The Pattern of Interleukin-1β (IL-1β) and Its Modulating Agents IL-1 Receptor Antagonist and IL-1 Soluble Receptor Type II in Acute Meningococcal Infections

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Abstract
Interleukin-1β (IL-1β) is considered an important mediator in the pathogenesis of septic shock or bacterial meningitis. Its activity is specifically modulated by IL-1 receptor antagonist (IL-1Ra) and IL-1 soluble receptor type II (IL-1sRII). We now describe the time-course of IL-1β and these modulating agents in 59 patients with acute meningococcal infections, the prototype human disease of acute endotoxin exposure. Plasma IL-1β was increased only in severe shock and normalized within 12 to 24 hours, indicating that patients were admitted in an early stage of cytokine activation. Increased IL-1β values in cerebrospinal fluid (CSF ) were confined to patients with meningitis. Plasma IL-1Ra was elevated in both shock and nonshock patients, extremely high values being measured in severe shock. High concentrations of IL-1Ra in CSF were found in meningitis. Plasma IL-1Ra peaked shortly after IL-1β and decreased steeply in 1 to 2 days, followed by sustained moderately elevated levels in shock patients. Interestingly, IL-1sRII showed a completely different pattern. At admission, both nonshock and shock patients manifested a similar moderate increase of plasma IL-1sRII. However, during recovery plasma IL-1sRII further increased reaching maximal concentrations 3 to 5 days after admission, 1 to 2 days after normalization of IL-1Ra. In shock patients this increase was more prominent than in nonshock patients. It is hypothesized that this increase in plasma IL-1sRII can be explained by a synergistic effect of dexamethasone and endotoxin. A second interesting observation was that, unlike the pattern in plasma, IL-1sRII levels in CSF paralleled those of IL-1β and IL-1Ra. This suggests different modulation of IL-1β activity in the subarachnoid space and the plasma compartment. We conclude that: (1) During the early stage of meningococcal infections IL-1Ra modulates IL-1 activity, whereas during recovery IL-1sRII may be more important. (2) Modulation in CSF and in the plasma compartment are differentially regulated.