Pleiotrophin ameliorates age-induced adult hippocampal neurogenesis decline and cognitive dysfunction

The roles of pleiotrophin in brain injuries: a narrative review of the literature

BACKGROUND

Pleiotrophin (PTN), a secreted multifunctional growth factor, is highly expressed in the developing brain. Recently, many studies have indicated that PTN participates in the development of brain and plays a neuroprotection after brain injury, especially promoting neuronal survival and neurite outgrowth, stimulating oligodendrocyte maturation and myelination, modulating neuroinflammation, and so on.

OBJECTIVE

However, no reviews comprehensively summarize the roles of PTN in brain injuries. Considering this, this review focuses on the roles and related regulatory pathways of PTN in brain injuries, what is known to date.

METHODS

PubMed and Embase databases have been searched, and related studies are compiled and summarized.

RESULTS

Our review has found PTN participates in the repairment of brain injuries, including hypoxic-ischemic brain injury, preterm white matter injury, traumatic brain injury, and neurodegenerative diseases, mainly based on animal data and small sample size studies. Besides, PTN interacts with receptors, such as, Z-type protein tyrosine phosphatase receptor and syndecan-3, regulating related pathways in these events.

CONCLUSION

It suggests PTN as a promising candidate for the treatment of brain injuries clinically. However, the evidence is early in its development. Further multi-center and large-sample studies are warranted to support our findings and determine the clinical value of PTN for treating brain injuries.

Electroacupuncture's Impact on the Hippocampal RAGE/LRP1 Receptor System in SAMP8 Mice

Age-related cognitive impairment (ARCI) is linked to β-amyloid (Aβ) accumulation and disrupted blood-brain barrier (BBB) transport via receptors for advanced glycation end products (RAGE) and low-density lipoprotein receptor-related protein 1 (LRP1). This study examines electroacupuncture (EA) effects on cognition, hippocampal pathology, neurotransmitters, and the RAGE/LRP1 system in senescence-accelerated mouse prone 8 (SAMP8) mice. EA at Zusanli (ST36) and Baihui (GV20) improved cognitive performance, reduced hippocampal neuronal degeneration, elevated cerebrospinal fluid dopamine, norepinephrine, serotonin, and 5-hydroxyindoleacetic acid, and decreased Aβ42 levels. EA downregulated hippocampal RAGE, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1), upregulated LRP1 and apolipoprotein E (ApoE), promoting Aβ clearance. NF-κB expression remained unchanged, suggesting alternative anti-inflammatory pathways. Thus, EA offers a promising non-pharmacological treatment for ARCI.

Crosstalk Signaling Between the Epithelial and Non-Epithelial Compartments of the Mouse Inner Ear

PURPOSE

The otolith organs of the inner ear consist of the utricle and saccule that detect linear acceleration. These organs rely on mechanosensitive hair cells for transduction of signals to the central nervous system. In the murine utricle, about half of the hair cells are born during the first postnatal week. Here, we wanted to explore the role and interaction of the non-epithelial mesenchymal cells with the sensory epithelium and provide a resource for the auditory neurosciences community.

METHODS

We utilized full-length Smart-seq2 single-cell RNA sequencing at postnatal days 4 and 6 along with a host of computational methods to infer interactions between the epithelial and non-epithelial compartments of the mouse utricle. We validated these findings using a combination of immunohistochemistry and quantitative multiplex in situ hybridization.

RESULTS

We report diverse cell-cell crosstalk among the 12 annotated cell populations (n = 955 cells) in the developing neonatal mouse utricle, including epithelial and non-epithelial cellular signaling. The mesenchymal cells are the dominant signal senders during the postnatal period. Epithelial to mesenchymal signaling, as well as mesenchymal to epithelial signaling, are quantitatively shown through the TGFβ and pleiotrophin pathways.

CONCLUSION

This study highlights the dynamic process of postnatal vestibular organ development that relies not only on epithelial cells, but also on crosstalk between spatial compartments and among different cell groups. We further provide a data-rich resource for the inner ear community.

