Antibodies in the CSF of a Parkinson patient recognizes neurons in rat mesencephalic regions

Peripheral aetiopathogenic drivers and mediators of Parkinson's disease and co-morbidities: role of gastrointestinal microbiota

We seek an aetiopathogenic model for the spectrum of Parkinson's disease (PD), functional bowel disease, depression and cognitive impairment. The adopted concept is that systemic immuno-inflammatory processes mediate neuro-inflammation. The model would be based on phenotype, exposome (including gastrointestinal microbiome), milieu (immuno-inflammatory and metabolome), human genetics and their interactions. It would enable a patient's position, to be understood in terms of drivers, perpetuators and mediators, and a future position, with and without intervention, predicted. Even the cardinal facets of PD may have different drivers: halting one may allow escape down subordinate pathways. Peptic ulceration is prodromal to PD. In our randomised placebo-controlled trial, hypokinesia improved over the year following biopsy-proven Helicobacter pylori eradication and rigidity worsened. This was independent of any (stable, long t½) antiparkinsonian medication. There are pointers to an autoimmune process: for example, surveillance-confirmed hypokinesia effect was indication specific. During surveillance, successive antimicrobial courses, other than for Helicobacter, were associated with cumulative increase in rigidity. Exhibiting laxatives appeared to stem the overall temporal increase, despite antiparkinsonian medication, in rigidity. Thus, intestinal dysbiosis may be a major source of bystander neuronal damage. There are biological gradients of objective measures of PD facets on circulating inflammatory markers and leucocyte subset counts. Moreover, lactulose hydrogen breath test positivity for small-intestinal bacterial overgrowth (present in two thirds of PD patients) is associated with the same subsets: higher natural killer and total CD4+ counts and lower neutrophils. With greater aetiopathogenic understanding, relatively low cost and on-the-shelf medication could have a major impact. A new generation of animal models, based on the gut microbiome, is envisaged.

Neuroimmunological processes in Parkinson's disease and their relation to α-synuclein: microglia as the referee between neuronal processes and peripheral immunity

The role of neuroinflammation and the adaptive immune system in PD (Parkinson's disease) has been the subject of intense investigation in recent years, both in animal models of parkinsonism and in post-mortem PD brains. However, how these processes relate to and modulate α-syn (α-synuclein) pathology and microglia activation is still poorly understood. Specifically, how the peripheral immune system interacts, regulates and/or is induced by neuroinflammatory processes taking place during PD is still undetermined. We present herein a comprehensive review of the features and impact that neuroinflamation has on neurodegeneration in different animal models of nigral cell death, how this neuroinflammation relates to microglia activation and the way microglia respond to α-syn in vivo. We also discuss a possible role for the peripheral immune system in animal models of parkinsonism, how these findings relate to the state of microglia activation observed in these animal models and how these findings compare with what has been observed in humans with PD. Together, the available data points to the need for development of dual therapeutic strategies that modulate microglia activation to change not only the way microglia interact with the peripheral immune system, but also to modulate the manner in which microglia respond to encounters with α-syn. Lastly, we discuss the immune-modulatory strategies currently under investigation in animal models of parkinsonism and the degree to which one might expect their outcomes to translate faithfully to a clinical setting.

Microglia acquire distinct activation profiles depending on the degree of alpha-synuclein neuropathology in a rAAV based model of Parkinson's disease

