[Effect of Tetrastigma hemsleyanum on sepsis and mechanism based on network pharmacology and experimental verification]

Based on network pharmacology and in vivo experiment, this study explored the therapeutic effect of Tetrastigma hemsle-yanum(SYQ) on sepsis and the underlying mechanism. The common targets of SYQ and sepsis were screened out by network pharmacology, and the "SYQ-component-target-sepsis" network was constructed. The protein-protein interaction(PPI) network was established by STRING. Gene Ontology(GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment were performed based on DAVID to predict the anti-sepsis mechanism of SYQ. The prediction results of network pharmacology were verified by animal experiment. The network pharmacology results showed that the key anti-sepsis targets of SYQ were tumor necrosis factor(TNF), interleukin(IL)-6, IL-1β, IL-10, and cysteinyl asparate specific proteinase 3(caspase-3), which were mainly involved in Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear factor kappaB(NF-κB) signaling pathway. The results of animal experiment showed that SYQ can decrease the content of C-reactive protein(CRP), procalcitonin(PCT), lactate dehydrogenase(LDH), IL-6, TNF-α, and IL-1β, increase the content of IL-10, and down-regulate the protein levels of Bcl-2-associa-ted X(Bax)/B-cell lymphoma 2(Bcl2), cleaved caspase-3, TLR4, MyD88, and p-NF-κB p65/NF-κB p65. In summary, SYQ plays an anti-inflammatory role in the treatment of sepsis by acting on the key genes related to inflammation and apoptosis, such as TNF-α, IL-6, IL-lβ, IL-10, Bax, Bcl2, and cleaved caspase-3. The mechanism is the likelihood that it suppresses the TLR4/MyD88/NF-κB signaling pathway, which verifies relative prediction results of network pharmacology.

Network Pharmacology-Based Combined with Experimental Validation Study to Explore the Underlying Mechanism of Agrimonia pilosa Ledeb. Extract in Treating Acute Myocardial Infarction

Purpose

The network pharmacology approach and validation experiment were performed to investigate the potential mechanisms of Agrimonia pilosa Ledeb. (APL) extract against acute myocardial infarction (AMI).

Methods

The primary compounds of APL extract were identified by High-Performance Liquid Chromatography (HPLC) analysis. The intersecting targets of active compounds and AMI were determined via network pharmacology analysis. A mouse model of AMI was established by subcutaneous injection of isoproterenol (Iso). Mice were treated with APL extract by intragastric administration. We assessed the effects of APL extract on the electrocardiography (ECG), cardiac representative markers, representative indicators of oxidative stress, pathological changes, and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, as well as apoptosis-related indicators in the mice.

Results

Five candidate compounds were identified in APL extract. Enrichment analyses indicated that APL extract could exert myocardial protective effects via the PI3K/Akt pathway. ST segment elevation and increased heart rate were obviously reversed in APL extract groups compared to Iso group. We also detected significant decreases in lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase MB (CK-MB), malondialdehyde (MDA), and reactive oxygen species (ROS), as well as a significant increase in superoxide dismutase activities (SOD) after APL extract treatment. In addition, APL extract markedly decreased the number of apoptotic cardiomyocytes after AMI. In the APL extract groups of AMI mice, there were increased expression levels of p-PI3K, p-Akt, and B-cell lymphoma-2 (Bcl-2) protein, and there were decreases in Bcl-2-associated X (Bax), cysteinyl aspartate-specific proteases-3 (caspase-3), and cleaved-caspase-3 protein expression levels, as well as the Bax/Bcl-2 ratio.

Conclusion

APL extract had a protective effect against Iso-induced AMI. APL extract could ameliorate AMI through antioxidant and anti-apoptosis actions which may be associated with the activation of the PI3K/Akt signaling pathway.

Skin transcriptomic analysis and immune-related gene expression of golden pompano (Trachinotus ovatus) after Amyloodinium ocellatum infection

Amyloodiniosis is a severe disease of marine and brackish water fish caused by Amyloodinium ocellatum. Golden pompano (Trachinotus ovatus) is often repeatedly infected by A. ocellatum, leading to extensive mortality. However, little is known about the immune response mechanisms of the T. ovatus following reinfection with A. ocellatum. In this study, an extensive analysis at the transcriptome level of T. ovatus skin was carried out at 24 h post-infection by A. ocellatum. During the transcriptomic analysis, 1367 differentially expressed genes (DEGs) in the skin of T. ovatus under A. ocellatum infection and control conditions were obtained. In Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotated analyses, the DEGs were significantly enriched in the immune-related pathways. To better understand the immune-related gene expression dynamics, a quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to assess the primary and secondary infection groups of T. ovatus at different stages (3 h, 12 h, 24 h, 48 h and, 72 h post-infection) of infection with A.ocellatum. The results showed that innate immunity-related genes [interleukin (IL-8), chemokine ligand 3 (CCL3), toll-like receptor 7 (TLR7), and G-type lysosome (LZM g)] and adaptive immunity-related gene [major histocompatibility complex (MHC) alpha antigen I and MHC alpha antigen II] expression levels in the primary and secondary infection groups were significantly increased compared to the control group. The expression of MHC I and MHC II was more rapidly upregulated in the secondary infection group compared with the primary infection group after A.ocellatum infection. However, no significant differences of A.ocellatum load were observed in primary and secondary infection groups. In addition, the serum of the primary infection group had significantly higher concentrations of triglyceride (TG), higher alanine transaminase (ALT), aspartate transaminase (AST), and lactate dehydrogenase (LDH) activities than the control group. This study contributes to understanding the defense mechanisms in fish skin against ectoparasite infection.

