Digital Commons Network^™

Endogenous And Combination Retinoids Are Active In Myelomonocytic Leukemias, Orsola Di Martino, Haixia Niu, Gayla Hadwiger, Heikki Kuusanmaki, Margaret A. Ferris, Anh Vu, Jeremy Beales, Carl Wagner, María P. Menéndez-Gutiérrez, Mercedes Ricote, Caroline Heckman, John S. Welch

Open Access Publications

Retinoid therapy transformed response and survival outcomes in acute promyelocytic leukemia (APL), but has demonstrated only modest activity in non-APL forms of acute myeloid leukemia (AML). The presence of natural retinoids in vivo could influence the efficacy of pharmacologic agonists and antagonists. We found that natural RXRA ligands, but not RARA ligands, were present in murine MLL-AF9-derived myelomonocytic leukemias in vivo and that the concurrent presence of receptors and ligands acted as tumor suppressors. Pharmacologic retinoid responses could be optimized by concurrent targeting RXR ligands (e.g. bexarotene) and RARA ligands (e.g. all-trans retinoic acid, ATRA), which induced either leukemic maturation …

An Open-Source Device For Measuring Food Intake And Operant Behavior In Rodent Home-Cages, Bridget A. Matikainen-Ankney, Thomas Earnest, Eric Casey, Justin G. Wang, Alex A. Legaria, Kia M. Barclay, Makenzie R. Norris, Yu-Hsuan Chang, Eric Lin, Sineadh M. Conway, Ream Al-Hasani, Jordan G. Mccall, Meaghan C. Creed, Alexxai V. Kravitz, Et Al

Open Access Publications

Feeding is critical for survival, and disruption in the mechanisms that govern food intake underlies disorders such as obesity and anorexia nervosa. It is important to understand both food intake and food motivation to reveal mechanisms underlying feeding disorders. Operant behavioral testing can be used to measure the motivational component to feeding, but most food intake monitoring systems do not measure operant behavior. Here, we present a new solution for monitoring both food intake and motivation in rodent home-cages: the Feeding Experimentation Device version 3 (FED3). FED3 measures food intake and operant behavior in rodent home-cages, enabling longitudinal studies of …

Crosstalk Between Nonclassical Monocytes And Alveolar Macrophages Mediates Transplant Ischemia-Reperfusion Injury Through Classical Monocyte Recruitment, Chitaru Kurihara, Wenjun Li, Daniel Kreisel, Et Al

Open Access Publications

Primary graft dysfunction (PGD) is the predominant cause of early graft loss following lung transplantation. We recently demonstrated that donor pulmonary intravascular nonclassical monocytes (NCM) initiate neutrophil recruitment. Simultaneously, host-origin classical monocytes (CM) permeabilize the vascular endothelium to allow neutrophil extravasation necessary for PGD. Here, we show that a CCL2-CCR2 axis is necessary for CM recruitment. Surprisingly, although intravital imaging and multichannel flow cytometry revealed that depletion of donor NCM abrogated CM recruitment, single cell RNA sequencing identified donor alveolar macrophages (AM) as predominant CCL2 secretors. Unbiased transcriptomic analysis of murine tissues combined with murine KOs and chimeras indicated that …

Laminin Β2 Variants Associated With Isolated Nephropathy That Impact Matrix Regulation, Yamato Kikkawa, Helen Liapis, Jeffrey H. Miner, Et Al.

Open Access Publications

Mutations in LAMB2, encoding laminin β2, cause Pierson syndrome and occasionally milder nephropathy without extrarenal abnormalities. The most deleterious missense mutations that have been identified affect primarily the N-terminus of laminin β2. On the other hand, those associated with isolated nephropathy are distributed across the entire molecule, and variants in the β2 LEa-LF-LEb domains are exclusively found in cases with isolated nephropathy. Here we report the clinical features of mild isolated nephropathy associated with 3 LAMB2 variants in the LEa-LF-LEb domains (p.R469Q, p.G699R, and p.R1078C) and their biochemical characterization. Although Pierson syndrome missense mutations often inhibit laminin β2 secretion, the …

Cryo-Em Structure Of The Rous Sarcoma Virus Octameric Cleaved Synaptic Complex Intasome, Krishan K Pandey, Sibes Bera, Ke Shi, Michael J Rau, Amarachi V Oleru, James A J Fitzpatrick, Alan N Engelman, Hideki Aihara, Duane P Grandgenett

