Mast cells play a key role in the development of late airway hyperresponsiveness through TNF-alpha in a murine model of asthma

Targeting Mast Cells in Allergic Disease: Current Therapies and Drug Repurposing

The incidence of allergic disease has grown tremendously in the past three generations. While current treatments are effective for some, there is considerable unmet need. Mast cells are critical effectors of allergic inflammation. Their secreted mediators and the receptors for these mediators have long been the target of allergy therapy. Recent drugs have moved a step earlier in mast cell activation, blocking IgE, IL-4, and IL-13 interactions with their receptors. In this review, we summarize the latest therapies targeting mast cells as well as new drugs in clinical trials. In addition, we offer support for repurposing FDA-approved drugs to target mast cells in new ways. With a multitude of highly selective drugs available for cancer, autoimmunity, and metabolic disorders, drug repurposing offers optimism for the future of allergy therapy.

Structural Characterization and Pro-inflammatory Activity of a Thaumatin-Like Protein from Pulp Tissues of Litchi chinensis

The objective of this study was to extract and purify proteins from the pulp tissues of litchi and evaluate their structure and pro-inflammatory activity. The results showed that a highly pure litchi protein was identified as the litchi thaumatin-like protein (LcTLP) by nano LC-MS/MS and verified by sequencing of the LcTLP gene. The molecular weight was 24 kDa, and the main secondary structure was a β sheet (33.00 ± 2.86%). Small-angle X-ray scattering results showed that LcTLP was a spherical particle (diameter of approximately 140 to 165 nm) with a close internal and rough surface in solution. The assay of pro-inflammatory activity in vitro revealed that the expression of inducible nitric oxide synthase and cyclooxygenase-2 genes reached 9.71 ± 0.64 and 7.05 ± 1.00 after 200 μg/mL LcTLP stimulation, which were 7.05-fold and 9.61-fold that of the blank control, respectively. LcTLP promoted the gene expression and production of pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, and it also enhanced the expression of p65, which is a key component of nuclear factor-κ B signaling pathways. Additionally, the levels of anti-inflammatory cytokines interleukin-10 and transforming growth factor-β1 increased after LcTLP stimulation.

Beneficial Effects of Neurotensin in Murine Model of Hapten-Induced Asthma

Neurotensin (NT) demonstrates ambiguous activity on inflammatory processes. The present study was undertaken to test the potential anti-inflammatory activity of NT in a murine model of non-atopic asthma and to establish the contribution of NTR1 receptors. Asthma was induced in BALB/c mice by skin sensitization with dinitrofluorobenzene followed by intratracheal hapten provocation. The mice were treated intraperitoneally with NT, SR 142948 (NTR1 receptor antagonist) + NT or NaCl. Twenty-four hours after the challenge, airway responsiveness to nebulized methacholine was measured. Bronchoalveolar lavage fluid (BALF) and lungs were collected for biochemical and immunohistological analysis. NT alleviated airway hyperreactivity and reduced the number of inflammatory cells in BALF. These beneficial effects were inhibited by pretreatment with the NTR1 antagonist. Additionally, NT reduced levels of IL-13 and TNF-α in BALF and IL-17A, IL12p40, RANTES, mouse mast cell protease and malondialdehyde in lung homogenates. SR 142948 reverted only a post-NT TNF-α decrease. NT exhibited anti-inflammatory activity in the hapten-induced asthma. Reduced leukocyte accumulation and airway hyperresponsiveness indicate that this beneficial NT action is mediated through NTR1 receptors. A lack of effect by the NTR1 blockade on mast cell activation, oxidative stress marker and pro-inflammatory cytokine production suggests that other pathways can be involved, which requires further research.

Urine TNF-α and IL-9 for clinical diagnosis of acute interstitial nephritis

BACKGROUNDClinical diagnosis of acute interstitial nephritis (AIN) is challenging because of lack of a diagnostic biomarker and requires a kidney biopsy. We hypothesized that AIN is mediated by specific T cell subsets such that specific T cell cytokine levels could serve as biomarkers to distinguish AIN from other causes of acute kidney disease (AKD).METHODSWe enrolled consecutive sampling participants who underwent a kidney biopsy for AKD evaluation at 2 centers between 2015 and 2018. Three pathologists independently established AIN diagnosis through review of kidney biopsies. Through univariable and multivariable analysis of 12 selected urine and plasma cytokines, we identified 2 that were diagnostic of AIN.RESULTSOf the 218 participants, 32 (15%) were diagnosed with AIN by all 3 pathologists. Participants with AIN had consistently higher levels of urine TNF-α and IL-9 than those with other diagnoses, including acute tubular injury, glomerular diseases, and diabetic kidney disease, and those without any kidney disease. As compared with participants in the lowest quartile, we noted higher odds of AIN in participants in the highest quartiles of TNF-α levels (adjusted odds ratio, 10.9 [1.8, 65.9]) and IL-9 levels (7.5 [1.2, 45.7]) when controlling for blood eosinophils, leukocyturia, and proteinuria. Addition of biomarkers improved area under receiver operating characteristic curve over clinicians' prebiopsy diagnosis (0.84 [0.78, 0.91]) vs. 0.62 [(0.53, 0.71]) and a model of current tests (0.84 [0.76, 0.91] vs. 0.69 [0.58, 0.80]).CONCLUSIONSInclusion of urinary TNF-α and IL-9 improves discrimination over clinicians' prebiopsy diagnosis and currently available tests for AIN diagnosis.FUNDINGSupported by NIH awards K23DK117065, T32DK007276, K24DK090203, K23DK097201, R01DK113191, UG3-DK114866, P30DK079310; the Robert E. Leet and Clara Guthrie Patterson Trust; and American Heart Association award 18CDA34060118.

