Analysis of real-world length of stay data and costs associated with use of autologous skin cell suspension for the treatment of small burns in U.S. centers.

BACKGROUND: Autologous skin cell suspension (ASCS) is a treatment for acute thermal burn injuries associated with significantly lower donor skin requirements than conventional split-thickness skin grafts (STSG). Projections using the BEACON model suggest that among patients with small burns (total body surface area [TBSA]<20 %), use of ASCS± STSG leads to a shorter length of stay (LOS) in hospital and cost savings compared with use of STSG alone. This study evaluated whether data from real-world clinical practice corroborate these findings. MATERIALS AND METHODS: Electronic medical record data were collected from January 2019 through August 2020 from 500 healthcare facilities in the United States. Adult patients receiving inpatient treatment with ASCS± STSG for small burns were identified and matched to patients receiving STSG using baseline characteristics. LOS was assumed to cost $7554/day and to account for 70 % of overall costs. Mean LOS and costs were calculated for the ASCS± STSG and STSG cohorts. RESULTS: A total of 151 ASCS± STSG and 2243 STSG cases were identified; 63.0 % of patients were male and the average age was 44.2 years. Sixty-three matches were made between cohorts. LOS was 18.5 days with ASCS± STSG and 20.6 days with STSG (difference: 2.1 days [10.2 %]). This difference led to bed cost savings of $15,587.62 per ASCS± STSG patient. Overall cost savings with ASCS± STSG were $22,268.03 per patient. CONCLUSIONS: Analysis of real-world data shows that treatment of small burn injuries with ASCS± STSG provides reduced LOS and substantial cost savings compared with STSG, supporting the validity of the BEACON model projections.

Clinical Practice Guideline: Early Mobilization and Rehabilitation of Critically Ill Burn Patients.

This Clinical Practice Guideline addresses early mobilization and rehabilitation (EMR) of critically ill adult burn patients in an intensive care unit (ICU) setting. We defined EMR as any systematic or protocolized intervention that could include muscle activation, active exercises in bed, active resistance exercises, active side-to-side turning, or mobilization to sitting at the bedside, standing, or walking, including mobilization using assistance with hoists or tilt tables, which was initiated within at least 14 days of injury, while the patient was still in an ICU setting. After developing relevant PICO (Population, Intervention, Comparator, Outcomes) questions, a comprehensive literature search was conducted with the help of a professional medical librarian. Available literature was reviewed and systematically evaluated. Recommendations were formulated through the consensus of a multidisciplinary committee, which included burn nurses, physicians, and rehabilitation therapists, based on the available scientific evidence. No recommendation could be formed on the use of EMR to reduce the duration of mechanical ventilation in the burn ICU, but we conditionally recommend the use of EMR to reduce ICU-acquired weakness in critically ill burn patients. No recommendation could be made regarding EMR's effects on the development of hospital-acquired pressure injuries or disruption or damage to the skin grafts and skin substitutes. We conditionally recommend the use of EMR to reduce delirium in critically ill burn patients in the ICU.

Experience with Implementing a Beta-lactam Therapeutic Drug Monitoring Service in a Burn Intensive Care Unit: A Retrospective Chart Review.

Thermal injuries alter pharmacokinetics, complicating the prediction of standard antibiotic dose effectiveness. Therapeutic drug monitoring (TDM) has been proposed to prevent subtherapeutic dosing of antibiotic therapy, but remains scarcely studied in the burn patient population. A retrospective chart review of burn patients receiving beta-lactam TDM from 2016 to 2019 was conducted. Adult patients with thermal injury receiving cefepime, piperacillin/tazobactam, or meropenem for ≥48 hours were included. Between February 2016 and July 2017, we utilized selective TDM based on clinical judgement to guide treatment. From October 2018 until July 2019, TDM was expanded to all burn patients on beta-lactams. The primary endpoint was achievement of therapeutic concentration, and the secondary endpoints were clinical cure, culture clearance, new resistance, length of stay, and mortality. The selective (control) group included 19 patients and the universal (study) group reviewed 23 patients. In both groups, skin and lungs were the most common primary infection sources, with Pseudomonas aeruginosa as the most common species. In the universal cohort, patients were older with higher risk factors, but more frequently achieved the target drug concentration, required less days to start TDM (p < .0001), and had more frequent measurements and beta-lactam dose adjustments. Positive clinical outcome was reported in 77%, and microbial eradication in 82% of all patients. All clinical outcomes were similar between the groups. The implementation of beta-lactam TDM protocol shortened the time, increased the probability of appropriate target attainment, and individualized beta-lactam therapy in burn patients.

