Evaluation of individual and combined effect of lactic acid-consuming bacteria on mesophilic hydrogen production from lactic acid effluent from food waste treatment.

Lactic acid has been applied as a precursor for hydrogen (H2) production from substrates rich in lactic acid bacteria (LAB), focusing on microbial interactions between producing and consuming LAB tested with model substrates. Therefore, this study evaluated the effect of single and combined lactic acid-consuming bacteria on mesophilic H2 production in batch tests from lactic acid from fermented food waste (FW). Megasphaera elsdenii, Clostridium beijerinckii, and Clostridium butyricum were inoculated at different ratios (v/v). Additionally, thermal pretreated sludge (TPS) was added to the strain mixtures. The highest production was obtained with M. elsdenii, C. beijerinckii, and C. butyricum (17:66:17 ratio), obtaining 1629.0 mL/Lreactor. The optimal mixture (68:32:0 of M. elsdenii and C. beijerinckii) enriched with TPS reached 1739.3 ± 98.6 mL H2/Lreactor, consuming 98 % of lactic acid added. M. elsdenii and Clostridium strains enhance H2 production from lactic acid as they persist in a microbial community initially dominated by LAB.

Astrocyte-derived lactate aggravates brain injury of ischemic stroke in mice by promoting the formation of protein lactylation.

Aim: Although lactate supplementation at the reperfusion stage of ischemic stroke has been shown to offer neuroprotection, whether the role of accumulated lactate at the ischemia phase is neuroprotection or not remains largely unknown. Thus, in this study, we aimed to investigate the roles and mechanisms of accumulated brain lactate at the ischemia stage in regulating brain injury of ischemic stroke. Methods and Results: Pharmacological inhibition of lactate production by either inhibiting LDHA or glycolysis markedly attenuated the mouse brain injury of ischemic stroke. In contrast, additional lactate supplement further aggravates brain injury, which may be closely related to the induction of neuronal death and A1 astrocytes. The contributing roles of increased lactate at the ischemic stage may be related to the promotive formation of protein lysine lactylation (Kla), while the post-treatment of lactate at the reperfusion stage did not influence the brain protein Kla levels with neuroprotection. Increased protein Kla levels were found mainly in neurons by the HPLC-MS/MS analysis and immunofluorescent staining. Then, pharmacological inhibition of lactate production or blocking the lactate shuttle to neurons showed markedly decreased protein Kla levels in the ischemic brains. Additionally, Ldha specific knockout in astrocytes (Aldh1l1 CreERT2; Ldha fl/fl mice, cKO) mice with MCAO were constructed and the results showed that the protein Kla level was decreased accompanied by a decrease in the volume of cerebral infarction in cKO mice compared to the control groups. Furthermore, blocking the protein Kla formation by inhibiting the writer p300 with its antagonist A-485 significantly alleviates neuronal death and glial activation of cerebral ischemia with a reduction in the protein Kla level, resulting in extending reperfusion window and improving functional recovery for ischemic stroke. Conclusion: Collectively, increased brain lactate derived from astrocytes aggravates ischemic brain injury by promoting the protein Kla formation, suggesting that inhibiting lactate production or the formation of protein Kla at the ischemia stage presents new therapeutic targets for the treatment of ischemic stroke.

A wearable nanozyme-enzyme electrochemical biosensor for sweat lactate monitoring.

In this study, we developed a wearable nanozyme-enzyme electrochemical biosensor that enablies sweat lactate monitoring. The biosensor comprises a flexible electrode system prepared on a polyimide (PI) film and the Janus textile for unidirectional sweat transport. We obtained favorable electrochemical activities for hydrogen peroxide reduction by modifying the laser-scribed graphene (LSG) electrode with cerium dioxide (CeO2)-molybdenum disulphide (MoS2) nanozyme and gold nanoparticles (AuNPs). By further immobilisation of lactate oxidase (LOx), the proposed biosensor achieves chronoamperometric lactate detection in artificial sweat within a range of 0.1-50.0 mM, a high sensitivity of 25.58 µA mM-1cm-2 and a limit of detection (LoD) down to 0.135 mM, which fully meets the requirements of clinical diagnostics. We demonstrated accurate lactate measurements in spiked artificial sweat, which is consistent with standard ELISA results. To monitor the sweat produced by volunteers while exercising, we conducted on-body tests, showcasing the wearable biosensor's ability to provide clinical sweat lactate diagnosis for medical treatment and sports management.

