Role of central nervous system periostin in cerebral ischemia

Ischemia does not provoke the full immune training repertoire in human cardiac fibroblasts

Trained immunity of monocytes, endothelial, and smooth muscle cells augments the cytokine response to secondary stimuli. Immune training is characterized by stabilization of hypoxia-inducible factor (HIF)-1α, mTOR activation, and aerobic glycolysis. Cardiac fibroblast (CF)-myofibroblast transition upon myocardial ischemia/reperfusion (I/R) features epigenetic and metabolic adaptations reminiscent of trained immunity. We assessed the impact of I/R on characteristics of immune training in human CF and mouse myocardium. I/R was simulated in vitro with transient metabolic inhibition. CF primed with simulated I/R or control buffer were 5 days later re-stimulated with Pam3CSK for 24 h. Mice underwent transient left anterior descending artery occlusion or sham operation with reperfusion for up to 5 days. HIF-regulated metabolic targets and cytokines were assessed by qPCR, immunoblot, and ELISA and glucose consumption, lactate release, and lactate dehydrogenase (LDH) by chromogenic assay. Simulated I/R increased HIF-1α stabilization, mTOR phosphorylation, glucose consumption, lactate production, and transcription of PFKB3 and F2RL3, a HIF-regulated target gene, in human CF. PGK1 and LDH mRNAs were suppressed. Intracellular LDH transiently increased after simulated I/R, and extracellular LDH showed sustained elevation. I/R priming increased abundance of pro-caspase-1, auto-cleaved active caspase-1, and the expression and secretion of interleukin (IL)-1β, but did not augment Pam3CSK-stimulated cytokine transcription or secretion. Myocardial I/R in vivo increased abundance of HIF-1 and the precursor and cleaved forms of caspase-1, caspase-11, and caspase-8, but not of LDH-A or phospho-mTOR. I/R partially reproduces features of immune training in human CF, specifically HIF-1α stabilization, aerobic glycolysis, mTOR phosphorylation, and PFKB3 transcription. I/R does not augment PGK1 or LDH expression or the cytokine response to Pam3CSK. Regulation of PAR4 and inflammasome caspases likely occurs independently of an immune training repertoire.

The Importance of Suppressing Pathological Periostin Splicing Variants with Exon 17 in Both Stroma and Cancer

BACKGROUND

Periostin (POSTN) is a type of matrix protein that functions by binding to other matrix proteins, cell surface receptors, or other molecules, such as cytokines and proteases. POSTN has four major splicing variants (PN1-4), which are primarily expressed in fibroblasts and cancer. We have reported that we should inhibit pathological POSTN (PN1-3), but not physiological POSTN (PN4). In particular, pathological POSTN with exon 17 is present in both stroma and cancer, but it is unclear whether the stroma or cancer pathological POSTN should be suppressed.

METHODS AND RESULTS

We transplanted 4T1 cells (breast cancer) secreting POSTN with exon 17 into 17KO mice lacking POSTN exon 17 to suppress stromal POSTN with exon 17. The results show that 17KO mice had smaller primary tumors and fewer metastases. Furthermore, to suppress cancer POSTN with exon 17, 4T1 cells transfected with POSTN exon 17 skipping oligo or control oligo were transplanted from the tail vein into the lungs. The results show that POSTN exon 17 skipping oligo significantly suppressed lung metastasis.

CONCLUSIONS

These findings suggest that it is important to suppress POSTN exon 17 in both stroma and cancer. Antibody targeting POSTN exon 17 may be a therapeutic candidate for breast cancer.

Single-nucleus and spatial transcriptomic profiling of human temporal cortex and white matter reveals novel associations with AD pathology

Alzheimer's disease (AD) is a neurodegenerative disorder with complex pathological manifestations and is the leading cause of cognitive decline and dementia in elderly individuals. A major goal in AD research is to identify new therapeutic pathways by studying the molecular and cellular changes in the disease, either downstream or upstream of the pathological hallmarks. In this study, we present a comprehensive investigation of cellular heterogeneity from the temporal cortex region of 40 individuals, comprising healthy donors and individuals with differing tau and amyloid burden. Using single-nucleus transcriptome analysis of 430,271 nuclei from both gray and white matter of these individuals, we identified cell type-specific subclusters in both neuronal and glial cell types with varying degrees of association with AD pathology. In particular, these associations are present in layer specific glutamatergic (excitatory) neuronal types, along with GABAergic (inhibitory) neurons and glial subtypes. These associations were observed in early as well as late pathological progression. We extended this analysis by performing multiplexed in situ hybridization using the CARTANA platform, capturing 155 genes in 13 individuals with varying levels of tau pathology. By modeling the spatial distribution of these genes and their associations with the pathology, we not only replicated key findings from our snRNA data analysis, but also identified a set of cell type-specific genes that show selective enrichment or depletion near pathological inclusions. Together, our findings allow us to prioritize specific cell types and pathways for targeted interventions at various stages of pathological progression in AD.

