A GLP-2 Analogue Protects SH-SY5Y and Neuro-2a Cells Against Mitochondrial Damage, Autophagy Impairments and Apoptosis in a Parkinson Model

Evolution and therapeutic potential of glucagon-like peptide 2 analogs

Glucagon-like peptide 2 (GLP-2) is a proglucagon-derived peptide released by intestinal endocrine cells. However, its therapeutic potential is limited by rapid inactivation via dipeptidyl peptidase-IV. The elucidation of three-dimensional structures of G-protein-coupled receptors, including GLP-2 receptor, has facilitated the rational design of novel peptide therapeutics. Recent studies have explored various structural modifications based on the structure of GLP-2, such as amino acid substitution, lipidation, and fusion with proteins, to extend the half-life of GLP-2 and enhance its biological activity. One promising avenue involves the development of multifunctional molecules targeting multiple pharmacological systems to boost therapeutic efficacy. This paper reviews the recent advancements in understanding GLP-2, including its physiological roles and structure-activity relationships, and evaluates the development prospects of GLP-2 analogs.

Proteomic analysis and experimental validation reveal the blood-brain barrier protective of Huanshaodan in the treatment of SAMP8 mouse model of Alzheimer's disease

BACKGROUND

Huanshaodan (HSD) is a Chinese Herbal Compound which has a definite clinical effect on Alzheimer's disease (AD), however, the underlying mechanism remains unclear. The aim of this study is to preliminarily reveal the mechanism of HSD in the treatment of AD model of SAMP8 mice.

METHODS

Chemical composition of HSD and its drug-containing serum were identified by Q-Orbitrap high resolution liquid mass spectrometry. Six-month-old SAMP8 mice were treated with HSD and Donepezil hydrochloride by gavage for 2 months, and Wogonin for 28 days. Behavioral test was performed to test the learning and memory ability of mice. Immunofluorescence (IF) or Western-blot methods were used to detect the levels of pSer404-tau and β-amyloid (Aβ) in the brain of mice. Hematoxylin-eosin (H&E) staining and Transmission electron microscopy (TEM) assay was applied to observe the pathological changes of neurons. Proteomic technology was carried out to analyze and identify the protein network of HSD interventions in AD. Then the pathological process of the revealed AD-related differential proteins was investigated by IF, Q-PCR, Western-blot, Fluorescence in situ hybridization (FISH) and 16S rRNA sequencing methods.

RESULTS

The results showed that HSD and Wogonin, one of the components in its drug-containing serum, can effectively improve the cognitive impairments of SAMP8 mice, protect hippocampal neurons and synapses, and reduce the expression of pSer404-tau and Aβ. HSD and Wogonin reduced the levels of fibrinogen β chain (FGB) and γ chain (FGG), the potential therapeutic targets revealed by proteomics analysis, reduced the colocalization of FGB and FGG with Aβ, ionized calcium binding adaptor molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), increased level of and myelin basic protein (MBP). Meanwhile, HSD and Wogonin increased ZO-1 and Occludin levels, improved brain microvascular injury, and reduced levels of bacteria/bacterial DNA and lipopolysaccharide (LPS) in the brain of mice. In addition, 16S rRNA sequencing indicated that HSD regulated the structure of intestinal microbiota of mice.

CONCLUSION

The effects of HSD on AD may be achieved by inhibiting the levels of fibrinogen and the interactions on glia cells in the brain, and by modulating the structure of intestinal microbiota and improving the blood-brain barrier function.

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's

Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.

GLP-2 regulation of intestinal lipid handling

Lipid handling in the intestine is important for maintaining energy homeostasis and overall health. Mishandling of lipids in the intestine contributes to dyslipidemia and atherosclerotic cardiovascular diseases. Despite advances in this field over the past few decades, significant gaps remain. The gut hormone glucagon-like peptide-2 (GLP-2) has been shown to play pleotropic roles in the regulation of lipid handling in the intestine. Of note, GLP-2 exhibits unique actions on post-prandial lipid absorption and post-absorptive release of intestinally stored lipids. This review aims to summarize current knowledge in how GLP-2 regulates lipid processing in the intestine. Elucidating the mechanisms of GLP-2 regulation of intestinal lipid handling not only improves our understanding of GLP-2 biology, but also provides insights into how lipids are processed in the intestine, which offers opportunities for developing novel strategies towards prevention and treatment of dyslipidemia and atherosclerotic cardiovascular diseases.

