Mitochondrial dysfunction in peripheral blood mononuclear cells in early experimental and clinical acute pancreatitis

Temperature-dependence of metabolism and fuel selection from cells to whole organisms

Temperature affects nearly every aspect of how organisms interact with and are constrained by their environment. Measures of organismal energetics, such as metabolic rate, are highly temperature-dependent and governed through temperature effects on rates of biochemical reactions. Characterizing the relationships among levels of biological organization can lend insight into how temperature affects whole-organism function. We tested the temperature dependence of cellular oxygen consumption and its relationship to whole-animal metabolic rate in garter snakes (Thamnophis elegans). Additionally, we tested whether thermal responses were linked to shifts in the fuel source oxidized to support metabolism with the use of carbon stable isotopes. Our results demonstrate temperature dependence of metabolic rates across levels of biological organization. Cellular (basal, adenosine triphosphate-linked) and whole-animal rates of respiration increased with temperature but were not correlated within or among individuals, suggesting that variation in whole-animal metabolic rates is not due simply to variation at the cellular level, but rather other interacting factors across scales of biological organization. Counter to trends observed during fasting, elevated temperature did not alter fuel selection (i.e., natural-abundance stable carbon isotope composition in breath, δ¹³ C_breath ). This consistency suggests the maintenance and oxidation of a single fuel source supporting metabolism across a broad range of metabolic demands.

Prolonged treatment with a PI3K p110α inhibitor causes sex- and tissue-dependent changes in antioxidant content, but does not affect mitochondrial function

Genetic inhibition of the p110α isoform of phosphatidylinositol-3-kinase (PI3K) can increase murine lifespan, enhance mitochondrial function and alter tissue-specific oxidative balance. Here, we investigated whether pharmacological inhibition of the p110α isoform of PI3K induces similar enhancement of mitochondrial function in middle-aged mice. Eight-month-old male and female mice were fed a diet containing 0.3 g/kg of the p110α-selective inhibitor BYL-719 (BYL) or a vehicle diet (VEH) for 6 weeks. Mice consuming BYL-719 had higher blood glucose and insulin, and tended towards decreased body weight. After 72 h, gene expression of the mitochondrial biogenesis mediators Pgc1α, Tfam and Nrf1 was greater in liver of BYL-719 males only, but unchanged in skeletal muscle of either sex. Six weeks of BYL-719 treatment did not affect mitochondrial content or function in the liver or skeletal muscle of either sex. In livers of males only, the expression of the antioxidant genes Nfe2l2, Cat, Sod1 and Sod2 increased within 72 h of BYL-719 treatment, and remained higher after 6 weeks. This was associated with an increase in hepatic GSH content and catalase protein expression, and lower H₂O₂ levels. Our results suggest that pharmacological inhibition of p110α in adult mice does not affect liver or skeletal muscle mitochondrial function, but does show sex- and tissue-specific effects on up-regulation of antioxidant response.

Infectious Complications of Acute Pancreatitis Is Associated with Peripheral Blood Phagocyte Functional Exhaustion

BACKGROUND

Infected pancreatic necrosis is one of the most severe complications of acute pancreatitis (AP). The development of secondary infection doubles the risk of death during the late stage of necrotizing pancreatitis. Phagocytes play a major role in AP pathogenesis, as well as in local and systemic complications of the disease.

AIMS

We aimed to investigate the relationship between quantitative and functional indices of circulating phagocyte at the time of admission and onset of infectious complications in patients with AP afterward.

METHODS

A post hoc analysis of 97 patients with AP was conducted. The metabolic state of peripheral blood neutrophils and monocytes was analyzed based on their phagocytic activity and generation of reactive oxygen species (ROS), which were determined by flow cytometry on admission. The clinical end point was marked by onset of infectious complications of AP.

RESULTS

On admission, baseline values and reactivity reserve of monocyte and neutrophil phagocytic activity in AP patients, who developed septic complications, were substantially decreased, whereas monocyte ROS generation was dramatically increased as compared to the group without infectious processes. ROC curve was obtained both for neutrophil and monocyte phagocytosis reactivity reserve expressed as modulation coefficient values and categorized as the risk factor of infectious complications, showing an area under curve of 0.95 (P < 0.0001) and 0.84 (P < 0.0001), respectively.

CONCLUSIONS

Early (at the time of admission) detection of quantitative and functional indices of circulating phagocytes can be useful for the prediction of septic complications in SAP patients.

