Up-regulation of RAGE and S100A6 in rats exposed to cigarette smoke

Blastocyst-Derived Lactic Acid May Regulate S100A6 Expression and Function in Mouse Decidualization via Stimulation of Uterine Epithelial Arachidonic Acid Secretion

(1) Background: Inflammatory responses are implicated in embryo implantation, decidualization, pregnancy maintenance and labor. Both embryo implantation and decidualization are essential to successful pregnancy in rodents and primates. S100A6 is involved in inflammation, tumor development, apoptosis and calcium homeostasis. S100A6 is strongly expressed in mouse decidua, but the underlying mechanisms of how S100A6 regulates implantation and decidualization are poorly defined. (2) Methods: Mouse endometrial stromal and epithelial cells are isolated from day 4 pseudopregnant mouse uteri. Both immunofluorescence and Western blotting are used to analyze the expression and localization of proteins. The molecular mechanism is verified in vitro by Western blotting and the quantitative polymerase chain reaction. (3) Results: From days 4 to 8 of pregnancy, S100A6 is specifically expressed in mouse subluminal stromal cells. Blastocyst-derived lactic acid induces AA secretion by activating the luminal epithelial p-cPLA2. The epithelial AA induces stromal S100A6 expression through the COX2/PGI2/PPAR δ pathway. Progesterone regulates S100A6 expression through the progesterone receptor (PR). S100A6/RAGE signaling can regulate decidualization via EGFR/ERK1/2 in vitro. (4) Conclusions: S100A6, as an inflammatory mediator, is important for mouse implantation and decidualization.

The Role of S100A6 in Human Diseases: Molecular Mechanisms and Therapeutic Potential

S100A6, also known as calcyclin, is a low-molecular-weight Ca2+-binding protein from the S100 family that contains two EF-hands. S100A6 is expressed in a variety of mammalian cells and tissues. It is also expressed in lung, colorectal, pancreatic, and liver cancers, as well as other cancers such as melanoma. S100A6 has many molecular functions related to cell proliferation, the cell cycle, cell differentiation, and the cytoskeleton. It is not only involved in tumor invasion, proliferation, and migration, but also the pathogenesis of other non-neoplastic diseases. In this review, we focus on the molecular mechanisms and potential therapeutic targets of S100A6 in tumors, nervous system diseases, leukemia, endometriosis, cardiovascular disease, osteoarthritis, and other related diseases.

The AGE-RAGE Axis and the Pathophysiology of Multimorbidity in COPD

Chronic obstructive pulmonary disease (COPD) is a disease of the airways and lungs due to an enhanced inflammatory response, commonly caused by cigarette smoking. Patients with COPD are often multimorbid, as they commonly suffer from multiple chronic (inflammatory) conditions. This intensifies the burden of individual diseases, negatively affects quality of life, and complicates disease management. COPD and comorbidities share genetic and lifestyle-related risk factors and pathobiological mechanisms, including chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) is an important driver of chronic inflammation. Advanced glycation end products (AGEs) are RAGE ligands that accumulate due to aging, inflammation, oxidative stress, and carbohydrate metabolism. AGEs cause further inflammation and oxidative stress through RAGE, but also through RAGE-independent mechanisms. This review describes the complexity of RAGE signaling and the causes of AGE accumulation, followed by a comprehensive overview of alterations reported on AGEs and RAGE in COPD and in important co-morbidities. Furthermore, it describes the mechanisms by which AGEs and RAGE contribute to the pathophysiology of individual disease conditions and how they execute crosstalk between organ systems. A section on therapeutic strategies that target AGEs and RAGE and could alleviate patients from multimorbid conditions using single therapeutics concludes this review.

