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Autophagy Oct 2023Neuroinflammation caused by microglial activation and consequent neurological impairment are prominent features of diabetes-associated cognitive impairment (DACI)....
Neuroinflammation caused by microglial activation and consequent neurological impairment are prominent features of diabetes-associated cognitive impairment (DACI). Microglial lipophagy, a significant fraction of autophagy contributing to lipid homeostasis and inflammation, had mostly been ignored in DACI. Microglial lipid droplets (LDs) accumulation is a characteristic of aging, however, little is known about the pathological role of microglial lipophagy and LDs in DACI. Therefore, we hypothesized that microglial lipophagy could be an Achilles's heel exploitable to develop effective strategies for DACI therapy. Here, starting with characterization of microglial accumulation of LDs in leptin receptor-deficient (db/db) mice and in high-fat diet and STZ (HFD/STZ) induced T2DM mice, as well as in high-glucose (HG)-treated mice BV2, human HMC3 and primary mice microglia, we revealed that HG-dampened lipophagy was responsible for LDs accumulation in microglia. Mechanistically, accumulated LDs colocalized with the microglial specific inflammatory amplifier TREM1 (triggering receptor expressed on myeloid cells 1), resulting in the buildup of microglial TREM1, which in turn aggravates HG-induced lipophagy damage and subsequently promoted HG-induced neuroinflammatory cascades via NLRP3 (NLR family pyrin domain containing 3) inflammasome. Moreover, pharmacological blockade of TREM1 with LP17 in db/db mice and HFD/STZ mice inhibited accumulation of LDs and TREM1, reduced hippocampal neuronal inflammatory damage, and consequently improved cognitive functions. Taken together, these findings uncover a previously unappreciated mechanism of impaired lipophagy-induced TREM1 accumulation in microglia and neuroinflammation in DACI, suggesting its translational potential as an attractive therapeutic target for delaying diabetes-associated cognitive decline. ACTB: beta actin; AIF1/IBA1: allograft inflammatory factor 1; ALB: albumin; ARG1: arginase 1; ATG3: autophagy related 3; Baf: bafilomycin A; BECN1: beclin 1, autophagy related; BW: body weight; CNS: central nervous system; Co-IP: co-immunoprecipitation; DACI: diabetes-associated cognitive impairment; DAPI: 4',6-diamidino-2-phenylindole; DGs: dentate gyrus; DLG4/PSD95: discs large MAGUK scaffold protein 4; DMEM: Dulbecco's modified Eagle's medium; DSST: digit symbol substitution test; EDTA: ethylenedinitrilotetraacetic acid; ELISA: enzyme linked immunosorbent assay; GFAP: glial fibrillary acidic protein; HFD: high-fat diet; HG: high glucose; IFNG/IFN-γ: interferon gamma; IL1B/IL-1β: interleukin 1 beta; IL4: interleukin 4; IL6: interleukin 6; IL10: interleukin 10; LDs: lipid droplets; LPS: lipopolysaccharide; MAP2: microtubule associated protein 2; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MWM: morris water maze; NFKB/NF-κB: nuclear factor of kappa light polypeptide gene enhancer in B cells; NLRP3: NLR family pyrin domain containing 3; NOS2/iNOS: nitric oxide synthase 2, inducible; NOR: novel object recognition; OA: oleic acid; PA: palmitic acid; PBS: phosphate-buffered saline; PFA: paraformaldehyde; PLIN2: perilipin 2; PLIN3: perilipin 3; PS: penicillin-streptomycin solution; RAPA: rapamycin; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; RELA/p65: RELA proto-oncogene, NF-kB subunit; ROS: reactive oxygen species; RT: room temperature; RT-qPCR: Reverse transcription quantitative real-time polymerase chain reaction; STZ: streptozotocin; SQSTM1/p62: sequestosome 1; SYK: spleen asociated tyrosine kinase; SYP: synaptophysin; T2DM: type 2 diabetes mellitus; TNF/TNF-α: tumor necrosis factor; TREM1: triggering receptor expressed on myeloid cells 1; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling.
