Availability of Receptors for Advanced Glycation End-Products (RAGE) Influences Differential Transcriptome Expression in Lungs from Mice Exposed to Chronic Secondhand Smoke (SHS).

The receptor for advanced glycation end-products (RAGE) has a central function in orchestrating inflammatory responses in multiple disease states including chronic obstructive pulmonary disease (COPD). RAGE is a transmembrane pattern recognition receptor with particular interest in lung disease due to its naturally abundant pulmonary expression. Our previous research demonstrated an inflammatory role for RAGE following acute exposure to secondhand smoke (SHS). However, chronic inflammatory mechanisms associated with RAGE remain ambiguous. In this study, we assessed transcriptional outcomes in mice exposed to chronic SHS in the context of RAGE expression. RAGE knockout (RKO) and wild-type (WT) mice were delivered nose-only SHS via an exposure system for six months and compared to control mice exposed to room air (RA). We specifically compared WT + RA, WT + SHS, RKO + RA, and RKO + SHS. Analysis of gene expression data from WT + RA vs. WT + SHS showed FEZ1, Slpi, and Msln as significant at the three-month time point; while RKO + SHS vs. WT + SHS identified cytochrome p450 1a1 and Slc26a4 as significant at multiple time points; and the RKO + SHS vs. WT + RA revealed Tmem151A as significant at the three-month time point as well as Gprc5a and Dynlt1b as significant at the three- and six-month time points. Notable gene clusters were functionally analyzed and discovered to be specific to cytoskeletal elements, inflammatory signaling, lipogenesis, and ciliogenesis. We found gene ontologies (GO) demonstrated significant biological pathways differentially impacted by the presence of RAGE. We also observed evidence that the PI3K-Akt and NF-κB signaling pathways were significantly enriched in DEGs across multiple comparisons. These data collectively identify several opportunities to further dissect RAGE signaling in the context of SHS exposure and foreshadow possible therapeutic modalities.

The Effect of Diesel Exhaust Particles on Adipose Tissue Mitochondrial Function and Inflammatory Status.

Air pollution poses a significant global health risk, with fine particulate matter (PM2.5) such as diesel exhaust particles (DEPs) being of particular concern due to their potential to drive systemic toxicities through bloodstream infiltration. The association between PM2.5 exposure and an increased prevalence of metabolic disorders, including obesity, metabolic syndrome, and type 2 diabetes mellitus (T2DM), is evident against a backdrop of rising global obesity and poor metabolic health. This paper examines the role of adipose tissue in mediating the effects of PM2.5 on metabolic health. Adipose tissue, beyond its energy storage function, is responsive to inhaled noxious stimuli, thus disrupting metabolic homeostasis and responding to particulate exposure with pro-inflammatory cytokine release, contributing to systemic inflammation. The purpose of this study was to characterize the metabolic response of adipose tissue in mice exposed to either DEPs or room air (RA), exploring both the adipokine profile and mitochondrial bioenergetics. In addition to a slight change in fat mass and a robust shift in adipocyte hypertrophy in the DEP-exposed animals, we found significant changes in adipose mitochondrial bioenergetics. Furthermore, the DEP-exposed animals had a significantly higher expression of adipose inflammatory markers compared with the adipose from RA-exposed mice. Despite the nearly exclusive focus on dietary factors in an effort to better understand metabolic health, these results highlight the novel role of environmental factors that may contribute to the growing global burden of poor metabolic health.

Respirable dust and crystalline silica concentrations among workers at a brick kiln in Bhaktapur, Nepal.

