Glial Cell Line-Derived Neurotrophic Factor and Focal Ischemic Stroke

Progress of Astrocyte-Neuron Crosstalk in Central Nervous System Diseases

Neurons are the primary cells responsible for information processing in the central nervous system (CNS). However, they are vulnerable to damage and insult in a variety of neurological disorders. As the most abundant glial cells in the brain, astrocytes provide crucial support to neurons and participate in synapse formation, synaptic transmission, neurotransmitter recycling, regulation of metabolic processes, and the maintenance of the blood-brain barrier integrity. Though astrocytes play a significant role in the manifestation of injury and disease, they do not work in isolation. Cellular interactions between astrocytes and neurons are essential for maintaining the homeostasis of the CNS under both physiological and pathological conditions. In this review, we explore the diverse interactions between astrocytes and neurons under physiological conditions, including the exchange of neurotrophic factors, gliotransmitters, and energy substrates, and different CNS diseases such as Alzheimer's disease, Parkinson's disease, stroke, traumatic brain injury, and multiple sclerosis. This review sheds light on the contribution of astrocyte-neuron crosstalk to the progression of neurological diseases to provide potential therapeutic targets for the treatment of neurological diseases.

Exploring Causal Relationships between Circulating Inflammatory Proteins and Thromboangiitis Obliterans: A Mendelian Randomization Study

BACKGROUND

 Thromboangiitis obliterans (TAO) is a vascular condition characterized by poor prognosis and an unclear etiology. This study employs Mendelian randomization (MR) to investigate the causal impact of circulating inflammatory proteins on TAO.

METHODS

 In this MR analysis, summary statistics from a genome-wide association study meta-analysis of 91 inflammation-related proteins were integrated with independently sourced TAO data from the FinnGen consortium's R10 release. Methods such as inverse variance weighting, MR-Egger regression, weighted median approaches, MR-PRESSO, and multivariable MR (MVMR) analysis were utilized.

RESULTS

 The analysis indicated an association between higher levels of C-C motif chemokine 4 and a reduced risk of TAO, with an odds ratio (OR) of 0.44 (95% confidence interval [CI]: 0.29-0.67; p = 1.4 × 10-4; adjusted p = 0.013). Similarly, glial cell line-derived neurotrophic factor exhibited a suggestively protective effect against TAO (OR: 0.43, 95% CI: 0.22-0.81; p = 0.010; adjusted p = 0.218). Conversely, higher levels of C-C motif chemokine 23 were suggestively linked to an increased risk of TAO (OR: 1.88, 95% CI: 1.21-2.93; p = 0.005; adjusted p = 0.218). The sensitivity analysis and MVMR revealed no evidence of heterogeneity or pleiotropy.

CONCLUSION

 This study identifies C-C motif chemokine 4 and glial cell line-derived neurotrophic factor as potential protective biomarkers for TAO, whereas C-C motif chemokine 23 emerges as a suggestive risk marker. These findings elucidate potential causal relationships and highlight the significance of these proteins in the pathogenesis and prospective therapeutic strategies for TAO.

The effect of inflammatory cytokines on the risk of hypertrophic scar: a mendelian randomization study

Hypertrophic scar (HS) results from burns or trauma, causing aesthetic and functional issues. However, observational studies have linked inflammatory cytokines to HS, but the causal pathways involved are unclear. We aimed to determine how circulating inflammatory cytokines contribute to HS formation. Two-sample Mendelian randomization (MR) was used to identify genetic variants associated with hypertrophic scar in a comprehensive, publicly available genome-wide association study (GWAS) involving 766 patients and 207,482 controls of European descent. Additionally, data on 91 plasma proteins were drawn from a GWAS summary involving 14,824 healthy participants. Causal relationships between exposures and outcomes were investigated primarily using the inverse variance weighted (IVW) method. Furthermore, a suite of sensitivity analyses, including MR‒Egger and weighted median approaches, were concurrently employed to fortify the robustness of the conclusive findings. Finally, reverse MR analysis was conducted to evaluate the plausibility of reverse causation between hypertrophic scar and the cytokines identified in our study. In inflammatory cytokines, there was evidence of inverse associations of osteoprotegerin(OPG) levels(OR = 0.59, 95% CI = 0.41 ∼ 0.85, p = 0.01), and leukemia inhibitory factor(LIF) levels(OR = 0.51, 95% CI = 0.32 ∼ 0.82, p = 0.01) are a nominally negative association with hypertrophic scar risk, while CUB domain-domain-containing protein 1(CDCP1) level(OR = 0.59, 95% CI = 0.41 ∼ 0.85, p = 0.01) glial cell line-derived neurotrophic factor(GDNF) levels(OR = 1.42, 95% CI = 1.03 ∼ 1.96, p = 0.01) and programmed cell death 1 ligand 1(PD-L1) levels(OR = 1.47, 95% CI = 1.92 ∼ 2.11, p = 0.04) showed a positive association with hypertrophic scar risk. These associations were similar in the sensitivity analyses. According to our MR findings, OPG and LIF have a protective effect on hypertrophic scar, while CDCP1, GDNF, and PD-L1 have a risk-increasing effect on Hypertrophic scar. Our study adds to the current knowledge on the role of specific inflammatory biomarker pathways in hypertrophic scar. Further validation is needed to assess the potential of these cytokines as pharmacological or lifestyle targets for hypertrophic scar prevention and treatment.

