Role of Lactate in Inflammatory Processes: Friend or Foe

Effects of volume management on free flap perfusion and metabolism in a large animal model study

Free flap failure represents a substantial clinical burden. The role of intraoperative volume management remains controversial, with valid studies lacking. Here, using a large animal model, we investigated the influence of volume management on free flap perfusion and metabolism. Autotransfer of a musculocutaneous gracilis flap was performed on 31 German domestic pigs, with arterial anastomosis and catheterization of the pedicle vein for sequential blood sampling. Flap reperfusion was followed by induction of a hemorrhagic shock with maintenance for 30 min and subsequent circulation stabilization with crystalloid solution, crystalloid solution and catecholamine, autotransfusion or colloidal solution. Flap perfusion and oxygenation were periodically assessed using hyperspectral imaging. Flap metabolism was assessed via periodic blood gas analyses. Hyperspectral imaging revealed no difference in either superficial or deep tissue oxygen saturation, tissue hemoglobin or tissue water content between the test groups at any time point. Blood gas analyses showed that lactate levels were significantly increased in the group that received crystalloid solution and catecholamine, after circulatory stabilization and up to 2 h after. We conclude that, in hemorrhagic shock, volume management impacts acid-base balance in free flaps. Crystalloid solutions with norepinephrine increase lactate levels, yet short-term effects on flap perfusion seem minimal, suggesting that vasopressors are not detrimental.

Caulerpa chemnitzia polysaccharide exerts immunomodulatory activity in macrophages by mediating the succinate/PHD2/HIF-1α/IL-1β pathway

Algal polysaccharide is an important food functional factor with diverse bioactive and low toxicity. Previous studies have confirmed Caulerpa chemnitzia polysaccharides (CRVP) have immunomodulatory activity, but the immunomodulatory mechanism of CRVP in macrophages has not been thoroughly explored yet. In our research, we found that CRVP has outstanding immunomodulatory activity in macrophages, which is reflected in promoting cell proliferation, upregulating cytokines (IL-1β, IL-6, and TNF-α) expression, and increasing NO and ROS levels. Additionally, the result of joint analysis of untargeted metabolomics showed metabolism played a major role in the immunomodulatory of CRVP and suggested succinic acid was a key metabolite. Further verification indicated that the accumulation of succinic acid in macrophages after administered with CRVP, induced the down-regulation of prolyl hydroxylase domain 2 (PHD2) and up-regulation of hypoxia-inducible factor-1α (HIF-1α), thereby enhancing IL-1β expression. Together, the immunomodulatory activity of CRVP in macrophages via succinate/PHD2/HIF-1α/IL-1β pathway.

IC100, a humanized therapeutic monoclonal anti-ASC antibody alleviates oxygen-induced retinopathy in mice

BACKGROUND

Retinopathy of prematurity (ROP), which often presents with bronchopulmonary dysplasia (BPD), is among the most common morbidities affecting extremely premature infants and is a leading cause of severe vision impairment in children worldwide. Activations of the inflammasome cascade and microglia have been implicated in playing a role in the development of both ROP and BPD. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is pivotal in inflammasome assembly. Utilizing mouse models of both oxygen-induced retinopathy (OIR) and BPD, this study was designed to test the hypothesis that hyperoxia induces ASC speck formation, which leads to microglial activation and retinopathy, and that inhibition of ASC speck formation by a humanized monoclonal antibody, IC100, directed against ASC, will ameliorate microglial activation and abnormal retinal vascular formation.

METHODS

We first tested ASC speck formation in the retina of ASC-citrine reporter mice expressing ASC fusion protein with a C-terminal citrine (fluorescent GFP isoform) using a BPD model that causes both lung and eye injury by exposing newborn mice to room air (RA) or 85% O2 from postnatal day (P) 1 to P14. The retinas were dissected on P14 and retinal flat mounts were used to detect vascular endothelium with AF-594-conjugated isolectin B4 (IB4) and citrine-tagged ASC specks. To assess the effects of IC100 on an OIR model, newborn ASC citrine reporter mice and wildtype mice (C57BL/6 J) were exposed to RA from P1 to P6, then 75% O2 from P7 to P11, and then to RA from P12 to P18. At P12 mice were randomized to the following groups: RA with placebo PBS (RA-PBS), O2 with PBS (O2-PBS), O2 + IC100 intravitreal injection (O2-IC100-IVT), and O2 + IC100 intraperitoneal injection (O2-IC100-IP). Retinal vascularization was evaluated by flat mount staining with IB4. Microglial activation was detected by immunofluorescence staining for allograft inflammatory factor 1 (AIF-1) and CD206. Retinal structure was analyzed on H&E-stained sections, and function was analyzed by pattern electroretinography (PERG). RNA-sequencing (RNA-seq) of the retinas was performed to determine the transcriptional effects of IC100 treatment in OIR.

RESULTS

ASC specks were significantly increased in the retinas by hyperoxia exposure and colocalized with the abnormal vasculature in both BPD and OIR models, and this was associated with increased microglial activation. Treatment with IC100-IVT or IC100-IP significantly reduced vaso-obliteration and intravitreal neovascularization. IC100-IVT treatment also reduced retinal microglial activation, restored retinal structure, and improved retinal function. RNA-seq showed that IC100 treatment corrected the induction of genes associated with angiogenesis, leukocyte migration, and VEGF signaling caused by O2. IC100 also corrected the suppression of genes associated with cell junction assembly, neuron projection, and neuron recognition caused by O2.

CONCLUSION

These data demonstrate the crucial role of ASC in the pathogenesis of OIR and the efficacy of a humanized therapeutic anti-ASC antibody in treating OIR mice. Thus, this anti-ASC antibody may potentially be considered in diseases associated with oxygen stresses and retinopathy, such as ROP.

Understanding lactate in the development of Hepatitis B virus-related hepatocellular carcinoma

Hepatitis B Virus (HBV) is a hepatotropic virus that can establish a persistent and chronic infection in humans. Chronic hepatitis B (CHB) infection is associated with an increased risk of hepatic decompensation, cirrhosis, and hepatocellular carcinoma (HCC). Lactate level, as the end product of glycolysis, plays a substantial role in metabolism beyond energy production. Emerging studies indicate that lactate is linked to patient mortality rates, and HBV increases overall glucose consumption and lactate production in hepatocytes. Excessive lactate plays a role in regulating the tumor microenvironment (TME), immune cell function, autophagy, and epigenetic reprogramming. The purpose of this review is to gather and summarize the existing knowledge of the lactate's functions in the dysregulation of the immune system, which can play a crucial role in the development of HBV-related HCC. Therefore, it is reasonable to hypothesize that lactate with intriguing functions can be considered an immunomodulatory metabolite in immunotherapy.

Distinct plasma metabolomic signatures differentiate autoimmune encephalitis from drug-resistant epilepsy

OBJECTIVE

Differentiating forms of autoimmune encephalitis (AE) from other causes of seizures helps expedite immunotherapies in AE patients and informs studies regarding their contrasting pathophysiology. We aimed to investigate whether and how Nuclear Magnetic Resonance (NMR)-based metabolomics could differentiate AE from drug-resistant epilepsy (DRE), and stratify AE subtypes.

METHODS

This study recruited 238 patients: 162 with DRE and 76 AE, including 27 with contactin-associated protein-like 2 (CASPR2), 29 with leucine-rich glioma inactivated 1 (LGI1) and 20 with N-methyl-d-aspartate receptor (NMDAR) antibodies. Plasma samples across the groups were analyzed using NMR spectroscopy and compared with multivariate statistical techniques, such as orthogonal partial least squares discriminant analysis (OPLS-DA).

RESULTS

The OPLS-DA model successfully distinguished AE from DRE patients with a high predictive accuracy of 87.0 ± 3.1% (87.9 ± 3.4% sensitivity and 86.3 ± 3.6% specificity). Further, pairwise OPLS-DA models were able to stratify the three AE subtypes. Plasma metabolomic signatures of AE included decreased high-density lipoprotein (HDL, -(CH2)n-, -CH3), phosphatidylcholine and albumin (lysyl moiety). AE subtype-specific metabolomic signatures were also observed, with increased lactate in CASPR2, increased lactate, glucose, and decreased unsaturated fatty acids (UFA, -CH2CH=) in LGI1, and increased glycoprotein A (GlycA) in NMDAR-antibody patients.

INTERPRETATION

This study presents the first non-antibody-based biomarker for differentiating DRE, AE and AE subtypes. These metabolomics signatures underscore the potential relevance of lipid metabolism and glucose regulation in these neurological disorders, offering a promising adjunct to facilitate the diagnosis and therapeutics.

