Infection-associated encephalopathies: their investigation, diagnosis, and treatment.

Reduced level of consciousness is a common clinical finding in acutely sick patients. In the majority of cases a cause for the encephalopathy is readily identifiable,whilst in a minority the aetiology is more difficult to ascertain. Frequently the onset of encephalopathy is associated with, or follows, infection. The mechanisms through which infection leads to encephalopathy are diverse. They range from direct microbial invasion of the brain or its supporting structures, to remote, infection-triggered mechanisms such as acute disseminated encephalomyelitis. Most common however, is the encephalopathy caused through a remote effect of systemic sepsis-septic encephalopathy. This article discusses the clinical presentation and underlying pathogeneses of the acute encephalopathies associated with infection, aiming to aid both their recognition and treatment.

Importance of intrathecal synthesis of IgD in multiple sclerosis. A combined clinical, immunologic, and magnetic resonance imaging study.

There is increasing evidence that soluble IgD has a certain role in the humoral immune response within the central nervous system. We report herein the results of a combined clinical, magnetic resonance imaging, and immunopathologic study to determine the clinical importance of intrathecal IgD synthesis. Intrathecal synthesis of IgD (detected through the calculation of index values) was studied in 64 patients with multiple sclerosis and in 50 neurologic control patients and normal subjects. Locally secreted IgD was detected in 30% of patients with clinically active multiple sclerosis, including two in whom magnetic resonance images of brain and spinal cord were normal and who had no evidence of intrathecal IgG synthesis. No intrathecal IgD production was detected in patients with clinically stable multiple sclerosis or those suffering from chronic progressive multiple sclerosis, while it significantly correlated with the interval from the last relapse and with the total duration of the disease process in patients with relapsing, remitting multiple sclerosis. Intrathecal IgD synthesis also correlated with the degree of cerebrospinal fluid pleocytosis and with the presence of free kappa and lambda light chain bands in cerebrospinal fluid. Present results supplement and expand earlier data and suggest that intrathecally secreted IgD is a putatively important part of the immune response in clinically active relapsing, remitting multiple sclerosis.

Significance of CSF immunoglobulins in monitoring neurologic disease activity in Behçet's disease.

We examined the intrathecal production of immunoglobulins (Ig) G, A, and M in 16 patients with Behçet's disease, 13 of whom have CNS involvement, and in 40 neurologic controls. Oligoclonal IgA and IgM bands were mainly detected in CSF samples from patients with active neuro-Behçet's disease and were documented to disappear when neurologic manifestations remit. Oligoclonal IgG bands, however, were not related to disease activity and were also found in some neurologic controls. High immunoglobulin index values were detected in both active and quiescent diseases and were high in some patients with impaired blood-CSF barriers. The study presented here demonstrates that CSF oligoclonal IgA and IgM may be helpful in monitoring CNS disease activity in neuro-Behçet's and could be useful in understanding the pathogenesis of this disease.

I.v. immunoglobulin reduces circulating proinflammatory cytokines in Guillain-Barré syndrome.

BACKGROUND: Treatment with human i.v. immunoglobulin (IVIg) modifies the course of Guillain-Barré syndrome (GBS), but its specific mode of action is unknown. Cellular interactions mediated through the release of cytokines play a role in the pathogenesis of GBS and may be regulated by IVIg therapy. OBJECTIVE: To delineate possible immunoregulatory mechanisms of IVIg in patients with GBS. METHODS: Circulating levels of the proinflammatory cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, were assayed in 21 patients with GBS before and serially after IVIg therapy. Comparisons were made with serum concentration of the anti-inflammatory cytokines, soluble TNF-alpha receptor and IL-10. Serial measurements were also performed in 12 untreated patients with relatively mild disease and 7 patients treated by plasma exchange. RESULTS: Circulating levels of TNF-alpha and IL-1beta decreased after treatment with IVIg but remained relatively high in untreated patients and in those treated by plasma exchange. Clinical improvement in patients treated with IVIg was associated with a reduction in unbound TNF-alpha during the acute phase of the illness. Circulating levels of anti-inflammatory cytokines were not affected by IVIg treatment. CONCLUSION: Data presented here suggest a novel mechanism of action of IVIg that involves selective modulation of circulating proinflammatory cytokines.

Patients with progressive multiple sclerosis have elevated antibodies to neurofilament subunit.