Exposure to respirable dust and crystalline silica (SiO2) has been linked to chronic obstructive pulmonary disease, silicosis, cancer, heart disease, and other respiratory diseases. Relatively few studies have measured respirable dust and SiO2 concentrations among workers at brick kilns in low- and middle-income countries. The purpose of this study was to measure personal breathing zone (PBZ) respirable dust and SiO2 concentrations among workers at one brick kiln in Bhaktapur, Nepal. A cross-sectional study was conducted among 49 workers in five job categories: administration, fire master, green (unfired) brick hand molder, green brick machine molder, and top loader. PBZ air samples were collected from each worker following Methods 0600 (respirable dust) and 7500 (respirable crystalline SiO2: cristobalite, quartz, tridymite) of the U.S. National Institute for Occupational Safety and Health. Eight-hour time-weighted average (TWA) respirable dust and quartz concentrations were also calculated. SiO2 percentage was measured in one bulk sample each of wet clay, the release agent used by green brick hand molders, and top coat soil at the brick kiln. The geometric mean (GM) sample and TWA respirable dust concentrations were 0.20 (95% confidence interval [CI]: 0.16, 0.27) and 0.12 (95% CI: 0.09, 0.16) mg/m3, respectively. GM sample and TWA quartz concentrations were 15.28 (95% CI: 11.11, 21.02) and 8.60 (95% CI: 5.99, 12.34) µg/m3, respectively. Job category was significantly associated with GM sample and TWA respirable dust and quartz concentrations (all p < 0.0001). Top loaders had the highest GM sample and TWA respirable dust concentrations of 1.49 and 0.99 mg/m3, respectively. Top loaders also had the highest GM sample and TWA quartz concentrations of 173.08 and 114.39 µg/m3, respectively. Quartz percentages in bulk samples were 16%-27%. Interventions including using wet methods to reduce dust generation, administrative controls, personal protective equipment, and education and training should be implemented to reduce brick kiln worker exposures to respirable dust and SiO2.

A Potential Role for the Receptor for Advanced Glycation End-Products (RAGE) in the Development of Secondhand Smoke-Induced Chronic Sinusitis.

Chronic sinusitis (CS) is characterized by sinonasal inflammation, mucus overproduction, and edematous mucosal tissue. CS impacts one in seven adults and estimates suggest up to 15% of the general U.S. population may be affected. This research sought to assess a potential role for receptors for advanced glycation end-products (RAGE), an inflammatory receptor expressed in tissues exposed to secondhand smoke (SHS). Human sinus tissue sections were stained for RAGE and S100s, common RAGE ligands. Wild-type mice and mice that over-express RAGE in sinonasal epithelium (RAGE TG) were maintained in room air (RA) or exposed to secondhand smoke (SHS) via a nose-only delivery system five days a week for 6 weeks. Mouse sections were stained for RAGE and tissue lysates were assayed for cleaved caspase 3, cytokines, or matrix metalloproteases. We discovered increased RAGE expression in sinus tissue following SHS exposure and in sinuses from RAGE TG mice in the absence of SHS. Cleaved caspase-3, cytokines (IL-1ß, IL-3, and TNF-α), and MMPs (-9 and -13) were induced by SHS and in tissues from RAGE TG mice. These results expand the inflammatory role of RAGE signaling, a key axis in disease progression observed in smokers. In this relatively unexplored area, enhanced understanding of RAGE signaling during voluntary and involuntary smoking may help to elucidate potential therapeutic targets that may attenuate the progression of smoke-related CS.

Inflammatory Cytokine Elaboration Following Secondhand Smoke (SHS) Exposure Is Mediated in Part by RAGE Signaling.