2-Aminoethoxydiphenyl borate ameliorates mitochondrial dysfunctions in MPTP/MPP+ model of Parkinson's disease

Mitochondrial dysfunction is closely linked with the pathophysiology of several neurodegenerative disorders including Parkinson's disease (PD). Despite several therapeutic advancements related to symptomatic modification of PD pathology, strategies targeting mitochondrial dysfunctions remain largely elusive. Recently, transient receptor potential (TRP) channels have been shown to play a pivotal role in the control of mitochondrial and neuronal functioning in PD. In this study, the effect of 2-aminoethoxydiphenyl borate (2-APB), TRP channel blocker was investigated in the context of mitochondrial dysfunctions in 1-methyl-4-phenylpyridinium (MPP⁺)-treated SH-SY5Y cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-administered Sprague Dawley rats. MPP⁺-treated SH-SY5Y cells exhibited reductions in cell viability, generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential. Co-treatment with 2-APB led to an increase in cell viability, reduction in intracellular and mitochondrial ROS and improvement in mitochondrial membrane potential compared to MPP⁺-treated SH-SY5Y cells. In addition, intranigral administration of MPTP led to a significant reduction in motor function in the rats. Fourteen days of 2-APB (3 and 10 mg/kg, i.p.) treatment improved behavioural parameters. MPTP-induced decrease in complex I activity and mitochondrial potential were also blocked by 2-APB in the mitochondria isolated from the brain regions i.e. midbrain and striatum. MPTP-induced decrease in tyrosine hydroxylase levels were also restored by 2-APB. Moreover, MPTP-induced reduction in proteins involved in mitochondrial biogenesis, viz. peroxisome proliferator-activated-receptor-gamma coactivator and mitochondrial transcription factor-A were increased after 2-APB treatment in vivo. In summary, 2-APB has a promising neuroprotective role in the MPP⁺/MPTP models of PD via targeting mitochondrial dysfunctions and biogenesis.

Involvement of Intestinal Enteroendocrine Cells in Neurological and Psychiatric Disorders

Neurological and psychiatric patients have increased dramatically in number in the past few decades. However, effective treatments for these diseases and disorders are limited due to heterogeneous and unclear pathogenic mechanisms. Therefore, further exploration of the biological aspects of the disease, and the identification of novel targets to develop alternative treatment strategies, is urgently required. Systems-level investigations have indicated the potential involvement of the brain–gut axis and intestinal microbiota in the pathogenesis and regulation of neurological and psychiatric disorders. While intestinal microbiota is crucial for maintaining host physiology, some important sensory and regulatory cells in the host should not be overlooked. Intestinal epithelial enteroendocrine cells (EECs) residing in the epithelium throughout intestine are the key regulators orchestrating the communication along the brain-gut-microbiota axis. On one hand, EECs sense changes in luminal microorganisms via microbial metabolites; on the other hand, they communicate with host body systems via neuroendocrine molecules. Therefore, EECs are believed to play important roles in neurological and psychiatric disorders. This review highlights the involvement of EECs and subtype cells, via secretion of endocrine molecules, in the development and regulation of neurological and psychiatric disorders, including Parkinson’s disease (PD), schizophrenia, visceral pain, neuropathic pain, and depression. Moreover, the current paper summarizes the potential mechanism of EECs in contributing to disease pathogenesis. Examination of these mechanisms may inspire and lead to the development of new aspects of treatment strategies for neurological and psychiatric disorders in the future.

The neuropeptide landscape of human prefrontal cortex

The neuropeptide system encompasses the most diverse family of neurotransmitters, but their expression, cellular localization, and functional role in the human brain have received limited attention. Here, we study human postmortem samples from prefrontal cortex (PFC), a key brain region, and employ RNA sequencing and RNAscope methods integrated with published single-cell data. Our aim is to characterize the distribution of peptides and their receptors in 17 PFC subregions and to explore their role in chemical signaling. The results suggest that the well-established anatomical and functional heterogeneity of human PFC is also reflected in the expression pattern of the neuropeptides. Our findings support ongoing efforts from academia and pharmaceutical companies to explore the potential of neuropeptide receptors as targets for drug development.

Human prefrontal cortex (hPFC) is a complex brain region involved in cognitive and emotional processes and several psychiatric disorders. Here, we present an overview of the distribution of the peptidergic systems in 17 subregions of hPFC and three reference cortices obtained by microdissection and based on RNA sequencing and RNAscope methods integrated with published single-cell transcriptomics data. We detected expression of 60 neuropeptides and 60 neuropeptide receptors in at least one of the hPFC subregions. The results reveal that the peptidergic landscape in PFC consists of closely located and functionally different subregions with unique peptide/transmitter–related profiles. Neuropeptide-rich PFC subregions were identified, encompassing regions from anterior cingulate cortex/orbitofrontal gyrus. Furthermore, marked differences in gene expression exist between different PFC regions (>5-fold; cocaine and amphetamine–regulated transcript peptide) as well as between PFC regions and reference regions, for example, for somatostatin and several receptors. We suggest that the present approach allows definition of, still hypothetical, microcircuits exemplified by glutamatergic neurons expressing a peptide cotransmitter either as an agonist (hypocretin/orexin) or antagonist (galanin). Specific neuropeptide receptors have been identified as possible targets for neuronal afferents and, interestingly, peripheral blood-borne peptide hormones (leptin, adiponectin, gastric inhibitory peptide, glucagon-like peptides, and peptide YY). Together with other recent publications, our results support the view that neuropeptide systems may play an important role in hPFC and underpin the concept that neuropeptide signaling helps stabilize circuit connectivity and fine-tune/modulate PFC functions executed during health and disease.

