The role of toll-like receptors in acute and chronic lung inflammation

Transcobalamin 2 orchestrates monocyte proliferation and TLR4-driven inflammation in systemic lupus erythematosus via folate one-carbon metabolism

Background

SLE is a complex autoimmune disease with deleterious effects on various organs. Accumulating evidence has shown abnormal vitamin B12 and one-carbon flux contribute to immune dysfunction. Transcobalamin II (TCN2) belongs to the vitamin B12-binding protein family responsible for the cellular uptake of vitamin B12. The role of TCN2 in SLE is still unclear.

Methods

We collected clinical information and blood from 51 patients with SLE and 28 healthy controls. RNA sequencing analysis, qPCR, and western blot confirmed the alteration of TCN2 in disease monocytes. The correlation between TCN2 expression and clinical features and serological abnormalities was analyzed. TCN2 heterozygous knockout THP1 cells were used to explore the effects of TCN2 dysfunction on monocytes. CCK-8 assay and EdU staining were used to detect cell proliferation. ELISA was conducted to assess vitamin B12, glutathione, and cytokines changes. UHPLC-MRM-MS/MS was used to detect changes in the intermediates of the one-carbon cycle. Flow cytometry is used to detect cell cycle, ROS, mitoROS, and CD14 changes.

Results

Elevated TCN2 in monocytes was correlated positively with disease progression and specific tissue injuries. Using CD14+ monocytes and TCN2 genetically modified THP1 cell lines, we found that the TCN2 was induced by LPS in serum from SLE patients. TCN2 heterozygous knockout inhibited cellular vitamin B12 uptake and one-carbon metabolism, leading to cell proliferation arrest and decreased Toll-like receptor 4 (TLR4)-mediated CCL2 release. Methionine cycle metabolites, s-adenosylmethionine and homocysteine, rescued these effects, whereas folate treatment proved to be ineffective. Folate deficiency also failed to replicate the impact of TCN2 downregulation on THP1 inflammatory response.

Conclusion

Our study elucidated the unique involvement of TCN2-driven one-carbon flux on SLE-associated monocyte behavior. Increased TCN2 may promote disease progression and tissue damage by enhancing one-carbon flux, fostering monocyte proliferation, and exacerbating TLR4 mediated inflammatory responses. The inhibition of TCN2 may be a promising therapeutic approach to ameliorate SLE.

Regulation of immune responses to infection through interaction between stem cell-derived exosomes and toll-like receptors mediated by microRNA cargoes

Infectious diseases are among the factors that account for a significant proportion of disease-related deaths worldwide. The primary treatment approach to combat microbial infections is the use of antibiotics. However, the widespread use of these drugs over the past two decades has led to the emergence of resistant microbial species, making the control of microbial infections a serious challenge. One of the most important solutions in the field of combating infectious diseases is the regulation of the host's defense system. Toll-like receptors (TLRs) play a crucial role in the first primary defense against pathogens by identifying harmful endogenous molecules released from dying cells and damaged tissues as well as invading microbial agents. Therefore, they play an important role in communicating and regulating innate and adaptive immunity. Of course, excessive activation of TLRs can lead to disruption of immune homeostasis and increase the risk of inflammatory reactions. Targeting TLR signaling pathways has emerged as a new therapeutic approach for infectious diseases based on host-directed therapy (HDT). In recent years, stem cell-derived exosomes have received significant attention as factors regulating the immune system. The regulation effects of exosomes on the immune system are based on the HDT strategy, which is due to their cargoes. In general, the mechanism of action of stem cell-derived exosomes in HDT is by regulating and modulating immunity, promoting tissue regeneration, and reducing host toxicity. One of their most important cargoes is microRNAs, which have been shown to play a significant role in regulating immunity through TLRs. This review investigates the therapeutic properties of stem cell-derived exosomes in combating infections through the interaction between exosomal microRNAs and Toll-like receptors.

The Interaction of HMGB1 with the Proinflammatory TREM-1 Receptor Generates Cytotoxic Lymphocytes Active against HLA-Negative Tumor Cells

High mobility group protein (HMGB1) is secreted by myeloid cells and cells of damaged tissues during inflammation, causing inflammatory reactions through various receptors, including TLRS and RAGE. TREM-1 is considered to be one of the potential HMGB1 receptors. In this work, we have shown that the HMGB1 protein is able to bind to the TREM-1 receptor at high affinity both in solution and on the cell surface. This binding causes lymphocytes to release cytokines IL-2, IL-1b, IL-6, TNF and Ifny into the medium, which leads to the appearance of cytotoxic lymphocytes in PBMC capable of lysing HLA-negative tumor cells. Expanding the spectra of proinflammatory receptor ligands and understanding the mechanisms of their action is essential for the creation of new immunotherapy pathways.

Green Extracts with Metal-based Nanoparticles for Treating Inflammatory Diseases: A Review

Globally, high death rates and poor quality of life are caused mainly by inflammatory diseases. Corticosteroids, which may have systemic side effects and would enhance the risk of infection, are the common forms of therapy. The field of nanomedicine has created composite nanoparticles that carry a pharmacological carrier and target ligands for distribution to sites of inflammation with less systemic toxicity. However, their relatively large size often causes systemic clearance. An interesting approach is metal-based nanoparticles that naturally reduce inflammation. They are made not only to be small enough to pass through biological barriers but also to allow label-free monitoring of their interactions with cells. The following literature review discusses the mechanistic analysis of the anti-inflammatory properties of several metal-based nanoparticles, including gold, silver, titanium dioxide, selenium, and zinc oxide. Current research focuses on the mechanisms by which nanoparticles infiltrate cells and the anti-inflammatory techniques using herbal extracts-based nanoparticles. Additionally, it provides a brief overview of the literature on many environmentally friendly sources employed in nanoparticle production and the mechanisms of action of various nanoparticles.

Emerging role of immune cells as drivers of pulmonary fibrosis

The pathogenesis of pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF) and other forms of interstitial lung disease, involves a complex interplay of various factors including host genetics, environmental pollutants, infection, aberrant repair and dysregulated immune responses. Highly variable clinical outcomes of some ILDs, in particular IPF, have made it difficult to identify the precise mechanisms involved in disease pathogenesis and thus the development of a specific cure or treatment to halt and reverse the decline in patient health. With the advent of in-depth molecular diagnostics, it is becoming evident that the pathogenesis of IPF is unlikely to be the same for all patients and therefore will likely require different treatment approaches. Chronic inflammation is a cardinal feature of IPF and is driven by both innate and adaptive immune responses. Inflammatory cells and activated fibroblasts secrete various pro-inflammatory cytokines and chemokines that perpetuate the inflammatory response and contribute to the recruitment and activation of more immune cells and fibroblasts. The balance between pro-inflammatory and regulatory immune cell subsets, as well as the interactions between immune cell types and resident cells within the lung microenvironment, ultimately determines the extent of fibrosis and the potential for resolution. This review examines the role of the innate and adaptive immune responses in pulmonary fibrosis, with an emphasis on IPF. The role of different immune cell types is discussed as well as novel anti-inflammatory and immunotherapy approaches currently in clinical trial or in preclinical development.

Shedding light on the molecular and regulatory mechanisms of TLR4 signaling in endothelial cells under physiological and inflamed conditions

Toll-like receptor 4 (TLR4) are part of the innate immune system. They are capable of recognizing pathogen-associated molecular patterns (PAMPS) of microbes, and damage-associated molecular patterns (DAMPs) of damaged tissues. Activation of TLR4 initiates downstream signaling pathways that trigger the secretion of cytokines, type I interferons, and other pro-inflammatory mediators that are necessary for an immediate immune response. However, the systemic release of pro-inflammatory proteins is a powerful driver of acute and chronic inflammatory responses. Over the past decades, immense progress has been made in clarifying the molecular and regulatory mechanisms of TLR4 signaling in inflammation. However, the most common strategies used to study TLR4 signaling rely on genetic manipulation of the TLR4 or the treatment with agonists such as lipopolysaccharide (LPS) derived from the outer membrane of Gram-negative bacteria, which are often associated with the generation of irreversible phenotypes in the target cells or unintended cytotoxicity and signaling crosstalk due to off-target or pleiotropic effects. Here, optogenetics offers an alternative strategy to control and monitor cellular signaling in an unprecedented spatiotemporally precise, dose-dependent, and non-invasive manner. This review provides an overview of the structure, function and signaling pathways of the TLR4 and its fundamental role in endothelial cells under physiological and inflammatory conditions, as well as the advances in TLR4 modulation strategies.

