Eotaxin represents the principal eosinophil chemoattractant in a novel murine asthma model induced by house dust containing cockroach allergens

HYDROCORTISONE, ASCORBIC ACID, AND THIAMINE THERAPY DECREASE RENAL OXIDATIVE STRESS AND ACUTE KIDNEY INJURY IN MURINE SEPSIS

ABSTRACT

Background: Acute kidney injury (AKI) occurs frequently in septic patients and correlates with increased mortality. Because clinical studies investigating hydrocortisone, ascorbic acid, and thiamine (HAT) have demonstrated discordant results, studies were performed using mortality stratification for therapy to identify candidates for therapy and determine mechanisms of organ injury. Methods: Sepsis was induced using the cecal ligation and puncture (CLP) model of sepsis with fluid and antibiotic support. Heart rate (HR) measurements obtained 6 hours after CLP stratified mice into live predicted (P-Live) or die predicted (P-Die). Stratified mice were then randomized for treatment with HAT or vehicle given 7 hours after CLP. Physiologic measurements were taken again at 24 hours, and mice were killed to collect blood and organs. Results: The following five groups were created: (1) P-Live vehicle, (2) P-Live HAT, (3) P-Die vehicle, (4) P-Die HAT, and (5) naive mice. Comparisons were made to test the hypotheses that (1) P-Die vehicle mice will have significant deterioration compared with P-Live mice targeting the kidney and (2) HAT will correct these deleterious changes in P-Die mice. Compared with P-Live, P-Die mice had a significant decline in all measured physiologic parameters (HR, cardiac output, breath rate, and temperature), which were corrected with HAT therapy (P < 0.05 for all parameters). The P-Die mice had declines in the ascorbic acid within the blood, peritoneal lavage, and kidney homogenate compared with P-Live mice indicating consumption, and the decline was corrected with HAT. Elevated IL-6, KC, Macrophage Inflammatory Protein-2, and IL-1RA were found in P-Die mice and decreased with HAT. Markers of endothelial cell injury (glypican 1 and glypican 4) were elevated in the P-Die mice, and these values were decreased with HAT therapy. Low oxygen levels with subsequent oxidative stress (OS) in the kidney were visualized in histologic sections using hypoxyprobe and also with carbonyl proteins and 8-iso-prostaglandin F2α in kidney homogenates. The P-Die mice had significant elevations of renal OSs, which was ameliorated with HAT. Kidney injury was evident in the P-Die mice compared with P-Live mice with elevations in blood urea nitrogen and cystatin C, which were significantly reduced with HAT. There was no evidence of global hypoxia or organ injury because hepatic parameters remained normal. Conclusions: Our data show that in CLP-induced sepsis, P-Die mice have increased inflammation, OS, and kidney injury. Hydrocortisone, ascorbic acid, and thiamine therapy decreased renal OS and injury in the P-Die group when given after the onset of sepsis-induced physiologic changes.

The Role of Macrophages in the Development of Acute and Chronic Inflammatory Lung Diseases

Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

IL-37 relieves allergic inflammation by inhibiting the CCL11 signaling pathway in a mouse model of allergic rhinitis

Allergic rhinitis (AR) is the allergic inflammation of immune cells in the nasal mucosa, caused by an abnormal T-cell response. Interleukin (IL)-37, a unique member of the IL-1 family with broad anti-inflammatory roles in various autoimmune diseases, participates in the immune regulation of AR. However, the regulatory mechanism of IL-37 in AR has remained elusive. In the present study, a mouse model of AR was established by treating mice with ovalbumin (OVA). Following systemic administration of IL-37, the effects of the cytokine on allergic symptoms were evaluated. The nasal mucosal infiltration of eosinophils was assessed by histopathological observation. The serum and nasal lavage fluid concentrations of immunoglobulin (Ig)E, IgG1, IgG2a, interferon (IFN)-γ, IL-4, IL-13, IL-17a and C-C motif cytokine ligand (CCL)11 were determined by ELISA. Treatment with OVA resulted in allergic symptoms, including enhanced eosinophil infiltration in the nasal mucosa, increased thickness of the nasal mucosa and increased levels of IgE, IgG1, IgG2a, IL-4, IL-13, IL-17a and CCL11, but the level of IFN-γ was indicated to decrease. After IL-37 treatment, the frequency of nasal rubbing and sneezing was reduced compared with that in the OVA group. IL-37 administration also decreased the number of eosinophils in the nasal mucosa and the thickness of the nasal mucosa, as well as the serum and nasal lavage fluid levels of IgE, IgG1, IgG2a, IL-4, IL-13, IL-17a and CCL11, but the level of IFN-γ decreased. In addition, the OVA-induced increases in histamine and substance P levels were reversed by IL-37 administration. CCL11 expression levels were correlated with the expression levels of IFN-γ, IL-4, IL-13, IL-17a, histamine and substance P. In conclusion, IL-37 alleviated the OVA-induced allergic symptoms and allergic inflammatory response by reducing the serum cytokine levels via decreasing CCL11 expression levels in mice.

IL-37 inhibits IL-4/IL-13-induced CCL11 production and lung eosinophilia in murine allergic asthma

BACKGROUND

IL-37 is emerging as an anti-inflammatory cytokine, particularly in innate inflammation. However, the role of IL-37 in Th2-mediated allergic lung inflammation remains uncertain. We sought to determine the role and the underlying mechanisms of IL-37 in the development of house dust mites (HDM)-induced murine asthma model.

METHODS

We examined the effect of IL-37 administration during the sensitization or challenge phase on Th2-mediated allergic asthma induced by inhaled HDM. Cellular source of CCL11 and distribution of IL-37 receptors, IL-18Rα and IL-1R8, were determined in HDM-exposed lungs. Finally, we examined the effect of IL-37 on CCL11 production and STAT6 activation in different primary lung structural cell types upon IL-4/IL-13 stimulation.

RESULTS

IL-37 had no effect on HDM sensitization, but when administrated during the challenge phase, significantly attenuated pulmonary eosinophilia, CCL11 production, and airway hyper-reactivity (AHR). Interestingly, IL-37 treatment had no significant effects on lung infiltrating T cells and Th2 cytokine production. Intranasal co-administration of CCL11 reversed the inhibiting effect of IL-37 on HDM-induced pulmonary eosinophilia and AHR. Furthermore, we demonstrated that CCL11 was primarily expressed by fibroblasts and airway smooth muscle cells (AMSC), while IL-37 receptors by tracheobronchial epithelial cells (TEC). In vitro study showed that IL-37 inhibited IL-4/IL-13-induced STAT6 activation and CCL11 production by fibroblasts and AMSC, which was dependent on its direct action on TEC. Moreover, cell contact was required for the inhibitory effect of IL-37-treated TEC.

