L-alpha-aminoadipic acid restricts dopaminergic neurodegeneration and motor deficits in an inflammatory model of Parkinson's disease in male rats

Epigenetic and Metabolic Landscape of Dementia with Lewy Bodies

BACKGROUND

Lewy body diseases, including dementia with Lewy bodies (DLB), are characterized by α-synuclein accumulation, leading to dementia. Previous studies suggest distinct epigenetic and metabolomic profiles in DLB.

OBJECTIVE

This study aims to identify diagnostic biomarkers by analyzing the methylome and metabolome in the Brodmann area 7 of postmortem brain tissues from DLB patients and control subjects using multiomics approaches.

METHODS

Methylation analysis was performed using the Illumina EPIC array, and metabolomics profiling was conducted via 1H nuclear magnetic resonance (NMR) and direct injection/liquid chromatography coupled with mass spectrometry. Differential methylation and metabolite analysis were conducted, followed by pathway enrichment to explore biological relevance.

RESULTS

We identified 3478 significantly differentially methylated cytosines, mostly hypermethylated, enriched in CpG islands near transcription start sites. Pathway enrichment analysis showed significant pathways, primarily linked to olfactory and synaptic functions. Metabolomics profiling identified 15 significantly altered metabolites, with Phosphatidylethanolamine (PE) Biosynthesis being the most affected pathway. Key correlations between differentially methylated cytosines and metabolites, particularly in the PE Biosynthesis pathway involving PTDSS1 and PCYT2 genes, were observed.

CONCLUSIONS

Notably, sex-specific differences were found, with females exhibiting more epigenetic and metabolomic changes than males. Increased hypermethylation, linked to transcriptional silencing, and disruptions in PE biosynthesis suggest a role in synaptic dysfunction and olfactory deficits. In addition, α-aminoadipic acid was strongly associated with vascular functions, hinting at a possible overlap between vascular health and DLB. This study provides new insights into DLB mechanisms and potential therapeutic targets. © 2024 International Parkinson and Movement Disorder Society.

Aminoadipic acid aggravates atherosclerotic vascular inflammation through ROS/TXNIP/NLRP3 pathway, a harmful microbial metabolite reduced by paeonol

AIM

Our previous study has found a differential microbial metabolite in atherosclerosis (AS) mice, aminoadipic acid (AAA), which was considered as a potential harmful metabolite. However, whether it can promote AS vascular inflammation and its mechanisms remain unclear. Paeonol (Pae) plays an anti-AS role by regulating the metabolic profile, but whether Pae exerts its antiatherogenic effect by reducing serum AAA levels is unknown.

RESULTS

The clinical trial results showed that the AS patients' serum AAA levels were higher than those healthy people'. Besides, AAA supplementation could increase aortic plaque size, serum inflammatory cytokines levels and liver malondialdehyde, superoxide dismutase levels in AS mice. Moreover, after AAA stimulation, the ROS levels and ASC, TXNIP, NLRP3 and caspase-1 proteins levels were increased in HUVECs, which could be reversed by antioxidant NAC and NLRP3 inhibitor. Pae significantly reduced the plaque size in the aorta, improved blood lipid levels and decreased serum inflammation factor levels in AS mice. Simultaneously, Pae could reduce the serum AAA levels of AS mice through the gut microbiota transmission. Finally, Pae inhibited NLRP3 inflammasome activation in aortas of AS mice. Broad-spectrum antibiotics could weaken the inhibitory effect of Pae on NLRP3 inflammasome.

CONCLUSION

Our study clarified that AAA could promote AS vascular inflammation via activating the ROS/TXNIP/NLRP3 pathway. Pae could inhibit AS development by reducing serum AAA levels in a microbiota-dependent manner. Taken together, we proposed that AAA could be served as a potential biomarker for AS clinical diagnosis and provided a new treatment strategy for AS.

High preoperative blood oxaloacetate and 2-aminoadipic acid levels are associated with postoperative delayed neurocognitive recovery

Introduction

This study aimed to identify preoperative blood biomarkers related to development of delayed neurocognitive recovery (dNCR) following surgery.