Human amniotic mesenchymal stem cell-conditioned medium inhibited LPS-induced cell injury and inflammation by modulating CD14/TLR4-mediated signaling pathway in monocytes

Human amniotic mesenchymal stem cells (hAMSCs) have attracted considerable attention as a promising regenerative therapy. Many studies reported that the conditioned medium of hAMSCs (AM-CM) exerted anti-inflammatory and immunomodulatory functions, while its underlying mechanism is poorly understood. In this study, we first confirmed that AM-CM (25%, 50%, 100%) was optimal for anti-inflammation at 24 h. Lipopolysaccharide (LPS)-induced alteration of cell morphology, the decrease of cell proliferation, and the upregulation of cell apoptosis were significantly reversed in AM-CM-treated THP-1 cells. 25% and 50% AM-CM significantly decreased LPS-induced intracellular reactive oxygen species (ROS) production and proinflammatory cytokines secretion. Mechanistically, we found that AM-CM treatment suppressed LPS-induced activation of MAPK and NF-κB pathways by inhibiting CD14/TLR4 in THP-1 cells. Meanwhile, activation of NLRP3 inflammasome was also dose-dependently attenuated by AM-CM treatment. Thus, AM-CM may exert positive influences on the inflammation microenvironment and provide a novel strategy for improving tissue regeneration.

In silico design of a polypeptide as a vaccine candidate against ascariasis

Ascariasis is the most prevalent zoonotic helminthic disease worldwide, and is responsible for nutritional deficiencies, particularly hindering the physical and neurological development of children. The appearance of anthelmintic resistance in Ascaris is a risk for the target of eliminating ascariasis as a public health problem by 2030 set by the World Health Organisation. The development of a vaccine could be key to achieving this target. Here we have applied an in silico approach to design a multi-epitope polypeptide that contains T-cell and B-cell epitopes of reported novel potential vaccination targets, alongside epitopes from established vaccination candidates. An artificial toll-like receptor-4 (TLR4) adjuvant (RS09) was added to improve immunogenicity. The constructed peptide was found to be non-allergic, non-toxic, with adequate antigenic and physicochemical characteristics, such as solubility and potential expression in Escherichia coli. A tertiary structure of the polypeptide was used to predict the presence of discontinuous B-cell epitopes and to confirm the molecular binding stability with TLR2 and TLR4 molecules. Immune simulations predicted an increase in B-cell and T-cell immune response after injection. This polypeptide can now be validated experimentally and compared to other vaccine candidates to assess its possible impact in human health.

Toll-like Receptors and Thrombopoiesis

Platelets are the second most abundant blood component after red blood cells and can participate in a variety of physiological and pathological functions. Beyond its traditional role in hemostasis and thrombosis, it also plays an indispensable role in inflammatory diseases. However, thrombocytopenia is a common hematologic problem in the clinic, and it presents a proportional relationship with the fatality of many diseases. Therefore, the prevention and treatment of thrombocytopenia is of great importance. The expression of Toll-like receptors (TLRs) is one of the most relevant characteristics of thrombopoiesis and the platelet inflammatory function. We know that the TLR family is found on the surface or inside almost all cells, where they perform many immune functions. Of those, TLR2 and TLR4 are the main stress-inducing members and play an integral role in inflammatory diseases and platelet production and function. Therefore, the aim of this review is to present and discuss the relationship between platelets, inflammation and the TLR family and extend recent research on the influence of the TLR2 and TLR4 pathways and the regulation of platelet production and function. Reviewing the interaction between TLRs and platelets in inflammation may be a research direction or program for the treatment of thrombocytopenia-related and inflammatory-related diseases.

Effects of a nutritional intervention on impaired behavior and cognitive function in an emphysematous murine model of COPD with endotoxin-induced lung inflammation

One cluster of the extrapulmonary manifestations in chronic obstructive pulmonary disease (COPD) is related to the brain, which includes anxiety, depression and cognitive impairment. Brain-related comorbidities are related to worsening of symptoms and increased mortality in COPD patients. In this study, a murine model of COPD was used to examine the effects of emphysema and repetitive pulmonary inflammatory events on systemic inflammatory outcomes and brain function. In addition, the effect of a dietary intervention on brain-related parameters was assessed. Adult male C57Bl/6J mice were exposed to elastase or vehicle intratracheally (i.t.) once a week on three consecutive weeks. Two weeks after the final administration, mice were i.t. exposed to lipopolysaccharide (LPS) or vehicle for three times with a 10 day interval. A dietary intervention enriched with omega-3 PUFAs, prebiotic fibers, tryptophan and vitamin D was administered from the first LPS exposure onward. Behavior and cognitive function, the degree of emphysema and both pulmonary and systemic inflammation as well as blood-brain barrier (BBB) integrity and neuroinflammation in the brain were assessed. A lower score in the cognitive test was observed in elastase-exposed mice. Mice exposed to elastase plus LPS showed less locomotion in the behavior test. The enriched diet seemed to reduce anxiety-like behavior over time and cognitive impairments associated with the presented COPD model, without affecting locomotion. In addition, the enriched diet restored the disbalance in splenic T-helper 1 (Th1) and Th2 cells. There was a trend toward recovering elastase plus LPS-induced decreased expression of occludin in brain microvessels, a measure of BBB integrity, as well as improving expression levels of kynurenine pathway markers in the brain by the enriched diet. The findings of this study demonstrate brain-associated comorbidities - including cognitive and behavioral impairments - in this murine model for COPD. Although no changes in lung parameters were observed, exposure to the specific enriched diet in this model appeared to improve systemic immune disbalance, BBB integrity and derailed kynurenine pathway which may lead to reduction of anxiety-like behavior and improved cognition.

HumanMine: advanced data searching, analysis and cross-species comparison

HumanMine (www.humanmine.org) is an integrated database of human genomics and proteomics data that provides a powerful interface to support sophisticated exploration and analysis of data compiled from experimental, computational and curated data sources. Built using the InterMine data integration platform, HumanMine includes genes, proteins, pathways, expression levels, Single nucleotide polymorphism (SNP), diseases and more, integrated into a single searchable database. HumanMine promotes integrative analysis, a powerful approach in modern biology that allows many sources of evidence to be analysed together. The data can be accessed through a user-friendly web interface as well as a powerful, scriptable web service Application programming interface (API) to allow programmatic access to data. The web interface includes a useful identifier resolution system, sophisticated query options and interactive results tables that enable powerful exploration of data, including data summaries, filtering, browsing and export. A set of graphical analysis tools provide a rich environment for data exploration including statistical enrichment of sets of genes or other biological entities. HumanMine can be used for integrative multistaged analysis that can lead to new insights and uncover previously unknown relationships.

Database URL: https://www.humanmine.org

Emerging Insights into the Impact of Air Pollution on Immune-Mediated Asthma Pathogenesis

PURPOSE OF REVIEW

Increases in ambient levels of air pollutants have been linked to lung inflammation and remodeling, processes that lead to the development and exacerbation of allergic asthma. Conventional research has focused on the role of CD4+ T helper 2 (TH2) cells in the pathogenesis of air pollution-induced asthma. However, much work in the past decade has uncovered an array of air pollution-induced non-TH2 immune mechanisms that contribute to allergic airway inflammation and disease.

RECENT FINDINGS

In this article, we review current research demonstrating the connection between common air pollutants and their downstream effects on non-TH2 immune responses emerging as key players in asthma, including PRRs, ILCs, and non-TH2 T cell subsets. We also discuss the proposed mechanisms by which air pollution increases immune-mediated asthma risk, including pre-existing genetic risk, epigenetic alterations in immune cells, and perturbation of the composition and function of the lung and gut microbiomes. Together, these studies reveal the multifaceted impacts of various air pollutants on innate and adaptive immune functions via genetic, epigenetic, and microbiome-based mechanisms that facilitate the induction and worsening of asthma.

N-Terminal Peptide of PGLYRP1/Tag7 Is a Novel Ligand for TREM-1 Receptor

An investigation of innate immunity receptors sheds light on the mechanisms of inflammation and associated immune reactions. One of the key immune regulators is the TREM-1 receptor, which is involved in both inflammation and antitumor immune response. In this article, we have obtained a new ligand for the TREM-1 receptor. The peptide, named N3, is a part of the innate immune protein PGLYRP1/Tag7. It is responsible for activating the TREM-1 signaling pathway. Here, we have demonstrated that the N3 peptide acts like other TREM-1 receptor ligands: its binding results in a mild inflammation response and appearance of cytotoxic lymphocytes. We have shown that cytotoxic populations of lymphocytes in N3 peptide-treated PBMCs are similar to those treated with Tag7 or Hsp70. We also determined the part of the N3 peptide responsible for binding to TREM-1. The resulting peptide (N9) consists of nine amino acids and can be considered as a potential peptide that blocks TREM-1 signaling.

Blocking Toll-like receptor 9 attenuates bleomycin-induced pulmonary injury

Background

Acute respiratory distress syndrome (ARDS) is one of the most common complications in coronavirus disease 2019 patients suffering from acute lung injury (ALI). In ARDS, marked distortion of pulmonary architecture has been reported. The pulmonary lesions in ARDS include hemodynamic derangements (such as alveolar edema and hemorrhage), vascular and bronchiolar damage, interstitial inflammatory cellular aggregations, and eventually fibrosis. Bleomycin induces ARDS-representative pulmonary damage in mice and rats; therefore, we used bleomycin model mice in our study. Recently, Toll-like receptor 9 (TLR9) was implicated in the development of ARDS and ALI.

