CCR2 and CXCR3 agonistic chemokines are differently expressed and regulated in human alveolar epithelial cells type II

CXCR3-independent role of CXCL10 in alveolar epithelial repair

The alveolar type II epithelial cells (AEC2s) act as stem cells in the lung for alveolar epithelial maintenance and repair. Chemokine C-X-C motif chemokine 10 (CXCL10) is expressed in injured tissues, modulating multiple cellular functions. AEC2s, previously reported to release chemokines to recruit leukocytes, were found in our study to secrete CXCL10 after bleomycin injury. We found that Sftpc-Cxcl10 transgenic mice were protected from bleomycin injury. The transgenic mice showed an increase in the AEC2 population in the lung by flow cytometry analysis. Both endogenous and exogenous CXCL10 promoted the colony formation efficiency of AEC2s in a three-dimensional (3-D) organoid growth assay. We identified that the regenerative effect of CXCL10 was CXCR3 independent using Cxcr3-deficient mice, but it was related to the TrkA pathway. Binding experiments showed that CXCL10 interacted with TrkA directly and reversibly. This study demonstrates a previously unidentified AEC2 autocrine signaling of CXCL10 to promote their regeneration and proliferation, probably involving a CXCR3-independent TrkA pathway.NEW & NOTEWORTHY CXCL10 may aid in lung injury recovery by promoting the proliferation of alveolar stem cells and using a distinct regulatory pathway from the classical one.

Hydrogen ameliorates endotoxin-induced acute lung injury through AMPK-mediated bidirectional regulation of Caspase3

Septic lung injury is characterized by uncontrollable inflammatory infiltrations and acute onset bilateral hypoxemia. Evidence has emerged of the beneficial effect of hydrogen in acute lung injury (ALI), but the underlying mechanism is unclear. In this research, the recovery action of hydrogen on lipopolysaccharide (LPS)-induced ALI in mice and A549 cells was investigated. The 7-day survival rate and body weight of mice were measured after intraperitoneal injection of LPS. Lung function was determined by a whole body plethysmography (WBP) system using the indicators respiratory rate and enhanced pause. Hematoxylin and eosin (HE) staining confirmed the signs of pulmonary edema and inflammatory ooze. Reverse transcription-polymerase chain reaction (RT-PCR) quantification was used to detect the expression of inflammatory factors. Western blotting analysis evaluated the expression levels of involved proteins in the AMP-activated protein kinase (AMPK) pathway. The experimental results confirmed that hydrogen provided an essential solution to the dissipative effects of LPS on survival rate, weight loss and lung function. The LPS-stimulated inflammatory factors, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also suppressed by hydrogen in A549 cells. Western blot analysis showed that hydrogen significantly upregulated the levels of phosphorylated AMPK (p-AMPK) and lowered the LPS-induced increased expression of dynamin-related protein 1 (Drp1) and Caspase3. These findings prove that hydrogen attenuated LPS-treated ALI by activating the AMPK pathway, supporting the feasibility of hydrogen treatment for sepsis.

A four-part guide to lung immunology: Invasion, inflammation, immunity, and intervention

Lungs are important respiratory organs primarily involved in gas exchange. Lungs interact directly with the environment and their primary function is affected by several inflammatory responses caused by allergens, inflammatory mediators, and pathogens, eventually leading to disease. The immune architecture of the lung consists of an extensive network of innate immune cells, which induce adaptive immune responses based on the nature of the pathogen(s). The balance of immune responses is critical for maintaining immune homeostasis in the lung. Infection by pathogens and physical or genetic dysregulation of immune homeostasis result in inflammatory diseases. These responses culminate in the production of a plethora of cytokines such as TSLP, IL-9, IL-25, and IL-33, which have been implicated in the pathogenesis of several inflammatory and autoimmune diseases. Shifting the balance of Th1, Th2, Th9, and Th17 responses have been the targets of therapeutic interventions in the treatment of these diseases. Here, we have briefly reviewed the innate and adaptive i3mmune responses in the lung. Genetic and environmental factors, and infection are the major causes of dysregulation of various functions of the lung. We have elaborated on the impact of inflammatory and infectious diseases, advances in therapies, and drug delivery devices on this critical organ. Finally, we have provided a comprehensive compilation of different inflammatory and infectious diseases of the lungs and commented on the pros and cons of different inhalation devices for the management of lung diseases. The review is intended to provide a summary of the immunology of the lung, with an emphasis on drug and device development.

Longitudinal Cytokine Profile in Patients With Mild to Critical COVID-19

The cytokine release syndrome has been proposed as the driver of inflammation in coronavirus disease 2019 (COVID-19). However, studies on longitudinal cytokine profiles in patients across the whole severity spectrum of COVID-19 are lacking. In this prospective observational study on adult COVID-19 patients admitted to two Hong Kong public hospitals, cytokine profiling was performed on blood samples taken during early phase (within 7 days of symptom onset) and late phase (8 to 12 days of symptom onset). The primary objective was to evaluate the difference in early and late cytokine profiles among patient groups with different disease severity. The secondary objective was to assess the associations between cytokines and clinical endpoints in critically ill patients. A total of 40 adult patients (mild = 8, moderate = 15, severe/critical = 17) hospitalized with COVID-19 were included in this study. We found 22 cytokines which were correlated with disease severity, as proinflammatory Th1-related cytokines (interleukin (IL)-18, interferon-induced protein-10 (IP-10), monokine-induced by gamma interferon (MIG), and IL-10) and ARDS-associated cytokines (IL-6, monocyte chemoattractant protein-1 (MCP-1), interleukin-1 receptor antagonist (IL-1RA), and IL-8) were progressively elevated with increasing disease severity. Furthermore, 11 cytokines were consistently different in both early and late phases, including seven (growth-regulated oncogene-alpha (GRO-α), IL-1RA, IL-6, IL-8, IL-10, IP-10, and MIG) that increased and four (FGF-2, IL-5, macrophage-derived chemokine (MDC), and MIP-1α) that decreased from mild to severe/critical patients. IL-8, followed by IP-10 and MDC were the best performing early biomarkers to predict disease severity. Among critically ill patients, MCP-1 predicted the duration of mechanical ventilation, highest norepinephrine dose administered, and length of intensive care stay.

Immunopathology of Hyperinflammation in COVID-19

The rapid spread of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), has resulted in an unprecedented public health crisis worldwide. Recent studies indicate that a hyperinflammatory syndrome induced by SARS-CoV-2 contributes to disease severity and mortality in COVID-19. In this review, an overview of the pathophysiology underlying the hyperinflammatory syndrome in severe COVID-19 is provided. The current evidence suggests that the hyperinflammatory syndrome results from a dysregulated host innate immune response. The gross and microscopic pathologic findings as well as the alterations in the cytokine milieu, macrophages/monocytes, natural killer cells, T cells, and neutrophils in severe COVID-19 are summarized. The data highlighted include the potential therapeutic approaches undergoing investigation to modulate the immune response and abrogate lung injury in severe COVID-19.

