In Silico Simulation of Corticosteroids Effect on an NFkB- Dependent Physicochemical Model of Systemic Inflammation

During the onset of an inflammatory response signaling pathways are activated for "translating" extracellular signals into intracellular responses converging to the activation of nuclear factor (NF)-kB, a central transcription factor in driving the inflammatory response. An inadequate control of its transcriptional activity is associated with the culmination of a hyper-inflammatory response making it a desired therapeutic target. Predicated upon the nature of the response, a systems level analysis might provide rational leads for the development of strategies that promote the resolution of the response.A physicochemical host response model is proposed to integrate biological information in the form of kinetic rules and signaling cascades with pharmacokinetic models of drug action for the modulation of the response. The unifying hypothesis is that the response is triggered by the activation of the NFkB signaling module and corticosteroids serve as a template for assessing anti-inflammatory strategies. The proposed in silico model is evaluated through its ability to predict and modulate uncontrolled responses. The pre-exposure of the system to hypercortisolemia, i.e. 6 hr before or simultaneously with the infectious challenge "reprograms" the dynamics of the host towards a balanced inflammatory response. However, if such an intervention occurs long before the inflammatory insult a symptomatic effect is observed instead of a protective relief while a steroid infusion after inducing inflammation requires much higher drug doses.We propose a reversed engineered inflammation model that seeks to describe how the system responds to a multitude of external signals. Timing of intervention and dosage regimes appears to be key determinants for the protective or symptomatic effect of exogenous corticosteroids. Such results lie in qualitative agreement with in vivo human studies exposed both to LPS and corticosteroids under various time intervals thus improving our understanding of how interacting modules generate a behavior

Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Effects of Methylprednisolone on Intracellular Bacterial Growth

Clinical studies have shown positive associations among sustained and intense inflammatory responses and the incidence of bacterial infections. Patients presenting with acute respiratory distress syndrome (ARDS) and high levels of proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), and IL-6, have increased risk for developing nosocomial infections attributable to organisms such as Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter spp., compared to those patients with lower levels. Our previous in vitro studies have demonstrated that these bacterial strains exhibit enhanced growth extracellularly when supplemented with high concentrations of pure recombinant TNF-α, IL-1β, or IL-6. In addition, we have shown that the intracellular milieu of phagocytic cells that are exposed to supraoptimal concentrations of TNF-α, IL-1β, and IL-6 or lipopolysaccharide (LPS) favors survival and replication of ingested bacteria. Therefore, we hypothesized that under conditions of intense inflammation the host's micromilieu favors bacterial infections by exposing phagocytic cells to protracted high levels of inflammatory cytokines. Our clinical studies have shown that methylprednisolone is capable of reducing the levels of TNF-α, IL-1β, and IL-6 in ARDS patients. Hence, we designed a series of in vitro experiments to test whether human monocytic cells (U937 cells) that are activated with high concentrations of LPS, which upregulate the release of proinflammatory cytokines from these phagocytic cells, would effectively kill or restrict bacterial survival and replication after exposure to methylprednisolone. Fresh isolates of S. aureus, P. aeruginosa, and Acinetobacter were used in our studies. Our results indicate that, compared with the control, stimulation of U937 cells with 100-ng/ml, 1.0-μg/ml, 5.0-μg/ml, or 10.0-μg/ml concentrations of LPS enhanced the intracellular survival and replication of all three species of bacteria significantly (for all, P = 0.0001). Stimulation with ≤10.0 ng of LPS generally resulted in efficient killing of the ingested bacteria. Interestingly, when exposed to graded concentrations of methylprednisolone, U937 cells that had been stimulated with 10.0 μg of LPS were able to suppress bacterial replication efficiently in a concentration-dependent manner. Significant reduction in numbers of CFU was observed at ≥150 μg of methylprednisolone per ml (P values were 0.032, 0.008, and 0.009 for S. aureus, P. aeruginosa, and Acinetobacter, respectively). We have also shown that steady-state mRNA levels of TNF-α, IL-1β, and IL-6 in LPS-activated cells were reduced by treatment of such cells with methylprednisolone, in a concentration-dependent manner. The effective dose of methylprednisolone was 175 mg, a value that appeared to be independent of priming level of LPS and type of mRNA. We therefore postulate that a U-shaped relationship exists between the level of expression of TNF-α, IL-1β, and IL-6 within the phagocytic cells and their abilities to suppress active survival and replication of phagocytized bacteria

