Adjuvant non-bacteriolytic and anti-inflammatory combination therapy in pneumococcal meningitis: an investigation in a mouse model.

OBJECTIVES: Therapy with antibiotics, dexamethasone, and supportive intensive care has improved the prognosis of pneumococcal meningitis, but mortality remains high. Here, we investigated an adjunctive combination therapy of the non-bacteriolytic antibiotic daptomycin plus several anti-inflammatory agents to identify the currently most promising adjunctive combination therapy for pneumococcal meningitis. METHODS: C57BL/6 mice were infected by injection of pneumococci into the cisterna magna. Treatment was begun 21 h after infection, and consisted of ceftriaxone plus (a) dexamethasone, (b) dexamethasone plus daptomycin, (c) daptomycin, (d) daptomycin plus an anti-IL1 antibody, (e) daptomycin plus roscovitine, or (f) daptomycin plus an anti-C5 antibody. Animals were followed until 45 h after infection. Furthermore, adjunctive daptomycin plus anti-C5 antibodies were assessed in a long-term follow-up. RESULTS: Adjunctive treatment with daptomycin and an anti-C5 antibody was superior to adjunctive dexamethasone and reduced disease symptoms (clinical score 1.1 ± 1.1 versus 5.0 ± 2.7, p < 0.0083), improved explorative activity (open field test 17.8 ± 8.2 versus 7.4 ± 4.3 crossed fields/2 minutes, p < 0.0083), and reduced hearing impairment (thresholds for click stimulus 96.1 ± 14.7 versus 114.8 ± 9.3 dB SPL, p < 0.0083) in the acute stage. Furthermore, explorative activity (14.4 ± 7.3 crossed fields/2 minutes versus 6.3 ± 7.2, p < 0.05) and cognitive function (t-maze test, exploration time previously unknown alley 72.4 ± 14.3 versus 48.7 ± 25.6%, p < 0.05) was improved at 2 weeks after infection. Treatment with daptomycin plus an anti-IL-1ß antibody or roscovitine was not of significant benefit in comparison to adjunctive therapy with dexamethasone. CONCLUSIONS: An adjunctive combination of the non-lytic antibiotic daptomycin plus an anti-C5 antibody was superior to standard therapy with adjunctive dexamethasone in the treatment of pneumococcal meningitis.

Diagnostic value of cerebrospinal fluid CXCL13 for acute Lyme neuroborreliosis. A systematic review and meta-analysis.

OBJECTIVES: The utility of cerebrospinal fluid (CSF) CXCL13 for diagnosis of acute Lyme neuroborreliosis (LNB) has been debated and the test is not yet routinely performed. This study's aim was to evaluate its overall diagnostic accuracy through meta-analysis. METHODS: Electronic searches in PubMed MEDLINE and Web of Science were performed to identify relevant articles published before January 2018. A summary receiver operating characteristic curve and an optimal cut-off were estimated modelling multiple cut-offs. Publication bias was evaluated using a funnel plot and the associated regression test. RESULTS: A total of 18 studies involving 618 individuals with acute LNB and 2326 individuals with other neurological disorders meeting the eligibility criteria were identified. The pooled sensitivity for CSF CXCL13 was 89% (95% CI 85%-93%) and the pooled specificity was 96% (95% CI 92%-98%), using the identified optimal cut-off value of 162 pg/mL. There was marked heterogeneity between studies, caused by differences in the designs of the study populations and age distribution. The optimal cut-off in the seven studies with a cross-sectional design was 91 pg/mL (sensitivity 96%, 95% CI 92%-98%; specificity 94%, 95% CI 86%-97%) and in the 11 case-control studies it was 164 pg/mL (sensitivity 85%, 95% CI 78%-91%; specificity 95%, 95% CI 90%-98%). CSF CXCL13 values above the optimal cut-off level (determined in this meta-analysis) were also detectable in some other central nervous system disorders, namely neurosyphilis and central nervous system lymphoma. CONCLUSIONS: Our meta-analysis shows that CSF CXCL13 has the potential to become a useful adjunct in the diagnosis of acute LNB.

Neuroinfectious diseases at a European neurological tertiary care center: one-third of patients require treatment in the neurological intensive care unit.

