The acute-phase protein PTX3 is an essential mediator of glial scar formation and resolution of brain edema after ischemic injury

Differential blood-based biomarkers of subcortical and deep brain small vessel disease

Background

Cerebral small vessel disease is the most common cause of lacunar strokes (LS). Understanding LS pathogenesis is vital for predicting disease severity, prognosis, and developing therapies.

Objectives

To research molecular profiles that differentiate LS in deep brain structures from those in subcortical white matter.

Design

Prospective case-control study involving 120 patients with imaging-confirmed LS and a 120 control group.

Methods

We examined the relationship between Alzheimer's disease biomarkers [amyloid beta (Aβ1-40, Aβ1-42)], serum inflammatory marker (interleukin-6, IL-6), and endothelial dysfunction markers [soluble tumor necrosis factor-like weak inducer of apoptosis, and pentraxin-3 (sTWEAK, PTX3)] with respect to LS occurring in deep brain structures and subcortical white matter. In addition, we investigated links between LS, leukoaraiosis presence (white matter hyperintensities, WMHs), and functional outcomes at 3 months. Poor outcome was defined as a modified Rankin scale >2 at 3 months.

Results

Significant differences were observed in levels of IL-6, PTX3, and sTWEAK between patients with deep lacunar infarcts and those with recent small subcortical infarcts (20.8 versus 15.6 pg/mL, p < 0.001; 7221.3 versus 4624.4 pg/mL, p < 0.0001; 2528.5 versus 1660.5 pg/mL, p = 0.001). Patients with poor outcomes at 3 months displayed notably higher concentrations of these biomarkers compared to those with good outcomes. By contrast, Aβ1-40 and Aβ1-42 were significantly lower in patients with deep LS (p < 0.0001). Aβ1-42 levels were significantly higher in patients with LS in subcortical white matter who had poor outcomes. WMH severity only showed a significant association with deep LS and correlated with sTWEAK (p < 0.0001).

Conclusion

The pathophysiological mechanisms of lacunar infarcts in deep brain structures seem different from those in the subcortical white matter. As a result, specific therapeutic and preventive strategies should be explored.

Pentraxin 3: A Main Driver of Inflammation and Immune System Dysfunction in the Tumor Microenvironment of Glioblastoma

Brain tumors are a heterogeneous group of brain neoplasms that are highly prevalent in individuals of all ages worldwide. Within this pathological framework, the most prevalent and aggressive type of primary brain tumor is glioblastoma (GB), a subtype of glioma that falls within the IV-grade astrocytoma group. The death rate for patients with GB remains high, occurring within a few months after diagnosis, even with the gold-standard therapies now available, such as surgery, radiation, or a pharmaceutical approach with Temozolomide. For this reason, it is crucial to continue looking for cutting-edge therapeutic options to raise patients' survival chances. Pentraxin 3 (PTX3) is a multifunctional protein that has a variety of regulatory roles in inflammatory processes related to extracellular matrix (ECM). An increase in PTX3 blood levels is considered a trustworthy factor associated with the beginning of inflammation. Moreover, scientific evidence suggested that PTX3 is a sensitive and earlier inflammation-related marker compared to the short pentraxin C-reactive protein (CRP). In several tumoral subtypes, via regulating complement-dependent and macrophage-associated tumor-promoting inflammation, it has been demonstrated that PTX3 may function as a promoter of cancer metastasis, invasion, and stemness. Our review aims to deeply evaluate the function of PTX3 in the pathological context of GB, considering its pivotal biological activities and its possible role as a molecular target for future therapies.

An immunomodulatory role of Fc receptor γ chain independent of FcγR ligation by IgG in acute neuroinflammation triggered by MPTP intoxication

Aberrant microglial activation is a prominent feature of neuroinflammation, which is implicated in the pathogenesis of neurological disorders. Fc receptor common γ-chain (FcRγ), one of the two immunoreceptor tyrosine-based activation motif-bearing adaptor proteins, is abundantly expressed in microglia. It couples with different receptors, such as receptors for the Fc portion of IgG. In this study, we observed increased FcRγ expression along with increased IgG-binding during acute neuroinflammation triggered by MPTP intoxication, where adaptive immune responses should not be involved. Notably, FcRγ was expressed not only in the cell membrane but also in the cytoplasm in the activated microglia. FcRγ deficiency exacerbated microglial activation, pro-inflammatory factor upregulation, nigral dopaminergic neuronal loss and motor deficits, implicating a beneficial role of FcRγ in this model. Blockade of Fcγ receptor ligation by IgG in mice by Endoglycosidase S treatment, a bacterial endo-β-N-acetylglucosaminidase cleaving specifically the Asn297-linked glycan of IgG, or by using the mice deficient in mature B cells (muMT) with IgG production defects, did not show similar phenotypes to those observed in FcRγ-deficient mice, indicating that the beneficial effect mediated by FcRγ did not depend on FcγR ligation by IgG. Further, FcRγ knockout aggravated the expression and activation of STAT1 in microglia, suggesting FcRγ modulated neuroinflammation by dampening STAT1 signaling. Collectively, these results revealed that FcRγ-associated receptors could function as negative regulators of neuroinflammation and dopaminergic neurodegeneration.

Integrated inflammatory signaling landscape response after delivering Elovanoid free-fatty-acid precursors leading to experimental stroke neuroprotection

Despite efforts to identify modulatory neuroprotective mechanisms of damaging ischemic stroke cascade signaling, a void remains on an effective potential therapeutic. The present study defines neuroprotection by very long-chain polyunsaturated fatty acid (VLC-PUFA) Elovanoid (ELV) precursors C-32:6 and C-34:6 delivered intranasally following experimental ischemic stroke. We demonstrate that these precursors improved neurological deficit, decreased T2WI lesion volume, and increased SMI-71 positive blood vessels and NeuN positive neurons, indicating blood-brain barrier (BBB) protection and neurogenesis modulated by the free fatty acids (FFAs) C-32:6 and C-34:6. Gene expression revealed increased anti-inflammatory and pro-homeostatic genes and decreases in expression of pro-inflammatory genes in the subcortex. Additionally, the FFAs elicit a comprehensive downregulation of inflammatory microglia/monocyte-derived macrophages and astrocyte-associated genes in the subcortical region. Functional analysis reveals inhibition of immune-related pathways and production of upstream molecules related to detrimental signaling events in post-stroke acute and subacute phases.

Pentraxin 3 in the cerebrospinal fluid during central nervous system infections: A retrospective cohort study

The present study describes diagnostic and prognostic abilities of Cerebrospinal fluid (CSF) Pentraxin 3 (PTX3) in central nervous system (CNS) infections. CSF PTX3 was measured retrospectively from 174 patients admitted under suspicion of CNS infection. Medians, ROC curves and Youdens index was calculated. CSF PTX3 was significantly higher among all CNS infections and undetectable in most of the patients in the control group, and significantly higher in bacterial infections compared to viral and Lyme infections. No association was found between CSF PTX3 and Glasgow Outcome Score. PTX3 in the CSF can distinguish bacterial infection from viral and Lyme infections and non-CNS infections. Highest levels were found in bacterial meningitis. No prognostic abilities were found.

Knockdown of ATF3 suppresses the progression of ischemic stroke through inhibiting ferroptosis

Objective

Current therapies towards ischemic stroke (IS) are still not satisfied, and alternative strategies targeting ferroptosis may be another choice. The purpose of this study is to screen potential ferroptosis-related genes involving in IS.

Methods

A rat model of IS was established via middle cerebral artery occlusion. Differentially expressed genes (DEGs) were screened from the model rats through transcriptional sequencing. Among the isolated DEGs, the expression of several attractive DEGs relating with ischemic injury was confirmed by qRT-PCR. Then, ATF3 relating with both IS and ferroptosis was selected a candidate gene for functional assays. After knockdown of ATF3 in the model rats, the infarction, histopathology, apoptosis, and ferroptosis in brain tissues were evaluated.

Results

IS model was successfully established in rats, exhibiting the emergence of infarction area, histopathological injury, and enhanced cell apoptosis. Total 699 up-regulated DEGs and 461 down-regulated DEGs were screened from the model rats. qRT-PCR verified the up-regulation of Hspa1b, Tfpi2, Ptx3, and Atf3, and the down-regulation of Smyd1 and Tacr2 in the Model group compared with those in the Sham group. It is noteworthy that knockdown of ATF3 decreased the infarction area, relieved histopathological injury, weakened apoptosis, and inhibited ferroptosis in the model rats.

Conclusion

Several candidate genes in relation with IS were revealed. More importantly, knockdown of ATF3 may relieve IS through inhibiting ferroptosis.

