Fetuin-A protein distribution in mature inflamed and ischemic brain tissue

Astrocyte modulation in cerebral ischemia-reperfusion injury: A promising therapeutic strategy

Cerebral ischemia-reperfusion injury (CIRI) poses significant challenges for drug development due to its complex pathogenesis. Astrocyte involvement in CIRI pathogenesis has led to the development of novel astrocyte-targeting drug strategies. To comprehensively review the current literature, we conducted a thorough analysis from January 2012 to December 2023, identifying 82 drugs aimed at preventing and treating CIRI. These drugs target astrocytes to exert potential benefits in CIRI, and their primary actions include modulation of relevant signaling pathways to inhibit neuroinflammation and oxidative stress, reduce cerebral edema, restore blood-brain barrier integrity, suppress excitotoxicity, and regulate autophagy. Notably, active components from traditional Chinese medicines (TCM) such as Salvia miltiorrhiza, Ginkgo, and Ginseng exhibit these important pharmacological properties and show promise in the treatment of CIRI. This review highlights the potential of astrocyte-targeted drugs to ameliorate CIRI and categorizes them based on their mechanisms of action, underscoring their therapeutic potential in targeting astrocytes.

Interorgan communication with the liver: novel mechanisms and therapeutic targets

The liver is a multifunctional organ that plays crucial roles in numerous physiological processes, such as production of bile and proteins for blood plasma, regulation of blood levels of amino acids, processing of hemoglobin, clearance of metabolic waste, maintenance of glucose, etc. Therefore, the liver is essential for the homeostasis of organisms. With the development of research on the liver, there is growing concern about its effect on immune cells of innate and adaptive immunity. For example, the liver regulates the proliferation, differentiation, and effector functions of immune cells through various secreted proteins (also known as "hepatokines"). As a result, the liver is identified as an important regulator of the immune system. Furthermore, many diseases resulting from immune disorders are thought to be related to the dysfunction of the liver, including systemic lupus erythematosus, multiple sclerosis, and heart failure. Thus, the liver plays a role in remote immune regulation and is intricately linked with systemic immunity. This review provides a comprehensive overview of the liver remote regulation of the body's innate and adaptive immunity regarding to main areas: immune-related molecules secreted by the liver and the liver-resident cells. Additionally, we assessed the influence of the liver on various facets of systemic immune-related diseases, offering insights into the clinical application of target therapies for liver immune regulation, as well as future developmental trends.

Reduction of fetuin-A levels contributes to impairment of Purkinje cells in cerebella of patients with Parkinson's disease

Phenotypic features such as ataxia and loss of motor function, which are characteristics of Parkinson's disease (PD), are expected to be very closely related to cerebellum function. However, few studies have reported the function of the cerebellum. Since the cerebellum, like the cerebrum, is known to undergo functional and morphological changes due to neuroinflammatory processes, elucidating key functional factors that regulate neuroinflammation in the cerebellum can be a beneficial therapeutic approach. Therefore, we employed PD patients and MPTP-induced PD mouse model to find cytokines involved in cerebellar neuroinflammation in PD and to examine changes in cell function by regulating related genes. Along with the establishment of a PD mouse model, abnormal shapes such as arrangement and number of Purkinje cells in the cerebellum were confirmed based on histological finding, consistent with those of cerebellums of PD patients. As a result of proteome profiling for neuroinflammation using PD mouse cerebellar tissues, fetuin-A, a type of cytokine, was found to be significantly reduced in Purkinje cells. To further elucidate the function of fetuin-A, neurons isolated from cerebellums of embryos (E18) were treated with fetuin-A siRNA. We uncovered that not only the population of neuronal cells, but also their morphological appearances were significantly different. In this study, we found a functional gene called fetuin-A in the PD model's cerebellum, which was closely related to the role of cerebellar Purkinje cells of mouse and human PD. In conclusion, morphological abnormalities of Purkinje cells in PD mice and patients have a close relationship with a decrease of fetuin-A, suggesting that diagnosis and treatment of cerebellar functions of PD patients might be possible through regulation of fetuin-A. [BMB Reports 2023; 56(5): 308-313].

Association Between Human Blood Metabolome and the Risk of Psychiatric Disorders

BACKGROUND AND HYPOTHESIS

To identify promising drug targets for psychiatric disorders, we applied Mendelian randomization (MR) design to systematically screen blood metabolome for potential mediators of psychiatric disorders and further predict target-mediated side effects.

