Interleukin-10 inhibits elevated chemokine interleukin-8 and regulated on activation normal T cell expressed and secreted production in cystic fibrosis bronchial epithelial cells by targeting the I(k)B kinase alpha/beta complex

IL-8 (CXCL8) Correlations with Psychoneuroimmunological Processes and Neuropsychiatric Conditions

Interleukin-8 (IL-8/CXCL8), an essential CXC chemokine, significantly influences psychoneuroimmunological processes and affects neurological and psychiatric health. It exerts a profound effect on immune cell activation and brain function, suggesting potential roles in both neuroprotection and neuroinflammation. IL-8 production is stimulated by several factors, including reactive oxygen species (ROS) known to promote inflammation and disease progression. Additionally, CXCL8 gene polymorphisms can alter IL-8 production, leading to potential differences in disease susceptibility, progression, and severity across populations. IL-8 levels vary among neuropsychiatric conditions, demonstrating sensitivity to psychosocial stressors and disease severity. IL-8 can be detected in blood circulation, cerebrospinal fluid (CSF), and urine, making it a promising candidate for a broad-spectrum biomarker. This review highlights the need for further research on the diverse effects of IL-8 and the associated implications for personalized medicine. A thorough understanding of its complex role could lead to the development of more effective and personalized treatment strategies for neuropsychiatric conditions.

Psychosocial and behavioral factors affecting inflammation among pregnant African American women

African American women are reported to have greater inflammation compared with women from other racial groups. Higher inflammation during pregnancy has been associated with increased risk of adverse perinatal outcomes. We hypothesized that maternal inflammation is related to depressive symptoms and social and behavioral risk factors among pregnant African American women. Pregnant African American women (n ​= ​187) were recruited at prenatal clinics in the Midwest. Women completed questionnaires and had blood drawn at a prenatal visit. Plasma levels of cytokines (interferon gamma [IFN]-γ, interleukin [IL]-6, IL-8, IL-10, tumor necrosis factor [TNF]-α) and C-reactive protein (CRP) were measured by multiplex assays. Women had a mean age of 26.58±5.42 years and a mean gestational age at data collection of 16.35±5.95 weeks. Twenty-six percent of women had Center for Epidemiological Studies-Depression (CES-D) scores ≥23 (scores that have been correlated with clinical diagnosis of depression), 15.5% smoked cigarettes, 16.6% used marijuana, and 5.3% reported experiencing intimate partner violence (IPV). Higher CES-D scores were correlated with higher plasma CRP levels (r ​= ​0.16, p ​= ​0.046). Women who reported any experiences of IPV during pregnancy had higher levels of IL-8 (p ​= ​0.018) and lower levels of IFN-γ (p ​= ​0.012) compared with women who did not report IPV. Cigarette smoking during pregnancy was associated with lower levels of the anti-inflammatory cytokine IL-10 (p ​= ​0.003). These findings suggest that depressive symptoms, IPV, and cigarette smoking during pregnancy relate to select inflammatory markers in pregnant African American women. The relationships of inflammation with these factors should be further investigated to better understand the mechanisms which influence maternal and fetal health outcomes.

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Depressive symptoms are related to higher levels of CRP in pregnant African American Women.

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Intimate partner violence in pregnancy is related to higher interleukin 8 levels.

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Smoking during pregnancy is associated with lower interleukin 10 levels.

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Inflammation is related to depressive symptoms, intimate partner violence and smoking in pregnant African American women.

