Treatment for Helicobacter pylori infection and risk of Parkinson's disease in Denmark

Update: Protective and risk factors for Parkinson disease

We review the epidemiologic literature on potential protective and risk factors in Parkinson's Disease (PD). Prior research identified numerous possible protective and risk factors. Potential protective factors include tobacco abuse, physical activity, urate levels, NSAID use, calcium channel blocker use, statin use, and use of some α1-adrenergic antagonists. Some potential protective factors could be products of reverse causation, including increased serum urate, tobacco abuse, and coffee-tea-caffeine consumption. Potential risk factors include traumatic brain injury, pesticide exposure, organic solvent exposure, lead exposure, air pollution, Type 2 Diabetes, some dairy products, cardiovascular disease, and some infections including Hepatitis C, H. pylori, and COVID-19. Potential non-environmental risk factors include bipolar disorder, essential tremor, bullous pemphigoid, and inflammatory bowel disease. There is an inverse relationship with PD and risk of most cancers. Though many potential protective and risk factors for PD were identified, research has not yet led to unique, rigorous prevention trials or successful disease-modifying interventions. While efforts to reduce exposure to some industrial toxicants are well justified, PD incidence might be most effectively reduced by mitigation of risks, such as Type 2 Diabetes, air pollution, traumatic brain injury, or physical inactivity, that are general public health intervention targets.

PARK7/DJ-1 deficiency impairs microglial activation in response to LPS-induced inflammation

BACKGROUND

Specific microglia responses are thought to contribute to the development and progression of neurodegenerative diseases, including Parkinson's disease (PD). However, the phenotypic acquisition of microglial cells and their role during the underlying neuroinflammatory processes remain largely elusive. Here, according to the multiple-hit hypothesis, which stipulates that PD etiology is determined by a combination of genetics and various environmental risk factors, we investigate microglial transcriptional programs and morphological adaptations under PARK7/DJ-1 deficiency, a genetic cause of PD, during lipopolysaccharide (LPS)-induced inflammation.

METHODS

Using a combination of single-cell RNA-sequencing, bulk RNA-sequencing, multicolor flow cytometry and immunofluorescence analyses, we comprehensively compared microglial cell phenotypic characteristics in PARK7/DJ-1 knock-out (KO) with wildtype littermate mice following 6- or 24-h intraperitoneal injection with LPS. For translational perspectives, we conducted corresponding analyses in human PARK7/DJ-1 mutant induced pluripotent stem cell (iPSC)-derived microglia and murine bone marrow-derived macrophages (BMDMs).

RESULTS

By excluding the contribution of other immune brain resident and peripheral cells, we show that microglia acutely isolated from PARK7/DJ-1 KO mice display a distinct phenotype, specially related to type II interferon and DNA damage response signaling, when compared with wildtype microglia, in response to LPS. We also detected discrete signatures in human PARK7/DJ-1 mutant iPSC-derived microglia and BMDMs from PARK7/DJ-1 KO mice. These specific transcriptional signatures were reflected at the morphological level, with microglia in LPS-treated PARK7/DJ-1 KO mice showing a less amoeboid cell shape compared to wildtype mice, both at 6 and 24 h after acute inflammation, as also observed in BMDMs.

CONCLUSIONS

Taken together, our results show that, under inflammatory conditions, PARK7/DJ-1 deficiency skews microglia towards a distinct phenotype characterized by downregulation of genes involved in type II interferon signaling and a less prominent amoeboid morphology compared to wildtype microglia. These findings suggest that the underlying oxidative stress associated with the lack of PARK7/DJ-1 affects microglia neuroinflammatory responses, which may play a causative role in PD onset and progression.

Helicobacter pylori infection is a risk factor for constipation in patients with Parkinson's disease: A multicenter prospective cohort study

BACKGROUND AND AIMS

Constipation is one of the most common nonmotor symptoms (NMSs) of Parkinson's disease (PD). The infection rate of Helicobacter pylori (HP) is greater in PD patients. This study was a multicenter prospective cohort study in which propensity score matching (PSM) was used to determine whether HP infection was a risk factor for constipation in patients with PD.

METHODS

A total of 932 PD patients with 13C-urea breath test for HP were included in the study. The PSM was estimated with the use of a nonparsimonious multivariate logistic regression model, with HP infection as the dependent variable and all the baseline characteristics as covariates. A total of 697 patients composed the study cohort, including 252 (36.2 %) patients in the HP-positive (HPP) group and 445 (63.8 %) patients in the HP-negative (HPN) group. Before PSM, there were differences in several of the baseline variables between the two groups. After PSM, 250 HPP patients were matched with 250 HPN patients and the standardized differences were less than 0.1 for all variables.

RESULTS

The present results demonstrate that HP infection is a risk factor for constipation in patients with PD [RR (95 % CI) 1.412 (1.155-1.727), P < 0.001]. Subgroup analyses revealed that HP infection was both a risk factor for constipation in Hoehn-Yahr scale (1,1.5) group and Hoehn-Yahr scale (2-5) group [OR (95 % CI) 1.811 (1.079-3.038), P < 0.025; OR (95 % CI) 2.041 (1.177-3.541), P < 0.011].

CONCLUSIONS

The results of our prospective cohort study suggest that Helicobacter pylori infection is a risk factor for constipation in patients with PD.

TRIAL REGISTRATION

ChiCTR2300071631.

Potential risk of proton pump inhibitors for Parkinson's disease: A nationwide nested case-control study

Proton pump inhibitor (PPI) use is a potential risk factor for neurodegenerative disease development; however, its role in Parkinson's disease (PD) remains unclear. This study aimed to investigate the association between PPI use and PD risk. A total of 31,326 patients with newly diagnosed PD were matches by age, sex, body mass index, diabetes, and hypertension with 125,304 controls at a ratio of 1:4. The data were collected from the Korean National Health Insurance Services Database from January 2010 to December 2019. Cumulative defined daily doses of PPIs were extracted from treatment claims. We examined the association between PPI use and PD risk using conditional logistic regression. To prevent protopathic bias, we excluded patients diagnosed with PD within a 1-year lag period after PPI exposure. We applied 2- and 3-year lag periods for sensitivity analysis. PPI use was associated with an increased risk of PD when a 1-year lag period was applied between PPI exposure and PD development (adjusted odds ratio, 1.10; 95% confidence interval, 1.07-1.13). A significant positive dose-response relationship existed between the cumulative defined daily doses of PPIs and PD development (P<0.001). Similar results were obtained for the 2- or 3-year lag periods. The association did not vary based on gender. Older age, a higher Charlson Comorbidity Index score, no alcohol consumption, and a non-smoking status were associated with a significantly increased PD risk with PPI use. We observed an association between PPI use and PD risk, although long-term follow-up studies are necessary to verify this association.

Should evidence of an autolysosomal de-acidification defect in Alzheimer and Parkinson diseases call for caution in prescribing chronic PPI and DMARD?

