Pyrroloquinoline quinone promotes human mesenchymal stem cell-derived mitochondria to improve premature ovarian insufficiency in mice through the SIRT1/ATM/p53 pathway.

BACKGROUND: DNA damage and oxidative stress induced by chemotherapy are important factors in the onset of premature ovarian insufficiency (POI). Studies have shown that mitochondria derived from mesenchymal stem cells (MSC-Mito) are beneficial for age-related diseases, but their efficacy alone is limited. Pyrroloquinoline quinone (PQQ) is a potent antioxidant with significant antiaging and fertility enhancement effects. This study aimed to investigate the therapeutic effect of MSC-Mito in combination with PQQ on POI and the underlying mechanisms involved. METHODS: A POI animal model was established in C57BL/6J mice by cyclophosphamide and busulfan. The effects of MSC-Mito and PQQ administration on the estrous cycle, ovarian pathological damage, sex hormone secretion, and oxidative stress in mice were evaluated using methods such as vaginal smears and ELISAs. Western blotting and immunohistochemistry were used to assess the expression of SIRT1, PGC-1α, and ATM/p53 pathway proteins in ovarian tissues. A cell model was constructed using KGN cells treated with phosphoramide mustard to investigate DNA damage and apoptosis through comet assays and flow cytometry. SIRT1 siRNA was transfected into KGN cells to further explore the role of the SIRT1/ATM/p53 pathway in combination therapy with MSC-Mito and PQQ for POI. RESULTS: The combined treatment of MSC-Mito and PQQ significantly restored ovarian function and antioxidant capacity in mice with POI. This treatment also reduced the loss of follicles at various stages, improving the disrupted estrous cycle. In vitro experiments demonstrated that PQQ facilitated the proliferation of MitoTracker-labelled MSC-Mito, synergistically restoring mitochondrial function and inhibiting oxidative stress in combination with MSC-Mito. Both in vivo and in vitro, the combination of MSC-Mito and PQQ increased mitochondrial biogenesis mediated by SIRT1 and PGC-1α while inhibiting the activation of ATM and p53, consequently reducing DNA damage-mediated cell apoptosis. Furthermore, pretreatment of KGN cells with SIRT1 siRNA reversed nearly all the aforementioned changes induced by the combined treatment. CONCLUSIONS: Our research findings indicate that PQQ facilitates MSC-Mito proliferation and, in combination with MSC-Mito, ameliorates chemotherapy-induced POI through the SIRT1/ATM/p53 signaling pathway.

Protective role of pyrroloquinoline quinone against gentamicin induced cochlear hair cell ototoxicity.

Gentamicin (GM) is one of the commonly used antibiotics in the aminoglycoside class but is ototoxic, which constantly impacts the quality of human life. Pyrroloquinoline quinone (PQQ) as a redox cofactor produced by bacteria was found in soil and foods that exert an antioxidant and redox modulator. It is well documented that the PQQ can alleviate inflammatory responses and cytotoxicity. However, our understanding of PQQ in ototoxicity remains unclear. We reported that PQQ could protect against GM-induced ototoxicity in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells in vitro. To evaluate reactive oxygen species (ROS) production and mitochondrial function, ROS and JC-1 staining, oxygen consumption rate (OCR), and extracellular acidification rate (ECAR) measurements in living cells, mitochondrial dynamics analysis was performed. GM-mediated damage was performed by reducing the production of ROS and inhibiting mitochondria biogenesis and dynamics. PQQ ameliorated the cellular oxidative stress and recovered mitochondrial membrane potential, facilitating the recovery of mitochondrial biogenesis and dynamics. Our in vitro findings improve our understanding of the GM-induced ototoxicity with therapeutic implications for PQQ.

Pyrroloquinoline quinone drives ATP synthesis in vitro and in vivo and provides retinal ganglion cell neuroprotection.

