MAP kinase phosphatase-1 inhibition of p38α within lung myofibroblasts is essential for spontaneous fibrosis resolution.

Fibrosis following tissue injury is distinguished from normal repair by the accumulation of pathogenic and apoptosis-resistant myofibroblasts (MFs), which arise primarily by differentiation from resident fibroblasts. Endogenous molecular brakes that promote MF dedifferentiation and clearance during spontaneous resolution of experimental lung fibrosis may provide insights that could inform and improve treatment of progressive pulmonary fibrosis in patients. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP1) influences cellular phenotype and fate through precise and timely regulation of MAPK activity within various cell types and tissues, yet its role in lung fibroblasts and pulmonary fibrosis has not been explored. Utilizing gain- and loss-of-function studies, we found that MKP1 promoted lung MF dedifferentiation and restored their sensitivity to apoptosis - effects determined to be mainly dependent upon its dephosphorylation of p38α MAPK (p38α). Fibroblast-specific deletion of MKP1 following peak bleomycin-induced lung fibrosis largely abrogated its subsequent spontaneous resolution. Such resolution was restored by treating these transgenic mice with the p38α inhibitor VX-702. We conclude that MKP1 is a critical antifibrotic brake whose inhibition of pathogenic p38α in lung fibroblasts is necessary for fibrosis resolution following lung injury.

Guidelines in Practice: Manual High-Level Disinfection.

There are several steps involved when performing high-level disinfection (HLD) of semicritical devices. The recently updated AORN "Guideline for manual high-level disinfection" provides perioperative nurses with evidence-based best practices for performing safe and effective HLD of reusable semicritical items. The guideline also addresses preventing injury to patients and health care workers associated with the handling of high-level disinfectants. This article provides an overview of the guideline and discusses recommendations for selection of a processing method, sterile processing areas, preparation of items for HLD, preparation of high-level disinfectants, manual HLD, drying and storage of items after HLD, and processing records. It also includes a scenario that illustrates specific concerns related to performing quality tests on high-level disinfectant solutions. Perioperative nurses should review the guideline in its entirety and apply the recommendations when performing manual HLD.

GTP Signaling Links Metabolism, DNA Repair, and Responses to Genotoxic Stress.

How cell metabolism regulates DNA repair is incompletely understood. Here, we define a GTP-mediated signaling cascade that links metabolism to DNA repair and has significant therapeutic implications. GTP, but not other nucleotides, regulates the activity of Rac1, a guanine nucleotide-binding protein, which promotes the dephosphorylation of serine 323 on Abl-interactor 1 (Abi-1) by protein phosphatase 5 (PP5). Dephosphorylated Abi-1, a protein previously not known to activate DNA repair, promotes nonhomologous end joining. In patients and mouse models of glioblastoma, Rac1 and dephosphorylated Abi-1 mediate DNA repair and resistance to standard-of-care genotoxic treatments. The GTP-Rac1-PP5-Abi-1 signaling axis is not limited to brain cancer, as GTP supplementation promotes DNA repair and Abi-1-S323 dephosphorylation in nonmalignant cells and protects mouse tissues from genotoxic insult. This unexpected ability of GTP to regulate DNA repair independently of deoxynucleotide pools has important implications for normal physiology and cancer treatment. SIGNIFICANCE: A newly described GTP-dependent signaling axis is an unexpected link between nucleotide metabolism and DNA repair. Disrupting this pathway can overcome cancer resistance to genotoxic therapy while augmenting it can mitigate genotoxic injury of normal tissues. This article is featured in Selected Articles from This Issue, p. 5.

Guidelines in Practice: Design and Maintenance of the Surgical Suite.

Hospital construction and renovation is an ongoing occurrence in the health care setting. The recently updated AORN "Guideline for design and maintenance of the surgical suite" provides perioperative nurses with information on the layout design and maintenance of perioperative spaces; safety measures to use during construction and renovation; monitoring and maintenance of the heating, ventilation, and air conditioning; and how to respond to unintended utility failures. This article provides an overview of the guideline and discusses recommendations for the interdisciplinary team, planning and designing the surgical suite, construction-related environmental contamination, ORs, and OR maintenance. It also includes a scenario describing specific concerns associated with the construction of an additional OR. Perioperative nurses should review the guideline in its entirety and apply the recommendations when participating in perioperative construction and renovation projects.

Guidelines in Practice: Medication Safety.