H151, A SMALL MOLECULE INHIBITOR OF STING AS A NOVEL THERAPEUTIC IN INTESTINAL ISCHEMIA-REPERFUSION INJURY

BACKGROUND

Intestinal ischemia-reperfusion (I/R) injury is a severe disease associated with high mortality. Stimulator of interferon genes (STING) is an intracellular protein that is activated by cytosolic DNA and is implicated in I/R injury, resulting in transcription of type I interferons (IFN-α and IFN-β) and other proinflammatory molecules. Extracellular cold-inducible RNA-binding protein (eCIRP), a damage-associated molecular pattern, induces STING activation. H151 is a small molecule inhibitor of STING that has not yet been studied as a potential therapeutic. We hypothesize that H151 reduces inflammation, tissue injury, and mortality after intestinal I/R. Methods: In vitro, RAW264.7 cells were pretreated with H151 then stimulated with recombinant murine (rm) CIRP, and IFN-β levels in the culture supernatant were measured at 24 hours after stimulation. In vivo, male C57BL/6 mice were subjected to 60-minute intestinal ischemia via superior mesenteric artery occlusion. At the time of reperfusion, mice were intraperitoneally instilled with H151 (10 mg/kg BW) or 10% Tween-80 in PBS (vehicle). Four hours after reperfusion, the small intestines, lungs, and serum were collected for analysis. Mice were monitored for 24 hours after intestinal I/R to assess survival. Results: In vitro, H151 reduced rmCIRP-induced IFN-β levels in a dose-dependent manner. In vivo, intestinal levels of pIRF3 were increased after intestinal I/R and decreased after H151 treatment. There was an increase in serum levels of tissue injury markers (lactate dehydrogenase, aspartate aminotransferase) and cytokine levels (interleukin 1β, interleukin 6) after intestinal I/R, and these levels were decreased after H151 treatment. Ischemia-reperfusion-induced intestinal and lung injury and inflammation were significantly reduced after H151 treatment, as evaluated by histopathologic assessment, measurement of cell death, chemokine expression, neutrophil infiltration, and myeloperoxidase activity. Finally, H151 improved the survival rate from 41% to 81% after intestinal I/R. Conclusions: H151, a novel STING inhibitor, attenuates the inflammatory response and reduces tissue injury and mortality in a murine model of intestinal I/R. H151 shows promise as a potential therapeutic in the treatment of this disease.

HSP70 protects H9C2 cells from hypoxia and reoxygenation injury through STIM1/IP3R

Hypoxia/reoxygenation (H/R) is used as an in vivo model of ischemia/reperfusion injury, and myocardial ischemia can lead to heart disease. Calcium overload is an important factor in myocardial ischemia-reperfusion injury and can lead to apoptosis of myocardial cells. Therefore, it is of great clinical importance to find ways to regulate calcium overload and reduce apoptosis of myocardial cells, and thus alleviate myocardial ischemia-reperfusion injury. There is evidence that heat shock protein 70 (HSP70) has a protective effect on the myocardium, but the exact mechanism of this effect is not completely understood. Stromal interaction molecule 1 and inositol 1,4,5-triphosphate receptor (STIM/1IP3R) play an important role in myocardial ischemia-reperfusion injury. Therefore, this study aimed to investigate whether HSP70 plays an anti-apoptotic role in H9C2 cardiomyocytes by regulating the calcium overload pathway through STIM1/IP3R. Rat H9C2 cells were subjected to transient oxygen and glucose deprivation (incubated in glucose-free medium and hypoxia for 6 h) followed by re-exposure to glucose and reoxygenation (incubated in high glucose medium and reoxygenation for 4 h) to simulate myocardial ischemia reperfusion-induced cell injury. H9C2 cell viability was significantly decreased, and lactate dehydrogenase (LDH) release and apoptosis were significantly increased after oxygen and glucose deprivation. Transfection of HSP70 into H9C2 cells could reduce the corresponding effect, increase cell viability and anti-apoptotic signal pathway, and reduce the apoptotic rate and pro-apoptotic signal pathway. After hypoxia and reoxygenation, the expression of STIM1/IP3R and intracellular calcium concentration of HSP70-overexpressed H9C2 cells were significantly lower than those of hypoxia cells. Similarly, direct silencing of STIM1 by siRNA significantly increased cell viability and expression of anti-apoptotic protein Bcl-2 and decreased apoptosis rate and expression of pro-apoptotic protein BAX. These data are consistent with HSP70 overexpression. These results suggest that HSP70 abrogates intracellular calcium overload by inhibiting upregulation of STIM1/IP3R expression, thus reducing apoptosis in H9C2 cells and playing a protective role in cardiomyocytes.