OBJECTIVE: The cause of axonal loss, an important contributor to disability in MS, is poorly understood. This study investigated whether progression in MS is associated with CSF antibodies to the 68-kd light neurofilament subunit (NF-L), an axonal cytoskeletal protein, and compared this with antibodies against tubulin and the heavy neurofilament subunit (NF-H). METHODS: IgG to NF-L, tubulin, and NF-H was measured by immunoassay in matched CSF and serum samples from patients with relapsing-remitting MS (RRMS; n = 39), primary progressive MS (PPMS; n = 10), and secondary progressive MS (SPMS; n = 18); patients with other inflammatory (n = 21) and noninflammatory (n = 40) neurologic diseases; and healthy controls (n = 12). Immunocytochemistry was performed to assess antibody binding to human brain sections, and isoelectric focusing with immunoblotting was performed to assess oligoclonal anti-NF-L production. RESULTS: Intrathecal production of anti-NF-L antibodies was significantly elevated in PPMS and SPMS. In contrast, there were no significant differences in CSF levels of antibodies to tubulin or NF-H between the groups. Anti-NF-L, antitubulin, and anti-NF-H levels correlated with the duration of disease before lumbar puncture and Expanded Disability Status Scale levels. Immunocytochemistry demonstrated binding of CSF or serum antibodies to axonal or neuronal components in six of seven RRMS patients, seven of seven PPMS patients, and eight of 10 SPMS patients tested. Isoelectric focusing demonstrated independent CSF oligoclonal bands reactive with NF-L in six of 13 specimens tested. CONCLUSIONS: Anti-NF-L antibodies seem to be raised in progressive MS and may serve as a marker for axonal loss and disease progression. They may contribute to axonal loss and the accumulation of disability.

Heightened intrathecal release of proinflammatory cytokines in Creutzfeldt-Jakob disease.

The authors report high intrathecal release of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta in five patients with sporadic or new-variant Creutzfeldt-Jakob disease (CJD) without activation of the humoral or lymphocytic immune responses. Increased release of TNF-alpha and IL-1beta was also detected in some patients with progressive dementias. CJD is associated with a local cerebral host response that involves the release of proinflammatory cytokines.

Neurophysiologic analysis of neuromuscular symptoms in UK Gulf War veterans: a controlled study.

BACKGROUND: UK veterans who were deployed to the Gulf in 1990 to 1991 reported higher prevalence of neuromuscular symptoms. OBJECTIVE: To investigate whether these Gulf War-related symptoms were associated with objective evidence of neuromuscular dysfunction. METHODS: Forty-nine Gulf War veterans with more than four neuromuscular symptoms (Gulf-ill), 26 Gulf-well veterans, 13 symptomatic Bosnian veterans (Bosnia-ill), and 22 symptomatic veterans who were not deployed to the Gulf (Era-ill) underwent detailed neurophysiologic assessment: nerve conduction studies, quantitative sensory and autonomic testing, and concentric needle and single-fiber electromyography (EMG). RESULTS: Nerve conduction studies detected carpal tunnel syndrome in two Gulf-ill, two Gulf-well, one Bosnia-ill, and three Era-ill veterans. Ulnar neuropathy was detected in one Gulf-ill and two Era-ill veterans. However, results of detailed nerve conduction studies of the Gulf-ill veterans were comparable with results observed in the other three groups. Quantitative sensory and autonomic assessments also failed to show any specific abnormalities in the Gulf-ill group. Similarly, quantitative assessment of concentric needle and single-fiber EMG detected no chronic denervation or myopathic changes or any abnormalities of neuromuscular transmission in the Gulf-ill veterans. CONCLUSION: Gulf War-related neuromuscular symptoms are not associated with specific impairments of peripheral nerves, neuromuscular junctions, or skeletal muscles.

A sensitive ELISA system for the rapid detection of virus specific IgM antibodies in the cerebrospinal fluid.

The intrathecal production of IgM antibodies to different viral antigens was measured by a modification of ELISA that was both sensitive and specific. Suitably diluted CSF and homologous serum samples containing similar amount of IgM were examined, and a comparison of the photometric signals permitted the detection of specific antibodies secreted from activated lymphocytes into the CSF compartment during the course of viral infections of the central nervous system. Polyvinyl chloride (PVC) microtitre plates were activated by glutaraldehyde and then coated with different viral antigens. Test samples were incubated on these solid-phase antigens and virus-specific IgM antibodies were detected using a peroxidase-conjugated F (ab')2 fragment of anti-human IgM antibody to avoid interference from rheumatoid factors.