Methods

A total of 67 patients (≥65 years old) who underwent head and neck tumor resection under general anesthesia were assessed using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Preoperative serum metabolomics were determined using widely targeted metabolomics technology.

Results

Of the 67 patients, 25 developed dNCR and were matched to 25 randomly selected patients from the remaining 42 without dNCR. Differential metabolites were selected using the criteria of variable importance in projection > 1.0 in orthogonal partial least squares discrimination analysis, false discovery rate <0.05, and fold-change >1.2 or <0.83 to minimize false positives. Preoperative serum levels of oxaloacetate (OR: 1.054, 95% CI: 1.027-1.095, P = 0.001) and 2-aminoadipic acid (2-AAA) (OR: 1.181, 95% CI: 1.087-1.334, P = 0.001) were associated with postoperative dNCR after adjusting for anesthesia duration, education, and age. Areas under the curve for oxaloacetate and 2-AAA were 0.86 (sensitivity: 0.84, specificity: 0.88) and 0.86 (sensitivity: 0.84, specificity: 0.84), respectively. High levels of preoperative oxaloacetate and 2-AAA also were associated with postoperative decreased MoCA (β: 0.022, 95% CI: 0.005-0.04, P = 0.013 for oxaloacetate; β: 0.077, 95%CI: 0.016-0.137, P = 0.014 for 2-AAA) and MMSE (β: 0.024, 95% CI: 0.009-0.039, P = 0.002 for oxaloacetate; β: 0.083, 95% CI: 0.032-0.135, P = 0.002 for 2-AAA) scores after adjusting for age, education level, and operation time.

Conclusion

High preoperative blood levels of oxaloacetate and 2-AAA were associated with increased risk of postoperative dNCR.

Clinical trial registration

https://classic.clinicaltrials.gov/ct2/show/NCT05105451, identifier NCT05105451.

Moquiniastrum polymorphum subsp. polymorphum extract inhibits the proliferation of an activated hepatic stellate cell line (GRX) by regulating the p27 pathway to generate cell cycle arrest

ETHNOPHARMACOLOGICAL RELEVANCE

The chosen plant and its extracts have been an alternative in the treatment of several inflammatory and oxidant diseases, and is therefore a viable option for the treatment of hepatic fibrosis.

AIM OF THE STUDY

This study aimed to use Moquiniastrum polymorphum subsp. polymorphum, mainly the ethanolic extract and fractions, in the treatment of hepatic fibrosis.

MATERIALS AND METHODS

Extracts were prepared from dried leaves in 100% ethanol (ET) and fractionated with an increased polarity solvent (dichloromethane to methanol). The quantification of compounds in the extracts was characterized by GCMS. The decrease in cell proliferation and the cytotoxicity of the extracts were evaluated together with the mechanisms of apoptosis and autophagy. The expression of genes associated with decreased fibrosis and cell cycle control was assessed and the production of lipid droplets was quantified by Oil Red O staining.

RESULTS

The experiments showed that treatment with ET and fraction 1 (F1) inhibited the expression of CDKIs (CCDN1, CDK2, CDK4 and CDK6) through an increase in p27, related to an increase in autophagic vesicles. The extract and F1 were able to decrease proliferation and revert the activated state of GRX cells to their quiescent state.

CONCLUSION

Our results suggest that extracts obtained from Moquiniastrum polymorphum subsp. polymorphum have a potential therapeutic effect against liver fibrosis.

Genetic Architecture of Plasma Alpha-Aminoadipic Acid Reveals a Relationship With High-Density Lipoprotein Cholesterol

