Elevated PINK1/Parkin-Dependent Mitophagy and Boosted Mitochondrial Function Mediate Protection of HepG2 Cells from Excess Palmitic Acid by Hesperetin.

Deregulation of mitochondrial functions in hepatocytes contributes to many liver diseases, such as nonalcoholic fatty liver disease (NAFLD). Lately, it was referred to as MAFLD (metabolism-associated fatty liver disease). Hesperetin (Hst), a bioactive flavonoid constituent of citrus fruit, has been proven to attenuate NAFLD. However, a potential connection between its preventive activities and the modulation of mitochondrial functions remains unclear. Here, our results showed that Hst alleviates palmitic acid (PA)-triggered NLRP3 inflammasome activation and cell death by inhibition of mitochondrial impairment in HepG2 cells. Hst reinstates fatty acid oxidation (FAO) rates measured by seahorse extracellular flux analyzer and intracellular acetyl-CoA levels as well as intracellular tricarboxylic acid cycle metabolites levels including NADH and FADH2 reduced by PA exposure. In addition, Hst protects HepG2 cells against PA-induced abnormal energetic profile, ATP generation reduction, overproduction of mitochondrial reactive oxygen species, and collapsed mitochondrial membrane potential. Furthermore, Hst improves the protein expression involved in PINK1/Parkin-mediated mitophagy. Our results demonstrate that it restores PA-impaired mitochondrial function and sustains cellular homeostasis due to the elevation of PINK1/Parkin-mediated mitophagy and the subsequent disposal of dysfunctional mitochondria. These results provide therapeutic potential for Hst utilization as an effective intervention against fatty liver disease.

Targeting PHGDH reverses the immunosuppressive phenotype of tumor-associated macrophages through α-ketoglutarate and mTORC1 signaling.

Phosphoglycerate dehydrogenase (PHGDH) has emerged as a crucial factor in macromolecule synthesis, neutralizing oxidative stress, and regulating methylation reactions in cancer cells, lymphocytes, and endothelial cells. However, the role of PHGDH in tumor-associated macrophages (TAMs) is poorly understood. Here, we found that the T helper 2 (Th2) cytokine interleukin-4 and tumor-conditioned media upregulate the expression of PHGDH in macrophages and promote immunosuppressive M2 macrophage activation and proliferation. Loss of PHGDH disrupts cellular metabolism and mitochondrial respiration, which are essential for immunosuppressive macrophages. Mechanistically, PHGDH-mediated serine biosynthesis promotes α-ketoglutarate production, which activates mTORC1 signaling and contributes to the maintenance of an M2-like macrophage phenotype in the tumor microenvironment. Genetic ablation of PHGDH in macrophages from tumor-bearing mice results in attenuated tumor growth, reduced TAM infiltration, a phenotypic shift of M2-like TAMs toward an M1-like phenotype, downregulated PD-L1 expression and enhanced antitumor T-cell immunity. Our study provides a strong basis for further exploration of PHGDH as a potential target to counteract TAM-mediated immunosuppression and hinder tumor progression.

Norbergenin prevents LPS-induced inflammatory responses in macrophages through inhibiting NFκB, MAPK and STAT3 activation and blocking metabolic reprogramming.

Inflammation is thought to be a key cause of many chronic diseases and cancer. However, current therapeutic agents to control inflammation have limited long-term use potential due to various side-effects. This study aimed to examine the preventive effects of norbergenin, a constituent of traditional anti-inflammatory recipes, on LPS-induced proinflammatory signaling in macrophages and elucidate the underlying mechanisms by integrative metabolomics and shotgun label-free quantitative proteomics platforms. Using high-resolution mass spectrometry, we identified and quantified nearly 3000 proteins across all samples in each dataset. To interpret these datasets, we exploited the differentially expressed proteins and conducted statistical analyses. Accordingly, we found that LPS-induced production of NO, IL1ß, TNFα, IL6 and iNOS in macrophages was alleviated by norbergenin via suppressed activation of TLR2 mediated NFκB, MAPKs and STAT3 signaling pathways. In addition, norbergenin was capable of overcoming LPS-triggered metabolic reprogramming in macrophages and restrained the facilitated glycolysis, promoted OXPHOS, and restored the aberrant metabolites within the TCA cycle. This is linked to its modulation of metabolic enzymes to support its anti-inflammatory activity. Thus, our results uncover that norbergenin regulates inflammatory signaling cascades and metabolic reprogramming in LPS stimulated macrophages to exert its anti-inflammatory potential.