The Multiple Roles of Periostin in Non-Neoplastic Disease

Periostin, identified as a matricellular protein and an ECM protein, plays a central role in non-neoplastic diseases. Periostin and its variants have been considered to be normally involved in the progression of most non-neoplastic diseases, including brain injury, ocular diseases, chronic rhinosinusitis, allergic rhinitis, dental diseases, atopic dermatitis, scleroderma, eosinophilic esophagitis, asthma, cardiovascular diseases, lung diseases, liver diseases, chronic kidney diseases, inflammatory bowel disease, and osteoarthrosis. Periostin interacts with protein receptors and transduces signals primarily through the PI3K/Akt and FAK two channels as well as other pathways to elicit tissue remodeling, fibrosis, inflammation, wound healing, repair, angiogenesis, tissue regeneration, bone formation, barrier, and vascular calcification. This review comprehensively integrates the multiple roles of periostin and its variants in non-neoplastic diseases, proposes the utility of periostin as a biological biomarker, and provides potential drug-developing strategies for targeting periostin.

Serum Periostin May Help to Identify Patients with Poor Collaterals in the Hyperacute Phase of Ischemic Stroke

Background: Periostin is a glycoprotein that mediates cell functions in the extracellular matrix and appears to be a promising biomarker in neurological damage, such as ischemic stroke (IS). We aimed to measure serum periostin levels in the hyperacute phase of ischemic stroke to explore its predictive power in identification of patients with poor collaterals (ASPECT < 6). Methods: We prospectively enrolled 122 patients with acute ischemic stroke within the first 6 h after onset. The early ischemic changes were evaluated by calculating ASPECT score on admission using a native CT scan. An unfavorable outcome was defined as the modified Rankin Scale (mRS) > 2 at 90 days follow-up. Blood samples were collected on admission immediately after CT scan and periostin serum concentrations were determined by ELISA. Results: The admission concentration of serum periostin was significantly higher in patients with unfavorable outcome than in patients with favorable outcome (615 ng/L, IQR: 443−1070 vs. 390 ng/L, 260−563, p < 0.001). In a binary logistic regression model, serum periostin level was a significant predictor for ASPECT < 6 status on admission, within 6 h after stroke onset (OR, 5.911; CI, 0.990−0.999; p = 0.015). Conclusion: Admission periostin levels can help to identify patients who are not suitable for neurointervention, especially if advanced neuroimaging is not available.

The proteome of distal nerves: implication in delayed repair and poor functional recovery

Chronic denervation is one of the key factors that affect nerve regeneration. Chronic axotomy deteriorates the distal nerve stump, causes protein changes, and renders the microenvironment less permissive for regeneration. Some of these factors/proteins have been individually studied. To better delineate the comprehensive protein expression profiles and identify proteins that contribute to or are associated with this detrimental effect, we carried out a proteomic analysis of the distal nerve using an established delayed rat sciatic nerve repair model. Four rats that received immediate repair after sciatic nerve transection served as control, whereas four rats in the experimental group (chronic denervation) had their sciatic nerve repaired after a 12-week delay. All the rats were sacrificed after 16 weeks to harvest the distal nerves for extracting proteins. Twenty-five micrograms of protein from each sample were fractionated in SDS-PAGE gels. NanoLC-MS/MS analysis was applied to the gels. Protein expression levels of nerves on the surgery side were compared to those on the contralateral side. Any protein with a P value of less than 0.05 and a fold change of 4 or higher was deemed differentially expressed. All the differentially expressed proteins in both groups were further stratified according to the biological processes. A PubMed search was also conducted to identify the differentially expressed proteins that have been reported to be either beneficial or detrimental to nerve regeneration. Ingenuity Pathway Analysis (IPA) software was used for pathway analysis. The results showed that 709 differentially expressed proteins were identified in the delayed repair group, with a bigger proportion of immune and inflammatory process-related proteins and a smaller proportion of proteins related to axon regeneration and lipid metabolism in comparison to the control group where 478 differentially expressed proteins were identified. The experimental group also had more beneficial proteins that were downregulated and more detrimental proteins that were upregulated. IPA revealed that protective pathways such as LXR/RXR, acute phase response, RAC, ERK/MAPK, CNTF, IL-6, and FGF signaling were inhibited in the delayed repair group, whereas three detrimental pathways, including the complement system, PTEN, and apoptosis signaling, were activated. An available database of the adult rodent sciatic nerve was used to assign protein changes to specific cell types. The poor regeneration seen in the delayed repair group could be associated with the down-regulation of beneficial proteins and up-regulation of detrimental proteins. The proteins and pathways identified in this study may offer clues for future studies to identify therapeutic targets.