Medication errors are preventable events that health care professionals, consumers, and medication manufacturers report to the US Food and Drug Administration. The agency receives more than 100,000 medication-related reports each year, and some reports involve patient death. A variety of sources provide perioperative nurses with information on interventions and practices to prevent medication errors, including the US Pharmacopeia, The Joint Commission, medication manufacturers' instructions for use, safety data sheets, and the updated AORN "Guideline for medication safety." This article provides an overview of the guideline and discusses recommendations for organizational oversight, procurement and storage, retrieval and preparation, labeling, and hazardous medications. It also includes a scenario that illustrates perioperative nursing practices for administering an antineoplastic medication intraoperatively. Perioperative nurses should review the guideline in its entirety and implement recommendations in operative or procedural settings.

Guidelines in Practice: Prevention of Venous Thromboembolism.

Venous thromboembolism (VTE), a condition involving deep vein thrombosis and embolism, can cause death when left untreated. Hospitalized patients and those who have recently undergone surgery or have a cancer diagnosis are at increased risk for VTE development. The updated AORN "Guideline for prevention of venous thromboembolism" provides perioperative nurses with a variety of evidence-based recommendations associated with the topic. This article provides an overview of the guideline and discusses recommendations for a VTE protocol, VTE and bleeding risk assessments, pharmacologic and mechanical VTE prophylaxis, postoperative ambulation, and patient and family education. It also includes a scenario that illustrates the importance of the VTE assessment and the use of mechanical prophylaxis for high-risk patients undergoing operative or other invasive procedures. Perioperative nurses should review the guideline in its entirety and implement recommendations in operative and procedural settings.

Guidelines in Practice: Minimally Invasive Surgery.

During minimally invasive surgery (MIS), surgeons create small and percutaneous incisions to access internal structures without open surgical incisions. Some MIS equipment is complex and challenging for perioperative nurses to manage. Patients also can experience life-threatening complications during MIS procedures. The updated AORN "Guideline for minimally invasive surgery" provides recommendations that perioperative nurses can use when caring for patients undergoing MIS procedures. This article provides an overview of the guideline and discusses several recommendations, including creating a safe environment in which to perform MIS procedures; using gas distension media, irrigation and fluid distension media, and computer-assisted navigation and robotics; and performing intraoperative magnetic resonance imaging in a hybrid OR. It also includes a scenario describing care of a patient undergoing a hysteroscopy. Perioperative nurses who care for patients undergoing MIS procedures should review the guideline in its entirety and apply the recommendations as applicable in their practice.

Guidelines in Practice: Processing Flexible Endoscopes.

Flexible endoscopes allow surgeons and proceduralists to view patients' internal organs through small incisions or natural orifices. These devices may be difficult to clean and dry adequately, and the formation of biofilm can further complicate effective cleaning. The updated AORN "Guideline for processing flexible endoscopes" provides perioperative personnel with evidence-based best practice recommendations on a variety of concepts associated with this topic. This article provides an overview of the guideline and discusses recommendations for point-of-use treatment, transport, cleaning (including verification and drying), and storage of flexible endoscopes. It also includes a scenario that illustrates the importance of adequately drying and storing flexible endoscopes. When processing flexible endoscopes, personnel should adhere to the endoscope and processing equipment manufacturers' instructions for use. Perioperative nurses should review the guideline in its entirety and implement recommendations in practice settings where flexible endoscopes are used.

Guidelines in Practice: Hand Hygiene.

Effective hand hygiene is an important part of infection prevention, especially in perioperative areas. The revised AORN "Guideline for hand hygiene" provides perioperative personnel with evidence-based practice recommendations for hand hygiene. This article presents an overview of the guideline and discusses specific recommendations for maintaining appropriate fingernail and hand condition; wearing or removing hand and wrist jewelry; performing general hand hygiene; performing surgical hand antisepsis with a traditional hand scrub or surgical hand rub; selecting sinks, faucets, and drains to avoid hand contamination; and implementing quality activities to enhance hand hygiene compliance. It also includes a scenario illustrating how nurses can use the guideline to mitigate hand dermatitis associated with surgical hand antisepsis. Perioperative nurses should review the revised guideline in its entirety and apply the recommendations as applicable for their practice.

Guidelines in Practice: Prevention of Perioperative Pressure Injury.

