Increased CSF Levels of Apolipoproteins and Complement Factors in Trigeminal Neuralgia Patients-In Depth Proteomic Analysis Using Mass Spectrometry

The main cause of trigeminal neuralgia (TN) is compression of a blood vessel at the root entry zone of the trigeminal nerve. However, a neurovascular conflict does not seem to be the only etiology and other mechanisms are implicated in the development of the disease. We hypothesized that TN patients may have distinct protein expression in the CSF. In this study, lumbar CSF from TN patients (n = 17), scheduled to undergo microvascular decompression, and from controls (n = 20) was analyzed and compared with in depth mass spectrometry TMTbased quantitative proteomics. We identified 2552 unique proteins, of which 46 were significantly altered (26 increased, and 20 decreased, q-value < .05) in TN patients compared with controls. An over-representation analysis showed proteins involved in high-density lipoprotein, such as Apolipoprotein A4, Apolipoprotein M, and Apolipoprotein A1, and the extracellular region, including proteins involved in the complement cascade to be over-represented. We conclude that TN patients have distinct protein expression in the CSF compared to controls. The pathophysiological background of the protein alterations found in this study warrants further investigation in future studies. PERSPECTIVE: In this article, cerebrospinal fluid from patients with trigeminal neuralgia was analyzed using in depth shotgun proteomics, revealing 46 differentially expressed proteins compared to controls. Among these, apolipoproteins and proteins involved in the complement system were elevated and significantly over-represented, implying an inflammatory component in the pathophysiology of the disease.

Cerebrospinal Fluid IgM Index Correlates with Cranial MRI Lesion Load in Patients with Multiple Sclerosis

In multiple sclerosis intrathecal IgM synthesis correlates with an unfavourable disease course. Whether this reflects a pathogenic role of IgM, possibly in conjunction with complement, is a matter of debate. In a cross-sectional study we measured intrathecal synthesis of IgM and the complement component C3, and on cranial MRI lesion load and central brain atrophy in clinically active patients, 17 relapsing-remitting, 16 secondary progressive. Correlative analysis showed that in relapsing-remitting patients CSF IgM index correlated with cranial MRI T2 and T1 lesion load, and central brain atrophy; and the C3 index correlated with T2 lesion load. In secondary progressive patients CSF IgM index correlated with periventricular T2 lesion load. Our data are in favour of a pathogenic role of IgM in multiple sclerosis.

Complement protein isoforms in CSF as possible biomarkers for neurodegenerative disease

It has been suggested that the activation of the complement system is involved in the pathogenesis of several neurodegenerative diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), and multiple sclerosis (MS). Here, the CSF expression levels of complement proteins C3b, C4b, factor B, and factor H were compared between normal subjects and patients diagnosed with AD, PD, MS, and neurosyphilis. The CSF proteins were initially separated using two-dimensional gel electrophoresis, which allowed the comparison of some of the individual complement isoforms. Patients with AD, PD, and MS all showed more than one complement isoform with a significant change (p < 0.05) in CSF expression level compared to normal subjects. PD patients were found to have the greatest number of significantly changed isoforms, all showing a decreased expression level in PD CSF. The complement isoforms examined were able to distinguish between some, but not all, of the diseases studied. The data suggest that when investigating a protein as a possible biomarker, it may be useful to compare individual protein isoform expression levels in addition to the more commonly measured total protein expression level.

Intrathecal levels of complement-derived soluble membrane attack complex (sC5b-9) correlate with blood-brain barrier dysfunction in patients with traumatic brain injury