Periostin aggravates the early phase of traumatic brain injury via the MAPK/ERK pathway

OBJECTIVES

Periostin is found associated with trauma severity and mortality following head injury. In this study, the role and mechanism of periostin in the traumatic brain injury were investigated.

METHODS

Male Sprague-Dawley adult rats underwent sham or TBI modeling. Vehicle or recombinant periostin was administered intracerebroventricularly at 30 minutes post-TBI, and U0126, a specific MEK1/2 inhibitor, was administered intravenously at 30 minutes pre-TBI. Garcia neuroscore, limb function and brain water content assessments, as well as TUNEL and Western blotting assays were performed to evaluate the status of the above rats at 24 hours post-TBI. Finally, the motor test and Morris water maze test were performed to measure the effects of periostin and U0126 in the late phase of TBI.

RESULTS

Periostin expression significantly increased 24 hours post-TBI. Treatment with R-periostin aggravated post-TBI neurobehavioral impairment, brain edema, induced apoptosis and raised the quantity of phospho-p38, phospho-JNK, phospho-ERK and MMP-9, and lowered the expression of ZO-1. However, U0126, a kind of inhibitor of MEK, lowered the quantities of phospho-ERK and MMP-9, raised the expression of ZO-1, and suppressed apoptosis. U0126 also ameliorated the neurobehavioral impairments and brain edema induced by R-periostin. Additionally, U0126 didn't inhibit the expression of periostin in the early phase of TBI model. IU0126 was also able to ameliorate the pathological conditions in the late phase of TBI.

DISCUSSION

Periostin could aggravate neurobehavioral impairments and brain edema following TBI, and was involved in the early phase of TBI via the MAPK/ERK pathway.

First Admission Neutrophil-Lymphocyte Ratio May Indicate Acute Prognosis of Ischemic Stroke

OBJECTIVES

Our study aimed to determine the relationship between serum periostin levels, and the neutrophil-lymphocyte ratio (NLR) with ischemic stroke subtypes, clinical stroke scales, and acute prognosis in patients with acute ischemic stroke.

MATERIALS AND METHODS

Forty-two ischemic stroke patients and 39 age- and sex-matched healthy volunteers were included in our study. Demographic characteristics including age and gender were recorded. Blood serum periostin and NLR values were evaluated in the first 24 hours after admission. Serum periostin levels were compared with healthy controls of similar age and sex. Lesion localization was determined by cranial CT or diffusion MRI of the patients. Stroke scales were recorded on days 1 and 7 of hospitalization in the study group.

RESULTS

The mean serum periostin levels were higher than in the control group, but no statistically significant difference was found. There was no correlation between serum periostin levels and prognosis of stroke. First admission NLRs were statistically higher than in the control group. The first admission NLRs were positively correlated with the first admission National Institute of Health Stroke Scale score and the day 7 modified Rankin score.

CONCLUSION

Our study is the first study to evaluate both NLR and serum periostin levels in all types of acute ischemic stroke. While our study did not show that first admission serum periostin levels can be used as a biomarker in ischemic stroke, it did indicate that the first admission NLR can be used for acute prognosis of ischemic stroke.

Central Nervous System Fibroblast-Like Cells in Stroke and Other Neurological Disorders

Fibroblasts are the most common cell type of connective tissues. In the central nervous system (CNS), fibroblast-like cells are mainly located in the meninges and perivascular Virchow-Robin space. The origins of these fibroblast-like cells and their functions in both CNS development and pathological conditions remain largely unknown. In this review, we first introduce the anatomic location and molecular markers of CNS fibroblast-like cells. Next, the functions of fibroblast-like cells in CNS development and neurological disorders, including stroke, CNS traumatic injuries, and other neurological diseases, are discussed. Third, current challenges and future directions in the field are summarized. We hope to provide a synthetic review that stimulates future research on CNS fibroblast-like cells.

Periostin Short Fragment with Exon 17 via Aberrant Alternative Splicing Is Required for Breast Cancer Growth and Metastasis

BACKGROUND

Periostin (POSTN) is a 93 kDa matrix protein that helps to regulate collagen gene expression in the extracellular matrix. POSTN overexpression is a prognostic factor in malignant cancers; however, some researchers have observed it in the stroma, whereas others have reported it on tumors.

OBJECTIVE

This study aimed to investigate the function of POSTN on tumors.

