PP2A catalytic subunit alpha is critically required for CD8+ T-cell homeostasis and antibacterial responses.

Although the functions of tyrosine phosphatases in T-cell biology have been extensively studied, our knowledge on the contribution of serine/threonine phosphatases in T cells remains poor. Protein phosphatase 2A (PP2A) is one of the most abundantly expressed serine/threonine phosphatases. It is important in thymocyte development and CD4+ T-cell differentiation. Utilizing a genetic model in which its catalytic subunit alpha isoform (PP2A Cα) is deleted in T cells, we investigated its contribution to CD8+ T-cell homeostasis and effector functions. Our results demonstrate that T-cell intrinsic PP2A Cα is critically required for CD8+ T-cell homeostasis in secondary lymphoid organs and intestinal mucosal site. Importantly, PP2A Cα-deficient CD8+ T cells exhibit reduced proliferation and survival. CD8+ T-cell antibacterial response is strictly dependent on PP2A Cα. Expression of Bcl2 transgene rescues CD8+ T-cell homeostasis in spleens, but not in intestinal mucosal site, nor does it restore defective antibacterial responses. Finally, proteomics and phosphoproteomics analyses reveal potential targets dependent on PP2A Cα, including mTORC1 and AKT. Thus, PP2A Cα is a key modulator of CD8+ T-cell homeostasis and effector functions.

Downregulation of HMGB1 carried by macrophage-derived extracellular vesicles delays atherosclerotic plaque formation through Caspase-11-dependent macrophage pyroptosis.

BACKGROUND: Macrophage-derived extracellular vesicle (macrophage-EV) is highly studied for its regulatory role in atherosclerosis (AS). Our current study tried to elucidate the possible role of macrophage-EV loaded with small interfering RNA against high-mobility group box 1 (siHMGB1) affecting atherosclerotic plaque formation. METHODS: In silico analysis was performed to find critical factors in mouse atherosclerotic plaque formation. EVs secreted by RAW 264.7 cells were collected by ultracentrifugation and characterized, followed by the preparation of macrophage-EV-loaded siHMGB1 (macrophage-EV/siHMGB1). ApoE-/- mice were used to construct an AS mouse model by a high-fat diet, followed by injection of macrophage-EV/siHMGB1 to assess the in vivo effect of macrophage-EV/siHMGB1 on AS mice. RAW264.7 cells were subjected to ox-LDL, LPS or macrophage-EV/siHMGB1 for analyzing the in vitro effect of macrophage-EV/siHMGB1 on macrophage pyrophosis and inflammation. RESULTS: In silico analysis found that HMGB1 was closely related to the development of AS. Macrophage-EV/siHMGB could inhibit the release of HMGB1 from macrophages to outside cells, and the reduced HMGB1 release could inhibit foam cell formation. Besides, macrophage-EV/siHMGB also inhibited the LPS-induced Caspase-11 activation, thus inhibiting macrophage pyroptosis and preventing atherosclerotic plaque formation. CONCLUSION: Our results proved that macrophage-EV/siHMGB could inhibit foam cell formation and suppress macrophage pyroptosis, finally preventing atherosclerotic plaque formation in AS mice.

Multiple Early Biomarkers to Predict Cognitive Decline in Dementia-Free Older Adults.

INTRODUCTION: Baseline olfactory impairment, poor performance on cognitive test, and medial temporal lobe atrophy are considered biomarkers for predicting future cognitive decline in dementia-free older adults. However, the combined effect of these predictors has not been fully investigated. METHODS: A group of 110 participants without dementia were continuously recruited into this study, and underwent olfactory, cognitive tests and MRI scanning at baseline and 5-year follow-up. Olfactory function was assessed using the University of Pennsylvania Smell Identification Test (UPSIT). Participants were divided into the cognitive decliners and non-decliners. RESULTS: Among 87 participants who completed the 5-year follow-up, cognitive decline was present in 32 cases and 55 remained stable. Compared with non-decliners, cognitive decliners presented lower scores on both the UPSIT and the Montreal Cognitive Assessment (MoCA), and smaller hippocampal volume at baseline (all P < .001). The logistic regression analysis revealed that lower scores on UPSIT and MoCA, and smaller hippocampal volume were strongly associated with subsequent cognitive decline, respectively (all P < .001). For the prediction of cognitive decline, lower score on UPSIT performed the sensitivity of 63.6% and specificity of 81.2%, lower score on MoCA with the sensitivity of 74.5% and specificity of 65.6%, smaller hippocampal volume with the sensitivity of 70.9% and specificity of 78.1%, respectively. Combining three predictors resulted in the sensitivity of 83.6% and specificity of 93.7%. CONCLUSIONS: The combination of olfactory test, cognitive test with structural MRI may enhance the predictive ability for future cognitive decline for dementia-free older adults.

