Metabolic Preconditioning Research Articles

Abstract 3248: Metabolic rewiring shifts engineered TCR T cell bioenergetics to enhance cytotoxicity

Abstract Background: Adoptive T cell-based transfer has shown tremendous success in hematological cancers. However, an important obstacle to using cell and gene therapy for solid tumors is the aggressive tumor microenvironment (TME). To significantly improve prognosis of subjects undergoing immunotherapy, it is essential to incorporate unique methods to drive T cell energy production and metabolism towards empowering T cells to dismantle the suppressive TME. This can promote anti-tumor effects and persistence of the transfused engineered T cells. In the present study we present a simple metabolic preconditioning process that improves T cell performance and bioenergetics. Methods: Using the Agilent xCELLigence RTCA eSight, and Seahorse XF Analyzer we assessed the killing efficiency, and bioenergetics of engineered T-cells after pretreating with Arginine. Briefly, engineered TCR T-cells against MART-1 were generated by transducing CD3+ T-cells (Hemacare, Seattle, WA) with retrovirus SAMEN-DMF5 with a CD34 marker gene, against MART-1. The TCR T cells were pre-conditioned in 6mM Arginine for 7 days, followed by a killing assay using MART-1 expressing melanoma cell line as target cells (624.38) at the E:T ratio of 5:1. Target melanoma cells, 624.38 cells, were engineered to express a red-fluorescent nuclear protein. The comparison was made with transduced T-cells grown in RPMI (no added amino acid supplementation, and non-transduced T cells. The cytotoxicity assay was assessed using real-time impedance and live cell imaging data collected on xCELLigence RTCA eSight. Concurrently, the metabolic profiling of the engineered T-cells was examined by the XF96 Analyzer. Results: Supplementing the growth medium with 6 mM Arginine significantly increased the potency of MART-1 engineered T cells (up to 6-fold) and bioenergetic studies revealed increased spare respiratory capacity, basal respiration, and ATP production via mitochondrial respiration. Conclusions: Arginine pre-conditioning improved TCR T cell potency through metabolic rewiring favoring mitochondrial respiration. For Research Use Only. Not for use in diagnostic procedures RA45236.3483333333 Citation Format: Rashmi Pillai, Xiaoyu Zhang, Yama Abassi. Metabolic rewiring shifts engineered TCR T cell bioenergetics to enhance cytotoxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3248.

Comparing Metabolic Preconditioning and Diabetes As Risk Factors in Knee Arthroplasty Complications.

Advanced osteoarthritis of the knee joint severely affects the patient's mobility, compounded by pre-existing comorbidities such as metabolic preconditioning (such as obesity, dyslipidemia, hyperuricemia, and insulin resistance syndrome) and both type I and type II diabetes. The success of total knee arthroplasty is influenced by knowledge and management of risk factors. The present study aims to evaluate differences in the evolution of risk factors such as obesity, injuries, and sedentary lifestyle, distinguishing those with metabolic preconditions and diabetes. The objectives of our study include (1) investigating the prevalence of obesity among patients, highlighting their proportion in the five categories of body weight; (2) analyzing statistically significant differences between research groups in terms of weight status and physical activity; (3) evaluating postoperative evolution based on the administration of nonsteroidal anti-inflammatory drugs (NSAIDs) and without NSAIDs (N-NSAIDs), with an emphasis on overweight patients and those with diabetes; and (4) examining changes in metabolic preconditioning and the incidence of postoperative injury depending on the administration of anti-inflammatory drugs. A cohort involving 730 patients diagnosed with gonarthrosis was divided into two groupsaccording to the administration of anti-inflammatory drugs in the first seven postoperative days:N-NSAIDs group (394 patients, 55.3%)and respectively NSAIDs group (319 patients, 44.7%). Theprospective, observational study was conducted in terms ofrisk factors and complications that occurred upon treatment administration in relation to each type of intervention andimplant used. The outcomes were assessed in terms of the influence on quality of life, the data beingcollected and interpreted for the entire cohort, and for each study year individually. The results indicate that almost 69% of them were overweight, while only 31% had a normal weight. Significant differences in weight status were observed between research groups, highlighting the association between obesity and metabolic preconditions or diabetes. Physical activity was absent in a significant proportion, having a notable impact on postoperative evolution, especially in the group without metabolic precondition. Administration of anti-inflammatory drugs influenced postoperative outcomes, with significant differences in overweight and diabetic patients. The findings suggest the need to manage body weight, promote physical activity, and personalize postoperative treatments, given the complex interactions between obesity, metabolic preconditions, and the administration of NSAIDs.

