Ciita Regulates Local and Systemic Immune Responses in a Combined rAAV-α-synuclein and Preformed Fibril-Induced Rat Model for Parkinson's Disease.

Background: Parkinson's disease (PD) is characterized by alpha-synuclein (α-Syn) pathology, neurodegeneration and neuroinflammation. Human leukocyte antigen (HLA) variants associated with PD and α-Syn specific CD4+ T lymphocytes in PD patients highlight the importance of antigen presentation in PD etiology. The class II transactivator (CIITA) regulates major histocompatibility complex class II (MHCII) expression. Reduced Ciita levels significantly increase α-Syn pathology, nigrostriatal neurodegeneration and behavioral deficits in α-Syn-induced rat PD models. Objective: Characterize immune profiles associated with enhanced PD-like pathology observed in rats expressing lower Ciita levels (DA.VRA4) compared to the background strain (DA). Methods: To model PD, we combined rAAV-mediated α-Syn overexpression in the substantia nigra with striatal injection of α-Syn preformed fibrils. Immune profiles in brain and blood were analyzed by flow cytometry and multiplexed ELISA in naïve rats, 4- and 8 weeks post rAAV injection. Results: Flow cytometry showed Ciita-dependent regulation of MHCII on microglia, brain macrophages and circulating myeloid cells. The MHCII-dependent microglial response was highest at 4 weeks post rAAV injection, whereas the MHCII levels in circulating myeloid cells was highest at 8 weeks. There was no major infiltration of macrophages or T lymphocytes into the CNS in response to α-Syn and only subtle Ciita- and/or α-Syn-dependent changes in the T lymphocyte compartment. Lower Ciita levels were consistently associated with higher TNF levels in serum. Conclusions: Ciita regulates susceptibility to PD-like pathology through minor but detectable changes in resident and peripheral immune cells and TNF levels, indicating that mild immunomodulatory therapies could have therapeutic effects in PD.

Parkinson's disease is characterized by loss of nerve cells. There is also abnormal aggregation of a protein called alpha-synuclein and an ongoing inflammatory response. Findings that immune cells in the blood of individuals with Parkinson's disease react against the alpha-synuclein protein and that genes important for the immune system affect the risk of developing Parkinson's disease indicate that immune responses are important in Parkinson's disease. We have previously found that a low expression of certain immune molecules worsens disease progression in a rat model of Parkinson's disease. The aim of this study was to identify changes in the immune system in rats that are associated with disease severity, to identify mechanisms that could be targeted to treat Parkinson's disease. To model Parkinson's disease, we injected a modified virus to produce large amounts of alpha-synuclein combined with an injection of aggregated alpha-synuclein proteins in the rat brain. The model mimics several features of Parkinson's disease including nerve cell death, problems with movement, accumulation of alpha-synuclein in the brain, and an immune response. We observed that the immune system in the brain and blood responded to the model but that differences were small compared to controls. Our results suggest that small changes in the immune system can have a large effect on disease progression and that therapies targeting the immune system are worth exploring to find better treatment for Parkinson's disease.

Flavin-containing monooxygenase 1 deficiency promotes neuroinflammation in dopaminergic neurons in mice.

A growing body of evidence indicates an association between flavin-containing monooxygenase (FMO) and neurodegeneration, including Parkinson's disease (PD); however, the details of this association are unclear. We previously showed that the level of Fmo1 mRNA is decreased in an in vitro rotenone model of parkinsonism. To further explore the potential involvement of FMO1 deficiency in parkinsonism, we generated Fmo1 knockout (KO) mice and examined the survival of dopaminergic neurons and relative changes. Fmo1 KO mice exhibited loss of tyrosine hydroxylase-positive neurons, decreased levels of tyrosine hydroxylase and Parkin proteins, and increased levels of pro-inflammatory cytokines (IL1ß and IL6) in the nigrostriatal region. Moreover, the protein levels of PTEN induced kinase 1 (PINK1) and p62, and the Microtubule associated protein 1 light chain 3 (LC3)-II/I ratio were not significantly altered in Fmo1 KO mice (P > 0.05). FMO1 deficiency promotes neuroinflammation in dopaminergic neurons in mice, thus may plays a potential pathological role in dopaminergic neuronal loss. These findings may provide new insight into the pathogenesis of PD.

The stimulator of interferon genes (STING) pathway is upregulated in striatal astrocytes of patients with multiple system atrophy.