Post-mortem analysis of brains from Parkinson's disease (PD) patients strongly supports microglia activation and adaptive immunity as factors contributing to disease progression. Such responses may be triggered by α-synuclein (α-syn), which is known to be the main constituent of the aggregated proteins found in Lewy bodies in the brains of PD patients. To investigate this we used a recombinant viral vector to express human α-syn in rat midbrain at levels that induced neuronal pathology either in the absence or the presence of dopaminergic cell death, thereby mimicking early or late stages of the disease. Microglia activation was assessed by stereological quantification of Mac1+ cells, as well as the expression patterns of CD68 and MCH II. In our study, when α-syn induced neuronal pathology but not cell death, a fast transient increase in microglia cell numbers resulted in the long-term induction of MHC II+ microglia, denoting antigen-presenting ability. On the other hand, when α-syn induced both neuronal pathology and cell death, there was a delayed increase in microglia cell numbers, which correlated with long-lasting CD68 expression and a morphology reminiscent of peripheral macrophages. In addition T-lymphocyte infiltration, as judged by the presence of CD4+ and CD8+ cells, showed distinct kinetics depending on the degree of neurodegeneration, and was significantly higher when cell death occurred. We have thus for the first time shown that the microglial response differs depending on whether α-syn expression results on cell death or not, suggesting that microglia may play different roles during disease progression. Furthermore, our data suggest that the microglial response is modulated by early events related to α-syn expression in substantia nigra and persists at the long term.

Helicobacter hypothesis for idiopathic parkinsonism: before and beyond

We challenge the concept of idiopathic parkinsonism (IP) as inevitably progressive neurodegeneration, proposing a natural history of sequential microbial insults with predisposing host response. Proof-of-principle that infection can contribute to IP was provided by case studies and a placebo-controlled efficacy study of Helicobacter eradication. "Malignant" IP appears converted to "benign", but marked deterioration accompanies failure. Similar benefit on brady/hypokinesia from eradicating "low-density" infection favors autoimmunity. Although a minority of UK probands are urea breath test positive for Helicobacter, the predicted probability of having the parkinsonian label depends on the serum H. pylori antibody profile, with clinically relevant gradients between this "discriminant index" and disease burden and progression. In IP, H. pylori antibodies discriminate for persistently abnormal bowel function, and specific abnormal duodenal enterocyte mitochondrial morphology is described in relation to H. pylori infection. Slow intestinal transit manifests as constipation from the prodrome. Diarrhea may flag secondary small-intestinal bacterial overgrowth. This, coupled with genetically determined intense inflammatory response, might explain evolution from brady/hypokinetic to rigidity-predominant parkinsonism.

Circulating interleukin-15 and RANTES chemokine in Parkinson's disease

Interleukin-15 promotes T-cell proliferation, induction of cytolytic effector cells including natural killer (NK) and cytotoxic cells and stimulates B-cell to proliferate and secrete immunoglobulins. RANTES is a C-C beta chemokine with strong chemoattractant activity for T lymphocytes and monocytes.

OBJECTIVES

The objective of our study was to find out whether IL-15 and RANTES are involved in the possible inflammatory reactions of PD.

PATIENTS AND METHODS

We measured by immunoassay serum IL-15 and RANTES levels in 41 patients with PD in comparison with serum levels in 19 healthy subjects age and sex-matched. IL-15 and RANTES levels were correlated with sex, age, disease duration. H-Y stage and the UPDRS III score in all the studied groups and were also correlated with treatment status in PD patients.

RESULTS

The PD group presented with significantly increased RANTES levels as compared to the control group (P = 0.0009). No difference was observed as regards IL-15 levels. A strong and significant correlation between RANTES levels and UPDRS III score was observed in PD patients (R(s) = 0.42, P = 0.007). Untreated patients had significantly higher RANTES levels as compared to the controls.

CONCLUSIONS

Our findings may suggest a recruitment of activated monocytes, macrophages and T lymphocytes to sites of inflammation in the central nervous system of PD patients.

Serum antibodies from Parkinson's disease patients react with neuronal membrane proteins from a mouse dopaminergic cell line and affect its dopamine expression

Evidence exists suggesting that the immune system may contribute to the severity of idiopathic Parkinson's disease (IPD). The data presented here demonstrates that antibodies in the sera of patients with IPD have increased binding affinity to dopaminergic (DA) neuronal (MN9D cell line) membrane antigens in comparison to antibodies in sera from healthy controls. In general, the degree of antibody reactivity to these antigens of the mouse MN9D cell line appears to correlate well with the disease severity of the IPD patients contributing sera, based on the total UPDRS scores. Surprisingly, the sera from IPD patients enhanced the DA content of MN9D cells differentiated with n-butyrate; the n-butyrate-differentiated MN9D cells had a greater concentration of DA (DA/mg total protein) than undifferentiated MN9D cells, especially early in culture. Although the IPD sera did not directly harm MN9D cellular viability or DA production, in the presence of the N9 microglial cell line, the amount of DA present in cultures of untreated or n-butyrate-treated MN9D cells was lowered by the IPD sera. The results suggest the involvement of antibodies in the decline of dopamine production and, thus, the potential of immune system participation in IPD.

