Apolipoprotein D Research Articles

Apolipoprotein D3 and LOX product play a role in immune-priming of a lepidopteran insect, Spodoptera exigua

Immune-priming occurs in insects after a prior pathogen exposure. However, its underlying mechanism in insects remains elusive. In the present work, immune-priming was detected in a lepidopteran insect, Spodoptera exigua. Specifically, a prior infection with a heat-killed pathogenic bacterium, Escherichia coli, led to increased survival upon the second infection of different pathogens. Plasma collected from larvae with the prior infection possessed the immune-priming factor(s) that significantly up-regulated cellular and humoral immune responses of naïve larvae. Our study also finds that variations in the timing of plasma collection for priming larvae resulted in distinct impacts on both cellular and humoral responses. However, when the active plasma exhibiting the immune-priming was heat-treated, it lost this priming activity, therefore suggesting that protein factor(s) play a role in this immune-priming. An immunofluorescence assay showed that the hemocytes collected from the immune-primed larvae highly reacted to a polyclonal antibody specific to a vertebrate lipocalin, apolipoprotein D (ApoD). Among 27 ApoD genes (Se-ApoD1 ∼ Se-ApoD27) of S. exigua, Se-ApoD3 was found to be highly induced during the immune-priming, in which it was shown to be expressed in hemocytes and fat body from a fluorescence in situ hybridization analysis. RNA interference of Se-ApoD3 expression significantly impaired the immune-priming of S. exigua larvae. Moreover, the inhibition of eicosanoid biosynthesis suppressed the immune-priming, in which treatment with a lipoxygenase (LOX) inhibitor—and not treatment with a cyclooxygenase inhibitor—suppressed immune-priming. Further, an addition of LOX product such as lipoxin A4 or lipoxin B4 significantly rescued the lost immune-priming activity. Taken together, these results suggest that a complex of ApoD3 and LOX product mediates the immune-priming activity of S. exigua.

RNA interference confirmed a close association of CYP, ApD, and UCH with the function of CpG ODNs in Litopenaeus vannamei

CpG oligonucleotides (CpG ODNs) have been demonstrated to enhance the innate immune response in various organisms, including Litopenaeus vannamei, a species of significant economic importance. However, the precise mechanism or the genetic factors of CpG ODNs underlying function in L. vannamei remained elusive. Our previous experiment has identified five potential marker genes, including cytochrome P450 (CYP), gamma-butyrobetaine dioxygenase (γ-BDO), apolipoprotein D (ApD), prostaglandin reductase 1 (PGR1), and ubiquitin carboxyl-terminal hydrolase (UCH). In this study, RNA interference (RNAi) was employed to validate the relevance of these five genes in responding the stimulation of CpG ODNs. Briefly, shrimps were fed CpG ODNs and subsequently injected dsRNA targeting these five genes for interference. Finally, the non-specific immune parameters of shrimps, including the expression of immune-related genes and antioxidant capacity of hepatopancreas, as well as the mortality of shrimps after pathogen attack were assessed. The tissue distribution analysis revealed a high abundance of CYP in the hepatopancreas, γ-BDO in the hemocytes, ApD in the eyestalk, PGR1 in the hemocytes, and UCH in the gonad. After blocking CYP, ApD, and UCH through RNAi, a significant down-regulation of the mRNA expression levels of immune-related genes, including ALF, TNF-α, Toll, and TOR, was observed. Additionally, a notable decline in the activity of antioxidant enzymes, such as CAT, GPX, GST, and SOD, was also observed. Moreover, the mortality rates of shrimps in the CYP, ApD, and UCH inhibited groups significantly increased compared to other treatment groups following exposure to Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VpAHPND) and white spot syndrome virus (WSSV). These results collectively suggest a close association of CYP, ApD, and UCH with the function of CpG ODNs in shrimps which will provide significant theoretical insights into comprehending the mechanism of CpG ODNs and optimizing their practical application in shrimp's aquaculture.