Branched-chain ketoacids derived from cancer cells modulate macrophage polarization and metabolic reprogramming.

Macrophages are prominent immune cells in the tumor microenvironment that can be educated into pro-tumoral phenotype by tumor cells to favor tumor growth and metastasis. The mechanisms that mediate a mutualistic relationship between tumor cells and macrophages remain poorly characterized. Here, we have shown in vitro that different human and murine cancer cell lines release branched-chain α-ketoacids (BCKAs) into the extracellular milieu, which influence macrophage polarization in an monocarboxylate transporter 1 (MCT1)-dependent manner. We found that α-ketoisocaproate (KIC) and α-keto-ß-methylvalerate (KMV) induced a pro-tumoral macrophage state, whereas α-ketoisovalerate (KIV) exerted a pro-inflammatory effect on macrophages. This process was further investigated by a combined metabolomics/proteomics platform. Uptake of KMV and KIC fueled macrophage tricarboxylic acid (TCA) cycle intermediates and increased polyamine metabolism. Proteomic and pathway analyses revealed that the three BCKAs, especially KMV, exhibited divergent effects on the inflammatory signal pathways, phagocytosis, apoptosis and redox balance. These findings uncover cancer-derived BCKAs as novel determinants for macrophage polarization with potential to be selectively exploited for optimizing antitumor immune responses.

Inverse Data-Driven Modeling and Multiomics Analysis Reveals Phgdh as a Metabolic Checkpoint of Macrophage Polarization and Proliferation.

Mechanistic or mammalian target of rapamycin complex 1 (mTORC1) is an important regulator of effector functions, proliferation, and cellular metabolism in macrophages. The biochemical processes that are controlled by mTORC1 are still being defined. Here, we demonstrate that integrative multiomics in conjunction with a data-driven inverse modeling approach, termed COVRECON, identifies a biochemical node that influences overall metabolic profiles and reactions of mTORC1-dependent macrophage metabolism. Using a combined approach of metabolomics, proteomics, mRNA expression analysis, and enzymatic activity measurements, we demonstrate that Tsc2, a negative regulator of mTORC1 signaling, critically influences the cellular activity of macrophages by regulating the enzyme phosphoglycerate dehydrogenase (Phgdh) in an mTORC1-dependent manner. More generally, while lipopolysaccharide (LPS)-stimulated macrophages repress Phgdh activity, IL-4-stimulated macrophages increase the activity of the enzyme required for the expression of key anti-inflammatory molecules and macrophage proliferation. Thus, we identify Phgdh as a metabolic checkpoint of M2 macrophages.

Anti-inflammatory effects of Morchella esculenta polysaccharide and its derivatives in fine particulate matter-treated NR8383 cells.

Fine particulate matter (PM2.5) exposure could cause many acute and chronic respiratory diseases. In this study the protective effects of polysaccharide from Morchella esculenta (FMP-1) and its derivatives against PM2.5-induced inflammation were evaluated. By flow cytometry and ELISA analysis, sulfated polysaccharide SFMP-1 showed the best protective effect in reducing PM2.5-induced cell death, cell apoptosis and production of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß), which was accompanied by a diminished level in reactive oxygen species (ROS) formation caused by PM2.5 in rat alveolar macrophage NR8383 cells. Furthermore, the mechanism was studied by immunofluorescence, qRT-PCR and western blotting. SFMP-1 could down-regulate the expression of inducible NO synthesis (iNOS) and cyclooxygenase-2 (COX-2) at both mRNA and protein levels in PM2.5-treated cells. The PM2.5-induced phosphorylation of nuclear factor-kappa B (NF-κB) was also reduced through suppressing nuclear translation of the NF-κB and inhibiting the degradation and phosphorylation of IκBα. These results indicated that SFMP-1 could protect NR8383 cells from PM2.5-induced inflammation by inhibiting NF-κB activation.

Effect of polysaccharide FMP-1 from Morchella esculenta on melanogenesis in B16F10 cells and zebrafish.

