Abnormal immune function of B lymphocyte in peripheral blood of Parkinson's disease

Aberrations in peripheral B lymphocytes and B lymphocyte subsets levels in Parkinson disease: a systematic review

Objective

The association of B lymphocytes and B lymphocyte subsets and Parkinson's disease (PD) is increasingly acknowledged. However, there is inconsistence in the alterations of B lymphocytes or B lymphocyte subsets in peripheral blood of PD patients. To comprehensively understand its changes in PD patients,it is necessary to conduct a systematic review on this subject.

Methods

PubMed, Cochrane Library, and MEDLINE databases were searched until 3rd February 2024.

Results

We included 20 studies (n=2658) to conduct this systematic review. We conducted a qualitative analysis to assess the alterations of B lymphocytes and B lymphocyte subsets in the peripheral blood of individuals with PD. And studies reviewed demonstrated a significant decrease in the number of B cells, as well as immune dysregulation in the B lymphocyte subsets of these patients' peripheral blood.

Conclusion

Studies reviewed demonstrated that PD is linked to abnormalities in B lymphocytes and/or B lymphocytes subsets in peripheral blood. This study provides a novel perspective into the pathogenesis of PD, and future investigations into the B lymphocytes and/or B lymphocyte subsets as biomarkers and therapeutic targets for PD is warranted.

Soluble Immune Factor Profiles in Blood and CSF Associated with LRRK2 Mutations and Parkinson's Disease

Background and Objectives

Mutations in the Leucine-rich repeat kinase 2 (LRRK2) gene are one of the most common genetic causes of Parkinson's disease (PD) and are linked to immune dysregulation in both the central nervous system and periphery. However, peripheral and central profiles of soluble immune factors associated with LRRK2 mutations and PD have not been comprehensively characterized. Using serum and CSF samples from the LRRK2 Cohort Consortium (LCC), this study aimed to probe a broad range of soluble immune biomarkers associated with LRRK2 mutations and PD.

Methods

We investigated the levels of soluble immune regulators in the serum (n=651) and cerebrospinal fluid (CSF, n=129) of LRRK2 mutation carriers and non-carriers, both with and without PD. A total of 65 cytokines, chemokines, growth factors, and soluble receptors were assessed by Luminex immunoassay. A multivariable robust linear model was used to determine levels associated with LRRK2 mutations and PD status, adjusting for age, sex, and sample cohort. Correlations were assessed using the Spearman correlation coefficient. LRRK2 G2019S knock-in mice were used to validate the associations identified in the LCC.

Results

In this extensive discovery cohort, we identified several elevated serum immune regulatory factors associated with LRRK2 mutations. In particular, serum stromal cell-derived factor-1 alpha (SDF-1 alpha) levels, as supported by findings in LRRK2 G2019S knock-in mice, and tumor necrosis factor receptor II (TNF-RII) were significantly increased after multiple comparison adjustment. In contrast, LRRK2 mutations were associated with reduced soluble immune markers, including BAFF, CD40-Ligand, I-TAC, MIP-3 alpha, NGF beta, and IL-27 in CSF. Those with clinically diagnosed PD, with or without LRRK2 mutations, did not show strong signals in serum but reduced inflammatory analytes in CSF, including MIF, MMP-1, CD30, Tweak, and SDF-1 alpha. In addition, we found that the serum levels of these soluble immune factors display varied correlations with their corresponding CSF levels.

Discussion

This study highlights distinct immune profiles associated with LRRK2 mutations and PD in the periphery and CNS. Serum levels of SDF-1alpha and TNF-RII were elevated in LRRK2 mutation carriers, while CSF immune markers were reduced. In PD, irrespective of LRRK2 status, reduced CSF inflammatory analytes and weak serum signals were observed. These results provide insight into immune dysregulation linked to LRRK2 mutations. If replicable in independent datasets, they offer potential avenues for biomarker and therapeutic exploration.

Phenotypic alterations in peripheral blood B Lymphocytes of patients with Alzheimer's Disease

INTRODUCTION

Dysfunction of humoral immunity has been implicated in the pathogenesis of Alzheimer's disease (AD). The distribution of B lymphocyte subsets and their clinical relevance in AD remain unclear.

