Chemotactic cytokine (IL-8 and MCP-1) gene expression by human whole blood

Cdc42 regulates cytokine expression and trafficking in bronchial epithelial cells

Airway epithelial cells can respond to incoming pathogens, allergens and stimulants through the secretion of cytokines and chemokines. These pro-inflammatory mediators activate inflammatory signaling cascades that allow a robust immune response to be mounted. However, uncontrolled production and release of cytokines and chemokines can result in chronic inflammation and appears to be an underlying mechanism for the pathogenesis of pulmonary disorders such as asthma and COPD. The Rho GTPase, Cdc42, is an important signaling molecule that we hypothesize can regulate cytokine production and release from epithelial cells. We treated BEAS-2B lung epithelial cells with a set of stimulants to activate inflammatory pathways and cytokine release. The production, trafficking and secretion of cytokines were assessed when Cdc42 was pharmacologically inhibited with ML141 drug or silenced with lentiviral-mediated shRNA knockdown. We found that Cdc42 inhibition with ML141 differentially affected gene expression of a subset of cytokines; transcription of IL-6 and IL-8 were increased while MCP-1 was decreased. However, Cdc42 inhibition or depletion disrupted IL-8 trafficking and reduced its secretion even though transcription was increased. Cytokines transiting through the Golgi were particularly affected by Cdc42 disruption. Our results define a role for Cdc42 in the regulation of cytokine production and release in airway epithelial cells. This underscores the role of Cdc42 in coupling receptor activation to downstream gene expression and also as a regulator of cytokine secretory pathways.

Identification of common secreted factors in human corneal fibroblasts exposed to LPS, poly(I:C), or zymosan

Infection of the cornea with bacteria, viruses, or fungi can result in corneal ulceration. Corneal stromal cells participate in the immune and inflammatory responses to such infection in part by producing various cytokines and chemokines. The effects of lipopolysaccharide (LPS), polyinosinic-polycytidylic acid [poly(I:C)], and zymosan as surrogates for bacteria, viruses, and fungi, respectively, on the release of cytokines and chemokines from cultured human corneal fibroblasts were examined in order to identify common factors in infectious corneal keratitis. The secretion of various cytokines and chemokines by human corneal fibroblasts exposed to LPS, poly(I:C), or zymosan was measured with a multiplex assay system. LPS induced the release of interleukin (IL)-6, IL-8, MCP-1, RANTES, IP-10, eotaxin, and IL-12 from corneal fibroblasts. Poly(I:C) stimulated the secretion of IL-6, IL-8, MCP-1, RANTES, IP-10, eotaxin, MIP-1β, and interferon-γ, whereas zymosan triggered the production of IL-6, IL-8, and MCP-1. LPS, poly(I:C), and zymosan thus each induced a distinct pattern of cytokine and chemokine release from human corneal fibroblasts, with the release of IL-6, IL-8, and MCP-1 being commonly elicited by all three agents. Our results suggest that IL-6, IL-8, and MCP-1 may therefore play a key role in the inflammatory response to corneal infection.

Circulating fibrocytes correlate with bronchiolitis obliterans syndrome development after lung transplantation: a novel clinical biomarker

BACKGROUND

Development of bronchiolitis obliterans syndrome (BOS) after lung transplantation confers increased patient morbidity and mortality. Fibrocytes are circulating bone marrow-derived mesenchymal cell progenitors that influence tissue repair and fibrosis. Fibrocytes have been implicated in chronic pulmonary inflammatory processes. We investigated the correlation of circulating fibrocyte number with BOS development in lung transplant patients.

METHODS

We prospectively quantified circulating fibrocyte levels among lung transplant patients. Patients were stratified according to the development of BOS as indicated by predicted forced expiratory volume in 1 second. Fibrocyte activity was analyzed by flow cytometry (cluster of differentiation 45+, collagen 1+) in a blinded manner related to clinical presentation.