METHODS AND RESULTS

We found that POSTN in cancer cells can be detected by using an antibody against the POSTN C-terminal region exon 17 (Ex17 antibody), but not with an antibody against the POSTN N-terminal region exon 12 (Ex12 antibody) in patients with breast cancer. In a fraction secreted from fibroblasts, LC-MS/MS analysis revealed a short fragment of POSTN of approximately 40 kDa with exon 17. In addition, molecular interaction analysis showed that POSTN with exon 17, but not POSTN without exon 17, bound specifically to wnt3a, and the Ex17 antibody inhibited the binding.

CONCLUSION

A short fragment of POSTN with exon 17, which originates in the fibroblasts, is transported to cancer cells, whereas POSTN fragments without exon 17 are retained in the stroma. The Ex17 antibody inhibits the binding between POSTN exon 17 and wnt3a.

Periostin Is Expressed by Pericytes and Is Crucial for Angiogenesis in Glioma

The expression of the matricellular protein periostin has been associated with glioma progression. In previous work we found an association of periostin with glioma angiogenesis. Here, we screen gliomas for POSTN expression and identify the cells that express periostin in human gliomas. In addition, we study the role of periostin in an in vitro model for angiogenesis. The expression of periostin was investigated by RT-PCR and by immunohistochemistry. In addition, we used double labeling and in situ RNA techniques to identify the expressing cells. To investigate the function of periostin, we silenced POSTN in a 3D in vitro angiogenesis model. Periostin expression was elevated in pilocytic astrocytoma and glioblastoma, but not in grade II/III astrocytomas and oligodendrogliomas. The expression of periostin colocalized with PDGFRβ+ cells, but not with OLIG2+/SOX2+ glioma stem cells. Silencing of periostin in pericytes in coculture experiments resulted in attenuation of the numbers and the length of the vessels formation and in a decrease in endothelial junction formation. We conclude that pericytes are the main source of periostin in human gliomas and that periostin plays an essential role in the growth and branching of blood vessels. Therefore, periostin should be explored as a novel target for developing anti-angiogenic therapy for glioma.

Decellularization optimizes the inhibitory microenvironment of the optic nerve to support neurite growth

Allogeneic or homologous tissue transplantation is an effective strategy to repair tissue injury. However, the central nervous tissues like the brain, spinal cord, and optic nerve are not ideal materials for nervous tissue regeneration due to the excessive axonal inhibitor cues in their microenvironments. In the present study, we found that decellularization optimizes the function of the adult optic nerve in supporting the oriented outgrowth of dorsal root ganglion (DRG) neurites. The neurites growing on the decellularized optic nerve (DON) showed longer extension distances than those growing on the normal optic nerve (ON). Neurite branching was also significantly increased on the DON compared to on the ON. Decellularization selectively removed some axon-inhibitory molecules such as myelin-associated glycoprotein (basically not detected in DON) and chondroitin sulfate proteoglycans (detected in DON at a level less than 0.3 fold that in ON) and preserved some axon-promoted extracellular matrix (ECM) proteins, including collagen IV and laminin (detected at levels 6.0-fold higher in DON than in ON). Furthermore, collagen IV and laminin were shown to be preserved in DON, and their binding activities with integrin α1 were retained to promote the extension of DRG neurites. Together, the findings provide a feasible way to optimize the axon-inhibited microenvironment of central nervous tissues and establish a theoretical basis for the application of DON scaffolds in repairing central nervous injury.

Upregulation of periostin in MOG-induced experimental autoimmune encephalomyelitis in mice

Periostin has dual roles as a multifunctional cytokine and an extracellular matrix protein that binds to several integrins on a variety of cells. This study evaluated whether the expression and cellular localization of periostin changes in the spinal cord of mice with experimental autoimmune encephalomyelitis (EAE), an animal model of human multiple sclerosis. Western blot analysis revealed that periostin was significantly upregulated in the spinal cord of EAE-induced mice in the effector stage, and did not significantly decrease in the recovery stage of EAE, compared with normal control. Periostin was constitutively detected in the neurons, ependymal cells, vascular endothelial cells, and astrocytes of normal mice. In the paralytic stage of EAE, periostin immunoreactivity was detected in some macrophages in the subarachnoid space (SAS), as well as in some microglial cells; in addition, periostin immunoreactivity was enhanced in astrocytes and vascular endothelial cells in EAE lesions. Collectively, these results suggest that periostin, either from monocyte-derived macrophages in SAS or glial cells in the parenchyma, partly facilitates the migration of inflammatory cells in the effector stage of EAE; moreover, periostin in the recovery stage of EAE appears to be involved in the plasticity of damaged central nervous system tissues.

