Alterations of Peripheral Lymphocyte Subsets in Isolated Rapid Eye Movement Sleep Behavior Disorder.

BACKGROUND: Adaptive immune dysfunction may play a crucial role in Parkinson's disease (PD) development. Isolated rapid eye movement sleep behavior disorder (iRBD) represents the prodromal stage of synucleinopathies, including PD. Elucidating the peripheral adaptive immune system is crucial in iRBD, but current knowledge remains limited. OBJECTIVE: This study aimed to characterize peripheral lymphocyte profiles in iRBD patients compared with healthy control subjects (HCs). METHODS: This cross-sectional study recruited polysomnography-confirmed iRBD patients and age- and sex-matched HCs. Venous blood was collected from each participant. Flow cytometry was used to evaluate surface markers and intracellular cytokine production in peripheral blood mononuclear cells. RESULTS: Forty-four iRBD patients and 36 HCs were included. Compared with HCs, patients with iRBD exhibited significant decreases in absolute counts of total lymphocytes and CD3+ T cells. In terms of T cell subsets, iRBD patients showed higher frequencies and counts of proinflammatory T helper 1 cells and INF-γ+ CD8+ T cells, along with lower frequencies and counts of anti-inflammatory T helper 2 cells. A significant increase in the frequency of central memory T cells in CD8+ T cells was also observed in iRBD. Regarding B cells, iRBD patients demonstrated reduced frequencies and counts of double-negative memory B cells compared with control subjects. CONCLUSIONS: This study demonstrated alterations in the peripheral adaptive immune system in iRBD, specifically in CD4+ and INF-γ+ CD8+ T cell subsets. An overall shift toward a proinflammatory state of adaptive immunity was already evident in iRBD. These observations might provide insights into the optimal timing for initiating immune interventions in PD. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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.

Plasma immune markers in an idiopathic REM sleep behavior disorder cohort.

INTRODUCTION: Increasing evidence shows a strong association between idiopathic REM sleep behavior disorder (iRBD) and α-synucleinopathies. Recent studies have indicated an inflammatory mechanism in the pathogenesis of α-synucleinopathies. Whether peripheral inflammatory cytokines are altered in iRBD and can be biomarkers for predicting phenoconversion remains unclear. METHODS: We collected baseline plasma samples from 77 consecutive iRBD patients and 64 age- and sex-matched healthy controls. Ten cytokines were measured: Interferon (IFN)-γ, interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, and tumor necrosis factor (TNF)-α. All iRBD patients underwent clinical assessment tests at baseline, and 75 were prospectively followed and received assessments for parkinsonism or dementia. Cox regression analyses were used to evaluate the predictive value of plasma cytokines in a follow-up period of 6.0 years. RESULTS: TNF-α and IL-10 were significantly elevated in iRBD compared with controls (both p < 0.001). IL-6/IL-10 and IL-8/IL-10 were significantly reduced in iRBD than in controls (p = 0.001, p < 0.001, respectively). After a median follow-up of 3.7 years, 16 iRBD patients developed neurodegenerative synucleinopathies. iRBD patients with higher TNF-α/IL-10 levels were more likely to develop neurodegenerative diseases (adjusted HR 1.07, 95% CI 1.01-1.14). The coexistence of elevated TNF-α/IL-10 and possible mild cognitive impairment predicted an early conversion of iRBD to neurodegenerative synucleinopathies (adjusted HR 4.17, 95% CI 1.47-11.81). CONCLUSIONS: Our study supported the early involvement of peripheral inflammation in prodromal α-synucleinopathy. Plasma cytokines may be predictive of disease conversion in iRBD, while large-scale longitudinal studies are warranted to validate the assumption.

Assessment of neuroinflammation in patients with idiopathic rapid-eye-movement sleep behaviour disorder: a case-control study.