EPOR/CD131-mediated attenuation of rotenone-induced retinal degeneration is associated with upregulation of autophagy genes

Mitochondrial dysfunction is a key driver of neurodegeneration. This study aimed to evaluate the protective potential of EPOR/CD131 (heterodimeric erythropoietin receptor) stimulation in the neurodegeneration caused by rotenone-induced mitochondrial dysfunction. The effects of erythropoietin (EPO) and an EPO mimetic peptide pHBSP were assessed using in vivo and in vitro models. Single injections of 10 µg/kg EPO or 5 µg/kg pHBSP significantly alleviated the degeneration of ganglion cells of the retina in a rotenone-induced retinopathy in rats (p < 0.05). Consistently, in vitro exposure of rotenone-treated murine primary neuroglial cultures to 500 nM EPO or pHBSP significantly rescued the survival of the cells (p < 0.005). The observed enhancement of LC3A, ATG7, Beclin-1, Parkin and BNIP3 mRNA expression by EPOR/CD131 agonists implicates the autophagy and mitophagy activation as a plausible mitoprotective mechanism.

Targeting Macroautophagy as a Therapeutic Opportunity to Treat Parkinson's Disease

Macroautophagy, an evolutionary conserved catabolic process in the eukaryotic cell, regulates cellular homeostasis and plays a decisive role in self-engulfing proteins, protein aggregates, dysfunctional or damaged organelles, and invading pathogens. Growing evidence from in vivo and in vitro models shows that autophagy dysfunction plays decisive role in the pathogenesis of various neurodegenerative diseases, including Parkinson's disease (PD). PD is an incurable and second most common neurodegenerative disease characterised by neurological and motor dysfunction accompanied of non-motor symptoms that can also reduce the life quality of patients. Despite the investment in research, the aetiology of the disease is still unknown and the therapies available are aimed mostly at ameliorating motor symptoms. Hence, therapeutics regulating the autophagy pathway might play an important role controlling the disease progression, reducing neuronal loss and even ameliorating non-motor symptoms. In this review, we highlight potential therapeutic opportunities involved in different targeting options like an initiation of autophagy, Leucine-rich repeat kinase 2 (LRRK2) inhibition, mitophagy, lysosomes, lipid metabolism, immune system, gene expression, biomarkers, and also non-pharmacological interventions. Thus, strategies to identify therapeutics targeting the pathways modulating autophagy might hold a future for therapy development against PD.

Gastrointestinal Dysfunction in Parkinson’s Disease: Current and Potential Therapeutics

Abnormalities in the gastrointestinal (GI) tract of Parkinson’s disease (PD) sufferers were first reported over 200 years ago; however, the extent and role of GI dysfunction in PD disease progression is still unknown. GI dysfunctions, including dysphagia, gastroparesis, and constipation, are amongst the most prevalent non-motor symptoms in PD. These symptoms not only impact patient quality of life, but also complicate disease management. Conventional treatment pathways for GI dysfunctions (i.e., constipation), such as increasing fibre and fluid intake, and the use of over-the-counter laxatives, are generally ineffective in PD patients, and approved compounds such as guanylate cyclase C agonists and selective 5-hyroxytryptamine 4 receptor agonists have demonstrated limited efficacy. Thus, identification of potential targets for novel therapies to alleviate PD-induced GI dysfunctions are essential to improve clinical outcomes and quality of life in people with PD. Unlike the central nervous system (CNS), where PD pathology and the mechanisms involved in CNS damage are relatively well characterised, the effect of PD at the cellular and tissue level in the enteric nervous system (ENS) remains unclear, making it difficult to alleviate or reverse GI symptoms. However, the resurgence of interest in understanding how the GI tract is involved in various disease states, such as PD, has resulted in the identification of novel therapeutic avenues. This review focuses on common PD-related GI symptoms, and summarizes the current treatments available and their limitations. We propose that by targeting the intestinal barrier, ENS, and/or the gut microbiome, may prove successful in alleviating PD-related GI symptoms, and discuss emerging therapies and potential drugs that could be repurposed to target these areas.

ACTH(6-9)PGP Peptide Protects SH-SY5Y Cells from H2O2, tert-Butyl Hydroperoxide, and Cyanide Cytotoxicity via Stimulation of Proliferation and Induction of Prosurvival-Related Genes

Stabilized melanocortin analog peptide ACTH(6-9)PGP (HFRWPGP) possesses a wide range of neuroprotective activities. However, its mechanism of action remains poorly understood. In this paper, we present a study of the proproliferative and cytoprotective activity of the adrenocorticotropic hormone fragment 6-9 (HFRW) linked with the peptide prolyine-glycyl-proline on the SH-SY5Y cells in the model of oxidative stress-related toxicity. The peptide dose-dependently protected cells from H2O2, tert-butyl hydroperoxide, and KCN and demonstrated proproliferative activity. The mechanism of its action was the modulation of proliferation-related NF-κB genes and stimulation of prosurvival NRF2-gene-related pathway, as well as a decrease in apoptosis.