Astroglial Dysfunctions in Mood Disorders and Rodent Stress Models: Consequences on Behavior and Potential as Treatment Target

Astrocyte dysfunctions have been consistently observed in patients affected with depression and other psychiatric illnesses. Although over the years our understanding of these changes, their origin, and their consequences on behavior and neuronal function has deepened, many aspects of the role of astroglial dysfunction in major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) remain unknown. In this review, we summarize the known astroglial dysfunctions associated with MDD and PTSD, highlight the impact of chronic stress on specific astroglial functions, and how astroglial dysfunctions are implicated in the expression of depressive- and anxiety-like behaviors, focusing on behavioral consequences of astroglial manipulation on emotion-related and fear-learning behaviors. We also offer a glance at potential astroglial functions that can be targeted for potential antidepressant treatment.

Prophylactic zinc and therapeutic selenium administration in adult rats prevents long-term cognitive and behavioral sequelae by a transient ischemic attack

The transient hypoxic-ischemic attack, also known as a minor stroke, can result in long-term neurological issues such as memory loss, depression, and anxiety due to an increase in nitrosative stress. The individual or combined administration of chronic prophylactic zinc and therapeutic selenium is known to reduce nitrosative stress in the first seven days post-reperfusion and, due to an antioxidant effect, prevent cell death. Besides, zinc or selenium, individually administered, also causes antidepressant and anxiolytic effects. Therefore, this work evaluated whether combining zinc and selenium could prevent stroke-elicited cognition and behavior deficits after 30 days post-reperfusion. Accordingly, we assessed the expression of growth factors at 7 days post-reperfusion, a four-time course of memory (from 7 to 28 days post-learning test), and cell proliferation, depression, and anxiety-like behavior at 30 days post-reperfusion. Male Wistar rats with a weight between 190 and 240 g) were treated with chronic prophylactic zinc administration with a concentration of 0.2 mg/kg for 15 days before common carotid artery occlusion (10 min) and then with therapeutic selenium (6 μg/kg) for 7 days post-reperfusion. Compared with individual administrations, the administration combined of prophylactic zinc and therapeutic selenium decreased astrogliosis, increased growth factor expression, and improved cell proliferation and survival in two regions, the hippocampus, and cerebral cortex. These effects prevented memory loss, depression, and anxiety-like behaviors. In conclusion, these results demonstrate that the prophylactic zinc administration combined with therapeutic selenium can reduce the long-term sequelae caused by the transient ischemic attack. Significance statement. A minor stroke caused by a transient ischemic attack can result in psychomotor sequelae that affect not only the living conditions of patients and their families but also the economy. The incidence of these micro-events among young people has increased in the world. Nonetheless, there is no deep understanding of how this population group responds to regular treatments (Ekker and et al., 2018) [1]. On the basis that zinc and selenium have antioxidant, anti-inflammatory, and regenerative properties in stroke animal models, our work explored whether the chronic combined administration of prophylactic zinc and therapeutic selenium could prevent neurological sequelae in the long term in a stroke rat model of unilateral common carotid artery occlusion (CCAO) by 10-min. Our results showed that this combined treatment provided a long-term neuroprotective effect by decreasing astrogliosis, memory loss, anxiety, and depression-like behavior.

Expression levels and diagnostic value of serum GDNF, CEA and CA199 in patients with colorectal carcinoma

Background

To investigate the expression levels and diagnostic value of glial cell line-derived neurotrophic factor (GDNF), carcinoembryonic antigen (CEA) and carbohydrate antigen199 (CA199) in patients with colorectal carcinoma (CRC).