Genome-wide identification, immune response profile and functional characterization of IL-10 from spotted knifejaw (Oplegnathus punctatus) during host defense against bacterial and viral infection

Interleukin 10 (IL-10), a pleiotropic cytokine, plays an essential role in multiple immunity responses. In the current study, the sequences of IL-10 family were identified from spotted knifejaw (Oplegnathus punctatus) whole genome, and O. punctatus IL-10 (OpIL-10) was cloned and characterized. OpIL-10 encodes 187 amino acids with a typical IL-10 family signature motif and predicted α-helices. It shared high identities with Notolabrus celidotus IL-10 and Epinephelus Lanceolatus IL-10. OpIL-10 was widely detected in healthy tissues, with the abundant expression in liver and skin. It was significantly up-regulated in the six immune-related tissues (liver, spleen, kidney, intestine, gill and skin) after infection against Vibrio harveyi and spotted knifejaw iridovirus (SKIV). Dual-luciferase analysis showed that OpIL-10 overexpression could suppress the activity of NF-κB. Meanwhile, OpIL-10 knockdown caused the down-regulation of five immune-related genes in JAK2/STAT3 signaling pathway and NF-κB signaling pathway, including IL-10R2, TYK2, STAT3, NOD2, and IκB. In addition, LPS and poly I:C stimulated expression of pro-inflammatory cytokines, including IL-6, IL-1β, IL-8, and IL-12, were lower with recombinant OpIL-10 (rOp IL-10) than the control group, indicating the anti-inflammatory roles of rOpIL-10. Taken together, these results indicated OpIL-10 as a negative regulator in the inflammatory responses of spotted knifejaw against bacterial and viral infection, which would help us better understand the role of IL-10 in teleost immunity.

Olodaterol exerts anti-inflammatory effects on COPD airway epithelial cells

BACKGROUND

Airway inflammation is a key feature of chronic obstructive pulmonary disease (COPD) and inhaled corticosteroids (ICS) remain the main treatment for airway inflammation. Studies have noted the increased efficacy of ICS and long-acting beta 2 agonist (LABA) combination therapy in controlling exacerbations and improving airway inflammation than either monotherapy. Further studies have suggested that LABAs may have inherent anti-inflammatory potential, but this has not been well-studied.

OBJECTIVE

We hypothesize that the LABA olodaterol can inhibit airway inflammation resulting from exposure to respiratory syncytial virus (RSV) via its binding receptor, the β2-adrenergic receptor.

METHODS

Human bronchial epithelial brushing from patients with and without COPD were cultured into air-liquid interface (ALI) cultures and treated with or without olodaterol and RSV infection to examine the effect on markers of inflammation including interleukin-8 (IL-8) and mucus secretion. The cell line NCI-H292 was utilized for gene silencing of the β2-adrenergic receptor via siRNA as well as receptor blocking via ICI 118,551 and butaxamine.

RESULTS

At baseline, COPD-ALIs produced greater amounts of IL-8 than control ALIs. Olodaterol reduced RSV-mediated IL-8 secretion in both COPD and control ALIs and also significantly reduced Muc5AC staining in COPD-ALIs infected with RSV. A non-significant reduction was seen in control ALIs. Gene silencing of the β2-adrenergic receptor in NCI-H292 negated the ability of olodaterol to inhibit IL-8 secretion from both RSV infection and lipopolysaccharide stimulus, as did blocking of the receptor with ICI 118,551 and butaxamine.

CONCLUSIONS

Olodaterol exhibits inherent anti-inflammatory properties on the airway epithelium, in addition to its bronchodilation properties, that is mediated through the β2-adrenergic receptor and independent of ICS usage.

Novel Anti-Inflammatory Approaches for Cystic Fibrosis Lung Disease: Identification of Molecular Targets and Design of Innovative Therapies

Cystic fibrosis (CF) is the most common genetic disorder among Caucasians, estimated to affect more than 70,000 people in the world. Severe and persistent bronchial inflammation and chronic bacterial infection, along with airway mucus obstruction, are hallmarks of CF lung disease and participate in its progression. Anti-inflammatory therapies are, therefore, of particular interest for CF lung disease. Furthermore, a better understanding of the molecular mechanisms involved in airway infection and inflammation in CF has led to the development of new therapeutic approaches that are currently under evaluation by clinical trials. These new strategies dedicated to CF inflammation are designed to treat different dysregulated aspects such as oxidative stress, cytokine secretion, and the targeting of dysregulated pathways. In this review, we summarize the current understanding of the cellular and molecular mechanisms that contribute to abnormal lung inflammation in CF, as well as the new anti-inflammatory strategies proposed to CF patients by exploring novel molecular targets and novel drug approaches.