Inhibition of viral and bacterial trigger-stimulated prostaglandin E2 by a throat lozenge containing flurbiprofen: An in vitro study using a human respiratory epithelial cell line

Objectives:

Symptoms of sore throat result from oropharyngeal inflammation, for which prostaglandin E₂ is a key mediator. Flurbiprofen is a non-steroidal anti-inflammatory that provides sore throat relief. The preliminary objective of this study was to develop an in vitro model for assessing prostaglandin E₂ stimulation by viral and bacterial triggers. The primary objective was to investigate the effect of diluted flurbiprofen-containing lozenges on prostaglandin E₂ concentrations in stimulated cells.

Methods:

Prostaglandin E₂ production was stimulated in three epithelial cell lines (A549, HEp2, and clonetics bronchial/tracheal epithelial) with influenza A virus (4.5 log₁₀ tissue culture infectious dose₅₀/mL), or bacterial lipopolysaccharide (10µ g/mL) and peptidoglycan (3µ g/mL) and incubated overnight. Prostaglandin E₂ levels were assessed by enzyme-linked immunosorbent assay up to 24 h after stimulation. The effect of flurbiprofen 8.75 mg lozenges (diluted to 0.44 mg/mL) on PGE₂ production in stimulated cells was assessed in parallel; prior to viral/LPS/PEP stimulation of cells, 300 μL of test product or control was added and incubated for 30 s, 2 and 5 min (and 10 min for bacterial trigger). Prostaglandin E₂ levels were measured following stimulation.

Results:

Viral and lipopolysaccharide/peptidoglycan infection did not consistently stimulate HEp2 cells and bronchial/tracheal epithelial cells to produce prostaglandin E₂. Influenza virus, and lipopolysaccharide/peptidoglycan stimulated high prostaglandin E₂ concentrations in A549: mean prostaglandin E₂ concentration 106.48 pg/mL with viral stimulation vs 33.82 pg/mL for uninfected cells; 83.84 pg/mL with lipopolysaccharide/peptidoglycan vs 71.96 pg/mL for uninfected cells. Flurbiprofen produced significant reductions in virus-stimulated prostaglandin E₂ vs stimulated untreated cells at 2 min (p = 0.03). Flurbiprofen produced significant reductions in lipopolysaccharide/peptidoglycan-stimulated prostaglandin E₂ concentrations from 30 s (p = 0.02), and at 2, 5 and 10 min (all p < 0.005) vs stimulated untreated cells.

Conclusions:

A549 cells provide a suitable model for assessment of prostaglandin E₂ stimulation by viral and bacterial triggers. Diluted flurbiprofen-containing lozenges demonstrated rapid anti-inflammatory activity in viral- and lipopolysaccharide/peptidoglycan-stimulated A549 cells.

Gaining insights on immune responses to the novel coronavirus, COVID-19 and therapeutic challenges

SARS-CoV-2 is a new member of coronaviruses that its sudden spreading put the health care system of most countries in a tremendous shock. For controlling of the new infection, COVID-19, many efforts have been done and are ongoing to defeat this virus in the combat field. In this review, we focused on how the immune system behaves toward the virus and the relative possible consequences during their interactions. Then the therapeutic steps and potential vaccine candidates have been described in a hope to provide a better prospective of effective treatment and preventive strategies to the novel SARS-CoV in near future.

Characterization of the cytokine storm reflects hyperinflammatory endothelial dysfunction in COVID-19

BACKGROUND

Physicians treating patients with coronavirus disease 2019 (COVID-19) increasingly believe that the hyperinflammatory acute stage of COVID-19 results in a cytokine storm. The circulating biomarkers seen across the spectrum of COVID-19 have not been characterized compared with healthy controls, but such analyses are likely to yield insights into the pursuit of interventions that adequately reduce the burden of these cytokine storms.

OBJECTIVE

To identify and characterize the host inflammatory response to severe acute respiratory syndrome coronavirus 2 infection, we assessed levels of proteins related to immune responses and cardiovascular disease in patients stratified as mild, moderate, and severe versus matched healthy controls.

METHODS

Blood samples from adult patients hospitalized with COVID-19 were analyzed using high-throughput and ultrasensitive proteomic platforms and compared with age- and sex-matched healthy controls to provide insights into differential regulation of 185 markers.

RESULTS

Results indicate a dominant hyperinflammatory milieu in the circulation and vascular endothelial damage markers within patients with COVID-19, and strong biomarker association with patient response as measured by Ordinal Scale. As patients progress, we observe statistically significant dysregulation of IFN-γ, IL-1RA, IL-6, IL-10, IL-19, monocyte chemoattractant protein (MCP)-1, MCP-2, MCP-3, CXCL9, CXCL10, CXCL5, ENRAGE, and poly (ADP-ribose) polymerase 1. Furthermore, in a limited series of patients who were sampled frequently, confirming reliability and reproducibility of our assays, we demonstrate that intervention with baricitinib attenuates these circulating biomarkers associated with the cytokine storm.

CONCLUSIONS

These wide-ranging circulating biomarkers show an association with increased disease severity and may help stratify patients and selection of therapeutic options. They also provide insights into mechanisms of severe acute respiratory syndrome coronavirus 2 pathogenesis and the host response.

SARS Unique Domain (SUD) of Severe Acute Respiratory Syndrome Coronavirus Induces NLRP3 Inflammasome-Dependent CXCL10-Mediated Pulmonary Inflammation

Severe acute respiratory syndrome–associated coronavirus (SARS-CoV) initiates the cytokine/chemokine storm-mediated lung injury. The SARS-CoV unique domain (SUD) with three macrodomains (N, M, and C), showing the G-quadruplex binding activity, was examined the possible role in SARS pathogenesis in this study. The chemokine profile analysis indicated that SARS-CoV SUD significantly up-regulated the expression of CXCL10, CCL5 and interleukin (IL)-1β in human lung epithelial cells and in the lung tissues of the mice intratracheally instilled with the recombinant plasmids. Among the SUD subdomains, SUD-MC substantially activated AP-1-mediated CXCL10 expression in vitro. In the wild type mice, SARS-CoV SUD-MC triggered the pulmonary infiltration of macrophages and monocytes, inducing CXCL10-mediated inflammatory responses and severe diffuse alveolar damage symptoms. Moreover, SUD-MC actuated NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome-dependent pulmonary inflammation, as confirmed by the NLRP3 inflammasome inhibitor and the NLRP3^−/− mouse model. This study demonstrated that SARS-CoV SUD modulated NLRP3 inflammasome-dependent CXCL10-mediated pulmonary inflammation, providing the potential therapeutic targets for developing the antiviral agents.