Exploring a New Pathophysiological Association in Acne Vulgaris and Metabolic Syndrome: The Role of Biogenic Amines and Glutathione Peroxidase.

Background and Objectives: Metabolic disorders cause many skin issues, including acne vulgaris. This research investigated the function of glutathione peroxidase (GTPx) and biogenic amines as a potential novel pathophysiological link between metabolic syndrome (MetS) and acne vulgaris. Materials and Methods: The patients were distributed into two groups: metabolic precondition (MPG, n = 78) and control (CG, n = 81). To determine the extent of acne and metabolic preconditioning, patients were subjected to extensive clinical/paraclinical investigations. Additionally, catecholamine levels in urine and GTPx levels in blood were measured. Results: Mild acne was more common in the CG (32.1 vs. 6.4, p < 0.001), and severe acne was more common in the MPG (61.54 vs. 25.9, p < 0.001), with the average age being substantially higher in the MPG (23.81 vs. 21.05, p = 0.002). Significant variations were observed in the paraclinical levels for catecholamines (p < 0.05). In the MPG, most severe acne patients were overweight (52.1%), insulin-resistant (48.8%), or obese (47.9%). Moderate acne was most often linked to obesity (56%), overweight (44%), and insulin resistance (20%). Patients with severe acne (48.83%) had a considerably greater incidence of insulin resistance syndrome (p = 0.039) than those with moderate or severe acne (20%). The presence of two or three metabolic disorders considerably raised the risk of severe acne. Significant differences between groups were observed only in the subgroup of patients with severe acne, with lower values in the MPG (p = 0.015). Significant differences between groups were observed regarding the subgroup of patients with severe acne, with lower DTPx values in the MPG. At the group level, only CG patients with severe acne had reduced GTPx levels. Significant differences in catecholamine values were seen between groups (p < 0.05), independent of acne severity, except for adrenaline in mild acne patients (p = 0.059). Conclusions: The complex connection between GTPx and catecholamines in MetS suggests a significant role of these factors in the pathogenesis of acne associated with this condition, opening new perspectives in the research and treatment of acne in the context of MetS.

Exploring the Metabolic and Endocrine Preconditioning Associated with Thyroid Disorders: Risk Assessment and Association with Acne Severity.

Metabolic preconditioning, characterized by conditions like obesity and insulin resistance syndrome, disrupts hormonal balance. Elevated androgen levels stimulate excessive sebum production and follicular cell proliferation, leading to acne lesions. Similarly, thyroid hormone imbalances affect sebaceous gland activity, epidermal lipid composition, and skin cell turnover, impacting acne occurrence and severity. This study aimed to assess the potential contribution of metabolic and endocrine preconditions to acne development. A total of 389 patients diagnosed with acne were included and divided into three groups: the metabolic precondition group (MPG, N = 163, 41.9%), the endocrine precondition group (EPG, N = 162, 41.65%), and the control group (CG, N = 89, 22.88%). Data related to the degree of acne severity and comorbidities of interest were collected from the patients' medical records. In the groups with concomitant diseases, moderate and severe acne were significantly more prevalent (56.44% and 41.10% in MPG, and 35.80% and 61.11% in EPG) compared to the control group (5.61% and 4.89%). The most prevalent preconditions observed were insulin resistance syndrome in MPG (63.8%) and autoimmune thyroiditis in EPG (95.06%). Significant age-related differences in acne severity were found across all study groups (p < 0.05). In MPG, the age variable was significantly higher in the presence of mild acne, while in EPG, the age variable was significantly lower for the mild acne group. A positive association was observed between the severity of acne and insulin resistance syndrome, obesity, autoimmune thyroiditis, and hypothyroidism (p < 0.05). Risk analysis indicated a significantly higher risk (RR > 1, 95% CI RR > 1, p < 0.001) of developing moderate and severe acne in the presence of these preconditions. The presence of both metabolic and endocrine preconditions significantly increased the likelihood of developing severe acne, leading to the hypothesis that both conditions may be contributing factors to the development of acne.

