Role of mitochondrial DNA level in epidural-related maternal fever: a single-centre, observational, pilot study.

INTRODUCTION: Epidural analgesia has been associated with intrapartum maternal fever development. Epidural-related maternal fever (ERMF) is believed to be based on a non-infectious inflammatory reaction. Circulating cell-free mitochondrial deoxyribonucleic acid (mtDNA) is one of the possible triggers of sterile inflammatory processes; however, a connection has not been investigated so far. Therefore, this study aimed to investigate cell-free mtDNA alterations in women in labour with ERMF in comparison with non-febrile women. MATERIAL AND METHODS: A total of 60 women in labour were assessed for maternal temperature every 4 h and blood samples were obtained at the beginning and after delivery. Depending on the analgesia and the development of fever (axillary temperature ≥ 37.5 °C), the women were allocated either to the group of no epidural analgesia (n = 17), to epidural analgesia no fever (n = 34) or to ERMF (n = 9). Circulating cell-free mtDNA was analysed in the maternal plasma for the primary outcome whereas secondary outcomes include the evaluation of inflammatory cytokine release, as well as placental inflammatory signs. RESULTS: Of the women with epidural analgesia, 20% (n = 9) developed ERMF and demonstrated a decrease of circulating mtDNA levels during labour (p = 0.04), but a trend towards higher free nuclear DNA. Furthermore, women with maternal pyrexia showed a 1.5 fold increased level of Interleukin-6 during labour. A correlation was found between premature rupture of membranes and ERMF. CONCLUSIONS: The pilot trial revealed an evident obstetric anaesthesia phenomenon of maternal fever due to epidural analgesia in 20% of women in labour, demonstrating counterregulated free mtDNA and nDNA. Further work is urgently required to understand the connections between the ERMF occurrence and circulating cell-free mtDNA as a potential source of sterile inflammation. TRIAL REGISTRATION: NCT0405223 on clinicaltrials.gov (registered on 25/07/2019).

Effects of Hyperoxia and Hyperoxic Oscillations on the Proteome of Murine Lung Microvascular Endothelium.

Patients presenting with insufficient tissue oxygenation and impaired lung function as in acute respiratory distress syndrome (ARDS) frequently require mechanical ventilation with supplemental oxygen. Despite the lung being used to experiencing the highest partial pressure of oxygen during healthy breathing, the organ is susceptible to oxygen-induced injury at supraphysiological concentrations. Hyperoxia-induced lung injury (HALI) has been regarded as a second hit to pre-existing lung injury and ventilator-induced lung injury (VILI) attributed to oxidative stress. The injured lung has a tendency to form atelectasis, a cyclic collapse and reopening of alveoli. The affected lung areas experience oxygen conditions that oscillate between hyperoxia and hypoxia rather than remaining in a constant hyperoxic state. Mechanisms of HALI have been investigated in many animal models previously. These studies provided insights into the effects of hyperoxia on the whole organism. However, cell type-specific responses have not been dissected in detail, but are necessary for a complete mechanistic understanding of ongoing pathological processes. In our study, we investigated the effects of constant and intermittent hyperoxia on the lung endothelium from a mouse by an in vitro proteomic approach. We demonstrate that these oxygen conditions have characteristic effects on the pulmonary endothelial proteome that underlie the physiological (patho)mechanisms.

Oxygen conditions oscillating between hypoxia and hyperoxia induce different effects in the pulmonary endothelium compared to constant oxygen conditions.

The pulmonary endothelium is an immediate recipient of high oxygen concentrations upon oxygen therapy and mediates down-stream responses. Cyclic collapse and reopening of atelectatic lung areas during mechanical ventilation with high fractions of inspired oxygen result in the propagation of oxygen oscillations in the hypoxic/hyperoxic range. We used primary murine lung endothelial cell cultures to investigate cell responses to constant and oscillating oxygen conditions in the hypoxic to hyperoxic range. Severe constant hyperoxia had pro-inflammatory and cytotoxic effects including an increase in expression of ICAM1, E-selectin, and RAGE at 24 hr exposure. The coagulative/fibrinolytic system responded by upregulation of uPA, tPA, and vWF and PAI1 under constant severe hyperoxia. Among antioxidant enzymes, the upregulation of SOD2, TXN1, TXNRD3, GPX1, and Gstp1 at 24 hr, but downregulation of SOD3 at 72 hr constant hyperoxia was evident. Hypoxic/hyperoxic oscillating oxygen conditions induced pro-inflammatory cytokine release to a lesser extent and later than constant hyperoxia. Gene expression analyses showed upregulation of NFKB p65 mRNA at 72 hr. More evident was a biphasic response of NOS3 and ACE1 gene expression (downregulation until 24 hr and upregulation at 72 hr). ACE2 mRNA was upregulated until 72 hr, but shedding of the mature protein from the cell surface favored ACE1. Oscillations resulted in severe production of peroxynitrite, but apart from upregulation of Gstp1 at 24 hr responses of antioxidative proteins were less pronounced than under constant hyperoxia. Oscillating oxygen in the hypoxic/hyperoxic range has a characteristical impact on vasoactive mediators like NOS3 and on the activation of the renin-angiotensin system in the lung endothelium.