Selenium Pretreatment Alleviated LPS-Induced Immunological Stress Via Upregulation of Several Selenoprotein Encoding Genes in Murine RAW264.7 Cells

This study was conducted to profile selenoprotein encoding genes in mouse RAW264.7 cells upon lipopolysaccharide (LPS) challenge and integrate their roles into immunological regulation in response to selenium (Se) pretreatment. LPS was used to develop immunological stress in macrophages. Cells were pretreated with different levels of Se (0, 0.5, 1.0, 1.5, 2.0 μmol Se/L) for 2 h, followed by LPS (100 ng/mL) stimulation for another 3 h. The mRNA expression of 24 selenoprotein encoding genes and 9 inflammation-related genes were investigated. The results showed that LPS (100 ng/mL) effectively induced immunological stress in RAW264.7 cells with induced inflammation cytokines, IL-6 and TNF-α, mRNA expression, and cellular secretion. LPS increased (P < 0.05) mRNA profiles of 9 inflammation-related genes in cells, while short-time Se pretreatment modestly reversed (P < 0.05) the LPS-induced upregulation of 7 genes (COX-2, ICAM-1, IL-1β, IL-6, IL-10, iNOS, and MCP-1) and further increased (P < 0.05) expression of IFN-β and TNF-α in stressed cells. Meanwhile, LPS decreased (P < 0.05) mRNA levels of 18 selenoprotein encoding genes and upregulated mRNA levels of TXNRD1 and TXNRD3 in cells. Se pretreatment recovered (P < 0.05) expression of 3 selenoprotein encoding genes (GPX1, SELENOH, and SELENOW) in a dose-dependent manner and increased (P < 0.05) expression of another 5 selenoprotein encoding genes (SELENOK, SELENOM, SELENOS, SELENOT, and TXNRD2) only at a high level (2.0 μmol Se/L). Taken together, LPS-induced immunological stress in RAW264.7 cells accompanied with the global downregulation of selenoprotein encoding genes and Se pretreatment alleviated immunological stress via upregulation of a subset of selenoprotein encoding genes.

Anti-Inflammatory Effects of a Mytilus coruscus α-d-Glucan (MP-A) in Activated Macrophage Cells via TLR4/NF-κB/MAPK Pathway Inhibition

The hard-shelled mussel (Mytilus coruscus) has been used as Chinese traditional medicine for thousands of years; however, to date the ingredients responsible for the various beneficial health outcomes attributed to Mytilus coruscus are still unclear. An α-d-Glucan, called MP-A, was isolated from Mytilus coruscus, and observed to exert anti-inflammatory activity in THP-1 human macrophage cells. Specifically, we showed that MP-A treatment inhibited the production of inflammatory markers, including TNF-α, NO, and PGE2, inducible NOS (iNOS), and cyclooxygenase-2 (COX-2), in LPS-activated THP-1 cells. It was also shown to enhance phagocytosis in the analyzed cells, but to severely inhibit the phosphorylation of mitogen-activated protein kinases (MAPKs) and the nuclear translocation of NF-κB P65. Finally, MP-A was found to exhibit a high binding affinity for the cell surface receptor TLR4, but a low affinity for TLR2 and dectin-1, via surface plasmon resonance (SPR) analysis. The study indicates that MP-A suppresses LPS-induced TNF-α, NO and PEG2 production via TLR4/NF-κB/MAPK pathway inhibition, and suggests that MP-A may be a promising therapeutic candidate for diseases associated with TNF-α, NO, and/or PEG2 overproduction.

Mast Cell-Derived Exosomes Promote Th2 Cell Differentiation via OX40L-OX40 Ligation

Exosomes are nanovesicles released by different cell types, such as dendritic cells (DCs), mast cells (MCs), and tumor cells. Exosomes of different origin play a role in antigen presentation and modulation of immune response to infectious disease. In this study, we demonstrate that mast cells and CD4(+) T cells colocated in peritoneal lymph nodes from BALB/c mouse. Further, bone marrow-derived mast cells (BMMCs) constitutively release exosomes, which express CD63 and OX40L. BMMC-exosomes partially promoted the proliferation of CD4(+) T cells. BMMC-exosomes significantly enhanced the differentiation of naive CD4(+) T cells to Th2 cells in a surface contact method, and this ability was partly inhibited by the addition of anti-OX40L Ab. In conclusion, BMMC-exosomes promoted the proliferation and differentiation of Th2 cells via ligation of OX40L and OX40 between exosomes and T cells. This method represents a novel mechanism, in addition to direct cell surface contacts, soluble mediators, and synapses, to regulate T cell actions by BMMC-exosomes.

Stem Cell Factor and Interleukin-31 Expression: Association with IgE among Egyptian Patients with Atopic and Nonatopic Bronchial Asthma

Bronchial asthma is a chronic inflammatory disorder which remains a significant cause of morbidity. Recently, it has been reported that the stem cell factor (SCF) and interleukin-31 (IL-31) may play a major role in bronchial asthma. The aim of the current study was to study the association of the stem cell factor and interleukin-31 expression with serum immunoglobulin E among Egyptian patients with atopic and nonatopic bronchial asthma. After measuring serum IgE using total enzyme linked immunosorbent assay (ELISA), Ribonucleic acid (RNA) was isolated to determine gene expression of SCF and IL-31 by real-time polymerase chain reaction (PCR). The levels of SCF mRNAs in atopic asthmatic patients' PBMCs were significantly higher than those in controls (p = 0.0001**) and nonatopic asthmatics (p = 0.0001**). There was a high statistical significant difference also with regard to IL-31 between atopic asthmatics and controls (p = 0.0001**) and between them and nonatopic patients (p = 0.014*). There was a strong significant direct correlation between SCF, IL-31 (r = 0.827 and p = 0.0001**) and between both of them and IgE in asthmatics (r = 0.543 and p = 0.0001**) (r = 0.443 and p = 0.0001**), respectively. A direct correlation between SCF, IL-31 and FEV-1/ FVC %, CRP and wheezing existed. These findings suggest that both SCF and IL-31 play an important role in mediating inflammation and enhancing severity of atopic asthma. Augmented inhaled glucocorticoid therapy was associated with significant reductions in SCF and IL-31 mRNA expression as well as improvements in lung function, symptom scores and bronchial hyperresponsiveness to methacholine (PD20) in atopic and nonatopic asthmatics.

