Is Glial Dysfunction the Key Pathogenesis of LRRK2-Linked Parkinson's Disease?

Leucine rich-repeat kinase 2 (LRRK2) is the most well-known etiologic gene for familial Parkinson's disease (PD). Its gene product is a large kinase with multiple functional domains that phosphorylates a subset of Rab small GTPases. However, studies of autopsy cases with LRRK2 mutations indicate a varied pathology, and the molecular functions of LRRK2 and its relationship to PD pathogenesis are largely unknown. Recently, non-autonomous neurodegeneration associated with glial cell dysfunction has attracted attention as a possible mechanism of dopaminergic neurodegeneration. Molecular studies of LRRK2 in astrocytes and microglia have also suggested that LRRK2 is involved in the regulation of lysosomal and other organelle dynamics and inflammation. In this review, we describe the proposed functions of LRRK2 in glial cells and discuss its involvement in the pathomechanisms of PD.

Two Elderly Men with Myasthenia Gravis during Androgen Deprivation Therapy for Prostate Cancer.

Myasthenia gravis (MG) development is female-dominant in younger patients and male-dominant in older patients. The reason for the sex-ratio inversion in elderly MG patients remains unclear. One possible explanation is the decrease in androgen secretion that occurs with aging, as androgen has an immunosuppressive function. We experienced two elderly men who developed MG after initiating androgen deprivation therapy (ADT) for treatment of prostate cancer and whose symptoms were ameliorated after ADT cessation. Our cases indicate that MG in older male patients can be caused by an androgen effect.

Systemic Metabolic Alteration Dependent on the Thyroid-Liver Axis in Early PD.

OBJECTIVE: Parkinson's disease (PD) is a common neurodegenerative disease characterized by initial involvement of the olfactory bulb/amygdala or autonomic nerves followed by nigral degeneration. Although autonomic innervation strictly regulates multiorgan systems, including endocrine functions, circulation, and digestion, how dysautonomia in PD affects systemic metabolism has not been identified. In this study, we tried to estimate the pathogenic linkage of PD by nuclear medicine techniques, trans-omic analysis of blood samples, and cultured cell experiments. METHODS: Thyroid mediastinum ratio of 123 I-metaiodobenzylguanidine (MIBG) scintigraphy was measured in 1,158 patients with PD. Furthermore, serum exosome miRNA transcriptome analysis and plasma metabolome analysis followed by trans-omic analysis were performed in patients with de novo PD and age-matched healthy control persons. Additionally, thyroid hormone was administered to skeletal muscle and liver derived cells to evaluate the effect of hypothyroidism for these organs. RESULTS: Sympathetic denervation of thyroid correlating with its cardiac denervation was confirmed in 1,158 patients with PD by MIBG scintigraphy. Among patients with drug-naïve PD, comprehensive metabolome analysis revealed decreased levels of thyroxine and insufficient fatty acid ß-oxidation, which positively correlate with one another. Likewise, both plasma metabolome data and transcriptome data of circulating exosomal miRNAs, revealed specific enrichment of the peroxisome proliferator-activated receptor (PPARα) axis. Finally, association of thyroid hormone with PPARα-dependent ß-oxidation regulation was confirmed by in vitro experiments. INTERPRETATION: Our findings suggest that interorgan communications between the thyroid and liver are disorganized in the early stage of PD, which would be a sensitive diagnostic biomarker for PD. ANN NEUROL 2023;93:303-316.

Recurrent and Multiple Intracerebral Hemorrhages in Polycythemia Vera Secondary to Myelofibrosis: A Case Report and Literature Review.

Polycythemia vera (PV) is one of the myeloproliferative neoplasms and has higher frequency of the JAK2 V617F mutation. Hemorrhagic stroke is rare in PV, and myelofibrosis is secondary to PV. A 76-year-old Japanese man was diagnosed as PV with the JAK2 V617F mutation at the age of 63 years. He developed anemia together with secondary myelofibrosis, and then 40 mg ruxolitinib was started at 70 years. At 76 years, he presented with apathy and was diagnosed with intracerebral hemorrhage (ICH) in the right thalamus. Six months later, he developed multiple ICHs in bilateral cerebellar hemispheres. Leukocyte count was 57,600/µL, platelet count was 66,000/µL, and the level of hemoglobin was 8.7 g/dL. Bleeding time was 6 min. The agglutination ability when adding collagen was 41%. A patient with the JAK2 V617F mutation developing hemorrhagic stroke due to late-stage PV and secondary myelofibrosis was reported, implying various mechanisms for recurrent and multiple ICH.

Improvement in the Symptoms and VEGF Levels after Resection of an Extrame Dullary Spinal Tumor and Additional Chemotherapy in a Patient with Multiple Myeloma Complicated with POEMS Syndrome.

We herein report a case of multiple myeloma and polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome. The patient experienced exacerbated gait disturbance due to weakness and numbness in the lower limbs. Thoracic magnetic resonance imaging revealed an extramedullary tumor with spinal compression that required surgical resection. Plasmacytoma was diagnosed based on a biopsy. Radiation, betamethasone, and chemotherapy were therefore administered. Surgical removal of extramedullary tumors improved his symptoms, motor conduction velocity, and amplitude of the muscle action potential in the peroneal and tibial nerves, as shown by the nerve conduction study. Surgery also decreased the serum vascular endothelial growth factor levels. The patient required additional chemotherapy due to multiple myeloma and showed better outcomes nine months after discharge. The benefits of some treatments remain controversial due to the small number of patients. However, our findings reveal that an early diagnosis and comprehensive treatment may result in better outcomes in such patients.

Cerebral artery dissection secondary to antiphospholipid syndrome: A report of two cases and a literature review.

INTRODUCTION: Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thromboembolic events, including ischemic stroke or complications in pregnancy, and the presence of antiphospholipid antibodies. Cervical artery dissection (CAD) is not an uncommon cause of stroke in young adults. The concomitant presence of APS and CAD is extremely rare. METHODS: Two cases with APS who developed acute ischemic strokes related to CAD are reported. A comprehensive systematic literature search using the PubMed database was also conducted. RESULTS: In Case 1, a 36-year-old woman who had been diagnosed with systemic lupus erythematosus and had been repeatedly positive for lupus anticoagulant tests developed an ischemic stroke caused by a vertebral artery dissection (VAD). After admission, she had a recurrent ischemic stroke, followed by considerable changes in steno-occlusive lesions of the vertebrobasilar artery system. In Case 2, a 36-year-old man developed multiple brain infarcts due to bilateral VAD with aneurysmal formations and associated with pulmonary embolism. The anticardiolipin antibody titer was repeatedly elevated after stroke. The literature review identified 8 patients with CAD associated with APS, involving the internal carotid artery in 6 patients and the middle cerebral artery and vertebral artery in 1 patient each. The patients were predominantly young and female, infrequently had atherosclerotic vascular risk factors, and were positive for various antiphospholipid antibodies. CONCLUSIONS: The current report described two rare cases of ischemic stroke caused by CAD secondary to APS, along with a review of the literature; the patients displayed characteristic clinical manifestations, implying specific mechanisms for cerebral artery disorders secondary to APS.