The effects of dexamethasone and oxygen in ventilated adult sheep with early phase acute respiratory distress syndrome.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a life-threating condition with high morbidity and mortality. Inflammation is the main factor in the pathogenesis of ARDS. Therefore systemic corticosteroids are a rational therapeutic approach, but the effect of corticosteroids is still unclear. In this study, we looked at the effects of corticosteroids in ventilated sheep with ARDS, induced by lung lavage. METHODS: We performed a prospective, randomised study in 64 ventilated sheep with ARDS, to evaluate the effect of corticosteroids and oxygen concentration on gas exchange and lung injury. Oxygenation index (OI) and ventilation efficacy index (VEI) were calculated to evaluate gas exchange. Lung injury was assessed by inflammatory response in broncho-alveolar lavage fluid (BALF) and plasma and histology of the lung. RESULTS: OI, VEI, lung inflammation, surfactant production, or lung histology was not influenced by corticosteroids. In the 100 % oxygen groups, OI was higher and total number of cells and disaturated phospholipids were lower in BALF. CONCLUSION: Our study showed that corticosteroids did not influence inflammation in early phase ARDS and that hyperoxia aggravated lung injury which could not be modulated by dexamethasone in early phase ARDS.

Plasma advanced glycation end-products and skin autofluorescence are increased in COPD.

Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation and oxidative stress. These conditions may lead to the formation of advanced glycation end-products (AGEs). In this study we investigated in 88 COPD patients and 55 control subjects (80% ex-smokers) the association of the plasma protein-bound AGEs N(ε)-(carboxymethyl)lysine (CML), pentosidine, N(ε)-(carboxyethyl)lysine (CEL), and AGE accumulation in skin by skin autofluorescence (AFR), with lung function. Mean ± sd plasma CML was decreased (COPD 61.6 ± 15.6 nmol · mmol(-1) lysine, never-smokers 80.7 ± 19.8 nmol · mmol(-1) lysine and ex-smokers 82.9 ± 19.3 nmol · mmol(-1) lysine) and CEL (COPD 39.1 ± 10.9 nmol · mmol(-1) lysine, never-smokers 30.4 ± 5.0 nmol · mmol(-1) lysine and ex-smokers 27.7 ± 6.4 nmol · mmol(-1) lysine) and AFR (COPD 3.33 ± 0.67 arbitrary units (AU), never-smokers 2.24 ± 0.45 AU and ex-smokers 2.31 ± 0.47 AU) were increased in COPD patients compared to controls. Disease state was inversely associated with CML, and linearly associated with CEL and AFR. Performing regression analyses in the total group, CEL and AFR showed a negative association and CML a positive association with lung function, even after correction for potential confounders. In conclusion, CEL and AFR were negatively and CML was positively associated with disease state. In the total group only the AGEs showed an association with forced expiratory volume in 1 s. Our data suggest that AGEs are involved in the pathophysiology of COPD, although their exact role remains to be determined.

Association of plasma sRAGE, but not esRAGE with lung function impairment in COPD.

RATIONALE: Plasma soluble Receptor for Advanced Glycation End Product (sRAGE) is considered as a biomarker in COPD. The contribution of endogenous sRAGE (esRAGE) to the pool of plasma sRAGE and the implication of both markers in COPD pathogenesis is however not clear yet. The aim of the current study was therefore to measure plasma levels of esRAGE comparative to total sRAGE in patients with COPD and a control group. Further, we established the relations of esRAGE and total sRAGE with disease specific characteristics such as lung function and DLCO, and with different circulating AGEs. METHODS: Plasma levels of esRAGE and sRAGE were measured in an 88 patients with COPD and in 55 healthy controls. FEV1 (%predicted) and FEV1/VC (%) were measured in both groups; DLCO (%predicted) was measured in patients only. In this study population we previously reported that the AGE Nϵ-(carboxymethyl) lysine (CML) was decreased, Nϵ-(carboxyethyl) lysine (CEL) increased and pentosidine was not different in plasma of COPD patients compared to controls. RESULTS: Plasma esRAGE (COPD: 533.9 ± 412.4, CONTROLS: 848.7 ± 690.3 pg/ml; p = 0.000) was decreased in COPD compared to controls. No significant correlations were observed between plasma esRAGE levels and lung function parameters or plasma AGEs. A positive correlation was present between esRAGE and total sRAGE levels in the circulation. Confirming previous findings, total sRAGE (COPD: 512.6 ± 403.8, CONTROLS: 1834 ± 804.2 pg/ml; p < 0.001) was lower in patients compared to controls and was positively correlated FEV1 (r = 0.235, p = 0.032), FEV1/VC (r = 0.218, p = 0.047), and DLCO (r = 0.308, p = 0.006). sRAGE furthermore did show a significant positive association with CML (r = 0.321, p = 0.003). CONCLUSION: Although plasma esRAGE is decreased in COPD patients compared to controls, only total sRAGE showed a significant and independent association with FEV1, FEV1/VC and DLCO, indicating that total sRAGE but not esRAGE may serve as marker of COPD disease state and severity.

