Extracellular ADP augments microglial inflammasome and NF-κB activation via the P2Y12 receptor.

The NLRP3 inflammasome is a molecular complex that translates signals from pathogens and tissue damage into inflammatory responses, and plays crucial roles in numerous neurological diseases. Activation of the NLRP3 inflammasome leads to caspase-1 dependent cleavage of pro-IL-1ß to form mature IL-1ß. By acting on the P2X7 purinergic receptor, extracellular ATP is one of the major stimuli that activates the NLRP3 inflammasome. Although microglia express multiple purinergic receptors, their roles in inflammasome-mediated inflammation are largely unknown. We studied the role of the P2Y12 receptor, a metabotropic P2Y receptor enriched in microglia, on inflammation in vitro. Inhibition of the microglial P2Y12 receptor by PSB0739 or siRNA knockdown suppressed IL-1ß release. P2Y12 receptor-deficient microglia displayed markedly attenuated IL-1ß mRNA expression and release. P2Y12 receptor blockade also suppressed IL-6 production. Both IL-1ß and IL-6 responses were augmented by extracellular ADP or ADP-ßS and were abrogated by PSB0739. Mechanistically, ADP-ßS potentiated NF-κB activation. In addition, ADP altered mitochondrial membrane potential in combination with ATP and increased the number of caspase-1 positive cells through the P2Y12 receptor. These results elucidate a novel inflammatory mechanism by which extracellular ADP acts on the P2Y12 receptor to activate NF-κB and the NLRP3 inflammasome to enhance microglial inflammation.

Oleic acid to stearic acid ratio might be a potential marker for insulin resistance in non-obese Japanese.

Results from a recent study indicate that a higher level of oleic acid/stearic acid ratio was associated with metabolically unhealthy obesity. This was further validated in cross-sectional and interventional studies; however, this was not extensively studied in a non-obese population. We recruited 260 Japanese subjects with serum free fatty acid profiles undergoing anti-aging health examinations. The determinants for oleic acid/stearic acid ratio were investigated using multiple regression analyses. To compare different markers, the subjects were classified based on oleic acid/stearic acid ratio and the combination of oleic acid/stearic acid ratio and triglyceride levels. The oleic acid/stearic acid ratio exhibited a positive correlation with the logmatic transformed triglyceride/high-density lipoprotein cholesterol ratio and the fasting triglycerides-glucose index, both of which were used as markers for insulin resistance. Multiple regression analyses revealed that the triglyceride/high-density lipoprotein cholesterol ratio and fasting triglyceride-glucose index were positively associated with the oleic acid/stearic acid ratio. Most markers were the worst in the highest triglyceride group in both oleic acid/stearic acid groups. In addition, most markers were worse in high oleic acid/stearic acid ratio group than low group. In conclusion, oleic acid/stearic acid ratio might be a useful marker for insulin resistance in non-obese Japanese subjects.

Factors associated with sleep duration among pupils.

BACKGROUND: Sleep shortage has been pervasive among pupils. METHODS: Multiple regression analysis was used to analyze 2,722 questionnaires obtained from grade 5 to 12 pupils, to determine factors associated with sleep duration. RESULTS: Significant regression formulae for sleep duration were obtained for all school types: adjusted R2 / P value were 0.14/<0.001 for elementary school; 0.11/<0.001 for junior high school; 0.06/<0.001 for high school. Longer after-school activities (standardized regression coefficient/ P value were -0.22/<0.001 for elementary school; -0.10/<0.01 for junior high school; -0.18/<0.001 for high school) and more sleepiness (-0.09/<0.001 for elementary school; -0.07/<0.05 for junior high school; -0.07/<0.05 for high school) were significantly associated with reduced sleep duration for all school types. In both elementary and junior high schools, the higher grade (-0.53/<0.001 for elementary school; -0.10/<0.01 for junior high school), and longer weekday screen time (-0.15/<0.001 for elementary school; -0.19/<0.001 for junior high school) were also significantly associated with sleep loss. In elementary school, irregular dinner (-0.07/<0.05), breakfast skipping (-0.11/<0.001), longer weekend screen time (-0.09/<0.05) and better self-reported academic performance (0.07/<0.05) also revealed significant associations with sleep loss. In high school, reduction of sleep duration was also significantly associated with higher standardized body mass index (-0.08/<0.05). CONCLUSIONS: Excessive after-school activity might be considered in association with pupils' sleep reduction.

