Trehalose induces SQSTM1/p62 expression and enhances lysosomal activity and antioxidative capacity in adipocytes

The powerful potential of amino acid menthyl esters for anti-inflammatory and anti-obesity therapies

Our newly developed menthyl esters of valine and isoleucine exhibit anti-inflammatory properties beyond those of the well-known menthol in macrophages stimulated by lipopolysaccharide (LPS) and in a mouse model of colitis induced by sodium dextran sulfate. Unlike menthol, which acts primarily through the cold-sensitive TRPM8 channel, these menthyl esters displayed unique mechanisms that operate independently of this receptor. They readily penetrated target cells and efficiently suppressed LPS-stimulated tumour necrosis factor-alpha (Tnf) expression mediated by liver X receptor (LXR), a key nuclear receptor that regulates intracellular cholesterol and lipid balance. The menthyl esters showed affinity for LXR and enhanced the transcriptional activity through their non-competitive and potentially synergistic agonistic effect. This effect can be attributed to the crucial involvement of SCD1, an enzyme regulated by LXR, which is central to lipid metabolism and plays a key role in the anti-inflammatory response. In addition, we discovered that the menthyl esters showed remarkable efficacy in suppressing adipogenesis in 3T3-L1 adipocytes at the mitotic clonal expansion stage in an LXR-independent manner as well as in mice subjected to diet-induced obesity. These multiple capabilities of our compounds establish them as formidable allies in the fight against inflammation and obesity, paving the way for a range of potential therapeutic applications.

Expression of LC3A, LC3B and p62/SQSTM1 autophagy proteins in hepatocellular carcinoma (HCC) tissues and the predicted microRNAs involved in the autophagy-related pathway

BACKGROUND

Autophagy plays multifaceted roles in regulating hepatocellular carcinoma (HCC) and the mechanisms involved are under-explored. Regulatory microRNAs (miRNAs) have been reported to target autophagy proteins but their roles in HCC is not well studied. Using HCC patient tissues, this study aims to investigate the association of autophagy with several clinicopathological parameters as well as identifying the autophagy-related miRNAs and the possible pathways.

METHODS AND RESULTS

Autophagy level in the HCC patient-derived cancer and non-cancer tissues was determined by immunohistochemistry (IHC) targeting SQSTM1, LC3A and LC3B proteins. Significance tests of clinicopathological variables were tested using the Fisher's exact or Chi-square tests. Gene and miRNA expression assays were carried out and analyzed using Nanostring platform and software followed by validation of other online bioinformatics tools, namely String and miRabel. Autophagy expression was significantly higher in cancerous tissues compared to adjacent non-cancer tissues. High LC3B expression was associated with advanced tumor histology grade and tumor location. Nanostring gene expression analysis revealed that SQSTM1, PARP1 and ATG9A genes were upregulated in HCC tissues compared to non-cancer tissues while SIRT1 gene was downregulated. These genes are closely related to an autophagy pathway in HCC. Further, using miRabel tool, three downregulated miRNAs (hsa-miR-16b-5p, hsa-miR-34a-5p, and hsa-miR-660-5p) and one upregulated miRNA (hsa-miR-539-5p) were found to closely interact with the abovementioned autophagy-related genes. We then mapped out the possible pathway involving the genes and miRNAs in HCC tissues.

CONCLUSIONS

We conclude that autophagy events are more active in HCC tissues compared to the adjacent non-cancer tissues. We also reported the possible role of several miRNAs in regulating autophagy-related genes in the autophagy pathway in HCC. This may contribute to the development of potential therapeutic targets for improving HCC therapy. Future investigations are warranted to validate the target genes reported in this study using a larger sample size and more targeted molecular technique.

Trehalose enhances mitochondria deficits in human NPC1 mutant fibroblasts but disrupts mouse Purkinje cell dendritic growth ex vivo

Lysosomes play important roles in catabolism, nutrient sensing, metabolic signaling, and homeostasis. NPC1 deficiency disrupts lysosomal function by inducing cholesterol accumulation that leads to early neurodegeneration in Niemann-Pick type C (NPC) disease. Mitochondria pathology and deficits in NPC1 deficient cells are associated with impaired lysosomal proteolysis and metabolic signaling. It is thought that activation of the transcription factor TFEB, an inducer of lysosome biogenesis, restores lysosomal-autophagy activity in lysosomal storage disorders. Here, we investigated the effect of trehalose, a TFEB activator, in the mitochondria pathology of NPC1 mutant fibroblasts in vitro and in mouse developmental Purkinje cells ex vivo. We found that in NPC1 mutant fibroblasts, serum starvation or/and trehalose treatment, both activators of TFEB, reversed mitochondria fragmentation to a more tubular mitochondrion. Trehalose treatment also decreased the accumulation of Filipin+ cholesterol in NPC1 mutant fibroblasts. However, trehalose treatment in cerebellar organotypic slices (COSCs) from wild-type and Npc1nmf164 mice caused mitochondria fragmentation and lack of dendritic growth and degeneration in developmental Purkinje cells. Our data suggest, that although trehalose successfully restores mitochondria length and decreases cholesterol accumulation in NPC1 mutant fibroblasts, in COSCs, Purkinje cells mitochondria and dendritic growth are negatively affected possibly through the overactivation of the TFEB-lysosomal-autophagy pathway.