CONCLUSIONS

IL-37 attenuates HDM-induced asthma, possibly by inhibiting IL-4/IL-13-induced CCL11 production by fibroblasts and AMSC via its direct act on TEC.

Sputum cytology during late-phase responses to inhalation challenge with different allergens

BACKGROUND

In mouse models of allergic asthma, exposure to different allergens can trigger distinct inflammatory subtypes in the airways. We investigated whether this observation extends to humans.

METHODS

We compared the frequency of sputum inflammatory subtypes between mild allergic asthma subjects (n = 129) exposed to different allergens in inhalation challenge tests. These tests were performed using a standardized protocol as part of clinical trials of experimental treatments for asthma, prior to drug randomization. Five allergen types were represented: the house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae, ragweed, grass, and cat.

RESULTS

Of 118 individuals with a sputum sample collected before allergen challenge (baseline), 45 (38%) had paucigranulocytic, 51 (43%) eosinophilic, 11 (9%) neutrophilic, and 11 (9%) mixed granulocytic sputum. Of note, most individuals with baseline paucigranulocytic sputum developed eosinophilic (48%) or mixed granulocytic (43%) sputum 7 hours after allergen challenge, highlighting the dynamic nature of sputum inflammatory subtype in asthma. Overall, there was no difference in the frequency of sputum inflammatory subtypes following challenge with different allergen types. Similar results were observed at 24 hours after allergen challenge.

CONCLUSIONS

Unlike reported in mice, in humans the sputum inflammatory subtype observed after an allergen-induced asthma exacerbation is unlikely to be influenced by the type of allergen used.

A 4-Week Model of House Dust Mite (HDM) Induced Allergic Airways Inflammation with Airway Remodeling

Animal models of allergic airways inflammation are useful tools in studying the pathogenesis of asthma and potential therapeutic interventions. The different allergic airways inflammation models available to date employ varying doses, frequency, duration and types of allergen, which lead to the development of different features of asthma; showing varying degrees of airways inflammation and hyper-responsiveness (AHR) and airways remodeling. Models that also exhibit airway remodeling, a key feature of asthma, in addition to AHR and airway inflammation typically require 5–12 weeks to develop. In this report, we describe a 4-week mouse model of house dust mite (HDM)-induced allergic airways inflammation, and compare the phenotypic features of two different doses of HDM exposures (10 µg and 25 µg) for 5 days/week with a well-characterized 8-week chronic HDM model. We found that 4 weeks of intranasal HDM (25 µg in 35 µl saline; 5 days/week) resulted in AHR, airway inflammation and airway remodeling that were comparable to the 8-week model. We conclude that this new 4-week HDM model is another useful tool in studies of human asthma that offers advantages of shorter duration for development and decreased costs when compared to other models that require longer durations of exposure (5–12 weeks) to develop.

The Role of Substance P in Pulmonary Clearance of Bacteria in Comparative Injury Models

Neural input to the immune system can alter its ability to clear pathogens effectively. Patients suffering mild traumatic brain injury (mTBI) have shown reduced rates of pneumonia and a murine model replicated these findings, with better overall survival of TBI mice compared with sham-injured mice. To further investigate the mechanism of improved host response in TBI mice, this study developed and characterized a mild tail trauma model of similar severity to mild TBI. Both mild tail trauma and TBI induced similar systemic changes that normalized within 48 hours, including release of substance P. Examination of tissues showed that injuries are limited to the target tissue (ie, tail in tail trauma, brain in mTBI). Pneumonia challenge showed that mild TBI mice showed improved immune responses, characterized by the following: i) increased survival, ii) increased pulmonary neutrophil recruitment, iii) increased bacterial clearance, and iv) increased phagocytic cell killing of bacteria compared with tail trauma. Administration of a neurokinin-1-receptor antagonist to block substance P signaling eliminated the improved survival of mTBI mice. Neurokinin-1-receptor antagonism did not alter pneumonia mortality in tail trauma mice. These data show that immune benefits of trauma are specific to mTBI and that tail trauma is an appropriate control for future studies aimed at elucidating the mechanisms of improved innate immune responses in mTBI mice.

CCR9 Is a Key Regulator of Early Phases of Allergic Airway Inflammation

Airway inflammation is the most common hallmark of allergic asthma. Chemokine receptors involved in leukocyte recruitment are closely related to the pathology in asthma. CCR9 has been described as a homeostatic and inflammatory chemokine receptor, but its role and that of its ligand CCL25 during lung inflammation remain unknown. To investigate the role of CCR9 as a modulator of airway inflammation, we established an OVA-induced allergic inflammation model in CCR9-deficient mice. Here, we report the expression of CCR9 and CCL25 as early as 6 hours post-OVA challenge in eosinophils and T-lymphocytes. Moreover, in challenged CCR9-deficient mice, cell recruitment was impaired at peribronchial and perivenular levels. OVA-administration in CCR9-deficient mice leads to a less inflammatory cell recruitment, which modifies the expression of IL-10, CCL11, and CCL25 at 24 hours after OVA challenge. In contrast, the secretion of IL-4 and IL-5 was not affected in CCR9-deficient mice compared to WT mice. These results demonstrate for the first time that CCR9 and CCL25 expressions are induced in the early stages of airway inflammation and they have an important role modulating eosinophils and lymphocytes recruitment at the first stages of inflammatory process, suggesting that they might be a potential target to regulate inflammation in asthma.

Alcohol and inflammatory responses: Highlights of the 2015 Alcohol and Immunology Research Interest Group (AIRIG) meeting

On September 27, 2015 the 20th annual Alcohol and Immunology Research Interest Group (AIRIG) meeting was held as a satellite symposium at the annual meeting of the Society for Leukocyte Biology in Raleigh, NC. The 2015 meeting focused broadly on adverse effects of alcohol and alcohol-use disorders in multiple organ systems. Divided into two plenary sessions, AIRIG opened with the topic of pulmonary inflammation as a result of alcohol consumption, which was followed by alcohol's effect on multiple organs, including the brain and liver. With presentations showing the diverse range of underlying pathology and mechanisms associated with multiple organs as a result of alcohol consumption, AIRIG emphasized the importance of continued alcohol research, as its detrimental consequences are not limited to one or even two organs, but rather extend to the entire host as a whole.

Animal models of allergic airways disease: where are we and where to next?