Nearly fifty million older people suffer from neurodegenerative diseases, including Alzheimer (AD) and Parkinson (PD) disease, a global burden expected to triple by 2050. Such an imminent "neurological pandemic" urges the identification of environmental risk factors that are hopefully avoided to fight the disease. In 2022, strong evidence in mouse models incriminated defective lysosomal acidification and impairment of the autophagy pathway as modifiable risk factors for dementia. To date, the most prescribed lysosomotropic drugs are proton pump inhibitors (PPIs), chloroquine (CQ), and the related hydroxychloroquine (HCQ), which belong to the group of disease-modifying antirheumatic drugs (DMARDs). This commentary aims to open the discussion on the possible mechanisms connecting the long-term prescribing of these drugs to the elderly and the incidence of neurodegenerative diseases.Abbreviations: AD: Alzheimer disease; APP-βCTF: amyloid beta precursor protein-C-terminal fragment; BACE1: beta-secretase 1; BBB: brain blood barrier; CHX: Ca2+/H+ exchanger; CMI: cognitive mild impairment; CQ: chloroquine; DMARD: disease-modifying antirheumatic drugs; GBA1: glucosylceramidase beta 1; HCQ: hydroxychloroquine; HPLC: high-performance liquid chromatography; LAMP: lysosomal associated membrane protein; MAPK/JNK: mitogen-activated protein kinase; MAPT: microtubule associated protein tau; MCOLN1/TRPML1: mucolipin TRP cation channel 1; NFE2L2/NRF2: NFE2 like bZIP transcription factor 2; NRBF2: nuclear receptor binding factor 2; PANTHOS: poisonous flower; PD: Parkinson disease; PIK3C3: phosphatIdylinositol 3-kinase catalytic subunit type 3; PPI: proton pump inhibitor; PSEN1: presenilin 1, RUBCN: rubicon autophagy regulator; RUBCNL: rubicon like autophagy enhancer; SQSTM1: sequestosome 1; TMEM175: transmembrane protein 175; TPCN2: two pore segment channel 2; VATPase: vacuolar-type H+-translocating ATPase; VPS13C: vacuolar protein sorting ortholog 13 homolog C; VPS35: VPS35 retromer complex component; WDFY3: WD repeat and FYVE domain containing 3; ZFYVE1: zinc finger FYVE-type containing 1.

The Role of Helicobacter pylori and Small Intestinal Bacterial Overgrowth in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder whose etiology remains largely unexplained. Several studies have aimed to describe a causative effect in the interactions between the gastrointestinal tract and the brain, for both PD pathogenesis and disease course. However, the results have been controversial. Helicobacter pylori and small intestinal bacterial overgrowth (SIBO) are theorized to be agents capable of triggering chronic proinflammatory changes with a possible neurotoxic effect, as well as a cause of erratic L-dopa response in PD patients. This review evaluates the individual and possibly synergistic influence of H. pylori and SIBO on PD, to provide an opportunity to consider prospective therapeutic approaches.

GSDMD in peripheral myeloid cells regulates microglial immune training and neuroinflammation in Parkinson's disease

Peripheral bacterial infections without impaired blood-brain barrier integrity have been attributed to the pathogenesis of Parkinson's disease (PD). Peripheral infection promotes innate immune training in microglia and exacerbates neuroinflammation. However, how changes in the peripheral environment mediate microglial training and exacerbation of infection-related PD is unknown. In this study, we demonstrate that GSDMD activation was enhanced in the spleen but not in the CNS of mice primed with low-dose LPS. GSDMD in peripheral myeloid cells promoted microglial immune training, thus exacerbating neuroinflammation and neurodegeneration during PD in an IL-1R-dependent manner. Furthermore, pharmacological inhibition of GSDMD alleviated the symptoms of PD in experimental PD models. Collectively, these findings demonstrate that GSDMD-induced pyroptosis in myeloid cells initiates neuroinflammation by regulating microglial training during infection-related PD. Based on these findings, GSDMD may serve as a therapeutic target for patients with PD.

Chaudhuri's Dashboard of Vitals in Parkinson's syndrome: an unmet need underpinned by real life clinical tests

We have recently published the notion of the "vitals" of Parkinson's, a conglomeration of signs and symptoms, largely nonmotor, that must not be missed and yet often not considered in neurological consultations, with considerable societal and personal detrimental consequences. This "dashboard," termed the Chaudhuri's vitals of Parkinson's, are summarized as 5 key vital symptoms or signs and comprise of (a) motor, (b) nonmotor, (c) visual, gut, and oral health, (d) bone health and falls, and finally (e) comorbidities, comedication, and dopamine agonist side effects, such as impulse control disorders. Additionally, not addressing the vitals also may reflect inadequate management strategies, leading to worsening quality of life and diminished wellness, a new concept for people with Parkinson's. In this paper, we discuss possible, simple to use, and clinically relevant tests that can be used to monitor the status of these vitals, so that these can be incorporated into clinical practice. We also use the term Parkinson's syndrome to describe Parkinson's disease, as the term "disease" is now abandoned in many countries, such as the U.K., reflecting the heterogeneity of Parkinson's, which is now considered by many as a syndrome.

Gastrointestinal Dysfunction in Parkinson's Disease: Neuro-Gastroenterology Perspectives on a Multifaceted Problem

Patients with Parkinson's disease (PD) face a multitude of gastrointestinal (GI) symptoms, including nausea, bloating, reduced bowel movements, and difficulties with defecation. These symptoms are common and may accumulate during the course of PD but are often under-recognized and challenging to manage. Objective testing can be burdensome to patients and does not correlate well with symptoms. Effective treatment options are limited. Evidence is often based on studies in the general population, and specific evidence in PD is scarce. Upper GI dysfunction may also interfere with the pharmacological treatment of PD motor symptoms, which poses significant management challenges. Several new less invasive assessment tools and novel treatment options have emerged in recent years. The current review provides an overview and a practical approach to recognizing and diagnosing common upper and lower GI problems in PD, e.g., dyspepsia, gastroparesis, small bowel dysfunction, chronic constipation, and defecatory dysfunction. Management aspects are discussed based on the latest evidence from the PD and general populations, with insights for future research pertaining to GI dysfunction in PD.

A functional role for alpha-synuclein in neuroimmune responses

Alpha-synuclein is a neuronal protein with unclear function but is associated with the pathogenesis of Parkinson's disease and other synucleinopathies. In this review, we discuss the emerging functional role of alpha-synuclein in support of the unique immune responses in the nervous system. Recent data now show that alpha-synuclein functions to support interferon signaling within neurons and is released from neurons to support chemoattraction and activation of local glial cells and infiltrating immune cells. Inflammatory activation and interferon signaling also induce post-translational modifications of alpha-synuclein that are commonly associated with Parkinson's disease pathogenesis. Taken together, emerging data implicate complex interactions between alpha-synuclein and host immune responses that may contribute to the pathogenesis of Parkinson's disease. Additional study of the function of alpha-synuclein in the brain's immune response may provide disease-modifying therapeutic targets for Parkinson's disease in the future.

Infections and Changes in Commensal Bacteria and the Pathogenesis of Parkinson’s Disease

The cause of Parkinson’s disease (PD) is unknown, but environmental factors are purported to influence risk. Interest in PD as a sequel of infection dates back to reports of parkinsonism arising from encephalitis lethargica. The objective of this paper is to review the literature as it relates to infections and changes in microbiome and the genesis of PD. There is evidence to support prior infection with Helicobacter pylori, hepatitis C virus, Malassezia, and Strep pneumonia in association with PD. A large number of studies support an association between changes in commensal bacteria, especially gut bacteria, and PD. Extant literature supports a role for some infections and changes in commensal bacteria in the genesis of PD. Studies support an inflammatory mechanism for this association, but additional research is required for translation of these findings to therapeutic options.

The relationship between Parkinson's disease and gastrointestinal diseases

An increasing number of studies have provided evidence for the hypothesis that the pathogenesis of Parkinson's disease (PD) may derive from the gut. Firstly, Lewy pathology can be induced in the enteric nervous system (ENS) and be transported to the central nervous system (CNS) via the vagal nerve. Secondly, the altered composition of gut microbiota causes an imbalance between beneficial and deleterious microbial metabolites which interacts with the increased gut permeability and the gut inflammation as well as the systemic inflammation. The activated inflammatory status then affects the CNS and promotes the pathology of PD. Given the above-mentioned findings, researchers start to pay attention to the connection between PD and gastrointestinal diseases including irritable bowel syndrome, inflammatory bowel disease (IBD), microscopic colitis (MC), gastrointestinal infections, gastrointestinal neoplasms, and colonic diverticular disease (CDD). This review focuses on the association between PD and gastrointestinal diseases as well as the pathogenesis of PD from the gut.