Background Elevated plasma levels of alpha-aminoadipic acid (2-AAA) have been associated with the development of type 2 diabetes and atherosclerosis. However, the nature of the association remains unknown. Methods and Results We identified genetic determinants of plasma 2-AAA through meta-analysis of genome-wide association study data in 5456 individuals of European, African, and Asian ancestry from the Framingham Heart Study, Diabetes Prevention Program, Jackson Heart Study, and Shanghai Women's and Men's Health Studies. No single nucleotide polymorphisms reached genome-wide significance across all samples. However, the top associations from the meta-analysis included single-nucleotide polymorphisms in the known 2-AAA pathway gene DHTKD1, and single-nucleotide polymorphisms in genes involved in mitochondrial respiration (NDUFS4) and macrophage function (MSR1). We used a Mendelian randomization instrumental variable approach to evaluate relationships between 2-AAA and cardiometabolic phenotypes in large disease genome-wide association studies. Mendelian randomization identified a suggestive inverse association between increased 2-AAA and lower high-density lipoprotein cholesterol (P=0.005). We further characterized the genetically predicted relationship through measurement of plasma 2-AAA and high-density lipoprotein cholesterol in 2 separate samples of individuals with and without cardiometabolic disease (N=98), and confirmed a significant negative correlation between 2-AAA and high-density lipoprotein (rs=-0.53, P<0.0001). Conclusions 2-AAA levels in plasma may be regulated, in part, by common variants in genes involved in mitochondrial and macrophage function. Elevated plasma 2-AAA associates with reduced levels of high-density lipoprotein cholesterol. Further mechanistic studies are required to probe this as a possible mechanism linking 2-AAA to future cardiometabolic risk.

Therapeutic function of iPSCs-derived primitive neuroepithelial cells in a rat model of Parkinson's disease

Induced pluripotent stem cells (iPSCs) are a promising unlimited source for cell replacement therapy of neurodegenerative disorders, including Parkinson's disease (PD). In the present study, rat iPSCs-derived primitive neuroepithelial cells (RiPSCs-iNECs) were successfully induced from rat iPSCs (RiPSCs) following two major developmental stages, and could generate neurospheres and differentiated into both neurons and astrocytes in vitro. Then, the RiPSCs-iNECs-GFP⁺ were unilaterally transplanted into the right substantia nigra (SN) of 6-hydroxydopamine-lesioned rat models of PD. The results demonstrated that the grafted RiPSCs-iNECs could survive in parkinsonian rat brain for at least 150 days, and many of them differentiated into tyrosine hydroxylase (TH)-positive cells. Furthermore, the PD model rats grafted with RiPSCs-iNECs exhibited a significant functional recovery from their parkinsonian behavioral defects. Histological studies showed that RiPSCs-iNECs could differentiate into multiple types of neurons including dopaminergic neurons, GFAP, Pax6, FoxA2 and DAT-positive cells, and induced dopaminergic neurons extended dense neurites into the host striatum. Thus, iPSCs derived primitive neuroepithelial cells could be an attractive candidate as a source of donor material for the treatment of PD, but the molecular mechanism needs further clarification.

Therapeutic Potential of Astrocyte Transplantation

Cell transplantation is an attractive treatment strategy for a variety of brain disorders, as it promises to replenish lost functions and rejuvenate the brain. In particular, transplantation of astrocytes has come into light recently as a therapy for amyotrophic lateral sclerosis (ALS); moreover, grafting of astrocytes also showed positive results in models of other conditions ranging from neurodegenerative diseases of older age to traumatic injury and stroke. Despite clear differences in etiology, disorders such as ALS, Parkinson's, Alzheimer's, and Huntington's diseases, as well as traumatic injury and stroke, converge on a number of underlying astrocytic abnormalities, which include inflammatory changes, mitochondrial damage, calcium signaling disturbance, hemichannel opening, and loss of glutamate transporters. In this review, we examine these convergent pathways leading to astrocyte dysfunction, and explore the existing evidence for a therapeutic potential of transplantation of healthy astrocytes in various models. Existing literature presents a wide variety of methods to generate astrocytes, or relevant precursor cells, for subsequent transplantation, while described outcomes of this type of treatment also differ between studies. We take technical differences between methodologies into account to understand the variability of therapeutic benefits, or lack thereof, at a deeper level. We conclude by discussing some key requirements of an astrocyte graft that would be most suitable for clinical applications.