Neuroinflammatory processes in Parkinson's disease

Parkinson's disease (PD) is a movement disorder characterized by the progressive degeneration of dopaminergic neurons in the midbrain. To date, its cause remains unknown and the mechanism of nerve cell death uncertain. Apart from the massive loss of dopaminergic neurons, PD brains also show a conspicuous glial reaction together with signs of a neuroinflammatory reaction manifested by elevated cytokine levels and upregulation of inflammatory-associated factors such as cyclooxygenase-2 and inducible nitric oxide synthase. Mounting evidence also suggests a possible deleterious effect of these neuroinflammatory processes in experimental models of the disease. We propose that, in PD, neuroinflammation plays a role in the cascade of events leading to nerve cell death, thus propagating the neurodegenerative process. In this review, we summarize and discuss the latest findings regarding neuroinflammatory aspects in PD.

IgG-immunostaining in the intact rabbit brain: variable but significant staining of hippocampal and cerebellar neurons with anti-IgG

A significant number of brain neurons in the rabbit brain were immunostained with anti-rabbit gamma-immunoglobulin (IgG). IgG-positive neurons were often found in the cerebellum, lower brainstem and motor nuclei. Similar IgG-positive neurons were occasionally found in the hippocampus, cerebral cortex and midbrain, but not in the striatum and thalamus. These neurons showed very clear Golgi-like staining of soma and dendrites but IgG staining was absent from the cell nuclei and axons. In particular, groups of Purkinje neurons in the rabbit cerebellum showed strong IgG-positive staining. To confirm whether the staining reflected the existence of IgG molecules in these neurons, staining specificity was carefully evaluated. Staining was specifically eliminated by pre-absorption of the antibodies with the purified rabbit IgG. An antibody to the neural cell adhesion molecule (NCAM or CD56), a member of the immunoglobulin superfamily, exhibited a completely different pattern of staining as that for IgG. To determine whether IgG-like immunoreactivity was a general feature of mammalian brain, brain sections of rabbits, rats, and mice were immunostained with antibodies to IgGs of each of the three species. Similar IgG-positive neurons were observed in all three species, although the distribution and frequency was characteristic for each species. In rabbit brain, anti-rabbit IgG stained-neurons were more abundant compared to rat and mouse brain. IgG-positive microglia-like cells were evident in mouse brain, but less frequent in rabbit and were hardly observed in rat brain. To evaluate whether stained neurons could synthesize IgG, in situ hybridization was carried out using an antisense oligonucleotide probe to rabbit IgG DNA. No significant label was observed in cerebellum. These results suggest that a significant number of neurons in the intact rabbit brain take up IgGs and concentrate them in their cytoplasm, although the molecular uptake mechanism is retained for future studies. Our results also suggest that the rabbit may be a suitable animal to study the function(s) of IgG in brain neurons.

Autoimmunity and neurological disease: antibody modulation of synaptic transmission

Over the past three decades, compelling evidence has emerged that the immune system can attack the nervous system with devastating consequences for human health. Either cell-mediated or humoral (antibody-mediated) autoimmune mechanisms may predominate in effecting a given disease, and either glia or neurons may fall under immune attack. A subset of these diseases has been particularly useful for understanding fundamental neuroscience as well as mechanisms of human disease. This subset involves humoral autoimmune attack on cell surface molecules subserving transmembrane signaling of excitable cells; special emphasis is placed here on proteins involved in synaptic transmission. We begin by reviewing the prototypic humoral autoimmune disease of synaptic transmission, myasthenia gravis. This provides a context for insights obtained from the study of diseases targeting molecules that regulate synaptic transmission at the neuromuscular junction and in the central nervous system. We also explore a disease where autoimmunity produces agonist antibodies acting at two distinct G-protein-coupled receptors. We conclude with an exploration of the vital issue of access of antibodies to targets within the central nervous system and the implications that such access may have in the pathogenesis of poorly understood idiopathic central nervous system diseases.

