Margaret Tropea

Detection of Macrophage Inflammatory Protein (MIP)-1α and MIP-β during Experimental Endotoxemia and Human Sepsis

Macrophage inflammatory protein (MIP)-1alpha and MIP-1beta regulate leukocyte activation and trafficking. To assess the role of MIP-1alpha and MIP-1beta in human inflammation, healthy subjects were studied during experimental endotoxemia with prior administration of ibuprofen, a cyclooxygenase inhibitor, or dimeric p75 tumor necrosis factor (TNF)-alpha receptor, a TNF antagonist; septic patients were also studied. Following endotoxin, blood levels of both MIP-1 molecules rose acutely and fell to baseline by 6 h (P=. 001). While MIP-1 mediates fever in animals independent of cyclooxygenase blockade, in subjects given endotoxin and ibuprofen, MIP-1 levels increased and fever was suppressed. MIP-1 levels were not diminished by inhibiting circulating TNF-alpha in humans. In septic patients, elevated levels of MIP-1alpha and MIP-1beta were detected within 24 h of sepsis and fell in parallel with TNF-alpha and interleukin-6 (P<.01). MIP-1alpha and MIP-1beta increase during acute inflammation but are not associated with fever in endotoxemic humans during cyclooxygenase blockade.

Effects of methylprednisolone infusion on markers of inflammation, coagulation, and angiogenesis in early acute respiratory distress syndrome.

Objective: Evaluate the effects of methylprednisolone on markers of inflammation, coagulation, and angiogenesis during early acute respiratory distress syndrome. Design: Retrospective analysis. Setting: Four intensive care units. Subjects: Seventy-nine of 91 patients with available samples enrolled in a randomized, blinded controlled trial. Interventions: Early methylprednisolone infusion (n = 55) compared with placebo (n = 24). Measurements and Main Results: Interleukin-6, tumor necrosis factor &agr;, vascular endothelial growth factor, protein C, procalcitonin, and proadrenomedullin were measured in archived plasma. Changes from baseline to day 3 and day 7 were compared between groups and in subgroups based on the precipitating cause of acute respiratory distress syndrome. Methylprednisolone therapy was associated with greater improvement in Lung Injury Score (p = .003), shorter duration of mechanical ventilation (p = .005), and lower intensive care unit mortality (p = .05) than control subjects. On days 3 and 7, methylprednisolone decreased interleukin-6 and increased protein C levels (all p < .0001) compared with control subjects. Proadrenomedullin levels were lower by day 3 with methylprednisolone treatment (p = .004). Methylprednisolone decreased interleukin-6 by days 3 and 7 in patients with pulmonary causes of acute respiratory distress syndrome but only at day 3 in those with extrapulmonary causes of acute respiratory distress syndrome. Protein C levels were increased with methylprednisolone on days 3 and 7 in patients with infectious and/or pulmonary causes of acute respiratory distress syndrome (all p < .0001) but not in patients with noninfectious or extrapulmonary causes of acute respiratory distress syndrome. Proadrenomedullin levels were decreased with methylprednisolone on day 3 in patients with infectious or extrapulmonary causes of acute respiratory distress syndrome (both p ⩽ .008) but not in noninfectious or pulmonary acute respiratory distress syndrome. Tumor necrosis factor, vascular endothelial growth factor, and procalcitonin were elevated but not differentially affected by methylprednisolone therapy. Conclusions: In early acute respiratory distress syndrome, administration of methylprednisolone was associated with improvement in important biomarkers of inflammation and coagulation and clinical outcomes. Biomarker changes varied with the precipitating cause of acute respiratory distress syndrome, suggesting that the underlying mechanisms and response to anti-inflammatory therapy may vary with the cause of acute respiratory distress syndrome.

Temporal Changes in Microrna Expression in Blood Leukocytes from Patients with the Acute Respiratory Distress Syndrome

Background: MicroRNA (miRNA) control gene transcription by binding to and repressing the translation of messenger RNA (mRNA). Their role in the acute respiratory distress syndrome (ARDS) is undefined. Methods: Blood leukocytes from 51 patients enrolled in a prior randomized trial of corticosteroids for ARDS were analyzed. After screening eight patients with microarrays for altered miRNA expression, 25 miRNAs were selected for further analysis using RT-PCR in all 51 patients. Results: On day 0, the 51 patients had APACHE III score of 60.4 ± 17.7 and PaO2/FiO2 of 117 ± 49. 21 miRNA were expressed at increased levels in blood leukocytes at the onset of ARDS compared with healthy controls. These miRNA remained elevated at day 3 and increased further by day 7 (log2 fold change from 0.66 to 5.7 fold, P <0.05 compared to day 0). In a subgroup analysis (37 patients treated with corticosteroids and 14 treated with placebo), the interaction of miRNA expression over time and steroid administration was not significant suggesting that systemic corticosteroids had no effect on the miRNA detected in our study. In contrast, corticosteroids but not placebo decreased IL-6 and C-reactive protein at day 3 (P < 0.001) demonstrating an early systemic anti-inflammatory response whereas both treatment arms had decreased values by day 7 (P <0.001). Conclusions: Expression of miRNA is increased in blood leukocytes of patients with ARDS at day 0 and day 3 and rises further by day 7, when systemic inflammation is subsiding. These effects appear independent of the administration of steroids, suggesting different inflammatory modifying roles for each in the resolving phases of ARDS.

Isolation of a circulating CD45-, CD34dim cell population and validation of their endothelial phenotype

Accurately detecting circulating endothelial cells (CECs) is important since their enumeration has been proposed as a biomarker to measure injury to the vascular endothelium. However, there is no single methodology for determining CECs in blood, making comparison across studies difficult. Many methods for detecting CECs rely on characteristic cell surface markers and cell viability indicators, but lack secondary validation. Here, a CEC population in healthy adult human subjects was identified by flow cytometry as CD45-, CD34dim that is comparable to a previously described CD45-, CD31bright population. In addition, nuclear staining with 7-aminoactinomycin D (7-AAD) was employed as a standard technique to exclude dead cells. Unexpectedly, the CD45-, CD34dim, 7-AAD- CECs lacked surface detectable CD146, a commonly used marker of CECs. Furthermore, light microscopy revealed this cell population to be composed primarily of large cells without a clearly defined nucleus. Nevertheless, immunostains still demonstrated the presence of the lectin Ulex europaeus and von Willebrand factor. Ultramicro analytical immunochemistry assays for the endothelial cell proteins CD31, CD34, CD62E, CD105, CD141, CD144 and vWF indicated these cells possess an endothelial phenotype. However, only a small amount of RNA, which was mostly degraded, could be isolated from these cells. Thus the majority of CECs in healthy individuals as defined by CD45-, CD34dim, and 7-AAD- have shed their CD146 surface marker and are senescent cells without an identifiable nucleus and lacking RNA of sufficient quantity and quality for transcriptomal analysis. This study highlights the importance of secondary validation of CEC identification.