RESULTS

Thirty-nine patients (61.5% men) underwent double (33.3%), left (25.6%), or right (41.0%) lung transplantation. Average patient age was similar between BOS and non-BOS patients (58.3±3.9 vs 60.3±2.0 years, p=0.67). Chronic obstructive lung disease was the most common indication for lung transplantation (41.0%). Median forced expiratory volume in 1 second was lower among BOS patients compared with non-BOS patients (1.08 vs. 2.18 L/s, p=0.001). Importantly, circulating fibrocyte numbers were increased in BOS patients compared with non-BOS patients (8.91 vs 2.96×10(5) cells/mL, p=0.03) by flow cytometry and were incrementally increased with advancing BOS stage (p=0.02).

CONCLUSIONS

Increased circulating fibrocyte levels correlate with the development of BOS after lung transplantation and positively correlate with advancing BOS stage. Quantification of circulating fibrocytes could serve as a novel biomarker and possible therapeutic target for BOS development in lung transplant patients.

Circulating peripheral blood fibrocytes in human fibrotic interstitial lung disease

Fibrotic interstitial lung diseases are illnesses of unknown cause characterized by progressive decline in lung function. Fibrocytes are bone marrow-derived, circulating progenitor cells capable of differentiating into diverse mesenchymal cell types. Prior work has shown fibrocytes to traffic to the lung via the CXCL12-CXCR4 chemokine axis in an animal model of pulmonary fibrosis. We therefore assessed the relevance of fibrocytes in patients with fibrotic interstitial lung disease. We found enhanced expression of CXCL12 in both the lungs and plasma of patients with lung fibrosis. CXCL12 levels were associated with an order of magnitude higher number of circulating fibrocytes in the peripheral blood of these patients. Most of the circulating fibrocytes in patients with interstitial lung diseases were negative for the myofibroblast marker alpha-smooth muscle actin, suggesting a relatively undifferentiated phenotype. Taken together, these data suggest that fibrocytes are involved in the pathogenesis of human lung fibrosis.

Whole blood cytokine profiles in cats infected by feline coronavirus and healthy non-FCoV infected specific pathogen-free cats

In this study, the cytokine profiles of clinically healthy cats naturally infected with feline coronavirus (FCoV), of cats with feline infectious peritonitis (FIP) and of specific pathogen-free (SPF) cats were investigated in whole blood using a traditional reverse-transcriptase polymerase chain reaction (RT-PCR) assay and a semi-quantitative method of analysis based on computerised quantification of positive bands. The low inter-assay coefficient of variation recorded demonstrated that this method is highly repeatable. Compared with SPF cats, cytokine production was upregulated in most of the samples from FCoV-positive non-symptomatic cats. The appearance of a case of FIP in the cattery was associated with an increased expression of cytokines, in particular there was an increased production of IL-1beta and IFN-gamma, suggesting that these cytokines might protect infected cats from the disease. This hypothesis was also supported by the low levels of IFN-gamma recorded in blood from cats with FIP.

1 alpha,25-dihydroxyvitamin D3 suppresses interleukin-1beta-induced interleukin-8 production in human whole blood: an involvement of erythrocytes in the inhibition

Interleukin (IL)-8, which is involved in inflammatory responses, is produced by a variety of cell types, monocytes/macrophages and neutrophils, in response to inflammatory stimuli including lipopolysaccharide, IL-1, and tumor necrosis factor alpha. Here we report the inhibitory effects of 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) on IL-8 production in human whole blood culture. 1,25(OH)2D3 inhibited only the late phase of the biphasic IL-8 production in lipopolysaccharide-stimulated human whole blood. It also effectively inhibited IL-8 production induced by IL-lbeta compared with that induced by tumor necrosis factor alpha. IL-8 mRNA expression in IL-lbeta-stimulated whole blood was found to require de novo protein synthesis. Although monocytes were found to be mainly responsible for IL-1beta-induced IL-8 production in whole blood, 1,25(OH)2D3 inhibited IL-8 production by isolated mononuclear cells only marginally. The inhibitory effect of 1,25(OH)2D3 on mononuclear cells was restored by adding erythrocytes. These results suggest that erythrocytes play a role in mediating the inhibitory effects of 1,25(OH)2D3 on IL-8 production in IL-1beta-stimulated whole blood.