It has become evident in recent years that intracranial inflammation after traumatic brain injury (TBI) is, at least in part, mediated by activation of the complement system. However, most conclusions have been drawn from experimental studies, and the intrathecal activation of the complement cascade after TBI has not yet been demonstrated in humans. In the present study, we analyzed the levels of the soluble terminal complement complex sC5b-9 by ELISA in ventricular cerebrospinal fluid (CSF) of patients with severe TBI (n = 11) for up to 10 days after trauma. The mean sC5b-9 levels in CSF were significantly elevated in 10 of 11 TBI patients compared to control CSF from subjects without trauma or inflammatory neurological disease (n = 12; p < 0.001). In some patients, the maximal sC5b-9 concentrations were up to 1,800-fold higher than in control CSF. The analysis of the extent of posttraumatic blood-brain barrier (BBB) dysfunction, as determined by CSF/serum albumin quotient (Q(A)), revealed that patients with a moderate to severe BBB impairment (mean Q(A) > 0.01) had significantly higher intrathecal sC5b-9 levels as compared to patients with normal BBB function (mean Q(A) < 0.007; p < 0.0001). In addition, a significant correlation between the individual daily Q(A) values and the corresponding sC5b-9 CSF levels was detected in 8 of 11 patients (r = 0.72-0.998; p < 0.05). These data demonstrate for the first time that terminal pathway complement activation occurs after head injury and suggest a possible pathophysiological role of complement with regard to posttraumatic BBB dysfunction.

[Cerebrospinal fluid complement and antinuclear antibodies in lupus meningoencephalitis]

Central nervous system involvement in systemic lupus erythematosus (SLE) requires immediate treatment. We report a case in a 30-year-old woman. Clinical features associated asthenia, headache, right nystagmus and coma. A mechanical ventilation was started. The neurologic pattern appeared three months after an initial treatment with pulsed doses of glucocorticoid (500 mg per day for 3 days) and one month after an oral cyclophosphamid regimen (50 mg twice a week). The cerebral involvement was evidenced by MRI and comparative analysis of the antinuclear auto antibodies (ANA) and the complement components in cerebral spinal fluid (CSF), pleural fluid and serum. The MRI slices showed a well-defined meningeal focal lesion. CSF-cell count was normal. CSF-proteins were elevated. ANA were positive, total complement (UI/l) was low, C4 component (g/l) was 0.11, undetectable and 0.25 respectively in plasma, CSF fluid and pleural fluid. The ANA specific pattern was anti-Sm2. We affirmed that specific cerebral injury was present because there were clinical and imaging features and a decrease of the C3 and C4 component in the CSF. The treatment associated in travenous pulsed doses of methylprednisolone (1000 mg per days for 3 days) and cyclophosphamid (500 mg per day for three days). Mechanical ventilation was with drawn one day after the end of the pulse therapy. The diminution of the complement component could help improving cerebral involvement of SLE. More clinical studies are required.

Cerebrospinal fluid complement activation in neurological diseases

Laser nephelometry (LN) is a rapid and very sensitive method for simultaneous determination of albumin, immunoglobulins, C3c and C4 in diluted serum and paired cerebrospinal fluid (CSF) samples. It is very useful in routine analyses. Determination of C3c and C4 covers classical as well as alternative pathways of complement activation. In CSF, they are mostly derived from and related to serum values. Under physiological conditions, the addition of intrathecal C4 synthesis is likely. The incidence of complement activation within CSF is also influenced by the method of choice (native molecules, activation products and complexes, inhibitors) and the mode of interpretation of results according to the functional state of the blood-brain barrier (BBB). Calculation of indexes and the modified Reiber's graph method are valid means of detection of complement activation within CSF. Complement activation within CSF was confirmed in 36% (111/302) of neurological patients examined; in 55% (48/87) of patients with inflammatory and demyelinating diseases, in 40% (37/94) of patients with CNS infections and complications, in 33% (4/12) of patients with motor neuron diseases, in 27% (11/40) of patients with spinal cord compression and sequelae, in 25% (8/32) of patients with neoplastic disease, and in 17% (6/37) of patients with cerebrovascular accidents.

Cerebrospinal fluid analysis differentiates between relapsing-remitting and secondary progressive multiple sclerosis

OBJECTIVES

To find whether CSF analysis may differentiate between relapsing-remitting and secondary progressive multiple sclerosis.