TH9 cells are required for tissue mast cell accumulation during allergic inflammation

BACKGROUND

IL-9 is important for the growth and survival of mast cells. IL-9 is produced by T cells, natural killer T cells, mast cells, eosinophils, and innate lymphoid cells, although the cells required for mast cell accumulation during allergic inflammation remain undefined.

OBJECTIVE

We sought to elucidate the role of TH9 cells in promoting mast cell accumulation in models of allergic lung inflammation.

METHODS

Adoptive transfer of ovalbumin-specific TH2 and TH9 cells was used to assess the ability of each subset to mediate mast cell accumulation in tissues. Mast cell accumulation was assessed in wild-type mice and mice with PU.1-deficient T cells subjected to acute and chronic models of allergic inflammation.

RESULTS

Adoptive transfer experiments demonstrated that recipients of TH9 cells had significantly higher mast cell accumulation and expression of mast cell proteases compared with control or TH2 recipients. Mast cell accumulation was dependent on IL-9, but not IL-13, a cytokine required for many aspects of allergic inflammation. In models of acute and chronic allergic inflammation, decreased IL-9 levels in mice with PU.1-deficient T cells corresponded to diminished tissue mast cell numbers and expression of mast cell proteases. Mice with PU.1-deficient T cells have defects in IL-9 production from CD4(+) T cells, but not natural killer T cells or innate lymphoid cells, suggesting a TH cell-dependent phenotype. Rag1(-/-) mice subjected to a chronic model of allergic inflammation displayed reduced mast cell infiltration comparable with accumulation in mice with PU.1-deficient T cells, emphasizing the importance of IL-9 produced by T cells in mast cell recruitment.

CONCLUSION

TH9 cells are a major source of IL-9 in models of allergic inflammation and play an important role in mast cell accumulation and activation.

Approaches for analyzing the roles of mast cells and their proteases in vivo

The roles of mast cells in health and disease remain incompletely understood. While the evidence that mast cells are critical effector cells in IgE-dependent anaphylaxis and other acute IgE-mediated allergic reactions seems unassailable, studies employing various mice deficient in mast cells or mast cell-associated proteases have yielded divergent conclusions about the roles of mast cells or their proteases in certain other immunological responses. Such "controversial" results call into question the relative utility of various older versus newer approaches to ascertain the roles of mast cells and mast cell proteases in vivo. This review discusses how both older and more recent mouse models have been used to investigate the functions of mast cells and their proteases in health and disease. We particularly focus on settings in which divergent conclusions about the importance of mast cells and their proteases have been supported by studies that employed different models of mast cell or mast cell protease deficiency. We think that two major conclusions can be drawn from such findings: (1) no matter which models of mast cell or mast cell protease deficiency one employs, the conclusions drawn from the experiments always should take into account the potential limitations of the models (particularly abnormalities affecting cell types other than mast cells) and (2) even when analyzing a biological response using a single model of mast cell or mast cell protease deficiency, details of experimental design are critical in efforts to define those conditions under which important contributions of mast cells or their proteases can be identified.

Insights into mast cell functions in asthma using mouse models

Therapeutics targeting specific mechanisms of asthma have shown promising results in mouse models of asthma. However, these successes have not transferred well to the clinic or to the treatment of asthma sufferers. We suggest a reason for this incongruity is that mast cell-dependent responses, which may play an important role in the pathogenesis of both atopic and non-atopic asthma, are not a key component in most of the current asthma mouse models. Two reasons for this are that wild type mice have, in contrast to humans, a negligible number of mast cells localized in the smaller airways and in the parenchyma, and that only specific protocols show mast cell-dependent reactions. The development of mast cell-deficient mice and the reconstitution of mast cells within these mice have opened up the possibility to generate mouse models of asthma with a marked role of mast cells. In addition, mast cell-deficient mice engrafted with mast cells have a distribution of mast cells more similar to humans. In this article we review and highlight the mast cell-dependent and -independent responses with respect to airway hyperresponsiveness and inflammation in asthma models using mast cell-deficient and mast cell-engrafted mice.

Nitidine chloride inhibits LPS-induced inflammatory cytokines production via MAPK and NF-kappaB pathway in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Zanthoxylum nitidium (Roxb.) DC. has long been used as a traditional herbal medicine for inflammatory diseases such as rheumatic arthritis and peridentitis. However, the anti-inflammatory mechanism of Nitidine chloride has not been fully elucidated.

AIM OF THE STUDY

To determine the anti-inflammatory effects and mechanism of Nitidine chloride (NTD), a pentacyclic alkaloid is isolated from the root of Z. nitidium, in murine macrophages.

MATERIALS AND METHODS

Anti-inflammatory properties of NTD were investigated using lipopolysaccharide (LPS)-stimulated Raw 264.7 macrophages as in vitro model. The pro-inflammatory cytokines were evaluated by real-time RT-PCR and ELISA. Furthermore, intracellular signaling pathways were analyzed by Western blot and Immunofluorescence staining using specific antibodies.