Systematic analysis of brain and skull ischemic injury expression profiles reveals associations of the tumor immune microenvironment and cell death with ischemic stroke

Background

Previous studies have shown that stroke is a potential first sign of neoplasia, but the relationship between stroke and cancer remains unclear. As a complex brain disease, ischemic stroke involves cell death and immunity. Thus, it is necessary to investigate the association of the tumor immune microenvironment and cell death with ischemic stroke.

Methods

We established a photothrombosis-induced ischemic injury model in mouse brain and skull. Subsequently, we sequenced the whole transcriptome of the injured mouse brain and skull and analyzed the expression profiles. To investigate the association of stroke with cell death and cancer, we systematically performed gene set enrichment analysis in pan-cell death (i.e., apoptosis, cuproptosis, ferroptosis, necroptosis, and pyroptosis) and the cancer hallmark pathways. The time-dependent immune cell abundance variations after ischemic injury were estimated. Furthermore, pan-cancer genomic and prognostic analyses of the ischemic injury-related gene sets were also performed.

Results

In this study, we found that there exist temporal and spatial differences in the gene expression patterns of both the brain and skull with ischemic injury. The skull ischemic injury-induced changes in the brain transcriptome were particularly great, but could recover in a short period, while the skull transcriptome variation resulting from brain ischemic injury was long-lasting. In addition, the expression of the genes related to ischemic injury was also associated with pan-cell death and the cancer hallmark pathways. The changes in the abundance of immune cells indicate that brain ischemic injury may disrupt the immune microenvironment for a longer time, while the skull can balance the stability of the immune microenvironment better. Moreover, the brain ischemic injury-related gene sets were highly correlated with a variety of tumors, particularly glioblastoma multiforme (GBM), kidney renal clear cell carcinoma (KIRC), brain lower grade glioma (LGG), and uveal melanoma (UVM), which carry a greater mortality risk after stroke.

Conclusion

This systematic analysis not only helps in the understanding of the changes in the gene expression profiles of both the brain and skull with ischemic injury but also reveals the association of the tumor immune microenvironment and cell death with ischemic stroke.

Molecular mediators of angiogenesis and neurogenesis after ischemic stroke

The mechanisms governing neurological and functional recovery after ischemic stroke are incompletely understood. Recent advances in knowledge of intrinsic repair processes of the CNS have so far translated into minimal improvement in outcomes for stroke victims. Better understanding of the processes underlying neurological recovery after stroke is necessary for development of novel therapeutic approaches. Angiogenesis and neurogenesis have emerged as central mechanisms of post-stroke recovery and potential targets for therapeutics. Frameworks have been developed for conceptualizing cerebral angiogenesis and neurogenesis at the tissue and cellular levels. These models highlight that angiogenesis and neurogenesis are linked to each other and to functional recovery. However, knowledge of the molecular framework linking angiogenesis and neurogenesis after stroke is limited. Studies of potential therapeutics typically focus on one mediator or pathway with minimal discussion of its role within these multifaceted biochemical processes. In this article, we briefly review the current understanding of the coupled processes of angiogenesis and neurogenesis after stroke. We then identify the molecular mediators and signaling pathways found in pre-clinical studies to upregulate both processes after stroke and contextualizes them within the current framework. This report thus contributes to a more-unified understanding of the molecular mediators governing angiogenesis and neurogenesis after stroke, which we hope will help guide the development of novel therapeutic approaches for stroke survivors.

β-Galactosylceramidase Deficiency Causes Upregulation of Long Pentraxin-3 in the Central Nervous System of Krabbe Patients and Twitcher Mice

Globoid cell leukodystrophy (GLD), or Krabbe disease, is a neurodegenerative sphingolipidosis caused by genetic deficiency of lysosomal β-galactosylceramidase (GALC), characterized by neuroinflammation and demyelination of the central (CNS) and peripheral nervous system. The acute phase protein long pentraxin-3 (PTX3) is a soluble pattern recognition receptor and a regulator of innate immunity. Growing evidence points to the involvement of PTX3 in neurodegeneration. However, the expression and role of PTX3 in the neurodegenerative/neuroinflammatory processes that characterize GLD remain unexplored. Here, immunohistochemical analysis of brain samples from Krabbe patients showed that macrophages and globoid cells are intensely immunoreactive for PTX3. Accordingly, Ptx3 expression increases throughout the course of the disease in the cerebrum, cerebellum, and spinal cord of GALC-deficient twitcher (Galc^twi/twi) mice, an authentic animal model of GLD. This was paralleled by the upregulation of proinflammatory genes and M1-polarized macrophage/microglia markers and of the levels of PTX3 protein in CNS and plasma of twitcher animals. Crossing of Galc^twi/twi mice with transgenic PTX3 overexpressing animals (hPTX3 mice) demonstrated that constitutive PTX3 overexpression reduced the severity of clinical signs and the upregulation of proinflammatory genes in the spinal cord of P35 hPTX3/Galc^twi/twi mice when compared to Galc^twi/twi littermates, leading to a limited increase of their life span. However, this occurred in the absence of a significant impact on the histopathological findings and on the accumulation of the neurotoxic metabolite psychosine when evaluated at this late time point of the disease. In conclusion, our results provide the first evidence that PTX3 is produced in the CNS of GALC-deficient Krabbe patients and twitcher mice. PTX3 may exert a protective role by reducing the neuroinflammatory response that occurs in the spinal cord of GALC-deficient animals.

Proficiency of Extracellular Vesicles From hiPSC-Derived Neural Stem Cells in Modulating Proinflammatory Human Microglia: Role of Pentraxin-3 and miRNA-21-5p

Extracellular vesicles (EVs) shed by human-induced pluripotent stem cell (hiPSC)-derived neural stem cells (hNSC-EVs) have shown potent antiinflammatory properties in a mouse macrophage assay and a mouse model of acute neuroinflammation. They can also quickly permeate the entire brain after intranasal administration, making them attractive as an autologous or allogeneic off-the-shelf product for treating neurodegenerative diseases. However, their ability to modulate activated human microglia and specific proteins and miRNAs mediating antiinflammatory effects of hNSC-EVs are unknown. We investigated the proficiency of hNSC-EVs to modulate activated human microglia and probed the role of the protein pentraxin 3 (PTX3) and the miRNA miR-21-5p within hNSC-EVs in mediating the antiinflammatory effects. Mature microglia generated from hiPSCs (iMicroglia) expressed multiple microglia-specific markers. They responded to lipopolysaccharide (LPS) or interferon-gamma challenge by upregulating tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) mRNA expression and protein release. iMicroglia also exhibited proficiency to phagocytose amyloid-beta (Aβ). The addition of hNSC-EVs decreased TNF-α and IL-1β mRNA expression and the release of TNF-α and IL-1β by LPS-stimulated iMicroglia (proinflammatory human Microglia). However, the antiinflammatory activity of hNSC-EVs on LPS-stimulated microglia was considerably diminished when the PTX3 or miR-21-5p concentration was reduced in EVs. The results demonstrate that hNSC-EVs are proficient for modulating the proinflammatory human microglia into non-inflammatory phenotypes, implying their utility to treat neuroinflammation in neurodegenerative diseases. Furthermore, the role of PTX3 and miR-21-5p in the antiinflammatory activity of hNSC-EVs provides a new avenue for improving the antiinflammatory effects of hNSC-EVs through PTX3 and/or miR-21-5p overexpression.

Pentraxin-3 in the Spinal Dorsal Horn Upregulates Nectin-1 Expression in Neuropathic Pain after Spinal Nerve Damage in Male Mice

Purpose: Neuropathic pain often originates from nerve injury or diseases of the somatosensory nervous system. However, its specific pathogenesis remains unclear. The requirement for excitatory synaptic plasticity in pain-related syndromes has been demonstrated. A recent study reported that pentraxin-3 is important in glutamatergic synaptic formation and function. Meanwhile, nectin-1 mediates synaptogenesis in neurological disorders. The present study aimed to evaluate whether pentraxin-3 and nectin-1 modulate spinal nerve damage-related neuropathic pain in male mice. Methods: L₄ spinal nerve ligation (SNL) in male mice was performed to induce experimental neuropathic pain. Mechanical allodynia and heat hyperalgesia following SNL were based on paw withdrawal (PW) threshold and PW latency, respectively. Spinal pentraxin-3 levels and nectin-1 expression following SNL were examined. Pentraxin-3 and nectin-1 knockdown models were established by the shRNA method. These models were used with a recombinant pentraxin-3 cell model to investigate the underlying mechanisms of SNL. Results: The SNL operation generated persistent decreases in mechanical PW threshold and thermal PW latency, with subsequent long-lasting elevations in spinal pentraxin-3 and nectin-1 expression levels. Pentraxin-3 knockdown reduced SNL-associated neuropathic pain behaviors as well as nectin-1 amounts in the spinal dorsal horn. Nectin-1 deficiency impaired mechanical allodynia and thermal hyperalgesia following spinal nerve injury. The application of recombinant pentraxin-3 in the spinal cord triggered an acute nociception phenotype and induced spinal overexpression of nectin-1. The intrathecal knockdown of nectin-1 prevented exogenous pentraxin-3-evoked pain hypersensitivity. Conclusions: The findings suggest spinal pentraxin-3 is required for SNL-triggered neuropathic pain via nectin-1 upregulation in male mice.

