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.

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.

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.

Differential stem- and progenitor-cell trafficking by prostaglandin E2.

To maintain lifelong production of blood cells, haematopoietic stem cells (HSCs) are tightly regulated by inherent programs and extrinsic regulatory signals received from their microenvironmental niche. Long-term repopulating HSCs reside in several, perhaps overlapping, niches that produce regulatory molecules and signals necessary for homeostasis and for increased output after stress or injury. Despite considerable advances in the specific cellular or molecular mechanisms governing HSC-niche interactions, little is known about the regulatory function in the intact mammalian haematopoietic niche. Recently, we and others described a positive regulatory role for prostaglandin E2 (PGE2) on HSC function ex vivo. Here we show that inhibition of endogenous PGE2 by non-steroidal anti-inflammatory drug (NSAID) treatment in mice results in modest HSC egress from the bone marrow. Surprisingly, this was independent of the SDF-1-CXCR4 axis implicated in stem-cell migration. Stem and progenitor cells were found to have differing mechanisms of egress, with HSC transit to the periphery dependent on niche attenuation and reduction in the retentive molecule osteopontin. Haematopoietic grafts mobilized with NSAIDs had superior repopulating ability and long-term engraftment. Treatment of non-human primates and healthy human volunteers confirmed NSAID-mediated egress in other species. PGE2 receptor knockout mice demonstrated that progenitor expansion and stem/progenitor egress resulted from reduced E-prostanoid 4 (EP4) receptor signalling. These results not only uncover unique regulatory roles for EP4 signalling in HSC retention in the niche, but also define a rapidly translatable strategy to enhance transplantation therapeutically.

Mechanisms and modulation of microvesicle uptake in a model of alveolar cell communication.

Extracellular vesicles, including exosomes and shed microvesicles (MVs), can be internalized by recipient cells to modulate function. Although the mechanism by which extracellular vesicles are internalized is incompletely characterized, it is generally considered to involve endocytosis and an initial surface-binding event. Furthermore, modulation of uptake by microenvironmental factors is largely unstudied. Here, we used flow cytometry, confocal microscopy, and pharmacologic and molecular targeting to address these gaps in knowledge in a model of pulmonary alveolar cell-cell communication. Alveolar macrophage-derived MVs were fully internalized by alveolar epithelial cells in a time-, dose-, and temperature-dependent manner. Uptake was dependent on dynamin and actin polymerization. However, it was neither saturable nor dependent on clathrin or receptor binding. Internalization was enhanced by extracellular proteins but was inhibited by cigarette smoke extract via oxidative disruption of actin polymerization. We conclude that MV internalization occurs via a pathway more consistent with fluid-phase than receptor-dependent endocytosis and is subject to bidirectional modulation by relevant pathologic perturbations.

Alveolar Epithelial Cell-Derived Prostaglandin E2 Serves as a Request Signal for Macrophage Secretion of Suppressor of Cytokine Signaling 3 during Innate Inflammation.

Preservation of gas exchange mandates that the pulmonary alveolar surface restrain unnecessarily harmful inflammatory responses to the many challenges to which it is exposed. These responses reflect the cross-talk between alveolar epithelial cells (AECs) and resident alveolar macrophages (AMs). We recently determined that AMs can secrete suppressor of cytokine signaling (SOCS) proteins within microparticles. Uptake of these SOCS-containing vesicles by epithelial cells inhibits cytokine-induced STAT activation. However, the ability of epithelial cells to direct AM release of SOCS-containing vesicles in response to inflammatory insults has not been studied. In this study, we report that SOCS3 protein was elevated in bronchoalveolar lavage fluid of both virus- and bacteria-infected mice, as well as in an in vivo LPS model of acute inflammation. In vitro studies revealed that AEC-conditioned medium (AEC-CM) enhanced AM SOCS3 secretion above basal levels. Increased amounts of PGE2 were present in AEC-CM after LPS challenge, and both pharmacologic inhibition of PGE2 synthesis in AECs and neutralization of PGE2 in AEC-CM implicated this prostanoid as the major AEC-derived factor mediating enhanced AM SOCS3 secretion. Moreover, pharmacologic blockade of PGE2 synthesis or genetic deletion of a PGE2 synthase similarly attenuated the increase in bronchoalveolar lavage fluid SOCS3 noted in lungs of mice challenged with LPS in vivo. These results demonstrate a novel tunable form of cross-talk in which AECs use PGE2 as a signal to request SOCS3 from AMs to dampen their endogenous inflammatory responses during infection.