STUDY DESIGN

We selected 92 unique blood metabolites from 3 metabolome genome-wide association studies (GWASs) with totally 147 827 participants. Summary statistics for bipolar disorder (BIP), attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), major depressive disorder (MDD), schizophrenia (SCZ), panic disorder (PD), autistic spectrum disorder (ASD), and anorexia nervosa (AN) originated from the Psychiatric Genomics Consortium, involving 1 143 340 participants. Mendelian randomization (MR) analyses were conducted to estimate associations of blood metabolites with psychiatric disorders. Phenome-wide MR analysis was further performed to predict side effects mediated by metabolite-targeted interventions.

RESULTS

Eight metabolites were identified associated with psychiatric disorders, including five established mediators: N-acetylornithine (BIP: OR, 0.72 [95% CI, 0.66-0.79]; SCZ: OR, 0.74 [0.64-0.84]), glycine (BIP: OR, 0.62 [0.50-0.77]), docosahexaenoic acid (MDD: OR, 0.96 [0.94-0.97]), 3-Hydroxybutyrate (MDD: OR, 1.14 [1.08-1.21]), butyrylcarnitine (SCZ: OR, 1.22 [1.12-1.32]); and three novel mediators: 1-arachidonoylglycerophosphocholine (1-arachidonoyl-GPC)(BIP: OR, 0.31 [0.23-0.41]), glycoproteins (BIP: OR, 0.94 [0.92-0.97]), sphingomyelins (AN: OR, 1.12 [1.06-1.19]). Phenome-wide MR analysis showed that all identified metabolites except for N-acetylornithine and 3-Hydroxybutyrate had additional effects on nonpsychiatric diseases, while glycine, 3-Hydroxybutyrate, N-acetylornithine, and butyrylcarnitine had no adverse side effects.

CONCLUSIONS

This MR study identified five established and three novel mediators for psychiatric disorders. N-acetylornithine, glycine, 3-Hydroxybutyrate, and butyrylcarnitine might be promising targets against psychiatric disorders with no predicted adverse side effects.

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with CNS inflammation in children

Fetuin-A is a liver derived plasma protein showing highest serum concentrations in utero, preterm infants, and neonates. Fetuin-A is also present in cerebrospinal fluid (CSF). The origin of CSF fetuin-A, blood-derived via the blood-CSF barrier or synthesized intrathecally, is presently unclear. Fetuin-A prevents ectopic calcification by stabilizing calcium and phosphate as colloidal calciprotein particles mediating their transport and clearance. Thus, fetuin-A plays a suppressive role in inflammation. Fetuin-A is a negative acute-phase protein under investigation as a biomarker for multiple sclerosis (MS). Here we studied the association of pediatric inflammatory CNS diseases with fetuin-A glycosylation and phosphorylation. Paired blood and CSF samples from 66 children were included in the study. Concentration measurements were performed using a commercial human fetuin-A/AHSG ELISA. Of 60 pairs, 23 pairs were analyzed by SDS-PAGE following glycosidase digestion with PNGase-F and Sialidase-AU. Phosphorylation was analyzed in 43 pairs by Phos-TagTM acrylamide electrophoresis following alkaline phosphatase digestion. Mean serum and CSF fetuin-A levels were 0.30 ± 0.06 mg/ml and 0.644 ± 0.55 μg/ml, respectively. This study showed that serum fetuin-A levels decreased in inflammation corroborating its role as a negative acute-phase protein. Blood-CSF barrier disruption was associated with elevated fetuin-A in CSF. A strong positive correlation was found between the CSF fetuin-A/serum fetuin-A quotient and the CSF albumin/serum albumin quotient, suggesting predominantly transport across the blood-CSF barrier rather than intrathecal fetuin-A synthesis. Sialidase digestion showed increased asialofetuin-A levels in serum and CSF samples from children with neuroinflammatory diseases. Desialylation enhanced hepatic fetuin-A clearance via the asialoglycoprotein receptor thus rapidly reducing serum levels during inflammation. Phosphorylation of fetuin-A was more abundant in serum samples than in CSF, suggesting that phosphorylation may regulate fetuin-A influx into the CNS. These results may help establish Fetuin-A as a potential biomarker for neuroinflammatory diseases.

