Interleukin-8 inhalation directly provokes bronchoconstriction in guinea pigs

Prostatic stromal inflammation is associated with bladder outlet obstruction in patients with benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is a common urologic disease in older men. Prostatic inflammation research has focused on the magnitude of inflammation; its location has received little attention. We investigated whether the anatomic location of prostatic inflammation is related to the severity of lower urinary tract symptoms (LUTS), measured subjectively and objectively.

METHODS

We retrospectively analyzed hematoxylin+eosin-stained tissue specimens from 179 BPH patients who underwent transurethral resection of the prostate (TURP) or holmium laser enucleation of the prostate (HoLEP). Chronic prostatic inflammation was assessed by the grade (lymphocyte density), extent (lymphocyte distribution), and location of inflammation. Each inflammation-finding type was evaluated in relation to these clinical parameters: age, prostate volume, prostate-specific antigen (PSA) value, body mass index (BMI), the frequency of acute urinary retention (AUR) episodes, the international prostatic symptom score (IPSS), and urodynamic study results.

RESULTS

The magnitude and extent of inflammation were not associated with any clinical parameters. We classified the BPH patients into stromal (n = 72) versus non-stromal (n = 105) groups based on their inflammation's dominant location. The stromal group's prostatic volume was significantly larger than the non-stromal group's (63.8 vs 53.8 mL; P = 0.032). AUR episodes were more significantly frequent in the stromal group (36.1% vs 11.4%; P = 0.006). Between-group differences in storage parameters (ie, maximum cystometric capacity) in the urodynamic study were not significantly different. Voiding parameters differed significantly between the stromal and non-stromal groups: maximum detrusor pressure (maxPdet) (116.8 vs 94.5 cmH₂ O, P = 0.014), Pdet at the maximum flow rate (Qmax) (95.8 vs 75.4 cmH₂ O, P = 0.014), and the bladder outlet obstruction index (BOOI) (78.5 vs 56.3, P = 0.014). The stromal group's Qmax was significantly lower than the non-stromal group's (7.3 vs 9.8 mL/s, P = 0.004).

CONCLUSIONS

The location of inflammation in the prostate might be an important factor affecting the severity of LUTS, especially voiding dysfunction.

Activity of sputum p38 MAPK is correlated with airway inflammation and reduced FEV1 in COPD patients

BACKGROUND

Inflammation and remodeling of the small airways are major determinants of the progression and severity of COPD. The present study explored the correlation between sputum p38 mitogen-activated protein kinase (MAPK) activity and airway inflammation and reduction of lung function in the patients with chronic obstructive pulmonary disease (COPD).

MATERIAL AND METHODS

Sputum samples were collected from 48 COPD patients and 12 healthy persons. Sputum p38 MAPK activity was measured by Western blotting and sputum levels of CXCL8 and neutrophil, and lung function was measured. The correlation between p38MAPK activity and airway inflammation and reduction of lung function was analyzed.

RESULTS

Our results showed the significantly increased expression of phospho-p38 MAPK and CXCL8 in the sputum samples of the COPD patients. The p38 MAPK activity was remarkably correlated with the CXCL8 level and neutrophils infiltration in the airway, and the decline of lung function in the COPD patients.

CONCLUSIONS

These findings suggest the pivotal role of p38 MAPK in the airway inflammation of COPD patients. We propose p38 MAPK as a potential target for the treatment of COPD.

Respiratory syncytial virus reverses airway hyperresponsiveness to methacholine in ovalbumin-sensitized mice

Each year, approximately 20% of asthmatics in the United States experience acute symptom exacerbations, which commonly result from pulmonary viral infections. The majority of asthma exacerbations in very young children follow infection with respiratory syncytial virus (RSV). However, pathogenic mechanisms underlying induction of asthma exacerbations by RSV are not well understood. We therefore investigated the effect of post-sensitization RSV infection on lung function in ovalbumin (OVA)-sensitized BALB/c mice as a model of RSV asthma exacerbations. OVA sensitization of uninfected female BALB/c mice increased bronchoalveolar lavage fluid (BALF) eosinophil levels and induced airway hyperresponsiveness to the muscarinic agonist methacholine, as measured by the forced-oscillation technique. In contrast, intranasal infection with replication-competent RSV strain A2 for 2–8 days reduced BALF eosinophil counts and reversed airway hyperresponsiveness in a pertussis toxin-sensitive manner. BALF levels of the chemokine keratinocyte cytokine (KC; a murine homolog of interleukin-8) were elevated in OVA-sensitized, RSV-infected mice and reversal of methacholine hyperresponsiveness in these animals was rapidly inhibited by KC neutralization. Hyporesponsiveness could be induced in OVA-sensitized, uninfected mice by recombinant KC or the Gαi agonist melittin. These data suggest that respiratory syncytial virus induces KC-mediated activation of Gαi, resulting in cross-inhibition of Gαq-mediated M₃-muscarinic receptor signaling and reversal of airway hyperresponsiveness. As in unsensitized mice, KC therefore appears to play a significant role in induction of airway dysfunction by respiratory syncytial virus. Hence, interleukin-8 may be a promising therapeutic target to normalize lung function in both asthmatics and non-asthmatics with bronchiolitis. However, the OVA-sensitized, RSV-infected mouse may not be an appropriate model for investigating the pathogenesis of viral asthma exacerbations.

