The c-kit Ligand Stem Cell Factor and Anti-IgE Promote Expression of Monocyte Chemoattractant Protein-1 in Human Lung Mast Cells

Mediator-Related Symptoms and Anaphylaxis in Children with Mastocytosis

Mastocytosis is characterized by the pathological accumulation of mast cells (MC) in various organs. In these patients, MC may degranulate and thereby contribute to clinical symptoms, especially when a concomitant allergy is present. However, MC activation can not only be induced by high-affinity receptors for IgE, but also by anaphylatoxins, neuropeptides, IgG immune complexes, complement-components, drugs, products of bacteria or parasites, as well as physical factors such as heat, cold, vibration, stress, sun, or physical effort. Symptoms due to mediators released by activated MC may develop in adults suffering from systemic mastocytosis, but also evolve in children who usually have cutaneous mastocytosis (CM). Clinically, CM is otherwise characterized by typical brown, maculopapular skin lesions or mastocytoma associated with a positive Darier's sign. Pruritus and flushing are common and blistering may also be recorded, especially in diffuse CM (DCM). Pediatric patients with mastocytosis may also have gastrointestinal, respiratory, and neurologic complaints. Although anaphylaxis is not a typical finding, pediatric patients with massive skin involvement and high tryptase levels have a relatively high risk to develop anaphylaxis. This paper reviews MC mediator-related symptoms and anaphylaxis in children with mastocytosis, with special emphasis on risk factors, triggers, and management.

More Than Just Attractive: How CCL2 Influences Myeloid Cell Behavior Beyond Chemotaxis

Monocyte chemoattractant protein-1 (MCP-1/CCL2) is renowned for its ability to drive the chemotaxis of myeloid and lymphoid cells. It orchestrates the migration of these cell types both during physiological immune defense and in pathological circumstances, such as autoimmune diseases including rheumatoid arthritis and multiple sclerosis, inflammatory diseases including atherosclerosis, as well as infectious diseases, obesity, diabetes, and various types of cancer. However, new data suggest that the scope of CCL2's functions may extend beyond its original characterization as a chemoattractant. Emerging evidence shows that it can impact leukocyte behavior, influencing adhesion, polarization, effector molecule secretion, autophagy, killing, and survival. The direction of these CCL2-induced responses is context dependent and, in some cases, synergistic with other inflammatory stimuli. The involvement of CCL2 signaling in multiple diseases renders it an interesting therapeutic target, although current targeting strategies have not met early expectations in the clinic. A better understanding of how CCL2 affects immune cells will be pivotal to the improvement of existing therapeutic approaches and the development of new drugs. Here, we provide an overview of the pleiotropic effects of CCL2 signaling on cells of the myeloid lineage, beyond chemotaxis, and highlight how these actions might help to shape immune cell behavior and tumor immunity.

The controversial role of mast cells in fibrosis

Fibrosis is a medical condition characterized by an excessive deposition of extracellular matrix compounds such as collagen in tissues. Fibrotic lesions are present in many diseases and can affect all organs. The excessive extracellular matrix accumulation in these conditions can often have serious consequences and in many cases be life-threatening. A typical event seen in many fibrotic conditions is a profound accumulation of mast cells (MCs), suggesting that these cells can contribute to the pathology. Indeed, there is now substantialv evidence pointing to an important role of MCs in fibrotic disease. However, investigations from various clinical settings and different animal models have arrived at partly contradictory conclusions as to how MCs affect fibrosis, with many studies suggesting a detrimental role of MCs whereas others suggest that MCs can be protective. Here, we review the current knowledge of how MCs can affect fibrosis.

Mechanisms Involved in Childhood Obesity-Related Bone Fragility

Childhood obesity is one of the major health problems in western countries. The excessive accumulation of adipose tissue causes inflammation, oxidative stress, apoptosis, and mitochondrial dysfunctions. Thus, obesity leads to the development of severe co-morbidities including type 2 diabetes mellitus, liver steatosis, cardiovascular, and neurodegenerative diseases which can develop early in life. Furthermore, obese children have low bone mineral density and a greater risk of osteoporosis and fractures. The knowledge about the interplay bone tissue and between adipose is still growing, although recent findings suggest that adipose tissue activity on bone can be fat-depot specific. Obesity is associated to a low-grade inflammation that alters the expression of adiponectin, leptin, IL-6, Monocyte Chemotactic Protein 1 (MCP1), TRAIL, LIGHT/TNFSF14, OPG, and TNFα. These molecules can affect bone metabolism, thus resulting in osteoporosis. The purpose of this review was to deepen the cellular mechanisms by which obesity may facilitate osteoporosis and bone fractures.

CCL2 is a KIT D816V-dependent modulator of the bone marrow microenvironment in systemic mastocytosis

Systemic mastocytosis (SM) is characterized by abnormal accumulation of neoplastic mast cells harboring the activating KIT mutation D816V in the bone marrow and other internal organs. As found in other myeloproliferative neoplasms, increased production of profibrogenic and angiogenic cytokines and related alterations of the bone marrow microenvironment are commonly found in SM. However, little is known about mechanisms and effector molecules triggering fibrosis and angiogenesis in SM. Here we show that KIT D816V promotes expression of the proangiogenic cytokine CCL2 in neoplastic mast cells. Correspondingly, the KIT-targeting drug midostaurin and RNA interference-mediated knockdown of KIT reduced expression of CCL2. We also found that nuclear factor κB contributes to KIT-dependent upregulation of CCL2 in mast cells. In addition, CCL2 secreted by KIT D816V⁺ mast cells was found to promote the migration of human endothelial cells in vitro. Furthermore, knockdown of CCL2 in neoplastic mast cells resulted in reduced microvessel density and reduced tumor growth in vivo compared with CCL2-expressing cells. Finally, we measured CCL2 serum concentrations in patients with SM and found that CCL2 levels were significantly increased in mastocytosis patients compared with controls. CCL2 serum levels were higher in patients with advanced SM and were found to correlate with poor survival. In summary, we have identified CCL2 as a novel KIT D816V-dependent key regulator of vascular cell migration and angiogenesis in SM. CCL2 expression correlates with disease severity and prognosis. Whether CCL2 may serve as a therapeutic target in advanced SM remains to be determined in forthcoming studies.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Genomic responses during acute human anaphylaxis are characterized by upregulation of innate inflammatory gene networks

Background

Systemic spread of immune activation and mediator release is required for the development of anaphylaxis in humans. We hypothesized that peripheral blood leukocyte (PBL) activation plays a key role.

Objective

To characterize PBL genomic responses during acute anaphylaxis.

Methods

PBL samples were collected at three timepoints from six patients presenting to the Emergency Department (ED) with acute anaphylaxis and six healthy controls. Gene expression patterns were profiled on microarrays, differentially expressed genes were identified, and network analysis was employed to explore underlying mechanisms.

Results

Patients presented with moderately severe anaphylaxis after oral aspirin (2), peanut (2), bee sting (1) and unknown cause (1). Two genes were differentially expressed in patients compared to controls at ED arrival, 67 genes at 1 hour post-arrival and 2,801 genes at 3 hours post-arrival. Network analysis demonstrated that three inflammatory modules were upregulated during anaphylaxis. Notably, these modules contained multiple hub genes, which are known to play a central role in the regulation of innate inflammatory responses. Bioinformatics analyses showed that the data were enriched for LPS-like and TNF activation signatures.

Conclusion

PBL genomic responses during human anaphylaxis are characterized by dynamic expression of innate inflammatory modules. Upregulation of these modules was observed in patients with different reaction triggers. Our findings indicate a role for innate immune pathways in the pathogenesis of human anaphylaxis, and the hub genes identified in this study represent logical candidates for follow-up studies.