Self-concept mediates the relationships between childhood traumatic experiences and adolescent depression in both clinical and community samples.

BACKGROUND: Childhood trauma is a pivotal risk factor for adolescent depression. While the association between childhood trauma and depression is well-established, the mediating role of self-concept has not been acknowledged. Specifically, limited attention has been paid to how childhood maltreatment impacts adolescent depression through physical and social self-concept, both in clinical and community samples. This study aims to investigate how distinct and cumulative childhood trauma affects adolescent depression, as well as the potential mediating role of self-concept in their relationships. METHODS: We recruited 227 depressed adolescents (dataset 1, 45 males, age = 15.34 ± 1.96) and 574 community adolescents (dataset 2, 107 males, age = 16.79 ± 0.65). Each participant was assessed on five subtypes of childhood trauma severity, cumulative trauma index, physical and social self-concept, and depression. Mediation models were tested separately in the clinical and community samples. RESULTS: Clinically depressed adolescents experienced a higher level of trauma severity, a greater number of trauma subtypes, and had lower levels of physical and social self-concept compared to community adolescents. Analyses on childhood trauma severity and cumulative trauma index jointly indicated that physical and social self-concept played mediation roles in the relationships between childhood trauma experiences and depression. Moreover, the mediating effects of self-concept were stronger in depressed adolescents when compared to community samples. CONCLUSIONS: Our findings suggest that physical and social self-concept play mediating roles in the pathway linking childhood trauma and adolescent depression, particularly in clinically depressed individuals.

Automatic synthesis of 18F-AV-45 and its clinical application in Alzheimer's disease.

OBJECTIVE: To investigate the automatic synthesis of ß-amyloid (Aß) positron emission tomography (PET) imaging agent (E) -4- (2- (6- (2- (2-18F fluoroethoxy) ethoxy) ethoxy) pyridine-3-yl) vinyl) - N-methylaniline (18F-AV-45) for the diagnosis of Alzheimer's disease (AD) and its clinical application in AD patients. MATERIALS AND METHODS: Fluorine-18-AV-45 was synthesized with AV-105 as the precursor, and the factors affecting the synthesis efficiency, such as the amount of precursor, nucleophilic reaction temperature were studied. At the same time, 18F-AV-45 PET/computed tomography (CT) brain scanning was performed in 15 patients with dementia to determine whether AD was the cause of the dementia. RESULTS: After optimizing the parameters, it was discovered that the highest synthesis efficiency was achieved with a AV-105 dosage of 2mg, a reaction temperature of 130oC, and 1mL of DMSO. The radiochemical yield (RCP) was greater than 98, and the uncorrected synthesis efficiency was about 31.0%±2.8%. Ten of the 15 patients with dementia showed positive Aß protein deposition, and the main deposition site of the imaging agent was the gray matter area of the brain, which was consistent with AD diagnosis, while the other 5 patients showed negative Aß protein deposition, suggesting non-AD dementia. CONCLUSION: ß-amyloid protein 18F-AV-45 imaging agent can be easily and quickly prepared by the All in One radiochemical synthesis module. Our preliminary results offer hope that it can effectively detect ß-amyloid deposition in the brain of AD patients in order to determine the etiology of dementia.

Diagnostic Performance of 18 F-FDG Positron Emission Tomography/Computed Tomography and Blood Test Parameters for Pulmonary Inflammatory Pseudotumor.

PURPOSE: Pulmonary inflammatory pseudotumor (PIP) is an inflammatory proliferative tumor-like lesion that frequently exhibits hypermetabolism on 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography imaging (PET/CT) and is readily misdiagnosed as a malignant tumor. The purpose of this study was to identify PIP by combining PET/computed tomography metabolic and blood test characteristics with machine learning. PATIENTS AND METHODS: We recruited 27 patients with PIP and 28 patients with lung cancer (LC). The PET metabolic and blood test parameters were collected, and the differences between the groups were evaluated. In addition, we combined the support vector machine (SVM) classifier with the indicators that differed between the groups to classify PIP and LC. RESULTS: For PET metabolic parameters, our findings showed that, as compared with the LC group, maximal standardized uptake value ( P < 0.001, t = -4.780), Mean standardized uptake value SUV mean , P < 0.001, t = -4.946), and SD40% ( P < 0.001, t = -4.893) were considerably reduced in the PIP group, whereas CV40% ( P = 0.004, t = 3.012) was significantly greater. For blood test parameters, the total white blood cell count ( P < 0.001, t = 6.457) and absolute neutrophil count ( P < 0.001, t = 6.992) were substantially higher in the PIP group than in the LC group. Furthermore, the performance of SVM trained solely on PET metabolic parameters (mean area under the curve [AUC] = 0.84) was comparable to that of SVM trained solely on blood test parameters (mean AUC = 0.86). Surprisingly, utilizing the combined parameters increased SVM performance significantly (mean AUC = 0.98). CONCLUSION: PET metabolic and blood test parameters differed significantly between the PIP and LC groups, and the SVM paradigm using these significantly different features has the potential to be used to classify PIP and LC, which has important clinical implications.