Differential cytokine mRNA expression in swine whole blood and peripheral blood mononuclear cell cultures

The kinetics of interleukin-2 (IL-2), IL-6, IL-8 and IL-10 gene expression in concanavalin A (Con A)-activated whole blood (WB) and peripheral blood mononuclear cell (PBMC) cultures were examined using reverse transcriptase-polymerase chain reaction (RT-PCR). Unstimulated PBMC or WB cultures failed to show increases in basal cytokine PCR amplicon levels for any cytokine examined. PBMC cultures demonstrated peak expression of IL-2, IL-6, IL-8 and IL-10 mRNA levels at 12, 24, 24 and 6h, respectively. WB cultures exhibited peak IL-2, IL-6, IL-8 and IL-10 mRNA levels at 24, 12, 6 and 24h, respectively. PBMC cultures consistently exhibited higher levels of IL-2 mRNA at all times examined than did WB cultures. WB cultures consistently had higher levels of IL-6 mRNA than PBMC cultures. IL-8 and IL-10 protein levels in PBMC cultures were first detected 12h after stimulation and continued to increase in concentration through 48h. In WB cultures, IL-8 and IL-10 protein levels were first noted at 12 and 6h, respectively. WB culture IL-8 and IL-10 levels quickly reached equilibrium after being detected and remained at levels lower than those noted in PBMC cultures. These results show WB cultures represent an approach with reduced cost and time when compared to traditional cell culture and isolation methods. It may also produce an in vitro test system that more closely resembles in vivo conditions.

Gene expression profiling in human peripheral blood mononuclear cells using high-density filter-based cDNA microarrays

Microarray technology has provided the ability to analyse the expression profiles for thousands of genes in parallel. The need for highly specialised equipment to use certain types of microarrays has restricted the application of this technology to a small number of dedicated laboratories. High-density filter-based cDNA microarrays provide a low-cost option for performing high-throughput gene expression analysis. We have used a model system in which filter-based cDNA microarrays representing over 4000 known human genes were used to monitor the kinetics of gene expression in human peripheral blood mononuclear cells (PBMCs) stimulated with phytohaemagluttinin (PHA). Using software-based cluster analysis, we identified 104 genes that altered in expression levels in response to PHA stimulation of PBMCs and showed that there was a considerable overlap between genes with similar temporal expression profiles and similar functional roles. Comparison of microarray quantitation with quantitative PCR showed almost identical expression profiles for a number of genes. Coupled with the fact that our findings are in agreement with a large number of independent observations, we conclude that the use of filter-based cDNA microarrays is a valid and accurate method for high-throughput gene expression profiling.

Monocyte chemoattractant protein-1 mRNA expression in the human burn wound

The inflammatory response following a thermal insult begins with the skin itself. Langerhan's cells, tissue macrophages, keratinocytes, fibroblasts, and endothelial cells contribute to the initial events of wound healing with active and passive release of cell mediators. One of the mediators potentially important to the repair process is monocyte chemoattractant protein-1 (MCP-1). Macrophages, fibroblasts, endothelial cells, and keratinocytes can produce MCP-1 in response to inflammatory stimuli. Therefore, we evaluated 10 human burn wound specimens for MCP-1 mRNA using in situ hybridization. Selected specimens of different ages were examined using combined in situ hybridization and immunocytochemistry to identify cell types that expressed MCP-1 mRNA. Antibodies to HAM56 for macrophages, CD45 for bone marrow-derived cells, Factor VIII for endothelial cells, and Factor XIIIa for dermal antigen-presenting cells were included in these experiments. By Postburn Day 2, basal layer keratinocytes at the edges of the wound had upregulated MCP-1 message; the increased signal persisted in the rate pegs deep in the dermal wound bed through 49 days postinjury. Occasional FXIIIa+ immunostained dermal cells expressed MCP-1 mRNA. Islands of granulation tissue throughout the wound bed were positive for increased expression of MCP-1; endothelial cells and inflammatory cells both contributed to this upregulated signal. Our data support the theory that the skin itself is a component of the immune system and that noninflammatory cells contribute to the initiation and maintenance of the inflammation at a wound site. Failure to produce MCP-1 or other related mediators by indigenous cutaneous cells may delay the inflammatory response to injury and potentially disrupt other essential phases of wound repair.

