Antibody neutralization of vascular endothelial growth factor (VEGF) fails to attenuate vascular permeability and brain edema in experimental pneumococcal meningitis

To determine the contribution of vascular endothelial growth factor (VEGF) to cerebral edema formation in bacterial meningitis, we used a VEGF neutralizing antibody to block VEGF in rabbits, following induction of meningitis by intracisternal inoculation with 10⁹ heat-killed pneumococci. At 8 h, cerebrospinal fluid (CSF) VEGF was significantly elevated in infected untreated animals, and correlated with CSF white blood cell (WBC) count (r=0.56, P=0.004), and brain water content (r=0.42, P=0.04). Blocking of VEGF did not attenuate brain edema, blood–brain barrier disruption, or CSF pleocytosis. The functional role of VEGF in the pathophysiology of BM remains elusive.     

Fluorescence method of evaluation of the lysosomes of the lymphoid cells of the cerebrospinal fluid in meningitis and meningism

The fluorescence method of Blume et al. was found to be useful for identification and morphological evaluation of lysosomes in cerebrospinal fluid cells. The investigations were carried out in 49 patients with viral and bacterial meningitis or meningismus. It was demonstrated that the CSF cells in most patients with purulent meningitis contained no fluorescent granules in an early stage of the disease before introduction of antibacterial therapy. These granules were found in CSF cells in cases of leptospirosis, viral meningitis and meningismus of various aetiology in acute stage of the disease and even in convalescence, and in purulent meningitis in convalescence. In bacterial meningitis large lysosomal granules were observed, and in viral meningitis these granules were small. The method visualizes easily bacteria (meningococci and pneumococci) in the cerebrospinal fluid.     

Beta-2-microglobulin and ferritin in cerebrospinal fluid for evaluation of patients with meningitis of different etiologies.

To determine whether or not the beta-2-microglobulin (beta2-m) and/or ferritin levels in cerebrospinal fluid (CSF) can be used as markers for the differential diagnosis of meningitis and determination of the response to treatment, 122 subjects with etiologically well-characterized diagnoses were classified into three groups: bacterial meningitis (n = 5; mean age +/- SD. 1.0+/-1.0 year), viral meningitis (n = 39; 5.9+/-3.8 years), and a non-meningitis group (n = 78; 5.2+/-4.9 years). The levels of beta2-m and ferritin in CSF were determined by means of a latex photometric immunoassay. The statistical significance of the data was analyzed with the Mann Whitney U-test. A receiver operating characteristic curve was used to evaluate the diagnostic accuracy of each prediction marker. This study indicated that (1) the levels of beta2-m and ferritin in CSF were related with age in the non-meningitis group: subjects of up to 5 months of age exhibited higher concentrations of these proteins than ones of above 6 months of age (beta2-m, 1.89+/-1.13 vs. 0.84+/-0.65 mg/l. P < 0.01; ferritin, 2.97+/-2.04 vs. 1.81+/-1.34 microg/l, P = 0.09); (2) the beta2-m level was significantly higher in the CSF of patients with viral meningitis than in ones without meningitis (2.41+/-1.23 vs. 0.84+/-0.65 mg/l, P < 0.01): the best cut-off value was 1.2 mg/l (3) the ferritin level was significantly higher in the CSF of patients with bacterial meningitis than in ones with viral meningitis (43.24+/-39.49 vs. 6.81+/-7.41 microg/l, P < (.01): the best cut-off value was 7.5 microg/l; and (4) sequential measurement of the CSF ferritin level was of value for determination of the response to antibiotic treatment for bacterial meningitis. These results only apply to patients of greater than 6 months of age. beta2-m and ferritin in the CSF can be used as an ancillary tool for diagnostic guidance in the acute phase of meningitis and determination of the response to treatment for bacterial meningitis.     

Cerebrospinal fluid levels of cyclic nucleotides in meningitis and idiopathic polyneuritis

Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) were measured in cerebrospinal fluid (CSF) and plasma from 7 patients with bacterial meningitis, 9 patients with serous meningitis, 5 patients with idiopathic polyneuritis and 15 reference patients. A significantly (P less than 0.01) higher mean concentration of CSF cAMP was found in serous meningitis (33.8 +/- 12.5 nmol/l) compared to the reference group (20.2 +/- 4.0 nmol/l). No significant difference could be observed between the patients with purulent meningitis compared to the reference group. The CSF cAMP concentration (11.0 +/- 2.8 nmol/l) for idiopathic polyneuritis was significantly (P less than 0.01) lower than in the reference group. No difference in CSF levels of cGMP or in the cAMP/cGMP ratios were detected between the groups. Our data suggest that the ratio between cAMP concentrations in CSF and plasma may aid in the differential diagnosis between serous and purulent meningitis.     

