The neutrophil-activating protein (NAP-1) is also chemotactic for T lymphocytes

IL-1β-Mediated Proinflammatory Responses Are Inhibited by Estradiol via Down-Regulation of IL-1 Receptor Type I in Uterine Epithelial Cells

The objective of this study was to examine the effects of sex hormones on IL-1beta-mediated responses by uterine epithelial cells. The mRNA expression and secretion of human beta-defensin-2 and CXCL8 by uterine epithelial cells was examined following stimulation with IL-1beta in the presence of estradiol or progesterone. Estradiol inhibited the IL-1beta-mediated mRNA expression and secretion of human beta-defensin-2 and CXCL8 by uterine epithelial cells while progesterone had no effect. Inhibition of the IL-1beta-mediated response by estradiol was dose dependent, with maximal inhibition observed using 10(-7) to 10(-10) M, and was shown to be mediated through the estrogen receptor because addition of a pure estrogen receptor antagonist abrogated this effect. The mechanism by which estradiol inhibits IL-1beta-mediated responses by uterine epithelial cells appears to be the down-modulation of the IL-1R type I, thereby reducing the uterine epithelial cell's ability to respond to IL-1beta. These results suggest that the inhibitory effect of estradiol on IL-1beta-mediated inflammatory responses by uterine epithelial cells indicates a link between the endocrine and immune systems and may be crucial for dampening proinflammatory responses during the time of ovulation or pregnancy.

In vitro reproduction of clinical hallmarks of eczematous dermatitis in organotypic skin models

Dermatitis is a group of highly pruritic chronic inflammatory skin diseases which represents a major public-health problem worldwide. The prevalence of dermatitis has increased in recent years affecting up to 20% of the general population. Acute skin lesions are characterized by extensive degrees of intercellular edema of the epidermis (spongiosis) and a marked perivenular inflammatory cell infiltrate in the dermis. Keratinocytes within eczematous lesions exhibit a modified expression of proinflammatory cytokines, chemokines and cell-surface molecules. The pathophysiological puzzle of dermatitis is far from being elucidated completely, but skin infiltration of activated memory/effector T cells are thought to play the pivotal role in the pathogeneses. The aim of this study was the set-up of organotypic models mimicking the symptoms of eczematous dermatitis to provide a tool for therapeutic research in vitro. Therefore activated T cells (ATs) were integrated in organotypic skin and epidermis equivalents (SE, EE). These models enabled the reproduction of several clinical hallmarks of eczematous dermatitis: (1) T cells induce keratinocyte apoptosis, which leads to a reduced expression of the adhesion molecule E-cadherin (E-cad) and disruption of the epidermal barrier. (2) Expression of intercellular adhesion molecule-1 (ICAM-1) allows the attachment of leukocytes to epidermal cells. (3) Upregulation of neurotrophin-4 (NT-4) in the epidermis is thought to mediate pruritus in lesions by supporting nerve outgrowth. (4) Elevated levels of pro-inflammatory cytokines (IL-1alpha and IL-6) and chemokines (IL-8, IP-10, TARC, MCP-1, RANTES and eotaxin) amplify the inflammatory response and lead to an influx of secondary immunocells into the skin. The therapeutics dexamethasone and FK506 markedly reduce cytokines/chemokines production and epidermal damaging in these models. These data underline that activated memory/effector T cells induce eczematous changes in this HaCaT cell based organotypic skin equivalent. Furthermore it can be concluded that these models make it possible to investigate targets of therapeutics in skin.

Monocyte-astrocyte networks and the regulation of chemokine secretion in neurocysticercosis

Neurocysticercosis, caused by infection with larval Taenia solium, is a major cause of epilepsy worldwide. Larval degeneration, which is symptomatic, results in inflammatory cell influx. Astrocytes, the most abundant cell type and major cytokine-producing cell within the CNS, may be important in orchestrating inflammatory responses after larval degeneration. We investigated the effects of direct stimulation and of conditioned medium from T. solium larval Ag (TsAg)-stimulated monocytes (CoMTsAg) on neutrophil and astrocyte chemokine release. CoMTsAg, but not control conditioned medium, stimulated astrocyte CCL2/MCP-1 (161.5 +/- 16 ng/ml), CXCL8/IL-8 (416 +/- 6.2 ng/ml), and CXCL10/IFN-gamma-inducible protein (9.07 +/- 0.6 ng/ml) secretion after 24 h, whereas direct astrocyte or neutrophil stimulation with TsAg had no effect. There was rapid accumulation of CCL2 and CXCL8 mRNA within 1 h, with somewhat delayed expression of CXCL10 mRNA initially detected 8 h poststimulation. Neutralizing anti-TNF-alpha inhibited CoMTsAg-induced CCL2 mRNA accumulation by up to 99%, causing total abolition of CXCL10 and up to 77% reduction in CXCL8 mRNA. CoMTsAg induced maximal nuclear binding of NF-kappaB p65 and p50 by 1 h, with IkappaBalpha and IkappaBbeta decay within 15 min. In addition, CoMTsAg induced transient nuclear binding of AP-1, which peaked 4 h poststimulation. In NF-kappaB blocking experiments using pyrrolidine dithiocarbamate, CoMTsAg-induced CCL2 secretion was reduced by up to 80% (p = 0.0006), whereas CXCL8 was inhibited by up to 75% (p = 0.0003). In summary, the data show that astrocytes are an important source of chemokines following larval Ag stimulation. Such chemokine secretion is NF-kappaB dependent, likely to involve AP-1, and is regulated in a paracrine loop by monocyte-derived TNF-alpha.

TGF-beta1 induces IL-8 and MCP-1 through a connective tissue growth factor-independent pathway

Transforming growth factor-beta(1) (TGF-beta(1)) functions as an important immunomodulatory cytokine in human kidney. Evidence suggests that connective tissue growth factor (CTGF) is an important downstream mediator of the profibrotic effects of TGF-beta(1). However, the role of CTGF in TGF-beta(1)-induced chemokine production remains unknown. This study was undertaken to determine whether CTGF is involved in mediating TGF-beta(1)-induced chemokine production in renal proximal tubular (HK-2) cells. Interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) were measured. TGF-beta(1) induced an increase in IL-8 and MCP-1 (both P < 0.05) compared with control levels. CTGF was effectively silenced using small interference RNA (siRNA) in HK-2 cells. RT-PCR and real-time PCR confirmed a 94% reduction in CTGF mRNA. In the CTGF-silenced cells, TGF-beta(1)-stimulated IL-8 and MCP-1 secretion was not altered compared with control cells. Similarly, basal secretion of IL-8 and MCP-1 was not changed in CTGF-silenced cells. The direct effect of CTGF (20, 200, and 400 ng/ml) on IL-8 and MCP-1 was assessed at 24-, 48-, and 72-h time points and no stimulation was observed. Our studies further demonstrate that in the CTGF gene-silenced cells, CTGF partially mediates TGF-beta(1)-induced fibronectin and collagen IV secretion. These data suggest that TGF-beta(1) induced IL-8 and MCP-1 via CTGF-independent pathway. TGF-beta mediates both fibrosis and chemokine production in the proximal tubule of the kidney. However, CTGF plays a more specific role as a downstream mediator of TGF-beta(1)-induced fibrosis.

Mast Cell Tryptase in Mast Cell Granules Enhances MCP-1 and Interleukin-8 Production in Human Endothelial Cells

OBJECTIVE

Recent studies have highlighted the pathogenetic importance of chronic inflammation in cardiovascular disorders such as congestive heart failure and atherosclerosis. Mast cells release a wide variety of immune mediators that may initiate inflammatory responses, whereas endothelial cells (ECs) play a prominent role in the pathogenesis of cardiovascular diseases by secreting cytokines. The purpose of this study was to clarify the role of mast cells as an activator of ECs.

METHODS AND RESULTS

ECs harvested from human umbilical cord veins were stimulated with mast cell granules (MCGs) prepared from sonicated human leukemic mast cells. The supernatants and total RNA from cells were collected. Levels of interleukin (IL)-1beta, tumor necrosis factor-alpha, and granulocyte colony-stimulating factor remained unchanged up to 24 hours. In contrast, levels of monocyte chemoattractant protein-1 (MCP-1) and IL-8 increased significantly within 6 hours. Northern blot analysis revealed an increase in MCP-1 and IL-8 mRNA expression in MCG-treated ECs. Induction of these chemokines was attenuated by antitryptase neutralizing antibody. Furthermore, MCP-1 and IL-8 were induced in ECs by incubation with human mast cell tryptase, but not with chymase.