Inflammation and endothelial dysfunction in pediatric migraine patients

BACKGROUND

Inflammation and endothelial dysfunction are the suggested underlying mechanisms in migraine. Pentraxins, C-reactive protein, erythrocyte sedimentation rate, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio are good indicators of inflammation. Alterations in insulin levels and insulin sensitivity may trigger endothelial dysfunction. This study evaluates the association between migraine and serum biomarkers of inflammation and endothelial dysfunction in children.

METHODS

Children with migraine and healthy subjects were recruited. Serum samples were obtained in an attack-free period. We collected data on serum levels of complete blood cell count, C-reactive protein, erythrocyte sedimentation rate, pentraxin-3, and data from biochemical investigations. We compared these with clinical data such as age, sex, disease duration, attack frequency, attack duration, analgesic use, family history, and Pediatric Migraine Disability Assessment Questionnaire scores.

RESULTS

We assessed samples from 32 children (11 boys, 21 girls) with migraine and 19 healthy controls (8 boys, 11 girls). We found significantly higher pentraxin-3, insulin, and insulin resistance in patients with migraine (P = 0.001, P = 0.032, and P = 0.008, respectively). A positive directional correlation is found between pentraxin-3 and Pediatric Migraine Disability Assessment Questionnaire scores. The best cut-off values for pentraxin-3 is determined between 12.75 pg/mL to 15 pg/mL in migraineurs.

CONCLUSIONS

In conclusion increased pentraxin-3 levels support the suggestions that inflammation plays a role in pediatric migraine. The vascular endothelial dysfunction is observed by a rise in insulin and insulin resistance levels. Our findings support the idea that ongoing inflammation and vascular endothelial dysfunction between attacks may play a role in migraine pathogenesis in children.

Interactions between glial cells and the blood-brain barrier and their role in Alzheimer's disease

Alzheimer's disease (AD), which is an irreversible neurodegenerative disorder characterized by senile plaques and neurofibrillary tangles, is the most common form of dementia worldwide. However, currently, there are no satisfying curative therapies for AD. The blood-brain barrier (BBB) acts as a selective physical barrier and plays protective roles in maintaining brain homeostasis. BBB dysfunction as an upstream or downstream event promotes the onset and progression of AD. Moreover, the pathogenesis of AD caused by BBB injury hasn't been well elucidated. Glial cells, BBB compartments and neurons form a minimal functional unit called the neurovascular unit (NVU). Emerging evidence suggests that glial cells are regulators in maintaining the BBB integrity and neuronal function. Illustrating the regulatory mechanism of glial cells in the BBB assists us in drawing a glial-vascular coupling diagram of AD, which may offer new insight into the pathogenesis of AD and early intervention strategies for AD. This review aims to summarize our current knowledge of glial-BBB interactions and their pathological implications in AD and to provide new therapeutic potentials for future investigations.

Examination of Genetic Variants Revealed from a Rat Model of Brain Ischemia in Patients with Ischemic Stroke: A Pilot Study

Although there has been great progress in understanding the genetic bases of ischemic stroke (IS), many of its aspects remain underexplored. These include the genetics of outcomes, as well as problems with the identification of real causative loci and their functional annotations. Therefore, analysis of the results obtained from animal models of brain ischemia could be helpful. We have developed a bioinformatic approach exploring single nucleotide polymorphisms (SNPs) in human orthologues of rat genes expressed differentially under conditions of induced brain ischemia. Using this approach, we identified and analyzed nine SNPs in 553 Russian individuals (331 patients with IS and 222 controls). We explored the association of SNPs with both IS outcomes and with the risk of IS. SNP rs66782529 (LGALS3) was associated with negative IS outcomes (p = 0.048). SNPs rs62278647 and rs2316710 (PTX3) were associated significantly with IS (p = 0.000029 and p = 0.0025, respectively). These correlations for rs62278647 and rs2316710 were found only in women, which suggests a sex-specific association of the PTX3 polymorphism. Thus, this research not only reveals some new genetic associations with IS and its outcomes but also shows how exploring variations in genes from a rat model of brain ischemia can be of use in searching for human genetic markers of this disorder.

Study on potential differentially expressed genes in stroke by bioinformatics analysis

Stroke is a sudden cerebrovascular circulatory disorder with high morbidity, disability, mortality, and recurrence rate, but its pathogenesis and key genes are still unclear. In this study, bioinformatics was used to deeply analyze the pathogenesis of stroke and related key genes, so as to study the potential pathogenesis of stroke and provide guidance for clinical treatment. Gene Expression profiles of GSE58294 and GSE16561 were obtained from Gene Expression Omnibus (GEO), the differentially expressed genes (DEGs) were identified between IS and normal control group. The different expression genes (DEGs) between IS and normal control group were screened with the GEO2R online tool. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs were performed. Using the Database for Annotation, Visualization and Integrated Discovery (DAVID) and gene set enrichment analysis (GSEA), the function and pathway enrichment analysis of DEGS were performed. Then, a protein–protein interaction (PPI) network was constructed via the Search Tool for the Retrieval of Interacting Genes (STRING) database. Cytoscape with CytoHubba were used to identify the hub genes. Finally, NetworkAnalyst was used to construct the targeted microRNAs (miRNAs) of the hub genes. A total of 85 DEGs were screened out in this study, including 65 upward genes and 20 downward genes. In addition, 3 KEGG pathways, cytokine − cytokine receptor interaction, hematopoietic cell lineage, B cell receptor signaling pathway, were significantly enriched using a database for labeling, visualization, and synthetic discovery. In combination with the results of the PPI network and CytoHubba, 10 hub genes including CEACAM8, CD19, MMP9, ARG1, CKAP4, CCR7, MGAM, CD79A, CD79B, and CLEC4D were selected. Combined with DEG-miRNAs visualization, 5 miRNAs, including hsa-mir-146a-5p, hsa-mir-7-5p, hsa-mir-335-5p, and hsa-mir-27a- 3p, were predicted as possibly the key miRNAs. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of ischemic stroke, and provide a new strategy for clinical therapy.

Immune Cells in the BBB Disruption After Acute Ischemic Stroke: Targets for Immune Therapy?

Blood-Brain Barrier (BBB) disruption is an important pathophysiological process of acute ischemic stroke (AIS), resulting in devastating malignant brain edema and hemorrhagic transformation. The rapid activation of immune cells plays a critical role in BBB disruption after ischemic stroke. Infiltrating blood-borne immune cells (neutrophils, monocytes, and T lymphocytes) increase BBB permeability, as they cause microvascular disorder and secrete inflammation-associated molecules. In contrast, they promote BBB repair and angiogenesis in the latter phase of ischemic stroke. The profound immunological effects of cerebral immune cells (microglia, astrocytes, and pericytes) on BBB disruption have been underestimated in ischemic stroke. Post-stroke microglia and astrocytes can adopt both an M1/A1 or M2/A2 phenotype, which influence BBB integrity differently. However, whether pericytes acquire microglia phenotype and exert immunological effects on the BBB remains controversial. Thus, better understanding the inflammatory mechanism underlying BBB disruption can lead to the identification of more promising biological targets to develop treatments that minimize the onset of life-threatening complications and to improve existing treatments in patients. However, early attempts to inhibit the infiltration of circulating immune cells into the brain by blocking adhesion molecules, that were successful in experimental stroke failed in clinical trials. Therefore, new immunoregulatory therapeutic strategies for acute ischemic stroke are desperately warranted. Herein, we highlight the role of circulating and cerebral immune cells in BBB disruption and the crosstalk between them following acute ischemic stroke. Using a robust theoretical background, we discuss potential and effective immunotherapeutic targets to regulate BBB permeability after acute ischemic stroke.

A1/A2 astrocytes in central nervous system injuries and diseases: Angels or devils?