Lactate Protects Microglia and Neurons from Oxygen-Glucose Deprivation/Reoxygenation

Lactate has received attention as a potential therapeutic intervention for brain diseases, particularly those including energy deficit, exacerbated inflammation, and disrupted redox status, such as cerebral ischemia. However, lactate roles in metabolic or signaling pathways in neural cells remain elusive in the hypoxic and ischemic contexts. Here, we tested the effects of lactate on the survival of a microglial (BV-2) and a neuronal (SH-SY5Y) cell lines during oxygen and glucose deprivation (OGD) or OGD followed by reoxygenation (OGD/R). Lactate signaling was studied by using 3,5-DHBA, an exogenous agonist of lactate receptor GPR81. Inhibition of lactate dehydrogenase (LDH) or monocarboxylate transporters (MCT), using oxamate or 4-CIN, respectively, was performed to evaluate the impact of lactate metabolization and transport on cell viability. The OGD lasted 6 h and the reoxygenation lasted 24 h following OGD (OGD/R). Cell viability, extracellular lactate concentrations, microglial intracellular pH and TNF-ɑ release, and neurite elongation were evaluated. Lactate or 3,5-DHBA treatment during OGD increased microglial survival during reoxygenation. Inhibition of lactate metabolism and transport impaired microglial and neuronal viability. OGD led to intracellular acidification in BV-2 cells, and reoxygenation increased the release of TNF-ɑ, which was reverted by lactate and 3,5-DHBA treatment. Our results suggest that lactate plays a dual role in OGD, acting as a metabolic and a signaling molecule in BV-2 and SH-SY5Y cells. Lactate metabolism and transport are vital for cell survival during OGD. Moreover, lactate treatment and GPR81 activation during OGD promote long-term adaptations that potentially protect cells against secondary cell death during reoxygenation.

"Click" amphotericin B in prodrug nanoformulations for enhanced systemic fungemia treatment

Severe nephrotoxicity and infusion-related side effects pose significant obstacles to the clinical application of Amphotericin B (AmB) in life-threatening systemic fungal infections. In pursuit of a cost-effective and safe formulation, we have introduced multiple phenylboronic acid (PBA) moieties onto a linear dendritic telodendrimer (TD) scaffold, enabling effective AmB conjugation via boronate chemistry through a rapid, high yield, catalysis-free and dialysis-free "Click" drug loading process. Optimized AmB-TD prodrugs self-assemble into monodispersed micelles characterized by small particle sizes and neutral surface charges. AmB prodrugs sustain drug release in circulation, which is accelerated in response to the acidic pH and Reactive Oxygen Species (ROS) in the infection and inflammation. Prodrugs mitigate the AmB aggregation status, reduce cytotoxicity and hemolytic activity compared to Fungizone®, and demonstrate superior antifungal activity to AmBisome®. AmB-PEG5kBA4 has a comparable maximum tolerated dose (MTD) to AmBisome®, while over 20-fold increase than Fungizone®. A single dose of AmB-PEG5kBA4 demonstrates superior efficacy to Fungizone® and AmBisome® in treating systemic fungal infections in both immunocompetent and immunocompromised mice.

Pantoprazole suppresses carcinogenesis and growth of hepatocellular carcinoma by inhibiting glycolysis and Na+/H+ exchange

Hepatocellular carcinoma (HCC) is one of the deadliest cancers. The prevention and therapy for this deadly disease remain a global medical challenge. In this study, we investigated the effect of pantoprazole (PPZ) on the carcinogenesis and growth of HCC. Both diethylnitrosamine (DEN) plus CCl4-induced and DEN plus high fat diet (HFD)-induced HCC models in mice were established. Cytokines and cell proliferation-associated gene in the liver tissues of mice and HCC cells were analyzed. Cellular glycolysis and Na+/H+ exchange activity were measured. The preventive administration of pantoprazole (PPZ) at a clinically relevant low dose markedly suppressed HCC carcinogenesis in both DEN plus CCl4-induced and HFD-induced murine HCC models, whereas the therapeutic administration of PPZ at the dose suppressed the growth of HCC. In the liver tissues of PPZ-treated mice, inflammatory cytokines, IL1, CXCL1, CXCL5, CXCL9, CXCL10, CCL2, CCL5, CCL6, CCL7, CCL20, and CCL22, were reduced. The administration of CXCL1, CXCL5, CCL2, or CCL20 all reversed PPZ-suppressed DEN plus CCL4-induced HCC carcinogenesis in mice. PPZ inhibited the expressions of CCNA2, CCNB2, CCNE2, CDC25C, CDCA5, CDK1, CDK2, TOP2A, TTK, AURKA, and BIRC5 in HCC cells. Further results showed that PPZ reduced the production of these inflammatory cytokines and the expression of these cell proliferation-associated genes through the inhibition of glycolysis and Na+/H+ exchange. In conclusion, PPZ suppresses the carcinogenesis and growth of HCC, which is related to inhibiting the production of inflammatory cytokines and the expression of cell proliferation-associated genes in the liver through the inhibition of glycolysis and Na+/H+ exchange.

Engineered Bacillus subtilis as oral probiotics to enhance clearance of blood lactate

Elevated lactate concentrations are implicated in various acute and chronic diseases such as sepsis and mitochondrial dysfunction, respectively. Conversely, ineffective lactate clearance is associated with poor clinical prognoses and high mortality in these diseases. While several groups have proposed using small molecule inhibitors and enzyme replacement to reduce circulating lactate, there are few practical and effective ways to manage this condition. Recent evidence suggests that lactate is exchanged between systemic circulation and the gut, allowing bidirectional modulation between the gut microbiota and peripheral tissues. Inspired by these findings, this work seeks to engineer spore-forming probiotic B. subtilis strains to enable intestinal delivery of lactate oxidase as a therapeutic enzyme. After strain optimization, we showed that oral administration of engineered B. subtilis spores to the gut of mice reduced elevations in blood lactate in two different mouse models involving exogenous challenge or pharmacologic perturbation without disrupting gut microbiota composition, liver function, or immune homeostasis. Taken together, through the oral delivery of engineered probiotic spores to the gastrointestinal tract, our proof-of-concept study offers a practical strategy to aid in the management of disease states with elevated blood lactate and provides a new approach to 'knocking down' circulating metabolites to help understand their roles in host physiological and pathological processes.

A Case Report of Refractory Hyperlactatemia Secondary to Thiamine Deficiency

Thiamine is an essential water-soluble vitamin that must be obtained through diet. This vitamin is crucial for various biochemical reactions and is vital for aerobic metabolism. When individuals are deficient in thiamine, which can be due to hypermetabolism (such as in inflammation, ischemia, or malnutrition, among other reasons), anaerobic metabolism may be utilized to maintain energy needs. Such chemical processes produce lactic acid. Excess lactic acid can cause various clinical signs and symptoms, though lactate dehydrogenase (LDH) can typically break down this compound. The following case presents a very unusual instance where a 51-year-old Caucasian woman presented with the chief complaint of ongoing and severe abdominal pain. After an extensive work-up ruling out numerous diagnoses and an eight-day hospital stay, it was believed that she may be suffering from hyperlactatemia secondary to thiamine deficiency, as she improved significantly after administration of this vitamin. It was thought that this was likely due to her previous systemic lupus erythematosus (SLE) diagnosis, vasculitis, chronic inflammation, and a hypermetabolic state, in addition to concurrent LDH malfunction.

Yogurt Prevents Colorectal Tumorigenesis in ApcMin/+ Mice

SCOPE

Yogurt consumption is related to a decreased risk of colorectal cancer (CRC), but whether such association is causal remains unclear. Patients with familial adenomatous polyposis (FAP) are at increased risk of CRC development. Here, the study investigates the efficacy of yogurt for intestinal polyposis chemoprevention in ApcMin/+ mice, a preclinical model for human FAP.

METHODS AND RESULTS

A 10-week yogurt supplementation (15 g kg-1) in ApcMin/+ mice significantly reduces the intestinal polyp number (6.50 ± 0.97 versus 1.80 ± 0.49; p < 0.001) compared to controls. 16S rRNA gene-based microbiota analysis suggests that yogurt supplementation may greatly modulate the gut microbiome composition, especially in the relative abundance of Lactobacillus and Bifidobacterium. Importantly, the fecal concentration of d-lactate (d-Lac, 0.39 ± 0.04 µmol g-1 versus 8.14 ± 0.62 µmol g-1; p < 0.001) is boosted by yogurt, while oral administration with d-Lac (125 or 250 mg kg-1) reduces the polyp number by 71.43% or 77.14% (p < 0.001), respectively. The study also observes that d-Lac does not affect cell viability and anchorage-independence in CRC cells, but it greatly suppresses epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation in preneoplastic cells. Mechanistically, it demonstrates that d-Lac may attenuate epithelial cell transformation by targeting PI3K/AKT/β-catenin axis.

CONCLUSION

Yogurt protects against intestinal polyposis in ApcMin/+ mice, and d-Lac may partially account for the chemopreventive effects above.

Lactylation Modification in Cardiometabolic Disorders: Function and Mechanism

Cardiovascular disease (CVD) is recognized as the primary cause of mortality and morbidity on a global scale, and developing a clear treatment is an important tool for improving it. Cardiometabolic disorder (CMD) is a syndrome resulting from the combination of cardiovascular, endocrine, pro-thrombotic, and inflammatory health hazards. Due to their complex pathological mechanisms, there is a lack of effective diagnostic and treatment methods for cardiac metabolic disorders. Lactylation is a type of post-translational modification (PTM) that plays a regulatory role in various cellular physiological processes by inducing changes in the spatial conformation of proteins. Numerous studies have reported that lactylation modification plays a crucial role in post-translational modifications and is closely related to cardiac metabolic diseases. This article discusses the molecular biology of lactylation modifications and outlines the roles and mechanisms of lactylation modifications in cardiometabolic disorders, offering valuable insights for the diagnosis and treatment of such conditions.