RESULTS

NTD significantly reduced the production of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 in both RNA and protein level. Moreover, transcriptional activity of NF-кB as well as the phosphorylation of mitogen-activated protein kinases (MAPKs) in LPS-treated RAW 264.7 was significantly inhibited by NTD in a dose dependent manner. These results suggested that NTD exerts an anti-inflammatory property by inhibiting TNF-α, IL-1β, and IL-6 production in association with reduced NF-κB and MAPK signaling pathways in RAW 264.7 cells.

CONCLUSION

These results suggested that NTD exerts an anti-inflammatory property by inhibiting TNF-α, IL-1β, and IL-6 production in association with reduced NF-κB and MAPK signaling pathways in RAW 264.7 cells. Nitidine chloride inhibits LPS-induced TNF alpha, IL-1beta and IL-6 production via the suppression of phosphorylation of MAPK and the translocation of p65. In addition, these results revealed a novel role of NTD in regulation of inflammatory diseases.

Biphasic late airway hyperresponsiveness in a murine model of asthma

BACKGROUND

Nonspecific airway hyperresponsiveness (AHR) is one of the cardinal features of bronchial asthma. Early AHR is caused by chemical mediators released from pulmonary mast cells activated in an IgE-dependent way. However, the mechanism of late AHR remains unclear.

METHODS

Features of airway allergic inflammation were analyzed, including antigen-induced AHR, using a murine model of asthma. The model was suitable for examining the sequential early molecular events occurring after the initial airway exposure to antigen.

RESULTS

AHR increased at 10-12 h after airway challenge, followed by the second-phase response, which was larger and broader in resistance at 18-30 h. Pretreatment of sensitized animals with anti-tumor necrosis factor (TNF) before airway challenge or induction of allergic asthma in TNF(-/-) mice resulted in abrogation of the first-phase late AHR. Intratracheal instillation of TNF induced a single peak of AHR at 10 h. IgE and IgG immune complexes induced the development of the first-phase late AHR by TNF production. Pretreatment with cytosolic phospholipase inhibitor and 5-lipoxygenase inhibitors abolished the first-phase late AHR as well as the leukotriene B(4) levels in the airway. CpG-oligodeoxynucleotide (ODN) pretreatment reduced airway levels of Th2 cytokines, eosinophil infiltration and second-phase late AHR. However, CpG-ODN did not reduce TNF levels or the magnitude of first-phase late AHR.

CONCLUSION

Biphasic late AHR occurs in a murine model of asthma. First- and second-phase late AHR is caused by TNF and Th2 response, respectively.

TNF-α-induces airway hyperresponsiveness to cholinergic stimulation in guinea pig airways

BACKGROUND AND PURPOSE

TNF-α is an inflammatory cytokine implicated in the pathogenesis of asthma and it causes airway inflammation, bronchoconstriction and airway hyperresponsiveness to a number of spasmogens following inhalation.

EXPERIMENTAL APPROACH

We compared contractions of guinea pig isolated trachea incubated with saline or TNF-α for 1, 2 or 4 days to electrical field stimulation (EFS), 5-HT or methacholine. In addition, we compared bronchoconstriction in anaesthetized guinea pigs 6 h after intratracheal instillation of saline or TNF-α to vagal nerve stimulation, i.v. 5-HT or methacholine. Differential counts were performed on the bronchoalvelolar lavage fluid (BALF).

KEY RESULTS

Maximum contractions to methacholine, 5-HT and EFS were not different between freshly prepared and saline-incubated tissues. Exposure to TNF-α concentration-dependently potentiated contractions to 5-HT and EFS, but not methacholine. All contractions were atropine-sensitive, but not hexamethonium-sensitive. 5-HT-evoked contractions were inhibited by ketanserin or epithelial denudation. Only EFS-evoked contractions were tetrodotoxin-sensitive. Vagal stimulation, i.v. 5-HT or MCh caused a significant atropine-sensitive, frequency- and dose-dependent bronchoconstriction and decreased blood pressure similarly in both saline and TNF-α pre-treated animals. TNF-α potentiated the bronchoconstriction to vagal stimulation and 5-HT, but not MCh. The BALF from saline-treated animals contained predominantly macrophages, whereas that from TNF-α-treated animals contained neutrophils.

CONCLUSIONS AND IMPLICATIONS

TNF-α caused airway hyperresponsiveness to nerve stimulation in vivo and increased contractility in vitro. However, responsiveness to MCh was unchanged, suggesting a pre-synaptic action of TNF-α on parasympathetic nerves. TNF-α-induced airway hyperresponsiveness to 5-HT suggested an increased 5-HT(2A) receptor-mediated acetylcholine release from epithelial cells.

Cockroach allergens induce biphasic asthma-like pulmonary inflammation in outbred mice

OBJECTIVES

The aim of this study is to define the kinetics of the pulmonary inflammatory response in cockroach allergen (CRA) sensitized and challenged outbred mice.

METHODS

Asthma-like pulmonary inflammation was induced with three pulmonary exposures to CRA, without the use of adjuvants. Mice were sacrificed at multiple time points and asthma-like pulmonary inflammation quantified.

RESULTS

Several pulmonary parameters showed a pronounced biphasic inflammatory response with an early stage (1.5 hours post challenge) and late stage (24 hours). The initial phase was characterized by the production of multiple inflammatory mediators, including CXC chemokines, and the recruitment of neutrophils to the lung. The number of pulmonary eosinophils decreased in the early phase but quickly rebounded. Both the early and late phases had increases in TNF production in addition to airways hyperreactivity. The model also demonstrated early production of mucin with clearance by 12 hours followed by new accumulation of mucin in the pulmonary epithelial cells. Eotaxins within the lung peaked at about 12 hours and the numbers of eosinophils in the lung remained constant throughout the 48 hours of the study.

CONCLUSIONS

The pulmonary inflammatory parameters in response to a clinically relevant allergen define a biphasic response. These data may be used to investigate the pathogenesis of the disease and develop targeted therapies for the distinct phases.