Methods

In this study, we evaluated the efficiency of a TLR9 blocker (ODN2088) on bleomycin-induced pulmonary damage. We measured the apoptosis rate, inflammatory reaction, and fibroplasia in bleomycin- and bleomycin + ODN2088-treated mice.

Results

Our results showed a significant amelioration in bleomycin-induced damage to pulmonary architecture following ODN2088 treatment. A marked decrease in pulmonary epithelial and endothelial apoptosis rate as measured by cleaved caspase-3 expression, inflammatory reaction as indicated by tumor necrosis factor α expression, and pulmonary fibrosis as demonstrated by Van Gieson staining and α-smooth muscle actin immunohistochemistry were observed following ODN2088 treatment.

Conclusions

All these findings indicate that blocking downstream TLR9 signaling could be beneficial in prevention or mitigation of ARDS through hemodynamic derangements, inflammation, apoptosis, and fibrosis.

Extracellular Vesicles and Alveolar Epithelial-Capillary Barrier Disruption in Acute Respiratory Distress Syndrome: Pathophysiological Role and Therapeutic Potential

Extracellular vesicles (EVs) mediate intercellular communication by transferring genetic material, proteins and organelles between different cells types in both health and disease. Recent evidence suggests that these vesicles, more than simply diagnostic markers, are key mediators of the pathophysiology of acute respiratory distress syndrome (ARDS) and other lung diseases. In this review, we will discuss the contribution of EVs released by pulmonary structural cells (alveolar epithelial and endothelial cells) and immune cells in these diseases, with particular attention to their ability to modulate inflammation and alveolar-capillary barrier disruption, a hallmark of ARDS. EVs also offer a unique opportunity to develop new therapeutics for the treatment of ARDS. Evidences supporting the ability of stem cell-derived EVs to attenuate the lung injury and ongoing strategies to improve their therapeutic potential are also discussed.

Eosinophils mediate SIgA production triggered by TLR2 and TLR4 to control Ascaris suum infection in mice

Human ascariasis is the most prevalent but neglected tropical disease in the world, affecting approximately 450 million people. The initial phase of Ascaris infection is marked by larval migration from the host's organs, causing mechanical injuries followed by an intense local inflammatory response, which is characterized mainly by neutrophil and eosinophil infiltration, especially in the lungs. During the pulmonary phase, the lesions induced by larval migration and excessive immune responses contribute to tissue remodeling marked by fibrosis and lung dysfunction. In this study, we investigated the relationship between SIgA levels and eosinophils. We found that TLR2 and TLR4 signaling induces eosinophils and promotes SIgA production during Ascaris suum infection. Therefore, control of parasite burden during the pulmonary phase of ascariasis involves eosinophil influx and subsequent promotion of SIgA levels. In addition, we also demonstrate that eosinophils also participate in the process of tissue remodeling after lung injury caused by larval migration, contributing to pulmonary fibrosis and dysfunction in re-infected mice. In conclusion, we postulate that eosinophils play a central role in mediating host innate and humoral immune responses by controlling parasite burden, tissue inflammation, and remodeling during Ascaris suum infection. Furthermore, we suggest that the use of probiotics can induce eosinophilia and SIgA production and contribute to controlling parasite burden and morbidity of helminthic diseases with pulmonary cycles.

Nanomaterial- and shape-dependency of TLR2 and TLR4 mediated signaling following pulmonary exposure to carbonaceous nanomaterials in mice

Background

Pulmonary exposure to high doses of engineered carbonaceous nanomaterials (NMs) is known to trigger inflammation in the lungs paralleled by an acute phase response. Toll-like receptors (TLRs), particularly TLR2 and TLR4, have recently been discussed as potential NM-sensors, initiating inflammation. Using Tlr2 and Tlr4 knock out (KO) mice, we addressed this hypothesis and compared the pattern of inflammation in lung and acute phase response in lung and liver 24 h after intratracheal instillation of three differently shaped carbonaceous NMs, spherical carbon black (CB), multi-walled carbon nanotubes (CNT), graphene oxide (GO) plates and bacterial lipopolysaccharide (LPS) as positive control.

Results

The LPS control confirmed a distinct TLR4-dependency as well as a pronounced contribution of TLR2 by reducing the levels of pulmonary inflammation to 30 and 60% of levels in wild type (WT) mice. At the doses chosen, all NM caused comparable neutrophil influxes into the lungs of WT mice, and reduced levels were only detected for GO-exposed Tlr2 KO mice (35%) and for CNT-exposed Tlr4 KO mice (65%). LPS-induced gene expression was strongly TLR4-dependent. CB-induced gene expression was unaffected by TLR status. Both GO and MWCNT-induced Saa1 expression was TLR4-dependent. GO-induced expression of Cxcl2, Cxcl5, Saa1 and Saa3 were TLR2-dependent. NM-mediated hepatic acute phase response in terms of liver gene expression of Saa1 and Lcn2 was shown to depend on TLR2 for all three NMs. TLR4, in contrast, was only relevant for the acute phase response caused by CNTs, and as expected by LPS.

Conclusion

TLR2 and TLR4 signaling was not involved in the acute inflammatory response caused by CB exposure, but contributed considerably to that of GO and CNTs, respectively. The strong involvement of TLR2 in the hepatic acute phase response caused by pulmonary exposure to all three NMs deserves further investigations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00432-z.

Dual Effect of Bleomycin on Histopathological Features of Lungs and Mediastinal Fat-Associated Lymphoid Clusters in an Autoimmune Disease Mouse Model

Mediastinal fat-associated lymphoid clusters (MFALCs) are novel immune clusters that function in the pathogenesis of bleomycin (BLM)-induced pneumonitis in a C57BL/6 mouse model. However, we lack literature on the effects of BLM in an autoimmune disease mouse model (AIDM). In the present study, BLM sulfate (BLM group) or phosphate-buffered saline (PBS group) were intranasally administered in BXSB/MpJ-Yaa (Yaa) AIDM and its wild-type strains (BXSB/MpJ “BXSB”) and the histopathology of MFALCs and lungs were examined on days 7 and 21 days. Immunohistochemical analysis was performed to detect lymphatic vessels (LVs), high endothelial venules (HEVs), proliferating, and immune cells. Furthermore, the mRNA expression of Yaa locus genes (TLR7, TLR8, Arhgap6, Msl3, and Tceanc) was detected in the lung tissues. Here, we show a dual effect of BLM on intra-thoracic immune hemostasis among Yaa AIDM and its corresponding wild-type strain (BXSB mice). The BLM group of BXSB mice displayed significantly higher values of lung injury scores (LIS) and size of MFALCs as compared with the corresponding PBS group. However, an opposite effect was detected in Yaa mice. Furthermore, Yaa mice displayed decreased serum autoantibody titers and downregulated expression of TLR7, TLR8, Msl3, and Tceanc in the lungs following BLM administration, especially on day 21. Interestingly, significant positive correlations were detected in both strains between the LIS and the size of MFALCs, LVs, HEVs, and proliferating cells. Conclusively, our findings revealed a crucial function of HEVs on the extent of lung injury and the development of MFALCs in BLM-administered Yaa AIDM and control BXSB mice with dual effects. Moreover, our data suggest that down regulation of Yaa locus genes could contribute as an important attributing factor leading to decrease in the degree of autoimmunity and lung injury in AIDM. Therefore, we suggest that genetic background contributes to BLM diversity among AIDM and the wild-type strain. Targeting some genes or venules could provide novel therapeutic approaches for some autoimmune-associated respiratory diseases via controlling the MFALCs development.

Lipopolysaccharide Derived From the Lymphoid-Resident Commensal Bacteria Alcaligenes faecalis Functions as an Effective Nasal Adjuvant to Augment IgA Antibody and Th17 Cell Responses

Alcaligenes spp., including A. faecalis, is a gram-negative facultative bacterium uniquely residing inside the Peyer's patches. We previously showed that A. faecalis-derived lipopolysaccharides (Alcaligenes LPS) acts as a weak agonist of toll-like receptor 4 to activate dendritic cells and shows adjuvant activity by enhancing IgG and Th17 responses to systemic vaccination. Here, we examined the efficacy of Alcaligenes LPS as a nasal vaccine adjuvant. Nasal immunization with ovalbumin (OVA) plus Alcaligenes LPS induced follicular T helper cells and germinal center formation in the nasopharynx-associated lymphoid tissue (NALT) and cervical lymph nodes (CLNs), and consequently enhanced OVA-specific IgA and IgG responses in the respiratory tract and serum. In addition, nasal immunization with OVA plus Alcaligenes LPS induced OVA-specific T cells producing IL-17 and/or IL-10, whereas nasal immunization with OVA plus cholera toxin (CT) induced OVA-specific T cells producing IFN-γ and IL-17, which are recognized as pathogenic type of Th17 cells. In addition, CT, but not Alcaligenes LPS, promoted the production of TNF-α and IL-5 by T cells. Nasal immunization with OVA plus CT, but not Alcaligenes LPS, led to increased numbers of neutrophils and eosinophils in the nasal cavity. Together, these findings indicate that the benign nature of Alcaligenes LPS is an effective nasal vaccine adjuvant that induces antigen-specific mucosal and systemic immune responses without activation of inflammatory cascade after nasal administration.