The isoprenoid end product N6-isopentenyladenosine reduces inflammatory response through the inhibition of the NFκB and STAT3 pathways in cystic fibrosis cells

Objective

N6-isopentenyladenosine (iPA) is an intermediate of the mevalonate pathway that exhibits various anti-cancer effects. However, studies on its anti-inflammatory activity are scarce and underlying molecular mechanisms are unknown. Therefore, we aimed to investigate the ability of iPA to exert anti-inflammatory effects in the human cystic fibrosis (CF) cell model of exacerbated inflammation.

Materials and methods

TNFα-stimulated CF cells CuFi-1 and its normal counterpart NuLi-1 were pre-treated with increasing concentrations of iPA and cell viability and proliferation were assessed by MTT and BrdU assays. The effect of iPA on IL-8 and RANTES secretion was determined by ELISA, and the activation and expression of signaling molecules and selenoproteins were studied by Western blot. To assess the direct effect of iPA on NFκB activity, luciferase assay was performed on TNFα-stimulated HEK293/T cells transfected with a NFκB reporter plasmid.

Results

We demonstrated for the first time that iPA prevents IL-8 and RANTES release in TNFα-stimulated CF cells and this effect is mediated by increasing the expression of the direct NFκB inhibitor IκBα and decreasing the levels of STAT3. Consistent with this, we showed that iPA inhibited TNFα-mediated NFκB activation in HEK/293T cells. Finally, we also found that iPA improved the levels of glutathione peroxidase 1 and thioredoxin reductase 1 only in CF cells suggesting its ability to maintain sufficient expression of these anti-oxidant selenoproteins.

Conclusions

Our findings indicate that iPA can exert anti-inflammatory activity especially in the cases of excessive inflammatory response as in CF.

Dysregulated Chemokine Signaling in Cystic Fibrosis Lung Disease: A Potential Therapeutic Target

CF lung disease is characterized by a chronic and non-resolving activation of the innate immune system with excessive release of chemokines/cytokines including IL-8 and persistent infiltration of immune cells, mainly neutrophils, into the airways. Chronic infection and impaired immune response eventually lead to pulmonary damage characterized by bronchiectasis, emphysema, and lung fibrosis. As a complete knowledge of the pathways responsible for the exaggerated inflammatory response in CF lung disease is lacking, understanding these pathways could reveal new therapeutic targets, and lead to novel treatments. Therefore, there is a strong rationale for the identification of mechanisms and pathways underlying the exaggerated inflammatory response in CF lung disease. This article reviews the role of inflammation in the pathogenesis of CF lung disease, with a focus on the dysregulated signaling involved in the overexpression of chemokine IL-8 and excessive recruitment of neutrophils in CF airways. The findings suggest that targeting the exaggerated IL-8/IL-8 receptor (mainly CXCR2) signaling pathway in immune cells (especially neutrophils) may represent a potential therapeutic strategy for CF lung disease.

Curcumin attenuates lipopolysaccharide-induced renal inflammation

Renal inflammation is the main pathological change in many acute and chronic kidney diseases. Curcumin, a yellow pigment present in the rhizome of turmeric (Curcuma longa L. Zingiberaceae), was found to be a potential anti-inflammatory agent. The present study aimed to investigate the effects of curcumin on the inflammation of mice kidney and cultured renal tubular epithelial cells (HK-2 cells) induced by lipopolysaccharide (LPS) and to explore the mechanism. Curcumin was injected intraperitoneally before LPS administration. Renal inflammation was assessed by evaluating monocyte chemoattractant protein-1 (MCP-1) expression and macrophage infiltration in renal tissue using immunohistochemical methods, and also by measuring renal MCP-1 mRNA level using Real-Time polymerase chain reaction (PCR). HK-2 cells were cultured to investigate the in vitro effect of curcumin against LPS-induced renal inflammation. The expression of MCP-1 and interleukin-8 (IL-8) mRNA was measured by Real-Time PCR. The expression of MCP-1 and IL-8 protein in supernatant was detected by enzyme-linked immunosorbent assay (ELISA). The activity of nuclear factor (NF)-κB was detected by electrophoretic mobility shift assay (EMSA). The results demonstrated that curcumin could inhibit LPS-induced renal MCP-1 mRNA expression. Curcumin also significantly inhibited the expression of MCP-1 and IL-2 mRNA in HK-2 cells, and partially inhibited the secretion of MCP-1 and IL-8. Furthermore, curcumin was found to inhibit the DNA-binding activity of NF-κB. The present study demonstrated that curcumin has a protective effect on LPS-induced experimental renal inflammation, and this effect might be attributed to its inhibitory effects on MCP-1 mRNA expression and DNA-binding activity of NF-κB. Hence, curcumin might be potentially useful in some kidney diseases by preventing renal inflammation.