Astrocytic pleiotrophin deficiency in the prefrontal cortex contributes to stress-induced depressive-like responses in male mice

Astrocytes are closely linked to depression, and the prefrontal cortex (PFC) is an important brain region involved in major depressive disorder (MDD). However, the underlying mechanism by which astrocytes within PFC contribute to MDD remains unclear. Using single-nucleus RNA sequencing analyses, we show a significant reduction in astrocytes and attenuated pleiotrophin-protein tyrosine phosphatase receptor type Z1 (PTN-PTPRZ1) signaling in astrocyte-to-excitatory neuron communication in the PFC of male MDD patients. We find reduced astrocytes and PTN in the dorsomedial PFC of male mice with depression induced by chronic restraint and social defeat stress. Knockdown of astrocytic PTN induces depression-related responses, which is reversed by exogenous PTN supplementation or overexpression of astrocytic PTN. The antidepressant effects exerted by astrocytic PTN require interaction with PTPRZ1 in excitatory neurons, and PTN-PTPRZ1 activates the AKT signaling pathway to regulate depression-related responses. Our findings indicate the PTN-PTPRZ1-AKT pathway may be a potential therapeutic target for MDD.

Targeting the PTN/PTPRZ1-ROS Pathway to Promote Bone Regeneration

Background: Osteoporosis is a global health problem that significantly decreases patients' quality of life and causes tremendous medical burdens. Therefore, exploring effective targeting strategies for osteoporosis treatment is crucial. Previous studies have indicated that pleiotrophin (PTN) was a secretory factor involved in several biological processes, such as angiogenesis, neural development, and abnormal osteogenic functions in osteoporosis. However, the roles of PTN in osteogenics and the mechanisms remain unclear. Methods: In this study, we explored the effects and mechanisms of PTN in regulating osteogenic functions using real-time quantitative PCR, immunofluorescence, ALP detection, a TUNEL assay, RNA sequencing, and phosphorylation quantitative proteomics. Fracture-healing experiments in osteoporosis rats were also conducted to evaluate the osteogenic functions of PTN in vivo. Results: We found that PTN significantly inhibited apoptosis and promoted the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs). Further experiments showed that PTN regulated the biological functions of rBMSCs by promoting antioxidant functions and reducing cellular reactive oxygen species (ROS), thereby protecting rBMSCs from accumulated ROS. Additionally, we found that PTN binds to the PTPRZ1 receptor, inducing intracellular PLCG1 phosphorylation and NCOA3 nuclear translocation, which regulate the downstream antioxidant functions of rBMSCs. Additionally, we verified that PTN effectively promoted fracture healing in osteoporotic animals. Conclusions: This study elucidates the mechanisms by which PTN promotes osteogenesis and verifies this effect in vivo, offering an effective target for osteoporosis treatment.

PTN activity in quiescent neural stem cells mediates Shank3 overexpression-induced manic behavior

Mania is a complex psychiatric disease characterized by hyperactivity, elevated mood and reduced anxiety. Despite extensive studies on the mechanism of the manic episodes, the molecular targets that control manic pathogenesis remain largely unclear. Here, through single-cell RNA sequencing (scRNA-seq) analysis, we show aberrant adult neurogenesis due to increased numbers of quiescent neural stem cells (qNSC) in a manic mouse model with Shank3 overexpression. Particularly, we found that the excessive Pleiotrophin (PTN), released by dysregulated qNSCs, is a key factor contributing to the manic-like phenotypes in Shank3-overexpressing mouse models. Pharmacological and molecular inhibition of PTN in qNSCs rescued aberrant neurogenesis and effectively alleviated the manic-like social deficits observed in Shank3-overexpressing mice. Taken together, our findings present an approach for modulating PTN activity in qNSCs, proposing it as a promising therapeutic target for manic development.

Neural stem cell heterogeneity in adult hippocampus

Adult neurogenesis is a unique cellular process of the ongoing generation of new neurons throughout life, which primarily occurs in the subgranular zone (SGZ) of the dentate gyrus (DG) and the subventricular zone (SVZ) of the lateral ventricle. In the adult DG, newly generated granule cells from neural stem cells (NSCs) integrate into existing neural circuits, significantly contributing to cognitive functions, particularly learning and memory. Recently, more and more studies have shown that rather than being a homogeneous population of identical cells, adult NSCs are composed of multiple subpopulations that differ in their morphology and function. In this study, we provide an overview of the origin, regional characteristics, prototypical morphology, and molecular factors that contribute to NSC heterogeneity. In particular, we discuss the molecular mechanisms underlying the balance between activation and quiescence of NSCs. In summary, this review highlights that deciphering NSC heterogeneity in the adult brain is a challenging but critical step in advancing our understanding of tissue-specific stem cells and the process of neurogenesis in the adult brain.