Epithelial Barrier Dysfunction in Chronic Respiratory Diseases

Mucosal surfaces are lined by epithelial cells, which provide a complex and adaptive module that ensures first-line defense against external toxics, irritants, antigens, and pathogens. The underlying mechanisms of host protection encompass multiple physical, chemical, and immune pathways. In the lung, inhaled agents continually challenge the airway epithelial barrier, which is altered in chronic diseases such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, or pulmonary fibrosis. In this review, we describe the epithelial barrier abnormalities that are observed in such disorders and summarize current knowledge on the mechanisms driving impaired barrier function, which could represent targets of future therapeutic approaches.

Immunomodulatory Responses Of Toll Like Receptors Against 2019nCoV

The present review discusses the immune signals via toll like receptors (TLRs) against 2019nCoV. We researched using different database, up to June 18th, 2020. All the included articles were published in English language. The outcome of this review, that some TLRs agonists or antagonists are progressed as drugs to combat and down regulating TLRs immune signals respectively. TLRs 3 and 4 recognized 2019nCoV spike protein through immune and molecular signals that leading to immune stimulation of pro-inflammatory cytokines and even the immune fever. While the TLRs7 and 8 recognized single-stranded ribonucleic acids (ssRNAs) leading to elevation of the tumour necrosis factor α (TNF-α), interleukin (IL)-6 and -12 levels. TLRs agonists or antagonists utilized as immunotherapeutic targets against 2019nCoV via TLRs signals. Chloroquine and hydroxychloroquine; the approval compounds for 2019nCoV therapy can be inhibiting the class II major histocompatibility complex molecules expression and antigen presentation and even immune suppressions of the pro-inflammatory cytokines profile.

Redox Role of ROS and Inflammation in Pulmonary Diseases

Reactive oxygen species (ROS), either derived from exogenous sources or overproduced endogenously, can disrupt the body's antioxidant defenses leading to compromised redox homeostasis. The lungs are highly susceptible to ROS-mediated damage. Oxidative stress (OS) caused by this redox imbalance leads to the pathogenesis of multiple pulmonary diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). OS causes damage to important cellular components in terms of lipid peroxidation, protein oxidation, and DNA histone modification. Inflammation further enhances ROS production inducing changes in transcriptional factors which mediate cellular stress response pathways. This deviation from normal cell function contributes to the detrimental pathological characteristics often seen in pulmonary diseases. Although antioxidant therapies are feasible approaches in alleviating OS-related lung impairment, a comprehensive understanding of the updated role of ROS in pulmonary inflammation is vital for the development of optimal treatments. In this chapter, we review the major pulmonary diseases-including COPD, asthma, ARDS, COVID-19, and lung cancer-as well as their association with ROS.

Chlorogenic acid abates oxido-inflammatory and apoptotic responses in the liver and kidney of Tamoxifen-treated rats

Plant-derived phenolics are utilized as chemopreventive agents to abate adverse toxic responses associated with drug-induced damages. Tamoxifen (TAM)-a chemotherapeutic agent-is used in managing all stages of hormone-dependent breast cancer. Notwithstanding TAM's clinical side effect-including hepatic toxicity-its use is commonplace. The present study investigates the effect of Chlorogenic acid (CGA: 25 and 50 mg kg-1; per os (p.o)) reported to exhibit various beneficial properties, including antioxidative effect against TAM (50 mg/kg; p.o.)-induced hepatorenal toxicities in rats treated as follows: Control, CGA, or TAM alone, and rats co-treated with CGA and TAM for 2 weeks. Biomarkers of hepatorenal function, oxido-inflammatory stress, and hepatorenal histopathology were performed. We observed that TAM alone decreased relative organ weights (ROW), marginally impacted rat's survivability, and significantly (P < 0.05) increased hepatorenal toxicities and reactive oxygen and nitrogen species (RONS). TAM decreased (P < 0.05) antioxidant, anti-inflammatory cytokine (IL-10), besides increase in (P < 0.05) lipid peroxidation (LPO), pro-inflammatory cytokines (IL-1β, TNF-α), nitric oxide (NO), xanthine oxidase (XO), myeloperoxidase (MPO), and apoptotic caspases (Casp-3 and -9) levels. These biochemical alterations were accompanied by morphological lesions in experimental rats' liver and kidney. Conversely, that CGA dose-dependently relieved TAM-mediated toxic responses, restored antioxidants capacities, reduced oxidative stress, pro-inflammatory cytokines levels, and Casp-3 and -9 activities in experimental rats. Furthermore, CGA protected against lesions observed in the liver and kidney of rats treated with TAM alone. Overall, CGA blocked TAM-mediated hepatorenal injuries associated with pro-oxidative, inflammatory, and apoptotic mechanisms. CGA may serve as a chemoprotective agent boosting patients prognosis undergoing TAM chemotherapy.

Co-administration of Luteolin mitigated toxicity in rats' lungs associated with doxorubicin treatment

Doxorubicin (DOX), is a drug against lung malignancies with undesirable side effect including oxidative, inflammatory and apoptotic effects. Luteolin (LUT), present in fruits and vegetables is pharmacologically active against oxido-inflammatory and apoptotic responses. The present study examined the effect of LUT on DOX-induced lungs and blood dysfunction in Wistars rat (sex: male; 10 weeks old, 160 ± 5 g). Randomly grouped (n = 10) rats were treated as follows: control, LUT alone (100 mg/kg; per os), DOX (2 mg/kg; i. p), and co-treated rats with LUT (50 or 100 mg/kg) and DOX for two consecutive weeks. DOX alone adversely altered the final body and relative organ weights, red and white blood cell and platelet counts. DOX significantly (p > 0.05) reduced lungs antioxidant capacity, and anti-inflammatory cytokines; increased biomarkers of oxidative stress, caspase-3 activity, and pro-inflammatory cytokine. Morphological damages accompanied these biochemical alterations in the lung of experimental rats. Co-treatment with LUT, dose-dependently reversed DOX-mediated changes in rats' survival, toxic responses, and diminished oxidative stress in rat's lungs. Furthermore, co-treatment with LUT resulted in the reduction of pro-inflammatory cytokines and apoptotic biomarkers, increased red and white blood cell, platelet counts and abated pathological injuries in rat lungs treated with DOX alone. In essence, our findings indicate that LUT dose-dependently mitigated DOX-induced toxicities in the lungs and haematopoietic systems. Supplementation of patients on DOX-chemotherapy with phytochemicals exhibiting antioxidant activities, specifically LUT, could circumvent the onset of unintended toxic responses in the lungs and haematopoietic system exposed to DOX.

Exposure to diesel exhaust particles results in altered lung microbial profiles, associated with increased reactive oxygen species/reactive nitrogen species and inflammation, in C57Bl/6 wildtype mice on a high-fat diet

BACKGROUND

Exposure to traffic-generated emissions is associated with the development and exacerbation of inflammatory lung disorders such as chronic obstructive pulmonary disorder (COPD) and idiopathic pulmonary fibrosis (IPF). Although many lung diseases show an expansion of Proteobacteria, the role of traffic-generated particulate matter pollutants on the lung microbiota has not been well-characterized. Thus, we investigated the hypothesis that exposure to diesel exhaust particles (DEP) can alter commensal lung microbiota, thereby promoting alterations in the lung's immune and inflammatory responses. We aimed to understand whether diet might also contribute to the alteration of the commensal lung microbiome, either alone or related to exposure. To do this, we used male C57Bl/6 mice (4-6-week-old) on either regular chow (LF) or high-fat (HF) diet (45% kcal fat), randomly assigned to be exposed via oropharyngeal aspiration to 35 μg DEP, suspended in 35 μl 0.9% sterile saline or sterile saline only (control) twice a week for 30 days. A separate group of study animals on the HF diet was concurrently treated with 0.3 g/day of Winclove Ecologic® Barrier probiotics in their drinking water throughout the study.

RESULTS

Our results show that DEP-exposure increases lung tumor necrosis factor (TNF)-α, interleukin (IL)-10, Toll-like receptor (TLR)-2, TLR-4, and the nuclear factor kappa B (NF-κB) histologically and by RT-qPCR, as well as Immunoglobulin A (IgA) and Immunoglobulin G (IgG) in the bronchoalveolar lavage fluid (BALF), as quantified by ELISA. We also observed an increase in macrophage infiltration and peroxynitrite, a marker of reactive oxygen species (ROS) + reactive nitrogen species (RNS), immunofluorescence staining in the lungs of DEP-exposed and HF-diet animals, which was further exacerbated by concurrent DEP-exposure and HF-diet consumption. Histological examinations revealed enhanced inflammation and collagen deposition in the lungs DEP-exposed mice, regardless of diet. We observed an expansion of Proteobacteria, by qPCR of bacterial 16S rRNA, in the BALF of DEP-exposed mice on the HF diet, which was diminished with probiotic-treatment.