CONCLUSIONS

These results indicate that the production of MCP-1 and IL-8 in ECs was induced by MCG and amplified by tryptase.

Cytokines and growth factors involved in apoptosis and proliferation of vascular smooth muscle cells

This review focuses on the role of cytokines and growth factors involved in the regulation of smooth muscle cells in an atherosclerotic plaque. As a plaque begins to develop, upon endothelial injury inflammatory cells within the lesion interact with the accumulating LDL, other inflammatory cells and smooth muscle cells and release cytokines and growth factors. The mediators released from the activated cells regulate the proliferation and/or survival of smooth muscle cells. This determines the stability and integrity of a plaque. New data emerging from various studies have provided novel insights into many of the cellular interactions and signaling mechanisms involving apoptosis of smooth muscle cells in the atherosclerotic plaques. A number of these studies, focusing on activation of inflammatory cells and the roles of chemokines, cytokines and growth factors, are addressed in this review.

Shock, inflammation and PARP

The activation of poly(ADP-ribose) polymerase (PARP) is well considered to play an important role in various patho-physiological conditions like inflammation and shock. A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants (such as peroxynitrite) as mediators of inflammation and shock. ROS (e.g., superoxide, peroxynitrite, hydroxyl radical and hydrogen peroxide) are all potential reactants capable of initiating DNA single strand breakage, with subsequent activation of the nuclear enzyme poly(ADP-ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. During the last years, numerous experimental studies have clearly demonstrated the beneficial effects of PARP inhibition in cell cultures through rodent models and more recently in pre-clinical large animal models of acute and chronic inflammation. The aim of this review is to describe recent experimental evidence implicating PARP as a pathophysiological modulator of acute and chronic inflammation.

Effect of alpha-melanocyte-stimulating hormone on interleukin 8 and monocyte chemotactic protein 1 expression in a human retinal pigment epithelial cell line

PURPOSE

To examine melanocortin receptor (from MC-1 to MC-5) mRNA and the effect of alpha-melanocyte-stimulating hormone (alpha-MSH) on interleukin 8 (IL-8) and monocyte chemotactic protein 1 (MCP-1) expression in a human retinal pigment epithelial cell line (ARPE-19) stimulated with IL-1beta or tumor necrosis factor alpha (TNF-alpha).

METHODS

Expressions of MC-1 to MC-5 mRNA were examined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). alpha-MSH and IL-1beta or TNF-alpha were added to serum-free medium. IL-8 and MCP-1 mRNA were measured by real-time PCR. IL-8 and MCP-1 protein concentrations were measured using enzyme-linked immunosorbent assay. Nuclear factor kappaB (NF-kappaB) translocation was examined by immunofluorescent staining/microscopy.

RESULTS

MC-1 to MC-5 receptor mRNA was expressed in unstimulated cells. IL-1beta stimulated IL-8 and MCP-1 mRNA at 6 h. TNF-alpha stimulated IL-8 and MCP-1 mRNA expression at 1.5 and 3 h. alpha-MSH (10(-14) to 10(-10)M) inhibited IL-8 and MCP-1 mRNA expression in the cells stimulated with IL-1beta or TNF-alpha. alpha-MSH inhibited IL-1beta or TNF-alpha-stimulated IL-8 and MCP-1 protein levels in the media. Immunofluorescent staining/microscopy of NF-kappaB in the nucleus was dense 30 min after stimulation with IL-1beta or TNF-alpha and was decreased by alpha-MSH.

CONCLUSIONS

ARPE-19 cells had MC-1 mRNA. alpha-MSH inhibited IL-8 and MCP-1 expression and protein secretion. Possibly, the effect on chemotactic factors may be via suppression of NF-kappaB translocation.

Interleukin-8 mRNA expression in synovial fluid of canine stifle joints with osteoarthritis

The objective of this study was to examine and compare the presence of interleukin (IL)-8 mRNA in canine stifle osteoarthritis (OA) differing in etiopathogenesis. Synovial fluid (SF) samples were collected from 24 clinically normal stifle joints and 46 diseased stifle joints (32 stifle joints with cranial cruciate ligament rupture (CCLR), 2 joints with CCLR and patella luxation (PL), 7 joints with medial PL and 5 joints with primary OA). The samples were centrifuged to collect synovial fluid cells for RNA extraction. Reverse transcription polymerase chain reaction (RT-PCR) was performed to obtain cDNA from all samples. Canine IL-8 mRNA expression was determined using real time PCR. Synovial fluid glass smears were made of all samples and coloured with H&E for differential cell counts. All stifle joints were radiographed and graded for the severity of OA. Sixty-one percent (28/46) of the samples from canine stifle OA had IL-8 mRNA expression in contrast to 4% (1/24) in the control stifle joints. This difference in prevalence is highly significant. There were no statistically significant pairwise differences among the mean ranks of the various OA groups for the absolute amount of IL-8 mRNA expression. Neither was there a link between the severity of OA (determined by radiographic evaluation) and the presence of IL-8 in the SF nor any significant difference in the absolute amount of IL-8 between the different OA grades. No statistical difference was found in differential cell counts between IL-8-positive and -negative SF samples. IL-8 cannot be used as a specific joint disease marker since IL-8 expression is found in OA differing in etiopathogenesis. It might, however, relate to the ongoing inflammation within the joint.

Induction of cyclooxygenase-2 expression by allergens in lymphocytes from allergic patients

Cyclooxygenase (COX) is a key enzyme in prostaglandin (PG) synthesis. Up-regulation of COX-2 expression is responsible for increased PG release during inflammatory conditions and is thought to be also involved in allergic states. In this study, we demonstrate that in human T, B and natural killer lymphocytes from allergic patients, COX-2 expression became induced upon cell challenge with specific allergens and that this process is presumably IgE dependent and occurs after CD23 receptor ligation. This induction took place at both mRNA and protein levels and was accompanied by PGD2 release. IgE-dependent lymphocyte treatment elicited, in parallel, an activation of the MAPK p38 and extracellular signal-regulated kinase 1/2, an enhancement of calcineurin (CaN) activity, and an increase of the DNA-binding activity of the nuclear factor of activated T cells and of NF-kappaB, with a concomitant decrease in the levels of the cytosolic inhibitor of kappaB, IkappaB. In addition, specific chemical inhibitors of MAPK, such as PD098059 and SB203580, as well as MG-132, an inhibitor of proteasomal activity, abolished allergen-induced COX-2 up-regulation, suggesting that this process is mediated by MAPK and NF-kappaB. However, induction of COX-2 expression was not hampered by the CaN inhibitor cyclosporin A. We also examined the effect of a selective COX-2 inhibitor, NS-398, on cytokine production by human lymphocytes. Treatment with NS-398 severely diminished the IgE-dependently induced production of IL-8 and TNF-alpha. These results underscore the relevant role of lymphocyte COX-2 in allergy and suggest that COX-2 inhibitors may contribute to the improvement of allergic inflammation through the reduction of inflammatory mediator production by human lymphocytes.

Bone marrow and blood plasma levels of IL-8 in aplastic anemia and their relationship with disease severity

Interleukin-8 (IL-8), a CXC chemokine, is also a potent inhibitor of myelopoiesis, the hematopoietic process that is severely impaired in aplastic anemia (AA). To elucidate its role in the disease, we have investigated levels of IL-8 by quantitative enzyme-linked immunosorbent assay in bone marrow and peripheral blood plasma of 27 AA patients and in the marrow of 16 controls and blood of 20 controls. Significantly increased levels of IL-8 were observed in the marrow and blood of patients as compared to controls (470.4 +/- 549.6 vs. 37.5 +/- 30.3; P < 0.0001) and (247.3 +/- 286.3 vs. 7.9 +/- 5.5; P < 0.0001), respectively. Among the patients, the IL-8 levels were higher in patients with severe AA than those with nonsevere AA in the marrow (568.8 +/- 586.9 vs. 126.3 +/- 102.5; P < 0.005) as well as in the blood (296.6 +/- 305.5 vs. 75.0 +/- 84.4; P < 0.008) plasma. The marrow and blood of 74% (20/27) of the patients had increased levels of IL-8 compared to 12% (2/16; P < 0.001) and 10% (2/20, P < 0.001) of the controls, respectively. These results suggest that IL-8 may have an important role in the pathogenesis of AA.