Acacia catechu (L.f.) Willd and Scutellaria baicalensis Georgi extracts suppress LPS-induced pro-inflammatory responses through NF-кB, MAPK, and PI3K-Akt signaling pathways in alveolar epithelial type II cells

Acacia catechu (L.f.) Willd (ACW) and Scutellaria baicalensis Georgi (SBG) are one of the most famous couplet Chinese medicines, widely used for treating infantile cough, phlegm, and fever caused by pulmonary infection. However, the underlying molecular mechanism of their anti-inflammatory activity has not been determined. The aim of this study was to evaluate the protective effect of this couplet Chinese medicines (ACW-SBG) on lipopolysaccharide (LPS)-induced inflammatory responses in acute lung injury (ALI) model of rats and the potential molecular mechanisms responsible for anti-inflammatory activities in alveolar epithelial type II cells (AEC-II). Standardization of the 70% ethanol extract of ACW and SBG was performed by using a validated reversed-phase high-pressure liquid chromatography method. Rats were pretreated with ACW-SBG for 7 days prior to LPS challenge. We assessed the effects of ACW-SBG on the LPS-induced production of tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) in the bronchoalveolar lavage fluid (BALF). The wet-to-dry weight ratio was calculated, and hematoxylin and eosin staining of lung tissue was performed. Cell viability of AEC-II was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Real-time quantitative reverse transcription polymerase chain reaction assay was carried out to quantify the relative gene expression of TNF-α and IL-1β in AEC-II. The western blotting analysis was executed to elucidate the expression of mediators linked to nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and phosphatidylinositol-3 kinase-protein kinase B (PI3K-Akt) signaling pathways. ACW-SBG significantly decreased lung wet-to-dry weight ratio, ameliorated LPS-induced lung histopathological changes, and reduced the release of inflammatory mediators such as TNF-α and IL-1β in BALF. In AEC-II, we found that the expression of TNF-α mRNA was also inhibited by ACW-SBG. ACW-SBG blocked NF-κB activation by preventing the phosphorylation of NF-κB (p65) as well as the phosphorylation and degradation of the inhibitor of kappa B kinase. ACW-SBG extracts also inhibited the phosphorylation of respective MAPKs (c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38) as well as Akt. The present study demonstrated that ACW-SBG played a potent anti-inflammatory role in LPS-induced ALI in rats. The potential molecular mechanism was involved in attenuating the NF-κB, MAPKs, and PI3K-Akt signaling pathways in LPS-induced AEC-II.

Serum CXCL9 and CCL17 as biomarkers of declining pulmonary function in chronic bird-related hypersensitivity pneumonitis

The clinical course of chronic hypersensitivity pneumonitis (HP) with fibrosis is similar to that of idiopathic pulmonary fibrosis (IPF). Current research is expected to identify biomarkers effective in predicting the deterioration of lung function in a clinical setting. Our group analyzed the relationships between the following parameters in chronic bird-related HP: patient characteristics, serum markers, lung function, HRCT findings, BALF profiles, and the worsening of lung function. We also analyzed serum levels of CXCL9, CCL17, and Krebs von den Lungen 6 (KL-6) as serum markers. Patients showing declines in vital capacity (VC) of over 5% at 6 months after first admission were categorized as the “decline group”; the others were categorized as the “stable group.” The serum level of CCL17 and the percentage of BALF macrophages were significantly higher in the decline group compared to the stable group. Serum levels of CXCL9 and CCL17 were significant variables in a multivariate logistic regression analysis of factors associated with VC decline. Patients with a chemokine profile combining lower serum CXCL9 and higher serum CCL17 exhibited significantly larger VC decline in a cluster analysis. Higher serum CCL17 and lower serum CXCL9 were important predictors of worsening lung function in patients with chronic bird-related HP.

Chemokines in COPD: From Implication to Therapeutic Use

: Chronic Obstructive Pulmonary Disease (COPD) represents the 3rd leading cause of death in the world. The underlying pathophysiological mechanisms have been the focus of extensive research in the past. The lung has a complex architecture, where structural cells interact continuously with immune cells that infiltrate into the pulmonary tissue. Both types of cells express chemokines and chemokine receptors, making them sensitive to modifications of concentration gradients. Cigarette smoke exposure and recurrent exacerbations, directly and indirectly, impact the expression of chemokines and chemokine receptors. Here, we provide an overview of the evidence regarding chemokines involvement in COPD, and we hypothesize that a dysregulation of this tightly regulated system is critical in COPD evolution, both at a stable state and during exacerbations. Targeting chemokines and chemokine receptors could be highly attractive as a mean to control both chronic inflammation and bronchial remodeling. We present a special focus on the CXCL8-CXCR1/2, CXCL9/10/11-CXCR3, CCL2-CCR2, and CXCL12-CXCR4 axes that seem particularly involved in the disease pathophysiology.

Linking tyrosine kinase inhibitor-mediated inflammation with normal epithelial cell homeostasis and tumor therapeutic responses

Receptor tyrosine kinases (RTKs) bearing oncogenic mutations in EGFR, ALK and ROS1 occur in a significant subset of lung adenocarcinomas. Tyrosine kinase inhibitors (TKIs) targeting tumor cells dependent on these oncogenic RTKs yield tumor shrinkage, but also a variety of adverse events. Skin toxicities, hematological deficiencies, nausea, vomiting, diarrhea, and headache are among the most common, with more acute and often fatal side effects such as liver failure and interstitial lung disease (ILD) occurring less frequently. In normal epithelia, RTKs regulate tissue homeostasis. For example, EGFR maintains keratinocyte homeostasis while MET regulates processes associated with tissue remodeling. Previous studies suggest that the acneiform rash occurring in response to EGFR inhibition is a part of an inflammatory response driven by pronounced cytokine and chemokine release and recruitment of distinct immune cell populations. Mechanistically, blockade of EGFR causes a Type I interferon (IFN) response within keratinocytes and in carcinoma cells driven by this RTK. This innate immune response within the tumor microenvironment (TME) involves increased antigen presentation and effector T cell recruitment that may participate in therapy response. This TKI-mediated release of inflammatory suppression represents a novel tumor cell vulnerability that may be exploited by combining TKIs with immune-oncology (IO) agents that rely on T-cell inflammation for efficacy. However, early clinical data indicate that combination therapies enhance the frequency and magnitude of the more acute adverse events, especially pneumonitis, hepatitis, and pulmonary fibrosis. Further preclinical studies to understand TKI mediated inflammation and crosstalk between normal epithelial cells, cancer cells, and the TME are necessary to improve treatment regimens for patients with RTK-driven carcinomas.

The Role of Mitochondria and Oxidative/Antioxidative Imbalance in Pathobiology of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common preventable and treatable disease, characterized by persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. The major risk factor of COPD, which has been proven in many studies, is the exposure to cigarette smoke. However, it is 15-20% of all smokers who develop COPD. This is why we should recognize the pathobiology of COPD as involving a complex interaction between several factors, including genetic vulnerability. Oxidant-antioxidant imbalance is recognized as one of the significant factors in COPD pathogenesis. Numerous exogenous and endogenous sources of ROS are present in pathobiology of COPD. One of endogenous sources of ROS is mitochondria. Although leakage of electrons from electron transport chain and forming of ROS are the effect of physiological functioning of mitochondria, there are various intra- and extracellular factors which may increase this amount and significantly contribute to oxidative-antioxidative imbalance. With the coexistence with impaired antioxidant defence, all these issues lead to oxidative and carbonyl stress. Both of these states play a significant role in pathobiology of COPD and may account for development of major comorbidities of this disease.