Expression of vascular endothelial growth factor in tuberculous meningitis.

The pathogenesis of tuberculous meningitis is still unclear. Recently, vascular endothelial growth factor (VEGF) was found to be associated with inflammatory diseases and we found the increased serum level of VEGF in pulmonary tuberculosis. We hypothesized that VEGF might be associated with the pathogenesis of tuberculous meningitis and measured serum and cerebrospinal fluid (CSF) levels of VEGF in 28 patients with tuberculous meningitis and 31 non-tuberculous infectious meningitis patients (13 bacterial meningitis patients, eight fungal meningitis patients and 10 patients with viral meningitis) before therapy. We examined the CSF VEGF levels 3 months after in 12 tuberculous meningitis patients. The serum and CSF levels of VEGF were significantly higher in tuberculous meningitis than in other meningitis. The decrease in titer of CSF VEGF paralleled the clinical improvement of tuberculous meningitis. Immunohistochemical staining of autopsied brains demonstrated the presence of VEGF in the inflammatory mononuclear cells of the dense fibroconnective tissue both in the subarachnoid space and surrounding the vasculitis lesion. We found the expression of VEGF in tuberculous meningitis and think that VEGF reflects its activity.     

Interleukin-1β and tumor necrosis factor-α in cerebrospinal fluid of children with bacterial meningitis

Certain cytokines may contribute to the sequence of events that lead to meningeal inflammation in bacterial meningitis. The purpose of this study was to determine the levels of cytokines in the cerebrospinal fluid (CSF) of children with bacterial meningitis and aseptic meningitis of different etiologies. We determined the concentrations of interleukin-1beta (IL-1beta) and tumor necrosis factor (TNF-alpha) in the CSF of 171 specimens of 144 patients whose cases were classified as follow: bacterial meningitis (n=23), aseptic meningitis (n=26) and non-meningitis (n=95). The detectable IL-1beta concentration (> or =20 pg/ml) in the bacterial meningitis, aseptic meningitis and non-meningitis groups were observed with 78.3%, 3.8%, and 8.4%, respectively. Significantly higher serum IL-1beta concentrations were detected in those with bacterial meningitis than those with aseptic meningitis (538.93+/-605.32 pg/ml vs 2.52+/-11.57 pg/ml; P<0.001) or among non-meningitis subjects (2.90+/-11.91 pg/ml; P<0.001). The mean TNF-alpha concentration was 148.74+/-338.77 pg/ml. There was significantly more TNF-alpha than aseptic meningitis (6.85+/-17.93 pg/ml; P<0.001) or non-meningitis (7.67+/-16.07 pg/ml; P<0.001). With regard to diagnosis, measurement of IL-1beta and TNF-alpha levels showed sensitivities of 78% and 74%, respectively; specificities of 96% and 81%, respectively. It is suggested that the levels of these cytokines, especially IL-1beta and TNF-alpha, are useful markers for distinguishing bacterial meningitis from aseptic meningitis.     

Matrix metalloproteinases contribute to the blood—brain barrier disruption during bacterial meningitis

In this study, we investigated the involvement of matrix metalloproteinases (MMPs) in the pathophysiology of bacterial meningitis. By using an enzyme immunoassay, high concentrations of MMP-9 were detected in the cerebrospinal fluid (CSF) of adult patients with bacterial meningitis but not in controls, and in patients with Guilain-Barré syndrome. Moreover, we observed significantly elevated concentrations of the tissue inhibitor of metalloproteinase-1 (TIMP-1) in the CSF of patients with bacterial meningitis, compared with controls. In a rat model of meningococcal meningitis, intracisternal injection of heat-killed meningococci caused a disruption of the blood–;brain barrier (BBB), and increase in intracranial pressure, and CSF pleocytosis paralleled by the occurrence of MMP-9 activity in the CSF 6 hours after meningococcal challenge. The MMP inhibitor batimastat (BB-94) significantly reduced the BBB disruption and the increase in intracranial pressure irrespective of the time of batmastat administration (15 minutes before and 3 hours after meningococcal challenge) but failed to significantly reduce CSF white blood cell counts. In conclusion, our results suggest that MMPs are involved in the alterations of BBB permeability during experimental meningococcal meningitis.     