CONCLUSIONS

Our findings suggest that exposure to DEP causes persistent and sustained inflammation and bacterial alterations in a ROS-RNS mediated fashion, which is exacerbated by concurrent consumption of an HF diet.

Targeting the phosphoinositide-3-kinase/protein kinase B pathway in airway innate immunity

The airway innate immune system maintains the first line of defense against respiratory infections. The airway epithelium and associated immune cells protect the respiratory system from inhaled foreign organisms. These cells sense pathogens via activation of receptors like toll-like receptors and taste family 2 receptors (T2Rs) and respond by producing antimicrobials, inflammatory cytokines, and chemokines. Coordinated regulation of fluid secretion and ciliary beating facilitates clearance of pathogens via mucociliary transport. Airway cells also secrete antimicrobial peptides and radicals to directly kill microorganisms and inactivate viruses. The phosphoinositide-3-kinase/protein kinase B (Akt) kinase pathway regulates multiple cellular targets that modulate cell survival and proliferation. Akt also regulates proteins involved in innate immune pathways. Akt phosphorylates endothelial nitric oxide synthase (eNOS) enzymes expressed in airway epithelial cells. Activation of eNOS can have anti-inflammatory, anti-bacterial, and anti-viral roles. Moreover, Akt can increase the activity of the transcription factor nuclear factor erythroid 2 related factor-2 that protects cells from oxidative stress and may limit inflammation. In this review, we summarize the recent findings of non-cancerous functions of Akt signaling in airway innate host defense mechanisms, including an overview of several known downstream targets of Akt involved in innate immunity.

Identification of Toxicity Parameters Associated with Combustion Produced Soot Surface Chemistry and Particle Structure by in Vitro Assays

Air pollution has become the world's single biggest environmental health risk of the past decade, causing millions of yearly deaths worldwide. One of the dominant air pollutants is fine particulate matter (PM2.5), which is a product of combustion. Exposure to PM2.5 has been associated with decreased lung function, impaired immunity, and exacerbations of lung disease. Accumulating evidence suggests that many of the adverse health effects of PM2.5 exposure are associated with lung inflammation and oxidative stress. While the physical structure and surface chemistry of PM2.5 are surrogate measures of particle oxidative potential, little is known about their contributions to negative health effects. In this study, we used functionalized carbon black particles as surrogates for atmospherically aged combustion-formed soot to assess the effects of PM2.5 surface chemistry in lung cells. We exposed the BEAS-2B lung epithelial cell line to different soot at a range of concentrations and assessed cell viability, inflammation, and oxidative stress. Our results indicate that exposure to soot with varying particle surface composition results in differential cell viability rates, the expression of pro-inflammatory and oxidative stress genes, and protein carbonylation. We conclude that particle surface chemistry, specifically oxygen content, in soot modulates lung cell inflammatory and oxidative stress responses.

Unpuzzling COVID-19: tissue-related signaling pathways associated with SARS-CoV-2 infection and transmission

The highly infective coronavirus disease 19 (COVID-19) is caused by a novel strain of coronaviruses - the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - discovered in December 2019 in the city of Wuhan (Hubei Province, China). Remarkably, COVID-19 has rapidly spread across all continents and turned into a public health emergency, which was ultimately declared as a pandemic by the World Health Organization (WHO) in early 2020. SARS-CoV-2 presents similar aspects to other members of the coronavirus family, mainly regarding its genome, protein structure and intracellular mechanisms, that may translate into mild (or even asymptomatic) to severe infectious conditions. Although the mechanistic features underlying the COVID-19 progression have not been fully clarified, current evidence have suggested that SARS-CoV-2 may primarily behave as other β-coronavirus members. To better understand the development and transmission of COVID-19, unveiling the signaling pathways that may be impacted by SARS-CoV-2 infection, at the molecular and cellular levels, is of crucial importance. In this review, we present the main aspects related to the origin, classification, etiology and clinical impact of SARS-CoV-2. Specifically, here we describe the potential mechanisms of cellular interaction and signaling pathways, elicited by functional receptors, in major targeted tissues/organs from the respiratory, gastrointestinal (GI), cardiovascular, renal, and nervous systems. Furthermore, the potential involvement of these signaling pathways in evoking the onset and progression of COVID-19 symptoms in these organ systems are presently discussed. A brief description of future perspectives related to potential COVID-19 treatments is also highlighted.

Impaired lnc-IL7R modulatory mechanism of Toll-like receptors is associated with an exacerbator phenotype of chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) are susceptible to bacterial infections, which worsen lung inflammation and contribute to lung function decline and acute exacerbation. Long noncoding (lnc) RNAs are emerging regulators of inflammation with unknown clinical relevance. Herein, we report that levels of the Toll-like receptor (TLR)-related lnc interleukin (IL) 7 receptor (IL7R) were significantly reduced in peripheral blood mononuclear cells from patients with COPD compared with those from normal controls, and the levels were correlated with pulmonary function. Moreover lnc-IL7R levels were reduced in lavaged alveolar macrophages and primary human small airway epithelial cells (HSAEpCs) from patients with COPD. Lnc-IL7R knockdown in primary human macrophages, HSAEpCs, and human pulmonary microvascular endothelial cells (HPMECs) significantly augmented the induction of proinflammatory mediators after TLR2/4 activation. By contrast, lnc-IL7R overexpression attenuated inflammation after TLR2/4 activation. Similar results with lnc-IL7R-mediated inflammation were observed in COPD HSAEpCs. Mechanistically, lnc-IL7R mediated a repressive chromatin state of the proinflammatory gene promoter as a result of decreased acetylation (H3K9ac) and increased methylation (H3K9me3 and H3K27me3). Plasma lnc-IL7R levels were reduced in patients with COPD who experienced more acute exacerbation in the previous year. Notably, patients with lower lnc-IL7R levels in the subsequent year had increased exacerbation risk. Low lnc-IL7R expression in COPD may augment TLR2/4-mediated inflammation and be associated with acute exacerbation.

Multiple Gene Expression Dataset Analysis Reveals Toll-Like Receptor Signaling Pathway is Strongly Associated With Chronic Obstructive Pulmonary Disease Pathogenesis

Chronic obstructive pulmonary disease is a complex pulmonary disease that causes airflow obstruction in humans. To identify the core genes in COPD pathogenesis, seven diverse microarray datasets (GSE475, GSE1122, GSE1650, GSE3212, GSE8823, GSE37768, and GSE22148) were downloaded from the gene expression omnibus database. All the datasets were analyzed independently with the R/Bioconductor package to screen the differentially expressed genes (DEGs). The gene ontology and pathway enrichment analysis were performed for the acquired DEGs using DAVID (Database for Annotation, Visualization, and Integrated Discovery). Further protein-protein interaction network was constructed for the DEGs and their potential hub genes and sub-networks were identified using Cytoscape software. From the selected seven datasets, 188 overlapped DEGs were perceived eventually based on considering the repetitive genes between at-least one dataset. Gene Ontology analysis reveals that most of the DEGs were significantly enriched in immune response, inflammatory response, extracellular region, lipid binding, cytokine, and chemokine activity. Moreover, genes from the sub-network analysis were again submitted to the DAVID server to validate the results which uncover the Toll-like receptor signaling pathway was significantly enriched and all the genes present in this pathway were likewise detected as hub genes from Cytoscape software. CXCL9, CXCL10, CXCL11, CCL4, TLR7, and SPP1 hub genes in the toll-like receptor signaling pathway were explored in this study as potential biomarker genes associated with COPD pathogenesis.

Differential toll like receptor expression in cystic fibrosis patients' airways during rhinovirus infection

OBJECTIVES

Since an inappropriate and sustained activation of TLRs may contribute to a chronic inflammatory response resulting in detrimental effects in cystic fibrosis (CF) patients, we sought to examine whether HRV infection might alter the respiratory expression of TLRs according to the microbiological status of CF patients.

METHODS

Respiratory samples were collected from the respiratory tract of CF patients (n = 294) over a period of 12 months. In addition to the usual microbiological investigation, HRV-RNA detection and typing were performed by RT-PCR and sequencing. HRV viral load and TLRs levels were measured by RT-Real Time PCR.

RESULTS

HRV-RNA was detected in 80 out of 515 respiratory samples (15.5%) with a similar rate in all age groups (0-10 years, 11-24 years, ≥ 25 years). Patients infected with different HRV A, B and C species exhibited higher levels of TLR2, TLR4 and TLR8 as compared to HRV negative patients. Moreover, the expression level of TLR2, TLR4 and TLR8 correlated with high level of HRV viral load. HRV positive patients co-colonized by Staphylococcus aureus or Pseudomonas aeruginosa showed also enhanced amounts of TLR2 and TLR2/4-mRNAs expression respectively. In the case of presence of both bacteria, TLR2, TLR4, TLR8 and TLR9 levels are elevated in positive HRV patients.

CONCLUSIONS

TLRs, especially TLR2 and TLR4, increased in HRV positive CF individuals and varies according to the presence of S. aureus, P. aeruginosa and both bacteria.