Cellular Players in the Immunopathogenesis of Sarcoidosis

Current hypotheses on the pathogenesis of sarcoidosis assume that it is induced by a nondegradable antigen inducing immune reactions, which are mediated by a panel of immune cells of the innate and adoptive immune system. This immune reaction leads to an accumulation of immune cells that is mainly alveolar macrophages, T cells, and neutrophils in the lung. As the antigen persists and cannot be eliminated, the ongoing immune reaction results in granuloma formation and remodeling of the lung. The current review aims to elucidate the different roles of the cellular players in the immunopathogenesis of sarcoidosis.

Effect of JAK Inhibitors on Release of CXCL9, CXCL10 and CXCL11 from Human Airway Epithelial Cells

Background

CD8⁺ T-cells are located in the small airways of COPD patients and may contribute to pathophysiology. CD8⁺ cells express the chemokine receptor, CXCR3 that binds CXCL9, CXCL10 and CXCL11, which are elevated in the airways of COPD patients. These chemokines are released from airway epithelial cells via activation of receptor associated Janus kinases (JAK). This study compared the efficacy of two structurally dissimilar pan-JAK inhibitors, PF956980 and PF1367550, and the glucocorticosteroid dexamethasone, in BEAS-2B and human primary airway epithelial cells from COPD patients and control subjects.

Methods

Cells were stimulated with either IFNγ alone or with TNFα, and release of CXCL9, CXCL10 and CXCL11 measured by ELISA and expression of CXCL9, CXCL10 and CXCL11 by qPCR. Activation of JAK signalling was assessed by STAT1 phosphorylation and DNA binding.

Results

There were no differences in the levels of release of CXCL9, CXCL10 and CXCL11 from primary airway epithelial cells from any of the subjects or following stimulation with either IFNγ alone or with TNFα. Dexamethasone did not inhibit CXCR3 chemokine release from stimulated BEAS-2B or primary airway epithelial cells. However, both JAK inhibitors suppressed this response with PF1367550 being ~50-65-fold more potent than PF956980. The response of cells from COPD patients did not differ from controls with similar responses regardless of whether inhibitors were added prophylactically or concomitant with stimuli. These effects were mediated by JAK inhibition as both compounds suppressed STAT1 phosphorylation and DNA-binding of STAT1 and gene transcription.

Conclusions

These data suggest that the novel JAK inhibitor, PF1367550, is more potent than PF956980 and that JAK pathway inhibition in airway epithelium could provide an alternative anti-inflammatory approach for glucocorticosteroid-resistant diseases including COPD.

CCR2-64I polymorphism is associated with Non-Small Cell Lung Cancer in Tunisian patients

Single nucleotide polymorphism (SNPs) in genes coding for chemokines may be associated with some cancer. The purpose of this study was to investigate the impact of CCR2-64I and CXCL12-3'A SNPs on the susceptibility and the clinicopathological characteristics of NSCLC (Non-Small Cell Lung Cancer) in the Tunisian population. 170 NSCLC patients and 225 healthy controls screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis were enrolled. A significant association for the homozygous genotype CCR2 64I/64I with lung cancer risk was observed (P=0.004). An increased significant frequency of the -64I allele (P=0.0006) was noted in the patient's group. Clinical analysis indicated a positive association of the -64I allele among squamous cell lung carcinoma patients (P=0.003). The CCR2 mRNA extracted from peripheral blood mononuclear cells (PBMC) was found highly expressed in NSCLC patients compared to controls. The same higher levels were found in patients carrying the CCR2 64I/64I genotype. No significant association was retrieved with CXCL12-3'A polymorphism. In conclusion, our results revealed that the subjects with -64I allele of CCR2-64I gene polymorphism, expressed a significantly higher risk for NSCLC risk without influence on its pathological progression.

The chemokine CXCL9 exacerbates chemotherapy-induced acute intestinal damage through inhibition of mucosal restitution

PURPOSE

Acute intestinal damage induced by chemotherapeutic agent is often a dose-limiting factor in clinical cancer therapy. The aim of this study was to investigate the effect of chemokine CXCL9 on the intestinal damage after chemotherapy and explore the therapeutic potential of anti-CXCL9 agents.

METHODS

In vitro cell proliferation assay was performed with a non-tumorigenic human epithelial cell line MCF10A. Multiple pathway analysis was carried out to explore the pathway that mediated the effect of CXCL9, and the corresponding downstream effector was identified with enzyme-linked immunosorbent assays. Chemotherapy-induced mouse model of intestinal mucositis was prepared by a single injection of the chemotherapeutic agent 5-fluorouracil (5-FU). In vivo expression of cxcl9 and its receptor cxcr3 in intestinal mucosa after chemotherapy was determined by quantitative real-time PCR. Therapeutic treatment with anti-CXCL9 antibodies was investigated to confirm the hypothesis that CXCL9 can contribute to the intestinal epithelium damage induced by chemotherapy.

RESULTS

CXCL9 inhibited the proliferation of MCF10A cells by activating phosphorylation of p70 ribosomal S6 kinase (p70S6K), which further promotes the secretion of transforming growth factor beta (TGF-β) as the downstream effector. A blockade of phospho-p70S6K with inhibitor abolished the effect of CXCL9 on MCF10A cells and reduced the secretion of TGF-β. The expression levels of cxcl9 and cxcr3 were significantly up-regulated in intestinal mucosa after 5-FU injection. Neutralizing elevated CXCL9 with anti-CXCR9 antibodies successfully enhanced reconstitution of intestinal mucosa and improved the survival rate of mice that received high-dose chemotherapy.

CONCLUSIONS

CXCL9 inhibits the proliferation of epithelial cells via phosphorylation of p70S6K, resulting in the excretion of TGF-β as downstream mediator. CXCL9/CXCR3 interaction can exacerbate chemotherapeutic agent-induced intestinal damage, and anti-CXCL9 agents are potential novel therapeutic candidates for promoting mucosal restitution.