Japanese Flounder HMGB1: A DAMP Molecule That Promotes Antimicrobial Immunity by Interacting with Immune Cells and Bacterial Pathogen

High mobility group box (HMGB) proteins are DNA-associated proteins that bind and modulate chromosome structures. In mammals, HMGB proteins can be released from the cell nucleus and serve as a damage-associated molecular pattern (DAMP) under stress conditions. In fish, the DAMP function of HMGB proteins in association with bacterial infection remains to be investigated. In this study, we examined the immunological functions of two HMGB members, HMGB1 and HMG20A, of Japanese flounder. HMGB1 and HMG20A were expressed in multiple tissues of the flounder. HMGB1 was released from peripheral blood leukocytes (PBLs) upon bacterial challenge in a temporal manner similar to that of lactate dehydrogenase release. Recombinant HMGB1 bound to PBLs and induced ROS production and the expression of inflammatory genes. HMGB1 as well as HMG20A also bound to various bacterial pathogens and caused bacterial agglutination. The bacteria-binding patterns of HMGB1 and HMG20A were similar, and the binding of HMGB1 competed with the binding of HMG20A but not vice versa. During bacterial infection, HMGB1 enhanced the immune response of PBLs and repressed bacterial invasion. Collectively, our results indicate that flounder HMGB1 plays an important role in antimicrobial immunity by acting both as a modulator of immune cells and as a pathogen-interacting DAMP.

Effects of the green tea catechin epigallocatechin-3-gallate on Streptococcus mutans planktonic cultures and biofilms: systematic literature review of in vitro studies

This study aimed at performing a systematic review of the literature on the effects of epigallocatechin-3-gallate (EGCG) on Streptococcus mutans planktonic cultures and biofilms. The selected references demonstrated that EGCG suppresses S. mutans acid production by inhibiting the activity of enzymes such as lactate dehydrogenase and FIF0-ATPase. Regarding virulence factors, one study reported a reduction in soluble and insoluble polysaccharide synthesis, another demonstrated that EGCG inhibited GTase activity, and another showed effects of EGCG on the expression of gtf B, C, and D. The effects of EGCG on S. mutans biofilms were reported only by 2 of the selected studies. Moreover, high variability in effective concentrations and microbial assessment methods were observed. The literature suggests that EGCG has effects against S. mutans planktonic cells viability and virulence factors. However, the literature lacks studies with appropriate biofilm models to evaluate the precise effectiveness of EGCG against S. mutans biofilms.

LDHB Overexpression Can Partially Overcome T Cell Inhibition by Lactic Acid

Accelerated glycolysis leads to secretion and accumulation of lactate and protons in the tumor environment and determines the efficacy of adoptive T cell and checkpoint inhibition therapy. Here, we analyzed effects of lactic acid on different human CD4 T cell subsets and aimed to increase CD4 T cell resistance towards lactic acid. In all CD4 T cell subsets analyzed, lactic acid inhibited metabolic activity (glycolysis and respiration), cytokine secretion, and cell proliferation. Overexpression of the lactate-metabolizing isoenzyme LDHB increased cell respiration and mitigated lactic acid effects on intracellular cytokine production. Strikingly, LDHB-overexpressing cells preferentially migrated into HCT116 tumor spheroids and displayed higher expression of cytotoxic effector molecules. We conclude, that LDHB overexpression might be a promising strategy to increase the efficacy of adoptive T cell transfer therapy.

Protective effects of methanolic leaf extracts of Monanthotaxis caffra against aflatoxin B1-induced hepatotoxicity in rats

Aflatoxins are potent hepatotoxic and carcinogenic secondary metabolites produced by toxigenic fungi. The present study investigated the protective effect of methanolic leaf extracts of Monanthotaxis caffra (MLEMC) against aflatoxin B1-induced toxicity in male Sprague-Dawley rats. The rats were randomly divided into 6 groups of 8 animals each. Five groups were administered orally for seven days with three different concentrations of MLEMC (100 mg/kg, 200 mg/kg and 300 mg/kg), curcumin (10 mg/kg) or vehicle (25% propylene glycol). The following day, these groups were administered 1 mg/kg b.w. of aflatoxin B1 (AFB1). The experiment was terminated three days after administration of AFB1. Group 6 represented untreated healthy control. Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatinine and liver histopathology were evaluated. Methanolic leaf extracts of M. caffra decreased the levels of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase and creatinine in the sera of rats as compared with the AFB1 intoxicated group. Co-administration of MLEMC improved the histological characteristics of the hepatocytes in contrast to the AFB1 treated group, which had mild to severe hepatocellular injuries including bile duct proliferation, bile duct hyperplasia, lymphoplasmacytic infiltrate and fibrosis. Extracts of M. caffra were beneficial in mitigating the hepatotoxic effects of AFB1 in rats by reducing the levels of liver enzymes and preventing hepatic injury.

Protective Effect of Amino Acids on the Muscle Injury of Aerobics Athletes after Endurance Exercise Based on CT Images

