Connective tissue growth factor expression is regulated by histamine in lung fibroblasts: potential role of histamine in airway remodeling

Store-Operated Ca2+ Entry in Fibrosis and Tissue Remodeling

Fibrosis is a pathological condition characterized by excessive tissue deposition of extracellular matrix (ECM) components, leading to scarring and impaired function across multiple organ systems. This complex process is mediated by a dynamic interplay between cell types, including myofibroblasts, fibroblasts, immune cells, epithelial cells, and endothelial cells, each contributing distinctively through various signaling pathways. Critical to the regulatory mechanisms involved in fibrosis is store-operated calcium entry (SOCE), a calcium entry pathway into the cytosol active at the endoplasmic reticulum-plasma membrane contact sites and common to all cells. This review addresses the multifactorial nature of fibrosis with a focus on the pivotal roles of different cell types. We highlight the essential functions of myofibroblasts in ECM production, the transformation of fibroblasts, and the participation of immune cells in modulating the fibrotic landscape. We emphasize the contributions of SOCE in these different cell types to fibrosis, by exploring the involvement of SOCE in cellular functions such as proliferation, migration, secretion, and inflammatory responses. The examination of the cellular and molecular mechanisms of fibrosis and the role of SOCE in these mechanisms offers the potential of targeting SOCE as a therapeutic strategy for mitigating or reversing fibrosis.

Histamine promotes angiogenesis through a histamine H1 receptor-PKC-VEGF-mediated pathway in human endothelial cells

Histamine is a well-known inflammatory mediator, but how histamine induces angiogenesis remains poorly understood. In the present study, we demonstrated a dose-dependent dynamic tube formation in the human endothelial cell line EA.hy926 in the presence of histamine that was completely blocked by histamine H1 receptor (H1R) and protein kinase C (PKC) inhibitors. However, histamine H2, H3, and H4 receptor inhibitors did not inhibit tube formation, suggesting that H1R-PKC signaling is involved in histamine-induced tube formation. Moreover, we found an H1-specific induction of vascular endothelial growth factor (VEGF) expression. Inhibition of VEGF receptor 2 (VEGFR2) suppressed the histamine-induced tube formation, indicating that VEGF is downstream of histamine signaling. Additionally, we demonstrated that histamine stimulation induces the expression of critical regulators of angiogenesis such as matrix metalloproteinase (MMP)-9 and MMP-14 metalloproteases, as histamine-induced tube formation is blocked by MMP inhibitors. In summary, our study indicates that histamine can activate the H1R in human endothelial cells and thereby promote tube formation through the PKC, MMP, and VEGF signaling pathways.

Histamine activates an intracellular Ca2+ signal in normal human lung fibroblast WI-38 cells

Histamine is an inflammatory mediator that can be released from mast cells to induce airway remodeling and cause persistent airflow limitation in asthma. In addition to stimulating airway smooth muscle cell constriction and hyperplasia, histamine promotes pulmonary remodeling by inducing fibroblast proliferation, contraction, and migration. It has long been known that histamine receptor 1 (H1R) mediates the effects of histamine on human pulmonary fibroblasts through an increase in intracellular Ca2+ concentration ([Ca2+]i), but the underlying signaling mechanisms are still unknown. Herein, we exploited single-cell Ca2+ imaging to assess the signal transduction pathways whereby histamine generates intracellular Ca2+ signals in the human fetal lung fibroblast cell line, WI-38. WI-38 fibroblasts were loaded with the Ca2+-sensitive fluorophore, FURA-2/AM, and challenged with histamine in the absence and presence of specific pharmacological inhibitors to dissect the Ca2+ release/entry pathways responsible for the onset of the Ca2+ response. Histamine elicited complex intracellular Ca2+ signatures in WI-38 fibroblasts throughout a concentration range spanning between 1 µM and 1 mM. In accord, the Ca2+ response to histamine adopted four main temporal patterns, which were, respectively, termed peak, peak-oscillations, peak-plateau-oscillations, and peak-plateau. Histamine-evoked intracellular Ca2+ signals were abolished by pyrilamine, which selectively blocks H1R, and significantly reduced by ranitidine, which selectively inhibits H2R. Conversely, the pharmacological blockade of H3R and H4R did not affect the complex increase in [Ca2+]i evoked by histamine in WI-38 fibroblasts. In agreement with these findings, histamine-induced intracellular Ca2+ signals were initiated by intracellular Ca2+ release from the endoplasmic reticulum through inositol-1,4,5-trisphosphate (InsP3) receptors (InsP3R) and sustained by store-operated Ca2+ channels (SOCs). Conversely, L-type voltage-operated Ca2+ channels did not support histamine-induced extracellular Ca2+ entry. A preliminary transcriptomic analysis confirmed that WI-38 human lung fibroblasts express all the three InsP3R isoforms as well as STIM2 and Orai3, which represent the molecular components of SOCs. The pharmacological blockade of InsP3 and SOC, therefore, could represent an alternative strategy to prevent the pernicious effects of histamine on lung fibroblasts in asthmatic patients.

Cellular and Molecular Mechanism of Traditional Chinese Medicine on Ventricular Remodeling

Ventricular remodeling is related to the renin-angiotensin-aldosterone system, immune system, and various cytokines involved in inflammation, apoptosis, and cell signal regulation. Accumulated studies have shown that traditional Chinese medicine can significantly inhibit the process of ventricular remodeling, which may be related to the mechanism mentioned above. Here, we conducted a system overview to critically review the cellular and molecular mechanism of traditional Chinese medicine on ventricular remodeling. We mainly searched PubMed for basic research about the anti-ventricular remodeling of traditional Chinese medicine in 5 recent years, and then objectively summarized these researches. We included more than 25 kinds of Chinese herbal medicines including Qi-Li-Qian-Xin, Qi-Shen-Yi-Qi Pill, Xin-Ji-Er-Kang Formula, and Yi-Qi-Wen-Yang Decoction, and found that they can inhibit ventricular remodeling effectively through multi-components and multi-action targets, which are promoting the clinical application of traditional Chinese medicine.