CD40 signal rewires fatty acid and glutamine metabolism for stimulating macrophage anti-tumorigenic functions

Exposure of lipopolysaccharide triggers macrophage pro-inflammatory polarization accompanied by metabolic reprogramming, characterized by elevated aerobic glycolysis and a broken tricarboxylic acid cycle. However, in contrast to lipopolysaccharide, CD40 signal is able to drive pro-inflammatory and anti-tumorigenic polarization by some yet undefined metabolic programming. Here we show that CD40 activation triggers fatty acid oxidation (FAO) and glutamine metabolism to promote ATP citrate lyase-dependent epigenetic reprogramming of pro-inflammatory genes and anti-tumorigenic phenotypes in macrophages. Mechanistically, glutamine usage reinforces FAO-induced pro-inflammatory and anti-tumorigenic activation by fine-tuning the NAD+/NADH ratio via glutamine-to-lactate conversion. Genetic ablation of important metabolic enzymes involved in CD40-mediated metabolic reprogramming abolishes agonistic anti-CD40-induced antitumor responses and reeducation of tumor-associated macrophages. Together these data show that metabolic reprogramming, which includes FAO and glutamine metabolism, controls the activation of pro-inflammatory and anti-tumorigenic polarization, and highlight a therapeutic potential of metabolic preconditioning of tumor-associated macrophages before agonistic anti-CD40 treatments.

Анаплеротичні принципи нутритивної терапії в клініці критичних станів

У статті надані сучасні анаплеротичні концепції нутритивної терапії для модуляції метаболічної відповіді в клініці критичних станів. Метаболічний стрес — універсальна гіперметаболічна гіперкатаболічна відповідь на захворювання, травму з активацією гіпоталамо-гіпофізарно-адреналової системи; виділенням гормонів стресу; катехоламінів; нейропептиду S; фактора, індукованого гіпоксією HIF-1α; експресією генів, що контролюють механізми адаптації до гіпоксії, у тому числі гліколіз і цикл трикарбонових кислот. У статті наведена розроблена нами модель визначення метаболічного стресу і мітохондріальної дисфункції. Анаплеротична терапія базується на концепції використання альтернативних субстратів як для циклу трикарбонових кислот, так і для транспорту електронів у дихальному ланцюзі з метою посилення продукції аденозинтрифосфату. Багато патологічних станів вимагають проведення анаплеротичної терапії або шляхом поповнення пулу анаплеротичних субстратів (піруват, аспартат, аспарагінат та інші джерела, поповнюючи оксалоацетат, глутамін та інші кислоти), або видаленням з тканин продуктів катаплеротичних реакцій — інтермедіатів циклу трикарбонових кислот. Катаплероз врівноважує анаплероз шляхом переміщення надлишку інтермедіаторів циклу трикарбонових кислот з мітохондріального матриксу в цитоплазму, в екстрамітохондріальний простір. Сучасні анаплеротичні концепції для модуляції метаболічної відповіді при критичних станах включають в себе такі позиції: I. Раннє використання розчинів глюкози та інтенсивна інсулінотерапія: мінімальна кількість вуглеводів близько 2 г/кг глюкози/добу; введення інсуліну, якщо два послідовних аналізи показали рівень глюкози &gt; 10 ммоль/л; уникати обов’язкового повноцінного калорійного харчування в перший тиждень, починати з 500 ккал/добу. II. Попередження гіперглікемічного метаболічного стресу — метаболічне прекондиціювання: вживання прозорих рідин припиняється за 2 години до індукції в анестезію, споживання щільної їжі — за 6 годин. Передопераційне призначення вуглеводів застосовується у всіх пацієнтів без цукрового діабету за 2 години до індукції; при наявності протипоказань — в/в інфузія глюкози за 2 години до операції. III. Використання енергосубстратів, що не потребують інсулінової стимуляції для їх входження до клітини: виявлено, що особи, які одержували &lt; 60 г фруктози на добу, мали кращі показники здоров’я, ніж ті, які споживали &gt; 100 г/добу. IV. Амінокислотні суміші: якщо парентеральне харчування показано, доцільно призначати збалансовані амінокислотні суміші, з розрахунку 1,3–1,5 г/кг/добу білка; 0,2–0,4 г/кг/добу L-глутаміну. При тяжких опіках режим введення білка в амінокислотних сумішах зростає до 1,5–2 г/кг/добу. V. Поповнення пулу анаплеротичних жирних кислот: жирові емульсії (LCT, MCT) повинні призначатися в кількості 0,7–1,5 г/кг/добу; ентерально призначається суміш соєвої і оливкової олій, риб’ячий жир, що містять омега-3, -6, -9 жирні кислоти; дієтична анаплеротична терапія з тригептаноїном підвищує виживаність пацієнтів у критичних станах. VI. Використання інтермедіатів циклу Кребса: превентивне або терапевтичне використання сукцинатвмісних препаратів може бути ефективним для активації ургентних адаптивних механізмів. Тіамін є найважливішим вітаміном для підтримки аеробного метаболізму й активності ключових ферментів циклу Кребса, а також чолночного механізму пентозофосфатного циклу.