Open Access Publications

Despite conserved catalytic integration mechanisms, retroviral intasomes composed of integrase (IN) and viral DNA possess diverse structures with variable numbers of IN subunits. To investigate intasome assembly mechanisms, we employed the Rous sarcoma virus (RSV) IN dimer that assembles a precursor tetrameric structure in transit to the mature octameric intasome. We determined the structure of RSV octameric intasome stabilized by a HIV-1 IN strand transfer inhibitor using single particle cryo-electron microscopy. The structure revealed significant flexibility of the two non-catalytic distal IN dimers along with previously unrecognized movement of the conserved intasome core, suggesting ordered conformational transitions between intermediates that …

Insulinase-Like Protease 1 Contributes To Macrogamont Formation In Cryptosporidium Parvum, Rui Xu, Yaoyu Feng, Lihua Xiao, L David Sibley

Open Access Publications

The apicomplexan parasite

The Transcription Factor Pdr802 Regulates Titan Cell Formation And Pathogenicity Of Cryptococcus Neoformans, Julia C V Reuwsaat, Daniel P Agustinho, Heryk Motta, Andrew L Chang, Holly Brown, Michael R Brent, Livia Kmetzsch, Tamara L Doering

Open Access Publications

No abstract provided.

Microbiota Functional Activity Biosensors For Characterizing Nutrient Metabolism In Vivo, Darryl A. Wesener, Zachary W. Beller, Samantha L. Peters, Amir Rajabi, Gianluca Dimartino, Richard J. Giannone, Robert L. Hettich, Jeffrey I. Gordon

Open Access Publications

Methods for measuring gut microbiota biochemical activities in vivo are needed to characterize its functional states in health and disease. To illustrate one approach, an arabinan-containing polysaccharide was isolated from pea fiber, its structure defined, and forward genetic and proteomic analyses used to compare its effects, versus unfractionated pea fiber and sugar beet arabinan, on a human gut bacterial strain consortium in gnotobiotic mice. We produced 'Microbiota Functional Activity Biosensors' (MFABs) consisting of glycans covalently linked to the surface of fluorescent paramagnetic microscopic glass beads. Three MFABs, each containing a unique glycan/fluorophore combination, were simultaneously orally gavaged into gnotobiotic mice, …

Complex Consequences Of Cantu Syndrome Sur2 Variant R1154q In Genetically Modified Mice, Haixia Zhang, Alex Hanson, Tobias Scherf De Almeida, Christopher Emfinger, Conor Mcclenaghan, Theresa Harter, Zihan Yan, Paige E Cooper, G Schuyler Brown, Eric C Arakel, Robert P Mecham, Atilla Kovacs, Carmen M Halabi, Blanche Schwappach, Maria S Remedi, Colin G Nichols

Open Access Publications

Cantu syndrome (CS) is caused by gain-of-function (GOF) mutations in pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunits, the most common mutations being SUR2[R1154Q] and SUR2[R1154W], carried by approximately 30% of patients. We used CRISPR/Cas9 genome engineering to introduce the equivalent of the human SUR2[R1154Q] mutation into the mouse ABCC9 gene. Along with minimal CS disease features, R1154Q cardiomyocytes and vascular smooth muscle showed much lower KATP current density and pinacidil activation than WT cells. Almost complete loss of SUR2-dependent protein and KATP in homozygous R1154Q ventricles revealed underlying diazoxide-sensitive SUR1-dependent KATP channel activity. Surprisingly, sequencing …

Parabrachial Opioidergic Projections To Preoptic Hypothalamus Mediate Behavioral And Physiological Thermal Defenses, Aaron J. Norris, Jordan R. Shaker, Aaron L. Cone, Imeh B. Ndiokho, Michael R. Bruchas

Open Access Publications

Maintaining stable body temperature through environmental thermal stressors requires detection of temperature changes, relay of information, and coordination of physiological and behavioral responses. Studies have implicated areas in the preoptic area of the hypothalamus (POA) and the parabrachial nucleus (PBN) as nodes in the thermosensory neural circuitry and indicate that the opioid system within the POA is vital in regulating body temperature. In the present study we identify neurons projecting to the POA from PBN expressing the opioid peptides dynorphin and enkephalin. Using mouse models, we determine that warm-activated PBN neuronal populations overlap with both prodynorphin (Pdyn) and proenkephalin (Penk) …

