, CD90, CD146, CD163 and HLA-DR to distinguish inflammatory and stromal cells. The influence of the digestion method on the detection of the different surface markers was studied separately. In addition, we studied the presence of a specific cell population hypothesized to be mesenchymal stem cells (MSC) based on the CD271 marker. Cell expansion cultures were set up and a MSC-related surface marker profile in passages 3 and 6 was obtained. Immunohistochemistry for CD34 and von Willebrand factor (vWF) was done to obtain additional data on synovium vascularity.

Results

The cell yield and viability normalized to tissue weight were significantly higher in inflammatory arthritis than in controls. Within the hematopoietic CD45-positive populations, we found no differences in relative amounts of macrophages, T-lymphocytes and B-lymphocytes between patient groups. Within the CD45-negative cells, more CD34-positive cells were seen in controls than in arthritis patients. In arthritis samples, a small CD271 positive population was detected. Culture expanded cells were found to fulfill the multipotent mesenchymal stromal cell marker profile, except for CD34 negativity. Detection of peripheral blood macrophage and B-cell markers was decreased after enzymatic exposure and mechanical forces, respectively, but stromal markers were not affected.

Conclusions

Flow cytometry can distinguish synovial cell populations in tissue digests. The preparation method can influence the detection levels of macrophage and B-cell populations. However, stromal cell markers seem not affected and quantification is possible, supporting flow cytometry tissue analysis as a tool to study these cell populations in arthritis.