The receptor for advanced glycation end products (RAGE) is a key contributor to immune and inflammatory responses in myriad diseases. RAGE is a transmembrane pattern recognition receptor with a special interest in pulmonary anomalies due to its naturally abundant pulmonary expression. Our previous studies demonstrated an inflammatory role for RAGE following acute 30-day exposure to secondhand smoke (SHS), wherein immune cell diapedesis and cytokine/chemokine secretion were accentuated in part via RAGE signaling. However, the chronic inflammatory mechanisms associated with RAGE have yet to be fully elucidated. In this study, we address the impact of long-term SHS exposure on RAGE signaling. RAGE knockout (RKO) and wild-type (WT) mice were exposed to SHS using a nose-only delivery system (Scireq Scientific, Montreal, Canada) for six months. SHS-exposed animals were compared to mice exposed to room air (RA) only. Immunoblotting was used to assess the phospho-AKT and phospho-ERK activation data, and colorimetric high-throughput assays were used to measure NF-kB. Ras activation was measured via ELISAs. Bronchoalveolar lavage fluid (BALF) cellularity was quantified, and a mouse cytokine antibody array was used to screen the secreted cytokines. The phospho-AKT level was decreased, while those of phospho-ERK, NF-kB, and Ras were elevated in both groups of SHS-exposed mice, with the RKO + SHS-exposed mice demonstrating significantly decreased levels of each intermediate compared to those of the WT + SHS-exposed mice. The BALF contained increased levels of diverse pro-inflammatory cytokines in the SHS-exposed WT mice, and diminished secretion was detected in the SHS-exposed RKO mice. These results validate the role for RAGE in the mediation of chronic pulmonary inflammatory responses and suggest ERK signaling as a likely pathway that perpetuates RAGE-dependent inflammation. Additional characterization of RAGE-mediated pulmonary responses to prolonged exposure will provide a valuable insight into the cellular mechanisms of lung diseases such as chronic obstructive pulmonary disease.

Yerba Maté (Ilex paraguariensis) Supplement Exerts Beneficial, Tissue-Specific Effects on Mitochondrial Efficiency and Redox Status in Healthy Adult Mice.

Yerba maté, a herbal tea derived from Ilex paraguariensis, has previously been reported to be protective against obesity-related and other cardiometabolic disorders. Using high-resolution respirometry and reverse-phase high-performance liquid chromatography, the effects of four weeks of yerba maté consumption on mitochondrial efficiency and cellular redox status in skeletal muscle, adipose, and liver, tissues highly relevant to whole-body metabolism, were explored in healthy adult mice. Yerba maté treatment increased the mitochondrial oxygen consumption in adipose but not in the other examined tissues. Yerba maté increased the ATP concentration in skeletal muscle and decreased the ATP concentration in adipose. Combined with the observed changes in oxygen consumption, these data yielded a significantly higher ATP:O2, a measure of mitochondrial efficiency, in muscle and a significantly lower ATP:O2 in adipose, which was consistent with yerba maté-induced weight loss. Yerba maté treatment also altered the hepatic glutathione (GSH)/glutathione disulfide (GSSG) redox potential to a more reduced redox state, suggesting the treatment's potential protective effects against oxidative stress and for the preservation of cellular function. Together, these data indicate the beneficial, tissue-specific effects of yerba maté supplementation on mitochondrial bioenergetics and redox states in healthy mice that are protective against obesity.

Decreased Expression of Pulmonary Homeobox NKX2.1 and Surfactant Protein C in Developing Lungs That Over-Express Receptors for Advanced Glycation End-Products (RAGE).

Receptors for advanced glycation end-products (RAGE) are multi-ligand cell surface receptors of the immunoglobin superfamily prominently expressed by lung epithelium. Previous experiments demonstrated that over-expression of RAGE by murine alveolar epithelium throughout embryonic development causes neonatal lethality coincident with significant lung hypoplasia. In the current study, we evaluated the expression of NKX2.1 (also referred to as TTF-1), a homeodomain-containing transcription factor critical for branching morphogenesis, in mice that differentially expressed RAGE. We also contextualized NKX2.1 expression with the abundance of FoxA2, a winged double helix DNA binding protein that influences respiratory epithelial cell differentiation and surfactant protein expression. Conditional RAGE over-expression was induced in mouse lung throughout gestation (embryonic day E0-18.5), as well as during the critical saccular period of development (E15.5-18.5), and analyses were conducted at E18.5. Histology revealed markedly less lung parenchyma beginning in the canalicular stage of lung development and continuing throughout the saccular period. We discovered consistently decreased expression of both NKX2.1 and FoxA2 in lungs from transgenic (TG) mice compared to littermate controls. We also observed diminished surfactant protein C in TG mice, suggesting possible hindered differentiation and/or proliferation of alveolar epithelial cells under the genetic control of these two critical transcription factors. These results demonstrate that RAGE must be specifically regulated during lung formation. Perturbation of epithelial cell differentiation culminating in respiratory distress and perinatal lethality may coincide with elevated RAGE expression in the lung parenchyma.