Lung injury and oxidative stress induced by inhaled chlorine in mice is associated with proinflammatory activation of macrophages and altered bioenergetics

Chlorine (Cl2) gas is a highly toxic and oxidizing irritant that causes life-threatening lung injuries. Herein, we investigated the impact of Cl2-induced injury and oxidative stress on lung macrophage phenotype and function. Spontaneously breathing male C57BL/6J mice were exposed to air or Cl2 (300 ppm, 25 min) in a whole-body exposure chamber. Bronchoalveolar lavage (BAL) fluid and cells, and lung tissue were collected 24 h later and analyzed for markers of injury, oxidative stress and macrophage activation. Exposure of mice to Cl2 resulted in increases in numbers of BAL cells and levels of IgM, total protein, and fibrinogen, indicating alveolar epithelial barrier dysfunction and inflammation. BAL levels of inflammatory proteins including surfactant protein (SP)-D, soluble receptor for glycation end product (sRAGE) and matrix metalloproteinase (MMP)-9 were also increased. Cl2 inhalation resulted in upregulation of phospho-histone H2A.X, a marker of double-strand DNA breaks in the bronchiolar epithelium and alveolar cells; oxidative stress proteins, heme oxygenase (HO)-1 and catalase were also upregulated. Flow cytometric analysis of BAL cells revealed increases in proinflammatory macrophages following Cl2 exposure, whereas numbers of resident and antiinflammatory macrophages were not altered. This was associated with increases in numbers of macrophages expressing cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS), markers of proinflammatory activation, with no effect on mannose receptor (MR) or Ym-1 expression, markers of antiinflammatory activation. Metabolic analysis of lung cells showed increases in glycolytic activity following Cl2 exposure in line with proinflammatory macrophage activation. Mechanistic understanding of Cl2-induced injury will be useful in the identification of efficacious countermeasures for mitigating morbidity and mortality of this highly toxic gas.

Metal exposure from additive manufacturing and its effect on the nasal lavage fluid proteome - a pilot study

The use of metal additive manufacturing (AM) is steadily increasing and is an emerging concern regarding occupational exposure. In this study, non-invasive sampled nasal lavage fluid (NLF) from the upper airways was collected from metal AM operators at the beginning and end of a workweek during two consecutive years with preventive interventions in the occupational setting in-between (n = 5 year 1, n = 9 year 2). During year one, NLF was also collected from welders (n = 6) from the same company to get a comparison with a traditional manufacturing technique with known exposure and health risks. The samples were investigated using untargeted proteomics, as well as using multi-immunoassay to analyze a panel of 71 inflammatory protein markers. NLF in AM operators from year 1 showed decreased levels of Immunoglobulin J and WAP four-disulfide core domain protein 2 and increased levels of Golgi membrane protein 1, Uteroglobin and Protein S100-A6 at the end of the workweek. At year two, after preventive interventions, there were no significant differences at the end of the workweek. In welders, Annexin A1 and Protein S100-A6 were increased at the end of the workweek. The analysis of 71 inflammatory biomarkers showed no significant differences between the beginning and the end of workweek year 1 in AM operators. We identified several proteins of interest in the AM operators that could serve as possible markers for exposure in future studies with a larger cohort for validation.

Cigarette Smoke Condensate Exposure Induces Receptor for Advanced Glycation End-Products (RAGE)-Dependent Sterile Inflammation in Amniotic Epithelial Cells

