Impact of Hydrocortisone Administration on White Blood Cell Gene Expression in Patients With Severe Sepsis

Severe sepsis is characterized by inadequate perfusion of vital organs due to infection. More than 750,000 cases of severe sepsis occur each year in the United States. Mortality among patients with severe sepsis ranges from 7% to 50%. Initiation of antibiotic therapy within the first hour of diagnosis as well as fluid resuscitation and hemodynamic stabilization are primary goals of therapy.

Steroid administration has been shown to improve outcome in the subset of severe sepsis patients suffering from relative adrenal insufficiency. Although initial studies using high dose short course steroid therapy did not demonstrate efficacy, more recent studies of low dose longer duration hydrocortisone administration demonstrated a significant reduction in mortality at 28 days. The mechanism by which steroid administration affords protection is unclear. We hypothesize that steroid administration changes white blood cell gene and protein expression in severe sepsis patients from an immuno-inflammatory profile to a pattern consistent with healing.

Our first specific aim is to obtain plasma and total cellular RNA from leukocytes in the blood of ten patients admitted to Stanford Medical Center with the diagnosis of severe sepsis and adrenal insufficiency. Significant and distinct variations in whole blood leukocyte gene expression patterns occur depending upon the method of RNA isolation. We will attempt to demonstrate that our sampling method provides reliable and consistent data.

Our second specific aim is to begin an analysis of gene expression patterns in white blood cells before and after steroid administration in patients suffering from severe sepsis with relative adrenal insufficiency. We will use a protocol for assessment of gene expression that was developed by members of our research team.

Inclusion criteria

• Admission Diagnosis of Sepsis
• Evidence of Relative Adrenal Insufficiency
• Hypotension (Mean Arterial Pressure less than 60 mm Hg) Refractory to a. Fluid Resuscitation b. Dopamine infusion (greater than 5 micrograms/kg/min) c. Phenylephrine infusion (greater than 1 microgram/kg/min)

Exclusion criteria

• Use of Immunosuppressant Medications
• Immune Compromised Due to Disease (e.g., HIV infection)
• Transfusion of Blood Products within the past 7 Days
• Use of Cytokine Therapy (i.e., G-CSF)
• History of Bone Marrow Transplantation