OBJECTIVE

In this study, we aimed to investigate the distribution of peripheral blood B lymphocyte subsets and their relevance with cognition and biomarkers in AD.

DESIGN, SETTING, AND PARTICIPANTS

We evaluated the immunophenotype of peripheral B lymphocytes in 27 AD patients confirmed by PET-Amyloid scan and 32 cognitively normal controls.

RESULTS

The phenotype of B lymphocytes is altered in AD patients. AD patients exhibit a decrease in both the numbers and proportions of switched memory (SwM) B cells and double-negative (DN) B cells. The proportion of unswitched memory (USwM) B cells was increased after in vitro stimulation. Additionally, B cells that produce proinflammatory cytokines including GM-CSF, IFN-γ, and TNF-α are increased, while those that produce the anti-inflammatory cytokine IL-10 are decreased in AD patients after in vitro stimulation. These alterations in B cell populations were linked to cognitive functions and biomarkers, including Aβ42/40 and pTau181, in AD patients.

DISCUSSION

This study reveals an altered B-lymphocyte phenotype in AD patients, marked by functional and compositional dysregulation. Further research incorporating mechanistic, longitudinal, and functional studies is needed to determine whether these immune perturbations directly contribute to AD pathogenesis or arise as secondary effects of neurodegeneration.

Frequencies of Circulating Immune Cells in Patients with Parkinson's Disease: Correlation with MDS-UPDRS Scores

BACKGROUND

Parkinson's Disease (PD) is associated with dysregulated/chronic inflammation. The immune system has multiple roles including beneficial effects such as clearing alpha synuclein aggregates. However, peripheral immune cells entering the brain may also contribute to inflammation and neurodegeneration. To identify which cells might have a negative impact and could be potential therapeutic targets, we compared immune signatures of patients and healthy controls.

METHODS

Multicolor flow cytometry was used to determine the frequencies of major immune cell subsets in peripheral blood mononuclear cells (PBMCs) of PD patients and controls. Because of the major impact of Cytomegalovirus (CMV) infection on the distribution of immune cell subsets, particularly cluster of differentiation (CD)8+ T-cells, all participants were tested for CMV seropositivity.

RESULTS

Although the cohort of 35 PD patients exhibited the well-established T-cell differentiation signature driven by CMV infection, there were no differences in the frequencies of differentiated or pro-inflammatory T-cells, B-cells or natural killer cells (NK-cells) attributable to the disease. However, percentages of myeloid-derived suppressor cells (MDSCs) were higher in PD patients than controls. Moreover, percentages of CD14+CD16+ (intermediate) monocytes expressing the C-C chemokine receptor type 5 (CCR5) correlated with disease severity assessed by the Movement Disorder Society's revised version of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) score and disease duration.

CONCLUSIONS

A comprehensive evaluation of the major subsets of circulating immune cells in PD patients revealed differences in myeloid cells between PD and healthy controls and some correlation of monocyte abundance with disease severity.

Immune Cell Distributions in the Blood of Healthy Individuals at High Genetic Risk of Parkinson's Disease

The immune system likely plays a key role in Parkinson's disease (PD) pathophysiology. Thus, we investigated whether immune cell compositions are already altered in healthy individuals at high genetic risk for PD. We quantified 92 immune cell subtypes in the blood of 442 individuals using multicolor flow cytometry. Polygenic risk scores (PGS) for PD were calculated based on genome-wide significant SNPs (n = 87) from a large genome-wide association study (n = 1,530,403). Linear regression analyses did not reveal significant associations between PGS and any immune cell subtype (FDR = 0.05). Nominally significant associations were observed for NKG2C+ B cells (p = 0.026) in the overall sample. Older participants at increased genetic PD risk also showed a higher proportion of myeloid dendritic cells (p = 0.019) and CD27+CD4+ memory T cells (p = 0.043). Several immune cells were nominally statistically associated in women only. These findings suggest that major alterations of immune cells only occur later in the progression of PD.

