Characterization of TLR-induced inflammatory responses in COPD and control lung tissue explants

Pulmonary delivery of icariin-phospholipid complex prolongs lung retention and improves therapeutic efficacy in mice with acute lung injury/ARDS

Icariin has been shown the promising therapeutic potential to treat inflammatory airway diseases, yet its poor lung distribution and retention restrict the clinical applications. To this end, this work aimed to prepare an icariin-phospholipid complex (IPC) formulation for sustained nebulization delivery that enabled excellent inhalability, improved lung exposure and prolonged duration of action. Icariin was found to react with soybean phospholipid to form supramolecular IPC, which was able to self-assemble into nanoparticle suspension. The suspension was stable during steam sterilization and nebulization processes, and its aerosols generated by a commercial nebulizer exhibited excellent aerodynamic properties and delivery efficiency. In vitro studies showed that the formation of complex sustained drug release, enhanced lung affinity and slowed lung clearance. The drug distribution in lung epithelial lining fluid (ELF) also demonstrated in vivo sustained release after intratracheal administration to mice. In addition, compared to free icariin, IPC improved the drug exposure to lung tissues and immune cells in the ELF by 4.61-fold and 39.5-fold, respectively. This resulted in improved and prolonged local anti-inflammatory effects up to 24 h in mice with lipopolysaccharide (LPS)-induced acute lung injury. Moreover, IPC improved survival rate of mice with acute respiratory distress syndrome (ARDS). Overall, the present phospholipid complex represented a promising formulation of icariin for the treatment of acute lung injury/ARDS by nebulization delivery.

Upregulation of key factors of viral entry of corona- and influenza viruses upon TLR3-signaling in cells from the respiratory tract and clinical treatment options by 1,8-Cineol

At the end of the 2019 coronavirus pandemic (COVID-19), highly contagious variants of coronaviruses had emerged. Together with influenza viruses, different variants of the coronavirus currently cause most colds and require appropriate drug treatment. We have investigated the expression of important factors for the replication of these viruses, namely transmembrane protease serine subtype 2 (TMPRSS2), neuropilin1 (NRP1), and angiotensin converting enzyme 2 (ACE2) or tumor necrosis factor-α (TNF-α) after toll like receptor-3 (TLR-3) stimulation using RT-qPCR and flow cytometry (FC) analysis. As model served primary fibroblasts derived from the lung and nasal cavity, as well as epidermal stem cells and fully matured respiratory epithelium. The stimulated cell cultures were treated with pharmaceuticals (Dexamethasone and Enzalutamide) and the outcome was compared with the phytomedicine 1,8-Cineol. The stimulation of TLR3 is sufficient to induce the expression of exactly those targets that were highly expressed in the corresponding culture type, specifically ACE2 and TMPRSS2 in respiratory epithelial stem cells and NRP1 in fibroblast cells. It seems this self-perpetuating cycle of infection-driven upregulation of key viral replication factors by the innate immune system represents an evolutionary advantage for viruses using these transcripts as viral replication factors. Likewise, to the standard pharmaceuticals with proven clinical efficiency, 1,8-Cineol was able to disrupt this self-perpetuating cycle. Considering the minor side effects and negligible pharmacological interactions with other drugs, it is conceivable that an adjuvant or combinatorial therapy with 1,8-Cineol for respiratory diseases caused by corona- or influenza viruses would be beneficial.

Immunoactive signatures of circulating tRNA- and rRNA-derived RNAs in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the most prevalent lung disease, and macrophages play a central role in the inflammatory response in COPD. We here report a comprehensive characterization of circulating short non-coding RNAs (sncRNAs) in plasma from patients with COPD. While circulating sncRNAs are increasingly recognized for their regulatory roles and biomarker potential in various diseases, the conventional RNA-seq method cannot fully capture these circulating sncRNAs due to their heterogeneous terminal structures. By pre-treating the plasma RNAs with T4 polynucleotide kinase, which converts all RNAs to those with RNA-seq susceptible ends (5'-phosphate and 3'-hydroxyl), we comprehensively sequenced a wide variety of non-microRNA sncRNAs, such as 5'-tRNA halves containing a 2',3'-cyclic phosphate. We discovered a remarkable accumulation of the 5'-half derived from tRNA ValCAC in plasma from COPD patients, whereas the 5'-tRNA GlyGCC half is predominant in healthy donors. Further, the 5'-tRNA ValCAC half activates human macrophages via Toll-like receptor 7 and induces cytokine production. Additionally, we identified circulating rRNA-derived fragments that were upregulated in COPD patients and demonstrated their ability to induce cytokine production in macrophages. Our findings provide evidence of circulating, immune-active sncRNAs in patients with COPD, suggesting that they serve as inflammatory mediators in the pathogenesis of COPD.