Reduced surface toll-like receptor-4 expression and absent interferon-γ-inducible protein-10 induction in cystic fibrosis airway cells

ABSTRACT As part of the innate and adaptive immune system, airway epithelial cells secrete proinflammatory cytokines after activation of Toll-like receptors (TLRs) by pathogens. Nevertheless, cystic fibrosis (CF) airways are chronically infected with Pseudomonas aeruginosa, suggesting a modified immune response in CF. The authors have shown that in CF bronchial epithelial cells, a reduced surface expression of TLR-4 causes a diminished interleukin (IL)-8 and IL-6 response upon lipopolysaccharide (LPS) stimulation. However, there is no information regarding activation of the MyD88 (myeloid differentiation primary response gene 88)-independent TLR-4 signaling pathway by LPS, which results in the activation of adaptive immune responses by secretion of the T cell-recruiting chemokine interferon-γ-inducible protein (IP)-10. Therefore, the authors investigated the induction of IP-10 in CF bronchial epithelial cell line CFBE41o- and its CFTR-corrected isotype under well-differentiating conditions. TLR-4 surface expression was significantly reduced in CFBE41o- by a factor of 2, compared to the CFTR-corrected cells. In CFTR-corrected cells, stimulation with LPS increased IP-10 secretion. Incubating cells with siRNA directed against TLR-4 inhibited the LPS stimulated increase of IP-10 in CFTR-corrected cells. The reduced TLR-4 surface expression in CF cells causes the loss of induction of IP-10 by LPS. This could compromise adaptive immune responses in CF due to a reduced T-cell recruitment.

Interleukin-10-mediated heme oxygenase 1-induced underlying mechanism in inflammatory down-regulation by norfloxacin in cirrhosis

Patients with cirrhosis receiving norfloxacin show a restored inflammatory balance that likely prevents clinical complications derived from an excessive proinflammatory response to bacterial product challenges. This study sought to investigate associated inflammatory control mechanisms established in patients with cirrhosis receiving norfloxacin. A total of 62 patients with cirrhosis and ascites in different clinical conditions were considered. Blood samples were collected and intracellular and serum norfloxacin were measured. Inflammatory mediators were evaluated at messenger RNA and protein levels. Neutrophils from all patients were cultured with lipopolysaccharide (LPS) and anti-interleukin-10 (anti-IL-10) monoclonal antibody in different conditions. IL-10 and heme oxygenase-1 (HO-1) were up-regulated in patients receiving norfloxacin and correlated with norfloxacin in a concentration-dependent manner, whereas proinflammatory inducible nitric oxide synthase, cyclooxygenase-2, and nuclear factor-κB behaved inversely. Higher IL-10 levels correlated with lower white blood cell count and higher mean arterial pressure. No correlations were found between IL-10 and disease clinical scores or liver function markers in blood. Neutrophilic in vitro assays showed that the effect of LPS on proinflammatory mediator levels in the presence of norfloxacin was abrogated by significantly increasing IL-10 and HO-1 expression. After stimulation with LPS plus anti-IL-10, proinflammatory mediators were dramatically increased in patients receiving norfloxacin, and increasing intracellular norfloxacin concentrations did not decrease the expression levels of these proinflammatory molecules. Unblocking IL-10 restored proinflammatory mediator and HO-1 expression to previously observed levels in response to LPS stimulation.