Changes in histidine decarboxylase expression influence extramedullary hematopoiesis in postnatal mice

Histidine decarboxylase (HDC), histamine synthase, is expressed in hematopoietic stem cells and in lineage-committed progenitors in the bone marrow (BM). However, the role of histamine in hematopoiesis is not well described. To evaluate the role of histamine in hematopoiesis, we analyzed the changes in HDC expression at hematopoietic sites, the BM, spleen, and liver of 2-, 3-, and 6-week-old wild-type mice. We also performed morphological analyses of the hematopoietic sites using HDC-deficient (HDC-KO) mice. In wild-type adults, HDC expression in the BM was higher than that in the spleen and liver and showed an age-dependent increase. Histological analysis showed no significant change in the adult BM and spleen of HDC-KO mice compared to wild-type mice. In the liver, HDC expression was temporarily increased at 3 weeks and decreased at 6 weeks of age. Morphological analysis of the liver revealed more numerous hematopoietic colonies and megakaryocytes in HDC-KO mice compared to wild-type mice at 2 and 3 weeks of age, whereas no changes were observed in adults. Most of these hematopoietic colonies consisted of B220-positive B-lymphocytes and TER119-positive erythroblasts and were positive for the cell proliferation marker PCNA. Notably, these hematopoietic colonies declined in HDC-KO mice upon N-acetyl histamine treatment. A significant increase in the expression of hematopoiesis-related cytokines, Il3, Il7, Epo, Gcsf, and Cxcl12 mRNA was observed in the liver of 3-week-old HDC-KO mice compared to wild-type mice. These results suggest that histamine-deficiency may maintain an microenvironment suitable for hematopoiesis by regulating hematopoiesis-related cytokine expression in the liver of postnatal mice.

Organic Cation Transporters in Human Physiology, Pharmacology, and Toxicology

Individual cells and epithelia control the chemical exchange with the surrounding environment by the fine-tuned expression, localization, and function of an array of transmembrane proteins that dictate the selective permeability of the lipid bilayer to small molecules, as actual gatekeepers to the interface with the extracellular space. Among the variety of channels, transporters, and pumps that localize to cell membrane, organic cation transporters (OCTs) are considered to be extremely relevant in the transport across the plasma membrane of the majority of the endogenous substances and drugs that are positively charged near or at physiological pH. In humans, the following six organic cation transporters have been characterized in regards to their respective substrates, all belonging to the solute carrier 22 (SLC22) family: the organic cation transporters 1, 2, and 3 (OCT1–3); the organic cation/carnitine transporter novel 1 and 2 (OCTN1 and N2); and the organic cation transporter 6 (OCT6). OCTs are highly expressed on the plasma membrane of polarized epithelia, thus, playing a key role in intestinal absorption and renal reabsorption of nutrients (e.g., choline and carnitine), in the elimination of waste products (e.g., trimethylamine and trimethylamine N-oxide), and in the kinetic profile and therapeutic index of several drugs (e.g., metformin and platinum derivatives). As part of the Special Issue Physiology, Biochemistry, and Pharmacology of Transporters for Organic Cations, this article critically presents the physio-pathological, pharmacological, and toxicological roles of OCTs in the tissues in which they are primarily expressed.

Status and prospects: personalized treatment and biomarker for airway remodeling in asthma

Airway remodeling, as a major characteristic of bronchial asthma, is critical to the progression of this disease, whereas it is of less importance in clinical management. Complying with the current stepwise treatment standard for asthma, the choice of intervention on the clinical status is primarily determined by the patient’s treatment response to airway inflammation. However, a considerable number of asthmatic patients, especially severe asthmatic subjects, remain uncontrolled though they have undergone fortified anti-inflammation treatment. In the past few years, a growing number of biologics specific to asthma phenotypes have emerged, bringing new hope for patients with refractory asthma and severe asthma. While at the same time, the effect of airway remodeling on asthma treatment has become progressively prominent. In the era of personalized treatment, it has become one of the development directions for asthma treatment to find reliable airway remodeling biomarkers to assist in asthma phenotypes classification, and to further combine multiple phenotypes to accurately treat patients. In the present study, the research status of airway remodeling in asthma is reviewed to show the basis for classifying and treating such disease. Besides, several selected airway remodeling biomarkers and possibility to use them in individual treatment are discussed as well. This study considers that continuously optimized mechanisms and emerging biomarkers for airway remodeling in the future may further support individual therapy for asthma patients.

Activated Leukocyte Cell Adhesion Molecule Stimulates the T-Cell Response in Allergic Asthma

RATIONALE

The activated leukocyte cell adhesion molecule (ALCAM) is a cluster of differentiation 6 ligand that is important for stabilizing the immunological synapse and inducing T-cell activation and proliferation.

OBJECTIVES

In this study, we investigated the role of ALCAM in the development of inflammation in allergic asthma.

METHODS

An ovalbumin (OVA)-induced allergic asthma model was established in wild-type (WT) and ALCAM-deficient (ALCAM^-/-) mice. T-cell proliferation was evaluated in cocultures with dendritic cells (DCs). Bone marrow-derived dendritic cells (BMDCs) from WT and ALCAM^-/- mice were cultured and adoptively transferred to OT-II mice for either OVA sensitization or challenge. An anti-ALCAM antibody was administered to assess its therapeutic potential. ALCAM concentrations in the sputum and serum of children with asthma were quantified by ELISA.