Immobility and lack of sensation during perioperative procedures increase the risk of patients developing pressure injuries (PIs). Such injuries can cause pain and result in serious infections, thereby leading to increased health care costs. The recently developed AORN "Guideline for prevention of perioperative pressure injury" provides perioperative nurses and leaders with applicable recommendations for preventing these injuries. In addition to a brief overview of a health care facility's interdisciplinary perioperative PI prevention program, this article discusses a variety of concepts related to PI prevention, including prophylactic materials, intraoperative considerations, hand-over communication, pediatric patient concerns, policies and procedures, quality management, and education. It also provides a pediatric patient-specific scenario that illustrates the implementation of the described recommendations. Perioperative nurses and leaders should review the guideline in its entirety and apply the recommendations to prevent PIs as appropriate for their facility and patient population.

Guidelines in Practice: Positioning the Patient.

Positioning the patient is an important perioperative task; the recently updated AORN "Guideline for positioning the patient" provides perioperative personnel with background information and evidence-based best practices for perioperative patient positioning and focuses on maintaining patient and staff member safety. The revised guideline includes recommendations for placing patients safely in a variety of positions and avoiding positioning injuries, such as postoperative vision loss. This article provides an overview of positioning recommendations for assessing patients' risk for injury, implementing safe positioning practices, placing patients in the Trendelenburg position, and preventing intraocular injuries. It also includes a patient-focused scenario on preventing adverse events associated with the Trendelenburg position that aligns with information discussed in the article. Perioperative nurses should review the guideline in its entirety and implement appropriate recommendations for positioning patients during procedures.

GTP signaling links metabolism, DNA repair, and responses to genotoxic stress.

How cell metabolism regulates DNA repair is incompletely understood. Here, we define a GTP-mediated signaling cascade that links metabolism to DNA repair and has significant therapeutic implications. GTP, but not other nucleotides, regulates the activity of Rac1, a G protein, that promotes the dephosphorylation of serine 323 on Abl-interactor 1 (Abi-1) by protein phosphatase 5 (PP5). Dephosphorylated Abi-1, a protein previously not known to activate DNA repair, promotes non-homologous end joining. In patients and mouse models of glioblastoma, Rac1 and dephosphorylated Abi-1 mediate DNA repair and resistance to standard of care genotoxic treatments. The GTP-Rac1-PP5-Abi-1 signaling axis is not limited to brain cancer, as GTP supplementation promotes DNA repair and Abi-1-S323 dephosphorylation in non-malignant cells and protects mouse tissues from genotoxic insult. This unexpected ability of GTP to regulate DNA repair independently of deoxynucleotide pools has important implications for normal physiology and cancer treatment.

KLF4 is a therapeutically tractable brake on fibroblast activation that promotes resolution of pulmonary fibrosis.

There is a paucity of information about potential molecular brakes on the activation of fibroblasts that drive tissue fibrosis. The transcription factor Krüppel-like factor 4 (KLF4) is best known as a determinant of cell stemness and a tumor suppressor. We found that its expression was diminished in fibroblasts from fibrotic lung. Gain- and loss-of-function studies showed that KLF4 inhibited fibroblast proliferation, collagen synthesis, and differentiation to myofibroblasts, while restoring their sensitivity to apoptosis. Conditional deletion of KLF4 from fibroblasts potentiated the peak degree of pulmonary fibrosis and abrogated the subsequent spontaneous resolution in a model of transient fibrosis. A small molecule inducer of KLF4 was able to restore its expression in fibrotic fibroblasts and elicit resolution in an experimental model characterized by more clinically relevant persistent pulmonary fibrosis. These data identify KLF4 as a pivotal brake on fibroblast activation whose induction represents a therapeutic approach in fibrosis of the lung and perhaps other organs.

ATP citrate lyase links increases in glycolysis to diminished release of vesicular suppressor of cytokine signaling 3 by alveolar macrophages.

Extracellular vesicles (EVs) are important vectors for intercellular communication. Lung-resident alveolar macrophages (AMs) tonically secrete EVs containing suppressor of cytokine signaling 3 (SOCS3), a cytosolic protein that promotes homeostasis in the distal lung via its actions in recipient neighboring epithelial cells. AMs are metabolically distinct and exhibit low levels of glycolysis at steady state. To our knowledge, whether cellular metabolism influences the packaging and release of an EV cargo molecule has never been explored in any cellular context. Here, we report that increases in glycolysis following in vitro exposure of AMs to the growth and activating factor granulocyte-macrophage colony-stimulating factor inhibit the release of vesicular SOCS3 by primary AMs. Glycolytically diminished SOCS3 secretion requires export of citrate from the mitochondria to the cytosol and its subsequent conversion to acetyl-CoA by ATP citrate lyase. Our data for the first time implicate perturbations in intracellular metabolites in the regulation of vesicular cargo packaging and secretion.