CXCR2: From Bench to Bedside

Leukocyte recruitment to sites of infection or tissue damage plays a crucial role for the innate immune response. Chemokine-dependent signaling in immune cells is a very important mechanism leading to integrin activation and leukocyte recruitment. CXC chemokine receptor 2 (CXCR2) is a prominent chemokine receptor on neutrophils. During the last years, several studies were performed investigating the role of CXCR2 in different diseases. Until now, many CXCR2 inhibitors are tested in animal models and clinical trials and promising results were obtained. This review gives an overview of the structure of CXCR2 and the signaling pathways that are activated following CXCR2 stimulation. We discuss in detail the role of this chemokine receptor in different disease models including acute lung injury, COPD, sepsis, and ischemia-reperfusion-injury. Furthermore, this review summarizes the results of clinical trials which used CXCR2 inhibitors.

Relationship between hepatitis C virus infection and pulmonary disorders: potential mechanisms of interaction

Recently, an increasing number of reports have suggested that chronic hepatitis C virus (HCV) infection is associated with pulmonary disorders. The effects of HCV on the lung may present as worsening of lung function and impaired responses to therapy in patients with chronic obstructive pulmonary disease and asthma. Moreover, chronic HCV infection may be associated with the pathogenesis of interstitial lung disease. It is believed that chronic HCV infection may contribute to the immune responses modulating the pathogenic processes underlying pulmonary disorders and, therefore, may lead to a wide spectrum of clinical presentations. Potential candidates for a role in these immune responses are the CD8(+) T lymphocytes and inflammatory cytokines. In this review, the effects of HCV on the lung and the potential mechanisms of interaction between chronic HCV infection and pulmonary disorders will be discussed.

Respiratory syncytial virus induces airway insensitivity to beta-agonists in BALB/c mice

beta-Adrenergic agonists (beta-agonists) are commonly used to treat respiratory syncytial virus (RSV) bronchiolitis but are generally ineffective for unknown reasons. We have previously shown that RSV strain A2 inhibits bronchoalveolar epithelial responses to beta-agonists in a BALB/c mouse model by inducing heterologous keratinocyte cytokine (KC)/CXCR2-mediated desensitization of epithelial beta(2)-adrenergic receptors. The aim of the current study was to determine whether RSV also induces airway insensitivity to beta-agonists. Total lung resistance (R) was measured in anesthetized female BALB/c mice undergoing mechanical ventilation on a flexiVent computer-controlled piston ventilator. Data were analyzed using the single-compartment model. Infection with RSV A2 did not induce airway hyperresponsiveness to increasing doses of the nebulized cholinergic agonist methacholine (MCh) at any time point after RSV infection. Prenebulization with the beta-agonist terbutaline (100 muM) significantly attenuated bronchoconstrictive responses to 20 and 50 mg/ml MCh in uninfected mice and in mice infected with RSV 4-8 days postinfection (d.p.i.). However, in mice infected with replication-competent, but not UV-inactivated, RSV for 2 days, significant terbutaline insensitivity was found. Terbutaline insensitivity at 2 d.p.i. could be reversed by systemic preinfection treatment with neutralizing anti-CXCR2 antibodies, which reduced bronchoalveolar lavage (BAL) neutrophil counts but did not alter viral replication, BAL KC levels, or lung edema. Terbutaline insensitivity was also reversed by postinfection nebulization with neutralizing anti-KC or anti-CXCR2 antibodies and could be replicated in normal, uninfected mice by nebulization with recombinant KC. These data suggest that KC/CXCR2-mediated airway insensitivity to beta-agonists may underlie the modest utility of these drugs as bronchodilators in therapy for acute RSV bronchiolitis.

