The Role of Toll-Like Receptors and Myeloid Differentiation Factor 88 in Bjerkandera adusta-Induced Lung Inflammation

Co-exposure of peptidoglycan and heat-inactivated Asian sand dust exacerbates ovalbumin-induced allergic airway inflammation in mice

AIMS

Asian sand dust (ASD) comprises soil particles, microorganisms, and various chemical components. We examined whether peptidoglycan (PGN), a structural cell wall component of Gram-positive bacteria, exacerbates ASD-induced allergic airway inflammation in mice.

METHODS

The ASD (median diameter ∼4 µm) used was a certified reference material from the National Institute for Environmental Studies in Japan, derived from Gobi Desert surface soil collected in 2011. BALB/c mice were intratracheally exposed to PGN, heat-inactivated ASD (H-ASD), and ovalbumin (OVA), individually and in combination. Twenty-four hours after the final intratracheal administration, bronchoalveolar lavage fluid (BALF) and serum samples were collected. Inflammatory cell count, cytokine levels in the BALF, OVA-specific immunoglobulin levels in the serum, and pathological changes in the lungs were analyzed.

RESULTS AND DISCUSSION

After OVA + PGN + H-ASD treatment, the number of eosinophils, neutrophils, and macrophages in the BALF and of eosinophils in the lung tissue was significantly higher than that after OVA + PGN or OVA + H-ASD treatment. Moreover, levels of chemokines and cytokines associated with eosinophil recruitment and activation were significantly higher in the BALF of this group than in that of the OVA + PGN group, and tended to be higher than those in the OVA + H-ASD group. Pathological changes in the lungs were most severe in mice treated with OVA + PGN + H-ASD.

CONCLUSIONS

Our results indicate that PGN is involved in the exacerbation of ASD-induced allergic airway inflammation in mice. Thus, inhalation of ASD containing Gram-positive bacteria may trigger allergic bronchial asthma.

Different Airway Inflammatory Phenotypes Correlate with Specific Fungal and Bacterial Microbiota in Asthma and Chronic Obstructive Pulmonary Disease

Background

Studies of chronic airway inflammatory diseases have increasingly focused on airway microbiota. However, the microbiota characteristics of asthma and chronic obstructive pulmonary disease (COPD) patients with different airway inflammatory phenotypes remain unclear.

Objective

We aimed to reveal the differences of fungal and bacterial microbiota between eosinophilic asthma (EA) and noneosinophilic asthma (NEA) patients and between eosinophilic COPD (EC) and noneosinophilic COPD (NEC) patients. Further, explore whether similarities exist in the airway microbiota of patients with the same phenotype.

Methods

Induced sputum samples were collected from 45 asthma subjects and 39 COPD subjects. The airway microbiota of the subjects was profiled by nearly full-length 16S rRNA and internal transcribed space (ITS) sequencing.

Results

Subjects with eosinophilic phenotype (EA and EC) showed significant differences in both fungal and bacterial microbiota compared to the corresponding subjects with noneosinophilic phenotype (NEA and NEC). In addition, no differences were observed between the fungal microbiota of subjects with the same phenotype (EA vs. EC, NEA vs. NEC). In bacterial microbiota, the greater relative abundance of Streptococcus thermophilus was observed in EA and EC subjects, while Ochrobactrum was enriched in NEA and NEC subjects. In fungal microbiota, the EA and EC subjects showed higher relative abundances of Aspergillus and Bjerkandera, while the NEA and NEC subjects were enriched in Rhodotorula and Papiliotrema.

Conclusions

Different airway inflammatory phenotypes were related to specific fungal and bacterial microbiota in both asthma and COPD, while the same airway inflammatory phenotype revealed a degree of similarity in airway microbiota, particularly in fungal microbiota.

Screening of Antiviral Components of Ma Huang Tang and Investigation on the Ephedra Alkaloids Efficacy on Influenza Virus Type A

Although Ma Huang Tang (MHT) has long been considered as a classical formula for respiratory infections like influenza, bronchitis and asthma, its chemical ingredients that really exert the main efficacy are still obscure. In this study we aimed to screen its antiviral components and investigate the potential mechanisms. The MDCK cellular research results showed that, among nine predominant ingredients of MHT, L-methylephedrin (LMEP), L-ephedrine (LEP) and D-pseudo- ephedrine (DPEP) significantly inhibited the proliferation of influenza A virus in vitro, and the inhibitory effect at 24 h after the treatment was more obvious than that at 48 h. They also significantly inhibited the mRNA expression levels of related genes in the TLR3, TLR4 and TLR7 signaling pathways, which were accompanied with the down-regulation of TNF-α level and the up-regulation of IFN-β level in the cell supernatant. Therefore, three Ephedra alkaloids exert an antiviral effect in vitro which may be closely related to the inhibition of viral replication and the modulation of inflammatory response. Animal research further indicated, at the 3rd and 7th days after infection, LEP and DPEP significantly attenuated lung injury, decreased lung index, virus load in the lung and the level of IL-1β in serum, inhibited the mRNA expression levels of TNF-α, TLR3, TLR4, TLR7, MyD88, NF-κB p65 and RIG-1 as well as the protein expression levels of TLR4, TLR7, MyD88 and NF-κB p65 and markedly increased thymus index, the level of IL-10 in serum and the mRNA expression level of IFN-γ. LEP and DPEP have certain protective effects on the influenza virus-infected mice, which may be associated with their abilities of effectively alleviating lung injury, improving the immunologic function of infected mice and adjusting the host's TLRs and RIG-1 pathways. The overall findings demonstrate that, as effective and inexpensive natural substances, Ephedra alkaloids and MHT may have potential utility in clinical management.