Increased Dietary Trp, Thr, and Met Supplementation Improves Performance, Health, and Protein Metabolism of Weaned Piglets under Mixed Management and Poor Housing Conditions

A sanitary challenge was carried out to induce suboptimal herd health while investigating the effect of amino acids supplementation on piglet responses. Weaned piglets of high sanitary status (6.33 ± 0.91 kg of BW) were distributed in a 2 × 2 factorial arrangement into two similar facilities with contrasting sanitary conditions and two different diets. Our results suggest that increased Trp, Thr, and Met dietary supplementation could support the immune systems of piglets under a sanitary challenge. In this manner, AA+ supplementation improved the performance and metabolism of piglets under mixed management and poor sanitary conditions. No major temporal microbiome changes were associated with differences in performance regardless of sanitary conditions or diets. Since piglets often become mixed in multiple-site production systems and facility hygiene is also often neglected, this study suggests that increased Trp, Thr, and Met (AA+) dietary supplementation could contribute to mitigating the side effects of these harmful risk factors in modern pig farms.

Thermoresponsive Polymeric Hydromorphone Prodrug Provides Sustained Local Analgesia without Apparent Adverse Effects

The extensive use of opioids for chronic pain management has contributed significantly to the current opioid epidemic. While many alternative nonopioid analgesics are available, opioids remain the most potent analgesics for moderate to severe pain management. In addition to the implementation of multimodal analgesia, there is a pressing need for the development of more effective and safer opioids. In this study, we developed a thermoresponsive N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based hydromorphone (HMP) prodrug (ProGel-HMP, HMP content = 16.2 wt %, in base form). The aqueous solution of ProGel-HMP was free-flowing at 4 °C but became a hydrogel when the temperature was raised to ≥37 °C, allowing sustained local retention when administered in vivo. When tested in the destabilization of the medial meniscus (DMM) mouse model of osteoarthritis (OA), ProGel-HMP was retained after intra-articular injection in the OA knee joint for at least 2 weeks postinjection, with low extra-articular distribution. ProGel-HMP was not detected in the central nervous system (CNS). A single dose of ProGel-HMP produced rapid and sustained joint pain resolution for greater than 14 days when compared to saline and dose-equivalent HMP controls, likely mediated through peripheral μ-opioid receptors in the knee joint. Systemic analgesia effect was absent in the DMM mice treated with ProGel-HMP, as evident in the lack of difference in tail flick response between the ProGel-HMP-treated mice and the controls (i.e., Healthy, Saline, and Sham). Repeated dosing of ProGel-HMP did not induce tolerance. Collectively, these data support the further development of ProGel-HMP as a potent, safe, long-acting and nonaddictive analgesic for better clinical pain management.

Urban airborne PM2.5 induces pulmonary fibrosis through triggering glycolysis and subsequent modification of histone lactylation in macrophages

Airborne fine particulate matter (PM2.5) can cause pulmonary inflammation and even fibrosis, however, the underlying molecular mechanisms of the pathogenesis of PM2.5 exposure have not been fully appreciated. In the present study, we explored the dynamics of glycolysis and modification of histone lactylation in macrophages induced by PM2.5-exposure in both in vivo and in vitro models. Male C57BL/6 J mice were anesthetized and administrated with PM2.5 by intratracheal instillation once every other day for 4 weeks. Mouse RAW264.7 macrophages and alveolar epithelial MLE-12 cells were treated with PM2.5 for 24 h. We found that PM2.5 significantly increased lactate dehydrogenase (LDH) activities and lactate contents, and up-regulated the mRNA expression of key glycolytic enzymes in the lungs and bronchoalveolar lavage fluids of mice. Moreover, PM2.5 increased the levels of histone lactylation in both PM2.5-exposed lungs and RAW264.7 cells. The pro-fibrotic cytokines secreted from PM2.5-treated RAW264.7 cells triggered epithelial-mesenchymal transition (EMT) in MLE-12 cells through activating transforming growth factor-β (TGF-β)/Smad2/3 and VEGFA/ERK pathways. In contrast, LDHA inhibitor (GNE-140) pretreatment effectively alleviated PM2.5-induced pulmonary inflammation and fibrosis via inhibiting glycolysis and subsequent modification of histone lactylation in mice. Thus, our findings suggest that PM2.5-induced glycolysis and subsequent modification of histone lactylation play critical role in the PM2.5-associated pulmonary fibrosis.

Predictive role of lactate in dogs with acute pancreatitis advanced to systemic inflammatory response syndrome

Acute pancreatitis (AP) can develop into life-threatening conditions such as systemic inflammatory response syndrome (SIRS) or multiple organ dysfunction syndrome. Thirty-nine of 54 client-owned dogs admitted to the Referral Animal Medical Center and diagnosed with AP within 24 hr of onset were retrospectively reviewed to assess early predictors of progression from AP to SIRS. The patients were divided into SIRS (SIRS occurring after AP) and non-SIRS (AP occurring but no SIRS) groups. The population and mean values of laboratory variables within 24 hr of admission were assessed and compared between both groups. There were significantly more dogs with abnormal lactate levels in the SIRS group (80.00%) than non-SIRS group (11.10%). Other parameters did not differ significantly. Mean lactate level values were significantly higher at 3.64 ± 1.75 mmol in the SIRS group compared to 1.68 ± 0.52 mmol in the non-SIRS group. The increased energy required by activated immune cells may lead to metabolic changes characterized by anaerobic glycolysis and increased lactate production. This study's results suggest blood lactate monitoring in the early stages of progression from AP to SIRS in small animal clinical practice. Measuring lactate levels at the early stages of pancreatitis could lead to rapid therapeutic intervention for SIRS and ultimately reduce mortality.

Lactate/Hydroxycarboxylic Acid Receptor 1 in Alzheimer's Disease: Mechanisms and Therapeutic Implications-Exercise Perspective

Lactate has a novel function different from previously known functions despite its traditional association with hypoxia in skeletal muscle. It plays various direct and indirect physiological functions. It is a vital energy source within the central nervous system (CNS) and a signal transmitter regulating crucial processes, such as angiogenesis and inflammation. Activating lactate and its associated receptors elicits effects like synaptic plasticity and angiogenesis alterations. These effects can significantly influence the astrocyte-neuron lactate shuttle, potentially impacting cognitive performance. Decreased cognitive function relates to different neurodegenerative conditions, including Alzheimer's disease (AD), ischemic brain injury, and frontotemporal dementia. Therefore, lactic acid has significant potential for treating neurodegenerative disorders. Exercise is a method that induces the production of lactic acid, which is similar to the effect of lactate injections. It is a harmless and natural way to achieve comparable results. Animal experiments demonstrate that high-intensity intermittent exercise can increase vascular endothelial growth factor (VEGF) levels, thus promoting angiogenesis. In vivo, lactate receptor-hydroxycarboxylic acid receptor 1 (HCAR1) activation can occur by various stimuli, including variations in ion concentrations, cyclic adenosine monophosphate (cAMP) level elevations, and fluctuations in the availability of energy substrates. While several articles have been published on the benefits of physical activity on developing Alzheimer's disease in the CNS, could lactic acid act as a bridge? Understanding how HCAR1 responds to these signals and initiates associated pathways remains incomplete. This review comprehensively analyzes lactate-induced signaling pathways, investigating their influence on neuroinflammation, neurodegeneration, and cognitive decline. Consequently, this study describes the unique role of lactate in the progression of Alzheimer's disease.

Lactate Protects Intestinal Epithelial Barrier Function from Dextran Sulfate Sodium-Induced Damage by GPR81 Signaling

The dysregulation of the intestinal epithelial barrier significantly contributes to the inflammatory progression of ulcerative colitis. Recent studies have indicated that lactate, produced by gut bacteria or derived from fermented foods, plays a key role in modulating inflammation via G-protein-coupled receptor 81 (GPR81). In this study, we aimed to investigate the potential role of GPR81 in the progression of colitis and to assess the impact of lactate/GPR81 signaling on intestinal epithelial barrier function. Our findings demonstrated a downregulation of GPR81 protein expression in patients with colitis. Functional verification experiments showed that Gpr81-deficient mice exhibited more severe damage to the intestinal epithelial barrier and increased susceptibility to DSS-induced colitis, characterized by exacerbated oxidative stress, elevated inflammatory cytokine secretion, and impaired expression of tight-junction proteins. Mechanistically, we found that lactate could suppress TNF-α-induced MMP-9 expression and prevent the disruption of tight-junction proteins by inhibiting NF-κB activation through GPR81 in vitro. Furthermore, our study showed that dietary lactate could preserve intestinal epithelial barrier function against DSS-induced damage in a GPR81-dependent manner in vivo. Collectively, these results underscore the crucial involvement of the lactate/GPR81 signaling pathway in maintaining intestinal epithelial barrier function, providing a potential therapeutic strategy for ulcerative colitis.

Excess fermentation and lactic acidosis as detrimental functions of the gut microbes in treatment-naive TB patients

Introduction

The link between gut microbiota and host immunity motivated numerous studies of the gut microbiome in tuberculosis (TB) patients. However, these studies did not explore the metabolic capacity of the gut community, which is a key axis of impact on the host's immunity.

Methods

We used deep sequencing of fecal samples from 23 treatment-naive TB patients and 48 healthy donors to reconstruct the gut microbiome's metabolic capacity and strain/species-level content.