Cerebrospinal fluid levels of soluble CD14 in inflammatory and non-inflammatory diseases of the CNS: upregulation during bacterial infections and viral meningitis

The CD14 antigen, an important cell surface molecule of monocytic cells, is involved in cellular activation: it binds lipopolysaccharide and other cellular lipid structures. Brain macrophages play a pivotal role during inflammatory reactions of the CNS parenchyma, ventricles and meninges. A soluble form of CD14 (sCD14) was measured in paired cerebrospinal fluid (CSF) and serum samples from 91 patients with different neurological diseases. Mean levels of circulating sCD14 in CSF in a control group of 22 patients with neurologic complaints but no neurological deficit on clinical examination were 0.19 +/- 0.06 (mean +/- SD) mg/l. The CSF/blood ratios of sCD14 was 49 +/- 16 x 10(-3), while those of albumin were 4.4 +/- 1.4 x 10(-3). These extremely high CSF/blood ratios of the sCD14 molecule compared to albumin indicate a local cerebral production. No significant changes in CSF sCD14 levels were found in patients with non-inflammatory neurological diseases (NID). In contrast, CSF sCD14 levels were markedly elevated during acute meningitis, but there was no direct correlation between sCD14 and monocyte count in the CSF. Thus, sCD14 could not originate in the CSF compartment from monocytes alone. The highest values for sCD14 were found in CSF during infections with various pathogens such as Staphylococcus aureus or Listeria monocytogenes. While sCD14 serum levels dramatically increased during acute bacterial meningitis, sCD14 ratios did not correlate with albumin ratios during the course of disease. Therefore, increased CSF sCD14 may originate from cerebral production by activated or infiltrated macrophages rather than passive diffusion from the blood, while elevated sCD14 serum levels resulted from enhanced local production. Increased CSF and serum sCD14 values were also observed in meningitis caused by viral infection. As in bacterial meningitis, sCD14 in CSF specimens did not correlate with the function of the blood/CSF barrier. Repeated lumbar punctures revealed a normalization of CSF sCD14 levels during clinical recovery. These results provide the first evidence for local production of sCD14 within the CNS. Our findings further indicate that sCD14 in CSF is a reliable marker for activation of macrophages within the CNS during inflammatory processes.     

NF-kappaB activation in cerebrospinal fluid cells from patients with meningitis

We examined whether or not NF-kappaB, a factor that regulates expression of the genes that code for pro-inflammatory cytokines, is activated in cerebrospinal fluid (CSF) cells to investigate the production of pro-inflammatory cytokines by CSF cells in patients with meningitis. Western blotting demonstrated that NF-kappaB was more activated in CSF cells of patients with bacterial meningitis than in those of patients with aseptic meningitis. NF-kappaB was hardly activated in carcinomatous meningitis. The NF-kappaB activation in CSF cells of patients with meningitis tended to be correlated with the CSF interleukin-6 concentration. Our data suggested that CSF cells produce pro-inflammatory cytokines through NF-kappaB activation in meningitis, and that increased NF-kappaB activation in CSF cells indicate infectious meningitis rather than carcinomatous meningitis.     

A comparative study of nitric oxide, glutathione, and glutathione peroxidase activities in cerebrospinal fluid from children with convulsive diseases/children with aseptic meningitis

It has been reported that active oxygen and/or free radicals are produced in the central nervous system (CNS) compartment in patients with bacterial meningitis, so it is supposed that the levels of endogenous antioxidative scavengers in the cerebrospinal fluid (CSF) are elevated as an adaptive reaction to bacterial meningitis, which exerts severe stress on the human body. We assumed that they are also elevated in patients with convulsive diseases. Nitric oxide (NO) and endogenous antioxidative scavengers (glutathione (GSH), glutathione peroxidase (GPX), (total) superoxide dismutase (T-SOD), manganese superoxide dismutase (Mn-SOD), and catalase) were measured in CSF from a group of child patients with various neurological diseases and a control group. NO, GSH, and GPX activities in CSF from the patients with convulsive diseases were significantly higher than in those with aseptic meningitis or in the controls. Furthermore, all parameters in CSF from patients with bacterial meningitis were significantly higher than in any other group. The present study suggests that oxidative stress may be associated with the pathophysiology of convulsion and that its clinical attenuation will lead to improvement in the prognosis for convulsive diseases.     