MEASUREMENTS AND MAIN RESULTS

Inflammatory responses were lower in ALCAM^-/- mice than in WT mice, and T cells cocultured with DCs from ALCAM^-/- mice showed reduced proliferation relative to those cocultured with DCs from WT mice. A decreased inflammatory response was observed upon adoptive transfer of BMDCs from ALCAM^-/- mice as compared with that observed after transfer of BMDCs from WT mice. In addition, anti-ALCAM antibody-treated mice showed a reduced inflammatory response, and sputum and serum ALCAM concentrations were higher in children with asthma than in control subjects.

CONCLUSIONS

ALCAM contributes to OVA-induced allergic asthma by stimulating T-cell activation and proliferation, suggesting it as a potential therapeutic target for allergic asthma.

Caffeine modulates glucocorticoid-induced expression of CTGF in lung epithelial cells and fibroblasts

Background

Although caffeine and glucocorticoids are frequently used to treat chronic lung disease in preterm neonates, potential interactions are largely unknown. While anti-inflammatory effects of glucocorticoids are well defined, their impact on airway remodeling is less characterized. Caffeine has been ascribed to positive effects on airway inflammation as well as remodeling. Connective tissue growth factor (CTGF, CCN2) plays a key role in airway remodeling and has been implicated in the pathogenesis of chronic lung diseases such as bronchopulmonary dysplasia (BPD) in preterm infants. The current study addressed the impact of glucocorticoids on the regulation of CTGF in the presence of caffeine using human lung epithelial and fibroblast cells.

Methods

The human airway epithelial cell line H441 and the fetal lung fibroblast strain IMR-90 were exposed to different glucocorticoids (dexamethasone, budesonide, betamethasone, prednisolone, hydrocortisone) and caffeine. mRNA and protein expression of CTGF, TGF-β1-3, and TNF-α were determined by means of quantitative real-time PCR and immunoblotting. H441 cells were additionally treated with cAMP, the adenylyl cyclase activator forskolin, and the selective phosphodiesterase (PDE)-4 inhibitor cilomilast to mimic caffeine-mediated PDE inhibition.

Results

Treatment with different glucocorticoids (1 μM) significantly increased CTGF mRNA levels in H441 (p < 0.0001) and IMR-90 cells (p < 0.01). Upon simultaneous exposure to caffeine (10 mM), both glucocorticoid-induced mRNA and protein expression were significantly reduced in IMR-90 cells (p < 0.0001). Of note, 24 h exposure to caffeine alone significantly suppressed basal expression of CTGF mRNA and protein in IMR-90 cells. Caffeine-induced reduction of CTGF mRNA expression seemed to be independent of cAMP levels, adenylyl cyclase activation, or PDE-4 inhibition. While dexamethasone or caffeine treatment did not affect TGF-β1 mRNA in H441 cells, increased expression of TGF-β2 and TGF-β3 mRNA was detected upon exposure to dexamethasone or dexamethasone and caffeine, respectively. Moreover, caffeine increased TNF-α mRNA in H441 cells (6.5 ± 2.2-fold, p < 0.05) which has been described as potent inhibitor of CTGF expression.

Conclusions

In addition to well-known anti-inflammatory features, glucocorticoids may have adverse effects on long-term remodeling by TGF-β1-independent induction of CTGF in lung cells. Simultaneous treatment with caffeine may attenuate glucocorticoid-induced expression of CTGF, thereby promoting restoration of lung homeostasis.

Histamine induces NF-κB controlled cytokine secretion by orbital fibroblasts via histamine receptor type-1

Mast cells and their products are likely to be involved in regulating orbital fibroblast activity in Graves' Ophthalmopathy (GO). Histamine is abundantly present in granules of mast cells and is released upon mast cell activation. However, the effect of histamine on orbital fibroblasts has not been examined so far. Orbital tissues from GO patients and controls were analyzed for the presence of mast cells using toluidine blue staining and immunohistochemical detection of CD117 (stem cell factor receptor). Orbital fibroblasts were cultured from GO patients and healthy controls, stimulated with histamine and cytokines (IL-6, IL-8, CCL2, CCL5, CCL7, CXCL10 and CXCL11) were measured in culture supernatants. Also hyaluronan levels were measured in culture supernatants and hyaluronan synthase (HAS) and hyaluronidase (HYAL) gene expression levels were determined. In addition, histamine receptor subtype gene expression levels were examined as well as the effect of the histamine receptor-1 (HRH1) antagonist loratadine and NF-κB inhibitor SC-514 on histamine-induced cytokine production. Mast cell numbers were increased in GO orbital tissues. Histamine stimulated the production of IL-6, IL-8 and CCL2 by orbital fibroblasts, while it had no effect on the production of CCL5, CCL7, CXCL10, CXCL11 and hyaluronan. Orbital fibroblasts expressed HRH1 and loratadine and SC-514 both blocked histamine-induced IL-6, IL-8 and CCL2 production by orbital fibroblasts. In conclusion, this study demonstrates that histamine can induce the production of NF-κB controlled-cytokines by orbital fibroblasts, which supports a role for mast cells in GO.

[Tranilast inhibits myocardial fibrosis in mice with viral myocarditis]

OBJECTIVE

To investigate the effect of tranilast on myocardial fibrosis in mice with viral myocarditis (VMC).

METHODS

Male balb/c mice (n=72) were randomly divided into control, VMC and tranilast groups (n=24 each). In the VMC and tranilast groups, the mice were infected with Coxsackie virus B3 (CVB3) to prepare VMC model, while the control group was treated with Eagle's medium. After modeling, the tranilast group was administrated with tranilast [200 mg/(kg.d)] until the day before sampling. On days 7, 14 and 28 after CVB3 or Eagle's medium infection, heart specimens (n=8) were taken and examined after Toluidine blue staining and Nissl staining for counts of mast cells (MC), hematoxylin-eosin staining for myocardial pathological changes, and Masson staining for myocardial fibrosis. The expression of CTGF and type I collagen (Col I) in the myocardial tissue was measured by RT-PCR and Western blot. The correlations of CTGF mRNA expression with MC counts and Col I expression were analyzed.