Bortezomib Inhibits Lung Fibrosis and Fibroblast Activation without Proteasome Inhibition.

The U.S. Food and Drug Administration-approved proteasomal inhibitor bortezomib (BTZ) has attracted interest for its potential antifibrotic actions. However, neither its in vivo efficacy in lung fibrosis nor its dependence on proteasome inhibition has been conclusively defined. In this study, we assessed the therapeutic efficacy of BTZ in a mouse model of pulmonary fibrosis, developed an in vitro protocol to define its actions on diverse fibroblast activation parameters, determined its reliance on proteasome inhibition for these actions in vivo and in vitro, and explored alternative mechanisms of action. The therapeutic administration of BTZ diminished the severity of pulmonary fibrosis without reducing proteasome activity in the lung. In experiments designed to mimic this lack of proteasome inhibition in vitro, BTZ reduced fibroblast proliferation, differentiation into myofibroblasts, and collagen synthesis. It promoted dedifferentiation of myofibroblasts and overcame their characteristic resistance to apoptosis. Mechanistically, BTZ inhibited kinases important for fibroblast activation while inducing the expression of DUSP1 (dual-specificity protein phosphatase 1), and knockdown of DUSP1 abolished its antifibrotic actions in fibroblasts. Collectively, these findings suggest that BTZ exhibits a multidimensional profile of robust inhibitory actions on lung fibroblasts as well as antifibrotic actions in vivo. Unexpectedly, these actions appear to be independent of proteasome inhibition, instead attributable to the induction of DUSP1.

PGE2 accounts for bidirectional changes in alveolar macrophage self-renewal with aging and smoking.

Alveolar macrophages (AMs) are resident immune cells of the lung that are critical for host defense. AMs are capable of proliferative renewal, yet their numbers are known to decrease with aging and increase with cigarette smoking. The mechanism by which AM proliferation is physiologically restrained, and whether dysregulation of this brake contributes to altered AM numbers in pathologic circumstances, however, remains unknown. Mice of advanced age exhibited diminished basal AM numbers and contained elevated PGE2 levels in their bronchoalveolar lavage fluid (BALF) as compared with young mice. Exogenous PGE2 inhibited AM proliferation in an E prostanoid receptor 2 (EP2)-cyclic AMP-dependent manner. Furthermore, EP2 knockout (EP2 KO) mice exhibited elevated basal AM numbers, and their AMs resisted the ability of PGE2 and aged BALF to inhibit proliferation. In contrast, increased numbers of AMs in mice exposed to cigarette smoking were associated with reduced PGE2 levels in BALF and were further exaggerated in EP2 KO mice. Collectively, our findings demonstrate that PGE2 functions as a tunable brake on AM numbers under physiologic and pathophysiological conditions.

Alveolar macrophage-derived extracellular vesicles inhibit endosomal fusion of influenza virus.

Alveolar macrophages (AMs) and epithelial cells (ECs) are the lone resident lung cells positioned to respond to pathogens at early stages of infection. Extracellular vesicles (EVs) are important vectors of paracrine signaling implicated in a range of (patho)physiologic contexts. Here we demonstrate that AMs, but not ECs, constitutively secrete paracrine activity localized to EVs which inhibits influenza infection of ECs in vitro and in vivo. AMs exposed to cigarette smoke extract lost the inhibitory activity of their secreted EVs. Influenza strains varied in their susceptibility to inhibition by AM-EVs. Only those exhibiting early endosomal escape and high pH of fusion were inhibited via a reduction in endosomal pH. By contrast, strains exhibiting later endosomal escape and lower fusion pH proved resistant to inhibition. These results extend our understanding of how resident AMs participate in host defense and have broader implications in the defense and treatment of pathogens internalized within endosomes.

Resident alveolar macrophage-derived vesicular SOCS3 dampens allergic airway inflammation.