Ischemia-reperfusion injury and pregnancy initiate time-dependent and robust signs of up-regulation of cardiac progenitor cells

To explore how cardiac regeneration and cell turnover adapts to disease, different forms of stress were studied for their effects on the cardiac progenitor cell markers c-Kit and Isl1, the early cardiomyocyte marker Nkx2.5, and mast cells. Adult female rats were examined during pregnancy, after myocardial infarction and ischemia-reperfusion injury with/out insulin like growth factor-1(IGF-1) and hepatocyte growth factor (HGF). Different cardiac sub-domains were analyzed at one and two weeks post-intervention, both at the mRNA and protein levels. While pregnancy and myocardial infarction up-regulated Nkx2.5 and c-Kit (adjusted for mast cell activation), ischemia-reperfusion injury induced the strongest up-regulation which occurred globally throughout the entire heart and not just around the site of injury. This response seems to be partly mediated by increased endogenous production of IGF-1 and HGF. Contrary to c-Kit, Isl1 was not up-regulated by pregnancy or myocardial infarction while ischemia-reperfusion injury induced not a global but a focal up-regulation in the outflow tract and also in the peri-ischemic region, correlating with the up-regulation of endogenous IGF-1. The addition of IGF-1 and HGF did boost the endogenous expression of IGF and HGF correlating to focal up-regulation of Isl1. c-Kit expression was not further influenced by the exogenous growth factors. This indicates that there is a spatial mismatch between on one hand c-Kit and Nkx2.5 expression and on the other hand Isl1 expression. In conclusion, ischemia-reperfusion injury was the strongest stimulus with both global and focal cardiomyocyte progenitor cell marker up-regulations, correlating to the endogenous up-regulation of the growth factors IGF-1 and HGF. Also pregnancy induced a general up-regulation of c-Kit and early Nkx2.5+ cardiomyocytes throughout the heart. Utilization of these pathways could provide new strategies for the treatment of cardiac disease.

The role of the CCL2/CCR2 axis in mouse mast cell migration in vitro and in vivo

Tissue-resident mast cells (MCs) are important in allergic diseases. In a mouse model of allergic airways inflammation, an increase in peribronchiolar MCs was associated with increased concentrations of the chemokine CCL2 in lung lavage. MC progenitors (MCps) arising in bone marrow (BM) are recruited to tissues by transendothelial migration, and we found that CCL2 is chemotactic for MCps in freshly isolated BM in vitro. Immature, but not mature, BM-derived MCs migrated in response to CCL2 when cultured in IL-3+stem cell factor (SCF) but not when cultured in IL-3 alone. However, the cells under both culture conditions expressed mRNA for CCR2, the receptor for CCL2, and bound the radiolabeled chemokine with similar affinities, highlighting SCF as a key mediator in coupling CCR2 to downstream events, culminating in chemotaxis. Immature BM-derived MCs from IL-3 +SCF cultures, when administered i.v., accumulated at skin sites injected with CCL2 in vivo. MCp recruitment to the allergen-sensitized/challenged lung was significantly reduced in CCR2(-/-) and CCL2(-/-) mouse strains. However, reconstitution studies of sublethally irradiated and BM-reconstituted mice indicated that BM cells and stromal elements could provide CCL2, whereas the CCR2 function resided with stromal elements rather than BM cells. These experiments revealed a new function of SCF in chemokine receptor coupling, but they suggest a complex role of the CCL2/CCR2 axis in recruiting MCps during pulmonary inflammation.

CD72 negatively regulates KIT-mediated responses in human mast cells

KIT activation, through binding of its ligand, stem cell factor, is crucial for normal mast cell growth, differentiation, and survival. Furthermore, KIT may also contribute to mast cell homing and cytokine generation. Activating mutations in KIT lead to the dysregulated mast cell growth associated with the myeloproliferative disorder, mastocytosis. We investigated the potential of downregulating such responses through mast cell inhibitory receptor activation. In this study, we report that the B cell-associated ITIM-containing inhibitory receptor, CD72, is expressed in human mast cells. Ligation of CD72 with the agonistic Ab, BU40, or with recombinant human CD100 (rCD100), its natural ligand, induced the phosphorylation of CD72 with a resulting increase in its association with the tyrosine phosphatase SH2 domain-containing phosphatase-1. This, in turn, resulted in an inhibition of KIT-induced phosphorylation of Src family kinases and extracellular-regulated kinases (ERK1/2). As a consequence of these effects, KIT-mediated mast cell proliferation, chemotaxis, and chemokine production were significantly reduced by BU40 and rCD100. Furthermore, BU40 and rCD100 also downregulated the growth of the HMC1.2 human mast cell line. Thus, targeting CD72 may provide a novel approach to the suppression of mast cell disease such as mastocytosis.

IL-33 synergizes with IgE-dependent and IgE-independent agents to promote mast cell and basophil activation

OBJECTIVE

Mast cell and basophil activation contributes to inflammation, bronchoconstriction, and airway hyperresponsiveness in asthma. Because IL-33 expression is inflammation inducible, we investigated IL-33-mediated effects in concert with both IgE-mediated and IgE-independent stimulation.

METHODS

Because the HMC-1 mast cell line can be activated by GPCR and RTK signaling, we studied the effects of IL-33 on these pathways. The IL-33- and SCF-stimulated HMC-1 cells were co-cultured with human lung fibroblasts and airway smooth muscle cells in a collagen gel contraction assay. IL-33 effects on IgE-mediated activation were studied in primary mast cells and basophils.

RESULT

IL-33 synergized with adenosine, C5a, SCF, and NGF receptor activation. IL-33-stimulated and SCF-stimulated HMC-1 cells demonstrated enhanced collagen gel contraction when cultured with fibroblasts or smooth muscle cells. IL-33 also synergized with IgE receptor activation of primary human mast cells and basophils.

CONCLUSION

IL-33 amplifies inflammation in both IgE-independent and IgE-dependent responses.

Human mast cell activation with virus-associated stimuli leads to the selective chemotaxis of natural killer cells by a CXCL8-dependent mechanism

Human mast cells are found in skin and mucosal surfaces and next to blood vessels. They play a sentinel cell role in immunity, recognizing invading pathogens and producing proinflammatory mediators. Mast cells can recruit granulocytes, and monocytes in allergic disease and bacterial infection, but their ability to recruit antiviral effector cells such as natural killer (NK) cells and T cells has not been fully elucidated. To investigate the role of human mast cells in response to virus-associated stimuli, human cord blood-derived mast cells (CBMCs) were stimulated with polyinosinic.polycytidylic acid, a double-stranded RNA analog, or infected with the double-stranded RNA virus, reovirus serotype 3 Dearing for 24 hours. CBMCs responded to stimulation with polyinosinic.polycytidylic acid by producing a distinct chemokine profile, including CCL4, CXCL8, and CXCL10. CBMCs produced significant amounts of CXCL8 in response to low levels of reovirus infection, while both skin- and lung-derived fibroblasts were unresponsive unless higher doses of reovirus were used. Supernatants from CBMCs infected with reovirus induced substantial NK cell chemotaxis that was highly dependent on CXCL8 and CXCR1. These results suggest a novel role for mast cells in the recruitment of human NK cells to sites of early viral infection via CXCL8.

Genome-wide association with select biomarker traits in the Framingham Heart Study

BACKGROUND

Systemic biomarkers provide insights into disease pathogenesis, diagnosis, and risk stratification. Many systemic biomarker concentrations are heritable phenotypes. Genome-wide association studies (GWAS) provide mechanisms to investigate the genetic contributions to biomarker variability unconstrained by current knowledge of physiological relations.

METHODS

We examined the association of Affymetrix 100K GeneChip single nucleotide polymorphisms (SNPs) to 22 systemic biomarker concentrations in 4 biological domains: inflammation/oxidative stress; natriuretic peptides; liver function; and vitamins. Related members of the Framingham Offspring cohort (n = 1012; mean age 59 +/- 10 years, 51% women) had both phenotype and genotype data (minimum-maximum per phenotype n = 507-1008). We used Generalized Estimating Equations (GEE), Family Based Association Tests (FBAT) and variance components linkage to relate SNPs to multivariable-adjusted biomarker residuals. Autosomal SNPs (n = 70,987) meeting the following criteria were studied: minor allele frequency > or = 10%, call rate > or = 80% and Hardy-Weinberg equilibrium p > or = 0.001.