Microglial cGAS Deletion Preserves Intercellular Communication and Alleviates Amyloid-β-Induced Pathogenesis of Alzheimer's Disease

Innate immune activation plays a crucial role in the pathogenesis of Alzheimer's disease (AD) and related dementias (ADRD). The cytosolic DNA sensing pathway, involving cGAMP synthase (cGAS) and Stimulator of Interferon Genes (STING), has emerged as a key mediator of neurodegenerative diseases. However, the precise mechanisms through which cGAS activation influences AD progression remain poorly understood. In this study, we observed significant up-regulation of cGAS-STING signaling pathway in AD. Notably, this increase is primarily attributed to microglia, rather than non-microglial cell types. Using an inducible, microglia-specific cGAS knockout mouse model in the 5xFAD background, we demonstrated that deleting microglial cGAS at the onset of amyloid-β (Aβ) pathology profoundly restricts plaque accumulation and protects mice from Aβ-induced cognitive impairment. Mechanistically, our study revealed cGAS promotes plaque-associated microglia accumulation and is essential for inflammasome activation. Moreover, we showed that restricting cGAS-mediated innate immunity is crucial for preserving inter-cellular communication in the brain and induces pleiotrophin, a neuroprotective factor. These findings offer novel insights into the specific roles of the innate immune system in AD employing a cell-type-specific approach. The conclusions provide a foundation for targeted interventions to modulate the microglial cGAS-STING signaling pathway, offering promising therapeutic strategy for AD treatment.

Pleiotrophin Prevents H2O2-Induced Senescence of Dental Pulp Stem Cells

BACKGROUND

Dental pulp stem cells (DPSCs) are widely used in research on dental tissue regeneration and systemic disease treatment. However, the oxidative microenvironment often causes cellular senescence, leading to decreased function. Our previous study demonstrated that pleiotrophin (PTN), a secreted extracellular matrix-associated protein, could rescue the proliferative capacity and osteogenic differentiation of replicative senescent DPSCs.

OBJECTIVE

This study aimed to explore the influence and mechanism of PTN on dental pulp stem cells under H2O2-induced oxidative microenvironment.

MATERIALS AND METHODS

DPSCs isolated from human third molars were treated with 100 μm H2O2 for 4 h, mimicking the oxidative microenvironment. To investigate the influence of PTN on DPSC under H2O2-induced oxidative microenvironment, 50 pg/mL PTN was added in the culture medium for 48 h. RT-qPCR, western blotting, SA-β-gal staining, intracellular ROS production and immunofluorescence staining assays were used to analyse the cellular senescence, osteogenic differentiation capacity, oxidative stress conditions and possible mechanism.

RESULTS

H2O2 treatment increased the ratio of SA-β-gal-positive DPSCs and upregulated the senescence-related gene expression, including P53, P21 and P16. PTN pretreatment downregulated the ratio of SA-β-gal-positive DPSCs and the expression of these genes. Besides, PTN pretreatment partially reversed the H2O2-induced decreased osteogenic differentiation potential of DPSCs, total antioxidant capacity and Nrf2 and HO-1 mRNA expression in DPSCs. Western blotting and immunofluorescent staining results indicated that PTN pretreatment enhanced the Nrf2 nuclear translocation under oxidative stress conditions and observable higher fluorescence signals in the nucleus denoted PTN and Nrf2 colocalisation. Western blotting results showed that PTN reversed the decreased expression of p-AKT in the H2O2-induced oxidative environment. However, the PI3K inhibitor LY294002 blocked the upregulated levels of total Nrf2. Immunofluorescence staining displayed that LY294002 also inhibited the nuclear translocation of Nrf2 which was enhanced under PTN pretreatment.

CONCLUSIONS

This study demonstrated that PTN could prevent senescent damage induced by H2O2 on DPSCs, mainly by combining with Nrf2 and enhancing its nuclear translocation.