Metabolic preconditioning in CD4+ T cells restores inducible immune tolerance in lupus-prone mice.

Autoimmune disease has presented an insurmountable barrier to restoration of durable immune tolerance. Previous studies indicate that chronic therapy with metabolic inhibitors can reduce autoimmune inflammation, but it remains unknown whether acute metabolic modulation enables permanent immune tolerance to be established. In an animal model of lupus, we determined that targeting glucose metabolism with 2-deoxyglucose (2DG) and mitochondrial metabolism with metformin enables endogenous immune tolerance mechanisms to respond to tolerance induction. A 2-week course of 2DG and metformin, when combined with tolerance-inducing therapy anti-CD45RB, prevented renal deposition of autoantibodies for 6 months after initial treatment and restored tolerance induction to allografts in lupus-prone mice. The restoration of durable immune tolerance was linked to changes in T cell surface glycosylation patterns, illustrating a role for glycoregulation in immune tolerance. These findings indicate that metabolic therapy may be applied as a powerful preconditioning to reinvigorate tolerance mechanisms in autoimmune and transplant settings that resist current immune therapies.

Bone metastasis unique plasma exosomal microRNA signature in non-small cell lung cancer.

e14534 Background: 20-40% of lung cancer patients develop bone metastasis (BM) with significantly decreased overall survival. Currently, BM is mainly diagnosed by CT scan or MRI when symptom develop. Novel biomarkers with higher prediction value of BM are needed. Tumor secreted exosomes that are enriched with microRNAs have been recently implicated in site-specific tumor metastasis for establishing a distant pro-metastatic niche. Methods: Plasma exosomes from 39 stage IV non-small cell lung cancer (NSCLC) patients (n = 23 with BM; n = 16 without BM) and 16 healthy individuals were separated by ultracentrifugation. Total RNAs were extracted followed by small RNA-sequencing. miRNA identification was performed by miRDeep2. Weighted correlation network analysis (WGCNA) was used for identifying co-expression networks of highly correlated miRNA clusters. miRNA enrichment analysis and annotation (MIEAA) was applied for pathway analysis. Differential expression of individual miRNA was analyzed by edgeR. Results: Hierarchical clustering based on the total miRNA profile can clearly separate cancer patients and healthy individuals (HP), but not patients with (BM+) or without (BM-) BM. WGCNA identified three consensus clusters (A, B, C) of highly correlated miRNAs, among which cluster A (144 miRNAs) showed significantly differential expression in lung cancer patients, especially in BM+ group. Pathway analysis of cluster B miRNAs revealed enrichment in glycolysis and gluconeogenesis pathways that may involve in metabolic preconditioning of the metastatic niche. Three differentially expressed miRNAs between BM+ and BM- patients within cluster A were identified as miR-574-5p, a suppressor of Wnt/β-catenin pathway, was down-regulated, while miR-328-3p and miR-423-3p, two activators of the same pathway, were up-regulated in BM+ patients. Cluster B miRNAs (n = 49) also showed trend of upregulation in BM+ patients. Interestingly, pathway analysis indicated that 43 of them are associated with chr14, which has been suggested to promote EMT and bone metastasis. Conclusions: NSCLC patients with BM displayed unique plasma exosomal miRNA profiles, which might involve in promoting BM, and be potential biomarkers for predicting BM in NSCLC.

Concise Review: Heart-Derived Cell Therapy 2.0: Paracrine Strategies to Increase Therapeutic Repair of Injured Myocardium.

Despite progress in cardiovascular medicine, the incidence of heart failure is rising and represents a growing challenge. To address this, ex vivo proliferated heart-derived cell products have emerged as a promising investigational cell-treatment option. Despite being originally proposed as a straightforward myocyte replacement strategy, emerging evidence has shown that cell-mediated gains in cardiac function are leveraged on paracrine stimulation of endogenous repair and tissue salvage. In this concise review, we focus on the paracrine repertoire of heart-derived cells and outline strategies used to boost cell potency by targeting cytokines, metabolic preconditioning and supportive biomaterials. Mechanistic insights from these studies will shape future efforts to use defined factors and/or synthetic cell approaches to help the millions of patients worldwide suffering from heart failure. Stem Cells 2018;36:1794-10.