Topics: Animals; Humans; Mice; Autophagy; Cognitive Dysfunction; Diabetes Mellitus, Type 2; Glucose; Lipid Droplets; Microglia; Neuroinflammatory Diseases; NF-kappa B; NLR Family, Pyrin Domain-Containing 3 Protein; Triggering Receptor Expressed on Myeloid Cells-1
PubMed: 37204119
DOI: 10.1080/15548627.2023.2213984 -
FEBS Letters Sep 2023Evidence from biochemistry, genetics, and electron microscopy strongly supports the idea that a ring of Synaptotagmin is central to the clamping and release of synaptic... (Review)
Review
Evidence from biochemistry, genetics, and electron microscopy strongly supports the idea that a ring of Synaptotagmin is central to the clamping and release of synaptic vesicles (SVs) for synchronous neurotransmission. Recent direct measurements in cell-free systems suggest there are 12 SNAREpins in each ready-release vesicle, consisting of six peripheral and six central SNAREpins. The six central SNAREpins are directly bound to the Synaptotagmin ring, are directly released by Ca , and they initially open the fusion pore. The six peripheral SNAREpins are indirectly bound to the ring, each linked to a central SNAREpin by a bridging molecule of Complexin. We suggest that the primary role of peripheral SNAREpins is to provide additional force to 'turbocharge' neurotransmitter release, explaining how it can occur much faster than other forms of membrane fusion. The SV protein Synaptophysin forms hexamers that bear two copies of the v-SNARE VAMP at each vertex, one likely assembling into a peripheral SNAREpin and the other into a central SNAREpin.
Topics: Biological Transport; Cell-Free System; Head; Synaptic Transmission; Synaptotagmins
PubMed: 37643878
DOI: 10.1002/1873-3468.14718 -
Annales de Pathologie Sep 2023A 75 years old patient presented with a papular easily bleeding lesion of the lower lip that had been growing for two months. He was known for alcoholic cirrhosis...
A 75 years old patient presented with a papular easily bleeding lesion of the lower lip that had been growing for two months. He was known for alcoholic cirrhosis complicated with hepatocellular carcinoma treated since one year. A working diagnostic hypothesis of benign vascular lesion was proposed. Microscopic examination showed a neoplastic dermal proliferation that had been fully excised, made of lobules segregated by thin fibrous septae. The neoplastic architecture was trabecular and delineating spaces forming pseudo-rosettes. Tumour cells were monomorphic, cuboidal or cylindric with abundant eosinophilic and granulous cytoplasm and centered by a lone nucleus that often contained a prominent nucleolus. Some spaces were filled with a brownish-greenish pigmented material. Immunohistochemical study showed that tumour cells were positive with the hepatocyte paraffin 1 antibody as well as cytokeratin 8 antibody. Chromogranin A and synaptophysin stainings were negative. Thus we concluded to a lip metastasis from the previously known hepatocellular carcinoma. Skin metastasis arise in around 3% of cases of hepatocellular carcinoma. They account for less than 1% of all cutaneous metastasis. Overall appearance of cutaneous metastasis of hepatocellular carcinoma is associated with a poor prognosis and an aggravated risk of metastasis to other locations and organs and a median overall survival of less than 5 months. Since incidence of hepatocellular carcinoma is rising pathologists might face more frequently in years to come to cutaneous metastasis whose varied clinical presentations make a diagnostic challenge.
Topics: Male; Humans; Aged; Carcinoma, Hepatocellular; Skin Neoplasms; Immunohistochemistry; Antibodies; Liver Neoplasms
PubMed: 36858940
DOI: 10.1016/j.annpat.2023.01.006 -
British Journal of Anaesthesia Sep 2023Sleep loss and its associated conditions (e.g. cognitive deficits) represent a large societal burden, but the underlying mechanisms of these cognitive deficits remain...
BACKGROUND
Sleep loss and its associated conditions (e.g. cognitive deficits) represent a large societal burden, but the underlying mechanisms of these cognitive deficits remain unknown. This study assessed the effect of dexmedetomidine (DEX) on cognitive decline induced by sleep loss.
METHODS
C57BL/6 mice were subjected to chronic sleep restriction (CSR) for 20 h (5 pm-1 pm the next day) daily for 7 days, and cognitive tests were subsequently carried out. The neuromolecular and cellular changes that occurred in the presence and absence of DEX (100 μg kg, i.v., at 1 pm and 3 pm every day) were also investigated.
RESULTS
CSR mice displayed a decline in learning and memory by 12% (P<0.05) in the Y-maze and by 18% (P<0.01) in the novel object recognition test; these changes were associated with increases in microglial activation, CD68+ microglial phagosome counts, astrocyte-derived complement C3 secretion, and microglial C3a receptor expression (all P<0.05). Synapse elimination, as indicated by a 66% decrease in synaptophysin expression (P=0.0004) and a 45% decrease in postsynaptic density protein-95 expression (P=0.0003), was associated with the occurrence of cognitive deficits. DEX activated astrocytic α adrenoceptors and inhibited astrocytic complement C3 release to attenuate synapse elimination through microglial phagocytosis. DEX restored synaptic connections and reversed cognitive deficits induced by CSR.