Macrophage control of phagocytosed mycobacteria is increased by factors secreted by alveolar epithelial cells through nitric oxide independent mechanisms

Tissue-resident macrophages are heterogeneous with tissue-specific and niche-specific functions. Thus, simplified models of macrophage activation do not explain the extent of heterogeneity seen in vivo. We focus here on the respiratory tract and ask whether factors secreted by alveolar epithelial cells (AEC) can influence the functionality of resident pulmonary macrophages (PuM). We have previously reported that factors secreted by AEC increase control of intracellular growth of BCG in macrophages. In the current study, we also aimed to investigate possible mechanisms by which AEC-derived factors increase intracellular control of BCG in both primary murine interstitial macrophages, and bone marrow-derived macrophages and characterize further the effect of these factors on macrophage differentiation. We show that; a) in contrast to other macrophage types, IFN-γ did not increase intracellular growth control of Mycobacterium bovis, Bacillus Calmette-Guérin (BCG) by interstitial pulmonary macrophages although the same macrophages could be activated by factors secreted by AEC; b) the lack of response of pulmonary macrophages to IFN-γ was apparently regulated by suppressor of cytokine signaling (SOCS)1; c) AEC-derived factors did not induce pro-inflammatory pathways induced by IFN-γ e.g. expression of inducible nitric oxide synthase (iNOS), secretion of nitric oxide (NO), or IL-12, d) in contrast to IFN-γ, intracellular bacterial destruction induced by AEC-derived factors was not dependent on iNOS transcription and NO production. Collectively, our data show that PuM were restricted in inflammatory responses mediated by IFN-γ through SOCS1 and that factors secreted by AEC- enhanced the microbicidal capacities of macrophages by iNOS independent mechanisms.

Aqueous two-phase systems enable multiplexing of homogeneous immunoassays

Quantitative measurement of protein biomarkers is critical for biomarker validation and early disease detection. Current multiplex immunoassays are time consuming costly and can suffer from low accuracy. For example, multiplex ELISAs require multiple, tedious, washing and blocking steps. Moreover, they suffer from nonspecific antibody cross-reactions, leading to high background and false-positive signals. Here, we show that co-localizing antibody-bead pairs in an aqueous two-phase system (ATPS) enables multiplexing of sensitive, no-wash, homogeneous assays, while preventing nonspecific antibody cross-reactions. Our cross-reaction-free, multiplex assay can simultaneously detect picomolar concentrations of four protein biomarkers ((C-X-C motif) ligand 10 (CXCL10), CXCL9, interleukin (IL)-8 and IL-6) in cell supernatants using a single assay well. The potential clinical utility of the assay is demonstrated by detecting diagnostic biomarkers (CXCL10 and CXCL9) in plasma from 88 patients at the onset of the clinical symptoms of chronic graft-versus-host disease (GVHD).

Granuloma formation in pulmonary sarcoidosis

Sarcoidosis is a granulomatous disorder of unknown cause, affecting multiple organs, but mainly the lungs. The exact order of immunological events remains obscure. Reviewing current literature, combined with careful clinical observations, we propose a model for granuloma formation in pulmonary sarcoidosis. A tight collaboration between macrophages, dendritic cells, and lymphocyte subsets, initiates the first steps toward granuloma formation, orchestrated by cytokines and chemokines. In a substantial part of pulmonary sarcoidosis patients, granuloma formation becomes an on-going process, leading to debilitating disease, and sometimes death. The immunological response, determining granuloma sustainment is not well understood. An impaired immunosuppressive function of regulatory T cells has been suggested to contribute to the exaggerated response. Interestingly, therapeutical agents commonly used in sarcoidosis, such as glucocorticosteroids and anti-TNF agents, interfere with granuloma integrity and restore the immune homeostasis in autoimmune disorders. Increasing insight into their mechanisms of action may contribute to the search for new therapeutical targets in pulmonary sarcoidosis.

Regulation of Monocyte Chemotactic Protein-1 secretion by the Two-Pore-Domain Potassium (K2P) channel TREK-1 in human alveolar epithelial cells

We recently proposed a role for the 2-pore-domain K(+) (K2P) channel TREK-1 in the regulation of cytokine release from alveolar epithelial cells (AECs) by demonstrating decreased IL-6 secretion from TREK-1 deficient cells, but the effects of altered TREK-1 expression on other inflammatory mediators remain poorly understood. We now examined the role of TREK-1 in TNF-α-induced MCP-1 release from human A549 cells. We hypothesized that TREK-1 regulates TNF-α-induced MCP-1 secretion via c-Jun N-terminal kinases (JNK)- and protein kinase-C (PKC)-dependent pathways. In contrast to IL-6 secretion, we found that TREK-1 deficiency resulted in increased MCP-1 production and secretion, although baseline MCP-1 gene expression was unchanged in TREK-1 deficient cells. In contrast to TREK-1 deficient AECs, overexpression of MCP-1 had no effect on MCP-1 secretion. Phosphorylation of JNK1/2/3 was increased in TREK-1 deficient cells upon TNF-α stimulation, but pharmacological inhibition of JNK1/2/3 decreased MCP-1 release from both control and TREK-1 deficient cells. Similarly, pharmacological inhibition of PKC decreased MCP-1 secretion from control and TREK-1 deficient cells, suggesting that alterations in JNK and PKC signaling pathways were unlikely the cause for the increased MCP-1 secretion from TREK-1 deficient cells. Furthermore, MCP-1 secretion from control and TREK-1 deficient cells was independent of extracellular Ca(2+) but sensitive to inhibition of intracellular Ca(2+) reuptake mechanisms. In summary, we report for the first time that TREK-1 deficiency in human AECs resulted in increased MCP-1 production and secretion, and this effect appeared unrelated to alterations in JNK-, PKC- or Ca(2+)-mediated signaling pathways in TREK-1 deficient cells.

Burkholderia mallei and Burkholderia pseudomallei stimulate differential inflammatory responses from human alveolar type II cells (ATII) and macrophages

Alveolar type II pneumocytes (ATII) and alveolar macrophages (AM) play a crucial role in the lung's innate immune response. Burkholderia pseudomallei (BP) and Burkholderia mallei (BM) are facultative Gram-negative bacilli that cause melioidosis and glanders, respectively. The inhalation of these pathogens can cause lethal disease and death in humans. We sought to compare the pathogenesis of and host responses to BP and BM through contact with human primary ATII cells and monocytes-derived macrophages (MDM). We hypothesized that because BP and BM induce different disease outcomes, each pathogen would induce distinct, unique host immune responses from resident pulmonary cells. Our findings showed that BP adhered readily to ATII cells compared to BM. BP, but not BM, was rapidly internalized by macrophages where it replicated to high numbers. Further, BP-induced significantly higher levels of pro-inflammatory cytokine secretion from ATII cells (IL-6, IL-8) and macrophages (IL-6, TNFα) at 6 h post-infection compared to BM (p < 0.05). Interestingly, BM-induced the anti-inflammatory cytokine, IL-10, in ATII cells and macrophages at 6 h post-infection, with delayed induction of inflammatory cytokines at 24 h post-infection. Because BP is flagellated and produces LPS, we confirmed that it stimulated both Toll-like receptor (TLR) 4 and TLR5 via NF-κb activation while the non-flagellated BM stimulated only TLR4. These data show the differences in BP and BM pathogenicity in the lung when infecting human ATII cells and macrophages and demonstrate the ability of these pathogens to elicit distinct immune responses from resident lung cells which may open new targets for therapeutic intervention to fight against these pathogens.