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by the accumulation of pathogenic phosphorylated α-synuclein in oligodendrocytes. In brains affected by MSA, severe astrogliosis is also observed, but its precise role in MSA pathogenesis remains largely unknown. Recently, the stimulator of interferon genes (STING) pathway and type I interferons, its downstream molecules, have been reported to be involved in the neurodegenerative process and to be activated in astrocytes. This study aimed to investigate the role of the STING pathway in the pathogenesis of MSA using postmortem brains. Samples used for immunohistochemical analysis included 6 cases of MSA parkinsonism type (MSA-P), 6 cases of MSA cerebellar type (MSA-C), and 7 age-matched controls. In MSA-P cases, astrocytes immunopositive for STING and TANK-binding kinase 1 (TBK1), its downstream molecule, were abundantly observed in the putamen and the substantia nigra. Moreover, these molecules colocalized with glial fibrillary acidic protein (GFAP) in reactive astrocytes, and the density of STING-positive astrocytes correlated with that of GFAP-positive reactive astrocytes in the brains of patients with MSA-P. These results suggest that the upregulated expression of STING pathway-related proteins in astrocytes and the subsequent inflammation may contribute to the pathogenesis in MSA-P and could provide novel therapeutic targets for the treatment of MSA.

Monocyte markers correlate with immune and neuronal brain changes in REM sleep behavior disorder.

Synucleinopathies are neurodegenerative diseases with both central and peripheral immune responses. However, whether the peripheral immune changes occur early in disease and their relation to brain events is yet unclear. Isolated rapid-eye-movement (REM) sleep behavior disorder (iRBD) can precede synucleinopathy-related parkinsonism and provides a prodromal phenotype to study early Parkinson's disease events. In this prospective case-control study, we describe monocytic markers in a cohort of iRBD patients that were associated with the brain-imaging markers of inflammation and neuronal dysfunction. Using 11C-PK11195 positron emission tomography (PET), we previously showed increased immune activation in the substantia nigra of iRBD patients, while 18F-DOPA PET detected reduced putaminal dopaminergic function. Here we describe that patients' blood monocytic cells showed increased expression of CD11b, while HLA-DR expression was decreased compared to healthy controls. The iRBD patients had increased classical monocytes and mature natural killer cells. Remarkably, the levels of expression of Toll-like receptor 4 (TLR4) on blood monocytes in iRBD patients were positively correlated with nigral immune activation measured by 11C-PK11195 PET and negatively correlated with putaminal 18F-DOPA uptake; the opposite was seen for the percentage of CD163+ myeloid cells. This suggesting a deleterious role for TLR4 and, conversely, a protective one for the CD163 expression. We show an association between peripheral blood monocytes and brain immune and dopaminergic changes in a synucleinopathy-related disorder, thus suggesting a cross-talk among periphery and brain during the disease.

Oral P. gingivalis impairs gut permeability and mediates immune responses associated with neurodegeneration in LRRK2 R1441G mice.

BACKGROUND: The R1441G mutation in the leucine-rich repeat kinase 2 (LRRK2) gene results in late-onset Parkinson's disease (PD). Peripheral inflammation and gut microbiota are closely associated with the pathogenesis of PD. Chronic periodontitis is a common type of peripheral inflammation, which is associated with PD. Porphyromonas gingivalis (Pg), the most common bacterium causing chronic periodontitis, can cause alteration of gut microbiota. It is not known whether Pg-induced dysbiosis plays a role in the pathophysiology of PD. METHODS: In this study, live Pg were orally administrated to animals, three times a week for 1 month. Pg-derived lipopolysaccharide (LPS) was used to stimulate mononuclear cells in vitro. The effects of oral Pg administration on the gut and brain were evaluated through behaviors, morphology, and cytokine expression. RESULTS: Dopaminergic neurons in the substantia nigra were reduced, and activated microglial cells were increased in R1441G mice given oral Pg. In addition, an increase in mRNA expression of tumor necrosis factor (TNF-α) and interleukin-1ß (IL-1ß) as well as protein level of α-synuclein together with a decrease in zonula occludens-1 (Zo-1) was detected in the colon in Pg-treated R1441G mice. Furthermore, serum interleukin-17A (IL-17A) and brain IL-17 receptor A (IL-17RA) were increased in Pg-treated R1441G mice. CONCLUSIONS: These findings suggest that oral Pg-induced inflammation may play an important role in the pathophysiology of LRRK2-associated PD.