Single-cell RNA sequencing provides new insights into the interaction between astrocytes and neurons after spinal cord injury in mice

Background

Spinal cord injury (SCI) is a devastating neurological disease in which astrocytes play a central role. Understanding the relationship between different subtypes of astrocytes and neuron subtypes during the progression of SCI is critical to understanding the disease.

Methods and results

In this study, single-cell RNA sequencing (scRNA-seq) was used to analyze the transcriptome data of acute, subacute and intermediate stages of SCI in mice as well as normal tissues. Different subtypes of astrocytes and neuronal cells were identified and their dynamic changes and functionalities during the development of SCI. An intriguing discovery was the identification of a specific subtype of astrocytes characterized by unique expression of Gap43, Vim, Aldoc, and Mt1. This subtype of cells shows similarities in gene expression with neurons and potentially transitioned into neurons during the course of SCI. Furthermore, we have uncovered the important role of the glycolytic pathway in this cellular transformation process. Furthermore, through cellular interaction analysis, we validated pathways (mdk-ptprz1,ptn-ptprz1,ptn-sdc3) associated with the potential conversion of these specific cell subsets into neurons. Finally, these cells were observed by fluorescence microscopy and critical gene expressions were validated by Western blot.

Conclusions

The results of this study not only deepen our understanding of the mechanisms underlying SCI, but also provide new insights and opportunities for the development of novel therapeutic strategies and interventions.

Spatiotemporal analysis of gene expression in the human dentate gyrus reveals age-associated changes in cellular maturation and neuroinflammation

The dentate gyrus of the hippocampus is important for many cognitive functions, including learning, memory, and mood. Here, we present transcriptome-wide spatial gene expression maps of the human dentate gyrus and investigate age-associated changes across the lifespan. Genes associated with neurogenesis and the extracellular matrix are enriched in infants and decline throughout development and maturation. Following infancy, inhibitory neuron markers increase, and cellular proliferation markers decrease. We also identify spatio-molecular signatures that support existing evidence for protracted maturation of granule cells during adulthood and age-associated increases in neuroinflammation-related gene expression. Our findings support the notion that the hippocampal neurogenic niche undergoes major changes following infancy and identify molecular regulators of brain aging in glial- and neuropil-enriched tissue.

The neuroscience in breast cancer: Current insights and clinical opportunities

The involvement of nerves in the development of breast cancer has emerged as a significant factor. Interaction between the nervous system and breast cancer can influence tumor initiation, growth, invasion, metastasis, reverse resistance to drugs, promote inflammation in tumors, and impair the immune system's ability to combat cancer. This review examined the intricate relationship linking the nervous system with breast cancer, emphasizing both central and peripheral aspects of the nervous system. Moreover, we reviewed neural cell factors and their impact on breast cancer progression, alongside the interactions between nerves and immunology, microbiota in breast cancer. Furthermore, the study discussed the potential of nerves as biomarkers for diagnosing and prognosticating breast cancer, and evaluated prospects for improving chemotherapy and immunotherapy therapeutic outcomes in breast cancer treatment. We hope to provide a deeper understanding of the neurobiological underpinnings of breast cancer and pave the way for the discovery of innovative therapeutic targets and prognostic markers.

Astrocyte-derived PTN alleviates deficits in hippocampal neurogenesis and cognition in models of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease that results in motor, sensory, cognitive, and affective deficits. Hippocampal demyelination, a common occurrence in MS, is linked to impaired cognitive function and mood. Despite this, the precise mechanisms underlying cognitive impairments in MS remain elusive. Pleiotrophin (PTN), secreted by neural stem cells and astrocytes, plays a crucial role in regulating cognition. This study investigates the role of astrocyte-derived PTN. We found that genetic deletion of astrocyte-derived PTN hinders hippocampal neurogenesis. Additionally, conditional ablation of PTN in astrocytes exacerbates neurogenic deficits in the demyelinated hippocampus. Importantly, overexpression of PTN in astrocytes reverses neurogenic and cognitive impairments caused by demyelination, underscoring PTN's protective role in MS. PTN cooperates with protein tyrosine phosphatase receptor type Z1 (PTPRZ1) or anaplastic lymphoma kinase (ALK) receptors to activate the AKT signaling pathway, thereby enhancing hippocampal neurogenesis and cognition in demyelinated mice. These findings illuminate novel effects of astrocyte-derived PTN on hippocampal neurogenesis and cognition.