Plasma Periostin and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a serious complication of aneurysmal subarachnoid hemorrhage (SAH). Matricellular protein periostin (POSTN) has been found to be upregulated and linked with early brain injury after experimental SAH. The aim of the present study was to investigate the relationship between plasma POSTN levels and various clinical factors including serum levels of C-reactive protein (CRP), an inflammatory marker, in 109 consecutive SAH patients whose POSTN levels were measured at days 1-12 after aneurysmal obliteration. DCI developed in 16 patients associated with higher incidence of angiographic vasospasm, cerebral infarction, and 90-day worse outcomes. POSTN levels peaked at days 4-6 before DCI development. Cerebrospinal fluid (CSF) drainage was associated with reduced POSTN levels, but did not influence CRP levels. There was no correlation between POSTN levels and other treatments or CRP levels. To predict DCI development, receiver-operating characteristic curves indicated that the most reasonable cutoff POSTN levels were obtained at days 1-3 in patients without CSF drainage (80.5 ng/ml; specificity, 77.6%; sensitivity, 85.7%). Multivariate analyses using variables obtained by day 3 revealed that POSTN level was an independent predictor of DCI. POSTN levels over the cutoff value were associated with higher incidence of DCI, but not angiographic vasospasm. This study shows for the first time that CSF drainage may reduce plasma POSTN levels, and that POSTN levels may increase prior to the development of DCI with and without vasospasm irrespective of systemic inflammatory reactions in clinical settings. These findings suggest POSTN as a new therapeutic molecular target against post-SAH DCI.

Attenuation of periostin in retinal Müller glia by TNF-α and IFN-γ

AIM

To investigate the regulation and mechanisms of periostin expression in retinal Müller glia, and to explore the relevance to retinal neovascularization.

METHODS

The oxygen-induced retinopathy (OIR) mouse model and the human Moorfield/Institute of Ophthalmology-Müller 1 (MIO-M1) cell line were used in the study. Immunofluorescence staining was used to determine the distribution and expression of periostin and a Müller glial cell marker glutamine synthetase (GS). Cytokines TNF-α and IFN-γ were added to stimulate the MIO-M1 cells. ShRNA was used to knockdown periostin expression in MIO-M1 cells. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) was conducted to assess the mRNA expression of periostin.

RESULTS

Immunofluorescence staining showed that periostin was expressed by MIO-M1 Müller glia. GS-positive Müller glia and periostin increased in OIR retinas, and were partially overlaid. The stimulation of TNF-α and IFN-γ reduced the mRNA expression of periostin significantly and dose-dependently in MIO-M1 cells. Knockdown of periostin reduced mRNA expression of vascular endothelial growth factor A (VEGFA) in MIO-M1 cells, while VEGFA expression was not changed in periostin knock-out OIR retinas.

CONCLUSION

Müller glia could be one of the main sources of periostin in the retina, and might contribute to the pathogenesis of retinal neovascularization. Proinflammatory cytokines TNF-α and IFN-γ attenuate the periostin expression in retinal Müller glia, which provides a potential and novel method in treating retinal neovascular diseases.

Practical Application of Periostin as a Biomarker for Pathological Conditions

In physiological condition, periostin is expressed in limited tissues such as periodontal ligament, periosteum, and heart valves. Periostin protein is mainly localized on extracellular collagen bundles and in matricellular space. On the other hand, in pathological condition, expression of periostin is induced in disordered tissues of human patients. In tumor development and progression, periostin is elevated mainly in its microenvironment and stromal tissue rich in extracellular matrix. Tumor stromal fibroblasts highly express periostin and organize the tumor-surrounding extracellular matrix architecture. In fibrosis in lung, liver, and kidney, proliferating activated fibroblasts express periostin and replace normal functional tissues with dense connective tissues. In inflammation and allergy, inflammatory cytokines such as IL-4 and IL-13 induce expression of periostin that plays important roles in pathogenesis of these diseases. The elevated levels of periostin in human patients could be detected not only in tissue biopsy samples but also in peripheral bloods using specific antibodies against periostin, because periostin secreted from the disordered tissues is transported into blood vessels and circulates in the cardiovascular system. In this chapter, I introduce the elevated expression of periostin in pathological conditions, and discuss how periostin could be utilized as a biomarker in disease diagnosis.

A Transcriptome Study of Progeroid Neurocutaneous Syndrome Reveals POSTN As a New Element in Proline Metabolic Disorder