Altered Epigenetic Profiles in the Placenta of Preeclamptic and Intrauterine Growth Restriction Patients.

Intrauterine growth restriction (IUGR) and preeclampsia (PE) are placental pathologies known to complicate pregnancy and cause neonatal disorders. To date, there is a limited number of studies on the genetic similarity of these conditions. DNA methylation is a heritable epigenetic process that can regulate placental development. Our objective was to identify methylation patterns in placental DNA from normal, PE and IUGR-affected pregnancies. DNA was extracted, and bisulfite was converted, prior to being hybridized for the methylation array. Methylation data were SWAN normalized and differently methylated regions were identified using applications within the USEQ program. UCSC's Genome browser and Stanford's GREAT analysis were used to identify gene promoters. The commonality among affected genes was confirmed by Western blot. We observed nine significantly hypomethylated regions, two being significantly hypomethylated for both PE and IGUR. Western blot confirmed differential protein expression of commonly regulated genes. We conclude that despite the uniqueness of methylation profiles for PE and IUGR, the similarity of some methylation alterations in pathologies could explain the clinical similarities observed with these obstetric complications. These results also provide insight into the genetic similarity between PE and IUGR and suggest possible gene candidates plausibly involved in the onset of both conditions.

Inflammation and Invasion in Oral Squamous Cell Carcinoma Cells Exposed to Electronic Cigarette Vapor Extract.

Electronic cigarettes (eCig) represent a new avenue of tobacco exposure that involves heating oil-based liquids and the delivery of aerosolized flavors with or without nicotine, yet little is known about their overall health impact. The oral cavity is an anatomic gateway for exposure that can be compromised by activating myriad of signaling networks. Oral squamous cell carcinoma (OSSC) is a common malignancy affecting 30,000 people in the United States each year. Our objective was to determine the impact of eCig and nicotine on gingival OSSC invasion and their secretion of pro-inflammatory molecules. Gingiva-derived Ca9-22 cells and tongue-derived Cal27 cells were exposed to eCig vapor extract (EVE) generated from Red Hot or Green Apple (Apple) flavored eCig solution +/- nicotine for 6 hours. Isolation of protein lysates and collection conditioned media was done after treatment. Real-time cellular invasion was assessed using a RTCA DP instrument. Protein expression was determined using western blot. Compared to controls, we observed: elevated NF-kB, TNF-α, ERK, JNK, MMP-13 and cell invasion by Ca9-22 treated with Apple EVE; increased TNF-α and JNK by Ca9-22 treated with Red Hot EVE; and increased TNF-α and JNK by Cal27 cells treated with both Apple and Red Hot EVE. We conclude that eCig flavoring and nicotine orchestrated differential cell invasion and inflammatory effects. This study provides an important initial step in dissecting mechanisms of cancerous invasion and molecular avenues employed by OSCC.

PTPα promotes fibroproliferative responses after acute lung injury.