Spatiotemporal modeling of molecular holograms

Quantifying spatiotemporal dynamics during embryogenesis is crucial for understanding congenital diseases. We developed Spateo (https://github.com/aristoteleo/spateo-release), a 3D spatiotemporal modeling framework, and applied it to a 3D mouse embryogenesis atlas at E9.5 and E11.5, capturing eight million cells. Spateo enables scalable, partial, non-rigid alignment, multi-slice refinement, and mesh correction to create molecular holograms of whole embryos. It introduces digitization methods to uncover multi-level biology from subcellular to whole organ, identifying expression gradients along orthogonal axes of emergent 3D structures, e.g., secondary organizers such as midbrain-hindbrain boundary (MHB). Spateo further jointly models intercellular and intracellular interaction to dissect signaling landscapes in 3D structures, including the zona limitans intrathalamica (ZLI). Lastly, Spateo introduces "morphometric vector fields" of cell migration and integrates spatial differential geometry to unveil molecular programs underlying asymmetrical murine heart organogenesis and others, bridging macroscopic changes with molecular dynamics. Thus, Spateo enables the study of organ ecology at a molecular level in 3D space over time.

Unveiling the NEFH+ malignant cell subtype: Insights from single-cell RNA sequencing in prostate cancer progression and tumor microenvironment interactions

Background

Prostate cancer (PCa) is a multifactorial and heterogeneous disease, ranking among the most prevalent malignancies in men. In 2020, there were 1,414,259 new cases of PCa worldwide, accounting for 7.3% of all malignant tumors. The incidence rate of PCa ranks third, following breast cancer and lung cancer. Patients diagnosed with high-grade PCa frequently present with existing or developing metastases, complicating their treatment and resulting in poorer prognoses, particularly for those with bone metastases. Utilizing single-cell RNA sequencing (scRNA-seq), we identified specific malignant cell subtypes that are closely linked to high-grade PCa. By investigating the mechanisms that govern interactions within the tumor microenvironment (TME), we aim to offer new theoretical insights that can enhance the prevention, diagnosis, and treatment of PCa, ultimately striving to improve patient outcomes and quality of life.

Methods

Data on scRNA-seq was obtained from the GEO database. The gene ontology and gene set enrichment analysis were employed to analyze differential expression genes. Using inferCNV analysis to identify malignant epithelial cells. We subsequently employed Monocle, Cytotrace, and Slingshot packages to infer subtype differentiation trajectories. The cellular communication between malignant cell subtypes and other cells was predicted using the CellChat package. Furthermore, we employed pySCENIC to analyze and identify the regulatory networks of transcription factors (TFs) in malignant cell subtypes. The MDA PCa 2b and VCap cell lines were employed to validate the analysis results through cellular functional experiments. In addition, a risk scoring model was developed to assess the variation in clinical characteristics, prognosis, immune infiltration, immune checkpoint, and drug sensitivity.

Results

A malignant cell subtype in PCa with high expression of NEFH was identified through scRNA-seq analysis. This subtype was situated at the differentiation terminal, exhibited a higher level of malignancy, and exhibited characteristics that were more prone to advanced tumor lesions. In addition, our research underscored the intricate interactions that exist within the TME, particularly the interaction between PTN secreted by this subtype and fibroblasts via the NCL receptor. This interaction may be closely associated with cancer-associated fibroblasts and tumor progression. Subsequently, we determined that the NEFH+ malignant cell subtype was significantly correlated with the TF IRX4. This TF is linked to a worse prognosis in PCa and may affect disease progression by regulating gene transcription. Our conclusions were additionally verified through cellular experiments. Furthermore, the prognostic model we developed demonstrated satisfactory predictive performance, with gene sets from the high NmRS group facilitating tumor progression and deterioration. The analysis of immune infiltration was instrumental in the development of clinical intervention strategies and patient prognosis.