Length of Stay and Costs with Autologous Skin Cell Suspension Versus Split-Thickness Skin Grafts: Burn Care Data from US Centers.

INTRODUCTION: Autologous skin cell suspension (ASCS) significantly reduces donor skin requirements versus conventional split-thickness skin grafts (STSG) for thermal burn treatment. In analyses using the Burn-medical counter measure Effectiveness Assessment Cost Outcomes Nexus (BEACON) model, ASCS was associated with shorter hospital length of stay (LOS) and cost savings versus STSG. This study hypothesized that daily practice data from the USA would support these findings. METHODS: Electronic medical record data from 500 healthcare facilities (January 2019-August 2020) were used to match adult patients who received inpatient burn treatment with ASCS (± STSG) to patients treated with STSG alone on the basis of sex, age, percent total body surface area (TBSA), and comorbidities. Based on BEACON analyses, LOS was assumed to represent 70% of total costs and used as a proxy to assess the data. Mean LOS, costs, and the incremental revenue associated with inpatient capacity changes were calculated. RESULTS: A total of 151 ASCS and 2443 STSG patients were identified: 63.0% were male and average age was 44.5 years. Eight-one matches were made between cohorts. LOS was 21.7 days with ASCS and 25.0 days with STSG alone (difference 3.3 days [13.2%]). LOS was lower with ASCS than STSG in four of five TBSA intervals. The LOS difference led to hospital bed cost savings of $25,864 per ASCS patient; overall cost savings were $36,949 per patient. Similar cost savings were observed in TBSA groupings < 20% and ≥ 20%. The reduced LOS with ASCS translated into an increased capacity of 2.2 inpatients/bed annually, which increased hospital revenue by $92,283/burn unit bed annually. CONCLUSIONS: Real-world data show that ASCS (± STSG) is associated with reduced LOS and cost savings versus STSG alone across all burn sizes, supporting the validity of the BEACON analyses. ASCS use may also increase patient capacity and throughput, leading to increased hospital revenue.

Autologous skin cell suspension (ASCS) is a treatment for thermal skin burn injuries that can be used alone or in combination with split-thickness skin grafts (STSG), the conventional standard of care. Projections using the Burn-medical counter measure Effectiveness Assessment Cost Outcomes Nexus (BEACON) model indicate that ASCS leads to shorter hospital length of stay (LOS) and overall cost savings compared with STSG alone. These model findings are supported by benchmarking study data from a limited sample of US burn centers. The current study aimed to understand whether the BEACON projections are supported by daily clinical practice data from US healthcare facilities. Using electronic medical record data, we matched patients who received ASCS ± STSG from January 2019 to August 2020 to those receiving STSG alone on the basis of demographic and clinical factors. Data analysis showed that hospital LOS was shorter (3.3 days) with ASCS ± STSG than STSG alone, a difference associated with a hospital bed cost savings of $25,864 per ASCS patient. Overall cost savings, which included nursing time and other costs, were $36,949 per patient. Analysis of patients with burns comprising total body surface areas less than 20% or at least 20% showed cost savings in both groups. The reduced LOS with ASCS also translated into the ability to treat 2.2 more patients per hospital bed per year, which was projected to increase hospital earnings. These real-world findings support those of modeling analyses, indicating that use of ASCS ± STSG is associated with meaningful clinical and economic benefits compared with use of STSG alone.

A phase 3, open-label, controlled, randomized, multicenter trial evaluating the efficacy and safety of StrataGraft® construct in patients with deep partial-thickness thermal burns.