Tissue chaperoning—the expanded functions of fetuin-A beyond inhibition of systemic calcification

Traditionally, fetuin-A embodies the prototype anti-calcification protein in the blood, preventing cardiovascular calcification. Low serum fetuin-A is generally associated with mineralization dysbalance and enhanced mortality in end stage renal disease. Recent evidence indicates that fetuin-A is a crucial factor moderating tissue inflammation and fibrosis, as well as a systemic indicator of acute inflammatory disease. Here, the expanded function of fetuin-A is discussed in the context of mineralization and inflammation biology. Unbalanced depletion of fetuin-A in this context may be the critical event, triggering a vicious cycle of progressive calcification, inflammation, and tissue injury. Hence, we designate fetuin-A as tissue chaperone and propose the potential use of exogenous fetuin-A as prophylactic agent or emergency treatment in conditions that are associated with acute depletion of endogenous protein.

Exploring Molecular Mechanisms Involved in the Development of the Depression-Like Phenotype in Interleukin-18-Deficient Mice

Interleukin-18 (IL-18) is an inflammatory cytokine that has been linked to energy homeostasis and psychiatric symptoms such as depression and cognitive impairment. We previously revealed that deficiency in IL-18 led to hippocampal abnormalities and resulted in depression-like symptoms. However, the impact of IL-18 deficiency on other brain regions remains to be clarified. In this study, we first sought to confirm that IL-18 expression in neural cells can be found in human brain tissue. Subsequently, we examined the expression of genes in the prefrontal cortex of Il18^−/− mice and compared it with gene expression in mice subjected to a chronic mild stress model of depression. Extracted genes were further analyzed using Ingenuity® Pathway Analysis, in which 18 genes common to both the chronic mild stressed model and Il18^−/− mice were identified. Of those, 16 were significantly differentially expressed between Il18^+/+ and Il18^−/− mice. We additionally measured protein expression of α-2-HS-glycoprotein (AHSG) and transthyretin (TTR) in serum and the brain. In the prefrontal cortex of Il18^−/− mice, TTR but not AHSG was significantly decreased. Conversely, in the serum of Il18^−/− mice, AHSG was significantly increased but not TTR. Therefore, our results suggest that in IL-18-deficit conditions, TTR in the brain is one of the mediators causally related to depression, and AHSG in peripheral organs is one of the regulators inducing energy imbalance. Moreover, this study suggests a possible “signpost” to clarify the molecular mechanisms commonly underlying the immune system, energy metabolism, neural function, and depressive disorders.

The possible link between Fetuin-A Protein and Neuro-inflammation in Children with Autism Spectrum Disorder

Objectives

To investigate the blood plasma levels of Fetuin-A protein in children with Autism Spectrum Disorder (ASD) and healthy controls that could offer novel diagnostic biomarkers of disease development in ASD. Another objective was to investigate the severity of autistic children by Childhood Autism Rating Scale (CARS) and Short Sensory Profile (SSP).

Methods

This case control study was carried out at Autism Research and Treatment (ART) Center, King Saud University, Riyadh, Saudi Arabia, from October 2019 to February 2020. Plasma concentration of Fetuin-A was analyzed by enzyme-linked immunosorbent assay (ELISA) in ASD subjects (n=46) and normal controls (n=44). Correlation among Fetuin-A levels, CARS and SSP was established by Spearman's correlation coefficient (r).

Results

Overall, autistic children had significantly (p= 0.0.02) lower Fetuin-A concentration [50.76 (22.2-68.5) ng/ml] than those of healthy controls [53.7 (35.6-99.7) ng/ml] [median (interquartile range)]. Children with mild to moderate autism (n=24, 52%) also showed significantly lower Fetuin-A levels [50.0 (30.0-68.2) ng/ml], (p =0.02} than healthy controls [53.7 (35.6-99.7) ng/ml] [median (IQR)]. However, there was no significant change (p = 0.71) observed between the Fetuin-A levels of children with severe autism [51.8 (22.2-68.5)] ng/ml, mild to moderate autism [50 (30-68.2)] ng/ml [median (IQR)] and healthy controls (p=0.12). Also no significant correlations between Fetuin-A, CARS and SSP were observed (CARS, r= 0.024, p=0.88; SSP, r= -0.003, p=0.98).

