Identification and characterization of microvesicles secreted by 3T3-L1 adipocytes: redox- and hormone-dependent induction of milk fat globule-epidermal growth factor 8-associated microvesicles

Adipocytes are now recognized as endocrine cells secreting adipocytokines, regulating multiple metabolic pathways. In this study, we addressed secretion of microvesicles by 3T3-L1 adipocytes. We found that MFG-E8, one of the exosomal proteins, was present in the microvesicles and was distributed in the sucrose density fractions with 1.13-1.20 g/ml, which has been reported for exosomes. Several integral, cytosolic, and nuclear proteins such as caveolin-1, c-Src kinase, and heat shock protein 70 were also found to be microvesicle components. Unexpectedly, adiponectin was also substantially distributed in the microvesicle fractions. Furthermore, proteomic analysis of the microvesicles revealed that many other proteins such as extracellular matrix-related proteins were also present. Microvesicles secreted by 3T3-L1 adipocytes exhibited heterogeneity in size and comprised both smaller exosome-like and larger membrane vesicles as revealed by electron microscopy. Milk fat globule-epidermal growth factor 8 (MFG-E8)-associated adiposomes exhibited binding activity toward phosphatidylserine and apoptotic cells. MFG-E8 in the microvesicles was reduced when cultured in the low-glucose medium or cultured in the high-glucose medium with antioxidant N-acetyl cysteine. Insulin and TNF-alpha also up-regulated MFG-E8 in the microvesicles. Moreover, MFG-E8 was strongly up-regulated in the hypertrophic adipose tissue, predominantly in adipocyte fractions, of diet-induced obese C57BL/6 mice, where increased oxidative stress is induced. Thus, it is suggested that microvesicles, especially MFG-E8-associated ones, modulate adipose functions under redox- and hormone-dependent regulation. Based on the above findings, the adipocyte-derived microvesicles were named adiposomes.     

Excessive exposure to anionic surfaces maintains autoantibody response to beta(2)-glycoprotein I in patients with antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune prothrombotic disorder associated with autoantibodies to phospholipid (PL)-binding proteins, such as beta(2)-glycoprotein I (beta(2)GPI). We have recently reported that binding of beta(2)GPI to anionic PL facilitates processing and presentation of the cryptic beta(2)GPI epitope that activates pathogenic autoreactive T cells. To clarify mechanisms that induce sustained presentation of the dominant antigenic beta(2)GPI determinant in patients with APS, T-cell proliferation induced by beta(2)GPI-treated phosphatidylserine liposome (beta(2)GPI/PS) was evaluated in bulk peripheral blood mononuclear cell cultures. T cells from patients with APS responded to beta(2)GPI/PS in the presence of immunoglobulin G (IgG) anti-beta(2)GPI antibodies derived from APS plasma, and this response was completely inhibited either by the depletion of monocytes or by the addition of anti-FcgammaRI antibody. These findings indicate that efficient presentation of the cryptic determinants can be achieved by monocytes undergoing FcgammaRI-mediated uptake of beta(2)GPI-bound anionic surfaces in the presence of IgG anti-beta(2)GPI antibodies. Finally, beta(2)GPI-bound oxidized LDL or activated platelets also induced the specific T-cell response. Continuous exposure to these anionic surfaces may play a critical role in maintaining the pathogenic anti-beta(2)GPI antibody response in patients with APS.     

Clinical usefulness of measurement of fibroblast growth factor 23 (FGF23) in hypophosphatemic patients: proposal of diagnostic criteria using FGF23 measurement

Fibroblast growth factor 23 (FGF23) plays important roles in the development of hypophosphatemic diseases such as tumor-induced osteomalacia (TIO) and X-linked hypophosphatemic rickets/osteomalacia (XLH). However, clinical usefulness of measurement of FGF23 has not been established. The objective of this study is to examine the importance of FGF23 measurement in the diagnosis of hypophosphatemic diseases. Biochemical parameters concerning phosphate metabolism were analyzed in a cross-sectional study. 32 patients with TIO, 28 patients with XLH and 16 hypophosphatemic patients with other causes including vitamin D deficiency, Fanconi's syndrome and Cushing's syndrome were studied. In patients with TIO and XLH, FGF23 was above the upper limit of the reference range in most patients irrespective of medical treatment. The lowest FGF23 in these patients was 38.0 pg/ml. FGF23 in hypophosphatemic patients with other causes was undetectable (less than 3 pg/ml) in 12 patients and the highest FGF23 in this group was 23.9 pg/ml. Relationship between phosphate and FGF23 indicated that TIO and XLH are diseases with high FGF23 and hypophosphatemia judged by age-dependent reference ranges for serum phosphate. FGF23 measurement is useful for differential diagnosis of hypophosphatemic diseases caused by excess actions of FGF23 and other etiologies. High FGF23 with low phosphate judged by age-dependent reference ranges for phosphate establishes the diagnosis of diseases caused by excess actions of FGF23.     