Alveolar epithelial cells are critical in protection of the respiratory tract by secretion of factors able to modulate the activity of pulmonary macrophages and directly control bacterial growth

The respiratory epithelium is a physical and functional barrier actively involved in the clearance of environmental agents. The alveolar compartment is lined with membranous pneumocytes, known as type I alveolar epithelial cells (AEC I), and granular pneumocytes, type II alveolar epithelial cells (AEC II). AEC II are responsible for epithelial reparation upon injury and ion transport and are very active immunologically, contributing to lung defense by secreting antimicrobial factors. AEC II also secrete a broad variety of factors, such as cytokines and chemokines, involved in activation and differentiation of immune cells and are able to present antigen to specific T cells. Another cell type important in lung defense is the pulmonary macrophage (PuM). Considering the architecture of the alveoli, a good communication between the external and the internal compartments is crucial to mount effective responses. Our hypothesis is that being in the interface, AEC may play an important role in transmitting signals from the external to the internal compartment and in modulating the activity of PuM. For this, we collected supernatants from AEC unstimulated or stimulated in vitro with lipopolysaccharide (LPS). These AEC-conditioned media were used in various setups to test for the effects on a number of macrophage functions: (i) migration, (ii) phagocytosis and intracellular control of bacterial growth, and (iii) phenotypic changes and morphology. Finally, we tested the direct effect of AEC-conditioned media on bacterial growth. We found that AEC-secreted factors had a dual effect, on one hand controlling bacterial growth and on the other hand increasing macrophage activity.

Understanding delayed T-cell priming, lung recruitment, and airway luminal T-cell responses in host defense against pulmonary tuberculosis

Mycobacterium tuberculosis (M.tb), the causative bacterium of pulmonary tuberculosis (TB), is a serious global health concern. Central to M.tb effective immune avoidance is its ability to modulate the early innate inflammatory response and prevent the establishment of adaptive T-cell immunity for nearly three weeks. When compared with other intracellular bacterial lung pathogens, such as Legionella pneumophila, or even closely related mycobacterial species such as M. smegmatis, this delay is astonishing. Customarily, the alveolar macrophage (AM) acts as a sentinel, detecting and alerting surrounding cells to the presence of an invader. However, in the case of M.tb, this may be impaired, thus delaying the recruitment of antigen-presenting cells (APCs) to the lung. Upon uptake by APC populations, M.tb is able to subvert and delay the processing of antigen, MHC class II loading, and the priming of effector T cell populations. This delay ultimately results in the deferred recruitment of effector T cells to not only the lung interstitium but also the airway lumen. Therefore, it is of upmost importance to dissect the mechanisms that contribute to the delayed onset of immune responses following M.tb infection. Such knowledge will help design the most effective vaccination strategies against pulmonary TB.

CXCR4 regulates migration of lung alveolar epithelial cells through activation of Rac1 and matrix metalloproteinase-2

Restoration of the epithelial barrier following acute lung injury is critical for recovery of lung homeostasis. After injury, alveolar type II epithelial (ATII) cells spread and migrate to cover the denuded surface and, eventually, proliferate and differentiate into type I cells. The chemokine CXCL12, also known as stromal cell-derived factor 1α, has well-recognized roles in organogenesis, hematopoiesis, and immune responses through its binding to the chemokine receptor CXCR4. While CXCL12/CXCR4 signaling is known to be important in immune cell migration, the role of this chemokine-receptor interaction has not been studied in alveolar epithelial repair mechanisms. In this study, we demonstrated that secretion of CXCL12 was increased in the bronchoalveolar lavage of rats ventilated with an injurious tidal volume (25 ml/kg). We also found that CXCL12 secretion was increased by primary rat ATII cells and a mouse alveolar epithelial (MLE12) cell line following scratch wounding and that both types of cells express CXCR4. CXCL12 significantly increased ATII cell migration in a scratch-wound assay. When we treated cells with a specific antagonist for CXCR4, AMD-3100, cell migration was significantly inhibited. Knockdown of CXCR4 by short hairpin RNA (shRNA) caused decreased cell migration compared with cells expressing a nonspecific shRNA. Treatment with AMD-3100 decreased matrix metalloproteinase-14 expression, increased tissue inhibitor of metalloproteinase-3 expression, decreased matrix metalloproteinase-2 activity, and prevented CXCL12-induced Rac1 activation. Similar results were obtained with shRNA knockdown of CXCR4. These findings may help identify a therapeutic target for augmenting epithelial repair following acute lung injury.

Tumor-cell co-culture induced alternative activation of macrophages is modulated by interferons in vitro

Tumor-associated macrophages infiltrate tumors and facilitate tumor growth. Here, we analyzed M1 and M2 marker expression in the course of co-culture-driven macrophage differentiation and investigated the influence of interferons (IFNs) on this differentiation. To generate monocyte-derived macrophages (MDMs) 1×10⁶ monocytes of healthy volunteers were cultivated either with 25×10³ adherent A549/mL or in medium containing 50% A549 conditioned medium (CM) for 72 h in the presence or absence of IFN-α, β or γ, respectively. Supernatants were tested for CCL18 (M2 marker) and CXCL10 (M1 marker) by enzyme-linked immunosorbent assay. CCL18 and CXCL10 release by MDM is increased by the presence of A549 cells, but also when cultured in A549 CM. On stimulation with IFN-γ, we observe an increased release of the M1 marker CXCL10 and a decreased release of CCL18. Type I IFNs also increases CXCL10 release. Thus, A549 releases a soluble factor which enhances CCL18 production and M2 polarization, indicating that a localized specific cytokine milieu, as found in the environment of a tumor or in fibrotic lung tissue, favors alternative activation of macrophages. In the presence of IFN-γ, M2 differentiation is attenuated as shown by the decrease of the M2 chemokine CCL18 and by the increase of the M1 chemokine CXCL10. However, CXCL10 levels were also increased by the co-culture, which indicates a simultaneous classical activation (M1) or the formation of a M1/M2 hybrid.

CCL26-targeted siRNA treatment of alveolar type II cells decreases expression of CCR3-binding chemokines and reduces eosinophil migration: implications in asthma therapy

The underlying inflammation present in chronic airway diseases is orchestrated by increased expression of CC chemokines that selectively recruit leukocyte populations into the pulmonary system. Human CCL26 signals through CC chemokine receptor 3 (CCR3), is dramatically upregulated in challenged asthmatics, and stimulates recruitment of eosinophils (EOSs) and other leukocytes. CCL26 participates in regulation of its receptor CCR3 and modulates expression of a variety of chemokines in alveolar type II cells. Utilizing the A549 alveolar type II epithelial cell culture model, we carried out studies to test the hypothesis that CCL26-siRNA treatment of these cells would ameliorate Th2-driven release of the eotaxins and other CCR3 ligands that would, in turn, decrease recruitment and activation of EOSs. Results demonstrate that CCL26-siRNA treatments decreased interleukin-4-induced CCL26 and CCL24 expression by >70%. CCL26-directed small-interfering RNA (siRNA) treatments significantly decreased release of CCL5 (RANTES), CCL15 (MIP-1δ), CCL8 (MCP-2), and CCL13 (MCP-4). In bioactivity assays it was shown that EOS migration and activation were reduced up to 80% and 90%, respectively, when exposed to supernatants of CCL26-siRNA-treated cells. These results provide evidence that CCL26 may be an appropriate target for development of new therapeutic agents designed to alleviate the underlying inflammation associated with chronic diseases of the airways.