Human polymorphonuclear neutrophils are recruited by porcine chemokines acting on CXC chemokine receptor 2, and platelet-activating factor

BACKGROUND

Pig-to-human xenotransplantation is hampered by strong humoral and cellular immune responses, including acute vascular rejection (AVR). Infiltration of vascular xenografts by recipient polymorphonuclear neutrophils (PMN) is an early feature of AVR. Since little is known about the initiation of PMN recruitment, the present study investigated whether activated porcine endothelial cells (EC) release factors that induce human PMN recruitment.

METHODS

Primary and immortalized porcine aortic EC cultures were stimulated with phorbol-myristate acetate/ionomycin, lipopolysaccharide, tumor-necrosis factor-alpha, or interferon-gamma. The interleukin (IL)-8 concentration of porcine EC supernatants was tested by ELISA. Human and porcine PMN were isolated from peripheral blood by Ficoll sedimentation and centrifugation, characterized by morphology and flow cytometry, and analyzed for chemotaxis using Boyden chambers or Transwells. PMN chemokine receptor desensitization was determined by intracellular calcium-flux measurements.

RESULTS

Porcine EC supernatants contained significant amounts of porcine IL-8 and triggered chemotaxis in both human and porcine PMN. Chemotaxis of porcine, but not human, PMN was inhibited by anti-porcine IL-8 antibodies and recombinant porcine IL-8 induced strong chemotaxis only in porcine PMN. Porcine EC supernatants desensitized human PMN CXC-chemokine receptor (CXCR) 2, but not CXCR1, a receptor for human IL-8. Human PMN chemotaxis induced by porcine EC supernatants was significantly inhibited by blocking CXCR2 and platelet-activating factor (PAF).

CONCLUSIONS

Both chemokines acting via CXCR2 and PAF are released by porcine EC inducing efficient chemotaxis of human PMN. These mechanisms responsible for the recruitment of human PMN to porcine endothelium during cell-mediated rejection of xenografts represent potential targets for preventive strategies.

Regulation of interleukin-8 expression in human endometrial endothelial cells: a potential mechanism for the pathogenesis of endometriosis

The elevation of the proinflammatory chemoattractant cytokine levels in ectopic and eutopic endometrium of endometriosis implies an inflammatory basis for this disease. The relationship between endothelial cells and leukocytes is likely to be important in the regulation of inflammatory mediators of endometriosis. The aim of this study was to describe the temporal and spatial expression of IL-8 in human endometrial endothelial cells (HEEC) in vivo and to compare the in vitro regulation of IL-8 expression by sex steroids in HEEC from women with or without endometriosis. Eutopic endometrial tissues and endometriosis implants were grouped according to menstrual cycle phase and examined by immunohistochemistry for IL-8 expression. Endothelial cells of endometriotic implants expressed higher IL-8 immunoreactivity compared with endothelial cells of eutopic endometrium from women with or without endometriosis (P < 0.02). For in vitro studies, HEEC were isolated from women with or without endometriosis and grown to preconfluence. The purity of cultured HEEC (90-95%) was confirmed by immunocytochemistry using endothelium-specific markers, CD31 and CD146. The effects of estradiol (5 x 10(-8) m), progesterone (10(-7) m), or both on IL-8 mRNA and protein levels were analyzed by RT-PCR and ELISA, respectively. Sex steroids reduced the expression of IL-8 mRNA and protein in HEEC from women without endometriosis. In contrast, both estradiol and progesterone stimulated IL-8 mRNA and protein expression in HEEC from women with endometriosis. We postulate that the stimulation of chemokine expression by sex steroids in HEEC of women with endometriosis may play a role in the inflammatory aspect of this disease.

IL-8 responsiveness defines a subset of CD8 T cells poised to kill

CD8 T cells play a key role in host defense against intracellular pathogens. Efficient migration of these cells into sites of infection is therefore intimately linked to their effector function. The molecular mechanisms that control CD8 T-cell trafficking into sites of infection and inflammation are not well understood, but the chemokine/chemokine receptor system is thought to orchestrate this process. Here we systematically examined the chemokine receptor profile expressed on human CD8 T cells. Surprisingly, we found that CXC chemokine receptor 1 (CXCR1), the predominant neutrophil chemokine receptor, defined a novel interleukin-8/CXC ligand 8 (IL-8/CXCL8)–responsive CD8 T-cell subset that was enriched in perforin, granzyme B, and interferon-γ (IFNγ), and had high cytotoxic potential. CXCR1 expression was down-regulated by antigen stimulation both in vitro and in vivo, suggesting antigen-dependent shaping of the migratory characteristics of CD8 T cells. On virus-specific CD8 T cells from persons with a history of Epstein-Barr virus (EBV) and influenza infection, CXCR1 expression was restricted to terminally differentiated effector memory cells. In HIV-1 infection, CXCR1-expressing HIV-1–specific CD8 T cells were present only in persons who were able to control HIV-1 replication during structured treatment interruptions. Thus, CXCR1 identifies a subset of CD8 T cells poised for immediate cytotoxicity and early recruitment into sites of innate immune system activation.

Potential Role of Endotoxin as a Proinflammatory Mediator of Atherosclerosis

Atherosclerosis is increasingly recognized as a chronic inflammatory disease. Although a variety of inflammatory markers (ie, C-reactive protein) have been associated with atherosclerosis and its consequences, it is important to identify principal mediators of the inflammatory responses. One potentially important source of vascular inflammation in atherosclerosis is bacterial endotoxin. Mutations in Toll-like receptor 4 (TLR-4), an integral component of the endotoxin signaling complex, are fairly common in the Caucasian population and have recently been associated with reduced incidence of atherosclerosis and other cardiovascular diseases in some studies. Moreover, epidemiological studies suggest that endotoxemia at levels as low as 50 pg/mL constitutes a strong risk factor for the development of atherosclerosis. Endotoxin concentrations in this range may be produced by a variety of common subclinical Gram-negative infections. In this article, we outline the main elements of the endotoxin signaling receptor complex that initiates proinflammatory signaling (lipopolysaccharide binding protein [LBP], CD14, TLR-4, and MD-2) and discuss how changes in expression of these molecules may affect proatherogenic responses in the vessel wall. We also describe some of the proinflammatory effects of endotoxin that may be relevant to atherosclerosis, and discuss how serum lipoproteins, especially high-density lipoprotein, may modulate endotoxin-induced inflammatory responses. Further, we discuss recent findings suggesting that the lipid-lowering statins may have an additional protective role in blocking at least some of these proinflammatory signaling pathways. Finally, we discuss species diversity with regard to endotoxin signaling that should be considered when extrapolating experimental data from animal models to humans.

Increased CXCL8 (IL-8) expression in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory disease of the CNS which is characterized by large mononuclear cell infiltration and significant demyelination. CXCL8 is a chemo-attractant for both neutrophils and monocytes and triggers their firm adhesion to endothelium. In this study, we demonstrate that serum CXCL8 and CXCL8 secretion from PBMCs are significantly higher in untreated MS patients compared to controls and are significantly reduced in MS patients receiving interferon-beta1a therapy. We suggest that CXCL8 may serve as a marker of monocyte activity in MS and may play a role in monocyte recruitment to the CNS.

Lipoprotein(a): new insights into mechanisms of atherogenesis and thrombosis

Lipoprotein(a) (Lp[a]) continues to be a controversial molecule regarding its role in human vascular disease. Although the physiologic role of this molecule is still unclear, novel discoveries within the last few years have suggested numerous mechanisms whereby Lp(a) may contribute to atherosclerosis and its complications in human subjects. These effects may differentially occur in vascular tissue and circulating blood compartments. A complex interplay between tissue-specific effects is probably more relevant to the pathogenicity of this molecule than one single effect alone. This review briefly describes the structure of Lp(a) in relation to its biochemical function, summarizing the current literature on various pathophysiologic mechanisms of Lp(a)-induced vascular disease and the role of cell and tissue-specific effects in promoting atherogenesis and thrombosis.

Interleukin (IL)-8 (CXCL8) induces cytokine expression and superoxide formation by guinea pig neutrophils infected with Mycobacterium tuberculosis

SETTING

Interleukin (IL)-8, a neutrophil attracting chemokine, is known to be made by a variety of leukocyte populations following stimulation by Mycobacterium tuberculosis.