The acute respiratory distress syndrome (ARDS) is a major healthcare problem, accounting for significant mortality and long-term disability. Approximately 25% of patients with ARDS will develop an overexuberant fibrotic response, termed fibroproliferative ARDS (FP-ARDS) that portends a poor prognosis and increased mortality. The cellular pathological processes that drive FP-ARDS remain incompletely understood. We have previously shown that the transmembrane receptor-type tyrosine phosphatase protein tyrosine phosphatase-α (PTPα) promotes pulmonary fibrosis in preclinical murine models through regulation of transforming growth factor-ß (TGF-ß) signaling. In this study, we examine the role of PTPα in the pathogenesis of FP-ARDS in a preclinical murine model of acid (HCl)-induced acute lung injury. We demonstrate that although mice genetically deficient in PTPα (Ptpra-/-) are susceptible to early HCl-induced lung injury, they exhibit markedly attenuated fibroproliferative responses. In addition, early profibrotic gene expression is reduced in lung tissue after acute lung injury in Ptpra-/- mice, and stimulation of naïve lung fibroblasts with the BAL fluid from these mice results in attenuated fibrotic outcomes compared with wild-type littermate controls. Transcriptomic analyses demonstrate reduced extracellular matrix (ECM) deposition and remodeling in mice genetically deficient in PTPα. Importantly, human lung fibroblasts modified with a CRISPR-targeted deletion of PTPRA exhibit reduced expression of profibrotic genes in response to TGF-ß stimulation, demonstrating the importance of PTPα in human lung fibroblasts. Together, these findings demonstrate that PTPα is a key regulator of fibroproliferative processes following acute lung injury and could serve as a therapeutic target for patients at risk for poor long-term outcomes in ARDS.

RAGE signaling during tobacco smoke-induced lung inflammation and potential therapeutic utility of SAGEs.

BACKGROUND: Smoke exposure culminates as a progressive lung complication involving airway inflammation and remodeling. While primary smoke poses the greatest risk, nearly half of the US population is also at risk due to exposure to secondhand smoke (SHS). METHODS: We used WT, RAGE-/- (KO), and Tet-inducible lung-specific RAGE overexpressing transgenic (TG) mice to study the role of RAGE during short-term responses to SHS. We evaluated SHS effects in mice with and without semi-synthetic glycosaminoglycan ethers (SAGEs), which are anionic, partially lipophilic sulfated polysaccharide derivatives known to inhibit RAGE signaling. TG Mice were weaned and fed doxycycline to induce RAGE at postnatal day (PN) 30. At PN40, mice from each line were exposed to room air (RA) or SHS from three Kentucky 3R4F research cigarettes via a nose-only delivery system (Scireq Scientific, Montreal, Canada) five days a week and i.p. injections of PBS or SAGE (30 mg/kg body weight) occurred three times per week from PN40-70 before mice were sacrificed on PN70. RESULTS: RAGE mRNA and protein expression was elevated following SHS exposure of control and TG mice and not detected in RAGE KO mice. Bronchoalveolar lavage fluid (BALF) analysis revealed RAGE-mediated influence on inflammatory cell diapedesis, total protein, and pro-inflammatory mediators following exposure. Lung histological assessment revealed indistinguishable morphology following exposure, yet parenchymal apoptosis was increased. Inflammatory signaling intermediates such as Ras and NF-κB, as well as downstream responses were influenced by the availability of RAGE, as evidenced by RAGE KO and SAGE treatment. CONCLUSIONS: These data provide fascinating insight suggesting therapeutic potential for the use of RAGE inhibitors in lungs exposed to SHS smoke.

A Role for RAGE in DNA Double Strand Breaks (DSBs) Detected in Pathological Placentas and Trophoblast Cells.

Impaired DNA damage responses are associated with several diseases, including pregnancy complications. Recent research identified an ATM-kinase dependent function for the nuclear isoform of the receptor for advanced glycation end-products (RAGE) during double strand break (DSB)-repair. RAGE contributes to end-resectioning of broken DNA sites by binding with the MRE11-Rad50-Nbs1 (MRN) complex. Placental research is limited regarding the impact of genomic instability and the mechanism for potential repair. We tested the hypothesis regarding the involvement of RAGE during the repair of placental DNA-DSBs. We first identified that the pregnancy complications of PE and preterm labor (PTL) experience loss of genomic integrity and an in vitro trophoblast cell model was used to characterize trophoblast DSBs. Colocalized immunofluorescence of γ-H2AX and RAGE support the potential involvement of RAGE in cellular responses to DNA-DSBs. Immunoblotting for both molecules in PE and PTL placenta samples and in trophoblast cells validated a connection. Co-immunoprecipitation studies revealed interactions between RAGE and pATM and MRE11 during DNA-DSBs. Reduced cellular invasion confirmed the role of genomic instability in trophoblastic function. Collectively, these experiments identified genomic instability in pregnancy complications, the impact of defective DNA on trophoblast function, and a possible RAGE-mediated mechanism during DNA-DSB repair.