Aging is a complex biological process. A study of pyrroline-5-carboxylate reductase 1 (PYCR1) deficiency, which causes a progeroid syndrome, may not only shed light on its genetic contribution to autosomal recessive cutis laxa (ARCL) but also help elucidate the functional mechanisms associated with aging. In this study, we used RNA-Seq technology to examine gene expression changes in primary skin fibroblasts from healthy controls and patients with PYCR1 mutations. Approximately 22 and 32 candidate genes were found to be up- and downregulated, respectively, in fibroblasts from patients. Among the downregulated candidates in fibroblasts with PYCR1 mutations, a strong reduction in the expression of 17 genes (53.1%) which protein products are localized in the extracellular space was detected. These proteins included several important ECM components, periostin (POSTN), elastin (ELN), and decorin (DCN); genetic mutations in these proteins are associated with different phenotypes of aging, such as cutis laxa and joint and dermal manifestations. The differential expression of ten selected extracellular space genes was further validated using quantitative RT-PCR. Ingenuity Pathway Analysis revealed that some of the affected genes may be associated with cardiovascular system development and function, dermatological diseases and conditions, and cardiovascular disease. POSTN, one of the most downregulated gene candidates in affected individuals, is a matricellular protein with pivotal functions in heart valvulogenesis, skin wound healing, and brain development. Perturbation of PYCR1 expression revealed that it is positively correlated with the POSTN levels. Taken together, POSTN might be one of the key molecules that deserves further investigation for its role in this progeroid neurocutaneous syndrome.

Longitudinal evaluation of serum periostin levels in patients after large-artery atherosclerotic stroke: A prospective observational study

Increasing evidence supports the involvement of periostin in the pathophysiological processes of stroke and atherosclerosis. The aim of this study was to assess circulating periostin levels at different times after large-artery atherosclerotic (LAA) stroke and their association with stroke. Serum periostin levels were measured using enzyme-linked immunosorbent assay on day 1 in 162 patients with LAA stroke and in 108 age- and sex-matched controls, on day 6 after stroke in 134 patients, and during the 4th week after stroke in 46 of the 162 patients. Stroke severity was determined using the National Institutes of Health Stroke Scale (NIHSS), and the stroke volume was measured. Outcome at 3 months was measured using the modified Rankin Scale (mRS). Our results indicated that periostin levels increased significantly on day 6 after stroke, and this increasing trend persisted for at least 4 weeks after the event. In addition, the increase in periostin levels was positively correlated with the NIHSS scores and stroke volume, but not with the mRS scores after adjusting for the NIHSS scores. In conclusion, these findings suggest that the increase in serum periostin levels observed after stroke may be associated with the stroke severity in patients with LAA stroke.

Increased concentration of serum periostin is associated with poor outcome of patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

To explore the role of serum periostin in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHOD

We conducted a retrospective study and 124 aSAH patients treated in Shenzhen People's hospital during March 1st 2015 to December 30th 2016 were included. Baseline information, neurological status and clinical outcome were recorded. Blood samples on admission were collected and enzyme linked immunosorbent assay (ELISA) kits were used to detect the serum level of periostin. Spearman's Correlation Analysis was used to analyze the correlation between periostin and clinical severity. Receiver operating characteristic (ROC) curve was performed to investigate variables' prognostic value in patients with aSAH.

RESULTS

The average age of patients included was 57.23 years old. Preliminary analysis revealed that serum periostin was significantly correlated with clinical severity. Patients with poor outcome at 12 months had higher level of periostin than patients with good outcome. Multivariate logistic regression analysis showed elevated level of periostin was significantly associated with poor outcome and the AUC was 0.85 for periostin in predicting poor outcome of patient with aSAH.

CONCLUSION

Elevated serum periostin concentrations are significantly associated with clinical severity and poor outcome of aSAH patients, which indicate serum periostin can be used as a prognostic biomarker in patients with aSAH.

Serum periostin concentrations and outcomes after severe traumatic brain injury

BACKGROUND

Periostin, a neurite outgrowth-promoting factor, is increasingly expressed in rat brain tissues after cerebral ischemia or subarachnoid hemorrhage. However, periostin concentrations are undetermined in peripheral blood from patients with traumatic brain injury (TBI).

METHODS

In this prospective, observational study, serum periostin concentrations were measured in 130 controls and 130 severe TBI patients. We investigated its association with trauma severity reflected by Glasgow Coma Scale (GCS) score and prognosis (i.e., 30-day mortality and 30-day overall survival).

RESULTS

As compared with the controls, serum periostin concentrations were significantly increased in the patients [(median, 246.5ng/ml; interquartile range, 164.5-328.6ng/ml) vs. (median, 61.8ng/ml; interquartile range, 37.9-77.9ng/ml), P<0.001]. Periostin concentrations independently correlated with GCS scores (t=-6.199, P<0.001). Serum periostin concentrations higher than 308.2ng/ml predicted 30-day mortality with a sensitivity of 72.4% and a specificity of 78.2% [area under curve, 815; 95% confidence interval (CI), 0.737-0.878]. Periostin concentrations higher than 246.5ng/ml were independently related to 30-day mortality and 30-day overall survival with odds ratio value of 3.829 (95% CI, 1.104-13.281) and hazard ratio value of 5.667 (95% CI, 1.953-16.443) respectively.

CONCLUSIONS

Increased serum periostin concentrations clearly reflect trauma severity and mortality following TBI.