Retinal ganglion cells are highly metabolically active requiring strictly regulated metabolism and functional mitochondria to keep ATP levels in physiological range. Imbalances in metabolism and mitochondrial mechanisms can be sufficient to induce a depletion of ATP, thus altering retinal ganglion cell viability and increasing cell susceptibility to death under stress. Altered metabolism and mitochondrial abnormalities have been demonstrated early in many optic neuropathies, including glaucoma, autosomal dominant optic atrophy, and Leber hereditary optic neuropathy. Pyrroloquinoline quinone (PQQ) is a quinone cofactor and is reported to have numerous effects on cellular and mitochondrial metabolism. However, the reported effects are highly context-dependent, indicating the need to study the mechanism of PQQ in specific systems. We investigated whether PQQ had a neuroprotective effect under different retinal ganglion cell stresses and assessed the effect of PQQ on metabolic and mitochondrial processes in cortical neuron and retinal ganglion cell specific contexts. We demonstrated that PQQ is neuroprotective in two models of retinal ganglion cell degeneration. We identified an increased ATP content in healthy retinal ganglion cell-related contexts both in in vitro and in vivo models. Although PQQ administration resulted in a moderate effect on mitochondrial biogenesis and content, a metabolic variation in non-diseased retinal ganglion cell-related tissues was identified after PQQ treatment. These results suggest the potential of PQQ as a novel neuroprotectant against retinal ganglion cell death.

Pyrroloquinoline Quinone (PQQ) Improves Long-term Survival of Fat Grafts by Alleviating Oxidative Stress and Promoting Angiogenesis During the Early Phase After Transplantation.

BACKGROUND: Reducing absorption after autologous fat grafting is a current challenge. Pyrroloquinoline quinone (PQQ) is the strongest known catalyst of redox reactions, which can scavenge reactive oxygen species (ROS) and alleviate oxidative stress. OBJECTIVES: The aim of this study was to establish an in vivo model of PQQ-assisted lipotransfer and clarify the role of PQQ in reducing oxidative stress, alleviating apoptosis, and promoting angiogenesis during the acute hypoxic phase after grafting. In addition the study was performed to assess whether this intervention would have a positive effect on the improvement of long-term volume retention. METHODS: Different concentrations of PQQ (low: 10 µM, medium: 100 µM, and high: 1000 µM) were mixed with human adipose tissue and transplanted subcutaneously into nude mice. Meanwhile, a control group of phosphate-buffered saline in an equal volume to PQQ was set up. On the third day after grafting, whole mount fluorescence staining was applied to detect ROS, mitochondrial membrane potential (MMP), apoptosis, adipocyte activity, and angiogenesis. Graft volume retention rate and electron microscopic morphology were evaluated at the third month. Immunohistochemistry and polymerase chain reaction (PCR) were further employed to elucidate the mechanism of action of PQQ. RESULTS: PQQ-assisted fat grafting improved the long-term volume retention, promoted the quality and viability of the adipose tissue, and reduced the level of fibrosis. The underlying mechanism of PQQ assisted in scavenging the accumulated ROS, restoring MMP, enhancing adipocyte viability, alleviating tissue apoptosis, and promoting timely angiogenesis during the hypoxia stress phase. The most effective concentration of PQQ was 100 µM. Immunohistochemistry and PCR experiments confirmed that PQQ reduced the expression of Bax and cytochrome c in the mitochondrial apoptotic pathway and increased the level of the antiapoptotic molecule Bcl-2. CONCLUSIONS: PQQ could improve the long-term survival of adipocytes by alleviating hypoxic stress and promoting timely angiogenesis in the early phase following lipotransfer.

Effects of Pyrroloquinoline Quinone (PQQ) and Coenzyme Q10 on Mitochondrial Genes, MitomiRs and Cellular Properties in HepG2 Cell Line.