Methods

50 CRC patients at our hospital from Feb. 2020 to Feb. 2021 were chosen as the malignant group, another 50 patients with benign colonic diseases were chosen as the benign group, and 50 healthy people who came to our hospital for physical examination during the same period were considered as the control group. Fasting peripheral venous blood was taken from all research subjects in the morning and tested by a fully-automated electrochemiluminometer to determine the GDNF, CEA and CA199 levels. The sensitivity and specificity of the combined detection of the three indexes for CRC were analyzed, and the receiver operating characteristic (ROC) curve was plotted to record the area under the curve (AUC).

Results

The malignant group had remarkably higher CEA and CA199 levels (P<0.001) and a lower GDNF level (P<0.001) when compared with the benign and control groups. The sensitivity, specificity, positive predictive value and negative predictive value of the combined detection were 96.0%, 94.0%, 88.9% and 97.9%, respectively. Under combined detection, AUC (95% CI) = 0.950 (0.909-0.991), standard error = 0.021, and P<0.001.

Conclusions

The combined diagnosis of serum GDNF, CEA and CA199 is a reliable method to improve the diagnostic accuracy of CRC, and this strategy can effectively reduce the missed diagnosis rate and has high application value in clinic.

Astrocyte Regulation of Neuronal Function and Survival in Stroke Pathophysiology

The interactions between astrocytes and neurons in the context of stroke play crucial roles in the disease's progression and eventual outcomes. After a stroke, astrocytes undergo significant changes in their morphology, molecular profile, and function, together termed reactive astrogliosis. Many of these changes modulate how astrocytes relate to neurons, inducing mechanisms both beneficial and detrimental to stroke recovery. For example, excessive glutamate release and astrocytic malfunction contribute to excitotoxicity in stroke, eventually causing neuronal death. Astrocytes also provide essential metabolic support and neurotrophic signals to neurons after stroke, ensuring homeostatic stability and promoting neuronal survival. Furthermore, several astrocyte-secreted molecules regulate synaptic plasticity in response to stroke, allowing for the rewiring of neural circuits to compensate for damaged areas. In this chapter, we highlight the current understanding of the interactions between astrocytes and neurons in response to stroke, explaining the varied mechanisms contributing to injury progression and the potential implications for future therapeutic interventions.

Dense dopaminergic innervation of the peri-infarct cortex despite dopaminergic cell loss after a pure motor-cortical stroke in rats

After ischemic stroke, the cortex directly adjacent to the ischemic core (i.e., the peri-infarct cortex, PIC) undergoes plastic changes that facilitate motor recovery. Dopaminergic signaling is thought to support this process. However, ischemic stroke also leads to the remote degeneration of dopaminergic midbrain neurons, possibly interfering with this beneficial effect. In this study, we assessed the reorganization of dopaminergic innervation of the PIC in a rat model of focal cortical stroke. Adult Sprague-Dawley rats either received a photothrombotic stroke (PTS) in the primary motor cortex (M1) or a sham operation. 30 days after PTS or sham procedure, the retrograde tracer Micro Ruby (MR) was injected into the PIC of stroke animals or into homotopic cortical areas of matched sham rats. Thus, dopaminergic midbrain neurons projecting into the PIC were identified based on MR signal and immunoreactivity against tyrosine hydroxylase (TH), a marker for dopaminergic neurons. The density of dopaminergic innervation within the PIC was assessed by quantification of dopaminergic boutons indicated by TH-immunoreactivity. Regarding postsynaptic processes, expression of dopamine receptors (D1- and D2) and a marker of the functional signal cascade (DARPP-32) were visualized histologically. Despite a 25% ipsilesional loss of dopaminergic midbrain neurons after PTS, the number and spatial distribution of dopaminergic neurons projecting to the PIC was not different compared to sham controls. Moreover, the density of dopaminergic innervation in the PIC was significantly higher than in homotopic cortical areas of the sham group. Within the PIC, D1-receptors were expressed in neurons, whereas D2-receptors were confined to astrocytes. The intensity of D1- and DARPP-32 expression appeared to be higher in the PIC compared to the contralesional homotopic cortex. Our data suggest a sprouting of dopaminergic fibers into the PIC and point to a role for dopaminergic signaling in reparative mechanisms post-stroke, potentially related to recovery.

Total flavones of Rhododendron induce the transformation of A1/A2 astrocytes via promoting the release of CBS-produced H2S

BACKGROUND

We previously found that total flavones of Rhododendron (TFR) protected against the cerebral ischemia/reperfusion (I/R) injury. But the detailed mechanism is not clear. Recent research revealed that reactive astrocytes were divided into A1 and A2 phenotypes for their morphological and functional remodeling and neurotoxic- vs-neuroprotective effect on the injury of the central nervous system (CNS).

PURPOSE

The present study was undertaken to explore the role and mechanism of TFR on the phenotypic change of astrocytes following cerebral I/R in vivo and oxygen glucose deprivation/re-oxygenation (OGD/R) in vitro.