Maternal smoking is a risk factor of preterm prelabor rupture of the fetal membranes (pPROM), which is responsible for 30% of preterm births worldwide. Cigarettes induce oxidative stress and inflammation, mechanisms both implicated in fetal membranes (FM) weakening. We hypothesized that the receptor for advanced glycation end-products (RAGE) and its ligands can result in cigarette-dependent inflammation. FM explants and amniotic epithelial cells (AECs) were treated with cigarette smoke condensate (CSC), combined or not with RAGE antagonist peptide (RAP), an inhibitor of RAGE. Cell suffering was evaluated by measuring lactate dehydrogenase (LDH) medium-release. Extracellular HMGB1 (a RAGE ligand) release by amnion and choriodecidua explants were checked by western blot. NF-κB pathway induction was determined by a luciferase gene reporter assay, and inflammation was evaluated by cytokine RT-qPCR and protein quantification. Gelatinase activity was assessed using a specific assay. CSC induced cell suffering and HMGB1 secretion only in the amnion, which is directly associated with a RAGE-dependent response. CSC also affected AECs by inducing inflammation (cytokine release and NFκB activation) and gelatinase activity through RAGE engagement, which was linked to an increase in extracellular matrix degradation. This RAGE dependent CSC-induced inflammation associated with an increase of gelatinase activity could explain a pathological FM weakening directly linked to pPROM.

The S100 Protein Family as Players and Therapeutic Targets in Pulmonary Diseases

The S100 protein family consists of over 20 members in humans that are involved in many intracellular and extracellular processes, including proliferation, differentiation, apoptosis, Ca₂⁺ homeostasis, energy metabolism, inflammation, tissue repair, and migration/invasion. Although there are structural similarities between each member, they are not functionally interchangeable. The S100 proteins function both as intracellular Ca²⁺ sensors and as extracellular factors. Dysregulated responses of multiple members of the S100 family are observed in several diseases, including the lungs (asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis, pulmonary hypertension, and lung cancer). To this degree, extensive research was undertaken to identify their roles in pulmonary disease pathogenesis and the identification of inhibitors for several S100 family members that have progressed to clinical trials in patients for nonpulmonary conditions. This review outlines the potential role of each S100 protein in pulmonary diseases, details the possible mechanisms observed in diseases, and outlines potential therapeutic strategies for treatment.

Perinatal nicotine exposure alters lung development and induces HMGB1-RAGE expression in neonatal mice

BACKGROUND

Maternal nicotine exposure during gestation and lactation adversely affect lung development of their children. High-mobility group box 1 (HMGB1) is the encoded non-histone, nuclear DNA-binding protein that regulates transcription, and is involved in organization of DNA. Receptors for advanced glycation end products (RAGE) is a receptor for HMGB1 and activates nuclear factor-κB (NF-κB) signaling. Animal and human studies have found cigarette smoke exposure upregulates RAGE expression, suggesting that the HMGB1-RAGE pathway might be involved in maternal nicotine-induced lung injury.

METHODS

This study evaluated prenatal and perinatal nicotine effects on lung development and HMGB1 and RAGE expression in mouse offspring. Nicotine was administered to pregnant mice by subcutaneous osmotic mini-pump at a dose of 6 mg kg^-1 day^-1 from gestational Day 14 to birth (prenatal) or to postnatal Day 21 (perinatal). A control group received an equal volume of saline by the same route. Three study groups were obtained: prenatal normal saline (NS), prenatal nicotine, and perinatal nicotine groups. The mice were euthanized on postnatal Day 21, and the lung tissues were collected for histological and Western blot analyses.

RESULTS

Mice exposed to prenatal nicotine exhibited significantly higher lung mean chord length and oxidative stress marker 8-hydroxy-2'-deoxyguanosine and NF-κB expression compared to mice exposed to NS. Perinatal nicotine exposure further enhanced these harmful effects. These perinatal nicotine effects on lung development were associated with increased HMGB1 and RAGE expression.

CONCLUSIONS

HMGB1-RAGE pathway may be involved in the pathogenesis of altered lung development induced by perinatal nicotine exposure.

Single-photon emission computed tomography/computed tomography imaging of RAGE in smoking-induced lung injury

Background

Expression of the Receptor for Advanced Glycation Endproducts (RAGE) initiates pro-inflammatory pathways resulting in lung destruction. We hypothesized that RAGE directed imaging demonstrates increased lung uptake in smoke-exposure.