Our study aimed to reveal the effects and changes, antioxidant metabolism (Oxidative Stress), inflammatory response, mitochondrial biogenesis and mitochondrial dysfunction characteristics in hepatocellular carcinoma cell line HepG2; that occur in genes (NRF-1, NRF-2, NFκB and PGC-1α) and miRNAs (miR15-a, miR16-1, miR181-c) that can control related features. To investigate the effects of Pyrroloquinoline quinone (PQQ) and Coenzyme Q10 (CoQ10) in HepG2, and their effects on cell viability, lateral cell migration, gene expression and miRNA expression levels were investigated. If the data we have obtained are evaluated in terms of anti-cancer effectiveness, the most effective use of CoQ10 can be defined as the use alone rather than the combined use. According to the results of the wound healing experiment, we determined that Pyrroloquinoline quinone and combined drug application increased the wound closure area and cell proliferation compared to the control group, while CoQ10 application decreased it. We found that Pyrroloquinoline quinone and Coenzyme Q10 exposure in the HepG2 cell line increased Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expression but not NRF-1 gene expression. We reported only a small increase in expression of the NRF-2 gene in the Pyrroloquinoline quinone application compared to the control group. We found that only Pyrroloquinoline quinone and CoQ10 application caused more expression increase in the Nuclear Factor kappa B (NFκB) gene compared to combined application. Pyrroloquinoline quinone and CoQ10 administration down-regulated the expression levels of miR16-1, miR15a and miR181c. The use of Pyrroloquinoline quinone and CoQ10 is effective on epigenetic factors, miR-15a, miR-16-1 and miR181c are important candidate biomarkers in hepatocellular carcinoma and diseases accompanied by mitochondrial dysfunction.

Pyrroloquinoline quinone ameliorates renal fibrosis in diabetic nephropathy by inhibiting the pyroptosis pathway in C57BL/6 mice and human kidney 2 cells.

Diabetic nephropathy (DN), which is characterized by renal fibrosis, is a major complication of diabetes, a disease that afflicted more than 460 million people worldwide in 2019. Pyroptosis is an essential signaling pathway in DN-related injuries, such as renal fibrosis. Pyrroloquinoline quinone (PQQ) is a naturally occurring bioactive compound that protects human kidney 2 (HK-2) cells from oxidative stress-induced damage caused by high glucose concentrations. However, the nature and underlying mechanism of the effect of PQQ on DN-related renal fibrosis remains unclear. In this study, we evaluated whether PQQ has potential protective effects against renal fibrosis due to DN by establishing type 1 diabetes in mice via streptozotocin treatment and then inhibiting their pyroptosis signaling pathway. We found that compared to control mice, the area of renal fibrosis and injury were significantly increased in diabetic mice, and this was accompanied by increased levels of expression of collagen Ⅰ and transforming growth factor-ß1; increased concentrations of the inflammatory cytokines, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α; and activation of the pyroptosis pathway components nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), caspase-1, IL-1ß, and IL-18. All of these changes were reversed by PQQ treatment. Analogously, we treated cultured HK-2 cells with a high concentration of glucose (35 mmol/L), which caused these cells to exhibit significantly increased concentrations of reactive oxygen species (ROS), phosphorylated (p)-nuclear factor kappa B (NF-κB), p-IkappaB, NLRP3, caspase-1, IL-1ß, and IL-18, and the loss of mitochondrial transmembrane potential. However, PQQ treatment significantly blunted these effects. In conclusion, in this study we demonstrated that PQQ attenuates renal fibrosis by alleviating mitochondrial dysfunction, reducing ROS production, and inhibiting the activation of the NF-κB/pyroptosis pathway under conditions of DN and hyperglycemia.

Pyrroloquinoline quinone ameliorates liver injury in mice induced by cyclophosphamide.

The current study aimed to investigate the potential ameliorative effects of pyrroloquinoline quinone (PQQ) on cyclophosphamide (CTX)-induced liver injury in mice. The liver injury model was established by injecting mice with CTX (80 mg/kg/day). Liver function indices, antioxidant enzyme activities, and inflammatory cytokines were evaluated. In addition, protein expression levels of the nuclear factor E2-related factor 2 (Nrf2) and nuclear factor kappa-B (NF-κB) pathways in the liver tissues were determined using western blot. The results indicated that PQQ decreased the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the malondialdehyde (MDA), interleukin (IL)-1ß, IL-6, tumor necrosis factor-α (TNF-α) levels in the liver tissues. Moreover, PQQ enhanced the activities of oxidative stress markers to alleviate CTX induced oxidative stress. Furthermore, the expression levels of heme oxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GCLM), and NAD(P)H quinone oxidoreductase 1 (NQO1) were significantly increased, and the expression levels of NF-κB p50, NF-κB p65, and inhibitor of NF-κB kinase alpha (IKKα) were significantly decreased after PQQ administration, suggesting that PQQ alleviated CTX-induced liver injury via activating the Nrf2-mediated antioxidant response pathway, and inhibiting the NF-κB-mediated inflammation pathway. Therefore, PQQ can be potentially used as a dietary supplement or functional foods for alleviating the CTX-induced liver injury.