Results

We show that the systematic depletion of the commensal flora of the large intestine, Bacteroidetes, and an increase in Actinobacteria, Firmicutes, and Proteobacteria such as Streptococcaceae, Erysipelotrichaceae, Lachnospiraceae, and Enterobacteriaceae explains the strong taxonomic divergence of the gut community in TB patients. The cumulative expansion of diverse disease-associated pathobionts in patients reached 1/4 of the total gut microbiota, suggesting a heavy toll on host immunity along with MTB infection. Reconstruction of metabolic pathways showed that the microbial community in patients shifted toward rapid growth using glycolysis and excess fermentation to produce acetate and lactate. Higher glucose availability in the intestine likely drives fermentation to lactate and growth, causing acidosis and endotoxemia.

Discussion

Excessive fermentation and lactic acidosis likely characterize TB patients' disturbed gut microbiomes. Since lactic acidosis strongly suppresses the normal gut flora, directly interferes with macrophage function, and is linked to mortality in TB patients, our findings highlight gut lactate acidosis as a novel research focus. If confirmed, gut acidosis may be a novel potential host-directed treatment target to augment traditional TB treatment.

Characterizing the Inflammatory Profile of Neutrophil-Rich Triple-Negative Breast Cancer

Breast cancer (BC) is one of the most common types of cancer in women in the United Arab Emirates. Immunogenic tumours, such as triple-negative breast cancer (TNBC), show increased neutrophil infiltration, which is associated with poor prognosis and limited efficacy of immunotherapy. This study aims to investigate in vitro the bidirectional effect of neutrophils on metastatic TNBC (MDA-MB-231) compared to less-metastatic luminal breast cancer (MCF-7) cell lines. We found that BC cells or their conditioned medium (CM) reduced the viability of neutrophil-like cells (HL60). This was supported by increased cellular stress and NETosis in differentiated HL60 cells (dHL60) upon exposure to MDA-MB-231 compared to MCF-7-CM using nucleic acid staining essays. Flow cytometry showed comparable expression of inflammatory markers by polymorphonuclear cells (PMN) when treated with MDA-MB-231-CM and standard polarizing cocktails. Furthermore, MDA-MB-231-CM triggered an inflammatory pattern with evidence of stronger adhesion (CD62L) and degranulation (CD11b and CD66b) phenotypes. The proinflammatory polarization of dHL60 by MDA-MB-231-CM was additionally confirmed by the elevated CD54 expression, myeloperoxidase, and CD11b protein levels, which matched an increased transwell migratory capacity. In conclusion, BC might use neutrophils to their benefit through NETosis and complement system activation, which makes this crosstalk a potential mechanism for understanding tumour progression.

TRPV1 Channel in Human Eosinophils: Functional Expression and Inflammatory Modulation

The transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel expressed on sensory neurons and immune cells. We hypothesize that TRPV1 plays a role in human eosinophil function and is modulated by inflammatory conditions. TRPV1 expression on human eosinophils was examined by qPCR, flow cytometry, and immunohistochemistry, respectively. TRPV1 functionality was analyzed by investigating calcium flux, apoptosis, modulation by cytokines and acidic pH, and CD69 externalization using flow cytometry. Activation of TRPV1 induced calcium influx and prolonged survival. Although eosinophils were not directly activated by TRPV1 agonists, activation by IL-3 or GM-CSF was mainly restricted to TRPV1-positive eosinophils. TRPV1 surface content was increased by acidic pH, IL-3, IL-31, IL-33, TSLP, TNF-α, BDNF, and NGF-β. Interestingly, TRPV1 was also expressed by eosinophils located in proximity to peripheral nerves in atopic dermatitis (AD) skin. In conclusion, eosinophils express functional TRPV1 channels which are increased by extracellular acidification and AD-related cytokines. Since eosinophils also express TRPV1 in AD skin, our results indicate an important role of TRPV1 for neuroimmune interaction mechanisms in itchy, inflammatory skin diseases, like AD.

NEDD4 lactylation promotes APAP induced liver injury through Caspase11 dependent non-canonical pyroptosis

Caspase-11 detection of intracellular lipopolysaccharide mediates non-canonical pyroptosis, which could result in inflammatory damage and organ lesions in various diseases such as sepsis. Our research found that lactate from the microenvironment of acetaminophen-induced acute liver injury increased Caspase-11 levels, enhanced gasdermin D activation and accelerated macrophage pyroptosis, which lead to exacerbation of liver injury. Further experiments unveiled that lactate inhibits Caspase-11 ubiquitination by reducing its binding to NEDD4, a negative regulator of Caspase-11. We also identified that lactates regulated NEDD4 K33 lactylation, which inhibits protein interactions between Caspase-11 and NEDD4. Moreover, restraining lactylation reduces non-canonical pyroptosis in macrophages and ameliorates liver injury. Our work links lactate to the exquisite regulation of the non-canonical inflammasome, and provides a basis for targeting lactylation signaling to combat Caspase-11-mediated non-canonical pyroptosis and acetaminophen-induced liver injury.

Metformin Attenuates Neutrophil Recruitment through the H3K18 Lactylation/Reactive Oxygen Species Pathway in Zebrafish

Beyond its well-established role in diabetes management, metformin has gained attention as a promising therapeutic for inflammation-related diseases, largely due to its antioxidant capabilities. However, the mechanistic underpinnings of this effect remain elusive. Using in vivo zebrafish models of inflammation, we explored the impact of metformin on neutrophil recruitment and the underlying mechanisms involved. Our data indicate that metformin reduces histone (H3K18) lactylation, leading to the decreased production of reactive oxygen species (ROS) and a muted neutrophil response to both caudal fin injury and otic vesicle inflammation. To investigate the precise mechanisms through which metformin modulates neutrophil migration via ROS and H3K18 lactylation, we meticulously established the correlation between metformin-induced suppression of H3K18 lactylation and ROS levels. Through supplementary experiments involving the restoration of lactate and ROS, our findings demonstrated that elevated levels of both lactate and ROS significantly promoted the inflammatory response in zebrafish. Collectively, our study illuminates previously unexplored avenues of metformin's antioxidant and anti-inflammatory actions through the downregulation of H3K18 lactylation and ROS production, highlighting the crucial role of epigenetic regulation in inflammation and pointing to metformin's potential in treating inflammation-associated conditions.

Metabolism Serves as a Bridge Between Cardiomyocytes and Immune Cells in Cardiovascular Diseases

Metabolic disorders of cardiomyocytes play an important role in the progression of various cardiovascular diseases. Metabolic reprogramming can provide ATP to cardiomyocytes and protect them during diseases, but this transformation also leads to adverse consequences such as oxidative stress, mitochondrial dysfunction, and eventually aggravates myocardial injury. Moreover, abnormal accumulation of metabolites induced by metabolic reprogramming of cardiomyocytes alters the cardiac microenvironment and affects the metabolism of immune cells. Immunometabolism, as a research hotspot, is involved in regulating the phenotype and function of immune cells. After myocardial injury, both cardiac resident immune cells and heart-infiltrating immune cells significantly contribute to the inflammation, repair and remodeling of the heart. In addition, metabolites generated by the metabolic reprogramming of immune cells can further affect the microenvironment, thereby affecting the function of cardiomyocytes and other immune cells. Therefore, metabolic reprogramming and abnormal metabolite levels may serve as a bridge between cardiomyocytes and immune cells, leading to the development of cardiovascular diseases. Herein, we summarize the metabolic relationship between cardiomyocytes and immune cells in cardiovascular diseases, and the effect on cardiac injury, which could be therapeutic strategy for cardiovascular diseases, especially in drug research.

Standardized Pre-clinical Surgical Animal Model Protocol to Investigate the Cellular and Molecular Mechanisms of Ischemic Flap Healing

BACKGROUND

Some of the most complex surgical interventions to treat trauma and cancer include the use of locoregional pedicled and free autologous tissue transfer flaps. While the techniques used for these reconstructive surgery procedures have improved over time, flap complications and even failure remain a significant clinical challenge. Animal models are useful in studying the pathophysiology of ischemic flaps, but when repeatability is a primary focus of a study, conventional in-vivo designs, where one randomized subset of animals serves as a treatment group while a second subset serves as a control, are at a disadvantage instigated by greater subject-to-subject variability. Our goal was to provide a step-by-step methodological protocol for creating an alternative standardized, more economical, and transferable pre-clinical animal research model of excisional full-thickness wound healing following a simulated autologous tissue transfer which includes the primary ischemia, reperfusion, and secondary ischemia events with the latter mimicking flap salvage procedure.

RESULTS

Unlike in the most frequently used classical unilateral McFarlane's caudally based dorsal random pattern skin flap model, in the herein described bilateral epigastric fasciocutaneous advancement flap (BEFAF) model, one flap heals under normal and a contralateral flap-under perturbed conditions or both flaps heal under conditions that vary by one within-subjects factor. We discuss the advantages and limitations of the proposed experimental approach and, as a part of model validation, provide the examples of its use in laboratory rat (Rattus norvegicus) axial pattern flap healing studies.