Uncovering the potential of APOD as a biomarker in gastric cancer: A retrospective and multi-center study

Gastric cancer (GC) poses a significant health challenge worldwide, necessitating the identification of predictive biomarkers to improve prognosis. Dysregulated lipid metabolism is a well-recognized hallmark of tumorigenesis, prompting investigation into apolipoproteins (APOs). In this study, we focused on apolipoprotein D (APOD) following comprehensive analyses of APOs in pan-cancer. Utilizing data from the TCGA-STAD and GSE62254 cohorts, we elucidated associations between APOD expression and multiple facets of GC, including prognosis, tumor microenvironment (TME), cancer biomarkers, mutations, and immunotherapy response, and identified potential anti-GC drugs. Single-cell analyses and immunohistochemical staining confirmed APOD expression in fibroblasts within the GC microenvironment. Additionally, we independently validated the prognostic significance of APOD in the ZN-GC cohort. Our comprehensive analyses revealed that high APOD expression in GC patients was notably associated with unfavorable clinical outcomes, reduced microsatellite instability and tumor mutation burden, alterations in the TME, and diminished response to immunotherapy. These findings provide valuable insights into the potential prognostic and therapeutic implications of APOD in GC.

A Study of the Resistance of Hu Sheep Lambs to Escherichia coli F17 Based on Whole Genome Sequencing.

This study aims to analyze the whole genome sequencing of E. coli F17 in antagonistic and susceptible Hu sheep lambs. The objective is to investigate the critical mutation loci in sheep and understand the genetic mechanism of sheep resistance to E. coli F17 at the genome level. Antagonist and susceptible venous blood samples were collected from Hu sheep lambs for whole genome sequencing and whole genome association analysis. A total of 466 genes with significant SNPs (p < 1.0 × 10-3) were found. GO and KEGG enrichment analysis and protein interaction network analysis were performed on these genes, and preliminary investigations showed that SNPs on CTNNB1, CDH8, APOD, HCLS1, Tet2, MTSS1 and YAP1 genes may be associated with the antagonism and susceptibility of Hu sheep lambs to E. coli F17. There are still some shortcomings that have not been explored via in vivo and in vitro functional experiments of the candidate genes, which will be our next research work. This study provides genetic loci and candidate genes for resistance of Hu sheep lambs to E. coli F17 infection, and provides a genetic basis for breeding disease-resistant sheep.

APOD acts on fibroblast-like synoviocyte and chondrocyte to alleviate the process of osteoarthritis in vitro.

The pathogenesis of osteoarthritis (OA) is still unclear, leading to the lack of targeted treatment. We aimed to probe into the effect of apolipoprotein D (APOD), the key gene from our previous study through bioinformatics analysis, on fibroblast-like synoviocyte (FLS) and chondrocytes in vitro to confirm its potential roles on the delay of OA progression. Primary FLS and chondrocytes were extracted from synovium and cartilage of OA patients and stimulated with interleukin 1β (IL-1β) in vitro. After APOD intervention, viability and proliferation of FLS and chondrocytes were detected. Subsequently, the inflammatory factors of the two cells were detected by quantitative reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and western blot, and the apoptosis and autophagy-related substances were determined at the same time. Finally, the oxidation level in FLS and chondrocytes were detected. APOD reversed the change of gene expression stimulated by IL-1β in FLS and chondrocytes. APOD alleviated the proliferation of FLS while promoted proliferation of chondrocytes, and reduced the expression of inflammatory factors. Moreover, APOD promoted apoptosis of FLS and autography of chondrocytes, while reduced apoptosis of chondrocytes. Finally, decrease level of reactive oxygen species (ROS) in both cells were observed after APOD intervention, as well as the increased expression of antioxidant-related genes. APOD had effects on the proliferation of FLS and chondrocytes through apoptosis and autography as well as the reduction of oxidative stress, delaying the progress of OA.