The effects of interleukin-8 on airway smooth muscle contraction in cystic fibrosis

BACKGROUND

Many cystic fibrosis (CF) patients display airway hyperresponsiveness and have symptoms of asthma such as cough, wheezing and reversible airway obstruction. Chronic airway bacterial colonization, associated with neutrophilic inflammation and high levels of interleukin-8 (IL-8) is also a common occurrence in these patients. The aim of this work was to determine the responsiveness of airway smooth muscle to IL-8 in CF patients compared to non-CF individuals.

METHODS

Experiments were conducted on cultured ASM cells harvested from subjects with and without CF (control subjects). Cells from the 2nd to 5th passage were studied. Expression of the IL-8 receptors CXCR1 and CXCR2 was assessed by flow cytometry. The cell response to IL-8 was determined by measuring intracellular calcium concentration ([Ca2+](i)), cell contraction, migration and proliferation.

RESULTS

The IL-8 receptors CXCR1 and CXCR2 were expressed in both non-CF and CF ASM cells to a comparable extent. IL-8 (100 nM) induced a peak Ca2+ release that was higher in control than in CF cells: 228 +/- 7 versus 198 +/- 10 nM (p < 0.05). IL-8 induced contraction was greater in CF cells compared to control. Furthermore, IL-8 exposure resulted in greater phosphorylation of myosin light chain (MLC20) in CF than in control cells. In addition, MLC20 expression was also increased in CF cells. Exposure to IL-8 induced migration and proliferation of both groups of ASM cells but was not different between CF and non-CF cells.

CONCLUSION

ASM cells of CF patients are more contractile to IL-8 than non-CF ASM cells. This enhanced contractility may be due to an increase in the amount of contractile protein MLC20. Higher expression of MLC20 by CF cells could contribute to airway hyperresponsiveness to IL-8 in CF patients.

CXCR2 antagonists for the treatment of pulmonary disease

Chemokines have long been implicated in the initiation and amplification of inflammatory responses by virtue of their role in leukocyte chemotaxis. The expression of one of the receptors for these chemokines, CXCR2, on a variety of cell types and tissues suggests that these receptors may have a broad functional role under both constitutive conditions and in the pathophysiology of a number of acute and chronic diseases. With the development of several pharmacological, immunological and genetic tools to study CXCR2 function, an important role for this CXC chemokine receptor subtype has been identified in chronic obstructive pulmonary disease (COPD), asthma and fibrotic pulmonary disorders. Interference with CXCR2 receptor function has demonstrated different effects in the lungs including inhibition of pulmonary damage induced by neutrophils (PMNs), antigen or irritant-induced goblet cell hyperplasia and angiogenesis/collagen deposition caused by lung injury. Many of these features are common to inflammatory and fibrotic disorders of the lung. Clinical trials evaluating small molecule CXCR2 antagonists in COPD, asthma and cystic fibrosis are currently underway. These studies hold considerable promise for identifying novel and efficacious treatments of pulmonary disorders.

Interleukin-8: novel roles in human airway smooth muscle cell contraction and migration

In patients with cystic fibrosis (CF) and asthma, elevated levels of interleukin-8 (IL-8) are found in the airways. IL-8 is a CXC chemokine that is a chemoattractant for neutrophils through CXCR1 and CXCR2 G protein-coupled receptors. We hypothesized that IL-8 acts directly on airway smooth muscle cells (ASMC) in a way that may contribute to the enhanced airway responsiveness and airway remodeling observed in CF and asthma. The aim of this study was to determine whether human ASMC (HASMC) express functional IL-8 receptors (CXCR1 and CXCR2) linked to cell contraction and migration. Experiments were conducted on cells harvested from human lung specimens. Real-time PCR and fluorescence-activated cell sorting analysis showed that HASMC expressed mRNA and protein for both CXCR1 and CXCR2. Intracellular Ca2+ concentration ([Ca2+]i) increased from 115 to 170 nM in response to IL-8 (100 nM) and decreased after inhibition of phospholipase C (PLC) with U-73122. On blocking the receptors with specific neutralizing antibodies, changes in [Ca2+]i were abrogated. IL-8 also contracted the HASMC, decreasing the length of cells by 15%, and induced a 2.5-fold increase in migration. These results indicate that HASMC constitutively express functional CXCR1 and CXCR2 that mediate IL-8-triggered Ca2+ release, contraction, and migration. These data suggest a potential role for IL-8 in causing abnormal airway structure and function in asthma and CF.