Conclusion

Overall the low Fetuin-A plasma values in ASD subjects, most likely show that Fetuin-A could be associated in the physiology of autism. Further studies with larger patient and control cohorts will be necessary to determine whether Fetuin-A can be used as a biomarker for ASD.

Effects of Alpha-2-HS-glycoprotein on cognitive and emotional assessment in prediabetic and diabetic subjects

BACKGROUND

High concentrations of Alpha-2-HS-glycoprotein, also called Fetuin-A (Fet-A), are associated with insulin resistance, obesity, non-alcoholic fatty liver disease, type 2 diabetes and polycystic ovary syndrome. Moreover, Fet-A is able to cross the bloodbrain barrier into ischemic brain tissue in adult humans. Although the brain is an important target of insulin action, there is little evidence associating serum levels of Fet-A with psychiatric conditions such as depression and cognitive decline, and no reports about the presence and degree of anxiety disorders.

METHODS

We have examined cognitive and emotional alterations in a Caucasian population of 94 subjects.

RESULTS

Our data confirmed that, irrespective of insulin sensitivity status, circulating Fet-A levels are positively associated with an increased risk of showing signs of depression according to the BDI-II test, and have reported new evidences of a positive association between Fet-A and state- and trait- anxiety, as measured by the STAI questionnaires. In contrast, no association was observed between Fet-A levels and cognitive performance on the MMSE.

LIMITATIONS

Although the study includes a well-characterized population, the small sample size and cross sectional nature are important limitations, and this results should not be considered definitive. The data are based only on Caucasian subjects and their generalizability to other ethnic groups should be done with caution.

CONCLUSION

Overall, these data suggest for the first time a role of Fet-A as an independent risk factor in the development of symptoms of anxiety and depression in prediabetic and diabetic subjects.

Fetuin-A is a HIF target that safeguards tissue integrity during hypoxic stress

Intrauterine growth restriction (IUGR) is associated with reduced kidney size at birth, accelerated renal function decline, and increased risk for chronic kidney and cardiovascular diseases in adults. Precise mechanisms underlying fetal programming of adult diseases remain largely elusive and warrant extensive investigation. Setting up a mouse model of hypoxia-induced IUGR, fetal adaptations at mRNA, protein and cellular levels, and their long-term functional consequences are characterized, using the kidney as a readout. Here, we identify fetuin-A as an evolutionary conserved HIF target gene, and further investigate its role using fetuin-A KO animals and an adult model of ischemia-reperfusion injury. Beyond its role as systemic calcification inhibitor, fetuin-A emerges as a multifaceted protective factor that locally counteracts calcification, modulates macrophage polarization, and attenuates inflammation and fibrosis, thus preserving kidney function. Our study paves the way to therapeutic approaches mitigating mineral stress-induced inflammation and damage, principally applicable to all soft tissues.

Cytoplasmic aggregation of uranium in human dopaminergic cells after continuous exposure to soluble uranyl at non-cytotoxic concentrations

Uranium exposure can lead to neurobehavioral alterations in particular of the monoaminergic system, even at non-cytotoxic concentrations. However, the mechanisms of uranium neurotoxicity after non-cytotoxic exposure are still poorly understood. In particular, imaging uranium in neurons at low intracellular concentration is still very challenging. We investigated uranium intracellular localization by means of synchrotron X-ray fluorescence imaging with high spatial resolution (< 300 nm) and high analytical sensitivity (< 1 μg.g^-1 per 300 nm pixel). Neuron-like SH-SY5Y human cells differentiated into a dopaminergic phenotype were continuously exposed, for seven days, to a non-cytotoxic concentration (10 μM) of soluble natural uranyl. Cytoplasmic submicron uranium aggregates were observed accounting on average for 62 % of the intracellular uranium content. In some aggregates, uranium and iron were co-localized suggesting common metabolic pathways between uranium and iron storage. Uranium aggregates contained no calcium or phosphorous indicating that detoxification mechanisms in neuron-like cells are different from those described in bone or kidney cells. Uranium intracellular distribution was compared to fluorescently labeled organelles (lysosomes, early and late endosomes) and to fetuin-A, a high affinity uranium-binding protein. A strict correlation could not be evidenced between uranium and the labeled organelles, or with vesicles containing fetuin-A. Our results indicate a new mechanism of uranium cytoplasmic aggregation after non-cytotoxic uranyl exposure that could be involved in neuronal defense through uranium sequestration into less reactive species. The remaining soluble fraction of uranium would be responsible for protein binding and for the resulting neurotoxic effects.

