Acute kidney injury (AKI) is a common clinically critical syndrome in hospitalized patients with high morbidity and mortality. At present, the mechanism of AKI has not been fully elucidated, and no therapeutic drugs exist. As known, glycolytic product lactate is a key metabolite in physiological and pathological processes. The kidney is an important gluconeogenic organ, where lactate is the primary substrate of renal gluconeogenesis in physiological conditions. During AKI, altered glycolysis and gluconeogenesis in kidneys significantly disturb the lactate metabolic balance, which exert impacts on the severity and prognosis of AKI. Additionally, lactate-derived posttranslational modification, namely lactylation, is novel to AKI as it could regulate gene transcription of metabolic enzymes involved in glycolysis or Warburg effect. Protein lactylation widely exists in human tissues and may severely affect non-histone functions. Moreover, the strategies of intervening lactate metabolic pathways are expected to bring a new dawn for the treatment of AKI. This review focused on renal lactate metabolism, especially in proximal renal tubules after AKI, and updated recent advances of lactylation modification, which may help to explore potential therapeutic targets against AKI.
Humans ; Acute Kidney Injury/metabolism* ; Lactic Acid/metabolism* ; Animals ; Glycolysis/physiology* ; Gluconeogenesis/physiology* ; Kidney/metabolism*

OBJECTIVE: To explore the role of the natural compound hesperidin in glycolysis, the key ratelimiting enzyme, in colorectal cancer (CRC) cell lines. METHODS: In vitro, HCT116 and SW620 were treated with different doses of hesperidin (0-500 µmol/L), cell counting kit-8 and colone formation assays were utilized to detected inhibition effect of hesperidin on CRC cell lines. Transwell and wound healing assays were performed to detect the ability of hesperidin (0, 25, 50 and 75 µmol/L) to migrate CRC cells. To confirm the apoptotic-inducing effect of hesperidin, apoptosis and cycle assays were employed. Western blot, glucose uptake, and lactate production determination measurements were applied to determine inhibitory effects of hesperidin (0, 25 and 50 µmol/L) on glycolysis. In vivo, according to the random number table method, nude mice with successful tumor loading were randomly divided into vehicle, low-dose hesperidin (20 mg/kg) and high-dose hesperidin (60 mg/kg) groups, with 6 mice in each group. The body weights and tumor volumes of mice were recorded during 4-week treatment. The expression of key glycolysis rate-limiting enzymes was determined using Western blot, and glucose uptake and lactate production were assessed. Finally, protein interactions were probed with DirectDIA Quantitative Proteomics, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. RESULTS: Hesperidin could inhibit CRC cell line growth (P<0.05 or P<0.01). Moreover, hesperidin presented an inhibitory effect on the migrating abilities of CRC cells. Hesperidin also promoted apoptosis and cell cycle alterations (P<0.05). The immunoblotting results manifested that hesperidin decreased the levels of hexokinase 2, glucose transporter protein 1 (GLUT1), GLUT3, L-lactate dehydrogenase A, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2), PFKFB3, and pyruvate kinase isozymes M2 (P<0.01). It remarkably suppressed tumor xenograft growth in nude mice. GO and KEGG analyses showed that hesperidin treatment altered metabolic function. CONCLUSION Hesperidin inhibits glycolysis and is a potential therapeutic choice for CRC treatment.
Hesperidin/therapeutic use* ; Colorectal Neoplasms/metabolism* ; Glycolysis/drug effects* ; Animals ; Humans ; Apoptosis/drug effects* ; Mice, Nude ; Cell Movement/drug effects* ; Cell Line, Tumor ; Cell Proliferation/drug effects* ; Glucose/metabolism* ; Cell Cycle/drug effects* ; Mice, Inbred BALB C ; Mice ; HCT116 Cells ; Lactic Acid

Lactic acid (LA) accumulation in tumor microenvironments (TME) has been implicated in immune suppression and tumor progress. Diverse roles of LA have been elucidated, including microenvironmental pH regulation, signal transduction, post-translational modification, and metabolic remodeling. This review summarizes LA functions within TME, focusing on the effects on tumor cells, immune cells, and stromal cells. Reducing LA levels is a potential strategy to attack cancer, which inevitably affects the physiological functions of normal tissues. Alternatively, transporting LA into the mitochondria as an energy source for immune cells is intriguing. We underscore the significance of LA in both tumor biology and immunology, proposing the burning of LA as a potential therapeutic approach to enhance antitumor immune responses.
Humans ; Tumor Microenvironment/immunology* ; Neoplasms/therapy* ; Lactic Acid/immunology* ; Mitochondria/metabolism* ; Animals ; Signal Transduction