Polysaccharides from Morchella esculenta are known to exhibit diverse bioactivities, while an anti-melanogenesis effect has been barely addressed. Herein, the anti-melanogenesis activity of a heteropolysaccharide from M. esculenta (FMP-1) was investigated in vitro and in vivo. FMP-1 had no significant cytotoxic effect on B16F10 melanoma cells as well as zebrafish larvae, but did reduce melanin contents and tyrosinase activities in both of them. Treatment with FMP-1 also effectively suppressed the expression of melanogenesis-related proteins, including MC1R, MITF, TRP-1 and TRP-2, through decreasing the phosphorylation of cyclic adenosine monophosphate response element-binding protein (CREB). Moreover, the mitogen-activated protein kinase (MAPK) pathway was observed mediating FMP-1's inhibitory effect against melanin production. Specifically, FMP-1 treatment markedly inhibited the activation of phosphorylation of p38 mitogen-activated protein kinase. These results suggested that FMP-1's inhibitory effect against melanogenesis is mediated by the inhibition of CREB and p38 signaling pathways, thereby resulting in the downstream repression of melanogenesis-related proteins and the subsequent melanin production. These data provide insight into FMP-1's potential anti-melanogenesis effect in food and cosmetic industries.

Polysaccharide FMP-1 from Morchella esculenta attenuates cellular oxidative damage in human alveolar epithelial A549 cells through PI3K/AKT/Nrf2/HO-1 pathway.

Oxidative stress is considered to involve cell death in severe pulmonary diseases like idiopathic pulmonary fibrosis (IPF). Polysaccharide FMP-1 from Morchella esculenta can exert significant antioxidant activity. However, its effects on alveolar epithelial cells remain unperceived. Herein, the effects of FMP-1 against H2O2-induced oxidative damage in human alveolar epithelial A549 cells were investigated. FMP-1 could inhibit H2O2-induced cytochrome C and Caspase-3 release to prevent cell apoptosis via attenuation of MDA and ROS levels, and enhancement the enzymatic activities of SOD and T-AOC. Furthermore, the underlying molecular mechanisms were clarified. The phosphorylation of AKT and the nuclear translocation of Nrf2 were observed to be promoted by FMP-1 as well as the level of HO-1. These findings suggested that FMP-1 attenuate cellular oxidative stress through PI3K/AKT pathway, and FMP-1 could be explored as natural potential antioxidants to lower oxidative stress relevant to the progression of IPF.

Structural characterization, in vitro and in vivo antioxidant activities of a heteropolysaccharide from the fruiting bodies of Morchella esculenta.

This study aimed to investigate the structural features, in vitro and in vivo antioxidant activities of a heteropolysaccharide from the fruiting bodies of Morchella esculenta (FMP-1). FMP-1 had an average molecular weight of 4.7 × 103 Da and consisted of mannose, glucose and galactose. By methylation and NMR analysis, the backbone of FMP-1 was deduced to be made up of 1,4-linked Glcp and 1,6-linked Galp. Hydroxyl, DPPH and superoxide radicals could be efficiently scavenged by FMP-1, with IC50 values of 74.26, 119.32 and 161.49 µg/mL, respectively. Furthermore, FMP-1 could significantly protect zebrafish embryos against AAPH-induced oxidative damage. Decrease in malformations and mortalities was observed along with the reduction of ROS production, NO production and cell death. The protective effects were by decreasing MDA content and increasing SOD, CAT and GSH-Px levels. The current work provided a good suggestion of the potential utilization of FMP-1 as an attractive natural antioxidant.

Antioxidant capacity and cytotoxicity of sulfated polysaccharide TLH-3 from Tricholoma lobayense.

Polysaccharide TLH-3 from the fruit body of Tricholoma lobayense Heim has shown outstanding antioxidant activity. In order to further explore it, TLH-3 was successfully modified to obtain a sulfated derivative (STLH-3). The chemical characteristics of STLH-3 and TLH-3 were determined by high performance liquid chromatography and infrared spectroscopy. Antioxidant activity and cytotoxicity of the samples were investigated in vitro. The antioxidant activities of STLH-3 were significantly improved. In the four indicators of antioxidant activity, the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion scavenging activities of STLH-3 have exceeded that of Vitamin C (Vc). The cytotoxicity against tumor cells including human cervical carcinoma cell line (HeLa) and human breast cancer cell line (MCF-7) of STLH-3 was obviously stronger than that of TLH-3. STLH-3 had no toxic on human embryonic lung fibroblasts (HELF) cells. These results suggested that STLH-3 would be a promising bioactive macromolecule for potential applications in the field of health care and pharmaceutical.