Altered Bioenergetics of Blood Cell Sub-Populations in Acute Pancreatitis Patients

Acute pancreatitis (AP) is a debilitating, sometimes fatal disease, marked by local injury and systemic inflammation. Mitochondrial dysfunction is a central feature of pancreatic damage in AP, however, its involvement in circulating blood cell subtypes is unknown. This study compared mitochondrial bioenergetics in circulating leukocytes from AP patients and healthy volunteers: 15 patients with mild to severe AP were compared to 10 healthy controls. Monocytes, lymphocytes and neutrophils were isolated using magnetic activated cell sorting and mitochondrial bioenergetics profiles of the cell populations determined using a Seahorse XF24 flux analyser. Rates of oxygen consumption (OCR) and extracellular acidification (ECAR) under conditions of electron transport chain (ETC) inhibition (“stress” test) informed respiratory and glycolytic parameters, respectively. Phorbol ester stimulation was used to trigger the oxidative burst. Basal OCR in all blood cell subtypes was similar in AP patients and controls. However, maximal respiration and spare respiratory capacity of AP patient lymphocytes were decreased, indicating impairment of functional capacity. A diminished oxidative burst occurred in neutrophils from AP patients, compared to controls, whereas this was enhanced in both monocytes and lymphocytes. The data demonstrate important early alterations of bioenergetics in blood cell sub-populations from AP patients, which imply functional alterations linked to clinical disease progression.

Icariin attenuates the severity of cerulein‑induced acute pancreatitis by inhibiting p38 activation in mice

Acute pancreatitis (AP) is an inflammatory disease of the pancreas. Icariin (ICA), a flavonoid glycoside, has been reported to have several pharmacological effects; however, the anti‑inflammatory effects of ICA against AP require further study. Therefore, we aimed to investigate the effect of ICA on cerulein‑induced AP. In the present study, AP was induced by intraperitoneally administering a supramaximal concentration of cerulein (50 µg/kg/h) for 6 h. ICA was also administered intraperitoneally, and mice were sacrificed 6 h after the final cerulein injection. Blood samples were collected to determine serum amylase and lipase levels. The pancreas and lung were rapidly removed for histological examination, and the analysis of myeloperoxidase activity. In addition, reverse transcription‑quantitative polymerase chain reaction was conducted to analyze the expression of inflammatory cytokines in pancreatic tissues. Our results revealed that the administration of ICA prevented an increase in the pancreas weight/body weight ratio of mice and serum digestive enzyme levels. ICA treatment also inhibited cerulein‑induced histological injury and neutrophil infiltration of the pancreas and lung. In addition, ICA suppressed the production of pro‑inflammatory cytokines, including interleukin (IL)‑1β, IL‑6 and tumor necrosis factor‑α in the pancreas. Furthermore, ICA administration was observed to inhibit p38 activation during cerulein‑induced AP. Inhibition of p38 activation resulted in alleviated pancreatitis. Collectively, our results suggested that ICA exhibits anti‑inflammatory effects in cerulein‑induced AP via the inhibition of p38.

Peripheral blood mononuclear cells do not reflect skeletal muscle mitochondrial function or adaptation to high-intensity interval training in healthy young men

Measurement of skeletal muscle mitochondrial respiration requires invasive biopsy to obtain a muscle sample. Peripheral blood mononuclear cell (PBMC) mitochondrial protein content appears to reflect training status in young men; however, no studies have investigated whether there are training-induced changes in PBMC mitochondrial respiration. Therefore, we determined whether PBMC mitochondrial respiration could be used as a marker of skeletal muscle mitochondrial respiration in young healthy men and whether PBMC mitochondrial respiration responds to short-term training. Skeletal muscle and PBMC samples from 10 healthy young (18–35 yr) male participants were taken before and after a 2-wk high-intensity interval training protocol. High-resolution respirometry was used to determine mitochondrial respiration from muscle and PBMCs, and Western blotting and quantitative PCR were used to assess mitochondrial biogenesis in PBMCs. PBMC mitochondrial respiration was not correlated with muscle mitochondrial respiration at baseline ( R2 = 0.012–0.364, P > 0.05). While muscle mitochondrial respiration increased in response to training (32.1–61.5%, P < 0.05), PBMC respiration was not affected by training. Consequently, PBMCs did not predict training effect on muscle mitochondrial respiration ( R2 = 0.024–0.283, P > 0.05). Similarly, gene and protein markers of mitochondrial biogenesis did not increase in PBMCs following training. This suggests PBMC mitochondrial function does not reflect that of skeletal muscle and does not increase following short-term high-intensity training. PBMCs are therefore not a suitable biomarker for muscle mitochondrial function in young healthy men. It may be useful to study PBMC mitochondrial function as a biomarker of muscle mitochondrial function in pathological populations with different respiration capacities.