Exposure to second-hand cigarette smoke exacerbates the progression of osteoarthritis in a surgical induced murine model.

Osteoarthritis (OA), formerly understood to be a result of passive wear, is now known to be associated with chronic inflammation. Cigarette smoking promotes systemic inflammation and has been implicated in increased joint OA incidence in some studies, though the recent observational data on the association are contradictory. We hypothesize that second-hand smoke (SHS) treatment will increase the incidence of OA in a mouse model that has been subjected to a surgical destabilization of the medial meniscus (DMM). To test this hypothesis, we applied either SHS treatment or room air (RA) to mice for 28 days post-DMM surgery. Histopathology findings indicated that the knees of SHS mice exhibited more severe OA than their control counterparts. Increased expression of matrix metalloprotease-13 (MMP-13), an important extracellular protease known to degrade articular cartilage, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), an intracellular effector of inflammatory pathways, were observed in the SHS group. These findings provide greater understanding and evidence for a detrimental role of cigarette smoke on OA progression and systemic inflammation.

Methylation of cysteinyl leukotriene receptor 1 genes associates with lung function in asthmatics exposed to traffic-related air pollution.

Air pollution is associated with early declines in lung function and increased levels of asthma-related cysteinyl leukotrienes (CysLT) but a biological pathway linking this rapid response has not been delineated. In this randomized controlled diesel exhaust (DE) challenge study of 16 adult asthmatics, increased exposure-attributable urinary leukotriene E4 (uLTE4, a biomarker of cysteinyl leukotriene production) was correlated (p = 0.04) with declines in forced expiratory volume in 1-second (FEV1) within 6 hours of exposure. Exposure-attributable uLTE4 increases were correlated (p = 0.02) with increased CysLT receptor 1 (CysLTR1) methylation in peripheral blood mononuclear cells which, in turn, was marginally correlated (p = 0.06) with decreased CysLTR1 expression. Decreased CysLTR1 expression was, in turn, correlated (p = 0.0007) with FEV1 declines. During the same time period, increased methylation of GPR17 (a negative regulator of CysLTR1) was observed after DE exposure (p = 0.02); this methylation increase was correlated (p = 0.001) with decreased CysLTR1 methylation which, in turn, was marginally correlated (p = 0.06) with increased CysLTR1 expression; increased CysLTR1 expression was correlated (p = 0.0007) with FEV1 increases. Collectively, these data delineate a potential mechanistic pathway linking increased DE exposure-attributable CysLT levels to lung function declines through changes in CysLTR1-related methylation and gene expression.

Regulation of trophoblast cell invasion by Pyruvate Kinase isozyme M2 (PKM2).

The Pyruvate kinase isozymes M2 (PKM2) protein is a metabolic enzyme that regulates the final step of glycolysis. This enzyme is present in highly proliferating cells and is expressed in the placenta. We recently demonstrated upregulated placental PKM2 during human intrauterine growth restriction (IUGR). Our current objective was to determine PKM2 regulation of trophoblast invasion, trophoblast PKM2 localization as well as mTOR protein expression, and to determine effects of activation of PKM2 during IUGR. Human placental tissues were obtained and analyzed by immunohistochemistry and western blot. Trophoblast cells were cultured in normoxic and hypoxic conditions and real time cell invasion and PKM2 protein were determined during activation (Fructose-6-bisphosphate; FBP6) or inhibition (Shikonin) of PKM2. In vivo studies determined the effects of PKM2 activation on placental and fetal weights. IUGR samples had elevated levels of p-PKM2. Different trophoblast PKM2 localization and expression was observed during normoxia and hypoxia. Decreased trophoblast invasion and PKM2 expression was observed during mTOR inhibition. Protection from decreased placental and fetal weights was observed by PKM2 activation. We conclude that PKM2 regulates trophoblast cell invasion depending on its subcellular location. Our results suggest that PKM2 regulation in trophoblast cells is more directly affected during hypoxia and its expression is regulated by mTOR activity. Additionally, we conclude that activation of PKM2 could reverse and/or rescue the deceased placental and fetal weights observed during IUGR. These results suggest that PKM2 could be a mediator of trophoblast cell invasion and its abundance influences the development of complicated pregnancies like IUGR.