Performance Enhancing Effect of Metabolic Pre-conditioning on Upper-Body Strength-Endurance Exercise.

High systemic blood lactate (La) was shown to inhibit glycolysis and to increase oxidative metabolism in subsequent anaerobic exercise. Aim of this study was to examine the effect of a metabolic pre-conditioning (MPC) on net La increase and performance in subsequent pull-up exercise (PU). Nine trained students (age: 25.1 ± 1.9 years; BMI: 21.7 ± 1.4) performed PU on a horizontal bar with legs placed on a box (angular hanging) either without or with MPC in a randomized order. MPC was a 26.6 ± 2 s all out shuttle run. Each trial started with a 15-min warm-up phase. Time between MPC and PU was 8 min. Heart rate (HR) and gas exchange measures (VO2, VCO2, and VE) were monitored, La and glucose were measured at specific time points. Gas exchange measures were compared by area under the curve (AUC). In PU without MPC, La increased from 1.24 ± 0.4 to 6.4 ± 1.4 mmol⋅l−1, whereas with MPC, PU started at 9.28 ± 1.98 mmol⋅l−1 La which increased to 10.89 ± 2.13 mmol⋅l−1. With MPC, net La accumulation was significantly reduced by 75.5% but performance was significantly increased by 1 rep (4%). Likewise, net oxygen uptake VO2 (50% AUC), pulmonary ventilation (VE) (34% AUC), and carbon dioxide VCO2 production (26% AUC) were significantly increased during PU but respiratory exchange ratio (RER) was significantly blunted during work and recovery. MPC inhibited glycolysis and increased oxidative metabolism and performance in subsequent anaerobic upper-body strength-endurance exercise.

Metabolic preconditioning protects BSEP/ABCB11−/− mice against cholestatic liver injury

Cholestasis is characterized by intrahepatic accumulation of potentially cytotoxic bile acids (BAs) subsequently leading to liver injury with disruption of hepatocellular integrity, inflammation, fibrosis and ultimately liver cirrhosis. Bile salt export pump (BSEP/ABCB11) is the main canalicular BA transporter and therefore the rate limiting step for hepatobiliary BA excretion. In this study we aimed to investigate the role of BSEP/ABCB11 in the development of acquired cholestatic liver and bile duct injury. Wild-type (WT) and BSEP knockout (BSEP-/-) mice were subjected to common bile duct ligation (CBDL) or 3.5-diethoxycarbonyl-1.4-dihydrocollidine (DDC) feeding as models for cholestasis with biliary obstruction and bile duct injury. mRNA expression profile, serum biochemistry, liver histology, immunohistochemistry, hepatic hydroxyproline levels and BA composition as well as biliary pressure were assessed. BSEP-/- mice were protected against acquired cholestatic liver injury induced by 7days of CBDL or 4weeks of DDC feeding, as reflected by unchanged serum levels of liver transaminases, alkaline phosphatase and BAs. Notably, BSEP-/- mice were also protected from cholestasis-induced hepatic inflammation and biliary fibrosis. In line with induced BA detoxification/hydroxylation pathways in BSEP-/- mice, polyhydroxylated BAs were increased 4-fold after CBDL and 6-fold after DDC feeding in comparison with cholestatic WT mice. Finally, following CBDL, biliary pressure in WT mice increased up to 47mmH2O but remained below 11mmH2O in BSEP-/- mice. Metabolic preconditioning with subsequent changes in BA metabolism favors detoxification of potentially toxic BAs and thereby protects BSEP-/- mice from cholestatic liver and bile duct injury. Reduced hepatobiliary bile acid transport due to loss of BSEP function leads to increased hydroxylation of bile acids in the liver. Metabolic preconditioning with a hydrophilic bile pool protects the BSEP-/- mice from acquired cholestatic liver disease.

Molecular approaches for improving desiccation tolerance: insights from the brine shrimp Artemia franciscana.