Role of Periostin in Early Brain Injury After Subarachnoid Hemorrhage in Mice

BACKGROUND AND PURPOSE

A matricellular protein tenascin-C is implicated in early brain injury after experimental subarachnoid hemorrhage (SAH). This study first evaluated the role of another matricellular protein periostin and the relationships with tenascin-C in post-SAH early brain injury.

METHODS

Wild-type (n=226) and tenascin-C knockout (n=9) C57BL/6 male adult mice underwent sham or filament perforation SAH modeling. Vehicle, anti-periostin antibody, or recombinant periostin was randomly administrated by an intracerebroventricular injection at 30 minutes post-modeling. Neuroscores, SAH grading, brain water content, immunostaining, and Western blotting were blindly evaluated at 24 to 48 hours post-SAH.

RESULTS

Periostin was induced in brain capillary endothelial cells and neurons at 24 hours post-SAH. Anti-periostin antibody improved post-SAH neurobehavior, brain edema, and blood-brain barrier disruption associated with downregulation of tenascin-C, inactivation of p38, extracellular signal-related kinase 1/2 and matrix metalloproteinase-9, and subsequent preservation of zona occludens-1. Recombinant periostin aggravated post-SAH brain edema and tenascin-C induction. Tenascin-C knockout prevented post-SAH neurobehavioral impairments and periostin induction.

CONCLUSIONS

Periostin may cause post-SAH early brain injury through activating downstream signaling pathways and interacting with tenascin-C, providing a novel approach for the treatment of early brain injury.

Different roles played by periostin splice variants in retinal neovascularization

Retinal neovascularization (NV) due to retinal ischemia is one of the major causes of vision reduction in patients with different types of retinal diseases although anti-vascular endothelial growth factor (anti-VEGF) therapy can partially reduce the size of the retinal NV. We recently reported that periostin plays an important role in the development of NV and the formation of preretinal fibrovascular membranes, but the role of the splice variants of periostin on retinal NV has not been determined. We examined the expressions of periostin splice variants in the ischemic retinas of a mouse model of oxygen-induced retinal NV. We also studied the function of periostin splice variants on retinal NV using periostin knock out mice, and the effects of anti-periostin antibodies on retinal NV. Our results showed that the expressions of the periostin splice variants were increased in ischemic retinas. The degree of increase of periostin lacking exon 17 was the highest among the periostin splice variants examined. Both genetic ablation of periostin exons 17 and 21 and antibodies for periostin exons 17 and 21 affected preretinal pathological NV. Inhibition of exon 17 of periostin had the greatest effect in reducing preretinal pathological NV. These findings suggest a causal link between periostin splice variants and retinal NV, and an intravitreal injection of antibody for exon 17 and exon 21 of periostin should be considered to inhibit preretinal pathological NV.

Inhibition of TYRO3/Akt signaling participates in hypoxic injury in hippocampal neurons

In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.

Initial research on the relationship between let-7 family members in the serum and massive cerebral infarction

Eighty-eight ischemic stroke patients with massive cerebral infarction (MCI) who met our selection criteria were included in this study. MCI was assessed using the Glasgow Coma Scale (GCS) at hospital admission and at 2 weeks. The sera of all patients and controls were sampled at 48 h after the patients' attacks, and the sera of patients with MCI who had no severe cardiopulmonary complications, including those with hemorrhagic transformation (HT), were sampled again at 2 weeks. The relative expression of let-7 miRNA in the serum was determined by real-time qRT-PCR, and the blood levels of lipids, glucose, high-sensitivity C-reactive protein (hs-CRP), homocysteine and blood pressure were measured at admission. Interleukin-6 (IL-6) levels were detected by ELISA, and a luciferase assay was performed to confirm that IL-6 was a gene target of let-7. The relative expression of let-7f was significantly down-regulated in MCI without HT patients compared with controls (P<0.001), and it was positively correlated with GCS (P<0.01) and negatively correlated with hs-CRP (P<0.01). The relative expression of let-7f was significantly up-regulated in MCI patients with HT (P<0.01). IL-6 is a direct target gene for let-7f, and IL-6 expression was increased in MCI without HT patients compared to controls (P<0.01). The expression of let-7f in serum is associated with MCI without HT, which specifically inhibits IL-6. This suggests that let-7f may control inflammation in patients with MCI without HT.