COVID-19 as an Acute Inflammatory Disease

The 2019 coronavirus disease (COVID-19) pandemic caused by the virus severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has created an unprecedented global crisis for the infrastructure sectors, including economic, political, healthcare, education, and research systems. Although over 90% of infected individuals are asymptomatic or manifest noncritical symptoms and will recover from the infection, those individuals presenting with critical symptoms are in urgent need of effective treatment options. Emerging data related to mechanism of severity and potential therapies for patients presenting with severe symptoms are scattered and therefore require a comprehensive analysis to focus research on developing effective therapeutics. A critical literature review suggests that the severity of SARS-CoV-2 infection is associated with dysregulation of inflammatory immune responses, which in turn inhibits the development of protective immunity to the infection. Therefore, the use of therapeutics that modulate inflammation without compromising the adaptive immune response could be the most effective therapeutic strategy.

Out-Smarting the Host: Bacteria Maneuvering the Immune Response to Favor Their Survival

Bacteria adapt themselves to various environmental conditions in nature, which can lead to bacterial adaptation and persistence in the host as commensals or pathogens. In healthy individuals, host defense mechanisms prevent the opportunistic bacteria/commensals from becoming a pathological infection. However, certain pathological conditions can impair normal defense barriers leading to bacterial survival and persistence. Under pathological conditions such as chronic lung inflammation, bacteria employ various mechanisms from structural changes to protease secretion to manipulate and evade the host immune response and create a niche permitting commensal bacteria to thrive into infections. Therefore, understanding the mechanisms by which pathogenic bacteria survive in the host tissues and organs may offer new strategies to overcome persistent bacterial infections. In this review, we will discuss and highlight the complex interactions between airway pathogenic bacteria and immune responses in several major chronic inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD).

Prominence of IL6, IGF, TLR, and Bioenergetics Pathway Perturbation in Lung Tissues of Scleroderma Patients With Pulmonary Fibrosis

Scleroderma-associated pulmonary fibrosis (SSc-PF) and idiopathic pulmonary fibrosis (IPF) are two of many chronic fibroproliferative diseases that are responsible for nearly 45% of all deaths in developed countries. While sharing several pathobiological characteristics, they also have very distinct features. Currently no effective anti-fibrotic treatments exist that can halt the progression of PF or reverse it. Our goal is to uncover potential gene targets for the development of anti-fibrotic therapies efficacious in both diseases, and those specific to SSc-PF, by identifying universal pathways and molecules driving fibrosis in SSc-PF and IPF tissues as well as those unique to SSc-PF. Using DNA microarray data, a meta-analysis of the differentially expressed (DE) genes in SSc-PF and IPF lung tissues (diseased vs. normal) was performed followed by a full systems level analysis of the common and unique transcriptomic signatures obtained. Protein-protein interaction networks were generated to identify hub proteins and explore the data using the centrality principle. Our results suggest that therapeutic strategies targeting IL6 trans-signaling, IGFBP2, IGFL2, and the coagulation cascade may be efficacious in both SSc-PF and IPF. Further, our data suggest that the expression of matrikine-producing collagens is also perturbed in PF. Lastly, an overall perturbation of bioenergetics, specifically between glycolysis and fatty acid metabolism, was uncovered in SSc-PF. Our findings provide insights into potential targets for the development of anti-fibrotic therapies that could be effective in both IPF and SSc-PF.

Kappa Opioid Receptor on Pulmonary Macrophages and Immune Function

Background

Respiratory failure significantly increases mortality in critically ill patients. While opioids are often used during the perioperative period and in critically ill situations, little is known about how opioids are involved in pulmonary immune function and the inflammatory response. There is currently no clear information on the role of the kappa opioid receptor (KOR) in pulmonary inflammation. Here we evaluate whether KORs are involved in the modulation of lung macrophages by the use of selective KOR agonists in lipopolysaccharide (LPS) activated alveolar macrophages.

Method

The inflammatory response in rat NR8383 macrophages was induced by stimulation with LPS (100 ng/ml) at different time-points. The effects of the KOR agonists Salvinorin A (SA) and U50488 on inflammatory factors such as nitrite, TNF-α, IL-1β, iNOS and COX-2 were investigated. Nor-binaltorphimine, a selective KOR antagonist, was used to investigate the specific role of KOR.

Results

Stimulation of NR8383 cells with LPS (100 ng/ml) significantly increased the level of TNF-α at 1h, 2h and 6h compared to un-stimulated cells. SA attenuated the inflammatory response by reducing the levels of TNF-α and IL-1β after LPS treatment. SA co-treatment reduced the elevated levels of NO induced by LPS and also alleviated the over-expression of iNOS and COX-2 within 2 hours after LPS activation, and such effects can be partially blocked by KOR antagonist, nor-binaltorphimine. Similar results from U50488 were observed.

Conclusion

Our results indicate that KORs may play a critical role in the modulation of the pulmonary inflammatory process by their activation in macrophages. Selective KOR agonists exert their anti-inflammatory effects acutely on lung macrophages, within 1-2 hours of LPS-stimulated inflammation in vitro.

Targeting murine alveolar macrophages by the intratracheal administration of locked nucleic acid containing antisense oligonucleotides

The pulmonary delivery of locked nucleic acid containing antisense oligonucleotides (LNA-ASOs) is expected to be a novel therapeutic approach for lung diseases. However, there are two concerns to be considered: immune responses, as the lung has a distinct immune mechanism to protect it from inhaled pathogens; and leakage into blood, since the lung is permeable to small molecules. As phagocytic alveolar macrophages reside in the alveolar space, it is hypothesized that inhaled LNA-ASOs effectively accumulate and exert a knockdown (KD) effect on these cells at low doses. Thus, targeting alveolar macrophages by inhaled LNA-ASOs may reduce these risks. To test this hypothesis, LNA-ASOs targeting Scarb1 or Hprt1 were intratracheally administered to mice. We confirmed the remarkable accumulation of intratracheally administered LNA-ASOs in murine alveolar macrophages and found that they exerted a significant and sequence-dependent KD effect. The dose required for KD in alveolar macrophages was lower than that required to induce KD in the whole lung. Furthermore, when a KD effect was observed in alveolar macrophages, no KD effect was observed in the liver or kidney; however, several inflammatory cytokines were increased in the lung. These results suggest the potential application of LNA-ASOs as an inhaled drug specific to alveolar macrophages. However, further studies on the immuno-stimulatory effects of LNA-ASOs will be necessary for the development of novel inhaled therapeutic agents.

Cynanchum atratum Ameliorates Airway Inflammation via Maintaining Alveolar Barrier and Regulating Mast Cell-Mediated Inflammatory Responses

Asthma is a common allergic airway inflammatory disease, characterized by abnormal breathing due to bronchial inflammation. Asthma aggravates the patient's quality of life and needs continuous pharmacological treatment. Therefore, discovery of drugs for the treatment of asthma is an important area of human health. The aim of the present study was to evaluate whether Cynanchum atratum extract (CAE) modulates the asthma-like allergic airway inflammation and to study its possible mechanism of action using ovalbumin (OVA)-induced airway inflammation and lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice, as well as a mast cell-based in vitro model. The histological analysis showed that CAE reduced the airway constriction and immune cell infiltration. CAE also inhibited release of β-hexosaminidase and expression of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-4, and IL-5 in bronchoalveolar lavage fluid and lung tissues. In addition, CAE reduced the OVA-specific immunoglobulin (Ig) E, total IgE, IgG1, and IgG2a levels in the serum. In the LPS-induced ALI model, CAE suppressed the LPS-induced lung barrier dysfunction and the release of proinflammatory cytokines. Because allergic airway inflammatory responses are associated with the activation of mast cells, RBL-2H3 cells were used to evaluate the underlying mechanism of CAE effects. In RBL-2H3 cells, CAE down-regulated release of β-hexosaminidase and histamine by reducing the intracellular calcium influx. In addition, CAE suppressed the expression of proinflammatory cytokines by inhibiting nuclear translocation of nuclear factor-κB. Taken together, our findings suggest that CAE may help in the prevention or treatment of airway inflammatory diseases.