In a complex inflammatory airways disease such as asthma, abnormalities in a plethora of molecular and cellular pathways ultimately culminate in characteristic impairments in respiratory function. The ability to study disease pathophysiology in the setting of a functioning immune and respiratory system therefore makes mouse models an invaluable tool in translational research. Despite the vast understanding of inflammatory airways diseases gained from mouse models to date, concern over the validity of mouse models continues to grow. Therefore the aim of this review is twofold; firstly, to evaluate mouse models of asthma in light of current clinical definitions, and secondly, to provide a framework by which mouse models can be continually refined so that they continue to stand at the forefront of translational science. Indeed, it is in viewing mouse models as a continual work in progress that we will be able to target our research to those patient populations in whom current therapies are insufficient.

Lung-derived SSEA-1(+) stem/progenitor cells inhibit allergic airway inflammation in mice

BACKGROUND

Asthma is characterized by chronic airway inflammation and airway hyperresponsiveness (AHR). Little is known about the role of pulmonary stem/progenitor cells (PSCs) in allergic airway inflammation.

METHODS

To identify and investigate the role of PSCs in the bronchial epithelium of neonatal mice, we developed an enzyme-based digestion method to obtain single-cell suspension from lung tissues. Characterization of PSCs was performed using flow cytometry, real-time PCR, immunofluorescence staining, confocal microscopy, and scanning electron microscopy. The effects of SSEA-1(+) (stage-specific embryonic antigen-1) PSCs was studied in an in vivo model of ovalbumin-induced allergic inflammation and an in vitro model of cell-based regulation using flow cytometry, real-time PCR, and immune-blotting.

RESULTS

Single-cell suspensions derived from neonatal lung tissue included populations that expressed either SSEA-1(+) or Sca-1(+) (stem cell antigen-1). The SSEA-1(+) PSCs were highly prevalent in neonatal mice, and they were rare in adult mice. Enriched neonatal SSEA-1(+) PSCs had the ability of self-renewal and differentiated into pneumocytes and tracheal epithelial cells. SSEA-1(+) PSCs reduced AHR and airway damage in asthmatic mice by decreasing eosinophil infiltration, inhibiting chemokines/cytokines production, and preserving the level of CCSP.

CONCLUSIONS

Here, we demonstrated that neonatal SSEA-1(+) PSCs play an immunomodulatory role in the progression of asthma by reducing lung damage and inhibiting inflammatory responses. Further understanding the molecular mechanisms of neonatal SSEA-1(+) PSCs might shed light on exploring the novel therapeutic approaches for allergic airway inflammation.

Neutrophil-mediated phagocytic host defense defect in myeloid Cftr-inactivated mice

Cystic fibrosis (CF) is a common and deadly inherited disease, caused by mutations in the CFTR gene that encodes a cAMP-activated chloride channel. One outstanding manifestation of the disease is the persistent bacterial infection and inflammation in the lung, which claims over 90% of CF mortality. It has been debated whether neutrophil-mediated phagocytic innate immunity has any intrinsic defect that contributes to the host lung defense failure. Here we compared phagosomal CFTR targeting, hypochlorous acid (HOCl) production, and microbial killing of the neutrophils from myeloid Cftr-inactivated (Myeloid-Cftr-/-) mice and the non-inactivated control (Cftrfl10) mice. We found that the mutant CFTR that lacked Exon-10 failed to target to the neutrophil phagosomes. This dysfunction resulted in impaired intraphagosomal HOCl production and neutrophil microbial killing. In vivo lung infection with a lethal dose of Pseudomonas aeruginosa caused significantly higher mortality in the myeloid CF mice than in the controls. The myeloid-Cftr-/- lungs were deficient in bacterial clearance, and had sustained neutrophilic inflammation and stalled transition from early to late immunity. These manifestations recapitulated the symptoms of human CF lungs. The data altogether suggest that myeloid CFTR expression is critical to normal host lung defense. CFTR dysfunction in neutrophils compromises the phagocytic innate immunity, which may predispose CF lungs to infection.

Chemokines mediate ethanol-induced exacerbations of murine cockroach allergen asthma

Asthma imposes considerable patient and economic burdens, with the most severe cases causing the greatest affliction. Identifying stimuli that worsen asthma severity is an essential step to controlling both disease morbidity and the lessening economic impact. This study provides the first mechanistic investigation into how acute ethanol exposure will increase asthma severity in a murine model of mild cockroach allergen (CRA)-induced asthma. Outbred mice were sensitized to induce mild allergic asthma, with intratracheal CRA exposures on days 0 and 14. On day 21 mice were gavaged with water or 32% ethanol, and the third allergen exposure was given 30 min post-gavage. Asthmatic responses were measured at several time-points up to 42 h after the third allergen challenge. Ethanol-gavaged mice showed increased asthma severity within 90 min post-allergen challenge, with exacerbations lasting for 24 h. Ethanol caused greater airways obstruction, including an eightfold increase in epithelial cell mucin and increased mucus plugs, resulting in a 50% reduction in bronchiole patency. Ethanol gavage also induced significant increases in airways hyperreactivity. While T helper type 1 (Th1) and Th2 cytokines were not altered by ethanol gavage, pulmonary neutrophil and eosinophil recruitment were augmented. This increase was associated with increased chemokine production. Administration 2 h prior to ethanol gavage of a neutralizing antibody cocktail to keratinocyte-derived chemokine, macrophage inflammatory protein-2, eotaxin-1 and eotaxin-2 prevented ethanol-induced eosinophil recruitment and airways hyperreactivity. These data provide evidence that acute alcohol exposure immediately prior to a mild allergen-triggered asthmatic episode will exacerbate asthma severity mediated by increased production of chemokines.

A2B adenosine receptor expression by myeloid cells is proinflammatory in murine allergic-airway inflammation

Asthma is a chronic condition with high morbidity and healthcare costs, and cockroach allergens are an established cause of urban pediatric asthma. A better understanding of cell types involved in promoting lung inflammation could provide new targets for the treatment of chronic pulmonary disease. Because of its role in regulating myeloid cell-dependent inflammatory processes, we examined A(2B) R expression by myeloid cells in a cockroach allergen model of murine asthma-like pulmonary inflammation. Both systemic and myeloid tissue-specific A(2B) R deletion significantly decreased pulmonary inflammatory cell recruitment, airway mucin production, and proinflammatory cytokine secretion after final allergen challenge in sensitized mice. A(2B) R deficiency resulted in a dramatic reduction on Th2-type airways responses with decreased pulmonary eosinophilia without augmenting neutrophilia, and decreased lung IL-4, IL-5, and IL-13 production. Chemokine analysis demonstrated that eotaxin 1 and 2 secretion in response to repeated allergen challenge is myeloid cell A(2B) R dependent. In contrast, there were no differences in the levels of the CXC chemokines keratinocyte-derived chemokine and MIP-2 in the myeloid cell A(2B) R-deficient mice, strengthening A(2B) R involvement in the development of Th2-type airways inflammation. Proinflammatory TNF-α, IFN-γ, and IL-17 secretion were also reduced in systemic and myeloid tissue-specific A(2B) R deletion mouse lines. Our results demonstrate Th2-type predominance for A(2B) R expression by myeloid cells as a mechanism of development of asthma-like pulmonary inflammation.