METHODS

In 17 patients with relapsing-remitting and 16 patients with secondary progressive multiple sclerosis, all without current or recent relapses, albumin CSF: peripheral blood ratio, mononuclear cell number, CD4+, CD8+, and B1+ subsets, CD4+:CD8+ ratio, IgG, IgG index, IgM, IgM index, complement components C3 and C4, and C3 and C4 indices, myelin basic protein, neuron specific enolase, S100, and lactate were determined. For each measure the statistical distance measure D2 was calculated. For computation of a discriminant score variables with a P value< or =0.15 were included (two sided univariate t test). These were albumin CSF: peripheral blood ratio, mononuclear cell number, IgM, IgM index, C3, C4, neuron specific enolase, S100, and lactate. Simultaneous distributions of the variables were compared between both groups (multivariate t test) and a discriminant score was computed (linear discriminant analysis).

RESULTS

The discriminant score allocated all 14 relapsing-remitting patients to the relapsing-remitting group (positive score) and 12 of 13 secondary progressive patients to the secondary progressive group (negative score). One secondary progressive patient was allocated to the relapsing-remitting group.

CONCLUSIONS

Patients with relapsing-remitting or secondary progressive multiple sclerosis differ in CSF profile and CSF analysis may help to differentiate between relapsing-remitting and secondary progressive multiple sclerosis.

Cerebrospinal fluid C3a increases with age, but does not increase further in Alzheimer's disease

Complement activation is present in the brain in Alzheimer's disease (AD), and C1q concentrations are decreased in AD cerebrospinal fluid (CSF). To determine whether concentrations of other complement proteins are also altered in AD CSF, we measured concentrations of C3a and SC5b-9 in CSF from patients with probable AD (n = 19), normal aged controls (n = 11), and normal younger controls (n = 15). C3a concentrations were similar between AD and aged controls, but threefold higher than in younger controls (p < 0.05 vs. both groups). A similar pattern was found with SC5b-9, though the increase was only twofold and statistically significant only for AD vs. younger controls. These results suggest that an increased generation of complement proteins in localized areas of the AD brain does not result in elevated concentrations of these proteins in CSF, compared with age-matched controls. Increased C3a (and, to a lesser extent, SC5b-9) in aged controls may be due to increased complement activation, increased central nervous system production, and/or blood-brain barrier leakage of these proteins.

Humoral and cellular immunologic study of cerebrospinal fluid in a patient with Behçet encephalitis

To study the immunopathogenesis of neuro-Behçet syndrome, we performed serial cerebrospinal fluid (CSF) examinations in a patient with Behçet's syndrome and involvement of the central nervous system. Before and after immunosuppressive treatment, we measured the CSF indexes of immunoglobulins (Ig), and the third (C3) and the fourth (C4) component of complement, and quantified immune complexes and lymphocyte subsets in CSF and peripheral blood. During active encephalitis, humoral abnormalities were intrathecal production of IgM and, to a lesser degree, IgG and IgA, presence of immune complexes in CSF but not in peripheral blood, intrathecal C3 production, and elevated CSF C3 and C4 concentrations; lymphocyte subset analysis showed an increased CSF CD8+ T-cell percentage, in combination with slightly increased PB CD3+ and CD8+ T-cell subsets. After effective immunosuppressive treatment, humoral and cellular CSF values were normal. We conclude that intrathecally produced immunoglobulins, immune complexes, and C3 as well as CD8+ T cells are likely to participate in the development of Behçet encephalitis.

Serum and CSF humoral immunity in Guillain-Barré syndrome: clinical correlations

Paired samples of CSF and serum obtained from 29 patients affected with Guillain-Barré syndrome (GBS) were analyzed for various protein levels, including immunoglobulins and complement components. An attempt was made to correlate these findings to the clinical stage, severity, and duration of the disease. Intrathecal IgG synthesis was detected and quantified by means of a previously reported formula. It is practically constant in the GBS during the stage of stabilized paralysis, and is significantly greater in this stage than in the stage of progressive paralysis. Moreover, it increases with severity and duration (longer than 3 months) of the disease. Evidence of intrathecal C3 consumption is also presented.

