Eric V. Granowitz

Production of interleukin-1-receptor antagonist during experimental endotoxaemia

Interleukin-1 (IL-1) has been implicated in the pathogenesis of sepsis. IL-1-receptor antagonist (IL-1ra) is a naturally occurring inhibitor of IL-1 activity that competes with IL-1 for occupancy of cell-surface receptors but possesses no agonist activity. We induced endotoxaemia in 9 healthy human volunteers by injection of Escherichia coli endotoxin, and measured plasma concentrations of IL-1 and IL-1ra by radioimmunoassay during the next 24 h. Peak plasma concentrations of IL-1ra were about a hundred-fold greater than those of IL-1 beta. No IL-1 or IL-1ra were detectable in the plasma of 4 volunteers injected with saline. Our results suggest that the predominant natural response to endotoxin in man is the production of antagonist rather than agonist.

Pharmacokinetics, safety and immunomodulatory effects of human recombinant interleukin-1 receptor antagonist in healthy humans

A phase I study of human recombinant interleukin-1 receptor antagonist (IL-1ra) was conducted in healthy males between the ages of 18 and 30. Twenty-five volunteers received a single, 3 h continuous intravenous infusion of doses ranging between 1 mg/kg and 10 mg/kg IL-1ra. At 3 h into the infusion, plasma IL-1ra levels were 3.1 micrograms/ml and 29 micrograms/ml for the 1 mg/kg and 10 mg/kg doses, respectively. Post-infusion plasma IL-1ra levels declined rapidly, exhibiting an initial half-life of 21 min and a terminal half-life of 108 min. Clinical, hematological, biochemical, endocrinological and immunomodulatory effects were monitored over 72 h and compared to those of four subjects receiving a 3 h infusion of saline. There were no clinically significant differences between the drug and saline groups in symptoms, physical examinations, complete blood counts, mononuclear cell phenotypes, blood chemistry profiles, serum iron and serum cortisol levels. Peripheral blood mononuclear cells (PBMC) obtained after completion of the IL-1ra infusion synthesized significantly less interleukin 6 ex vivo than PBMC from saline-injected controls. These data suggest that transient blockade of interleukin 1 receptors is safe and does not significantly affect homeostasis.

Hyperbaric oxygen inhibits stimulus-induced proinflammatory cytokine synthesis by human blood-derived monocyte-macrophages

Hyperbaric oxygen (HBO) is 100% oxygen administered at elevated atmospheric pressure to patients with inflammatory diseases. We developed an in vitro model to investigate the effects of HBO on stimulus‐induced proinflammatory cytokine transcription and translation. Human blood‐derived monocyte‐macrophages were stimulated before being transferred to an HBO chamber where they were incubated at 97·9% O2, 2·1% CO2, 2·4 atmospheres absolute, 37°C. Controls were maintained in the same warm room at normoxia at sea level, hyperoxia or increased pressure alone. A 90‐min HBO exposure inhibited IL‐1β synthesized in response to lipopolysaccharide by 23%, lipid A by 45%, phytohaemagglutinin A (PHA) by 68%, and tumour necrosis factor (TNF)‐α by 27%. HBO suppressed lipopolysaccharide‐, lipid A‐ and PHA‐induced TNF‐α by 29%, 31% and 62%, respectively. HBO transiently reduced PHA‐induced steady state IL‐1β mRNA levels. Hyperoxia alone and pressure alone did not affect cytokine production. The immunosuppressive effect of HBO was no longer evident in monocyte‐macrophages exposed to HBO for more than 3 h. Interestingly, cells exposed to HBO for 12 h synthesized more IL‐1β than cells cultured under control conditions. In summary, HBO exposure transiently suppresses stimulus‐induced proinflammatory cytokine production and steady state RNA levels.

Clinical, hematologic, and immunologic effects of interleukin-10 in humans.

We conducted a double-blind, placebo-controlled study to investigate the safety, pharmacokinetics, and immunological properties of interleukin-10 (IL-10) administration in healthy humans. Volunteers received a single intravenous bolus injection of recombinant human IL-10 (1, 10, or 25μg/kg) or placebo. Cytokine production in whole blood and peripheral blood mononuclear cells (PBMC) was assessed before and 3, 6, 24, and 48 hr after the injection. Peak serum concentrations of IL-10 (15±1.1, 208±20.1, and 505±22.3 ng/ml) occurred after 2–5 min for 1, 10, and 25μg/kg IL-10, respectively. The terminal-phase half-life was 3.18 hr. A transient leukocytosis (24–63% above baseline) was observed 6 hr after injection, which coincided with a dose-dependent decrease (12–24%) in neutrophil superoxide generation. There was a marked inhibition (60–95%) of endotoxin-induced IL-6 production from whole blood in each group receiving IL-10. Production of IL-8 in endotoxin-stimulated blood was reduced in the 10μg/kg group. In PBMC stimulated with phytohemagglutinin and phorbol ester, there was a decrease (72–87%) in interferon-γ (IFNγ) production 6 hr after IL-10 with a return to pre-IL-10 levels after 24 hr. This reduction was only partially associated with a decrease in the number of CD2-bearing cells. We conclude that IL-10 administration into humans is without significant side effects, and a single injection reducesex vivo production of IL-6, IL-8, and IFNγ.

Interleukin-1 (IL-1) receptor blockade reduces endotoxin and Borrelia burgdorferi-stimulated IL-8 synthesis in human mononuclear cells.