Astrocytes play a pivotal role in maintaining the central nervous system (CNS) homeostasis and function. In response to CNS injuries and diseases, reactive astrocytes are triggered. By purifying and genetically profiling reactive astrocytes, it has been now found that astrocytes can be activated into two polarization states: the neurotoxic or pro-inflammatory phenotype (A1) and the neuroprotective or anti-inflammatory phenotype (A2). Although the simple dichotomy of the A1/A2 phenotypes does not reflect the wide range of astrocytic phenotypes, it facilitates our understanding of the reactive state of astrocytes in various CNS disorders. This article reviews the recent evidences regarding A1/A2 astrocytes, including (a) the specific markers and morphological characteristics, (b) the effects of A1/A2 astrocytes on the neurovascular unit, and (c) the molecular mechanisms involved in the phenotypic switch of astrocytes. Although many questions remain, a deeper understanding of different phenotypic astrocytes will eventually help us to explore effective strategies for neurological disorders by targeting astrocytes.

Long pentraxin PTX3 is upregulated systemically and centrally after experimental neurotrauma, but its depletion leaves unaltered sensorimotor deficits or histopathology

Long pentraxin PTX3, a pattern recognition molecule involved in innate immune responses, is upregulated by pro-inflammatory stimuli, contributors to secondary damage in traumatic brain injury (TBI). We analyzed PTX3 involvement in mice subjected to controlled cortical impact, a clinically relevant TBI mouse model. We measured PTX3 mRNA and protein in the brain and its circulating levels at different time point post-injury, and assessed behavioral deficits and brain damage progression in PTX3 KO mice. PTX3 circulating levels significantly increased 1-3 weeks after injury. In the brain, PTX3 mRNA was upregulated in different brain areas starting from 24 h and up to 5 weeks post-injury. PTX3 protein significantly increased in the brain cortex up to 3 weeks post-injury. Immunohistochemical analysis showed that, 48 h after TBI, PTX3 was localized in proximity of neutrophils, likely on neutrophils extracellular traps (NETs), while 1- and 2- weeks post-injury PTX3 co-localized with fibrin deposits. Genetic depletion of PTX3 did not affect sensorimotor deficits up to 5 weeks post-injury. At this time-point lesion volume and neuronal count, axonal damage, collagen deposition, astrogliosis, microglia activation and phagocytosis were not different in KO compared to WT mice. Members of the long pentraxin family, neuronal pentraxin 1 (nPTX1) and pentraxin 4 (PTX4) were also over-expressed in the traumatized brain, but not neuronal pentraxin 2 (nPTX2) or short pentraxins C-reactive protein (CRP) and serum amyloid P-component (SAP). The long-lasting pattern of activation of PTX3 in brain and blood supports its specific involvement in TBI. The lack of a clear-cut phenotype in PTX3 KO mice may depend on the different roles of this protein, possibly involved in inflammation early after injury and in repair processes later on, suggesting distinct functions in acute phases versus sub-acute or chronic phases. Brain long pentraxins, such as PTX4-shown here to be overexpressed in the brain after TBI-may compensate for PTX3 absence.

Neurogenesis After Stroke: A Therapeutic Perspective

Stroke is a major cause of death and disability worldwide. Yet therapeutic strategies available to treat stroke are very limited. There is an urgent need to develop novel therapeutics that can effectively facilitate functional recovery. The injury that results from stroke is known to induce neurogenesis in penumbra of the infarct region. There is considerable interest in harnessing this response for therapeutic purposes. This review summarizes what is currently known about stroke-induced neurogenesis and the factors that have been identified to regulate it. Additionally, some key studies in this field have been highlighted and their implications on future of stroke therapy have been discussed. There is a complex interplay between neuroinflammation and neurogenesis that dictates stroke outcome and possibly recovery. This highlights the need for a better understanding of the neuroinflammatory process and how it affects neurogenesis, as well as the need to identify new mechanisms and potential modulators. Neuroinflammatory processes and their impact on post-stroke repair have therefore also been discussed.

Molecular Biology of Atherosclerotic Ischemic Strokes

Among the causes of global death and disability, ischemic stroke (also known as cerebral ischemia) plays a pivotal role, by determining the highest number of worldwide mortality, behind cardiomyopathies, affecting 30 million people. The etiopathogenetic burden of a cerebrovascular accident could be brain ischemia (~80%) or intracranial hemorrhage (~20%). The most common site when ischemia occurs is the one is perfused by middle cerebral arteries. Worse prognosis and disablement consequent to brain damage occur in elderly patients or affected by neurological impairment, hypertension, dyslipidemia, and diabetes. Since, in the coming years, estimates predict an exponential increase of people who have diabetes, the disease mentioned above constitutes together with stroke a severe social and economic burden. In diabetic patients after an ischemic stroke, an exorbitant activation of inflammatory molecular pathways and ongoing inflammation is responsible for more severe brain injury and impairment, promoting the advancement of ischemic stroke and diabetes. Considering that the ominous prognosis of ischemic brain damage could by partially clarified by way of already known risk factors the auspice would be modifying poor outcome in the post-stroke phase detecting novel biomolecules associated with poor prognosis and targeting them for revolutionary therapeutic strategies.

Polydatin promotes the neuronal differentiation of bone marrow mesenchymal stem cells in vitro and in vivo: Involvement of Nrf2 signalling pathway

Bone marrow mesenchymal stem cell (BMSC) transplantation represents a promising repair strategy following spinal cord injury (SCI), although the therapeutic effects are minimal due to their limited neural differentiation potential. Polydatin (PD), a key component of the Chinese herb Polygonum cuspidatum, exerts significant neuroprotective effects in various central nervous system disorders and protects BMSCs against oxidative injury. However, the effect of PD on the neuronal differentiation of BMSCs, and the underlying mechanisms remain inadequately understood. In this study, we induced neuronal differentiation of BMSCs in the presence of PD, and analysed the Nrf2 signalling and neuronal differentiation markers using routine molecular assays. We also established an in vivo model of SCI and assessed the locomotor function of the mice through hindlimb movements and electrophysiological measurements. Finally, tissue regeneration was evaluated by H&E staining, Nissl staining and transmission electron microscopy. PD (30 μmol/L) markedly facilitated BMSC differentiation into neuron‐like cells by activating the Nrf2 pathway and increased the expression of neuronal markers in the transplanted BMSCs at the injured spinal cord sites. Furthermore, compared with either monotherapy, the combination of PD and BMSC transplantation promoted axonal rehabilitation, attenuated glial scar formation and promoted axonal generation across the glial scar, thereby enhancing recovery of hindlimb locomotor function. Taken together, PD augments the neuronal differentiation of BMSCs via Nrf2 activation and improves functional recovery, indicating a promising new therapeutic approach against SCI.

Determination of pentraxin 3 levels in cerebrospinal fluid during central nervous system infections

Pentraxin 3 (PTX3) is an acute phase protein; its plasmatic levels significantly rise during severe infections. Data on PTX3 levels in cerebrospinal fluid (CSF) of patients with central nervous system (CNS) infections are lacking. We aimed (a) to assess the diagnostic potential of measuring CSF PTX3 levels in patients with CNS infections and (b) to establish CSF PTX3 cutoffs to distinguish between bacterial and aseptic meningoencephalitis (ROC curve). PTX3 levels were measured in CSF from 19 patients admitted to Trieste Hospital, Italy, with CNS infection. A diagnosis of bacterial infection and aseptic meningoencephalitis was made in 7 (37%) and 12 (63%) patients, respectively. Subjects with bacterial infections showed significantly higher PTX3 levels (13.5 vs 1.27 ng/mL in aseptic meningoencephalitis, p = 0.010). We identified two different CSF PTX3 levels cutoffs. (1) The best cutoff to maximise Youden's J was 9.6 ng/mL with a sensitivity, specificity, positive predictive value and negative predictive value (NPV) of 71.4%, 91.4%, 83.3%, 84.6%, respectively. (2) The cutoff with higher NPV (100%) was 3.6 ng/mL; a diagnosis of bacterial infections was obtained in 0% patients with CSF PTX3 levels < 3.6 ng/mL vs 58% of those with CSF PTX3 levels ≥ 3.6 ng/mL (p = 0.017). CSF PTX3 levels are higher in bacterial meningitis than aseptic meningoencephalitis. A cutoff of 3.6 ng/mL of CSF PTX3 has a high NPV and can be used to exclude bacterial CNS infections.