Detection of activated terminal complement (C5b-9) in cerebrospinal fluid from patients with central nervous system involvement of primary Sjogren's syndrome or systemic lupus erythematosus

We have examined cerebrospinal fluid (CSF) and serum from patients with Sjogren's syndrome (SS) and systemic lupus erythematosus (SLE) for evidence of activation of the terminal pathway of complement. Fluid phase terminal complement complexes (SC5b-9), quantitated by ELISA, were detected in the CSF of 14 of 16 patients with SS and focal central nervous system (CNS) disease. Five of six SS patients without focal CNS disease but with psychiatric disease or cognitive dysfunction had detectable CSF SC5b-9, whereas two other SS patients without focal CNS or neuropsychiatric disease had no detectable CSF SC5b-9. Six of seven patients with SLE or SLE overlap syndrome with CNS involvement had CSF SC5b-9, whereas two patients with SLE without CNS involvement had no CSF SC5b-9. A subset of SS and SLE patients with CNS disease had SC5b-9 detected in CSF but not in serum. SC5b-9 was generally absent from the CSF of patients with noninflammatory CNS diseases. These findings demonstrate intrathecal activation of terminal complement in patients with CNS SS or CNS SLE, and suggest a role for terminal complement activation in the pathophysiology of CNS involvement in both SS and SLE.

Intrathecal complement activation in neurological diseases evaluated by analysis of the terminal complement complex

The terminal complement complex (TCC) was determined in plasma and cerebrospinal fluid (CSF) from 208 neurological patients. Elevated CSF TCC levels were observed in higher frequencies in patients with infectious diseases (80%), radiculoneuritis (62%), multiple sclerosis (30%), and miscellaneous autoimmune diseases (27%) than in patients with miscellaneous non-inflammatory diseases (2-13%). The plasma level of TCC was significantly increased only in the infectious group. No positive correlation was observed between the plasma and the CSF TCC concentration in the whole patient population nor in subgroups divided according to blood-brain barrier function. Furthermore, the CSF TCC concentration did not correlate with the serum/CSF albumin ratio or with CSF total protein concentration when this was below 1.0 g/l. It is concluded that an elevated TCC concentration in CSF reflects intrathecal complement activation and that quantification of TCC in CSF may be a valuable supplement in the examination of neurological diseases.

Activated terminal complement in cerebrospinal fluid in Guillain-Barré syndrome and multiple sclerosis

A quantitative enzyme-linked immunosorbent assay was used to measure the concentration of fluid-phase complement C5b-9 complexes (SC5b-9) in the cerebrospinal fluid (CSF) of 14 patients with acute monophasic Guillain-Barré Syndrome (GBS), 21 patients with multiple sclerosis (MS), and 11 patients with noninflammatory central nervous system (CNS) diseases. SC5b-9 complexes were detected in the CSF of 13 of 14 patients with acute GBS (mean, 3.08 micrograms/ml; range, 0 to 7.1 micrograms/ml) and 16 of 21 patients with MS (mean, 1.83 micrograms/ml; range, 0 to 7.5 micrograms/ml). In the control group of patients with noninflammatory CNS diseases, SC5b-9 was not detected in eight of 11 and was present in low concentrations in the remaining three patients (mean, 0.28 micrograms/ml; range, 0 to 1.7 micrograms/ml). The finding of SC5b-9 complexes in the CSF of patients with GBS and MS suggests that terminal complement components may participate in the tissue-damaging processes in these diseases.