The Warburg effect, originally discovered by Otto Warburg, refers to the metabolic reprogramming of tumor cells from aerobic oxidation to glycolysis, enabling rapid energy production to support their growth and metastasis. This process is accompanied by the massive production and accumulation of lactate both intracellularly and extracellularly. The resulting acidic microenvironment impairs the normal physiological functions of immune cells and promotes tumor progression. An increasing number of studies indicate that lactate, a key metabolite in the tumor microenvironment (TME), acts as a pivotal immunosuppressive signaling molecule that modulates immune cell function. This review aims to comprehensively examine lactate's role as an immunosuppressive molecule in TME. It focuses on mechanisms such as membrane receptor binding, functional reshaping of immune cells via lactate shuttle transport, epigenetic regulation of gene expression through histone lactylation, and modulation of protein structure and function through nonhistone lactylation, emphasizing lactate's importance in immune regulation within the TME. Ultimately, this review offers novel insights into immunosuppressive therapies aimed at targeting lactate function.
Humans ; Neoplasms/metabolism* ; Tumor Microenvironment/immunology* ; Lactic Acid/immunology* ; Warburg Effect, Oncologic ; Animals ; Glycolysis ; Epigenesis, Genetic

OBJECTIVE: To evaluate the advantages and limitations of transcutaneous electrical acupoint stimulation (TEAS) in the treatment of patients with severe gastrointestinal function injury in intensive care unit (ICU) by analyzing dynamic changes of intestinal fatty acid binding protein (I-FABP), D-lactic acid and citrulline. METHODS: A prospective single-center randomized controlled trial was conducted. Patients with severe gastrointestinal function injury admitted to the ICU from February 2021 to January 2024 were enrolled [age > 18 years old, acute gastrointestinal injury (AGI) grade 2 to 3, stable hemodynamics]. Patients with different AGI grades were randomly assigned in a 1:1 ratio to the TEAS group and the control group using simple randomization. Both groups received conventional treatment and enteral nutrition (EN). In addition, the TEAS group underwent TEAS at the Neiguan and Zusanli points for 30 minutes per session, twice daily for 7 days. Baseline data, including age, gender, underlying diseases, and primary diagnoses, were recorded. Three intestinal biomarkers, such as I-FABP, D-lactic acid, and citrulline were measured before and after 7 days of treatment. EN tolerance indicators and 28 days survival status were documented. The differences in various indicators were compared between the two groups, subgroup analyses were conducted based on AGI grading, and interaction between AGI grade and TEAS were analyzed. The 28-day Kaplan-Meier survival curves were generated for both groups. RESULTS: Finally, 133 patients were included, with 68 in the TEAS group and 65 in the control group. Baseline characteristics were comparable between the two groups. A comparison of the dynamic changes in intestinal biomarkers revealed that the I-FABP level in both groups decreased after treatment compared to pre-treatment, with a more pronounced reduction in the TEAS group. The least square mean difference (LS Mean difference) for the corrected I-FABP level between the two groups during the observation period was -0.23 μg/L [95% confidence interval (95%CI) was -0.45 to -0.01], which was statistically significant (P = 0.041). Additionally, a significant interaction with AGI was observed (P = 0.004). Post-treatment, D-lactic acid level decreased in both groups compared to pre-treatment, with a more significant reduction in the TEAS group. The LS Mean difference for the corrected D-lactic acid level was -0.08 mmol/L (95%CI was -0.11 to -0.05), which was statistically significant (P < 0.001), and the interaction with AGI was also significant (P = 0.005). There was no significant change in citrulline levels between the two groups before and after treatment. The LS Mean difference for the corrected citrulline level was -0.17 μmol/L (95%CI was -1.87 to 1.53), which was not statistically significant (P = 0.845), and no significant interaction with AGI was observed (P = 0.913). Comparison of EN tolerance parameters between the two groups revealed that the TEAS group had a longer total EN time (hours: 72±31 vs. 60±28) and higher total EN calories (kJ: 11 469.23±7 237.34 vs. 6 638.76±5 098.37), as well as a higher 70% target caloric attainment rate (52.9% vs. 32.3%) compared to the control group (all P < 0.05). The incidence of abdominal distension after EN was lower in the TEAS group than that in the control group (23.5% vs. 43.1%, P < 0.05), while the incidence of diarrhea after EN was higher in the TEAS group (22.1% vs. 7.7%, P < 0.05). There were no significantly differences in AGI grade reduction rate, post-EN vomiting/gastric retention rate, incidence of feeding interruption, and 28-day survival rate between the two groups. Furthermore, there were no significantly interaction between these observation measures and AGI. Kaplan-Meier survival analysis showed that there was no significantly difference in 28-day cumulative survival rate between the TEAS group and the control group [Log-Rank test: P = 0.501, hazard ratio (HR) = 0.81, 95%CI was 0.43-1.51), and there was no significantly interaction with AGI (P = 0.702). CONCLUSIONS The advantage of TEAS in the treatment of ICU patients with severe gastrointestinal function injury lies in its ability to reverse intestinal cell necrosis and promote the reconstruction of intestinal barrier function. Additionally, gastrointestinal tolerance is significantly improved, and both the duration and total calories of EN are increased. However, the limitation of TEAS therapy is that it does not promote the recovery of intestinal cell absorption and synthesis function in the target patients. Moreover, it may lead to nutrient solution overload due to improved gastrointestinal tolerance. Furthermore, TEAS does not appear to improve 28-day cumulative survival rate in the target patients.
Humans ; Prospective Studies ; Intensive Care Units ; Acupuncture Points ; Fatty Acid-Binding Proteins/metabolism* ; Transcutaneous Electric Nerve Stimulation ; Male ; Female ; Citrulline/metabolism* ; Lactic Acid/metabolism* ; Gastrointestinal Diseases/therapy* ; Middle Aged ; Enteral Nutrition ; Adult