BACKGROUND: Findings from longitudinal follow-up studies in patients with idiopathic rapid-eye-movement sleep behaviour disorder (IRBD) have shown that most patients will eventually develop the synucleinopathies Parkinson's disease, dementia with Lewy bodies, or multiple system atrophy. Neuroinflammation in the form of microglial activation is present in synucleinopathies and is a potential therapeutic target to halt or delay the neurodegenerative process. We aimed to investigate whether neuroinflammation is present in patients with IRBD and its possible relation to nigrostriatal dopamine function. METHODS: In this prospective, case-control, PET study, patients with IRBD and no clinical evidence of parkinsonism and cognitive impairment were recruited from tertiary sleep centres in Spain (Barcelona) and Denmark (Aarhus). We included patients with polysomnography-confirmed IRBD according to established criteria. Healthy controls were recruited through newspaper advertisements. Controls had no motor or cognitive complaints, a normal neurological examination, and a mean group age similar to the IRBD group. In patients with IRBD, we assessed microglial activation in the substantia nigra, putamen, and caudate with 11C-PK11195 PET, and dopaminergic axon terminal function in the putamen and caudate with 18F-DOPA PET. Controls underwent either 11C-PK11195 PET or 18F-DOPA PET. We compared 18F-DOPA uptake and 11C-PK11195 binding potential between groups with an unpaired, two-tailed Student's t test. FINDINGS: Between March 23, 2015, and Oct 19, 2016, we recruited 20 consecutive patients with IRBD and 19 healthy controls. 11C-PK11195 binding was increased on the left side of the substantia nigra in patients with IRBD compared with controls (Student's t test, mean difference 0·153 [95% CI 0·055 to 0·250], p=0·003), but not on the right side (0·121 [-0·007 to 0·250], p=0·064). 11C-PK11195 binding was not significantly increased in the putamen and caudate of patients with IRBD. 18F-DOPA uptake was reduced in IRBD in the left putamen (-0·0032 [-0·0044 to -0·0021], p<0·0001) and right putamen (-0·0032 [-0·0044 to -0·0020], p<0·0001), but not in the caudate. INTERPRETATION: In patients with IRBD, increased microglial activation was detected by PET in the substantia nigra along with reduced dopaminergic function in the putamen. Further studies, including more participants than were in this study and longitudinal follow-up, are needed to support our findings and evaluate whether the presence of activated microglia in patients with IRBD represents a marker of short-term conversion to a clinically defined synucleinopathy in the near future. FUNDING: Danish Council for Independent Research, Instituto de Salud Carlos III (Spain).

Rapid Eye Movement Sleep Behavior Disorder in Paraneoplastic Cerebellar Degeneration: Improvement with Immunotherapy.

STUDY OBJECTIVES: To report two female patients with paraneoplastic cerebellar degeneration (PCD) related to breast cancer that presented with rapid eye movement-sleep behavior disorder (RBD) and improved sleep symptoms with immunotherapy. METHODS: The two patients were evaluated through clinical scale and polysomnography before and after therapy with intravenous immunoglobulin. RESULTS: RBD was successfully treated with immunotherapy in both patients. Score on the RBD screening questionnaire dropped from 10 to 1 or 0, allied with the normalization of polysomnographic findings. CONCLUSIONS: A marked improvement in RBD after immunotherapy in PCD raises the hypothesis that secondary RBD may be an immune-mediated sleep disorder.

Narcolepsy, REM sleep behavior disorder, and supranuclear gaze palsy associated with Ma1 and Ma2 antibodies and tonsillar carcinoma.