Reduced plasma Fetuin-A is a promising biomarker of depression in the elderly

Depression affects 7% of the elderly population, and it often remains misdiagnosed or untreated. Peripheral biomarkers might aid clinicians by allowing more accurate and well-timed recognition of the disease. We sought to determine if plasma protein levels predict the severity of depressive symptomatology or distinguish patients from healthy individuals. The severity of depressive symptoms and global cognitive functioning were assessed by the Geriatric Depression Scale (GDS) and Mini-Mental State Examination (MMSE) in 152 elderly subjects, 76 of which with major depressive disorder (MDD). Plasma levels of 24 proteins were measured by multiplexing and analyzed as continuous predictors or dichotomized using the median value. The association between individual plasma proteins and MDD risk or depressive symptoms severity was investigated using multiple logistic and linear regressions including relevant covariates. Sensitivity analyses were performed excluding cognitively impaired individuals or non-acute patients with MDD. After adjusting for possible confounders and false discovery rate (FDR) correction, we found lower Fetuin-A levels in MDD patients vs. controls (p_FDR = 1.95 × 10^-6). This result was confirmed by the sensitivity and dichotomized analyses. Lower prolactin (PRL) levels predicted more severe depressive symptoms in acute MDD patients (p_FDR = 0.024). Fetuin-A is a promising biomarker of MDD in the elderly as this protein was negatively associated with the disorder in our sample, regardless of the global cognitive functioning. Lower PRL levels may be a peripheral signature of impaired neuroprotective processes and serotoninergic neurotransmission in more severely depressed patients.

Aging and Neuroinflammatory Disorders: New Biomarkers and Therapeutic Targets

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Chronic neuroinflammation is a common feature of the pathogenic mechanisms involved in various neurodegenerative age-associated disorders, such as Alzheimer's disease, multiple sclerosis, Parkinson’s disease, and dementia.

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In particular, persistent low-grade inflammation may disrupt the brain endothelial barrier and cause a significant increase of pro-inflammatory cytokines and immune cells into the cerebral tissue that, in turn, leads to microglia dysfunction and loss of neuroprotective properties.

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Nowadays, growing evidence highlights a strong association between persistent peripheral inflammation, as well as metabolic alterations, and neurodegenerative disorder susceptibility. The identification of common pathways involved in the development of these diseases, which modulate the signalling and immune response, is an important goal of ongoing research.

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The aim of this review is to elucidate which inflammation-related molecules are robustly associated with the risk of neurodegenerative diseases. Of note, peripheral biomarkers may represent direct measures of pathophysiologic processes common of aging and neuroinflammatory processes. In addition, molecular changes associated with the neurodegenerative process might be present many decades before the disease onset. Therefore, the identification of a comprehensive markers panel, closely related to neuroinflammation, could be helpful for the early diagnosis, and the identification of therapeutic targets to counteract the underlying chronic inflammatory processes.

Diagnostic Tests for Vascular Calcification

Vascular calcification (VC) is the heterogeneous endpoint of multiple vascular insults, which varies by arterial bed, the layer of the arterial wall affected, and is propagated by diverse cellular and biochemical mechanisms. A variety of in vivo and ex vivo techniques have been applied to the analysis of VC in preclinical studies, but clinical examination has principally relied on a number of noninvasive and invasive imaging modalities for detection and quantitation. Most imaging methods suffer from suboptimal spatial resolution, leading to the inability to distinguish medial from intimal VC and insufficient sensitivity to detect microcalcifications that are indicative of active mineral deposition and of vulnerable plaques which may be prone to rupture. Serum biomarkers lack specificity for VC and cannot discriminate pathology. Overall, uncertainties surrounding the sensitivity and specificity of different VC testing modalities, the absence of a clear cause-effect relationship, and lack of any evidence-based diagnostic or therapeutic protocols in relation to VC testing in chronic kidney disease has yielded weak or ungraded recommendations for their use in clinical practice. While VC is recognized as a key manifestation of chronic kidney disease-mineral and bone disorder and those with an increasing burden of VC are considered to be at higher cardiovascular risk, routine screening is not currently recommended.