Bactericidal Antibiotics Induce Toxic Metabolic Perturbations that Lead to Cellular Damage.

The alarming global rise of antibiotic resistance among bacterial pathogens necessitates not only urgent discovery of new antibiotics but also practical strategies to preserve those that are currently used (1, 2). A system-level understanding of the killing mechanisms of bactericidal antibiotics holds the promise of shortening treatment time courses and decreasing the chances that sensitive bacteria will evolve resistance during treatment (3). As different classes of bactericidal antibiotics have different primary cellular target(s), it is not surprising that a significant aspect of the bacterial killing mechanism is specific to the essential function targeted by each antibiotic class: β-lactams induce a futile cycle of cell wall synthesis (4), aminoglycosides induce mistranslation of peptides that compromise inner membrane integrity (5), and fluoroquinolones cause DNA breaks by inhibiting DNA gyrase or topoisomerase IV (6). However, regardless of the primary cellular target, different bactericidal antibiotics all induce a similar cascade of events that contribute to their lethality in Escherichia coli : accelerated respiration (7); changes in iron and redox metabolism (8); formation of reactive oxygen species (9); oxidative damage of DNA (10), RNA, and proteins (11); and cell death. Interestingly, the same killing cascade is seen in a number of antibiotic-independent killing phenomena, for example, T6SS-effector dependent killing (12) and expression of a toxic fusion protein (13). In PNAS, Fan et al. (14) explore whether different classes of bactericidal antibiotics used to treat Mycobacterium tuberculosis , the causative agent of tuberculosis, share a common killing cascade. They used bactericidal antibiotics of the aminoglycoside and fluoroquinolone classes that were also used in previous bactericidal antibiotic lethality studies in E. coli . They discovered that lethal oxidative DNA damage does occur in nongrowing M. tuberculosis cells treated with different bactericidal antibiotics. They also used rifampicin, an RNA polymerase inhibitor that is not bactericidal in … [↵][1]1To whom correspondence should be addressed. Email: evgeny.nudler{at}nyumc.org. [1]: #xref-corresp-1-1

SummaryIt is known that changes in bacterial metabolism can contribute to the modulation of bacterial susceptibility to antibiotics. Understanding how bacterial metabolism is impacted by antibiotics may improve our understanding of the antibiotic mechanism of actions from a metabolic perspective. Here, we utilized a mass spectrometry‐based targeted metabolic profiling technique to characterize the metabolome of a pair of isogenic methicillin‐susceptible and resistant Staphylococcus aureus (MSSA and MRSA) strains RN450 and 450M treated with the sublethal dose of three antibiotics from different classes (β‐lactams, aminoglycosides and quinolones). These treatments induced a set of metabolic alterations after 6 h of co‐incubation with antibiotics. Similar and divergent metabolic perturbations were observed from different antibiotics to the tested strains. Different metabolic response from MSSA and MRSA to the same antibiotics was also detected in the study and indicated the potentially different stress response mechanism in MSSA and MRSA metabolism. This work has shown that a complex set of metabolic changes can be induced by a variety of antibiotics, and the comparative metabolomics strategy can provide a good understanding of this process from a metabolic perspective.

Carbohydrate and lipid metabolism in multiple sclerosis: Clinical implications for etiology, pathogenesis, diagnosis, prognosis, and therapy

ADSA Foundation Scholar Award. Biology of dairy cows during the transition period: the final frontier?