Update to the Treatment of Parkinson's Disease Based on the Gut-Brain Axis Mechanism

Gastrointestinal (GI) symptoms represented by constipation were significant non-motor symptoms of Parkinson’s disease (PD) and were considered early manifestations and aggravating factors of the disease. This paper reviewed the research progress of the mechanism of the gut-brain axis (GBA) in PD and discussed the roles of α-synuclein, gut microbiota, immune inflammation, neuroendocrine, mitochondrial autophagy, and environmental toxins in the mechanism of the GBA in PD. Treatment of PD based on the GBA theory has also been discussed, including (1) dietary therapy, such as probiotics, vitamin therapy, Mediterranean diet, and low-calorie diet, (2) exercise therapy, (3) drug therapy, including antibiotics; GI peptides; GI motility agents, and (4) fecal flora transplantation can improve the flora. (5) Vagotomy and appendectomy were associated but not recommended.

The microbiome-gut-brain axis in Parkinson disease - from basic research to the clinic

Evidence for a close bidirectional link between the brain and the gut has led to a paradigm shift in neurology, especially in the case of Parkinson disease (PD), in which gastrointestinal dysfunction is a prominent feature. Over the past decade, numerous high-quality preclinical and clinical publications have shed light on the highly complex relationship between the gut and the brain in PD, providing potential for the development of new biomarkers and therapeutics. With the advent of high-throughput sequencing, the role of the gut microbiome has been specifically highlighted. Here, we provide a critical review of the literature on the microbiome-gut-brain axis in PD and present perspectives that will be useful for clinical practice. We begin with an overview of the gut-brain axis in PD, including the potential roles and interrelationships of the vagus nerve, α-synuclein in the enteric nervous system, altered intestinal permeability and inflammation, and gut microbes and their metabolic activities. The sections that follow synthesize the proposed roles of gut-related factors in the development and progression of, in responses to PD treatment, and as therapeutic targets. Finally, we summarize current knowledge gaps and challenges and delineate future directions for the field.

Reducing neuroinflammation via therapeutic compounds and lifestyle to prevent or delay progression of Parkinson's disease

Parkinson's disease (PD) is the second most common age-associated neurodegenerative disorder and is characterised by progressive loss of dopamine neurons in the substantia nigra. Peripheral immune cell infiltration and activation of microglia and astrocytes are observed in PD, a process called neuroinflammation. Neuroinflammation is a fundamental response to protect the brain but, when chronic, it triggers neuronal damage. In the last decade, central and peripheral inflammation were suggested to occur at the prodromal stage of PD, sustained throughout disease progression, and may play a significant role in the pathology. Understanding the pathological mechanisms of PD has been a high priority in research, primarily to find effective treatments once symptoms are present. Evidence indicates that early life exposure to neuroinflammation as a consequence of life events, environmental or behaviour factors such as exposure to infections, pollution or a high fat diet increase the risk of developing PD. Many studies show healthy habits and products that decrease neuroinflammation also reduce the risk of PD. Here, we aim to stimulate discussion about the role of neuroinflammation in PD onset and progression. We highlight that reducing neuroinflammation throughout the lifespan is critical for preventing idiopathic PD, and present epidemiological studies that detail risk and protective factors. It is possible that introducing lifestyle changes that reduce neuroinflammation at the time of PD diagnosis may slow symptom progression. Finally, we discuss compounds and therapeutics to treat the neuroinflammation associated with PD.

Movement Disorders and the Gut: A Review

There is a close link between multiple movement disorders and gastrointestinal dysfunction. Gastrointestinal symptoms may precede the development of the neurologic syndrome or may arise following the neurologic presentation. This review will provide an overview of gastrointestinal accompaniments to several well-known as well as lesser known movement disorders. It will also highlight several disorders which may not be considered primary movement disorders but have an overlapping presentation of both gastrointestinal and movement abnormalities.

Association between Proton Pump Inhibitor Use and Parkinson's Disease in a Korean Population

Few studies have shown an increased risk of Parkinson’s disease (PD) with the use of proton pump inhibitors (PPIs), and the pathophysiological mechanism for this association has not been unveiled. This study examined the relationship between PPI use and PD in a Korean population. We investigated 3026 PD patients and 12,104 controls who were matched by age, sex, income, and region of residence at a ratio of 1:4 in the Korean National Health Insurance Service, National Sample Cohort between 2002 and 2015. We estimated the associations between current and past use of PPIs and PD using odds ratios (ORs) and 95% confidence intervals (CIs) in a conditional/unconditional logistic regression after adjusting for probable confounders. Compared with PPI nonusers, both current users and past users had significantly greater odds of having PD, with ORs of 1.63 (95% CI = 1.44−1.84) and 1.12 (95% CI = 1.01−1.25), respectively. A significant association with PD was observed in individuals who used PPIs for 30−90 days and ≥90 days (OR = 1.26 and 1.64, 95% CI = 1.12−1.43 and 1.43−1.89) but not among those who used PPIs for <30 days. Both current and past use of PPIs associated with a higher probability of PD in the Korean population. Our study provides evidence regarding the association between PPI exposure and PD, but further investigation and possible explanations are warranted.

Intestinal Inflammation and Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease which significantly influences the life quality of patients. The protein α-synuclein plays an important driving role in PD occurrence and development. Braak's hypothesis suggests that α-synuclein is produced in intestine, and then spreads into the central nervous system through the vagus nerve. The abnormal expression of α-synuclein has been found in inflammatory bowel disease (IBD). Intestinal inflammation and intestinal dysbiosis have been involved in the occurrence and development of PD. The present review aimed to summarize recent advancements in studies focusing on intestinal inflammation and PD, especially the mechanisms through which link intestinal inflammation and PD. The intestinal dysfunctions such as constipation have been introduced as non-motor manifestations of PD. The possible linkages between IBD and PD, including genetic overlaps, inflammatory responses, intestinal permeability, and intestinal dysbiosis, are mainly discussed. Although it is not confirmed whether PD starts from intestine, intestinal dysfunction may affect intestinal microenvironment to influence central nervous system, including the α-synuclein pathologies and systematic inflammation. It is expected to develop some new strategies in the diagnosis and treatment of PD from the aspect of intestine. It may also become an exciting direction to find better ways to regulate the composition of gut microorganism to treat PD.

The Role of Gut Microbiota and Gut-Brain Interplay in Selected Diseases of the Central Nervous System

The gut microbiome has attracted increasing attention from researchers in recent years. The microbiota can have a specific and complex cross-talk with the host, particularly with the central nervous system (CNS), creating the so-called “gut–brain axis”. Communication between the gut, intestinal microbiota, and the brain involves the secretion of various metabolites such as short-chain fatty acids (SCFAs), structural components of bacteria, and signaling molecules. Moreover, an imbalance in the gut microbiota composition modulates the immune system and function of tissue barriers such as the blood–brain barrier (BBB). Therefore, the aim of this literature review is to describe how the gut–brain interplay may contribute to the development of various neurological disorders, combining the fields of gastroenterology and neuroscience. We present recent findings concerning the effect of the altered microbiota on neurodegeneration and neuroinflammation, including Alzheimer’s and Parkinson’s diseases, as well as multiple sclerosis. Moreover, the impact of the pathological shift in the microbiome on selected neuropsychological disorders, i.e., major depressive disorders (MDD) and autism spectrum disorder (ASD), is also discussed. Future research on the effect of balanced gut microbiota composition on the gut–brain axis would help to identify new potential opportunities for therapeutic interventions in the presented diseases.