Pyrroloquinoline-Quinone Is More Than an Antioxidant: A Vitamin-like Accessory Factor Important in Health and Disease Prevention.

Pyrroloquinoline quinone (PQQ) is associated with biological processes such as mitochondriogenesis, reproduction, growth, and aging. In addition, PQQ attenuates clinically relevant dysfunctions (e.g., those associated with ischemia, inflammation and lipotoxicity). PQQ is novel among biofactors that are not currently accepted as vitamins or conditional vitamins. For example, the absence of PQQ in diets produces a response like a vitamin-related deficiency with recovery upon PQQ repletion in a dose-dependent manner. Moreover, potential health benefits, such as improved metabolic flexibility and immuno-and neuroprotection, are associated with PQQ supplementation. Here, we address PQQ's role as an enzymatic cofactor or accessory factor and highlight mechanisms underlying PQQ's actions. We review both large scale and targeted datasets demonstrating that a neonatal or perinatal PQQ deficiency reduces mitochondria content and mitochondrial-related gene expression. Data are reviewed that suggest PQQ's modulation of lactate acid and perhaps other dehydrogenases enhance NAD+-dependent sirtuin activity, along with the sirtuin targets, such as PGC-1α, NRF-1, NRF-2 and TFAM; thus, mediating mitochondrial functions. Taken together, current observations suggest vitamin-like PQQ has strong potential as a potent therapeutic nutraceutical.

Pyrroloquinoline quinone (PQQ) alleviated sepsis-induced acute liver injury, inflammation, oxidative stress and cell apoptosis by downregulating CUL3 expression.

PQQ has anti-inflammatory and anti-oxidant effects. PQQ can relieve high glucose-induced renal cell damage by suppressing Keap1 expression. Keap1 can interact with CUL3. Upregulation of CUL3 facilitates the apoptosis of LPS-induced podocytes. Based on knowledge above, this current work was designed to explore the role of PQQ in sepsis and determine the molecular function of CUL3 in the pathogenesis of sepsis. Rats received CLP surgery to establish sepsis models in vivo. Kupffer cells were pretreated with PQQ (10, 50 and 100 nmol/L) for 2 h and then treated with 100 ng/mL LPS for 24 h, simulating sepsis-induced acute liver injury in vitro. H&E staining was performed to evaluate liver injury of SD rats. Levels of inflammatory factors and oxidative stress markers were detected to assess inflammatory response and oxidative stress. Moreover, TUNEL staining, flow cytometric analysis and western blot were applied to determine cell apoptosis. It was confirmed that PQQ treatment relieved acute liver injury, inflammatory and oxidative stress damage and apoptosis of liver tissue cells in sepsis rats. In addition, PQQ therapy could alleviate inflammation, oxidative stress and apoptosis in LPS-induced Kupffer cells. Notably, LPS stimulation enhanced CUL3 expression and PQQ repressed CUL3 expression in Kupffer cells suffered from LPS. Overall, CUL3 overexpression weakened the remission effects of PQQ on LPS-induced inflammatory and oxidative damage and apoptosis of Kupffer cells. Mechanistically, PQQ treatment may mitigate sepsis-induced acute liver injury through downregulating CUL3 expression.

The mechanism of pyrroloquinoline quinone influencing the fracture healing process of estrogen-deficient mice by inhibiting oxidative stress.

