Dietary advanced glycation end-products, its pulmonary receptor, and high mobility group box 1 in aspiration lung injury

Serum Biomarkers in Differential Diagnosis of Idiopathic Pulmonary Fibrosis and Connective Tissue Disease-Associated Interstitial Lung Disease

Introduction: The goal of this study is to determine whether Advanced glycosylated end-products (AGE), Advanced oxidation protein products (AOPP) and Matrix metalloproteinase 7 (MMP7) could be used as differential biomarkers for idiopathic pulmonary fibrosis (IPF) and connective tissue disease-associated interstitial lung disease (CTD-ILD). Method: Seventy-three patients were enrolled: 29 with IPF, 14 with CTD-ILD, and 30 healthy controls. The study included a single visit by participants. A blood sample was drawn and serum was analysed for AGE using spectrofluorimetry, AOPP by spectrophotometry, and MMP7 using sandwich-type enzyme-linked immunosorbent assay. Results: AGE, AOPP and MMP7 serum levels were significantly higher in both IPF and CTD-ILD patients versus healthy controls; and AGE was also significantly elevated in CTD-ILD compared to the IPF group. AGE plasma levels clearly distinguished CTD-ILD patients from healthy participants (AUC = 0.95; 95% IC 0.86–1), whereas in IPF patients, the distinction was moderate (AUC = 0.78; 95% IC 0.60–0.97). Conclusion: In summary, our results provide support for the potential value of serum AGE, AOPP and MMP7 concentrations as diagnostic biomarkers in IPF and CTD-ILD to differentiate between ILD patients and healthy controls. Furthermore, this study provides evidence, for the first time, for the possible use of AGE as a differential diagnostic biomarker to distinguish between IPF and CTD-ILD. The value of these biomarkers as additional tools in a multidisciplinary approach to IPF and CTD-ILD diagnosis needs to be considered and further explored. Multicentre studies are necessary to understand the role of AGE in differential diagnosis.

Role of Atypical Chemokines and Chemokine Receptors Pathways in the Pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) represents a heightened inflammatory response in the lung generally resulting from tobacco smoking-induced recruitment and activation of inflammatory cells and/or activation of lower airway structural cells. Several mediators can modulate activation and recruitment of these cells, particularly those belonging to the chemokines (conventional and atypical) family. There is emerging evidence for complex roles of atypical chemokines and their receptors (such as high mobility group box 1 (HMGB1), antimicrobial peptides, receptor for advanced glycosylation end products (RAGE) or toll-like receptors (TLRs)) in the pathogenesis of COPD, both in the stable disease and during exacerbations. Modulators of these pathways represent potential novel therapies for COPD and many are now in preclinical development. Inhibition of only a single atypical chemokine or receptor may not block inflammatory processes because there is redundancy in this network. However, there are many animal studies that encourage studies for modulating the atypical chemokine network in COPD. Thus, few pharmaceutical companies maintain a significant interest in developing agents that target these molecules as potential antiinflammatory drugs. Antibody-based (biological) and small molecule drug (SMD)-based therapies targeting atypical chemokines and/or their receptors are mostly at the preclinical stage and their progression to clinical trials is eagerly awaited. These agents will most likely enhance our knowledge about the role of atypical chemokines in COPD pathophysiology and thereby improve COPD management.

