Gregor Zysk

Anti-Inflammatory Treatment Influences Neuronal Apoptotic Cell Death in the Dentate Gyrus in Experimental Pneumococcal Meningitis

Apoptotic neuronal death and the increase of neuron-specific enolase (NSE) in cerebrospinal fluid (CSF) were studied in a rabbit model of experimental pneumococcal meningitis after treatment with antimicrobial (ceftriaxone) and antiinflammatory agents (dexamethasone, monoclonal antibodies against the β-subunit of β2-integrins [anti-CD18 mAb]). Twenty-four hours after infection, apoptotic cell death was found solely in the granular cell layer of the dentate gyrus. Neurons with DNA fragmentation were quantified with the in situ tailing (IST) reaction. Dexamethasone and anti-CD18 mAb inhibited the NSE increase in CSF significantly (p=0.003, p=0.011). After administration of dexamethasone the density of apoptotic neurons was significantly higher than in control animals receiving only ceftriaxone (p=0.044). The median of the density of apoptotic neurons was lower in the dentate gyrus in animals receiving anti-CD18 mAb and ceftriaxone vs those receiving only ceftriaxone, although the difference did not reach statistic significance (p=0.058). In conclusion, apoptotic cell death occurs in the dentate gyrus during the early phase of bacterial meningitis. The extent was influenced by antiinflammatory therapy. The systemic administration of glucocorticoids increased the quantity of apoptotic neurons in the dentate gyrus but reduced overall neuronal damage as indicated by low levels of NSE concentration in CSF.

Reduced Release of Pneumolysin by Streptococcus pneumoniae In Vitro and In Vivo after Treatment with Nonbacteriolytic Antibiotics in Comparison to Ceftriaxone

ABSTRACT Pneumolysin, a virulence factor of Streptococcus pneumoniae with cytotoxic and proinflammatory activities, occurs at concentrations from 0.85 to 180 ng/ml in cerebrospinal fluid (CSF) of meningitis patients. In pneumococcal cultures and in a rabbit meningitis model, the concentrations of pneumolysin in supernatant and CSF were lower after addition of nonbacteriolytic bactericidal antibiotics (rifampin and clindamycin) than after incubation with ceftriaxone.

Decreased Virulence of a Pneumolysin-Deficient Strain of Streptococcus pneumoniae in Murine Meningitis

ABSTRACT Pneumolysin, neuraminidases A and B, and hyaluronidase are virulence factors of Streptococcus pneumoniae that appear to be involved in the pathogenesis of meningitis. In a murine model of meningitis after intracerebral infection using mutants of S. pneumoniae D39, only mice infected with a pneumolysin-deficient strain were healthier at 32 and 36 h, had lower bacterial titers in blood at 36 h, and survived longer than the D39 parent strain. Cerebellar and spleen bacterial titers, meningeal inflammation, and neuronal damage scores remained uninfluenced by the lack of any of the virulence factors.

Pharmacokinetic quantification of the exchange of drugs between blood and cerebrospinal fluid in man

SummaryVarious parameters which may be useful in quantification of drug transit from blood into CSF and vice versa after a short duration infusion are compared here by recalculating previously published data from our group.Due to the slower entry into and elimination from the CSF compartment as compared to the central compartment, the ratio of drug concentrations in CSF and serum sampled at the same time increase with time after an infusion. Therefore, concentration quotients of simultaneously drawn blood and CSF are inadequate to characterise CSF penetration.The ratio of the areas under the concentration-time curves in a body fluid and serum (AUCbody fluid/AUCS) is an established measure to quantify overall penetration from the central into a peripheral compartment. AUCCSF/AUCS is closely correlated with the quotient of the maximum CSF and serum concentrations (CmaxCSF/ CmaxS) (rS=0.87, n=42, P<0.001) and with the rate constant of distribution in CSF (CLin/VCSF) (rS=0.80, n=42, P<0.001).Since CmaxCSF/CmaxS depends on the mode of drug administration, it is suggested that AUCCSF/AUCS be used to quantify overall drug transit into CSF. CLin/VCSF is of use when CSF can only be sampled once, or when the velocity of the transit of a drug into CSF is to be described.The CSF exit rate constant (CLout/VCSF) characterises elimination from CSF independent of the elimination from serum and may be applied to estimate the formation rate of CSF; in the present study it averaged 20 ml/h.