It is reported that oxidative stress plays a detrimental role in the process of bone fracture healing. And pyrroloquinoline quinone (PQQ) is used as antioxidant. However, there is no report about whether PQQ supplementation can promote fracture healing by eliminating oxidative stress. To investigate the protective effect of PQQ on fracture healing, open mid-diaphyseal femur fractures model were created in sham, ovariectomized (OVX) mice and PQQ-treated OVX mice. Our results confirmed that PQQ played a preventive and protective role in OVX-induced delay of bone fracture healing by inhibiting oxidative stress, subsequently promoting osteoblastic bone formation and inhibiting osteoclastic bone resorption. The findings of this study not only revealed the mechanism of PQQ supplementation in promoting fracture healing, but also provide experimental and theoretical basis for the clinical application of PQQ in the treatment of bone fracture.

Pyrroloquinoline quinone protects against exercise-induced fatigue and oxidative damage via improving mitochondrial function in mice.

Pyrroloquinoline quinone (PQQ) has a variety of biological functions. However, rare attention has been paid to its effects on exercise-induced damage. Here, we assessed the potential protective effects of PQQ against the fatigue and oxidative damage caused by repeated exhaustive exercise, and studied the underlying mechanism. The models for exercise-induced fatigue were established, and the parameters were measured, including the time to exhaustion (TTE), biochemical indicators, the expression of nuclear factor kappa B (NF-κB) and inflammatory cytokines and so on. Besides, the mitochondrial function was evaluated by the morphology, membrane potential, respiratory function, adenosine triphosphate (ATP) levels, and the application of the mitochondrial complex I inhibitor. The results demonstrate that PQQ prolongs TTE, causes the decrease in the activity of serum creatine kinase and lactate dehydrogenase, increases the activity of antioxidant enzymes, inhibits the production of reactive oxygen species (ROS) and malondialdehyde (MDA), and diminishes the over expression of NF-κB (p65) and inflammatory mediators. Furthermore, PQQ preserves normal mitochondrial function. Particularly, PQQ reduces the accumulation of ROS triggered by the mitochondrial complex I inhibitor. These data suggest that PQQ can significantly protect mice from exercise-induced fatigue and oxidative damage by improving mitochondrial function. These data also suggest that PQQ controls mitochondrial activity through directly affecting the NADH dehydrogenase.

Protective Effect of Pyrroloquinoline Quinone on TNF-α-induced Mitochondrial Injury in Chondrocytes.

Osteoarthritis (OA) is a degenerative disease characterized by matrix degradation and cell death leading to a gradual loss of articular cartilage integrity. As a bacterial synthesis of quinine, pyrroloquinoline quinone (PQQ) is a strong redox cofactor with a variety of biological benefits, including antioxidant, anti-inflammation-induced mitochondrial metabolism regulation. This study was designed to investigate the effect of PQQ on TNF-α-induced mitochondrial damage in chondrocytes. Chondrocytes isolated from C57BL/6 mice were exposed to TNF-α 50 ng/mL, TNF-α 50 ng/mL + PQQ 10 µmol/L for 24 h. Then, morphological study, functional study and mechanism study were taken. The results revealed TNF-α-induced chondrocyte mitochondrion damage could be reduced by application of PQQ, evidenced by elevated number of mitochondria, well-kept mtDNA integrity, preserved ATP level, reestablished mitochondrial membrane potential, and prevented mitochondrial function. The present work strongly suggests that the mitochondrion is an important target for OA chondrocyte damage induced by TNF-α and the PQQ protection from this damage ameliorates mitochondrial dysfunction induced by TNF-α. PQQ might be a potential chemical for OA intervention.

Pyrroloquinoline Quinone Inhibits Rotenone-Induced Microglia Inflammation by Enhancing Autophagy.