The pathophysiology of SARS-CoV-2: A suggested model and therapeutic approach

In this paper, a model is proposed of the pathophysiological processes of COVID-19 starting from the infection of human type II alveolar epithelial cells (pneumocytes) by SARS-CoV-2 and culminating in the development of ARDS. The innate immune response to infection of type II alveolar epithelial cells leads both to their death by apoptosis and pyroptosis and to alveolar macrophage activation. Activated macrophages secrete proinflammatory cytokines and chemokines and tend to polarise into the inflammatory M1 phenotype. These changes are associated with activation of vascular endothelial cells and thence the recruitment of highly toxic neutrophils and inflammatory activated platelets into the alveolar space. Activated vascular endothelial cells become a source of proinflammatory cytokines and reactive oxygen species (ROS) and contribute to the development of coagulopathy, systemic sepsis, a cytokine storm and ARDS. Pulmonary activated platelets are also an important source of proinflammatory cytokines and ROS, as well as exacerbating pulmonary neutrophil-mediated inflammatory responses and contributing to systemic sepsis by binding to neutrophils to form platelet-neutrophil complexes (PNCs). PNC formation increases neutrophil recruitment, activation priming and extraversion of these immune cells into inflamed pulmonary tissue, thereby contributing to ARDS. Sequestered PNCs cause the development of a procoagulant and proinflammatory environment. The contribution to ARDS of increased extracellular histone levels, circulating mitochondrial DNA, the chromatin protein HMGB1, decreased neutrophil apoptosis, impaired macrophage efferocytosis, the cytokine storm, the toll-like receptor radical cycle, pyroptosis, necroinflammation, lymphopenia and a high Th17 to regulatory T lymphocyte ratio are detailed.

Kaempferol Improves Lung Ischemia-Reperfusion Injury via Antiinflammation and Antioxidative Stress Regulated by SIRT1/HMGB1/NF-κB Axis

Trauma, organ transplantation, and thromboembolism are the main causes of lung ischemia-reperfusion injury (LIRI), and new therapies and drugs are urgent to relieve LIRI. In preliminary experiment, authors found that kaempferol could improve LIRI in rats, and the current study further explored its possible mechanism. The model of rat LIRI was established and appropriate research methods were implemented. Results shown that kaempferol could significantly improve LIRI, inhibit release of inflammatory factors including interleukin (IL) 6 and tumor necrosis factor (TNF) α in bronchoalveolar lavage fluid, and reduce oxidative stress reaction. Western blotting was used to detect protein expression levels and found that kaempferol could up-regulate the protein expressions of phosphorylated (p-) p65 and p65, and down-regulate the protein expression of sirtuin (SIRT) 1. Immunofluorescence was used to localize the expression of high mobility group box (HMGB) 1 and found its higher expression in outside of nucleus. However, the above effects of kaempferol on LIRI markedly attenuated by EX 527, a selective inhibitor of SIRT 1. Taken together, we first reported the protective effect of kaempferol on rat LIRI and confirmed that kaempferol’s antiinflammation and antioxidative stress involving the SIRT1/HMGB1/NF-κB axis.

Increased risk of respiratory diseases in adults with Type 1 and Type 2 diabetes

AIMS

Diabetes is linked with decreases in lung elasticity and in capacity to transfer carbon monoxide. Systemic inflammation, a common concern with diabetes, may contribute to airflow obstruction. We examined the association of self-reported diabetes with self-reported respiratory diseases (RDs) among 53,146 adults from the C8 Health Project.

METHODS

Participants were categorized into three groups: Type 1 (T1D, n = 781), Type 2 (T2D, n = 4277), or no diabetes (n = 48,088). ORs (95% CIs) for the association of diabetes with four RDs were computed: emphysema, chronic obstructive pulmonary disease (COPD), chronic bronchitis (CB), and asthma. Covariates controlled for were age, sex, estimated glomerular filtration rate, C-reactive protein, smoking history, BMI, and perfluorooctonaoic acid (C8).

RESULTS

RDs were present in 26%, 21% and 13% of persons with T1D, T2D, and no diabetes, respectively. In multivariable analyses, persons with T1D were 62% more likely to have any RD (OR: 1.62, CI: (1.36-1.93)), while those with T2D were 1.3 times as likely (OR: 1.26, CI: 1.15-1.37)). Compared to those without diabetes, in those with T1D and T2D diabetes respectively, ORs (CIs) for COPD were 1.89 (1.38-2.57), 1.45 (1.23-1.71), asthma: 1.51 (1.21-1.87), 1.38 (1.24-1.53), CB: 1.96 (1.57-2.45), 1.35 (1.20-1.52) and emphysema: 1.25 (0.85-1.82), 1.31 (1.10-1.56). Population attributable risks for any RDs associated with a history of smoking were 19%, 30%, and 26% for those with Type 1, Type 2, and no diabetes respectively.