RESULTS

With GEE, 58 SNPs had p < 10(-6): the top SNPs were rs2494250 (p = 1.00*10(-14)) and rs4128725 (p = 3.68*10(-12)) for monocyte chemoattractant protein-1 (MCP1), and rs2794520 (p = 2.83*10(-8)) and rs2808629 (p = 3.19*10(-8)) for C-reactive protein (CRP) averaged from 3 examinations (over about 20 years). With FBAT, 11 SNPs had p < 10(-6): the top SNPs were the same for MCP1 (rs4128725, p = 3.28*10(-8), and rs2494250, p = 3.55*10(-8)), and also included B-type natriuretic peptide (rs437021, p = 1.01*10(-6)) and Vitamin K percent undercarboxylated osteocalcin (rs2052028, p = 1.07*10(-6)). The peak LOD (logarithm of the odds) scores were for MCP1 (4.38, chromosome 1) and CRP (3.28, chromosome 1; previously described) concentrations; of note the 1.5 support interval included the MCP1 and CRP SNPs reported above (GEE model). Previous candidate SNP associations with circulating CRP concentrations were replicated at p < 0.05; the SNPs rs2794520 and rs2808629 are in linkage disequilibrium with previously reported SNPs. GEE, FBAT and linkage results are posted at http://www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?id=phs000007 webcite.

CONCLUSION

The Framingham GWAS represents a resource to describe potentially novel genetic influences on systemic biomarker variability. The newly described associations will need to be replicated in other studies.

Chemokines and Chemokine Receptors in Scleroderma

Scleroderma is a connective tissue disease with unknown etiology characterized by excessive deposition of extracellular matrix in the skin. Cellular infiltrates of certain immune cells and proinflammatory mediators are suggested to play a crucial role in cutaneous fibrosis, forming complicated networks between fibroblasts and immune cells via cell-cell communications. Tissue-selective trafficking of leukocytes is mediated by combinations of adhesion molecules and chemokines. Recent studies have shown that an increase in proinflammatory chemokines has been associated with the initiation and/or development of skin fibrosis/sclerosis, suggesting that chemokines and their receptors may be important mediators of inflammation and fibrosis in scleroderma. This review will focus on the roles of chemokines and their receptors during the process of cutaneous sclerosis and will also provide a current insight into the potential mechanisms of scleroderma.

Stem cell factor expression, mast cells and inflammation in asthma

The Kit ligand SCF or stem cell factor (SCF) is a multipotent growth factor, acting as an important growth factor for human mast cells. SCF induces chemotaxis and survival of the mast cell, as well as proliferation and differentiation of immature mast cells from CD34(+) progenitors. Additionally, SCF enhances antigen-induced degranulation of human lung-derived mast cells, and induces a mast cell hyperplasia after subcutaneous administration. SCF expression increases in the airways of asthmatic patients, and this is reversed after treatment with glucocorticoids. A role for SCF may thus be hypothesized in diseases associated with a local increase in the number and/or activation of mast cells, as occurring in the airways in asthma. SCF will be reviewed as a potential therapeutic target in asthma, to control the regulation of mast cell number and activation. We here report the main pathways of SCF synthesis and signalling, and its potential role on airway function and asthma.

Generation and characterization of bone marrow-derived cultured canine mast cells

Disorders of mast cells, particularly mast cell tumors (MCTs), are common in dogs. There now is evidence that many of these disorders exhibit breed predilections, suggesting an underlying heritable component. In comparison to humans and mice, little is known regarding the biology of canine mast cells. To facilitate the study of mast cell biology in other species, bone marrow-derived cultured mast cells (BMCMCs) often are used because these represent a ready source of large numbers of cells. We have developed a protocol to successfully generate canine BMCMCs from purified CD34(+) cells. After 5-7 weeks of culture with recombinant canine stem cell factor (rcSCF), greater than 90% of the cell population consisted of mast cells as evidenced by staining with Wright's-Giemsa, as well as production of chymase, tryptase, IL-8 and MCP-1. These cells expressed cell surface markers typical of mast cells including Kit, Fc epsilonRI, CD44, CD45 and CD18/CD11b. The canine BMCMCs were dependent on rcSCF for survival and proliferation, and migrated in response to rcSCF gradients. Cross-linking of cell surface-bound IgE induced the release of histamine and TNFalpha. Histamine release could also be stimulated by ConA, compound 48/80, and calcium ionophore. In summary, canine BMCMCs possess phenotypic and functional properties similar to mast cells found in vivo. These cells represent a novel, valuable resource for investigating normal canine mast cell biology as well as for identifying factors that lead to mast cell dysregulation in the dog.

Inhibition of SCF attenuates peribronchial remodeling in chronic cockroach allergen-induced asthma

The progression and severity of chronic asthma likely depends upon the intensity of the damage and remodeling of the tissue. We have developed a chronic model of allergic asthma using multiple cockroach allergen challenges. Using this clinically relevant allergen we have established significant peribronchial fibrosis and mucus overproduction. These remodeling events are accompanied by intense peribronchial inflammation, including lymphocytes and eosinophils. A cytokine that has been identified as having a prominent role in short-term allergic events, stem cell factor (SCF), appears to have a significant role in this late-stage process. Using our polyclonal antibody specific for SCF administered into the airways of mice during the final allergen challenges, we find a significant effect on the chronic peribronchial allergen-induced fibrotic remodeling. This was characterized by reduced inflammation, especially eosinophils, as well as reduced hydroxyproline levels in anti-SCF compared to control antibody-treated animals. In addition, when we examined chemokines associated with the chronic disease and neutralized SCF in vivo we observed a corresponding decrease in CCL6 and CCL17. Using an inhibitor, imatinib mesylate, that blocks SCF/c-kit-associated RTK, we find similar results as with anti-SCF for attenuating AHR and fibrotic changes, suggesting that a potential clinical treatment for chronic asthma already exists related to this pathway. These results further support the potential use of SCF/c-kit inhibition for targeting chronic severe asthmatic responses.

Stem cell factor and its receptor c-Kit as targets for inflammatory diseases

Stem cell factor (SCF), the ligand of the c-Kit receptor, is expressed by various structural and inflammatory cells in the airways. Binding of SCF to c-Kit leads to activation of multiple pathways, including phosphatidyl-inositol-3 (PI3)-kinase, phospholipase C (PLC)-gamma, Src kinase, Janus kinase (JAK)/Signal Transducers and Activators of Transcription (STAT) and mitogen activated protein (MAP) kinase pathways. SCF is an important growth factor for mast cells, promoting their generation from CD34+ progenitor cells. In vitro, SCF induces mast cells survival, adhesion to extracellular matrix and degranulation, leading to expression and release of histamine, pro-inflammatory cytokines and chemokines. SCF also induces eosinophil adhesion and activation. SCF is upregulated in inflammatory conditions both in vitro and in vivo, in human and mice. Inhibition of the SCF/c-Kit pathway leads to significant decrease of histamine levels, mast cells and eosinophil infiltration, interleukin (IL)-4 production and airway hyperresponsiveness in vivo. Taken together, these data suggest that SCF/c-Kit may be a potential therapeutic target for the control of mast cell and eosinophil number and activation in inflammatory diseases.

PGE1analog alprostadil induces VEGF and eNOS expression in endothelial cells

Endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor 1-α (HIF-1α) are important regulators of endothelial function, which plays a role in the pathophysiology of heart failure (HF). PGE1analog treatment in patients with HF elicits beneficial hemodynamic effects, but the precise mechanisms have not been investigated. We have investigated the effects of the PGE1analog alprostadil on eNOS, VEGF, and HIF-1α expression in human umbilical vein endothelial cells (HUVEC) using RT-PCR and immunoblotting under normoxic and hypoxic conditions. In addition, we studied protein expression by immunohistochemical staining in explanted hearts from patients with end-stage HF, treated or untreated with systemic alprostadil. Alprostadil causes an upregulation of eNOS and VEGF protein and mRNA expression in HUVEC and decreases HIF-1α. Hypoxia potently increased eNOS, VEGF, and HIF-1α synthesis. The alprostadil-induced upregulation of eNOS and VEGF was prevented by inhibition of MAPKs with PD-98056 or U-0126. Consistently, the expression of eNOS and VEGF was increased, and HIF-1α was reduced in failing hearts treated with alprostadil. The potent effects of alprostadil on endothelial VEGF and eNOS synthesis may be useful for patients with HF where endothelial dysfunction is involved in the disease process.

