Enhanced PMN response in chronic bronchitis and community-acquired pneumonia

Telmisartan ameliorates LPS-induced pneumonia in rats through regulation of the PPARγ/NF-κB pathway

Pneumonia is a common disorder of the respiratory system associated with inflammation. Telmisartan (TEL) has been reported to treat inflammatory-related diseases. The current study is aimed to make investigations for the possible role and action mechanism of TEL on lipopolysaccharide (LPS)-induced pneumonia rats. Forty male Sprague Dawley (SD) rats aged 8 weeks were assigned into four groups ad libitum: a control group received saline only, an experimental group received LPS, a group received TEL (5 mg/kg), followed by LPS treatment, and a group received TEL (10 mg/kg), followed by LPS treatment. LPS (2 mg/kg) and equal saline were administered intratracheally. TEL was orally administrated 5 days before LPS. After LPS treatment for 24 h, bronchoalveolar lavage fluid (BALF) and serum were collected for the analysis of cell counts and/or cytokines. Lung tissues were used to perform histological examination, assess oxidative stress levels, and determine the levels of PPARγ/NF-κB pathway-related proteins. Rats received LPS treatment exhibited high levels of lung wet/dry ratio, ALP, LDH, BALF polymorphonuclear leukocytes count, inflammatory cytokines, and oxidative stress. Meanwhile, LPS also resulted in severe interstitial edema and inflammatory cells infiltration. Interestingly, TEL by oral administration remarkably ameliorated the adverse effects on pneumonia rats caused by LPS. In addition, western blotting further revealed that TEL could activate PPARγ and repress NF-κB (p65). TEL is protective against pneumonia through inhibition of the inflammation and oxidative stress via the PPARγ/NF-κB pathway. This article is protected by copyright. All rights reserved.

Neutrophil-Derived IL-17 Promotes Ventilator-Induced Lung Injury via p38 MAPK/MCP-1 Pathway Activation

Ventilator-induced lung injury (VILI) is one of the most common complications of mechanical ventilation and can severely affect health. VILI appears to involve excessive inflammatory responses, but its pathogenesis has not yet been clarified. Since interleukin-17 (IL-17) plays a critical role in the immune system and the development of infectious and inflammatory diseases, we investigated here whether it plays a role in VILI. In a mouse model of VILI, mechanical ventilation with high tidal volume promoted the accumulation of lung neutrophils, leading to increased IL-17 levels in the lung, which in turn upregulated macrophage chemoattractant protein-1 via p38 mitogen-activated protein kinase. Depletion of neutrophils decreases the production IL-17 in mice and inhibition of IL-17 significantly reduced HTV-induced lung injury and inflammatory response. These results were confirmed in vitro using RAW264.7 macrophage cultures. Our results suggest that IL-17 plays a pro-inflammatory role in VILI and could serve as a new target for its treatment.

Pinitol attenuates LPS-induced pneumonia in experimental animals: Possible role via inhibition of the TLR-4 and NF-κB/IκBα signaling cascade pathway

Pneumonia is a chronic disorder of the respiratory system associated with worsening quality of life and a significant economic burden. Pinitol, a plant cyclic polyol, has been documented for immune-inflammatory potential. The aim of present investigation was to evaluate the potential and possible mechanism of action of pinitol against lipopolysaccharide (LPS)-induced pneumonia in the experimental animal model. Pneumonia was induced in Sprague-Dawley rats by intratracheal administration of LPS (2 mg/kg). Animals were treated with either vehicle or dexamethasone or pinitol (5 or 10 or 20 mg/kg). Potential of pinitol against LPS-induced pulmonary insult was assessed based on behavioral, biochemical, molecular, and ultrastructural studies. Intratracheal instillation of LPS induced significant (P < .05) inflammatory infiltration in bronchoalveolar lavage fluid (BALF) and lung tissue reflected by elevated pleural effusion volume, lung edema, BALF polymorphonuclear leukocytes count and lung myeloperoxidase levels, which was attenuated by pinitol (10 and 20 mg/kg) administration. Pinitol also markedly (P < .05) inhibited LPS-induced alterations in electrocardiographic, hemodynamic changes, right ventricular, and lung function tests. The LPS-induced downregulated nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase-1 (HO-1), whereas upregulated transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), and inducible nitric oxide synthase (iNOs) lung messenger RNA expressions were significantly (P < .05) inhibited by pinitol. Western blot analysis suggested pinitol markedly (P < .05) decreased nuclear factor-κB (NF-κB), inhibitor of nuclear factor κB (IkBα), toll-like receptor 4 (TLR-4), and cyclooxygenase-II (COX-II) protein expressions in the lung. These findings were further supported by histological and ultrastructural analyses of lung tissue that show pinitol significantly (P < .05) ameliorates LPS-induced aberrations in lung tissue. In conclusion, pinitol attenuated LPS-induced pneumonia via inhibition of TLR-4 to downregulate the NF-κB/IκBα signaling cascade and thus ameliorated the production of proinflammatory cytokines (TNF-α, ILs, NLRP3, and TGF-β), inflammatory mediators (COX-II and iNOs) and elevated oxidative stress (Nrf-2 and HO-1).