OBJECTIVE

The effect of recombinant guinea pig IL-8 on the ability of neutrophils to generate a cytokine response after infection with M. tuberculosis H37Ra was examined.

DESIGN

Recombinant gpIL-8 was produced by subcloning the gene into Escherichia coli and purification over a nickel column. The identity of the rgpIL-8 was confirmed by sequencing. Neutrophils were harvested from the blood of non-vaccinated or M. bovis BCG-vaccinated guinea pigs and tested for their ability to migrate toward media alone, 10 microg/ml PPD, f-Met-Leu-Phe (f-MLP), or rgpIL-8 in 96-well chemotactic chambers. Neutrophils were also pre-stimulated with rgpIL-8 then restimulated with LPS (10 microg/ml) or infected in vitro with M. tuberculosis H37Ra (MOI 1:1).

RESULTS

Recombinant gpIL-8 and f-MLP induced significant chemotaxis in neutrophils from both non-vaccinated and BCG-vaccinated guinea pigs, with the best chemotaxis occurring at a concentration of 10(-7)M. Real-time PCR analysis revealed that pre-treatment of neutrophils induced elevated levels of IL-8 and TNF-alpha mRNA and protein as well as superoxide, but not mRNA for MCP-1, IFN-gamma, or TGF-beta when compared to neutrophils pre-stimulated with media alone.

CONCLUSIONS

The presence of IL-8 early in the host response to M. tuberculosis infection may be an important contributor to a successful immune response. How essential a role IL-8 plays remains unknown and merits further study.

Toll-like receptor (TLR) expression and TLR-mediated cytokine/chemokine production by human uterine epithelial cells

The objective of this study was to examine the expression of toll-like receptors (TLRs) by the uterine epithelial cell line ECC-1 and to determine if stimulation of the expressed TLRs induces changes in cytokine and/or chemokine secretion. The expression of TLR1 to TLR9 by ECC-1 cells was demonstrated by reverse transcription polymerase chain reaction, with only TLR10 not being expressed. Stimulation of ECC-1 cells using agonists to TLR2, TLR4 and TLR5 induced the expression of the chemokines interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1), as well as the pro-inflammatory cytokine IL-6, and occurred in a dose-dependent manner. In response to zymosan and flagellin, pathogen-associated molecular patterns (PAMP) that are recognized by TLR2 and TLR5 respectively, ECC-1 cells secreted significantly more IL-8, MCP-1 and IL-6 than in response to other TLR agonists. In contrast, agonists to TLR3, TLR7, and TLR9 had no effect on the secretion of the 13 cytokines or chemokines analysed. These results indicate that uterine epithelial cells are important sentinels of the innate immune system. Further it indicates that all but one of the known TLRs are expressed by ECC-1 cells and that stimulation through specific TLRs mediates changes in the expression of key chemokines and pro-inflammatory cytokines that aid in the defence of the uterus against potential pathogens.

Human neutrophils synthesize IL-8 in an IgE-mediated activation

It has been demonstrated that neutrophils are responsible for the release of large amounts of the inflammatory chemokine interleukin-8 (IL-8), associated with inflammation. To further define the mechanisms implicated, we have analyzed the response of human neutrophils from allergic patients to specific antigens or challenge with anti-immunoglobulin (Ig)E antibodies. Neutrophils showed a dose- and time-dependent production of IL-8. The release of the cytokine was parallel to expression of IL-8 mRNA analyzed by the polymerase chain reaction. This expression was transient-it occurred after 3 h of anti-IgE treatment and was maintained for 18 h. Trifluoperazine, EGTA, reduced nicotinamide adenine dinucleotide phosphate-oxidase inhibitors, and reactive oxygen species (ROS) scavengers inhibited IL-8 production, indicating a critical dependence of calcium and oxidative stress. Moreover, an inhibitory effect of cyclosporin A, an immunosuppressor that inhibits calcineurin activity, on IL-8 release and IL-8 mRNA expression was observed. This is the first evidence of the involvement of ROS and calcium/calcineurin in IgE-dependent IL-8 production. These findings open new perspectives into the functional role of neutrophils in IgE-associated diseases.

Differential regulation of IGF-II-induced IL-8 by extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinases in human keratinocytes

In order to study the relationship between insulin like growth factor-II (IGF-II) and interleukin-8 (IL-8) that are upregulated in psoriasis, we monitored IL-8 expression in IGF-II-treated human keratinocytes and explored the signaling pathways of IL-8 expression by IGF-II. IGF-II increased the IL-8 mRNA and protein levels in human keratinocytes. The upregulation of IL-8 expression by IGF-II was reduced by pretreatment with inhibitors of tyrosine kinase, Src, PI3-kinase, and ERK, but not by p38. Furthermore, IGF-II remarkably increased the DNA binding activities of NF-kappaB and AP-1, and the IL-8 promoter activity. However, cotransfection with IkappaB mutant blocked the IGF-II-induced IL-8 promoter activity. In addition, cotransfection with dominant negative MEK1 mutant, but not with dominant negative p38 mutant, blocked the IGF-II-induced IL-8 promoter activity. These results suggest that IGF-II is involved in the pathogenesis of psoriasis by inducing IL-8 gene expression through the tyrosine kinase-Src-ERK1/2-AP-1 pathway, and the PI3-kinase and NF-kappaB pathway.

Pleiotropic effects of CXC chemokines in gastric carcinoma: differences in CXCL8 and CXCL1 expression between diffuse and intestinal types of gastric carcinoma

CXC chemokines modulate host immunity, neovascularization, growth and invasive behaviour of tumours. Despite their relevance in tumour biology, chemokine expression in intestinal- and diffuse-type gastric carcinoma, which exhibit a completely different growth pattern, has not been investigated in detail. In this study, expression of the CXC chemokines CXCL8 [interleukin (IL)-8], CXCL1 [growth-related oncogene alpha (Gro alpha)], CXCL9 [monokine induced by interferon (IFN)-gamma] and CXCL10 [IFN-gamma-inducible protein-10 (IP-10)] and the corresponding chemokine receptors CXCR1-3 was investigated by immunohistochemistry in intestinal- and diffuse-type gastric carcinoma. Tumour cells of all patients expressed CXCL8. CXCL8 expression was significantly stronger in tumour cells of diffuse- rather than intestinal-type gastric carcinoma (P < 0.01) as determined by a semiquantitative score. CXCL1 was expressed almost exclusively by diffuse- but not intestinal-type carcinoma cells. The corresponding chemokine receptors, CXCR1 and CXCR2, were found on carcinoma cells. Furthermore, CXCL8 expression correlated with number of tumour vessels (P < 0.01), suggesting an angiogenetic function in gastric carcinoma not only in vitro but also in vivo. CXCL10 and CXCL9, attractants for T cells, were expressed by peritumorous macrophages in close proximity to IFN-gamma-producing CXCR3-positive T cells in both tumour types. These chemokines may attract gastric carcinoma-infiltrating T cells via an IFN-gamma-mediated pathway and enhance host immunity against the tumour. In gastric carcinoma a complex interplay between CXC-chemokine signals derived from both tumour cells and tumour-infiltrating immune cells may exhibit pleiotropic effects in tumour biology that go far beyond their originally described functions as leucocyte chemoattractants. Because CXCL8 and CXCL1, which are known to increase growth and invasive behaviour of malignant tumours, are significantly stronger expressed in diffuse- than intestinal-type gastric carcinoma, one may speculate that these chemokines influence the different growth pattern of gastric carcinoma types.

Reduction in the evolution of murine type II collagen-induced arthritis by treatment with rosiglitazone, a ligand of the peroxisome proliferator-activated receptor gamma

OBJECTIVE

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The thiazolidinedione rosiglitazone is a PPARgamma ligand that modulates the transcription of target genes. The aim of this study was to investigate the effects of rosiglitazone on the inflammatory response in mice with collagen-induced arthritis (CIA).

METHODS

CIA was induced in DBA/1J mice by an intradermal injection of 100 microl of an emulsion of bovine type II collagen (CII; 100 microg) in Freund's complete adjuvant (CFA) at the base of the tail. On day 21, a second injection of CII in CFA was administered. Rosiglitazone (10 mg/kg/day) or vehicle (10% DMSO) was administered beginning on day 25 (arthritis onset) until day 35. Clinical, radiographic, histopathologic, and laboratory assessments were performed.

