Katsushi Tajima

The Role of G-Protein-Coupled Receptor Kinase 5 in Pathogenesis of Sporadic Parkinson's Disease

Sporadic Parkinsons disease (sPD) is a common neurodegenerative disorder, characterized by selective degeneration of dopaminergic neurons in the substantia nigra. Although the pathogenesis of the disease remains undetermined, phosphorylation of α-synuclein and its oligomer formation seem to play a key role. However, the protein kinase(s) involved in the phosphorylation in the pathogenesis of sPD has not been identified. Here, we found that G-protein-coupled receptor kinase 5 (GRK5) accumulated in Lewy bodies and colocalized with α-synuclein in the pathological structures of the brains of sPD patients. In cotransfected cells, GRK5 phosphorylated Ser-129 of α-synuclein at the plasma membrane and induced translocation of phosphorylated α-synuclein to the perikaryal area. GRK5-catalyzed phosphorylation also promoted the formation of soluble oligomers and aggregates of α-synuclein. Genetic association study revealed haplotypic association of the GRK5 gene with susceptibility to sPD. The haplotype contained two functional single-nucleotide polymorphisms, m22.1 and m24, in introns of the GRK5 gene, which bound to YY1 (Yin Yang-1) and CREB-1 (cAMP response element-binding protein 1), respectively, and increased transcriptional activity of the reporter gene. The results suggest that phosphorylation of α-synuclein by GRK5 plays a crucial role in the pathogenesis of sPD.

Microalbuminuria is a risk factor for cerebral small vessel disease in community-based elderly subjects

Microalbuminuria (MA) is known as a marker for generalized vascular dysfunction. It occurs most commonly in the setting of diabetes and hypertension; however, its association with cerebral small vessel disease (SVD) in community-based elderly remains to be clarified. In this cross-sectional analysis, we evaluated the association between MA and cerebral SVD in total 651 community-based elderly subjects. We assessed cardiovascular risk factors by interviews and physical examinations, including an evaluation of urinary albumin creatinine ratio (UACR). All subjects underwent brain magnetic resonance imaging (MRI) and carotid ultrasonography. As endothelial markers, the serum levels of thrombomodulin (TM) and a tissue-type plasminogen activator/ plasminogen activator inhibitor-1 complex were also studied. The mean TM and UACR were higher in subjects with lacunar infarcts or with moderate white matter hyperintensities (mWMH) on MRI than in those without them. Additionally, the prevalence of lacunar infarcts or mWMH was higher in the highest tertile of UACR level than in the lowest or middle tertile. Furthermore, in logistic regression analysis, the elevation of logarithmically transformed UACR (log UACR) was associated with the higher likelihood for total lacunar infarcts (odds ratio [OR], 1.85 per one log UACR increase), multiple lacunar infarcts (OR, 1.89 per one log UACR increase), and mWMH (OR, 2.15 per one log UACR increase). The present study revealed that levels of urinary albumin are associated with cerebral SVD, independently of traditional cerebrovascular risk factors, in community-based elderly.

Deposits of eosinophil granule proteins in eosinophilic cholecystitis and eosinophilic colitis associated with hypereosinophilic syndrome.

SummaryA case of hypereosinophilic syndrome with eosinophilic colitis, eosinophilic cholecystitis, and increased serum levels of interleukin-5 (IL-5) and soluble interleukin-2 receptor (sIL-2R) is reported. Immunohistochemical studies of cholecystectomy and colon biopsy specimens with monoclonal antibodies, which are specific for activated eosinophils, secreted eosinophil cationic protein (ECP) and for major basic protein (MBP), demonstrated the presence of numerous activated eosinophils, secretion of ECP, and deposition of MBP in areas of tissue damage. These findings suggest that in eosinophilic cholecystitis and eosinophilic colitis, activated eosinophils infiltrate and degranulate in each tissue, releasing eosinophil granule proteins that produce tissue damage.

Cerebral small vessel disease and C-reactive protein: results of a cross-sectional study in community-based Japanese elderly.

BACKGROUND AND PURPOSE Inflammatory processes are involved in the pathogenesis of atherosclerosis. Inflammation has been known as a risk factor for coronary heart disease, whereas inflammation as a risk for cerebrovascular disease is less well established. Whether inflammatory processes, excluded from their involvement in large-vessel disease, are implicated in the pathogenesis of cerebral small vessel disease remains unclear. We assessed whether higher C-reactive protein (CRP) levels were associated with an increased number of lacunar infarcts or severity of white matter lesions. METHODS AND RESULTS In a community-based group of Japanese elderly (n=689), CRP concentrations were measured using a highly sensitive assay. All participants underwent magnetic resonance imaging (MRI), and cerebral small vessel disease-related lesions (lacunar infarcts and white matter hyperintensity) were subsequently evaluated. Furthermore, carotid atherosclerosis was also assessed with ultrasonography. As the grades of white matter hyperintensity and the numbers of lacunes were considered small vessel disease-related lesions, we evaluated the relationships between CRP levels and small vessel disease-related brain lesions. Interestingly, the median CRP concentration of our participants was remarkably lower, being approximately one third or one quarter of the value of Western populations. Subjects with higher CRP levels tended to have more small vessel disease-related lesions; however, these associations were not seen after adjustment for cardiovascular risk factors and carotid atherosclerosis. CONCLUSIONS The relationship between CRP levels and small vessel disease-related lesions was not apparent in the community-based Japanese elderly. The impact of inflammation in the pathogenesis of small vessel disease-related brain lesions seems to be weak among the Japanese elderly.