CONCLUSIONS
The results demonstrate that complement pathway activation associated with synapse elimination contributes to sleep loss-related cognitive deficits and that dexmedetomidine protects against sleep deprivation-induced complement activation. Dexmedetomidine holds potential for preventing cognitive deficits associated with sleep loss, which warrants further study.
Topics: Mice; Animals; Sleep Deprivation; Complement C3; Dexmedetomidine; Mice, Inbred C57BL; Complement Activation; Cognition; Hippocampus; Microglia
PubMed: 37517957
DOI: 10.1016/j.bja.2023.04.044 -
Brain, Behavior, and Immunity Oct 2023Microglia have an innate immunity memory (IIM) with divergent functions in different animal models of neurodegenerative diseases, including Alzheimer's disease (AD). AD...
Microglia have an innate immunity memory (IIM) with divergent functions in different animal models of neurodegenerative diseases, including Alzheimer's disease (AD). AD is characterized by chronic neuroinflammation, neurodegeneration, tau tangles and β-amyloid (Aβ) deposition. Systemic inflammation has been implicated in contributing to the progression of AD. Multiple reports have demonstrated unique microglial signatures in AD mouse models and patients. However, the proteomic profiles of microglia modified by IIM have not been well-documented in an AD model. Therefore, in the present study, we investigate whether lipopolysaccharide (LPS)-induced IIM in the pre-clinical stage of AD alters the microglial responses and shapes the neuropathology. We accomplished this by priming 5xFAD and wild-type (WT) mice with an LPS injection at 6 weeks (before the robust development of plaques). 140 days later, we evaluated microglial morphology, activation, the microglial barrier around Aβ, and Aβ deposition in both 5xFAD primed and unprimed mice. Priming induced decreased soma size of microglia and reduced colocalization of PSD95 and Synaptophysin in the retrosplenial cortex. Priming appeared to increase phagocytosis of Aβ, resulting in fewer Thioflavin S Aβ fibrils in the dentate gyrus. RIPA-soluble Aβ 40 and 42 were significantly reduced in Primed-5xFAD mice leading to a smaller size of MOAB2 Aβ plaques in the prefrontal cortex. We also found that Aβ-associated microglia in the Primed-5xFAD mice were less activated and fewer in number. After priming, we also observed improved memory performance in 5xFAD. To further elucidate the molecular mechanism underlying these changes, we performed quantitative proteomic analysis of microglia and bone marrow monocytes. A specific pattern in the microglial proteome was revealed in primed 5xFAD mice. These results suggest that the imprint signatures of primed microglia display a distinctive phenotype and highlight the potential for a beneficial adaption of microglia when intervention occurs in the pre-clinical stage of AD.
Topics: Mice; Animals; Alzheimer Disease; Lipopolysaccharides; Microglia; Mice, Transgenic; Proteomics; Amyloid beta-Peptides; Disease Models, Animal
PubMed: 37437821
DOI: 10.1016/j.bbi.2023.07.006 -
Theranostics 2024Spinal cord injury (SCI) results in neural tissue damage. However, the limited regenerative capacity of adult mammals' axons upon SCI leads to persistent neurological...
Exosomes derived from CD271CD56 bone marrow mesenchymal stem cell subpopoulation identified by single-cell RNA sequencing promote axon regeneration after spinal cord injury.