Hypocretin-1/Hypocretin Receptor 1 Regulates Neuroplasticity and Cognitive Function through Hippocampal Lactate Homeostasis in Depressed Model.

Cognitive dysfunction is not only a common symptom of major depressive disorder, but also a more common residual symptom after antidepressant treatment and a risk factor for chronic and recurrent disease. The disruption of hypocretin regulation is known to be associated with depression, however, their exact correlation is remains to be elucidated. Hypocretin-1 levels are increased in the plasma and hypothalamus from chronic unpredictable mild stress (CUMS) model mice. Excessive hypocretin-1 conducted with hypocretin receptor 1 (HCRTR1) reduced lactate production and brain-derived neurotrophic factor (BDNF) expression by hypoxia-inducible factor-1α (HIF-1α), thus impairing adult hippocampal neuroplasticity, and cognitive impairment in CUMS model. Subsequently, it is found that HCRTR1 antagonists can reverse these changes. The direct effect of hypocretin-1 on hippocampal lactate production and cognitive behavior is further confirmed by intraventricular injection of hypocretin-1 and microPET-CT in rats. In addition, these mechanisms are further validated in astrocytes and neurons in vitro. Moreover, these phenotypes and changes in molecules of lactate transport pathway can be duplicated by specifically knockdown of HCRTR1 in hippocampal astrocytes. In summary, the results provide molecular and functional insights for involvement of hypocretin-1-HCRTR1 in altered cognitive function in depression.

Modulation of brain energy metabolism in hepatic encephalopathy: impact of glucose metabolic dysfunction.

Cerebral function is linked to a high level of metabolic activity and relies on glucose as its primary energy source. Glucose aids in the maintenance of physiological brain activities; as a result, a disruption in metabolism has a significant impact on brain function, launching a chain of events that leads to neuronal death. This metabolic insufficiency has been observed in a variety of brain diseases and neuroexcitotoxicity disorders, including hepatic encephalopathy. It is a significant neurological complication that develops in people with liver disease, ranging from asymptomatic abnormalities to coma. Hyperammonemia is the main neurotoxic villain in the development of hepatic encephalopathy and induces a wide range of complications in the brain. The neurotoxic effects of ammonia on brain function are thought to be mediated by impaired glucose metabolism. Accordingly, in this review, we provide an understanding of deranged brain energy metabolism, emphasizing the role of glucose metabolic dysfunction in the pathogenesis of hepatic encephalopathy. We also highlighted the differential metabolic profiles of brain cells and the status of metabolic cooperation between them. The major metabolic pathways that have been explored are glycolysis, glycogen metabolism, lactate metabolism, the pentose phosphate pathway, and the Krebs cycle. Furthermore, the lack of efficacy in current hepatic encephalopathy treatment methods highlights the need to investigate potential therapeutic targets for hepatic encephalopathy, with regulating deficient bioenergetics being a viable alternative in this case. This review also demonstrates the importance of the development of glucose metabolism-focused disease diagnostics and treatments, which are now being pursued for many ailments.

Effect of Preoperative Serum Lactate Dehydrogenase-to-Albumin Ratio on the Survival of Oral Cancer: A Retrospective Study.