In recent years, significant progress has been made in the study of the complex pathophysiology of sepsis. However, sepsis remains the main cause of high mortality among critically ill patients worldwide. Early diagnosis, timely treatment, and accurate prediction of the prognosis are crucial for the successful treatment of septic patients. Lactic acid not only serves as a diagnostic indicator for septic shock but also participates in the immune response process of sepsis. It regulates gene epigenetic regulation through lactylation, thereby affecting the expression of related genes, cellular metabolism, and the immune response of the body. Therefore, it may become a new target for the treatment of sepsis. Lactate-related indicators, such as lactic acid/albumin ratio (LAR) and lactic acid/hematocrit ratio (LHR), also have important value in the prognosis assessment of septic patients and are superior to the evaluation efficacy of a single indicator. This is of great significance for timely detection of the changes in the condition of septic patients and their risk stratification and precise treatment. This review focused on the relationship between lactylation, lactatization, lactate-related indicators and sepsis, as well as the latest research progress. By revealing their roles in the occurrence, development and prognosis of sepsis, it provided new ideas for clinical diagnosis and treatment, uncovered new mechanisms of disease onset, guided disease risk stratification, optimized existing treatment strategies, and also offered new references and directions for basic research on lactate-related indicators.
Humans ; Sepsis/metabolism* ; Lactic Acid/metabolism* ; Prognosis ; Biomarkers/blood*

The Chinese hamster ovary (CHO) cell is the most representative mammalian cell protein expression system, and it is widely used in recombinant protein, vaccine and other biopharmaceutical fields. However, due to its vulnerability to environmental factors, apoptosis, and metabolic inhibitors, CHO cells demonstrate poor robustness, and thus the integrated viable cell density and unit cell productivity are largely limited. To improve the robustness and foreign protein expression efficiency of CHO cells, we employed CRISPR/Cas9 to knock out the apoptosis genes Bax and Bak and the lactate dehydrogenase gene LDHa, thereby blocking apoptosis and lactic acid metabolism pathways. The results of apoptosis and single cell viability detection showed that the number of apoptotic cells in the knockout cell lines Bax^-/-, Bax-bak^-/-, and LDHa-Bax-bak^-/- was reduced by 22.51%, 37.73%, and 64.12%, respectively, compared with the wild-type cell line CHO-K1, which indicated that the anti-apoptotic ability was significantly improved. After staurosporine treatment, the single cell viability of Bax^-/-, Bax-bak^-/-, and LDHa-Bax-bak^-/- cells was increased by 30.8%, 22%, and 41.1%, respectively. After treatment with puromycin, the single cell viability of Bax^-/-, Bax-bak^-/-, and LDHa-Bax-bak^-/- cells was increased by 26.7%, 30.7%, and 38.8%, respectively. To further investigate the production performance of cells obtained after blocking apoptosis and lactic acid metabolism pathways, we induced transient expression of human tissue plasminogen activator (tPA) in these cells. The results showed that the secretion of tPA in Bax^-/-, Bax-Bak^-/-, and LDHa-Bax-Bak^-/- cells was 11.12%, 46.18%, and 63.13%, respectively, higher than that in wild-type CHO-K1 cells. The expression of intracellular tPA was increased by 35.65%, 130%, and 192.15%. In conclusion, blocking apoptosis and lactic acid metabolism pathways simultaneously can improve cell robustness and productivity, with the performance better than blocking the apoptosis pathway alone. The above results indicated that the constructed cell lines were expected to be the delivery carriers of protein drugs such as medicinal peptides, and better used for the treatment of diseases.
CHO Cells ; Cricetulus ; Animals ; Apoptosis/genetics* ; Lactic Acid/metabolism* ; Recombinant Proteins/biosynthesis* ; L-Lactate Dehydrogenase/genetics* ; bcl-2-Associated X Protein/genetics* ; bcl-2 Homologous Antagonist-Killer Protein/genetics* ; Cricetinae ; CRISPR-Cas Systems ; Staurosporine/pharmacology*