CONCLUSIONS

This technically challenging but feasible reconstructive surgery model eliminates inter-subject variability, while concomitantly minimizing the number of animals needed to achieve adequate statistical power. BEFAFs may be used to investigate the spatiotemporal cellular and molecular responses to complex tissue injury, interventions simulating clinically relevant flap complications (e.g., vascular thrombosis) as well as prophylactic, therapeutic or surgical treatment (e.g., flap delay) strategies in the presence or absence of confounding risk factors (e.g., substance abuse, irradiation, diabetes) or favorable wound-healing promoting activities (e.g., exercise). Detailed visual instructions in BEFAF protocol may serve as an aid for teaching medical or academic researchers basic vascular microsurgery techniques that focus on precision, tremor management and magnification.

Clinical metabolic monitoring to inform metabolic dysregulation in sepsis

OBJECTIVE

The objective of this study was to offer further evidence of the utility of metabolic monitoring in early recognition of sepsis. Metabolic derangement in sepsis is of increasing interest. Sepsis was redefined as a dysregulated host response to infection, and studies have since emerged advising that disrupted metabolic pathways in sepsis may interfere with the host's ability to convert oxygen to useable energy. Indirect calorimetry (IC) is a metabolic monitoring technology that measures oxygen consumption (V02) and resting energy expenditure (REE). IC offers clinically important, specific information in terms of patient's metabolic state and has been shown to differentiate patients with sepsis from those without. Additionally, IC is more specific than predictive equations used as the established standard for clinical nutrition.

RESEARCH METHODS AND PROCEDURES

Data for this retrospective descriptive study were obtained from chart review of records of critically ill patients who received metabolic monitoring while under the care of the nutrition support team. Data were retrieved from January through March of 2020. The cases included were from January 2018 through January 2020. Variables included key demographics, sepsis diagnosis and specific metabolic variables of cellular respiration and energy expenditure.

RESULTS

For this all-male sample (N = 56), mean age was 56 years (±17.5). Significant differences were noted in V02 between the two groups of cases (sepsis and non-sepsis); (p = .026, Cohen's d = 0.618); and REE (p = .032, Cohen's d = 0.607). A strong association was found between V02 and sepsis (Eta 0.981). REE as measured by IC was statistically more specific than predictive equation (p < .001, Cohen's d = 0.527).

CONCLUSIONS

VO2 and REE were significantly altered in subjects with sepsis in this study, demonstrating that IC may be a useful tool in identifying sepsis. This study was based on an earlier pilot which yielded similar results. Indirect calorimetry can be easily performed clinically, offering specific metabolic information that can be helpful in the determination of a diagnosis of sepsis.

PATIENT OR PUBLIC CONTRIBUTION

No patient or public contribution to this manuscript. The study design, analysis of retrospective data, and manuscript preparation were completed entirely by the authors.

IMPLICATIONS FOR CLINICIANS

Sepsis remains one of the number one killers of hospitalized patients globally Current means of identifying sepsis remain overly sensitive and under-specific, making recognition of sepsis challenging for Emergency Clinicians Metabolic monitoring can be done easily in the clinical setting by nurses and respiratory therapists. Metabolic monitoring has the capability of offering further information specific to the identification of sepsis, and to further understanding of the altered metabolic phenotype of patients with sepsis.

Adverse childhood experiences and reoccurrence of illness impact the gut microbiome, which affects suicidal behaviours and the phenome of major depression: towards enterotypic phenotypes

The first publication demonstrating that major depressive disorder (MDD) is associated with alterations in the gut microbiota appeared in 2008 (Maes et al., 2008). The purpose of the present study is to delineate a) the microbiome signature of the phenome of depression, including suicidal behaviours (SB) and cognitive deficits; the effects of adverse childhood experiences (ACEs) and recurrence of illness index (ROI) on the microbiome; and the microbiome signature of lowered high-density lipoprotein cholesterol (HDLc). We determined isometric log-ratio abundances or prevalences of gut microbiome phyla, genera, and species by analysing stool samples from 37 healthy Thai controls and 32 MDD patients using 16S rDNA sequencing. Six microbiome taxa accounted for 36% of the variance in the depression phenome, namely Hungatella and Fusicatenibacter (positive associations) and Butyricicoccus, Clostridium, Parabacteroides merdae, and Desulfovibrio piger (inverse association). This profile (labelled enterotype 1) indicates compositional dysbiosis, is strongly predicted by ACE and ROI, and is linked to SB. A second enterotype was developed that predicted a decrease in HDLc and an increase in the atherogenic index of plasma (Bifidobacterium, P. merdae, and Romboutsia were positively associated, while Proteobacteria and Clostridium sensu stricto were negatively associated). Together, enterotypes 1 and 2 explained 40.4% of the variance in the depression phenome, and enterotype 1 in conjunction with HDLc explained 39.9% of the variance in current SB. In conclusion, the microimmuneoxysome is a potential new drug target for the treatment of severe depression and SB and possibly for the prevention of future episodes.

The role of lactate in cardiovascular diseases

Cardiovascular diseases pose a major threat worldwide. Common cardiovascular diseases include acute myocardial infarction (AMI), heart failure, atrial fibrillation (AF) and atherosclerosis. Glycolysis process often has changed during these cardiovascular diseases. Lactate, the end-product of glycolysis, has been overlooked in the past but has gradually been identified to play major biological functions in recent years. Similarly, the role of lactate in cardiovascular disease is gradually being recognized. Targeting lactate production, regulating lactate transport, and modulating circulating lactate levels may serve as potential strategies for the treatment of cardiovascular diseases in the future. The purpose of this review is to integrate relevant clinical and basic research on the role of lactate in the pathophysiological process of cardiovascular disease in recent years to clarify the important role of lactate in cardiovascular disease and to guide further studies exploring the role of lactate in cardiovascular and other diseases. Video Abstract.

Construction of an Exudative Age-Related Macular Degeneration Diagnostic and Therapeutic Molecular Network Using Multi-Layer Network Analysis, a Fuzzy Logic Model, and Deep Learning Techniques: Are Retinal and Brain Neurodegenerative Disorders Related?

Neovascular age-related macular degeneration (nAMD) is a leading cause of irreversible visual impairment in the elderly. The current management of nAMD is limited and involves regular intravitreal administration of anti-vascular endothelial growth factor (anti-VEGF). However, the effectiveness of these treatments is limited by overlapping and compensatory pathways leading to unresponsiveness to anti-VEGF treatments in a significant portion of nAMD patients. Therefore, a system view of pathways involved in pathophysiology of nAMD will have significant clinical value. The aim of this study was to identify proteins, miRNAs, long non-coding RNAs (lncRNAs), various metabolites, and single-nucleotide polymorphisms (SNPs) with a significant role in the pathogenesis of nAMD. To accomplish this goal, we conducted a multi-layer network analysis, which identified 30 key genes, six miRNAs, and four lncRNAs. We also found three key metabolites that are common with AMD, Alzheimer's disease (AD) and schizophrenia. Moreover, we identified nine key SNPs and their related genes that are common among AMD, AD, schizophrenia, multiple sclerosis (MS), and Parkinson's disease (PD). Thus, our findings suggest that there exists a connection between nAMD and the aforementioned neurodegenerative disorders. In addition, our study also demonstrates the effectiveness of using artificial intelligence, specifically the LSTM network, a fuzzy logic model, and genetic algorithms, to identify important metabolites in complex metabolic pathways to open new avenues for the design and/or repurposing of drugs for nAMD treatment.

Lactate dehydrogenase contribution to symptom persistence in long COVID: A pooled analysis

There's critical need for risk predictors in long COVID. This meta-analysis evaluates the evidence for an association between plasma lactate dehydrogenase (LDH) and long COVID and explores the contribution of LDH to symptoms persistent across the distinct post-acute sequelae of COVID-19 (PASC) domains. PubMed, EMBASE, Web of Science, and Google Scholar were searched for articles published up to 20 March 2023 for studies that reported data on LDH levels in COVID-19 survivors with and without PASC. Random-effect meta-analysis was employed to estimate the standardized mean difference (SMD) with corresponding 95% confidence interval of each outcome. There were a total of 8289 study participants (3338 PASC vs. 4951 controls) from 46 studies. Our meta-analysis compared to the controls showed a significant association between LDH elevation and Resp-PASC [SMD = 1.07, 95%CI = 0.72, 1.41, p = 0.01] but not Cardio-PASC [SMD = 1.79, 95%CI = -0.02, 3.61, p = 0.05], Neuro-PASC [SMD = 0.19, 95%CI = -0.24, 0.61, p = 0.40], and Gastrointestinal-PASC [SMD = 0.45, 95%CI = -1.08, 1.98, p = 0.56]. This meta-analysis suggests elevated LDH can be used for predicting Resp-PASC, but not Cardio-PASC, Neuro-PASC or gastrointestinal-PASC. Thus, elevated plasma LDH following COVID infection may be considered as a disease biomarker.

Histone lactylation regulates cancer progression by reshaping the tumor microenvironment

As a major product of glycolysis and a vital signaling molecule, many studies have reported the key role of lactate in tumor progression and cell fate determination. Lactylation is a newly discovered post-translational modification induced by lactate. On the one hand, lactylation introduced a new era of lactate metabolism in the tumor microenvironment (TME), and on the other hand, it provided a key breakthrough point for elucidation of the interaction between tumor metabolic reprogramming and epigenetic modification. Studies have shown that the lactylation of tumor cells, tumor stem cells and tumor-infiltrating immune cells in TME can participate in the development of cancer through downstream transcriptional regulation, and is a potential and promising tumor treatment target. This review summarized the discovery and effects of lactylation, as well as recent research on histone lactylation regulating cancer progression through reshaping TME. We also focused on new strategies to enhance anti-tumor effects via targeting lactylation. Finally, we discussed the limitations of existing studies and proposed new perspectives for future research in order to further explore lactylation targets. It may provide a new way and direction to improve tumor prognosis.