The role of human mast cell-derived cytokines in eosinophil biology

Eosinophil-mediated diseases, such as allergic asthma, eosinophilic fasciitis, and certain hypersensitivity pulmonary disorders, are characterized by eosinophil infiltration and tissue injury. Mast cells and T cells often colocalize to these areas. Recent data suggest that mast cells can contribute to eosinophil-mediated inflammatory responses. Activation of mast cells can occur by antigen and immunoglobulin E (IgE) via the high-affinity receptor (FcepsilonRI) for IgE. The liberation of proteases, leukotrienes, lipid mediators, and histamine can contribute to tissue inflammation and allow recruitment of eosinophils to tissue. In addition, the synthesis and expression of a plethora of cytokines and chemokines (such as granulocyte-macrophage colony-stimulating factor [GM-CSF], interleukin-1 [IL-1], IL-3, IL-5, tumor necrosis factor-alpha [TNF-alpha], and the chemokines IL-8, regulated upon activation normal T cell expressed and secreted [RANTES], monocyte chemotactic protein-1 [MCP-1], and eotaxin) by mast cells can influence eosinophil biology. Stem cell factor (SCF)-c-kit, cytokine-cytokine receptor, and chemokine-chemokine receptor (CCR3) interactions leading to nuclear factor kappaB (NF-kappaB), mitogen-activated protein kinase (MAPK) expression, and other signaling pathways can modulate eosinophil function. Eosinophil hematopoiesis, activation, survival, and elaboration of mediators can all be regulated thus by mast cells in tissue. Moreover, because eosinophils can secrete SCF, eosinophils can regulate mast cell function in a paracrine manner. This two-way interaction between eosinophils and mast cells can pave the way for chronic inflammatory responses in a variety of human diseases. This review summarizes this pivotal interaction between human mast cells and eosinophils.

Role of human mast cells and basophils in bronchial asthma

Mast cells and basophils are the only cells expressing the tetrameric (alphabetagamma2) structure of the high affinity receptor for IgE (FcepsilonRI) and synthesizing histamine in humans. Human FcepsilonRI+ cells are conventionally considered primary effector cells of bronchial asthma. There is now compelling evidence that these cells differ immunologically, biochemically, and pharmacologically, which suggests that they might play distinct roles in the appearance and fluctuation of the asthma phenotype. Recent data have revealed the complexity of the involvement of human mast cells and basophils in asthma and have shed light on the control of recruitment and activation of these cells in different lung compartments. Preliminary evidence suggests that these cells might not always be detrimental in asthma but, under some circumstances, they might exert a protective effect by modulating certain aspects of innate and acquired immunity and allergic inflammation.

Inhibition of stem cell factor reduces pulmonary cytokine levels during allergic airway responses

Stem cell factor (SCF) has a significant role in the inflammation and activation of allergic airway responses. When monoclonal anti-SCF was administered intratracheally during allergen challenge there was a significant alteration of eosinophil accumulation and airway hyperreactivity (AHR). Anti-SCF treatment also attenuated pulmonary cytokine and chemokine levels. In particular, there was an antibody dose-dependent decrease in interleukin (IL)-5 and tumour necrosis factor (TNF)-alpha. There was also a significant reduction of CCL2 and CCL5, which correlated with the reduction in AHR. Mice treated with anti-SCF demonstrated a significant decrease in pulmonary gob-5 gene expression, which has been shown to correlate to goblet cell hyperplasia/metaplasia relating to airway mucus production. Blocking SCF-mediated activation within the airway using a monoclonal antibody indicates that this cytokine may represent a viable target for therapeutic intervention that could affect multiple aspects of allergen-induced immunopathology.

Role of immunoreactions and mast cells in pathogenesis of human endometriosis -morphologic study and gene expression analysis-

STUDY OBJECTIVES

To investigate the pathophysiology of human endometriosis, we examined by morphological and molecular biological methods.

METHODS

Samples of ovarian endometriosis and normal ovarian tissues were obtained laparoscopically after informed consent. A morphological study by toluidine blue staining, immunohistochemistry of c-kit and electron microscopy demonstrated the localization of mast cells in the stromal lesions of endometriosis. Oligonucleotide microarrays were used for gene expression analysis.

RESULTS

Infiltration of numerous mast cells and development of fibrosis was observed throughout the stromal lesions. Gene expression analysis by oligonucleotide microarrays indicated inflammatory immunoreactions in the lesions. Expressions of the FCER1G and PGDS, which are considered to be mast cell-specific genes, were upregulated in the ovarian endometriotic lesions as compared to the normal ovarian tissues. Furthermore, expressions of genes associated with immunological inflammation, such as IL-8, GRO1, GRO2, CXCR4, MCP1, and those related to tissue remodeling (MMP, COL4A2, and COL5A2) were also higher in endometriotic lesions than in the normal ovarian tissue.

CONCLUSIONS

Thus it is likely that mast cells and their related inflammatory immunoreactions via chemokines play important roles in producing fibrosis and adhesions in endometriotic lesions.

Preferential signaling and induction of allergy-promoting lymphokines upon weak stimulation of the high affinity IgE receptor on mast cells

Mast cell degranulation and de novo cytokine production is a consequence of antigen-aggregation of the immunoglobulin E (IgE)-occupied high affinity receptor for IgE (Fc epsilon RI). Herein, we report that lymphokines that promote allergic inflammation, like MCP-1, were potently induced at low antigen (Ag) concentrations or at low receptor occupancy with IgE whereas some that down-regulate this response, like interleukin (IL)-10, required high receptor occupancy. Weak stimulation of mast cells caused minimal degranulation whereas a half-maximal secretory response was observed for chemokines and, with the exception of TNF-alpha, a weaker cytokine secretory response was observed. The medium from weakly stimulated mast cells elicited a monocyte/macrophage chemotactic response similar to that observed at high receptor occupancy. Weak stimulation also favored the phosphorylation of Gab2 and p38MAPK, while LAT and ERK2 phosphorylation was induced by a stronger stimulus. Gab2-deficient mast cells were severely impaired in chemokine mRNA induction whereas LAT-deficient mast cells showed a more pronounced defect in cytokines. These findings demonstrate that perturbation of small numbers of IgE receptors on mast cells favors certain signals that contribute to a lymphokine response that can mediate allergic inflammation.

Simvastatin reduces the expression of adhesion molecules in circulating monocytes from hypercholesterolemic patients

OBJECTIVE

The intercellular adhesion molecule-1 (ICAM-1/CD54) and its ligand, CD11a/CD18, mediate endothelial adhesion of leukocytes and their consecutive transmigration. Anti-inflammatory effects of statins are considered to be exerted in part through inhibition of leukocyte-endothelial interactions. We investigated the in vivo effects of simvastatin treatment in hypercholesterolemic patients and the influence of various statins on expression of cellular adhesion molecules in vitro.

METHODS AND RESULTS

A total number of 107 hypercholesterolemic patients were treated with 20 mg (n=52) or 40 mg (n=55) of simvastatin daily. After 6 weeks of treatment, peripheral blood mononuclear cells (PBMCs) expressed lower amounts of CD54-, CD18-, and CD11a-mRNA compared with pretreatment values. Surface expression of CD54 and CD18/CD11a on CD14+-monocytes also decreased significantly in both groups of patients. Moreover, simvastatin, atorvastatin, and cerivastatin were found to downregulate tumor necrosis factor (TNF)-alpha-induced expression of CD54 and CD18/CD11a in isolated PBMCs obtained from normal donors as well as TNF-alpha-dependent expression of these CAMs in cultured human umbilical vein endothelial cells (HUVECs). Furthermore, all three statins were found to reduce the binding of PBMCs to TNF-alpha-stimulated HUVECs in vitro.