Pink1/Parkin deficiency alters circulating lymphocyte populations and increases platelet-T cell aggregates in rats

Parkinson's disease (PD) is the most common progressive neurodegenerative movement disorder and results from the selective loss of dopaminergic neurons in the substantia nigra pars compacta. Pink1 and Parkin are proteins that function together in mitochondrial quality control, and when they carry loss-of-function mutations lead to familial forms of PD. While much research has focused on central nervous system alterations in PD, peripheral contributions to PD pathogenesis are increasingly appreciated. We report Pink1/Parkin regulate glycolytic and mitochondrial oxidative metabolism in peripheral blood mononuclear cells (PBMCs) from rats. Pink1/Parkin deficiency induces changes in the circulating lymphocyte populations, namely increased CD4 + T cells and decreased CD8 + T cells and B cells. Loss of Pink1/Parkin leads to elevated platelet counts in the blood and increased platelet-T cell aggregation. Platelet-lymphocyte aggregates are associated with increased thrombosis risk suggesting targeting the Pink1/Parkin pathway in the periphery might have therapeutic potential.

The humoral immune landscape in Parkinson's disease: Unraveling antibody and B cell changes

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by the accumulation of α-synuclein (α-syn) in the brain and progressive loss of dopaminergic neurons in the substantia nigra (SN) region of the brain. Although the role of neuroinflammation and cellular immunity in PD has been extensively studied, the involvement of humoral immunity mediated by antibodies and B cells has received less attention. This article provides a comprehensive review of the current understanding of humoral immunity in PD. Here, we discuss alterations in B cells in PD, including changes in their number and phenotype. Evidence mostly indicates a decrease in the quantity of B cells in PD, accompanied by a shift in the population from naïve to memory cells. Furthermore, the existence of autoantibodies that target several antigens in PD has been investigated (i.e., anti-α-syn autoantibodies, anti-glial-derived antigen antibodies, anti-Tau antibodies, antineuromelanin antibodies, and antibodies against the renin-angiotensin system). Several autoantibodies are generated in PD, which may either provide protection or have harmful effects on disease progression. Furthermore, we have reviewed studies focusing on the utilization of antibodies as a potential treatment for PD, both in animal and clinical trials. This review sheds light on the intricate interplay between antibodies and the pathological processes in PD, including complement system activation.

Target engagement and immunogenicity of an active immunotherapeutic targeting pathological α-synuclein: a phase 1 placebo-controlled trial

Investigational therapeutics that target toxic species of α-synuclein (αSyn) aim to slow down or halt disease progression in patients with Parkinson's disease (PD). Here this 44-week, randomized, placebo-controlled, double-blind, single-center phase 1 study investigated safety, tolerability and immunogenicity of UB-312, an active immunotherapeutic targeting pathological αSyn, in patients with PD. The primary outcome measures were adverse event frequency and change in anti-αSyn antibody titers in blood and cerebrospinal fluid (CSF). Exploratory outcomes were changes in clinical scales and biomarker-based target engagement as measured by seed amplification assays. Twenty patients were randomized 7:3 (UB-312:placebo) into 300/100/100 μg or 300/300/300 μg (weeks 1, 5 and 13) intramuscular prime-boost dose groups. Safety was similar across groups; adverse events were mostly mild and transient. Two patients experienced three serious adverse events in total, one possibly treatment related; all resolved without sequalae. Anti-αSyn antibodies in serum from 12/13 and CSF from 5/13 patients who received three UB-312 doses confirmed immunogenicity. Mean serum titers (in log-dilution factor) increased from baseline by 1.398 and 1.354, and peaked at week 29 at 2.520 and 2.133, for 300/100/100 μg and 300/300/300 μg, respectively. CSF titers were 0 at baseline and were 0.182 and 0.032 at week 21, respectively. Exploratory analyses showed no statistical differences in clinical scales but a significant reduction of αSyn seeds in CSF of a subset of UB-312-treated patients. These data support further UB-312 development. ClinicalTrials.gov: NCT04075318 .

The role of peripheral inflammation-related biomarkers in distinguishing Parkinson's disease

BACKGROUND

Peripheral inflammation plays a significant role in Parkinson's disease (PD). Conflicting studies on whether inflammatory indicators in blood could serve as biomarkers to distinguish PD.

OBJECTIVE

Include a wider range of biomarkers and control confounding factors to comprehensively evaluate the value of peripheral inflammation-related indicators.