Endotoxin is not essential for the development of cockroach induced allergic airway inflammation

PURPOSE

Cockroach (CR) is an important inhalant allergen and can induce allergic asthma. However, the mechanism by which CR induces airway allergic inflammation and the role of endotoxin in CR extract are not clearly understood in regards to the development of airway inflammation. In this study, we evaluated whether endotoxin is essential to the development of CR induced airway allergic inflammation in mice.

MATERIALS AND METHODS

Airway allergic inflammation was induced by intranasal administration of either CR extract, CR with additional endotoxin, or endotoxin depleted CR extract, respectively, in BALB/c wild type mice. CR induced inflammation was also evaluated with toll like receptor-4 (TLR-4) mutant (C3H/HeJ) and wild type (C3H/HeN) mice.

RESULTS

Intranasal administration of CR extracts significantly induced airway hyperresponsiveness (AHR), eosinophilic and neutrophilic airway inflammation, as well as goblet cell hyperplasia in a dose-dependent manner. The addition of endotoxin along with CR allergen attenuated eosinophilic inflammation, interleukin (IL)-13 level, and goblet cell hyperplasia of respiratory epithelium; however, it did not affect the development of AHR. Endotoxin depletion in CR extract did not attenuate eosinophilic inflammation and lymphocytosis in BAL fluid, AHR and IL-13 expression in the lungs compared to CR alone. The attenuation of AHR, eosinophilic inflammation, and goblet cell hyperplasia induced by CR extract alone was not different between TLR-4 mutant and the wild type mice. In addition, heat inactivated CR extract administration induced attenuated AHR and eosinophilic inflammation.

CONCLUSION

Endotoxin in CR extracts may not be essential to the development of airway inflammation.

Pulmonary endotoxin tolerance protects against cockroach allergen-induced asthma-like inflammation in a mouse model

BACKGROUND

Compounds which activate the innate immune system, such as lipopolysaccharide, are significant components of ambient air, and extremely difficult to remove from the environment. It is currently unclear how prior inhalation of endotoxin affects allergen sensitization. We examined whether lung-specific endotoxin tolerance induction prior to sensitization can modulate the response to allergen.

METHODS

Endotoxin tolerance was induced by repeated intratracheal exposure to endotoxin. All mice were then sensitized and challenged by direct intratracheal instillation of cockroach allergen.

RESULTS

After allergen sensitization and challenge, endotoxin tolerant mice had significantly decreased airways hyperresponsiveness to methacholine challenge, which was confirmed by invasive lung function tests. Decreased goblet cell hyperplasia and mucus production were also found by histological assessment. Tolerant mice were protected from airway eosinophilia through the mechanism of reduced CCL11 and CCL24. Interestingly, endotoxin tolerant mice had only a modest reduction in cockroach-specific IgE; however, total IgE was significantly reduced.

CONCLUSIONS

These data show that induction of endotoxin tolerance prior to sensitization protects against the hallmark features of asthma-like inflammation, and that transient modulation of innate immunity can have long-lasting effects on adaptive responses.

Local tissue expression of the cell death ligand, fas ligand, plays a central role in the development of extrapulmonary acute lung injury

Indirect acute lung injury (ALI) is a common manifestation in critically ill patients. Using a model of indirect ALI in mice, our laboratory has shown that local/pulmonary inhibition of extrinsic death receptor protein (Fas) leads to a decrease in lung inflammation and improved survival. However, it is unknown if local, i.e., autocrine/paracrine, inhibition of Fas ligand (FasL) affects Fas-expressing target cells itself or blockade of the actions of a more distal/endocrine source of FasL that accounts for these findings. To examine this, we used a model of indirect ALI in mice (dual insult of hemorrhagic shock followed 24 h later by cecal ligation and puncture, in which animals received FasL small interfering RNA (siRNA) intratracheally (local silencing) or intravenously (systemic/distal delivery) after hemorrhage. After intratracheal delivery of FasL siRNA, there was a significant decrease in inflammatory cytokines, myeloperoxidase activity, and caspase 3 activity in lung tissue along with protein leak as compared with controls. There was no difference found in these various outcome markers between those treated with intravenously administered FasL siRNA versus controls. The observation that local silencing of FasL, as opposed to distal/systemic silencing, ameliorates the effects of indirect ALI suggests not only that FasL produced in an autocrine/paracrine fashion in local tissues has pathological consequences within the lungs, but also that FasL might be a valuable pulmonary therapeutic target.

Interleukin-23-mediated inflammation in Pseudomonas aeruginosa pulmonary infection

Pseudomonas aeruginosa is an opportunistic pathogen that is capable of causing acute and chronic pulmonary infection in the immunocompromised host. In the case of cystic fibrosis (CF), chronic P. aeruginosa infection causes increased mortality by promoting overly exuberant airway inflammation and cumulative lung damage. Identifying the key regulators of this inflammation may lead to the development of new therapies that improve P. aeruginosa-related mortality. We report here that interleukin-23 (IL-23), the cytokine most clearly tied to IL-17-mediated inflammation, also promotes IL-17-independent inflammation during P. aeruginosa pulmonary infection. During the early innate immune response, prior to IL-17 induction, IL-23 acts synergistically with IL-1β to promote early neutrophil (polymorphonuclear leukocyte [PMN]) recruitment. However, at later time points, IL-23 also promoted IL-17 production by lung γδ T cells, which was greatly augmented in the presence of IL-1β. These studies show that IL-23 controls two independent phases of neutrophil recruitment in response to P. aeruginosa infection: early PMN emigration that is IL-17 independent and later PMN emigration regulated by IL-17.