P02.14.B SPATIAL TRANSCRIPTOMIC ARCHITECTURE OF TUMOURS OF THE PERIPHERAL NERVOUS SYSTEM

Abstract BACKGROUND Studies into the genetics of peripheral nerve tumors have been focused on their association with known gene mutations and syndromes as well as on the tumor microenvironment of malignant peripheral nerve sheath tumors. Still, not many advances have been made into clarifying the structure and diverse pathophysiology of these tumors. Here we present spatially resolved transcriptomic profiling of benign and malignant entities and describe the topographical architecture of the neoplastic and microenvironmental diversity. MATERIAL AND METHODS We employed spatially resolved transcriptomics using the 10X Visium technology from paraffine embedded specimens. We included hybrid peripheral nerve sheath tumors (HPNSTs) plexiform neurofibromas and malignant peripheral nerve sheath tumors (MPNST). Computational analysis was employed by the SPATA2 toolbox. Transcriptomic niches were identified by graph-based spatial clustering. Correlation of histomorphological features and transcriptomic programs was performed by a co-expression network-based analysis. RESULTS We identified hub genes associated with neurofibroma and schwannoma histopathology across primary pathologies and discovered that neurofibroma regions of HPNSTs exhibited unique transcriptional programs marked by a significant higher local accumulation of bone-derived macrophages and lymphoid cells compared to primary neurofibromas. A novel marker, Apolipoprotein D (APOD), was found to accurately identify neurofibroma subregions in HPNSTs, which was confirmed by immunostaining in a control cohort. In MPNSTs, we observed a high grade of inter- and intrapatient heterogeneity driven by unique transcriptional niches and genetic variability. Subsequent pathway analysis revealed distinct oncogenic signaling driver across regional niches along with variance in immune infiltration. Our findings highlight the disbalance between histological annotation and actual tumor cell abundance in MPNSTs indicated by inferred copy number alterations. CONCLUSION Our integrated analysis pipeline revealed distinct transcriptional signatures and cellular interactions within benign PNSTs, including neurofibromas and hybrid peripheral nerve sheath tumors (HPNSTs) and sought to expose the tumor heterogeneity of MPNST and identify various cancer niches. Our study underscores the potential of spatially resolved transcriptomics as a powerful tool for advancing our understanding of PNST biology, and ultimately improving diagnosis, prognosis, and treatment strategies.

The evolution and functional divergence of 10 Apolipoprotein D-like genes in Nilaparvata lugens.

Apolipoprotein D (ApoD), a member of the lipocalin superfamily of proteins, is involved in lipid transport and stress resistance. Whereas only a single copy of the ApoD gene is found in humans and some other vertebrates, there are typically several ApoD-like genes in insects. To date, there have been relatively few studies that have examined the evolution and functional differentiation of ApoD-like genes in insects, particularly hemi-metabolous insects. In this study, we identified 10 ApoD-like genes (NlApoD1-10) with distinct spatiotemporal expression patterns in Nilaparvata lugens (BPH), which is an important pest of rice. NlApoD1-10 were found to be distributed on 3 chromosomes in a tandem array of NlApoD1/2, NlApoD3-5, and NlApoD7/8, and show sequence and gene structural divergence in the coding regions, indicating that multiple gene duplication events occurred during evolution. Phylogenetic analysis revealed that NlApoD1-10 can be clustered into 5 clades, with NlApoD3-5 and NlApoD7/8 potentially evolving exclusively in the Delphacidae family. Functional screening using an RNA interference approach revealed that only NlApoD2 was essential for BPH development and survival, whereas NlApoD4/5 are highly expressed in testes, and might play roles in reproduction. Moreover, stress response analysis revealed that NlApoD3-5/9, NlApoD3-5, and NlApoD9 were up-regulated after treatment with lipopolysaccharide, H2 O2 , and ultraviolet-C, respectively, indicating their potential roles in stress resistance.

Apolipoprotein D in Oxidative Stress and Inflammation.

