Characterization of Hevin (SPARCL1) Immunoreactivity in Postmortem Human Brain Homogenates

Astrocytic Hevin/SPARCL-1 Regulates Cognitive Decline in Pathological and Normal Brain Aging

Dementia, characterized by loss of cognitive abilities in the elderly, poses a significant global health challenge. This study explores the role of astrocytes, one of most representative glial cells in the brain, in mitigating cognitive decline. Specifically, we investigated the impact of Hevin (also known as SPARC-like1/SPARCL-1), a secreted glycoprotein, on cognitive decline in both normal and pathological brain aging. By using adeno-associated viruses, we overexpressed Hevin in hippocampal astrocytes of middle-aged APP/PSEN mice, an established Alzheimer's disease (AD) model. Results demonstrated that Hevin overexpression attenuates cognitive decline, as evidenced by cognitive tests, increased pre- and postsynaptic markers colocalization, and altered expression of synaptic mediators, as revealed by proteomic profiling. Importantly, Hevin overexpression did not influence the deposition of Aβ plaques in the hippocampus, a hallmark of AD pathology. Furthermore, the study extended its findings to middle-aged wild-type animals, revealing improved cognitive performance following astrocytic Hevin overexpression. In conclusion, our results propose astrocytic Hevin as a potential therapeutic target for age-associated cognitive decline.

Glioma-derived SPARCL1 promotes the formation of peritumoral neuron-glioma synapses

PURPOSE

Gliomas are the most common type of primary malignant brain tumor with high degree of malignancy and rapid progression, and patients often have complications such as epilepsy and cognitive impairment. Thus, identifying related therapeutic targets, prolonging patient survival time and improving patient quality of life are urgently needed. Recent studies have shown that glutamatergic neurons around tumors and glioma cells form synapses, neuron-glioma synapses (NGSs), which have electrophysiological properties and participate in the proliferation, infiltration and invasion of tumors. Therefore, we aimed to explore the molecular mechanisms underlying NGS formation.

METHODS

We used bioinformatic analysis to screen for the expression of SPARCL1, which may play a role in promoting NGS formation, and we evaluated clinical samples through immunofluorescence, Western blot, and reverse transcriptase polymerase chain reaction (RT‒PCR) assays to validate the bioinformatic analysis results. Vitro neuron-glioma cell coculture model was established and allowed us to edit SPARCL1 expression in glioma cells, further allowing us to investigate the role of SPARCL1 in NGS formation.

RESULTS

Bioinformatic analysis revealed that SPARCL1 is highly expressed in glioma cells and is associated with synaptogenesis. Clinical samples were evaluated to verify the bioinformatics results, and SPARCL1 was found to be highly distributed in the tumor peripheral region. In the vitro neuron-glioma cell coculture model, NGSs were clearly observed, and SPARCL1 overexpression promoted NGS formation.

CONCLUSION

Taken together, these findings suggest that SPARCL1 is one of the molecules that promotes NGS formation in the tumor peripheral region.

In need of a specific antibody against the oxytocin receptor for neuropsychiatric research: A KO validation study

Antibodies are one of the most utilized tools in biomedical research. However, few of them are rigorously evaluated, as there are no accepted guidelines or standardized methods for determining their validity before commercialization. Often, an antibody is considered validated if it detects a band by Western blot of the expected molecular weight and, in some cases, if blocking peptides result in loss of staining. Neither of these approaches are unquestionable proof of target specificity. Since the oxytocin receptor has recently become a popular target in neuropsychiatric research, the need for specific antibodies to be used in brain has arisen. In this work, we have tested the specificity of six commercially available oxytocin receptor antibodies, indicated by the manufacturers to be suitable for Western blot and with an available image showing the correct size band (45-55 KDa). Antibodies were first tested by Western blot in brain lysates of wild-type and oxytocin receptor knockout mice. Uterus tissue was also tested as control for putative differential tissue specificity. In brain, the six tested antibodies lacked target specificity, as both wild-type and receptor knockout samples resulted in a similar staining pattern, including the expected 45-55 KDa band. Five of the six antibodies detected a selective band in uterus (which disappeared in knockout tissue). These five specific antibodies were also tested for immunohistochemistry in uterus, where only one was specific. However, when the uterine-specific antibody was tested in brain tissue, it lacked specificity. In conclusion, none of the six tested commercial antibodies are suitable to detect oxytocin receptor in brain by either Western blot or immunohistochemistry, although some do specifically detect it in uterus. The present work highlights the need to develop standardized antibody validation methods, including a proper negative control, in order to grant quality and reproducibility of the generated data.