Free radicals have been implicated as Diabetes Mellitus (DM) contributors in type 2 DM and its associated Diabetes Mellitus Neuropathy (DMN). However, the potential for protein mediated oxidative stress to contribute disease pathogenesis remains largely unexplored. To investigate the status and contribution of protein mediated oxidative stress in patients with DM or DMN and to explore whether oxidative protein modification has a role in DM progression to DM associated neuropathy. Sera from 42 DM and 37 DMN patients with varying levels of disease activities biomarkers (HbA1C, patients' age or disease duration) and 21 age- and sex-matched healthy controls were evaluated for serum levels of protein mediated oxidative stress. Serum analysis showed significantly higher levels of protein carbonyl contents in both DM and DMN patients compared with healthy controls. Importantly, not only was there an increased number of subjects positive for protein carbonylation, but also the levels of protein carbonyl contents were significantly higher among DM and DMN patients, whose HbA1C were ≥8.8 as compared with patients with lower HbA1C (HbA1C<8.8). Similar pattern of protein carbonyls formation was also observed with patients' ages or with patient's disease durations, suggesting a possible relationship between protein oxidation and disease progression. Furthermore, sera from DMN patients had higher levels of protein carbonylation compared with non-neuropathic DM patients' sera, suggesting an involvement of protein oxidation in the progression of diabetes to diabetes neuropathy. These findings support an association between protein oxidation and DM or DMN progression. The stronger response observed in patients with higher HbA1C or patients' ages or disease durations suggests, that protein mediated oxidative stress may be useful in evaluating the progression of DM and its associated DMN and in elucidating the mechanisms of these disorders pathogenesis.

Mycobacterium tuberculosis (Mtb) is a persistent intracellular pathogen intrinsically tolerant to most antibiotics. However, the specific factors that mediate this tolerance remain incompletely defined. Here we apply metabolomic profiling to discover a common set of metabolic changes associated with the activities of three clinically used tuberculosis drugs, isoniazid, rifampicin and streptomycin. Despite targeting diverse cellular processes, all three drugs trigger activation of Mtb's isocitrate lyases (ICLs), metabolic enzymes commonly assumed to be involved in replenishing of tricarboxylic acid (TCA) cycle intermediates. We further show that ICL-deficient Mtb strains are significantly more susceptible than wild-type Mtb to all three antibiotics, and that this susceptibility can be chemically rescued when Mtb is co-incubated with an antioxidant. These results identify a previously undescribed role for Mtb's ICLs in antioxidant defense as a mechanism of antibiotic tolerance.

Environmental and genetic risk factors, and their interactions, contribute significantly to the etiology of neurodevelopmental disorders (NDDs). Recent epidemiology studies have implicated pyrethroid pesticides as an environmental risk factor for autism and developmental delay. Our previous research showed that low-dose developmental exposure to the pyrethroid pesticide deltamethrin in mice caused male-biased changes in the brain and in NDD-relevant behaviors in adulthood. Here, we used a metabolomics approach to determine the broadest possible set of metabolic changes in the adult male mouse brain caused by low-dose pyrethroid exposure during development. Using a litter-based design, we exposed mouse dams during pregnancy and lactation to deltamethrin (3 mg/kg or vehicle every 3 days) at a concentration well below the EPA-determined benchmark dose used for regulatory guidance. We raised male offspring to adulthood and collected whole brain samples for untargeted high-resolution metabolomics analysis. Developmentally exposed mice had disruptions in 116 metabolites which clustered into pathways for folate biosynthesis, retinol metabolism, and tryptophan metabolism. As a cross-validation, we integrated metabolomics and transcriptomics data from the same samples, which confirmed previous findings of altered dopamine signaling. These results suggest that pyrethroid exposure during development leads to disruptions in metabolism in the adult brain, which may inform both prevention and therapeutic strategies.