Inhalable spray-dried porous microparticles containing dehydroandrographolide succinate phospholipid complex capable of improving and prolonging pulmonary anti-inflammatory efficacy in mice

Due to the unique physiological barriers within the lungs, there are considerable challenges in developing drug delivery systems enabling prolonged drug exposure to respiratory epithelial cells. Here, we report a PulmoSphere-based dry powder technology that incorporates a drug-phospholipid complex to promote intracellular retention of dehydroandrographolide succinate (DAS) in respiratory epithelial cells following pulmonary delivery. The DAS-phospholipid complex has the ability to self-assemble into nanoparticles. After spray-drying to produce PulmoSphere microparticles loaded with the drug-phospholipid complex, the rehydrated microparticles discharge the phospholipid complex without altering its physicochemical properties. The microparticles containing the DAS-phospholipid complex exhibit remarkable aerodynamic properties with a fine particle fraction of ∼ 60% and a mass median aerodynamic diameter of ∼ 2.3 μm. These properties facilitate deposition in the alveolar region. In vitro cell culture and lung tissue explants experiments reveal that the drug-phospholipid complex prolongs intracellular residence time and lung tissue retention due to the slow intracellular disassociation of drug from the complex. Once deposited in the lungs, the DAS-phospholipid complex loaded microparticles increase and extend drug exposure to the lung tissues and the immune cells compared to the free DAS counterpart. The improved drug exposure to airway epithelial cells, but not immune cells, is related to a prolonged duration of pulmonary anti-inflammation at decreased doses in a mouse model of acute lung injury induced by lipopolysaccharide. Overall, the phospholipid complex loaded microparticles present a promising approach for improved treatment of respiratory diseases, e.g. pneumonia and acute respiratory distress syndrome.

Identification of potential phytochemical inhibitors for the proven six chronic obstructive pulmonary disease biomarkers - A molecular dynamics study

COPD is a multifactorial lung disease causing breathing difficulties in individuals and is becoming a major health concern worldwide. The unclear pathogenic mechanism and high mortality rate urge the development of drugs against this disease. In this study, around six COPD biomarkers identified from the preceding research through integrated gene expression analysis were taken as COPD target proteins. A total of 3307 phytocompounds were included in the COPD phytocompound library from 59 therapeutic plant sources. Furthermore, a crucial three-step virtual screening process (Absorption, Distribution, Metabolism, and Excretion, respiratory nontoxicity, less harmful and nontoxic compound category) was implemented to filter the potential drug-like phytocompounds. As a result, 160 phytocompounds were filtered with desired Absorption, Distribution, Metabolism, Excretion and Toxicity properties. The filtered 160 phytocompounds were docked against six COPD target proteins and the best-docked complexes were identified through visual inspection based on six unique parameters in SeeSAR. Furthermore, the best docked complexes were subjected to molecular dynamics simulation studies to assess the stability and conformational changes of the complexes. The presence of few amino acid residues within the crucial active, allosteric and catalytic sites of the six target proteins were revealed from the binding interaction types and major residual fluctuations from molecular docking and dynamic simulation studies respectively. This is indicative of the potential inhibitory activity of phytocompounds against the COPD biomarkers. Here we report the identified phytocompounds as a promising lead molecule for the six COPD biomarkers through in silico analysis opening new avenues in COPD pathogenesis and treatments.Communicated by Ramaswamy H. Sarma.

The pulmonary biopharmaceutics and anti-inflammatory effects after intratracheal and intravenous administration of Re-Du-Ning injection

BACKGROUND

Re-Du-Ning injection (RDN) is a renowned heat-clearing traditional Chinese medicine for the treatment of respiratory diseases owing to its anti-inflammatory effects. However, very little is known about the pulmonary distribution and lung exposure-efficacy relationships. This study aimed to investigate the pulmonary distribution and biopharmaceutics concerning lung penetrability and affinity and the local anti-inflammatory effects after intravenous and pulmonary administration of RDN.