CONCLUSION

Although the described association does not necessarily mean causality, an IL-10-mediated HO-1-induced anti-inflammatory mechanism is present in patients with cirrhosis receiving norfloxacin, that is directly associated with cell-modulating events in these patients.

Pathway prediction by bioinformatic analysis of the untranslated regions of the CFTR mRNA

Mining the information contained within the genetic code in untranslated regions has proven difficult because of the ambiguity of microRNA and protein binding sites. This manuscript describes a bioinformatic screen that identifies long sequences with partial identity to the untranslated regions of the cystic fibrosis transmembrane regulator. This screen uncovered a long, evolutionarily conserved motif common to the 3' UTRs of the CFTR and SEC24A transcripts, and shorter, statistically significant motifs unique to either 5' or 3' UTRs. In addition, of the 140 transcripts identified in the screen that encode proteins with known protein interactions, 130 are linked to CFTR through protein interactions. The screen identified genes that are known to be involved in lung fibrosis, the inflammatory response of cystic fibrosis and sensitivity to Pseudomonas aeruginosa infections. The bioinformatic analysis of untranslated regions should prove to be a powerful adjunct to other tools for predicting pathways and relevant interactions.

HCMV IL-10 suppresses cytokine expression in monocytes through inhibition of nuclear factor-kappaB

Modulation of host immune responses is a common strategy for promoting virus persistence and avoiding clearance. Human cytomegalovirus (HCMV) is known to encode numerous immunomodulatory genes, including a homolog of the cytokine human interleukin-10 (hIL-10). While having limited sequence homology to hIL-10, cytomegalovirus IL-10 (cmvIL-10) shares many functional characteristics with the human cytokine and acts as a potent suppressor of the inflammatory immune response. The mechanism by which hIL-10 inhibits inflammatory cytokines involves a transcriptional block via inhibition of nuclear factor-kappaB (NF-kappaB) activity. To determine whether cmvIL-10 employs the same mechanism to inhibit cytokine production, the effect of cmvIL-10 on NF-kappaB signaling in monocytes was investigated. The results demonstrate that cmvIL-10 does inhibit NF-kappaB activation, as evidenced by reduced degradation of the NF-kappaB inhibitor IkappaB-alpha, and decreased transcription of the NF-kappaB-responsive genes tumor necrosis factor-alpha (TNF-alpha) and IL-1beta. These studies confirm that cmvIL-10 mediates cytokine suppression by blocking NF-kappaB transcriptional activity in human monocytes.

NF-kappaB activation by combinations of NEMO SUMOylation and ATM activation stresses in the absence of DNA damage

The inactive transcription factor NF-kappaB is localized in the cytoplasm and rapidly responds to a variety of extracellular factors and intracellular stress conditions to initiate multiple cellular responses. While the knowledge regarding NF-kappaB signaling pathways initiated by extracellular ligands is rapidly expanding, the mechanisms of activation by intracellular stress conditions are not well understood. We recently described a critical role for a small ubiquitin-like modifier (SUMO) modification of NF-kappaB essential modulator (NEMO), the regulatory subunit of the IkappaB kinase, in response to certain genotoxic stress conditions. One important unanswered question is whether the role of this modification is limited to the genotoxic agents or some other signaling pathways also employ SUMOylation of NEMO to regulate NF-kappaB activation. Here, we report that a variety of other stress conditions, including oxidative stress, ethanol exposure, heat shock and electric shock, also induce NEMO SUMOylation, thus demonstrating that DNA damage per se is not necessary for this NEMO modification to occur. Moreover, combinations of certain SUMO stress and ATM (ataxia telangiectasia mutated) activation conditions lead to NF-kappaB activation without inducing DNA damage. Our study helps to conceptualize how individual or a combination of different stress conditions may funnel into this previously unappreciated signal transduction mechanism to regulate the activity of the ubiquitous NF-kappaB transcription factor.