We have evaluated the endogenous expression and molecular properties of selected Group 3 LEA proteins from Artemia franciscana , and the capacity of selected Groups 1 and 3 proteins transfected into various desiccation-sensitive cell lines to improve tolerance to drying. Organisms inhabiting both aquatic and terrestrial ecosystems frequently are confronted with the problem of water loss for multiple reasons--exposure to hypersalinity, evaporative water loss, and restriction of intracellular water due to freezing of extracellular fluids. Seasonal desiccation can become severe and lead to the production of tolerant propagules and entry into the state of anhydrobiosis at various stages of the life cycle. Such is the case for gastrula-stage embryos of the brine shrimp, Artemia franciscana. Physiological and biochemical responses to desiccation are central for survival and are multifaceted. This review will evaluate the impact of multiple late embryogenesis abundant proteins originating from A. franciscana, together with the non-reducing sugar trehalose, on prevention of desiccation damage at multiple levels of biological organization. Survivorship of desiccation-sensitive cells during water stress can be improved by use of the above protective agents, coupled to metabolic preconditioning and rapid cell drying. However, obtaining long-term stability of cells in the dried state at room temperature has not been accomplished and will require continued efforts on both the physicochemical and biological fronts.

In vivo inhibition of the mitochondrial H+-ATP synthase in neurons promotes metabolic preconditioning

A key transducer in energy conservation and signaling cell death is the mitochondrial H(+)-ATP synthase. The expression of the ATPase inhibitory factor 1 (IF1) is a strategy used by cancer cells to inhibit the activity of the H(+)-ATP synthase to generate a ROS signal that switches on cellular programs of survival. We have generated a mouse model expressing a mutant of human IF1 in brain neurons to assess the role of the H(+)-ATP synthase in cell death in vivo. The expression of hIF1 inhibits the activity of oxidative phosphorylation and mediates the shift of neurons to an enhanced aerobic glycolysis. Metabolic reprogramming induces brain preconditioning affording protection against quinolinic acid-induced excitotoxicity. Mechanistically, preconditioning involves the activation of the Akt/p70S6K and PARP repair pathways and Bcl-xL protection from cell death. Overall, our findings provide the first in vivo evidence highlighting the H(+)-ATP synthase as a target to prevent neuronal cell death.

Hypoxia-Inducible Factor-1α in Pulmonary Arterial Smooth Muscle Cells and Hypoxia-induced Pulmonary Hypertension

Hypoxia-Inducible Factor-1α in Pulmonary Arterial Smooth Muscle Cells and Hypoxia-induced Pulmonary Hypertension

Metabolic preconditioning with fructose prior to organ recovery attenuates ischemia-reperfusion injury in the isolated perfused rat liver

Objective. Ischemia-reperfusion injury is associated with a high rate of primary organ dysfunction and thereby contributes substantially to morbidity and mortality in the course of liver transplantation. In the present study, the impact of metabolic preconditioning with fructose on ischemia-reperfusion injury in the isolated perfused rat liver model is evaluated. Methods. Fasted rats received a single intravenous fructose injection to induce metabolic preconditioning (fructose group) or a volume equivalent of normal saline (control group) 10 min before liver explantation. After 26 h of cold storage, livers were reperfused for 90 min at 37°C with Krebs-Henseleit buffer. The parameters used to quantify ischemia-reperfusion injury included hepatic oxygen consumption, enzyme release, and cell viability. Results. During reperfusion, livers in the fructose group consumed more oxygen than livers in the control group (p < 0.005), indicating ATP synthesis as a result of glycolytic fructose degradation. Moreover, cell injury was reduced by fructose administration, as reflected by a lower enzyme release during both cold ischemia and reperfusion (p < 0.05). Finally, hepatocyte viability at the end of reperfusion was significantly higher in the fructose group (p < 0.01). However, there was no significant difference between the two experimental groups in reference to the viability of endothelial cells. Conclusion. In clinical use, metabolic preconditioning with fructose prior to organ recovery might contribute to a reduction in the incidence of primary organ dysfunction after liver transplantation.

40. Development of stallion sperm cryopreservation extenders by analysis of semen quality and new cryocapacitation markers