BACKGROUND AND PURPOSE: Studies on the impact of infectious diseases affecting the nervous system are sparse. METHODS: All patients with neuroinfectious diseases (NIDs) who were treated at our Department of Neurology from 2005 until 2009 were retrospectively analyzed. RESULTS: Patients with NIDs required treatment at the intensive care unit in 34.8%. The mortality rate of patients with NIDs was significantly higher than that of other inpatients with neurological diseases (5.1% vs. 3.0%, respectively, P = 0.018). CONCLUSION: In summary, this study shows that patients with NIDs are severely ill and mortality is high.

Severe cochlear inflammation and vestibular syndrome in an experimental model of Streptococcus suis infection in mice.

Hearing impairment is a common and frequently permanent sequel of Streptococcus suis meningitis in humans. Nevertheless, mechanisms underlying the development of cochlear damage have not been addressed so far. In the present work, we characterized a mouse model of suppurative labyrinthitis and meningitis induced by a systemic infection with S. suis and studied the impact of the injected bacterial dosage on the progression of such inflammatory events. We observed that high infection doses of bacteria lead to sustained bacteremia, with an increase in the permeability of the blood-labyrinth and blood-brain barriers, causing suppurative labyrinthitis and meningitis, respectively. However, in mice infected with a low dose of S. suis, bacteria disappeared quickly from blood, hence, cochlear inflammation and meningitis were not consistent features. This model of S. suis infection seems ideal to evaluate novel drugs that may help alleviate the negative consequences of such important sequelae of S. suis-induced meningitis and labyrinthitis.

A prospective study on the role of CXCL13 in Lyme neuroborreliosis.

BACKGROUND: The definite diagnosis of acute Lyme neuroborreliosis (LNB) requires detection of an increased Borrelia burgdorferi-specific antibody index (AI). The B burgdorferi AI, however, is negative in up to 20% of patients with early LNB and can remain elevated for years after adequate therapy; both of these factors can make the diagnosis difficult. Recent retrospective studies suggested the chemokine CXCL13 as a potential biomarker for LNB. To evaluate its diagnostic value, we conducted a prospective study. METHODS: From March 2008 to August 2009, CSF and serum samples from all patients in whom a B burgdorferi-specific AI was requested (n=692) and CSF analysis revealed CSF pleocytosis (n=192) were included in the study. Because of the low number of patients with untreated LNB, 13 additional retrospectively selected samples of patients with untreated LNB were added. CXCL13 concentrations were measured by ELISA and receiver operating characteristic curves were generated. RESULTS: CSF CXCL13 was highly elevated in all patients with untreated acute LNB (mean=15,149 pg/mL) compared with that in the patients without LNB (mean=247 pg/mL). At a cutoff of 1,229 pg/mL, the sensitivity of CXCL13 was 94.1%, which is higher than the AI (85.7%). Only 7 patients (5 with a CNS lymphoma and 2 with bacterial meningitis) had a CXCL13 level above the cutoff, resulting in a specificity equal to the AI of 96.1%. CONCLUSIONS: CXCL13 shows high sensitivity and specificity for acute, untreated LNB. This novel marker appears to be helpful in clinically atypical cases and, in particular, in early stages of the disease when the B burgdorferi AI is (still) negative.

Therapy of community-acquired acute bacterial meningitis: the clock is running.

Despite antibiotic therapy and supportive intensive medical care, bacterial meningitis remains a disease with high mortality and morbidity. Rapid recognition of symptoms is crucial to direct physicians quickly towards appropriate diagnostic measures and, initially, empiric antibiotic therapy. It has become evident that time from arrival at the hospital to application of the first dose of antibiotics is a crucial independent factor that influences outcome. Here, we review the clinical and laboratory presentation of community-acquired bacterial meningitis and the antibiotic regiments that are currently recommended for its treatment; future therapeutic options are also discussed. Finally, suggestions for the approach to a patient with suspected bacterial meningitis are presented.

Nitrogen and oxygen molecules in meningitis-associated labyrinthitis and hearing impairment.