Clinical and immunological significance of neopterin measurement in cerebrospinal fluid in patients with febrile convulsions.

Neopterin is synthesized mainly by monocytes/macrophages and is considered to be a marker for activation of the cellular immune system. It has been reported that cerebrospinal fluid (CSF) neopterin levels are significantly higher in patients with bacterial meningitis than in those with aseptic meningitis or non-pleocytotic CSF. In this study levels of neopterin and interferon-gamma (IFN-gamma) were measured in children with non-pleocytotic CSF. The CSF neopterin levels were significantly higher in patients with typical febrile convulsions (FCs) (15.0 +/- 4.5 nmol/l) than in those with pyrexia without convulsions (6.5 +/- 2.7 nmol/l) or convulsions without pyrexia, namely, epilepsy (4.8 +/- 2.4 nmol/l). The CSF neopterin/serum neopterin ratio (C/S ratio) was also higher in patients with typical FCs (1.54 +/- 0.83) than in those with pyrexia without convulsions (0.32 +/- 0.18) or convulsions without pyrexia (0.77 +/- 0.28). Patients with prolonged FCs tended to have higher CSF neopterin levels than those with typical FCs. There was also a tendency for CSF IFN-gamma levels to be higher in patients with FCs than in those with pyrexia without convulsions or convulsions without pyrexia. The results of the present study suggest that some immune activation in the central nervous system (CNS) compartment may be related to the mechanisms of FCs.     

Human immunodeficiency virus type-1 Nef protein induces blood-brain barrier disruption in the rat: role of matrix metalloproteinase-9

We recently showed that MMP-9 activity was detectable in the cerebrospinal fluid (CSF) of about half of neurologically symptomatic HIV-infected patients. Using an experimental animal model, we detected MMP-9 activity in CSF samples from rats that had been injected intracisternally with recombinant HIV-1 Nef protein, but not after injection of heat-treated Nef, gp120, gp160 or PBS. Nef also induced a breaching of the blood-brain barrier (BBB), which could be inhibited by pretreatment with the matrix metalloproteinase (MMP) inhibitor batimastat. In vitro Nef only slightly induced MMP-9 activity in freshly isolated human peripheral blood mononuclear cells and in the murine macrophage cell line RAW 264.7, but not in endothelial, neuronal or astroglial cell lines. Taken together, our findings indicate that HIV-1 Nef protein can induce BBB disruption in the rat - presumably via MMP induction.     

NF-κB activation in cerebrospinal fluid cells from patients with meningitis

Abstract

We examined whether or not NF-κB, a factor that regulates expression of the genes that code for pro-inflammatory cytokines, is activated in cerebrospinal fluid (CSF) cells to investigate the production of pro-inflammatory cytokines by CSF cells in patients with meningitis. Western blotting demonstrated that NF-κB was more activated in CSF cells of patients with bacterial meningitis than in those of patients with aseptic meningitis. NF-κB was hardly activated in carcinomatous meningitis. The NF-κB activation in CSF cells of patients with meningitis tended to be correlated with the CSF interleukin-6 concentration. Our data suggested that CSF cells produce pro-inflammatory cytokines through NF-κB activation in meningitis, and that increased NF-κB activation in CSF cells indicate infectious meningitis rather than carcinomatous meningitis.     

The possible role of cerebrospinal fluid adenosine deaminase activity in the diagnosis of tuberculous meningitis in adults.