CONCLUSIONS

Statin-induced inhibition of expression of CD54 and CD18/CD11a in PBMCs and HUVECs with consecutive loss of adhesive function may contribute to the anti-inflammatory effects of these drugs and some of their beneficial clinical activities.

Constitutive secretion of the granule chymase mouse mast cell protease-1 and the chemokine, CCL2, by mucosal mast cell homologues

BACKGROUND

The mucosal mast cell (MMC) granule-specific beta-chymase, mouse mast cell protease-1 (mMCP-1), is released systemically into the bloodstream early in nematode infection before parasite-specific IgE responses develop and TGF-beta1 induces constitutive release of mMCP-1 by homologues of MMC in vitro. Intraepithelial MMC may also express the chemokine CCL2 (monocyte chemotactic protein-1) during nematode infection but the expression of this chemokine by MMC homologues has not been investigated.

OBJECTIVE

To investigate the expression and to compare the mechanisms of constitutive release of the chymase, mMCP-1, and the chemokine, CCL2.

METHODS

MMC homologues were generated by culturing bone marrow cells in the presence of TGF-beta1, IL-3, IL-9 and stem cell factor (SCF). The intracellular distribution of mMCP-1 and CCL2 was examined by confocal microscopy. The involvement of the Golgi complex and of protein synthesis in the constitutive release of mMCP-1 and CCL2 was investigated using the Golgi-disrupting agent brefeldin A and cycloheximide to block protein synthesis. Secreted analytes were quantified by ELISA.

RESULTS

mMCP-1 colocalized with Golgi matrix protein 130 but was most abundant in the granules, whereas CCL2 was not found in the granules but appeared to be located uniquely in the Golgi complex. Extracellular release of mMCP-1 was significantly inhibited ( approximately 40%) by cycloheximide and by the Golgi-disrupting agent brefeldin A, indicating both continuous protein synthesis and transportation via the Golgi complex are required for optimal mMCP-1 secretion. A similar but more marked inhibitory effect with both compounds was demonstrated on the constitutive secretion of CCL2.

CONCLUSION

The culture conditions that promote mMCP-1 expression and release by MMC homologues also promote the expression and release of CCL2. Constitutive release involves de novo protein synthesis and requires a functional Golgi complex, suggesting that similar mechanisms of extracellular secretion operate for both mediators.

Simvastatin reduces expression of cytokines interleukin-6, interleukin-8, and monocyte chemoattractant protein-1 in circulating monocytes from hypercholesterolemic patients

OBJECTIVE

A number of studies have shown that statins decrease morbidity and mortality in patients with cardiovascular diseases. The anti-inflammatory effects of statins have recently been implicated in the clinical benefit that can be obtained in the treatment of atherosclerosis. Little is known about the mechanisms by which statins counteract inflammation.

METHODS AND RESULTS

In this study, we asked whether simvastatin can influence in vitro and in vivo production of the proinflammatory cytokines interleukin (IL)-6, IL-8, and monocyte chemoattractant protein-1. A total of 107 hypercholesterolemic patients were treated with simvastatin. As measured by ELISA, serum levels of cytokines significantly decreased after 6 weeks of treatment (P<0.05). Furthermore, simvastatin decreased the expression of IL-6, IL-8, and monocyte chemoattractant protein-1 mRNA in peripheral blood mononuclear cells. Similar results were obtained in vitro by using cultured human umbilical vein endothelial cells and peripheral blood mononuclear cells from healthy normolipemic donors. Exposure to simvastatin, atorvastatin, or cerivastatin caused downregulation of the expression of cytokine mRNA in a time- and dose-dependent manner. Furthermore, all statins tested were able to reduce the concentrations of cytokines in cellular and extracellular fractions of human umbilical vein endothelial cells (P<0.05).

CONCLUSIONS

Our data show that simvastatin is anti-inflammatory through the downregulation of cytokines in the endothelium and leukocytes. These effects may explain some of the clinical benefits of these drugs in the treatment of atherosclerosis.

Chemokine and cytokine expression in murine intestinal epithelium following Nippostrongylus brasiliensis infection

Infection of mice with the nematode parasite Nippostrongylus brasiliensis results in a well characterized intestinal mastocytosis with intraepithelial migration of mucosal mast cells (MMC). The molecules mediating this response are unknown. We examined expression of several putative mast cell chemoattractants in intestinal epithelium following N. brasiliensis infection. Expression of the chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1 alpha (MIP-1alpha), RANTES (regulated on activation normal T-cell expressed and secreted), fractalkine, and thymocyte expressed chemokine (TECK); and the cytokines stem cell factor (SCF) and transforming growth factor beta1 (TGFbeta1), was constitutive and no alteration was detected following infection. MCP-1 expression was also constitutive but at much lower levels and increased expression was detected on days 7 and 14 postinfection. Expression of MCP-1 in whole jejunum was at much higher levels than in epithelium. Constitutive expression of MCP-1, MIP-1alpha and TGFbeta1 was also detected in cultured bone marrow-derived homologues of MMC. In an intestinal epithelial cell line (CMT-93), there was constitutive expression of SCF, TGFalpha1, fractalkine and MCP-1. The results show that, in vivo, epithelium is a potentially important source of mast cell chemoattractants.

Expression, epitope analysis, and functional role of the LFA-2 antigen detectable on neoplastic mast cells

Recent data suggest that mast cells (MCs) in patients with systemic mastocytosis or mast cell leukemia express a CD2-reactive antigen. To explore the biochemical nature and function of this antigen, primary MCs as well as the MC line HMC-1 derived from a patient with mast cell leukemia were examined. Northern blot experiments revealed expression of CD2 messenger RNA in HMC-1, whereas primary nonneoplastic MCs did not express transcripts for CD2. In cell surface staining experiments, bone marrow (BM) MCs in systemic mastocytosis (n = 12) as well as HMC-1 cells (30%-80%) were found to express the T11-1 and T11-2 (but not T11-3) epitopes of CD2. By contrast, BM MCs in myelodysplastic syndromes and nonhematologic disorders (bronchiogenic carcinoma, foreskin phimosis, uterine myeomata ) were consistently CD2(-). All MC species analyzed including HMC-1 were found to express LFA-3 (CD58), the natural ligand of CD2. To study the functional role of CD2 on neoplastic MCs, CD2(+) and CD2(-) HMC-1 cells were separated by cell sorting. CD2(+) HMC-1 cells were found to form spontaneous aggregates and rosettes with sheep erythrocytes in excess over CD2(-) cells, and a T11-1 antibody inhibited both the aggregation and rosette formation. Moreover, exposure of CD2(+) HMC-1 cells to T11-1 or T11-2 antibody was followed by expression of T11-3. In addition, stimulation of neoplastic MCs through T11-3 and a second CD2 epitope resulted in histamine release. These data show that neoplastic MCs express functionally active CD2. It is hypothesized that expression of CD2 is associated with pathologic accumulation and function of MCs in systemic mastocytosis.

Protection from pulmonary fibrosis in the absence of CCR2 signaling

Pulmonary fibrosis can be modeled in animals by intratracheal instillation of FITC, which results in acute lung injury, inflammation, and extracellular matrix deposition. We have previously shown that despite chronic inflammation, this model of pulmonary fibrosis is lymphocyte independent. The CC chemokine monocyte-chemoattractant protein-1 is induced following FITC deposition. Therefore, we have investigated the contribution of the main monocyte-chemoattractant protein-1 chemokine receptor, CCR2, to the fibrotic disease process. We demonstrate that CCR2(-/-) mice are protected from fibrosis in both the FITC and bleomycin pulmonary fibrosis models. The protection is specific for the absence of CCR2, as CCR5(-/-) mice are not protected. The protection is not explained by differences in acute lung injury, or the magnitude or composition of inflammatory cells. FITC-treated CCR2(-/-) mice display differential patterns of cellular activation as evidenced by the altered production of cytokines and growth factors following FITC inoculation compared with wild-type controls. CCR2(-/-) mice have increased levels of GM-CSF and reduced levels of TNF-alpha compared with FITC-treated CCR2(+/+) mice. Thus, CCR2 signaling promotes a profibrotic cytokine cascade following FITC administration.