Chronic administration of methamphetamine hydrochloride (MA-HCl, philopon) has a marked ability to produce a reduction in activity. However, it would appear strange that such a psychic stimulant as methamphetamine has an effect like this. Dr. UTENA et al (2) and Dr. YAGI (11) also has clearly shown that a reduction of spontaneity lasts as long as two months after the cessation of chronic administration made for about a month. Dr. UTENA explained comprehensively that inactivity produced by chronic administration of methamphetamine is very similar to a reduction of spontaneity which is certainly one of the essential symptoms of psychotic patients from the view point of experimental psychopathology. This effect was called an after-depression by Dr. UTENA and in our experiment the after-depression was studied from the view point of experimental psychology.Methods : 21 male albino rats, aged about 150 days at the end of the experiment, were used and they were divided into three groups, namely a control group, a MA · avoidance group, and a MA-avoidance group.1. In the control group, rats were not given methamphetamine and were tested by the method of avoidance learning.2. In the MA · avoidance group, rats were tested by the method of avoidance learning on the 36th day after every 35 days of daily injection of methamphetamine (6 mg/kg/a day, dissolved by 2cc saline, given subcutaneously).3. In the MA-avoidance group, rats were tested by the method of avoidance learning on the 66th day : after 35 days' injections which are the same procedures as in the case of the MA · avoidance group and the 30 days' period of rest in each home cage.Results and conclusions : As it would be seen in Table 1, avoidance learning was more difficult in the MA·avoidance group and the MA-avoidance group than in the control group. It is interpreted as chronic administration of MA-HCl makes rats dull.It is a well known fact that fast extinction succeeds slow learning because discrimination between them becomes easy, and this fact is clearly shown in Table 1 also. However, both of the experimental groups did not show fast extinction and showed slower extinction than did the control group. It is interpreted as chronic administration of MA-HCl makes rats fearful.The present findings mentioned above are due to the adapted mechanisms for the chronic chemical stimulation, that is, a set of metabolic changes in the brain tissues as observed by Dr. UTENA, but not to the loss of motor ability because difference between the control group and the two experimental groups was not seen in running times at the first trials and the last trials of learning.

Oxidative metabolism, ROS and NO under oxygen deprivation

Developmental pyrethroid exposure in mouse leads to disrupted brain metabolism in adulthood

Thioredoxins (Trxs) modulate metabolic responses during stress conditions; however, the mechanisms governing the responses of plants subjected to multiple drought events and the role of Trxs under these conditions are not well understood. Here we explored the significance of the mitochondrial Trx system in Arabidopsis following exposure to single and repeated drought events. We analyzed the previously characterized NADPH-dependent Trx reductase A and B double mutant (ntra ntrb) and two independent mitochondrial thioredoxin o1 (trxo1) mutant lines. Following similar reductions in relative water content (∼50%), Trx mutants subjected to two drought cycles displayed a significantly higher maximum quantum efficiency (Fv/Fm) and were less sensitive to drought than their wild-type counterparts and than all genotypes subjected to a single drought event. Trx mutant plants displayed a faster recovery after two cycles of drought, as observed by the higher accumulation of secondary metabolites and higher stomatal conductance. Our results indicate that plants exposed to multiple drought cycles are able to modulate their subsequent metabolic and physiological response, suggesting the occurrence of an exquisite acclimation in stressed Arabidopsis plants. Moreover, this differential acclimation involves the participation of a set of metabolic changes as well as redox poise alteration following stress recovery.

Metabolic-dysfunction-associated steatotic liver disease (MASLD, formerly known as NAFLD) is a global chronic liver disease, and no licensed drugs are currently available for its treatment. The incidence of MASLD is increasing, which could lead to a huge clinical and economic burden. As a multifactorial disease, MASLD involves a complex set of metabolic changes, and many monotherapies for it are not clinically effective. Therefore, combination therapies using multiple drugs are emerging, with the advantages of improving drug efficacy and reducing side effects. Peanut skin extract (PSE), geniposide (GEN), and isoquercitrin (IQ) are three natural antiaging components or compounds. In this study, the preventive effects of individual PSE, GEN, and IQ in comparison with the effects of their mixture (MPGI) were examined in a mouse model of high-fat-feed-induced MASLD. The results showed that MPGI could significantly reduce the body and liver weights of mice and improve hepatic steatosis and liver function indicators. Further mechanistic studies showed that PSE, GEN, and IQ worked together by reducing inflammation, modulating the intestinal flora, and regulating the TLR4/NF-κB, AMPK/ACC/CPT1, and AMPK/UKL1/LC3B signaling pathways. It is a promising therapeutic method for preventing MASLD.