Background: Several studies have investigated the relationship between serum lactate dehydrogenase-to-albumin ratio (LAR) and the prognosis of cancers. However, no studies have explored the association between serum LAR and the survival of oral cancer (OC). This study was aimed to determine the association of serum LAR with the overall survival (OS) of OC. Methods: One hundred and ninety patients with OC were included in this study between January 2018 and December 2019. Log rank test and Kaplan-Meier method were used to compare the survival rate of OC between the low LAR group and the high LAR group. The association between serum LAR and the survival of OC patients was determined via univariate and multivariate Cox regression analyses. Results: Kaplan-Meier analysis and Log rank test indicated that the OS rate in low LAR group was significantly higher than that in high LAR group (P < 0.05). Univariate cox analysis showed that TNM III-IV stage, serum LDH > 162 U/L, and serum LAR > 3.79 were significantly associated with the OS of OC patients. Multivariate Cox analysis suggested that the TNM III-IV stage (HR, 2.317; 95% CI, 1.423-3.774, P = 0.001) and serum LAR > 3.79 (HR, 5.138; 95% CI, 2.245-11.756, P = 0.000) were independently related with poor OS of OC patients. Conclusion: High serum LAR (>3.79) is an independent predictor of adverse prognosis in OC patients. LAR could be used as a promising marker for predicting the OS of OC patients.

Evaluation of the CCL17/CCL22-CCR4 axis in pediatrics with B-cell acute lymphoblastic leukemia before and after a chemotherapy course.

AIMS: Acute lymphoblastic leukemia (ALL) is the most common type of pediatrics cancer. Chemokines exert different roles in leukemia process through leukocyte recruitment and regulation of disease severity. Due to the prominent roles of chemokine/receptor axes, this study aimed to measure the blood expression levels of CCR4 and their ligands in pediatrics with B-cell ALL (B-ALL). We also evaluated the impact of cytotoxic chemotherapy on this axis. MATERIAL AND METHOD: Thirty children suffering from B-ALL were included in the study and followed up for 30 days after completion of a chemotherapy course. The blood sampling was performed before and after chemotherapy. 30 healthy donors have also entered the study as control subjects. The mRNA expression of CCL17, CCL22 and CCR4 genes was determined by quantitative real-time PCR. The frequency of the peripheral blood mononuclear cells expressing CCR4 (CCR4 + PBMCs) was also evaluated by the flow cytometry method. Moreover, we evaluated the association of the CCL17/CCL22-CCR4 axis with some diagnostic, prognostic and predictive biomarkers in ALL patients. RESULTS: There was overexpression of the CCL17/CCL22-CCR4 axis along with lactate dehydrogenase (LDH) in pediatrics with B-ALL compared to healthy controls. After induction of chemotherapy, the blood expression levels of the CCL17/CCL22-CCR4 axis have reached the levels of healthy controls. The findings for the blood expression levels of CCR4 were also confirmed using flow cytometry. CONCLUSION: The CCL17/CCL22-CCR4 axis can be used as a novel predictive and prognostic biomarker in B-ALL.

Delayed and Diminished Postprandial Lactate Shuttling in Healthy Older Men and Women.

Lactate, a product of glycolysis, is formed under aerobic conditions. Extensive work has shown lactate flux in young and exercising humans; however, the effect of age is not known. We tested the hypothesis that postprandial lactate shuttling (PLS) would be diminished in older adults. We used [3-13C]lactate and [6,6-2H]-glucose tracers, an OGTT, and arterialized blood sampling to determine postprandial lactate rates of appearance (Ra), disappearance (Rd), and oxidation (Rox) in 15 young (28.1 ± 1.4 yr) and 13 older (70.6 ± 2.4 yr) healthy men and women. In young participants fasting blood [lactate] [¼ 0.5 mM] rose after the glucose challenge, peaked at 15 min, dipped to a nadir at 30 min, and rose again peaking at 60 min [¼ 1.0mM]. Initial responses in lactate Ra of older participants were delayed and diminished until 90 minutes rising by 0.83 mg·kg-1·min-1. Lactate Rox was higher throughout the entire trial in young participants by a difference of approximately 0.5 mg·kg-1·min-1. Initial peaks in lactate Ra and concentration in all volunteers demonstrated presence of an enteric PLS following an OGTT. Notably, in the systemic, but not enteric PLS phase, lactate Ra correlated highly with glucose Rd (r2 = 0.92). Correspondence of second peaks in lactate Ra and concentration and glucose Rd show dependence of lactate Ra on glucose Rd. While results show both enteric and systemic PLS phases in young and older study cohorts, metabolic responses were delayed and diminished in healthy older individuals.