Gene expression screening of human mast cells and eosinophils using high-density oligonucleotide probe arrays: abundant expression of major basic protein in mast cells

Mast cells (MCs) and eosinophils are thought to play important roles in evoking allergic inflammation. Cell-type--specific gene expression was screened among 12,000 genes in human MCs and eosinophils with the use of high-density oligonucleotide probe arrays. In comparison with other leukocytes, MCs expressed 140 cell-type--specific transcripts, whereas eosinophils expressed only 34. Among the transcripts for expected MC-specific proteins such as tryptase, major basic protein (MBP), which had been thought to be eosinophil specific, was ranked fourth in terms of amounts of increased MC-specific messenger RNA. Mature eosinophils were almost lacking this transcript. MCs obtained from 4 different sources (ie, lung, skin, adult peripheral blood progenitor--derived and cord blood progenitor--derived MCs, and eosinophils) were found to have high protein levels of MBP in their granules with the use of flow cytometric and confocal laser scanning microscopic analyses. The present finding that MCs can produce abundant MBP is crucial because many reports regarding allergic pathogenesis have been based on earlier findings that MBP was almost unique to eosinophils and not produced by MCs. (Blood. 2001;98:1127-1134)

Role of stem cell factor and monocyte chemoattractant protein-1 in the interaction between fibroblasts and mast cells in fibrosis

Mast cell infiltration and accumulation is known to occur in tissue fibrosis. Increased numbers of mast cells are detected in scleroderma or hypertrophic scar skin, however, neither the role of mast cells nor the interaction of fibroblasts and mast cells in fibrosis are fully understood. A growing body of evidence indicate that mast cells are rich source of cytokines, growth factors or chemokines, which are suggested to play an important role in the induction of fibrosis. Recent in vivo and in vitro studies suggest the involvement of monocyte chemoattractant protein-1 (MCP-1), a member of the C-C chemokine family, in fibrosis. Here, we examined the effect of stem cell factor (SCF), a mast cell growth factor, on MCP-1 gene expression in a human mast cell line, HMC-1, and as well as the effect of MCP-1 on alpha1(I) collagen gene expression in human skin fibroblasts. HMC-1 cells spontaneously expressed MCP-1 mRNA transcripts, which was detectable by in situ hybridization and Northern blot analysis. Stimulation with SCF further upregulated MCP-1 mRNA expression in a time- and dose-dependent manner, and stimulation with 100 ng/ml SCF for 24 h induced a 3-fold increase of MCP-1 mRNA expression in HMC-1 cells as compared with unstimulated cells. The concentration of MCP-1 protein in the culture supernatants of 50 ng/ml SCF-stimulated HMC-1 cells (3816+/-70 pg/ml) was significantly elevated compared to unstimulated cells (2588+/-130 pg/ml) (P < 0.01), as assessed by ELISA. Adversely, MCP-1 induced alpha1(I) collagen mRNA expression in normal skin fibroblasts dose-dependently. Finally, comparative study revealed that the concentration of SCF in the culture supernatants of scleroderma fibroblasts at primary passages was significantly increased (344.6+/-182.4 pg/ml), as compared with normal skin fibroblasts (72.4+/-20.2 pg/ml) (P<0.05). These results suggest that fibroblast-derived SCF upregulates MCP-1 expression and synthesis in mast cells, which acts on fibroblasts to enhance alpha1(I) collagen mRNA expression. Our data may indicate an important interaction of fibroblasts and mast cells, via SCF and MCP-1, in the induction of fibrosis.

Immunohistochemical study of hepatic oval cells in human chronic viral hepatitis

AIM: To detect immunohistochemically the presence of oval cells in chronic viral hepatitis with antibody against c-kit.

METHODS: We detected oval cells in paraffin embedded liver sections of 3 normal controls and 26 liver samples from patients with chronic viral hepatitis, using immunohistochemistry with antibodies against c-kit, π class glutathione S-transferase (π-GST) and cytokeratins 19 (CK19).

RESULTS: Oval cells were not observed in normal livers. In chronic viral hepatitis, hepatic oval cells were located predominantly in the periportal region and fibrosis septa, characterized by an ovoid nucleus, small size, and scant cytoplasm. Antibody against stem cell factor receptor, c-kit, had higher sensitivity and specificity than π-GST and CK19. About 50%-70% of c-kit positive oval cells were stained positively for either π-GST or CK19.

CONCLUSION: Oval cells are frequently detected in human livers with chronic viral hepatitis, suggesting that oval cell proliferation is asso ciated with the liver regeneration in this condition.

Regulation of the inflammatory response in asthma by mast cell products

In airways, mast cells lie adjacent to nerves, blood vessels and lymphatics, which highlights their pivotal importance in regulating allergic inflammatory processes. In asthma, mast cells are predominantly activated by IgE receptor cross linking. In response to activation, preformed mediators that are stored bound to proteoglycans, for example, TNF-alpha, IL-4, IL-13, histamine, tryptase and chymase, are released. New synthesis of arachidonic acid metabolites (leukotriene C4 (LTC4), leukotriene B4 (LTB4) and prostaglandin D2 (PGD2)) and further cytokines is stimulated. Mediators from degranulating mast cells are critical to the pathology of the asthmatic lung. Mast cell proteases stimulate tissue remodelling, neuropeptide inactivation and enhanced mucus secretion. Histamine stimulates smooth muscle cell contraction, vasodilatation and increased venular permeability and further mucus secretion. Histamine induces IL-16 production by CD8+ cells and airway epithelial cells; IL-16 is an important early chemotactic factor for CD4+ lymphocytes. LTC4, LTB4 and PGD2 affect venular permeability and can regulate the activation of immune cells. The best characterized mast cell cytokine in asthmatic inflammation is TNF-alpha, which induces adhesion molecules on endothelial cells and subsequent transmigration of inflammatory leucocytes. IL-13 is critical to development of allergic asthma, although its mode of action is less clear.

Chemokine production by G protein-coupled receptor activation in a human mast cell line: roles of extracellular signal-regulated kinase and NFAT

Chemoattractants are thought to be the first mediators generated at sites of bacterial infection. We hypothesized that signaling through G protein-coupled chemoattractant receptors may stimulate cytokine production. To test this hypothesis, a human mast cell line (HMC-1) that normally expresses receptors for complement components C3a and C5a at low levels was stably transfected to express physiologic levels of fMLP receptors. We found that fMLP, but not C3a or C5a, induced macrophage inflammatory protein (MIP)-1ss (CCL4) and monocyte chemoattractant protein-1 (CCL2) mRNA and protein. Although fMLP stimulated both sustained Ca(2+) mobilization and phosphorylation of extracellular signal-regulated kinase (ERK), these responses to C3a or C5a were transient. However, transient expression of C3a receptors in HMC-1 cells rendered the cells responsive to C3a for sustained Ca(2+) mobilization and MIP-1ss production. The fMLP-induced chemokine production was blocked by pertussis toxin, PD98059, and cyclosporin A, which respectively inhibit G(i)alpha activation, mitgen-activated protein kinase kinase-mediated ERK phosphorylation, and calcineurin-mediated activation of NFAT. Furthermore, fMLP, but not C5a, stimulated NFAT activation in HMC-1 cells. These data indicate that chemoattractant receptors induce chemokine production in HMC-1 cells with a selectivity that depends on the level of receptor expression, the length of their signaling time, and the synergistic interaction of multiple signaling pathways, including extracellular signal-regulated kinase phosphorylation, sustained Ca(2+) mobilization and NFAT activation.

Effects of remifentanil on neutrophil adhesion, transmigration, and intercellular adhesion molecule expression

BACKGROUND

Anaesthetic drugs are used for pain therapy and anaesthesia. Neutrophils play a significant role during the process of inflammation. The aim of the current study was to investigate the effects of remifentanil and fentanyl on neutrophil migration through endothelial cell monolayers, and on adhesion molecule expression.