RESULTS

The myocardial pathological changes and collagen volume fraction in the VMC group were significantly higher than in the control group at all three time points (P<0.05). Tranilast treatment significantly decreased the myocardial pathological changes and collagen volume fraction compared with the VMC group (P<0.05). The mRNA and protein expression of CTGF and Col I increased in the VMC group compared with the control group, and the increases were reduced with tranilast treatment (P<0.05). The number of MC was positively correlated to CTGF mRNA expression on the 7th day and 14th day (r=0.439, P=0.049) in the VMC group. There were positive correlations between the mRNA expression of Col I and CTGF on the 7th day and 14th day (r=0.646, P=0.007) and the 28th day (r=0.326, P=0.031).

CONCLUSIONS

Tranilast may inhibit the aggregation of MC and down-regulate the expression of CTGF, relieving myocardial fibrosis of mice with VMC.

Long-Term Effects of Diesel Exhaust Particles on Airway Inflammation and Remodeling in a Mouse Model

Purpose

Diesel exhaust particles (DEPs) can induce and trigger airway hyperresponsiveness (AHR) and inflammation. The aim of this study was to investigate the effect of long-term DEP exposure on AHR, inflammation, lung fibrosis, and goblet cell hyperplasia in a mouse model.

Methods

BALB/c mice were exposed to DEPs 1 hour a day for 5 days a week for 3 months in a closed-system chamber attached to a ultrasonic nebulizer (low dose: 100 µg/m³ DEPs, high dose: 3 mg/m³ DEPs). The control group was exposed to saline. Enhanced pause was measured as an indicator of AHR. Animals were subjected to whole-body plethysmography and then sacrificed to determine the performance of bronchoalveolar lavage and histology.

Results

AHR was higher in the DEP group than in the control group, and higher in the high-dose DEP than in the low-dose DEP groups at 4, 8, and 12 weeks. The numbers of neutrophils and lymphocytes were higher in the high-dose DEP group than in the low-dose DEP group and control group at 4, 8, and 12 weeks. The levels of interleukin (IL)-5, IL-13, and interferon-γ were higher in the low-dose DEP group than in the control group at 12 weeks. The level of IL-10 was higher in the high-dose DEP group than in the control group at 12 weeks. The level of vascular endothelial growth factor was higher in the low-dose and high-dose DEP groups than in the control group at 12 weeks. The level of IL-6 was higher in the low-dose DEP group than in the control group at 12 weeks. The level of transforming growth factor-β was higher in the high-dose DEP group than in the control group at 4, 8, and 12 weeks. The collagen content and lung fibrosis in lung tissue was higher in the high-dose DEP group at 8 and 12 weeks.

Conclusions

These results suggest that long-term DEP exposure may increase AHR, inflammation, lung fibrosis, and goblet cell hyperplasia in a mouse model.

The emerging prominence of the cardiac mast cell as a potent mediator of adverse myocardial remodeling

Cardiac mast cells store and release a variety of biologically active mediators, several of which have been implicated in the activation of matrix metalloproteinases in the volume-overloaded heart, while others are involved in the fibrotic process in pressure-overloaded hearts. Increased numbers of mast cells have been reported in explanted human hearts with dilated cardiomyopathy and in animal models of experimentally induced hypertension, myocardial infarction, and chronic cardiac volume overload. Also, there is evolving evidence implicating the cardiac mast cell as having a major role in the adverse remodeling underlying these cardiovascular disorders. Thus, the cardiac mast cell is the focus of this chapter that begins with a historical background, followed by sections on methods for their isolation and characterization, endogenous secretagogues, phenotype, and ability of estrogen to alter their phenotype so as to provide cardioprotection. Finally the role of mast cells in myocardial remodeling secondary to a sustained cardiac volume overload, hypertension, and ischemic injury and future research directions are discussed.

Histamine induces human lung fibroblast-mediated collagen gel contraction via histamine H1 receptor

BACKGROUND

Airway remodeling is implicated in irreversible airflow limitation of refractory asthma, which includes increased smooth muscle mass and subepithelial fibrosis. Activated fibroblasts acquire contractile phenotype to participate in tissue contraction and structural alteration of extracellular matrices. Histamine is a potent mediator of allergic inflammation, substantially involved in asthmatic pathophysiology.

OBJECTIVE

We hypothesized that histamine might play a role in airway remodeling, and investigated its effect on fibroblast-mediated collagen gel contraction.

METHODS

Fibroblast-mediated collagen gel contraction was studied. Histamine's regulation of collagen gel contraction was characterized by using specific histamine-receptor antagonists, an IP3 receptor antagonist and a PKC inhibitor.

RESULTS

Histamine induced contraction of collagen gels embedded with human lung fibroblasts, in a time-dependent manner, and at the concentration more than 10(-6) M, both in four primary cultured adult lung fibroblasts and three fetal lung fibroblast cell lines. This effect was attenuated by H1 receptor antagonist, whereas those for H2 to H4 receptors failed to show an inhibitory effect. Furthermore, IP3 receptor-mediated Ca(2+) mobilization was implicated in histamine's action on collagen gel contraction.

CONCLUSIONS

Our results suggest that histamine is involved in airway remodeling through its action on lung fibroblasts, and antihistamine drugs, especially H1 receptor antagonists, might be potentially beneficial for a subset of asthmatic patients.