Low-density Lipoprotein Subclasses are Associated with Serum Uric Acid Levels.

BACKGROUND: Levels of uric acid (UA) and low-density lipoprotein (LDL) subclasses are both associated with coronary heart disease and metabolic syndrome (MetS). However, the relationship between UA and LDL subclasses is not well understood. METHODS: Subjects included 633 Japanese subjects not receiving medication for hyperuricemia, diabetes mellitus, dyslipidemia, or chronic renal disease who underwent an annual health examination that included determination of small, dense low-density lipoprotein cholesterol (sdLDL-C) and malondialdehyde-modified low-density lipoprotein (MDA-LDL) levels. RESULTS: Serum UA exhibited a positive correlation with both sdLDL-C and MDA-LDL (r = 0.335 and 0.339, respectively). Since sdLDL-C and MDA-LDL show strong positive association, sdLDL-C and MDA-LDL were used as separate explanatory variables in multiple linear regression analysis. Male gender, waist circumference (WC), high-density lipoprotein cholesterol (HDL-C), logarithmic transformed triglyceride (TG) [ln(TG)], and MDALDL as a group were associated with serum UA. Similarly, male gender, body mass index (BMI), ln(TG), and sdLDL-C as a group were associated with serum UA. These results further supported that both MDA-LDL and sdLDL-C levels were positively correlated with serum UA levels. Evaluation of subjects' characteristics according to tertile UA values (tertile 1, < 5.0 mg/dL; tertile 2, 5.0 - < 6.3 mg/dL; tertile 3, ≥ 6.3 mg/dL) indicated that MDALDL and sdLDL-C levels gradually increased with increasing UA levels. Additionally, the upper third UA tertile was associated with the worst metabolic profile based on BMI, WC, blood pressure, fasting plasma glucose, fasting immunoreactive insulin, homeostasis model assessment insulin resistance, TG, HDL-C, and the number of MetS components. CONCLUSIONS: Both LDL particle size and oxidized LDL were associated with serum UA levels in Japanese subjects.

Evaluation of Malondialdehyde Low-Density Lipoprotein Stratified by Low-Density Lipoprotein Cholesterol.

BACKGROUND: Malondialdehyde low-density lipoprotein (MDA-LDL) is a major form of oxidized LDL and considered to be more atherogenic than LDL. Information on major determinants of MDA-LDL and their association in subjects who are not under treatment for diabetes mellitus and dyslipidemia is limited. METHODS: This study included 778 Japanese subjects who were not taking medication for diabetes mellitus and dyslipidemia. All subjects underwent an annual health examination that included MDA-LDL analysis. Study subjects were divided into four groups according to mean values of LDL-C and MDA-LDL, and the metabolic profile was compared. RESULTS: LDL cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were mainly associated with MDA-LDL. When subjects were stratified based on LDL-C levels, small dense LDL-C and MDA-LDL levels increased as LDL-C levels increased. Comparison of the characteristics of study subjects in the same LDL-C level group revealed that subjects with high MDA-LDL showed high metabolic risk in all LDL-C groups, particularly notable in the group with LDL-C levels < 120 mg/dL. CONCLUSIONS: Our data indicated that high LDL-C and low HDL-C levels were independently associated with high MDA-LDL. To prevent high MDA-LDL, it is important to lower LDL-C level as well as to increase HDL-C even in subjects with low LDL-C level by lifestyle modification.

Prediction and Validation of Metabolic Dysfunction-Associated Fatty Liver Disease Using Fatty Liver-Related Indices in a Japanese Population.