RESULTS

Mice immunized with CII in CFA developed erosive arthritis of the hind paws. Macroscopic evidence of CIA first appeared as periarticular erythema and edema of the hind paws. The incidence of CIA was 100% by day 27 in the CII-challenged mice, and the severity progressed over the 35-day study period. Radiographic evaluation revealed focal resorption of bone. Histopathologic features of CIA included erosion of cartilage at the joint margins. Rosiglitazone treatment ameliorated the clinical signs on days 26-35 and improved the histologic findings in the joint and paw. The degree of oxidative and nitrosative damage was significantly reduced in rosiglitazone-treated mice, as indicated by elevation of malondialdehyde levels, formation of nitrotyrosine, and activation of poly(ADP-ribose) polymerase. Plasma levels of the proinflammatory cytokines tumor necrosis factor, interleukin-1beta, and interleukin-6 were also significantly reduced by rosiglitazone treatment.

CONCLUSION

These data demonstrate that rosiglitazone exerts an antiinflammatory effect on chronic inflammation and is able to ameliorate the tissue damage associated with CIA.

Nicotine induces human neutrophils to produce IL-8 through the generation of peroxynitrite and subsequent activation of NF-kappaB

Leukocytosis in tobacco smokers has been well recognized; however, the exact cause has not been elucidated. To test the hypothesis that tobacco nicotine stimulates neutrophils in the respiratory tract to produce IL-8, which causes neutrophilia in vivo, we examined whether nicotine induces neutrophil-IL-8 production in vitro; the causative role of NF-kappaB in its production, in association with the possible production of reactive oxygen intermediates that activate NF-kappaB; and the nicotinic acetylcholine receptors (nAChRs) involved in IL-8 production. Nicotine stimulated neutrophils to produce IL-8 in both time- and concentration-dependent manners with a 50% effective concentration of 1.89 mM. A degradation of IkappaB-alpha/beta proteins and an activity of NF-kappaB p65 and p50 were enhanced following nicotine treatment. The synthesis of superoxide and the oxidation of dihydrorhodamine 123 (DHR) were also enhanced. The NOS inhibitor, nomega-Nitro-l-arginine methyl ester, prevented nicotine-induced IL-8 production, with an entire abrogation of DHR oxidation, IkappaB degradation, and NF-kappaB activity. Neutrophils spontaneously produced NO whose production was not increased, but rather decreased by nicotine stimulation, suggesting that superoxide, produced by nicotine, generates peroxynitrite by reacting with preformed NO, which enhances the NF-kappaB activity, thereby producing IL-8. The nAChRs seemed to be involved in IL-8 production. In smokers, blood IL-8 levels were significantly higher than those in nonsmokers. In conclusion, nicotine stimulates neutrophil-IL-8 production via nAChR by generating peroxynitrite and subsequent NF-kappaB activation, and the IL-8 appears to contribute to leukocytosis in tobacco smokers.

Hypoxia increases 25-hydroxycholesterol-induced interleukin-8 protein secretion in human macrophages

Interleukin-8 (IL-8) is a chemotactic factor for T-lymphocytes and smooth muscle cells and may therefore have an important effect in atherogenesis. It is secreted from oxysterol-containing foam cells which have been found in hypoxic zones in atherosclerotic plaques. The aim of this study was to investigate the effect of hypoxia on the secretion of IL-8 by oxysterol-stimulated macrophages. Hypoxia enhances 25-hydroxycholesterol (25-OH-chol)-induced IL-8 secretion in human monocyte-derived macrophages. The effect is most pronounced when macrophages are incubated with low concentrations of 25-OH-chol. Both 25-OH-chol and hypoxia increases the intracellular level of the signalling molecule hydrogen peroxide (H(2)O(2)). This event coincided with an enhanced binding of the transcription factor c-jun to the IL-8 gene promoter and an increased IL-8 mRNA expression in hypoxic macrophages. These observations suggest that similar intracellular signalling pathways are used for both 25-OH-chol-induced IL-8 expression and hypoxia-induced IL-8 expression. Thus, hypoxia in atherosclerotic plaques may increase the secretion of IL-8 from oxysterol-containing foam cells, which subsequently may accelerate the progression of atherosclerosis.

The Chemokine Connection: Hormonal and Embryonic Regulation at the Human Maternal-Embryonic Interface—A Review

Chemokines are small polypeptides that attract specific leukocyte subsets by binding to cell-surface receptors. In reproductive biology, they have been implicated in ovulation, menstruation, and embryo implantation, and pathological processes such as preterm delivery, HIV infection, and endometriosis. It is known that successful implantation requires a functionally normal embryo at the blastocyst stage and a receptive endometrium that is adequately communicated through the implantation process. This crosstalk is highly regulated, with numerous molecules taking part. Accumulated evidence suggests that chemokines produced and received by the endometrial epithelium and the human blastocyst are implicated in this molecular network. Here, we present updated information on the presence and hormonal and embryonic regulation of chemokines and their receptors during human implantation.

Interactions between inducible nitric oxide and other inflammatory mediators during Helicobacter pylori infection

BACKGROUND

Recent studies in both humans and animal models strongly suggest the contribution of the host immune response to Helicobacter pylori-related disease. Inducible nitric oxide synthase has been shown to be up-regulated in the gastric epithelium during H. pylori gastritis, suggesting a role in inflammation.

MATERIALS AND METHODS

C57BL/6 wild-type and inducible nitric oxide synthase gene knockout mice were infected with H. pylori strain SS1. Expression of macrophage inflammatory protein-2 (MIP-2), interleukin-1 beta (IL-1 beta), Th1 (IL-2 and gamma interferon) and Th2 (IL-4 and IL-10) cytokines, and inducible cyclooxygenase mRNA in mice was determined in mouse gastric tissues and quantified using either competitive reverse transcription-polymerase chain reaction or competitive polymerase chain reaction following reverse transcription.

RESULTS

The Th1 cytokine gamma interferon was only detected in wild-type and inducible nitric oxide synthase gene knockout infected mice, while a Th2 (IL-4) response was not detected. H. pylori induced MIP-2 and IL-1 beta mRNA in mice.

CONCLUSIONS

Because similar levels of inflammatory mediators were noted in both wild-type and nitric oxide synthase gene knockout infected mice, our data suggest that inducible nitric oxide synthase does not influence expression of these inflammatory mediators in the early stages of H. pylori infection in mice.

Neutrophils influence melanoma adhesion and migration under flow conditions

We have studied human melanoma cell (C8161) adhesion and migration in response to stimulation by soluble collagen IV (CIV) using a modified Boyden chamber. In this modified chamber, shear flow can be introduced over the cell-substrate interface, affecting tumor cell chemotactic migration through a microporous filter. A relatively high level of intercellular adhesion molecule-1 (ICAM-1) was found on C8161 cells. In contrast, levels of beta(2)-integrins (e.g., LFA-1 and Mac-1), the molecules that would be necessary for C8161 stable adhesion to the endothelium substrate, were found to be very low on these melanoma cells. As a result, C8161 transendothelial migration under a flow condition of 4 dyn/cm(2) decreased by 70% as compared to static migration. When human neutrophils (PMNs) were present in the tumor cell suspension, C8161 migration recovered by 85% over C8161 cells alone under the 4 dyn/cm(2) flow condition. Blocking ICAM-1 on C8161 cells or Mac-1 on PMNs significantly inhibited C8161-PMN adhesion and subsequent C8161 migration through the endothelium under flow conditions. In addition, increased interleukin-8 production and Mac-1 expression by PMNs were detected when they were co-cultured with C8161 melanoma cells. These results suggest that transmigration of C8161 cells under flow conditions can be influenced by PMNs, mediated by Mac-1/ICAM-1 adhesive interactions and enhanced by altered cytokine production.

The strategy of T cell antigen-presenting cell encounter in antigen-draining lymph nodes revealed by imaging of initial T cell activation

The development of an immune response critically relies on the encounter of rare antigen (Ag)-specific T cells with dendritic cells (DCs) presenting the relevant Ag. How two rare cells find each other in the midst of irrelevant other cells in lymph nodes (LNs) is unknown. Here we show that initial T cell activation clusters are generated near high endothelial venules (HEVs) in the outer paracortex of draining LNs by retention of Ag-specific T cells as they exit from HEVs. We further show that tissue-derived DCs preferentially home in the vicinity of HEVs, thus defining the site of cluster generation. At this location DCs efficiently scan all incoming T cells and selectively retain those specific for the major histocompatibility complex-peptide complexes the DCs present. Such strategic positioning of DCs on the entry route of T cells into the paracortex may foster T cell-DC encounter and thus optimize initial T cell activation in vivo.