Determination of interleukin-2 in cerebrospinal fluid by a sensitive enzyme-linked immunosorbent assay.

A sensitive technique was developed for the quantitative detection of intrathecal production of interleukin-2 (IL-2). Concentrations of IL-2 in paired cerebrospinal fluid (CSF) and serum samples were measured by an enzyme-linked immunosorbent assay using a monoclonal antibody and an affinity purified polyclonal antibody. The assay produced a linear response with respect to IL-2 concentration, and could readily detect levels of IL-2 as low as 1.5 international units/ml. Concentrations of IL-2 in CSF and serum samples were standardised by calculating their ratio to albumin concentration in order to correct for passive transudation of IL-2 across blood-CSF barriers. CSF IL-2/albumin ratios higher than concomitant serum ratios were considered indicative of intrathecal IL-2 production. The technique provides a sensitive, specific, and reproducible method for the determination of in vivo synthesis of IL-2 within the central nervous system.

Hypokalaemic myopathy in alcoholism.

We describe the clinical and pathological features of a patient with an acute painless proximal myopathy due to hypokalaemia associated with alcoholism. There was an excellent response to treatment with potassium supplements. The importance of recognition of low potassium states in alcohol-dependent patients with muscular weakness is emphasized.

Increased cellular expression of the caspase inhibitor FLIP in intrathecal lymphocytes from patients with multiple sclerosis.

Failure of Fas-mediated apoptosis of potentially pathogenic, autoreactive T lymphocytes may be involved in the pathogenesis of multiple sclerosis. The intracellular protein FLIP, a naturally occurring caspase-antagonist, is a potent inhibitor of the Fas signalling pathway that may block Fas-mediated apoptosis of activated lymphocytes. This study reports specific overexpression of both long and short forms of FLIP in intrathecal lymphocytes from patients with multiple sclerosis. The overexpression of FLIP is independent of cellular expressions of Fas receptor or the anti-apoptotic protein Bcl-2. These results provide a better understanding of some of the intrinsic immunoregulatory mechanisms that are involved in multiple sclerosis.

Impaired Fas-independent apoptosis of T lymphocytes in patients with multiple sclerosis.

The homeostasis of the immune system is maintained by apoptotic (programmed cell death) elimination of potentially pathogenic, autoreactive mononuclear cells. There is emerging evidence that apoptosis mediated by the cell death receptor Fas is impaired in activated lymphocytes from patients with multiple sclerosis (MS), but other forms of apoptosis have not yet been fully evaluated. To further explore the dynamics of programmed cell death in MS, spontaneous and induced apoptosis of both peripheral and intrathecal mononuclear cells was investigated in clinically active MS patients and appropriate controls. In the MS group, spontaneous apoptosis of unfractionated mononuclear cells was significantly reduced, and activated intrathecal and peripheral T cells were found to be predominantly resistant to Fas-independent apoptosis. These results indicate that in clinically active MS, the reduced susceptibility of mononuclear cells to apoptosis is partly due to impairment of Fas-independent apoptotic pathways.

In vivo relationship of tumor necrosis factor-alpha to blood-brain barrier damage in patients with active multiple sclerosis.

Tumor necrosis factor-alpha (TNF-alpha) has well recognized effects on cerebral endothelial cells and, therefore, may mediate disruption of blood-brain barrier in patients with multiple sclerosis (MS). To evaluate the in vivo relationship of TNF-alpha to blood-brain barrier impairment in MS, levels of this cytokine in cerebrospinal fluid (CSF) and serum samples from 38 patients with active MS and 48 controls were correlated with CSF to serum albumin ratios. TNF-alpha was detected in the serum of 74% and the CSF of 66% of patients with active MS. CSF levels of TNF-alpha were significantly higher in active MS compared to stable MS or other controls, and were significantly higher than corresponding serum levels. In patients with active MS, only those with detectable TNF-alpha showed signs of blood-brain barrier damage. Moreover, intrathecal levels of TNF-alpha in active MS correlated with albumin ratios and with the degree of barrier damage. Our findings are important in understanding some of the pathological changes in active multiple sclerosis.

Upregulation of the inhibitor of apoptosis proteins in activated T lymphocytes from patients with multiple sclerosis.