Pentraxin-3 Modulates Osteogenic/Odontogenic Differentiation and Migration of Human Dental Pulp Stem Cells

Pentraxin-3 (PTX3) is recognized as a modulator of inflammation and a mediator of tissue repair. In this study, we characterized the role of PTX3 on some biological functions of human dental pulp stem cells (HDPSCs). The expression level of PTX3 significantly increased during osteogenic/odontogenic differentiation of HDPSCs, whereas the knockdown of PTX3 decreased this differentiation. Silencing of PTX3 in HDPSCs inhibited their migration and C-X-C chemokine receptor type 4 (CXCR4) expression. Our present study indicates that PTX3 is involved in osteogenic/odontogenic differentiation and migration of HDPSCs, and may contribute to the therapeutic potential of HDPSCs for regeneration and repair.

Brief overview: Protective roles of astrocyte-derived pentraxin-3 in blood-brain barrier integrity

Stroke is one of the world's leading causes of mortality and morbidity. Greater understanding is required of the underlying relationships in ischemic brains in order to prevent stroke or to develop effective treatment. This review highlights new findings about the relationship of blood–brain barrier with astrocytes, pentraxin-3 (PTX3), and other factors expressed during or after ischemic stroke. These are discussed with respect to their ameliorative or deleterious effects. These effects are measured in vivo in animal models as well as in vitro in cell cultures. Evidence was found to suggest that astrocytes play a key role in stroke by expressing PTX3, which, in turn, enhances endothelial tightness, increases tight junction proteins, and inhibits vascular endothelial growth factor. The role of astrocytes and PTX3 is examined in relation to hypoxic stress and conditioning as well as mitochondrial transfer. Astrocytes and PTX3 are placed in the context of brain circulation and related areas.

Tissue Dependent Role of PTX3 During Ischemia-Reperfusion Injury

Reperfusion of an ischemic tissue is the treatment of choice for several diseases, including myocardial infarction and stroke. However, reperfusion of an ischemic tissue causes injury, known as Ischemia and Reperfusion Injury (IRI), that limits the benefit of blood flow restoration. IRI also occurs during solid organ transplantation. During IRI, there is activation of the innate immune system, especially neutrophils, which contributes to the degree of injury. It has been shown that PTX3 can regulate multiple aspects of innate immunity and tissue inflammation during sterile injury, as observed during IRI. In humans, levels of PTX3 increase in blood and elevated levels associate with extent of IRI. In mice, there is also enhanced expression of PTX3 in tissues and plasma after IRI. In general, absence of PTX3, as seen in PTX3-deficient mice, results in worse outcome after IRI. On the contrary, increased expression of PTX3, as seen in PTX3 transgenic mice and after PTX3 administration, is associated with better outcome after IRI. The exception is the gut where PTX3 seems to have a clear deleterious role. Here, we discuss mechanisms by which PTX3 contributes to IRI and the potential of taming this system for the treatment of injuries associated with reperfusion of solid organs.

Pentraxin 3 regulates neutrophil infiltration to the brain during neuroinflammation

Introduction: The acute phase protein pentraxin 3 (PTX3) is known for its anti-inflammatory effects through downregulating neutrophil transmigration during peripheral inflammation. Furthermore, we have previously demonstrated a neuroprotective and neuroreparative effect of PTX3 after cerebral ischaemia. Here we investigated, to our knowledge for the first time, the role of PTX3 in neutrophil transmigration and neurotoxicity following lipopolysaccharide (LPS)-induced cerebral inflammation and cerebral ischaemia.

Methods: Neutrophil transmigration through interleukin-1β (IL-1β) activated brain endothelium and neurotoxicity of neutrophils isolated from wild-type (WT) or PTX3 knock-out (KO) mice was assessed in vitro. Primary cortical neuronal death after treatment with transmigrated neutrophils was quantified by lactate dehydrogenase (LDH) assay. Cerebral inflammation or ischemia was induced in WT and PTX3 KO mice via intrastriatal LPS injection or by transient middle cerebral artery occlusion (MCAo) respectively. Subsequent neutrophil infiltration in the brain was assessed by immunohistochemistry and the expression of pro-inflammatory cytokines interleukin-6 (IL-6) and IL-1β by enzyme-linked immunosorbent assay (ELISA).

Results: Neutrophils isolated from WT mice after intrastriatal LPS injection transmigrated significantly more through IL-1β activated brain endothelium compared to neutrophils from PTX3 KO mice. Transmigrated WT and PTX3 KO neutrophils were significantly more neurotoxic than corresponding non-transmigrated neutrophils; however, no significant differences in neurotoxicity between genotypes were observed. PTX3 reduced the number of transmigrated neutrophils to the brain after intrastriatal LPS injection. Furthermore, PTX3 KO mice showed significantly increased levels of neutrophils in the brain after LPS administration or in the ischaemic hemisphere after MCAo, compared to WT mice.

Conclusion: Our study shows that PTX3 regulates neutrophil transmigration in the CNS during neuroinflammation, demonstrating the potential of PTX3 as an effective therapeutic target in neuroinflammatory conditions.

Pentraxin 3 in Cardiovascular Disease

The long pentraxin PTX3 is a member of the pentraxin family produced locally by stromal and myeloid cells in response to proinflammatory signals and microbial moieties. The prototype of the pentraxin family is C reactive protein (CRP), a widely-used biomarker in human pathologies with an inflammatory or infectious origin. Data so far describe PTX3 as a multifunctional protein acting as a functional ancestor of antibodies and playing a regulatory role in inflammation. Cardiovascular disease (CVD) is a leading cause of mortality worldwide, and inflammation is crucial in promoting it. Data from animal models indicate that PTX3 can have cardioprotective and atheroprotective roles regulating inflammation. PTX3 has been investigated in several clinical settings as possible biomarker of CVD. Data collected so far indicate that PTX3 plasma levels rise rapidly in acute myocardial infarction, heart failure and cardiac arrest, reflecting the extent of tissue damage and predicting the risk of mortality.

The Long Pentraxin PTX3 as a Link Between Innate Immunity, Tissue Remodeling, and Cancer

The innate immune system comprises a cellular and a humoral arm. Humoral pattern recognition molecules include complement components, collectins, ficolins, and pentraxins. These molecules are involved in innate immune responses by recognizing microbial moieties and damaged tissues, activating complement, exerting opsonic activity and facilitating phagocytosis, and regulating inflammation. The long pentraxin PTX3 is a prototypic humoral pattern recognition molecule that, in addition to providing defense against infectious agents, plays several functions in tissue repair and regulation of cancer-related inflammation. Characterization of the PTX3 molecular structure and biochemical properties, and insights into its interactome and multiple roles in tissue damage and remodeling support the view that microbial and matrix recognition are evolutionarily conserved functions of humoral innate immunity molecules.

Pentraxin 3 Detects Clinically Significant Fibrosis in Patients with Chronic Viral Hepatitis C

Pentraxin 3 (PTX3) plays a pathogenic role in experimental models of chronic liver injury and contributes to the progression of fibrosis. The detection of advanced fibrosis (METAVIR F≥3) is important to identify patients who are in urgent need of antiviral treatments versus those whose treatment could be deferred (F≥2). The aim was to assess the diagnostic value of PTX3 as a potential biomarker for clinically significant and advanced fibrosis. PTX3 associations with biochemical and histological parameters of inflammatory activity and fibrosis were investigated in 138 patients with chronic viral hepatitis C (HCV) before antiviral treatment. METAVIR histological scores of activity and fibrosis were obtained. PTX3 was measured by enzyme-linked immunosorbent assay. The diagnostic accuracy of serum PTX3 levels was compared to that of other fibrosis markers, including transforming growth factor‐β₁ (TGF-β₁), hyaluronic acid (HA), aspartate transaminase to platelet ratio index (APRI), fibrosis score based on four factors (FIB4), gamma-glutamyltranspeptidase to platelet ratio (GPR), and the liver stiffness measurement (LSM) by transient elastography (FibroScan®). In HCV patients the PTX3 level increased in parallel with the METAVIR histological score of activity, being independently associated with the METAVIR fibrosis score (P < 0.001). Using the receiver operating characteristics analysis, the best marker for detecting F≥2 and F≥3 was PTX3 with AUC = 0.802 and AUC = 0.867, respectively. The area under the curve of PTX3 for predicting significant fibrosis (F≥2) was significantly greater than those for the GPR ratio (AUC = 0.648) and FIB-4 score (AUC = 0.770) and similar to that for APRI index (AUC = 0.831). PTX3 provided clinically relevant diagnostic accuracy as a single marker of significant fibrosis.