Bidirectional Regulation Of Glial Potassium Buffering - Glioprotection Versus Neuroprotection, Hailun Li, Lorenzo Lones, Aaron Diantonio

Open Access Publications

Glia modulate neuronal excitability and seizure sensitivity by maintaining potassium and water homeostasis. A salt inducible kinase 3 (SIK3)-regulated gene expression program controls the glial capacity to buffer K

Norovirus Evolution In Immunodeficient Mice Reveals Potentiated Pathogenicity Via A Single Nucleotide Change In The Viral Capsid, Forrest C Walker, Ebrahim Hassan, Stefan T. Peterson, Rachel Rodgers, Lawrence A. Schriefer, Cassandra E. Thompson, Yuhao Li, Gowri Kalugotla, Carla Blum-Johnston, Dylan Lawrence, Broc T. Mccune, Vincent R. Graziano, Larissa Lushniak, Sanghyun Lee, Alexa N. Roth, Stephanie M. Karst, Timothy J. Nice, Jonathan J. Miner, Craig B. Wilen, Megan T. Baldridge

Open Access Publications

Interferons (IFNs) are key controllers of viral replication, with intact IFN responses suppressing virus growth and spread. Using the murine norovirus (MNoV) system, we show that IFNs exert selective pressure to limit the pathogenic evolutionary potential of this enteric virus. In animals lacking type I IFN signaling, the nonlethal MNoV strain CR6 rapidly acquired enhanced virulence via conversion of a single nucleotide. This nucleotide change resulted in amino acid substitution F514I in the viral capsid, which led to >10,000-fold higher replication in systemic organs including the brain. Pathogenicity was mediated by enhanced recruitment and infection of intestinal myeloid cells and …

Increased Functional Coupling Between Vta And Hippocampus During Rest In First-Episode Psychosis, David F Gregory, Jane M Rothrock, Maria Jalbrzikowski, William Foran, David F Montez, Beatriz Luna, Vishnu P Murty

Open Access Publications

Animal models suggest that interactions between the hippocampus and ventral tegmental area (VTA) underlie the onset and etiology of psychosis. While a large body of research has separately characterized alterations in hippocampal and VTA function in psychosis, alterations across the VTA and hippocampus have not been characterized in first-episode psychosis (FEP). As the phase of psychosis most proximal to conversion, studies specifically focused on FEP are valuable to psychosis research. Here, we characterize alterations in VTA-hippocampal interactions across male and female human participants experiencing their first episode of psychosis using resting state functional magnetic resonance imaging (rsfMRI). In comparison to …

Defining Phenotypic And Functional Heterogeneity Of Glioblastoma Stem Cells By Mass Cytometry, Luciano Galdieri, Arijita Jash, Olga Malkova, Diane D Mao, Patrick Desouza, Yunli E Chu, Amber Salter, Jian L Campian, Kristen M Naegle, Cameron W Brennan, Hiroaki Wakimoto, Stephen T Oh, Albert H Kim, Milan G Chheda

Open Access Publications

Most patients with glioblastoma (GBM) die within 2 years. A major therapeutic goal is to target GBM stem cells (GSCs), a subpopulation of cells that contribute to treatment resistance and recurrence. Since their discovery in 2003, GSCs have been isolated using single-surface markers, such as CD15, CD44, CD133, and α6 integrin. It remains unknown how these single-surface marker-defined GSC populations compare with each other in terms of signaling and function and whether expression of different combinations of these markers is associated with different functional capacity. Using mass cytometry and fresh operating room specimens, we found 15 distinct GSC subpopulations in …

Epithelial Il-33 Appropriates Exosome Trafficking For Secretion In Chronic Airway Disease, Ella Katz-Kiriakos, Deborah F Steinberg, Colin E Kluender, Omar A Osorio, Catie Newsom-Stewart, Arjun Baronia, Derek E Byers, Michael J Holtzman, Dawn Katafiasz, Kristina L Bailey, Steven L Brody, Mark J Miller, Jennifer Alexander-Brett