Neuroinflammation is a feature common to neurodegenerative diseases, such as Parkinson's disease (PD), which might be responsive to therapeutic intervention. Rotenone has been widely used to establish PD models by inducing mitochondrial dysfunction and inflammation. Our previous studies have reported that pyrroloquinoline quinone (PQQ), a naturally occurring redox cofactor, could prevent mitochondrial dysfunction in rotenone induced PD models by regulating mitochondrial functions. In the present study, we aimed to investigate the effect of PQQ on neuroinflammation and the mechanism involved. BV2 microglia cells were pre-treated with PQQ followed by rotenone incubation. The data showed that PQQ did not affect the cell viability of BV2 cells treated with rotenone, while the conditioned medium (CM) of BV2 cells pre-treated with PQQ significantly increased cell viability of SH-SY5Y cells. In rotenone-treated BV2 cells, PQQ dose-dependently decreased lactate dehydrogenase (LDH) release and suppressed the up-regulation of pro-inflammation factors, such as interleukin-1ß (IL-1ß), IL-6 and tumor necrosis factor-α (TNF-α) in the cultured media, as well as nitric oxide (NO) release induced by rotenone. PQQ pretreatment also increased the ratio of LC3-II/LC3-I and expression of Atg5 in BV2 cells stimulated with rotenone. Additionally, the autophagosome observed by transmission electron microscopy (TEM) and co-localization of mitochondria with lysosomes indicated that mitophagy was induced by PQQ in rotenone-injured BV2 cells, and the PINK1/parkin mediated mitophagy pathway was regulated by PQQ. Further, autophagy inhibitor, 3-methyladenine (3-MA), partially abolished the neuroprotective effect of PQQ and attenuated the inhibition of inflammation with PQQ pretreatment. Taken together, our data extend our understanding of the neuroprotective effect of PQQ against rotenone-induced injury and provide evidence that autophagy enhancement might be a novel therapeutic strategy for PD treatment.

Ameliorate effect of pyrroloquinoline quinone against cyclophosphamide-induced nephrotoxicity by activating the Nrf2 pathway and inhibiting the NLRP3 pathway.

AIMS: Cyclophosphamide (CTX) is an effective anti-tumor and immunosuppressive agent, but it induces nephrotoxicity in clinical applications. The present study aimed to evaluate the protective effect of pyrroloquinoline quinone (PQQ) on CTX-induced nephrotoxicity. MAIN METHODS: We injected male ICR mice with CTX (80 mg/kg/day), and determined nephrotoxicity indices, MDA and antioxidant defenses, inflammatory cytokines, and the levels of main proteins in the Nrf2-HO-1 and NLRP3 signaling pathways. KEY FINDINGS: PQQ has significantly decreased the serum levels of creatinine and urea compared to Model group. When treated with PQQ, MDA, IL-1ß, IL-6, and TNF-α levels have decreased, and SOD, GSH-Px, and CAT activity have increased in the kidney tissues of CTX-induced mice. PQQ activated the Nrf2-mediated signaling pathway, as indicated by the increased expression of Nrf2, HO-1, GCLM, and NQO1. Moreover, PQQ inhibited the NLRP3 inflammatory pathway, as indicated by the reduced expression of NLRP3, ASC, and Caspase-1. SIGNIFICANCE: Our results suggest that PQQ protects against CTX-induced nephrotoxicity, probably by activating the Nrf2-mediated antioxidant pathway and inhibiting the NLRP3 inflammatory pathway.

Nuclear respiratory factor 1 (NRF-1) upregulates the expression and function of reduced folate carrier (RFC) at the blood-brain barrier.

Folates are important for neurodevelopment and cognitive function. Folate transport across biological membranes is mediated by three major pathways: folate receptor alpha (FRα), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC). Brain folate transport primarily occurs at the choroid plexus through FRα and PCFT; inactivation of these transport systems results in suboptimal folate levels in the cerebrospinal fluid (CSF) causing childhood neurological disorders. Our group has reported that upregulation of RFC at the blood-brain barrier (BBB) through interactions with specific transcription factors, that is, vitamin D receptor (VDR) could increase brain folate delivery. This study investigates the role of nuclear respiratory factor 1 (NRF-1) in the regulation of RFC at the BBB. Activation of NRF-1/PGC-1α signaling through treatment with its specific ligand, pyrroloquinoline quinone (PQQ), significantly induced RFC expression and transport activity in hCMEC/D3 cells. In contrast, transfection with NRF-1 or PGC-1α targeting siRNA downregulated RFC functional expression in the same cell system. Applying chromatin immunoprecipitation (ChIP) assay, we further demonstrated that PQQ treatment increased NRF-1 binding to putative NRF-1 binding sites within the SLC19A1 promoter, which encodes for RFC. Additionally, in vivo treatment of wild type mice with PQQ-induced RFC expression in isolated mouse brain capillaries. Together, these findings demonstrate that NRF-1/PGC-1α activation by PQQ upregulates RFC functional expression at the BBB and could potentially enhance brain folate uptake.