Methods

After exposure to room air or to cigarette smoke for 4-weeks or 16-weeks, rabbits were injected with ^99mTc-anti-RAGE F(ab’)₂ and underwent Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) imaging. Lung radiotracer uptake was calculated as percent injected dose (%ID). Lungs were dissected for gamma well counting and histological analysis.

Results

^99mTc-anti-RAGE F(ab’)₂ SPECT/CT imaging demonstrated increased lung expression of RAGE with smoke exposure compared to room air control at 4-weeks: Room air right (R) 0.75 ± 0.38%ID, left (L) 0.62 ± 0.32%ID vs. Smoke exposed R 0.17 ± 0.03, L 0.17 ± 0.02%ID (p = 0.02 and 0.028, respectively). By 16-weeks of smoke exposure, the uptake decreased to 0.19 ± 0.05%ID R and 0.17 ± 0.05%ID L, significantly lower than 4-week imaging (p = 0.0076 and 0.0129 respectively). Staining for RAGE confirmed SPECT results, with the RAGE ligand HMGB1 upregulated in the macrophages of 4-week smoke-exposed rabbits.

Conclusions

RAGE-directed imaging identified pulmonary RAGE expression acutely in vivo in an animal model of emphysema early after smoke exposure, with diminution over time. These studies document the extent and time course of RAGE expression under smoke exposure conditions and could be utilized for disease monitoring and examining response to future RAGE-targeted therapies.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1064-4) contains supplementary material, which is available to authorized users.

Effect of long-term maternal smoking on the offspring's lung health

Maternal smoking during pregnancy contributes to long-term health problems in offspring, especially respiratory disorders that can manifest in either childhood or adulthood. Receptors for advanced glycation end products (RAGE) are multiligand receptors abundantly localized in the lung, capable of responding to by-products of reactive oxygen species and proinflammatory responses. RAGE signaling is a key regulator of inflammation in cigarette smoking-related pulmonary diseases. However, the impact of maternal cigarette smoke exposure on lung RAGE signaling in the offspring is unclear. This study aims to investigate the effect of maternal cigarette smoke exposure (SE), as well as mitochondria-targeted antioxidant [mitoquinone mesylate (MitoQ)] treatment, during pregnancy on the RAGE-mediated signaling pathway in the lung of male offspring. Female Balb/c mice (8 wk) were divided into a sham group (exposed to air), an SE group (exposed to cigarette smoke), and an SE + MQ group (exposed to cigarette smoke with MitoQ supplement from mating). The lungs from male offspring were collected at 13 wk. RAGE and its downstream signaling, including nuclear factor-κB and mitogen-activated protein kinase family consisting of extracellular signal-regulated kinase 1, ERK2, c-JUN NH2-terminal kinase (JNK), and phosphorylated JNK, in the lung were significantly increased in the SE offspring. Mitochondrial antioxidant manganese superoxide dismutase was reduced, whereas IL-1β and oxidative stress response nuclear factor (erythroid-derived 2)-like 2 were significantly increased in the SE offspring. Maternal MitoQ treatment normalized RAGE, IL-1β, and Nrf-2 levels in the SE + MQ offspring. Maternal SE increased RAGE and its signaling elements associated with increased oxidative stress and inflammatory cytokines in offspring lungs, whereas maternal MitoQ treatment can partially normalize these changes.

The effects of MEK1/2 inhibition on cigarette smoke exposure-induced ET receptor upregulation in rat cerebral arteries