Decreased plasma sRAGE levels in COPD: influence of oxygen therapy.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation and oxidative stress. N(ε) -(carboxymethyl) lysine (CML), an advanced glycation end product (AGE) and the soluble decoy receptor, sRAGE, are exciting new molecules linked to oxidative stress and inflammation. Here the levels of plasma sRAGE and CML were determined and their variation in relation to lung function, external long-term oxygen therapy (LTOT) and plasma levels of inflammatory molecules in COPD evaluated. METHODS: Plasma sRAGE and CML levels were measured by ELISA in 146 patients with stable COPD and 81 healthy subjects, subgrouped from a larger case-control study and matched for age, gender and pack-years smoked. RESULTS: Decreased levels of plasma sRAGE and no significant difference in levels of plasma CML were found in patients with COPD in comparison with controls. In the total group, plasma sRAGE was positively associated with FEV(1) and forced vital capacity and negatively with pack-years smoked. In patients receiving LTOT, levels of plasma sRAGE were lower compared with those without LTOT. Only in controls, a weak correlation was found between plasma sRAGE and CML. sRAGE did not correlate with measured inflammatory markers, whereas CML was negatively correlated with fibrinogen. CONCLUSION: Plasma sRAGE levels are lower in patients with COPD compared with healthy control subjects, and even lower levels in patients receiving LTOT. Because sRAGE correlated with lung function only in the whole group, sRAGE can be considered a marker of COPD, but not of disease severity. A lack of clear association between sRAGE, CML and systemic inflammation is furthermore evident.

Advanced glycation end products and their receptor in age-related, non-communicable chronic inflammatory diseases; Overview of clinical evidence and potential contributions to disease.

Age-related, non-communicable chronic inflammatory diseases represent the major 21st century health problem. Especially in Western countries, the prevalence of non-communicable diseases like chronic obstructive pulmonary disease, cardiovascular disease, type 2 diabetes and osteoporosis are exponentially rising as the population ages. These diseases are determined by common risk factors and share an age-related onset. The affected organs display evidence of accelerated ageing, and are hallmarked by chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) has been implicated in a number of inflammatory diseases and plays a central role in amplifying inflammatory responses. Advanced glycation end product (AGE) formation and accumulation is accelerated under these conditions. Advanced glycation end products are not only linked to RAGE signaling and inflammation, but to various hallmarks of the ageing process. In addition to these biological functions, circulating levels of the soluble form of RAGE and of advanced glycation end products are candidate biomarkers for many age-related inflammatory diseases. The purpose of this review is to provide an overview of the mechanistic connections between RAGE and advanced glycation end products and the processes of inflammation and ageing. Furthermore, through the presented overview of AGE-RAGE alterations that have been described in clinical studies in chronic obstructive pulmonary disease, cardiovascular disease, type 2 diabetes and osteoporosis, and insight obtained from mechanistic in vitro and animal studies, it can be concluded that these AGE-RAGE disturbances are a common contributing factor to the inflammatory state and pathogenesis of these various conditions.

Various Mechanistic Pathways Representing the Aging Process Are Altered in COPD.

BACKGROUND: Accelerated aging has been proposed as a pathologic mechanism of various chronic diseases, including COPD. This concept has almost exclusively been approached by analyses of individual markers. We investigated whether COPD is associated with accelerated aging using a panel of markers representing various interconnected aspects of the aging process. METHODS: Lung function, leukocyte telomere length, lymphocyte gene expression of anti-aging (sirtuin 1, total klotho, and soluble klotho [Sklotho]), senescence (p16/21), and DNA repair (Ku70/80 and TERF2) proteins, and markers of systemic inflammation and oxidative stress were determined in 160 patients with COPD, 82 smoking subjects, and 38 never-smoking control subjects. RESULTS: Median levels for telomere length, Sklotho, Ku70, and sirtuin 1 gene expression were lower (respectively, 4.4, 4.6, and 4.7 kbp for telomere length; 74%, 82%, and 100% for Sklotho; 88%, 92%, and 100% for Ku70 and 70%, 92%, and 100% for sirtuin 1, all P < .05) in patients compared with the smoking and never-smoking control groups. P21 gene expression was higher in patients compared with smoking control subjects. Telomere length correlated with Ku70 gene expression (r = 0.15, P = .02). After correction for age, smoking history, systemic inflammation, and oxidative stress, telomere length and p21 were the only markers that remained independently associated with lung function. In separate groups, only telomere length remained associated with lung function parameters. CONCLUSIONS: Markers of the aging mechanism represent distinct molecular aspects of aging. Among them, different markers were altered in COPD, but only telomere length was consistently associated with lung function, and seems a useful marker for expressing accelerated aging in COPD.