Regional microglial activation in the substantia nigra is linked with fatigue in MS.

OBJECTIVE: The goal of our study is to assess the role of microglial activation in MS-associated fatigue (MSAF) using [F-18]PBR06-PET. METHODS: Fatigue severity was measured using the Modified Fatigue Impact Scale (MFIS) in 12 subjects with MS (7 relapsing-remitting and 5 secondary progressive) and 10 healthy control participants who underwent [F-18]PBR06-PET. The MFIS provides a total fatigue score as well as physical, cognitive, and psychosocial fatigue subscale scores. Standardized Uptake Value (SUV) 60-90 minute frame PET maps were coregistered to 3T MRI. Voxel-by-voxel analysis using Statistical Parametric Mapping and atlas-based regional analyses were performed. SUV ratios (SUVRs) were global brain normalized. RESULTS: Peak voxel-based level of significance for correlation between total fatigue score and PET uptake was localized to the right substantia nigra (T-score 4.67, p = 0.001). Similarly, SUVRs derived from atlas-based segmentation of the substantia nigra showed significant correlation with MFIS (r = 0.76, p = 0.004). On multiple regression, the right substantia nigra was an independent predictor of total MFIS (p = 0.02) and cognitive MFIS subscale values (p = 0.007), after adjustment for age, disability, and depression. Several additional areas of significant correlations with fatigue scores were identified, including the right parahippocampal gyrus, right precuneus, and juxtacortical white matter (all p < 0.05). There was no correlation between fatigue scores and brain atrophy and lesion load in patients with MS. CONCLUSION: Substantia nigra microglial activation is linked to fatigue in MS. Microglial activation across key brain regions may represent a unifying mechanism for MSAF, and further evaluation of neuroimmunologic basis of MSAF is warranted.

HMGB1 A box protects neurons by potently inhibiting both microglia and T cell-mediated inflammation in a mouse Parkinson's disease model.

In the subacute Parkinson's disease (PD) mice model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), injection of HMGB1 competitive inhibitor protein HMGB1 A box and the ethyl pyruvate (EP) that inhibit the release of HMGB1 from cells restored the number of dopaminergic neurons and TH+ fibers in the SN and striatum. Our data show that A box up-regulated CD200-CD200R signal of microglia inhibited the activation of microglia mediated by HMGB1, and the production of TNF-α, IL-1ß and IL-6 in vivo and in vitro mixed culture system. Microglia overexpressing CD200R produced less inflammatory chemokines and reduced the loss of TH+ neurons. In addition, HMGB1 A box decreased the level of CCL5 and significantly inhibited the infiltration of almost all T cells including Th17 and the proportion of Th17 in CD4+ T cells. In vitro MPP+ induced model and HMGB1-stimulated mesencephalic cell system activated microglia induced the differentiation of naïve T cells to Th17, and A box significantly inhibited this process. To sum up, our results show that HMGB1 A box targeting HMGB1, which effectively reduces the activation of microglia in MPTP PD model by restoring CD200-CD200R signal inhibit microglia mediated neuroinflammation and the differentiation of T cells to Th17.

Long-term post-mortem studies following neurturin gene therapy in patients with advanced Parkinson's disease.

We performed post-mortem studies on two patients with advanced Parkinson's disease 8 and10 years following AAV2-neurturin (CERE120) gene therapy, the longest post-mortem trophic factor gene therapy cases reported to date. CERE120 was delivered to the putamen bilaterally in one case (10 years post-surgery), and to the putamen plus the substantia nigra bilaterally in the second (8 years post-surgery). In both patients there was persistent, albeit limited, neurturin expression in the putamen covering ∼3-12% of the putamen. In the putamen, dense staining of tyrosine hydroxylase-positive fibres was observed in areas that contained detectable neurturin expression. In the substantia nigra, neurturin expression was detected in 9.8-18.95% and 22.02-39% of remaining melanin-containing neurons in the patient with putamenal and combined putamenal and nigral gene delivery, respectively. Melanized neurons displayed intense tyrosine hydroxylase and RET proto-oncogene expression in nigral neurons in the patient where CERE120 was directly delivered to the nigra. There was no difference in the degree of Lewy pathology in comparison to untreated control patients with Parkinson's disease, and α-synuclein aggregates were detected in neurons that also stained for neurturin, RET, and tyrosine hydroxylase. These changes were not associated with antiparkinsonian benefits likely due to the limited neurturin expression. This study provides the longest term evidence of persistent transgene expression following gene delivery to the CNS and the first human results when targeting both the terminal fields in the putamen as well as the originating nigral neurons.