Spinal cord injury (SCI) results in neural tissue damage. However, the limited regenerative capacity of adult mammals' axons upon SCI leads to persistent neurological dysfunction. Thus, exploring the pathways that can enhance axon regeneration in injured spinal cord is of great significance. Through the utilization of single-cell RNA sequencing in this research, a distinct subpopulation of bone marrow mesenchymal stem cells (BMSCs) that exhibits the capacity to facilitate axon regeneration has been discovered. Subsequently, the CD271CD56 BMSCs subpopulation was isolated using flow cytometry, and the exosomes derived from this subpopulation (CD271CD56 BMSC-Exos) were extracted and incorporated into a hydrogel to create a sustained release system. The aim was to investigate the therapeutic effects of CD271CD56 BMSC-Exos and elucidate the underlying mechanisms involved in promoting axon regeneration and neural function recovery. The findings indicate that CD271CD56 BMSC-Exos share similar physical and chemical properties with conventional exosomes. Importantly, in an SCI model, in situ implantation of CD271CD56 BMSC-Exos hydrogel resulted in increased expression of NF and synaptophysin, markers associated with axon regeneration and synapse formation, respectively. This intervention also contributed to improved neural function recovery. In vitro experiments demonstrated that CD271CD56 BMSC-Exos treatment significantly enhanced axon extension distance and increased the number of branches in dorsal root ganglion axons. Moreover, further investigation into the molecular mechanisms underlying CD271CD56 BMSC-Exos-mediated axon regeneration revealed the crucial involvement of the miR-431-3p/RGMA axis. In summary, the implantation of CD271CD56 BMSC-Exos hydrogel presents a promising and effective therapeutic approach for SCI.
Topics: Adult; Animals; Humans; Axons; Exosomes; Adapalene; Nerve Regeneration; Mesenchymal Stem Cells; Spinal Cord Injuries; Hydrogels; Sequence Analysis, RNA; Mammals
PubMed: 38169566
DOI: 10.7150/thno.89008 -
Life Sciences Nov 2023Menopause is a natural process in women that can lead to post-menopausal syndrome with symptoms such as hot flushes, weight gain, anxiety, cognitive decline, and...
AIMS
Menopause is a natural process in women that can lead to post-menopausal syndrome with symptoms such as hot flushes, weight gain, anxiety, cognitive decline, and depression. Hormonal replacement therapy is commonly prescribed. However, it has serious adverse effects. Herbal medicinal products and isoflavones are used as alternatives. D-Pinitol found in Pinaceae and Fabaceae families has anti-inflammatory and antioxidant effects. However, it has not received as much attention as isoflavones. In this study, we investigated whether D-pinitol could alleviate post-menopausal symptoms using an ovariectomized (OVX) mouse model.
MAIN METHODS
Female ICR mice were divided into six groups: sham (vehicle), OVX (vehicle), OVX + D-pinitol (10, 30, 100 mg/kg, p.o.), and OVX + estradiol (0.5 mg/kg, s.c.). Treatment with vehicle, D-pinitol, and estradiol began at seven weeks post ovariectomy. We employed several behavioral tests, hot-flush test, and Western blot analysis.
KEY FINDINGS
We found that D-pinitol treatment (30, 100 mg/kg, p.o.) reversed cognitive dysfunction in OVX mice (novel object recognition and Y-maze test). Additionally, D-pinitol alleviated anxiety-like behaviors (elevated plus-maze) and reversed depressive-like behaviors (splash test, tail suspension test). It also normalized increased basal tail skin temperature in OVX mice. Moreover, D-pinitol administration reversed decreased expression of ERβ and synaptophysin and phosphorylation of ERK and PI3K-Akt-GSK-3β induced by OVX in the hippocampus and prefrontal cortex.
SIGNIFICANCE
These findings indicate that D-pinitol might be a promising candidate for treating post-menopausal symptoms by increasing ERβ and synaptophysin expression levels and activation of ERK or PI3K-Akt-GSK-3β signaling pathway, at least in part.
Topics: Humans; Mice; Female; Animals; Postmenopause; Glycogen Synthase Kinase 3 beta; Synaptophysin; Proto-Oncogene Proteins c-akt; Estrogen Receptor beta; Phosphatidylinositol 3-Kinases; Mice, Inbred ICR; Estradiol; Isoflavones; Ovariectomy
PubMed: 37802198
DOI: 10.1016/j.lfs.2023.122147 -
Journal of Veterinary Diagnostic... Nov 2023An 11-y-old hembra alpaca was admitted because of cerebellar and vestibular signs, dysphagia, and aspiration pneumonia; without clinical improvement following empirical...