Acute Pseudomonas challenge in cystic fibrosis mice causes prolonged nuclear factor-kappa B activation, cytokine secretion, and persistent lung inflammation

BACKGROUND

Cystic fibrosis (CF) is characterized by an excessive and prolonged inflammatory response to Pseudomonas aeruginosa in the lung. There are high levels of cytokines and chemokines and an exaggerated PMN influx causing significant morbidity and mortality.

OBJECTIVE

To compare the kinetics of the inflammatory response with the kinetics of clearance of acute bacterial challenge in the lungs of CF and wild-type (WT) mice.

METHODS

We challenged CF knockout (KO) and WT mice intratracheally with P aeruginosa in suspension and evaluated bacteria counts, nuclear factor-kappaB (NF-kappaB), and inhibitor of NF-kappaB alpha protein (I-kappaBalpha) in lung tissue, cytokines, and PMN in bronchoalveolar lavage (BAL).

RESULTS

Both groups of mice cleared the infection with the same kinetics. CF-KO mice had more PMN in BAL than WT mice. CF-KO mice had high concentrations of proinflammatory cytokines in BAL on days 2 and 4, whereas cytokines in BAL from WT mice were only slightly elevated. CF-KO mice failed to regenerate I-kappaBalpha once it was degraded, and consequently had prolonged and excessive activation of NF-kappaB for the entire 6-day duration of the study. In contrast, WT mice showed only slight NF-kappaB activation, which plateaued at day 4.

CONCLUSION

These data suggest that NF-kappaB is dysregulated in CF lung infection and could be a good target for therapy. Prolonged responses to initial acute infections may contribute to the eventual establishment of chronic persistent inflammation.

CLINICAL IMPLICATIONS

Dysregulation of the I-kappaB/NF-kappaB pathway in cystic fibrosis leads to prolonged cytokine secretion and persistent inflammation in response to acute challenges and may be important in the development of chronic lung inflammation and infection.

The role of airway epithelium and blood neutrophils in the inflammatory response in cystic fibrosis

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which accounts for the cAMP-modulated chloride conductance of airway epithelial cells. CFTR also regulates other membrane proteins like the negative regulation of the amiloride-sensitive epithelial sodium channel (ENaC). Mutations in the CFTR gene lead to hyperabsorption of sodium chloride and a reduction in the periciliary salt and water content which leads to impaired mucociliary clearance. It seems that a lack of functional CFTR leads to abnormal function of the NF-kappaB pathway in submucosal gland cells, causing an increased production of pro-inflammatory cytokines and the chemokine IL-8, and a pro-inflammatory environment. CFTR is also expressed in neutrophils and several neutrophil functions like cytokine production, migration, phagocytosis and apoptosis seem altered in CF. In this review we describe the role of airway epithelium and blood neutrophils in the viscious circle of inflammation and infection seen in CF.

TLR-induced inflammation in cystic fibrosis and non-cystic fibrosis airway epithelial cells

Cystic fibrosis (CF) is a genetic disease characterized by severe neutrophil-dominated airway inflammation. An important cause of inflammation in CF is Pseudomonas aeruginosa infection. We have evaluated the importance of a number of P. aeruginosa components, namely lipopeptides, LPS, and unmethylated CpG DNA, as proinflammatory stimuli in CF by characterizing the expression and functional activity of their cognate receptors, TLR2/6 or TLR2/1, TLR4, and TLR9, respectively, in a human tracheal epithelial line, CFTE29o(-), which is homozygous for the DeltaF508 CF transmembrane conductance regulator mutation. We also characterized TLR expression and function in a non-CF airway epithelial cell line 16HBE14o(-). Using RT-PCR, we demonstrated TLR mRNA expression. TLR cell surface expression was assessed by fluorescence microscopy. Lipopeptides, LPS, and unmethylated CpG DNA induced IL-8 and IL-6 protein production in a time- and dose-dependent manner. The CF and non-CF cell lines were largely similar in their TLR expression and relative TLR responses. ICAM-1 expression was also up-regulated in CFTE29o(-) cells following stimulation with each agonist. CF bronchoalveolar lavage fluid, which contains LPS, bacterial DNA, and neutrophil elastase (a neutrophil-derived protease that can activate TLR4), up-regulated an NF-kappaB-linked reporter gene and increased IL-8 protein production in CFTE29o(-) cells. This effect was abrogated by expression of dominant-negative versions of MyD88 or Mal, key signal transducers for TLRs, thereby implicating them as potential anti-inflammatory agents for CF.