Interleukin‐1 (IL‐1) is a potent stimulator of IL‐8 production by fibroblasts and monocytes. In the present study, we asked how much of endotoxin (LPS)‐induced IL‐8 production by human peripheral blood mononuclear cells was due to IL‐1 induced by LPS. Cells were stimulated with either IL‐1β, LPS, or Borrelia burgdorferi, and total IL‐8 was determined by a specific radioimmunoassay. The addition of saturating concentrations of IL‐1 receptor antagonist protein (IRAP) reduced the IL‐1β‐, LPS‐, and B. burgdorferi‐induced IL‐8 synthesis by 85, 50, and 40%, respectively. Increasing the concentration of LPS did not affect the reduction in IL‐8 synthesis observed in the presence of IRAP. Significant inhibition of the IL‐1β‐induced IL‐8 synthesis was observed when IRAP was added 60 or 90 min after IL‐1β; similarly, IL‐8 synthesis after LPS was also reduced by delayed addition of IRAP. These data suggest that the ameliorative effects of IL‐1 receptor blockade in models of inflammation and infection may be due, in part, to suppression of IL‐1‐induced IL‐8.—Porat, R.; Poutsiaka, D. D.; Miller, L. C.; Granowitz, E. V.; Dinarello, C. A. Interleukin‐1 (IL‐1) receptor blockade reduces endotoxin and Borrelia burgdorferi‐stimulated IL‐8 synthesis in human mononuclear cells. FASEB J. 6: 2482‐2486; 1992.

Antibiotic adverse reactions and drug interactions.

When contemplating antibiotic use, intensivists must consider possible beneficial and harmful drug interactions. After antibiotics are instituted, adverse reactions must be anticipated. Acute illness, comorbidities, and concurrent medications affect the presentation and management of antibiotic-related adverse events. Intensivists should use the fewest possible antibiotics, carefully choosing agents that maximize antimicrobial activity and minimize potential drug interactions and adverse reactions.

Extraintestinal Clostridium difficile: 10 Years' Experience at a Tertiary-Care Hospital

OBJECTIVE To determine the clinical characteristics of patients with extraintestinal Clostridium difficile (ECD). MATERIAL AND METHODS All cultures obtained during a 10.5-year period (from Jan. 1, 1985, to Jun. 30, 1995) at a tertiary-care hospital were retrospectively examined. The medical records of patients from whom ECD was isolated were then reviewed. RESULTS Fourteen patients from whom ECD was cultured were identified. Thirteen of these patients (93%) had underlying systemic disease. All but one patient had recent exposure to antibiotics, and all had major bowel pathologic conditions. Nine patients had colon perforation. Of the eight patients in whom the colonic mucosa was directly inspected at operation or endoscopy, only two had evidence of pseudomembranous colitis. Five patients (36%) had documentation of recent diarrhea. ECD was isolated from intraperitoneal sites (in nine patients), blood cultures (in three), a perianal abscess, and a prosthetic hip joint. In 13 patients (93%), the infection was polymicrobial. Seven of the 13 inpatients (54%) survived to dismissal. CONCLUSION C. difficile is a rare isolate outside of the gastrointestinal tract. ECD is found in patients with systemic illness who have been hospitalized (usually for an extended period), have intestinal pathologic conditions, and have received antibiotics. The isolation of ECD portends a poor prognosis.

Hyperbaric oxygen enhances apoptosis in hematopoietic cells

Hyperbaric oxygen (HBO) is 100% oxygen administered at elevated atmospheric pressure. In this study, we examined the effect of HBO on hematopoietic cell apoptosis. Cells exposed to HBO were incubated in a chamber containing 97.9% O2 and 2.1% CO2 at 2.4 atmospheres absolute (ATA). HBO enhanced spontaneous HL-60 cell apoptosis in a time-dependent manner; a 12 h exposure increased apoptosis by 42%. Exposing these cells to hyperoxia at standard atmospheric pressure (95% O2, 5% CO2 at 1 ATA) or increased pressure alone (8.75% O2, 2.1% CO2 at 2.4 ATA) had minimal effect on apoptosis. HBO also enhanced stimulus-induced apoptosis. HL-60 cells stimulated to die using γ radiation underwent 33% more apoptosis than cells exposed to radiation alone. HBO enhanced melphalan, camptothecin, and chlorambucil-induced apoptosis by 22%, 13%, and 8%, respectively. Jurkat cells stimulated to die with anti-Fas antibody underwent 44% more apoptosis when exposed to HBO. Spontaneous apoptosis was increased by 15% in HBO-exposed murine thymocytes. HBOs effect on apoptosis did not require new protein synthesis. As expected, HBO exposure increased the intracellular concentration of H2O2. Incubating HL-60 cells in the presence of dehydroascorbic acid partially abrogated HBO-induced increases in intracellular H2O2 and apoptosis. In summary, HBO enhances spontaneous and stimulus-induced apoptosis in hematopoietic cells, at least in part, by enhancing the intracellular accumulation of H2O2.

Potentially Fatal Interaction Between Azithromycin and Disopyramide

A patient on disopyramide developed disopyramide toxicity when treated concurrently with azithromycin. Evidence of toxicity included an elevated serum disopyramide level and ventricular tachycardia requiring cardioversion. The azalide antibiotic presumably inhibited dealkylation of disopyramide to its major metabolite, mono‐N‐dealkyldisopyramide. Physicians should avoid using azithromycin in patients on disopvramide. If this drug combination is unavoidable, disopyramide levels must be closely monitored.

A pseudoepidemic of Alcaligenes xylosoxidans attributable to contaminated saline

Alcaligenes xylosoxidans is an uncommon but serious cause of nosocomial epidemics. This report describes a cluster of two patients who underwent revision of hip arthroplasties and one patient who had a lumbar puncture. Cultures obtained during all three procedures showed A. xylosoxidans with similar antibiotic sensitivity patterns. An investigation found that saline used to process these specimens was contaminated with this organism.