An overnight fast of 8–10 h is normal for most people. Fasting is characterised by a coordinated set of metabolic changes designed to spare carbohydrate and increase reliance on fat...

The thrifty aged hypothesis (TAH) holds that aging is a "saving program", a set of strategies all of them focused to reduce energy consumption in the post-reproductive age. Aged adults remove fewer energy resources from the environment, and the remaining fuel can be profitably used by offspring. Thus, from an evolutionary point of view, the variable submitted to natural selection would be the amount of energy removed by post-reproductive individuals from the environment, favoring "reduced energy extraction" (REE) strategies. Senescence is characterized by a set of metabolic changes, and one of them is a deep modification in adipose tissue. A pattern of progressive loss of subcutaneous (SF) and gain of visceral fat (VF) throughout life has been demonstrated. The evolutionary reasons for this change have not been explored. No one has questioned why energy is deposited in VF. It appears that VF is not the best place for storing fat. The objective of this theoretical paper is to analyze the relationship between aging and adipose tissue. Furthermore, an evolutionary explanation is proposed. Fat redistribution could be thought of as a consequence of the TAH. While SF responds to the equilibrium between energy needs and fuel supply, VF acts in a dysfunctional manner. VF is not coordinated with pathways that regulate the state of fat depots. Hence, the purpose of the changes observed upon aging is to limit the effectiveness of those pathways that force the organism to obtain energy from the environment. In summary, adipose tissue modifications promote REE strategies.

BackgroundDepression is one of the most common and untreated comorbidities in chronic obstructive pulmonary disease (COPD), and is associated with poor health outcomes (e.g. increased hospitalization/exacerbation rates). Although metabolic disturbances have been suggested in depressed non-diseased conditions, comprehensive metabolic phenotyping has never been conducted in those with COPD. We examined whether depressed COPD patients have certain clinical/functional features and exhibit a specific amino acid phenotype which may guide the development of targeted (nutritional) therapies.MethodsSeventy-eight outpatients with moderate to severe COPD (GOLD II–IV) were stratified based on presence of depression using a validated questionnaire. Lung function, disease history, habitual physical activity and protein intake, body composition, cognitive and physical performance, and quality of life were measured. Comprehensive metabolic flux analysis was conducted by pulse stable amino acid isotope administration. We obtained blood samples to measure postabsorptive kinetics (production and clearance rates) and plasma concentrations of amino acids by LC–MS/MS. Data are expressed as mean [95% CI]. Stats were done by graphpad Prism 9.1.0. ɑ < 0.05.ResultsThe COPD depressed (CD, n = 27) patients on average had mild depression, were obese (BMI: 31.7 [28.4, 34.9] kg/m2), and were characterized by shorter 6-min walk distance (P = 0.055), physical inactivity (P = 0.03), and poor quality of life (P = 0.01) compared to the non-depressed COPD (CN, n = 51) group. Lung function, disease history, body composition, cognitive performance, and daily protein intake were not different between the groups. In the CD group, plasma branched chain amino acid concentration (BCAA) was lower (P = 0.02), whereas leucine (P = 0.01) and phenylalanine (P = 0.003) clearance rates were higher. Reduced values were found for tyrosine plasma concentration (P = 0.005) even after adjustment for the large neutral amino acid concentration (= sum BCAA, tyrosine, phenylalanine and tryptophan) as a marker of dopamine synthesis (P = 0.048).ConclusionMild depression in COPD is associated with poor daily performance and quality of life, and a set of metabolic changes in depressed COPD that include perturbation of large neutral amino acids, specifically the BCAAs.Trial registration clinicaltrials.gov: NCT01787682, 11 February 2013—Retrospectively registered; NCT02770092, 12 May 2016—Retrospectively registered; NCT02780219, 23 May 2016—Retrospectively registered; NCT03796455, 8 January 2019—Retrospectively registered.