Open Access Publications

IL-33 is a key mediator of chronic airway disease driven by type 2 immune pathways, yet the nonclassical secretory mechanism for this cytokine remains undefined. We performed a comprehensive analysis in human airway epithelial cells, which revealed that tonic IL-33 secretion is dependent on the ceramide biosynthetic enzyme neutral sphingomyelinase 2 (nSMase2). IL-33 is cosecreted with exosomes by the nSMase2-regulated multivesicular endosome (MVE) pathway as surface-bound cargo. In support of these findings, human chronic obstructive pulmonary disease (COPD) specimens exhibited increased epithelial expression of the abundantly secreted IL33Δ34 isoform and augmented nSMase2 expression compared with non-COPD specimens. Using an Alternaria-induced …

Pharmacokinetic And Pharmacodynamic Profiling Of Minocycline For Injection Following A Single Infusion In Critically Ill Adults In A Phase Iv Open-Label Multicenter Study (Acumin), Thomas P Lodise, Yasir Hamad, Et Al

Open Access Publications

Intravenous (i.v.) minocycline is increasingly used to treat infections caused by multidrug-resistant (MDR)

Cancer-Associated Exportin-6 Upregulation Inhibits The Transcriptionally Repressive And Anticancer Effects Of Nuclear Profilin-1, Cuige Zhu, Sun-Joong Kim, Arshag Mooradian, Faliang Wang, Ziqian Li, Sean Holohan, Patrick L Collins, Keren Wang, Zhanfang Guo, Jeremy Hoog, Cynthia X Ma, Eugene M Oltz, Jason M Held, Jieya Shao

Open Access Publications

Aberrant expression of nuclear transporters and deregulated subcellular localization of their cargo proteins are emerging as drivers and therapeutic targets of cancer. Here, we present evidence that the nuclear exporter exportin-6 and its cargo profilin-1 constitute a functionally important and frequently deregulated axis in cancer. Exportin-6 upregulation occurs in numerous cancer types and is associated with poor patient survival. Reducing exportin-6 level in breast cancer cells triggers antitumor effects by accumulating nuclear profilin-1. Mechanistically, nuclear profilin-1 interacts with eleven-nineteen-leukemia protein (ENL) within the super elongation complex (SEC) and inhibits the ability of the SEC to drive transcription of numerous pro-cancer …

Kmt2c Mutations Enhance Hsc Self-Renewal Capacity And Convey A Selective Advantage After Chemotherapy, Ran Chen, Theresa Okeyo-Owuor, Riddhi M Patel, Emily B Casey, Andrew S Cluster, Wei Yang, Jeffrey A Magee

Open Access Publications

The myeloid tumor suppressor KMT2C is recurrently deleted in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), particularly therapy-related MDS/AML (t-MDS/t-AML), as part of larger chromosome 7 deletions. Here, we show that KMT2C deletions convey a selective advantage to hematopoietic stem cells (HSCs) after chemotherapy treatment that may precipitate t-MDS/t-AML. Kmt2c deletions markedly enhance murine HSC self-renewal capacity without altering proliferation rates. Haploid Kmt2c deletions convey a selective advantage only when HSCs are driven into cycle by a strong proliferative stimulus, such as chemotherapy. Cycling Kmt2c-deficient HSCs fail to differentiate appropriately, particularly in response to interleukin-1. Kmt2c deletions mitigate histone …

Transcriptomic And Functional Analyses Of Mitochondrial Dysfunction In Pressure Overload-Induced Right Ventricular Failure, Hyuntae V Hwang, Nefthi Sandeep, Ramesh V Nair, Dong-Qing Hu, Mingming Zhao, Ingrid S Lan, Giovanni Fajardo, Scot J Matkovich, Daniel Bernstein, Sushma Reddy

Open Access Publications

Background In complex congenital heart disease patients such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload, leading to RV hypertrophy and eventually RV failure. The mechanisms that promote the transition from stable RV hypertrophy to RV failure are unknown. We evaluated the role of mitochondrial bioenergetics in the development of RV failure. Methods and Results We created a murine model of RV pressure overload by pulmonary artery banding and compared with sham-operated controls. Gene expression by RNA-sequencing, oxidative stress, mitochondrial respiration, dynamics, and structure were assessed in pressure overload-induced RV failure. RV failure …