Ropivacaine Activates Multiple Proapoptotic and Inflammatory Signaling Pathways That Might Subsume to Trigger Epidural-Related Maternal Fever.

BACKGROUND: Epidural-related maternal fever (ERMF) is an adverse effect of epidural analgesia during labor and is associated with perinatal and neonatal morbidity. Local anesthetics have been proposed to trigger ERMF via sterile inflammation. Ropivacaine is currently the most frequently used epidural anesthetic and considered least toxic. This study investigates molecular effects of ropivacaine on human umbilical vein endothelial cells (HUVECs) as model system for endothelial cells and human placental trophoblasts (TBs), compares the effects to the putative anti-inflammatory lidocaine and investigates the partially alleviating impact of the anti-inflammatory corticosteroid dexamethasone. METHODS: HUVECs and TBs were exposed to ropivacaine (35 µM-7 mM) or lidocaine (21 mM) with or without dexamethasone (1 µM). AnnexinV/propidium iodide staining and lactate dehydrogenase release were used to analyze apoptosis and cytotoxicity. Proinflammatory interleukins-6 (IL-6) and IL-8 as well as prostaglandin E2 (PGE2) were measured by enzyme-linked immunosorbent assay (ELISA), while activation of signaling pathways was detected by Western blotting. Oxidative stress was visualized by live cell imaging and quantification of antioxidant proteins, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, platelet endothelial cell adhesion molecule 1, cyclooxygenase 2, and mitochondrial deoxyribonucleic acid by real-time polymerase chain reaction. Dissipation of the mitochondrial membrane potential was assessed with cytofluorimetric analysis using the J-Aggregate (JC-1 staining [cytofluorimetric analysis using the J-Aggregate]). RESULTS: Ropivacaine exposure dose-dependently induced apoptosis and an increased release of IL-6, IL-8, and PGE2 from HUVECs and TBs. Furthermore, caspase-3, nuclear factor-κB, and p38 mitogen-activated protein kinase pathways were activated, while extracellular signal-regulated kinase 1/2 and protein kinase B (Akt) were dephosphorylated. Downregulation of antioxidative proteins induced oxidative stress and upregulation of ICAM1, VCAM1, and PECAM1 possibly facilitate leukocyte transmigration. Mitochondrial effects included increased release of the proinflammatory mitochondrial DNA damage-associated molecular patterns, but no significant dissipation of the mitochondrial membrane potential. Conversely, lidocaine exhibited repression of IL-6 and IL-8 release over all time points, and early downregulation of COX2 and cell adhesion molecules, which was followed by a late overshooting reaction. Dexamethasone reduced especially inflammatory effects, but as an inducer of mitophagy, had negative long-term effects on mitochondrial function. CONCLUSIONS: This study suggests that ropivacaine causes cellular injury and death in HUVECs and TBs via different signaling pathways. The detrimental effects induced by ropivacaine are only partially blunted by dexamethasone. This observation strengthens the importance of inflammation in ERMF.

Intermittent Hypoxia Activates Duration-Dependent Protective and Injurious Mechanisms in Mouse Lung Endothelial Cells.

Intermittent hypoxia is a major factor in clinical conditions like the obstructive sleep apnea syndrome or the cyclic recruitment and derecruitment of atelectasis in acute respiratory distress syndrome and positive pressure mechanical ventilation. In vivo investigations of the direct impact of intermittent hypoxia are frequently hampered by multiple co-morbidities of patients. Therefore, cell culture experiments are important model systems to elucidate molecular mechanisms that are involved in the cellular response to alternating oxygen conditions and could represent future targets for tailored therapies. In this study, we focused on mouse lung endothelial cells as a first frontier to encounter altered oxygen due to disturbances in airway or lung function, that play an important role in the development of secondary diseases like vascular disease and pulmonary hypertension. We analyzed key markers for endothelial function including cell adhesion molecules, molecules involved in regulation of fibrinolysis, hemostasis, redox balance, and regulators of gene expression like miRNAs. Results show that short-time exposure to intermittent hypoxia has little impact on vitality and health of cells. At early timepoints and up to 24 h, many endothelial markers are unchanged in their expression and some indicators of injury are even downregulated. However, in the long-term, multiple signaling pathways are activated, that ultimately result in cellular inflammation, oxidative stress, and apoptosis.

