No abstract

Mitochondria of patients with alcoholic liver disease exhibit structural abnormalities, and mitochondria isolated from animals exposed to ethanol are functionally deficient when studied in vitro. To assess possible functional consequences of these ethanol-associated alterations in vivo, we measured mitochondrial function in alcoholics noninvasively with a breath test. A mitochondrial function, the decarboxylation of ketoisocaproate (KICA), was assessed by measuring the exhalation of 13CO2 following the administration of 1 mg/kg 2-keto[1-13C]isocaproic acid, the decarboxylation of which occurs in mitochondria. The results of the KICA breath test in 12 alcoholic subjects were compared with the results in healthy controls and patients with nonalcoholic liver disease. The peak exhalation of 13CO2 and the fraction of the administered dose decarboxylated in 120 min were both significantly lower in alcoholics than in healthy controls and patients with nonalcoholic liver disease. In alcoholics, KICA decarboxylation was impaired in the presence of normal quantitative liver function tests such as the aminopyrine breath test and galactose elimination capacity, indicating that KICA decarboxylation does not simply reflect a decreased functional hepatic mass. The enrichment of circulating KICA with [13C]KICA was similar in alcoholics and controls, indicating that a decreased bioavailability or an increased dilution of labeled KICA cannot account for the decreased exhalation of 13CO2. It is concluded that mitochondrial function as reflected by KICA decarboxylation is impaired in chronic alcoholics. The functional impairment is specific for ethanol abuse and not a reflection of decreased global hepatic function. KICA decarboxylation could thus be useful as a marker for excessive ethanol consumption.

The excellent sensitivity and specificity of the urea breath test9 101718 and its simplicity make it an ideal method for screening people for H pylori colonisation. Thus we evaluated 100 healthy adults with a broad age range for past or active H pylori infection using serology and the urea breath test. Patients and methods PATIENTSOne hundred people aged 20 to 92 participated in this study. All were healthy and were invited by the investigators to participate. They were recruited from family members, friends, and relatives of the investigators and fellow workers. None had a history of chronic dyspepsia, peptic ulcers, or gastric or other abdominal surgery except for appendicitis; none had taken antacids, a bismuth preparation, or other drugs for dyspepsia within the previous year, and none had taken antibiotics within the three months before the study. The protocol was approved by the University of Basel Ethical Committee and each subject gave written informed consent.'3C-UREA BREATH TEST All breath tests were performed in the morning after an overnight fast according to the method used and validated previously'0; Dill et al have shown that the urea breath test has a sensitivity and specificity of 97% and 100%, respectively.'0 Briefly, the subjects drank 150 ml of a liquid test meal to delay gastric emptying and subsequently 150 mg '3C-urea dissolved in 20 ml of tap water. 'C-urea (99% '3C) was purchased as a crystalline substance (Tracer Technologies Inc, Somerville MA, USA). The test meal we used was a 25% glucose polymeric solution that was prepared as a powder (glucose 4 g, maltose 2 g, polysaccharide 30 g, citric acid 0.2 g) in 250 ml bottles and dissolved with 150 ml of tap water immediately before use. Two breath samples were obtained at baseline and then every 15 min for up to 60 min and stored in silicon-coated, evacuated 20 ml glass tubes (vacutainers) for later analysis. Excess '3C02 in breath samples was measured by isotope ratio mass spectrometry (Sira 10, VG

Whether screening the metabolic activity of immune cells facilitates discovery of molecular pathology remains unknown. Here we prospectively screened the extracellular acidification rate (ECAR) as a measure of glycolysis and the oxygen consumption rate (OCR) as a measure of mitochondrial respiration in B cells from patients with primary antibody deficiency (PAD). The highest OCR values were detected in three study participants with persistent polyclonal B cell lymphocytosis (PPBL). Exome sequencing identified germline mutations in SDHA, which encodes succinate dehydrogenase subunit A, in all three patients with PPBL. SDHA gain-of-function led to accumulation of fumarate in PPBL B cells, which engaged the KEAP1-Nrf2 system to drive the transcription of genes encoding inflammatory cytokines. In a single patient trial, blocking the activity of the cytokine IL-6 in vivo prevented systemic inflammation and ameliorated clinical disease. Overall, our study has identified pathological mitochondrial retrograde signaling as a disease modifier in PAD. 3 Primary immunodeficiency disorders (PIDs) are rare genetic syndromes arising from defects in the immune system 1. The majority of PID patients display primary antibody deficiency (PAD) that can develop due to B cell intrinsic defects 2. The causes and genetic background of PADs are complex and pathogenic mutations have been identified only in a minority of cases 3, 4, 5. PADs present with a spectrum of clinical problems, ranging from infections to autoinflammation, autoimmunity, lymphoproliferation and enteropathy. Non-infectious complications are typically unaffected by immunoglobulin replacement therapy and contribute to excess mortality 6. The spectrum of clinical presentation is broad even in patients harboring the same pathogenic mutations, pointing to disease modifiers shaping clinical features 6. Cellular metabolism governs immune cell function 7, 8, 9. Specifically, various facets of glycolysis and glutaminolysis impact the function of B cells 10, 11, 12, 13. Glutaminolysis can contribute to ATP production, and glutamine-derived α-ketoglutarate (α-KG) serves as an anaplerotic source of tricarboxylic acid (TCA) cycle metabolites 14. Mitochondrial oxidative phosphorylation (OxPhos) produces most of the ATP required for anabolic processes in immune cells 15. Non-bioenergetic features of mitochondria also regulate immune cell function. Production of mitochondrial reactive oxygen species (mROS) has been linked to the activation of the transcription factor NFAT in CD4 + T cells and to inhibition of the B cell antigen receptor (BCR) signaling in B cells 16, 17. In T cells, mitochondrial function and epigenetic remodeling are interlinked via pyruvate oxidation and conversion of pyruvate-derived citrate to acetyl-CoA, which is required for histone acetylation 18, 19. Metabolites of the TCA cycle can also directly activate (a-KG), or inhibit (fumarate, succinate) dioxygenases involved in histone and DNA demethylation, thus modulating transcriptional activity. This process of m...

Limited thymic recovery after extracorporeal photopheresis in a low-bodyweight patient with acute graft-versus-host disease of the skin.