Plasma connective tissue growth factor levels as potential biomarkers of airway obstruction in patients with asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory disorder characterized by airway hyperresponsiveness and airflow limitation. Connective tissue growth factor (CTGF), one of the key profibrotic factors associated with transforming growth factor β, may be related to airway remodeling in asthma. However, no data are available on the association between plasma CTGF levels and clinical and physiologic parameters in patients with asthma. Recently, we developed a novel subtraction method for determination of plasma CTGF levels.

OBJECTIVE

To investigate the utility of plasma CTGF level as a surrogate biomarker in asthma.

METHODS

Plasma CTGF levels were measured in 67 patients with stable asthma and 81 healthy volunteers, using the subtraction method. We evaluated correlations between plasma CTGF levels and clinical and physiologic parameters in patients with asthma.

RESULTS

Plasma CTGF levels were higher in patients with asthma than in healthy volunteers. Asthmatic patients with a percentage of predicted forced expiratory volume in 1 second (FEV1) less than 80% had significantly higher levels of plasma CTGF than those with a percentage of predicted FEV1 of 80% or more. In patients with asthma, plasma CTGF levels had significantly negative correlations with forced vital capacity (FVC), FEV1, percentage of predicted FEV1, FEV1/FVC ratio, forced expiratory flow at 50% of the FVC (FEF50%), percentage of predicted FEF50%, forced expiratory flow at 75% of the FVC (FEF75%), and percentage of predicted FEF75%, parameters that reflect the degree of airway obstruction. Plasma CTGF levels were negatively correlated with Asthma Control Test scores, a patient-based index of clinical control of asthma.

CONCLUSION

Plasma CTGF may be a potential biomarker for stable asthma when evaluating the degree of persistent airway obstruction.

TRIAL REGISTRATION

umin.ac.jp/ctr Identifier: UMIN000013081.

Fibroblasts induce epithelial to mesenchymal transition in breast tumor cells which is prevented by fibroblasts treatment with histamine in high concentration

Epithelial to mesenchymal transition (EMT) of cancer cells is an essential process in cancer progression. Cancer cells that undergone EMT loose cell-cell contacts, acquire mesenchymal properties and develop migratory and invasive abilities. In previous studies we have demonstrated that histamine may modify the invasive phenotype of pancreatic and mammary tumor cells. In this work we proposed to investigate whether histamine may also influence the interaction between tumor cells and normal fibroblasts. The potential activation of normal CCD-1059Sk fibroblasts by histamine and EMT phenotypic changes induced in MCF-7 and MDA-MB-231 breast tumor cells by the conditioned media (CM) derived from fibroblasts were evaluated. Initially, we determined the presence of H1, H2 and H4 histamine receptors and matrix metalloproteinase 2 (MMP2) mRNA in CCD-1059Sk fibroblasts. MMP2 gelatinolytic activity, cell migration and alpha-smooth muscle actin expression were increased in fibroblasts by low doses (<1μM) and decreased by high doses (20μM) of histamine. MCF-7 cells cultured with CM from fibroblasts exhibited spindle-shaped morphology, cell spreading and cytoplasmic expression of β-catenin but there was no change in MMP2 activity and cell migration. MDA-MB-231 cells cultured with CM from fibroblasts showed a more elongated phenotype, cell spreading, cytoplasmic β-catenin, increased MMP2 activity and endogenous TGF-β1 expression, and enhanced cell migration and invasion. Notably, all these features were reversed when mammary tumor cells were cultured with CM from fibroblasts treated with 20μM histamine. In conclusion, high doses of histamine may prevent the activation of fibroblasts and also avert the EMT related changes induced in epithelial tumor cells by fibroblasts CM.

The pathogenesis of cardiac fibrosis

Cardiac fibrosis is characterized by net accumulation of extracellular matrix proteins in the cardiac interstitium, and contributes to both systolic and diastolic dysfunction in many cardiac pathophysiologic conditions. This review discusses the cellular effectors and molecular pathways implicated in the pathogenesis of cardiac fibrosis. Although activated myofibroblasts are the main effector cells in the fibrotic heart, monocytes/macrophages, lymphocytes, mast cells, vascular cells and cardiomyocytes may also contribute to the fibrotic response by secreting key fibrogenic mediators. Inflammatory cytokines and chemokines, reactive oxygen species, mast cell-derived proteases, endothelin-1, the renin/angiotensin/aldosterone system, matricellular proteins, and growth factors (such as TGF-β and PDGF) are some of the best-studied mediators implicated in cardiac fibrosis. Both experimental and clinical evidence suggests that cardiac fibrotic alterations may be reversible. Understanding the mechanisms responsible for initiation, progression, and resolution of cardiac fibrosis is crucial to design anti-fibrotic treatment strategies for patients with heart disease.

Variability of histamine pharmacodynamic response in children with allergic rhinitis

Histamine iontophoresis with laser Doppler monitoring (HILD) is a robust and dynamic surrogate for histamine microvasculature response. We characterized histamine pharmacodynamics in children using HILD. HILD was performed in 54 children with allergic rhinitis. A non-compartmental analysis and non-linear mixed-effects model with a linked effect PK/PD model was used to provide estimates for area under the effect curve (AUEC), maximal response over baseline (EffmaxNT), and time of EffmaxNT (Tmax). Data were placed in sub-groups by visualization of time vs. response relationships. ANOVA and regression analyses were used for sub-group comparisons. Three histamine response phenotypes were identified. One group demonstrated a hyper-responsive phenotype (higher Tmax, EffmaxNt and AUEC, P < .01). AUEC and EffmaxNT were more strongly associated in this group (r(2)  = 0.86) than the entire cohort (r(2)  = 0.64). These data demonstrate a hyper-responsive histamine phenotype via HILD. This finding is important to future pharmacologic studies of antihistamines.