METHODS

A total of 80 PD patients were recruited and 80 one-to-one matched healthy controls (HCs). The levels of B-cell, T-cell, and natural killer (NK)-cell in blood were measured using flow cytometry. The levels of neurodegeneration-related proteins in serum were detected and clinical blood test results were collected. Multivariable logistic regression analysis was conducted to explore the role of significant variables in PD. Receiver operating characteristic curve analysis was performed to assess the potential value of these variables.

RESULTS

Compared to HCs, PD patients showed lower levels of lymphocyte, B-cell, T-cell, high-density lipoprotein cholesterol (HDL-C) and lymphocyte-to-monocyte ratio, while the levels of neutrophil, NK-cell, β-amyloid40, neurofilament light chain, neutrophil-to-lymphocyte ratio, and neutrophil-to-HDL-C ratio (NHR) were increased. A higher B-cell count was associated with a lower risk of PD, while higher levels of NK-cell and NHR were associated with a higher risk of PD. B-cell, NK-cell and NHR have potential value in distinguishing PD from non-PD. B-cell and NHR levels were significantly correlated with PD dyskinesia scores.

CONCLUSIONS

B-cell, NK-cell, and NHR may potentially contribute to distinguishing PD patients from HCs. There could be a correlation between the number of B-cell, the level of NHR, and the severity of PD dyskinesia.

Pink1/Parkin deficiency alters circulating lymphocyte populations and increases platelet-T cell aggregates in rats

Parkinson's disease (PD) is the most common progressive neurodegenerative movement disorder and results from the selective loss of dopaminergic neurons in the substantia nigra pars compacta. Pink1 and Parkin are proteins that function together in mitochondrial quality control, and when they carry loss-of-function mutations lead to familial forms of PD. While much research has focused on central nervous system alterations in PD, peripheral contributions to PD pathogenesis are increasingly appreciated. We report Pink1/Parkin regulate glycolytic and mitochondrial oxidative metabolism in peripheral blood mononuclear cells (PBMCs) from rats. Pink1/Parkin deficiency induces changes in the circulating lymphocyte populations, namely increased CD4 + T cells and decreased CD8 + T cells and B cells. Loss of Pink1/Parkin leads to elevated platelet counts in the blood and increased platelet-T cell aggregation. Platelet-lymphocyte aggregates are associated with increased thrombosis risk, and venous thrombosis is a cause of sudden death in PD, suggesting targeting the Pink1/Parkin pathway in the periphery has therapeutic potential.

Exploring the causal relationship between B lymphocytes and Parkinson's disease: a bidirectional, two-sample Mendelian randomization study

Parkinson's disease (PD) is a neurodegenerative disorder with extensive involvement of motor symptoms, imposing a heavy economic burden on patients and society. B lymphocytes, a group of immune cells associated with humoral immunity, have been shown to be involved in the pathogenesis of PD. However, the causal relationship and potential pathogenic effects of B cell in PD remain unclear. Based on the three core hypotheses of the Mendelian randomization (MR) study, we explored causal associations between 190 B-cell immunological traits and 482,730 European individuals (Ncase = 33,674, Ncontrol = 449,056) from genome wide association studies by means of the two-sample bidirectional MR method. The inverse‑variance weighted method was selected as the main approach when conducting MR analysis. Finally, the results were verified by the heterogeneity and horizontal pleiotropy analyses. Five B-cell immunological phenotypes were nominally associated with PD at the significance threshold of P < 0.05. Concretely, IgD + CD38- B cell %lymphocyte (OR 1.052, 95% CI 1.001-1.106, P = 0.046), CD20 on IgD- CD24- B cell (OR 1.060, 95% CI 1.005-1.117, P = 0.032), CD38 on IgD+ CD24- B cell (OR 1.113, 95% CI 1.028-1.206, P = 0.009), and BAFF-R on CD20- B cell (OR 1.093, 95% CI 1.010-1.184, P = 0.027) were identified as risk factors for PD. Instead, CD38 on Plasma Blast-Plasma Cell (OR 0.894, 95% CI 0.802-0.996, P = 0.043) was proved to be protective. However, there is no statistically significant correlation between B cell and PD after Bonferroni correction. The results of reverse MR were negative, avoiding the reverse causal effects. Eventually, the association results were identified as stable across several sensitivity analyses. Briefly, our study might demonstrate the key factor of B cells in PD. Further studies are warranted to clarify the associations for early identification and immunotherapeutic development in PD patients.