Intrastriatal injection of preformed alpha-synuclein fibrils alters central and peripheral immune cell profiles in non-transgenic mice.

Parkinson's disease (PD) is characterized by the accumulation of alpha-synuclein (α-syn) inclusions, the major component of Lewy bodies. Extracellular α-syn aggregates act as a damage-associated molecular pattern (DAMP) and the presence of autoantibodies against α-syn species in the cerebrospinal fluid and the serum of PD patients implicate the involvement of innate and adaptive immune responses. In non-transgenic (Tg) mice, intrastriatal injection of preformed fibril (PFF) α-syn results in widespread pathologic α-syn inclusions in the CNS. While the PFF model has been broadly utilized to study the mechanistic relationship between α-syn transmission and other neuropathological phenotypes, the immune phenotypes in this model are not clearly demonstrated. This study aimed to characterize the immune phenotypes during pathologic α-syn propagation by utilizing PFF α-syn-injected non-tg mice. Here, we showed that pathologic α-syn inclusions are prevalent in various brain regions and the gut at 5 months post injection (p.i.), preceding the degeneration of dopaminergic neurons in substantia nigra (SN). We discovered a distinct inflammatory response involving both activation of microglia and astrocytes and infiltration of B, CD4+ T, CD8+ T, and natural killer cells in the brain at 5 months p.i. Moreover, PFF α-syn-injected mice display significant alterations in the frequency and number of leukocyte subsets in the spleen and lymph nodes with minimum alterations in the blood. Our data provide primary evidence that intracerebral-initiated synucleinopathies in non-tg mice alter immune cell profiles both in the CNS and peripheral lymphoid organs. Furthermore, our data provides support for utilizing this mouse model to assess the mechanistic connection between immune responses and synuclein pathology.

Schisandrin A ameliorates MPTP-induced Parkinson's disease in a mouse model via regulation of brain autophagy.

Schisandrin A (Sch A) is one of the principal bioactive lignans isolated from Fructus schisandrae. In this study, we demonstrated its protective effect and biochemical mechanism of action in a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine-induced mouse model of Parkinson's disease. Sch A significantly ameliorated behavioural abnormalities and increased the number of nigral dopaminergic neurons detected by tyrosine hydroxylase immunohistochemistry. Pre-treatment with Sch A significantly decreased the levels of the inflammatory mediators IL-6, IL-1ß, and TNF-α and markedly improved antioxidant defences by inhibiting the activity of MDA and increasing that of SOD. Furthermore, Sch A activated expression of the autophagy-related proteins LC3-II, beclin1, parkin, and PINK1 and increased mTOR expression. Taken together, these findings indicate that Sch A has neuroprotective effects against the development of Parkinson's disease via regulation of brain autophagy.

RANTES-induced invasion of Th17 cells into substantia nigra potentiates dopaminergic cell loss in MPTP mouse model of Parkinson's disease.

Although Parkinson's disease (PD) is a progressive neurodegenerative disease, the disease does not progress or persist in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model, the most common animal model of PD. Recently, we have described that supplementation of regulated on activation, normal T cell expressed and secreted (RANTES), a chemokine known to drive infiltration of T cells, induces persistent nigrostriatal pathology in MPTP mouse model. However, which particular T cell subsets are recruited to the substantia nigra (SN) by RANTES is not known. Here, by adoptive transfer of different subset of T cells from tomato red transgenic mice to MPTP-intoxicated immunodeficient Rag1-/- mice, we describe that invasion of Th17 cells into the SN is stimulated by exogenous RANTES administration. On the other hand, RANTES supplementation remained unable to influence the infiltration of Th1 and Tregs into the SN of MPTP-insulted Rag1-/- mice. Accordingly, RANTES supplementation increased MPTP-induced TH cell loss in Rag1-/-mice receiving Th17, but neither Th1 nor Tregs. RANTES-mediated aggravation of nigral TH neurons also paralleled with significant DA loss in striatum and locomotor deficits in MPTP-intoxicated Rag1-/- mice receiving Th17 cells. Finally, we demonstrate that levels of IL-17 (a Th17-specific cytokine) and RANTES are higher in serum of PD patients than age-matched controls and that RANTES positively correlated with IL-17 in serum of PD patients. Together, these results highlight the importance of RANTES-Th17 pathway in progressive dopaminergic neuronal loss and associated PD pathology.