Background: Recently, metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. It is uncertain how indices that predict fatty liver are associated with MAFLD in Japanese. Methods: Among subjects who underwent a health examination at our hospital, 1257 (men: 787, women: 474) subjects participated in fatty liver evaluation of the fatty liver index (FLI) and fatty liver predicting index (FLPI) were included in this cross-sectional study. The discriminatory ability of each index for MAFLD was tested using receiver operating characteristic curve analysis. The association between FLI, FLPI, and MAFLD was investigated using multiple logistic regression analysis. Results: FLI and FLPI had good discriminatory ability for identifying MAFLD in both men and women, with specific cutoff values. Both FLI and FLPI were significantly higher in subjects with MAFLD, and the odds of MAFLD were higher among those in the highest tertile relative to the lowest tertile in both men and women. FLI and FLPI were higher in subjects who met the criteria for both MAFLD and metabolic syndrome (MetS) compared to those who had MAFLD or MetS alone, and most of the examined parameters in subjects with both conditions indicated a high metabolic risk profile. Conclusions: The study suggests that FLI and FLPI are valuable tools for predicting MAFLD and are similarly correlated with the disease. Furthermore, the highest values of these indices were observed in subjects who met the criteria for both MAFLD and MetS, emphasizing the importance of considering both conditions when assessing metabolic risk.

Oxygen-Glucose Deprivation Increases NR4A1 Expression and Promotes Its Extranuclear Translocation in Mouse Astrocytes.

Hypoxic-ischemic brain injury induces metabolic dysfunction that ultimately leads to neuronal cell death. Astrocytes, a type of glial cell, play a key role in brain metabolism; however, their response to hypoxic-ischemic brain injury is not fully understood. Microglia were removed from murine primary mixed glial cultures to enrich astrocytes. Next, we explored genes whose expression is altered following oxygen-glucose deprivation using a microarray. Microarray analysis revealed that the expression of Nr4a1 and Nr4a3 is markedly increased in astrocyte-enriched cultures after 15 h of oxygen-glucose deprivation. The expression of both Nr4a1 and Nr4a3 was regulated by HIF-1α. At the protein level, NR4A1 was translocated from the nucleus to the cytoplasm following oxygen-glucose deprivation and co-localized with mitochondria in apoptotic cells; however, its localization was restored to the nucleus after reoxygenation. Oxygen-glucose deprivation causes an increase in NR4A1 mRNA in astrocytes as well as its nuclear to cytoplasmic transfer. Furthermore, reoxygenation enhances NR4A1 transcription and promotes its nuclear translocation.

Comparative study of MAFLD as a predictor of metabolic disease treatment for NAFLD.

A novel concept of Metabolic Associated Fatty Liver Disease (MAFLD) was proposed, incorporating metabolic abnormalities such as obesity and diabetes, which are risk factors that affect the prognosis. Non-Alcoholic Fatty Liver Disease (NAFLD), entails fat accumulation in the liver without alcohol consumption and is often linked to obesity, insulin resistance, and metabolic syndrome. However, the broad nature of the disease concept has hindered prognosis accuracy. In this study, we assess the contribution of the impact of diagnostic criteria for MAFLD on metabolic disease progression compared to conventional diagnostic criteria for NAFLD. A total of 7159 patient who were presented to the health screening center in Tokai University Hospital both in 2015 and 2020 were included in the study. Fatty liver was diagnosed using abdominal ultrasonography. The diagnostic criteria for NAFLD were consistent with the global guidelines based on alcohol consumption. The diagnostic criteria for MAFLD were based on the International Consensus Panel. Medications (anti-hypertensive, diabetic, and dyslipidemia medications) were evaluated by self-administration in the submitted medical questionnaire. A total of 2500 (34.9%) participants were diagnosed with fatty liver (FL +), 1811 (72.4%) fit both NAFLD and MAFLD diagnostic criteria (overlap), 230 (9.2%) fit only the NAFLD diagnostic criteria (NAFLD group) and 404 (16.1%) fit the MAFLD diagnostic criteria (MAFLD group) at 2015. Over the next 5 years, medication rates increased in the NAFLD group for anti-hypertensive, + 17 (7.4%); diabetes, + 3 (1.3%); and dyslipidemia, + 32 (13.9%). In contrast, the only-MAFLD group showed a more significant increase with + 49 (12.1%), + 21 (5.2%), and + 49 (12.1%), for the respective medications, indicating a substantial rise in patients starting new medications. Our analysis of repeated health check-ups on participants revealed that the diagnostic criteria for MAFLD are more predictive of future treatment for metabolic disease than conventional diagnostic criteria for NAFLD.