Glucocorticoid treatment in community-acquired pneumonia without severe sepsis: No evidence of efficacy

The study by Snijders and colleagues finds no evidence of efficacy for prolonged glucocorticoid treatment in hospitalized CAP patients without severe sepsis. We believe that, at present, there is no evidence to support the use of glucocorticoids in such patients. An exception, however, would apply to patients with documented adrenal insufficiency. Although Snijders and colleagues found no benefit of glucocorticoids in the smaller subgroup of patients with respiratory failure, lack of information about baseline characteristics and adequacy of antibiotic treatment makes it difficult to effectively appraise these data. Two recent meta-analyses have extensively reviewed the literature on prolonged glucocorticoid treatment in patients with severe sepsis (n = 1,228) and acute lung injury\u2013acute respiratory distress syndrome (n = 648) frequently caused by severe pneumonia. We believe that the findings of this study do not change the conclusions of recent consensus guidelines for patients admitted to the ICU with severe CAP with either shock or acute lung injury

Nuclear factor-κB- and glucocorticoid receptor α-mediated mechanisms in the regulation of systemic and pulmonary inflammation during sepsis and acute respiratory distress syndrome: Evidence for inflammation-induced target tissue resistance to glucocorticoids

To test the hypothesis that the interaction between nuclear factor-κB (NF-κB) and glucocorticoid receptor α (GRα) is a key pathogenetic mechanism regulating the progression of systemic and pulmonary inflammation in sepsis and acute respiratory distress syndrome (ARDS), we used an ex vivo model of systemic inflammation. Naïve peripheral blood leukocytes (PBL) were exposed to longitudinal (days 1-10) plasma samples from ARDS patients divided into three groups based on physiological improvement and clinical outcome by days 7-10: improvers, nonimprovers-survivors, and nonimprovers-nonsurvivors. In a separate group of nonimprovers-survivors, we correlated the severity of lung histopathology with the intensity of NF-κB and GRα nuclear staining in immunohistochemistry analysis of lung tissue obtained by open lung biopsy. We found that exposure of naïve cells to longitudinal plasma samples led to divergent directions in NF-κB and GRα activation that reflected the severity of systemic inflammation. Plasma samples from improvers with declining cytokine levels over time elicited a progressive increase in all measured aspects of glucocorticoid (GC)-induced GRα-mediated activity (p = 0.0001) and a correspondent reduction in NF-κB nuclear binding (p = 0.0001) and transcription of TNF-α and IL-1β (regulated, GRα-driven response). In contrast, plasma samples from nonimprovers with sustained elevation in cytokine levels over time elicited only a modest longitudinal increase in GC-GRα-mediated activity (p = 0.04) and a progressive increase in NF-κB nuclear binding over time (p = 0.0001) that was most striking in nonsurvivors (dysregulated, NF-κB-driven response). By days 3-5, no overlap was observed between groups for NF-κB and GC-GRα nuclear binding. In immunohistochemistry analyses, lung tissues of patients with severe versus mild ARDS had a higher intensity of NF-κB nuclear staining (13 ± 1.3 vs. 7 ± 2.9; p = 0.01) and a lower ratio of GRα:NF-κB in nuclear staining (0.5 ± 0.2 vs. 1.5 ± 0.2; p = 0.007). In conclusion, we demonstrated that the ability of GC-GRα to downregulate NF-κB activation is critical for the resolution of systemic and pulmonary inflammation in ARDS. The findings provide a rationale for the use of prolonged GC treatment in early ARD

Persistent elevation of inflammatory cytokines predicts a poor outcome in ARDS: Plasma IL-1β and IL-6 levels are consistent and efficient predictors of outcome over time