Screening of the macromolecular component of CSF from various pathologies for its interference with GABAA receptor function

Cerebrospinal fluid (CSF) samples from patients undergoing lumbar puncture for suspected neurological diseases were fractioned into macromolecular (MW > 3000 Daltons) and small molecule components (MW < 3000 Daltons). The macromolecular component was tested for its interference with GABA stimulation of 36Cl- accumulation in rat cerebral cortex microsacs. For many pathologies, no interference was apparent; an exception was two patients with Parkinson's disease in whom there were clear signs of stimulated GABA activity. This last result seems worthy of further investigation.

A correlation study between serum adenosine deaminase activities and peripheral lymphocyte subsets in Parkinson's disease

Adenosine deaminase (ADA) and its isozyme activities in serum were measured together with peripheral lymphocyte subsets in 42 patients with idiopathic Parkinson's disease. The total and ADA 2 activities were significantly higher than normal controls (p < 0.01). As regards the peripheral lymphocyte subsets, the proportion of OKT 10+ cells (activated T lymphocytes) and the proportions of interleukin-2 receptor+ and HLA-DR+ cells (mainly activated T lymphocytes) were significantly higher than normal controls (p < 0.05, 0.01, 0.01, respectively). On the other hand, OKT 10+ cells demonstrated a significant correlation not only with total ADA but also with ADA 2 activity. These results suggest that high serum ADA activity may be involved in the pathogenesis of Parkinson's disease through peripheral T lymphocyte activation.

Experimental autoimmune nigral damage in guinea pigs

An animal model of experimental autoimmune nigral damage (EAND) has been developed in guinea pigs by immunization with hybrid dopaminergic cells (MES 23.5). In such animals, loss of 40% of the substantia nigra (SN) neurons and damage to an additional 10% of SN neurons was associated with a 37-43% decrease of tyrosine hydroxylase (TH) activity and a 36% decrease of dopamine (DA) content in the nigral-striatum. Eight of the thirteen animals developed significant hypokinesia. The EAND model suggests that degeneration of dopaminergic neurons in SN can be caused by immune-mediated processes, which may help our understanding of the pathogenesis in Parkinson's disease.

Parkinsonian serum carries complement-dependent toxicity for rat mesencephalic dopaminergic neurons in culture

The presence of antibodies recognizing specific epitopes of dopaminergic neurons in serum of patients suffering of Parkinson's Disease (PD) as well as their capability to induce neuronal damage was investigated utilizing serum-free dissociated mesencephalic-striatal co-cultures. High affinity dopamine (DA) and GABA uptakes were assessed as specific, functional markers of dopaminergic and GABAergic cell viability, respectively. Heat-inactivated serum samples from 18 and 13 patients suffering from idiopathic and vascular parkinsonism, respectively and from 18 neurologic controls, were added to co-cultures on day 4 in vitro. Twenty four hours later, reconstituted rabbit complement was added for 60 min and uptake parameters as well as immunocytochemical staining for tyrosine hydroxylase (TH)-containing cells were subsequently assessed. DA, but not GABA, uptake was significantly decreased only when complement was added to cultures containing serum samples from 14 out of 18 patients with idiopathic parkinsonism and 3 out of 13 patients with vascular parkinsonism (Fisher test, P < 0.01). Complement addition to cultures containing serum samples from seropositive parkinsonian patients significantly reduced immunocytochemical staining of TH-containing cells. Seropositive and seronegative patients did not differ in demographic and clinical features. These results suggest that a complement-dependent humoral immune response occurs mainly in idiopathic parkinsonian patients, but its clinical relevance remains to be established.