OBJECTIVE: This phase 3 study evaluated StrataGraft construct as a donor-site sparing alternative to autograft in patients with deep partial-thickness (DPT) burns. METHODS: Patients aged ≥18 years with 3-49% total body surface area (TBSA) thermal burns were enrolled. In each patient, 2 DPT areas (≤2000cm2 total) of comparable depth after excision were randomized to either cryopreserved StrataGraft or autograft. Coprimary endpoints were: the difference in percent area of StrataGraft treatment site and autograft treatment site autografted at Month 3 (M3), and the proportion of patients achieving durable wound closure of the StrataGraft site without autograft at M3. Safety assessments were performed in all patients. Efficacy and safety follow-up continued to 1 year. RESULTS: Seventy-one patients were enrolled. By M3, there was a 96% reduction in mean percent area of StrataGraft treatment sites that required autografting, compared with autograft treatment sites (4.3% vs 102.1%, respectively; P<.0001). StrataGraft treatment resulted in durable wound closure at M3 without autografting in 92% (95% CI: 85.6, 98.8; n/n 59/64) of patients for whom data were available. The most common StrataGraft-related adverse event was pruritus (15%). CONCLUSIONS: Both coprimary endpoints were achieved. StrataGraft may offer a new treatment for DPT burns to reduce the need for autografting. CLINICAL TRIAL IDENTIFIER: NCT03005106.

Porcine Xenograft and Epidermal Fully Synthetic Skin Substitutes in the Treatment of Partial-Thickness Burns: A Literature Review.

Background and Objectives: Porcine xenografts have been used successfully in partial thickness burn treatment for many years. Their disappearance from the market led to the search for effective and efficient alternatives. In this article, we examine the synthetic epidermal skin substitute Suprathel® as a substitute in the treatment of partial thickness burns. Materials and Methods: A systematic review following the PRISMA guidelines has been performed. Sixteen Suprathel® and 12 porcine xenograft studies could be included. Advantages and disadvantages between the treatments and the studies' primary endpoints have been investigated qualitatively and quantitatively. Results: Although Suprathel had a nearly six times larger TBSA in their studies (p < 0.001), it showed a significantly lower necessity for skin grafts (p < 0.001), and we found a significantly lower infection rate (p < 0.001) than in Porcine Xenografts. Nonetheless, no significant differences in the healing time (p = 0.67) and the number of dressing changes until complete wound healing (p = 0.139) could be found. Both products reduced pain to various degrees with the impression of a better performance of Suprathel® on a qualitative level. Porcine xenograft was not recommended for donor sites or coverage of sheet-transplanted keratinocytes, while Suprathel® was used successfully in both indications. Conclusion: The investigated parameters indicate that Suprathel® to be an effective replacement for porcine xenografts with even lower subsequent treatment rates. Suprathel® appears to be usable in an extended range of indications compared to porcine xenograft. Data heterogeneity limited conclusions from the results.

Pseudomonal Meningoencephalitis With Ventriculitis Secondary to Bacteremia in a Burn Patient: A Novel Case.

Burn patients with large burn surface area involvement are at increased risk of infection due to the presence of large wounds, multiple surgeries, prolonged intensive care unit admission, and immunosuppression. Pseudomonas aeruginosa is the most commonly isolated organism in this population. Even with frequent infections in the burn population, meningitis and encephalitis are rare, and ventriculitis is exceptional. We report the case of a 66-year-old woman who developed P. aeruginosa bacteremia during her hospital course, causing secondary meningoencephalitis with ventriculitis. She was admitted for partial- and full-thickness burns affecting the neck, chest, abdomen, upper medial arms, and bilateral anteromedial thighs for an estimated 20% total body surface area burn. She met sepsis criteria and broad-spectrum antimicrobial coverage was initiated. Magnetic resonance imaging of the brain, performed for altered mental status, revealed meningitis and ventriculitis. Cerebrospinal fluid analysis demonstrated findings consistent with bacterial meningitis, with cultures positive for P. aeruginosa. Serial neuroimaging with computerized tomography revealed new areas of ischemia concerning for septic emboli. In the presence of altered mental status and fever of unknown origin, workup should remain broad. Even in the presence of another source, it is important to keep an open mind for the rarer intracerebral infection as it requires different management, including urgent evaluation of antibiotic selection and dosing to ensure central nervous system penetration, and neurosurgical evaluation.