Pyrroloquinoline Quinone Inhibits Oxidative Stress in Rats with Diabetic Nephropathy.

BACKGROUND Diabetic nephropathy (DN) is one of the chronic microvascular complications of diabetes. This study focused on the protective effects of pyrroloquinoline quinone (PQQ) on oxidative stress (OS) in DN. MATERIAL AND METHODS Thirty Sprague Dawley rats were randomly selected for this study; 10 rats were randomly selected as the control group. The other 20 rats were established for the DN model. After establishment of the successful model, the DN model rats were randomly divided into a DN group and a PQQ group. The PQQ group was fed with a PQQ diet. Blood urea nitrogen (BUN), serum creatinine (SCr), and blood glucose levels were measured in each group, and OS-related protein expression and AMPK pathway were detected by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). At the same time, we constructed a DN model by culturing NRK-52E cells with high glucose to detect the molecular mechanisms. RESULTS The kidney function of the DN group was significantly decreased, SCr and BUN levels were significantly increased, and the renal structure under the microscope was disordered, and interstitial edema was obvious. The expression of SOD1, SOD2, GPX1, and GPX3 were significantly decreased, and the level of reactive oxygen species (ROS) was significantly increased. PQQ treatment can effectively alleviate renal function, improve structural damage, and inhibit OS. In vivo, PQQ can effectively inhibit high glucose-induced OS damage and activate the AMPK/FOXO3a signaling pathway. CONCLUSIONS PQQ improves renal structural damage and functional damage, and protects kidney cells in DN by inhibiting OS, which may be related to activating the AMPK/FOXO3a pathway.

Pyrroloquinoline Quinine and LY294002 Changed Cell Cycle and Apoptosis by Regulating PI3K-AKT-GSK3ß Pathway in SH-SY5Y Cells.

To verify the role of PI3K-AKT-GSK3ß pathway during manganese (Mn)-induced cell death, apoptosis, related indicators were investigated. SH-SY5Y cells were directly exposed to different concentrations of MnCl2. Then, cell viability, apoptosis, necrosis rate, and cell cycle were detected by MTT, FITC Annexin V Apoptosis Detection Kit with PI and PI staining. Then, in two intervention groups, cells were preconditioned with agonist (PQQ) and suppressant (LY294002). The cell viability decreased with a dose-response relationship (p < 0.05), while apoptosis and necrosis increased (p < 0.05). The ratio of G0/G1 and G2/M also decreased, but the percentage of S phase increased (p < 0.05). During above process, PI3K-AKT-GSK3ß pathway was involved by regulating the expression of PI3K, AKT, p-AKT, and GSK3ß (p < 0.05). For further research, cell cycle and apoptosis were detected pretreatment with PQQ and LY294002 before Mn exposure. The result showed cell ability, apoptosis, and necrosis rate changed obviously compared with non-pretreated group (p < 0.05). The variance of G0/G1 and G2/M ratio and percentage of S phase were also different, especially in 2.0 mM (p < 0.05). Mn can cause apoptosis and necrosis, varying cell cycle of SH-SY5Y cells, which could be changed by PQQ and LY294002 by regulating PI3K-AKT-GSK3ß pathway.

Pyrroloquinoline quinone delays inflammaging induced by TNF-α through the p16/p21 and Jagged1 signalling pathways.