An 11-y-old hembra alpaca was admitted because of cerebellar and vestibular signs, dysphagia, and aspiration pneumonia; without clinical improvement following empirical therapy, the patient was euthanized. On autopsy, a neoplasm was found incorporating the right vestibulocochlear nerve at the level of the acoustic meatus. Histologically, the mass was composed of a multiphasic primitive cell population associated with a dense fibrous stroma and enveloping a remnant ganglion and nerve bundles. Patterns included dense ribbons and cords of embryonal neuroepithelial cells admixed with loosely defined interlacing spindle cells. The embryonal cells had angular cell profiles with variable amounts of lightly basophilic cytoplasm, ovoid-to-irregular nuclei, and an open chromatin pattern with a typically inapparent nucleolus. Necrosis was not evident, and there was 1 mitotic figure per 2.37 mm. The entire mass was infiltrated by small numbers of lymphocytes and plasma cells. Immunohistochemistry (IHC) revealed strong and diffuse cytoplasmic immunolabeling for vimentin, microtubule-associated protein-2, protein gene product 9.5, and synaptophysin; ~50% immunolabeling for cytokeratin AE1/3; sporadic OLIG2 and S100 immunolabeling; and absent glial fibrillary acidic protein immunolabeling. Based on the histologic pattern and the IHC results, our diagnosis was a poorly differentiated embryonal tumor with ependymal differentiation associated with the vestibulocochlear nerve.
Topics: Animals; Camelids, New World; Neoplasms, Germ Cell and Embryonal
PubMed: 37638696
DOI: 10.1177/10406387231195611 -
Frontiers in Cellular Neuroscience 2023Microglia play an important role in the maintenance of brain and behavioral homeostasis. The protective effect of microglial replenishment was reported in neurological...
BACKGROUND
Microglia play an important role in the maintenance of brain and behavioral homeostasis. The protective effect of microglial replenishment was reported in neurological diseases, but whether microglial therapy would benefit psychiatric disorders such as schizophrenia has been unclear. As schizophrenia is a stress-vulnerable disorder and psychosocial stress promotes inflammation and microglial activation, we aim to understand how microglial replenishment works in stress-associated schizophrenia.
METHODS
We used a CSF1R-mediated pharmacological approach to study repopulated microglia (repMg) in a cohort of mice ( 10/group) undergoing chronic unpredictable stress (CUS). We further studied a cohort of first-episode schizophrenia (FES, 74) patients who had higher perceived stress scores (PSS) than healthy controls (HCs, 68).
RESULTS
Reborn microglia attenuated CUS-induced learned hopelessness and social withdrawal but not anxiety in mice. Compared to control, CUS- or repMg-induced differentially expressed genes (DEGs) in the prefrontal cortex regulated nervous system development and axonal guidance. CUS also caused microglial hyper-ramification and increased engulfment of synaptophysin and vesicular glutamate transporter-2 by microglia and astrocytes, which were recovered in CUS + repMg (all < 0.05). Moreover, FES patients had smaller hippocampal fimbria than HCs ( < 1e-7), which were negatively associated with PSS ( = -0.397, = 0.003). Blood DEGs involved in immune system development were also associated with PSS and the right fimbria more prominently in FES patients than HCs (Zr, < 0.0001). The was a partial mediator between PSS and fimbria size ( = -0.442, 95% CI: -1.326 ~ -0.087).
CONCLUSION
Microglial replenishment may potentially benefit psychiatric disorders such as schizophrenia.
PubMed: 37771931
DOI: 10.3389/fncel.2023.1254923 -
Nature Jun 2024Synaptic vesicles are organelles with a precisely defined protein and lipid composition, yet the molecular mechanisms for the biogenesis of synaptic vesicles are mainly...
Synaptic vesicles are organelles with a precisely defined protein and lipid composition, yet the molecular mechanisms for the biogenesis of synaptic vesicles are mainly unknown. Here, we discovered a well-defined interface between the synaptic vesicle V-ATPase and synaptophysin by in situ cryo-electron tomography and single particle cryo-electron microscopy of functional synaptic vesicles isolated from mouse brains. The synaptic vesicle V-ATPase is an ATP-dependent proton pump that establishes the protein gradient across the synaptic vesicle, which in turn drives the uptake of neurotransmitters. Synaptophysin and its paralogs synaptoporin and synaptogyrin belong to a family of abundant synaptic vesicle proteins whose function is still unclear. We performed structural and functional studies of synaptophysin knockout mice, confirming the identity of synaptophysin as an interaction partner with the V-ATPase. Although there is little change in the conformation of the V-ATPase upon interaction with synaptophysin, the presence of synaptophysin in synaptic vesicles profoundly affects the copy number of V-ATPases. This effect on the topography of synaptic vesicles suggests that synaptophysin assists in their biogenesis. In support of this model, we observed that synaptophysin knockout mice exhibit severe seizure susceptibility, suggesting an imbalance of neurotransmitter release as a physiological consequence of the absence of synaptophysin.
PubMed: 38838737
DOI: 10.1038/s41586-024-07610-x