The resolution of phagosomes

Phagocytosis is a fundamental immunobiological process responsible for the removal of harmful particulates. While the number of phagocytic events achieved by a single phagocyte can be remarkable, exceeding hundreds per day, the same phagocytic cells are relatively long-lived. It should therefore be obvious that phagocytic meals must be resolved in order to maintain the responsiveness of the phagocyte and to avoid storage defects. In this article, we discuss the mechanisms involved in the resolution process, including solute transport pathways and membrane traffic. We describe how products liberated in phagolysosomes support phagocyte metabolism and the immune response. We also speculate on mechanisms involved in the redistribution of phagosomal metabolites back to circulation. Finally, we highlight the pathologies owed to impaired phagosome resolution, which range from storage disorders to neurodegenerative diseases.

Insights on the role of L-lactate as a signaling molecule in skin aging

L-lactate is a catabolite from the anaerobic metabolism of glucose, which plays a paramount role as a signaling molecule in various steps of the cell survival. Its activity, as a master tuner of many mechanisms underlying the aging process, for example in the skin, is still presumptive, however its crucial position in the complex cross-talk between mitochondria and the process of cell survival, should suggest that L-lactate may be not a simple waste product but a fine regulator of the aging/survival machinery, probably via mito-hormesis. Actually, emerging evidence is highlighting that ROS are crucial in the signaling of skin health, including mechanisms underlying wound repair, renewal and aging. The ROS, including superoxide anion, hydrogen peroxide, and nitric oxide, play both beneficial and detrimental roles depending upon their levels and cellular microenvironment. Physiological ROS levels are essential for cutaneous health and the wound repair process. Aberrant redox signaling activity drives chronic skin disease in elderly. On the contrary, impaired redox modulation, due to enhanced ROS generation and/or reduced levels of antioxidant defense, suppresses wound healing via promoting lymphatic/vascular endothelial cell apoptosis and death. This review tries to elucidate this issue.

Epigenetic meets metabolism: novel vulnerabilities to fight cancer

Histones undergo a plethora of post-translational modifications (PTMs) that regulate nucleosome and chromatin dynamics and thus dictate cell fate. Several evidences suggest that the accumulation of epigenetic alterations is one of the key driving forces triggering aberrant cellular proliferation, invasion, metastasis and chemoresistance pathways. Recently a novel class of histone "non-enzymatic covalent modifications" (NECMs), correlating epigenome landscape and metabolic rewiring, have been described. These modifications are tightly related to cell metabolic fitness and are able to impair chromatin architecture. During metabolic reprogramming, the high metabolic flux induces the accumulation of metabolic intermediate and/or by-products able to react with histone tails altering epigenome homeostasis. The accumulation of histone NECMs is a damaging condition that cancer cells counteracts by overexpressing peculiar "eraser" enzymes capable of removing these modifications preserving histones architecture. In this review we explored the well-established NECMs, emphasizing the role of their corresponding eraser enzymes. Additionally, we provide a parterre of drugs aiming to target those eraser enzymes with the intent to propose novel routes of personalized medicine based on the identification of epi-biomarkers which might be selectively targeted for therapy. Video Abstract.

Identifying possible biomarkers of lower urinary tract symptoms using metabolomics and partial least square regression

INTRODUCTION

The objective of this study was to explore potential novel biomarkers for moderate to severe lower urinary tract symptoms (LUTS) using a metabolomics-based approach, and statistical methods with significant different features than previous reported.

MATERIALS AND METHODS

The patients and the controls were selected to participate in the study according to inclusion/exclusion criteria (n = 82). We recorded the following variables: International prostatic symptom score (IPSS), prostate volume, comorbidities, PSA, height, weight, triglycerides, glycemia, HDL cholesterol, and blood pressure. The study of 41 plasma metabolites was done using the nuclear magnetic resonance spectroscopy technique. First, the correlations between the metabolites and the IPSS were done using Pearson. Second, significant biomarkers of LUTS from metabolites were further analysed using a multiple linear regression model. Finally, we validated the findings using partial least square regression (PLS).

RESULTS

Small to moderate correlations were found between IPSS and methionine (-0.301), threonine (-0.320), lactic acid (0.294), pyruvic acid (0.207) and 2-aminobutyric-acid (0.229). The multiple linear regression model revealed that only threonine (p = 0.022) was significantly associated with IPSS, whereas methionine (p = 0.103), lactic acid (p = 0.093), pyruvic acid (p = 0.847) and 2-aminobutyric-acid (p = 0.244) lost their significance. However, all metabolites lost their significance in the PLS model.

CONCLUSION

When using the robust PLS-regression method, none of the metabolites in our analysis had a significant association with lower urinary tract symptoms. This highlights the importance of using appropriate statistical methods when exploring new biomarkers in urology.

Probing the substrate binding modes and catalytic mechanisms of BLEG-1, a promiscuous B3 metallo-β-lactamase with glyoxalase II properties

BLEG-1 from Bacillus lehensis G1 is an evolutionary divergent B3 metallo-β-lactamase (MBL) that exhibited both β-lactamase and glyoxalase II (GLXII) activities. Sequence, phylogeny, biochemical and structural relatedness of BLEG-1 to B3 MBL and GLXII suggested BLEG-1 might be an intermediate in the evolutionary path of B3 MBL from GLXII. The unique active site cavity of BLEG-1 that recognizes both β-lactam antibiotics and S-D-lactoylglutathione (SLG) had been postulated as the key factor for its dual activity. In this study, dynamic ensembles of BLEG-1 and its substrate complexes divulged conformational plasticity and binding modes of structurally distinct substrates to the enzyme, providing better insights into its structure-to-function relationship and enzymatic promiscuity. Our results highlight the flexible nature of the active site pocket of BLEG-1, which is governed by concerted loop motions involving loop7+α3+loop8 and loop12 around the catalytic core, thereby moulding the binding pocket and facilitate interactions of BLEG-1 with both ampicillin and SLG. The distribution of (i) predominantly hydrophobic amino acids in the N-terminal domain, and (ii) flexible amino acids with polar and/or charged side chains in both N- and C-termini provide additional advantages to BLEG-1 in confining the aromatic group of ampicillin, and polar groups of SLG, respectively. The importance of these residues for substrates binding was further confirmed by the reduction in MBL and GLXII activities upon alanine substitutions of Ile-10, Phe-57, Arg-94, Leu-95, and Arg-159. Based on molecular dynamics simulation, mutational, and biochemical data presented herein, the catalytic mechanisms of BLEG-1 toward the hydrolysis of β-lactams and SLG were proposed.

Lactate: A Theranostic Biomarker for Metabolic Psychiatry?

Alterations in neurometabolism and mitochondria are implicated in the pathophysiology of psychiatric conditions such as mood disorders and schizophrenia. Thus, developing objective biomarkers related to brain mitochondrial function is crucial for the development of interventions, such as central nervous system penetrating agents that target brain health. Lactate, a major circulatory fuel source that can be produced and utilized by the brain and body, is presented as a theranostic biomarker for neurometabolic dysfunction in psychiatric conditions. This concept is based on three key properties of lactate that make it an intriguing metabolic intermediate with implications for this field: Firstly, the lactate response to various stimuli, including physiological or psychological stress, represents a quantifiable and dynamic marker that reflects metabolic and mitochondrial health. Second, lactate concentration in the brain is tightly regulated according to the sleep-wake cycle, the dysregulation of which is implicated in both metabolic and mood disorders. Third, lactate universally integrates arousal behaviours, pH, cellular metabolism, redox states, oxidative stress, and inflammation, and can signal and encode this information via intra- and extracellular pathways in the brain. In this review, we expand on the above properties of lactate and discuss the methodological developments and rationale for the use of functional magnetic resonance spectroscopy for in vivo monitoring of brain lactate. We conclude that accurate and dynamic assessment of brain lactate responses might contribute to the development of novel and personalized therapies that improve mitochondrial health in psychiatric disorders and other conditions associated with neurometabolic dysfunction.

Differences in the metabolomic profile of the human palatine tonsil between pediatrics and adults

Palatine tonsils (PT) are B cell-predominant lymphoid organs that provide primary immune responses to airborne and dietary pathogens. Numerous histopathological and immunological studies have been conducted on PT, yet no investigations have been conducted on its metabolic profile. We performed high-resolution magic angle spinning nuclear magnetic resonance spectroscopy-based metabolic profiling in 35 pediatric and 28 adult human palatine tonsillar tissue samples. A total of 36 metabolites were identified, and the levels of 10 metabolites were significantly different depending on age. Among them, partial correlation analysis shows that glucose levels increased with age, whereas glycine, phosphocholine, phosphoethanolamine, and ascorbate levels decreased with age. We confirmed the decrease in immunometabolic activity in adults through metabolomic analysis, which had been anticipated from previous histological and immunological studies on the PT. These results improve our understanding of metabolic changes in the PT with aging and serve as a basis for future tonsil-related metabolomic studies.