Mast cell TNF receptors regulate responses to Mycoplasma pneumoniae in surfactant protein A (SP-A)-/- mice

BACKGROUND

Mycoplasma pneumoniae (Mp) frequently colonizes the airways of patients with chronic asthma and likely contributes to asthma exacerbations. We previously reported that mice lacking surfactant protein A (SP-A) have increased airway hyperresponsiveness (AHR) during M pneumoniae infection versus wild-type mice mediated by TNF-α. Mast cells (MCs) have been implicated in AHR in asthma models and produce and respond to TNF-α.

OBJECTIVE

Determine the contribution of MC/TNF interactions to AHR in airways lacking functional SP-A during Mp infection.

METHODS

Bronchoalveolar lavage fluid was collected from healthy and asthmatic subjects to examine TNF-α levels and M pneumoniae positivity. To determine how SP-A interactions with MCs regulate airway homeostasis, we generated mice lacking both SP-A and MCs (SP-A(-/-)Kit(W-sh/W-sh)) and infected them with M pneumoniae.

RESULTS

Our findings indicate that high TNF-α levels correlate with M pneumoniae positivity in human asthmatic patients and that human SP-A inhibits M pneumoniae-stimulated transcription and release of TNF-α by MCs, implicating a protective role for SP-A. MC numbers increase in M pneumoniae-infected lungs, and airway reactivity is dramatically attenuated when MCs are absent. Using SP-A(-/-)Kit(W-sh/W-sh) mice engrafted with TNF-α(-/-) or TNF receptor (TNF-R)(-/-) MCs, we found that TNF-α activation of MCs through the TNF-R, but not MC-derived TNF-α, leads to augmented AHR during M pneumoniae infection when SP-A is absent. Additionally, M pneumoniae-infected SP-A(-/-)Kit(W-sh/W-sh) mice engrafted with TNF-α(-/-) or TNF-R(-/-) MCs have decreased mucus production compared with that seen in mice engrafted with wild-type MCs, whereas burden was unaffected.

CONCLUSION

Our data highlight a previously unappreciated but vital role for MCs as secondary responders to TNF-α during the host response to pathogen infection.

Protective effects of basic fibroblast growth factor in the development of emphysema induced by interferon-γ

Recent clinical evidence indicates that the non-eosinophilic subtype of severe asthma is characterized by fixed airway obstruction, which may be related to emphysema. Transgenic studies have demonstrated that high levels of IFN-γ in the airways induce emphysema. Fibroblast growth factor 2 (FGF2), which is the downstream mediator of TGF-β, is important in wound healing. We investigated the role of FGF2 in IFN-γ-induced emphysema and the therapeutic effects of recombinant FGF2 in the prevention of emphysema in a severe non-eosinophilic asthma model. To evaluate the role of FGF2 in IFN-γ-induced emphysema, lung targeted IFN-γ transgenic mice were cross-bred with FGF2-deficient mice. A severe non-eosinophilic asthma model was generated by airway application of LPS-containing allergens twice a week for 4 weeks. To evaluate protective effects of FGF2, recombinant FGF2 (10 μg) was injected subcutaneously during allergen challenge in the severe asthma model. We found that non-eosinophilic inflammation and emphysema induced by transgenic overexpression of IFN-γ in the airways were aggravated by the absence of FGF2. Airway challenge with LPS-containing allergens induced more inflammation in mice sensitized with LPS-containing allergens compared to challenge with allergens alone. In addition, LPS-induced lung inflammation and emphysema depended on IFN-γ but not on IL-13. Interestingly, emphysema in the severe asthma model was significantly inhibited by treatment with recombinant FGF2 during allergen challenge, whereas lung inflammation was unaffected. Therefore, our present data suggest that FGF2 may help protect against IFN-γ-induced emphysema, and that recombinant FGF2 may help lessen the severity of emphysema.

IgG immune complex induces the recruitment of inflammatory cells into the airway and TNF-mediated late airway hyperresponsiveness via NF-κB activation in mice

BACKGROUND

Many of the inflammatory proteins that are expressed in asthmatic airways are regulated, at least partially, by nuclear factor (NF)-κB. Blockade of NF-κB activity has resulted in attenuation of the cardinal features of asthma. Thus, delineating the mechanisms involved in NF-κB activation in asthma might provide an interesting approach to improving the management of asthma. However, despite its importance, the mechanism for NF-κB activation in asthma has not yet been determined.

OBJECTIVE

To examine the role of IgE and IgG antibodies (Abs) in the activation of NF-κB in mouse lungs.

METHODS

To examine the effect of IgE, mice underwent intratracheal (i.t.) instillation of an IgE immune complex (IgE-IC) (anti-2,4-dinitrophenyl hapten (DNP) IgE + DNP-BSA or DNP-OVA) and anaphylactogenic anti-IgE (LO-ME-2). For IgG, mice underwent i.t. instillation with a complex of anti-chicken gamma globulin (CGG) IgG1 mAb + CGG. NF-κB activation was determined by gel shift assay. Small interfering RNA was used for blockade of p50 expression. The effect of tumor necrosis factor (TNF) blockade was determined using anti-TNF Ab. A previously established murine model of asthma was used to assess airway hyperresponsiveness (AHR).

RESULTS

A single i.t. instillation of either IgE-IC or LO-ME-2 failed to induce activation of NF-κB in the lungs. In contrast, single i.t. instillation of IgG-IC was capable of inducing NF-κB activation, as well as NF-κB-dependent proinflammatory molecules, such as TNF and CXC chemokines. Pretreatment of p50 small interfering RNA decreased bronchoalveolar lavage fluid levels of TNF and macrophage inflammatory protein-2 induced by IgG-IC instillation. Single i.t. instillation of IgG-IC caused the recruitment of neutrophils and macrophages into the airway and TNF-mediated late AHR, but failed to induce Th2 cell-mediated asthmatic phenotypes.