Involvement of Peroxiredoxin-3, Thioredoxin-2, and Protein Deglycase-1 in Cypermethrin-Induced Parkinsonism

Owing to its lipophilic nature, cypermethrin makes entry into the brain through the blood-brain barrier and causes severe damage to the nigrostriatal dopaminergic neurons after prolonged exposure. Following substantial accrual in the brain, cypermethrin induces the abnormal expression and accumulation of α-synuclein. Besides, cytochrome P450 2E1 (CYP2E1) causes free radical generation leading to lipid peroxidation in toxicant-induced parkinsonism. Conversely, 4-hydroxynonenal (4-HNE), a byproduct of lipid peroxidation, is known to contribute to neuronal damage. The current investigation aimed to explicate the participation of endogenous redox-sensitive proteins in cypermethrin-induced cellular and animal models of parkinsonism. The qualitative and quantitative expressions of selected redox-sensitive proteins were evaluated employing the standard procedures. Cypermethrin reduced the expression of peroxiredoxin 3 (Prx3), thioredoxin 2 (Trx2), and protein deglycase-1 (DJ-1). Knocking down of Prx3, Trx2, or DJ-1 further reduced the level of expression in the cypermethrin-treated group. Reduction in the expression of Prx3, Trx2, or DJ-1 was found to be associated with overexpression of α-synuclein and 4-HNE modification of proteins. Besides, cypermethrin increased the expression of CYP2E1, which was not altered after Prx3 or Trx2 knockdown. However, knocking down the DJ-1 augmented the level of CYP2E1 both in the cypermethrin-treated group and its respective control. The outcomes of the study demonstrate that cypermethrin reduces the level of Prx3, Trx2, and DJ-1 proteins. While the reduction in the expression of selected redox-sensitive proteins leads to α-synuclein overexpression and 4-HNE modification of proteins, DJ-1 attenuation is also linked with increased CYP2E1 expression, which in turn could lead to oxidative stress-mediated neuronal damage.

Isoforms of the DHTKD1-Encoded 2-Oxoadipate Dehydrogenase, Identified in Animal Tissues, Are not Observed upon the Human DHTKD1 Expression in Bacterial or Yeast Systems

Unlike the OGDH-encoded 2-oxoglutarate dehydrogenase (OGDH), which is an essential enzyme present in all animal tissues, expression of the DHTKD1-encoded isoenzyme, 2-oxoadipate dehydrogenase (OADH), depends on a number of factors, and mutant DHTKD1 phenotypes are rarely manifested. Physiological significance of OADH is also obscured by the fact that both isoenzymes transform 2-oxoglutarate and 2-oxoadipate. By analogy with other members of the 2-oxo acid dehydrogenases family, OADH is assumed to be a component of the multienzyme complex that catalyzes oxidative decarboxylation of 2-oxoadipate. This study aims at molecular characterization of OADH from animal tissues. Phylogenetic analysis of 2-oxo acid dehydrogenases reveals OADH only in animals and Dictyostelium discoideum slime mold, within a common branch with bacterial OGDH. Examination of partially purified animal OADH by immunoblotting and mass spectrometry identifies two OADH isoforms with molecular weights of about 130 and 70 kDa. These isoforms are not observed upon the expression of human DHTKD1 protein in either bacterial or yeast system, where the synthesized OADH is of expected molecular weight (about 100 kDa). Thus, the OADH isoforms present in animal tissues, may result from the animal-specific regulation of the DHTKD1 expression and/or posttranslational modifications of the encoded protein. Mapping of the peptides identified in the OADH preparations, onto the protein structure suggests that the 70-kDa isoform is truncated at the N-terminus, but retains the active site. Since the N-terminal domain of OGDH is required for the formation of the multienzyme complex, it is possible that the 70-kDa isoform catalyzes non-oxidative transformation of dicarboxylic 2-oxo acids that does not require the multienzyme structure. In this case, the ratio of the OADH isoforms in animal tissues may correspond to the ratio between the oxidative and non-oxidative decarboxylation of 2-oxoadipate.

