muramidase and Meningitis--Pneumococcal

Antimicrobial peptides are intrinsic to the innate immune system in many organ systems, but little is known about their expression in the central nervous system. We examined cerebrospinal fluid (CSF) and serum from patients with active bacterial meningitis to assess antimicrobial peptides and possible bactericidal properties of the CSF. We found antimicrobial peptides (human cathelicidin LL-37) in the CSF of patients with bacterial meningitis but not in control CSF. We next characterized the expression, secretion, and bactericidal properties of rat cathelin-related antimicrobial peptide, the homologue of the human LL-37, in rat astrocytes and microglia after incubation with different bacterial components. Using real-time polymerase chain reaction and Western blotting, we determined that supernatants from both astrocytes and microglia incubated with bacterial component supernatants had antimicrobial activity. The expression of rat cathelin-related antimicrobial peptide in rat glial cells involved different signal transduction pathways and was induced by the inflammatory cytokines interleukin 1beta and tumor necrosis factor. In an experimental model of meningitis, infant rats were intracisternally infected with Streptococcus pneumoniae, and rat cathelin-related antimicrobial peptide was localized in glia, choroid plexus, and ependymal cells by immunohistochemistry. Together, these results suggest that cathelicidins produced by glia and other cells play an important part in the innate immune response against pathogens in central nervous system bacterial infections.

Topics: Adolescent; Adult; Aged; Animals; Animals, Newborn; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Brain; Cathelicidins; Cells, Cultured; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Female; Gene Expression; Humans; Male; Meningitis, Pneumococcal; Middle Aged; Muramidase; Neuroglia; Nitrites; Rats; Rats, Wistar; RNA, Messenger; Time Factors; Young Adult

We tested in a rat meningitis model 1) whether pneumococcal cell wall components are capable of producing changes in regional cerebral blood flow, brain water content, and intracranial pressure similar to those we have already observed after intracisternal inoculation of live pneumococci and 2) whether antioxidants would modulate these alterations in the early phase of meningitis.. Regional cerebral blood flow as measured by laser Doppler flowmetry and intracranial pressure were monitored continuously for 4 hours after intracisternal challenge. Brain edema formation was assessed by brain water content determinations. We investigated the following groups: rats challenged intracisternally with the whole intact pneumococcal cell wall (n = 7) or the pneumococcal cell wall hydrolyzed by the M1-muramidase (n = 7); rats injected intracisternally with phosphate-buffered saline (n = 6); rats pretreated intravenously with superoxide dismutase conjugated with polyethylene glycol (10,000 units/kg) and injected intracisternally with cell wall components (n = 5) or phosphate-buffered saline (n = 6); rats injected intracisternally with phosphate-buffered saline and pretreated intravenously with polyethylene glycol (10% solution, 1.2 ml/kg, n = 5) or continuously treated with intravenous free superoxide dismutase (22,000 units/kg per hour, n = 6); and rats continuously treated intravenously with deferoxamine mesylate (10 mg/kg per hour) and injected intracisternally with cell wall components (n = 6) or phosphate-buffered saline (n = 7).. Both pneumococcal cell wall preparations produced a significant increase in regional cerebral blood flow, intracranial pressure, and brain water content. Conjugated superoxide dismutase as well as deferoxamine prevented the increase in intracranial pressure and brain water content. In addition, the increase in regional cerebral blood flow as observed in untreated, cell wall-challenged rats (baseline, 100%; 183.1 +/- 12.3% after 4 hours, mean +/- SEM) was significantly attenuated by administration of both conjugated superoxide dismutase (136.6 +/- 14.1%) and deferoxamine (149.8 +/- 8.2%) (p < 0.05). Polyethylene glycol-conjugated superoxide dismutase alone produced an increase in regional cerebral blood flow (125.6 +/- 8.7% after 4 hours). We found that polyethylene glycol per se accounts for this action.. These data show that pneumococcal cell wall components containing teichoic acid produce changes in regional cerebral blood flow, intracranial pressure, and brain water content and that oxygen radicals contribute to these pathophysiological alterations in the early phase of experimental pneumococcal meningitis.

Topics: Animals; Antioxidants; Body Water; Brain; Cell Wall; Cerebrovascular Circulation; Deferoxamine; Free Radical Scavengers; Hydrolysis; Intracranial Pressure; Male; Meningitis, Pneumococcal; Microcirculation; Muramidase; Polyethylene Glycols; Rats; Rats, Wistar; Streptococcus pneumoniae; Superoxide Dismutase

Meningococci and Haemophilus influenzae may invade the subarachnoid space during the bacteriaemic phase without impairment of the blood-CSF barrier and in the absence of any leucocyte reaction. In pneumococcal meningitis the CSF may also contain less than 100 cells/microliter despite the presence of "pure bacterial cultures", but the barrier is completely broken when the serum/CSF concentration ratio is below 10. A clinical analysis of eight patients with fewer than 100 cells/microliter revealed that the first symptoms of meningitis appeared at least 3 days prior to the diagnostic lumbar puncture. There was a strong neutrophilic reaction in the blood with a prevalence of juvenile forms in most cases, indicating intact antibacterial defence mechanisms. Within 24 h after the start of antibiotic therapy the cell number rose above 2000/microliter accompanied by disappearance of pneumococci. Six of the eight patients died. In three cases autopsy revealed thick layers of pus over the convexities, indicating a compartmental separation of the ventricles and the spinal subarachnoid space. In one case of late diagnosed bacterial meningitis with a pleocytosis of 430/microliter the CSF lysozyme level was seven times higher than compatible with this cell number. Hyperphagocytosis and cellular disintegration is thought to cause the leucopenia within the spinal CSF compartment. "Apurulent bacterial meningitis" can be seen as a disease entity that is a diagnostic pitfall and also a prognostic sign.

Topics: Adult; Aged; Bacterial Infections; Blood-Brain Barrier; Female; Glucuronidase; Humans; Leukocyte Count; Leukopenia; Male; Meningitis; Meningitis, Haemophilus; Meningitis, Listeria; Meningitis, Pneumococcal; Middle Aged; Muramidase; Prognosis

The concentration of lysozyme (LZM) in cerebrospinal fluid was determined in 25 patients with bacterial meningitis, in 18 patients with viral meningitis and in 25 control patients who had other fibrile illnesses. The concentration of LZM was less than 1.5 microgram/ml in all control patients, and slightly to markedly raised in 10 patients with viral meningitis and in 11 out of 13 patients with untreated bacterial meningitis. The concentration of LZM was significantly different in the viral and bacterial meningitis patients (p less than 0.001). Most raised concentrations of cerebrospinal fluid LZM persisted for at least one week after the start of antibiotic treatment. The concentrations of LZM correlated well with concentrations of lactic dehydrogenase. These results show that the determination of cerebrospinal fluid LZM is a useful tool in the differential diagnosis of meningitis, particularly when the prehospital treatment with antibiotics may be responsible for a diagnostically misleading negative bacterial culture of the cerebrospinal fluid and altered cerebrospinal fluid cytology.

Topics: Diagnosis, Differential; Echovirus Infections; Humans; L-Lactate Dehydrogenase; Meningitis, Meningococcal; Meningitis, Pneumococcal; Meningitis, Viral; Mumps; Muramidase