IL-17A exacerbates neuroinflammation and neurodegeneration by activating microglia in rodent models of Parkinson's disease.

Neuroinflammation has been involved in pathogenesis of Parkinson's disease (PD), a chronic neurodegenerative disease characterized neuropathologically by progressive dopaminergic neuronal loss in the substantia nigra (SN). We recently have shown that helper T (Th)17 cells facilitate dopaminergic neuronal loss in vitro. Herein, we demonstrated that interleukin (IL)-17A, a proinflammatory cytokine produced mainly by Th17 cells, contributed to PD pathogenesis depending on microglia. Mouse and rat models for PD were prepared by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or striatal injection of 1-methyl-4-phenylpyridinium (MPP+), respectively. Both in MPTP-treated mice and MPP+-treated rats, blood-brain barrier (BBB) was disrupted and IL-17A level increased in the SN but not in cortex. Effector T (Teff) cells that were adoptively transferred via tail veins infiltrated into the brain of PD mice but not into that of normal mice. The Teff cell transfer aggravated nigrostriatal dopaminergic neurodegeneration, microglial activation and motor impairment. Contrarily, IL-17A deficiency alleviated BBB disruption, dopaminergic neurodegeneration, microglial activation and motor impairment. Anti-IL-17A-neutralizing antibody that was injected into lateral cerebral ventricle in PD rats ameliorated the manifestations mentioned above. IL-17A activated microglia but did not directly affect dopaminergic neuronal survival in vitro. IL-17A exacerbated dopaminergic neuronal loss only in the presence of microglia, and silencing IL-17A receptor gene in microglia abolished the IL-17A effect. IL-17A-treated microglial medium that contained higher concentration of tumor necrosis factor (TNF)-α facilitated dopaminergic neuronal death. Further, TNF-α-neutralizing antibody attenuated MPP+-induced neurotoxicity. The findings suggest that IL-17A accelerates neurodegeneration in PD depending on microglial activation and at least partly TNF-α release.

Peli1 controls the survival of dopaminergic neurons through modulating microglia-mediated neuroinflammation.

Chronic neuroinflammation is known to contributes to the toxicity of neurodegeneration of Parkinson's disease (PD). However, the molecular and cellular mechanisms controlling inflammatory responses in the central nervous system remain poorly understood. Here we found that a E3 ubiquitin ligase Peli1 is dramatically induced only in the substantia nigra (SN) of the human and mouse PD brains. The ablation of Peli1 significantly suppressed LPS-induced production of neurotoxic mediators and proinflammatory cytokines in SN and in primary microglia, whereas Peli1 is dispensable for the inflammatory responses in astrocyte. Accordingly, Peli1 deficiency markedly inhibited neuron death induced by the conditioned medium from LPS-stimulated microglia. Mechanistical study suggested that Peli1 acts as a positive regulator of inflammatory response in microglia through activation of NF-κB and MAP kinase. Our results established Peli1 as a critical mediator in the regulation of microglial activation and neuroinflammation-induced death of dopaminergic neurons during PD pathogenesis, suggesting that targeting Peli1 may have therapeutic effect in neuroinflammation.

Post-treatment with PT302, a long-acting Exendin-4 sustained release formulation, reduces dopaminergic neurodegeneration in a 6-Hydroxydopamine rat model of Parkinson's disease.

We previously demonstrated that pretreatment with Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, reduces 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -mediated dopaminergic neurodegeneration. The use of GLP-1 or Exendin-4 for Parkinson's disease (PD) patients is limited by their short half-lives. The purpose of this study was to evaluate a new extended release Exendin-4 formulation, PT302, in a rat model of PD. Subcutaneous administration of PT302 resulted in sustained elevations of Exendin-4 in plasma for >20 days in adult rats. To define an efficacious dose within this range, rats were administered PT302 once every 2 weeks either before or following the unilaterally 6-hydroxydopamine lesioning. Pre- and post-treatment with PT302 significantly reduced methamphetamine-induced rotation after lesioning. For animals given PT302 post lesion, blood and brain samples were collected on day 47 for measurements of plasma Exendin-4 levels and brain tyrosine hydroxylase immunoreactivity (TH-IR). PT302 significantly increased TH-IR in the lesioned substantia nigra and striatum. There was a significant correlation between plasma Exendin-4 levels and TH-IR in the substantia nigra and striatum on the lesioned side. Our data suggest that post-treatment with PT302 provides long-lasting Exendin-4 release and reduces neurodegeneration of nigrostriatal dopaminergic neurons in a 6-hydroxydopamine rat model of PD at a clinically relevant dose.