Sperm capacitation is a complex process which is highly demanding of ATP considering events such as calcium flow, hyperactive motility, phosphorylation, and membrane-fusion, which are essential for gametes interaction and occurs in the female reproductive tract. Sperm cryocapacitation represents an altered state of sperm functionality triggered by cooling, freezing and thawing stress, so-called due to similarities to the capacitation process, which happens precociously before the insemination impeding fertilization. The aim of this study is to evaluate whether AMPK activation can stop or decrease the energetic processes linked to sperm cryocapacitation, in order to increase the post-freezing quality in equine semen using a freezing and experimental extender for equine semen considering metabolic preconditioning as described by Menze et al.. (2010) in somatic cells. Twelve ejaculates from Heavy Draft breeds stallions (3 Ardennes, 5 Percheron, 4 Breton), were cryopreserved by standard procedures, using BotuCrio ® (commercial control) and experimental HM-0 extender as base medium to which Metformin, AICAR and AMP + compound C inhibitor were added. Post-centrifugation sperm pellets were resuspended in extenders previously tempered at 20 °C, packed in 0.5 ml (50 × 10 6 sperm/mL) straws and cooled to 5 °C in 90 min. The straws were further exposed to liquid nitrogen steam for 20 min, plunged in liquid nitrogen and stored for at least 2 weeks at −196 °C. Samples were thawed at 37 °C for 30 s and objective assessment of motility and viability were performed using the Sperm Class Analyzer ® System. Acrosomal integrity was evaluated using a conjugate of Pisum sativum agglutinin and fluorescein isothiocyanate (PSA-FITC) visualized by epifluorescence microscopy and, simultaneous analysis of viability and acrosome integrity through flow cytometry using propidium iodide and FITC-PSA. Phosphoproteins analysis were performed by Western blot and indirect immunofluorescence with the following antibodies: p-AMPK, p-CaMKIV, P-DARPP-32, total phosphotyrosines (pY20) and β -tubulin as loading control. In vitro evaluation of frozen-thawed stallion semen indicates that of three independently evaluated parameters (viability, acrosome integrity and motility), only motility was higher when BotuCrio ® was used as the extender. However, motility did not differ between treatments when assessments were performed after one hour of incubation or in the presence of metabolic substrates such as glucose and/or fructose. Cytometric analysis revealed a larger population of live sperms with intact acrosome using the experimental extender HM-0 (43.1 ± 3.3). However, no significant differences were found using HM-0 + AMPK activators such as Metformin (41.3 ± 3.6), AMP (41.1 ± 3.4) and AICAR (39.3 ± 3.9), or with Compound C (37.3 ± 3.6), Compound C + AICAR (32.7 ± 3.3) and BotuCrio ® (34.8 ± 2.7). In addition, western blot analysis revealed several isoforms of p-AMPK and p-CaMKIV, for which AMPK did not respond to classic activators, but seemed that compound C inhibited its phosphorylation. Moreover, we also confirmed the presence of p-DARPP32 and its sensitivity to activation by NaHCO 3 /cAMP, which makes it an early marker of the capacitation process. The results of in vitro sperm evaluation validate the freezing protocol and the use of HM-0, nonetheless, further studies improving our understanding of cellular mechanisms activated by cryopreservation stress, particularly related to sperm cryocapacitation will attempt to discover the importance/relevance of these and others phosphoproteins in cryopreservation process.

Metabolic preconditioning of mammalian cells: mimetic agents for hypoxia lack fidelity in promoting phosphorylation of pyruvate dehydrogenase

Induction of HIF-1α by oxygen limitation promotes increased phosphorylation and catalytic depression of mitochondrial pyruvate dehydrogenase (PDH) and an enhanced glycolytic poise in cells. Cobalt chloride and desferrioxamine are widely used as mimics for hypoxia because they increase the levels of HIF-1α. We evaluated the ability of these agents to elicit selected physiological responses to hypoxia as a means to metabolically precondition mammalian cells, but without the detrimental effects of hypoxia. We show that, while CoCl(2) does increase HIF-1α in a dose-dependent manner, it unexpectedly and strikingly decreases PDH phosphorylation at E1α sites 1, 2, and 3 (Ser(293), Ser(300), and Ser(232), respectively) in HepG2 cells. This same effect is also observed for site 1 in mouse NIH/3T3 fibroblasts and J774 macrophages. CoCl(2) unexpectedly decreases the mRNA expression for PDH kinase-2 in HepG2 cells, which likely explains the dephosphorylation of PDH observed. And nor does desferrioxamine promote the expected increase in PDH phosphorylation. Dimethyloxaloylglycine (a prolyl hydroxylase inhibitor) performs better in this regard, but failed to promote the stronger effects seen with hypoxia. Consequently, CoCl(2) and desferrioxamine are unreliable mimics of hypoxia for physiological events downstream of HIF-1α stabilization. Our study demonstrates that mimetic chemicals must be chosen with caution and evaluated thoroughly if bona fide cellular outcomes are to be promoted with fidelity.