CONCLUSION

IgG, but not IgE, is the major Ab that induces not only NF-κB activation and NF-κB-dependent proinflammatory molecules in the lungs but also subsequent recruitment of inflammatory cells into the airway and TNF-mediated late AHR.

Mast cells and the development of allergic airway disease

Murine models have highlighted the importance of T-cells and T_H2 cytokines in development of allergen-induced airway disease. In contrast, the role of mast cells for the development of allergic airway disease has been controversial. Recent studies in murine models demonstrate a significant contribution of mast cells during the development of airway hyperresponsiveness and airway inflammation. Furthermore these models have allowed identifying certain mast cell-produced mediators (e.g. histamine and leukotriene B4) to be involved in the recruitment of effector T-cells into the lung. Additionally, mast cell-produced TNF can directly activate T_H2 cells and contribute to the development of allergic airway disease. These new findings demonstrate a complex role of mast cells and their mediators, not only as effector cells, but also during sensitization and development of allergic airway disease. Therefore mast cells and certain mast cell-produced mediators might be an interesting target for the prevention and treatment of allergic asthma.

Mast cells play a key role in Th2 cytokine-dependent asthma model through production of adhesion molecules by liberation of TNF-α

Mast cells are well recognized as key cells in allergic reactions, such as asthma and allergic airway diseases. However, the effects of mast cells and TNF-α on T-helper type 2 (Th2) cytokine-dependent asthma are not clearly understood. Therefore, an aim of this study was to investigate the role of mast cells on Th2 cytokine-dependent airway hyperresponsiveness and inflammation. We used genetically mast cell-deficient WBB6F1/J-Kitw/Kitw-v (W/Wv), congenic normal WBB6F1/J-Kit+/Kit+ (+/+), and mast cell-reconstituted W/Wv mouse models of allergic asthma to investigate the role of mast cells in Th2 cytokine-dependent asthma induced by ovalbumin (OVA). And we investigated whether the intratracheal injection of TNF-α directly induce the expression of ICAM-1 and VCAM-1 in W/Wv mice. This study, with OVA-sensitized and OVA-challenged mice, revealed the following typical histopathologic features of allergic diseases: increased inflammatory cells of the airway, airway hyperresponsiveness, and increased levels of TNF-α, intercellular adhesion molecule (ICAM)-1, and vascular cellular adhesion molecule (VCAM)-1. However, the histopathologic features and levels of ICAM-1 and VCAM-1 proteins in W/Wv mice after OVA challenges were significantly inhibited. Moreover, mast cell-reconstituted W/Wv mice showed restoration of histopathologic features and recovery of ICAM-1 and VCAM-1 protein levels that were similar to those found in +/+ mice. Intratracheal administration of TNF-α resulted in increased ICAM-1 and VCAM-1 protein levels in W/Wv mice. These results suggest that mast cells play a key role in a Th2 cytokine-dependent asthma model through production of adhesion molecules, including ICAM-1 and VCAM-1, by liberation of TNF-α.

Immunotherapy in asthma

Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. Chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing, as well as variable airflow obstruction within the lung. With time, such airflow obstruction may become permanent due to remodeling. It has been treated for more than 100 years by subcutaneous immunotherapy with allergen extracts but in recent years, other forms and types of immunotherapy have been introduced. Perhaps the most successful of these to date, is sublingual immunotherapy, which has attained significant usage in European countries but has yet to make inroads into clinical practice in North America. Other mechanisms to modify the inflammatory responses of asthma have included immunotherapy with recombinant allergens, the use of allergen peptides targeting antigen-specific T cells and the administration of Toll-like receptor agonists coupled to allergen proteins. As the inflammatory responses in asthma frequently involve IgE, a modified monoclonal antibody to IgE and interfering with its binding to the IgE receptor have gained acceptance for treating severe allergic asthma. Other monoclonal antibodies or recombinant receptor antagonists are being assessed for their ability to block other contributors to the inflammatory response. Finally, attempts have been made to generate autoantibody responses to cytokines implicated in asthma. Most of these therapies aim to modify or inhibit the so-called Th 2 immune response, which is implicated in many forms of asthma, or to inhibit cytokines involved in these responses. However, an added benefit of classical immunotherapy seems to be the ability to prevent the allergic progression to new sensitivities and new forms of allergic disease.

IL-10 and TNFalpha genotypes in SLE

The production of two regulators of the inflammatory response, interleukin 10 (IL-10) and tumor necrosis factor α (TNFα), has been found to be deeply deregulated in SLE patients, suggesting that these cytokines may be involved in the pathogenesis of the disease. Genetic polymorphisms at the promoter regions of IL-10 and TNFα genes have been associated with different constitutive and induced cytokine production. Given that individual steady-state levels of these molecules may deviate an initial immune response towards different forms of lymphocyte activation, functional genetic variants in their promoters could influence the development of SLE. The present review summarizes the information previously reported about the involvement of IL-10 and TNFα genetic variants on SLE appearance, clinical phenotype, and outcome. We show that, in spite of the heterogeneity of the populations studied, the existing knowledge points towards a relevant role of IL-10 and TNFα genotypes in SLE.

