Kinetics of adipose tissue microdialysis-derived metabolites in critically ill septic patients: associations with sepsis severity and clinical outcome

Microdialysis (MD) provides the opportunity to monitor tissue metabolic changes. This study aimed to describe the kinetics of MD-derived metabolites during the course of critical sepsis, to assess whether these metabolites are useful in grading sepsis severity, and to investigate their prognostic use. To this end, 54 mechanically ventilated septic patients were prospectively studied, out of which 39 had shock. Upon sepsis onset, an MD catheter was inserted into the subcutaneous adipose tissue of the upper thigh. Dialysate samples were analyzed for glucose, pyruvate, lactate, and glycerol. Sampling was performed six times per day for a maximum of 6 days. The daily mean values of MD measurements were calculated for each patient. Arterial blood was analyzed for glucose, lactate, and glycerol concomitantly with dialysate sampling. Blood glucose and tissue glucose levels along with lactate levels were high during the entire study period. Tissue pyruvate and glycerol were also raised, whereas the lactate-pyruvate ratio was preserved. At study entry, patients with septic shock had higher tissue lactate (3.3 vs. 1.9 mmol/L, P = 0.01) and glycerol (340 vs. 169 μmol/L, P = 0.04) levels compared with those without shock. Nonsurvivors had higher tissue lactate (P = 0.008), glycerol (P = 0.004), and pyruvate (P = 0.002) levels than survivors during the whole observation period. Logistic regression analysis showed that age (odds ratio [OR], 1.075; 95% confidence interval [CI], 1.004-1.150; P = 0.03), Sequential Organ Failure Assessment score on day 1 (OR, 1.550; 95% CI, 1.043-2.312; P = 0.03), and tissue glycerol on day 1 (OR, 1.007; 95% CI, 1.001-1.012; P = 0.01) predicted mortality independently. In conclusion, critical sepsis is characterized by high tissue lactate and pyruvate levels and a preserved lactate-pyruvate ratio, suggesting a nonischemic mechanism for raised blood lactate levels. Septic shock is associated with higher tissue lactate and glycerol levels compared with sepsis without shock. Elevated tissue lactate, pyruvate, and glycerol levels are related to poor clinical outcome, with the latter constituting an independent predictor.     

Inflammatory and non-invasive vascular markers: the multimarker approach for risk stratification in coronary artery disease

Current thinking supports the notion that several inflammatory proteins intervene with endothelium and haemostatic factors leading to plaque formation and rupture. Of these, C-reactive protein (CRP), monocyte/macrophage colony-stimulating factor (MCSF) and interleukin-6 (IL-6) promote atherogenesis by inducing monocyte-macrophage activation, foam cell formation, platelet activation, tissue factor expression, release of other procoagulant cytokines or downregulation of atheroprotective cytokines such as interleukin 10 and transforming growth factor b-1 (TGFb-1). CRP, MSCF and IL-6 are interrelated and have been found in increased blood concentrations in CAD. Increased levels of CRP and IL-6 predict a higher cardiovascular event rate in the general population and in addition to high MCSF or low TGFb-1 predict adverse outcome in CAD patients independently of traditional risk factors. Moreover, in CAD patients, the predictive value of MCSF is additive and beyond that of CRP suggesting the need of a “multimarker approach” in assessing cardiovascular risk. Accumulating evidence supports the utility of non-invasive markers of subclinical atherosclerosis, namely carotid intimal media thickness, flow mediated dilatation of the brachial artery, augmentation index or pulse wave velocity, in the prediction of cardiovascular risk particularly in primary prevention settings. The combination of these non-invasive tests has been shown to improve their prognostic accuracy compared to each other alone. Although several therapeutic strategies like vaccination against antigens promoting atherogenesis, cyclooxygenase inhibitors, statins, and ACE inhibitors may reduce the levels of these inflammatory markers and improve the non-invasive markers of subclinical atherosclerosis, the impact on cardiovascular risk resulting from these changes is unknown. The combination of an established inflammatory marker such as CRP or a vascular marker such as IMT with novel biochemical and vascular markers of cardiovascular disease may offer additive prognostic information for adverse outcome.     

Association of soluble apoptotic markers with impaired left ventricular deformation in patients with rheumatoid arthritis. Effects of inhibition of interleukin-1 activity by anakinra

Myocardial function is impaired in rheumatoid arthritis (RA). Inhibition of interleukin (IL)-1 activity reduces experimental myocardial infarction by limiting apoptosis. We investigated whether a) soluble apoptotic markers are related with impaired left ventricular (LV) performance and b) treatment with anakinra, an IL-1 receptor antagonist, reduces apoptotic markers leading to improved LV performance in RA. We studied 46 RA patients. In an acute, double-blind cross-over trial, 23 patients were randomised to a single injection of anakinra or placebo and after 48 hours (h) to the alternative treatment. In a chronic trial, 23 patients who received anakinra for 30 days were compared with 23 patients who received prednisolone. At baseline, 3 h and 30 days after treatment, we measured circulating IL-1β, tumour necrosis factor (TNF)-α, Fas, Fas-ligand and caspase-9 to assess apoptosis. At baseline and 30 days after treatment, we assessed LV longitudinal strain, strain rate and E/Em ratio using 2D-speckle tracking and tissue Doppler echocardiography. At baseline, increased apoptotic markers were related with reduced LongSRS and increased E/Em (p<0.05). After 3 h and 30 days of anakinra, there was a reduction in Fas (median 481 vs. 364 vs. 301 pg/ml), Fas-ligand (median 289 vs. 221 vs. 190 pg/ml), caspase-9 (median 1.90 vs. 1.40 vs. 1.07 ng/ml), TNF-α and IL-1β (p<0.05 for all comparisons). E/Em, LongS and LongSRS were improved after anakinra (p<0.01) and their percent changes were related with the corresponding changes of Fas and caspase-9 (p<0.05). No changes of the examined parameters were observed after prednisolone. In conclusion, inhibition of IL-1 activity by anakinra reduces apoptotic markers leading to improved LV performance in RA.