Maternal serum mitochondrial DNA (mtDNA) levels are elevated in preeclampsia - A matched case-control study.

OBJECTIVE: Oxidative stress and mitochondrial dysfunction may play a crucial role in preeclampsia (PE). The aim of this study was to investigate differences in maternal levels of serum-mitochondrial (mt) DNA, a proposed biomarker for mitochondrial dysfunction, in women with PE compared to healthy pregnant women. STUDY DESIGN: Using samples obtained from the prospective Biobank study, we measured serum-mtDNA levels in pregnant women diagnosed with PE and in women with uneventful pregnancies, matched for gestational and maternal age, BMI, and smoking status. In a second step, we performed a generalized linear model to detect associations between mtDNA-serum-levels and certain conditions during pregnancy. RESULTS: Mean mtDNA levels were significantly higher in PE (n = 20) than in matched controls (n = 20) and were 0.00767 (SD 0.00255) U/L and 0.00513 (SD 0.00458) U/L, respectively (p = 0.038). We did not find a significant correlation between higher mtDNA levels and early onset PE, IUGR, maternal age, or maternal BMI. Interestingly, increased mtDNA levels were significantly associated with female fetal sex (p = 0.003). CONCLUSION: Our findings strengthen the hypothesis postulating that oxidative stress and mitochondrial dysfunction are key factors in the pathophysiology of PE. More prospective studies are highly warranted to further investigate the role of mtDNA in PE and assess the usefulness as a possible biomarker for PE.

Recent advances in understanding acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by acute diffuse lung injury, which results in increased pulmonary vascular permeability and loss of aerated lung tissue. This causes bilateral opacity consistent with pulmonary edema, hypoxemia, increased venous admixture, and decreased lung compliance such that patients with ARDS need supportive care in the intensive care unit to maintain oxygenation and prevent adverse outcomes. Recently, advances in understanding the underlying pathophysiology of ARDS led to new approaches in managing these patients. In this review, we want to focus on recent scientific evidence in the field of ARDS research and discuss promising new developments in the treatment of this disease.

Remote access perfusion for minimally invasive cardiac surgery: to clamp or to inflate?

OBJECTIVES: Endoaortic balloon occlusion (EBO) and aortic transthoracic clamping (TTC) are the dominant methods of remote access perfusion (RAP) in minimally invasive cardiac surgery. The aim of the study was to compare the two methods in terms of feasibility, success and complications. METHODS: From June 2001 to November 2011, 307 (median age; range) (57; 16-77 years) and 460 (62; 11-88 years) patients underwent minimally invasive CABG, ASD and mitral valve surgery using EBO and TTC, respectively. Perioperative procedure feasibility, success and postoperative complications were recorded. RESULTS: Overall 30-day mortality was 0 and 2 (0.43%) for the EBO and TTC groups, respectively (P = 0.52). Overall and RAP-associated conversions were noted in 21 (6.8%) and 4 (1.3%) patients in the EBO and in 9 (2%) and 6 (1.3%) patients in the TTC groups (P < 0.001, P = 1.00, respectively). Incidence of major complications, including aortic dissection, major vessel perforation, injury of intrapericardial structures, limb ischaemia, myocardial infarction and neurologic events, was similar [EBO: 12 (4%); TTC: 11 (2.4%); P = 0.23]. Minor complications such as minor vessel injury, groin bleeding or lymphatic fistula were noted in 31 (10.1%) and 35 (7.6%), respectively (P = 0.23). Successful RAP procedures defined as absence of RAP-associated conversions and major complications were equal [EBO: 295 (96%); TTC: 449 (97.6%); P = 0.23]. Complications detected during follow-up included pain: 30 of 249 (12%) and 13 of 279 (4.7%) (P = 0.002); sensational disturbances: 60 of 249 (24.1%) and 40 of 278 (14.4%) (P = 0.005) and wound-healing complications: 49 of 249 (19.7%) and 42 of 277 (15.2%) (P = 0.172) for EBO and TTC, respectively. CONCLUSIONS: RAP can be successfully and safely implemented in minimally invasive cardiac surgery. EBO and transthoracic clamping of the ascending aorta are performing equally in terms of feasibility and procedural success.