METHODS

Two iridoids and seven phenolic acid components were selected as the chemical markers in RDN. The in vitro pulmonary distribution and biopharmaceutics were conducted by evaluating the binding and disassociation kinetics of chemical markers in lung tissue explants whereas the in vivo evaluation was performed by determining the time-dependent concentrations of chemical markers in plasma, lung epithelial lining fluid (ELF), lung tissues and immune cells in the ELF after intratracheal and intravenous administrations of RDN. The inhibitory effects on tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production were used to evaluate the anti-inflammatory effect of RDN on lung tissues in vitro and on mice with LPS-induced lung inflammation.

RESULTS

The chemical markers of RDN exhibited excellent lung penetrability but poor lung affinity in vitro and in vivo. After intravenous administration, the chemical markers appeared to rapidly penetrate through the lung tissue to reach the ELF, leading to markedly higher drug exposure to ELF and immune cells in the ELF than to lung tissues. Compared to intravenous injection, the intratracheal instillation of RDN increased drug exposure to lung tissue and immune cells in the ELF by up to > 80-fold, leading to improved anti-inflammatory potency and prolonged duration of action.

CONCLUSION

The drug exposure to immune cells in the ELF was correlated with the lung-targeted anti-inflammatory effects of RDN and pulmonary delivery has the potential to replace intravenous injection of RDN for the treatment of respiratory diseases.

Review: the role of GSDMD in sepsis

Purpose

Gasdermin D (GSDMD) is a cytoplasmic protein that is encoded by the gasdermin family GSDMD gene and is the ultimate executor of pyroptosis. Pyroptosis is a mode of lysis and inflammation that regulates cell death, ultimately leading to cell swelling and rupture. In sepsis, a dysregulated host response to infection frequently results in hyperinflammatory responses and immunosuppression, eventually leading to multiple organ dysfunction. Pyroptosis regulates innate immune defenses and plays an important role in the process of inflammatory cell death, and the absence of any link in the entire pathway from GSDMD to pyroptosis causes bacterial clearance to be hampered. Under normal conditions, the process of pyroptosis occurs much faster than apoptosis, and the threat to the body is also much greater.

Materials and methods

We conducted a systematic review of relevant reviews and experimental articles using the keywords sepsis, Gasdermin D, and Pyroptosis in the PubMed, Scopus, Google Scholar, and Web of Science databases.

Conclusion

Combined with the pathogenesis of sepsis, it is not difficult to find that pyroptosis plays a key role in bacterial inflammation and sepsis. Therefore, GSDMD inhibitors may be used as targeted drugs to treat sepsis by reducing the occurrence of pyroptosis. This review mainly discusses the key role of GSDMD in sepsis.

Deciphering Respiratory-Virus-Associated Interferon Signaling in COPD Airway Epithelium

COPD is a chronic lung disorder characterized by a progressive and irreversible airflow obstruction, and persistent pulmonary inflammation. It has become a global epidemic affecting 10% of the population, and is the third leading cause of death worldwide. Respiratory viruses are a primary cause of COPD exacerbations, often leading to secondary bacterial infections in the lower respiratory tract. COPD patients are more susceptible to viral infections and associated severe disease, leading to accelerated lung function deterioration, hospitalization, and an increased risk of mortality. The airway epithelium plays an essential role in maintaining immune homeostasis, and orchestrates the innate and adaptive responses of the lung against inhaled and pathogen insults. A healthy airway epithelium acts as the first line of host defense by maintaining barrier integrity and the mucociliary escalator, secreting an array of inflammatory mediators, and initiating an antiviral state through the interferon (IFN) response. The airway epithelium is a major site of viral infection, and the interaction between respiratory viruses and airway epithelial cells activates host defense mechanisms, resulting in rapid virus clearance. As such, the production of IFNs and the activation of IFN signaling cascades directly contributes to host defense against viral infections and subsequent innate and adaptive immunity. However, the COPD airway epithelium exhibits an altered antiviral response, leading to enhanced susceptibility to severe disease and impaired IFN signaling. Despite decades of research, there is no effective antiviral therapy for COPD patients. Herein, we review current insights into understanding the mechanisms of viral evasion and host IFN antiviral defense signaling impairment in COPD airway epithelium. Understanding how antiviral mechanisms operate in COPD exacerbations will facilitate the discovery of potential therapeutic interventions to reduce COPD hospitalization and disease severity.