Mucosal mast cells mediate motor response induced by chronic oral exposure to ovalbumin in the rat gastrointestinal tract

We previously demonstrated that oral chronic exposure to ovalbumin (OVA) causes intestinal hypermotility in Sprague-Dawley rats. In this study, the objective was to determine the mechanism of action of OVA and the role of mucosal mast cells in the regulation of motor activity in this model. Rats were orally exposed to OVA during 6 weeks. Intestinal mucosal mast cells (IMMCs) were counted and rat mast cell protease II (RMCPII) measured in duodenum, jejunum, ileum and colon. Anti-OVA IgE, IgG, and IL-4 were measured in serum. Eosinophils and IgE(+) cells were counted in jejunum. In an additional study rats were treated with the mast cell stabilizer ketotifen and mast cell number, RMCPII concentration and motor activity in vitro were evaluated. OVA exposed rats showed an increase in mucosal mast cell number and in RMCPII content in small intestine and colon. However, variables of a Th(2) type response were not affected by exposure to OVA: (i) neither OVA specific IgE nor IgG were found; (ii) IL-4 did not increase and, (iii) the number of eosinophils and IgE(+) cells was identical in the exposed and unexposed groups. These results brought us to hypothesize a possible non-Ig-mediated action of OVA on mast cells. Ketotifen significantly diminished the response to OVA: Ketotifen reduced the number of mast cells and the RMCPII content and blocked increased intestinal contractility. In addition ketotifen modified motor response in both OVA exposed and unexposed animals giving evidence of the importance of mast cells in intestine motor activity driving.

A20 attenuates allergic airway inflammation in mice

TNF receptor 1 can activate signaling pathways leading to the activation of NF-kappaB. A20, an NF-kappaB-inducible protein, negatively regulates these signaling pathways and acts as an anti-inflammatory mediator. Therefore, A20 is viewed as a potential therapeutic target for inflammatory disease. In this study, we examined the effect of A20 on an OVA-induced allergic airway inflammation model in mice. We used an adenovirus containing A20 cDNA (Ad-A20) that was delivered intratracheally before OVA challenge. Single administration of Ad-A20 reduced airway inflammatory cell recruitment and peribronchiolar inflammation and suppressed the production of various cytokines in bronchoalveolar fluid. In addition, Ad-A20 suppressed mucus production and prevented the development of airway hyperresponsiveness. The protective effect of Ad-A20 was mediated by the inhibition of the NF-kappaB signaling pathway. Taken together, our results suggest that the development of an immunoregulatory strategy based on A20 may have therapeutic potential for the treatment of allergic asthma.

Mouse models of asthma: a comparison between C57BL/6 and BALB/c strains regarding bronchial responsiveness, inflammation, and cytokine production

OBJECTIVE

Animal models of asthma mimic major features of human disease. Since the genetic background of experimental animals might affect hyperresponsiveness and inflammation, we studied its potential influence and the mechanisms leading to differences in strains.

METHODS

We applied a mouse model of allergic asthma to BALB/c and C57BL/6 mice.

RESULTS

BALB/c mice displayed greater levels of airway reactivity to methacholine than C57BL/6 mice. Moreover, BALB/c mice exhibited higher numbers of mast cells in lung tissue when compared to C57BL/6. On the contrary, eosinophil and neutrophil counts in bronchoalveolar lavage fluid (BALF) as well as peribronchial eosinophilia were greater in C57BL/6. IL (Interleukin)-4, IL-5, IL-13, and CCL11 levels measured in whole-lung extracts were higher in BALB/c, while, in sharp contrast, CCL11 and CCL5 levels were higher in BALF of C57BL/6 mice.

CONCLUSIONS

We observed phenotypic differences between C57BL/6 and BALB/c mice in an asthma model with different distributions of pro-inflammatory cytokines and inflammatory cells.

Etanercept prevents airway hyperresponsiveness by protecting neuronal M2 muscarinic receptors in antigen-challenged guinea pigs

BACKGROUND AND PURPOSE

Increased tumour necrosis factor-alpha (TNF-alpha) is associated with airway hyperreactivity in antigen-challenged animals. In human asthmatics, TNF-alpha is increased and blocking it prevents airway hyperreactivity in some asthmatic patients. However, the mechanisms by which TNF-alpha mediates hyperreactivity are unknown. Airway hyperreactivity can be caused by dysfunction of neuronal M(2) muscarinic receptors that normally limit acetylcholine release from parasympathetic nerves. Here we test whether blocking TNF-alpha receptors with etanercept prevents M(2) receptor dysfunction and airway hyperreactivity in antigen-challenged guinea pigs.

EXPERIMENTAL APPROACH

Ovalbumin-sensitized guinea pigs were challenged by inhalation of antigen. Some animals received etanercept (3 mg kg(-1) i.p.) 3 h before challenge. 24 h after challenge, airway hyperreactivity and M(2) receptor function were tested. Inflammatory cells in bronchoalveolar lavage, blood and lung were counted. TNF-alpha and its receptors were detected by real-time RT-PCR and immunocytochemistry in parasympathetic nerves from humans and guinea pigs and in human neuroblastoma cells.

KEY RESULTS

Antigen-challenged animals were hyperreactive to vagal stimulation and neuronal M(2) receptors were dysfunctional. Both M(2) receptor dysfunction and airway hyperreactivity were prevented by etanercept. Etanercept reduced eosinophils around airway nerves, and in blood, bronchoalveolar lavage and airway smooth muscle. Also, TNF-alpha decreased M(2) receptor mRNA in human and guinea pig parasympathetic neurons.

CONCLUSIONS AND IMPLICATIONS

Tumour necrosis factor-alpha may contribute to M(2) receptor dysfunction and airway hyperreactivity directly by decreasing receptor expression and indirectly by promoting recruitment of eosinophils, containing major basic protein, an M(2) antagonist. This suggests that etanercept may be beneficial in treatment of allergic asthma.