During the training process, the aerobics athletes gradually increase their technical movements, the appreciation of the movements has been gradually improved, and the injuries of the athletes themselves have also gradually become serious. Based on CT image analysis, we study the protective effect of amino acids on aerobics athletes' muscle injury after endurance exercise. There are three major substance metabolism disorders in patients with muscle sclerosis, which are mainly manifested as decreased glucose tolerance and insulin resistance. Some patients develop muscle-derived diabetes. At the same time, the synthesis of lipids such as cholesterol and apolipoproteins decreases, the production of ketone bodies increases and the body uses more ketones for energy. The BCAA/AAA factor refers to the branched-chain amino acid/aromatic amino acid (BCAA/AAA) value. In amino acid metabolism, plasma albumin decreased significantly, the ratio of amino acids was unbalanced, and BCAA/AAA decreased, which was more likely to induce muscular encephalopathy. Using computer tomography (CT) to study the protective effect of amino acids on muscle injury, 32 aerobics athletes were randomly divided into an intervention group (Ig) and a control group (CG), each with 16 people. After 64-slice spiral CT scanning of muscles and three-dimensional reconstruction, the intervention group and the control group participated in aerobic endurance training 3 weeks in advance to establish a muscle microinjury model. The intervention group took the preprepared BCAA, while the control group did not take it. After three weeks of training, there will be one hour and three hours of aerobics competition. We need to detect changes in blood glucose (BS), creatine kinase (SCK), lactate dehydrogenase (LD), alanine (ALA), and alanine aminotransferase (AA) before and after exercise and 1 hour after exercise and record AVS athletes' pain analysis table. We successfully established the muscle injury model, letting all athletes' VAS score in 6-8 points; after 1 hour of exercise, the measurement results were the same as those of 2 hours. Therefore, after endurance training, the blood glucose content of the intervention group gradually decreased and returned to the original level after 2 hours of exercise, while the control group was lower than the level of exercise after 2 hours of exercise; the content of alanine in the two groups decreased more after 2 hours of exercise; the results of serum creatine kinase in the intervention group were higher than those in the control group after exercise. In the intervention group, lactate dehydrogenase increased rapidly at 2 hours after exercise; the alanine aminotransferase in the intervention group increased after exercise, but there was no significant change in the control group. It is also concluded that the longer the exercise time and the more energy consumption, the more effective the branched-chain amino acids supplement will be. The obtained imaging data can provide a more intuitive and accurate basis for the scientific selection of athletes, and amino acids can promote the synthesis of hormones, accelerate the synthesis of proteins and other products, reduce the content of creatine kinase in the blood, and protect the rapid recovery of muscle damage.

Is the level of serum lactate dehydrogenase a potential biomarker for glucose monitoring with type 2 diabetes mellitus?

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is a metabolic disorder due to defects in insulin secretion or insulin resistance leading to the dysfunction and damage of various organs. To improve the clinical evaluation of short-term blood glycemic variability monitoring, it is critical to identify another blood cell status and nutritional status biomarker that is less susceptible to interference. This study identifies the significance of serum lactate dehydrogenase (LDH) level among T2DM patients treated in outpatient clinics and investigates the relationship of LDH level with other variables.

METHODS

This study comprised 72 outpatients with T2DM over 20 years of age. Blood samples were collected followed by a hematological analysis of serum glycated albumin (GA), LDH, fasting blood glucose, glycosylated hemoglobin, C-peptide, and insulin antibodies (insulin Ab).

RESULTS

Serum LDH level was significantly correlated with GA (p < 0.001), C-peptide (p = 0.04), insulin Ab (p = 0.03), and thyroid-stimulating hormone (TSH) levels (p = 0.04). Hence, we performed a linear regression analysis of hematological markers. GA (p < 0.001, r² = 0.45) and insulin Ab (p < 0.001, r² = 0.40) were significantly associated with LDH level. Then, we classified patients into low (<200 U/L) and high (≥200 U/L) serum LDH level groups, respectively. GA (p < 0.001), C-peptide (p = 0.001), and TSH (p = 0.03) showed significant differences in patients with high LDH levels compared with those in patients with low LDH levels.

CONCLUSION

In conclusion, we suggested that LDH level was independent of long-term but associated with short-term blood glucose monitoring. The results indicated that changes in serum GA induced cell damage and the abnormal elevation of the serum level of LDH may occur simultaneously with glycemic variability. It has been reported that many biomarkers are being used to observe glucose variability in T2DM. However, LDH could provide a more convenient and faster evaluation of glycemic variability in T2DM.

Combined proteomic and lipidomic studies in Pompe disease allow a better disease mechanism understanding

Pompe disease (PD) is caused by deficiency of the enzyme acid α-glucosidase resulting in glycogen accumulation in lysosomes. Clinical symptoms include skeletal myopathy, respiratory failure, and cardiac hypertrophy. We studied plasma proteomic and lipidomic profiles in 12 PD patients compared to age-matched controls. The proteomic profiles were analyzed by nLC-MS/MS SWATH method. Wide-targeted lipidomic analysis was performed by LC-IMS/MS, allowing to quantify >1100 lipid species, spanning 13 classes. Significant differences were found for 16 proteins, with four showing the most relevant changes (GPLD1, PON1, LDHB, PKM). Lipidomic analysis showed elevated levels of three phosphatidylcholines and of the free fatty acid 22:4, and reduced levels of six lysophosphatidylcholines. Up-regulated glycolytic enzymes (LDHB and PKM) are involved in autophagy and glycogen metabolism, while down-regulated PON1 and GPLD1 combined with lipidomic data indicate an abnormal phospholipid metabolism. Reduced GPLD1 and dysregulation of lipids with acyl-chains characteristic of GPI-anchor structure suggest the potential involvement of GPI-anchor system in PD. Results of proteomic analysis displayed the involvement of multiple cellular functions affecting inflammatory, immune and antioxidant responses, autophagy, Ca²⁺ -homeostasis, and cell adhesion. The combined multi-omic approach revealed new biosignatures in PD, providing novel insights in disease pathophysiology with potential future clinical application.