Evaluating tissue hypoxia and the response to fluid administration in septic shock patients: a metabolic cluster analysis.

BACKGROUND: The selection of adequate indicators of tissue hypoxia for guiding the resuscitation process of septic patients is a highly relevant issue. Current guidelines advocate for the use of lactate as sole metabolic marker, which may be markedly limited, and the integration of different variables seems more adequate. In this study, we explored the metabolic profile and its implications in the response to the administration of a fluid challenge in early septic shock patients. METHODS: Observational study including septic shock patients within 24 h of ICU admission, monitored with a cardiac output estimation system, with ongoing resuscitation. Hemodynamic and metabolic variables were measured before and after a fluid challenge (FC). A two-step cluster analysis was used to define the baseline metabolic profile, including lactate, central venous oxygen saturation (ScvO2), central venous-to-arterial carbon dioxide difference (PcvaCO2), and PcvaCO2 corrected by the difference in arterial-to-venous oxygen content (PcvaCO2/CavO2). RESULTS: Seventy-seven fluid challenges were analyzed. Cluster analysis revealed two distinct metabolic profiles at baseline. Cluster A exhibited lower ScvO2, higher PcvaCO2, and lower PcvaCO2/CavO2. Increases in cardiac output (CO) were associated with increases in VO2 exclusively in cluster A. Baseline isolated metabolic variables did not correlate with VO2 response, and changes in ScvO2 and PcvaCO2 were associated to VO2 increase only in cluster A. CONCLUSIONS: In a population of early septic shock patients, two distinct metabolic profiles were identified, suggesting tissue hypoxia or dysoxia. Integrating metabolic variables enhances the ability to detect those patients whose VO2 might increase as results of fluid administration.

Lactate dehydrogenase A (LDHA)-mediated lactate generation promotes pulmonary vascular remodeling in pulmonary hypertension.

BACKGROUND: High levels of lactate are positively associated with prognosis and mortality in pulmonary hypertension (PH). Lactate dehydrogenase A (LDHA) is a key enzyme for the production of lactate. This study is undertaken to investigate the role and molecular mechanisms of lactate and LDHA in PH. METHODS: Lactate levels were measured by a lactate assay kit. LDHA expression and localization were detected by western blot and Immunofluorescence. Proliferation and migration were determined by CCK8, western blot, EdU assay and scratch-wound assay. The right heart catheterization and right heart ultrasound were measured to evaluate cardiopulmonary function. RESULTS: In vitro, we found that lactate promoted proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) in an LDHA-dependent manner. In vivo, we found that LDHA knockdown reduced lactate overaccumulation in the lungs of mice exposed to hypoxia. Furthermore, LDHA knockdown ameliorated hypoxia-induced vascular remodeling and right ventricular dysfunction. In addition, the activation of Akt signaling by hypoxia was suppressed by LDHA knockdown both in vivo and in vitro. The overexpression of Akt reversed the inhibitory effect of LDHA knockdown on proliferation in PASMCs under hypoxia. Finally, LDHA inhibitor attenuated vascular remodeling and right ventricular dysfunction in Sugen/hypoxia mouse PH model, Monocrotaline (MCT)-induced rat PH model and chronic hypoxia-induced mouse PH model. CONCLUSIONS: Thus, LDHA-mediated lactate production promotes pulmonary vascular remodeling in PH by activating Akt signaling pathway, suggesting the potential role of LDHA in regulating the metabolic reprogramming and vascular remodeling in PH.