Pentraxin 3 Modulates the Inflammatory Response in Human Dental Pulp Cells

INTRODUCTION

Pentraxin 3 (PTX3) has been suggested as a novel inflammatory biomarker in inflammation-associated diseases. The aim of this study was to examine the role of PTX3 in the inflammatory response of human dental pulp cells (HDPCs).

METHODS

HDPCs were treated with tumor necrosis factor alpha (TNF-α), and total RNA and protein were extracted. PTX3 messenger RNA and protein expression levels were analyzed using reverse transcription polymerase chain reaction and Western blotting, respectively. For PTX3 knockdown, HDPCs were transfected with a small interfering RNA against human PTX3. Macrophage chemotaxis after PTX3 silencing in HDPCs was assessed by transwell migration assays.

RESULTS

TNF-α increased PTX3 messenger RNA and protein levels in HDPCs. TNF-α-induced PTX3 expression was mediated by extracellular signal-regulated kinase 1/2 and nuclear factor kappa B. PTX3 knockdown decreased the expression levels of interleukin 6, interleukin 8, and monocyte chemoattractant protein 1 after stimulation with TNF-α in HDPCs. Moreover, PTX3 silencing in HDPCs significantly decreased the chemotactic migration of macrophages.

CONCLUSIONS

Our findings indicate PTX3 plays a critical role in the regulation of pulp inflammatory processes and reveal its underlying molecular mechanism.

Pentraxin 3 promotes long-term cerebral blood flow recovery, angiogenesis, and neuronal survival after stroke

Restoration of cerebral blood flow (CBF) and upregulation of angiogenesis are crucial for brain repair and functional recovery after cerebral ischaemia. Pentraxin 3 (PTX3) is a key regulator of angiogenesis and is emerging as a promising target for cerebrovascular repair after stroke. Here, we investigated for the first time the role of PTX3 in long-term CBF, angiogenesis, and neuronal viability after ischaemic stroke induced by transient middle cerebral artery occlusion (MCAo). Lack of PTX3 had no effect on early brain damage, but significantly impaired restoration of CBF, 14 and 28 days after MCAo, compared to wild-type (WT) mice. Immunohistochemical analysis revealed that PTX3 KO mice have significantly greater neuronal loss, significantly decreased vessel diameter, vessel proliferation, vascular density, and reactive astrocytes and decreased expression of vascular endothelial growth factor receptor 2 (VEGR2), vascular extracellular matrix (ECM)-proteins (collagen IV, laminin), and integrin-β, in the ipsilateral (stroke) hemisphere compared to WT mice, 28 days after MCAo. Therefore, PTX3 promotes sustained long-term recovery of CBF, angiogenesis, and neuronal viability after cerebral ischaemia. Collectively, these findings demonstrate the potential and clinical relevance of PTX3 as a promising therapeutic target, providing sustained long-term post-stroke neurovascular repair and reducing the loss of neurons. KEY MESSAGES: Pentraxin 3 (PTX3) is a key regulator of angiogenesis and is emerging as a promising target for cerebrovascular repair after stroke. Restoration of cerebral blood flow (CBF) and angiogenesis are crucial for brain repair and functional recovery after cerebral ischaemia. PTX3 promotes sustained long-term recovery of CBF, angiogenesis, and neuronal viability after cerebral ischaemia.

Astrocytes: Heterogeneous and Dynamic Phenotypes in Neurodegeneration and Innate Immunity

Astrocytes are the most numerous cell type in the brain and perform several essential functions in supporting neuronal metabolism and actively participating in neural circuit and behavioral function. They also have essential roles as innate immune cells in responding to local neuropathology, and the manner in which they respond to brain injury and degeneration is the subject of increasing attention in neuroscience. Although activated astrocytes have long been thought of as a relatively homogenous population, which alter their phenotype in a relatively stereotyped way upon central nervous system injury, the last decade has revealed substantial heterogeneity in the basal state and significant heterogeneity of phenotype during reactive astrocytosis. Thus, phenotypic diversity occurs at two distinct levels: that determined by regionality and development and that determined by temporally dynamic changes to the environment of astrocytes during pathology. These inflammatory and pathological states shape the phenotype of these cells, with different consequences for destruction or recovery of the local tissue, and thus elucidating these phenotypic changes has significant therapeutic implications. In this review, we will focus on the phenotypic heterogeneity of astrocytes in health and disease and their propensity to change that phenotype upon subsequent stimuli.

Pentraxin 3 regulates synaptic function by inducing AMPA receptor clustering via ECM remodeling and β1-integrin

Control of synapse number and function in the developing central nervous system is critical to the formation of neural circuits. Astrocytes play a key role in this process by releasing factors that promote the formation of excitatory synapses. Astrocyte‐secreted thrombospondins (TSPs) induce the formation of structural synapses, which however remain post‐synaptically silent, suggesting that completion of early synaptogenesis may require a two‐step mechanism. Here, we show that the humoral innate immune molecule Pentraxin 3 (PTX3) is expressed in the developing rodent brain. PTX3 plays a key role in promoting functionally‐active CNS synapses, by increasing the surface levels and synaptic clustering of AMPA glutamate receptors. This process involves tumor necrosis factor‐induced protein 6 (TSG6), remodeling of the perineuronal network, and a β1‐integrin/ERK pathway. Furthermore, PTX3 activity is regulated by TSP1, which directly interacts with the N‐terminal region of PTX3. These data unveil a fundamental role of PTX3 in promoting the first wave of synaptogenesis, and show that interplay of TSP1 and PTX3 sets the proper balance between synaptic growth and synapse function in the developing brain.

PTX3, a Humoral Pattern Recognition Molecule, in Innate Immunity, Tissue Repair, and Cancer

Innate immunity includes a cellular and a humoral arm. PTX3 is a fluid-phase pattern recognition molecule conserved in evolution which acts as a key component of humoral innate immunity in infections of fungal, bacterial, and viral origin. PTX3 binds conserved microbial structures and self-components under conditions of inflammation and activates effector functions (complement, phagocytosis). Moreover, it has a complex regulatory role in inflammation, such as ischemia/reperfusion injury and cancer-related inflammation, as well as in extracellular matrix organization and remodeling, with profound implications in physiology and pathology. Finally, PTX3 acts as an extrinsic oncosuppressor gene by taming tumor-promoting inflammation in murine and selected human tumors. Thus evidence suggests that PTX3 is a key homeostatic component at the crossroad of innate immunity, inflammation, tissue repair, and cancer. Dissecting the complexity of PTX3 pathophysiology and human genetics paves the way to diagnostic and therapeutic exploitation.

Interleukin-1 Receptor 1 Deletion in Focal and Diffuse Experimental Traumatic Brain Injury in Mice

Important differences in the biology of focal and diffuse traumatic brain injury (TBI) subtypes may result in unique pathophysiological responses to shared molecular mechanisms. Interleukin-1 (IL-1) signaling has been tested as a potential therapeutic target in preclinical models of cerebral contusion and diffuse TBI, and in a phase II clinical trial, but no published studies have examined IL-1 signaling in an impact/acceleration closed head injury (CHI) model. We hypothesized that genetic deletion of IL-1 receptor-1 (IL-1R1 KO) would be beneficial in focal (contusion) and CHI in mice. Wild type and IL-1R1 KO mice were subjected to controlled cortical impact (CCI), or to CHI. CCI produced brain leukocyte infiltration, HMGB1 translocation and release, edema, cell death, and cognitive deficits. CHI induced peak rotational acceleration of 9.7 × 10⁵ ± 8.1 × 10⁴ rad/s², delayed time to righting reflex, and robust Morris water maze deficits without deficits in tests of anxiety, locomotion, sensorimotor function, or depression. CHI produced no discernable acute plasmalemma damage or cell death, blood-brain barrier permeability to IgG, or brain edema and only a modest increase in brain leukocyte infiltration at 72 h. In both models, mature (17 kDa) interleukin-1 beta (IL-1β) was induced by 24 h in CD31+ endothelial cells isolated from injured brain but was not induced in CD11b⁺ cells in either model. High mobility group box protein-1 was released from injured brain cells in CCI but not CHI. Surprisingly, cognitive outcome in mice with global deletion of IL-1R1 was improved in CHI, but worse after CCI without affecting lesion size, edema, or infiltration of CD11b⁺/CD45⁺ leukocytes in CCI. IL-1R1 may induce unique biological responses, beneficial or detrimental to cognitive outcome, after TBI depending on the pathoanatomical subtype. Brain endothelium is a hitherto unrecognized source of mature IL-1β in both models.