Apolipoprotein D (ApoD) is lipocalin able to bind hydrophobic ligands. The APOD gene is upregulated in a number of pathologies, including Alzheimer's disease, Parkinson's disease, cancer, and hypothyroidism. Upregulation of ApoD is linked to decreased oxidative stress and inflammation in several models, including humans, mice, Drosophila melanogaster and plants. Studies suggest that the mechanism through which ApoD modulates oxidative stress and regulate inflammation is via its capacity to bind arachidonic acid (ARA). This polyunsaturated omega-6 fatty acid can be metabolised to generate large variety of pro-inflammatory mediators. ApoD serves as a sequester, blocking and/or altering arachidonic metabolism. In recent studies of diet-induced obesity, ApoD has been shown to modulate lipid mediators derived from ARA, but also from eicosapentaenoic acid and docosahexaenoic acid in an anti-inflammatory way. High levels of ApoD have also been linked to better metabolic health and inflammatory state in the round ligament of morbidly obese women. Since ApoD expression is upregulated in numerous diseases, it might serve as a therapeutic agent against pathologies aggravated by OS and inflammation such as many obesity comorbidities. This review will present the most recent findings underlying the central role of ApoD in the modulation of both OS and inflammation.

Data-Independent Acquisition-Based Serum Proteomic Profiling of Adult Moyamoya Disease Patients Reveals the Potential Pathogenesis of Vascular Changes.

Moyamoya disease (MMD) is a chronic cerebrovascular disease with unknown etiology. The pathogenesis of vascular changes remains unclear. Ischemic and hemorrhagic adult MMD patients and healthy volunteers were enrolled to collect serum for data-independent acquisition (DIA)-based proteomic analysis and ELISA validation. DIA serum proteomic revealed that apolipoprotein C-I (APOC1), apolipoprotein D (APOD), and apolipoprotein A-IV (APOA4) were decreased. The reductases glutathione S-transferase omega-1 (GSTO1) and peptidyl-prolyl cis-trans isomerase A (PPIA) were upregulated, and ADAMTS-like protein 4 (ADAMTSL4) was downregulated in both ischemic and hemorrhagic MMD. Afamin (AFM) and transforming growth factor-beta-induced protein ig-h3 (TGFBI) increased in ischemic patients but decreased in hemorrhagic patients. Serum ELISA results confirmed that APOA4, APOC1, and APOD were decreased compared to controls. Then, we retrospectively analyzed biochemical indexes of 200 MMD patients. A total of 54 enrolled MMD patients showed decreased total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-c). APOA4, APOC1, and APOD were vital factors in the HDL decrease in MMD patients. Lipoprotein dysfunction in MMD patients is involved in MMD. Intimal thickening by enhanced adhesion, middle layer vascular smooth muscle cell migration, and decreased lipid antioxidant function represented by HDL are potential pathogeneses of vascular changes in MMD.

Preparation, characterization, and osteogenic activity mechanism of casein phosphopeptide-calcium chelate.

Casein phosphopeptides (CPPs) are good at calcium-binding and intestinal calcium absorption, but there are few studies on the osteogenic activity of CPPs. In this study, the preparation of casein phosphopeptide calcium chelate (CPP-Ca) was optimized on the basis of previous studies, and its peptide-calcium chelating activity was characterized. Subsequently, the effects of CPP-Ca on the proliferation, differentiation, and mineralization of MC3T3-E1 cells were studied, and the differentiation mechanism of CPP-Ca on MC3T3-E1 cells was further elucidated by RNA sequencing (RNA-seq). The results showed that the calcium chelation rate of CPPs was 23.37%, and the calcium content of CPP-Ca reached 2.64 × 105 mg/kg. The test results of Ultraviolet–Visible absorption spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) indicated that carboxyl oxygen and amino nitrogen atoms of CPPs might be chelated with calcium during the chelation. Compared with the control group, the proliferation of MC3T3-E1 cells treated with 250 μg/mL of CPP-Ca increased by 21.65%, 26.43%, and 28.43% at 24, 48, and 72 h, respectively, and the alkaline phosphatase (ALP) activity and mineralized calcium nodules of MC3T3-E1 cells were notably increased by 55% and 72%. RNA-seq results showed that 321 differentially expressed genes (DEGs) were found in MC3T3-E1 cells treated with CPP-Ca, including 121 upregulated and 200 downregulated genes. Gene ontology (GO) revealed that the DEGs mainly played important roles in the regulation of cellular components. The enrichment of the Kyoto Encyclopedia of Genes and Genomes Database (KEGG) pathway indicated that the AMPK, PI3K-Akt, MAPK, and Wnt signaling pathways were involved in the differentiation of MC3T3-E1 cells. The results of a quantitative real-time PCR (qRT-PCR) showed that compared with the blank control group, the mRNA expressions of Apolipoprotein D (APOD), Osteoglycin (OGN), and Insulin-like growth factor (IGF1) were significantly increased by 2.6, 2.0 and 3.0 times, respectively, while the mRNA levels of NOTUM, WIF1, and LRP4 notably decreased to 2.3, 2.1, and 4.2 times, respectively, which were consistent both in GO functional and KEGG enrichment pathway analysis. This study provided a theoretical basis for CPP-Ca as a nutritional additive in the treatment and prevention of osteoporosis.