American Burn Association Guidelines on the Management of Acute Pain in the Adult Burn Patient: A Review of the Literature, a Compilation of Expert Opinion, and Next Steps.

The ABA pain guidelines were developed 14 years ago and have not been revised despite evolution in the practice of burn care. A sub-committee of the American Burn Association's Committee on the Organization and Delivery of Burn Care was created to revise the adult pain guidelines. A MEDLINE search of English-language publications from 1968 to 2018 was conducted using the keywords "burn pain," "treatment," and "assessment." Selected references were also used from the greater pain literature. Studies were graded by two members of the committee using Oxford Centre for Evidence-based Medicine-Levels of Evidence. We then met as a group to determine expert consensus on a variety of topics related to treating pain in burn patients. Finally, we assessed gaps in the current knowledge and determined research questions that would aid in providing better recommendations for optimal pain management of the burn patient. The literature search produced 189 papers, 95 were found to be relevant to the assessment and treatment of burn pain. From the greater pain literature 151 references were included, totaling 246 papers being analyzed. Following this literature review, a meeting to establish expert consensus was held and 20 guidelines established in the areas of pain assessment, opioid medications, nonopioid medications, regional anesthesia, and nonpharmacologic treatments. There is increasing research on pain management modalities, but available studies are inadequate to create a true standard of care. We call for more burn specific research into modalities for burn pain control as well as research on multimodal pain control.

Results of a Multicenter Feasibility Study of an Automated Bedside Glucose Monitoring System in the Burn Intensive Care Setting.

Intensive blood glucose regimens required for tight glycemic control in critically ill burn patients carry risk of hypoglycemia and are ultimately limited by the frequency of which serum glucose measurements can be feasibly monitored. Continuous inline glucose monitoring has the potential to significantly increase the frequency of serum glucose measurement. The objective of this study was to assess the accuracy of a continuous glucose monitor with inline capability (Optiscanner) in the burn intensive care setting. A multicenter, observational study was conducted at two academic burn centers. One hundred and six paired blood samples were collected from 10 patients and measured on the Optiscanner and the Yellow Springs Instrument. Values were plotted on a Clarke Error Grid and mean absolute relative difference calculated. Treatment was guided by existing hospital protocols using separately obtained values. 97.2% of results obtained from Optiscanner were within 25% of corresponding Yellow Springs Instrument values and 100% were within 30%. Mean absolute relative difference was calculated at 9.6%. Our findings suggest that a continuous glucose monitor with inline capability provides accurate blood glucose measurements among critically ill burn patients.

Management of exposed pacemaker caused by burns.

Annual implants of cardiovascular implantable devices (CIEDs) are increasing, thus increasing the risk of device exposure. This case presents CIED management issues following traumatic thermal injury. A 59-year-old female presented to intensive care with 42% total body surface area burn involving tissue over her pacemaker generator. Electrophysiologists interrogated and reprogrammed the pacer and observed the patient over 72 hours without pacing. Serratia bacteremia developed and cardiology recommended device removal. The pacemaker generator and leads were removed by cardiothoracic and burn surgery. Postoperatively, asystole required emergency transvenous pacing wire placement. During bacteremia treatment, cardiology planned to pace with an active-fixation screw-in lead with long-term plans to place a single right ventricular chamber leadless pacemaker because of the extensive burns. The patient developed fungemia and the family opted for comfort care. This case report discusses the management of a CIED exposed after a traumatic thermal burn, including device extraction.

Cardiorespiratory Capacity and Strength Remain Attenuated in Children with Severe Burn Injuries at Over 3 Years Postburn.