Histamine may induce airway remodeling through release of epidermal growth factor receptor ligands from bronchial epithelial cells

Asthma is a chronic inflammatory disease that is associated with airway remodeling, including hyperplasia of airway epithelial cells and airway smooth muscle cells, and goblet cell differentiation. We wished to address the potential role of histamine, a key biogenic amine involved in allergic reactions, in airway remodeling through the epidermal growth factor receptor (EGFR) pathway. Here, we demonstrate that histamine releases 2 EGFR ligands, amphiregulin and heparin-binding epidermal growth factor-like growth factor (HB-EGF), from airway epithelial cells. Amphiregulin and HB-EGF were expressed in airway epithelium of patients with asthma. Histamine up-regulated their mRNA expression (amphiregulin 3.2-fold, P<0.001; HB-EGF 2.3-fold, P<0.05) and triggered their release (amphiregulin EC(50) 0.50 μM, 31.2 ± 2.7 pg/ml with 10 μM histamine, P<0.01; HB-EGF EC(50) 0.54 μM, 78.5 ± 1.8 pg/ml with 10 μM histamine, P<0.001) compared to vehicle control (amphiregulin 19.3 ± 0.9 pg/ml; HB-EGF 60.2 ± 1.0 pg/ml), in airway epithelial cells. Histamine increased EGFR phosphorylation (2.1-fold by Western blot analysis) and induced goblet cell differentiation (CLCA1 up-regulation by real-time qPCR) in normal human bronchial epithelial (NHBE) cells. Moreover, amphiregulin and HB-EGF caused proliferation and migration of both NHBE cells and human airway smooth muscle cells. These results suggest that histamine may induce airway remodeling via the epithelial-derived EGFR ligands amphiregulin and HB-EGF.

Histamine H4 receptors in normal conjunctiva and in vernal keratoconjunctivitis

BACKGROUND

While it is known that histamine is the primary mediator of ocular allergy, the presence and distribution of histamine receptors are not well documented in the human eye. Our aim was to evaluate histamine receptor expression in normal and vernal keratoconjunctivitis conjunctiva.

METHODS

Mucosal biopsies were obtained from conjunctiva of healthy donors and from tarsal conjunctiva of vernal patients. Immunostaining and semi-quantitative reverse-transcriptase polymerase chain reaction for H(1), H(2), H(3), and H(4) receptors were performed. Histamine receptor expression was also evaluated in conjunctival cell cultures exposed to histamine, interleukin-4, interleukin-5, interferon-γ and tumor necrosis factor-α.

RESULTS

Immunostaining for H(1) and H(2) receptors was slightly positive in normal and over-expressed in vernal tissues. H(3) receptors were rarely present in normal and inflamed conjunctiva. In striking contrast to control tissues, H(4) receptors were highly expressed in all inflamed tissues, particularly by stromal inflammatory cells. Semi-quantitative reverse-transcriptase polymerase chain reaction demonstrated an over-expression of H(1), H(2), and H(4) receptors in vernal vs control tissues. Notably, H(4) receptors were five times more expressed in vernal vs control tissues. In cell cultures, H(2) receptor expression was stimulated eight times the normal levels by interleukin-4 and three times by histamine, but the H(4) receptor was only slightly affected by stimulation with these mediators.

CONCLUSIONS

Increased expression of H1, and particularly of H(2) and H(4) receptors in vernal keratoconjunctival tissues indicate their important role in the pathogenesis of this disease. H(4) receptors may be a target in the treatment of allergic inflammation.

Can anti-IgE therapy prevent airway remodeling in allergic asthma?

Airway remodeling is a central feature of asthma. It is exemplified by thickening of the lamina reticularis and structural changes to the epithelium, submucosa, smooth muscle, and vasculature of the airway wall. Airway remodeling may result from persistent airway inflammation. Immunoglobulin E (IgE) is an important mediator of allergic reactions and has a central role in airway inflammation and asthma-related symptoms. Anti-IgE therapies (such as omalizumab) have the potential to block an early step in the allergic cascade and therefore have the potential to reduce airway remodeling. The reduction in free IgE levels following anti-IgE therapy leads to reductions in high-affinity IgE receptor (FcεRI) expression on mast cells, basophils, and dendritic cells. This combined effect results in attenuation of several markers of inflammation, including peripheral and bronchial tissue eosinophilia and levels of granulocyte macrophage colony-stimulating factor, interleukin (IL)-2, IL-4, IL-5, and IL-13. Considering the previously demonstrated anti-inflammatory effects of anti-IgE therapy, along with results from a small study showing continued benefit after discontinuation of long-term treatment, a larger study to assess its effect on markers of airway remodeling is underway.

Chromogranin A--biological function and clinical utility in neuro endocrine tumor disease

BACKGROUND

Neuroendocrine tumors (NETs) are a form of cancer that differ from other neoplasia in that they synthesize, store, and secrete peptides, e.g., chromogranin A (CgA) and amines. A critical issue is late diagnosis due to failure to identify symptoms or to establish the biochemical diagnosis. We review here the utility of CgA measurement in NETs and describe its biological role and the clinical value of its measurement.

METHODS

Literature review and analysis of the utility of plasma/serum CgA measurements in NETs and other diseases.

RESULTS

CgA is a member of the chromogranin family; its transcription and peptide processing are well characterized, but its precise function remains unknown. Levels are detectable in the circulation but vary substantially (approximately 25%) depending on which assay is used. Serum and plasma measurements are concordant. CgA is elevated in approximately 90% of gut NETs and correlates with tumor burden and recurrence. Highest values are noted in ileal NETs and gastrointestinal NETs associated with multiple endocrine neoplasia type 1. Both functioning and nonfunctioning pancreatic NETs have elevated values. CgA is more frequently elevated in well-differentiated tumors compared to poorly differentiated NETs. Effective treatment is often associated with decrease in CgA levels. Proton pump inhibitors falsely increase CgA, but levels normalize with therapy cessation.