Cytokines in proliferative diabetic retinopathy and proliferative vitreoretinopathy

We determined whether interleukin-8, monocyte chemotactic protein-1, and macrophage-colony stimulating factor are present in the vitreous of patients with proliferative diabetic retinopathy (PDR) or proliferative vitreoretinopathy (PVR). The levels of these cytokines were measured by specific enzyme-linked immunoassays in vitreous from 30 patients with PDR, 13 patients with PVR, and 26 control individuals, including 10 cadaver eyes and 16 patients with idiopathic macular holes, idiopathic macular puckers, vitreous hemorrhages, or uncomplicated retinal detachments. Detectable levels of interleukin-8 were found in 90% of vitreous samples of patients with PDR, 85% with PVR, and 58% of control samples. IL-8 was significantly increased in PDR (mean +/- SEM; 25.0 +/- 5.3 ng/ml; p = 0.01), but not in PVR (11.9 +/- 3.9 ng/ml; p = 0.50) compared to control human vitreous (8.5 +/- 2.5 2.5 ng/ml). MCP-1 was detected in 90% of vitreous samples of patients with PDR, 92% with PVR, and 81% of control samples. MCP-1 was significantly increased in PDR (6.2 +/- 0.9 ng/ml, p = 0.001) and PVR (7.7 +/- 2.5 ng/ml, p = 0.001) over the levels in control vitreous (1.2 +/- 0.2 ng/ml). M-CSF was detected in 94% of vitreous samples of patients with PDR, 88% with PVR, and 92% from control vitreous. M-CSF was significantly elevated in PDR (32.3 +/- 8.3 ng/ml, p = 0.03), but not in PVR (23.6 +/- 12.8 ng/ml, p = 0.4) compared to control (10.7 +/- 3.5 ng/ml). Our results suggest that IL-8, MCP-1, and M-CSF participate in the pathogenesis of PDR and PVR.

Tumor necrosis factor and cachexia: a current perspective

Anorexia, net proteolysis of skeletal muscle and consumption of body fat are hallmarks of the cachexia syndrome associated with chronic disease states. While inanition contributes to cachexia, this wasting diathesis has little in common with simple starvation. The cachexia syndrome is characterized by progressive weight loss and depletion of lean body mass in excess to that resulting from comparable caloric restriction. Accelerated mobilization and consumption of host protein stores from peripheral tissues occurs to support gluconeogenesis and acute phase protein synthesis [1, 2]. In contrast, simple starvation is associated with a relative sparing of lean tissue with the preferential consumption of fat. While the clinical manifestations of cachexia are readily apparent, identification of the specific mechanisms responsible for the development of cachexia remains an enigma. In recent years, interest has focused on the role that the immune system plays in the development of cachexia. Investigators initially hypothesized that the chronic production of two inflammatory cytokines, tumour necrosis factor alpha (TNF alpha) and/or interleukin-1 (IL-1), could explain the host non-specific responses resulting in cachexia [3-5]. Other pro-inflammatory cytokines, including interleukin-6 (IL-6) [6, 7] and interferon-gamma [8, 9], have been more recently proposed to be involved in this complex process. Although no consensus exists for the exclusive role of any one cytokine in the pathogenesis of cachexia, there is growing acceptance that the progression of cachexia results in part from the inappropriate release of one or more pro-inflammatory cytokines [10, 11]. In the present review, the current role of TNF alpha as a mediator of cachexia is examined.