CONCLUSIONS

Diabetes, more so in T1D, appears to increase RD risk. Smoking is an important risk factor, but not as informative in Type 1 diabetes.

Emerging role of HMGB1 in lung diseases: friend or foe

Lung diseases remain a serious problem for public health. The immune status of the body is considered to be the main influencing factor for the progression of lung diseases. HMGB1 (high‐mobility group box 1) emerges as an important molecule of the body immune network. Accumulating data have demonstrated that HMGB1 is crucially implicated in lung diseases and acts as independent biomarker and therapeutic target for related lung diseases. This review provides an overview of updated understanding of HMGB1 structure, release styles, receptors and function. Furthermore, we discuss the potential role of HMGB1 in a variety of lung diseases. Further exploration of molecular mechanisms underlying the function of HMGB1 in lung diseases will provide novel preventive and therapeutic strategies for lung diseases.

Xuebijing Ameliorates Sepsis-Induced Lung Injury by Downregulating HMGB1 and RAGE Expressions in Mice

Xuebijing (XBJ) injection, a traditional Chinese medicine, has been reported as a promising approach in the treatment of sepsis in China. However, its actual molecular mechanisms in sepsis-induced lung injury are yet unknown. Therefore, this study aimed to investigate the beneficial effects of XBJ on inflammation and the underlying mechanisms in a model of caecal ligation and puncture-(CLP-) induced lung injury. The mice were divided into CLP group, CLP+XBJ group (XBJ, 4 mL/kg per 12 hours), and sham group. The molecular and histological examinations were performed on the lung, serum, and bronchoalveolar lavage (BAL) fluid samples of mice at the points of 6, 24, and 48 hours after CLP. The results show that XBJ reduces morphological destruction and neutrophil infiltration in the alveolar space and lung wet/dry weight ratio, which improves mortality of CLP-induced lung injury. Meanwhile, XBJ treatment downregulates high mobility group box protein 1 (HMGB1) and the receptor for advanced glycation end products (RAGE) expression, as well as neutrophil counts, production of IL-1β, IL-6, and TNF-α in the BAL fluids. In conclusion, these results indicate that XBJ may reduce the mortality through inhibiting proinflammatory cytokines secretion mediated by HMGB1/RAGE axis.

Effect of chronic hypoxia on RAGE and its soluble forms in lungs and plasma of mice

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor. Alternative splicing and enzymatic shedding produce soluble forms that protect against damage by ligands including Advanced Glycation End products (AGEs). A link between RAGE and oxygen levels is evident from studies showing RAGE-mediated injury following hyperoxia. The effect of hypoxia on pulmonary RAGE expression and circulating sRAGE levels is however unknown. Therefore mice were exposed to chronic hypoxia for 21 d and expression of RAGE, sheddases in lungs and circulating sRAGE were determined. In addition, accumulation of AGEs in lungs and expression of the AGE detoxifying enzyme GLO1 and receptors were evaluated. In lung tissue gene expression of total RAGE, variants 1 and 3 were elevated in mice exposed to hypoxia, whereas mRAGE and sRAGE protein levels were decreased. In the hypoxic group plasma sRAGE levels were enhanced. Although the levels of pro-ADAM10 were elevated in lungs of hypoxia exposed mice, the relative amount of the active form was decreased and gelatinase activity unaffected. In the lungs, the RAGE ligand HMGB1 was decreased and of the AGEs, only LW-1 was increased by chronic hypoxia. Gene expression of AGE receptors 2 and 3 was significantly upregulated. Chronic hypoxia is associated with downregulation of pulmonary RAGE protein levels, but a relative increase in sRAGE. These alterations might be part of the adaptive and protective response mechanism to chronic hypoxia and are not associated with AGE formation except for the fluorophore LW-1 which emerges as a novel marker of tissue hypoxia.