Immunohistochemical detection of bone morphogenetic protein-2 and transforming growth factor beta-1 in tracheopathia osteochondroplastica

Abstract Tracheopathia osteochondroplastica (TO) is an unusual condition characterized by cartilaginous or bony submucosal nodules in the tracheobronchial tree. Bone morphogenetic protein-2 (BMP-2) and transforming growth factor beta-1 (TGF-β1) are potent inducers for new bone formation. We studied the precise localization of BMP-2 and TGF-β1 in two autopsied cases of TO, using immunohistochemical methods. Positive BMP-2 immunoreactivity was detected in numerous mesenchymal cells and chondroblasts lining the nodules in the tracheal submucosa. BMP-2 was not found in mature lamellar bony nodules. TGF-β1 was not seen in mesenchymal cells, though it did appear in chondrocytes and osteocytes in the nodules. These results suggest that BMP-2 plays an important role in nodule formation and acts synergistically with TGF-β1 to promote the nodules inductive cascade in the tracheal submucosa.

A case of inflammatory demyelinating polyradiculoneuropathy associated with T-cell lymphoma

Malignant lymphoma may present prominent peripheral nervous system disorders with variable etiologies. We describe a patient who presented with chronic relapsing polyradiculoneuropathy accompanied by right facial nerve palsy. Gadolinium enhancement of the right facial nerve and cervical spinal roots was noted on magnetic resonance imaging (MRI). Sural nerve biopsy specimens showed mononuclear cell infiltration around the vessels in the epineurium. Histopathological and immunohistochemical investigations of sural nerve specimens revealed perivascular infiltration of lymphocytes with T‐cell dominancy. No apparent direct invasion of lymphoma cells was seen. The results of nerve conduction studies, sural nerve biopsy and cerebrospinal fluid examination were suggestive of immune‐mediated inflammatory demyelinating neuropathy. The chronic and relapsing fashion and unique radiological findings in our patient expand on the previously reported features of peripheral neuropathy associated with peripheral T‐cell lymphoma.

Novel point mutation in the leucine‐rich motif of the platelet glycoprotein IX associated with Bernard‐Soulier syndrome

Bernard‐Soulier syndrome (BSS) is a rare inherited bleeding disorder which is caused by a qualitative or quantitative abnormality of the platelet glycoprotein (GP) Ib/IX/V complex. We examined a patient with BSS to find a molecular basis for the defect underlying this disease. The propositus was a 39‐year‐old Japanese female with life‐long bleeding diathesis. Sequence analysis of the GPIX gene revealed a T → C point mutation at nucleotide 1856 (EMBL, M80478), resulting in Phe55(TTT) → Ser(TCT) replacement. This substitution created a new MnlI restriction site in the mutant allele. Restriction analysis revealed that the propositus was homozygous for this sequence, and the same mutation was not detected in 57 unrelated Japanese subjects. Since this mutation is located in the leucine‐rich motif (LRM) of the GPIX polypeptide, the Phe55 → Ser substitution may result in an alteration of the LRM which leads to the impaired surface expression of GPIb/IX/V complex, a characteristic of BSS.

Expression of BAFF-R and TACI in reactive lymphoid tissues and B-cell lymphomas

Aims:  The receptor for B‐cell‐activating factor belonging to the tumour necrosis factor family (BAFF‐R) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) have been established as binding molecules to BAFF. The aim of this study was to determine the pathological diagnostic roles and clinical significance of these BAFF‐binding receptors in B‐cell neoplasms.

Cellular localization of interleukin-5 expression in rectal carcinoma with eosinophilia

Eosinophilia often occurs in malignant diseases. This report concerns a female patient aged 76 years, diagnosed with rectal carcinoma with eosinophilia. Sera were obtained at two different periods (at diagnosis and after the operation) for the evaluation of levels of interleukin-5 (IL-5). The serum IL-5 level increased to 264 pg/mL, and returned to an undetectable level after the operation. The serum at diagnosis enhanced the viability of normal eosinophils in vitro, and this activity was inhibited by antihuman IL-5 polyclonal antibody. Immunohistochemistry and in situ hybridization revealed that stromal eosinophils contained IL-5 protein and messenger RNA (mRNA), but no IL-5 transcripts were detected in eosinophils attached to carcinoma cells. In situ detection of apoptosis showed that several eosinophils attached to tumor cells underwent apoptosis and lost their eosinophil secreted cationic protein (ECP) and major basic protein (MBP). These results may suggest that activated eosinophils by IL-5 play an important role in host defense mechanisms, releasing their toxic granule proteins on adjoining tumor cells.

Radiation increases the cellular uptake of exosomes through CD29/CD81 complex formation.

Exosomes mediate intercellular communication, and mesenchymal stem cells (MSC) or their secreted exosomes affect a number of pathophysiologic states. Clinical applications of MSC and exosomes are increasingly anticipated. Radiation therapy is the main therapeutic tool for a number of various conditions. The cellular uptake mechanisms of exosomes and the effects of radiation on exosome-cell interactions are crucial, but they are not well understood. Here we examined the basic mechanisms and effects of radiation on exosome uptake processes in MSC. Radiation increased the cellular uptake of exosomes. Radiation markedly enhanced the initial cellular attachment to exosomes and induced the colocalization of integrin CD29 and tetraspanin CD81 on the cell surface without affecting their expression levels. Exosomes dominantly bound to the CD29/CD81 complex. Knockdown of CD29 completely inhibited the radiation-induced uptake, and additional or single knockdown of CD81 inhibited basal uptake as well as the increase in radiation-induced uptake. We also examined possible exosome uptake processes affected by radiation. Radiation-induced changes did not involve dynamin2, reactive oxygen species, or their evoked p38 mitogen-activated protein kinase-dependent endocytic or pinocytic pathways. Radiation increased the cellular uptake of exosomes through CD29/CD81 complex formation. These findings provide essential basic insights for potential therapeutic applications of exosomes or MSC in combination with radiation.