Early-life exposure to bisphenol A induces dysregulation of lipid homeostasis by the upregulation of SCD1 in male mice

Exposure of Bisphenol A (BPA) is closely associated with an increased prevalence of obesity-related metabolic syndrome. However, the potential mechanism of BPA-induced adipogenesis remains to be fully elucidated. Herein, potential mechanisms of BPA-induced adipogenesis in 3T3-L1 preadipocytes were evaluated using RNA-Seq. Then, using an early-life BPA exposure model, we further evaluated the effects of BPA exposure on lipid and glucose homeostasis. The results showed that lipid content in 3T3-L1 adipocytes was significantly increased after BPA exposure (p < 0.01) and male C57BL/6 mice with the dose of 500 μg/kg/day BPA by once-a-day oral administration for 8 weeks displayed a NAFLD-like phenotype. RNA-Seq analysis of preadipocytes showed that BPA exposure affected multiple biological processes including glycosphingolipid biosynthesis, regulation of lipolysis in adipocytes, PPAR signaling pathway and fatty acid metabolism. The dysregulation in a series of genes of mice was associated to de novo lipogenesis and lipid transport, which was linked to obesity. Importantly, we also found a significant expression increase of stearoyl-CoA desaturase 1 (SCD1) and a significant decrease of apolipoprotein D (APOD) in both fat (p < 0.01) and livers (p < 0.01) of male mice. Besides, the dysregulation of pro-inflammatory genes (TNF-α,IL-6 and SAA3) showed that BPA exposure promoted progression of hepatic inflammation. In conclusion, this study elucidated a novel mechanism in which obesity associated with BPA exposure by targeting SCD1. Exposure to BPA should be carefully examined in the chronic liver metabolic diseases.

Apolipoprotein D as a Potential Biomarker and Construction of a Transcriptional Regulatory-Immune Network Associated with Osteoarthritis by Weighted Gene Coexpression Network Analysis.

Synovial inflammation influences the progression of osteoarthritis (OA). Herein, we aimed to identify potential biomarkers and analyze transcriptional regulatory-immune mechanism of synovitis in OA using weighted gene coexpression network analysis (WGCNA). A data set of OA synovium samples (GSE55235) was analyzed based on WGCNA. The most significant module with OA was identified and function annotation of the module was performed, following which the hub genes of the module were identified using Pearson correlation and a protein-protein interaction network was constructed. A transcriptional regulatory network of hub genes was constructed using the TRRUST database. The immune cell infiltration of OA samples was evaluated using the single-sample Gene Set Enrichment Analysis (ssGSEA) method. The hub genes coexpressed in multiple tissues were then screened out using data sets of synovium, cartilage, chondrocyte, subchondral bone, and synovial fluid samples. Finally, transcriptional factors and coexpressed hub genes were validated via experiments. The turquoise module of GSE55235 was identified via WGCNA. Functional annotation analysis showed that "mineral absorption" and "FoxO signaling pathway" were mostly enriched in the module. JUN, EGR1, FOSB, and KLF4 acted as central nodes in protein-protein interaction network and transcription factors to connect several target genes. "Activated B cell," "activated CD4T cell," "eosinophil," "neutrophil," and "type 17 T helper cell" showed high immune infiltration, while FOSB, KLF6, and MYBL2 showed significant negative correlation with type 17 T helper cell. Our results suggest that the expression level of apolipoprotein D (APOD) was correlated with OA. Furthermore, transcriptional regulatory-immune network was constructed, which may contribute to OA therapy.