CPT2 mediated fatty acid oxidation is dispensable for humoral immunity.

B cell activation is accompanied by dynamic metabolic reprogramming, supported by a multitude of nutrients that include glucose, amino acids and fatty acids. While several studies have indicated that fatty acid mitochondrial oxidation is critical for immune cell functions, contradictory findings have been reported. Carnitine palmitoyltransferase II (CPT2) is a critical enzyme for long-chain fatty acid oxidation in mitochondria. Here, we test the requirement of CPT2 for humoral immunity using a mouse model with a lymphocyte specific deletion of CPT2. Stable 13C isotope tracing reveals highly reduced fatty acid-derived citrate production in CPT2 deficient B cells. Yet, CPT2 deficiency has no significant impact on B cell development, B cell activation, germinal center formation, and antibody production upon either thymus-dependent or -independent antigen challenges. Together, our findings indicate that CPT2 mediated fatty acid oxidation is dispensable for humoral immunity, highlighting the metabolic flexibility of lymphocytes.

Novel ß-amyloid PET Imaging Study of [18F]92 in Patients with Cognitive Decline.

[18F]-4-((E)-(((E)-4-(2-(2-(2-Fluoroethoxy)ethoxy)ethoxy)benzylidene)-hydrazono)methyl)-N-methylaniline ([18F]92) is a novel positron emission tomography (PET) tracer previously reported to exhibit high binding affinity to aggregated ß-amyloid (Aß). This study aims to report a fully automated radiosynthesis procedure for [18F]92, explore its radioactive distribution in the brains of healthy subjects, and investigate its potential application value in the early diagnosis of Alzheimer's disease (AD). The fully automated radiosynthesis of [18F]92 was performed on the AllinOne module. Thirty one participants were recruited for this study. Dynamic [18F]92 PET imaging was conducted over 0-90 min period to assess time-activity curves (TAC) and standardized uptake value ratio (SUVR) curves in cognitively normal (CN) subjects. All participants were visually classified as either positive (+) or negative (-). Semiquantitative analyses of [18F]92 were performed by calculating SUVRs in different regions of interest. Furthermore, the study analyzed the relationships between global SUVR and plasma AD biomarkers, including Aß42, Aß40, P-tau181, and T-tau. The automated radiosynthesis of [18F]92 was completed within 50 min, yielding a radiochemical purity of greater than 95% and a radiochemical yield of 36 ± 3% (nondecay-corrected). Among the participants, 15 were estimated as Aß (-) and 16 as Aß (+). TACs indicated that [18F]92 rapidly crossed the blood-brain barrier within 10 min, followed by a rapid decrease, which then slowed down in the last 50-90 min. SUVR curves revealed that SUVR values stabilized around 60-70 min after injection and reached an equilibrium between 70 and 90 min, primarily in the cerebral cortex. SUVRs of Aß (+) participants were significantly higher than those of Aß (-) individuals within the cerebral cortex. In addition, Aß42 and the Aß42/Aß40 ratio exhibited negative correlations with global SUVR, while plasma P-tau181 and the P-tau181/T-tau ratio displayed positive correlations with global SUVR. [18F]92 exhibits excellent pharmacokinetic properties in the human brain and can be synthesized automatically on a large scale. [18F]92 is a promising and reliable radiotracer for estimating Aß pathology accumulation, providing valuable assistance in AD diagnosis and guiding clinical trials of therapeutic drugs.

The nutrient-sensing Rag-GTPase complex in B cells controls humoral immunity via TFEB/TFE3-dependent mitochondrial fitness.

During the humoral immune response, B cells undergo rapid metabolic reprogramming with a high demand for nutrients, which are vital to sustain the formation of the germinal centers (GCs). Rag-GTPases sense amino acid availability to modulate the mechanistic target of rapamycin complex 1 (mTORC1) pathway and suppress transcription factor EB (TFEB) and transcription factor enhancer 3 (TFE3), members of the microphthalmia (MiT/TFE) family of HLH-leucine zipper transcription factors. However, how Rag-GTPases coordinate amino acid sensing, mTORC1 activation, and TFEB/TFE3 activity in humoral immunity remains undefined. Here, we show that B cell-intrinsic Rag-GTPases are critical for the development and activation of B cells. RagA/RagB deficient B cells fail to form GCs, produce antibodies, and generate plasmablasts in both T-dependent (TD) and T-independent (TI) humoral immune responses. Deletion of RagA/RagB in GC B cells leads to abnormal dark zone (DZ) to light zone (LZ) ratio and reduced affinity maturation. Mechanistically, the Rag-GTPase complex constrains TFEB/TFE3 activity to prevent mitophagy dysregulation and maintain mitochondrial fitness in B cells, which are independent of canonical mTORC1 activation. TFEB/TFE3 deletion restores B cell development, GC formation in Peyer's patches and TI humoral immunity, but not TD humoral immunity in the absence of Rag-GTPases. Collectively, our data establish Rag-GTPase-TFEB/TFE3 pathway as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.