Low-level endotoxin induces potent inflammatory activation of human blood vessels: inhibition by statins

BACKGROUND

Low-level endotoxemia (ie, >or=50 pg/mL) in apparently healthy subjects was recently identified as a powerful, independent risk factor for atherosclerosis.

METHODS AND RESULTS

We treated human saphenous veins (HSVs) with low levels of endotoxin. Release of the proinflammatory chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. Superoxide was determined by using the fluorescent probe dihydroethidium (HE), and monocyte binding was assessed with calcein-labeled U-937 cells. Three- to 4-fold increases in MCP-1 and IL-8 release were observed at endotoxin concentrations of 100 pg/mL; these increases were inhibited by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin. Studies in cultured endothelial cells suggest that the mechanism is related to inhibition of isoprenylation (ie, geranylgeranylation) rather than cholesterol formation. Endotoxin produced dose-dependent increases in HE fluorescence that were inhibited by the superoxide dismutase mimics Tiron and MnTBAP. Endotoxin potently induced U-937 cell binding to HSV; binding was inhibited by both Tiron and atorvastatin. Toll-like receptor-4 expression was detected in cultured HSV endothelial and smooth muscle cells and in intact HSV.

CONCLUSIONS

Clinically relevant levels of endotoxin, as reported in ambulatory populations, have profound inflammatory effects on intact HSV. Inhibition of endotoxin-induced vascular inflammation might contribute to the beneficial effects of statins in treating atherosclerosis.

Synthesis and structure-activity relationship of 2-amino-3-heteroaryl-quinoxalines as non-peptide, small-molecule antagonists for interleukin-8 receptor

Interleukin-8 modulation is implicated in many inflammatory and cancer diseases. Starting from a mass-screening hit, the synthesis and structure-activity relationship of 2-amino-3-heteroarylquinoxalines as non-peptide, small molecule interleukine-8 receptor antagonists have been developed. The optimized derivatives, PD 0210293 (13y) and PD 0220245 (13r), show inhibition of both IL-8 receptor binding and IL-8-mediated neutrophil chemotaxis.

Lactobacillus gasseri OLL2716 as a probiotic in clarithromycin-resistant Helicobacter pylori infection

BACKGROUNDS AND AIM

Clarithromycin (CAM)-resistant Helicobacter pylori sometimes offers serious problems with eradication by antibiotics. The aim of this study was to determine whether a probiotic can be an alternative therapy in CAM-resistant Hp infection.

METHODS

The effects of Lactobacillus gasseri (strain OLL2716) on the growth of CAM-susceptible and CAM-resistant H. pylori and interleukin (IL)-8 production provoked by these strains were examined by in vitro experiments. Moreover, mice were infected with these CAM-susceptible or CAM-resistant H. pylori, and were treated with CAM or L. gasseri.

RESULTS

In vitro experiments demonstrated that L. gasseri inhibited the growth of H. pylori and suppressed H. pylori-associated IL-8 production. Such effects were noted in CAM-resistant and CAM-susceptible H. pylori. Similarly, in an in vivo model of H. pylori infection, H. pylori colonization was significantly decreased by L. gasseri.

CONCLUSION

Therefore, L. gasseri was found to act as a probiotic in CAM-resistant H. pylori infection.

Effects of baicalin, baicalein, and wogonin on interleukin-6 and interleukin-8 expression, and nuclear factor-kappab binding activities induced by interleukin-1beta in human retinal pigment epithelial cell line

The objective of the study was to investigate the effects of baicalin, baicalein, and wogonin (plant flavonoids) on interleukin-6 (IL-6) and interleukin-8 (IL-8) protein production, mRNA expression, and nuclear factor-kappaB (NF-kappaB) binding activities induced by interleukin-1beta (IL-1beta) in human retinal pigment epithelial cell line (ARPE-19) cells. To induce IL-6 and IL-8 mRNA expression and protein levels, IL-1beta was added to serum-free medium of ARPE-19 cells and incubated. The flavonoids were added to the medium. IL-6 and IL-8 in the media were measured using enzyme-linked immunosorbent assay. Both IL-6 and IL-8 mRNA were measured by semiquantitative reverse transcription polymerase chain reaction. The binding activities of the transcription factor NF-kappaB complexes to IL-6 and IL-8 were measured by electrophoretic mobility shift assay. IL-6 and IL-8 in the culture media of ARPE-19 cells were increased by IL-1beta in a dose-dependent manner. Baicalin did not suppress IL-1beta-induced IL-6 and IL-8 production, but dexamethasone, baicalein, and wogonin, significantly suppressed IL-6 and IL-8 production. Elevation of IL-6 and IL-8 mRNA was not suppressed by baicalin but was significantly suppressed by dexamethasone, baicalein, and wogonin. NF-kappaB binding activities were not suppressed by baicalin and baicalein, but was suppressed by wogonin. Wogonin and baicalein inhibited IL-1beta-induced IL-6 and IL-8 mRNA and protein production in ARPE-19 cells. The data suggest that wogonin may inhibit IL-6 and IL-8 mRNA expression via the suppression of NF-kappaB binding activities.

Chemokine receptor expression in human endometrium

Chemokines play a role in endometrial physiology and pathology and may affect endometrial receptivity and menstrual shedding. Chemokines exert their effect by binding to their relevant receptors, the expression levels of which may modulate their action. In the present study, we examined the expression of chemokine receptors CXCR1 and CXCR2 (receptors for interleukin-8) and CCR5 (receptor for RANTES [regulated-on-activation, normal-T-cell-expressed and -secreted], macrophage inflammatory protein [MIP]-1alpha, and MIP-1beta) in human endometrium. Human endometria (n = 35) were grouped according to the menstrual cycle phase and examined by immunohistochemistry for CXCR1, CXCR2, and CCR5. In both epithelial and stromal cells, CXCR1 and CXCR2 immunoreactivity was detected. Staining was most prominent at the apical and basal aspects of epithelial cells. Intense CCR5 immunostaining was observed in epithelial and stromal compartments throughout the menstrual cycle. Epithelial and stromal staining for CXCR1 reached a peak at the midsecretory phase, during which it was significantly higher than the level of staining during the proliferative phase (P < 0.05). Immunostaining for CXCR2 and CCR5 showed no significant variation across the menstrual cycle. Expression of interleukin-8 and RANTES in endometrium, together with the presence of their receptors, suggests that autocrine and paracrine interactions involving these chemokines may participate in endometrial physiology.

Interleukin-8 production induced by the endozepine triakontatetraneuropeptide in human neutrophils: role of calcium and pharmacological investigation of signal transduction pathways

The endozepine triakontatetraneuropeptide (TTN) induces intracellular calcium ([Ca(2+)](i)) changes and is chemotactic for human neutrophils (PMNs). Because interleukin-8 (IL-8) production is Ca(2+) dependent and can be induced by chemotactic stimuli, we have investigated the ability of TTN to induce IL-8 production in PMNs, as well as the signal transduction mechanisms involved. Our results show that TTN increases IL-8 release and IL-8 mRNA expression in a concentration- and time-dependent fashion, and these effects are prevented by the Ca(2+) chelator BAPTA-AM. TTN-induced [Ca(2+)](i) changes and IL-8 mRNA expression are sensitive to pertussis toxin, to the phospholipase C (PLC) inhibitor U73122 (but not to its inactive analogue U73343) and to the protein kinase C (PKC) inhibitor calphostin C. It is therefore suggested that TTN-induced IL-8 production in human PMNs results from a G protein-operated, PLC-activated [Ca(2+)](i) rise, and PKC contributes to this effect. These findings further support the possible role of TTN in the modulation of the inflammatory processes.