Updates on immunity and inflammation in Parkinson disease pathology.

Studies in the last decade have suggested the association of both neuroinflammatory processes and immune responses in Parkinson disease (PD) pathology. PD pathology is related to depleted dopamine levels, α-synuclein aggregation, and death of nigrostriatal dopaminergic neurons. Reports have suggested central and peripheral inflammation in the prodromal stage of the disease, which is sustained during disease progression. Alongside the activation of peripheral immune system exacerbates the dissonant central inflammatory responses and could contribute in synergistic neurodegeneration. Activated glial cells contribute significantly in the neuroinflammatory process during the occurrence of the disease and are also acknowledged as a hallmark of disease progression. However, the contribution of glial cells is not well defined in the context of neurodegeneration and neuroprotection. This review provides an overview of the roles of immune and inflammatory responses and their consequences in PD disease pathogenesis and also discusses possible therapeutic strategies for PD based on these findings.

Peripheral immune tolerance alleviates the intracranial lipopolysaccharide injection-induced neuroinflammation and protects the dopaminergic neurons from neuroinflammation-related neurotoxicity.

BACKGROUND: Neuroinflammation plays a critical role in the onset and development of neurodegeneration disorders such as Parkinson's disease. The immune activities of the central nervous system are profoundly affected by peripheral immune activities. Immune tolerance refers to the unresponsiveness of the immune system to continuous or repeated stimulation to avoid excessive inflammation and unnecessary by-stander injury in the face of continuous antigen threat. It has been proved that the immune tolerance could suppress the development of various peripheral inflammation-related diseases. However, the role of immune tolerance in neuroinflammation and neurodegenerative diseases was not clear. METHODS: Rats were injected with repeated low-dose lipopolysaccharide (LPS, 0.3 mg/kg) intraperitoneally for 4 days to induce peripheral immune tolerance. Neuroinflammation was produced using intracranial LPS (15 µg) injection. Inflammation cytokines were measured using enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Microglial activation were measured using immunostaining of Iba-1 and ED-1. Dopaminergic neuronal damage was evaluated using immunochemistry staining and stereological counting of TH-positive neurons. Behavioral impairment was evaluated using amphetamine-induced rotational behavioral assessment. RESULTS: Compared with the non-immune tolerated animals, pre-treatment of peripheral immune tolerance significantly decreased the production of inflammatory cytokines, suppressed the microglial activation, and increased the number of dopaminergic neuronal survival in the substantia nigra. CONCLUSIONS: Our results indicated that peripheral immune tolerance attenuated neuroinflammation and inhibited neuroinflammation-induced dopaminergic neuronal death.

[Immunohistochemical characteristics of the substantia nigra neurons of the human]. / Immunogistokhimicheskaia kharakteristika neironov chernogo veshchestva golovnogo mozga cheloveka.

AIM: To determine the cytochemical characteristics of unchanged neurons of the human substantia nigra using a wide range of immunocytochemical markers some of which (glutamate decarboxylase-65, PGP 9.5, non-phosphorylated neurofilament proteins, alpa-tubulin) have never been used for study of human dopaminergic neurons. MATERIAL AND METHODS: Fragments of human midbrain (17 men and women, aged from 28 to 78 years) from the archives of the Department of General and Specific Morphology of the Institute of Experimental Medicine were used. The study was performed using classical neurohistological techniques and immunocytochemistry using antibodies to 15 different proteins. RESULTS: Most neurons in substantia nigra exhibited a reduced expression of common neuronal markers such as neuronal nuclear protein NeuN, PGP 9.5 protein, and neuron-specific enolase. GABAergic (GAD65-immunopositive) neurons were not found in the substantia nigra. Single cholinergic neurons without neuromelanin were identified in the dorsal part of the substantia nigra. Calcium-binding proteins calbindin and calretinin were not found in the majority of nigral cells although calbindin was rarely seen in some neurons of the dorsal part and calretinin in the ventral one. Nitric oxide synthase (NOS) was present in the substantia nigra both in neuropil and neuronal bodies. CONCLUSION: The results suggest the unique cytochemical properties of the nigral neurons, which may be related to their increased susceptibility to lesion and degeneration.