Multiple subtypes of TLR22 molecule from Schizothorax prenanti present the functional diversity in ligand recognition and signal activation

Evolutionary development has increased the diversity of genotypes and the complexity of gene functions in fish. TLR22 has been identified as a teleost-specific gene, but its functions are tremendously different among different fish species. Whether the functional diversity relates to the difference of genotypes remains poorly understand. In this study, we cloned and identified three TLR22 molecules from Schizothorax prenanti (S. prenanti), named as spTLR22-1, spTLR22-2 and spTLR22-3. The full-length coding regions of spTLR22s are 2841 bp, 2805 bp and 2868 bp and coding 946 aa, 934 aa and 955 aa, respectively. All spTLR22s are composed of multiple leucine-rich repeat (LRR) domains, a transmembrane structure and a Toll/IL-1 receptor (TIR) region. The phylogenetic analysis showed that three spTLR22s were close to Cyprinus carpio TLR22-1, TLR22-2 and TLR22-3, respectively. Among the spTLR22s, they presented not close relationship but remained to belong to TLR22 subfamily. All spTLR22s were ubiquitously expressed in all tested tissues, but the expression levels of spTLR22s were dominant in immune-related tissues, such as gill and spleen. The expression levels of spTLR22-1 and spTLR22-3 were significantly increased after treatment with bacteria, LPS and Poly(I:C). However, spTLR22-2 seems like no response to these treatments. The luciferase reporter assay demonstrated that all spTLR22s could activate NF-κB signaling pathway, but only spTLR22-1 and spTLR22-2 could activate IFN-β signaling pathway. Interestingly, in the ligand recognition analysis, spTLR22-1 and spTLR22-3 but not spTLR22-2 had the recognized potential to Poly(I:C), and all spTLR22s could not recognize LPS. Both spTLR22-1 and spTLR22-3 significantly up-regulated the expression of anti-viral-related genes (Mx, IFN and ISG15) and down-regulated the expression of anti-inflammatory factor IL-10 after the overexpression in carp EPC cell line, but spTLR22-2 failed to impact the expression of these genes. Moreover, we found that all spTLR22s localized to the intracellular region. Taken together, our results reveal that spTLR22-1 and spTLR22-3 but not spTLR22-2 may be involved into the anti-viral immune response via IFN-β signaling pathway, and all spTLR22s can activate NF-κB signaling pathway but only spTLR22-1 and spTLR22-3 response to the stimulation of bacteria and LPS.

TLRs in pulmonary diseases

Toll-like receptors (TLRs) comprise a clan of proteins involved in identification and triggering a suitable response against pathogenic attacks. As lung is steadily exposed to multiple infectious agents, antigens and host-derived danger signals, the inhabiting stromal and myeloid cells of the lung express an aggregate of TLRs which perceive the endogenously derived damage-associated molecular patterns (DAMPs) along with pathogen associated molecular patterns (PAMPs) and trigger the TLR-associated signalling events involved in host defence. Thus, they form an imperative component of host defence activation in case of microbial infections as well as non-infectious pulmonary disorders such as interstitial lung disease, acute lung injury and airways disease, such as COPD and asthma. They also play an equally important role in lung cancer. Targeting the TLR signalling network would pave ways to the design of more reliable and effective vaccines against infectious agents and control deadly infections, desensitize allergens and reduce inflammation. Moreover, TLR agonists may act as adjuvants by increasing the efficiency of cancer vaccines, thereby contributing their role in treatment of lung cancer too. Overall, TLRs present a compelling and expeditiously bolstered area of research and addressing their signalling events would be of significant use in pulmonary diseases.

Gram-Negative Pneumonia Augments Non-Small Cell Lung Cancer Metastasis through Host Toll-like Receptor 4 Activation

INTRODUCTION

Surgery is essential for cure of early-stage non-small cell lung cancer (NSCLC). Rates of postoperative bacterial pneumonias, however, remain high, and clinical data suggests that post-operative infectious complications confer an increased risk for metastasis. Toll-like receptors (TLRs) mediate the inflammatory response to infection by recognizing evolutionarily conserved bacterial structures at the surface of numerous pulmonary cell types; yet, little is known about how host TLR activation influences NSCLC metastasis. TLR4 recognizes gram-negative bacterium lipopolysaccharide activating the innate immune system.

METHODS

C57BL/6 and TLR4 knockout murine airways were inoculated with Escherichia coli or lipopolysaccharide. Hepatic metastasis assays and intravital microscopy were performed. Bronchoepithelial conditioned media was generated through coincubation of bronchoepithelial cells with TLR4 activating Escherichia coli or lipopolysaccharide. Subsequently, H59 NSCLC were stimulated with conditioned media and subject to various adhesion assays.

RESULTS

We demonstrate that gram-negative Escherichia coli pneumonia augments the formation of murine H59 NSCLC liver metastases in C57BL/6 mice through TLR4 activation. Additionally, infected C57BL/6 mice demonstrate increased H59 NSCLC in vivo hepatic sinusoidal adhesion compared with negative controls, a response that is significantly diminished in TLR4 knockout mice. Similarly, intratracheal injection of purified TLR4 activating lipopolysaccharide increases in vivo adhesion of H59 cells to murine hepatic sinusoids. Furthermore, H59 cells incubated with bronchoepithelial conditioned medium show increased cell adhesion to in vitro extracellular matrix proteins and in vivo hepatic sinusoids through a mechanism dependent on bronchoepithelial TLR4 activation and interleukin-6 secretion.

CONCLUSION

TLR4 is a viable therapeutic target for NSCLC metastasis augmented by gram-negative pneumonia.

Phagocytosis of Leptospira by leukocytes from mice with different susceptibility to leptospirosis and possible role of chemokines

Background

Leptospirosis is a widespread zoonosis caused by pathogenic prokaryotic microbes of the genus Leptospira. Although there are several reports in the literature, host-pathogen interaction is still poorly understood. The role of chemokine expression is important on the chemotaxis, activation and regulation of immune cells. Recent studies have shown that their expression profiles play an important role on the severity of leptospirosis outcome. We evaluated the phagocytosis of Leptospira by spleens cells from C3H/HeJ, C3H/HePas and BALB/c mouse strains, respectively susceptible, intermediate and resistant to leptospirosis, and by RAW 264.7 macrophages. Besides, we evaluated the effects of CCL2 treatment on the phagocytosis. The cells were incubated with or without CCL2 chemokine, and infected with virulent L. interrogans sv Copenhageni. Cells and culture supernatants were collected for subsequent analysis.

Results

The number of leptospires was higher in BALB/c cells, CCL2 pre-treated or only infected groups, when compared to C3H/HeJ and C3H/HePas cells. Indeed, CCL2 activation did not interfere in the phagocytosis of Leptospira. Expression of chemokines CXCL5 and CCL8 levels were significantly inhibited in infected BALB/c cells when compared to the non-infected control.

Conclusions

Higher ability to phagocytosis and early modulation of some chemokines correlated with the resistance to leptospirosis disease. Exposure to CCL2 did not interfere on phagocytosis of Leptospira in our experimental conditions, but acted in the modulation of chemokines expression during Leptospira infection.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1371-9) contains supplementary material, which is available to authorized users.

Involvement of M1 Macrophage Polarization in Endosomal Toll-Like Receptors Activated Psoriatic Inflammation

Psoriasis is a chronic inflammatory skin disorder that affects ~2%–3% of the worldwide population. Inappropriate and excessive activation of endosomal Toll-like receptors 7, 8, and 9 (TLRs 7–9) at the psoriatic site has been shown to play a pathogenic role in the onset of psoriasis. Macrophage is a major inflammatory cell type that can be differentiated into phenotypes M1 and M2. M1 macrophages produce proinflammatory cytokines, and M2 macrophages produce anti-inflammatory cytokines. The balance between these two types of macrophages determines the progression of various inflammatory diseases; however, whether macrophage polarization plays a role in psoriatic inflammation activated by endosomal TLRs has not been investigated. In this study, we investigated the function and mechanism of macrophages related to the pathogenic role of TLRs 7–9 in the progression of psoriasis. Analysis of clinical data in database revealed significantly increased expression of macrophage markers and inflammatory cytokines in psoriatic tissues over those in normal tissues. In animal studies, depletion of macrophages in mice ameliorated imiquimod, a TLR 7 agonist-induced psoriatic response. Imiquimod induced expression of genes and cytokines that are signature of M1 macrophage in the psoriatic lesions. In addition, treatment with this TLR 7 agonist shifted macrophages in the psoriatic lesions to a higher M1/M2 ratio. Both of the exogenous and endogenous TLR 7–9 ligands activated M1 macrophage polarization. M1 macrophages expressed higher levels of proinflammatory cytokines and TLRs 7–9 than M2 macrophages. These results suggest that by rendering macrophages into a more inflammatory status and capable of response to their ligands in the psoriatic sites, TLR 7–9 activation drives them to participate in endosomal TLR-activated psoriatic inflammation, resulting in an amplified inflammatory response. Our results also suggest that blocking M1 macrophage polarization could be a strategy which enables inhibition of psoriatic inflammation activated by these TLRs.