STUDY DESIGN AND METHODS

We tested the expression of astrocytes marker glial fibrillary acidic protein (GFAP), A1 astrocytes marker C3 protein and A2 astrocytes marker S100a10, as well as the BrdU/GFAP-positive cells, GFAP/S100a10-positive cells and GFAP/C3-positive cells in mice hippocampal tissues to evaluate the phenotypic change of astrocytes. Besides, we assessed the change of astrocyte phenotypes following OGD/R in vitro.

RESULTS

We found that mice cerebral I/R promoted the astrocytes proliferation of both A1 and A2 phenotypes in hippocampal tissues. While treatment with TFR could promote the proliferation of A2 astrocytes but inhibit the A1 astrocytes proliferation in mice hippocampal tissues, suggesting that TFR could accelerate the astrocytes transformation into A2 subtype following cerebral I/R. Whereas, in OGD/R model of astrocytes, we found that TFR inhibited the proliferation of both A1 and A2 astrocytes. Besides, we found that TFR could up-regulate the release of cystathionine β-synthase (CBS)-produced hydrogen sulfide (H₂S) and inhibit RhoA/Rho kinase pathway, and revealed that the inhibitory effect of TFR on astrocytes proliferation could be blocked by aminooxyacetic acid (AOAA), an CBS inhibitor. Furthermore, TFR could ameliorate the mice cerebral I/R injury and the OGD/R-induced astrocytic damage.

CONCLUSION

These findings suggested that TFR could affect the transformation of astrocytes subtypes following cerebral I/R, which may be related to up-regulation of CBS-produced H₂S and subsequent inhibition of RhoA/ROCK pathway.

m6A methylation: Critical roles in aging and neurological diseases

N6-methyladenosine (m6A) is the most abundant internal RNA modification in eukaryotic cells, which participates in the functional regulation of various biological processes. It regulates the expression of targeted genes by affecting RNA translocation, alternative splicing, maturation, stability, and degradation. As recent evidence shows, of all organs, brain has the highest abundance of m6A methylation of RNAs, which indicates its regulating role in central nervous system (CNS) development and the remodeling of the cerebrovascular system. Recent studies have shown that altered m6A levels are crucial in the aging process and the onset and progression of age-related diseases. Considering that the incidence of cerebrovascular and degenerative neurologic diseases increase with aging, the importance of m6A in neurological manifestations cannot be ignored. In this manuscript, we focus on the role of m6A methylation in aging and neurological manifestations, hoping to provide a new direction for the molecular mechanism and novel therapeutic targets.

Neurotrophic factor-based pharmacological approaches in neurological disorders

Aging is a physiological event dependent on multiple pathways that are linked to lifespan and processes leading to cognitive decline. This process represents the major risk factor for aging-related diseases such as Alzheimer's disease, Parkinson's disease, and ischemic stroke. The incidence of all these pathologies increases exponentially with age. Research on aging biology has currently focused on elucidating molecular mechanisms leading to the development of those pathologies. Cognitive deficit and neurodegeneration, common features of aging-related pathologies, are related to the alteration of the activity and levels of neurotrophic factors, such as brain-derived neurotrophic factor, nerve growth factor, and glial cell-derived neurotrophic factor. For this reason, treatments that modulate neurotrophin levels have acquired a great deal of interest in preventing neurodegeneration and promoting neural regeneration in several neurological diseases. Those treatments include both the direct administration of neurotrophic factors and the induced expression with viral vectors, neurotrophins' binding with biomaterials or other molecules to increase their bioavailability but also cell-based therapies. Considering neurotrophins' crucial role in aging pathologies, here we discuss the involvement of several neurotrophic factors in the most common brain aging-related diseases and the most recent therapeutic approaches that provide direct and sustained neurotrophic support.

Research progress on astrocyte autophagy in ischemic stroke

Ischemic stroke is a highly disabling and potentially fatal disease. After ischemic stroke, autophagy plays a key regulatory role as an intracellular catabolic pathway for misfolded proteins and damaged organelles. Mounting evidence indicates that astrocytes are strongly linked to the occurrence and development of cerebral ischemia. In recent years, great progress has been made in the investigation of astrocyte autophagy during ischemic stroke. This article summarizes the roles and potential mechanisms of astrocyte autophagy in ischemic stroke, briefly expounds on the crosstalk of astrocyte autophagy with pathological mechanisms and its potential protective effect on neurons, and reviews astrocytic autophagy-targeted therapeutic methods for cerebral ischemia. The broader aim of the report is to provide new perspectives and strategies for the treatment of cerebral ischemia and a reference for future research on cerebral ischemia.