Nigral damage and dopaminergic hypofunction in mesencephalon-immunized guinea pigs

To support a potential role for immune mechanisms in the destruction of substantia nigra (SN) neurons, guinea pigs were immunized with bovine mesencephalon containing SN neurons. After immunization no clinical signs of basal ganglia dysfunction appeared. However, pathological examination revealed evidence of neuronal damage in the SN in 8 of 17 guinea pigs immunized with bovine mesencephalon. No nigral pathology was noted in animals immunized with spinal cord gray matter or Freund's adjuvant alone. Accompanying the SN damage in mesencephalon-immunized guinea pigs was a 25% decrease in tyrosine hydroxylase activity in the SN and a 27% decrease in dopamine content in the striatum. Deposits of IgG were detected by immunohistochemical techniques in sections of SN from mesencephalon-immunized guinea pigs and in sections of human SN after exposure to serum from mesencephalon-immunized guinea pigs. These data document the antigenicity of SN and suggest the possibility that immune mechanisms can contribute to basal ganglia pathology.

Non-specific binding of normal human IgG, including F(ab')2 and Fc fragments, to embryonic rat brain neurons and human cortex synaptosomes

Binding of normal human IgG to embryonic rat brain neurons was quantitated by flow cytometry. IgG binding was linear between 0.05 and 1.5 mg/ml; slight binding was detectable even at normal cerebrospinal fluid concentrations. Similar binding curves were obtained for purified Fc and F(ab')2 fragments from normal human IgG. Normal human IgG also bound to synaptosomes (resealed nerve terminals) from human cerebral cortex. However, competition assays utilizing 125I-IgG showed no evidence for specific binding. This study indicates that the specificity of putative anti-neuronal antibodies should be confirmed by competition assays as for other receptor-ligand binding.

Antibody in the CSF of patients with multiple system atrophy reacts specifically with rat locus ceruleus

Idiopathic chronic autonomic dysfunction may occur as pure autonomic failure (PAF) or in association with multiple system atrophy (MSA). CSF immunoreactivity to rat locus ceruleus occurred in a significantly greater number of samples from MSA patients compared to control subjects or patients with PAF. Other brain regions infrequently showed immunoreactivity. These findings suggest that degeneration in MSA may release antigen(s) that induce antibodies against locus ceruleus neurons. Further studies are required to determine whether immune abnormalities play a pathogenetic role in MSA. Lack of CSF immunoreactivity in PAF is consistent with primarily peripheral involvement.

Investigations on auto-antibodies in Alzheimer's and Parkinson's diseases, using defined neuronal cultures

In immunocytochemical studies, the CSF from Parkinson disease (PD) patients and from Alzheimer disease (AD) patients were investigated for the presence of neuron specific antibodies using dopaminergic and cholinergic neuronal cultures from embryonic rat brain, respectively. Dopamine containing cell bodies were labelled by Parkinsonian CSF-IgG, while cholinergic neurons, identified with a-NGF-receptor antibodies, were recognized by CSF from AD-patients. The CSF from PD-patients was investigated after autologous adrenal transplantation. CSF was removed 7 d, 5 months and 1 year after operation. When added to 18 d neuronal cultures for 3 d, the 7 d CSF caused neuronal cell and a glial reaction. The 4 months CSF caused cell death, but markedly less than the 7 d CSF. One year after transplantation the CSF had no toxic effects; these cultures were similar to control cultures. It is concluded that CSF from PD patients may contain aggressive IgG-species specific for DA neurons, and that the amount of such antibodies decrease after adrenal transplant operations. It is suggested that neurodegenerative diseases may become aggravated by autoimmune reactions.