Induction of Adaptive Immunity Leads to Nigrostriatal Disease Progression in MPTP Mouse Model of Parkinson's Disease.

Although the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model is the most widely used animal model for Parkinson's disease (PD), it is known that nigrostriatal pathologies do not persist in the acute MPTP mouse model. This study highlights the importance of adaptive immunity in driving persistent and progressive disease in acute MPTP-intoxicated mice. Although marked infiltration of T cells into the nigra was found on 1 d of MPTP insult, T cell infiltration decreased afterward, becoming normal on 30 d of insult. Interestingly, twice-weekly supplementation of RANTES and eotaxin, chemokines that are involved in T cell trafficking, drove continuous T cell infiltration to the nigra and incessant glial inflammation. Supplementation of RANTES and eotaxin was also associated with the induction of nigral α-synuclein pathology, persistent loss of dopaminergic neurons and striatal neurotransmitters, and continuous impairment of motor functions in MPTP-intoxicated mice. In contrast, supplementation of TNF-α and IL-1ß, widely studied proinflammatory cytokines, did not induce persistent disease in MPTP-insulted mice. Our results suggest that induction of adaptive immunity by RANTES and eotaxin could hold the key for driving persistent nigrostriatal pathologies in the MPTP mouse model, and that targeting these factors may halt disease progression in PD patients.

Injury-stimulated Sonic hedgehog expression in microglia contributes to neuroinflammatory response in the MPTP model of Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder in which dopamine (DA) neurons in the substantia nigra pars compacta (SNpc) region are selectively destroyed. Sonic hedgehog (Shh) has been well known to play a key role in a variety of processes such as embryogenesis, cell proliferation and protection, and tissue repair during inflammation. However, the evidences for the innate role of Shh in adult brain injury are presently lacking and studies have been needed to unveil the importance of Shh in the process of neurodegeneration. Here, we investigated the role of Shh in the pathologic progress of Parkinson's disease in MPTP-induced animal model system. Interestingly, we observed that Shh expression was gradually increased in MPTP affected SNpc region. Activated microglia exclusively expressed SHH in vivo and we could recapitulate Shh induction in activated cultured primary microglia cells. Using the SHH responsive Cre-loxP binary genetic reporter transgenic mouse system, we also found that most of the cell types except for oligodendrocyte in the SNpc region reacted to the SHH by MPTP injection. Taken together, activated microglia induced Shh expression and most neural cells except oligodendrocyte responded to microglia-derived SHH in MPTP-treated SN. These results suggest that SHH in activated microglia by MPTP-injection might be involved in the innate processes of recovery from neurotoxin induced injury in the PD animal model system.

Distinct alterations in motor & reward seeking behavior are dependent on the gestational age of exposure to LPS-induced maternal immune activation.

The dopaminergic system is involved in motivation, reward and the associated motor activities. Mesodiencephalic dopaminergic neurons in the ventral tegmental area (VTA) regulate motivation and reward, whereas those in the substantia nigra (SN) are essential for motor control. Defective VTA dopaminergic transmission has been implicated in schizophrenia, drug addiction and depression whereas dopaminergic neurons in the SN are lost in Parkinson's disease. Maternal immune activation (MIA) leading to in utero inflammation has been proposed to be a risk factor for these disorders, yet it is unclear how this stimulus can lead to the diverse disturbances in dopaminergic-driven behaviors that emerge at different stages of life in affected offspring. Here we report that gestational age is a critical determinant of the subsequent alterations in dopaminergic-driven behavior in rat offspring exposed to lipopolysaccharide (LPS)-induced MIA. Behavioral analysis revealed that MIA on gestational day 16 but not gestational day 12 resulted in biphasic impairments in motor behavior. Specifically, motor impairments were evident in early life, which were resolved by adolescence, but subsequently re-emerged in adulthood. In contrast, reward seeking behaviors were altered in offspring exposed MIA on gestational day 12. These changes were not due to a loss of dopaminergic neurons per se in the postnatal period, suggesting that they reflect functional changes in dopaminergic systems. This highlights that gestational age may be a key determinant of how MIA leads to distinct alterations in dopaminergic-driven behavior across the lifespan of affected offspring.