R-2-hydroxyglutarate attenuates aerobic glycolysis in leukemia by targeting the FTO/m6A/PFKP/LDHB axis

R-2-hydroxyglutarate (R-2HG), a metabolite produced by mutant isocitrate dehydrogenases (IDHs), was recently reported to exhibit anti-tumor activity. However, its effect on cancer metabolism remains largely elusive. Here we show that R-2HG effectively attenuates aerobic glycolysis, a hallmark of cancer metabolism, in (R-2HG-sensitive) leukemia cells. Mechanistically, R-2HG abrogates fat-mass- and obesity-associated protein (FTO)/N6-methyladenosine (m6A)/YTH N6-methyladenosine RNA binding protein 2 (YTHDF2)-mediated post-transcriptional upregulation of phosphofructokinase platelet (PFKP) and lactate dehydrogenase B (LDHB) (two critical glycolytic genes) expression and thereby suppresses aerobic glycolysis. Knockdown of FTO, PFKP, or LDHB recapitulates R-2HG-induced glycolytic inhibition in (R-2HG-sensitive) leukemia cells, but not in normal CD34+ hematopoietic stem/progenitor cells, and inhibits leukemogenesis in vivo; conversely, their overexpression reverses R-2HG-induced effects. R-2HG also suppresses glycolysis and downregulates FTO/PFKP/LDHB expression in human primary IDH-wild-type acute myeloid leukemia (AML) cells, demonstrating the clinical relevance. Collectively, our study reveals previously unrecognized effects of R-2HG and RNA modification on aerobic glycolysis in leukemia, highlighting the therapeutic potential of targeting cancer epitranscriptomics and metabolism.

Novel Prokaryotic CRISPR-Cas12a-Based Tool for Programmable Transcriptional Activation and Repression

Transcriptional perturbation using inactivated CRISPR-nucleases (dCas) is a common method in eukaryotic organisms. While rare examples of dCas9-based tools for prokaryotes have been described, multiplexing approaches are limited due to the used effector nuclease. For the first time, a dCas12a derived tool for the targeted activation and repression of genes was developed. Therefore, a previously described SoxS activator domain was linked to dCas12a to enable the programmable activation of gene expression. A proof of principle of transcriptional regulation was demonstrated on the basis of fluorescence reporter assays using the alternative host organism Paenibacillus polymyxa as well as Escherichia coli. Single target and multiplex CRISPR interference targeting the exopolysaccharide biosynthesis of P. polymyxa was shown to emulate polymer compositions of gene knockouts. The simultaneous expression of 11 gRNAs targeting multiple lactate dehydrogenases and a butanediol dehydrogenase resulted in decreased lactate formation, as well as an increased butanediol production in microaerobic fermentation processes. Even though Cas12a is more restricted in terms of its genomic target sequences compared to Cas9, its ability to efficiently process its own guide RNAs in vivo makes it a promising tool to orchestrate sophisticated genetic reprogramming of bacterial cells or to screen for engineering targets in the genome. The developed tool will accelerate metabolic engineering efforts in the alternative host organism P. polymyxa and might be also applied for other bacterial cell factories.

Cancer/testis antigen LDHC promotes proliferation and metastasis by activating the PI3K/Akt/GSK-3β-signaling pathway and the in lung adenocarcinoma

The cancer/testis antigen lactate dehydrogenase-C4 (LDHC) is a specific isoenzyme of the LDH family that regulates invasion and metastasis in some malignancies; however, little is known regarding its role in progression of lung adenocarcinoma (LUAD). Thus, we investigated LDHC expression by immunohistochemistry, and analyzed its clinical significance in 88 LUAD specimens. The role and molecular mechanisms subserving LDHC in cellular proliferation, migration, and invasion were explored both in vitro and in vivo. As a result, we found that high LDHC expression was significantly correlated with clinicopathological features of aggressive LUAD and a poor prognosis. Overexpression of LDHC induced LUAD cells to produce lactate and ATP, increased their metastatic and invasive potential-, and accelerated xenograft tumor growth. We further demonstrated that overexpression of LDHC affected the expression of cell proliferation-related proteins (cyclin D1 and c-Myc) and epithelial-mesenchymal transition (EMT)-related proteins (MMP-2, MMP-9, E-cadherin, Vimentin, Twist, Slug, and Snail) both in vitro and in vivo. Finally, excessive activation of LDHC enhanced the phosphorylation levels of AKT and GSK-3β, revealing activation of the PI3K/Akt/GSK-3β oncogenic-signaling pathways. Treatment with a PI3K inhibitor reversed the effects of LDHC overexpression by inhibiting cellular proliferation, migration, and invasion, with diminished levels of p-Akt and p-GSK3β. PI3K inhibition also reversed cell proliferation-related and EMT-related proteins in LDHC-overexpressing A549 cells. In conclusion, LDHC promotes proliferation, migration, invasion, and EMT in LUAD cells via activation of the PI3K/Akt/GSK-3β pathway.