Trim67 Regulates Exocytic Mode And Neuronal Morphogenesis Via Snap47, Fabio L Urbina, Shalini Menon, Dennis Goldfarb, Reginald Edwards, M Ben Major, Patrick Brennwald, Stephanie L Gupton

Open Access Publications

Neuronal morphogenesis involves dramatic plasma membrane expansion, fueled by soluble N-ethylmaleimide-sensitive factor attachment protein eceptors (SNARE)-mediated exocytosis. Distinct fusion modes described at synapses include full-vesicle fusion (FVF) and kiss-and-run fusion (KNR). During FVF, lumenal cargo is secreted and vesicle membrane incorporates into the plasma membrane. During KNR, a transient fusion pore secretes cargo but closes without membrane addition. In contrast, fusion modes are not described in developing neurons. Here, we resolve individual exocytic events in developing murine cortical neurons and use classification tools to identify four distinguishable fusion modes: two FVF-like modes that insert membrane material and two KNR-like modes …

Controlling Opioid Receptor Functional Selectivity By Targeting Distinct Subpockets Of The Orthosteric Site, Rajendra Uprety, Tao Che, Balázs R. Varga, Abdelfattah Faouzi, Sarah M. Bernhard, Susruta Majumdar, Et Al

Open Access Publications

Controlling receptor functional selectivity profiles for opioid receptors is a promising approach for discovering safer analgesics; however, the structural determinants conferring functional selectivity are not well understood. Here, we used crystal structures of opioid receptors, including the recently solved active state kappa opioid complex with

Gut Helicobacter Presentation By Multiple Dendritic Cell Subsets Enables Context-Specific Regulatory T Cell Generation, Emilie V. Russler-Germain, Jaeu Yi, Shannon Young, Katherine Nutsch, Harikesh S. Wong, Teresa L. Ai, Jiani N. Chai, Vivek Durai, Daniel H. Kaplan, Ronald N. Germain, Kenneth M. Murphy, Chyi-Song Hsieh

Open Access Publications

Generation of tolerogenic peripheral regulatory T (pTreg) cells is commonly thought to involve CD103

Enhanced Efficacy And Increased Long-Term Toxicity Of Cns-Directed, Aav-Based Combination Therapy For Krabbe Disease, Yedda Li, Christopher A Miller, Lauren K Shea, Xuntian Jiang, Miguel A Guzman, Randy J Chandler, Sai M Ramakrishnan, Stephanie N Smith, Charles P Venditti, Carole A Vogler, Daniel S Ory, Timothy J Ley, Mark S Sands

Open Access Publications

Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a demyelinating disease caused by the deficiency of the lysosomal enzyme galactosylceramidase (GALC) and the progressive accumulation of the toxic metabolite psychosine. We showed previously that central nervous system (CNS)-directed, adeno-associated virus (AAV)2/5-mediated gene therapy synergized with bone marrow transplantation and substrate reduction therapy (SRT) to greatly increase therapeutic efficacy in the murine model of Krabbe disease (Twitcher). However, motor deficits remained largely refractory to treatment. In the current study, we replaced AAV2/5 with an AAV2/9 vector. This single change significantly improved several endpoints primarily associated with motor function. However, nearly all …

Satb2 Induction Of A Neural Crest Mesenchyme-Like Program Drives Melanoma Invasion And Drug Resistance, Maurizio Fazio, Charles K. Kaufman, Et Al

Open Access Publications

Recent genomic and scRNA-seq analyses of melanoma demonstrated a lack of recurrent genetic drivers of metastasis, while identifying common transcriptional states correlating with invasion or drug resistance. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:

Capsule Carbohydrate Structure Determines Virulence In Acinetobacter Baumannii, Yuli Talyansky, Travis B. Nielsen, Jun Yan, Ulrike Carlino-Macdonald, Gisela Di Venanzio, Somnath Chakravorty, Amber Ulhaq, Mario F. Feldman, Thomas A. Russo, Evgeny Vinogradov, Brian Luna, Meredith S. Wright, Mark D. Adams, Brad Spellberg