Rag-GTPase-TFEB/TFE3 axis controls B cell mitochondrial fitness and humoral immunity independent of mTORC1.

During the humoral immune response, B cells undergo rapid metabolic reprogramming with a high demand for nutrients, which are vital to sustain the formation of the germinal centers (GCs). Rag-GTPases sense amino acid availability to modulate the mechanistic target of rapamycin complex 1 (mTORC1) pathway and suppress transcription factor EB (TFEB) and transcription factor enhancer 3 (TFE3), members of the microphthalmia (MiT/TFE) family of HLH-leucine zipper transcription factors. However, how Rag-GTPases coordinate amino acid sensing, mTORC1 activation, and TFEB/TFE3 activity in humoral immunity remains undefined. Here, we show that B cell-intrinsic Rag-GTPases are critical for the development and activation of B cells. RagA/RagB deficient B cells fail to form GCs, produce antibodies, and generate plasmablasts in both T-dependent (TD) and T-independent (TI) humoral immune responses. Deletion of RagA/RagB in GC B cells leads to abnormal dark zone (DZ) to light zone (LZ) ratio and reduced affinity maturation. Mechanistically, the Rag-GTPase complex constrains TFEB/TFE3 activity to prevent mitophagy dysregulation and maintain mitochondrial fitness in B cells, which are independent of canonical mTORC1 activation. TFEB/TFE3 deletion restores B cell development, GC formation in Peyer's patches and TI humoral immunity, but not TD humoral immunity in the absence of Rag-GTPases. Collectively, our data establish Rag-GTPase-TFEB/TFE3 axis as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.

PP2A catalytic subunit alpha is critically required for CD8+ T cell homeostasis and anti-bacterial responses.

While the functions of tyrosine phosphatases in T cell biology have been extensively studied, our knowledge on the contribution of serine/threonine phosphatases in T cells remains poor. Protein phosphatase 2A (PP2A) is one of the most abundantly expressed serine/threonine phosphatases. It is important in thymocyte development and CD4+ T cell differentiation. Utilizing a genetic model in which its catalytic subunit alpha isoform (PP2A Cα) is deleted in T cells, we investigated its contribution to CD8+ T cell homeostasis and effector functions. Our results demonstrate that T cell intrinsic PP2A Cα is critically required for CD8+ T cell homeostasis in secondary lymphoid organs and intestinal mucosal site. Importantly, PP2A Cα deficient CD8+ T cells exhibit reduced proliferation and survival. CD8+ T cell anti-bacterial response is strictly dependent on PP2A Cα. Expression of Bcl2 transgene rescues CD8+ T cell homeostasis in spleens, but not in intestinal mucosal site, nor does it restore the defective anti-bacterial responses. Finally, proteomics and phosphoproteomics analyses reveal potential targets dependent on PP2A Cα, including mTORC1 and AKT. Thus, PP2A Cα is a key modulator of CD8+ T cell homeostasis and effector functions.

Effect of prodigiosin on the alleviation of the intestinal inflammation of weaned rats based on 1H-NMR spectroscopy study and biochemistry indexes

Weaning results in intestinal dysfunction, mucosal atrophy, transient anorexia, and intestinal barrier defects. In this study, the effect of prodigiosin (PG) on the intestinal inflammation of weaned rats was investigated by using 1H-NMR spectroscopy and biochemistry indexes to regulate the intestinal metabolism. After administration for 14 days, the body mass of the PG group was increased by 1.29- and 1.26-fold compared with those of the control and alcohol groups, respectively, using a dose of 200 µg PG·kg-1 body weight per day. PG increased organic acid content and decreased moisture, pH values, and free ammonia in feces. In addition, PG alleviated the intestinal inflammation of weaned rats. The analysis of 1H-NMR signal peak attribution and the model validation of metabolic data of feces contents showed that PG significantly affected the metabolism of small molecular compounds in the intestinal tract of weaned rats. This study presents the promising alternative of using PG to alleviate intestinal inflammation effectively in the intestinal tract of weaned rats.