Looking to the Future of the Role of Macrophages and Extracellular Vesicles in Neuroinflammation in ALS

Neuroinflammation is a common pathological feature of amyotrophic lateral sclerosis (ALS). Although scientific evidence to date does not allow defining neuroinflammation as an ALS trigger, its role in exacerbating motor neuron (MNs) degeneration and disease progression is attracting research interest. Activated CNS (Central Nervous System) glial cells, proinflammatory peripheral and infiltrated T lymphocytes and monocytes/macrophages, as well as the immunoreactive molecules they release, represent the active players for the role of immune dysregulation enhancing neuroinflammation. The crosstalk between the peripheral and CNS immune cells significantly correlates with the survival of ALS patients since the modification of peripheral macrophages can downregulate inflammation at the periphery along the nerves and in the CNS. As putative vehicles for misfolded protein and inflammatory mediators between cells, extracellular vesicles (EVs) have also drawn particular attention in the field of ALS. Both CNS and peripheral immune cells release EVs, which are able to modulate the behavior of neighboring recipient cells; unfortunately, the mechanisms involved in EVs-mediated communication in neuroinflammation remain unclear. This review aims to synthesize the current literature regarding EV-mediated cell-to-cell communication in the brain under ALS, with a particular point of view on the role of peripheral macrophages in responding to inflammation to understand the biological process and exploit it for ALS management.

Metabolic alterations upon SARS-CoV-2 infection and potential therapeutic targets against coronavirus infection

The coronavirus disease 2019 (COVID-19) caused by coronavirus SARS-CoV-2 infection has become a global pandemic due to the high viral transmissibility and pathogenesis, bringing enormous burden to our society. Most patients infected by SARS-CoV-2 are asymptomatic or have mild symptoms. Although only a small proportion of patients progressed to severe COVID-19 with symptoms including acute respiratory distress syndrome (ARDS), disseminated coagulopathy, and cardiovascular disorders, severe COVID-19 is accompanied by high mortality rates with near 7 million deaths. Nowadays, effective therapeutic patterns for severe COVID-19 are still lacking. It has been extensively reported that host metabolism plays essential roles in various physiological processes during virus infection. Many viruses manipulate host metabolism to avoid immunity, facilitate their own replication, or to initiate pathological response. Targeting the interaction between SARS-CoV-2 and host metabolism holds promise for developing therapeutic strategies. In this review, we summarize and discuss recent studies dedicated to uncovering the role of host metabolism during the life cycle of SARS-CoV-2 in aspects of entry, replication, assembly, and pathogenesis with an emphasis on glucose metabolism and lipid metabolism. Microbiota and long COVID-19 are also discussed. Ultimately, we recapitulate metabolism-modulating drugs repurposed for COVID-19 including statins, ASM inhibitors, NSAIDs, Montelukast, omega-3 fatty acids, 2-DG, and metformin.

Evaluation of plasma prealbumin as a novel inflammatory biomarker in dogs: a pilot study

Introduction

Prealbumin (PAB) is a plasma protein synthesized in the hepatic parenchymal cells. PAB has a short half-life (~2 days), and its concentration is affected by changes in transcapillary escape. Measurement of PAB is widely used in hospitalized patients in human medicine due to its decreasing concentration in states of inflammation and malnutrition. However, only a few studies are available in dogs. The aim of this study is to determine whether the plasma PAB concentration decreases in dogs with inflammation and to evaluate the relationship between the plasma PAB concentration and inflammation-related parameters in dogs.

Methods

A total of 94 dogs were divided into healthy (n = 33) and diseased (n = 61) groups. These were further divided into group A (n = 24) and group B (n = 37) according to plasma C-reactive protein (CRP) levels. Group A included dogs with a plasma CRP < 10 mg/L, and group B consisted of dogs with a plasma CRP ≥ 10 mg/L. Patient signalment, history, physical examination findings, hematologic and biochemical parameters, various inflammatory markers, and plasma PAB levels were investigated and compared between groups.

Results

The plasma PAB concentration was found to be lower in group B than in the other groups (p < 0.001), but no statistical difference was found when comparing the control group and group A (p > 0.05). A plasma PAB < 6.3 mg/dL predicted an increased CRP level (10 mg/L or greater) with a sensitivity of 89.5% and a specificity of 86.5%. Receiver operating characteristic curve analysis revealed that the area under the curve for PAB was higher than that for the white blood cell count, neutrophil count, albumin level, lactate level, neutrophil-to-lymphocyte ratio, and neutrophil percentage-to-albumin ratio. In addition, the PAB concentration was significantly negatively correlated with the CRP concentration (r = -0.670, p < 0.001).

Conclusion

In conclusion, this is the first study to demonstrate the clinical usefulness of the plasma PAB concentration as an inflammatory marker in dogs. These findings suggest that measuring the plasma PAB concentration along with the CRP concentration may be more useful for evaluating inflammation than measuring CRP alone in canine patients.

d-lactate-induced ETosis in cattle polymorphonuclear leucocytes is dependent on the release of mitochondrial reactive oxygen species and the PI3K/Akt/HIF-1 and GSK-3β pathways

d-lactate is a metabolite originating from bacterial metabolism that accumulates as a result of dietary disturbances in cattle, leading to ruminal acidosis. d-lactate exerts functions as a metabolic signal inducing metabolic reprogramming and extracellular trap (ET) release in polymorphonuclear leucocytes (PMNs). We previously demonstrated that d-lactate induces metabolic reprogramming via hypoxia-induced factor 1 alpha (HIF-1α) stabilization in bovine fibroblast-like synoviocytes (FLSs). In the present study, the role of HIF-1 in ET formation induced by d-lactate was assessed. HIF-1α stabilization in PMNs was controlled by mitochondrial reactive oxygen species (_mtROS) release. Furthermore, inhibition of mitochondrial complex I and scavenging of _mtROS decreased d-lactate-triggered ETosis. d-lactate-enhanced HIF-1α accumulation was dependent on the PI3K/Akt pathway but independent of GSK-3β activity. Pharmacological blockade of the PI3K/Akt/HIF-1 and GSK-3β axes inhibited d-lactate-triggered ETosis and downregulated PDK1 and LDHA expression. However, only GSK-3β inhibition decreased the expression of glycogen metabolism enzymes and prevented the decline in glycogen stores induced by d-lactate exposure. The results of this study suggest that _mtROS, PI3K/Akt/HIF-1 and GSK-3β axes regulate carbohydrate metabolism adaptations that support d-lactate-induced ET formation in cattle.

Discovery of Lactomodulin, a Unique Microbiome-Derived Peptide That Exhibits Dual Anti-Inflammatory and Antimicrobial Activity against Multidrug-Resistant Pathogens

The human body is a superorganism that harbors trillions of microbes, most of which inhabit the gut. To colonize our bodies, these microbes have evolved strategies to regulate the immune system and maintain intestinal immune homeostasis by secreting chemical mediators. There is much interest in deciphering these chemicals and furthering their development as novel therapeutics. In this work, we present a combined experimental and computational approach to identifying functional immunomodulatory molecules from the gut microbiome. Based on this approach, we report the discovery of lactomodulin, a unique peptide from Lactobacillus rhamnosus that exhibits dual anti-inflammatory and antibiotic activities and minimal cytotoxicity in human cell lines. Lactomodulin reduces several secreted proinflammatory cytokines, including IL-8, IL-6, IL-1β, and TNF-α. As an antibiotic, lactomodulin is effective against a range of human pathogens, and is most potent against antibiotic-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). The multifunctional activity of lactomodulin affirms that the microbiome encodes evolved functional molecules with promising therapeutic potential.

Extracellular Lactic Acidosis of the Tumor Microenvironment Drives Adipocyte-to-Myofibroblast Transition Fueling the Generation of Cancer-Associated Fibroblasts

Lactic acidosis characterizes the tumor microenvironment (TME) and is involved in the mechanisms leading to cancer progression and dissemination through the reprogramming of tumor and local host cells (e.g., endothelial cells, fibroblasts, and immune cells). Adipose tissue also represents a crucial component of the TME which is receiving increasing attention due to its pro-tumoral activity, however, to date, it is not known whether it could be affected by the acidic TME. Now, emerging evidence from chronic inflammatory and fibrotic diseases underlines that adipocytes may give rise to pathogenic myofibroblast-like cells through the adipocyte-to-myofibroblast transition (AMT). Thus, our study aimed to investigate whether extracellular acidosis could affect the AMT process, sustaining the acquisition by adipocytes of a cancer-associated fibroblast (CAF)-like phenotype with a pro-tumoral activity. To this purpose, human subcutaneous adipose-derived stem cells committed to adipocytes (acADSCs) were cultured under basal (pH 7.4) or lactic acidic (pH 6.7, 10 mM lactate) conditions, and AMT was evaluated with quantitative PCR, immunoblotting, and immunofluorescence analyses. We observed that lactic acidosis significantly impaired the expression of adipocytic markers while inducing myofibroblastic, pro-fibrotic, and pro-inflammatory phenotypes in acADSCs, which are characteristic of AMT reprogramming. Interestingly, the conditioned medium of lactic acidosis-exposed acADSC cultures was able to induce myofibroblastic activation in normal fibroblasts and sustain the proliferation, migration, invasion, and therapy resistance of breast cancer cells in vitro. This study reveals a previously unrecognized relationship between lactic acidosis and the generation of a new CAF-like cell subpopulation from adipocytic precursor cells sustaining tumor malignancy.