The Influence of Neurotrophic Factors BDNF and GDNF Overexpression on the Functional State of Mice and Their Adaptation to Audiogenic Seizures

The high prevalence of diagnosed cases of severe neurological disorders, a significant proportion of which are epilepsy, contributes to a high level of mortality and disability in the population. Neurotrophic factors BDNF and GNDF are considered promising agents aimed at increasing the central nervous system's adaptive potential for the development of the epileptiform activity. Despite the pronounced neuroprotective and anticonvulsant potential, an appropriate way to stimulate these endogenous signaling molecules with minimal risk of side effects remains an open question. Herein, we assessed the safety of gene therapy using original adeno-associated viral constructs carrying the genes of neurotrophic factors BDNF and GDNF in the early postnatal period of development of experimental animals. The intraventricular injection of AAV-Syn-BDNF-eGFP and AAV-Syn-GDNF-eGFP viral constructs into newborn mice was found to provide persistent overexpression of target genes in the hippocampus and cerebral cortex in vivo for four weeks after injection. The application of viral constructs has a multidirectional effect on the weight and body length characteristics of mice in the early postnatal period; however, it ensures the animals' resistance to the development of seizure activity under audiogenic stimulation in the late postnatal period and preserves basic behavioral reactions, emotional status, as well as the mnestic and cognitive abilities of mice after simulated stress. Our results demonstrated the safety of using the AAV-Syn-BDNF-eGFP and AAV-Syn-GDNF-eGFP viral constructs in vivo, which indicates the expediency of further testing the constructs as therapeutic anticonvulsants.

Therapeutic potential of hair follicle-derived stem cell intranasal transplantation in a rat model of ischemic stroke

BACKGROUND

Stem cell-based therapy has received considerable attention as a potential candidate in the treatment of ischemic stroke; however, employing an appropriate type of stem cells and an effective delivery route are still challenging. In the present study, we investigated the therapeutic effect of safe, noninvasive, and brain-targeted intranasal administration of hair follicle-derived stem cells (HFSCs) in a rat model of ischemic stroke.

METHODS

Stem cells were obtained from the adult rat hair follicles. In experiment 1, stroke was induced by 30 min middle cerebral artery occlusion (MCAO) and stem cells were intranasally transplanted immediately after ischemia. In experiment 2, stroke was induced by 120 min MCAO and stem cells were administered 24 h after cerebral ischemia. In all experimental groups, neurological performance, short-term spatial working memory and infarct volume were assessed. Moreover, relative expression of major trophic factors in the striatum and cortex was evaluated by the quantitative PCR technique. The end point of experiment 1 was day 3 and the end point of experiment 2 was day 15.

RESULTS

In both experiments, intranasal administration of HFSCs improved functional performance and decreased infarct volume compared to the MCAO rats. Furthermore, NeuN and VEGF expression were higher in the transplanted group and stem cell therapy partially prevented BDNF and neurotrophin-3 over-expression induced by cerebral ischemia.

CONCLUSIONS

These findings highlight the curative potential of HFSCs following intranasal transplantation in a rat model of ischemic stroke.

Brain-Derived Neurotrophic Factor And Coronary Artery Disease

Coronary artery disease (CAD) is defined as myocardial damage developing as a result of its organic and functional changes, and leading to impaired blood flow through the coronary arteries. An important pathogenetic component of CAD is atherosclerosis. Currently, key aspects of the molecular relationship between inflammation and atherosclerosis are being actively studied, the immunometabolic theory of atherosclerosis is being discussed, along with an involvement of perivascular adipose tissue in the pathogenesis of this pathology, due to its ability to respond to atherogenic stimuli via developing inflammatory reactions. Evidence has been accumulated that in patients with CAD, both in their blood and perivascular adipose tissue, the level of neurotrophic factors (in particular, brain-derived neurotrophic factor, BDNF) changes, which may be a promising area of research from the standpoint of studying this factor as a therapeutic target for atherosclerosis in CAD. Neurotrophic growth factors control the functioning of both immune and nervous systems, and the balance of energy metabolism and innervation of adipose tissue. They affect vascular homeostasis, and are also involved in causing and stopping inflammation. Currently, there are data on the role of BDNF in the pathogenesis of cardiovascular, neurodegenerative and metabolic diseases, and on the effect of polyunsaturated fatty acids and eicosanoids on the level of BDNF and, accordingly, the development and progression of coronary artery atherosclerosis. Our review summarizes published data (2019-2021) on the pathophysiological and pathogenetic mechanisms of the relationship between BDNF and CAD (atherosclerosis).