ATP1A3-related early childhood onset developmental and epileptic encephalopathy responding to corpus callosotomy: A case report.

BACKGROUND: VariousATP1A3variant-related diseases have been reported, including alternating hemiplegia of childhood; rapid-onset dystonia-parkinsonism; and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss syndrome. Moreover, a few cases of developmental and epileptic encephalopathy (DEE) with none of these symptoms have been reported. Here, we present a case of DEE with early childhood onset caused by anATP1A3variant that was effectively treated using corpus callosotomy (CC). CASE PRESENTATION: At the age of 3 years, the patient developed epileptic spasms, complicated by generalized and focal aware tonic seizures. Based on the seizure type and electroencephalographic findings showing a generalized spike and waves as well as interictal left frontal-dominant spikes, combined generalized and focal epilepsy was diagnosed. Whole-exome sequencing revealed a de novo missense variant inATP1A3(c.2888G > A, p.Gly963Asp), which was classified as likely pathogenic. At the age of 5 years, CC for generalized tonic seizures resulted in seizure-freedom using two anti-seizure medications. Subsequently, the patient achieved better verbal development. DISCUSSION AND CONCLUSION: Early childhood onset DEE has not been reported in patients with ATP1A3 variants. Moreover, CC was extremely effective in our case. Although more research is needed to determine the etiology of epilepsy caused by theATP1A3 variant, the clinical course of DEE caused by the ATP1A3 variant is diverse and its prognosis may be improved in early childhood onset cases using aggressive control of epilepsy, such as CC.

Lipocalin-2 production by astrocytes in response to high concentrations of glutamate.

AIMS: Glutamate-induced excitotoxicity is mainly mediated by neuronal NMDA receptors; however, it is unclear how astrocytes are involved in this phenomenon. This study aimed to explore the effects of excess glutamate on astrocytes both in vitro and in vivo. METHODS: We used astrocyte-enriched cultures (AECs), in which microglia were removed from mixed glial cultures, to investigate the effects of extracellular glutamate on these cells by microarray, quantitative PCR, ELISA, and immunostaining. We also examined the production of lipocalin-2 (Lcn2) by immunohistochemistry in the brains of mice after status epilepticus induced by pilocarpine and by ELISA in the cerebrospinal fluid (CSF) of patients characterised by status epilepticus. RESULTS: Microarray analysis identified Lcn2 as a factor upregulated in AECs by excess glutamate; glutamate addition increased Lcn2 in the cytoplasm of astrocytes and AECs released Lcn2 in a concentration-dependent manner. Lcn2 production was reduced by chemical inhibition of metabotropic glutamate receptor or siRNA knockdown of metabotropic glutamate receptor 3. Furthermore, Lcn2 was increased in the astrocytes of a status epilepticus mouse model and in the CSF of human patients. CONCLUSION: These results indicate that astrocytes stimulate Lcn2 production via metabotropic glutamate receptor 3 in response to high concentrations of glutamate.

Prediction and Validation of Metabolic Dysfunction-Associated Fatty Liver Disease Using Insulin Resistance-Related Indices in the Japanese Population.

