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.

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.

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.

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.