Elevated lactate dehydrogenase - A red herring in the diagnosis of a sclerosing stromal tumor: A case report.

Sclerosing stromal tumors are a rare type of ovarian tumor in the category of sex cord stromal tumors, which arise from the ovarian connective tissue. This report concerns a case of a sclerosing stromal tumor in a 19-year-old nulliparous woman who presented with the chief complaints of menstrual irregularities and dyspareunia. Preoperative imaging revealed a complex right adnexal mass with blood flow and without associated ascites. Tumor markers were all normal except lactate dehydrogenase, which was elevated. The elevated lactate dehydrogenase, in combination with patient age and menstrual irregularities, initially misdirected the clinicians toward suspicion for dysgerminoma or other malignant germ cell tumor of the ovary. Clinicians should beware of excluding the diagnosis of sex cord stromal tumor on the differential in a young person with an adnexal mass and elevated lactate dehydrogenase.

Identifying high-risk undifferentiated emergency department patients with hyperlactatemia: Predictors of 30-day in-hospital mortality.

BACKGROUND: Hyperlactatemia has been recognized as a significant prognostic indicator in critically ill patients. Nonetheless, there remains a gap in understanding the specific risk factors contributing to increased mortality among undifferentiated emergency department (ED) patients presenting with elevated lactate levels. OBJECTIVES: The objective of the study is to investigate potential risk factors for 30-day in-hospital mortality in ED patients with hyperlactatemia. METHODS: All nontraumatic adult presentations to the ED who had a lactate level of ≥2.5 mmol/L were included. Comorbidities, vital signs, lactate levels, lactate clearance, lactate normalization, and final diagnosis were compared with 30-day in-hospital mortality. RESULTS: A 30-day in-hospital mortality rate of 10.4% was observed in 979 patients. The mortality rate was higher in hypotensive patients (odds ratio [OR] 4.973), in nursing home patients (OR 5.689), and bedridden patients (OR 3.879). The area under the curve for the second lactate level (0.804) was higher than the first lactate level (0.691), and lactate clearance (0.747) for in-hospital mortality. A second lactate level >3.15 mmol/l had a sensitivity of 81.3% in predicting in-hospital mortality. The OR for mortality was 6.679 in patients without lactate normalization. A higher mortality rate was observed in patients with acute renal failure (OR 4.305), septic shock (OR 4.110), and acute coronary syndrome (OR 2.303). CONCLUSIONS: A second lactate measurement more accurately predicts in-hospital mortality than lactate clearance and the first lactate level in ED patients. Nursing home patients, bed-ridden patients, hypotensive patients on initial ED presentation, patients without lactate normalization, and patients with a final diagnosis of acute renal failure, septic shock, and acute coronary syndrome had a higher mortality rate.

Operational stability study of lactate biosensors: modeling, parameter identification, and stability analysis.

Introduction: This paper investigates the operational stability of lactate biosensors, crucial devices in various biomedical and biotechnological applications. We detail the construction of an amperometric transducer tailored for lactate measurement and outline the experimental setup used for empirical validation. Methods: The modeling framework incorporates Brown and Michaelis-Menten kinetics, integrating both distributed and discrete delays to capture the intricate dynamics of lactate sensing. To ascertain model parameters, we propose a nonlinear optimization method, leveraging initial approximations from the Brown model's delay values for the subsequent model with discrete delays. Results: Stability analysis forms a cornerstone of our investigation, centering on linearization around equilibrium states and scrutinizing the real parts of quasi-polynomials. Notably, our findings reveal that the discrete delay model manifests marginal stability, occupying a delicate balance between asymptotic stability and instability. We introduce criteria for verifying marginal stability based on characteristic quasi-polynomial roots, offering practical insights into system behavior. Discussion: Qalitative examination of the model elucidates the influence of delay on dynamic behavior. We observe a transition from stable focus to limit cycle and period-doubling phenomena with increasing delay values, as evidenced by phase plots and bifurcation diagrams employing Poincaré sections. Additionally, we identify limitations in model applicability, notably the loss of solution positivity with growing delays, underscoring the necessity for cautious interpretation when employing delayed exponential function formulations. This comprehensive study provides valuable insights into the design and operational characteristics of lactate biosensors, offering a robust framework for understanding and optimizing their performance in diverse settings.