METHODS

After isolation of polymorphonuclear neutrophils (PMNL) we used a currently described migration assay. PMNL and/or endothelial cell monolayers (ECM) were pre-treated with remifentanil using clinically relevant, as well as higher and lower concentrations or relevant concentrations of fentanyl.

RESULTS

Concentrations of remifentanil (50 ng/mL) similar to the relevant plasma concentration were able to inhibit PMNL migration through ECM significantly (migration compared to the control 82+/-7% SD; P<0.05), when both cell types were treated with the synthetic narcotic remifentanil. Fentanyl (30 ng/mL) showed a stronger inhibitory effect (migration compared to the control 67+/-9.2%; P<0.05). Endothelial cell adhesion molecule expression was reduced after either remifentanil or fentanyl.

CONCLUSION

The results of the present investigation indicate that remifentanil influences interaction of ECM against human neutrophils. Compared to fentanyl, remifentanil seems to exhibit minor inhibitory effects on neutrophil migration.

Molecular consequences of human mast cell activation following immunoglobulin E-high-affinity immunoglobulin E receptor (IgE-FcepsilonRI) interaction

The cross-linking by immunoglobulin E of its high-affinity receptor, FcepsilonRI, on mast cells initiates a complex series of biochemical events leading to degranulation and the synthesis and secretion of eicosanoids and cytokines through the action of transcription factors, such as nuclear factor-kappaB. The initial activation involves the phosphorylation of FcepsilonRI beta- and gamma-subunits through the actions of the tyrosine kinases lyn and syk. For the purposes of description, the subsequent events may be grouped in three cascades characterized by the key proteins involved. First, the phospholipase C-inositol phosphate cascade activates protein kinase C and is largely responsible for calcium mobilization and influx. Second, activation of Ras and Raf via mitogen-activated protein kinase causes the production of arachidonic acid metabolites. Third, the generation of sphingosine and sphingosine-1-phosphate occurs through activation of sphingomyelinase. While the early signaling events tend to be specific for the cited cascades, there is an increasing overlap of activated proteins with the downstream propagation of the signal. It is the balanced interaction between these proteins that culminates in degranulation, synthesis, and release of eicosanoids and cytokines.

Rapid, fluorescence-based assay for microtiter plates to test drug influences on neutrophil transmigration through endothelial cell monolayers

Investigation of drug interactions between blood cells and endothelium is of high interest. The current study describes the development of a rapid fluorescence-based leukocyte transmigration system through endothelial cell monolayers for investigation of drug influences. To test the new assay, endothelial cells were cultured on microporous filters, pore size 3.0 microm, in 96-well-plates. Freshly isolated neutrophils were seeded on endothelial cell monolayers and transmigrated cells were measured after incubation for three hours. Migration of non-stimulated neutrophils through non-stimulated endothelial cell monolayer was used as control and set as 100%. The influence of the non-steroidal anti-inflammatory drug diclofenac was investigated. Assay precision tests were done using intraassay (within-day variability) and interassay (day-to-day variability) controls. Transmigration rate was decreased to 53 +/- 6.8% SD (diclofenac 0.7 microg/mL). Different concentrations showed a dose dependent effect (0.07 microg/mL: 97 +/- 9.5%, 7 microg/mL: 37 +/- 4.7%). Analysis of assay accuracy of the new 96-well-sized transmigration assay showed reliable results (coefficient of variation: intraassay 8.2 %; interassay 11.8%). In conclusion, this new, rapid, and sample saving 96-well-microtiter transmigration assay allows examination of drug influence on neutrophil migration through endothelial cell monolayers. Moreover, this assay can also be used for other cell-cell interactions.

Oral contraceptives that contain ethinyl estradiol (0.035 mg) and cyproterone acetate (2 mg) inhibit leukocyte transmigration through endothelial cell monolayers

OBJECTIVE

To investigate the influence of ethinyl estradiol and cyproterone acetate in oral contraceptives on leukocyte migration through endothelial cell monolayers.

DESIGN

Experimental in vitro prospective study.

SETTING

An academic research laboratory.

INTERVENTION(S)

Endothelial cells were cultured on microporous membranes to produce monolayers. Polymorphonuclear leukocytes were used in a previously described migration assay (n = 7). The amount of untreated polymorphonuclear leukocytes that migrated through untreated endothelial cell monolayers was used as a control and set at 100%. In addition, a leukocyte adhesion assay was used.

MAIN OUTCOME MEASURE(S)

Leukocyte adhesion to and transmigration through endothelial cell monolayers.

RESULT(S)

Ethinyl estradiol and cyproterone acetate inhibited the migration of polymorphonuclear leukocytes through endothelial cell monolayers significantly (67% +/- 6.4%) when both cell types were treated to simulate in vivo conditions. The adhesion assay produced similar results.

CONCLUSION(S)

Ethinyl estradiol and cyproterone acetate were identified as potent inhibitors of leukocyte migration through endothelial cell monolayers.

Amoxycillin/clavulanic acid combinations increase transmigration of leucocytes through endothelial cell monolayers: endothelial cells play a key role

Postoperative inflammation is still viewed as an unresolved problem. During inflammation, leucocytes play a tremendous role and migrate from intravascular spaces into the tissue to attack microorganisms. Different agents, e.g. anaesthetic drugs, are able to influence leucocyte recruitment. Previous studies have investigated the influence of amoxycillin on chemotaxis of leucocytes alone. The aim of our study was to examine the effect of amoxycillin/clavulanic acid (co-amoxiclav) on leucocyte migration through endothelial cell monolayers (ECMs). Human umbilical endothelial cells were cultured on microporous membranes, achieving a monolayer. Polymorphonuclear neutrophil leucocytes (PMNLs) were used in a migration assay. The numbers of untreated PMNLs migrating through untreated ECMs were used as control and set as 100%. PMNLs and/or ECMs were pretreated with co-amoxiclav using clinically relevant as well as higher and lower concentrations. Co-amoxiclav was able to increase PMNL migration through ECMs significantly (P<0.05) when both cell types were treated (291+/-18.7%). When PMNLs or ECMs were treated alone, it could be shown that ECMs were more affected than PMNLs. The greatest effect was shown when both cell types, PMNLs and ECMs, were treated. In conclusion, co-amoxiclav was identified as a potent drug to increase leucocyte transmigration through ECMs. ECMs were also critically involved. Co-amoxiclav also affects endothelial cells.

Propofol reduces the migration of human leukocytes through endothelial cell monolayers

OBJECTIVE

To test propofol and the solvent of propofol on leukocyte function in the presence of endothelial cell monolayers. The interactions of leukocytes with endothelial cells play a tremendous role during inflammation. Previous studies have investigated the influence of propofol on leukocytes.

DESIGN

Prospective, controlled study.

SETTING

University research laboratories.

SUBJECTS

Seven independent experiments were performed to investigate the influence of propofol (0.4, 4, and 40 ng/mL) on the migration of human leukocytes through human endothelial cell monolayers. Moreover, the authors tested the solvent of propofol on leukocyte migration.

INTERVENTIONS

Human endothelial cell monolayers and/or human leukocytes were preincubated with clinically relevant higher and lower concentrations of propofol. The amount of leukocyte migration after 3 hrs was measured with a fluorometer.

MEASUREMENTS AND MAIN RESULTS

Human endothelial cells isolated from umbilical veins were cultured on microporous membranes until they formed an endothelial cell monolayer. Leukocytes were separated by standard procedures. The migration of leukocytes through monolayers of endothelial cells using the clinically relevant concentration of propofol was reduced to 93% +- 3.8% (so; p < .05) when the leukocytes but not the endothelial cell monolayers were preincubated with propofol. Leukocyte migration was reduced to 80% - 5.9% (p < .05) when only monolayers of endothelial cells were treated with propofol, and was reduced to 73% + 10.4% (p < .05) when both leukocytes and monolayers of endothelial cells were treated with propofol. The higher and lower concentrations showed a dose-dependent effect. The solvent of propofol had no significant effect.