Reducing lactate accumulation has always been a goal of the mammalian cell biotechnology industry. When animal cells are cultured in vitro, the accumulation of lactate is mainly the combined result of two metabolic pathways. On one hand, glucose generates lactate under the function of lactate dehydrogenase A (LDHA); on the other hand, lactate can be oxidized to pyruvate by LDHB or LDHC and re-enter the TCA cycle. This study comprehensively evaluated the effects of LDH manipulation on the growth, metabolism and human adenovirus (HAdV) production of human embryonic kidney 293 (HEK-293) cells, providing a theoretical basis for engineering the lactate metabolism in mammalian cells. By knocking out ldha gene and overexpression of ldhb and ldhc genes, the metabolic efficiency of HEK-293 cells was effectively improved, and HAdV production was significantly increased. Compared with the control cell, LDH manipulation promoted cell growth, reduced the accumulation of lactate and ammonia, significantly enhanced the efficiency of substrate and energy metabolism of cells, and significantly increased the HAdV production capacity of HEK-293 cells. Among these LDH manipulation measures, ldhc gene overexpression performed the best, with the maximum cell density increased by about 38.7%. The yield of lactate to glucose and ammonia to glutamine decreased by 33.8% and 63.3%, respectively; and HAdV titer increased by at least 16 times. In addition, the ATP production rate, ATP/O₂ ratio, ATP/ADP ratio and NADH content of the modified cell lines were increased to varying degrees, and the energy metabolic efficiency was significantly improved.
Animals ; Humans ; L-Lactate Dehydrogenase/genetics* ; Lactic Acid ; Adenoviruses, Human ; Ammonia ; HEK293 Cells ; Glucose/metabolism* ; Adenosine Triphosphate/metabolism* ; Kidney/metabolism* ; Mammals/metabolism*

OBJECTIVE: To investigate the effect of lactic acid-induced upregulation of PLEKHA4 expression on biological behaviors of glioma cells and the possible molecular mechanism. METHODS: GEO database and GEPIA2 website were used to analyze the relationship between PLEKHA4 expression level and the pathological grade of glioma. A specific PLEKHA4 siRNA was transfected in glioma U251 and T98G cells, and the changes in cell proliferation ability were assessed by real-time cell analysis technology and Edu experiment. The colony-forming ability of the cells was evaluated using plate cloning assay, and cell cycle changes and cell apoptosis were analyzed with flow cytometry. The mRNA expression of PLEKHA4 was detected by PCR in glioma samples and controls and in glioma cells treated with lactic acid and glucose. Xenograft mice in vivo was used to detect tumor formation in nude mice; Western blotting was used to detect the expressions of cyclinD1, CDK2, Bcl2, β-catenin and phosphorylation of the key proteins in the MAPK signaling pathway. RESULTS: The results of GEO database and online website analysis showed that PLEKHA4 was highly expressed in glioma tissues and was associated with poor prognosis; PLEKHA4 knockdown obviously inhibited the proliferation and attenuated the clone-forming ability of the glioma cells (P < 0.05). Flow cytometry showed that PLEKHA4 knockdown caused cell cycle arrest in G1 phase and promoted apoptosis of the cells (P < 0.01). PLEKHA4 gene mRNA expression was increased in glioma samples and glioma cells after lactate and glucose treatment (P < 0.01). PLEKHA4 knockdown, tumor formation ability of nude mice decreased; PLEKHA4 knockdown obviously lowered the expression of cyclinD1, CDK2, Bcl2 and other functional proteins, inhibited the phosphorylation of ERK and p38 and reduced the expression of β-catenin protein (P < 0.01). CONCLUSION PLEKHA4 knockdown inhibited the proliferation of glioma cells and promoted apoptosis by inhibiting the activation of the MAPK signaling pathway and expression of β-catenin. Lactic acid produced by glycolysis upregulates the expression of PLEKHA4 in glioma cells.
Humans ; Animals ; Mice ; Up-Regulation ; beta Catenin/metabolism* ; Mice, Nude ; Brain Neoplasms/pathology* ; Lactic Acid ; Cell Line, Tumor ; Glioma/pathology* ; Cell Proliferation ; Apoptosis ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; RNA, Messenger/genetics* ; Gene Expression Regulation, Neoplastic