NEW & NOTEWORTHY Research in primates has suggested that peripheral blood mononuclear cells (PBMCs) may provide a less-invasive alternative to a muscle biopsy for measuring muscle mitochondrial function. Furthermore, trained individuals appear to have greater mitochondrial content in PBMCs. Here we show that in healthy young men, PBMCs do not reflect skeletal muscle mitochondrial function and do not adapt in response to a training intervention that increases muscle mitochondrial function, suggesting PBMCs are a poor marker of muscle mitochondrial function in humans.

A Mini-Review on the Effect of Docosahexaenoic Acid (DHA) on Cerulein-Induced and Hypertriglyceridemic Acute Pancreatitis

Acute pancreatitis refers to the sudden inflammation of the pancreas. It is associated with premature activation and release of digestive enzymes into the pancreatic interstitium and systemic circulation, resulting in pancreatic tissue autodigestion and multiple organ dysfunction, as well as with increased cytokine production, ultimately leading to deleterious local and systemic effects. Although mechanisms involved in pathogenesis of acute pancreatitis have not been completely elucidated, oxidative stress is regarded as a major risk factor. In human acute pancreatitis, lipid peroxide levels in pancreatic tissues increase. Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid (C22:6n-3), exerts anti-inflammatory and antioxidant effects on various cells. Previous studies have shown that DHA activates peroxisome proliferator-activated receptor-γ and induces catalase, which inhibits oxidative stress-mediated inflammatory signaling required for cytokine expression in experimental acute pancreatitis using cerulein. Cerulein, a cholecystokinin analog, induces intra-acinar activation of trypsinogen in the pancreas, which results in human acute pancreatitis-like symptoms. Therefore, DHA supplementation may be beneficial for preventing or inhibiting acute pancreatitis development. Since DHA reduces serum triglyceride levels, addition of DHA to lipid-lowering drugs like statins has been investigated to reduce hypertriglyceridemic acute pancreatitis. However, high DHA concentrations increase cytosolic Ca²⁺, which activates protein kinase C and may induce hyperlipidemic acute pancreatitis. In this review, effect of DHA on cerulein-induced and hypertriglyceridemic acute pancreatitis has been discussed. The relation of high concentration of DHA to hyperlipidemic acute pancreatitis has been included.

Septic Shock and the Aging Process: A Molecular Comparison

Aging is a continuous process promoted by both intrinsic and extrinsic factors that each trigger a multitude of molecular events. Increasing evidence supports a central role for inflammation in this progression. Here, we discuss how the low-grade chronic inflammation that characterizes aging is tightly interconnected with other important aspects of this process, such as DNA damage, mitochondrial dysfunction, and epigenetic changes. Similarly, inflammation also plays a critical role in many morbid conditions that affect patients who are admitted to Intensive Care. Although the inflammatory response is low grade and persistent in healthy aging while it is acute and severe in critically ill states, we hypothesize that both situations have important interconnections. Here, we performed an extensive review of the literature to investigate this potential link. Because sepsis is the most extensively studied disease and is the leading cause of death in Critical Care, we focus our discussion on comparing the inflammatory profile of healthy older people with that of patients in septic shock to explain why we believe that both situations have synergistic effects, leading to critically ill aged patients having a worse prognosis when compared with critically ill young patients.

High versus low energy administration in the early phase of acute pancreatitis (GOULASH trial): protocol of a multicentre randomised double-blind clinical trial

INTRODUCTION

Acute pancreatitis (AP) is an inflammatory disease with no specific treatment. Mitochondrial injury followed by ATP depletion in both acinar and ductal cells is a recently discovered early event in its pathogenesis. Importantly, preclinical research has shown that intracellular ATP delivery restores the physiological function of the cells and protects from cell injury, suggesting that restoration of energy levels in the pancreas is therapeutically beneficial. Despite several high quality experimental observations in this area, no randomised trials have been conducted to date to address the requirements for energy intake in the early phase of AP.

METHODS/DESIGN

This is a randomised controlled two-arm double-blind multicentre trial. Patients with AP will be randomly assigned to groups A (30 kcal/kg/day energy administration starting within 24 hours of hospital admission) or B (low energy administration during the first 72 hours of hospital admission). Energy will be delivered by nasoenteric tube feeding with additional intravenous glucose supplementation or total parenteral nutrition if necessary. A combination of multiorgan failure for more than 48 hours and mortality is defined as the primary endpoint, whereas several secondary endpoints such as length of hospitalisation or pain will be determined to elucidate more detailed differences between the groups. The general feasibility, safety and quality checks required for high quality evidence will be adhered to.

ETHICS AND DISSEMINATION

The study has been approved by the relevant organisation, the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (55961-2/2016/EKU). This study will provide evidence as to whether early high energy nutritional support is beneficial in the clinical management of AP. The results of this trial will be published in an open access way and disseminated among medical doctors.

TRIAL REGISTRATION

The trial has been registered at the ISRCTN (ISRTCN 63827758).