OBJECTIVES: To compare physical capacity and body composition between children with burn injuries at approximately 4 years postburn and healthy, fit children. STUDY DESIGN: In this retrospective, case-control study, we analyzed the strength, aerobic capacity, and body composition of children with severe burn injuries (n = 40) at discharge, after completion of a 6- to 12-week rehabilitative exercise training program, and at 3-4 years postburn. Values were expressed as a relative percentage of those in age- and sex-matched children for comparison (n = 40 for discharge and postexercise; n = 40 for 3.5 years postburn). RESULTS: At discharge, lean body mass was 89% of that in children without burn injuries, and exercise rehabilitation restored this to 94% (P < .01). At 3.5 years postburn, lean body mass (94%), bone mineral content (89%), and bone mineral density (93%; each P ≤ .02) remained reduced, whereas total body fat was increased (148%, P = .01). Cardiorespiratory fitness remained lower in children with burn injuries both after exercise training (75%; P < .0001) and 3.5 years later (87%; P < .001). Peak torque (60%; P < .0001) and average power output (58%; P < .0001) were lower after discharge. Although exercise training improved these, they failed to reach levels achieved in healthy children without burns (83-84%; P < .0001) but were maintained at 85% and 82%, respectively, 3.5 years later (P < .0001). CONCLUSIONS: Although the benefits of rehabilitative exercise training on strength and cardiorespiratory capacity are maintained at almost 4 years postburn, they are not restored fully to the levels of healthy children. Although the underlying mechanism of this phenomenon remains elusive, these findings suggest that future development of continuous exercise rehabilitation interventions after discharge may further narrow the gap in relation to healthy adolescents.

Tunneling nanotubes: an alternate route for propagation of the bystander effect following oncolytic viral infection.

Tunneling nanotubes (TNTs) are ultrafine, filamentous actin-based cytoplasmic extensions which form spontaneously to connect cells at short and long-range distances. We have previously described long-range intercellular communication via TNTs connecting mesothelioma cells in vitro and demonstrated TNTs in intact tumors from patients with mesothelioma. Here, we investigate the ability of TNTs to mediate a viral thymidine kinase based bystander effect after oncolytic viral infection and administration of the nucleoside analog ganciclovir. Using confocal microscopy we assessed the ability of TNTs to propagate enhanced green fluorescent protein (eGFP), which is encoded by the herpes simplex virus NV1066, from infected to uninfected recipient cells. Using time-lapse imaging, we observed eGFP expressed in infected cells being transferred via TNTs to noninfected cells; additionally, increasing fluorescent activity in recipient cells indicated cell-to-cell transmission of the eGFP-expressing NV1066 virus had also occurred. TNTs mediated cell death as a form of direct cell-to-cell transfer following viral thymidine kinase mediated activation of ganciclovir, inducing a unique long-range form of the bystander effect through transmission of activated ganciclovir to nonvirus-infected cells. Thus, we provide proof-of-principle demonstration of a previously unknown and alternative mechanism for inducing apoptosis in noninfected recipient cells. The conceptual advance of this work is that TNTs can be harnessed for delivery of oncolytic viruses and of viral thymidine kinase activated drugs to amplify the bystander effect between cancer cells over long distances in stroma-rich tumor microenvironments.

Oncolytic herpes simplex virus kills stem-like tumor-initiating colon cancer cells.

Stem-like tumor-initiating cells (TICs) are implicated in cancer progression and recurrence, and can be identified by sphere-formation and tumorigenicity assays. Oncolytic viruses infect, replicate in, and kill a variety of cancer cells. In this study, we seek proof of principle that TICs are susceptible to viral infection. HCT8 human colon cancer cells were subjected to serum-free culture to generate TIC tumorspheres. Parent cells and TICs were infected with HSV-1 subtype NV1066. Cytotoxicity, viral replication, and Akt1 expression were assessed. TIC tumorigenicity was confirmed and NV1066 efficacy was assessed in vivo. NV1066 infection was highly cytotoxic to both parent HCT8 cells and TICs. In both populations, cell-kill of >80% was achieved within 3 days of infection at a multiplicity of infection (MOI) of 1.0. However, the parent cells required 2-log greater viral replication to achieve the same cytotoxicity. TICs overexpressed Akt1 in vitro and formed flank tumors from as little as 100 cells, growing earlier, faster, larger, and with greater histologic atypia than tumors from parent cells. Treatment of TIC-induced tumors with NV1066 yielded tumor regression and slowed tumor growth. We conclude that colon TICs are selected for by serum-free culture, overexpress Akt1, and are susceptible to oncolytic viral infection.