Open Access Publications

Acinetobacter baumannii is a highly antibiotic-resistant bacterial pathogen for which novel therapeutic approaches are needed. Unfortunately, the drivers of virulence in A. baumannii remain uncertain. By comparing genomes among a panel of A. baumannii strains we identified a specific gene variation in the capsule locus that correlated with altered virulence. While less virulent strains possessed the intact gene gtr6, a hypervirulent clinical isolate contained a spontaneous transposon insertion in the same gene, resulting in the loss of a branchpoint in capsular carbohydrate structure. By constructing isogenic gtr6 mutants, we confirmed that gtr6-disrupted strains were protected from phagocytosis in vitro and …

Evaluating Cognitive Relationships With Resting-State And Task-Driven Blood Oxygen Level-Dependent Variability, Peter R Millar, Beau M Ances, Brian A Gordon, Tammie L S Benzinger, John C Morris, David A Balota

Open Access Publications

Recent functional magnetic resonance imaging studies have reported that moment-to-moment variability in the blood oxygen level-dependent (BOLD) signal is positively associated with task performance and, thus, may reflect a behaviorally sensitive signal. However, it is not clear whether estimates of resting-state and task-driven BOLD variability are differentially related to cognition, as they may be driven by distinct sources of variance in the BOLD signal. Moreover, other studies have suggested that age differences in resting-state BOLD variability may be particularly sensitive to individual differences in cardiovascular, rather than neural, factors. In this study, we tested relationships between measures of behavioral task …

Global, Cell Non-Autonomous Gene Regulation Drives Individual Lifespan Among Isogenic C. Elegans, Holly E. Kinser, Matthew C. Mosley, Isaac B. Plutzer, Zachary Pincus

Open Access Publications

Across species, lifespan is highly variable among individuals within a population. Even genetically identical

Progress Towards Onchocerciasis Elimination In Côte D'Ivoire: A Geospatial Modelling Study, Obiora A. Eneanya, Benjamin G. Koudou, Meite Aboulaye, Aba Ange Elvis, Yeo Souleymane, Marie-Madeleine Kouakou, Gary J. Weil, Peter U. Fischer

Open Access Publications

BACKGROUND: Côte d'Ivoire has had 45 years of intervention for onchocerciasis by vector control (from 1975 to 1991), ivermectin mass drug administration (MDA) (from 1992 to 1994) and community directed treatment with ivermectin (CDTi) from 1995 to the present. We modeled onchocerciasis endemicity during two time periods that correspond to the scale up of vector control and ivermectin distribution, respectively. This analysis illustrates progress towards elimination during these periods, and it has identified potential hotspots areas that are at risk for ongoing transmission.

METHODS AND FINDINGS: The analysis used Ministry of Health skin snip microfilaria (MF) prevalence and intensity data …

Nanoparticle T-Cell Engagers As A Modular Platform For Cancer Immunotherapy, Kinan Alhallak, Jennifer Sun, Katherine Wasden, Nicole Guenthner, Julie O'Neal, Barbara Muz, Justin King, Daniel Kohnen, Ravi Vij, Samuel Achilefu, John F Dipersio, Abdel Kareem Azab

Open Access Publications

T-cell-based immunotherapy, such as CAR-T cells and bispecific T-cell engagers (BiTEs), has shown promising clinical outcomes in many cancers; however, these therapies have significant limitations, such as poor pharmacokinetics and the ability to target only one antigen on the cancer cells. In multiclonal diseases, these therapies confer the development of antigen-less clones, causing tumor escape and relapse. In this study, we developed nanoparticle-based bispecific T-cell engagers (nanoBiTEs), which are liposomes decorated with anti-CD3 monoclonal antibodies (mAbs) targeting T cells, and mAbs targeting the cancer antigen. We also developed a nanoparticle that targets multiple cancer antigens by conjugating multiple mAbs against …

Short-Term Effects Of Appropriate Empirical Antimicrobial Treatment With Ceftolozane/Tazobactam In A Swine Model Of Nosocomial Pneumonia, Ana Motos, Marin Kollef, Et Al

Open Access Publications

The rising frequency of multidrug-resistant and extensively drug-resistant (MDR/XDR) pathogens is making more frequent the inappropriate empirical antimicrobial therapy (IEAT) in nosocomial pneumonia, which is associated with increased mortality. We aim to determine the short-term benefits of appropriate empirical antimicrobial treatment (AEAT) with ceftolozane/tazobactam (C/T) compared with IEAT with piperacillin/tazobactam (TZP) in MDR