The pathogenesis of multiple sclerosis (MS) may involve failure of programmed cell death (apoptosis) to eliminate potentially pathogenic, autoreactive T lymphocytes. This failure may be caused by multiple abnormalities of the cell death machinery. In this study, we investigated the expression of the inhibitors of apoptosis (IAP) proteins, cellular IAP-1, IAP-2, and X-linked IAP (XIAP), in T lymphocytes from patients with active relapsing-remitting MS and appropriate controls. The expression of IAP proteins was significantly higher in mitogen-stimulated intrathecal and peripheral T lymphocytes from MS patients when compared to corresponding expressions from inflammatory and non-inflammatory neurologic controls, and healthy individuals. IAP proteins were also expressed in resting (unstimulated) T lymphocytes predominantly from MS patients. The heightened expression of IAP proteins in MS patients correlated with T lymphocyte resistance to apoptosis, and was independent of cellular expression of the death receptor protein Fas. In contrast, cellular expression of the anti-apoptosis protein Bcl-2 was relatively similar between MS patients and the control groups. These findings suggest that over-expression of IAP proteins in mitogen-stimulated T lymphocytes is a feature of multiple sclerosis.

Heightened expression of survivin in activated T lymphocytes from patients with multiple sclerosis.

The perpetuation of the inflammatory process in multiple sclerosis (MS) may arise from the failure to eliminate potentially pathogenic autoreactive lymphocytes by programmed cell death (apoptosis). Such impairment may be caused by multiple abnormalities of apoptosis regulatory proteins. In this study, we investigated the expression of survivin, a recently described cell cycle-regulated antiapoptosis protein, in lymphocytes from patients with active relapsing-remitting MS and appropriate controls. Survivin reactivity was detected in intrathecal lymphocytes from some MS patients, but not in resting peripheral lymphocytes. However, mitogen stimulation of resting lymphocytes induced survivin expression, which was significantly higher in stimulated intrathecal and peripheral T lymphocytes from MS patients when compared to controls. In contrast, cellular expression of the antiapoptosis protein Bcl-2 was relatively similar between MS patients and the control groups. Moreover, heightened survivin expression in MS patients correlated with T lymphocyte resistance to apoptosis, and was independent of cellular expression of the death receptor Fas. These findings suggest that upregulation of the antiapoptotic protein survivin in mitogen-stimulated T lymphocytes is a feature of multiple sclerosis.

The expression of apoptosis-regulatory proteins in B lymphocytes from patients with multiple sclerosis.

The pathogenesis of multiple sclerosis (MS) is thought to involve T- and B-lymphocyte-mediated autoimmunity. However, the mechanisms that regulate lymphocyte activity in MS are poorly understood. In normal circumstances, programmed cell death (apoptosis) contributes to the maintenance of lymphocytes homeostasis and the deletion of autoreactive cells. Cellular commitment to apoptosis is partly regulated by the cell death receptor Fas, and the anti-apoptosis proteins Bcl-2 and FLIP. Although there is emerging evidence that dysregulations of apoptotic pathways play a role in T-cell autoimmunity in MS, the expression of apoptosis-regulatory proteins in B cells from MS patients is largely unknown. In this study, we analyzed the expression profiles of Fas, Bcl-2, and FLIP proteins in peripheral B lymphocytes from patients with relapsing-remitting and progressive MS, and from appropriate controls. We observed a significant up-regulation of Bcl-2 and FLIP proteins in B cells from relapsing-remitting MS when compared to corresponding expression in progressive MS, or in noninflammatory neurologic controls and healthy individuals. This cellular overexpression of Bcl-2 and FLIP proteins was not affected by treatment with interferon-beta, but was also observed in B cells from patients with systemic inflammatory diseases. Our findings suggest that cellular overexpression of the apoptosis-inhibitory proteins in patients with relapsing MS may promote apoptotic resistance of potentially pathogenic, autoreactive B lymphocytes and consequently, may allow for continuing autoimmune tissue destruction.

Glutaraldehyde-enhanced immunofixation: a sensitive new method for detecting oligoclonal immunoglobulin M.

A new, specific and economical method with enhanced sensitivity for rapid detection of IgM oligoclonal bands in unconcentrated cerebrospinal fluid (CSF) is presented. It is based on the use of glutaraldehyde during immunofixation of electrophoresed specimens and utilizes peroxidase-conjugated F(ab')2 fragment of anti-IgM antibody to avoid cross-reactivity with other CSF gamma globulins. It is able to detect 1 ng of IgM banded protein in electrophoresed CSF. Using this method, oligoclonal IgM was mainly detected in inflammatory and infectious conditions of the central nervous system.