Exposure to paraquat associated with periodontal disease causes motor damage and neurochemical changes in rats

Exposure to paraquat is possibly involved with the development of several conditions, including neurodegenerative diseases, such as Parkinson's disease (PD). This condition is mainly characterized by the loss of dopaminergic neurons in the nigrostriatal pathway and the development of classical motor symptoms. Etiology includes exposure to environmental factors, such as the paraquat exposure, and inflammatory diseases may exacerbate paraquat neurotoxicity. The aim of the study was to investigate whether the exposure to paraquat associated with the presence of periodontal disease is able to induce motor and biochemical changes in rats similar to that observed in PD. Adult male Wistar rats were sent to ligature. After 48 h, they were sent to daily treatment paraquat (1 mg/kg/day; 2 mL/kg; intragastric) or vehicle for 4 weeks. Twenty-four hours after the last administration, the open field test was performed. The rats were euthanized and the left hemimandibles and striatum were dissected for the analysis of dopaminergic and inflammatory markers. Only the combination of periodontal disease model plus paraquat exposure induced motor impairments. Remarkably, the paraquat exposure increased the ligature-induced alveolar bone loss in hemimandibles. Moreover, only the combination of periodontal disease and paraquat exposure induced the loss of dopaminergic neurons and astrocyte activation in the striatum.

Synthetic analogues of 2-oxo acids discriminate metabolic contribution of the 2-oxoglutarate and 2-oxoadipate dehydrogenases in mammalian cells and tissues

The biological significance of the DHTKD1-encoded 2-oxoadipate dehydrogenase (OADH) remains obscure due to its catalytic redundancy with the ubiquitous OGDH-encoded 2-oxoglutarate dehydrogenase (OGDH). In this work, metabolic contributions of OADH and OGDH are discriminated by exposure of cells/tissues with different DHTKD1 expression to the synthesized phosphonate analogues of homologous 2-oxodicarboxylates. The saccharopine pathway intermediates and phosphorylated sugars are abundant when cellular expressions of DHTKD1 and OGDH are comparable, while nicotinate and non-phosphorylated sugars are when DHTKD1 expression is order(s) of magnitude lower than that of OGDH. Using succinyl, glutaryl and adipoyl phosphonates on the enzyme preparations from tissues with varied DHTKD1 expression reveals the contributions of OADH and OGDH to oxidation of 2-oxoadipate and 2-oxoglutarate in vitro. In the phosphonates-treated cells with the high and low DHTKD1 expression, adipate or glutarate, correspondingly, are the most affected metabolites. The marker of fatty acid β-oxidation, adipate, is mostly decreased by the shorter, OGDH-preferring, phosphonate, in agreement with the known OGDH dependence of β-oxidation. The longest, OADH-preferring, phosphonate mostly affects the glutarate level. Coupled decreases in sugars and nicotinate upon the OADH inhibition link the perturbation in glucose homeostasis, known in OADH mutants, to the nicotinate-dependent NAD metabolism.

GC-MS based metabolomic profiling of lung tissue couple with network pharmacology revealed the possible protection mechanism of Pudilan Xiaoyan Oral Liquid in LPS-induced lung injury of mice

Pudilan Xiaoyan Oral Liquid (PDL) originated from "Pudilan" Classic Recipe of traditional Chinese medicine is one kind of anti-inflammatory Chinese patent medicine recorded in Chinese Pharmacopeia. PDL has been used clinically for treating inflammatory diseases of the respiratory tract. However, due to the complex composition of PDL, its potential anti-inflammation and the mechanism remain unknown. To identify the mechanism of the PDL in the treatment of lipopolysaccharide (LPS)-induced lung injury of mice. The mice models of lung injury were established and the changes of biochemical indices in serum and histopathology were detected to explore the effects of PDL. The approach of GC-MS metabolomics was used to find more significant metabolites, and the metabolic pathways were enriched through MetaboAnalyst. Then network analysis was applied to visualize the protein related to the important metabolites, merging into a protein-metabolite network via Cytoscape. The treatment of PDL could attenuate LPS-induced histopathological damage of lung tissues, followed by reducing pro-inflammation mediators including IL-10, TNF-a and NF-ĸB in serum. 11 potential metabolites were identified in lung tissue through metabolomics, which were significantly regulated to recover by PDL treatment. The correlated network was constructed by integrating potential metabolites and pathways. Aspartate and l-cysteine were selected as key metabolites and correlated proteins such as IL4I1 and ASPA were speculated as the potential target to treat LPS-induced lung injury using PDL. These results demonstrated that PDL might prevent the pathological process of lung injury through regulating the disturbed protein-metabolite network.