Diesel exhaust particulates exacerbate asthma-like inflammation by increasing CXC chemokines

Particulate matter heavily pollutes the urban atmosphere, and several studies show a link between increased ambient particulate air pollution and exacerbation of pre-existing pulmonary diseases, including asthma. We investigated how diesel exhaust particulates (DEPs) aggravate asthma-like pulmonary inflammation in a mouse model of asthma induced by a house dust extract (HDE) containing cockroach allergens and endotoxin. BALB/c mice were exposed to three pulmonary challenges via hypopharyngeal administration of an HDE collected from the home of an asthmatic child. One hour before each pulmonary challenge, mice were exposed to DEP or PBS. Pulmonary inflammation was assessed by histological features, oxidative stress, respiratory physiological features, inflammatory cell recruitment, and local CXC chemokine production. To prove the role of CXC chemokines in the augmented inflammation, CXC chemokine-specific antibodies were delivered to the lungs before DEP exposure. DEP exacerbated HDE-induced airway inflammation, with increased airway mucus production, oxidative stress, inflammatory cell infiltration, bronchoalveolar lavage concentrations of CXC chemokines, and airway hyperreactivity. Neutralization of airway keratinocyte-derived chemokine and macrophage inflammatory protein-2 significantly improves the respiratory function in addition to decreasing the infiltration of neutrophils and eosinophils. Blocking the chemokines also decreased airway mucus production. These results demonstrate that DEP exacerbates airway inflammation induced by allergen through increased pulmonary expression of the CXC chemokines (keratinocyte-derived chemokine and macrophage inflammatory protein-2).

Herbal medicine treatment reduces inflammation in a murine model of cockroach allergen-induced asthma

BACKGROUND

Asthma is a significant disease among children, and its prevalence has increased notably during the last 2 decades. A traditional Korean medicine, So-Cheong-Ryong-Tang (SCRT), has been used for the treatment of asthma in Asia for centuries, but its mechanism for reducing bronchopulmonary inflammation in asthma has yet to be elucidated.

OBJECTIVE

To investigate whether the herbal extract SCRT inhibits inflammation in a mouse model of cockroach allergen-induced asthma.

METHODS

A house dust extract containing endotoxin and cockroach allergens was used for immunization and 2 additional pulmonary challenges in BALB/c mice. Mice were treated with SCRT or vehicle 1 hour before each pulmonary challenge. Respiratory parameters were evaluated by whole-body plethysmography and forced oscillation methods 24 hours after the last challenge. Bronchoalveolar lavage (BAL) fluid was collected, and histologic sections of lung were prepared either 4 or 24 hours after the last house dust extract challenge.

RESULTS

SCRT treatment significantly reduced the hyperreactivity of the airways as measured by whole-body plethysmography and direct measurement of airway resistance. Inflammation was significantly inhibited by SCRT treatment as demonstrated by reduced plasma IgE levels and improved pulmonary histologic characteristics. SCRT significantly reduced the number of neutrophils in the BAL fluid and also significantly reduced the BAL levels of CXC chemokines, providing a potential mechanism for the reduced inflammation. In a similar fashion, SCRT reduced eosinophil recruitment and BAL levels of eotaxin and RANTES.

CONCLUSION

These data indicate that SCRT treatment alleviates asthma-like pulmonary inflammation via suppression of specific chemokines.

Cockroach induces inflammatory responses through protease-dependent pathways

Exposure to cockroaches is a major risk factor for asthma. Products from cockroaches may contain proteases and ligands for pattern recognition receptors. These molecules may activate airway inflammatory cells, such as eosinophils, that are involved in asthma. Among inner-city children, cockroach allergens play an especially important role in increasing asthma morbidity. The molecular mechanism for this association between cockroach exposure and asthma is not fully understood. Enzymatic activities from cockroaches activate inflammatory cells in the airways and may also exacerbate certain human airway diseases, such as asthma. We recently reported that cockroach extracts contain pepstatin A-sensitive proteases that activate PAR-2 and induce activation and degranulation of human eosinophils. This review focuses on the effects of cockroach on various inflammatory cells, including eosinophils, epithelial cells, fibroblasts, dendritic cells, and T cells, in allergic reactions.

Reducing LPS content in cockroach allergens increases pulmonary cytokine production without increasing inflammation: a randomized laboratory study

Background

Endotoxins are ubiquitously present in the environment and constitute a significant component of ambient air. These substances have been shown to modulate the allergic response, however a consensus has yet to be reached whether they attenuate or exacerbate asthmatic responses. The current investigation examined whether reducing the concentration of lipopolysaccharide (LPS) in a house dust extract (HDE) containing high concentrations of both cockroach allergens [1] and LPS would attenuate asthma-like pulmonary inflammation.

Methods

Mice were sensitized with CRA and challenged with the intact HDE, containing 182 ng of LPS, or an LPS-reduced HDE containing 3 ng LPS, but an equivalent amount of CRA. Multiple parameters of asthma-like pulmonary inflammation were measured.

Results

Compared to HDE challenged mice, the LPS-reduced HDE challenged mice had significantly reduced TNFα levels in the bronchoalveolar lavage fluid. Plasma levels of IgE and IgG1 were significantly reduced, however no change in CRA-specific IgE was detected. In HDE mice, plasma IgG2a levels were similar to naïve mice, while LPS-reduced HDE mice had significantly greater concentrations. Reduced levels of LPS in the HDE did not decrease eosinophil or neutrophil recruitment into the alveolar space. Equivalent inflammatory cell recruitment occurred despite having generally higher pulmonary concentrations of eotaxins and CXC chemokines in the LPS-reduced HDE group. LPS-reduced HDE challenge induced significantly higher concentrations of IFNγ, and IL-5 and IL-13 in the BAL fluid, but did not decrease airways hyperresponsiveness or airway resistance to methacholine challenge. Conclusion: These data show that reduction of LPS levels in the HDE does not significantly protect against the severity of asthma-like pulmonary inflammation.

Detoxified endotoxin vaccine (J5dLPS/OMP) protects mice against lethal respiratory challenge with Francisella tularensis SchuS4

Francisella tularensis is a category A select agent. J5dLPS/OMP is a novel vaccine construct consisting of detoxified, O-polysaccharide side chain-deficient, lipopolysaccharide non-covalently complexed with the outer membrane protein of N. meningitidis group B. Immunization elicits high-titer polyclonal antibodies specific for the highly-conserved epitopes expressed within the glycolipid core that constitutes gram-negative bacteria (e.g., F. tularensis). Mice immunized intranasally with J5dLPS/OMP exhibited protective immunity to intratracheal challenge with the live vaccine strain, as well as the highly-virulent SchuS4 strain, of F. tularensis. The efficacy of J5dLPS/OMP vaccine suggests its potential utility in immunizing the general population against several different gram-negative select agents concurrently.