Generation and evaluation of a monoclonal antibody, designated MAdL, as a new specific marker for adenocarcinomas of the lung

Background:

Different therapy regimens in non-small-cell lung cancer (NSCLC) are of rising clinical importance, and therefore a clear-cut subdifferentiation is mandatory. The common immunohistochemical markers available today are well applicable for subdifferentiation, but a fraction of indistinct cases still remains, demanding upgrades of the panel by new markers.

Methods:

We report here the generation and evaluation of a new monoclonal antibody carrying the MAdL designation, which was raised against primary isolated human alveolar epithelial cells type 2.

Results:

Upon screening, one clone (MAdL) was identified as a marker for alveolar epithelial cell type II, alveolar macrophages and adenocarcinomas of the lung. In a large-scale study, this antibody, with an optimised staining procedure for formalin-fixed tissues, was then evaluated together with the established markers thyroid transcription factor-1, surfactant protein-A, pro-surfactant protein-B and napsin A in a series of 362 lung cancer specimens. The MAdL displays a high specificity (>99%) for adenocarcinomas of the lung, together with a sensitivity of 76.5%, and is capable of delivering independent additional diagnostic information to the established markers.

Conclusion:

We conclude that MAdL is a new specific marker for adenocarcinomas of the lung, which helps to clarify subdifferentiation in a considerable portion of NSCLCs.

Innate immunity in the respiratory epithelium

The airway epithelium represents the first point of contact for inhaled foreign organisms. The protective arsenal of the airway epithelium is provided in the form of physical barriers and a vast array of receptors and antimicrobial compounds that constitute the innate immune system. Many of the known innate immune receptors, including the Toll-like receptors and nucleotide oligomerization domain-like receptors, are expressed by the airway epithelium, which leads to the production of proinflammatory cytokines and chemokines that affect microorganisms directly and recruit immune cells, such as neutrophils and T cells, to the site of infection. The airway epithelium also produces a number of resident antimicrobial proteins, such as lysozyme, lactoferrin, and mucins, as well as a swathe of cationic proteins. Dysregulation of the airway epithelial innate immune system is associated with a number of medical conditions that can result in compromised immunity and chronic inflammation of the lung. This review focuses on the innate immune capabilities of the airway epithelium and its role in protecting the lung from infection as well as the outcomes when its function is compromised.

Human lung innate immune cytokine response to adenovirus type 7

Adenovirus (Ad) type 7 can cause severe infection, including pneumonia, in military recruits and children. The initial inflammation is a neutrophilic interstitial infiltration with neutrophilic alveolitis. Subsequently, monocytes become evident and, finally, there is a predominantly lymphocytic infiltrate. We have established that Ad7 infection of epithelial cells stimulates release of the neutrophil chemotaxin interleukin (IL)-8, and have extended these studies to a human lung tissue model. Here, we studied cytokine responses to Ad7 in human alveolar macrophages (HAM) and our human lung tissue model. Both ELISA and RNase-protection assay (RPA) data demonstrated that, upon Ad7 infection, IP-10 and MIP-1alpha/beta are released from HAM. IP-10 and MIP-1alpha/beta protein levels were induced 2- and 3-fold, respectively, in HAM 24 h after Ad7 infection. We then investigated induction of specific cytokines in human lung tissue by RPA and ELISA. The results showed that IL-8 and IL-6 were induced 8 h after infection and, by 24 h, levels of IL-8, IL-6, MIP-1alpha/beta and MCP-1 were all increased. IP-10, a monocyte and lymphocyte chemokine, was also induced 30-fold, but only 24 h after infection. Immunohistochemistry staining confirmed that IL-8 was only released from the epithelial cells of lung slices and not from macrophages. IP-10 was secreted from both macrophages and epithelial cells. Moreover, full induction of IP-10 is likely to require participation and cooperation of both epithelial cells and macrophages in intact lung. Understanding the cytokine and chemokine induction during Ad7 infection may lead to novel ways to modulate the response to this pathogen.

Pulmonary epithelium is a prominent source of proteinase-activated receptor-1-inducible CCL2 in pulmonary fibrosis

RATIONALE

Studies in patients and experimental animals provide compelling evidence of the involvement of the major thrombin receptor, proteinase-activated receptor-1 (PAR(1)), and the potent chemokine, chemokine (CC motif) ligand-2 (CCL2)/monocyte chemotactic protein-1, in the pathogenesis of idiopathic pulmonary fibrosis (IPF). PAR(1) knockout mice are protected from bleomycin-induced lung inflammation and fibrosis and this protection is associated with marked attenuation in CCL2 induction.

OBJECTIVES

The aim of this study was to determine which cell types represent the major source of PAR(1)-inducible CCL2 in the fibrotic lung.

METHODS

Using immunohistochemistry and dual immunofluorescence, we examined PAR(1) and CCL2 expression in the bleomycin model and human IPF lung. PAR(1) and CCL2 gene expression was also assessed in laser-captured alveolar septae from patients with IPF. The ability of PAR(1) to induce CCL2 production by lung epithelial cells was also examined in vitro.

MEASUREMENTS AND MAIN RESULTS

We report for the first time that PAR(1) and CCL2 are coexpressed and co-up-regulated on the activated epithelium in fibrotic areas in IPF. Similar observations were found in bleomycin-induced lung injury. Furthermore, we show that thrombin is a potent inducer of CCL2 gene expression and protein release by cultured lung epithelial cells via a PAR(1)-dependent mechanism.

CONCLUSIONS

These data support the notion that PAR(1) activation on lung epithelial cells may represent an important mechanism leading to increased local CCL2 release in pulmonary fibrosis. Targeting PAR(1) on the pulmonary epithelium may offer a unique opportunity for therapeutic intervention in pulmonary fibrosis and other inflammatory and fibroproliferative conditions associated with excessive local generation of thrombin and CCL2 release.