Effect of Ambroxol and Beclomethasone on Lipopolysaccharide-Induced Nitrosative Stress in Bronchial Epithelial Cells

BACKGROUND

Nitrosative stress is involved in different airway diseases. Lipopolysaccharide (LPS) induces neutrophil-related cytokine release and nitrosative stress in human bronchial epithelial (BEAS-2B) cells alone or with human polymorphonuclear neutrophils (PMNs). Ambroxol protects against oxidative stress, and beclomethasone dipropionate is an anti-inflammatory drug.

OBJECTIVES

We evaluated the ability of ambroxol and/or beclomethasone dipropionate to inhibit LPS-induced expression/release of RANTES, IL-8, inducible NO synthase (iNOS), myeloperoxidase (MPO) and 3-nitrotyrosine (3-NT: nitrosative stress biomarker) in BEAS-2B ± PMNs stimulated with LPS (1 μg/ml).

METHODS

The effect of ambroxol and/or beclomethasone dipropionate on IL-8, RANTES and iNOS levels was assessed by Western blot analysis; IL-8, MPO and 3-NT levels were measured by ELISA. Cell viability was assessed by the trypan blue exclusion test.

RESULTS

In BEAS-2B alone, LPS (at 12 h) increased RANTES/iNOS expression and IL-8 levels (p < 0.001). Ambroxol suppressed LPS-induced RANTES expression and IL-8 release (p < 0.001), whilst inhibiting iNOS expression (p < 0.05). Beclomethasone dipropionate had no effect on RANTES but halved iNOS expression and IL-8 release. Coculture of BEAS-2B with PMNs stimulated IL-8, MPO and 3-NT production (p < 0.001), potentiated by LPS (p < 0.001). Ambroxol and beclomethasone dipropionate inhibited LPS-stimulated IL-8, MPO and 3-NT release (p < 0.05). Ambroxol/beclomethasone dipropionate combination potentiated the inhibition of IL-8 and 3-NT production in BEAS-2B with PMNs (p < 0.05 and p < 0.01, respectively). Ambroxol and/or beclomethasone dipropionate inhibited nitrosative stress and the release of neutrophilic inflammatory products in vitro.

CONCLUSION

The additive effect of ambroxol and beclomethasone dipropionate on IL-8 and 3-NT inhibition suggests new therapeutic options in the treatment of neutrophil-related respiratory diseases such as chronic obstructive pulmonary disease and respiratory infections.

Decreased apoptosis of pulmonary PMN in COPD patients with community-acquired pneumonia

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) predisposes for the acquisition of community-acquired pneumonia (CAP).

OBJECTIVE/METHODS

To assess clinically and scientifically suggested disorders in innate immune response during acute phrase and resolution CAP (T2), we evaluated peripheral and pulmonary polymorphnuclear neutrophils (PMN), recovered by induced sputum, from CAP patients with and without COPD with regard to cell activation, interleukin-8 (CXCL-8) and CXCL-8 receptor expression, and apoptosis rate.

RESULTS

At T1, COPD patients displayed significantly lower pulmonary PMN apoptosis rates, while total cell count, the amount of macrophages, and vital and necrotic neutrophils in sputum samples were similar between study groups. At T2, there were no differences between study groups or between pulmonary and peripheral compartment. While under systemic steroid treatment apoptosis rates of peripheral and pulmonary PMN at T1 were slightly decreased, there were no significant differences in intrapulmonary CXCL-8 levels. Regarding cell activation, no significant differences could be seen, neither in comparing study groups nor in pulmonary to peripheral PMN.

CONCLUSION

Elucidating the pathology of suspected disorder in innate immune response, we found decreased apoptosis rates of pulmonary neutrophils in COPD at the peak of CAP indicating an increased inflammatory response, which is independent from anti-apoptotic cytokines such as CXCL-8, severity of disease and isolation of bacteria from sputum cultures.