Adipose-Derived Lipid-Binding Proteins: The Good, the Bad and the Metabolic Diseases

Adipose tissue releases a large range of bioactive factors called adipokines, many of which are involved in inflammation, glucose homeostasis and lipid metabolism. Under pathological conditions such as obesity, most of the adipokines are upregulated and considered as deleterious, due to their pro-inflammatory, pro-atherosclerotic or pro-diabetic properties, while only a few are downregulated and would be designated as beneficial adipokines, thanks to their counteracting properties against the onset of comorbidities. This review focuses on six adipose-derived lipid-binding proteins that have emerged as key factors in the development of obesity and diabetes: Retinol binding protein 4 (RBP4), Fatty acid binding protein 4 (FABP4), Apolipoprotein D (APOD), Lipocalin-2 (LCN2), Lipocalin-14 (LCN14) and Apolipoprotein M (APOM). These proteins share structural homology and capacity to bind small hydrophobic molecules but display opposite effects on glucose and lipid metabolism. RBP4 and FABP4 are positively associated with metabolic syndrome, while APOD and LCN2 are ubiquitously expressed proteins with deleterious or beneficial effects, depending on their anatomical site of expression. LCN14 and APOM have been recently identified as adipokines associated with healthy metabolism. Recent findings on these lipid-binding proteins exhibiting detrimental or protective roles in human and murine metabolism and their involvement in metabolic diseases are also discussed.

Predictive protein markers for depression severity in mood disorders: A preliminary trans-diagnostic approach study

Depression is a common symptom of many mental disorders, especially major depressive disorder (MDD) and bipolar disorder (BD). Previous studies have reported that these diseases share common pathophysiological pathways; therefore, this study elucidated whether the plasma levels of protein markers related to common depressive symptoms differed between patients with BD and those with MDD. Plasma samples of 71 patients with mood disorders and clinical manifestations were analyzed in this study. After depleting the abundant proteins, liquid chromatography–tandem mass spectrometry and label-free quantification were performed. Five proteins, viz., cholesteryl ester transfer protein (CETP), apolipoprotein D (APOD), mannan-binding lectin serine protease 2 (MASP2), Ig lambda chain V-II region BO (IGLV2-8) and Ig kappa chain V-III region NG9 (IGKV3-20) were negatively associated with the total scores of the Hamilton depression rating scale (HAM-D), after adjusting for the covariates. CETP and APOD also showed significant negative correlations with the anhedonia/retardation and guilt/agitation scores of the HAM-D. Four proteins, namely, Ig kappa chain V-II region TEW (IGKC; IGKV2D-28), Ig lambda variable 5–45 (IGLV5-45), complement factor H (CFH) and attractin (ATRN), showed significant associations with anhedonia/retardation after adjusting for covariates. Proteins that significantly correlated with the symptoms could predict the remission state of depression (area under the curve [AUC], 0.83) and anhedonia/retardation (AUC, 0.80). Bioinformatics analysis revealed that complement activation, immune response, and lipid metabolism were significantly enriched pathways. Although our study design was cross-sectional and no controls were included, protein markers identified in this preliminary study will be further investigated in our subsequent longitudinal study.

A Five-Gene Prognostic Nomogram Predicting Disease-Free Survival of Differentiated Thyroid Cancer.