Resident alveolar macrophages (AMs) suppress allergic inflammation in murine asthma models. Previously we reported that resident AMs can blunt inflammatory signaling in alveolar epithelial cells (ECs) by transcellular delivery of suppressor of cytokine signaling 3 (SOCS3) within extracellular vesicles (EVs). Here we examined the role of vesicular SOCS3 secretion as a mechanism by which AMs restrain allergic inflammatory responses in airway ECs. Bronchoalveolar lavage fluid (BALF) levels of SOCS3 were reduced in asthmatics and in allergen-challenged mice. Ex vivo SOCS3 secretion was reduced in AMs from challenged mice and this defect was mimicked by exposing normal AMs to cytokines associated with allergic inflammation. Both AM-derived EVs and synthetic SOCS3 liposomes inhibited the activation of STAT3 and STAT6 as well as cytokine gene expression in ECs challenged with IL-4/IL-13 and house dust mite (HDM) extract. This suppressive effect of EVs was lost when they were obtained from AMs exposed to allergic inflammation-associated cytokines. Finally, inflammatory cell recruitment and cytokine generation in the lungs of OVA-challenged mice were attenuated by intrapulmonary pretreatment with SOCS3 liposomes. Overall, AM secretion of SOCS3 within EVs serves as a brake on airway EC responses during allergic inflammation, but is impaired in asthma. Synthetic liposomes encapsulating SOCS3 can rescue this defect and may serve as a framework for novel therapeutic approaches targeting airway inflammation.

Transcriptional regulation of the IL-13Rα2 gene in human lung fibroblasts.

Interleukin (IL)-13 is a type 2 cytokine with important roles in allergic diseases, asthma, and tissue fibrosis. Its receptor (R) α1 is primarily responsible for the biological actions of this cytokine, while Rα2 possesses a decoy function which can block IL-13 signaling. Although the expression of Rα2 is known to be subject to modulation, information about its transcriptional regulation is limited. In this study, we sought to expand the understanding of transcriptional control of Rα2 in lung fibroblasts. We confirmed previous reports that IL-13 elicited modest induction of Rα2 in normal adult human lung fibroblasts, but found that prostaglandin E2 (PGE2) and fibroblast growth factor 2 (FGF-2) -mediators known to influence fibroblast activation in tissue fibrosis but not previously investigated in this regard - led to a much greater magnitude of Rα2 induction. Although both PGE2 (via protein kinase A) and FGF-2 (via protein kinase B, also known as AKT) depended on activation of cAMP-responsive element-binding protein (CREB) for induction of Rα2 expression, they nevertheless demonstrated synergy in doing so, likely attributable to their differential utilization of distinct transcriptional start sites on the Rα2 promoter. Our data identify CREB activation via PGE2 and FGF-2 as a previously unrecognized molecular controller of Rα2 gene induction and provide potential new insights into strategies for therapeutic manipulation of this endogenous brake on IL-13 signaling.

Alveolar macrophage secretion of vesicular SOCS3 represents a platform for lung cancer therapeutics.

Lung cancer remains the leading cause of cancer-related death in the United States. Although the alveolar macrophage (AM) comprises the major resident immune cell in the lung, few studies have investigated its role in lung cancer development. We recently discovered a potentially novel mechanism wherein AMs regulate STAT-induced inflammatory responses in neighboring epithelial cells (ECs) via secretion and delivery of suppressors of cytokine signaling 3 (SOCS3) within extracellular vesicles (EVs). Here, we explored the impact of SOCS3 transfer on EC tumorigenesis and the integrity of AM SOCS3 secretion during development of lung cancer. AM-derived EVs containing SOCS3 inhibited STAT3 activation as well as proliferation and survival of lung adenocarcinoma cells. Levels of secreted SOCS3 were diminished in lungs of patients with non-small cell lung cancer and in a mouse model of lung cancer, and the impaired ability of murine AMs to secrete SOCS3 within EVs preceded the development of lung tumors. Loss of this homeostatic brake on tumorigenesis prompted our effort to "rescue" it. Provision of recombinant SOCS3 loaded within synthetic liposomes inhibited proliferation and survival of lung adenocarcinoma cells in vitro as well as malignant transformation of normal ECs. Intratumoral injection of SOCS3 liposomes attenuated tumor growth in a lung cancer xenograft model. This work identifies AM-derived vesicular SOCS3 as an endogenous antitumor mechanism that is disrupted within the tumor microenvironment and whose rescue by synthetic liposomes can be leveraged as a potential therapeutic strategy for lung cancer.