Background: Recently, metabolic dysfunction-associated fatty liver disease (MAFLD), which is based on evidence of hepatic steatosis and any of the following three conditions: overweight/obesity, presence of type 2 diabetes mellitus, or evidence of metabolic dysregulation, has been proposed. It is uncertain how indices that predict insulin resistance (IR) are associated with MAFLD. Methods: Among subjects who had undergone health examinations at our hospital, 1,257 (787 men and 474 women) who underwent fatty liver evaluation, were included in this cross-sectional study. The discriminatory ability of each index for MAFLD was tested using a receiver operating characteristic curve analysis. The associations between the homeostasis model assessment-IR (HOMA-IR), triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, triglyceride-glucose (TyG) index, and MAFLD were investigated using multiple logistic regression analysis. Results: The mean age and body mass index of MAFLD subjects were 58.1 years and 26.0 kg/m2 in men and 63.0 years and 26.1 kg/m2 in women, respectively. The cutoff values of HOMA-IR, TG/HDL-C ratio, and TyG index in men and women were 1.40 (area under the curve [AUC]: 0.81) and 1.90 (AUC: 0.88); 1.56 (AUC: 0.75) and 1.06 (AUC: 0.78); and 8.62 (AUC: 0.75) and 8.45 (AUC: 0.80), respectively. All indices were significantly higher in both men and women with MAFLD. In the multivariate models, the odds of MAFLD were higher among both men and women in the highest tertile than those in the lowest tertile. When subjects were divided by sex, presence of MAFLD, and alanine aminotransferase (ALT) values, all indices were significantly higher in both men and women with high ALT levels who were diagnosed with MAFLD. Conclusion: IR strongly correlated with MAFLD, particularly in subjects with high ALT levels.

Relationship Between Pancreatic Cysts and Cysts in Other Organs in Patients Undergoing Medical Checkup.

OBJECTIVE: We investigated the association between pancreatic cysts and cystic diseases of other organs using abdominal ultrasonography in patients undergoing medical checkup. METHODS: Between April 2021 and March 2022, 4496 patients had a comprehensive medical checkup at our hospital, which included abdominal ultrasonography. RESULTS: Among 4496 patients, 172 (3.8%), 1592 (35.4%), and 1425 (31.7%) had pancreatic, liver, and renal cysts, respectively. Multivariate analysis revealed that the significant factors were female sex and the presence of renal cysts. CONCLUSION: Pancreatic cysts were more common in females. Renal cysts are relatively commonly detected on abdominal ultrasonography. If renal cysts are detected, comorbidities with pancreatic cysts should be considered.

Self-rated health as a comprehensive indicator of lifestyle-related health status.

OBJECTIVES: To evaluate the usefulness of self-rated health (SRH) as a comprehensive indicator of lifestyle-related health status by examining the relationships between SRH and: (1) history of cancer and cardiovascular disease; (2) treatment of hypertension, diabetes, and dyslipidemia; (3) abnormalities in clinical parameters including blood pressure, fasting glucose, and lipids; and (4) lifestyle habits. METHODS: 3744 health-check examinees at Tokai University Hachioji Hospital seen between April 2009 and March 2010 were enrolled. SRH was graded as "good," "relatively good," "relatively poor," or "poor." For statistical comparison, the differences among "healthy" (=good), "relatively healthy" (=relatively good), and "unhealthy" (=relatively poor plus poor) groups were examined. Mantel-Haenszel odds ratios were calculated to remove the confounding effect of age, using the healthy group as the reference. The Mantel-extension method was used as a trend test. RESULTS: 1049 subjects rated their health as good, 2194 as relatively good, 428 as relatively poor, and 73 as poor. The prevalence of all diseases showed significant odds ratios and trends as SRH deteriorated. Obesity, blood pressure, glucose metabolism, and lipids deteriorated significantly as SRH became poorer, and a trend was observed in all parameters. Weight change, exercise, smoking, and rest showed significant odds ratios and trends as SRH deteriorated. CONCLUSION: SRH appears useful as a comprehensive indicator of lifestyle-related health status.

Estimated Elovl6 and delta-5 desaturase activities might represent potential markers for insulin resistance in Japanese adults.