Pneumococcal meningitis remains a serious disease with a case fatality rate of 15%-25%. Furthermore, long-term residues affect up to 50% of survivors. One of the most frequent sequelae is sensorineural hearing loss, which occurs in 26% of survivors of pneumococcal meningitis. Unfortunately, sufficient treatment regimens are still missing. New insights into the pathology and pathophysiology of meningitis-associated hearing loss have come from animal models of bacterial meningitis. Most likely, bacteria reach the cochlea through the cochlear aquaeduct. Once arrived in the perilymphatic spaces, they induce a severe suppurative labyrinthitis. The blood-labyrinth barrier breaks, hair cells are damaged, and neurons in the spiral ganglion undergo cell death, leading to meningitis-associated hearing loss. Reactive oxygen and nitrogen species, in particular peroxynitrite, seem to be among the crucial mediators of cochlear damage and hearing loss during meningitis. In our rat model of pneumococcal meningitis, adjunctive therapy with the antioxidants and peroxynitrite scavengers Mn(III)tetrakis(4-bencoic acid)-porphyrin (MnTBAP) and N-Acetyl-L-Cystein (NAC) significantly attenuated acute and long-term hearing loss. In several other animal studies of pneumococcal meningitis, adjunctive antioxidant therapy also protected infected animals from intracranial complications. Therefore, the use of antioxidants seems to be a promising future treatment option in pneumococcal meningitis.

A role for the urokinase-type plasminogen activator system in amyotrophic lateral sclerosis.

There is substantial evidence, implicating extracellular matrix (ECM) regulating enzymes in the pathogenesis of motor neuron degeneration in amyotrophic lateral sclerosis (ALS). The most important ECM-degrading proteases are serine proteases (plasminogen activators, PA) and matrix metalloproteinases (MMPs). Since the role of MMPs in ALS has been addressed recently, we investigated the expression of the serine protease urokinase-type plasminogen activator (uPA) and its receptor in ALS. Employing rtPCR, zymography and immunohistochemistry we analyzed the expression of uPA and its receptor uPAR in spinal cord tissue of ALS cases and in the G93A SOD1 transgenic mouse. In the ventral horn of the spinal cord of ALS cases we found increased uPAR staining of motor neurons. In G93A mice, the expression profile of uPA and uPAR mRNA was significantly increased starting at the age of 90 days as compared to non-transgenic littermates. The uPA-dependent plasminogen activation in G93A mice at endstage increased markedly compared with controls and immunostaining of the spinal cord from G93A mice revealed increased uPAR immunostaining in neurons. To determine the functional role of uPA, we investigated the effect of intraperitoneal (i.p.) administration of the uPA inhibitor WX-340 (10 mg/kg), starting at the age of 30 days (n=18). Treatment with WX-340 prolonged (p<0.05) survival of the animals (135+/-2 vs. 126+/-3) as well as improving rotarod performance. Our experiments demonstrate that uPA and its receptor are expressed in ALS patients and in an animal model of ALS. Early inhibition with a synthetic uPA inhibitor prolonged the life of the transgenic animals. These findings indicate that the urokinase-type plasminogen activator system may play a role in the complex pathogenesis of ALS.

[N-acetyl-L-cysteine as a therapeutic option in bacterial meningitis]. / N-acetyl-L-Cystein bei bakterieller Meningitis. Eine zukünftige adjuvante Therapieoption?

Despite antibiotic therapy, supportive intensive care, and adjunctive treatment with dexamethasone, the mortality and morbidity remain high in patients with bacterial meningitis. The intracranial complications that mainly contribute to the poor outcome are in part a result of the production of reactive oxygen and nitrogen species. Experimental studies have shown that the prognosis for bacterial meningitis can be improved by the administration of antioxidants. Especially adjunctive therapy with N-acetyl-L-cystein (NAC) was shown to have mainly positive effects. Since NAC is already in clinical use in high doses for treating other diseases (e.g., acetaminophen intoxication) and only minor side effects have been observed, there is justified hope that adjunctive therapy with NAC could improve the prognosis of patients with bacterial meningitis.

[Cytokine CXCL13--a possible early CSF marker for neuroborreliosis]. / Zyktokin CXCL13 : Ein früher Liquormarker für die Neuroborreliose?