Objective: To investigate the molecular mechanism of how lactate induces high mobility group box 1 (HMGB1) release. Methods: Gastric cancer HGC-27 cells were divided into the control group and the lactate group (The cells were treated with lactate for 6 h). The level of HMGB1 in the cell culture medium was detected by enzyme-linked immunosorbent assay (ELISA), the localization of HMGB1 was detected using laser confocal microscopy, and the nuclear translocation of HMGB1 was detected using the nucleoplasmic separation assay. The phosphorylation and acetylation levels of HMGB1 were determined by co-immunoprecipitation, and Western blot was used to measure the phosphorylation of Akt and protein kinase C (PKC). HGC-27 cells were first treated with lactate and LY294002, the inhibitor of Akt, and then the phosphorylation of HMGB1 and Akt was analyzed by co-immunoprecipitation and Western blot, respectively. The localization of HMGB1 in cells was detected by laser confocal microscopy. EdU and Transwell assays were used to detect the proliferation and migration abilities of HGC-27 cells, respectively. HGC-27 cells were then injected into the BALB/C null mice for subcutaneous tumor implantation. Mice in the lactate group were intraperitoneally injected with lactate (0.2 g/kg/2 d), while those in the control group were intraperitoneally injected with an equal amount of PBS for 20 consecutive days. ELISA was used to detect the HMGB1 levels in the blood samples taken from the medial canthus vein of the mice, while co-immunoprecipitation and Western blot were used to detect the phosphorylation of HMGB1 and Akt in tumor tissue proteins, respectively. Results: The release levels of HMGB1 in the lactate group were (2 995.00±660.91) pg/ml and (696.33±22.03) pg/ml, after lactate treatment for 6 h and 12 h, respectively, both higher than those in the control group (485.00±105.83) pg/ml (P<0.001 and P=0.028, respectively). After lactate treatment for 6 h, the relative expression of HMGB1 protein in the cytoplasm of HGC-27 cells was 1.13±0.09, higher than that of the control group (0.83±0.07, P=0.001), while the relative expression of HMGB1 in the nucleus was 0.79±0.06, lower than that of the control group (1.07±0.06, P=0.007). The phosphorylation level of HMGB1 reached 1.41±0.09, which was higher than that of the control group (0.97±0.10, P=0.031). The phosphorylation level of Akt was 11.16±0.06, higher than that of the control group (0.91±0.022, P=0.002). The phosphorylation level and nuclear translocation of HMGB1 induced by lactate decreased obviously after Akt inhibition; the proliferation and migration abilities induced by lactate were also obviously inhibited after Akt inhibition. In vivo, the HMGB1 level in the peripheral blood was (1 280.70±389.66) pg/ml in the lactate group, which was obviously higher than that in the control group (595.11±44.75) pg/ml (P=0.008), and the phosphorylation levels of HMGB1 and Akt in tumor tissues in the lactate group were obviously enhanced compared with the control group. Conclusion: Lactate induces HMGB1 release through enhancing HMGB1 phosphorylation via the Akt signaling pathway.
Mice ; Animals ; Stomach Neoplasms/pathology* ; Proto-Oncogene Proteins c-akt/metabolism* ; HMGB1 Protein/metabolism* ; Phosphorylation ; Lactic Acid ; Mice, Inbred BALB C ; Signal Transduction