Purpose: Results from a recent study indicated that lower stearic acid/palmitic acid (SA/PA) and arachidonic acid/dihomo-γ-linolenic acid (AA/DGLA) ratios were associated with metabolically unhealthy obesity. However, this has not been extensively studied in the Japanese population. Methods: We recruited 291 Japanese subjects with serum free fatty acid profiles undergoing health examinations. Whole serum desaturase activity was estimated as the product: precursor ratio -SA/PA ratio for elongation of long-chain fatty acid family member 6 (Elovl6) and AA/DGLA for delta-5 desaturase (D5D). The determinants of Elovl6 and D5D activity were investigated using multiple regression analyses. Results: The Elovl6 and D5D activities exhibited a negative correlation with the logmatic-transformed TG/HDL-C ratio and TyG index. Multiple regression analyses revealed that the TG/HDL-C ratio and TyG index were negatively associated with Elovl6 and D5D activities. Most atherogenic markers were worse in the low Elovl6 or D5D activity group than in the high Elovl6 or D5D activity group. When study subjects were further stratified by TG levels, most atherogenic markers were the worst in the highest TG group in either the lowest Elovl6 or lowest D5D activity groups. Conclusion: The estimated Elovl6 and D5D activities might be useful markers of insulin resistance in Japanese subjects.

Analysis of Comorbidity for Patients with Pancreatic Cysts in Medical Checkup Screening.

OBJECTIVES: We investigated whether there is a difference in the frequency of comorbidity between patients with pancreatic cysts and those without pancreatic cysts by abdominal ultrasonography in patients undergoing medical checkup screening. METHODS: The subjects were 6,627 patients who underwent abdominal ultrasonography at Tokai University Hachioji Hospital's Health Screening Center between April 2019 and March 2020. RESULTS: Of the total 6,627 patients, 158 (2.4%) were pointed out to have pancreatic cysts. Multivariate analysis revealed that the related factors were female sex, age 60 years or older, diabetes, lung cancer, and uterine/ovarian cancer. CONCLUSION: Unlike pancreatic cancer, pancreatic cysts are more common in women. In addition, it is known that pancreatic cysts have a high complication rate of cancers of other organs; lung cancer and uterine/ovarian cancer were identified as high-risk factors in this study.

Association of High-Density Lipoprotein Subclasses Levels with Sleep Duration and Other Lifestyles in Middle-Aged and Elderly Women: Cross-Sectional Study.

Objective: We aimed at investigating the association of high-density lipoprotein subclasses (HDL2-C and HDL3-C) levels with sleep duration, in comparison to other lifestyles in middle-aged and elderly women. Materials and Methods: A total of 69 women aged older than 40 who underwent "Anti-aging Health Checkups" were enrolled in the study. The analyses were conducted for all the subjects using personal data regarding clinical characteristics and lifestyle. Sleep duration was categorized into two groups of less than or more than 6 hrs. First, an analysis was performed to assess the correlation of two major HDL subclasses with various factors. Next, a multiple regression analysis was conducted to identify the association for each HDL2-C and HDL3-C with lifestyles such as sleep duration, daily breakfast, dinner time, habitual exercise, and drinking. Moreover, we examined the associations between HDL2-C and sleep duration combined with other lifestyle factors such as dinner time, daily breakfast, habitual exercise, and drinking. Results: In comparison to lifestyles, sleep duration had a strong association with only HDL2-C after adjustment for confounders. The "less 6 hrs sleep" group in combination with the "no exercise habit" or the "routine drinking habit" significantly decreased HDL2-C levels more than the assumed reference group. Regarding breakfast, there is a significant association between the "less than 6 hrs sleep with no daily breakfast" and the "more than 6 hrs sleep with daily breakfast." Conclusion: The results of this study may suggest that sufficient sleep might be significant for maintaining appropriate HDL2-C levels in middle-aged and elderly women under the condition that lifestyle might change during the ongoing COVID-19 pandemic.

Adenosine A2A receptor is involved in cell surface expression of A2B receptor.