Crosstalk of toll-like receptors signaling and Nrf2 pathway for regulation of inflammation

Inflammation as a second line of defense of innate immunity plays a crucial role in eliminating invading pathogens (bacteria, viruses, fungi as well as other parasites). The inflammatory response may also activate adaptive immune system involving lymphocytes to mount either antibody dependent or cell-mediated immune responses to clear pathogenic insult. However, if continued, the inflammatory processes may become uncontrolled culminating in cellular injury and tissue destruction, thereby manifesting itself in chronic form. The chronic inflammation has been associated with numerous human pathological conditions like allergies and autoimmune diseases, atherosclerosis, arthritis, Alzheimer's disease, cancer, obesity, type 2 diabetes, schizophrenia, neuro-degenerative diseases and numerous others. The dysregulated inflammatory process is associated with overproduction of free radicals leading to oxidative stress and activation of different cell signaling pathways. The regulation of inflammation by TLR signaling as well as Nrf2 pathways separately is widely documented. Since both these major signaling pathways modulate inflammation, they may crosstalk to bring about coordinated inflammatory responses. The linkage between TLR signaling and Nrf2-Keap1 pathway may serve as a bridge between immune regulation and oxidative stress responses through regulation of inflammation. Also, inflammation is reportedly responsible for the plethora of diseased conditions; a study of its regulation by targeting the TLR-Nrf2 cross-talks may also be beneficial for the development of therapeutic therapies or prophylactic treatments. Hence, present review focuses on the crosstalk between TLR signaling and Nrf2 pathway with respect to their role in modulation of inflammation in normal as well as pathologic conditions.

Functional Evidence of Pulmonary Extracellular Vesicles in Infectious and Noninfectious Lung Inflammation

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a highly complex process that can be triggered by both noninfectious (sterile) and infectious stimuli. Inflammatory lung responses are one of the key features in the pathogenesis of this devastating syndrome. How ALI/ARDS-associated inflammation develops remains incompletely understood, particularly after exposure to sterile stimuli. Emerging evidence suggests that extracellular vesicles (EVs) regulate intercellular communication and inflammatory responses in various diseases. In this study, we characterized the generation and function of pulmonary EVs in the setting of ALI/ARDS, induced by sterile stimuli (oxidative stress or acid aspiration) and infection (LPS/Gram-negative bacteria) in mice. EVs detected in bronchoalveolar lavage fluid (BALF) were markedly increased after exposure of animals to both types of stimuli. After sterile stimuli, alveolar type-І epithelial cells were the main source of the BALF EVs. In contrast, infectious stimuli-induced BALF EVs were mainly derived from alveolar macrophages (AMs). Functionally, BALF EVs generated in both the noninfectious and infectious ALI models promoted the recruitment of macrophages in in vivo mouse models. Furthermore, BALF EVs differentially regulated AM production of cytokines and inflammatory mediators, as well as TLR expression in AMs in vivo. Regardless of their origin, BALF EVs contributed significantly to the development of lung inflammation in both the sterile and infectious ALI. Collectively, our results provide novel insights into the mechanisms by which EVs regulate the development of lung inflammation in response to diverse stimuli, potentially providing novel therapeutic and diagnostic targets for ALI/ARDS.

Toll-like receptor 2, 4 and 9 polymorphisms and their association with ICU-acquired infections in Central Greece

PURPOSE

To test the potential of four common Toll-like receptor (TLR) polymorphisms to predispose to specific intensive care unit (ICU)-acquired infections and affect outcomes in a Greek ICU.

MATERIALS AND METHODS

The incidence of TLR2-Arg753Gln, TLR4-Asp299Gly, TLR4-Thr399Ile and TLR9-T1237C polymorphisms, and their association with ICU-acquired infections and patients' clinical outcomes were prospectively evaluated The examined genetic polymorphisms were assessed by real-time Polymerase-Chain-Reaction (PCR).

RESULTS

During a 15-month period, 224 patients were enrolled and genotyped. The prevalence of genetic polymorphisms for TLR4-Asp299Gly, TLR4-Thr399Ile, mixed TLR4-Asp299Gly/Thr399Ile, TLR9-T1237C and TLR2-Arg753Gln was 14.4%, 14.7%, 11.2%, 24.5% and 2.2%, respectively. TLR4 polymorphisms were associated with increased susceptibility towards specific ICU-acquired infections, i.e. Gram-negative central-nervous-system infections (CNSI), ventilator-associated pneumonia (VAP) and urinary-tract infections (UTI), principally due to multi-drug resistant (MDR) Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumonia, respectively (all P < 0.05). TLR9-T1237C polymorphism was associated with lower incidence and fewer relapses of CNSIs and UTIs when compared to mixed TLR4-Asp299Gly/Thr399Ile polymorphism group (P ≤ 0.039). ICU-stay was significantly prolonged in TLR4 polymorphisms (P ≤ 0.0416).

CONCLUSIONS

Common TLR-signaling polymorphisms might be implicated in the clinical phenotype of ICU-acquired infections in Central Greece. The possible impact of TLR4 polymorphisms on enhanced susceptibility towards Gram-negative MDR-infections in defined critical-disease states warrants further investigation. Trial Registration Clinical Trials.gov identifier: NCT00932243.

Cigarette smoke-induced inflammation: NLRP10-mediated mechanisms

Chronic obstructive pulmonary disease (COPD) is a progressive, life-threatening disease that causes irreversible lung damage. Cigarette smoking is the chief etiologic factor for the commencement of this condition. Despite constant efforts to develop therapeutic interventions and to ascertain the molecular mechanism leading to the pathophysiology of this disease, much remains unknown. However, pattern recognition receptors (PRRs), i.e., Toll-like-receptors (TLRs) and NOD-like receptors (NLRs) are believed to play important roles in COPD and could serve as effective therapeutic targets. Although the role of TLRs in COPD has been well studied, the importance of NLRs has not yet been explored in detail. The NLR family member NLRP10 (aka NOD8, PAN5, PYNOD) is the only member of this family of proteins that lacks the leucine rich repeat (LRR) domain responsible for detection of pathogen and danger-associated molecular patterns (PAMPs/DAMPs). Therefore, instead of functioning as a PRR, NLRP10 may have a broader regulatory role. To elucidate the role of NLRP10 in secondhand smoke (SHS)-induced inflammation, we exposed C57Bl/6 (WT) and Nlrp10-deficient mice (Nlrp10^-/-) on the C57Bl/6 background to filtered air- or SHS- for 6 weeks (acute exposure) and assessed the resulting molecular events. Leukocyte recruitment in SHS-exposed Nlrp10^-/- mice was found to be significantly lower compared to SHS-exposed WT mice. In addition, we observed an important role for NLRP10 in SHS-mediated caspase-1 activation, cytokine/chemokine production (IL-1β, IL-18, MCP-1 and IL-17A), and induction of NF-κB and MAPKs in the lungs of C57Bl/6 mice. The reduced influx of CD4⁺IL-17A⁺ and CD8⁺IL-17A⁺ cells into the lungs of SHS-exposed Nlrp10^-/- mice and impaired differentiation of Nlrp10^-/- Th0 cells into Th17 cells (ex vivo) provide insight into the mechanistic details underlying NLRP10-dependent IL-17 production. We further substantiated our in vivo findings by challenging human alveolar type II epithelial cells (A549) transfected with scrambled- or Nlrp10-siRNA with cigarette smoke extract (CSE). We observed an important role of NLRP10 in cytokine and chemokine production as well as expression of NF-κB and MAPKs in CSE-exposed A549 cells. Furthermore, replenishment of A549 cell culture with recombinant IL-17A (rIL-17A) during NLRP10 knockdown rescued CSE-induced inflammatory responses. To identify upstream mediators of NLRP10 regulation we investigated epigenetic markers within the Nlrp10 promoter following cigarette smoke exposure and observed significant changes in active as well as repressive gene markers on histone 3 and histone 4 using both in vivo and in vitro study models. Further, alterations in the respective histone acetyl- and methyltransferases (PCAF, SET1, ESET, SUV20H1) correlated well with the observed histone modifications. Overall, our findings suggest a novel role of epigenetically regulated NLRP10 in Th17/IL-17 signaling during CS exposure.

Effects of lipopolysaccharide on the histomorphology and expression of toll-like receptor 4 in the chicken trachea and lung

Endotoxin or lipopolysaccharide (LPS) exposure can cause injury to the respiratory airways and in response, the respiratory epithelia express toll-like receptors (TLRs) in many species. However, its role in the innate immunity in the avian respiratory system is poorly understood. The aim of the present study was to evaluate the effects of LPS on the chicken trachea and lung. After intraperitoneal LPS or saline injection, the trachea and lungs were harvested at 0, 12, 36 and 72 h (n = 6 at each time point) and histopathologically analysed using haematoxylin and eosin and periodic acid-Schiff staining, while TLR4 expression was determined by immunohistochemistry and secretory Immunoglobulin A (SIgA) levels by enzyme-linked immunosorbent assay. After LPS stimulation, we observed a remarkable decrease in the number of goblet cells along with obvious disruption and desquamation of the ciliated epithelium in the trachea, blurring of the boundary between pulmonary lobules, narrowed or indistinguishable lumen of the pulmonary atria and leukostasis in the lungs. Following LPS stimulation, TLR4 protein expression was up-regulated in both the trachea and the lungs and was found on the ciliated columnar cells as well as in the submucosa of the trachea, and in the lungs on parenchymal and immune cells. However, SIgA levels were only up-regulated in the trachea at 12 h following LPS stimulation. Hence, this report provides novel information about the effects of LPS on the microstructure of the lower respiratory tract and it is concluded that its intra-peritoneal administration leads to TLR4-mediated destruction of the tracheal epithelium and pulmonary inflammation along with increased SIgA expression in the tracheal mucosa.