Gut dysbiosis, defective autophagy and altered immune responses in neurodegenerative diseases: Tales of a vicious cycle

The human microbiota comprises trillions of symbiotic microorganisms and is involved in regulating gastrointestinal (GI), immune, nervous system and metabolic homeostasis. Recent observations suggest a bidirectional communication between the gut microbiota and the brain via immune, circulatory and neural pathways, termed the Gut-Brain Axis (GBA). Alterations in gut microbiota composition, such as seen with an increased number of pathobionts and a decreased number of symbionts, termed gut dysbiosis or microbial intestinal dysbiosis, plays a prominent role in the pathogenesis of central nervous system (CNS)-related disorders. Clinical reports confirm that GI symptoms often precede neurological symptoms several years before the development of neurodegenerative diseases (NDDs). Pathologically, gut dysbiosis disrupts the integrity of the intestinal barrier leading to ingress of pathobionts and toxic metabolites into the systemic circulation causing GBA dysregulation. Subsequently, chronic neuroinflammation via dysregulated immune activation triggers the accumulation of neurotoxic misfolded proteins in and around CNS cells resulting in neuronal death. Emerging evidence links gut dysbiosis to the aggravation and/or spread of proteinopathies from the peripheral nervous system to the CNS and defective autophagy-mediated proteinopathies. This review summarizes the current understanding of the role of gut microbiota in NDDs, and highlights a vicious cycle of gut dysbiosis, immune-mediated chronic neuroinflammation, impaired autophagy and proteinopathies, which contributes to the development of neurodegeneration in Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis and frontotemporal lobar degeneration. We also discuss novel therapeutic strategies targeting the modulation of gut dysbiosis through prebiotics, probiotics, synbiotics or dietary interventions, and faecal microbial transplantation (FMT) in the management of NDDs.

Roles of α‑synuclein in gastrointestinal microbiome dysbiosis‑related Parkinson's disease progression (Review)

Parkinson's disease (PD) is the second most common neurodegenerative disease amongst the middle-aged and elderly populations. Several studies have confirmed that the microbiota-gut-brain axis (MGBA) serves a key role in the pathogenesis of PD. Changes to the gastrointestinal microbiome (GM) cause misfolding and abnormal aggregation of α-synuclein (α-syn) in the intestine. Abnormal α-syn is not eliminated via physiological mechanisms and is transported into the central nervous system (CNS) via the vagus nerve. The abnormal levels of α-syn aggregate in the substantia nigra pars compacta, not only leading to the formation of eosinophilic Lewis Bodies in the cytoplasm and mitochondrial dysfunction in dopaminergic (DA) neurons, but also leading to the stimulation of an inflammatory response in the microglia. These pathological changes result in an increase in oxidative stress (OS), which triggers nerve cell apoptosis, a characteristic of PD. This increase in OS further oxidizes and intensifies abnormal aggregation of α-syn, eventually forming a positive feedback loop. The present review discusses the abnormal accumulation of α-syn in the intestine caused by the GM changes and the increased levels of α-syn transport to the CNS via the MGBA, resulting in the loss of DA neurons and an increase in the inflammatory response of microglial cells in the brain of patients with PD. In addition, relevant clinical therapeutic strategies for improving the GM and reducing α-syn accumulation to relieve the symptoms and progression of PD are described.

Helicobacter Pylori Infection Is Associated with Neurodegeneration in Cognitively Normal Men

BACKGROUND

An association between Helicobacter pylori (H. pylori) infection and dementia was reported in previous studies; however, the evidence is inconsistent.

OBJECTIVE

In the present study, the association between H. pylori infection and brain cortical thickness as a biomarker of neurodegeneration was investigated.

METHODS

A cross-sectional study of 822 men who underwent a medical health check-up, including an esophagogastroduodenoscopy and 3.0 T magnetic resonance imaging, was performed. H. pylori infection status was assessed based on histology. Multiple linear regression analyses were conducted to evaluate the relationship between H. pylori infection and brain cortical thickness.

RESULTS

Men with H. pylori infection exhibited overall brain cortical thinning (p = 0.022), especially in the parietal (p = 0.008) and occipital lobes (p = 0.050) compared with non-infected men after adjusting for age, educational level, alcohol intake, smoking status, and intracranial volume. 3-dimentional topographical analysis showed that H. pylori infected men had cortical thinning in the bilateral lateral temporal, lateral frontal, and right occipital areas compared with non-infected men with the same adjustments (false discovery rate corrected, Q < 0.050). The association remained significant after further adjusting for inflammatory marker (C-reactive protein) and metabolic factors (obesity, dyslipidemia, fasting glucose, and blood pressure).

CONCLUSION

Our results indicate H. pylori infection is associated with neurodegenerative changes in cognitive normal men. H. pylori infection may play a pathophysiologic role in the neurodegeneration and further studies are needed to validate this association.

Microbial Infections Are a Risk Factor for Neurodegenerative Diseases

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, comprise a family of disorders characterized by progressive loss of nervous system function. Neuroinflammation is increasingly recognized to be associated with many neurodegenerative diseases but whether it is a cause or consequence of the disease process is unclear. Of growing interest is the role of microbial infections in inciting degenerative neuroinflammatory responses and genetic factors that may regulate those responses. Microbial infections cause inflammation within the central nervous system through activation of brain-resident immune cells and infiltration of peripheral immune cells. These responses are necessary to protect the brain from lethal infections but may also induce neuropathological changes that lead to neurodegeneration. This review discusses the molecular and cellular mechanisms through which microbial infections may increase susceptibility to neurodegenerative diseases. Elucidating these mechanisms is critical for developing targeted therapeutic approaches that prevent the onset and slow the progression of neurodegenerative diseases.

Hypoxia, Acidification and Inflammation: Partners in Crime in Parkinson’s Disease Pathogenesis?

Like in other neurodegenerative diseases, protein aggregation, mitochondrial dysfunction, oxidative stress and neuroinflammation are hallmarks of Parkinson’s disease (PD). Differentiating characteristics of PD include the central role of α-synuclein in the aggregation pathology, a distinct vulnerability of the striato-nigral system with the related motor symptoms, as well as specific mitochondrial deficits. Which molecular alterations cause neurodegeneration and drive PD pathogenesis is poorly understood. Here, we summarize evidence of the involvement of three interdependent factors in PD and suggest that their interplay is likely a trigger and/or aggravator of PD-related neurodegeneration: hypoxia, acidification and inflammation. We aim to integrate the existing knowledge on the well-established role of inflammation and immunity, the emerging interest in the contribution of hypoxic insults and the rather neglected effects of brain acidification in PD pathogenesis. Their tight association as an important aspect of the disease merits detailed investigation. Consequences of related injuries are discussed in the context of aging and the interaction of different brain cell types, in particular with regard to potential consequences on the vulnerability of dopaminergic neurons in the substantia nigra. A special focus is put on the identification of current knowledge gaps and we emphasize the importance of related insights from other research fields, such as cancer research and immunometabolism, for neurodegeneration research. The highlighted interplay of hypoxia, acidification and inflammation is likely also of relevance for other neurodegenerative diseases, despite disease-specific biochemical and metabolic alterations.

Helicobacter pylori eradication improves motor fluctuations in advanced Parkinson's disease patients: A prospective cohort study (HP-PD trial)

BACKGROUND

Helicobacter pylori (HP) is a bacterium associated with many gastrointestinal (GI) diseases and has shown a high prevalence in Parkinson's disease (PD). As HP-associated GI dysfunction could affect L-dopa (levodopa) absorption, HP eradication might improve the clinical response and decrease motor fluctuations.

METHODS

A prospective cohort study was conducted on the clinical symptoms of PD patients with motor fluctuations. The 13C-urea breath test was used to diagnose a current HP infection. All patients with HP infection received a 2-week regimen of triple therapy. The changes in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score, L-dopa onset time, wearing-off symptoms, mean daily on-off time, GI symptom scores, and quality of life score were measured at baseline and at a 6-week follow-up.

RESULTS

A total of 163 PD patients were assessed, of whom 40 were enrolled. Fifty-five percent of the enrolled patients (22/40) had a current HP infection, whereas HP eradication was identified in 17 of 22 (77.3%) patients who received eradication therapy. Patients with HP eradication showed a significant decrease in daily 'off' time (4.0 vs. 4.7 h, p = 0.040) and an increase in daily 'on' time (11.8 vs. 10.9 h, p = 0.009). Total wearing-off score (4.4 vs. 6.0, p = 0.001) and the GI symptom score (8.1 vs. 12.8, p = 0.007) were significantly improved. There was no significant improvement in L-dopa onset time, UPDRS motor score, or quality of life score.

CONCLUSIONS

HP eradication leads to significant clinical improvement in the symptoms of PD. Eradication of HP not only increases the total daily 'on' time but also decreases wearing-off symptoms and improves GI symptoms.