The definitive diagnosis of acute neuroborreliosis (NB) is based upon the presence of lymphomonocytic CSF pleocytosis and intrathecal Borrelia burgdorferi (B.b.)-specific antibody production (expressed by an antibody index of >2). However, the latter might be absent in early stages of the disease. Now a recently discovered additional CSF marker-the cytokine CXCL13-was found to be positive in every initial CSF sample from patients with NB and therefore could be a valuable tool for early diagnosis and initiation of antibiotic therapy. We report an unusual case of NB in a patient with a history of metastatic carcinoma of the prostate and unilateral polyradiculitis. While no intrathecal B.b.-specific antibody production could be demonstrated initially, the CSF CXCL13 level was high (>500 ng/g vs <1.7 ng/g in healthy controls). During the course of the disease, the antibody index turned positive (4.8) and the patient responded to antibiotic therapy, thus confirming the diagnosis. In this case, measuring CXCL13 in the CSF would have led to earlier diagnosis and treatment of NB.

The chemokine CXCL13 (BLC): a putative diagnostic marker for neuroborreliosis.

Using protein expression profiling, the authors identified an upregulation of the chemokine B lymphocyte chemoattractant (BLC) in the CSF of patients with neuroborreliosis but not in patients with noninflammatory and various other inflammatory neurologic diseases. This upregulation was confirmed by ELISA, showing increased BLC levels in every neuroborreliosis patient while being undetectable in patients with noninflammatory neurologic diseases. These results point to BLC as a putative additional diagnostic marker for neuroborreliosis.

Evaluation of cerebrospinal fluid uPA, PAI-1, and soluble uPAR levels in HIV-infected patients.

To evaluate the potential role of the uPAR/uPA/PAI-1 system in HIV-induced blood-brain-barrier (BBB) disruption, CSF uPA-dependent plasminogen activation (PdPA) was analyzed by casein zymography, and CSF protein levels of all three molecules were measured by ELISA. CSF uPAR, but not uPA, PAI-1, or PdPA levels was significantly increased in neurologically compromised HIV+ patients. Only individual patients with severe AIDS dementia complex had increased levels of uPA (but not PAI-1) which fell upon initiation of antiretroviral therapy. The levels of all three molecules did not correlate with the CSF to serum albumin ratio suggesting not an important role in HIV-induced BBB disruption.

Evaluation of CSF glial fibrillary acidic protein (GFAP) as a putative marker for HIV-associated dementia.

BACKGROUND: The involvement of the central nervous system (CNS) is a prominent feature of infection with human immunodeficiency virus type-1 (HIV-1). One of the neuropathological hallmarks of HIV-1-associated dementia (HAD) is the proliferation of astrocytes (astrogliosis). The major structural protein of astrocytes is glial fibrillary acidic protein (GFAP) and its increased expression has been reported in disorders characterized by astrogliosis. PATIENTS AND METHODS: In order to determine whether CSF GFAP may be a putative marker for HAD, we measured CSF GFAP levels of HIV-infected patients with (n = 11) and without (n = 21) HAD, and, additionally, of HIV-infected patients with opportunistic CNS diseases (n = 13) and HIV negative control patients (n = 20) using an immuno flourescent sandwich immunoassay. RESULTS: CSF GFAP levels and the frequency of increased GFAP levels did not significantly differ between the three groups of HIV-infected patients. CONCLUSION: Our data suggest that CSF GFAP is not a sensitive laboratory marker for HAD.

Vascular endothelial growth factor (VEGF) is increased in serum, but not in cerebrospinal fluid in HIV associated CNS diseases.