The Impact of Uremic Toxins on Cerebrovascular and Cognitive Disorders

Individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing cognitive disorders and dementia. Stroke is also highly prevalent in this population and is associated with a higher risk of neurological deterioration, in-hospital mortality, and poor functional outcomes. Evidence from in vitro studies and in vivo animal experiments suggests that accumulation of uremic toxins may contribute to the pathogenesis of stroke and amplify vascular damage, leading to cognitive disorders and dementia. This review summarizes current evidence on the mechanisms by which uremic toxins may favour the occurrence of cerebrovascular diseases and neurological complications in CKD.

Potentially Common Therapeutic Targets for Multiple Sclerosis and Ischemic Stroke

Ischemic stroke (IS) and multiple sclerosis (MS) are two pathologies of the central nervous system (CNS). At the first look, this appears to be the only similarity between the two diseases, as they seem quite different. Indeed IS has an acute onset compared to MS which develops chronically; IS is consecutive to blood clot migrating to cerebral blood vessels or decrease in cerebral blood flow following atherosclerosis or decreases in cardiac output, whereas MS is an immune disease associated with neurodegeneration. However, both pathologies share similar pathologic pathways and treatments used in MS have been the object of studies in IS. In this mini-review we will discuss similarities between IS and MS on astrocytes and neuroinflammation hallmarks emphasizing the potential for treatments.

Microglia in the Neurovascular Unit: Blood-Brain Barrier-microglia Interactions After Central Nervous System Disorders

Over the past few decades, microglial cells have been regarded as the main executor of inflammation after acute and chronic central nervous system (CNS) disorders, responding rapidly to exogenous stimuli during acute trauma or infections, or signals released by cells undergoing cell death during conditions such as stroke, Alzheimer's disease (AD) and Parkinson's disease (PD). Barriers of the nervous system, and in particular the blood-brain barrier (BBB), play a key role in the normal physiological and cognitive functions of the brain. Being at the interface between the central and peripheral compartment, the BBB is regarded as a sensor of homeostasis, and any disruption within the brain or the systemic compartment triggers BBB dysfunction and neuroinflammation, both contributing to the pathogenesis of cerebrovascular disease. This involves a dynamic response mediated by all components of the neurovascular unit (NVU), and ongoing research suggests that BBB-microglia interaction is critical to dictate the microglial response to NVU injury. The present review aims to give an up-to-date account of the emerging critical role of BBB-microglia interactions during neuroinflammation, and how these could be targeted for the therapeutic treatment of major central inflammatory disease.

Pentraxin-3 in Thrombolytic Therapy for Acute Ischemic Stroke: No Relation with Curative Effect and Prognosis

Background

Pentraxin-3 (PTX3) is considered a high quality inflammatory marker of the severity and prognosis of several diseases, however, the value of PTX3 in thrombolytic therapy for acute ischemic stroke remains unclear and PTX3 is still controversial in evaluating the prognosis of stroke patients. In this study, we investigated the association of PTX3 with thrombolytic therapy in patients with acute ischemic stroke.

Material/Methods

Forty-seven stroke patients who received thrombolytic therapy within 4.5 hours after symptom onset were enrolled consecutively between July 2016 and June 2017. All the patients underwent multiphase CTA (computerized tomography angiography) or CT perfusion before thrombolysis with no indication for endovascular treatment. Initial and 24 hours of National Institute of Health Stroke Scale (NIHSS) scores and serum PTX3 level, stroke risk factors and predictors, and mRS (modified Rankin scale) at 3 months were collected prospectively. Predictors of thrombolytic therapy effect and long-term prognosis were investigated by univariate and multivariate logistic regression.

Results

The 24 hour NIHSS score and the treatment time was associated with symptom improvement, while the PTX3 level had no association with neurological improvement and prognosis in stroke patients receiving thrombolytic therapy.

Conclusions

PTX3 is not suitable to serve as an indicator of thrombolytic efficacy and had no association with long-term prognosis in stroke patients receiving thrombolytic therapy.

The long pentraxin PTX3: A prototypical sensor of tissue injury and a regulator of homeostasis

Tissue damage frequently occurs. The immune system senses it and enforces homeostatic responses that lead to regeneration and repair. The synthesis of acute phase molecules is emerging as a crucial event in this program. The prototypic long pentraxin PTX3 orchestrates the recruitment of leukocytes, stabilizes the provisional matrix in order to facilitate leukocyte and stem progenitor cells trafficking, promotes swift and safe clearance of dying cells and of autoantigens, limiting autoimmunity and protecting the vasculature. These non-redundant actions of PTX3 are necessary for the resolution of inflammation. Recent studies have highlighted the mechanisms by which PTX3 adapts the functions of innate immune cells, orchestrates tissue repair and contributes to select the appropriate acquired immune response in various tissues. Conversely, PTX3 continues to be produced in diseases where the inflammatory response does not resolve. It is therefore a valuable biomarker for more precise and personalized stratification of patients, often independently predicting clinical evolution and outcome. There is strong promise for novel therapies based on understanding the mechanisms with which PTX3 plays its homeostatic role, especially in regulating leukocyte migration and the resolution of inflammatory processes.

Allogeneic transplantation of programmable cells of monocytic origin (PCMO) improves angiogenesis and tissue recovery in critical limb ischemia (CLI): a translational approach

BACKROUND

Employing growth factor-induced partial reprogramming in vitro, peripheral human blood monocytes can acquire a state of plasticity along with expression of various markers of pluripotency. These so-called programmable cells of monocytic origin (PCMO) hold great promise in regenerative therapies. The aim of this translational study was to explore and exploit the functional properties of PCMO for allogeneic cell transplantation therapy in critical limb ischemia (CLI).

METHODS

Using our previously described differentiation protocol, murine and human monocytes were differentiated into PCMO. We examined paracrine secretion of pro-angiogenic and tissue recovery-associated proteins under hypoxia and induction of angiogenesis by PCMO in vitro. Allogeneic cell transplantation of PCMO was performed in a hind limb ischemia mouse model in comparison to cell transplantation of native monocytes and a placebo group. Moreover, we analyzed retrospectively four healing attempts with PCMO in patients with peripheral artery disease (PAD; Rutherford classification, stage 5 and 6). Statistical analysis was performed by using one-way ANOVA, Tukey's test or the Student's t test, p < 0.05.

RESULTS

Cell culture experiments revealed good resilience of PCMO under hypoxia, enhanced paracrine release of pro-angiogenic and tissue recovery-associated proteins and induction of angiogenesis in vitro by PCMO. Animal experiments demonstrated significantly enhanced SO₂ saturation, blood flow, neoangiogenesis and tissue recovery after treatment with PCMO compared to treatment with native monocytes and placebo. Finally, first therapeutic application of PCMO in humans demonstrated increased vascular collaterals and improved wound healing in patients with chronic CLI without exaggerated immune response, malignant processes or extended infection after 12 months. In all patients minor and/or major amputations of the lower extremity could be avoided.

CONCLUSIONS

In summary, PCMO improve angiogenesis and tissue recovery in chronic ischemic muscle and first clinical results promise to provide an effective and safe treatment of CLI.

Sirt3 Mediates the Inhibitory Effect of Adjudin on Astrocyte Activation and Glial Scar Formation following Ischemic Stroke

In response to stroke-induced injury, astrocytes can be activated and form a scar. Inflammation is an essential component for glial scar formation. Previous study has shown that adjudin, a potential Sirt3 activator, could attenuate lipopolysaccharide (LPS)- and stroke-induced neuroinflammation. To investigate the potential inhibitory effect and mechanism of adjudin on astrocyte activation, we used a transient middle cerebral artery occlusion (tMCAO) model with or without adjudin treatment in wild type (WT) and Sirt3 knockout (KO) mice and performed a wound healing experiment in vitro. Both our in vivo and in vitro results showed that adjudin reduced astrocyte activation by upregulating Sirt3 expression. In addition, adjudin treatment after stroke promoted functional and neurovascular recovery accompanied with the decreased area of glial scar in WT mice, which was blunted by Sirt3 deficiency. Furthermore, adjudin could increase Foxo3a and inhibit Notch1 signaling pathway via Sirt3. Both the suppression of Foxo3a and overexpression of N1ICD could alleviate the inhibitory effect of adjudin in vitro indicating that Sirt3-Foxo3a and Sirt3-Notch1 signaling pathways were involved in the inhibitory effect of adjudin in wound healing experiment.