Pressure tolerance of deep-sea enzymes can be evolved through increasing volume changes in protein transitions: a study with lactate dehydrogenases from abyssal and hadal fishes

We explore the principles of pressure tolerance in enzymes of deep-sea fishes using lactate dehydrogenases (LDH) as a case study. We compared the effects of pressure on the activities of LDH from hadal snailfishes Notoliparis kermadecensis and Pseudoliparis swirei with those from a shallow-adapted Liparis florae and an abyssal grenadier Coryphaenoides armatus. We then quantified the LDH content in muscle homogenates using mass-spectrometric determination of the LDH-specific conserved peptide LNLVQR. Existing theory suggests that adaptation to high pressure requires a decrease in volume changes in enzymatic catalysis. Accordingly, evolved pressure tolerance must be accompanied with an important reduction in the volume change associated with pressure-promoted alteration of enzymatic activity ( Δ V PP ∘ ). Our results suggest an important revision to this paradigm. Here, we describe an opposite effect of pressure adaptation-a substantial increase in the absolute value of Δ V PP ∘ in deep-living species compared to shallow-water counterparts. With this change, the enzyme activities in abyssal and hadal species do not substantially decrease their activity with pressure increasing up to 1-2 kbar, well beyond full-ocean depth pressures. In contrast, the activity of the enzyme from the tidepool snailfish, L. florae, decreases nearly linearly from 1 to 2500 bar. The increased tolerance of LDH activity to pressure comes at the expense of decreased catalytic efficiency, which is compensated with increased enzyme contents in high-pressure-adapted species. The newly discovered strategy is presumably used when the enzyme mechanism involves the formation of potentially unstable excited transient states associated with substantial changes in enzyme-solvent interactions.

Biophysical and Biochemical Characterization of TP0037, a d-Lactate Dehydrogenase, Supports an Acetogenic Energy Conservation Pathway in Treponema pallidum

A longstanding conundrum in Treponema pallidum biology concerns how the spirochete generates sufficient energy to fulfill its complex pathogenesis processes during human syphilitic infection. For decades, it has been assumed that the bacterium relies solely on glucose catabolism (via glycolysis) for generation of its ATP. However, the organism's robust motility, believed to be essential for human tissue invasion and dissemination, would require abundant ATP likely not provided by the parsimony of glycolysis. As such, additional ATP generation, either via a chemiosmotic gradient, substrate-level phosphorylation, or both, likely exists in T. pallidum Along these lines, we have hypothesized that T. pallidum exploits an acetogenic energy conservation pathway that relies on the redox chemistry of flavins. Central to this hypothesis is the apparent existence in T. pallidum of an acetogenic pathway for the conversion of d-lactate to acetate. Herein we have characterized the structural, biophysical, and biochemical properties of the first enzyme (d-lactate dehydrogenase [d-LDH]; TP0037) predicted in this pathway. Binding and enzymatic studies showed that recombinant TP0037 consumed d-lactate and NAD+ to produce pyruvate and NADH. The crystal structure of TP0037 revealed a fold similar to that of other d-acid dehydrogenases; residues in the cofactor-binding and active sites were homologous to those of other known d-LDHs. The crystal structure and solution biophysical experiments revealed the protein's propensity to dimerize, akin to other d-LDHs. This study is the first to elucidate the enzymatic properties of T. pallidum's d-LDH, thereby providing new compelling evidence for a flavin-dependent acetogenic energy conservation (ATP-generating) pathway in T. pallidumIMPORTANCE Because T. pallidum lacks a Krebs cycle and the capability for oxidative phosphorylation, historically it has been difficult to reconcile how the syphilis spirochete generates sufficient ATP to fulfill its energy needs, particularly for its robust motility, solely from glycolysis. We have postulated the existence in T. pallidum of a flavin-dependent acetogenic energy conservation pathway that would generate additional ATP for T. pallidum bioenergetics. In the proposed acetogenic pathway, first d-lactate would be converted to pyruvate. Pyruvate would then be metabolized to acetate in three additional steps, with ATP being generated via substrate-level phosphorylation. This study provides structural, biochemical, and biophysical evidence for the first T. pallidum enzyme in the pathway (TP0037; d-lactate dehydrogenase) requisite for the conversion of d-lactate to pyruvate. The findings represent the first experimental evidence to support a role for an acetogenic energy conservation pathway that would contribute to nonglycolytic ATP production in T. pallidum.

A D-lactate dehydrogenase from rice is involved in conferring tolerance to multiple abiotic stresses by maintaining cellular homeostasis

D-lactate dehydrogenase (D-LDH) converts D-lactate (the end product of glyoxalase system) to pyruvate and thereby completes the detoxification process of methylglyoxal. D-LDH detoxifies and diverts the stress induced toxic metabolites, MG and D-lactate, towards energy production and thus, protects the cell from their deteriorating effects. In this study, a D-LDH enzyme from rice (OsD-LDH2, encoded by Os07g08950.1) was characterized for its role in abiotic stress tolerance. For this, a combination of in silico, molecular, genetic and biochemical approaches was used. The kinetic analysis revealed OsD-LDH2 to be the most efficient D-LDH enzyme in comparison to D-LDHs from other plant species. Heterologous overexpression of OsD-LDH2 provides tolerance against multiple abiotic stresses in E. coli, yeast and plant system. The analysis of D-LDH mutant and OsD-LDH2 overexpressing transgenic plants uncovered the crucial role of D-LDH in mitigation of abiotic stresses. OsD-LDH2 overexpressing plants maintained lower level of ROS and other toxic metabolites along with better functioning of antioxidant system. This is the first report on correlation of D-LDH with multiple abiotic stress tolerance. Overall, OsD-LDH2 emerged as a promising candidate which can open a new direction for engineering stress tolerant crop varieties by maintaining their growth and yield in unfavorable conditions.