Cigarette smoking, a major stroke risk factor, upregulates endothelin receptors in cerebral arteries. The present study examined the effects of MEK1/2 pathway inhibition on cigarette smoke exposure-induced ET receptor upregulation. Rats were exposed to the secondhand smoke (SHS) for 8weeks followed by intraperitoneal injection of MEK1/2 inhibitor, U0126 for another 4weeks. The urine cotinine levels were assessed with high-performance liquid chromatography. Contractile responses of isolated cerebral arteries were recorded by a sensitive wire myograph. The mRNA and protein expression levels of receptor and MEK/ERK1/2 pathway molecules were examined by real-time PCR and Western blotting, respectively. Cerebral artery receptor localization was determined with immunohistochemistry. The results showed the urine cotinine levels from SHS exposure group were significantly higher than those from the fresh group. In addition, the MEK1/2 inhibitor, U0126 significantly reduced SHS exposure-increased ETA receptor mRNA and protein levels as well as contractile responses mediated by ETA receptors. The immunoreactivity of increased ETA receptor expression was primarily cytoplasmic in smooth muscle cells. In contrast, ETB receptor was noted in endothelial cells. However, the SHS-induced decrease in endothelium-dependent relaxation was unchanged after U0126 treatment. Furthermore, SHS increased the phosphorylation of MEK1/2 and ERK1/2 protein in cerebral arteries. By using U0126 could inhibit the phosphorylated ERK1/2 protein but not MEK1/2. Taken together, our data show that treatment with MEK1/2 pathway inhibitor offsets SHS exposure-induced ETA receptor upregulation in rat cerebral arteries.

RAGE-ligands axis: A new 'driving force' for cigarette smoke-induced airway inflammation in COPD?

Receptor for advanced glycation end products (RAGE) was recently shown to contribute to cigarette smoke (CS)-induced airway inflammation in chronic obstructive pulmonary disease (COPD). In this study, RAGE small interfering ribonucleic acid (RNA) transfection attenuated increased messenger RNA levels of common RAGE ligands HMGB1, S100A8, S100A9 and S100A12, but not S100B following exposure to CS extract. Our findings and those from recent studies suggest a positive feedback involving RAGE and its ligands as a new 'driving force' for CS-induced airway inflammation in COPD.

Oxidative DNA damage is involved in cigarette smoke-induced lung injury in rats

OBJECTIVE

Reactive oxygen species (ROS) induced by exogenous toxicants are suggested to be involved in carcinogenesis by oxidative modification of DNA. 8-Hydroxyl-2-deoxyguanosine (8-OHdG) has been considered as a reliable biomarker for oxidative DNA damage both in vivo and in vitro studies. But the effect of smoking on oxidative damage has not yet been fully elucidated.

METHODS

Wistar rats were exposed to cigarette smoke at concentrations of 20 and 60 % for 30 min, twice/day for 45 weeks. Then the histopathology of lung tissues, levels of ROS, 8-OHdG, and total antioxidant (T-AOC), expression of DNA repair enzymes, e.g. 8-oxyguaine DNA glycosylase (OGG1), and MutThomolog 1 (Oxidized Purine Nucleoside Triphosphatase, MTH1) were determined in urine, peripheral blood lymphocytes, and lung tissue.

RESULTS

The results showed that long-term cigarette smoke exposure can cause obvious damages of lung tissue in rats. In addition, a significant and cigarette smoke concentration-dependent increase in ROS and 8-OHdG were observed compared with the non-exposed control rats. In contrast, the expression of OGG1 and MTH1, and T-AOC levels were obviously decreased after long-term exposure to cigarette smoke.

CONCLUSION

These findings indicate that long-term exposure to cigarette smoker increases ROS levels, decreases total antioxidant capacity, and interferes DNA repair capacity that eventually induces oxidative DNA damage, which appears to play an important role in cigarette smoke-induced lung injury in rats, and determination of 8-OHdG levels might be a useful method for monitoring oxidative damage in cigarette smokers.

Conditionally induced RAGE expression by proximal airway epithelial cells in transgenic mice causes lung inflammation

Background

Receptors for advanced glycation end-products (RAGE) are multiligand cell-surface receptors expressed abundantly by distal pulmonary epithelium. Our lab has discovered RAGE-mediated effects in the orchestration of lung inflammation induced by tobacco smoke and environmental pollutants; however, the specific contribution of RAGE to the progression of proximal airway inflammation is still inadequately characterized.