Integrin ß3 enhances glycolysis and increases lactate production in endometriosis.

BACKGROUND: Endometriosis (EMs) is a chronic disease characterized by endometrial-like tissue present outside of the uterus. Macrophages have been confirmed to participate in the development of EMs. Integrin ß3 (ITGB3), a ß-subunit of the integrin family, is crucial in tumor progression. In this study, we investigated the pivotal role of ITGB3 in endometrial stromal cells (ESCs) and its influence on the development of EMs, particularly focusing on the regulatory impact of macrophages. METHODS: In this study, we used western blot, Real-time qPCR, Immunohistochemistry to detected the high expression of ITGB3 in ESCs. ITGB3-overexpression ESCs (ITGB3-OE) was constructed and detected by RNA-seq with normal ESCs. ATP and lactate expression assay, transwell migration assay, wound healing, cell adhesion assay and other molecular biology techniques were used to explore the potential mechanisms. In vivo, we constructed the EMs mouse model and injected with cilengitite to inhibit ITGB3. RESULTS: Here, we found ITGB3 highly expressed in ectopic lesions in EMs. The increasing ITGB3 resulted in activating the glycolysis, which produced more ATP and lactate in ITGB3-OE. After culturing with lactate, the migration, proliferation and invasion ability of ESCs were enhanced, while the result in 2-DG was reversed. In vivo, the results showed that after antagonizing ITGB3, the number of ectopic lesions was decrease. CONCLUSIONS: Our findings indicate that ITGB3 up-regulated by macrophages are able to regulate the glycolysis to promote the development of EMs and lactate enhances the ability of proliferation, migration, invasion and adhesion of EMs iv vivo and in vitro.

Cardiac biomarkers are associated with increased risks of adverse clinical outcomes after ischemic stroke.

BACKGROUND: Impaired cardiac function was suggested to be implicated in the functional recovery after ischemic stroke, but the prognostic value of cardiac biomarkers among ischemic stroke patients remains unclear. We aimed to prospectively explore the associations of serum lactate dehydrogenase (LDH), plasma N-terminal pro-brain natriuretic peptide (NT-proBNP), and plasma high-sensitivity cardiac troponin T (hs-cTnT) with adverse clinical outcomes after ischemic stroke in a large-scale cohort study. METHODS: We measured serum LDH, plasma NT-proBNP, and plasma hs-cTnT levels at baseline among 5056 ischemic stroke patients from the Minhang Stroke Cohort study. All patients were followed up at 3 months after ischemic stroke onset. The primary outcome was composite outcome of death and major disability (modified Rankin Scale [mRS] score ≥ 3) at 3 months after stroke onset, and secondary outcomes included death and ordered 7-level categorical score of the mRS. RESULTS: During 3 months of follow-up, 1584 patients developed the primary outcome. Baseline serum LDH, plasma NT-proBNP, and plasma hs-cTnT were positively associated with the risk of adverse outcomes after ischemic stroke. The multivariable-adjusted odds ratios of primary outcome for the highest versus lowest quartile of LDH, NT-proBNP, and hs-cTnT were 1.37 (95% CI 1.13-1.66; Ptrend = 0.001), 2.51 (95% CI, 2.00-3.16; Ptrend < 0.001), and 2.24 (95% CI 1.77-2.83; Ptrend < 0.001), respectively. Each SD increase of log-transformed cardiac biomarker score was associated with a 49% (95% CI 37-62%; P < 0.001) increased risk of primary outcome. Multivariable-adjusted spline regression analyses showed linear relationships between cardiac biomarkers and the risk of primary outcome (all P for linearity < 0.001). Moreover, adding LDH, NT-proBNP, hs-cTnT, or cardiac biomarker score to conventional risk factors significantly improved the risk reclassification of primary outcome after ischemic stroke (all P < 0.05). CONCLUSION: High LDH, NT-proBNP, hs-cTnT, and cardiac biomarker score were independently associated with increased risks of adverse clinical outcomes among ischemic stroke patients, suggesting that cardiac biomarkers might be potential prognostic biomarkers for ischemic stroke.