Cytokine networks in the infected lung

The generation of an innate immune response is essential for rapid clearance of microbes from the respiratory tract, whereas acquired immunity is required for the generation of cellular immunity necessary for the killing of certain intracellular pathogens and the development of immunological memory. Cytokines play an integral role in host defense by serving as leukocyte chemoattractants, leukocyte-activating factors or afferent signals in the induction or regulation of other effector molecules. This review assesses the contribution of cytokine networks to the generation of antimicrobial host defenses in the lung, with an emphasis on cytokines/cytokine networks that are instrumental in innate antibacterial responses, including mucosal immunity, and also introduces networks that instruct the development of adaptive immunity.

Granulocyte apoptosis in the pathogenesis and resolution of lung disease

Apoptosis, programmed cell death, of neutrophil and eosinophil granulocytes is a potential control point in the physiological resolution of innate immune responses. There is also increasing evidence that cellular processes of apoptosis can be dysregulated by pathogens as a mechanism of immune evasion and that delayed apoptosis, resulting in prolonged inflammatory cell survival, is important in persistence of tissue inflammation. The identification of cell-type specific pathways to apoptosis may allow the design of novel anti-inflammatory therapies or agents to augment the innate immune responses to infection. This review will explore the physiological roles of granulocyte apoptosis and their importance in infectious and non-infectious lung disease.

Modulation of neutrophil apoptosis in plasma of patients after orthognathic surgery

BACKGROUND

Human neutrophils undergo rapid apoptosis during in vitro culture. The aim of this study was to investigate the role of interleukin-8 (IL-8) on neutrophil apoptosis in surgery-induced inflammation.

MATERIALS AND METHODS

Blood samples were drawn from 21 patients with mandibular prognathism 2 days before, and 1 and 5 days after orthognathic surgery. The IL-8 levels in the separated plasma were measured using an ELISA kit. The expression of two receptors for IL-8, CXCR1, and CXCR2, and their role in neutrophil apoptosis was evaluated using a flow cytometer.

RESULTS

The IL-8 levels in the plasma were correlated with acute inflammatory markers, such as peripheral blood neutrophil counts and C-reactive protein levels. Both IL-8 receptors were markedly raised in patient-derived neutrophils 1 day post-operatively. Recombinant IL-8 (0-100 ng/ml) suppressed apoptosis in fresh-isolated neutrophils from healthy donors dose-dependently. Neutrophil apoptosis 1 day post-operatively was slightly accelerated in the presence of fetal bovine serum compared to the value 2 days pre-operatively and 5 days post-operatively. In contrast, in the presence of autogenous plasma, neutrophil apoptosis was significantly suppressed 1 day post-operatively compared to the value 2 days pre-operatively and 5 days post-operatively. Moreover, the anti-apoptotic effect of plasma on neutrophil apoptosis was partially decreased by the addition of anti-IL-8 neutralizing antibody.

CONCLUSIONS

These results suggest that circulating neutrophils are susceptible to augmentation by IL-8 through the reinforcement of IL-8 receptors in acute inflammatory conditions. Furthermore, IL-8 may, in part, contribute to the regulation of neutrophil survival during the inflammatory response.

Apoptosis of peripheral blood neutrophils in COPD exacerbation does not correlate with serum cytokines

The study investigated the relationship between apoptosis of peripheral blood neutrophils during exacerbation of chronic obstructive pulmonary disease (COPD) and the inflammatory response that characterises this condition. Twenty-six hospitalised patients with COPD exacerbation and 13 controls were included. Three sequential blood and sputum samples were obtained from patients at admission, after 3 days and at discharge. Blood apoptotic neutrophils were measured by flow-cytometry and light microscopy. Serum and sputum levels of IL-6, IL-8 and TNF-alpha were determined by an immunoassay technique. We found a significantly reduced percentage of apoptotic neutrophils at the onset of COPD exacerbation which increased over time (1.1+/-0.4% at admission vs. 2.4+/-0.4% at discharge, P<0.0001). Patients presented no changes in serum cytokines neither during exacerbation nor in comparison to controls. In contrast, sputum levels of cytokines were significantly increased compared to serum levels. There was no significant correlation between the apoptotic neutrophils and the cytokine concentrations in serum or sputum. None of the clinical parameters, such as smoking, microbial infection, corticosteroids or hypoxemia showed a correlation with neutrophil apoptosis. No relationship could be found between the reduced percentage of apoptotic neutrophils in blood and serum concentration of IL-6, IL-8 and TNF-alpha or other clinical parameters in patients with COPD exacerbation.