Tumor necrosis factor-alpha is a common genetic risk factor for asthma, juvenile rheumatoid arthritis, and systemic lupus erythematosus in a Mexican pediatric population

There is a great deal of evidence that points to the association of the tumor necrosis factor-alpha (TNF-alpha) gene as a common genetic factor in the pathogenesis of diseases that are caused by inflammatory and/or autoimmune etiologies. Two single nucleotide polymorphisms (SNPs) identified in the TNF-alpha promoter region have been associated with disease susceptibility and severity. We investigated whether -308G/A and -238G/A TNF-alpha polymorphisms were associated with asthma, systemic lupus erythematosus (SLE), and juvenile rheumatoid arthritis (JRA) in a pediatric Mexican population. In a case-control study of 725 patients (asthma: 226, JRA: 171, and SLE: 328) and 400 control subjects, the participants were analyzed using the allelic discrimination technique. The genotype distribution of both TNF-alpha polymorphisms was in Hardy-Weinberg equilibrium in each group. However, there were significant differences in the allele frequency of TNF-alpha-308A between the patients and the healthy controls. This allele was detected in 2.9% of the controls, 6.0% of asthmatic and JRA patients (p = 0.002 and p = 0.0086), and 6.7% of SLE patients (p = 0.00049); statistical significance was maintained after ancestry stratification (asthma: p = 0.0143, JRA: p = 0.0083, and SLE: p = 0.0026). Stratification by gender showed that the risk for the -308A allele in asthma and JRA was greater in females (OR = 4.16, p = 0.0008 and OR = 4.4, p = 0.0002, respectively). The TNF-alpha -238A allele showed an association only with JRA in males (OR = 2.89, p = 0.004). These results support the concept that the TNF-alpha gene is a genetic risk factor for asthma, SLE, and JRA in the pediatric Mexican population.

Immunomodulatory mast cells: negative, as well as positive, regulators of immunity

Mast cells can promote inflammation and other tissue changes in IgE-associated allergic disorders, as well as in certain innate and adaptive immune responses that are thought to be independent of IgE. However, mast cells can also have anti-inflammatory and immunosuppressive functions. Here, we review the evidence that mast cells can have negative, as well as positive, immunomodulatory roles in vivo, and we propose that mast cells can both enhance and later suppress certain features of an immune response.

Mechanisms of allergy and asthma

Allergies are the result of an inappropriate reaction against innocuous environmental proteins. The prevalence and severity of allergic diseases has increased dramatically during the last decade in developed countries. Allergen-specific T helper (Th) cells play a pivotal role in the pathogenesis of allergic hypersensitivity reactions. These Th cells activate a complex immune reaction that triggers the release of potent mediators and enhances the recruitment of inflammatory cells, which in turn elicit an inflammatory response that leads to the clinical symptoms of allergic disease. The current therapies for allergic diseases focus primarily on control of symptoms and suppression of inflammation, without affecting the underlying cause. However, the knowledge about the pathophysiology of allergic diseases has substantially increased, offering new opportunities for therapeutic intervention. In this review, we will focus on current insights into the mechanism of allergic reactions.

Mast cell production of IL-4 and TNF may be required for protective and pathological responses in gastrointestinal helminth infection

Expulsion of the gastrointestinal nematode Trichinella spiralis is associated with Th2 responses and intestinal inflammation, which correlate with a marked mast cell (MC) response. To address the role of MC-derived cytokines in the induction of protective responses, WBB6F1-KitW/KitW-v (W/W(v)) mice were reconstituted with wild-type, tumor necrosis factor (TNF)-alpha(-/-), or interleukin (IL)-4(-/-) bone marrow (BM) prior to infection with T. spiralis. W/W(v) mice reconstituted with TNF-alpha(-/-) or IL-4(-/-) BM expelled the parasite less efficiently and showed diminished enteropathy, whereas protective responses were normal in W/W(v) mice reconstituted with wild-type BM and were accompanied by intestinal pathology. MC responses were reduced in W/W(v) mice reconstituted with IL-4(-/-) BM and to a lesser extent when reconstituted with TNF-alpha(-/-). These results suggest that MC-derived IL-4 and TNF may regulate the induction of protective Th2 responses and intestinal inflammation associated with the expulsion of T. spiralis. Significantly, these studies suggest a role for MC-derived cytokines as autocrine growth factors.

SCF and IL-31 rather than IL-17 and BAFF are potential indicators in patients with allergic asthma

BACKGROUND

Although the prevalence of allergic asthma increased quickly in the past decade, the diagnostic criteria have not been well established. The aim of the present study was to explore whether stem cell factor (SCF), B cell-activating factor (BAFF), and cytokines interleukin (IL)-17 and IL-31 are usable parameters for the diagnosis of allergic asthmatics.

METHODS

Blood samples were collected from patients with allergic asthma, control patients, and healthy control subjects. The serum concentrations of SCF, BAFF, IL-17, and IL-31 were measured by enzyme-linked immunosorbent assay. The corresponding mRNA levels in peripheral blood mononuclear cells (PBMCs) were determined by real-time reverse-transcription polymerase chain reaction.

RESULTS

A good correlation existed between protein levels of SCF and IL-31 and their mRNA levels (SCF: r = 0.6162; IL-31: r = 0.5463). The serum concentrations of SCF and IL-31 in allergic asthmatic patients, but not control patients, were significantly higher than those in normal control subjects (SCF: median 1.83 vs 0.85 ng/ml, P < 0.01; IL-31: 50.15 vs 10.01 pg/ml, P < 0.001). Consistently, the levels of SCF and IL-31 mRNAs in allergic asthmatic patients' PBMCs were also significantly higher than those in normal control subjects (P = 0.002 and P < 0.001, respectively).

CONCLUSIONS

These findings suggest that allergic asthma is characterized by an elevation of cytokines SCF and IL-31 and the measurement of their expression at either protein level in serum or mRNA level in PBMCs will be a valuable parameter for the diagnosis of allergic asthma.