The role of complement in inflammation during experimental pneumococcal meningitis

The mechanism whereby an effective bactericidal inflammatory reaction develops in the subarachnoid space is not clearly defined. While normal cerebrospinal fluid is deficient in complement, immunoglobulin and leukocytes, these serum components appear in cerebrospinal fluid (CSF) during the course of bacterial meningitis. Using a rabbit model of pneumococcal meningitis we examined the role of the alternate complement pathway in three early events important to the defense of the subarachnoid space: leukocyte chemotaxis, phagocyte mediated bacterial killing, and clearance of bacterial components from the cerebrospinal fluid space. Rabbits treated with cobra venom factor to deplete complement were inoculated intracisternally with encapsulated (type II or XIX) pneumococci. Following complement depletion, there was a dramatic (at least 100-fold) decrease in the LD50 for these strains. Nevertheless, complement depletion did not affect the magnitude of CSF leucocytosis or the rate of clearance of bacterial particles from CSF. A short delay in the appearance of leukocytes in CSF was found in the absence of complement. The major effect of complement depletion, however, was to diminish the efficiency of leukocyte mediated killing of encapsulated bacteria in the CSF. Although the short delay in the onset of leukocytosis in the complement depleted animals is consistent with a chemotactic role of complement in the normal animal, the quantitatively normal leukocytosis in the complement depleted rabbits clearly indicates that important chemotaxins other than complement function in CSF. Inhibition of leukocytosis by indomethacin and diclofenac suggests that metabolite(s) of the arachidonic acid pathway may perform such a chemotactic role. A major role of complement in the defense of the subarachnoid space appears to be as an opsonin needed for the effective bactericidal activity of leukocytes. It is the lack of this function that best explains the greatly decreased LD50 value of encapsulated pneumococci in the complement depleted animal.

[Immunologic study of cerebrospinal fluid in the diagnosis of posttraumatic meningitis]

Immunological examination of the cerebrospinal fluid (CSF) in 280 patients in the acute period of craniocerebral trauma demonstrated an increase in the beta-lysin content and lysozyme concentration in it when meningitis developed. Increase in the CSF beta lytic and lysozyme activity reflects the severity of the inflammatory process. Tests for these factors in the CSF may be used in the early diagnosis of post-traumatic meningitis.

Complement-mediated opsonic activity in normal and infected human cerebrospinal fluid: early response during bacterial meningitis

A local defense mechanism in bacterial meningitis was evaluated in humans by measuring complement-mediated opsonic activity (CMOA) in normal and infected cerebrospinal fluid (CSF) with a complement-dependent phagocytic bactericidal assay. CMOA was absent in normal untreated CSF and remained undetectable in 20 samples of CSF from patients with viral meningitis and five samples from patients with acute meningococcemia. In contrast, 15 of 27 samples of CSF from patients with acute bacterial meningitis had a measurable CMOA, which was correlated with protein concentrations (P less than 0.01) and C4 hemolytic activity (P less than 0.001) in the CSF. A favorable outcome of bacterial meningitis was associated with the presence of CMOA in CSF (P less than 0.005). Recovery was also correlated with higher levels of C4 (P less than 0.01) and C3 (P less than 0.05) in CSF and with lower concentrations of microorganisms in the sample of CSF collected at the time of admission (P less than 0.01). Thus, CMOA, although absent in normal CSF, can appear in CSF during acute bacterial meningitis, particularly in patients who recover completely.

Immunologic tests of value in diagnosis. 2. Complement

Laboratory tests are available to assess the function of the complement pathway and to measure levels of individual complement components. The pattern of complement abnormalities is often helpful in suggesting diagnostic possibilities. For example, when when total hemolytic complement, C3, and C4 are all decreased, one of the rheumatoid diseases is likely. In addition, complement levels in spinal and synovial fluid may provide helpful diagnostic clues.