CONCLUSION

The authors investigated the influence of propofol and its solvent on the interaction between both cell systems-leukocytes and endothelial cells. Propofol is able to reduce significantly the migration of leukocytes through endothelial cell monolayers. The use of different doses revealed a dose-dependent effect. The current model allowed treatment of one cell type: leukocyte or endothelial cell. The results of this investigation indicate that the influence of propofol on leukocyte migration affects endothelial cells more than leukocytes.

Mast cells in rapidly progressive glomerulonephritis

The role of mast cells (MC) in tubulointerstitial damage in glomerulonephritis (GN) is not fully understood. The distribution of MC was compared in renal biopsies from 50 patients with different stages of rapidly progressive GN (RPGN) and in 20 control samples. The immunoreactivity of renal MC with anti-tryptase and anti-chymase antibodies was studied. Interstitial myofibroblasts were stained with anti-alpha-smooth muscle actin (alpha-SMA) antibody, and inflammatory cells were identified by anti-CD3, -CD20, and -CD68 monoclonal antibodies. Positively stained cells were counted, and the relative interstitial and fractional areas of anti-alpha-SMA-stained cells were measured. MC were rarely found in control samples. In contrast, samples showing crescentic GN contained numerous tryptase-positive MC (MC(T)) (43.7+/-4.65 versus 7.14+/-1.3/mm2) and fewer tryptase- and chymase-positive MC (MC(TC)) (13.8+/-1.86 versus 1.89+/-0.86/mm2) in the renal interstitium but never in the glomerulus. Double immunostaining demonstrated the presence of both phenotypes of MC. Accumulation of MC was significantly correlated with the numbers of T lymphocytes (MC(T), r = 0.67) and interstitial macrophages (MC(T), r = 0.455). There was also a significant correlation between the number of MC(T) and the relative interstitial area. The number of MC(TC) was well correlated with the fractional area of alpha-SMA-positive interstitium (r = 0.749) and the percentage of the interstitial fibrotic area (r = 0.598). There was also a significant negative correlation between interstitial MC(TC) accumulation and creatinine clearance (r = 0.661). The density of MC(TC) was higher (1.4-fold) in advanced forms of GN associated with fibrocellular crescents and interstitial fibrosis. These results show the potential involvement of MC in the fibroproliferative process in the renal interstitium of patients with RPGN. The results indicate that these cells constitute part of the overall inflammatory cell accumulation in RPGN.

Dexamethasone inhibits leukocyte migration through endothelial cells towards smooth muscle cells

Leukocyte interactions with endothelial cell monolayers (ECM) and smooth muscle cells (SMC) play an important role during inflammatory processes. Several studies describe an inhibitory effect of dexamethasone on polymorphonuclear leukocytes (PMNL), endothelial cell function, and interleukin-1 (IL-1) release. Aim of the current study was to investigate the influence of dexamethasone on leukocyte migration through an endothelial cell monolayer towards SMC-layers stimulated by tumor necrosis factor-alpha (TNF-alpha). Using a recently developed triple chamber migration system, SMC-layers were cultured on the bottom of a 24-well plate. On the upper surface of the first filter, ECM were cultured, the second filter was a collecting filter. The amount of leukocyte migration through ECM towards TNF-alpha-stimulated smooth muscle cell layers with and without dexamethasone-pretreatment was measured using a fluorescence technique. The pretreatment of SMC-layers with dexamethasone reduced the amount of leukocyte migration down to 92 +/- 8.8% (0.001 mM, p=n.s.), to 67 +/- 5.7% (0.01 mM, p<0.05), to 53 +/- 4.6% (0.1 mM, p<0.05), and to 41 +/- 5.0% (1 mM, p<0.05). In conclusion, dexamethasone treatment of smooth muscle cell layers inhibits leukocyte migration through ECM towards smooth muscle cell layers. The inhibition seems to be due to a decrease in IL-1 release. Treatment of all cell types, PMNL, endothelial cells, as well as smooth muscle cell layers, simulating an in-vivo situation, seems to have an additive effect.

Hydroxyethyl starch reduces the chemotaxis of white cells through endothelial cell monolayers

BACKGROUND

Polymorphonuclear leukocytes (PMNs) play a tremendous role during inflammatory processes. PMNs have to pass a monolayer of endothelial cells to migrate into the extravascular space. Hydroxyethyl starch (HES) is frequently used as a volume expander in critically ill patients.

STUDY DESIGN AND METHODS

The aim of this study was to investigate whether HES influences the chemotaxis of PMNs through endothelial cell monolayers by using a test system that allows the simultaneous treatment of both cell types. Human umbilical endothelial cells were cultured on microporous membrane filters. PMNs were isolated and PMN chemotaxis was studied.

RESULTS

The number of untreated PMNs that migrated through untreated endothelial cell monolayers in response to a chemoattractant was used as a control and set as 100 percent. In clinically relevant concentrations, HES was able to significantly decrease PMN chemotaxis through endothelial cell monolayers, showing a dose-dependent effect (0.1 mg/mL: 99.6 +/- 10.9%, p = NS compared to control; 1 mg/mL: 82.4 +/- 8.3%, p<0.05 compared to control; 10 mg/mL: 62.9 +/- 11.7%, p<0.05). In this assay, both cell types (PMNs and endothelial cells in the monolayer) were treated simultaneously, which simulated the clinical situation after an intravenous injection of HES. The treatment of one cell type, PMNs (89.6 +/- 8.8%, p<0.05) or endothelial cells in the monolayer (76.2 +/- 9.4%, p<0.05), suggests that the influence on endothelial cells is greater.

CONCLUSION

HES is able to significantly reduce the chemotaxis of PMNs through endothelial cell monolayers. The possible clinical consequence of a moderate reduction in endothelium-mediated PMN chemotaxis in critically ill patients remains to be evaluated.

The MCP/eotaxin subfamily of CC chemokines

Migration of leukocytes from the bone marrow to the circulation, the primary lymphoid organs and inflammatory sites is directed by chemokines and specific receptor interactions. Besides the role of this group of low molecular weight cytokines in leukocyte attraction and activation, anti-HIV and hematopoietic activities were also attributed to chemokines. On the basis of the number and arrangement of the conserved cysteines, chemokines are subdivided in two multi-member families, namely the CXC and CC chemokines, whereas fractalkine (CX3C) and lymphotactin (C) are unique relatives. The CC chemokines possess four cysteines of which the first two are adjacent. Functionally, they form a rather heterogeneous family. Here, the focus is on the monocyte chemotactic proteins and eotaxin which, on a structural basis, can be considered as a CC chemokine subfamily. Not only the protein sequences, but also the gene structures, chromosomal location, biological activities and receptor usage exhibit considerable similarities. The review is complemented with a comparison of the biological functions of the MCP/eotaxin-subfamily in physiology and pathology.

Leukocyte migration: a new triple migration chamber assay allows investigation of various cell interactions simultaneously

Examination of the interactions between various cells of the vascular wall and blood components are essential for understanding different pathophysiological processes. Such investigations require appropriate techniques. Several groups have attempted to establish different methods. In all blood vessels except capillaries, endothelial cells (EC) and smooth muscle cells (SMC) coexist and interact very closely. The current study describes a new 3-dimensional triple chamber migration assay, studying leukocyte migration through human endothelial cell monolayers (ECM) towards human SMC layers simultaneously. To test the new assay, SMC-layers were prestimulated with different concentrations of tumor necrosis factor alpha (TNF-alpha, 1 ng/ml, 10 ng/ml, 100 ng/ml) over 6 hours. Then, two microporous membranes, a collecting membrane and a third membrane with cultured ECM, were inserted. Freshly isolated peripheral blood mononuclear cells (PBMNC) were seeded on the ECM and transmigrated cells were measured after further 3 hours incubation. The migration against non stimulated SMC-layers was used as control. Prestimulated SMC-layers led to a dose dependent increase of PBMNC migration into the subendothelial cell space. Antibodies against interleukin-1 reduced the PBMNC migration. In conclusion, this assay allows to study cell migration into the subendothelial space and interactions between different vascular cells. Moreover, this assay can also be used for studies on other cell-cell interactions in man.