Previous studies on the longevity effect of pyrroloquinoline quinine (PQQ) on nematode worms have revealed that PQQ can enhance the antioxidant capacity of nematode worms, thus extending the lifespan of the worms. The induction and development of cellular senescence are closely connected with inflammatory reactions. The aim of this study was to determine the effect of PQQ and ageing factors on senescent cells. To this end, we cultivated human embryonic lung fibroblasts in nutrient solution with or without tumour necrosis factor-alpha (TNF-α) to establish an inflammaging model in vitro. The cells were preincubated with or without PQQ to determine if PQQ had any anti-inflammaging effect. More senescent cells were detected with the addition of TNF-α than without (P < .01). The ratio of senescent cells to non-senescent cells in the TNF-α group was greater than that in the control group (P < .01). When cells were preincubated with PQQ prior to TNF-α treatment, there were fewer senescent cells than those in the control group, which was not pretreated with PQQ (P < .05). The same tendency was noted with regard to p21, p16, and Jagged1. In summary, we used TNF-α, a well-known pro-inflammatory cytokine associated with inflammaging, to establish an in vitro inflammaging model and provided evidence that PQQ delays TNF-α -induced cellular senescence and has anti-inflammaging properties.

Pyrroloquinoline quinine ameliorates doxorubicin-induced autophagy-dependent apoptosis via lysosomal-mitochondrial axis in vascular endothelial cells.

The cardiotoxicity of doxorubicin (DOX) limits its clinical use in the treatment of a variety of solid tumors and malignant hematologic disease. However, the mechanism by which it causes cardiotoxicity is not fully understood. Apoptosis has been regarded as one of mechanisms underlying the cardiotoxic effects of DOX. In our study, we found that treatment of human umbilical vein endothelial cells (HUVECs) with DOX induced autophagy and apoptosis in a dose- and time-dependent manner. Treatment with DOX induced autophagy at earlier time (3 h), then lysosomal membrane permeabilization (LMP) altered after treatment for 12 h which followed by the release of cathepsin D (CTSD). Lysosome-associated membrane proteins-1 and -2 (LAMP1 and LAMP2) were decreased in DOX-treated cells. Additionally, DOX induced the collapse of mitochondrial transmembrane potential, reduction of translocase of the outer mitochondrial membrane-20 (TOM-20), and release of cytochrome c. Furthermore, autophagy inhibitor 3-MA relieved DOX-induced apoptosis as assessed by the expression of cleaved caspase-3, cleaved caspase-9 and TUNEL assay. CTSD inhibitor, pepstatin A, upregulated TOM-20 and suppressed the mitochondria release of cytochrome c as well as apoptosis under DOX stress. Pyrroloquinoline quinine (PQQ), a new B vitamin, ameliorated aforementioned phenomenon. In conclusion, our results suggested that DOX-induced apoptosis was autophagy-dependent via lysosomal-mitochondrial axis. PQQ had an ability to protect cell from autophagy-dependent apoptosis induced by DOX via lysosomal-mitochondrial axis to some extent. This study provided new mechanistic insight toward understanding the pathogenesis of DOX-induced cardiotoxicity and the protection effect of PQQ.

Pyrroloquinoline quinone improves abnormal functional development of whisker-mediated tactile perception and social behaviors caused by neonatal whisker trimming.

Abnormalities in tactile perception and response, such as sensory defensiveness, are core features of autism spectrum disorder (ASD) and may be associated with impaired communication skills. However, the influences of tactile perception deficits on the development of social behaviors and neuronal circuits related to emotional regulation of social interactions remain unclear. Whiskers are the most important tactile apparatus in rodents. We previously reported that adult mice receiving bilateral whisker trimming for 10 days after birth (BWT10) exhibited deficits in whisker-mediated tactile discrimination, abnormal social behaviors, and hyperactivity of brain emotional systems under psychological stress. Pyrroloquinoline quinone (PQQ) is an essential nutrient with important roles in central nervous system development and function through modulation of glutamatergic N-methyl-d-aspartate receptor (NMDAR) activity. Here we examined the effect of neonatal PQQ administration on the behavioral abnormalities of BWT10 mice. PQQ treatment significantly reversed abnormal social behavior in adult BWT10 mice as detected by three-chamber social interaction and social dominance tube tests, and improved whisker perception as revealed by the gap-crossing test. In addition, PQQ reversed hyperactivity in emotional systems as evidenced by c-Fos expression pattern following elevated-platform stress. These data suggest that PQQ may be a promising candidate therapeutic drug for neurodevelopmental disorders such as ASD.