Cell invasion, RAGE expression, and inflammation in oral squamous cell carcinoma (OSCC) cells exposed to e-cigarette flavoring.

OBJECTIVE: Electronic cigarettes have given rise to a new, largely unregulated market within the smoking industry. While generally supposed to be less harmful than traditional tobacco smoke, awareness of the biological effects of electronic cigarette liquid is still scarce. Our objective was to determine the impact of electronic cigarette flavoring and nicotine on gingival squamous cell carcinoma invasion, RAGE expression, and the elaboration of pro-inflammatory molecules. METHODS AND MATERIALS: Gingival and tongue squamous cell carcinoma cells were exposed to Red Hot or Green Apple flavored electronic cigarette flavoring with or without nicotine. Immunofluorescence determined RAGE expression. Real-time cellular invasion was assessed using a RTCA DP instrument. Culture medium was assayed for cytokine secretion. RESULTS: Compared to controls we observed: increased cell invasion in gingival cells with Red Hot electronic cigarette flavoring and decreased cell invasion with Green Apple; decreased cell invasion in tongue cells treated with Red Hot electronic cigarette flavoring and no differences in invasion with Green Apple; flavor and nicotine dependent increases in RAGE expression; and differential expression of IL-1α, IL-8, and MMP-13. CONCLUSION: We conclude that electronic cigarette flavoring and nicotine orchestrate differential regulation of oral squamous cell carcinoma (OSCC) cell invasion and inflammatory effects. This study provides an important initial step in dissecting RAGE-mediated mechanisms of cancerous invasion and molecular avenues employed by OSCC.

Protein tyrosine phosphatase-α amplifies transforming growth factor-ß-dependent profibrotic signaling in lung fibroblasts.

Idiopathic pulmonary fibrosis (IPF) is a progressive, often fatal, fibrosing lung disease for which treatment remains suboptimal. Fibrogenic cytokines, including transforming growth factor-ß (TGF-ß), are central to its pathogenesis. Protein tyrosine phosphatase-α (PTPα) has emerged as a key regulator of fibrogenic signaling in fibroblasts. We have reported that mice globally deficient in PTPα (Ptpra-/-) were protected from experimental pulmonary fibrosis, in part via alterations in TGF-ß signaling. The goal of this study was to determine the lung cell types and mechanisms by which PTPα controls fibrogenic pathways and whether these pathways are relevant to human disease. Immunohistochemical analysis of lungs from patients with IPF revealed that PTPα was highly expressed by mesenchymal cells in fibroblastic foci and by airway and alveolar epithelial cells. To determine whether PTPα promotes profibrotic signaling pathways in lung fibroblasts and/or epithelial cells, we generated mice with conditional (floxed) Ptpra alleles (Ptpraf/f). These mice were crossed with Dermo1-Cre or with Sftpc-CreERT2 mice to delete Ptpra in mesenchymal cells and alveolar type II cells, respectively. Dermo1-Cre/Ptpraf/f mice were protected from bleomycin-induced pulmonary fibrosis, whereas Sftpc-CreERT2/Ptpraf/f mice developed pulmonary fibrosis equivalent to controls. Both canonical and noncanonical TGF-ß signaling and downstream TGF-ß-induced fibrogenic responses were attenuated in isolated Ptpra-/- compared with wild-type fibroblasts. Furthermore, TGF-ß-induced tyrosine phosphorylation of TGF-ß type II receptor and of PTPα were attenuated in Ptpra-/- compared with wild-type fibroblasts. The phenotype of cells genetically deficient in PTPα was recapitulated with the use of a Src inhibitor. These findings suggest that PTPα amplifies profibrotic TGF-ß-dependent pathway signaling in lung fibroblasts.