Efficient l-lactic acid production from corncob residue using metabolically engineered thermo-tolerant yeast

Lactic acid is an important industrial product and the production from inexpensive and renewable lignocellulose can reduce the cost and environmental pollution. In this study, a Kluyveromyces marxianus strain which produced lactic acid efficiently from corncob was constructed. Firstly, two of six different lactate dehydrogenases, which from Plasmodium falciparum and Bacillus subtilis, respectively, were proved to be effective for l-lactic acid production. Then, five single genetic modifications were conducted. The overexpression of Saccharomyces cerevisiae proton-coupled monocarboxylate transporter, K. marxianus 6-phosphofructokinase, or disruption of K. marxianus putative d-lactate dehydrogenase enhanced the l-lactic acid accumulation. Finally, the strain YKX071, obtained via combination of above effective genetic engineering, produced 103.00 g/L l-lactic acid at 42 °C with optical purity of 99.5% from corncob residue via simultaneous saccharification and co-fermentation. This study first developed an effective platform for high optical purity l-lactic acid production from lignocellulose using yeast with inexpensive nitrogen sources.

Chitosan oligosaccharides alleviate PM2.5-induced lung inflammation in rats

Air pollution of particulate matter (PM), especially PM_2.5, has become a major public health problem in China. Exploration of therapeutic and preventive measures against PM_2.5 toxicity is of practical significance. The aim of this study was to examine the inhibitory effects of chitosan oligosaccharides (COS) on PM_2.5-induced lung inflammation in rats. Forty SPF (specific pathogen-free) male Wistar rats weighing 200-220 g were randomly divided into four groups: control group, COS group, PM_2.5 group, and PM_2.5+COS group. COS was pre-administered to rats by gavage at a single dose of 500 mg/kg 2 h before intratracheal instillation of PM_2.5 at a single dose of 1.2 mg/kg daily for 3 consecutive days. Normal saline (NS) was used as negative control. Twenty-four hours after the last instillation of PM_2.5, rats were sacrificed and subjected to bronchoalveolar lavage (BAL). The BAL fluids (BALF) were collected for measurement of levels of total proteins, lactate dehydrogenase (LDH), interleukin-1 (IL-1β), IL-8, and tumor necrosis factor-ɑ (TNF-ɑ) using colorimetric or ELISA kits. Levels of total proteins, LDH activities, and pro-inflammatory mediators including IL-1β, IL-8, and TNF-ɑ in BALF of rats in PM_2.5 group significantly increased in comparison with those of the control group. Pre-treatment of rats with COS markedly blocked PM_2.5-induced increase in LDH, IL-8, and TNF-ɑ levels in BALF. In conclusion, PM_2.5 exposure induces rat lung inflammation, which could be ameliorated by the pre-treatment of COS.

Protective effects of effective ingredients of Danshen (Radix Salviae Miltiorrhizae) and Honghua (Flos Carthami) compatibility after rat hippocampal neurons induced by hypoxia injury

OBJECTIVE

To investigate the effective ingredients of Danshen (Radix Salviae Miltiorrhizae) and Honghua (Flos Carthami) (Danhong) on protective properties towards neonatal rat hippocampal neurons under hypoxia condition.

METHODS

Primary culture of neonatal rat hippocampal neurons was used to model hypoxia damage on the hippocampus. Methyl thiazolyl tetrazolium (MTT) assay and preliminary experiments were conducted to identify the four effective ingredients of Danhong, along with the injection of positive drug onto hippocampal neurons at a non-toxic dosage level. The cultured cells were randomly divided into 12 groups: the normal group, model group, positive drug control group and nine compatibility groups of the four effective ingredients. Different test methods were applied to determine lactate dehydrogenasein (LDH), total superoxide dismutase (T-SOD), malondialdehyde (MDA), 6-keto prostaglandin Fla (6-keto-PGF1a), thromboxane B2 (TXB2), mitochondrial membrane potential (MMP), free calcium ions concentration ([Ca2+]i) and early onset cell apoptosis.

RESULTS

Different compatibility groups could inhibit the content of LDH and intracellular calcium overload, increase activity in T-SOD, decrease level of MDA and TXB2, improve level of 6-keto-PGF1a and MMP, and prevent the early onset cell apoptosis.

CONCLUSION

The compatibility of four effective ingredients of Danhong had protective effect toward hippocampi hypoxia. The mechanism might be related to inhibit oxidative stress damage and cell apoptosis, resist thrombosis, and reduce the intracellular calcium ion of overload.