Pharmacologic increase in HIF1α enhances hematopoietic stem and progenitor homing and engraftment.

Hematopoietic stem cell (HSC) transplantation is a lifesaving therapy for a number of immunologic disorders. For effective transplant, HSCs must traffic from the peripheral blood to supportive bone marrow niches. We previously showed that HSC trafficking can be enhanced by ex vivo treatment of hematopoietic grafts with 16-16 dimethyl prostaglandin E2 (dmPGE2). While exploring regulatory molecules involved in dmPGE2 enhancement, we found that transiently increasing the transcription factor hypoxia-inducible factor 1-α (HIF1α) is required for dmPGE2-enhanced CXCR4 upregulation and enhanced migration and homing of stem and progenitor cells and that pharmacologic manipulation of HIF1α is also capable of enhancing homing and engraftment. We also now identify the specific hypoxia response element required for CXCR4 upregulation. These data define a precise mechanism through which ex vivo pulse treatment with dmPGE2 enhances the function of hematopoietic stem and progenitor cells; these data also define a role for hypoxia and HIF1α in enhancement of hematopoietic transplantation.

Blockade of prostaglandin E2 signaling through EP1 and EP3 receptors attenuates Flt3L-dependent dendritic cell development from hematopoietic progenitor cells.

Dendritic cell (DC) homeostasis, like all mature blood cells, is maintained via hierarchal generation from hematopoietic precursors; however, little is known about the regulatory mechanisms governing DC generation. Here, we show that prostaglandin E(2) (PGE(2)) is required for optimal Flt3 ligand-mediated DC development and regulates expression of the Flt3 receptor on DC-committed progenitor cells. Inhibition of PGE(2) biosynthesis reduces Flt3-mediated activation of STAT3 and expression of the antiapoptotic protein survivin, resulting in increased apoptosis of DC-committed progenitor cells. Reduced DC development caused by diminished PGE(2) signaling is reversed by overexpression of Flt3 or survivin in DC progenitors and conversely is mimicked by STAT3 inhibition. PGE(2) regulation of DC generation is specifically mediated through the EP1 and EP3 G protein PGE(2) receptors. These studies define a novel DC progenitor regulatory pathway in which PGE(2) signaling through EP1/EP3 receptors regulates Flt3 expression and downstream STAT3 activation and survivin expression, required for optimal DC progenitor survival and DC development in vivo.

Concise review: Sowing the seeds of a fruitful harvest: hematopoietic stem cell mobilization.

Hematopoietic stem cell transplantation is the only curative option for a number of malignant and nonmalignant diseases. As the use of hematopoietic transplant has expanded, so too has the source of stem and progenitor cells. The predominate source of stem and progenitors today, particularly in settings of autologous transplantation, is mobilized peripheral blood. This review will highlight the historical advances which led to the widespread use of peripheral blood stem cells for transplantation, with a look toward future enhancements to mobilization strategies.

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.

Guidelines in Practice: Team Communication.

The perioperative setting is a complex environment requiring interdisciplinary team collaboration to avoid adverse events. To protect the safety of patients and perioperative team members, communication among personnel should be clear and effective. The recently updated AORN "Guideline for team communication" provides perioperative nurses with recommendations on the topic. To promote effective communication in perioperative areas, all personnel should value and commit to a culture of safety. This article discusses recommendations for supporting a culture of safety, developing and implementing an effective hand-off process and surgical safety checklist, and developing education strategies for team communication. It also includes a scenario describing the implementation of a standardized, electronic surgical safety checklist in the OR. Perioperative nurses should review the guideline in its entirety and apply the recommendations for team communication in their working environments.

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.

MAPK 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 the treatment of progressive pulmonary fibrosis in patients. MAPK phosphatase 1 (MKP1) influences the 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. Using gain- and loss-of-function studies, we found that MKP1 promoted lung MF dedifferentiation and restored the sensitivity of these cells to apoptosis - effects determined to be mainly dependent on MKP1's 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.

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: 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: 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: 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: 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: 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: 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.