Metabolomic Analysis of Trehalose Alleviating Oxidative Stress in Myoblasts

Trehalose, a naturally occurring non-toxic disaccharide, has attracted considerable attention for its potential in alleviating oxidative stress in skeletal muscle. In this study, our aim was to elucidate the metabolic mechanisms underlying the protective effects of trehalose against hydrogen peroxide (H2O2)-induced oxidative stress in C2C12 myoblasts. Our results show that both trehalose treatment and pretreatment effectively alleviate the H2O2-induced decrease in cell viability, reduce intracellular reactive oxygen species (ROS), and attenuate lipid peroxidation. Furthermore, using NMR-based metabolomics analysis, we observed that trehalose treatment and pretreatment modulate the metabolic profile of myoblasts, specifically regulating oxidant metabolism and amino acid metabolism, contributing to their protective effects against oxidative stress. Importantly, our results reveal that trehalose treatment and pretreatment upregulate the expression levels of P62 and Nrf2 proteins, thereby activating the Nrf2-NQO1 axis and effectively reducing oxidative stress. These significant findings highlight the potential of trehalose supplementation as a promising and effective strategy for alleviating oxidative stress in skeletal muscle and provide valuable insights into its potential therapeutic applications.

Upconversion Nanoparticle-Based Cell Membrane-Coated cRGD Peptide Bioorthogonally Labeled Nanoplatform for Glioblastoma Treatment

Glioblastoma is hard to be eradicated partly because of the obstructive blood-brain barrier (BBB) and the dynamic autophagy activities of glioblastoma. Here, hydroxychloroquine (HDX)-loaded yolk-shell upconversion nanoparticle (UCNP)@Zn0.5Cd0.5S nanoparticle coating with the cyclic Arg-Gly-Asp (cRGD)-grafted glioblastoma cell membrane for near-infrared (NIR)-triggered treatment of glioblastoma is prepared for the first time. UCNPs@Zn0.5Cd0.5S (abbreviated as YSN, yolk-shell nanoparticle) under NIR radiation will generate reactive oxygen species for imposing cytotoxicity. HDX, the only available autophagy inhibitor in clinical studies, can enhance cytotoxicity by preventing damaged organelles from being recycled. The cRGD-decorated cell membrane allowed the HDX-loaded nanoparticles to efficiently bypass the BBB and specifically target glioblastoma cells. Exceptional treatment efficacy of the NIR-triggered chemotherapy and photodynamic therapy was achieved in U87 cells and in the mouse glioblastoma model as well. Our results provided proof-of-concept evidence that HDX@YSN@CCM@cRGD could overcome the delivery barriers and achieve targeted treatment of glioblastoma.

Trehalose Attenuates Oxidative Stress and Endoplasmic Reticulum Stress-Mediated Apoptosis in IPEC-J2 Cells Subjected to Heat Stress

This study was carried out to investigate the effects of trehalose (Tre) on antioxidant capacity, endoplasmic reticulum stress (ERS) response and apoptosis of heat-stressed intestinal porcine epithelial cells (IPEC-J2). IPEC-J2 cells were cultured at 37 °C until the end of the experiment (control, CON); exposed to heat stress for 2 h (43 °C, HS); or pretreated with 0.1, 1, 5, 10, and 15 mM trehalose at 37 °C for 4 h prior to heat stress exposure for 2 h. The optimum level of trehalose for protecting against HS-induced cell injuries was determined to be 10 mM, as evidenced by the highest cellular viability and lowest malondialdehyde (MDA) content and lactate dehydrogenase (LDH) activity. Based on these, IPEC-J2 cells were divided into three groups: the first group was cultured at 37 °C until the end of the experiment (control, CON); the second group was exposed to heat stress for 2 h (43 °C, HS); the third group was pretreated with 10 mM trehalose for 4 h at 37 °C prior to heat stress exposure for 2 h (Tre + HS). The reactive oxygen species (ROS) content, superoxide dismutase (SOD) activity, mitochondrial membrane potential (MMP) changes, and expressions of the manganese superoxide dismutase (SOD2), ERS and apoptosis-related proteins were determined. Compared to the CON group, HS significantly increased ROS generation (p < 0.01), decreased SOD activity (p < 0.05), and downregulated protein expression of SOD2 (p < 0.01). Compared to the HS group, Tre supplementation reduced ROS levels and increased SOD activity and SOD2 expression to the levels that were comparable to the control (p < 0.05). The HS-induced ERS response was evidenced by the increased protein expressions of glucose-regulated protein 78 (GRP78) (p < 0.01), eukaryotic translation initiation factor 2α (p-eif2α) (p < 0.01), transcription activator 4 (ATF4) (p < 0.01), and the protein expression of C/EBP homologous protein (CHOP) (p < 0.01), which were the four hallmarks of ERS. The Tre + HS group showed lower expressions of GRP78 (p < 0.01), p-eif2α (p < 0.01), ATF4 (p < 0.01), and CHOP (p < 0.01) than that of the HS group. Tre pretreatment attenuated HS-induced mitochondrial apoptosis in IPEC-J2 cells, demonstrated by the increased MMP and decreased proapoptotic proteins active caspase 3, Bax, and cytochrome c (Cyt c). Taken together, trehalose can protect against HS-induced oxidative damage and endoplasmic reticulum stress-mediated apoptosis in IPEC-J2 cells. These data may provide a nutritional strategy for alleviating heat stress in pig production.