Vascular endothelial growth factor (VEGF) is a potent angiogenic and mitogenic peptide, which also induces several mediators that may play a role in HIV induced CNS damage. VEGF levels were determined in cerebrospinal fluid (CSF) and serum samples from patients with (n = 8) and without (n = 19) directly HIV associated CNS disorders and HIV negative control patients (n = 18). VEGF serum but not CSF levels were significantly increased in HIV infected patients with (381.1 (78.9) pg/ml) HIV associated CNS diseases compared with those without (120.8 (13.1) pg/ml) and HIV negative control patients (133.1(14.8) pg/ml). Serum samples from patients with untreated HIV associated encephalopathy (HIVE, n = 3) contained the highest VEGF levels (583.9 (71.5) pg/ml). In two patients VEGF serum levels were reduced during antiretroviral therapy. However, regardless of effective viral suppression, patients with HIVE still had higher levels compared with HIV infected patients without HIVE. A relevant increase of serum VEGF was not observed in patients without HIVE though high HI viral load. We conclude that HIVE is associated with increased serum VEGF levels. Further studies are warranted to elucidate the role of VEGF in HIVE.

Pneumococcal meningitis in the rat: evaluation of peroxynitrite scavengers for adjunctive therapy.

We evaluated the effect of different peroxynitrite scavengers for adjunctive therapy of experimental bacterial meningitis. Twenty hours after intracisternal injection of Streptococcus pneumoniae, rats were treated with ceftriaxone [100 mg/kg intraperitoneal (i.p.)] and either urate (300 mg/kg i.p.), Mn(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP, 15 mg/kg i.p.), ascorbate (100 mg/kg i.p.), or urate (300 mg/kg i.p.) + ascorbate (100 mg/kg i.p.). Six hours after initiation of treatment, the cerebrospinal fluid (CSF) pleocytosis was significantly (p<0.05) reduced by urate (8697 +/- 1526 cells/microl) and MnTBAP (8542 +/- 4059 cells/microl) vs. ceftriaxone alone (15,793 +/- 3202 cells/microl). Brain concentrations of proinflammatory cytokines [interleukin-1beta (IL-beta), interleukin-6 (IL-6), and macrophage inflammatory protein-2 (MIP-2)] were also reduced by urate and MnTBAP. The intracranial hypertension was significantly reduced by MnTBAP (14.0 +/- 5.4 mm Hg), but not by urate (25.5 +/- 7.1 mm Hg) vs. ceftriaxone alone (22.5 +/- 5.9 mm Hg). Ascorbate alone had no effect on CSF pleocytosis (15,775 +/- 7058 cells/microl), intracranial pressure (25.6 +/- 8.8 mm Hg), and brain cytokine concentrations. However, the combination of urate and ascorbate was as effective as MnTBAP (CSF pleocytosis: 5392 +/- 4232 cells/microl, intracranial pressure: 13.3 +/- 6.9 mm Hg).

Oxidative stress in bacterial meningitis in humans.

OBJECTIVE: To study reactive nitrogen species-mediated oxidative brain damage and antioxidant defenses in patients with acute bacterial meningitis. METHODS: Nitrotyrosine (a widely used marker for the formation of reactive nitrogen species, such as peroxynitrite) and the lipid peroxidation product 4-hydroxynonenal were detected by immunohistochemistry in brain specimens obtained at autopsy. CSF concentrations of nitrotyrosine were quantified by ELISA. CSF and serum concentrations of ascorbic acid, uric acid, and its oxidation product allantoin were determined by high-pressure liquid chromatography. RESULTS: Tyrosine nitration was strongly increased during meningitis. It was most evident in inflammatory cells and blood vessels in the subarachnoid space. The same cell types stained positive for the lipid peroxidation marker 4-hydroxynonenal, suggesting that reactive nitrogen species contribute to oxidative brain damage during meningitis. High CSF nitrotyrosine concentrations were associated with an unfavorable outcome according to the Glasgow Outcome Score. In the CSF, the increase of nitrotyrosine was accompanied by a depletion of the antioxidant ascorbic acid and an increased oxidation of the natural peroxynitrite scavenger uric acid to allantoin. CONCLUSION: These findings indicate that oxidative stress due to reactive nitrogen species and altered antioxidant defenses are involved in the pathophysiology of bacterial meningitis in humans.

Lack of endothelial nitric oxide synthase aggravates murine pneumococcal meningitis.