Periostin Promotes Neural Stem Cell Proliferation and Differentiation following Hypoxic-Ischemic Injury

Neural stem cell (NSC) proliferation and differentiation are required to replace neurons damaged or lost after hypoxic-ischemic events and recover brain function. Periostin (POSTN), a novel matricellular protein, plays pivotal roles in the survival, migration, and regeneration of various cell types, but its function in NSCs of neonatal rodent brain is still unknown. The purpose of this study was to investigate the role of POSTN in NSCs following hypoxia-ischemia (HI). We found that POSTN mRNA levels significantly increased in differentiating NSCs. The proliferation and differentiation of NSCs in the hippocampus is compromised in POSTN knockout mice. Moreover, NSC proliferation and differentiation into neurons and astrocytes significantly increased in cultured NSCs treated with recombinant POSTN. Consistently, injection of POSTN into neonatal hypoxic-ischemic rat brains stimulated NSC proliferation and differentiation in the subventricular and subgranular zones after 7 and 14 days of brain injury. Lastly, POSTN treatment significantly improved the spatial learning deficits of rats subjected to HI. These results suggest that POSTN significantly enhances NSC proliferation and differentiation after HI, and provides new insights into therapeutic strategies for the treatment of hypoxic-ischemic encephalopathy.

Periostin, a neurite outgrowth-promoting factor, is expressed at high levels in the primate cerebral cortex

Periostin (POSTN or osteoblast specific factor) is an extracellular matrix protein originally identified as a protein highly expressed in osteoblasts. Recently, periostin has been reported to function in axon regeneration and neuroprotection. In the present study, we focused on periostin function in cortical evolution. We performed a comparative gene expression analysis of periostin between rodents (mice) and primates (marmosets and macaques). Periostin was expressed at higher levels in the primate cerebral cortex compared to the mouse cerebral cortex. Furthermore, we performed overexpression experiments of periostin in vivo and in vitro. Periostin exhibited neurite outgrowth activity in cortical neurons. These results suggested the possibility that prolonged and increased periostin expression in the primate cerebral cortex enhances the cortical plasticity of the mammalian cerebral cortex.

Astroglial-derived periostin promotes axonal regeneration after spinal cord injury

Traumatic spinal cord injury (SCI) results in a cascade of tissue responses leading to cell death, axonal degeneration, and glial scar formation, exacerbating the already hostile environment and further inhibiting axon regeneration. Overcoming these inhibitory cues and promoting axonal regeneration is one of the primary targets in developing a cure for SCI. Previously, we demonstrated that transplantation of bone morphogenetic protein (BMP)-induced astrocytes derived from embryonic glial-restricted precursors (GDAs(BMP)) promotes extensive axonal growth and motor function recovery in a rodent spinal cord injury model. Here, we identify periostin (POSTN), a secreted protein, as a key component of GDA(BMP)-induced axonal regeneration. POSTN is highly expressed by GDAs(BMP) and the perturbation of POSTN expression by shRNA diminished GDA(BMP)-induced neurite extension in vitro. We also found that recombinant POSTN is sufficient to overcome the inhibitory effect of scar-associated molecules and promote neurite extension in vitro by signaling through focal adhesion kinase and Akt. Furthermore, transplantation of POSTN-deficient GDAs(BMP) into the injured rat spinal cord resulted in compromised axonal regeneration, indicating that POSTN plays an essential role in GDA(BMP)-mediated axonal regeneration. This finding reveals not only one of the major mechanisms underlying GDA(BMP)-dependent recovery from SCI, but also the potential of POSTN as a therapeutic agent for traumatic injury of the CNS.

Long-term expression of periostin during the chronic stage of ischemic stroke in mice

Periostin is an extracellular matrix glycoprotein and has various cellular effects. Previously, we demonstrated the neuroprotective effects of periostin during the acute stage of cerebral ischemia. However, its expression during the chronic stage remains unknown. Herein, we examined the expression of full-length periostin (periostin 1; Pn1) and its splicing variant lacking exon 17 (periostin 2; Pn2) during the 28 days following transient middle cerebral artery occlusion in mice. Real-time reverse transcription-PCR showed that the expression of Pn2 was dramatically upregulated between days 3 and 28, and the highest expression was observed on day 7. The expression of Pn1 was also increased, but delayed compared with Pn2. Immunohistochemistry showed that periostin was weakly expressed in reactive astrocytes in the peri-infarct region and in microglia/macrophages in infarct regions, on days 3 and 7. Periostin was also expressed around CD31-positive cells in both the peri-infarct and the sub-ventricular zone (SVZ) on days 3 and 7. SOX-2 positive cells, which are neural stem cells, also expressed periostin on day 7. The highest periostin immunoreactivity that occurred co-localized with collagen I and fibronectin in the peri-infarct region between days 7 and 28. Thus, the expression pattern of periostin mRNA was dependent on the splicing variant, and it continued to be expressed up to 28 days after cerebral ischemia. As periostin was expressed in various cells, such as reactive astrocytes/microglia, fibroblasts and neuronal progenitor cells, periostin might be associated with pathophysiology in post-ischemic inflammation and neurogenesis.