Epitope-based vaccination against pneumonic tularemia

Francisella tularensis, the etiological agent of tularemia, is one of the most infectious bacterial pathogens known. No vaccine is currently approved for public use. Previously, we identified epitopes recognized specifically by T cells obtained from individuals following infection with F. tularensis. Here, we report that a subunit vaccine constructed based upon these epitopes elicited protective immunity in "humanized" HLA class II (DRB1*0401) transgenic mice. Vaccinated mice challenged intratracheally with a lethal dose of F. tularensis (Live Vaccine Strain) exhibited a rapid increase in pro-inflammatory cytokine production and diminished number of organisms in the lungs, and a concurrent increased rate of survival. These results demonstrate the efficacy of an epitope-based tularemia vaccine and suggest that such an approach might be widely applicable to the development of vaccines specific for intracellular bacterial pathogens.

Attenuating burn wound inflammation improves pulmonary function and survival in a burn-pneumonia model

OBJECTIVE

We previously showed that topical inhibition of inflammatory signaling in burn wounds reduced systemic inflammatory response and burn-induced pulmonary inflammation. We hypothesized that this topical intervention would attenuate burn-induced lung injury, improve pulmonary function, protect lungs from bacterial invasion, and reduce mortality.

DESIGN

Controlled, in vivo, laboratory study.

SETTING

University laboratory.

SUBJECTS

Female mice, 8-10 wks old.

INTERVENTIONS

Animals received 30% total body surface area burn followed by topical application of a specific inhibitor of p38 mitogen-activated protein kinase, a key inflammatory signaling pathway, or vehicle to the wound. Twenty-four hours after injury, pulmonary collagen deposition and pulmonary function were assessed. One day postburn, some of the animals received intratracheal instillation of Klebsiella pneumoniae and were subsequently monitored for 7 days.

MEASUREMENTS AND MAIN RESULTS

Topical inhibition of p38 mitogen-activated protein kinase significantly decreased pulmonary collagen deposition and prevented a decline in pulmonary function at 1 day after burn injury. Compared with sham controls, animals with burn injury had a significantly higher mortality in response to intratracheal bacterial challenge. Application of p38 mitogen-activated protein kinase inhibitor to the burn wound attenuated pulmonary neutrophil infiltration and reduced the mortality rate to a level experienced by sham controls.

CONCLUSIONS

Inflammatory source control in burn wounds with topical p38 mitogen-activated protein kinase inhibition attenuates acute lung injury, avoids pulmonary dysfunction, protects lungs from bacterial challenge, and improves survival.

Gene therapy with lipopolysaccharide binding protein for gram-negative pneumonia: respiratory physiology

BACKGROUND

Lipopolysaccharide binding protein (LBP) plays an essential role in the pulmonary immune response to gram-negative bacterial infection. LBP knockout mice with gram-negative pneumonia have increased mortality compared with wild-type controls. This mortality difference can be abolished with systemic LBP gene therapy. We postulate that LBP knockout mice will develop derangements in lung physiology from gram-negative pneumonia and that these changes can be reversed with systemic LBP gene therapy.

METHODS

Twelve- to 16-week-old C57BL/6 wild-type mice and/or sex, age, matched LBP knockout mice were administered 1 x 10(3) colony-forming units/mouse of Klebsiella pneumoniae by intratracheal inoculation. Treated mice were administered 5 x 10(9) plaque-forming units of recombinant adenovirus containing either the gene for LBP or the irrelevant control protein beta-galactosidase by intravenous injection 2 days before bacterial inoculation. Respiratory physiology parameters were measured preinoculation and 24 hours postbacterial inoculation.

RESULTS

Administration of LBP by systemic gene therapy to LBP knockout mice improved 7-day survival from Klebsiella pneumonia to a level equivalent to wild-type mice exposed to the same dose of bacteria (42 vs. 43% survival). LBP knockout mice given the LBP gene therapy demonstrated increased 14-day survival from Klebsiella pneumonia when compared with controls treated with beta-galactosidase (28 vs. 0%, p < 0.001). LBP knockout mice developed significant differences in respiratory rate, minute ventilation, and enhanced pause (Penh), when compared with wild-type mice with Klebsiella pneumonia. These respiratory derangements were prevented with adenoviral delivery of the LBP gene before K. pneumoniae inoculation.

CONCLUSIONS

Gram-negative pneumonia produces measurable changes in mortality and respiratory physiology between wild-type and LBP knockout mice. These changes can be prevented in LBP knockout mice by systemic gene therapy to restore innate immunity.

Allergens induce enhanced bronchoconstriction and leukotriene production in C5 deficient mice

Background

Previous genetic analysis has shown that a deletion in the complement component 5 gene-coding region renders mice more susceptible to allergen-induced airway hyperresponsiveness (AHR) due to reduced IL-12 production. We investigated the role of complement in a murine model of asthma-like pulmonary inflammation.

Methods

In order to evaluate the role of complement B10 mice either sufficient or deficient in C5 were studied. Both groups of mice immunized and challenged with a house dust extract (HDE) containing high levels of cockroach allergens. Airways hyper-reactivity was determined with whole-body plesthysmography. Bronchoalveolar lavage (BAL) was performed to determine pulmonary cellular recruitment and measure inflammatory mediators. Lung homogenates were assayed for mediators and plasma levels of IgE determined. Pulmonary histology was also evaluated.

Results

C5-deficient mice showed enhanced AHR to methylcholine challenge, 474% and 91% increase above baseline Penh in C5-deficient and C5-sufficient mice respectively, p < 0.001. IL-12 levels in the lung homogenate (LH) were only slightly reduced and BAL IL-12 was comparable in C5-sufficient and C5-deficient mice. However, C5-deficient mice had significantly higher cysteinyl-leukotriene levels in the BAL fluid, 1913 +/- 246 pg/ml in C5d and 756 +/- 232 pg/ml in C5-sufficient, p = 0.003.

Conclusion

These data demonstrate that C5-deficient mice show enhanced AHR due to increased production of cysteinyl-leukotrienes.

Anti-tumor necrosis factor-alpha antibody treatment reduces pulmonary inflammation and methacholine hyper-responsiveness in a murine asthma model induced by house dust

BACKGROUND/AIMS

Recent studies documented that sensitization and exposure to cockroach allergens significantly increase children's asthma morbidity as well as severity, especially among inner city children. TNF-alpha has been postulated to be a critical mediator directly contributing to the bronchopulmonary inflammation and airway hyper-responsiveness in asthma. This study investigated whether an anti-TNF-alpha antibody would inhibit pulmonary inflammation and methacholine (Mch) hyper-responsiveness in a mouse model of asthma induced by a house dust extract containing both endotoxin and cockroach allergens.

METHODS

A house dust sample was extracted with phosphate-buffered saline and then used for immunization and two additional pulmonary challenges of BALB/c mice. Mice were treated with an intravenous injection of anti-TNF-alpha antibody or control antibody 1 h before each pulmonary challenge.