IgG4-positive plasma cells in inflammatory abdominal aortic aneurysm: the possibility of an aortic manifestation of IgG4-related sclerosing disease

Inflammatory abdominal aortic aneurysm (IAA) is associated with autoimmune disease. However, the precise mechanism of IAA remains unclear. There is increasing evidence that IgG4 is involved in the autoimmune mechanism of various idiopathic sclerosing lesions, including sclerosing pancreatitis and retroperitoneal fibrosis. The present study investigated the hypothesis that the IgG4-related autoimmune reaction is involved in the formation of IAA. The study group consisted of 11 cases of IAA (69.2 +/- 8.59y) and 12 age-matched cases of atherosclerotic abdominal aortic aneurysm (AAA, 69.6 +/- 5.94y), which were used in the previous report. A clinicopathologic examination of these lesions was performed, including histology and immunohistochemistry, in relation to the involvement of IgG4-positive plasma cells in the formation of IAA. No difference in the incidence of risk factors for atherosclerosis was observed between the patients with IAA and AAA. Autoimmune diseases were diagnosed in 2 patients with IAA, including rheumatoid arthritis and polyarteritis nodosa. A patient with IAA had pulmonary fibrosis. In contrast, autoimmune diseases were absent in patients with AAA. However, there was no significant difference in the incidence of autoimmune diseases between the patients with IAA and AAA. Lymphocyte and plasma cell infiltration and fibrosis were significantly more intense and extensive in IAA than in AAA. In addition, lymph follicle formation and vasculitis of small veins and arteries were frequently found in the affected lesions of IAA. Immunohistochemically, IAA showed a significant increase in the number of infiltrating IgG4-positive plasma cells and the incidence of a disrupted follicular dendritic cell network in lymph follicles, in comparison with AAA. These findings suggest that IAA may be an aortic lesion reflecting the presence of IgG4-related sclerosing disease, and not a simple inflammatory aneurysm of the aorta.     

The severity of ultrasonographic findings in nonalcoholic fatty liver disease reflects the metabolic syndrome and visceral fat accumulation

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is closely associated with the metabolic syndrome. AIM: We evaluated the association among the metabolic syndrome, visceral fat accumulation, and the severity of fatty liver with a new scoring system of ultrasonographic findings in apparently healthy Japanese adults. METHODS: Subjects consisted of 94 patients who received liver biopsy and 4,826 participants who were selected from the general population. Two hepatologists scored the ultrasonographic findings from 0 to 6 points. We calculated Cohen's kappa of within-observer reliability and between-observer reliability. We evaluated the predictive value of the score by the area under a conventional receiver operating characteristic curve (AUC). RESULTS: Within-observer reliability was 0.95 (95% CI 0.93-0.97, P<0.001) and between-observer reliability was 0.95 (95% CI 0.93-0.97, P<0.001). The AUC to diagnose NAFLD was 0.980. The sensitivity was 91.7% (95% CI 87.0-95.1, P<0.001) and the specificity was 100% (95% CI 95.4-100.0, P<0.001). The AUC to diagnose visceral obesity was 0.821. The sensitivity was 68.3% (95% CI 51.9-81.9, P=0.028) and the specificity was 95.1% (95% CI 86.3-99.0, P<0.001). Adjusted odds ratio of the score for the metabolic syndrome was 1.37 (95% CI 1.26-1.49, P<0.001). CONCLUSIONS: The scoring system with abdominal ultrasonography could provide accurate information about hepatic steatosis, visceral obesity, and the metabolic syndrome in apparently healthy people who do not consume alcohol.     

Statistical image analysis of cerebral glucose metabolism in patients with cognitive impairment following diffuse traumatic brain injury

The aim of this study was to explore the regional cerebral glucose metabolism (rCM) in patients with chronic stage traumatic brain injury (TBI) compared with normal controls. We also investigated the relationship between regional cerebral glucose metabolism and cognitive function. We performed 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) study using statistical parametric mapping (SPM) analysis in 36 diffuse axonal injury (DAI) patients (mean age +/- SD, 36.3 +/- 9.8 years). At 6 months or more after head injury, all patients underwent FDG-PET study and neuropsychological batteries to assess cognitive function. Thirty healthy, gender-matched control subjects who were comparable in age were also studied. Between the TBI patients and normal controls, group comparisons showed regional metabolic decreases in the bilateral frontal lobes, temporal lobes, thalamus, as well as the right cerebellum in the TBI group. Only full-scale Intelligence Quotient (IQ) (mean +/- SD, 78.5 +/- 11.9) correlated positively with rCM in the right cingulate gyrus and the bilateral medial frontal gyrus. In other examinations, the correlation was not provided. DAI may induce functional disconnection and decreased neuronal activity, and finally lead to diffuse glucose hypometabolism. Low full-scale IQ scores may be related to significantly different underlying cognitive impairment. In supporting cognitive function following TBI, which showed diffuse cerebral metabolic reduction compared with normal controls, medial prefrontal cortex and anterior cingulate cortex may be an important component.     

Cyst wall resection and ablation by hand-assisted laparoscopic surgery combined with argon plasma coagulator for huge hepatic cysts

Six cases of deroofing of giant liver cysts by hand-assisted laparoscopic surgery (HALS) and safe and definitive cyst wall ablation with argon plasma coagulation (APC), which was verified by pathological examination of the resected cyst wall, were shown.