Maximal oxidative capacity during exercise is associated with skeletal muscle fuel selection and dynamic changes in mitochondrial protein acetylation.

Maximal exercise-associated oxidative capacity is strongly correlated with health and longevity in humans. Rats selectively bred for high running capacity (HCR) have improved metabolic health and are longer-lived than their low-capacity counterparts (LCR). Using metabolomic and proteomic profiling, we show that HCR efficiently oxidize fatty acids (FAs) and branched-chain amino acids (BCAAs), sparing glycogen and reducing accumulation of short- and medium-chain acylcarnitines. HCR mitochondria have reduced acetylation of mitochondrial proteins within oxidative pathways at rest, and there is rapid protein deacetylation with exercise, which is greater in HCR than LCR. Fluxomic analysis of valine degradation with exercise demonstrates a functional role of differential protein acetylation in HCR and LCR. Our data suggest that efficient FA and BCAA utilization contribute to high intrinsic exercise capacity and the health and longevity benefits associated with enhanced fitness.

A novel oncolytic viral therapy and imaging technique for gastric cancer using a genetically engineered vaccinia virus carrying the human sodium iodide symporter.

BACKGROUND: Gastric cancers have poor overall survival despite recent advancements in early detection methods, endoscopic resection techniques, and chemotherapy treatments. Vaccinia viral therapy has had promising therapeutic potential for various cancers and has a great safety profile. We investigated the therapeutic efficacy of a novel genetically-engineered vaccinia virus carrying the human sodium iodide symporter (hNIS) gene, GLV-1 h153, on gastric cancers and its potential utility for imaging with (99m)Tc pertechnetate scintigraphy and ¹²4I positron emission tomography (PET). METHODS: GLV-1 h153 was tested against five human gastric cancer cell lines using cytotoxicity and standard viral plaque assays. In vivo, subcutaneous flank tumors were generated in nude mice with human gastric cancer cells, MKN-74. Tumors were subsequently injected with either GLV-1 h153 or PBS and followed for tumor growth. (99m)Tc pertechnetate scintigraphy and ¹²4I microPET imaging were performed. RESULTS: GFP expression, a surrogate for viral infectivity, confirmed viral infection by 24 hours. At a multiplicity of infection (MOI) of 1, GLV-1 h153 achieved > 90% cytotoxicity in MNK-74, OCUM-2MD3, and AGS over 9 days, and >70% cytotoxicity in MNK- 45 and TMK-1. In vivo, GLV-1 h153 was effective in treating xenografts (p < 0.001) after 2 weeks of treatment. GLV-1 h153-infected tumors were readily imaged by (99m)Tc pertechnetate scintigraphy and ¹²4I microPET imaging 2 days after treatment. CONCLUSIONS: GLV-1 h153 is an effective oncolytic virus expressing the hNIS protein that can efficiently regress gastric tumors and allow deep-tissue imaging. These data encourages its continued investigation in clinical settings.

Irreversible electroporation facilitates gene transfer of a GM-CSF plasmid with a local and systemic response.