Role of Toll-Like Receptor 2 in Regulation of T-Helper Immune Response in Chronic Obstructive Pulmonary Disease

Objective

According to modern views, the differences in the clinical course of chronic obstructive pulmonary disease (COPD) are associated with certain types of T-helper (Th) immune response. Recent data have shown that toll-like receptor 2 (TLR2) is involved in the development of Th immune response. However, TLR2-mediated regulation of Th subpopulation balance in COPD needs to be elucidated. The aim of our work is to determine the mechanisms of TLR2-mediated regulation of Th immune response in COPD of varying severity.

Methods

The study included 323 smokers/ex-smokers with stable COPD (GOLD I, GOLD II, and GOLD III) and 97 healthy nonsmokers (control group). Serum levels of Th1 (TNF-α and IFN-γ), Th2 (IL-4), Th17 (IL-6 and IL-17A), Treg (IL-10) cytokines, and the percentage of peripheral blood Th cells expressing TLR2 (CD4⁺CD282⁺) were assessed by flow cytometry. Serum concentrations of IL-21 (Th17) and TGF-β1 (Treg) were measured using the ELISA method. The predominant Th cytokine profile in serum was determined by calculating the ratios between levels of Th1 and Th17 cytokines. Spearman's correlation test was performed.

Results

Patients with COPD GOLD II and III with Th1 and Th17 cytokine profiles exhibited an increase in the percentage of CD4⁺CD282⁺ cells compared to the control group. In COPD GOLD I–III, positive correlations between CD4⁺CD282⁺ cell frequency and Th17 cytokine levels (IL-6, IL-17A, and IL-21) were found. In COPD GOLD I, IL-10 concentration was negatively correlated with the percentages of studied cells; in COPD GOLD II, a positive correlation between these parameters was noted.

Conclusions

Enhanced TLR2 expression on CD4⁺ cells shifts cytokine profile toward Th17 phenotype that plays a crucial role in COPD progression. The level of TLR2 expression on peripheral blood CD4⁺ cells may be considered as a biomarker for diagnosing and predicting the progression of COPD.

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.

Targeted Repolarization of Tumor-Associated Macrophages via Imidazoquinoline-Linked Nanobodies

Tumor-associated macrophages (TAMs) promote the immune suppressive microenvironment inside tumors and are, therefore, considered as a promising target for the next generation of cancer immunotherapies. To repolarize their phenotype into a tumoricidal state, the Toll-like receptor 7/8 agonist imidazoquinoline IMDQ is site-specifically and quantitatively coupled to single chain antibody fragments, so-called nanobodies, targeting the macrophage mannose receptor (MMR) on TAMs. Intravenous injection of these conjugates result in a tumor- and cell-specific delivery of IMDQ into MMRhigh TAMs, causing a significant decline in tumor growth. This is accompanied by a repolarization of TAMs towards a pro-inflammatory phenotype and an increase in anti-tumor T cell responses. Therefore, the therapeutic benefit of such nanobody-drug conjugates may pave the road towards effective macrophage re-educating cancer immunotherapies.

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.

The Role of Toll-Like Receptors 2 and 4 in the Pathogenesis of Chronic Obstructive Pulmonary Disease

Currently, chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide. The determination of immune mechanisms of inflammation in the disease presents an important challenge for fundamental medical research. According to modern views, Toll-like receptors (TLRs), among which TLR2 and TLR4 play a key role, are one of the essential components of inflammatory process in COPD. This review focuses on following aspects: the role of TLR2 and TLR4 in the initiation of inflammatory process in COPD; the mechanisms of influence of various exogenous factors (cigarette smoke, suspended particulate matter, and bacteria) on the expression of TLR2 and TLR4; the contribution of these TLRs to the T-helper (Th) immune response development in COPD, in particular to the Th17 immune response, which contributes to the progression of the disease and therapeutic implications of TLR2 and TLR4 in COPD.

Sputum and blood transcriptomics characterisation of the inhaled PDE4 inhibitor CHF6001 on top of triple therapy in patients with chronic bronchitis

Background

Although phosphodiesterase-4 (PDE4) inhibitors have been shown to reduce COPD exacerbation rate, their biological mechanism of action is not completely elucidated at the molecular level. We aimed to characterise the whole genome gene expression profile of the inhaled PDE4-inhibitor CHF6001 on top of triple therapy in sputum cells and whole blood of patients with COPD and chronic bronchitis.

Methods

Whole genome gene expression analysis was carried out by microarray in 54 patients before and after 32 days treatment with CHF6001 800 and 1600 μg and placebo twice daily (BID) in a randomised crossover study.