Update on the role of Pentraxin 3 in atherosclerosis and cardiovascular diseases

Pentraxin 3 (PTX3) is an acute-phase protein that was recently demonstrated to play pleiotropic activities in cardiovascular (CV) diseases. Tumor necrosis factor and interleukins up-regulates PTX3 transcription in different cell types (i.e. endothelial cells, phagocytes, smooth muscle cells, fibroblasts and glial cells) involved in atherogenesis. By interacting with numerous ligands, PTX3 acts as a modulatory molecule of complement system, inflammatory response, angiogenesis, and vascular/tissue remodeling. Experimental data point to a beneficial role of PTX3 in atherosclerotic plaque development and vulnerability. Animal studies indicated a protective role of PTX3 signaling in ischemic/reperfusion injury and failing heart. Clinical studies have so far provided contrasting results, highlighting a debated role of PTX3 as an active mediator of endothelial dysfunction, atherosclerotic plaque vulnerability and worse outcome after ischemic events. Therefore, substantial evidence suggests a dual role of PTX3 as modulator or amplifiers of the innate immune response. The final result of PTX3 activation might be determined by a fine tuning of time, space and environmental signals. The aim of this review is to provide an overview of biological properties of PTX3 in CV diseases and to discuss the ability of PTX3 to act as a crossroad between pro- and anti-inflammatory pathways.

Pentraxins in the activation and regulation of innate immunity

Humoral fluid phase pattern recognition molecules (PRMs) are a key component of the activation and regulation of innate immunity. Humoral PRMs are diverse. We focused on the long pentraxin PTX3 as a paradigmatic example of fluid phase PRMs. PTX3 acts as a functional ancestor of antibodies and plays a non-redundant role in resistance against selected microbes in mouse and man and in the regulation of inflammation. This molecule interacts with complement components, thus modulating complement activation. In particular, PTX3 regulates complement-driven macrophage-mediated tumor progression, acting as an extrinsic oncosuppressor in preclinical models and selected human tumors. Evidence collected over the years suggests that PTX3 is a biomarker and potential therapeutic agent in humans, and pave the way to translation of this molecule into the clinic.

Semi-synthetic sapogenin exerts neuroprotective effects by skewing the brain ischemia reperfusion transcriptome towards inflammatory resolution

Stroke represents one of the first causes of mortality and morbidity worldwide. We evaluated the therapeutic potential of a novel semi-synthetic spirosteroid sapogenin derivative "S15" in a transient middle cerebral artery occlusion (tMCAO) focal ischemia model in rat. S15-treated rats had significantly reduced infarct volumes and improved neurological functions at 24h post-reperfusion, compared with ischemia. Corresponding gene expression changes in brain were characterized by mRNA sequencing and qPCR approaches. Next, we applied geneset, pathway and transcription factor motif enrichment analysis to identify relevant signaling networks responsible for neuronal damage upon ischemia-reperfusion or neuroprotection upon pretreatment with S15. As expected, ischemia-reperfusion brain damage strongly modulates transcriptional programs associated with immune responses, increased differentiation of immune cells as well as reduced (cat)ion transport and synaptic activity. Interestingly, S15-dependent neuroprotection regulates inflammation-associated genes involved in phagosome specific resolution of tissue damage, chemotaxis and anti-inflammatory alternative activation of microglia. Altogether our transcriptome wide RNA sequencing and integrated pathway analysis provides new clues in the neuroprotective properties of a novel spirosteroid S15 or neuronal damage in rat brains subjected to ischemia, which opens new perspectives for successful treatment of stroke.

Effects of 6 months of resveratrol versus placebo on pentraxin 3 in patients with type 2 diabetes mellitus: a double-blind randomized controlled trial

AIMS

The anti-inflammatory effects of the polyphenol resveratrol in patients with type 2 diabetes mellitus (T2DM) are controversial. Its role on pentraxin 3 (PTX3) concentrations, a human acute phase protein, has never been evaluated. Our aim was to determine whether a two-dosage resveratrol supplementation (500 and 40 mg/day) has an impact on PTX3 values in T2DM patients from a double-blind randomized placebo-controlled trial. Variations in total antioxidant status (TAS) were evaluated too.

METHODS

A total of 192 T2DM patients were randomized to receive resveratrol 500 mg/day (Resv 500 arm), resveratrol 40 mg/day (Resv 40 arm) or placebo for 6 months. At baseline and at the trial end, PTX3 and TAS values were determined.

RESULTS

A dose-dependent increase in PTX3 concentrations of 4.7% (Resv 40 arm) and 26.3% (Resv 500 arm), and 8.0% reduction after placebo were found. Adjusted mean differences of change versus placebo were 0.16 (95% CI 0.01-0.32) and 0.25 (0.09-0.42) in the Resv 40 and Resv 500 arms, respectively. At subgroup analyses, lower diabetes duration, aspirin, alcohol use, younger age, female gender, smoking (Resv 500 arm) and female gender and aspirin use (Resv 40 arm) were associated with higher PTX3 increments. A dose-dependent increment in TAS values in the resveratrol arms (1.4 and 6.4% for Resv 40 and Resv 500, respectively), and a reduction in placebo arm (-8.9%) were observed. Adjusted mean differences of change were 28.5 (95% CI 10.1-46.8) and 44.8 (25.4-64.1) in the Resv 40 and Resv 500 arms, respectively.

CONCLUSION

Resveratrol supplementation increased PTX3 and TAS levels in a dose-dependent manner in T2DM patients. At present, potential clinical implications of these results remain unclear. CLINICALTRIALS.

GOV IDENTIFIER

NCT02244879.

A Thermosensitive Heparin-Poloxamer Hydrogel Bridges aFGF to Treat Spinal Cord Injury

Acidic fibroblast growth factor (aFGF) exerts a protective effect on spinal cord injury (SCI) but is limited by the lack of physicochemical stability and the ability to cross the blood spinal cord barrier (BSCB). As promising biomaterials, hydrogels contain substantial amounts of water and a three-dimensional porous structure and are commonly used to load and deliver growth factors. Heparin can not only enhance growth factor loading onto hydrogels but also can stabilize the structure and control the release behavior. Herein, a novel aFGF-loaded thermosensitive heparin-poloxamer (aFGF-HP) hydrogel was developed and applied to provide protection and regeneration after SCI. To assess the effects of the aFGF-HP hydrogel, BSCB restoration, neuron and axonal rehabilitation, glial scar inhibition, inflammatory response suppression, and motor recovery were studied both in vivo and in vitro. The aFGF-HP hydrogels exhibited sustained release of aFGF and protected the bioactivity of aFGF in vitro. Compared to groups intravenously administered either drug-free HP hydrogel or aFGF alone, the aFGF-HP hydrogel group revealed prominent and attenuated disruption of the BSCB, reduced neuronal apoptosis, reactive astrogliosis, and increased neuron and axonal rehabilitation both in vivo and in vitro. This work provides an effective approach to enhance recovery after SCI and provide a successful strategy for SCI protection.

The clearance of cell remnants and the regeneration of the injured muscle depend on soluble pattern recognition receptor PTX3

OBJECTIVE

The signals causing the resolution of muscle inflammation are only partially characterized. The long pentraxin PTX3, which modulates leukocyte recruitment and activation, could contribute.

METHODS

We analysed the expression of ptx3 after muscle injury and verified whether hematopoietic precursors are a source of the protein. The kinetics of regeneration and leukocytes infiltration, the accumulation of cell remnants and anti-histidyl-t-RNA synthetase autoantibodies were compared in wild-type and ptx3-deficient mice.

RESULTS

Ptx3 expression was up-regulated three-five days after injury and restricted to the extracellular matrix. Cellular debris and leukocytes persisted in the muscle of ptx3-deficient mice for a long time after wild-type animals had healed. ptx3-deficient macrophages expressed receptors involved in apoptotic cell clearance and engulfed dead cells in vitro. Accumulation of cell debris in a pro-inflammatory microenvironment was not sufficient to elicit autoantibodies.

CONCLUSION

PTX3 generated in response to muscle injury prompts the clearance of debris and the termination of the inflammatory response.

Innate immunity, hemostasis and matrix remodeling: PTX3 as a link

Innate immunity is evolutionarily connected with hemostasis. PTX3 is an essential fluid-phase pattern recognition molecule of the innate immune system that acts as a functional ancestor of antibodies. PTX3 by interacting with defense collagens and fibrinogens amplifies effector functions of the innate immune system. At wound sites, PTX3 regulates the injury-induced thrombotic response and promotes wound healing by favoring timely fibrinolysis. Therefore, PTX3 interacts with ancestral domains conserved in innate immunity, hemostasis and extracellular matrix and exerts functions related to both antimicrobial resistance and tissue repair. These findings strengthen the connection between innate immune system and hemostasis, and suggest that recognition of microbes and extracellular matrix are evolutionarily conserved and integrated functions of the innate immune system.