Conclusion

By examining the cellular heterogeneity of a unique NEFH+ malignant cell subtype within the PCa microenvironment, we were able to disclose their reciprocal interaction with disease progression. This offers a novel viewpoint on the diagnosis and treatment of PCa.

Pleiotrophin modulates acute and long-term LPS-induced neuroinflammatory responses and hippocampal neurogenesis

The hippocampus is one of the most vulnerable regions affected in disorders characterized by overt neuroinflammation such as neurodegenerative diseases. Pleiotrophin (PTN) is a neurotrophic factor that modulates acute neuroinflammation in different contexts. PTN is found highly upregulated in the brain in different chronic disorders characterized by neuroinflammation, suggesting an important role in the modulation of sustained neuroinflammation. To test this hypothesis, we studied the acute and long-term effects of a single lipopolysaccharide (LPS; 5 mg/kg) administration in Ptn+/+ and Ptn-/- mice, and in mice with Ptn-overexpression (Ptn-Tg). Endogenous PTN levels proportionally modulate LPS-induced increase in TNF-α plasma levels one hour after treatment. In the dentate gyrus (DG) of the hippocampus, a lower percentage of DCX+ cells were detected in saline-treated Ptn-/- mice compared to Ptn+/+ mice, suggesting a crucial role of PTN in the maintenance of hippocampal neuronal progenitors. The data show that PTN overexpression tends to potentiate acute microglial responses in the DG 16 hours after LPS treatment. Remarkably, a significant increase in the number of neuronal progenitors together with astrogliosis was detected 10 months after a single injection of LPS treatment in wild type mice. However, these LPS-induced long-term effects were prevented in Ptn-/- and Ptn-Tg mice, suggesting that PTN modulates LPS-induced long-term neurogenesis changes and astrocytic response in the hippocampus. The data presented here suggest that endogenous PTN levels are crucial in the regulation of acute LPS-induced systemic and hippocampal microglial responses in young mice. Furthermore, our findings provide evidence of the key role of PTN in the regulation of long-term LPS effects on astrocytic response and neurogenesis in the hippocampus.

Pleiotrophin Overexpression Reduces Adolescent Ethanol Consumption and Modulates Ethanol-Induced Glial Responses and Changes in the Perineuronal Nets in the Mouse Hippocampus

AIMS

To investigate whether pleiotrophin (PTN) overexpression influences ethanol consumption during adolescence and its effects on glial responses, neurogenesis, and perineuronal nets (PNNs) in the mouse hippocampus.

METHODS

Male and female adolescent transgenic mice with elevated PTN levels (Ptn-Tg) and controls underwent an intermittent access to ethanol (IAE) 2-bottle choice protocol. Ethanol consumption, PTN levels, neurogenesis, and glial responses were measured in the hippocampus. Immunohistochemistry was used to assess changes in new neurons, microglial and astrocyte populations, and PNNs.

RESULTS

Ptn-Tg mice consumed significantly less ethanol compared to controls, irrespective of sex. Chronic alcohol exposure reduced PTN levels in the hippocampus. PTN overexpression decreased the number of new neurons in the dentate gyrus (DG) and prevented ethanol-induced microglial activation. Ptn-Tg mice had significantly more astrocytes and fewer PNNs, with a higher percentage of parvalbumin (PV) positive cells surrounded by PNNs under basal conditions. However, ethanol drastically reduced the number of PV+ cells in the DG of Ptn-Tg mice, despite the presence of PNNs.

CONCLUSION

PTN overexpression reduces adolescent ethanol consumption and influences ethanol-induced effects on hippocampal neurogenesis, glial responses, and PNN remodeling. These findings underscore the importance of PTN in modulating alcohol-induced neurotoxicity.