The role of AMP-activated protein kinase in myocardial tolerance to ischemia and reperfusion injury in type 2 diabetes mellitus and its relation to metformin therapy

Background. Several previous studies suggest that the drug in the biguanide class — metformin, in addition to the well-known hypoglycemic action can exert a significant cardioprotective effect. Molecular mechanisms of cardioprotection mediated by metformin are practically unknown. Objective. To examine the role of AMP-activated protein kinase (AMPK) — a key regulator of energy metabolism in myocardial tolerance to ischemia and reperfusion injury under the action of metformin in animals with type 2 diabetes mellitus (T2DM). Design and methods. The Wistar rats with streptozotocin-induced neonatal type 2 diabetes mellitus were used in the study. Ischemia-reperfusion of the myocardium was modeled according to Langendorf on the isolated heart with the preliminary intraperitoneal administration of metformin for 3 days. Cardioprotective effect of metformin was assessed by hemodynamic parameters and the size of myocardial infarction. AMPK activity in the myocardium was assessed by Western blot analysis. Results. Metformin did not significantly affected infarct size and nature of the postischemic recovery of left ventricular function in control group and in animals with T2DM. At the same time, the infarct size in T2DM was significantly lower than in the controls, which confirms the phenomenon of metabolic preconditioning. Activation of AMPK in the myocardium compared with the control group was observed in animals with T2DM, and in both metformin groups. Administration of metformin to animals with T2DM was accompanied by the maximum increase in AMPK activity. Conclusions. T2DM led to the activation of AMPK and was accompanied by improved myocardial tolerance to ischemia. In the absence of significant cardioprotective effect pre-ischemic systemic administration of metformin led to the increase of AMPK activity in the myocardium that was the highest in the animals with T2DM and metformin administration.

The Effect of Metformin on the Myocardial Tolerance to Ischemia-Reperfusion Injury in the Rat Model of Diabetes Mellitus Type II

In recent years, evidence has been accumulated that metformin, an antidiabetic drug in the biguanide class, in addition to its well-recognized glucose-lowering effect, can also reduce cardiovascular mortality in the patients with type 2 diabetes mellitus (T2DM). Besides, there are a few experimental studies on the possibility of the direct anti-ischemic effect of the drug in both type 1 diabetes mellitus and T2DM. In our study, myocardial tolerance to ischemia in rats with neonatal streptozotocin T2DM was investigated using the model of global ischemia-reperfusion of the isolated perfused heart. Metformin was administered i.p. at a dose of 200 mg/kg/day for 3 days prior to isolated heart perfusion. The results showed that both the infarct size and postischemic recovery of left ventricular function were not different between controls and metformin-treated animals. At the same time, the infarct size in the T2DM animals was significantly lower than that in the controls (24.4 ± 7.6% versus 45.0 ± 10.4%, resp., P < .01), indicative of the metabolic preconditioning in T2DM. It follows that the protocol of metformin administration used in this study had not elicited cardioprotective effect in animals with T2DM so that the different mechanism(s) may underlie the beneficial effect of metformin on cardiovascular complications in patients with T2DM which, however, would need further investigation.

Metabolic preconditioning of cells with AICAR-riboside: Improved cryopreservation and cell-type specific impacts on energetics and proliferation

In species whose evolutionary history has provided natural tolerance to dehydration and freezing, metabolic depression is often a pre-requisite for survival. We tested the hypothesis that preconditioning of mammalian cells with 5-aminoimidazole-4-carboxamide-1-b- d-ribofuranoside (AICAR) to achieve metabolic depression will promote greater survivorship during cryopreservation. AICAR is used extensively to stimulate AMP-activated protein kinase (AMPK), which can result in downregulation of biosynthetic processes. We showed that the metabolic interconversion of AICAR was cell-type dependent. Accumulation of 5-aminoimidazole-4-carboxamide-1b- d-ribofuranosyl-5′-monophosphate (ZMP), as well as other metabolites that possess multiple phosphates (i.e., ZDP, ZTP), varied approximately 3.5-fold across the cell lines tested. AICAR treatment also significantly influenced the concentrations of cellular adenylates (ATP, ADP, and AMP). Depression of cell metabolism and proliferation with AICAR treatment differed among cell lines. Proliferation for a given cell line was negatively correlated with the fold-increase achieved in the ‘effective adenylate ratio’ ([AMP] + [ZMP])/[ATP]) after AICAR treatment. Metabolic preconditioning with AICAR promoted a significant increase in viability post-freezing in J774.A1 macrophages, HepG2/C3A cells and primary hepatocytes but not in NIH/3T3 fibroblasts or OMK cells. The effect of AICAR on viability after freezing was positively correlated ( r 2 = 0.94) with the fold-increase in the ‘effective adenylate ratio’. Thus for each cell line, the greater the depression of metabolism and proliferation due to preconditioning with AICAR, the greater was the survivorship post-freezing.