Helicobacter and the Potential Role in Neurological Disorders: There Is More Than Helicobacter pylori

Trillions of symbiotic microbial cells colonize our body, of which the larger part is present in the human gut. These microbes play an essential role in our health and a shift in the microbiome is linked to several diseases. Recent studies also suggest a link between changes in gut microbiota and neurological disorders. Gut microbiota can communicate with the brain via several routes, together called the microbiome–gut–brain axis: the neuronal route, the endocrine route, the metabolic route and the immunological route. Helicobacter is a genus of Gram-negative bacteria colonizing the stomach, intestine and liver. Several papers show the role of H. pylori in the development and progression of neurological disorders, while hardly anything is known about other Helicobacter species and the brain. We recently reported a high prevalence of H. suis in patients with Parkinson’s disease and showed an effect of a gastric H. suis infection on the mouse brain homeostasis. Here, we discuss the potential role of H. suis in neurological disorders and how it may affect the brain via the microbiome–gut–brain axis.

Rigorous Plasma Microbiome Analysis Method Enables Disease Association Discovery in Clinic

Blood microbiome is important to investigate microbial-host interactions and the effects on systemic immune perturbations. However, this effort has met with major challenges due to low microbial biomass and background artifacts. In the current study, microbial 16S DNA sequencing was applied to analyze plasma microbiome. We have developed a quality-filtering strategy to evaluate and exclude low levels of microbial sequences, potential contaminations, and artifacts from plasma microbial 16S DNA sequencing analyses. Furthermore, we have applied our technique in three cohorts, including tobacco-smokers, HIV-infected individuals, and individuals with systemic lupus erythematosus (SLE), as well as corresponding controls. More than 97% of total sequence data was removed using stringent quality-filtering strategy analyses; those removed amplicon sequence variants (ASVs) were low levels of microbial sequences, contaminations, and artifacts. The specifically enriched pathobiont bacterial ASVs have been identified in plasmas from tobacco-smokers, HIV-infected individuals, and individuals with SLE but not from control subjects. The associations between these ASVs and disease pathogenesis were demonstrated. The pathologic activities of some identified bacteria were further verified in vitro. We present a quality-filtering strategy to identify pathogenesis-associated plasma microbiome. Our approach provides a method for studying the diagnosis of subclinical microbial infection as well as for understanding the roles of microbiome-host interaction in disease pathogenesis.

Genetic and Environmental Factors in Parkinson's Disease Converge on Immune Function and Inflammation

Idiopathic Parkinson's disease (iPD) is a movement disorder characterized by the degeneration of dopaminergic neurons and aggregation of the protein α-synuclein. Patients with iPD vary in age of symptom onset, rate of progression, severity of motor and non-motor symptoms, and extent of central and peripheral inflammation. Genetic and environmental factors are believed to act synergistically in iPD pathogenesis. We propose that environmental factors (pesticides and infections) increase the risk for iPD via the immune system and that the role of PD risk genes in immune cells is worthy of investigation. This review highlights the major PD-relevant genes expressed in immune cells and key environmental factors that activate immune cells and, alone or in combination with other factors, may contribute to iPD pathogenesis. By reviewing these interactions, we seek to enable the future development of immunomodulatory approaches to prevent or delay onset of iPD. © 2020 International Parkinson and Movement Disorder Society.

The α-Synuclein Origin and Connectome Model (SOC Model) of Parkinson's Disease: Explaining Motor Asymmetry, Non-Motor Phenotypes, and Cognitive Decline

A new model of Parkinson's disease (PD) pathogenesis is proposed, the α-Synuclein Origin site and Connectome (SOC) model, incorporating two aspects of α-synuclein pathobiology that impact the disease course for each patient: the anatomical location of the initial α-synuclein inclusion, and α-synuclein propagation dependent on the ipsilateral connections that dominate connectivity of the human brain. In some patients, initial α-synuclein pathology occurs within the CNS, leading to a brain-first subtype of PD. In others, pathology begins in the peripheral autonomic nervous system, leading to a body-first subtype. In brain-first cases, it is proposed that the first pathology appears unilaterally, often in the amygdala. If α-synuclein propagation depends on connection strength, a unilateral focus of pathology will disseminate more to the ipsilateral hemisphere. Thus, α-synuclein spreads mainly to ipsilateral structures including the substantia nigra. The asymmetric distribution of pathology leads to asymmetric dopaminergic degeneration and motor asymmetry. In body-first cases, the α-synuclein pathology ascends via the vagus to both the left and right dorsal motor nuclei of the vagus owing to the overlapping parasympathetic innervation of the gut. Consequently, the initial α-synuclein pathology inside the CNS is more symmetric, which promotes more symmetric propagation in the brainstem, leading to more symmetric dopaminergic degeneration and less motor asymmetry. At diagnosis, body-first patients already have a larger, more symmetric burden of α-synuclein pathology, which in turn promotes faster disease progression and accelerated cognitive decline. The SOC model is supported by a considerable body of existing evidence and may have improved explanatory power.

Ketogenic diet and cognition in neurological diseases: a systematic review

CONTEXT

In recent years, the ketogenic diet has gained special relevance as a possible therapeutic alternative to some neurological and chronic diseases.

OBJECTIVE

The aim of this systematic review was to answer the following question: Does a ketogenic diet improve cognitive skills in patients with Alzheimer's disease, Parkinson's disease, refractory epilepsy, and type 1 glucose deficiency syndrome? To define the research question, the PICOS criteria were used, following the guidelines of the PRISMA method.

DATA SOURCES

Medline/PubMed, Elsevier Science Direct, Dialnet, EBSCOhost, Mediagraphic, Sage Journals, ProQuest, and Wiley Online Library databases were used.

DATA EXTRACTION

After applying inclusion and exclusion criteria in accordance with the PRISMA method, a total of 63 entries published between 2004 and 2019 were used.

DATA ANALYSIS

The records extracted were analyzed from a qualitative approach, so no statistical analysis was carried out.

CONCLUSION

Although scientific literature on the subject is scarce and there has tended to be a lack of scientific rigor, the studies reviewed confirmed the effectiveness of this diet in improving the cognitive symptomatology of the aforementioned diseases.

Single Nucleotide Polymorphisms Associated With Gut Homeostasis Influence Risk and Age-at-Onset of Parkinson's Disease

Research is increasingly focusing on gut inflammation as a contributor to Parkinson's disease (PD). Such gut inflammation is proposed to arise from a complex interaction between various genetic, environmental, and lifestyle factors, however these factors are under-characterized. This study investigated the association between PD and single-nucleotide polymorphisms (SNPs) in genes responsible for binding of bacterial metabolites and intestinal homeostasis, which have been implicated in intestinal infections or inflammatory bowel disease. A case-control analysis was performed utilizing the following cohorts: (i) patients from the Australian Parkinson's Disease Registry (APDR) (n = 212); (ii) a Caucasian subset of the Parkinson's Progression Markers Initiative (PPMI) cohort (n = 376); (iii) a combined control group (n = 404). The following SNPs were analyzed: PGLYRP2 rs892145, PGLYRP4 rs10888557, TLR1 rs4833095, TLR2 rs3804099, TLR4 rs7873784, CD14 rs2569190, MUC1 rs4072037, MUC2 rs11825977, CLDN2 rs12008279 and rs12014762, and CLDN4 rs8629. PD risk was significantly associated with PGLYRP4 rs10888557 genotype in both cohorts. PGLYRP2 rs892145 and TLR1 rs4833095 were also associated with disease risk in the APDR cohort, and TLR2 rs3804099 and MUC2 rs11825977 genotypes in the PPMI cohort. Interactive risk effects between PGLYRP2/PGLYRP4 and PGLYRP4/TLR2 were evident in the APDR and PPMI cohorts, respectively. In the APDR cohort, the PGLYRP4 GC genotype was significantly associated with age of symptom onset, independently of gender, toxin exposure or smoking status. This study demonstrates that genetic variation in the bacterial receptor PGLYRP4 may modulate risk and age-of-onset in idiopathic PD, while variants in PGLYRP2, TLR1/2, and MUC2 may also influence PD risk. Overall, this study provides evidence to support the role of dysregulated host-microbiome signaling and gut inflammation in PD, and further investigation of these SNPs and proteins may help identify people at risk of developing PD or increase understanding of early disease mechanisms.