Hepatitis C virus and the lung: implications for therapy

Hepatitis C virus (HCV) infection is a chronic blood-borne disease that affects > 4,000,000 individuals in the United States. The majority of individuals with HVC infection acquire a chronic hepatitis that predisposes them to the complications of cirrhosis and hepatoma. Chronic HCV infection is, however, associated with multiple extrahepatic manifestations as well, including recently recognized effects on the lung. These include primary effects on lung function, as well as secondary effects in the settings of progressive liver disease and drug treatment for HCV. In this article, we discuss the emerging clinical data that support a role for HCV infection in lung disease, describe the multiple pulmonary manifestations of this viral infection, and outline the therapies available for specific pulmonary complications of chronic HCV infection.

Induction of p38- and gC1qR-dependent IL-8 expression in pulmonary fibroblasts by soluble hepatitis C core protein

Background

Recent studies suggest that HCV infection is associated with progressive declines in pulmonary function in patients with underlying pulmonary diseases such as asthma and chronic obstructive pulmonary disease. Few molecular studies have addressed the inflammatory aspects of HCV-associated pulmonary disease. Because IL-8 plays a fundamental role in reactive airway diseases, we examined IL-8 signaling in normal human lung fibroblasts (NHLF) in response to the HCV nucleocapsid core protein, a viral antigen shown to modulate intracellular signaling pathways involved in cell proliferation, apoptosis and inflammation.

Methods

NHLF were treated with HCV core protein and assayed for IL-8 expression, phosphorylation of the p38 MAPK pathway, and for the effect of p38 inhibition.

Results

Our studies demonstrate that soluble HCV core protein induces significant increases in both IL-8 mRNA and protein expression in a dose- and time-dependent manner. Treatment with HCV core led to phosphorylation of p38 MAPK, and expression of IL-8 was dependent upon p38 activation. Using TNFα as a co-stimulant, we observed additive increases in IL-8 expression. HCV core-mediated expression of IL-8 was inhibited by blocking gC1qR, a known receptor for soluble HCV core linked to MAPK signaling.

Conclusion

These studies suggest that HCV core protein can lead to enhanced p38- and gC1qR-dependent IL-8 expression. Such a pro-inflammatory role may contribute to the progressive deterioration in pulmonary function recently recognized in individuals chronically infected with HCV.

The role of neutrophils in LPS-induced changes in pulmonary function in conscious rats

We have previously reported on a model of lipopolysaccharide (LPS)-induced pulmonary inflammation in rats, where LPS-challenged animals develop a significant pulmonary neutrophilia and mucus hypersecretion. In the current studies, we utilized whole body plethysmography and computer assisted data acquisition to examine changes in pulmonary parameters, e.g. frequency (f) tidal volume and Penh as a measure of bronchoconstriction, due to LPS-challenge in conscious rats. Compared to saline challenge, LPS-challenged rats displayed a significant increase in (f) which began within 30 min, peaked by 2 h and remained elevated up to 24 h. Mirroring this increase in (f) was a decrease in the observed tidal volume of LPS-challenged rats. Additionally, compared to saline challenge, LPS-challenge provoked a significant and spontaneous bronchoconstriction, as measured by Penh, 2 h after challenge. In order to further understand these observed LPS-induced pulmonary changes, we utilized two classes of pulmonary obstructive disease standards, namely, bronchodilators and anti-inflammatory agents, and examined their ability to affect the spontaneous bronchoconstriction and the increase in (f) seen at two discrete time points, i.e. 2 and 24 h after LPS-challenge. While ineffective on either the 2 h increase in (f) or the LPS-induced inflammation, animals pretreated with salbutamol (10 mg/kg, p.o.) were protected from the increase in (f) seen at the 24 h time point after LPS-challenge. In contrast, when animals were pretreated with theophylline (10 mg/kg, p.o.) no effect on the LPS-induced pulmonary inflammation or increase in (f) was noted. Meanwhile, in animals pretreated with either betamethasone (3 mg/kg, p.o.) or SB207499 (10 mg/kg, p.o.), a PDE4 inhibitor, doses previously shown to block the LPS-induced neutrophilic inflammation, the persistent increase in (f) seen at 24 h was attenuated, but neither compound was able to attenuate either the increase in (f) or the spontaneous bronchoconstriction seen at 2 h. In summary, the intra-tracheal LPS-challenge of rats results in pulmonary inflammation and dysfunction, which is similar to that seen in COPD patients. We conclude that the early increase in (f) and bronchoconstriction are not dependent upon airway inflammation, but airway inflammation most likely contributes to the persistent increase in (f) seen at 24 h.

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.