Background: Inflammatory cytokines have been related to the development of adult respiratory distress syndrome (ARDS), shock, and multiple organ dysfunction syndrome (MODS). We tested the hypothesis that unfavorable outcome in patients with ARDS is related to the presence of a persistent inflammatory response. For this purpose, we evaluated the behavior of inflammatory cytokines during progression of ARDS and the relationship of plasma inflammatory cytokines with clinical variables and outcome. Methods: We prospectively studied 27 consecutive patients with severe medical ARDS. Plasma levels of tumor necrosis factor alpha (TNF-α) and interleukins (ILs) 1β, 2, 4, 6, and 8 were measured (enzyme-linked immunosorbent assay [ELISA] method) on days 1, 2, 3, 5, 7, 10, and 12 of ARDS and every third day thereafter while patients were receiving mechanical ventilation. Subgroups of patients were identified based on outcome, cause of ARDS, presence or absence of sepsis, shock, and MODS at the time ARDS developed. Subgroups were compared for levels of plasma inflammatory cytokines on day 1 of ARDS and over time. Results: Of the 27 patients, 13 survived ICU admission and 14 died (a mortality rate of 52%). Overall mortality was higher in patients with sepsis (86 vs 38%, p\u3c0.02). The mean initial plasma levels of TNF-α, IL- 1β, IL-6, and IL-8 were significantly higher in nonsurvivors (p\u3c0.0001) and in those patients with sepsis (p\u3c0.0001). Plasma levels of IL-1β (p\u3c0.01) and IL-6 (p=0.03) were more strongly associated with patient outcome than cause of ARDS (p=0.8), lung injury score (LIS), APACHE II score, sepsis (p=0.16), shock, or MODS score. Plasma levels of TNF-α, IL-1β, IL-6, and IL-8 remained significantly elevated over time (p\u3c0.0001) in those who died. Although it was the best early predictor of death (p\u3c0.001), plasma IL-2\u3e200 pg/mL lost its usefulness after the first 48 h. A plasma IL-1β or IL-6 level \u3e400 pg/mL on any day in the first week of ARDS was associated with a low likelihood of survival. Conclusions: Our findings indicate that unfavorable outcome in acute lung injury is related to the degree of inflammatory response at the onset and during the course of ARDS. Patients with higher plasma levels of TNF-α, IL-1β, IL-6, and IL-8 on day 1 of ARDS had persistent elevation of these inflammatory cytokines over time and died. Survivors had lesser elevations of plasma inflammatory cytokines on day 1 of ARDS and a rapid reduction over time. Plasma IL-1β and IL-6 levels were consistent and efficient predictors of outcome

Acute respiratory failure in patients with severe community-acquired pneumonia: A prospective randomized evaluation of noninvasive ventilation

In uncontrolled studies, noninvasive positive pressure ventilation (NPPV) was found useful in avoiding endotracheal intubation in patients with acute respiratory failure (ARF) caused by severe community-acquired pneumonia (CAP). We conducted a prospective, randomized study comparing standard treatment plus NPPV delivered through a face mask to standard treatment alone in patients with severe CAP and ARF. Patients fitting the American Thoracic Society criteria for severe CAP were included in presence of ARF (refractory hypoxemia and/or hypercapnia with acidosis). Exclusion criteria were: severe hemodynamic instability, requirement for emergent cardiopulmonary resuscitation, home mechanical ventilation or oxygen long-term supplementation, concomitant severe disease with a low expectation of life, inability to expectorate or contraindications to the use of the mask. Fifty-six consecutive patients (28 in each arm) were enrolled, and the two groups were similar at study entry. The use of NPPV was well tolerated, safe, and associated with a significant reduction in respiratory rate, need for endotracheal intubation (21% versus 50%; p = 0.03), and duration of intensive care unit (ICU) stay (1.8 +/- 0.7 d versus 6 +/- 1.8 d; p = 0.04). The two groups had a similar intensity of nursing care workload, time interval from study entry to endotracheal intubation, duration of hospitalization, and hospital mortality. Among patients with chronic obstructive pulmonary disease (COPD), those randomized to NPPV had a lower intensity of nursing care workload (p = 0.04) and improved 2-mo survival (88.9% versus 37.5%; p = 0.05). We conclude that in selected patients with ARF caused by severe CAP, NPPV was associated with a significant reduction in the rate of endotracheal intubation and duration of ICU stay. A 2-mo survival advantage was seen in patients with COPD