Saccharomyces cerevisiae β-glucan-induced SBD-1 expression in ovine ruminal epithelial cells is mediated through the TLR-2-MyD88-NF-κB/MAPK pathway

Ovine ruminal epithelial cells (ORECs) not only have a physical barrier function but also can secrete host defence peptides (HDPs), such as sheep β-defensin-1 (SBD-1). As a feed additive, Saccharomyces cerevisiae can enhance the host's innate immunity. β-glucan, a cell wall component of Saccharomyces cerevisiae, can stimulate innate immune responses and trigger the up-regulation of SBD-1 in ORECs. The signaling mechanisms involved in β-glucan-induced SBD-1 expression are not completely understood. The aim of this study was to identify the receptors and intracellular pathways involved in the up-regulation of SBD-1 induced by β-glucan. ORECs were cultured, and the regulatory mechanisms of β-glucan-induced up-regulation of SBD-1 were detected using quantitative real-time PCR (qPCR), enzyme-linked immunosorbent assay (ELISA), and western blotting. TLR-2 and MyD88 knockdown or inhibition attenuated β-glucan-induced SBD-1 expression. We also showed that inhibition of MAPK and NF-κB pathways significantly reduced β-glucan-induced SBD-1 expression. These results demonstrate that β-glucan-induced SBD-1 expression is TLR-2-MyD88-dependent and may be regulated by both MAPK and NF-κB pathways. Since NF-κB inhibition had a greater effect on the down-regulation of β-glucan-induced SBD-1 expression, the NF-κB pathway may be the dominant signaling pathway involved in the regulation of defensin expression. Our studies demonstrate that β-glucan-induced SBD-1 expression is mediated through the TLR-2-MyD88-NF-κB/MAPK pathway. Our results would contribute to the understanding of immunological modulations in the gastrointestinal tract triggered by probiotic yeast cell wall components.

Biological effects of airborne fine particulate matter (PM2.5) exposure on pulmonary immune system

Airborne fine particulate matter (PM_2.5) attracts more and more attention due to its environmental effects. The immune system appears to be a most sensitive target organ for the environmental pollutants. Inhaled PM_2.5 can deposit in different compartments in the respiratory tract and interact with epithelial cells and resident immune cells. Exposed to PM_2.5 can induce local or systematic inflammatory responses. This review focus on the effects of respiratory tract exposed to PM_2.5. Firstly, we introduced the major emission sources, basic characteristics of PM_2.5 and discussed its immunoadjuvant potential. Secondly, we elaborated the immune cells in the respiratory tract and the deposition of PM_2.5 regarding the structural characteristics of the respiratory tract. Furthermore, we summarized the in vivo/vitro studies that revealed the immunotoxic effects of PM_2.5 exposure to pulmonary cellular effectors and explored the contribution of PM_2.5 exposure to the Th1/Th2 balance.

Antiviral effects of Ma Huang Tang against H1N1 influenza virus infection in vitro and in an ICR pneumonia mouse model

Ma Huang Tang (MHT), a classical Chinese herbal decoction which has been used in clinic for thousands of years, was very effective in treating the upper respiratory tract infection. But its activity against influenza virus A, the anti-inflammatory effect and the underlying mechanisms have been poorly investigated in previous researches. In this study, the antiviral efficacy of MHT directly inhibiting influenza virus A was investigated in vitro in MDCK cells. In an ICR pneumonia mouse model infected with influenza virus A PR/8/34, MHT (8, 4 and 2 g/kg) were oral administrated for 7 days after viral challenge, to evaluate the effect of MHT on ameliorating viral pneumonia and decipher the underlying mechanisms. The in vitro results showed that MHT possessed antiviral activity with low toxicity. The in vivo assays showed that MHT (8 and 4 g/kg) significantly attenuated lung histopathological changes, decreased lung index, interleukin (IL)-4,5, tumor necrosis factor alpha (TNF-α), CD3⁺, CD8⁺ T cell levels, increased IL-2, gamma interferon (IFN-γ), CD4⁺ T cell levels and CD4⁺/CD8⁺ ratio, inhibited toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and tumor necrosis factor receptor associated factor 6 (TRAF6) protein levels. All these results demonstrate that MHT can strikingly ameliorate influenza virus A pneumonia in mice, which is associated with the regulating effect of MHT in the imbalance of body's immune function and the MyD88-dependent signaling pathway of TLR4.