Sheth M, Viswanath O, Urits I. Chronic Pain Treatment Strategies in Parkinson's Disease

Neurological disorders, including Parkinson's disease (PD), have increased in prevalence and are expected to further increase in the coming decades. In this regard, PD affects around 3% of the population by age 65 and up to 5% of people over the age of 85. PD is a widely described, physically and mentally disabling neurodegenerative disorder. One symptom often poorly recognized and under-treated by health care providers despite being reported as the most common non-motor symptom is the finding of chronic pain. Compared to the general population of similar age, PD patients suffer from a significantly higher level and prevalence of pain. The most common form of pain reported by Parkinson's patients is of musculoskeletal origin. One of the most used combination drugs for PD is Levodopa-Carbidopa, a dopamine precursor that is converted to dopamine by the action of a naturally occurring enzyme called DOPA decarboxylase. Pramipexole, a D2 dopamine agonist, and apomorphine, a dopamine agonist, and Rotigotine, a dopamine receptor agonist, have showed efficacy on PD-associated pain. Other treatments that have shown efficacy in treating pain of diverse etiologies are acetaminophen, Nonsteroidal anti-inflammatory drugs (NSAIDs), and cyclooxygenase-2 (COX-2) inhibitors. Opioids and opioid-like medications such as oxycodone, morphine, tramadol, and codeine are also commonly employed in treatment of chronic pain in PD. Other opioid related medications such as Tapentadol, a central-acting oral analgesic with combined opioid and noradrenergic properties, and Targinact, a combination of the opioid agonist oxycodone and the opioid antagonist naloxone have shown improvement in pain. Anticonvulsants such as gabapentin, pregabalin, lamotrigine, carbamazepine and tricyclic antidepressants (TCAs) can be trialed when attempting to manage chronic pain in PD. The selective serotonin and noradrenaline reuptake inhibitors (SNRIs) also possess pain relieving and antidepressant properties, but carry less of the risk of anticholinergic side effects seen in TCAs. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been shown in multiple studies to be effective against various types of PD associated pain symptoms. Massage therapy (MT) is one of the most common forms of complementary and alternative medicine. Studies have shown that pressure applied during MT may stimulate vagal activity, promoting reduced anxiety and pain, as well as increasing levels of serotonin. In a survey study of PD patients, rehabilitative therapy and physical therapy were rated as the most effective for pain reduction, though with only temporary relief but these studies were uncontrolled. Yoga has been studied for patients with a wide array of neurological disorders. In summary, PD pathology is thought to have a modulating effect on pain sensation, which could amplify pain. This could help explain a portion of the higher incidence of chronic pain felt by PD patients. A treatment plan can be devised that may include dopaminergic agents, acetaminophen, NSAIDs, opioids, antidepressants, physical therapies, DBS and other options discussed in this review. A thorough assessment of patient history and physical examination should be made in patients with PD so chronic pain may be managed effectively.

Gut-Brain Axis: Role of Gut Microbiota on Neurological Disorders and How Probiotics/Prebiotics Beneficially Modulate Microbial and Immune Pathways to Improve Brain Functions

The gut microbiome acts as an integral part of the gastrointestinal tract (GIT) that has the largest and vulnerable surface with desirable features to observe foods, nutrients, and environmental factors, as well as to differentiate commensals, invading pathogens, and others. It is well-known that the gut has a strong connection with the central nervous system (CNS) in the context of health and disease. A healthy gut with diverse microbes is vital for normal brain functions and emotional behaviors. In addition, the CNS controls most aspects of the GI physiology. The molecular interaction between the gut/microbiome and CNS is complex and bidirectional, ensuring the maintenance of gut homeostasis and proper digestion. Besides this, several mechanisms have been proposed, including endocrine, neuronal, toll-like receptor, and metabolites-dependent pathways. Changes in the bidirectional relationship between the GIT and CNS are linked with the pathogenesis of gastrointestinal and neurological disorders; therefore, the microbiota/gut-and-brain axis is an emerging and widely accepted concept. In this review, we summarize the recent findings supporting the role of the gut microbiota and immune system on the maintenance of brain functions and the development of neurological disorders. In addition, we highlight the recent advances in improving of neurological diseases by probiotics/prebiotics/synbiotics and fecal microbiota transplantation via the concept of the gut-brain axis.

[The role of the gut microbiome in idiopathic Parkinson's disease]

BACKGROUND

In recent years studies have provided increasing evidence suggesting an association between the (gut) microbiome and idiopathic Parkinson's disease (IPD).

OBJECTIVE

The aim of this article is to summarize and evaluate existing evidence with respect to the relevance of the (gut) microbiome for IPD.

MATERIAL AND METHODS

An analysis and critical review of studies in the field of IPD and (gut) microbiome were carried out. The resulting potential perspectives and therapeutic strategies are discussed.

RESULTS

Despite partially divergent results between different studies (potentially due to the applied methods and variance in the composition of the investigated cohorts), there is an overlap between studies indicating an association between IPD, the microbiome and microbial metabolites. Nevertheless, the cause-effect relationship between IPD and the microbiome has still not been clarified. Taken together, existing evidence supports a potentially relevant role for the microbiome with respect to typical disease symptoms and pathogenesis of the disease.

CONCLUSION

Over the past 5 years there has been an enormous increase in the evidence with respect to the relevance of the microbiome for IPD. While early work in this field was mainly descriptive, new diagnostic methods provide evidence for the underlying mechanisms and the complex interactions between man as the host, the human immune system, the enteric nervous system, gut microbiota and microbial metabolites. A relatively novel and clinically relevant field of research is how the gut microbiome can influence the success of oral pharmacotherapy and whether substitution of specific microbiome components might be used either for future therapeutic or prophylactic strategies.

Unique Novel Role of Adropin in a Gastric Ulcer in a Rotenone-Induced Rat Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, frequently associated with a gastric ulcer. We aimed to investigate the adropin neuroprotective/gastroprotective potential in the indomethacin (IND)-induced gastric ulcer in a rotenone-induced PD model. Rats were randomly divided into four groups: normal control group, rotenone/IND treated (PD /Ulcer) group, adropin treated PD/Ulcer group, and l-dopa/omeprazole (Om) treated PD/Ulcer group. There were ten rats selected for the normal control group. Striatal dopamine (DA), apoptosis/redox status, and motor/behavioral impairments were evaluated. Gastric oxidative stress, H⁺/K⁺-ATPase activity, prostaglandin E2, mucin content, and von Willebrand factor were measured. Gastric/striatal phosphatidylinositol 3-kinase (PI3K)/phosphorylated Akt and gastric vascular endothelial growth factor (VEGF)/striatal P53 immunoreactivities were checked. Striatal P53 upregulated modulator of apoptosis (Puma)/gastric vascular endothelial growth factor receptor-2 (Vegfr-2) expressions were evaluated. Adropin successfully restored striatal DA and attenuated rotenone-induced motor/behavior deficits along with strong gastroprotective potential, possibly through antioxidant activity via reduction in malondialdehyde level and upregulated superoxide dismutase, catalase activities, and serum ferric reducing antioxidant power. Adropin restored the delicate balance between the defective pro-survival PI3K/Akt/murine double minute 2 signals and apoptotic P53/Puma pathways. Adropin can be considered as a uniquely attractive therapeutic target in PD and its associated gastric ulcer.

Association between Parkinson's disease and proton pump inhibitors therapy in older people

OBJECTIVES

The study was to explore the association between Parkinson's disease and proton pump inhibitors use.