CONCLUSIONS

CgA is currently the best available biomarker for the diagnosis of NETs. It is critical to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy. Measurement of plasma CgA is mandatory for the effective diagnosis and management of NET disease.

Recent advances in the pathophysiology of asthma

There has been an increased understanding, over the past 2 decades, that asthma is a chronic, immunologically mediated condition with a disturbance of the normal airway repair mechanism, which results in inflammatory changes and airway remodeling. The airway inflammation and remodeling together likely explain the clinical manifestations of asthma. The mechanisms by which the external environmental cues, together with the complex genetic actions, propagate the inflammatory process that characterize asthma are beginning to be understood. There is also an evolving awareness of the active participation of structural elements, such as the airway epithelium, airway smooth muscle, and endothelium, in this process. In tandem with this has come the realization that inflammatory cells respond in a coordinated, albeit dysfunctional manner, via an array of complex signaling pathways that facilitate communication between these cells; these structural elements within the lung and the bone marrow serve as reservoirs for and the source of inflammatory cells and their precursors. Although often viewed as separate mechanistic entities, so-called innate and acquired immunity often overlap in the propagation of the asthmatic response. This review examines the newer information on the pathophysiologic characteristics of asthma and focuses on papers published over the past 3 years that have helped to improve current levels of understanding.

Airway remodelling in asthma: from benchside to clinical practice

Airway remodelling refers to the structural changes that occur in both large and small airways relevant to miscellaneous diseases including asthma. In asthma, airway structural changes include subepithelial fibrosis, increased smooth muscle mass, gland enlargement, neovascularization and epithelial alterations. Although controversial, airway remodelling is commonly attributed to an underlying chronic inflammatory process. These remodelling changes contribute to thickening of airway walls and, consequently, lead to airway narrowing, bronchial hyper-responsiveness, airway edema and mucous hypersecretion. Airway remodelling is associated with poor clinical outcomes among asthmatic patients. Early diagnosis and prevention of airway remodelling has the potential to decrease disease severity, improve control and prevent disease expression. The relationship between structural changes and clinical and functional abnormalities clearly deserves further investigation. The present review briefly describes the characteristic features of airway remodelling observed in asthma, its clinical consequences and relevance for physicians, and its modulation by therapeutic approaches used in the treatment of asthmatic patients.

Subtraction method for determination of N-terminal connective tissue growth factor

Background

Connective tissue growth factor (CTGF) may be a potential marker of fibrosis. However, platelet-derived CTGF may be released into the plasma by platelet activation during or after blood collection, thereby interfering with accurate determination of the true plasma CTGF level. Plasma CTGF exists as the N-terminal CTGF fragment (N-fragment), composed of modules 1 and 2, whereas platelet CTGF exists as full-length CTGF (full-length), composed of modules 1–4. We perceived the need to develop a method for distinguishing between the N-fragment and full-length CTGF levels, so that the true plasma and serum CTGF (N-fragment) levels could be accurately determined.

Methods

Full-length levels were determined by a sandwich enzyme-linked immunosorbent assay (ELISA) using two monoclonal antibodies recognizing modules 1 and 4, respectively (M1/4 ELISA). Total CTGF (full-length CTGF plus N-terminal CTGF) levels were determined by a sandwich ELISA using two monoclonal antibodies recognizing modules 1 and 2, respectively (M1/2 ELISA). N-terminal CTGF levels were determined by subtracting the full-length levels from the total CTGF levels.

Results

Both the M1/2 and M1/4 ELISAs showed good analytical performance. When the CTGF levels of plasma and serum collected simultaneously from the same subject were compared, the N-fragment levels determined by the subtraction method were the same, in spite of the fact that full-length CTGF was present in the sample.

Conclusion

N-fragment levels in plasma and serum can be accurately determined by this subtraction method, even if full-length CTGF in platelets is released during or after blood collection.

Human lung parenchyma but not proximal bronchi produces fibroblasts with enhanced TGF-beta signaling and alpha-SMA expression

Given the contribution various fibroblast subsets make to wound healing and tissue remodeling, the concept of lung fibroblast heterogeneity is of great interest. However, the mechanisms contributing to this heterogeneity are unknown. To this aim, we compared molecular and biophysical characteristics of fibroblasts concurrently isolated from normal human proximal bronchi (B-FBR) and distal lung parenchyma (P-FBR). Using quantitative RT-PCR, spontaneous expression of more than 30 genes related to repair and remodeling was analyzed. All P-FBR lines demonstrated significantly increased basal α-smooth muscle actin (α-SMA) mRNA and protein expression levels when compared with donor-matched B-FBR. These differences were not associated with sex, age, or disease history of lung tissue donors. In contrast to B-FBR, P-FBR displayed enhanced transforming growth factor (TGF)-β/Smad signaling at baseline, and inhibition of either ALK-5 or neutralization of endogenously produced and activated TGF-β substantially decreased basal α-SMA protein in P-FBR. Both B-FBR and P-FBR up-regulated α-SMA after stimulation with TGF-β1, and basal expression levels of TGF-β1, TGF-βRI, and TGF-βRII were not significantly different between fibroblast pairs. Blockade of metalloproteinase-dependent activation of endogenous TGF-β did not significantly modify α-SMA expression in P-FBR. However, resistance to mechanical tension of these cells was significantly higher in comparison with B-FBR, and added TGF-β1 significantly increased stiffness of both cell monolayers. Our data suggest that in contrast with human normal bronchial tissue explants, lung parenchyma produces mesenchymal cells with a myofibroblastic phenotype by intrinsic mechanisms of TGF-β activation in feed-forward manner. These results also offer a new insight into mechanisms of human fibroblast heterogeneity and their function in the airway and lung tissue repair and remodeling.