We studied an adenosine deaminase (ADA) activity in the cerebrospinal fluid (CSF) of 182 patients with meningitis. The patients were subdivided into four groups, (1) 36 cases of tuberculous meningitis; (2) 130 cases of viral or aseptic meningitis; (3) nine cases of bacterial meningitis; (4) seven cases of cryptococcal meningitis. Mean+/-S.D. ADA activity was 12.76+/-7.53 U/l in group 1; 2.58+/-2.37 U/l in group 2; 7.38+/-3.27 U/l in group 3; 7.42+/-4.38 U/l in group 4. Comparing the ADA activity in each group with the other groups, the difference is significant (P<0.001), except between groups 3 and 4. The sensitivity of the test for group 1 compared with group 2 was 0.83 and the specificity was 0.95 when a cut-off value of 7 U/l was used. When group 1 was compared with groups 3 and 4, the sensitivity was 0.58 and the specificity was 0.89 and 0.71 with groups 3 and 4, respectively, when a cut-off value of 10 U/l was used. Values >15 U/l were not observed in any of the non-tuberculous meningitis patients; therefore, ADA activity >15 U/l could be a strong indication of tuberculous meningitis. We conclude that a determination of CSF ADA can aid in the early differential diagnosis of tuberculous meningitis.     

Glutamic acid decarboxylase in cerebrospinal fluid in infancy and childhood Part II. Glutamic acid decarboxylase activity in cerebrospinal fluid of children with neurological diseases

Glutamic acid decarboxylase (GAD) activity in cerebrospinal fluid (CSF) was determined in 53 patients with neurological diseases as follows: Epilepsy (n:17), febrile convulsions (n:3), meningoencephalitis (n:17), encephalopathies (n:10), CNS leukemia (n:3), congenital hydrocephalus (n:2) and pseudoileus neonatorum (n:1). Compared with the mean normal value (5.2 +/- 2.5 pmol CO2 formed/hr/ml) reported in Part I, a significant increase of GAD activity in CSF was demonstrated in patients with uncontrolled epileptic seizures (11.4 +/- 3.9 pmol CO2 formed/hr/ml), febrile convulsions (13.5 +/- 8.7), viral meningitis with or without encephalitis (20.3 +/- 13.6), encephalopathies (30.0 +/- 25.9), CNS leukemia (11.1 +/- 5.0), congenital hydrocephalus (20.5 +/- 7.3) and pseudoileus neonatorum (28.6). Markedly high GAD activity was found in patients with CNS leukemia several days after intrathecal injection of methotrexate (39.8 +/- 18.0). On the other hand, significantly low GAD activity was shown in patients with bacterial meningitis or brain abscess (1.3 +/- 1.2). This suggests that some bacterial factors may be inhibitory toward GAD activity in CSF. High GAD activity in CSF may be useful as an indicator of aseptic brain dysfunction, although it was not always correlated with the severity of symptoms.     

Human alpha 1-microglobulin levels in neurological disorders

The concentration of alpha 1-microglobulin (alpha 1-m) in sera and cerebrospinal fluids (CSF) was measured in 121 patients with various neurological disorders. Using single radial immunodiffusion, its serum level was determined. No significant difference was found between the patients (29.1 +/- 4.3 mg/l; mean +/- 1 SD) and normal control group (23.7 +/- 4.6 mg/l). The level of CSF alpha 1-m was determined by the radioimmunoassay of solid antibody system. Its CSF level in the control group was 34.8 +/- 16.0 micrograms/l, while it was significantly increased in the patients with viral meningitis (p less than 0.01) and cerebral infarct (p less than 0.05). The level was also elevated in some cases of brain tumor, bacterial meningitis, cerebral hemorrhage, cervical spondylosis, and acute lymphocytic leukemia. There was a positive correlation between alpha 1-m and albumin levels in CSF. The analysis by CSF/serum albumin ratio and alpha 1-m ratio suggested that the increase of alpha 1-m in CSF could be explained mainly by an increase in permeability of the serum alpha 1-m through damaged blood brain barrier under these pathological conditions. Its local production within the central nervous system, however, could not be ruled out in these disorders.     