Results

CHF6001 had a strong effect in sputum, with 1471 and 2598 significantly differentially-expressed probe-sets relative to placebo (p-adjusted for False Discovery Rate < 0.05) with 800 and 1600 μg BID, respectively. Functional enrichment analysis showed significant modulation of key inflammatory pathways involved in cytokine activity, pathogen-associated-pattern-recognition activity, oxidative stress and vitamin D with associated inhibition of downstream inflammatory effectors. A large number of pro-inflammatory genes coding for cytokines and matrix-metalloproteinases were significantly differentially expressed for both doses; the majority (> 87%) were downregulated, including macrophage inflammatory protein-1-alpha and 1-beta, interleukin-27-beta, interleukin-12-beta, interleukin-32, tumour necrosis factor-alpha-induced-protein-8, ligand-superfamily-member-15, and matrix-metalloproteinases-7,12 and 14. The effect in blood was not significant.

Conclusions

Inhaled PDE4 inhibition by CHF6001 on top of triple therapy in patients with COPD and chronic bronchitis significantly modulated key inflammatory targets and pathways in the lung but not in blood. Mechanistically these findings support a targeted effect in the lung while minimising unwanted systemic class-effects.

Trial registration

ClinicalTrial.gov, EudraCT, 2015–005550-35. Registered 15 July 2016.

Targeting IL-17A/glucocorticoid synergy to CSF3 expression in neutrophilic airway diseases

IL-17A plays a critical role in the pathogenesis of steroid-resistant neutrophilic airway inflammation, which is a hallmark of severe asthma and chronic obstructive pulmonary disease (COPD). Through RNA sequencing analysis of transcriptomes of human airway smooth muscle cells treated with IL-17A, dexamethasone (DEX, a synthetic glucocorticoid drug), alone or in combination, we identified a group of genes that are synergistically induced by IL-17A and DEX, including the neutrophil-promoting cytokine CSF3. In type-17 (Th17/IL-17Ahi) preclinical models of neutrophilic severe asthma (acute and chronic) and COPD, although DEX treatment was able to reduce the expression of neutrophil-mobilizing CXCL1 and CXCL2 in lung tissue, CSF3 expression was upregulated by DEX treatment. We found that DEX treatment alone failed to alleviate neutrophilic airway inflammation and pathology, and even exacerbated the disease phenotype when CSF3 was highly induced. Disruption of the IL-17A/DEX synergy by IL-17A inhibition with anti-IL-17A mAb or cyanidin-3-glucoside (C3G, a small-molecule IL-17A blocker) or depletion of CSF3 effectively rendered DEX sensitivity in type-17 preclinical models of neutrophilic airway diseases. Our study elucidates what we believe is a novel mechanism of steroid resistance in type-17 neutrophilic airway inflammation and offers an effective steroid-sparing therapeutic strategy (combined low-dose DEX and C3G) for treating neutrophilic airway diseases.

Comparative analysis of pathophysiological parameters between emphysematous smokers and emphysematous patients with COPD

Emphysematous smokers with normal spirometry form a considerable proportion of the clinical population. However, despite presenting with respiratory symptoms and activity limitation, they cannot be diagnosed with chronic obstructive lung disease (COPD) according to current criteria. Thus, we aimed to determine whether emphysema in smokers has a different pathogenesis from that in patients with COPD. We compared 12 pairs of lung tissue samples from emphysematous patients with normal spirometry and COPD, and determined the degree of emphysema using computed tomography. With a focus on COPD-related pathogenesis, we independently assessed inflammatory response, protease-antiprotease balance, oxidative stress, and apoptosis in both groups. Both groups showed similar pathological changes at a comparable degree of emphysema; the expression of inflammatory factors was comparable, with overexpression of proteases and decreased levels of antiproteases. Moreover, there was no significant difference in the activities of glutathione and superoxide dismutase, and expression of apoptosis-related factors. In conclusion, emphysema in smokers with normal spirometry and in patients with COPD had similar pathogenesis. Forced expiratory volume in 1 second cannot be used as the sole diagnostic criterion in patients with COPD; early intervention is of great importance to such patients.

SP-A and TLR4 localization in lung tissue of SM-exposed patients

INTRODUCTION

Long-term pulmonary complications are one of the major long-term consequences of sulfur mustard (SM) exposure. Toll-like receptor 4 (TLR4) involves in the pathogenesis of several pulmonary disorders. Surfactant protein-A (SP-A) regulates LPS-induced TLR4 localization and activation responses. However, the intensity and significance of TLR4 and SP-A expression by lung cells in SM-exposed patients is not clear.