Expression ratios of the Bcl-2 family proteins and disease activity in multiple sclerosis.

There is emerging evidence that failure of apoptosis (programmed cell death) of potentially pathogenic T lymphocytes may be involved in the pathogenesis of multiple sclerosis (MS). The commitment of T lymphocytes to die is partly regulated by the Bcl-2 family proteins, which act as a checkpoint upstream of mitochondrial dysfunction. These proteins include the death antagonists Bcl-2 and Bcl-X(L), and death agonists Bax and Bad. Recent studies suggest that altered expression of Bcl-2 family proteins in T lymphocytes is involved in promoting cellular resistance to apoptosis in patients with MS. However, the relationship between these alterations in Bcl-2 proteins expression and clinical disease activity has not yet been evaluated. In this study, we analyzed the expression ratios of pro- to anti-apoptosis Bcl-2 family proteins in patients with clinically active MS and compared results to corresponding ratios in patients with stable MS and relevant control groups. We observed a significant reduction in the expression ratios of pro- to anti-apoptosis Bcl-2 members in peripheral lymphocytes from patients with active MS when compared to corresponding ratios in patients with stable MS or other controls. This imbalance in the expression ratios of pro- and anti-apoptosis proteins was functionally active in reducing cellular susceptibility to apoptosis in active MS. It also correlated with clinical features of disease activity, such as the number of gadolinium-enhancing MRI lesions and clinical relapses. Our findings indicate that dysregulated expression of Bcl-2 family proteins in peripheral lymphocytes is a feature of clinically active multiple sclerosis.

The relationship of interleukin-2 and soluble interleukin-2 receptors to intrathecal immunoglobulin synthesis in patients with multiple sclerosis.

The in vivo relationship of interleukin-2 (IL-2) to the local humoral immune response within the central nervous system (CNS) in patients with multiple sclerosis (MS) is hitherto largely unknown. Intrathecal levels of IL-2 and soluble IL-2 receptors (sIL-2R) were correlated to the local CNS synthesis of immunoglobulin G, A, D, and M isotypes in 70 patients with clinically definite MS. Levels were also determined in 19 normal control subjects to establish normal reference limits. High cerebrospinal fluid levels of IL-2 and sIL-2R were detected mainly in patients with acute relapsing-remitting MS and were significantly higher than corresponding serum levels. Intrathecal levels of IL-2 significantly correlated with local CNS synthesis of IgD and IgM, while no correlation was found with either IgG or IgA. Similarly, intrathecal sIL-2R levels significantly correlated with local CNS production of IgD and IgM, but not IgG or IgA. These findings further extend previous reports and also suggest that IL-2 and sIL-2R are involved in the early intrathecal humoral immune response in MS.

Reduced expression of the inhibitor of apoptosis proteins in T cells from patients with multiple sclerosis following interferon-beta therapy.

Treatment with interferon-beta reduces clinical exacerbations in multiple sclerosis (MS) through several immunomodulatory mechanisms that involve the augmentation of programmed cell death (apoptosis) of peripheral T lymphocytes. The recently identified family of inhibitor of apoptosis (IAP) proteins is a potent regulator of cell death. The expression of IAP-1, IAP-2, and X-linked IAP (XIAP) is upregulated in mitogen stimulated T lymphocytes from MS patients, and this expression correlates with MS disease activity. In this study, we sought to evaluate the effect of interferon-beta on cellular expression of IAP proteins and other apoptosis regulatory molecules. In a prospective study, we evaluated the expression of IAP proteins, the anti-apoptosis Bcl-2 protein, and the death receptor Fas in in vitro stimulated T lymphocytes from MS patients, before and serially after treatment with interferon-beta. We also investigated the long-term effects of interferon-beta on cellular expression of these proteins and T lymphocyte apoptosis in a cross-sectional study of MS patients receiving drug therapy for a mean of 4.8 years. Treatment with interferon-beta reduced the expression of IAP-1, IAP-2 and XIAP in stimulated T lymphocytes. This reduced expression correlated with increased T cell susceptibility to apoptosis and with clinical response to treatment. In contrast, interferon-beta therapy did not alter cellular expression of Bcl-2 protein or the death receptor Fas. This downregulatory effect of interferon-beta on cellular expression of IAP proteins was maintained following long-term therapy. Our findings suggest that interferon-beta therapy exerts a regulatory effect on peripheral T lymphocytes through an anti-apoptosis mechanism that involves the downregulation of cellular IAP proteins expression.