Cerebrospinal fluid and serum immunoglobulins and antibody titers in mumps meningitis and aseptic meningitis of other etiology

Cerebrospinal fluid (CSF) and serum from 19 patients with mumps meningitis and 19 patients with meningitis of other etiology were investigated on two or more occasions for at least 1 month after onset. Intrathecal synthesis of immunoglobulin (Ig) G was found in 55%, of IgA in 26%, and of IgM in 24% of the patients. Oligoclonal Ig was demonstrable by agarose gel electrophoresis in 37% of the patients, mostly already during the first week after onset, and could persist for years. Mumps virus antibody synthesis within the central nervous system occurred in 37% of the mumps meningitis patients. The inflammatory reaction within the central nervous system as reflected by mononuclear pleocytosis, Ig synthesis, and oligoclonal Ig was not correlated to the clinical course. The blood-brain barrier was evaluated by determination of the CSF total protein, CSF/serum albumin ratio, and CSF/serum alpha2-macroglobulin ratio. A significant correlation was found among these three parameters. Persistence of the elevated CSF/serum albumin ratio seems to influence prognosis, and this parameter is recommended for evaluation of the blood-brain barrier function.

[Demonstration of total complement in normal cerebrospinal fluid]

Até o presente momento, todos os autores afirmam que o líquido cefalorraqueano (LCR) normal do homem não apresenta atividade hemolítica do complemento total. Alguns pesquisadores verificaram, entretanto, a presença de todos os quatro componentes em muitas amostras de LCR normal sem conseguir, porém, demonstrar a atividade hemolítica do complemento total. Este fato parecia indicar que o LCR normal era desprovido da atividade hemolítica do complemento total provavelmente por motivo da concentração insuficiente de suas proteínas. Para investigar esta hipótese foi feita uma prova preliminar, concentrando 10 amostras de LCR normal, dividindo-se o concentrado em duas partes, uma das quais foi inativada à temperatura de 56°C, durante 20 minutos. Esta prova revelou hemólise das hemácias sensibilizadas somente em relação com o LCR concentrado ativo. Em prosseguimento foram feitas pesquisas em 108 amostras de LCR normal obtidas por punção cisternal, selecionadas de pacientes sem doença de ordem geral, porém com perturbações neurológicas ou psíquicas que, em geral, não costumam determinar alterações do LCR. As amostras de LCR foram concentradas vinte vezes o seu volume, pelo método da diálise sob pressão negativa em camisa de colódio, segundo o processo de Mies. Esta pesquisa proporcionou resultados que permitiram concluir que o líquido cefalorraqueano normal concentrado apresenta atividade hemolítica do complemento total em 98% dos casos. O título do complemento total variou de 0 a 23 unidades de hemólise 50% em 1 ml de líquido concentrado.

Neutrophil chemotaxis in cerebral astrocytoma

Neutrophil chemotaxis was evaluated for five patients with a primary intracerebral malignancy. All patients had intratumor cysts and these fluids with corresponding serum and cerebrospinal fluid were tested for their chemotactic ability. The ability of cyst fluid to effect neutrophil chemotaxis was diminished in comparison to serum from either patients or control population. Cyst fluids had lower complement levels than serum and did not have a humoral chemotactic inhibitor. The neutrophils for both the patient and control groups had similar chemotaxis to a given chemotactic stimulus suggesting that this malignancy does not have an accompanying peripheral blood phagocytic cell chemotactic defect. Chemotaxis, the migration of phagocytic cells, is a fundamental requisite for the inflammatory and the immune response.

Recent observations on central nervous system lupus erythematosus

The recent literature on CNS-SLE has been reviewed. An improved prognosis is noted that is thought to be due to the use of high-dose corticosteroids. The frequencies of the various neurologic and psychiatric findings are discussed, and a distinction is noted between organic psychoses and functional psychiatric complaints. The question of corticosteroids versus cerebral vasculitis as the cause of the neuropsychiatric symptomatology in SLE is examined, and the necessity of clear psychiatric diagnosis and treatment is stressed. Recent observations on HL-A antigens, complement, immunoglobulins, virus, and immunocomplexes suggest that the latter are prominent in CNS-SLE, but that an infectious agent may be etiologic in the genesis of SLE. Fifty-four patients not previously reported are discussed. Thirty-eight of them had neuropsychiatric manifestations. The treatment of CNS-SLE with cytotoxic agents, in addition to corticosteroids, is considered, and the experience of the authors with such treatment is presented.