Emedastine difumarate: a review of its potential ameliorating effect for tissue remodeling in allergic diseases

BACKGROUND

Emedastine difumarate, a selective histamine-H1 receptor antagonist and effective antiallergic agent, inhibits various clinical symptoms of allergic rhinitis, allergic conjunctivitis, urticaria, allergic dermatitis, pruritus cutaneous, and prurigo. In addition to greater efficacy than other antihistamines, emedastine difumarate produces no adverse cardiovascular effects and exhibits minimal anticholinergic activity. Moreover, a recent study revealed that the effect of emedastine difumarate on inhibition of histamine-induced collagen synthesis in vitro was greater in dermal fibroblasts than in nasal mucosa fibroblasts. This result indicates that there are tissue-specific effects of emedastine difumarate and that it may be more effective for treating fibrosis in skin than in nasal mucosa. However, the mechanism and role of tissue remodeling is less well established for allergic skin diseases and allergic conjunctivitis, in comparison to respiratory allergic diseases.

OBJECTIVE

This review outlines the involvement of histamine in the pathogenesis of tissue remodeling in a variety of organs, and presents the evidence for the effect of antihistamines on this process. Furthermore, this review also discusses antihistamines as an intervention strategy in tissue remodeling.

METHODS

The scientific literature, published abstracts, and selected textbooks were reviewed.

RESULTS/CONCLUSION

Although additional evidence is required, emerging evidence suggests that emedastine difumarate may be of value in the prevention of excess tissue remodeling in allergic skin inflammation.

Strategies for blocking the fibrogenic actions of connective tissue growth factor (CCN2): From pharmacological inhibition in vitro to targeted siRNA therapy in vivo

Connective tissue growth factor (CCN2) is a major pro-fibrotic factor that frequently acts downstream of transforming growth factor beta (TGF-beta)-mediated fibrogenic pathways. Much of our knowledge of CCN2 in fibrosis has come from studies in which its production or activity have been experimentally attenuated. These studies, performed both in vitro and in animal models, have demonstrated the utility of pharmacological inhibitors (e.g. tumor necrosis factor alpha (TNF-alpha), prostaglandins, peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists, statins, kinase inhibitors), neutralizing antibodies, antisense oligonucleotides, or small interfering RNA (siRNA) to probe the role of CCN2 in fibrogenic pathways. These investigations have allowed the mechanisms regulating CCN2 production to be more clearly defined, have shown that CCN2 is a rational anti-fibrotic target, and have established a framework for developing effective modalities of therapeutic intervention in vivo.

New insights into mechanisms of immunoregulation in 2007

Substantial progress in understanding the mechanisms of immune regulation in allergic diseases and asthma has been made during the last year. In asthma, rhinitis, and atopic dermatitis the immune system is activated by allergens, autoantigens, and components of superimposed infectious agents. Immune regulation in the lymphatic organs and in the tissue has an important role in the control and suppression of allergic disease in all stages of the inflammatory process, such as cell migration to tissues, cells gaining an inflammatory and tissue-destructive phenotype in the tissues, and their interaction with resident tissue cells to augment the inflammation. After the discovery of regulatory T cells, the importance of their unique suppressive capacity was strongly emphasized for the suppression of effector T-cell responses. However, it seems that all 3 subsets of effector T(H)1, T(H)2, and T(H)17 cells, as well as regulatory T cells, regulate each other at the level of transcription, major cytokines, and surface molecules. This review highlights key advances in immune regulation that were published in the Journal of Allergy and Clinical Immunology.

New perspectives on mechanisms underlying chronic allergic inflammation and asthma in 2007

This review summarizes selected articles appearing from January to December 2007 in the Journal of Allergy and Clinical Immunology. Articles were chosen that related to advances in mechanisms of chronic allergic inflammation and asthma, including those describing gene association studies, mast cells, IgE, eosinophils, cytokines, the inception of allergy, airway remodeling, preclinical therapeutic targets, and virally induced asthma.

Airway modeling and remodeling in the pathogenesis of asthma

PURPOSE OF REVIEW

Asthma remains a severe health problem since current therapies are directed to suppressing, rather than preventing or reversing, the primary disease process. Clearly, a greater understanding of the pathogenesis of asthma is critical to the development of better therapeutic modalities. In this review, we discuss the recent advancements in research targeting the role of airway remodeling in asthma.

RECENT FINDINGS

Epithelial fragility and abnormalities are being recognized as important facets of asthma, as are other features of remodeling such as angiogenesis, goblet cell hyperplasia and thickened lamina reticularis. Significantly, these anomalies occur early in disease pathogenesis. However, their impact on disease severity remains unclear.

SUMMARY

Although an altered immune response is undoubtedly important to the pathogenesis of asthma, there is increasing evidence that the tissue-specific manifestations occur independently of inflammation and significantly impact on disease development and severity.

Airway remodeling in asthma and irreversible airflow limitation-ECM deposition in airway and possible therapy for remodeling-

Airway remodeling in asthma is characterized by goblet cell hyperplasia, subepithelial fibrosis, and hyperplasia and hypertrophy of airway smooth muscle cells. The airway wall thickness increases because of subepithelial fibrosis, and hyperplasia and hypertrophy of the airway smooth muscle cells and submucosal glands. Airway remodeling, therefore, can often cause irreversible airflow limitation and an increase of airway hyperresponsiveness. Recent studies have described the molecular and cellular mechanisms of collagen deposition in the airway wall such as subepithelial fibrosis. Fibroblasts or myofibroblasts play a critical role in the exaggerated deposition of collagen in asthmatic airways. Bone marrow derived fibroblasts may play a role in fibrotic remodeling in asthmatic airways. Airway remodeling is induced by cytokines and mediators produced in chronic allergic airway inflammation. Since, once formed, remodeling is resistant to asthma therapy, early intervention with inhaled corticosteroid should be considered to prevent the progress of airway remodeling.