Role of IL-10 deficiency in excessive nuclear factor-κB activation and lung inflammation in cystic fibrosis transmembrane conductance regulator knockout mice

BACKGROUND

Patients with cystic fibrosis (CF) and CF transmembrane conductance regulator knockout (CF-KO) mice are deficient in pulmonary IL-10 and have excessive inflammatory response to Pseudomonas aeruginosa infection.

OBJECTIVE

We hypothesized that local IL-10 deficiency in the lung was responsible for prolonged and excessive inflammatory responses and observations of inflammation in the absence of infection.

METHODS

To determine whether IL-10 deficiency could account for persistent inflammation in CF mice independent of interactions of bacteria with epithelial cells, we challenged IL-10-knockout (IL-10-KO), CF-KO, and wild-type (WT) mice intratracheally with LPS and determined the effects of IL-10 replacement in CF-KO mice.

RESULTS

In response to LPS, IL-10-KO and CF-KO mice had more neutrophils and proinflammatory cytokines in bronchoalveolar lavage than WT mice. Both types of knockout mice had more profound and prolonged consumption of I-kappaB and increased activation of nuclear factor kappaB (NF-kappaB). Activated NF-kappaB persisted for 6 to 8 hours in CF-KO and IL-10-KO mice but was not detected beyond 2 hours in WT mice. IL-10 treatment of CF-KO mice attenuated the reduction in I-kappaBalpha and activation of NF-kappaB and reduced the excessive inflammation.

CONCLUSION

Similarities in the responses of CF-KO and IL-10-KO mice and correction of excessive responses in CF mice by exogenous IL-10 suggest that deficiency of IL-10 may be responsible for prolonged and excessive inflammatory responses in CF. Because LPS was used as the stimulus, these excessive responses are independent of any possible differences in the interactions of bacteria with CF epithelial cells.

NF-kappaB activation and sustained IL-8 gene expression in primary cultures of cystic fibrosis airway epithelial cells stimulated with Pseudomonas aeruginosa

The progression of lung disease in cystic fibrosis (CF) is characterized by an exuberant inflammatory response mounted by the respiratory epithelium that is further exacerbated by bacterial infection. Recent studies have demonstrated upregulation of nuclear factor-kappaB (NF-kappaB) in response to infection in genetically modified cell culture models, which is associated with expression of interleukin (IL)-8. Using human airway epithelial cells grown in primary culture, we examined in vitro activation of NF-kappaB in cells isolated from five CF (DeltaF508/DeltaF508) and three non-CF (NCF) patients in response to Pseudomonas aeruginosa. Immunofluorescence, gel-shift, and immunoblot assays demonstrated a rapid translocation of NF-kappaB subunits (p50 and p65) to the nucleus in both CF and NCF cell cultures. However, nuclear extracts from CF cells both before and following P. aeruginosa stimulation revealed elevated NF-kappaB activation compared with NCF cells. Additionally, elevated nuclear levels of the NF-kappaB inhibitor IkappaBalpha were detected in nuclei of CF cells after P. aeruginosa stimulation, but this increase was transient. There was no difference in IL-8 mRNA levels between CF and NCF cells early after stimulation, whereas expression was higher and sustained in CF cells at later times. Our results also demonstrated increased baseline translocation of NF-kappaB to nuclei of primary CF epithelial cell cultures, but intranuclear IkappaBalpha may initially block its effects following P. aeruginosa stimulation. Thus, IL-8 mRNA expression was prolonged after P. aeruginosa stimulation in CF epithelial cells, and this sustained IL-8 expression may contribute to the excessive inflammatory response in CF.