Nitric oxide (NO) plays a central role in the pathogenesis of bacterial meningitis. However, the role of NO produced by endothelial NO synthase (eNOS) in meningitis is still unclear. We investigated the influence of eNOS depletion on the inflammatory host response, intracranial complications, and outcome in experimental pneumococcal meningitis. Leukocyte accumulation in the cerebrospinal fluid was more pronounced in infected eNOS-deficient mice than in infected wild type mice. This effect could be attributed to an increased expression of P-selectin, macrophage inflammatory protein-2, keratinocyte-derived cytokine, and interleukin (IL)-1beta in the brain of infected eNOS-deficient mice. However, no differences in the cerebral expression of intercellular adhesion molecule-1, tumor necrosis factor-alpha, and IL-6 as well as of neuronal NOS and inducible NOS could be detected between infected wild type and mutant mice. In addition to enhanced leukocyte infiltration into the CSF, meningitis-associated intracranial complications including blood-brain barrier disruption and the rise in intracranial pressure were significantly augmented in infected eNOS-deficient mice. The aggravation of intracranial complications was paralleled by a worsening of the disease, as evidenced by a more pronounced hypothermia, an enhanced weight reduction, and an increased death rate. The current data indicate that eNOS deficiency is detrimental in bacterial meningitis. This effect seems to be related to an increased expression of (certain) cytokines/chemokines and adhesion molecules; thus leading to increased meningeal inflammation and, subsequently, to aggravated intracranial complications.

Experimental meningitis in the rat: protection by uric acid at human physiological blood concentrations.

The natural peroxynitrite scavenger uric acid was previously shown to be protective in a rat model of pneumococcal meningitis; however, rats have much lower blood uric acid levels than humans. Therefore, we evaluated its therapeutic effect at human physiological blood concentrations. Intraperitoneal pretreatment with uric acid increased its blood concentrations from 44.9+/-10.0 microM in untreated rats to 169.8+/-122.6 microM and reduced the cerebrospinal fluid (CSF) pleocytosis from 12767+/-2520 to 8376+/-2450 cells/microl (P<0.05) and the intracranial pressure from 11.6+/-3.0 to 4.3+/-1.2 mm Hg (P<0.05). Coadministration of oxonic acid, an inhibitor of urate oxidase, increased the blood uric acid levels to 355.0+/-79.6 microM and further reduced the CSF pleocytosis (4190+/-1749 cells/microl, P<0.05) and the intracranial pressure (1.4+/-2.4 mm Hg). Uric acid+oxonic acid also had a beneficial effect when administered 2 or 4 h after the induction of meningitis. We demonstrate a dose-dependent anti-inflammatory effect of uric acid at blood levels in the human physiological range.

Superantigen overcomes resistance of IL-6-deficient mice towards MOG-induced EAE by a TNFR1 controlled pathway.

Experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein peptide 35-55 (MOG) leads to a chronic form of disease characterized by demyelination, inflammation and gliosis in the central nervous system (CNS). Recently IL-6 and LT alpha were found to be required for induction of the disease. The main features associated with EAE resistance of IL-6(-/-) and LT alpha(-/-) mice were reduced T cell proliferation and endothelial activation. As shown here treatment of MOG-immunized IL-6(-/-) mice with staphylococcal enterotoxin B (SEB)reversed their resistance to MOG-induced EAE. SEB failed to restore susceptibility to EAE in LT alpha(-/-) mice. The effect of SEB to induce EAE in IL-6(-/-) mice depends on TNF receptor type 1 (TNFR1) signaling because IL-6/TNF/LT alpha(-/-) and IL-6/TNFR1(-/-) are refractory to SEB. TNFR1 is involved in SEB induced trafficking of T cells into the CNS as evidenced by the failure to up-regulate VCAM-1 on CNS endothelium and lack of accumulation of V beta 8(+) T cells in the CNS of IL-6/TNFR1(-/-) mice upon immunization with MOG and treatment with SEB. The course of SEB triggered EAE in MOG immunized IL-6(-/-) mice was characterized by reduced severity and duration of clinical manifestations, which were associated with a significant drop of CNS infiltrating neutrophils and MIP-2 expression after peak disease. Taken collectively the effect of SEB to overcome EAE resistance points to a transient IL-6 independent but TNFR1 dependent proinflamatory pathway in EAE pathogenesis and suggests a crucial function for IL-6 in disease perpetuation.