Vascular endothelial growth factor in CSF: a biological marker for carcinomatous meningitis

OBJECTIVE: To determine the value of vascular endothelial growth factor (VEGF) in CSF as a marker for carcinomatous meningitis (CM). METHODS: The concentration of VEGF was measured by ELISA in matched samples of CSF and serum collected from 162 patients. These included patients with solid tumors with CM (n = 11) or brain metastases without concomitant CM (n = 12), paraneoplastic neurologic syndromes (n = 4), viral (n = 15) and bacterial (n = 20) meningitis, and a variety of non-neoplastic and noninfectious neurologic diseases (n = 100). Using CSF/serum albumin ratios, the VEGF index was calculated to estimate the proportion of intrathecally produced VEGF. Immunohistochemical staining for VEGF was performed in a brain metastasis from a mammary carcinoma associated with CM. RESULTS: High VEGF levels (median 6,794.8 pg/mL) were found in CSF of all patients with CM, whereas VEGF levels in matched sera were comparable to other disease groups. In patients with CM, the concentration of VEGF in CSF decreased significantly following antineoplastic treatment. In CSF samples from patients with brain metastases without concomitant CM, VEGF was not detectable. Median VEGF concentration in CSF from patients with acute bacterial meningitis was 38.6 pg/mL, with only 9 of these 17 patients showing detectable VEGF levels in CSF. The VEGF indices in patients with bacterial meningitis were significantly lower than in tumor patients with CM (<22.8 versus >62.3), suggesting that the proportion of intrathecally produced VEGF is much higher in patients with CM as compared with patients with bacterial meningitis. Patients without neoplastic or infectious neurologic disorders consistently showed VEGF levels in CSF below the assay detection limit of 25 pg/mL. Immunohistochemistry revealed strong cytoplasmic staining for VEGF in a metastatic lesion from breast cancer infiltrating the meninges. CONCLUSION: In patients with carcinomatous meningitis, significant amounts of VEGF are released into CSF. This study yields preliminary evidence that VEGF in CSF may be a useful biologic marker for both the diagnosis and evaluation of treatment response in carcinomatous meningitis.     

Quantitation of lymphocyte subsets in cerebrospinal fluid and blood during the clinical course of aseptic and bacterial meningitis.

Mononuclear cell subsets in cerebrospinal fluid (CSF) and peripheral blood (PB) were monitored during the clinical course in 23 patients with acute meningitis using 6 monoclonal antibodies. Significant differences between aseptic and bacterial meningitis mainly consisted of a higher percentage of OKT4-positive cells in PB in the acute phase of bacterial meningitis. Significant differences between CSF and PB are found in the amount of most cell subtypes at all times except the acute phase of bacterial meningitis. The OKT4/OKT8 ratio was always significantly higher in CSF and correlated with the acuity of inflammation in bacterial meningitis.     

Value of second lumbar puncture in confirming a diagnosis of aseptic meningitis. A prospective study.

In patients with viral meningitis, polymorphonuclear leukocytes sometimes predominate in the CSF on initial examination. In a prospective analysis of this phenomenon, 16 consecutive patients with viral meningitis were followed up with serial CSF studies. The percentage of polymorphonuclear leukocytes showed a significant fall between initial and second examinations (41.75 +/- 27.0 to 8.6 +/- 8.78 [mean +/- 2 SD], P less than .001), while total WBC counts and the protein and sugar content levels remained unchanged. Based mainly upon this "polymorph shift," antibiotic therapy was correctly withheld from 100% of patients reexamined. On subsequent examinations, the percentage of polymorphonuclear cells remained low. All patients recovered completely without any specific treatment. In otherwise healthy subjects with the aseptic meningitis syndrome, antibiotic therapy can be withheld even when polymorphonuclear cells predominate on initial CSF examination. If suspicion arises regarding the diagnosis, another examination will demonstrate a significant fall in polymorphonuclear cells if the initial impression was correct.     

巨噬细胞和粒细胞集落刺激因子在细菌性脑膜炎患者脑脊液中呈增高趋势

检测了24例细菌性脑膜炎(BM)，20例多发性硬化症(MS)和20例肌紧张性头痛(TH)患者的脑脊液(CSF)巨噬细胞集落刺激因子(M-CSF)及粒细胞集落刺激因子(G-CSF)。24例BM患者中19例检出M-CSF，含量为60～5600／ml；16例检出G-CSF，含量为40～1200／ml。20例MS组和20例TH组均未检出。BM患者CSF中M-CSF和G-CSF呈增高趋势。鉴于这两种细胞集落刺激因子可促使活性单拔细胞、纤堆细胞和内皮细胞产生某些细胞因子，从而增强机休抵抗细菌感染的能力，提示M-CSF和G-CSF在中枢神经系统感染性疾病中可能起到重要的免疫调节作用。