Background Differentiated thyroid cancer (DTC) is the most common type of thyroid tumor with a high recurrence rate. Here, we developed a nomogram to effectively predict postoperative disease-free survival (DFS) in DTC patients. Methods The mRNA expressions and clinical data of DTC patients were downloaded from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) database. Seventy percent of patients were randomly selected as the training dataset, and thirty percent of patients were classified into the testing dataset. Multivariate Cox regression analysis was adopted to establish a nomogram to predict 1-year, 3-year, and 5-year DFS rate of DTC patients. Results A five-gene signature comprised of TENM1, FN1, APOD, F12, and BTNL8 genes was established to predict the DFS rate of DTC patients. Results from the concordance index (C-index), area under curve (AUC), and calibration curve showed that both the training dataset and the testing dataset exhibited good prediction ability, and they were superior to other traditional models. The risk score and distant metastasis (M) of the five-gene signature were independent risk factors that affected DTC recurrence. A nomogram that could predict 1-year, 3-year, and 5-year DFS rate of DTC patients was established with a C-index of 0.801 (95% CI: 0.736, 0.866). Conclusion Our study developed a prediction model based on the gene expression and clinical characteristics to predict the DFS rate of DTC patients, which may be applied to more accurately assess patient prognosis and individualized treatment.

Analysis of site-specific glycan profiles of serum proteins in patients with multiple sclerosis or neuromyelitis optica spectrum disorder-a pilot study.

Glycosylation is important for biological functions of proteins and greatly affected by diseases. Exploring the glycosylation profile of the protein-specific glycosylation and/or the site-specific glycosylation may help understand disease etiology, differentiate diseases and ultimately develop therapeutics. Patients with multiple sclerosis (MS) and patients with neuromyelitis optica spectrum disorder (NMOSD) are sometimes difficult to differentiate due to the similarity in their clinical symptoms. The disease-related glycosylation profiles of MS and NMOSD have not yet been well studied. Here, we analyzed site-specific glycan profiles of serum proteins of these patients by using a recently developed mass spectrometry technique. A total of 286 glycopeptides from 49 serum glycoproteins were quantified and compared between healthy controls (n=6), remitting MS (n=45) and remitting NMOSD (n=23) patients. Significant differences in the levels of site-specific N-glycans on inflammation-associated components [IgM, IgG1, IgG2, complement components 8b (CO8B) and attractin], central nerve system-damage-related serum proteins [apolipoprotein D (APOD), alpha-1-antitrypsin, plasma kallikrein and ADAMTS-like protein 3] were observed among three study groups. We furthered demonstrated that site-specific N-glycans on APOD on site 98, CO8B on sites 243 and 553 are potential markers to differentiate MS from NMOSD with an area under receiver operating curve value>0.75. All these observations indicate that remitting MS or NMOSD patients possess a unique disease-associated glyco-signature in their serum proteins. We conclude that monitoring one's serum protein glycan profile using this high-throughput analysis may provide an additional diagnostic criterion for differentiating diseases, monitoring disease status and estimating response-to-treatment effect.

Brain-specific lipoprotein receptors interact with astrocyte derived apolipoprotein and mediate neuron-glia lipid shuttling

Lipid shuttling between neurons and glia contributes to the development, function, and stress responses of the nervous system. To understand how a neuron acquires its lipid supply from specific lipoproteins and their receptors, we perform combined genetic, transcriptome, and biochemical analyses in the developing Drosophila larval brain. Here we report, the astrocyte-derived secreted lipocalin Glial Lazarillo (GLaz), a homolog of human Apolipoprotein D (APOD), and its neuronal receptor, the brain-specific short isoforms of Drosophila lipophorin receptor 1 (LpR1-short), cooperatively mediate neuron-glia lipid shuttling and support dendrite morphogenesis. The isoform specificity of LpR1 defines its distribution, binding partners, and ability to support proper dendrite growth and synaptic connectivity. By demonstrating physical and functional interactions between GLaz/APOD and LpR1, we elucidate molecular pathways mediating lipid trafficking in the fly brain, and provide in vivo evidence indicating isoform-specific expression of lipoprotein receptors as a key mechanism for regulating cell-type specific lipid recruitment.

