The effect of smoking cessation and steroid treatment on emphysema in guinea pigs

Therapeutic effects of soluble guanylate cyclase stimulation on pulmonary hemodynamics and emphysema development in guinea pigs chronically exposed to cigarette smoke

We have analyzed the effect of the soluble guanylate cyclase (sGC) stimulator BAY 41-2272 in a therapeutic intervention in guinea pigs chronically exposed to cigarette smoke (CS). The effects of sGC stimulation on respiratory function, pulmonary hemodynamics, airspace size, vessel remodeling, and inflammatory cell recruitment to the lungs were evaluated in animals that had been exposed to CS for 3 mo. CS exposure was continued for an additional 3 mo in half of the animals and withdrawn in the other half. Animals that stopped CS exposure had slightly lower pulmonary artery pressure (PAP) and right ventricle (RV) hypertrophy than those who continued CS exposure, but they did not recover from the emphysema and the inflammatory cell infiltrate. Conversely, oral BAY 41-2272 administration stopped progression or even reversed the CS-induced emphysema in both current and former smokers, respectively. Furthermore, BAY 41-2272 produced a reduction in the RV hypertrophy, which correlated with a decrease in the PAP values. By contrast, the degree of vessel remodeling induced by CS remained unchanged in the treated animals. Functional network analysis suggested perforin/granzyme pathway downregulation as an action mechanism capable of stopping the progression of emphysema after sGC stimulation. The pathway analysis also showed normalization of the expression of cGMP-dependent serine/kinases. In conclusion, in guinea pigs chronically exposed to CS, sGC stimulation exerts beneficial effects on the lung parenchyma and the pulmonary vasculature, suggesting that sGC stimulators might be a potential alternative for chronic obstructive pulmonary disease treatment that deserves further evaluation.

Effects of Tobacco Usage and Antiretroviral Therapy on Biomarkers of Systemic Immune Activation in HIV-Infected Participants

Like HIV infection, smoking, which is common among HIV-infected persons, is associated with chronic, systemic inflammation. However, the possible augmentative effects of HIV infection and smoking and other types of tobacco usage on indices of systemic inflammation and the impact of combination antiretroviral therapy (cART) thereon remain largely unexplored and represent the focus of the current study. Of the total number of HIV-infected persons recruited to the study (n = 199), 100 were categorised as pre-cART and 99 as virally suppressed (HIV viral load < 40 copies/mL). According to serum cotinine levels, 144 and 55 participants were categorised as nonusers and users of tobacco, respectively. In addition to cytokines (IL-6, IL-8, and TNF-α) and chemokines (IP-10, MIG, IL-8, MCP-1, and RANTES), other biomarkers of systemic inflammation included C-reactive protein (CRP), β2-microglobulin, and those of neutrophil activation [ICAM-1, L-selectin, matrix metalloproteinase-9 (MMP-9)], microbial translocation (soluble CD14, LPS-binding protein), and oxidative stress (cyclophilin A, surfactant D). These were measured using multiplex bead array, ELISA, and immunonephelometric procedures. Viral suppression was associated with significant decreases in the levels of most of the biomarkers tested (P < 0.0037-0.0008), with the exceptions of CRP, cyclophilin A, and MMP-9. With respect to tobacco usage, irrespective of cART status, circulating levels of β2-microglobulin, cyclophilin A, and RANTES were significantly elevated (P < 0.042-0.012) in users vs nonusers. Additional analysis of the groups of tobacco users and nonusers according to cART status revealed high levels of RANTES in pre-cART/tobacco users relative to the three other subgroups (P < 0.004-0.0001), while more modest increases in cyclophilin A and MMP-9 (P < 0.019-0.027) were observed in comparison with the cART/tobacco user subgroup. Notwithstanding the efficacy of cART in attenuating HIV-associated, chronic systemic inflammation, the current study has identified RANTES as being significantly and seemingly selectively increased in those with active HIV infection who use tobacco, a mechanism which may underpin augmentative proinflammatory activity.

Protein Carbonylation in Human Smokers and Mammalian Models of Exposure to Cigarette Smoke: Focus on Redox Proteomic Studies

SIGNIFICANCE

Oxidative stress is one mechanism whereby tobacco smoking affects human health, as reflected by increased levels of several biomarkers of oxidative stress/damage isolated from tissues and biological fluids of active and passive smokers. Many investigations of cigarette smoke (CS)-induced oxidative stress/damage have been carried out in mammalian animal and cellular models of exposure to CS. Animal models allow the investigation of many parameters that are similar to those measured in human smokers. In vitro cell models may provide new information on molecular and functional differences between cells of smokers and nonsmokers. Recent Advances: Over the past decade or so, a growing number of researches highlighted that CS induces protein carbonylation in different tissues and body fluids of smokers as well as in in vivo and in vitro models of exposure to CS.

CRITICAL ISSUES

We review recent findings on protein carbonylation in smokers and models thereof, focusing on redox proteomic studies. We also discuss the relevance and limitations of these models of exposure to CS and critically assess the congruence between the smoker's condition and laboratory models.

FUTURE DIRECTIONS

The identification of protein targets is crucial for understanding the mechanism(s) by which carbonylated proteins accumulate and potentially affect cellular functions. Recent progress in redox proteomics allows the enrichment, identification, and characterization of specific oxidative protein modifications, including carbonylation. Therefore, redox proteomics can be a powerful tool to gain new insights into the onset and/or progression of CS-related diseases and to develop strategies to prevent and/or treat them. Antioxid. Redox Signal. 26, 406-426.

Modification of the rat airway explant transcriptome by cigarette smoke

Although a number of animal model studies have addressed changes in gene expression in the parenchyma and their relationship to emphysema, much less is known about the pathogenesis of cigarette smoke-induced small airway remodeling. In this study the authors exposed rat tracheal explants, a model of the airway wall, to whole smoke for 15 min, and then cultured the explants in air. The airway transcriptome was evaluated using RAE 230_2 gene chips. By 2 h after starting smoke exposure, expression levels of 502 genes were differentially expressed by more than 1.5 times (p < .01 or less) and by 24 h 1870 genes were significantly changed up or down. These included genes involved in antioxidant protection, epithelial defense and remodeling, inflammatory mediators and transcription factors, and a number of unexpected genes, including the matrix metalloproteinase (MMP)-12 inducer, tachykinin-1 (substance P). Pretreatment of the explants with 1 x 10(-7) M dexamethasone reduced the number of significantly changed genes by approximately 47% at 2 h and 68% at 24 h and in almost all instances reduced the magnitude of the smoke-induced changes. The authors conclude that even a very brief exposure to cigarette smoke can lead to rapid changes in the expression of a large number of genes in rat tracheal explants, and that these effects are directly mediated by smoke, without a need for exogenous inflammatory cells. Steroids, contrary to the usual belief, are able to ameliorate many of these changes, at least in this very acute model.