OBJECTIVE: To describe a patient with diencephalic and mesencephalic presentation of a Ma1 and Ma2 antibody-associated paraneoplastic neurological disorder. DESIGN: Case report. SETTING: The Colorado Neurological Institute Movement Disorders Center in Englewood, Colorado, and the Mayo Clinic in Rochester, Minnesota. PATIENT: A 55-year-old man with a paraneoplastic neurological disorder characterized by rapid eye movement sleep behavior disorder, narcolepsy, and a progressive supranuclear palsy-like syndrome in the setting of tonsillar carcinoma. INTERVENTION: Immunotherapy for paraneoplastic neurological disorder, surgery and radiotherapy for cancer, and symptomatic treatment for parkinsonism and sleep disorders. MAIN OUTCOME MEASURES: Polysomnography, multiple sleep latency test, and neurological examination. RESULTS: The cancer was detected at a limited stage and treatable. After oncological therapy and immunotherapy, symptoms stabilized. Treatment with modafinil improved daytime somnolence. CONCLUSIONS: Rapid onset and progression of multifocal deficits may be a clue to paraneoplastic etiology. Early treatment of a limited stage cancer (with or without immunotherapy) may possibly slow progression of neurological symptoms. Symptomatic treatment may be beneficial.

Changing demographics in REM sleep behavior disorder: possible effect of autoimmunity and antidepressants.

BACKGROUND: Rapid eye movement (REM) sleep behavior disorder (RBD) has been described predominantly in elderly men and in association with neurodegenerative disease. But an increasing proportion of cases in recent reports and in clinical practice do not fit this description; thus we sought to describe a current RBD population and possibly identify new subgroups with RBD. METHODS: Records of 115 consecutive patients with polysomnogram-confirmed RBD at an academic sleep center were retrospectively reviewed. RESULTS: Male to female ratio was 2:1, and 1.25:1 for early-onset (age <50) cases. Mean age at diagnosis was 53.7±16.4years. Most (60%) cases were idiopathic, and neurodegenerative disease was coincident primarily in older men. Autoimmune disease was unexpectedly common in women (20%) particularly in the 30-49 age groups (40%). Antidepressant use was frequent (46.1%), especially in early-onset cases (57.8%). CONCLUSIONS: RBD is diagnosed more equally between men and women and in younger individuals than previously reported. While neurodegenerative disease is frequently co-incident with RBD in older men, most women and early-onset cases have "idiopathic" RBD. High prevalence of autoimmune disease among women with RBD suggests an intriguing link between immune dysfunction and RBD. A high rate of antidepressant use provides support for a potentially causal role for antidepressants in RBD.

REM sleep behavior disorder and narcoleptic features in anti-Ma2-associated encephalitis.

A 69-year-old man with anti-Ma2 paraneoplastic encephalitis presented with subacute onset of severe hypersomnia, memory loss, parkinsonism, and gaze palsy. A brain magnetic resonance imaging study showed bilateral damage in the dorsolateral midbrain, amygdala, and paramedian thalami. Videopolysomnography disclosed rapid eye movement (REM) sleep behavior disorder, and a Multiple Sleep Latency Test showed a mean sleep latency of 7 minutes and 4 sleep-onset REM periods. The level of hypocretin-1 in the cerebrospinal fluid was low (49 pg/mL). This observation illustrates that REM sleep behavior disorder and narcoleptic features are 2 REM-sleep abnormalities that (1) may share the same autoimmune-mediated origin affecting the brainstem, limbic, and diencephalic structures and (2) may occur in the setting of the paraneoplastic anti-Ma2-associated encephalitis.

Rapid eye movement sleep behavior disorder and potassium channel antibody-associated limbic encephalitis.

Of six patients registered in our center with nonparaneoplastic limbic encephalitis associated with antibodies to voltage-gated potassium channels, the five men had rapid eye movement sleep behavior disorder (RBD) coincident with voltage-gated potassium channel antibody-associated limbic encephalitis onset. In three patients, immunosuppression resulted in resolution of RBD in parallel with remission of the limbic syndrome. RBD persisted in two patients with partial resolution of the limbic syndrome. Our findings suggest that RBD is frequent in the setting of voltage-gated potassium channel antibody-associated limbic encephalitis and can be related to autoimmune-mediated mechanisms. In addition, these observations suggest that impairment of the limbic system may play a role in the pathogenesis of RBD.