Ectopic expression of human apolipoprotein D in Arabidopsis plants lacking chloroplastic lipocalin partially rescues sensitivity to drought and oxidative stress

The chloroplastic lipocalin (LCNP) is induced in response to various abiotic stresses including high light, dehydration and low temperature. It contributes to protection against oxidative damage promoted by adverse conditions by preventing accumulation of fatty acid hydroperoxides and lipid peroxidation. In contrast to animal lipocalins, LCNP is poorly characterized and the molecular mechanism by which it exerts protective effects during oxidative stress is largely unknown. LCNP is considered the ortholog of human apolipoprotein D (APOD), a protein whose lipid antioxidant function has been characterized. Here, we investigated whether APOD could functionally replace LCNP in Arabidopsis thaliana. We introduced APOD cDNA fused to a chloroplast transit peptide encoding sequence in an Arabidopsis LCNP KO mutant line and challenged the transgenic plants with different abiotic stresses. We demonstrated that expression of human APOD in Arabidopsis can partially compensate for the lack of the plastid lipocalin. The results are consistent with a conserved function of APOD and LCNP under stressful conditions. However, if the results obtained with the drought and oxidative stresses point to the protective effect of constitutive expression of APOD in plants lacking LCNP, this effect is not as effective as that conferred by LCNP overexpression. Moreover, when investigating APOD function in thylakoids after high light stress at low temperature, it appeared that APOD could not contribute to qH, a slowly reversible form of non-photochemical chlorophyll fluorescence quenching, as described for LCNP. This work provides a base of understanding the molecular mechanism underlying LCNP protective function.

Celecoxib promotes survival and upregulates the expression of neuroprotective marker genes in two different in vitro models of Parkinson's disease

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder after Alzheimer's disease. Increasing evidence highlights the role of age-related chronic inflammation, oxidative stress and mitochondrial dysfunction in the pathogenesis of PD. A combination of these factors impairs the crosstalk between mitochondria and lysosomes, resulting in compromised cell homeostasis. Apolipoprotein D (APOD), an ancient and highly conserved anti-inflammatory and antioxidant lipocalin, and the transcription factor EB (TFEB), a master regulator of mitophagy, autophagy and lysosomal biogenesis, play key roles in these processes. Both APOD and TFEB have attracted attention as therapeutic targets for PD. The aim of this study was to investigate if the selective cyclooxygenase-2 inhibitor celecoxib (CXB) exerts a direct neuroprotective effect in 6-hydroxydopamine (6-OHDA) and paraquat (PQ) PD models. We found that CXB rescued SH-SY5Y cells challenged by 6-OHDA- and PQ-induced toxicity. Furthermore, treatment with CXB led to a marked and sustained upregulation of APOD and the two microphthalmia transcription factors TFEB and MITF. In sum, this study highlights the clinically approved drug CXB as a promising neuroprotective therapeutic tool in PD research that has the potential to increase the survival rate of dopaminergic neurons that are still alive at the time of diagnosis.

Involvement of apolipoprotein D in desiccation tolerance and adult fecundity of Acyrthosiphon pisum

Apolipoprotein D (ApoD) is a lipocalin superfamily member that plays important roles in the transport of small hydrophobic molecules, lipid metabolism, and stress resistance. Cuticular hydrocarbons are the principal components of the epicuticular lipid layer and play a critical role in water retention against environmental desiccation stress; however, the mechanism underlying the role of ApoD in insect desiccation tolerance has not yet been elucidated. Here, we report the molecular constitution, functional analysis, and phylogenetic relationship of the ApoD gene in Acyrthosiphon pisum (ApApoD). We found that ApApoD was transcribed throughout the life cycle of A. pisum, but was prominently expressed in the embryonic period and abdominal cuticle. In addition, we optimized the dose and silencing duration of RNAi, observing that RNAi against ApApoD significantly reduced the levels of both internal and cuticular hydrocarbons and adult fecundity. Moreover, cuticular hydrocarbon deficiency increased the sensitivity of aphids to desiccation stress and reduced their survival time, while desiccation stress significantly increased ApApoD expression. Together, it is confirmed that ApApoD participates in regulating cuticular hydrocarbon content of aphids under desiccation stress and is crucial for aphid reproduction. Therefore, the ApApoD gene of A. pisum may be a potential target for RNAi-based insect pest control due to its involvement in cuticular hydrocarbon accumulation and reproduction.