The A2A and A2B adenosine receptors (A2AR and A2BR) are implicated in many physiological processes. However, the mechanisms of their intracellular maturation and trafficking are poorly understood. In comparative studies of A2AR versus A2BR expression in transfected cells, we noticed that the levels of cell surface expression of A2BR were significantly lower than those of A2AR. A large portion of the A2BR was degraded by the proteasome. Studies of cell surface expression of A2BR chimeric molecules in transfectants suggested that A2BR does not have the dominant forward transport signal for export from the endoplasmic reticulum to the cell surface. A2BR surface expression was increased in A2BR chimeras where the A2BR carboxyl terminus (CT) was replaced or fused with the A2AR CT. Co-transfection of A2AR with A2BR enhanced surface expression of A2BR though the F(X)(6)LL motif in the A2AR CT. The requirements of A2AR expression for better A2BR cell surface expression was not only established in transfectants but also confirmed by observations of much lower levels of A2BR-induced intracellular cAMP accumulation in response to A2BR-activating ligand in splenocytes from A2AR(-/-) mice than in wild type mice. The results of mechanistic studies suggested that poor A2BR expression at the cell surface might be accounted for mainly by the lack of a dominant forward transport signal from the endoplasmic reticulum to the plasma membrane; it is likely that A2BR forms a hetero-oligomer complex for better function.

Assembly of the biogenesis of lysosome-related organelles complex-3 (BLOC-3) and its interaction with Rab9.

The Hermansky-Pudlak syndrome (HPS) is a genetic hypopigmentation and bleeding disorder caused by defective biogenesis of lysosome-related organelles (LROs) such as melanosomes and platelet dense bodies. HPS arises from mutations in any of 8 genes in humans and 16 genes in mice. Two of these genes, HPS1 and HPS4, encode components of the biogenesis of lysosome-related organelles complex-3 (BLOC-3). Herein we show that recombinant HPS1-HPS4 produced in insect cells can be efficiently isolated as a 1:1 heterodimer. Analytical ultracentrifugation reveals that this complex has a molecular mass of 146 kDa, equivalent to that of the native complex and to the sum of the predicted molecular masses of HPS1 and HPS4. This indicates that HPS1 and HPS4 interact directly in the absence of any other protein as part of BLOC-3. Limited proteolysis and deletion analyses show that both subunits interact with one another throughout most of their lengths with the sole exception of a long, unstructured loop in the central part of HPS4. An interaction screen reveals a specific and strong interaction of BLOC-3 with the GTP-bound form of the endosomal GTPase, Rab9. This interaction is mediated by HPS4 and the switch I and II regions of Rab9. These characteristics indicate that BLOC-3 might function as a Rab9 effector in the biogenesis of LROs.

Evaluation of the Diagnostic Criteria for Anti-NMDA Receptor Encephalitis in Japanese Children.

OBJECTIVE: To evaluate the validity of the 2016 clinical diagnostic criteria proposed for probable anti-NMDA receptor (NMDAR) encephalitis in children, we tested the criteria in a Japanese pediatric cohort. METHODS: We retrospectively reviewed clinical information of patients with neurologic symptoms whose CSF was analyzed for NMDAR antibodies (NMDAR-Abs) in our laboratory from January 1, 2015, to March 31, 2019. RESULTS: Overall, 137 cases were included. Of the 41 cases diagnosed as probable anti-NMDAR encephalitis (criteria-positive) according to the 2016 criteria, 13 were positive and 28 were negative for anti-NMDAR-Abs. Of the 96 criteria-negative cases, 3 were positive and 93 were negative for anti-NMDAR-Abs. The sensitivity of the criteria was 81.2%, specificity was 76.9%, positive predictive value (PPV) was 31.7%, and negative predictive value was 96.9%. Compared with the true-positive group, the false-positive group contained more male than female patients (male:female, 4:9 in the true-positive vs 19:9 in the false-positive group, p = 0.0425). The majority of the cases with false-positive diagnoses were associated with neurologic autoimmunity. CONCLUSION: The clinical diagnostic criteria are reliable for deciding to start immunomodulatory therapy in the criteria-positive cases. Low PPV may be caused by a lower prevalence of NMDAR encephalitis or lower level of suspicion for encephalitis in the pediatric population. Physicians should therefore continue differential diagnosis, focusing especially on other forms of encephalitis. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that the proposed diagnostic criteria for anti-NMDAR encephalitis in children has a sensitivity of 81.2% and a specificity of 76.9%.