Pathophysiological roles of interleukin-8/CXCL8 in pulmonary diseases

Fifteen years have passed since the first description of interleukin (IL)-8/CXCL8 as a potent neutrophil chemotactic factor. Accumulating evidence has demonstrated that various types of cells can produce a large amount of IL-8/CXCL8 in response to a wide variety of stimuli, including proinflammatory cytokines, microbes and their products, and environmental changes such as hypoxia, reperfusion, and hyperoxia. Numerous observations have established IL-8/CXCL8 as a key mediator in neutrophil-mediated acute inflammation due to its potent actions on neutrophils. However, several lines of evidence indicate that IL-8/CXCL8 has a wide range of actions on various types of cells, including lymphocytes, monocytes, endothelial cells, and fibroblasts, besides neutrophils. The discovery of these biological functions suggests that IL-8/CXCL8 has crucial roles in various pathological conditions such as chronic inflammation and cancer. Here, an overview of its protein structure, mechanisms of production, and receptor system will be discussed as well as the pathophysiological roles of IL-8/CXCL8 in various types of lung pathologies.

Upregulation of CXCR1 by proliferating cells in patients with lymphoproliferative disease of granular lymphocytes

The expression and the functional activities of different chemokine receptors (CC motif: CCR1, CCR2, CCR3, CCR5, CCR6; CXC motif: CXCR1, CXCR2, CXCR3, CXCR4, CXCR5) were investigated in 12 patients with lymphoproliferative disease of granular lymphocytes (LDGL). Six patients were characterized by the proliferation of CD3+ve GL and six patients by the expansion of CD3-ve GL. The interleukin 8 (IL-8/CXCL8) receptor CXCR1 was expressed in 12/12 patients, the CXCR4 in 6/12 patients (four CD3+ve and two CD3-ve) and the CXCR3 in 3/12 patients (one CD3+ve and two CD3-ve). CXCR1 was expressed only by proliferating GL. Other CC and CXC receptors were not expressed on proliferating GL (< 2%). In functional assays, purified GL from the patients displayed significant migration in response to specific chemokines, indicating that CXCR1, CXCR3 and CXCR4 were functionally active in these patients. In addition, a significant reduction of IL-8/CXCL8-mediated cell migration was reported in the presence of anti-CXCR1 monoclonal antibody. Our results indicate that expanding cells from patients with LDGL express specific CXCR. These data may help to define functional properties of proliferating GL in patients with LDGL and contribute toward the understanding of the complex clinical features of this disease. In particular, as CXCR1 was expressed in all of the patients studied, we speculate that abnormal expression of this receptor on proliferating GL might play a role in the pathogenesis of neutropenia, which represents a common feature in LDGL patients.

Expression and regulation of interleukin-8 in human fallopian tubal cells

OBJECTIVE

The human fallopian tube creates the microenvironment for fertilization and early embryogenesis. Salpingitis may result in infertility and ectopic pregnancy by causing tubal blockage and hydrosalpinx. To better understand the relationship between infectious inflammation and tubal damage, we investigated the expression and regulation of interleukin-8 in human tubal epithelial and stromal cells in culture.

STUDY DESIGN

Human fallopian tube epithelial and stromal cell cultures were used to measure interleukin-8 messenger RNA and interleukin-8 protein levels at basal conditions and after stimulation with interleukin-1alpha and tumor necrosis factor-alpha. Northern blot analysis and enzyme-linked immunosorbent assay were used to evaluate messenger RNA and protein levels, respectively.

RESULTS

Tubal epithelial cells expressed high levels of interleukin-8 messenger RNA and secreted significantly more immunoreactive interleukin-8 into culture medium than did tubal stromal cells (2065 +/- 153 pg/mg vs 530 +/- 56 pg/mg of total protein, P <.01). Interleukin-1alpha and TNF-alpha treatments induced a concentration-dependent increase in interleukin-8 messenger RNA expression in both epithelial and stromal cells. However, at the protein level, although interleukin-1alpha and tumor necrosis factor-alpha treatments increased the secretion of interleukin-8 from stromal cells significantly, similar treatments had no effect on interleukin-8 secretion from epithelial cells.

CONCLUSION

The expression of interleukin-8 in human tubal epithelial and stromal cells is different. Interleukin-8 expression of tubal epithelial and stromal cells in response to inflammatory cytokines such as interleukin-1alpha and tumor necrosis factor-alpha also varies. This may be important in the pathogenesis of salpingitis.

Albumin stimulates interleukin-8 expression in proximal tubular epithelial cells in vitro and in vivo

Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the stimuli for leukocyte recruitment are not fully understood. IL-8 is a potent chemokine produced by proximal tubular epithelial cells (PTECs). Whether nephrotic proteins stimulate tubular IL-8 expression remains unknown. Acute exposure of human PTECs to albumin induced IL-8 gene and protein expression time- and dose-dependently. Apical albumin predominantly stimulated basolateral IL-8 secretion. Electrophoretic mobility shift assay demonstrated nuclear translocation of NF-kappaB, and the p65/p50 subunits were activated. NF-kappaB activation and IL-8 secretion were attenuated by the NF-kappaB inhibitors pyrrolidine dithiocarbamate and cell-permeable peptide. Albumin upregulated intracellular reactive oxygen species (ROS) generation, while exogenous H2O2 stimulated NF-kappaB translocation and IL-8 secretion. Albumin-induced ROS generation, NF-kappaB activation, and IL-8 secretion were endocytosis- and PKC-dependent as these downstream events were abrogated by the PI3K inhibitors LY294002 and wortmannin, and the PKC inhibitors GF109203X and staurosporin, respectively. In vivo, IL-8 mRNA expression was localized by in situ hybridization to the proximal tubules in nephrotic kidney tissues. The intensity of IL-8 immunostaining was higher in nephrotic than non-nephrotic subjects. In conclusion, albumin is a strong stimulus for tubular IL-8 expression, which occurs via NF-kappaB-dependent pathways through PKC activation and ROS generation.

Pyridostigmine bromide modulates topical irritant-induced cytokine release from human epidermal keratinocytes and isolated perfused porcine skin

Gulf War personnel were given pyridostigmine bromide (PB) as a prophylactic treatment against organophosphate nerve agent exposure, and were exposed to the insecticide permethrin and the insect repellent N,N-diethyl-m-toluamide (DEET). The purpose of this study was to assess the effects of PB to modulate release of inflammatory biomarkers after topical chemical exposure to chemical mixtures containing permethrin and DEET applied in ethanol or water vehicles. Treatments were topically applied to isolated perfused porcine skin flaps (IPPSFs). Concentrations of interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha) and prostaglandin E(2) (PGE(2)) were assayed in perfusate to probe for potential inflammatory effects after complex mixture application. IPPSFs (n=4/treatment) were topically dosed with mixtures of permethrin, DEET, and permethrin/DEET, in ethanol. Each treatment was repeated with perfusate spiked with 50 ng/ml of PB. Perfusate was also spiked with 30 ng/ml diisopropylfluorophosphate to simulate low level organophosphate nerve agent exposure. Timed IPPSF venous effluent samples (0.5,1,2,4, and 8 h) were assayed by ELISA for IL-8 and TNF-alpha and by EIA for PGE(2). Overall, PB infusion caused a decrease or IL-8 and PGE(2) release. Effects on TNF-alpha were vehicle dependent. To probe the potential mechanism of this PB effect, human epidermal keratinocyte HEK cell cultures were exposed to permethrin DEET permethrin/DEET, with and without PB in DMSO. IL-8 was assayed at 1, 2, 4, 8, 12 and 24 h. PB suppressed IL-8 in permethrin and ethanol treatment from 4 to 24 h confirming the IPPSF results. In conclusion, these studies suggest that systemic exposure to PB suppressed IL-8 release at multiple time points in two skin model systems. This interaction merits further study.

Oral mucosal keratinocytes express RANTES and ICAM-1, but not interleukin-8, in oral lichen planus and oral lichenoid reactions induced by amalgam fillings

Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa characterized by a band-like accumulation of lymphocytes in the connective tissue adjacent to the basement membrane as well as intraepithelially. Amalgam fillings can induce oral lichenoid reactions (OLR) that are similar to OLP. The adhesion molecule ICAM-1 and the chemokines interleukin-8 and RANTES all play central roles in leucocyte trafficking. The aim of this study was to investigate the possible role of these molecules in the migration of leucocytes into the oral mucosa in OLP and OLR. Standard immunoperoxidase techniques were used to visualize the expression of ICAM-1, RANTES and interleukin-8 in frozen biopsy sections. ICAM-1 was expressed by endothelial cells, but not by keratinocytes, in normal oral mucosa. ICAM-1 was expressed by keratinocytes in 11 of 12 biopsies of OLP and in six of seven biopsies of OLR. In all of these cases ICAM-1 was also expressed by endothelial cells and leucocytes. Although not present in normal oral mucosa, RANTES was expressed by keratinocytes in 21 of 24 biopsies of OLP and in seven of seven cases of OLR. Interleukin-8 was not detected in any of the samples. The expression of ICAM-1 and RANTES by epithelial keratinocytes in the oral mucosa in OLP and OLR could be a key inflammatory mechanism in these diseases.