RESULTS

In a kinetic study, TNF-alpha levels within the bronchoalveolar lavage (BAL) fluid increased quickly peaking at 2 h while BAL levels of IL-4, IL-5, and IL-13 peaked at later time-points. Mch hyper-responsiveness was measured 24 h after the last challenge, and mice were killed 24 h later. TNF inhibition resulted in an augmentation of these Th2 cytokines. However, the allergic pulmonary inflammation was significantly reduced by anti-TNF-alpha antibody treatment as demonstrated by a substantial reduction in the number of BAL eosinophils, lymphocytes, macrophages, and neutrophils compared with rat IgG-treated mice. Mch hyper-responsiveness was also significantly reduced in anti-TNF-alpha antibody-treated mice and the pulmonary histology was also significantly improved. Inhibition of TNF significantly reduced eotaxin levels within the lung, suggesting a potential mechanism for the beneficial effects. These data indicate that anti-TNF-alpha antibody can reduce the inflammation and pathophysiology of asthma in a murine model of asthma induced by a house dust extract.

CXC chemokines modulate IgE secretion and pulmonary inflammation in a model of allergic asthma

The pathophysiology of asthma is influenced by exposure to allergens and endotoxin. Although the role of allergen-induced eosinophilia has been widely studied, neutrophil-mediated responses remain elusive. A role for neutrophils in the asthmatic responses is likely since human neutrophils have been shown to express IgE receptors, as well as receptors for many cytokines and chemokines implicated in the pathogenesis of asthma. In this study we investigated neutrophil involvement in a novel, house dust extract (HDE) induced model of asthma-like pulmonary inflammation. Mice were immunized and challenged with HDE containing high levels of cockroach allergens, 377 U/ml Bla g1 and 6249 ng/ml Bla g2. The biological activity of the murine chemokines KC and MIP-2 was inhibited with specific rabbit antisera. Differential counting of cells recovered from the bronchoalveolar lavage (BAL) fluid showed that neutralization of KC and MIP-2 significantly decreased pulmonary recruitment of neutrophils (reduced 86%) and lymphocytes (reduced 76%). Neutralization of these chemokines also exerted a systemic effect with a significant decrease in plasma IgE levels, 547 ng/ml+/-65 compared to 1314 ng/ml+/-247 for control sera treated animals. This study shows that CXC chemokines play an important role in allergy and asthma both at the level of pulmonary cell recruitment and systemic immune responses.

Sequential ELISA to profile multiple cytokines from small volumes

Due to the low cost and relative effectiveness the enzyme-linked immunosorbent assay (ELISA) is widely used to measure the concentration of inflammatory cytokines in plasma and other sources. Blood volume represents a limiting factor in those mouse models requiring repeated sample collection at multiple time intervals to monitor the trajectory of inflammatory processes. The small blood volumes in such scenarios restrict the array of cytokines that can be measured using the traditional ELISA. The implementation of the sequential ELISA protocol presented here can dramatically increase the number of measured cytokines, since the plasma samples are not discarded after the initial assay but re-used to measure additional selected inflammatory proteins in consecutive tests. From the original 20 mul of blood volume collected, up to fifteen cytokines can be successfully assayed in five consecutive cycles. With more unstable cytokines analyzed in the initial cycles, no inter-assay interference and/or deterioration of samples occurs. The sequential ELISA technique based on commercially-available antibody pairs can be an attractive alternative to more advanced, costly methods. Given the simplistic validation procedure, the proposed sequential ELISA protocol has a wide potential for further modifications to include other inflammation-related targets.

A new mouse model of lung allergy induced by the spores of Alternaria alternata and Cladosporium herbarum molds

Asthma is a serious health problem and during the last decade various experimental models of asthma have been developed to study the pathogenesis of this disease. In this study we describe a new mouse model of asthma that uses the spores of Alternaria alternata and Cladosporium herbarum, two allergenic molds recognized as common inducers of rhinitis and asthma in humans. Here we demonstrate that A. alternata and C. herbarum spores are immunogenic when injected into BALB/c mice, and induce the production of specific IgM and IgG1 antibodies and strongly increase IgE serum levels. To induce the allergic response, mice were sensitized by two intraperitoneal (i.p.) injections and then intranasaly (i.n.) challenged with A. alternata and C. herbarum spores. Bronchoalveolar lavages (BALs) from these mice contained numerous macrophages, neutrophils, eosinophils and lymphocytes whereas neutrophils were the predominant BAL inflammatory cells in nonsensitized mice. Histological studies demonstrated an influx of eosinophils in peri-vascular and peri-bronchial areas and the presence of numerous epithelial goblet cells only in sensitized mice. Increased expression of mRNA specific for various chemokines (eotaxin, MIP-1alpha, MIP-2) and chemokine receptors (CCR-1, CCR-2 and CCR-5) was observed in the lungs of nonsensitized mice challenged with the spores. Expression of CCR-3 mRNA in the lungs and Th2 cytokine (IL-4, IL-5 and IL-13) secretion in the BAL was additionally observed in sensitized and challenged mice. Finally we demonstrate through whole-body plethysmography that mold spore sensitization and challenge induce the development of an airway hyperreactivity in response to nebulized methacholine.

In vivo gene silencing (with siRNA) of pulmonary expression of MIP-2 versus KC results in divergent effects on hemorrhage-induced, neutrophil-mediated septic acute lung injury

Lung injury in trauma patients exposed to a secondary infectious/septic challenge contributes to the high morbidity/mortality observed in this population. Associated pathology involves a dys-regulation of immune function, specifically, sequestration of activated polymorphonuclear neutrophils (PMN) in the lungs. The targeting of PMN is thought to involve the release of chemokines from cells within the local environment, creating a concentration gradient along which PMN migrate to the focus of inflammation. Keratinocyte-derived chemokine (KC) and macrophage-inflammatory protein-2 (MIP-2) are murine neutrophil chemokines identified as playing significant but potentially divergent roles in the pathogenesis of acute lung injury (ALI). In the current study, we examined the contribution of local pulmonary cells to the production of KC and MIP-2 and the pathogenesis of ALI. We hypothesized that local silencing of KC or MIP-2, via the local administration of small interference RNA (siRNA) against KC or MIP-2, following traumatic shock/hemorrhage (Hem), would suppress signaling for PMN influx to the lung, thereby reducing ALI associated with a secondary septic challenge (cecal ligation and puncture). Assessment of siRNA local gene silencing was done in green fluorescent protein (GFP)-transgenic, overexpressing mice. A marked suppression of GFP expression was observed in the lung 24 h following intratracheal (i.t.) instillation of GFP siRNA, which was not observed in the liver. To test our hypothesis, siRNA against KC or MIP-2 (75 ug/C3H/Hen mouse) was instilled (i.t.) 2 h post-Hem (35 mm Hg for 90 min, 4x LRS Rx.). Twenty-four hours after, mice were subjected to septic challenge and then killed 24 h later. i.t. MIP-2 siRNA significantly (P < 0.05, ANOVA-Tukey's test, n = 5-6/group) reduced tissue and plasma interleukin (IL)-6, tissue MIP-2 (enzyme-linked immunosorbent assay), as well as neutrophil influx [myeloperoxidase (MPO) activity]. In contrast, KC siRNA treatment reduced plasma KC, tissue KC, and IL-6 but produced no significant reduction in plasma IL-6 or MPO. Neither treatment reduced tissue or plasma levels of tumor necrosis factor alpha compared with vehicle. These data support not only our hypothesis that local pulmonary chemokine production of MIP-2, to a greater extent than KC, contributes to the pathogenesis of PMN-associated ALI following Hem but also the use of siRNA as a potential therapeutic.