Human type II pneumocyte chemotactic responses to CXCR3 activation are mediated by splice variant A

Chemokine receptors control several fundamental cellular processes in both hematopoietic and structural cells, including directed cell movement, i.e., chemotaxis, cell differentiation, and proliferation. We have previously demonstrated that CXCR3, the chemokine receptor expressed by Th1/Tc1 inflammatory cells present in the lung, is also expressed by human airway epithelial cells. In airway epithelial cells, activation of CXCR3 induces airway epithelial cell movement and proliferation, processes that underlie lung repair. The present study examined the expression and function of CXCR3 in human alveolar type II pneumocytes, whose destruction causes emphysema. CXCR3 was present in human fetal and adult type II pneumocytes as assessed by immunocytochemistry, immunohistochemistry, and Western blotting. CXCR3-A and -B splice variant mRNA was present constitutively in cultured type II cells, but levels of CXCR3-B greatly exceeded CXCR3-A mRNA. In cultured type II cells, I-TAC, IP-10, and Mig induced chemotaxis. Overexpression of CXCR3-A in the A549 pneumocyte cell line produced robust chemotactic responses to I-TAC and IP-10. In contrast, I-TAC did not induce chemotactic responses in CXCR3-B and mock-transfected cells. Finally, I-TAC increased cytosolic Ca2+ and activated the extracellular signal-regulated kinase, p38, and phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B kinases only in CXCR3-A-transfected cells. These data indicate that the CXCR3 receptor is expressed by human type II pneumocytes, and the CXCR3-A splice variant mediates chemotactic responses possibly through Ca2+ activation of both mitogen-activated protein kinase and PI 3-kinase signaling pathways. Expression of CXCR3 in alveolar epithelial cells may be important in pneumocyte repair from injury.

Expression of interferon-gamma- inducible protein-10 and its receptor CXCR3 in chronic pancreatitis

AIM

The role of CXC chemokine, interferon-gamma-inducible protein-10 and its receptor CXCR3 in pathophysiology of chronic pancreatitis (CP) is not very clear. Hence, this study was carried out to analyze the expression of CXCL10 and CXCR3 in CP tissues.

METHODS

Pancreatic tissues from 25 histopathologically graded CP cases (11 alcohol associated CP, 5 confirmed idiopathic and 9 of undefined nature) and 10 normal cases were studied. Tissues were subjected to real-time PCR, immunohistochemistry, and Western blot analysis for CXCL10 and CXCR3 expression.

RESULTS

Real-time (RT)-PCR revealed increased expression of CXCL10 (13-fold) and CXCR3 (7-fold) in CP tissue. The immunohistochemistry and Western blot analysis of the same showed significant increased protein expression and correlated well with the histopathological grades. The CXCL10 was localized mainly in the cytoplasm of pancreatic acinar cells and expression increased from grade I to grade II and declined in grade III while no expression was recorded in normal. The CXCR3 was expressed strongly at the acinar cell membrane in CP as compared to normal. Further, comparative analysis by semiquantitative RT-PCR analysis was performed for other CXC/CC chemokines (CXCL9, CXCL11, CCL3, CCL4, CCL5) and receptor (CCR5) which revealed their upregulation in the diseased state.

CONCLUSION

The existence of CXCL10 and CXCR3 with other CXC/CC chemokine signature in CP is suggestive of their vital role in the progression of chronic inflammation.

Role of primary human alveolar epithelial cells in host defense against Francisella tularensis infection

Francisella tularensis, an intracellular pathogen, is highly virulent when inhaled. Alveolar epithelial type I (ATI) and type II (ATII) cells line the majority of the alveolar surface and respond to inhaled pathogenic bacteria via cytokine secretion. We hypothesized that these cells contribute to the lung innate immune response to F. tularensis. Results demonstrated that the live vaccine strain (LVS) contacted ATI and ATII cells by 2 h following intranasal inoculation of mice. In culture, primary human ATI or ATII cells, grown on transwell filters, were stimulated on the apical (AP) surface with virulent F. tularensis Schu 4 or LVS. Basolateral (BL) conditioned medium (CM), collected 6 and 24 h later, was added to the BL surfaces of transwell cultures of primary human pulmonary microvasculature endothelial cells (HPMEC) prior to the addition of polymorphonuclear leukocytes (PMNs) or dendritic cells (DCs) to the AP surface. HPMEC responded to S4- or LVS-stimulated ATII, but not ATI, CM as evidenced by PMN and DC migration. Analysis of the AP and BL ATII CM revealed that both F. tularensis strains induced various levels of a variety of cytokines via NF-kappaB activation. ATII cells pretreated with an NF-kappaB inhibitor prior to F. tularensis stimulation substantially decreased interleukin-8 secretion, which did not occur through Toll-like receptor 2, 2/6, 4, or 5 stimulation. These data indicate a crucial role for ATII cells in the innate immune response to F. tularensis.

Modulation of endotoxin-induced neutrophil transendothelial migration by alveolar epithelium in a defined bilayer model

Within the alveolus, epithelial cells, due to their close association with endothelial cells, can potentially influence endothelial cell responsiveness during inflammation and their interaction with leukocytes. To investigate this, three lung epithelial cell lines (A549, Calu-3, or NCI-H441) were grown with endothelium on opposing surfaces of Transwell filters and the formation and stability of bilayers was rigorously evaluated. All epithelial lines disrupted endothelial monolayer formation on filters with 3- or 5-microm pores by breaching the filter, and this occurred regardless of seeding density, matrix composition, or duration of culture. Endothelial disruption was not detectable by electrical resistance or permeability measurements but required cell-specific staining with immunofluorescence and microscopy. Distinct bilayers formed only on filters with 0.4-microm pores and only with A549 cells and human umbilical vein endothelial cells. Endotoxin (lipopolysaccharide [LPS]) stimulation of bilayers (4 hours) enhanced neutrophil transendothelial migration, but this was significantly decreased compared with the response of endothelium grown alone, irrespective of whether LPS exposure was via the epithelial or endothelial side of the bilayer. Down-modulation required epithelial-endothelial approximation and was not seen when these cells were separated by 0.5 to 1 mm. This study defines optimal conditions required for generation of intact bilayers of lung epithelial cells with endothelium for the study of leukocyte-transendothelial migration. Furthermore, it was demonstrated that lung epithelial cells can modulate endothelial cell responsiveness to an environmental inflammatory stimulus such as LPS and thus may have an important role in minimizing excessive and deleterious neutrophilic inflammation in the lung alveolus.

Expression of JP-8–Induced Inflammatory Genes in AEII Cells Is Mediated by NF-κB and PARP-1

Lung epithelial cells are critical in the regulation of airway inflammation in response to environmental pollutants. Altered activation of NF-kappaB is associated with expression of several proinflammatory factors in respiratory epithelial cells in response to an insult. Here we show that a low threshold dose (8 microg/ml) of the jet fuel JP-8 induces in a rat alveolar epithelial cell line (RLE-6TN) a prolonged activation of NF-kappaB as well as the increased expression of the proinflammatory cytokines TNF-alpha and IL-8, which are regulated by NF-kappaB. The up-regulation of IL-6 mRNA in cells exposed to JP-8 appears to be a reaction of RLE-6TN cells to reduce the enhancement of proinflammatory mediators in response to the fuel. Moreover, lung tissues from rats exposed to occupational levels of JP-8 by nasal aerosol also showed dysregulated expression of TNF-alpha, IL-8, and IL-6, confirming the in vitro data. The poly(ADP-ribosyl)ation of PARP-1, a coactivator of NF-kappaB, was coincident with the prolonged activation of NF-kappaB during JP-8 treatment. These results evidenced that a persistent exposure of the airway epithelium to aromatic hydrocarbons may have deleterious effects on pulmonary function.