Differential expression of IL-10 receptor by epithelial cells and alveolar macrophages

BACKGROUND

Interleukin (IL)-10 is a pleiotropic cytokine with a broad spectrum of immunosuppressive and anti-inflammatory effects. IL-10 secretion from alveolar macrophages is defective in patients with asthma and lower concentrations of IL-10 are found in bronchoalveolar lavage (BAL) from asthmatic patients than in normal control subjects. Reduced IL-10 may result in exaggerated and more prolonged inflammatory responses in asthmatic airways. IL-10 acting through the IL-10 receptor (IL-10R) stimulates the transcription factors STAT1 and STAT3.

METHODS

We investigated IL-10 and IL-10R expression in normal and asthmatic bronchial epithelium and BAL macrophages using reverse transcription-polymerase chain reaction, immunohistochemistry and Western blotting. The functional effect of IL-10 was examined using granulocyte-macrophage-colony stimulating factor, enzyme-linked immunosorbent assay and Western blotting for phosphorylated STAT1 and STAT3.

RESULTS

IL-10 was not expressed in epithelial cells; furthermore these cells did not express the IL-10R and had no functional response to exogenous IL-10. Bronchial epithelial cells expressed variable levels of phosphorylated STAT1 and STAT3 with no change in expression between normal subjects and asthmatics. IL-10 protein and IL-10R expression was detected in alveolar macrophages from all subjects.

CONCLUSION

Our study suggests that the bronchial epithelium is not a source of IL-10 and cannot respond to exogenous IL-10 because of a lack of IL-10R expression.

Reduction of chemokine IL-8 and RANTES expression in human bronchial epithelial cells by a sea-water derived saline through inhibited nuclear factor-kappaB activation

The NaCl content of airway surface fluid is believed to be of central importance in lung pathology. To test whether the Na+ concentration could influence the inflammatory response in human bronchial epithelial cells (BECs), we investigated the interleukin (IL)-8 and RANTES expression in BECs exposed to an isotonic sea-water derived low Na+ (ISW) saline compared to isotonic 0.9% NaCl saline. Exposure of BECs to ISW saline caused a significant decrease in IL-8 and RANTES gene expression and protein production as compared to that observed with 0.9% NaCl saline. Furthermore, we observed a concomitant reduction of phosphorylated IkappaBalpha associated with a marked inhibition of NF-kappaB-DNA binding activity in BECs exposed to ISW saline as compared to 0.9% NaCl saline. These findings support a new role for Na+ in the pathogenesis of airway inflammatory disorders. Therapies targeted at lowering Na+ level in airway epithelium may be beneficial in treating inflammatory lung diseases.

Cyclooxygenase-2-deficient mice are resistant to endotoxin-induced inflammation and death

Sepsis is a systemic inflammatory response to a blood-borne infection that is associated with an extremely high rate of morbidity and mortality. The present study investigates the role of cyclooxygenase (COX)-2 in host responses to bacterial endotoxemia. After administration of Escherichia coli lipopolysaccharide, 50% of wild-type mice die within 96 h. COX-2 deficient mice displayed a dramatic improvement in survival with reduced leukocyte infiltration into critical organs (kidneys and lungs) and a blunted and delayed induction of the cytokine inducible genes nitric oxide synthase 2 and heme oxygenase-1. Translocation and activation of transcription factors important for signaling events during an inflammatory response, such as nuclear factor (NF)-kappaB, were also markedly reduced. While the absence of COX-2 did not alter the induction of several pro-inflammatory cytokines in tissue macrophages, induction of the anti-inflammatory cytokine IL-10 was exaggerated. Administration of IL-10 to wild-type mice reduced NF-kappaB activation. Taken together, our data suggest that COX-2 deficient mice are resistant to many of the detrimental consequences of endotoxemia. These beneficial effects occur, in part, by a compensatory increase in IL-10 that counterbalances the pro-inflammatory host response to endotoxemia.