Phloretin alleviates sleep deprivation-induced cognitive impairment by reducing inflammation through PPARγ/NF-κB signaling pathway

Sleep loss leads to significant pathophysiological consequences, including cognitive impairment. The neuroinflammation are pivotal factors in the pathogenesis of cognitive impairment induced by sleep loss. The phloretin (PHL), derived from peel of juicy fruits, has demonstrated potent anti-inflammatory properties. However, the precise influence of PHL on the cognitive impairment triggered by sleep loss and its underlying mechanism remain uncertain. In the present study, mice were subjected to sleep deprivation (SD) paradigm. Cognitive impairment induced by SD were significantly relieved by administration of PHL in a dose-dependent manner. Furthermore, PHL not only mitigated the synaptic losses but also enhanced dendritic spine density and neuronal activity within mice hippocampus following exposure to SD. Moreover, PHL treatment decreased the microglial numbers and altered microglial morphology in the hippocampus to restore the M1/M2 balances; these effects were accompanied by regulation of pro-/anti-inflammatory cytokine production and secretion in SD-exposed mice. Additionally, in vivo and in vitro studies showed PHL might attenuate the inflammation through the PPARγ/NF-κB pathway. Our findings suggest that PHL exerts inhibitory effects on microglia-mediated neuroinflammation, thereby providing protection against cognitive impairment induced by SD through a PPAR-γ dependent mechanism. The results indicate PHL is expected to provide a valuable candidate for new drug development for SD-induced cognitive impairment in the future.

Proteomic Markers of Aging and Longevity: A Systematic Review

This article provides a systematic review of research conducted on the proteomic composition of blood as part of a complex biological age estimation. We performed a comprehensive analysis of 17 publicly available datasets and compiled an integral list of proteins. These proteins were sorted based on their detection probability using mass spectrometry in human plasma. We propose this list as a basis for creating a panel of peptides and quantifying the content of selected proteins in the format of a proteomic aging clock. The selected proteins are especially notable for their roles in inflammatory processes and lipid metabolism. Our findings suggest, for the first time, that proteins associated with systemic disorders, including those approved by the FDA for clinical use, could serve as potential markers of aging.

Dynamics of Neurogenic Signals as Biological Switchers of Brain Plasticity

The discovery of adult neurogenesis in the middle of the past century is considered one of the most important breakthroughs in neuroscience. Despite its controversial nature, this discovery shaped our concept of neural plasticity, revolutionizing the way we look at our brains. In fact, after the discovery of adult neurogenesis, we started to consider the brain as something even more dynamic and highly adaptable. In neurogenic niches, adult neurogenesis is supported by neural stem cells (NSCs). These cells possess a unique set of characteristics such as being quiescent for long periods while actively sensing and reacting to their surroundings to influence a multitude of processes, including the generation of new neurons and glial cells. Therefore, NSCs can be viewed as sentinels to our brain's homeostasis, being able to replace damaged cells and simultaneously secrete numerous factors that restore regular brain function. In addition, it is becoming increasingly evident that NSCs play a central role in memory formation and consolidation. In this review, we will dissect how NSCs influence their surroundings through paracrine and autocrine types of action. We will also depict the mechanism of action of each factor. Finally, we will describe how NSCs integrate different and often opposing signals to guide their fate.

Spatiotemporal analysis of gene expression in the human dentate gyrus reveals age-associated changes in cellular maturation and neuroinflammation

The dentate gyrus of the hippocampus is important for many cognitive functions, including learning, memory, and mood. Here, we investigated age-associated changes in transcriptome-wide spatial gene expression in the human dentate gyrus across the lifespan. Genes associated with neurogenesis and the extracellular matrix were enriched in infants, while gene markers of inhibitory neurons and cell proliferation showed increases and decreases in post-infancy, respectively. While we did not find evidence for neural proliferation post-infancy, we did identify molecular signatures supporting protracted maturation of granule cells. We also identified a wide-spread hippocampal aging signature and an age-associated increase in genes related to neuroinflammation. Our findings suggest major changes to the putative neurogenic niche after infancy and identify molecular foci of brain aging in glial and neuropil enriched tissue.

Protocol for lentivirus-mediated delivery of genes to study neurogenesis and cognitive function in adult rodents

Adult neurogenesis leads to the generation of functional neurons from neural stem cells, whereas impairment of adult hippocampal neurogenesis contributes to the pathophysiology of cognitive symptoms in neurodegenerative and neuropsychiatric diseases. Here, we present a protocol for a direct hippocampal injection of lentivirus-delivered gene in adult rodents to study the specific molecular mechanism underlying adult neurogenesis, including lentivirus packaging and stereotaxic injection, EdU and BrdU injections, tissue immunostaining and imaging analysis, and cognitive testing. For complete details on the use and execution of this protocol, please refer to Li et al. (2023).1.