X-linked TLR7 gene polymorphisms are associated with diverse immunological conditions but not with discoid lupus erythematosus in Polish patients

Introduction

Toll-like receptor 7 (TLR7) is an important molecule involved in the development of autoimmunity and the response to different pathogens. Several polymorphisms within the TLR7 gene were previously found to be associated with systemic lupus erythematosus (SLE). However, none of those studies investigated the TLR7 promoter flanking variants rs1634318 and rs1616583. TLR7 gene diversity has not been analyzed with respect to discoid lupus erythematosus (DLE) development, while its role in the human immunological response to fungal infection is not fully known.

Aim

To clarify the potential involvement of two novel single-nucleotide polymorphisms (SNPs) located in the TLR7 gene (rs1634318 and rs1616583) in a variety of immune-related conditions, we studied the variability of these loci in patients from a Polish population with SLE and DLE, as well as in immunocompromised patients who were affected by invasive aspergillosis (IA) and those who were not affected.

Material and methods

Real-time polymerase chain reaction was used to genotype SNPs. Statistically significant differences between case and control groups for both allele and genotype frequencies were assessed using the χ² test with Yates’ correction or two-tailed Fisher’s exact test. The results were Bonferroni-corrected for multiple comparisons and odds ratios were calculated.

Results

Two polymorphisms located in TLR7 might be associated with the development of SLE but not DLE within the Polish population. Moreover, variation of the two investigated SNPs was found to be associated with IA in immunocompromised Polish patients.

Conclusions

In Polish patients, TLR7 promoter flanking gene polymorphisms might be associated with IA and SLE but not DLE.

Co-exposure to zymosan A and heat-inactivated Asian sand dust exacerbates ovalbumin-induced murine lung eosinophilia

Background

Epidemiological studies have implicated Asian sand dust (ASD) in the increased prevalence of respiratory disorders, including asthma. It has been observed that fungal elements such as β-glucan can be adsorbed onto ASD. In the present study, the exacerbating effect of the combined exposure to zymosan A (ZymA) containing yeast β-glucan and heat-inactivated ASD on ovalbumin (OVA)-induced murine lung eosinophilia was investigated.

Methods

BALB/c mice were repeatedly instilled intratracheally with one of eight immunogenic formulations consisting of various combinations of (1) ZymA, (2) ASD that was briefly heated to remove organic substances (H-ASD), and (3) OVA in normal saline, or each of the above alone. Pathologic changes, cytological alterations in bronchoalveolar lavage fluid (BALF), changes in inflammatory cytokines and chemokines in BALF, and OVA-specific IgE and IgG₁ antibodies in serum were investigated.

Results

Exposure to ZymA with or without OVA had no effect on most indicators of lung inflammation. Exposure to H-ASD with OVA increased the recruitment of inflammatory cells to the lungs and the serum levels of OVA-specific IgE and IgG₁. The combination OVA + ZymA + H-ASD induced a marked recruitment of eosinophils and upregulation of T helper 2 (Th2) cytokines (interleukin [IL]-4 and IL-13), IL-6, eotaxin/CCL11, and monocyte chemotactic protein (MCP)-3/CCL7 in BALF and OVA-specific IgE in serum. This treatment also induced the most severe pathological changes in the lungs of mice. ZymA was found to boost the effects of H-ASD, thereby exacerbating the OVA-induced allergic inflammation, even though ZymA alone did not have such effect.

Conclusions

The results suggest that fungal elements such as β-1,3-glucan aggravate the allergic inflammation caused by ASD. Our findings may facilitate prophylaxis of some allergic diseases in Asia.

Biological factor related to Asian sand dust particles contributes to the exacerbation of asthma

Epidemiologic studies have revealed that Asian sand dust particles (ASDs) can affect respiratory and immune health represented by asthma. Factors responsible for the exacerbation of asthma remain unclear. The fungus Bjerkandera adusta (B.ad) and polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) have been identified in ASDs collected from the atmosphere when an ASD event occurred. We investigated the effects of B.ad and BaP related to ASDs on respiratory and immune systems. Bone marrow-derived antigen-presenting cells (APCs) and splenocytes from atopic prone NC/Nga mice and human airway epithelial cells were exposed to the B.ad or to BaP in the presence and absence of heated-ASDs (H-ASDs). B.ad and BaP in both the presence and absence of H-ASDs increased the expression of cell surface molecules on APCs. H-ASDs alone slightly activated APCs. The expressions induced by B.ad were higher than those induced by BaP in the presence and absence of H-ASDs. There were no remarkable effects on the activation of splenocytes or the proinflammatory responses in airway epithelial cells. These results suggest that B.ad rather than BaP contributes to the exacerbation of asthma regardless of the presence or absence of sand particles, particularly by the activation of the immune system via APCs. Copyright © 2016 John Wiley & Sons, Ltd.