Exogenous Penicillium camemberti Lipase Preparation Exerts Prebiotic-like Effects by Increasing Cecal Bifidobacterium and Lactobacillus Abundance in Rats

Penicillium camemberti is used in cheese production; however, its health benefits remain to be elucidated. We previously found that supplemental Aspergillus-derived lipase preparation exerts a strong bifidogenic effect in rats fed a high-fat diet. This study investigated the effects of the feeding of a diet containing a 0.2% or 0.4% Penicillium camemberti-derived lipase preparation (PCL) for two weeks on the cecal microbiota in rats. According to 16S rRNA gene sequencing analysis, both PCL supplements significantly (p < 0.05) affected the cecal microbial community. At the genus level, supplemental 0.4% PCL significantly increased the relative abundance of beneficial bacteria such as Bifidobacterium, Lactobacillus, and Collinsella (127-fold, 6-fold, and 193-fold increase, respectively). The abundance of these bacteria in the 0.2% PCL group was between that of the control and 0.4% PCL groups. Notably, the effects of supplemental 0.4% PCL on modulating the abundance of these bacteria matched the effects observed in studies on typical prebiotic oligosaccharides. PICRUSt analysis revealed that PCL supplements significantly modulated the relative abundance of bacterial genes associated with 27 metabolic pathways, some of which were similar to those reported for prebiotic oligosaccharides. This study provides the first evidence indicating that supplemental PCL exerts prebiotic-like effects by modulating the abundance of the gut microbiota.

Bovine tumor necrosis factor-alpha Increases IL-6, IL-8, and PGE2 in bovine fibroblast-like synoviocytes by metabolic reprogramming

Lameness is a common condition in dairy cattle caused by infectious or noninfectious agents. Joint lesions are the second most common cause of lameness and can be diagnosed in association with the presentation of digit injuries. Fibroblast-like synoviocyte (FLS) are predominant cells of synovia and play a key role in the pathophysiology of joint diseases, thus increasing the expression of proinflammatory mediators. Tumor necrosis factor-alpha (TNF-α) is a potent proinflammatory cytokine involved in cyclooxygenase 2 (COX-2) and proinflammatory cytokine expression in FLS. Previously, TNF-α was demonstrated to increase hypoxia-inducible Factor 1 (HIF-1), a transcription factor that rewires cellular metabolism and increases the expression of interleukin (IL)-6 in bovine FLS (bFLS). Despite this, the proinflammatory effects of TNF-α in bFLS on metabolic reprogramming have been poorly studied. We hypothesized that TNF-α increases glycolysis and in this way controls the expression of IL-6, IL-8, and COX-2 in bFLS. Results first, gas chromatography/mass spectrometry (GC/MS)-based untargeted metabolomics revealed that bTNF-α altered the metabolism of bFLS, increasing glucose, isoleucine, leucine, methionine, valine, tyrosine, and lysine and decreasing malate, fumarate, α-ketoglutarate, stearate, palmitate, laurate, aspartate, and alanine. In addition, metabolic flux analysis using D-glucose-¹³C₆ demonstrated an increase of pyruvate and a reduction in malate and citrate levels, suggesting a decreased flux toward the tricarboxylic acid cycle after bTNF-α stimulation. However, bTNF-α increased lactate dehydrogenase subunit A (LDHA), IL-6, IL-8, IL-1β and COX-2 expression, which was dependent on glycolysis and the PI3K/Akt pathway. The use of FX11 and dichloroacetate (DCA), an inhibitor of LDHA and pyruvate dehydrogenase kinase (PDK) respectively, partially reduced the expression of IL-6. Our results suggest that bTNF-α induces metabolic reprogramming that favors glycolysis in bFLS and increases IL-6, IL-8, IL-1β and COX-2/PGE2.

Alterations in Lymphocytic Metabolism-An Emerging Hallmark of MS Pathophysiology?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterised by acute inflammation and subsequent neuro-axonal degeneration resulting in progressive neurological impairment. Aberrant immune system activation in the periphery and subsequent lymphocyte migration to the CNS contribute to the pathophysiology. Recent research has identified metabolic dysfunction as an additional feature of MS. It is already well known that energy deficiency in neurons caused by impaired mitochondrial oxidative phosphorylation results in ionic imbalances that trigger degenerative pathways contributing to white and grey matter atrophy. However, metabolic dysfunction in MS appears to be more widespread than the CNS. This review focuses on recent research assessing the metabolism and mitochondrial function in peripheral immune cells of MS patients and lymphocytes isolated from murine models of MS. Emerging evidence suggests that pharmacological modulation of lymphocytic metabolism may regulate their subtype differentiation and rebalance pro- and anti-inflammatory functions. As such, further understanding of MS immunometabolism may aid the identification of novel treatments to specifically target proinflammatory immune responses.

1H NMR Profiling of the Venom from Hylesia continua: Implications of Small Molecules for Lepidopterism

Lepidopterism caused by caterpillar contact is considered a public health problem around the world. The local and systemic responses of this pathology include short- and long-term inflammatory events. Although the proteolytic activity of the venoms from caterpillars is strongly associated with an inflammatory response in humans and murine models, fast and acute symptoms such as a burning sensation, itching, and pain should be related to the presence of low-weight hydrophilic molecules which easily influence cell metabolism. This investigation reports on the ¹H-Nuclear Magnetic Resonance (NMR) profiling of the venom from the larva of Hylesia continua, a caterpillar linked to frequent cases of lepidopterism in the northern highlands of Puebla, Mexico. According to one-dimensional (1D) and two-dimensional (2D) NMR data, the venom of H. continua contained 19 compounds with proven pain-inducing activity (i.e., acetic acid, lactic acid, formic acid, succinic acid, 2-hydroxyglutaric acid, ethanol, and glutamate), inflammatory activity (i.e., cadaverine, putrescine, and acetoin), as well as natural immunosuppressive activity (i.e., O-phosphocholine and urocanic acid). The levels of the 19 compounds were calculated using quantitative-NMR (qNMR) and extensively discussed on the basis of their toxic properties which partially explain typical symptoms of lepidopterism caused by the larvae of H. continua. To the best of our knowledge, this is the first investigation reporting a complex mixture of small molecules with inflammatory properties dissolved in the venom of a lepidopteran larva.

The hypoxic tissue microenvironment as a driver of mucosal inflammatory resolution

On the backdrop of all acute inflammatory processes lies the activation of the resolution response. Recent years have witnessed an emerging interest in defining molecular factors that influence the resolution of inflammation. A keystone feature of the mucosal inflammatory microenvironment is hypoxia. The gastrointestinal tract, particularly the colon, exists in a state of physiological hypoxia and during active inflammation, this hypoxic state is enhanced as a result of infiltrating leukocyte oxygen consumption and the activation of oxygen consuming enzymes. Most evidence suggests that mucosal hypoxia promotes the active resolution of inflammation through a variety of mechanisms, including extracellular acidification, purine biosynthesis/salvage, the generation of specialized pro-resolving lipid mediators (ie. resolvins) and altered chemokine/cytokine expression. It is now appreciated that infiltrating innate immune cells (neutrophils, eosinophils, macrophages) have an important role in molding the tissue microenvironment to program an active resolution response. Structural or functional dysregulation of this inflammatory microenvironment can result in the loss of tissue homeostasis and ultimately progression toward chronicity. In this review, we will discuss how inflammatory hypoxia drives mucosal inflammatory resolution and its impact on other microenvironmental factors that influence resolution.

Dachengqi Decoction alleviates intestinal inflammation in ovalbumin-induced asthma by reducing group 2 innate lymphoid cells in a microbiota-dependent manner

Background and aim

Dachengqi Decoction (DCQD) as a classic traditional Chinese medicine has been reported to be effective in treating asthma, but its mechanism remains unknown. This study aimed to reveal the mechanisms of DCQD on the intestinal complications of asthma mediated by group 2 innate lymphoid cells (ILC2) and intestinal microbiota.

Experimental procedure

Ovalbumin (OVA) was used to construct asthmatic murine models. IgE, cytokines (e.g., IL-4, IL-5), fecal water content, colonic length, histopathologic appearance, and gut microbiota were evaluated in asthmatic mice treated with DCQD. Finally, we administered DCQD to antibiotic-treated asthmatic mice to measure the ILC2 in the small intestine and colon.

Results and conclusion

DCQD decreased pulmonary IgE, IL-4, and IL-5 levels in asthmatic mice. The fecal water content, the colonic length weight loss, and the epithelial damage of jejunum, ileum, and colon of asthmatic mice were ameliorated by DCQD. Meanwhile, DCQD greatly improved intestinal dysbiosis by enriching Allobaculum, Romboutsia and Turicibacter in the whole intestine, and Lactobacillus gasseri only in the colon. However, DCQD caused less abundant Faecalibaculum and Lactobacillus vaginalis in the small intestine of asthmatic mice. A higher ILC2 proportion in different gut segments of asthmatic mice was reversed by DCQD. Finally, significant correlations appeared between DCQD-mediated specific bacteria and cytokines (e.g., IL-4, IL-5) or ILC2. These findings indicate that DCQD alleviated the concurrent intestinal inflammation in OVA-induced asthma by decreasing the excessive accumulation of intestinal ILC2 in a microbiota-dependent manner across different gut locations.