Antibody reactivity to brain membrane proteins in serum from schizophrenic patients

Antibody reactivity to rat brain components in sera from schizophrenic patients and healthy controls was determined using ELISA and Western immunoblotting. Crude membranes prepared from striatum, hippocampus and cortex were used as antigens. The degree of ELISA reactivity varied between individuals but no significant difference was seen between the patient and control groups in any of the different preparations. With a blocking-type of ELISA, in which a pool of dopamine receptor antagonists/neuroleptica was used to compete with the antibody binding, inhibition of IgG reactivity was seen in half of the patient and a quarter of the control sera. When the antagonists were added individually, 25% of the patients but none of the controls showed an inhibited IgG response due to haloperidol and sulpiride. In Western immunoblotting there was a complex background pattern overlaid with a variety of individual bands that could not be related to disease. However a few bands specific for the schizophrenic group were found in more than 50% of the patients. The molecular weights of the two most prominent polypeptides were 86 and 68 kD. The three major Ig-classes G, A, and M showed a partly overlapping and variable degree of reactivity in the patient group. By screening, it was found that 3 out of 50 control sera reacted with either the 86 or the 68 Kd polypeptide. The results do not exclude the possibility that schizophrenic patients do have antibodies reactive to the dopamine receptor.

An antibody in the CSF of Parkinson's disease patients disappears following adrenal medulla transplantation

CSF from Parkinson's disease (PD) patients undergoing autologous transplantation of adrenal medulla tissue into their lateral ventricle was examined for the presence of IgG. CSF from 6 of 7 patients incubated with rat brain tissue reacted immunocytochemically to neuronal cell bodies in the substantia nigra and ventral tegmental region. This reactivity gradually disappeared in the months following transplantation. Five of 6 CSF samples from non-transplanted PD patients also produced this immunocytochemical reactivity whereas 26 non-PD samples were immunonegative. Possible implications to the transplant procedure are discussed.

Parkinson's disease: an autoimmune process

Parkinson's disease (PD) is a common condition that, in the majority of cases, is idiopathic in origin. The loss of central dopaminergic pathways is well-known and in this paper a theory is presented that this is brought about by an autoimmune process. The lack of any HLA association or familial clumping for the disease does not exclude such a theory, as a common etiological agent may exist that we do not yet recognize, e.g., infection, or drugs. Several autoantibodies and disturbances in T-cell function have been found in PD. The theory proposes that the production of autoantibodies and T-cell activation are important in the pathogenesis of idiopathic PD by an action on the substance P striatonigral pathway and its input to the dopaminergic nigrostriatal pathway. The autoimmune destruction of the substance P input leads to a secondary loss of the dopaminergic system and hence PD.

Rate of cell death in parkinsonism indicates active neuropathological process

It has been hypothesized that idiopathic parkinsonism might be due to age-related attrition of dopamine neurons occurring long after an initial acute episode. We present evidence against this hypothesis, based on our finding of at least six times as many HLA-DR-positive microglia phagocytosing dopamine neurons in parkinsonian brains as in control brains. This difference indicates an active pathological process.

A double-blind evaluation of electroconvulsive therapy in Parkinson's disease with "on-off" phenomena

Eleven patients with severe Parkinson's disease and on-off-phenomena were included in a controlled double-blind study on the effect of electroconvulsive therapy (ECT). Pharmacological treatment was optimally adjusted before the trial. The severity of extrapyramidal symptoms was measured before, during and after the treatment. The patients were randomly allocated into one group, receiving active ECT and another, receiving sham treatment. The patients given active ECT showed significantly (P less than 0.05) prolonged duration of "on"-phases after ECT, in comparison to the sham-treated group. When collecting data from the controlled part of the study and the subsequent with open administration of ECT, the treatment was in addition found to significantly decrease the time and number of steps required to walk 10 meters. Moreover it reduced the severity of parkinsonian symptoms according to the Webster scale. The improvement induced by ECT was generally short-lasting. Lumbar punctures were performed before and after ECT. The concentrations of monoamine metabolites in cerebrospinal fluid were not affected by the treatment. The results indicate that ECT has an antiparkinsonian effect which probably is mediated via changed responsiveness of dopamine receptors and that further improvement is possible in patients, therapy resistant to the presently available medication.