Activation of ectopic olfactory receptor 544 induces GLP-1 secretion and regulates gut inflammation

Olfactory receptors are ectopically expressed in extra-nasal tissues. The gut is constantly exposed to high levels of odorants where ectopic olfactory receptors may play critical roles. Activation of ectopic olfactory receptor 544 (Olfr544) by azelaic acid (AzA), an Olfr544 ligand, reduces adiposity in mice fed a high-fat diet (HFD) by regulating fuel preference to fats. Herein, we investigated the novel function of Olfr544 in the gut. In GLUTag cells, AzA induces the cAMP-PKA-CREB signaling axis and increases the secretion of GLP-1, an enteroendocrine hormone with anti-obesity effects. In mice fed a HFD and orally administered AzA, GLP-1 plasma levels were elevated in mice. The induction of GLP-1 secretion was negated in cells with Olfr544 gene knockdown and in Olfr544-deficient mice. Gut microbiome analysis revealed that AzA increased the levels of Bacteroides acidifaciens and microbiota associated with antioxidant pathways. In fecal metabolomics analysis, the levels of succinate and trehalose, metabolites correlated with a lean phenotype, were elevated by AzA. The function of Olfr544 in gut inflammation, a key feature in obesity, was further investigated. In RNA sequencing analysis, AzA suppressed LPS-induced activation of inflammatory pathways and reduced TNF-α and IL-6 expression, thereby improving intestinal permeability. The effects of AzA on the gut metabolome, microbiome, and colon inflammation were abrogated in Olfr544-KO mice. These results collectively demonstrated that activation of Olfr544 by AzA in the gut exerts multiple effects by regulating GLP-1 secretion, gut microbiome and metabolites, and colonic inflammation in anti-obesogenic phenotypes and, thus, may be applied for obesity therapeutics.

Neuroprotective Effects of Trehalose and Sodium Butyrate on Preformed Fibrillar Form of α-Synuclein-Induced Rat Model of Parkinson's Disease

Therapeutic options for Parkinson's disease (PD) are limited to a symptomatic approach, making it a global threat. Targeting aggregated alpha-synuclein (α-syn) clearance is a gold standard for ameliorating PD pathology, bringing autophagy into the limelight. Expression of autophagy related genes are under the regulation by histone modifications, however, its relevance in PD is yet to be established. Here, preformed fibrillar form (PFF) of α-syn was used to induce PD in wistar rats, which were thereafter subjected to treatment with trehalose (tre, 4g/kg, orally), a potent autophagy inducer and sodium butyrate (SB, 300 mg/kg, orally), a pan histone deacetylase inhibitor alone as well as in combination. The combination treatment significantly reduced motor deficits as evidenced after rotarod, narrow beam walk, and open field tests. Novel object location and recognition tests were performed to govern cognitive abnormality associated with advanced stage PD, which was overcome by the combination treatment. Additionally, with the combination, the level of pro-inflammatory cytokines were significantly reduced, along with elevated levels of dopamine and histone H3 acetylation. Further, mRNA analysis revealed that levels of certain autophagy related genes and proteins implicated in PD pathogenesis significantly improved after administration of both tre and SB. Immunofluorescence and H&E staining in the substantia nigra region mirrored a potential improvement after treatment with both tre and SB. Therefore, outcomes of the present study were adequate to prove that combinatorial efficacy with tre and SB may prove to be a formidable insight into ameliorating PD exacerbated by PFF α-syn as compared to its individual efficacy.