BACKGROUND: Electroporation uses an electric field to induce pores in the cell membrane that can transfer macromolecules into target cells. Modulation of electrical parameters leads to irreversible electroporation (IRE), which is being developed for tissue ablation. We sought to evaluate whether the application of IRE may induce a lesser electric field in the periphery where reversible electroporation may occur, facilitating gene transfer of a granulocyte macrophage colony-stimulating factor (GM-CSF) plasmid to produce its biologic response. METHODS: Yorkshire pigs underwent laparotomy, and IRE of the liver was performed during hepatic arterial infusion of 1 or 7 mg of a naked human GM-CSF plasmid. The serum, liver, lymph nodes, and bone marrow were harvested for analysis. RESULTS: Human GM-CSF level rose from undetectable to 131 pg/mL in the serum at 24 hours after IRE and plasmid infusion. The liver demonstrated an ablation zone surrounded by an immune infiltrate that had greater macrophage intensity than when treated with IRE or plasmid infusion alone. This dominance of macrophages was dose dependent. Distant effects of GM-CSF were found in the bone marrow, where proliferating myeloid cells increased from 14% to 25%. CONCLUSION: IRE facilitated gene transfer of the GM-CSF plasmid and brought about a local and systemic biologic response. This technique holds potential for tumor eradication and immunotherapy of residual cancer.

Quantification of mitochondrial acetylation dynamics highlights prominent sites of metabolic regulation.

Lysine acetylation is rapidly becoming established as a key post-translational modification for regulating mitochondrial metabolism. Nonetheless, distinguishing regulatory sites from among the thousands identified by mass spectrometry and elucidating how these modifications alter enzyme function remain primary challenges. Here, we performed multiplexed quantitative mass spectrometry to measure changes in the mouse liver mitochondrial acetylproteome in response to acute and chronic alterations in nutritional status, and integrated these data sets with our compendium of predicted Sirt3 targets. These analyses highlight a subset of mitochondrial proteins with dynamic acetylation sites, including acetyl-CoA acetyltransferase 1 (Acat1), an enzyme central to multiple metabolic pathways. We performed in vitro biochemistry and molecular modeling to demonstrate that acetylation of Acat1 decreases its activity by disrupting the binding of coenzyme A. Collectively, our data reveal an important new target of regulatory acetylation and provide a foundation for investigating the role of select mitochondrial protein acetylation sites in mediating acute and chronic metabolic transitions.

Calorie restriction and SIRT3 trigger global reprogramming of the mitochondrial protein acetylome.

Calorie restriction (CR) extends life span in diverse species. Mitochondria play a key role in CR adaptation; however, the molecular details remain elusive. We developed and applied a quantitative mass spectrometry method to probe the liver mitochondrial acetyl-proteome during CR versus control diet in mice that were wild-type or lacked the protein deacetylase SIRT3. Quantification of 3,285 acetylation sites-2,193 from mitochondrial proteins-rendered a comprehensive atlas of the acetyl-proteome and enabled global site-specific, relative acetyl occupancy measurements between all four experimental conditions. Bioinformatic and biochemical analyses provided additional support for the effects of specific acetylation on mitochondrial protein function. Our results (1) reveal widespread reprogramming of mitochondrial protein acetylation in response to CR and SIRT3, (2) identify three biochemically distinct classes of acetylation sites, and (3) provide evidence that SIRT3 is a prominent regulator in CR adaptation by coordinately deacetylating proteins involved in diverse pathways of metabolism and mitochondrial maintenance.

A quantitative map of the liver mitochondrial phosphoproteome reveals posttranslational control of ketogenesis.

Mitochondria are dynamic organelles that play a central role in a diverse array of metabolic processes. Elucidating mitochondrial adaptations to changing metabolic demands and the pathogenic alterations that underlie metabolic disorders represent principal challenges in cell biology. Here, we performed multiplexed quantitative mass spectrometry-based proteomics to chart the remodeling of the mouse liver mitochondrial proteome and phosphoproteome during both acute and chronic physiological transformations in more than 50 mice. Our analyses reveal that reversible phosphorylation is widespread in mitochondria, and is a key mechanism for regulating ketogenesis during the onset of obesity and type 2 diabetes. Specifically, we have demonstrated that phosphorylation of a conserved serine on Hmgcs2 (S456) significantly enhances its catalytic activity in response to increased ketogenic demand. Collectively, our work describes the plasticity of this organelle at high resolution and provides a framework for investigating the roles of proteome restructuring and reversible phosphorylation in mitochondrial adaptation.