Significant Pulmonary Injury Research Articles

Comparative analysis of compartment-specific immunothrombotic biomarker profiles in bronchoalveolar lavage fluid and serum of patients with pneumonia-related acute respiratory distress syndrome: A preliminary cross-sectional study.

Immunothrombosis has emerged as a potential mechanistic link underlying the development and progression of acute respiratory distress syndrome (ARDS), but understanding its specific profile in patients, both locally and systemically, is limited. The objective of this study was to characterize and compare the immunothrombotic signatures in patients diagnosed with pneumonia-related ARDS (p-ARDS) at both the pulmonary and systemic levels and to evaluate their clinical relevance. The study included 23 consecutive patients diagnosed with p-ARDS admitted to the intensive care unit at a tertiary university hospital from July 2022 to May 2023, alongside 40 concurrently hospitalized patients with common pneumonia as controls. Paired bronchoalveolar lavage fluid (BALF) and serum samples were collected from the participants for the analysis of 15 biomarkers to assess and quantify the pulmonary and systemic immunothrombotic signatures. The study results revealed significant pulmonary inflammation and systemic endothelial injury in p-ARDS patients compared to pneumonia controls. These observations were maintained after adjustment for severity of illness (Acute Physiology and Chronic Health Evaluation II scores). In terms of clinical relevance, inflammatory biomarkers (interleukin [IL]-6, IL-8) in BALF were found to correlate with PaO2/FiO2 ratio, while serum levels of a disintegrin and metalloproteinase with thrombospondin type 1 motif 13 (ADAMTS-13) and thrombomodulin showed associations with Sequential Organ Failure Assessment and Disseminated Intravascular Coagulation scores. In conclusion, this preliminary investigation identified compartment-specific variations in the immunothrombotic signature between patients with p-ARDS and those with pneumonia alone, with inflammatory responses predominantly localized in the alveolar compartments and coagulation/endothelial injury biomarkers more pronounced in peripheral blood.

Fulminant myocarditis induced by SARS-CoV-2 infection without severe lung involvement: insights into COVID-19 pathogenesis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection often leads to pulmonary complications. Cardiovascular sequelae, including myocarditis and heart failure, have also been reported. Here, the study presents two fulminant myocarditis cases infected by SARS-CoV-2 exhibiting remarkable elevation of cardiac biomarkers without significant pulmonary injury, as determined by imaging examinations. Immunohistochemical staining reveals the viral antigen within cardiomyocytes, indicating that SARS-CoV-2 could directly infect the myocardium. The full viral genomes from respiratory, anal, and myocardial specimens are obtained via next-generation sequencing. Phylogenetic analyses of the whole genome and spike gene indicate that viruses in the myocardium/pericardial effusion and anal swabs are closely related and cluster together yet diverge from those in the respiratory samples. In addition, unique mutations are found in the anal/myocardial strains compared to the respiratory strains, suggesting tissue-specific virus mutation and adaptation. These findings indicate genetically distinct SARS-CoV-2 variants have infiltrated and disseminated within myocardial tissues, independent of pulmonary injury, and point to different infection routes between the myocardium and respiratory tract, with myocardial infections potentially arising from intestinal infection. These findings highlight the potential for systemic SARS-CoV-2 infection and the importance of a thorough multi-organ assessment in patients for a comprehensive understanding of the pathogenesis of COVID-19.

NRICM101 ameliorates SARS-CoV-2-S1-induced pulmonary injury in K18-hACE2 mice model.

The coronavirus disease 2019 (COVID-19) pandemic continues to represent a challenge for public health globally since transmission of different variants of the virus does not seem to be effectively affected by the current treatments and vaccines. During COVID-19 the outbreak in Taiwan, the patients with mild symptoms were improved after the treatment with NRICM101, a traditional Chinese medicine formula developed by our institute. Here, we investigated the effect and mechanism of action of NRICM101 on improval of COVID-19-induced pulmonary injury using S1 subunit of the SARS-CoV-2 spike protein-induced diffuse alveolar damage (DAD) of hACE2 transgenic mice. The S1 protein induced significant pulmonary injury with the hallmarks of DAD (strong exudation, interstitial and intra-alveolar edema, hyaline membranes, abnormal pneumocyte apoptosis, strong leukocyte infiltration, and cytokine production). NRICM101 effectively reduced all of these hallmarks. We then used next-generation sequencing assays to identify 193 genes that were differentially expressed in the S1+NRICM101 group. Of these, three (Ddit4, Ikbke, Tnfaip3) were significantly represented in the top 30 enriched downregulated gene ontology (GO) terms in the S1+NRICM101 group versus the S1+saline group. These terms included the innate immune response, pattern recognition receptor (PRR), and Toll-like receptor signaling pathways. We found that NRICM101 disrupted the interaction of the spike protein of various SARS-CoV-2 variants with the human ACE2 receptor. It also suppressed the expression of cytokines IL-1β, IL-6, TNF-α, MIP-1β, IP-10, and MIP-1α in alveolar macrophages activated by lipopolysaccharide. We conclude that NRICM101 effectively protects against SARS-CoV-2-S1-induced pulmonary injury via modulation of the innate immune response, pattern recognition receptor, and Toll-like receptor signaling pathways to ameliorate DAD.