METHODS

The gene expression of TLR4 (through real-time PCR) and TLR4 and SP-A positive cells and alveolar type II cells, as SP-A producers, (using IHC) were assessed in formalin fixed paraffin embedded (FFPE) specimens from SM-exposed (n = 17), and non-SM exposed individuals (n = 12).

RESULTS

TLR4 gene expression did not change between study groups. However, its cell surface presentation was significantly reduced in SM-exposed patients and particularly in which with constrictive bronchiolitis compared with the control group (P < 0.001 and P = 0.002, respectively). Frequency of alveolar type II cells was lower in the case group rather than the control group while the number of SP-A positive cells did not alter.

CONCLUSIONS

These findings suggest that reduced TLR4 cell surface presentation may have anti-inflammatory function and SP-A may have a critical role in regulation of inflammatory responses in SM-exposed patients. Further investigation on other possible mechanisms involved in TLR4 internalization maybe help to illustrate the modulatory or inflammatory activity of TLR4 in these patients.

Toll-Like Receptors and Relevant Emerging Therapeutics with Reference to Delivery Methods

The built-in innate immunity in the human body combats various diseases and their causative agents. One of the components of this system is Toll-like receptors (TLRs), which recognize structurally conserved molecules derived from microbes and/or endogenous molecules. Nonetheless, under certain conditions, these TLRs become hypofunctional or hyperfunctional, thus leading to a disease-like condition because their normal activity is compromised. In this regard, various small-molecule drugs and recombinant therapeutic proteins have been developed to treat the relevant diseases, such as rheumatoid arthritis, psoriatic arthritis, Crohn’s disease, systemic lupus erythematosus, and allergy. Some drugs for these diseases have been clinically approved; however, their efficacy can be enhanced by conventional or targeted drug delivery systems. Certain delivery vehicles such as liposomes, hydrogels, nanoparticles, dendrimers, or cyclodextrins can be employed to enhance the targeted drug delivery. This review summarizes the TLR signaling pathway, associated diseases and their treatments, and the ways to efficiently deliver the drugs to a target site.

New therapeutic targets for the prevention of infectious acute exacerbations of COPD: role of epithelial adhesion molecules and inflammatory pathways

Chronic respiratory diseases are among the leading causes of mortality worldwide, with the major contributor, chronic obstructive pulmonary disease (COPD) accounting for approximately 3 million deaths annually. Frequent acute exacerbations (AEs) of COPD (AECOPD) drive clinical and functional decline in COPD and are associated with accelerated loss of lung function, increased mortality, decreased health-related quality of life and significant economic costs. Infections with a small subgroup of pathogens precipitate the majority of AEs and consequently constitute a significant comorbidity in COPD. However, current pharmacological interventions are ineffective in preventing infectious exacerbations and their treatment is compromised by the rapid development of antibiotic resistance. Thus, alternative preventative therapies need to be considered. Pathogen adherence to the pulmonary epithelium through host receptors is the prerequisite step for invasion and subsequent infection of surrounding structures. Thus, disruption of bacterial-host cell interactions with receptor antagonists or modulation of the ensuing inflammatory profile present attractive avenues for therapeutic development. This review explores key mediators of pathogen-host interactions that may offer new therapeutic targets with the potential to prevent viral/bacterial-mediated AECOPD. There are several conceptual and methodological hurdles hampering the development of new therapies that require further research and resolution.

Recent clinical trends in Toll-like receptor targeting therapeutics

Toll‐like receptors (TLRs) are germline‐encoded receptors that are central to innate and adaptive immune responses. Owing to their vital role in inflammation, TLRs are rational targets in clinics; thus, many ligands and biologics have been reported to overcome the progression of various inflammatory and malignant conditions and support the immune system. For each TLR, at least one, and often many, drug formulations are being evaluated. Ligands reported as stand‐alone drugs may also be reported based on their use in combinatorial therapeutics as adjuvants. Despite their profound efficacy in TLR‐modulation in preclinical studies, multiple drugs have been terminated at different stages of clinical trials. Here, TLR modulating drugs that have been evaluated in clinical trials are discussed, along with their mode of action, suggestive failure reasons, and ways to improve the clinical outcomes. This review presents recent advances in TLR‐targeting drugs and provides directions for more successful immune system manipulation.