Reproducibility of a novel model of murine asthma-like pulmonary inflammation

Sensitization to cockroach allergens (CRA) has been implicated as a major cause of asthma, especially among inner-city populations. Endotoxin from Gram-negative bacteria has also been investigated for its role in attenuating or exacerbating the asthmatic response. We have created a novel model utilizing house dust extract (HDE) containing high levels of both CRA and endotoxin to induce pulmonary inflammation (PI) and airway hyperresponsiveness (AHR). A potential drawback of this model is that the HDE is in limited supply and preparation of new HDE will not contain the exact components of the HDE used to define our model system. The present study involved testing HDEs collected from various homes for their ability to cause PI and AHR. Dust collected from five homes was extracted in phosphate buffered saline overnight. The levels of CRA and endotoxin in the supernatants varied from 7.1 to 49.5 mg/ml of CRA and 1.7-6 micro g/ml of endotoxin in the HDEs. Following immunization and two pulmonary exposures to HDE all five HDEs induced AHR, PI and plasma IgE levels substantially higher than normal mice. This study shows that HDE containing high levels of cockroach allergens and endotoxin collected from different sources can induce an asthma-like response in our murine model.

Prevention and reversal of pulmonary inflammation and airway hyperresponsiveness by dexamethasone treatment in a murine model of asthma induced by house dust

The morbidity and mortality from asthma in the Western world have increased 75% in the past 20 years. Recent studies have demonstrated that sensitization to cockroach allergens correlates strongly with the increased asthma morbidity for adults and children. We investigated whether dexamethasone administered before or after allergen challenge would inhibit the pulmonary inflammation and airway hyperresponsiveness in a mouse model of asthma induced by a house dust extract with high levels of cockroach allergens. For the prevention experiment, mice were treated with an intraperitoneal injection of dexamethasone 1 h before each pulmonary challenge, and airway hyperresponsiveness was measured 24 h after the last challenge. Mice were killed 48 h after the last challenge. For the reversal study, airway hyperresponsiveness was measured 24 h after the last challenge, and the mice were treated with dexamethasone. Dexamethasone treatment before allergen challenge significantly reduced the pulmonary recruitment of inflammatory cells, myeloperoxidase activity in the lung, airway hyperreactivity, and total serum IgE levels compared with PBS-treated mice. Additionally, dexamethasone treatment could significantly reduce the airway hyperreactivity of an established asthmatic response. These results demonstrate that dexamethasone not only prevents but also halts the asthmatic response induced by house dust containing cockroach allergens. This model exhibits several features of human asthma that may be exploited in the study of pathophysiological mechanisms and potential therapeutic interventions.

Improved sensitivity of colorimetric compared to chemiluminescence ELISAs for cytokine assays

Cytokines are often measured using ELISAs and chemiluminescence (CMIL) is reported to exhibit increased sensitivity compared to colorimetric (COL) assays. CMIL also has a wider dynamic detection range. We sought to directly compare ELISAs for measuring human TNF and IL-8 using CMIL or COL. CMIL substrates with glow fluorescence were obtained from 4 different commercial sources while the COL substrate was TMB. ELISAs for TNF and IL-8 were run under identical conditions and the standard curve extended from 0.5 to 4000 pg/ML. The COL substrate demonstrated a sigmoid shaped curve when plotted on a log-linear scale while the CMIL continued to increase up to the highest concentration. Both substrates were modeled most accurately by a 4 parameter equation with R values > 0.99. The standard curves for both the IL-8 and TNF demonstrated a lower limit of detection (LLD) for the COL comparable to the CMIL detection system. To precisely define the LLD quadruplicate blanks were run and the mean plus 4 standard deviations were used. By these criteria, the COL assay routinely had a LLD of < 1.5 pg/ML which was better than any of the CMIL substrates. Our data demonstrate the COL assays have the same or better sensitivity than CMIL and are significantly less expensive.

Functional expression and characterization of macaque C-C chemokine receptor 3 (CCR3) and generation of potent antagonistic anti-macaque CCR3 monoclonal antibodies

Eosinophils are major effector cells implicated in a number of chronic inflammatory diseases in humans, particularly bronchial asthma and allergic rhinitis. The beta-chemokine receptor C-C chemokine receptor 3 (CCR3) provides a mechanism for the selective recruitment of eosinophils into tissue and thus has recently become an attractive biological target for therapeutic intervention. In order to develop in vivo models of inflammatory diseases, it is essential to identify and characterize the homologues of human eotaxin (C-C chemokine ligand 11) and CCR3 from other species, such as non-human primates. Accordingly, we cloned the macaque eotaxin and CCR3 genes and revealed that they were 91 and 92% identical at the amino acid level to their human homologues, respectively. Macaque CCR3 expressed in the murine pre-B L1-2 cell line bound macaque eotaxin with high affinity (K(d) = 0.1 nm) and exhibited a robust eotaxin-induced Ca(2+) flux and chemotaxis. Characterization of beta-chemokines on native macaque CCR3 on eosinophils was performed by means of eotaxin-induced shape change in whole blood using a novel signaling assay known as gated autofluorescence forward scatter. Additionally, mAbs were raised against macaque CCR3 using two different immunogens: a 30-amino acid synthetic peptide derived from the predicted NH(2) terminus of macaque CCR3 and intact macaque CCR3-transfected cells. These anti-macaque CCR3 monoclonal antibodies exhibited potent antagonist activity in receptor binding and functional assays. The characterization of the macaque eotaxin/CCR3 axis and development of antagonistic anti-macaque CCR3 monoclonal antibodies will facilitate the development of CCR3 small molecule antagonists with the hope of ameliorating chronic inflammatory diseases in humans.