Methods and results

We generated a Tet-inducible transgenic mouse that conditionally overexpressed RAGE using the club cell (Clara) secretory protein (CCSP) promoter expressed by club (Clara) cells localized to the proximal airway. RAGE was induced for 40 days from weaning (20 days of age) until sacrifice date at 60 days. Immunohistochemistry, immunoblotting, and qPCR revealed significant RAGE up-regulation when compared to non-transgenic controls; however, H&E staining revealed no detectible morphological abnormalities and apoptosis was not enhanced during the 40 days of augmentation. Freshly procured bronchoalveolar lavage fluid (BALF) from CCSP-RAGE TG mice had significantly more total leukocytes and PMNs compared to age-matched control littermates. Furthermore, CCSP-RAGE TG mice expressed significantly more tumor necrosis factor alpha (TNF-α), interleukin 7 (IL-7), and interleukin 14 (IL-14) in whole lung homogenates compared to controls.

Conclusions

These data support the concept that RAGE up-regulation specifically in lung airways may function in the progression of proximal airway inflammation.

Association of polymorphisms of the receptor for advanced glycation end products gene with COPD in the Chinese population

The receptor for advanced glycation end products (RAGE) is a cell surface molecule of the immunoglobulin superfamily that binds diverse endogenous ligands involved in the development of chronic diseases and inflammatory damage. A growing body of evidence has suggested that RAGE is involved in the development and progression of chronic obstructive pulmonary disease (COPD). The present study investigated the existence of an association among three polymorphisms (-374T/A, -429T/C, and G82S) of the RAGE gene with the risk of COPD in the Chinese population. The RAGE genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 216 patients with COPD and 239 age-matched healthy individuals. Our study demonstrated that the frequencies of the GS genotype and the S allele in the G82S mutation were significantly higher in COPD patients than in controls (odds ratios [OR]=1.70, 95% confidence interval [CI]: 1.15-2.50, p=0.0098 and OR=1.42, 95% CI: 1.06-1.91, p=0.023, respectively). Further stratification analysis by smoking status revealed that the presence of the GS genotype conferred a higher risk of developing COPD in current smokers (p=0.044). In contrast, mutations at -374T/A and -429T/C did not demonstrate any association with COPD, even after taking into account the patients' smoking history. Our study provides preliminary evidence that the G82S polymorphism in the RAGE gene is associated with an increased risk of COPD and that the GS genotype of the G82S variant is a risk factor for COPD in the Chinese population.

RAGE: a new frontier in chronic airways disease

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous inflammatory disorders of the respiratory tract characterized by airflow obstruction. It is now clear that the environmental factors that drive airway pathology in asthma and COPD, including allergens, viruses, ozone and cigarette smoke, activate innate immune receptors known as pattern-recognition receptors, either directly or indirectly by causing the release of endogenous ligands. Thus, there is now intense research activity focused around understanding the mechanisms by which pattern-recognition receptors sustain the airway inflammatory response, and how these mechanisms might be targeted therapeutically. One pattern-recognition receptor that has recently come to attention in chronic airways disease is the receptor for advanced glycation end products (RAGE). RAGE is a member of the immunoglobulin superfamily of cell surface receptors that recognizes pathogen- and host-derived endogenous ligands to initiate the immune response to tissue injury, infection and inflammation. Although the role of RAGE in lung physiology and pathophysiology is not well understood, recent genome-wide association studies have linked RAGE gene polymorphisms with airflow obstruction. In addition, accumulating data from animal and clinical investigations reveal increased expression of RAGE and its ligands, together with reduced expression of soluble RAGE, an endogenous inhibitor of RAGE signalling, in chronic airways disease. In this review, we discuss recent studies of the ligand-RAGE axis in asthma and COPD, highlight important areas for future research and discuss how this axis might potentially be harnessed for therapeutic benefit in these conditions.