Enhanced Expression of Catalase in Mitochondria Modulates NF-κB-Dependent Lung Inflammation through Alteration of Metabolic Activity in Macrophages.

NF-κB is a reduction-oxidation-sensitive transcription factor that plays a key role in regulating the immune response. In these studies, we intended to investigate the role of mitochondrial-derived reactive oxygen species in regulating NF-κB activation by studying transgenic mice that overexpress mitochondrial-targeted human catalase (mCAT). We treated wild-type (WT) and mCAT mice with intratracheal instillation of Escherichia coli LPS and found that mCAT mice had exaggerated NF-κB activation in the lungs, increased neutrophilic alveolitis, and greater lung inflammation/injury compared with WT mice. Additional studies using bone marrow chimeras revealed that this hyperinflammatory phenotype was mediated by immune/inflammatory cells. Mechanistic studies using bone marrow-derived macrophages (BMDMs) showed that LPS treatment induced a sustained increase in NF-κB activation and expression of NF-κB-dependent inflammatory mediators in mCAT BMDMs compared with WT BMDMs. Further investigations showed that cytoplasmic, but not mitochondrial, hydrogen peroxide levels were reduced in LPS-treated mCAT BMDMs. However, mCAT macrophages exhibited increased glycolytic and oxidative metabolism, coupled with increased ATP production and an increased intracellular NADH/NAD+ ratio compared with BMDMs from WT mice. Treatment of BMDMs with lactate increased the intracellular NADH/NAD+ ratio and upregulated NF-κB activation after LPS treatment, whereas treatment with a potent inhibitor of the mitochondrial pyruvate carrier (UK5099) decreased the NADH/NAD+ ratio and reduced NF-κB activation. Taken together, these findings point to an increased availability of reducing equivalents in the form of NADH as an important mechanism by which metabolic activity modulates inflammatory signaling through the NF-κB pathway.

Noncystic fibrosis bronchiectasis management: opportunities and challenges.

PURPOSE OF REVIEW: Noncystic fibrosis bronchiectasis is a challenging disease which carries a heavy healthcare burden and significant mortality and morbidity. This review highlights the challenges in the diagnosis of bronchiectasis and discusses the management strategies and research opportunities in this field. RECENT FINDINGS: The challenges in the management of bronchiectasis appear to be multifactorial, arising from both etiological heterogeneity and disease-specific management. Frequent inflammation and infections not only lead to progressive respiratory failure but also increase the risk of cardiovascular complications. No therapies are approved specifically for adult bronchiectasis, but new guidelines and recent studies outline strategies for control of infection and inflammation and for prevention of frequent exacerbations to improve overall prognosis. SUMMARY: Recent studies in the management of bronchiectasis are encouraging. Advances have been made in understanding both disease heterogeneity and best practices for care; interventions such as daily mucociliary clearance, eradication of colonized microbial organisms, and control of inflammation may result in favorable outcomes.

Randomized Trial of Apneic Oxygenation during Endotracheal Intubation of the Critically Ill.

RATIONALE: Hypoxemia is common during endotracheal intubation of critically ill patients and may predispose to cardiac arrest and death. Administration of supplemental oxygen during laryngoscopy (apneic oxygenation) may prevent hypoxemia. OBJECTIVES: To determine if apneic oxygenation increases the lowest arterial oxygen saturation experienced by patients undergoing endotracheal intubation in the intensive care unit. METHODS: This was a randomized, open-label, pragmatic trial in which 150 adults undergoing endotracheal intubation in a medical intensive care unit were randomized to receive 15 L/min of 100% oxygen via high-flow nasal cannula during laryngoscopy (apneic oxygenation) or no supplemental oxygen during laryngoscopy (usual care). The primary outcome was lowest arterial oxygen saturation between induction and 2 minutes after completion of endotracheal intubation. MEASUREMENTS AND MAIN RESULTS: Median lowest arterial oxygen saturation was 92% with apneic oxygenation versus 90% with usual care (95% confidence interval for the difference, -1.6 to 7.4%; P = 0.16). There was no difference between apneic oxygenation and usual care in incidence of oxygen saturation less than 90% (44.7 vs. 47.2%; P = 0.87), oxygen saturation less than 80% (15.8 vs. 25.0%; P = 0.22), or decrease in oxygen saturation greater than 3% (53.9 vs. 55.6%; P = 0.87). Duration of mechanical ventilation, intensive care unit length of stay, and in-hospital mortality were similar between study groups. CONCLUSIONS: Apneic oxygenation does not seem to increase lowest arterial oxygen saturation during endotracheal intubation of critically ill patients compared with usual care. These findings do not support routine use of apneic oxygenation during endotracheal intubation of critically ill adults. Clinical trial registered with www.clinicaltrials.gov (NCT 02051816).

Case of Immune Checkpoint Inhibitor Induced Myasthenia Gravis.