Elimination of blood-derived macrophages inhibits the release of interleukin-1 and the entry of leukocytes into the cerebrospinal fluid in experimental pneumococcal meningitis

Parameters of inflammation during pneumococcal meningitis were determined in rabbits after monocyte elimination by dichloromethylene diphosphonate (Cl(2)MDP)-containing mannosylated liposomes in comparison with untreated controls. Monocyte depletion reduced the migration of white blood cells into the cerebrospinal fluid (CSF) (medians: 42 versus 2146/mm3 at 18 h, 323 versus 7413/mm3 at 24 h p.i., p < 0.01). CSF IL-1beta concentrations were lower in depleted animals (379 versus 3282 pg/ml, 24 h p.i., p < 0.01), whereas TNF-alpha concentrations were not different. Monocyte-depleted animals lost body temperature during the experiment carried out in anaesthesia (p = 0.01) indicating that macrophages are necessary for thermogenesis during meningitis.

D- and L-lactate in Rabbit and Human Bacterial Meningitis

Increased total CSF lactate is an important indicator differentiating bacterial from aseptic meningitis. Bacteria can produce D- and L-lactate; mammalian cells produce only L-lactate. We measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Escherichia coli in vitro, of S. pneumoniae and E. coli in rabbit experimental meningitis and of various common pathogens in CSF from patients with bacterial meningitis. Despite marked in vitro production of D-lactate by S. aureus (maximum: 4.59 mmol/l; i.e. 34.9% of total lactate), N. meningitidis (4.62 mmol/l; i.e. 98.1%) and E. coli (3.14 mmol/l; i.e. 97.2%), minimal amounts were measured in human S. aureus (0.38 mmol/l; i.e. 1.3% of total lactate) or N. meningitidis (0.28 mmol/l; i.e. 3.9%) and experimental E. coli meningitis (0.75 mmol/l; i.e. 4.4%). In only 9 of 54 human CSF samples did D-lactate exceed 0.15 mmol/l. S. pneumoniae did not produce significant amounts of D-lactate in vitro (maximum: 0.55 mmol/l; i.e. 2.7% of total lactate), in experimental meningitis (0.18 mmol/l; i.e. 3%) or in human cases of meningitis (0.28 mmol/l; i.e. 1.9%). In conclusion, increased total CSF lactate in meningitis consists mainly of L-lactate and originates predominantly from host cells. CSF D-lactate is of limited diagnostic value.Increased total CSF lactate is an important indicator differentiating bacterial from aseptic meningitis. Bacteria can produce D- and L-lactate; mammalian cells produce only L-lactate. We measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Escherichia coli in vitro, of S. pneumoniae and E. coli in rabbit experimental meningitis and of various common pathogens in CSF from patients with bacterial meningitis. Despite marked in vitro production of D-lactate by S. aureus (maximum: 4.59 mmol/l; i.e. 34.9% of total lactate), N. meningitidis (4.62 mmol/l; i.e. 98.1%) and E. coli (3.14 mmol/l; i.e. 97.2%), minimal amounts were measured in human S. aureus (0.38 mmol/l; i.e. 1.3% of total lactate) or N. meningitidis (0.28 mmol/l; i.e. 3.9%) and experimental E. coli meningitis (0.75 mmol/l; i.e. 4.4%). In only 9 of 54 human CSF samples did D-lactate exceed 0.15 mmol/l. S. pneumoniae did not produce significant amounts of D-lactate in vitro (maximum: 0.55 mmol/l; i.e. 2.7% of total lactate), in experimental meningitis (0.18 mmol/l; i.e. 3%) or in human cases of meningitis (0.28 mmol/l; i.e. 1.9%). In conclusion, increased total CSF lactate in meningitis consists mainly of L-lactate and originates predominantly from host cells. CSF D-lactate is of limited diagnostic value.