Growth arrest-specific protein-6/AXL signaling induces preeclampsia in rats†.

Preeclampsia (PE) is a complicated obstetric complication characterized by increased blood pressure, decreased trophoblast invasion, and inflammation. The growth arrest-specific 6 (Gas6) protein is known to induce dynamic cellular responses and is elevated in PE. Gas6 binds to the AXL tyrosine kinase receptor and AXL-mediated signaling is implicated in proliferation and migration observed in several tissues. Our laboratory utilized Gas6 to induce preeclamptic-like conditions in pregnant rats. Our objective was to determine the role of Gas6/AXL signaling as a possible model of PE. Briefly, pregnant rats were divided into three groups that received daily intraperitoneal injections (from gestational day 7.5 to 17.5) of phosphate buffered saline (PBS), Gas6, or Gas6 + R428 (an AXL inhibitor administered from gestational day 13.5 to 17.5). Animals dispensed Gas6 experienced elevated blood pressure, increased proteinuria, augmented caspase-3-mediated placental apoptosis, and diminished trophoblast invasion. Gas6 also enhanced expression of several PE-related genes and a number of inflammatory mediators. Gas6 further enhanced placental oxidative stress and impaired mitochondrial respiration. Each of these PE-related characteristics was ameliorated in dams and/or their placentae when AXL inhibition by R428 occurred in tandem with Gas6 treatment. We conclude that Gas6 signaling is capable of inducing PE and that inhibition of AXL prevents disease progression in pregnant rats. These results provide insight into pathways associated with PE that could be useful in the clarification of potential therapeutic approaches.

RAGE and AXL expression following secondhand smoke (SHS) exposure in mice.

Aim and Purpose: Tobacco exposure is one of the top three global health risks leading to the development of chronic obstructive pulmonary disease (COPD). Although there is extensive research into the effects of cigarette smoke, the effect of secondhand smoke (SHS) in the lung remains limited. SHS induces receptors for advanced glycation end-products (RAGE) and an inflammatory response that leads to COPD characteristics. Semi-synthetic glycosaminoglycan ethers (SAGEs) are sulfated polysaccharides derived from hyaluronic acid that inhibit RAGE signaling. The growth arrest-specific 6 (Gas6) protein is known to induce dynamic cellular responses and is correlated with cell function. Gas6 binds to the AXL tyrosine kinase receptor and AXL-mediated signaling is implicated in proliferation and inflammation. This project's purpose was to study the correlation between RAGE, AXL, and Gas6 during SHS exposure in the lung. Methods: C57Bl/6 mice were exposed to SHS alone or SHS + SAGEs for 4 weeks and compared to control animals exposed to room air (RA). Results: Compared to controls we observed: 1) increased RAGE mRNA and protein expression in SHS-exposed lungs which was decreased by SAGEs; 2) decreased expression of total AXL, but highly elevated pAXL expression following exposure; 3) highly elevated Gas6 expression when RAGE was targeted by SAGEs during SHS exposure; 4) SHS-mediated BALF cellularity and inflammatory molecule elaboration; and 5) the induction of both RAGE and AXL by Gas6 in cell culture models. Conclusions: Our results suggest that there is a possible correlation between RAGE and AXL during SHS exposure. Additional research is critically needed that dissects the molecular interplay between these two important signaling cascades. At this point, the current studies provide insight into tobacco-mediated effects in the lung and clarify possible avenues for alleviating complications that could arise during SHS exposure such as those observed during COPD exacerbations.