Enhancing Coupled Enzymatic Activity by Colocalization on Nanoparticle Surfaces: Kinetic Evidence for Directed Channeling of Intermediates

Multistep enzymatic cascades are becoming more prevalent in industrial settings as engineers strive to synthesize complex products and pharmaceuticals in economical, environmentally friendly ways. Previous work has shown that immobilizing enzymes on nanoparticles can enhance their activity significantly due to localized interfacial effects, and this enhancement remains in place even when that enzyme's activity is coupled to another enzyme that is still freely diffusing. Here, we investigate the effects of displaying two enzymes with coupled catalytic activity directly on the same nanoparticle surface. For this, the well-characterized enzymes pyruvate kinase (PykA) and lactate dehydrogenase (LDH) were utilized as a model system; they jointly convert phosphoenolpyruvate to lactate in two sequential steps as part of downstream glycolysis. The enzymes were expressed with terminal polyhistidine tags to facilitate their conjugation to semiconductor quantum dots (QDs) which were used here as prototypical nanoparticles. Characterization of enzyme coassembly to two different sized QDs showed a propensity to cross-link into nanoclusters consisting of primarily dimers and some trimers. Individual and joint enzyme activity in this format was extensively investigated in direct comparison to control samples lacking the QD scaffolds. We found that QD association enhances LDH activity by >50-fold and its total turnover by at least 41-fold, and that this high activation appears to be largely due to stabilization of its quarternary structure. When both enzymes are simultaneously bound to the QD surfaces, their colocalization leads to >100-fold improvements in the overall rates of coupled activity. Experimental results in conjunction with detailed kinetic simulations provide evidence that this significant improvement in coupled activity is partially attributable to a combination of enhanced enzymatic activity and stabilization of LDH. More importantly, experiments aimed at disrupting channeled processes and further kinetic modeling suggest that the bulk of the performance enhancement arises from intermediary "channeling" between the QD-colocalized enzymes. A full understanding of the underlying processes that give rise to such enhancements from coupled enzymatic activity on nanoparticle scaffolds can provide design criteria for improved biocatalytic applications.

Catalytic, Computational, and Evolutionary Analysis of the d-Lactate Dehydrogenases Responsible for d-Lactic Acid Production in Lactic Acid Bacteria

d-Lactate dehydrogenase (d-LDH) catalyzes the reversible reaction pyruvate + NADH + H⁺ ↔ lactate + NAD⁺, which is a principal step in the production of d-lactate in lactic acid bacteria. In this study, we identified and characterized the major d-LDH (d-LDH1) from three d-LDHs in Leuconostoc mesenteroides, which has been extensively used in food processing. A molecular simulation study of d-LDH1 showed that the conformation changes during substrate binding. During catalysis, Tyr101 and Arg235 bind the substrates by hydrogen bonds and His296 acts as a general acid/base for proton transfer. These residues are also highly conserved and have coevolved. Point mutations proved that the substrate binding sites and catalytic site are crucial for enzyme activity. Network and phylogenetic analyses indicated that d-LDH1 and the homologues are widely distributed but are most abundant in bacteria and fungi. This study expands the understanding of the functions, catalytic mechanism, and evolution of d-LDH.

Lauric Acid Accelerates Glycolytic Muscle Fiber Formation through TLR4 Signaling

Lauric acid (LA), which is the primary fatty acid in coconut oil, was reported to have many metabolic benefits. TLR4 is a common receptor of lipopolysaccharides and involved mainly in inflammation responses. Here, we focused on the effects of LA on skeletal muscle fiber types and metabolism. We found that 200 μM LA treatment in C2C12 or dietary supplementation of 1% LA increased MHCIIb protein expression and the proportion of type IIb muscle fibers from 0.452 ± 0.0165 to 0.572 ± 0.0153, increasing the mRNA expression of genes involved in glycolysis, such as HK2 and LDH2 (from 1.00 ± 0.110 to 1.35 ± 0.0843 and from 1.00 ± 0.123 to 1.71 ± 0.302 in vivo, respectively), decreasing the catalytic activity of lactate dehydrogenase (LDH), and transforming lactic acid to pyruvic acid. Furthermore, LA activated TLR4 signaling, and TLR4 knockdown reversed the effect of LA on muscle fiber type and glycolysis. Thus, we inferred that LA promoted glycolytic fiber formation through TLR4 signaling.

From gene to structure: Lactobacillus bulgaricus D-lactate dehydrogenase from yogurt as an integrated curriculum model for undergraduate molecular biology and biochemistry laboratory courses

We have developed an integrated, project-oriented curriculum for undergraduate molecular biology and biochemistry laboratory courses spanning two semesters that is organized around the ldhA gene from the yogurt-fermenting bacterium Lactobacillus bulgaricus, which encodes the enzyme d-lactate dehydrogenase. The molecular biology module, which consists of nine experiments carried out over eleven sessions, begins with the isolation of genomic DNA from L. bulgaricus in yogurt and guides students through the process of cloning the ldhA gene into a prokaryotic expression vector, followed by mRNA isolation and characterization of recombinant gene expression levels using RT-PCR. The biochemistry module, which consists of nine experiments carried out over eight sessions, begins with overexpression of the cloned ldhA gene and guides students through the process of affinity purification, biochemical characterization of the purified LdhA protein, and analysis of enzyme kinetics using various substrates and an inhibitor, concluding with a guided inquiry investigation of structure-function relationships in the three-dimensional structure of LdhA using molecular visualization software. Students conclude by writing a paper describing their work on the project, formatted as a manuscript to be submitted for publication in a scientific journal. Overall, this curriculum, with its emphasis on experiential learning, provides hands-on training with a variety of common laboratory techniques in molecular biology and biochemistry and builds experience with the process of scientific reasoning, along with reinforcement of essential transferrable skills such as critical thinking, information literacy, and written communication, all within the framework of an extended project having the look and feel of a research experience. © 2018 by The International Union of Biochemistry and Molecular Biology, 46(3):270-278, 2018.