METHODS

A population-based case-control study was conducted to analyze the 2000-2013 database of Taiwan National Health Insurance Program. In total, there were 4280 participants aged ≥65 years with newly diagnosed Parkinson's disease as the case group and 4280 sex- and age-matched participants without Parkinson's disease as the control group. Ever use of proton pump inhibitors was defined as participants who had at least a prescription for proton pump inhibitors before the index date. Never use of proton pump inhibitors was defined as participants who did not have a prescription for proton pump inhibitors before the index date. The odds ratio and 95% confidence interval were used to estimate the association between Parkinson's disease and proton pump inhibitors use by the logistic regression model.

RESULTS

A significant association was detected between Parkinson's disease and proton pump inhibitors use (odds ratio 1.15, 95% confidence interval 1.04-1.27).

CONCLUSIONS

An association is found between Parkinson's disease and proton pump inhibitors use in older people. Other real-world data are required to confirm the clinical impact of proton pump inhibitors therapy on the risk of Parkinson's disease.

No association between proton pump inhibitor use and ALS risk: a nationwide nested case-control study

The use of proton pump inhibitors (PPIs) has been proposed as a potential risk factor for neurodegenerative diseases, but little is known regarding its role in amyotrophic lateral sclerosis (ALS). We therefore aimed to assess the association of PPI use with the subsequent risk of ALS, and performed a register-based nationwide nested case–control study, including 2,484 ALS cases diagnosed during July 2006–December 2013 in Sweden and 10 population controls per case that were individually matched to the case by sex, age, and area of residence. Dispenses and cumulative defined daily doses (cDDDs) of PPIs were extracted from the Swedish Prescribed Drug Register. The association of PPI use with the risk of ALS was assessed using conditional logistic regression, after applying different lag windows to avoid reverse causation. ALS patients were more likely to be dispensed with PPIs before diagnosis than controls. However, previous PPI use was not associated with an increased risk of ALS (OR = 1.08, 95% CI 0.97–1.19), and there was no dose–response relationship between cDDDs of PPIs and ALS risk (p = 0.0874), after excluding dispenses during the year before ALS diagnosis. The results were similar after excluding dispenses during the 2 or 3 years before ALS diagnosis.

Clostridium difficile infection and risk of Parkinson's disease: a Swedish population-based cohort study

BACKGROUND AND PURPOSE

Gastrointestinal inflammation has been implicated in Parkinson's disease (PD). The aim of this study was to examine whether individuals with a history of Clostridium difficile infection (CDI) are at elevated risk of PD.

METHODS

We performed a population-based cohort study using Swedish national register data. Adults aged ≥35 years were identified from the Swedish Population and Housing Census 1990 and followed during the period 1997-2013. Diagnoses of CDI and PD were extracted from the National Patient Register. Associations of CDI history with PD risk were estimated using Cox proportional hazards regression. We also explored whether the association differed by the source of CDI diagnosis (inpatient vs. outpatient), presence of recurrent infections, and pre-infection use of antibiotics.

RESULTS

Amongst the study population (N = 4 670 423), 34 868 (0.75%) had a history of CDI. A total of 165 and 47 035 incident PD cases were identified from individuals with and without CDI history, respectively. Across the entire follow-up, a 16% elevation of PD risk was observed among the CDI group [hazard ratio 1.16, 95% confidence interval (CI)1.00-1.36], which was mainly driven by increased PD risk within the first 2 years after CDI diagnosis (hazard ratio 1.38, 95% CI 1.12-1.69). In longer follow-up, CDI was not associated with subsequent PD occurrence. This temporal pattern of CDI-PD associations was generally observed across all CDI subgroups.

CONCLUSIONS

Clostridium difficile may be associated with an increased short-term PD risk, but this might be explained by reverse causation and/or surveillance bias. Our results do not imply that CDI history affects long-term PD risk.

Role of Helicobacters in Neuropsychiatric Disease: A Systematic Review in Idiopathic Parkinsonism

Interest in an aetiopathogenic role for Helicobacter in neuropsychiatric diseases started with idiopathic parkinsonism (IP), where the cardinal signs can be assessed objectively. This systematic review, using an EMBASE database search, addresses Oxford Centre for Evidence-Based Medicine based questions on the inter-relationship of Helicobacter and IP, the benefits of eradicating Helicobacter in IP and the outcome of not treating. The search strategy was based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines: 21 of 204 articles met the inclusion criteria. The results show that the assumption that any benefit of Helicobacter eradication results from improved levodopa bioavailability is unjustified. The inter-relationship between Helicobacter and IP is well-established. H. pylori virulence markers (associated with autoimmunity and immune tolerance) influence the risk, severity and progression of IP. The birth cohort effect for virulence marker antibodies, seen in controls, is obliterated in IP, suggesting causality. Successful H. pylori eradication in IP is disease-modifying (even in anti-parkinsonian treatment-naïve patients) but not preventive. Hypokinesia regresses with eradication and overall motor severity lessens. Eradication may influence gastrointestinal microbiota adversely, unlocking the next stage in the natural history, the development of rigidity. Failed eradication worsens hypokinesia, as does the presence/persistence of H. pylori at molecular level only. Adequate prognostic assessment of the consequences of not treating Helicobacter, for IP, is prevented by a short follow-up. We conclude that Helicobacter is a pathophysiological driver of IP.

Clinical implications of gastric complications on levodopa treatment in Parkinson's disease

Disorders of the gastrointestinal (GI) tract are common and distressing nonmotor symptoms of Parkinson's disease (PD) that can adversely affect levodopa absorption and lead to OFF periods, also known as motor fluctuations. Gastroparesis, which is primarily defined as delayed gastric emptying (DGE), and Helicobacter pylori infection, which is present with increased frequency in PD, are among the most common and important GI disorders reported in PD that may impair oral levodopa absorption and increase OFF time. Symptoms of gastroparesis include nausea, vomiting, postprandial bloating, fullness, early satiety, abdominal pain, and weight loss. DGE has been reported in a substantial fraction of individuals with PD. Symptoms of H. pylori infection include gastritis and peptic ulcers. Studies have found that DGE and H. pylori infection are correlated with delayed peak levodopa plasma levels and increased incidence of motor fluctuations. Therapeutic strategies devised to minimize the potential that gastric complications will impair oral levodopa absorption and efficacy in PD patients include treatments that circumvent the GI tract, such as apomorphine injection, levodopa intestinal gel delivery, levodopa inhalation powder, and deep brain stimulation. Other strategies aim at improving gastric emptying in PD patients, primarily including prokinetic agents.

Bacterial, viral, and fungal infection-related risk of Parkinson's disease: Meta-analysis of cohort and case-control studies

AIMS

Recent studies showed that patients with various bacterial, viral, and fungal infections might be at increased risk of Parkinson's disease (PD). However, the risk of PD in patients with each specific infection varied. This meta-analysis estimated the association between various infections and PD risk.

METHODS

Literature published from January 1965 to October 2019 in PubMed and EMBASE databases was searched. Data were extracted and pooled using random/fixed effects model. Sensitivity analysis and meta-regression were also performed to analyze the source of heterogeneity. Publication bias was estimated by the trim and fill.

RESULTS

Twenty-three out of 6,609 studies were included. Helicobacter pylori (HP; pooled OR = 1.653, 1.426-1.915, p < .001), hepatitis C virus (HCV; pooled OR = 1.195, 1.012-1.410, p = .035), Malassezia (pooled OR = 1.694, 1.367-2.100, p < .001), and pneumoniae (pooled OR = 1.595, 1.020-2.493, p = .041) infection were associated with increased PD risk. Influenza virus, herpes virus, hepatitis B virus, scarlet fever, mumps virus, chicken pox, pertussis, German measles, and measles were not associated with PD risk. After antiviral treatment against HCV reduced the risk of PD in patients with HCV infection (OR = 0.672, 0.571-0.791, p < .001). Significant heterogeneity exists among the included studies.

CONCLUSION

Patients with infection of HP, HCV, Malassezia, pneumoniae might be an increased risk of PD. Antiviral treatment of HCV could reduce the risk of PD.