Modulation of growth factor/cytokine synthesis and signaling by 1alpha,25-dihydroxyvitamin D(3): implications in cell growth and differentiation

Distinct from its classic functions in the regulation of calcium and phosphorus metabolism as a systemic hormone, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] is involved in the local control and regulation of cellular growth and differentiation in various tissues, including epidermis (keratinocytes) and bone (osteoblasts and osteoclasts). In this review, the impact of 1alpha,25(OH)(2)D(3) on growth factor/cytokine synthesis and signaling is discussed, particularly as it pertains to bone cells and keratinocytes. 1alpha,25(OH)(2)D(3) not only regulates growth factor/cytokine synthesis but may also alter growth factor signaling. Recently discovered examples for such interactions are the interactions between the vitamin D receptor and the mothers against decapentaplegic-related proteins that function downstream of TGFbeta receptors. Inhibitory effects of 1alpha,25(OH)(2)D(3) on keratinocytes through TGFbeta activation and IL-1alpha, IL-6, and IL-8 suppression may provide a rationale for its beneficial effects in the treatment of hyperproliferative skin disorders, whereas stimulatory effects through the epidermal growth factor-related family members and platelet-derived growth factor may be operative in its beneficial effects in skin atrophy and wound healing. Modulation of cytokines and growth factors by 1alpha,25(OH)(2)D(3) during bone remodeling plays an important role in the coupling of osteoblastic bone formation with osteoclastic resorption to maintain bone mass.

A potent and selective nonpeptide antagonist of CXCR2 inhibits acute and chronic models of arthritis in the rabbit

Much evidence implicates IL-8 as a major mediator of inflammation and joint destruction in rheumatoid arthritis. The effects of IL-8 and its related ligands are mediated via two receptors, CXCR1 and CXCR2. In the present study, we demonstrate that a potent and selective nonpeptide antagonist of human CXCR2 potently inhibits (125)I-labeled human IL-8 binding to, and human IL-8-induced calcium mobilization mediated by, rabbit CXCR2 (IC(50) = 40.5 and 7.7 nM, respectively), but not rabbit CXCR1 (IC(50) = >1000 and 2200 nM, respectively). These data suggest that the rabbit is an appropriate species in which to examine the anti-inflammatory effects of a human CXCR2-selective antagonist. In two acute models of arthritis in the rabbit induced by knee joint injection of human IL-8 or LPS, and a chronic Ag (OVA)-induced arthritis model, administration of the antagonist at 25 mg/kg by mouth twice a day significantly reduced synovial fluid neutrophils, monocytes, and lymphocytes. In addition, in the more robust LPS- and OVA-induced arthritis models, which were characterized by increased levels of proinflammatory mediators in the synovial fluid, TNF-alpha, IL-8, PGE(2), leukotriene B(4), and leukotriene C(4) levels were significantly reduced, as was erythrocyte sedimentation rate, possibly as a result of the observed decreases in serum TNF-alpha and IL-8 levels. In vitro, the antagonist potently inhibited human IL-8-induced chemotaxis of rabbit neutrophils (IC(50) = 0.75 nM), suggesting that inhibition of leukocyte migration into the knee joint is a likely mechanism by which the CXCR2 antagonist modulates disease.

Regulation of interleukin-8 expression by HMG-CoA reductase inhibitors in human vascular smooth muscle cells

Interleukin-8 (IL-8) is a potent chemotactic factor that has been implicated in atherogenesis. HMG-CoA reductase inhibitors (statins) may reduce the cardiovascular risk and vulnerability of atherosclerotic plaque through nonlipid mechanisms such as inhibition of cytokine expression. In this study, we investigated the effects of statins on IL-8 synthesis in human vascular smooth muscle cells (VSMCs). Addition of angiotensin II (Ang II) increased IL-8 production in VSMCs in a time (0-24 h)- and dose (10(-8)-10(-6) mol/l)-dependent manner with increased IL-8 mRNA accumulation. The Ang II type 1 receptor (AT1R) antagonist candesartan, but not the Ang II type 2 receptor (AT2R) antagonist PD123319, significantly blocked Ang II-induced IL-8 production. Addition of fluvastatin decreased the basal and Ang II-induced IL-8 production in VSMCs in a dose (10(-8)-10(-5) mol/l)-dependent manner with a decrease in IL-8 mRNA accumulation. The effect of fluvastatin on IL-8 production was completely reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate, but not in the presence of squalene or farnesyl-pyrophosphate. Lipophilic cerivastatin also significantly decreased IL-8 production, while hydrophilic pravastatin showed no effect on IL-8 levels. In conclusion, we demonstrated for the first time that Ang II increased IL-8 production and fluvastatin decreased the basal and Ang II-induced IL-8 production in human VSMCs. These findings suggested that Ang II may exacerbate atherosclerosis through induction of IL-8 in VSMCs, while statins may exert therapeutic effects by modulating IL-8 synthesis in patients with atherosclerotic disease.

Interleukin-8 and growth-regulated oncogene alpha mediate angiogenesis in Kaposi's sarcoma

The development of the complex neoplasm Kaposi's sarcoma is dependent on infection with the Kaposi's sarcoma-associated herpesvirus (KSHV) and appears to be greatly enhanced by cytokines and human immunodeficiency virus type 1 (HIV-1) Tat. Interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) are chemokines involved in chemoattraction, neovascularization, and stimulation of HIV-1 replication. We have previously demonstrated that production of GRO-alpha is stimulated by exposure of monocyte-derived macrophages (MDM) to HIV-1. Here we show that exposure of MDM to HIV-1, viral Tat, or viral gp120 leads to a substantial increase in IL-8 production. We also demonstrate that IL-8 and GRO-alpha are induced by KSHV infection of endothelial cells and are crucial to the angiogenic phenotype developed by KSHV-infected endothelial cells in cell culture and upon implantation into SCID mice. Thus, the three known etiological factors in Kaposi's sarcoma pathogenesis-KSHV, HIV-1 Tat, and cellular growth factors-might be linked, in part, through induction of IL-8 and GRO-alpha.

Mycobacterium bovis BCG vaccination augments interleukin-8 mRNA expression and protein production in guinea pig alveolar macrophages infected with Mycobacterium tuberculosis

Alveolar macrophages are likely the first cell type to encounter Mycobacterium tuberculosis in a pulmonary infection, resulting in the production of chemokines. In order to evaluate this response, alveolar macrophages harvested from nonvaccinated and Mycobacterium bovis BCG-vaccinated guinea pigs were infected in vitro with live M. tuberculosis H37Ra or H37Rv (multiplicity of infection, 1:1) or cultured with lipopolysaccharide (10 micro g/ml) for 3, 12, and 24 h. Interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) mRNA expression was determined by real-time PCR. Culture supernatants were assayed for guinea pig IL-8 protein by using a human IL-8 enzyme-linked immunosorbent assay kit. Alveolar macrophages harvested from BCG-vaccinated guinea pigs produced significantly more mRNA and protein for IL-8 than alveolar macrophages harvested from nonvaccinated guinea pigs at 12 and 24 h poststimulation or postinfection. Infection with attenuated M. tuberculosis (H37Ra) stimulated alveolar macrophages isolated from BCG-vaccinated guinea pigs to produce significantly more IL-8 mRNA than did alveolar macrophages infected with a virulent strain (H37Rv) at 12 and 24 h postinfection. Significant MCP-1 mRNA production was also detected in stimulated or infected alveolar macrophages; however, prior vaccination did not significantly affect levels of MCP-1 mRNA. Alveolar macrophages isolated from BCG-vaccinated guinea pigs produced significantly more IL-8 mRNA and protein when stimulated for 24 h with heat-killed H37Ra, heat-killed H37Rv, and H37Rv cell wall, but not mannose-capped lipoarabinomannan (ManLAM), than did cells stimulated with media alone. These observations indicate that prior vaccination may alter very early events in the M. tuberculosis-infected lung.