Lactate promotes microglial scar formation and facilitates locomotor function recovery by enhancing histone H4 lysine 12 lactylation after spinal cord injury.

Lactate-derived histone lactylation is involved in multiple pathological processes through transcriptional regulation. The role of lactate-derived histone lactylation in the repair of spinal cord injury (SCI) remains unclear. Here we report that overall lactate levels and lactylation are upregulated in the spinal cord after SCI. Notably, H4K12la was significantly elevated in the microglia of the injured spinal cord, whereas exogenous lactate treatment further elevated H4K12la in microglia after SCI. Functionally, lactate treatment promoted microglial proliferation, scar formation, axon regeneration, and locomotor function recovery after SCI. Mechanically, lactate-mediated H4K12la elevation promoted PD-1 transcription in microglia, thereby facilitating SCI repair. Furthermore, a series of rescue experiments confirmed that a PD-1 inhibitor or microglia-specific AAV-sh-PD-1 significantly reversed the therapeutic effects of lactate following SCI. This study illustrates the function and mechanism of lactate/H4K12la/PD-1 signaling in microglia-mediated tissue repair and provides a novel target for SCI therapy.

A bright red fluorescent genetically encoded sensor for lactate imaging.

Lactate plays a crucial role in energy metabolism and greatly impacts protein activities, exerting diverse physiological and pathological effects. Therefore, convenient lactate assays for tracking spatiotemporal dynamics in living cells are desirable. In this paper, we engineered and optimized a red fluorescent protein sensor for l-lactate named FiLa-Red. This indicator exhibited a maximal fluorescence change of 730 % and an apparent dissociation constant (Kd) of approximately 460 µM. By utilizing FiLa-Red and other sensors, we monitored energy metabolism in a multiplex manner by simultaneously tracking lactate and NAD+/NADH abundance in the cytoplasm, nucleus, and mitochondria. The FiLa-Red sensor is expected to be a useful tool for performing metabolic analysis in vitro, in living cells and in vivo.

Association of serum lactate dehydrogenase with prognosis and tumor metabolism in patients with hepatocellular carcinoma treated with atezolizumab plus bevacizumab therapy.

PURPOSE: Treatment outcomes are predicted by analyzing peripheral blood markers such as serum lactate dehydrogenase (LDH). We conducted this study to investigate whether serum LDH levels can predict the prognosis of patients treated with atezolizumab plus bevacizumab (ATZ/BEV) therapy for hepatocellular carcinoma (HCC) and whether LDH levels correlate with metabolic changes. METHODS: We enrolled 66 HCC patients treated with ATZ/BEV. Based on the change in serum LDH levels before and after treatment, the patients were divided into two groups, and the prognosis of each group was examined. Moreover, the association of LDH levels with tumor metabolism was analyzed by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). RESULTS: There were 32 patients categorized as the LDH-decrease group. Kaplan-Meier survival analysis indicated worse progression-free survival (PFS) in the LDH-increase group than in the LDH-decrease group (p = 0.0029). Multivariate analysis showed that an increase in the LDH level was an independent risk factor for worse PFS (p = 0.0045). The baseline LDH level correlated significantly with a high maximum standardized uptake value of 18F-FDG, according to the PET/CT findings. Transcriptomic analyses of specimens resected after ATZ/BEV therapy showed downregulated mitochondria-related pathways. CONCLUSION: Serum LDH levels are a potential prognostic marker and an indicator of tumor metabolism.