Dangerous Liaison: Helicobacter pylori, Ganglionitis, and Myenteric Gastric Neurons: A Histopathological Study

Chronic inflammation induced by Helicobacter pylori (H. pylori) infection plays a major role in development of gastric cancer. However, recent findings suggested that progression of inflammation and neoplastic transformation in H. pylori infection are more complex than previously believed and could involve different factors that modulate gastric microenvironment and influence host-pathogen interaction. Among these factors, gastric myenteric plexus and its potential adaptive changes in H. pylori infection received little attention. This study is aimed at identifying the impact of H. pylori-associated gastritis on number and morphology of nerve cells in the stomach. The distribution of density, inflammation, and programmed cell death in neurons was immunohistochemically assessed in full-thickness archival tissue samples obtained from 40 patients with H. pylori infection who underwent surgery for gastric cancer and were compared with findings on samples collected from 40 age- and sex-matched subjects without bacteria. Overall, significant differences were noted between H. pylori-positive and H. pylori-negative patients. The analysis of tissue specimens obtained from those with infection revealed higher density and larger surface of the myenteric nervous plexus, as well as a significant increase in the number of gastric neuronal cell bodies and glial cells compared to controls. A predominant CD3-immunoreactive T cell infiltrate confined to the myenteric plexus was observed in infected subjects. The presence of mature B lymphocytes, plasma cells, and eosinophils was also noted, but to a lesser extent, within the ganglia. Myenteric ganglionitis was associated with degeneration and neuronal loss. Our results represent the first histopathological evidence supporting the hypothesis that H. pylori-induced gastric inflammation may induce morphological changes in myenteric gastric ganglia. These findings could help gain understanding of some still unclear aspects of pathogenesis of H. pylori infection, with the possibility of having broader implications for gastric cancer progression.

The role of gut microbiota, butyrate and proton pump inhibitors in amyotrophic lateral sclerosis: a systematic review

Aim of the study: We conducted a systematic review on existing literature in humans and animals, linking the gut microbiome with amyotrophic lateral sclerosis (ALS). Additionally, we sought to explore the role of the bacterially produced metabolite butyrate as well as of proton pump inhibitors (PPIs) in these associations.Materials and methods: Following PRISMA guidelines for systematic literature reviews, four databases (Medline, Scopus, Embase and Web of Science) were searched and screened by two independent reviewers against defined inclusion criteria. Six studies in humans and six animal studies were identified, summarized and reviewed.Results: Overall, the evidence accrued to date is supportive of changes in the gut microbiome being associated with ALS risk, and potentially progression, though observational studies are small (describing a total of 145 patients with ALS across all published studies), and not entirely conclusive.Conclusions: With emerging studies beginning to apply metagenome sequencing, more clarity regarding the importance and promise of the gut microbiome in ALS can be expected. Future studies may also help establish the therapeutic potential of butyrate, and the role of PPIs in these associations.

Helicobacter suis Is Associated With Mortality in Parkinson's Disease

Helicobacter pylori has been implicated in the pathogenesis of Parkinson's disease (PD). Its eradication, in a randomized placebo-controlled trial, improved PD hypokinesia. Helicobacter species zoonosis might explain excess mortality from PD and non-Hodgkin lymphoma in livestock, but not arable, farmers. Indeed, Helicobacter is causally-associated with gastric lymphoma. We have previously shown that the relative-frequency, H. suis to H. pylori, was 10-times greater in 60 PD-patients than in 256 controls. We now go on to evaluate the pathological significance of H. suis, detected in gastric-biopsy DNA-extracts by ureA-based species-specific qPCR, validated by amplicon sequencing. The methodology had been cross-validated by a carR-based PCR. The pathological significance is put in context of H. pylori detection [urea-breath-test (UBT) with biopsy-culture, and, if negative, PCR], and the potential reservoir in pigs. Here, we explore, in these 60 PD-patients, associations of H. suis status with all-cause-mortality, and with orthostatic cardiovascular and blood profiling. H. suis had been detected in 19 of the 60 PD-patients on one or more occasion, only two (with co-existent H. pylori) being UBT positive. We found that the hazard-of-death (age-at-diagnosis- and gender-adjusted) was 12 (95% CI 1,103) times greater (likelihood-ratio test, P = 0.005) with H. suis-positivity (6/19) than with negativity (2/40: one lost to follow-up). UBT-values did not influence the hazard. H. suis-positivity was associated with lower standing mean-arterial-pressure [6 (1, 11) mmHg], H. pylori-positivity having no effect. The lower total lymphocyte count with H. pylori-positivity [-8 (-1, -14) %] was not seen with H. suis, where T-cell counts were higher [24 (2, 52) %]. Regarding the potential zoonotic reservoir in the UK, Helicobacter-like-organism frequency was determined in freshly-slaughtered pigs, nature ascertained by sequencing. Organisms immunostaining for Helicobacter, with corkscrew morphology typical of non-H. pylori Helicobacter, were seen in 47% of 111 pig-antra. We conclude that H. suis is associated with all-cause-mortality in PD and has a potential zoonotic reservoir.

Infectious Etiologies of Parkinsonism: Pathomechanisms and Clinical Implications

Extensive research in recent decades has expanded our insights into the pathogenesis of Parkinson's disease (PD), though the underlying cause remains incompletely understood. Neuroinflammation have become a point of interest in the interconnecting areas of neurodegeneration and infectious diseases. The hypothesis concerning an infectious origin in PD stems from the observation of Parkinson-like symptoms in individuals infected with the influenza virus who then developed encephalitis lethargica. The implications of infectious pathogens have later been studied in neuronal pathways leading to the development of Parkinsonism and PD, through both a direct association and through synergistic effects of infectious pathogens in inducing neuroinflammation. This review explores the relationship between important infectious pathogens and Parkinsonism, including symptoms of Parkinsonism following infectious etiologies, infectious contributions to neuroinflammation and neurodegenerative processes associated with Parkinsonism, and the epidemiologic correlations between infectious pathogens and idiopathic PD.

Altered Gut Microbiome and Intestinal Pathology in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder arising from an interplay between genetic and environmental risk factors. Studies have suggested that the pathological hallmarks of intraneuronal α-synuclein aggregations may start from the olfactory bulb and the enteric nervous system of the gut and later propagate to the brain via the olfactory tract and the vagus nerve. This hypothesis correlates well with clinical symptoms, such as constipation, that may develop up to 20 years before the onset of PD motor symptoms. Recent interest in the gut-brain axis has led to vigorous research into the gastrointestinal pathology and gut microbiota changes in patients with PD. In this review, we provide current clinical and pathological evidence of gut involvement in PD by summarizing the changes in gut microbiota composition and gut inflammation associated with its pathogenesis.

Exploring the "Multiple-Hit Hypothesis" of Neurodegenerative Disease: Bacterial Infection Comes Up to Bat

Despite major strides in personalized genomics, it remains poorly understood why neurodegenerative diseases occur in only a fraction of individuals with a genetic predisposition and conversely, why individuals with no genetic risk of a disorder develop one. Chronic diseases like Alzheimer's, Parkinson's, and Multiple sclerosis are speculated to result from a combination of genetic and environmental factors, a concept commonly referred to as the “multiple hit hypothesis.” A number of bacterial infections have been linked to increased risk of neurodegeneration, and in some cases, clearance of bacterial pathogens has been correlated with amelioration of central nervous system (CNS) deficits. Additionally, mutations in several genes known to contribute to CNS disorders like Parkinson's Disease have repeatedly been implicated in susceptibility to intracellular bacterial infection. Recent data has begun to demonstrate roles for these genes (PARK2, PINK1, and LRRK2) in modulating innate immune outcomes, suggesting that immune dysregulation may play an even more important role in neurodegeneration than previously appreciated. This review will broadly explore the connections between bacterial infection, immune dysregulation, and CNS disorders. Understanding this interplay and how bacterial pathogenesis contributes to the “multiple-hit hypothesis” of neurodegeneration will be crucial to develop therapeutics to effectively treat both neurodegeneration and infection.