An 85-year-old man was diagnosed with hepatocellular carcinoma (HCC) and was initially treated with transarterial chemoembolization (TACE) and sorafenib. He was then switched to nivolumab and ipilimumab in view of sorafenib intolerance and disease progression. Subsequently, he developed dysphagia and generalized dyspnea culminating in hypercapnic respiratory failure requiring intubation. After an extensive workup, the etiology of his fluctuating respiratory issues was narrowed down to a likely neuromuscular process. Although antibodies to acetylcholine receptors (anti-AChR Ab) were negative, he was treated with high-dose steroids due to clinical concern for Immune Checkpoint Inhibitor (ICI) neurotoxicity. His recovery post immune suppression and absence of recurrence after ICI cessation suggested the possibility of this being an ICI neurotoxicity manifesting with myasthenic symptoms. Incidentally, he also had evidence of aseptic meningitis on cerebrospinal fluid analysis further strengthening this diagnosis. This case illustrates the importance of early recognition of ICI toxicity which will in turn lead to initiating treatments sooner and also decreasing the length of illness.

Arcanobacterium haemolyticum bacteremia presenting as severe sepsis: A case report and review of the literature.

Objective: to describe a case of severe sepsis and complicated bacteremia caused by Arcanobacterium haemolyticum and review similar cases in the literature. Case summary: A 26-year-old gentleman with a history of epilepsy presented with symptoms of sore throat, productive cough, periumbilical abdominal pain, watery diarrhea, nausea and vomiting, subjective fevers along with progressive jaundice for seven days. The patient had acute fulminant liver failure, septic shock, and Multi-organ failure. He required vasopressors, underwent intubation, and had grown Arcanobacterium haemolyticum in the blood and Bronchoalveolar lavage samples. He developed a peritonsillar abscess and cavitary pneumonia and required chest tube drainage followed by thoracotomy for hemothorax. The patient improved on Ampicillin-Sulbactam treatment and was treated with a total antibiotic duration of 6 weeks. He fully improved on post-discharge follow-up. Discussion: Arcanobacterium haemolyticum is a Gram-positive (sometimes Gram variable), catalase-negative facultatively anaerobic, non-motile, non-spore-forming, and variably ß-hemolytic and is known to be a cause of pharyngitis and skin and soft tissue infections. Rarely A. Haemolyticum can be associated with severe systemic infections such as infective endocarditis, systemic abscesses, osteomyelitis, and septicemia. In previous literature reviews, the source of A. haemolyticum depended on the host, and pharyngeal and upper respiratory sources were likely to be associated with immunocompetent hosts. Conclusion: A. haemolyticum should be included in the differential diagnosis of bacterial pharyngitis complicated by severe systemic illness. Penicillins are the most commonly used antibiotics for treating A. haemolyticum bacteremia, and macrolides can be used for Penicillin's treatment failure.

Dysfunctional BMPR2 signaling drives an abnormal endothelial requirement for glutamine in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is increasingly recognized as a systemic disease driven by alteration in the normal functioning of multiple metabolic pathways affecting all of the major carbon substrates, including amino acids. We found that human pulmonary hypertension patients (WHO Group I, PAH) exhibit systemic and pulmonary-specific alterations in glutamine metabolism, with the diseased pulmonary vasculature taking up significantly more glutamine than that of controls. Using cell culture models and transgenic mice expressing PAH-causing BMPR2 mutations, we found that the pulmonary endothelium in PAH shunts significantly more glutamine carbon into the tricarboxylic acid (TCA) cycle than wild-type endothelium. Increased glutamine metabolism through the TCA cycle is required by the endothelium in PAH to survive, to sustain normal energetics, and to manifest the hyperproliferative phenotype characteristic of disease. The strict requirement for glutamine is driven by loss of sirtuin-3 (SIRT3) activity through covalent modification by reactive products of lipid peroxidation. Using 2-hydroxybenzylamine, a scavenger of reactive lipid peroxidation products, we were able to preserve SIRT3 function, to normalize glutamine metabolism, and to prevent the development of PAH in BMPR2 mutant mice. In PAH, targeting glutamine metabolism and the mechanisms that underlie glutamine-driven metabolic reprogramming represent a viable novel avenue for the development of potentially disease-modifying therapeutics that could be rapidly translated to human studies.

Women's Health and Lung Development and Disease.

Although the lung is not traditionally thought of as an organ affected by sex-based differences, emerging literature elucidates major differences between men and women in the development, physiology, and predilection to and outcomes in lung diseases. These differences are driven by both differences in sex hormones and differences in environmental exposures. However, in many cases the underlying etiology of these sex- and gender-based differences is unknown. This article outlines the state-of-the-art knowledge on the etiology of sex differences in lung disease, including differences in lung development and physiology, and reviews therapy recommendations that are sex based.