One-Lung Ventilation in a Patient With Necrotizing Pneumonia Complicated by a Bronchopleural Fistula

A 32-year-old male with morbid obesity presented to the emergency department with a one-week history of shortness of breath and productive cough. This patient had previously been evaluated at an urgent care facility, diagnosed with pneumonia, and prescribed oral antibiotics. This patient’s worsening shortness of breath and productive cough led this patient to seek further care at the emergency department. Chest radiography revealed acute respiratory distress syndrome (ARDS) with an empyema in the right pleural space. He was admitted to the intensive care unit and subsequently intubated due to severely compromised cardiopulmonary function. The patient then underwent irrigation of the chest cavity and chest tube placement for drainage of the right-sided empyema. Surgical cultures revealed growth of Streptococcus anginosus and appropriate antibiotics were started. The patient’s pulmonary function continued to deteriorate and this patient was placed on venous to venous extracorporeal membrane oxygenation (VV ECMO). Due to continued respiratory failure and a persistent air leak, a double-lumen endotracheal tube (DLT) was exchanged to initiate one-lung ventilation (OLV) to optimize ventilation and protect the lung containing the empyema. Over the following days, worsening leukocytosis and atelectasis were noted upon imaging prompting cardiothoracic surgery to return to the operating room to perform a right posterolateral thoracotomy and full right lung decortication. The procedure was successful and a bronchopleural fistula (BPF) was observed, secondary to the necrotizing pneumonia. The observation of the fistula explained the persistent air leak and issues maintaining adequate oxygenation. OLV through a DLT was continued over the following days, and the patient’s pulmonary status and leukocytosis ultimately began to improve over the next two weeks. This patient was then able to be weaned off the EMCO device and was extubated. The patient was stabilized and discharged to a rehabilitation facility for further recovery. This case highlights how the use of lung isolation techniques were essential in the recovery of this patient with an estimated 50% mortality rate due to significant pulmonary injury from necrotizing pneumonia and complicated by a BPF.

Abstract No. 558 Does lung shunt fraction estimation using injection of 99mTc-MAA still vital in 90Y radioembolization dosimetry? A hypothetical study using patient specific information

To compare and estimate the impact of actual vs. arbitrarily chosen lung shunt fraction (LSF) on 90Y radioembolization dosimetry Institutional review board approved this retrospective study of patients who underwent invasive catheter angiogram with injection of macroaggregated albumin (99mTc-MAA) to measure the actual LSF that was then used in 90Y dosimetry for glass microspheres based radioembolization for hepatocellular carcinoma in 2017 and 2018. 40 patients (mean age, 68 years) underwent 44 injections of 99mTc-MAA. Details related to the targeted liver volume, 99mTc-MAA and 90Y procedures were collected from medical records. Impact of arbitrarily chosen LSF on 90Y dosimetry was compared with the 90Y dosimetry based on actual LSF. There was on average 22 days (range, 10–44) delay between the 99mTc-MAA and 90Y procedures. The mean actual LSF was 4.9% (range, 0.8%–11.3%). Average mass of the treated liver was 0.791 kg (range, 0.3–2.36). The mean prescribed radiation dose was 153.7 Gy (range, 110– 320 Gy). The actual radiation dose deposited by glass microspheres was estimated to be 153.4 Gy (range, 100.6–318.4). Alternatively, if 90Y dosimetry is calculated using an arbitrarily chosen LSF of 5%, a minimum commercially available radioactivity (i.e., 3 GBq at the time of calibration) required for the smallest treatment mass (0.3 kg) in this study group would deposit a dose of 118 Gy at 4 pm on a Friday, and the maximum commercially available radioactivity (20 GBq) for the largest treatment mass (2.36 kg) would deposit a dose of 321 Gy at 8 am on a Monday. This study indicates the feasibility of using arbitrary LSF in 90Y dosimetry. When a range of commercially available vials of radioactivity is readily available at the treatment enter, glass microspheres based radioembolization using arbitrarily chosen LSF based 90Y dosimetry would be feasible without the need for 99mTc-MAA injection in most patients. However, an alternative method to predict and identify the small percentage of patients who could have high LSF is required to prevent significant pulmonary injury from radioembolization based on arbitrarily chosen low LSF.