Serum Secreted Protein Acidic and Rich in Cysteine-Like 1 as a Biochemical Predictor for Prognosticating Clinical Outcomes After Acute Supratentorial Intracerebral Hemorrhage: A Prospective Cohort Study

Background

Secreted protein acidic and rich in cysteine-like 1 (SPARCL1) regulates synaptic stability and is up-regulated during axonal regeneration. Here, serum SPARCL1 was determined for estimating severity and prognosticating early neurological deterioration (END) and functional outcomes of acute intracerebral hemorrhage (ICH).

Methods

In this prospective observational cohort study of 156 patients with supratentorial ICH, blood samples of 53 were acquired not only at admission but also ad days 1, 3, 5, 7 and 10. Another group of 53 healthy controls were recruited. The modified Rankin Scale (mRS) scores of 3-6 at poststroke six months were regarded as poor prognosis.

Results

As opposed to controls, serum SPARCL1 levels were markedly elevated during the early ten days after ICH, with the highest levels at days 1 and 3. Admission serum SPARCL1 levels were independently correlated with National Institutes of Health Stroke Scale scores and hematoma volume, were significantly increased in the order of six-month mRS scores from 0 to 6 and were independently correlated with six-month mRS scores. Serum SPARCL1 levels were linearly related to risks of poor six-month prognosis and END under restricted cubic spline, had significant efficiency under receiver operating characteristic (ROC) curve and were independently associated with END and poor prognosis. Subgroup analysis confirmed that no interactions existed for associations of serum SPARCL1 levels with other variables, such as age, gender and some specific vascular risk factors. END and poor prognosis prediction models integrating serum SPARCL1 were displayed using the two nomograms. The poor prognosis prediction model, but END prediction model not, performed well under calibration curve, decision curve and ROC curve.

Conclusion

A substantial elevation of serum SPARCL1 levels during the early period after ICH is independently related to illness severity and poor neurological outcomes, thus signifying that serum SPARCL1 may appear as a prognostic biomarker of ICH.

The Matricellular Protein Hevin Is Involved in Alcohol Use Disorder

Astrocytic-secreted matricellular proteins have been shown to influence various aspects of synaptic function. More recently, they have been found altered in animal models of psychiatric disorders such as drug addiction. Hevin (also known as Sparc-like 1) is a matricellular protein highly expressed in the adult brain that has been implicated in resilience to stress, suggesting a role in motivated behaviors. To address the possible role of hevin in drug addiction, we quantified its expression in human postmortem brains and in animal models of alcohol abuse. Hevin mRNA and protein expression were analyzed in the postmortem human brain of subjects with an antemortem diagnosis of alcohol use disorder (AUD, n = 25) and controls (n = 25). All the studied brain regions (prefrontal cortex, hippocampus, caudate nucleus and cerebellum) in AUD subjects showed an increase in hevin levels either at mRNA or/and protein levels. To test if this alteration was the result of alcohol exposure or indicative of a susceptibility factor to alcohol consumption, mice were exposed to different regimens of intraperitoneal alcohol administration. Hevin protein expression was increased in the nucleus accumbens after withdrawal followed by a ethanol challenge. The role of hevin in AUD was determined using an RNA interference strategy to downregulate hevin expression in nucleus accumbens astrocytes, which led to increased ethanol consumption. Additionally, ethanol challenge after withdrawal increased hevin levels in blood plasma. Altogether, these results support a novel role for hevin in the neurobiology of AUD.