The Toxicity, Pathophysiology, and Treatment of Acute Hydrazine Propellant Exposure: A Systematic Review.

Hydrazines are highly toxic inorganic liquids that are used as propellants in military and aviation industries, such as the U.S. Air Force F-16 Emergency Power Unit and SpaceX SuperDraco Rockets. The most commonly used derivatives include hydrazine, monomethylhydrazine, and 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine). Industrial workers in close contact with hydrazines during routine maintenance tasks can be exposed to levels well above the National Institute for Occupational Safety and Health relative exposure limits. A systematic review was performed using PubMed, Web of Science, Google Scholar, National Aeronautics and Space Administration Technical Server, and Defense Technical Information Center, and data related to hydrazine exposures were searched from inception to April 2020. Publications or reports addressing hydrazine toxicity, pathophysiology, and treatment of hydrazine fuel exposure were selected. Acute toxic exposures to hydrazine and its derivatives are rare. There are few case reports of acute toxic exposure in humans, and data are largely based on animal studies. The initial search identified 741 articles, manuscripts, and government reports. After screening for eligibility, 51 were included in this review. Eight articles reported acute exposures to hydrazine propellant in humans, and an additional 14 articles reported relevant animal data. Exposure to small amounts of hydrazine and its derivatives can cause significant soft tissue injury, pulmonary injury, seizures, coma, and death. Neurologic presentations can vary based on exposure compound and dose. Decontamination is critical as treatment is mainly supportive. High-dose intravenous pyridoxine has been suggested as treatment for hydrazine-related neurologic toxicity, but this recommendation is based on limited human data. Despite recent research efforts to generate less toxic alternatives to hydrazine fuel, it will likely continue to have a role in military and aviation industries. Aerospace and military physicians should be aware of the toxicity associated with hydrazine exposure and be prepared to treat hydrazine toxicity in at-risk populations.

Abstract 261: Acute Lung Injury and Recovery in Patients with Refractory Vf/vt Cardiac Arrest Treated with Prolonged Cpr and Veno Arterial Extracorporeal Membrane Oxygenation

Background: Post cardiac arrest syndrome includes significant pulmonary injury that is not clearly understood. Objectives: Describe the lung injury patterns among patients presenting with refractory ventricular tachycardia/ventricular fibrillation out-of-hospital cardiac arrest (VT/VF OHCA) patients who were treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods: OHCA characteristics, post-arrest computed tomography (CT) scans, ventilator parameters and complications were collected using a retrospective cohort design. Changes in lung compliance were compared over time between survivors, patients with acute brain death and those who had other modes of death with a two- way analysis of variance. Results: Among138 refractory VT/VF OHCA patients (81% were male with a median age of 59.0 years, mean CPR time of 64.3 ±16.1 min, a mean APACHE II score of 30.5 ± 4.6) 48/138 (34.8%) survived, acute brain death occurred in 48/138 (34.8%) and other modes of death in 56/138 (40.6%). The dependent posterior segments of the lung were the most commonly affected areas on the initial CT scan(Fig1A). There was no difference in the number of hyperattenuated areas between the survival groups.Compliance was borderline on day one (median 26.3(19.3,33.3)ml/cmH 2 0), but improved throughout the hospitalization (p=0.001) and was higher in survivors compared to those who died (p<0.001, Fig1B). VA-ECMO allowed the use of lung-protective ventilation in patients with borderline compliances maintaining safe PaO2 and PaCO2. Patients additionally treated with IABP/Impella had lower pulmonary compliance and more hyperattenuated areas on their initial CT scan compared to those treated exclusively with VA-ECMO. Conclusions: Refractory VT/VF OHCA patients who are treated with VA-ECMO frequently have lung injury with borderline compliance soon after the index event. Lung compliance improves throughout hospitalization and is higher in survivors.

Long-term PM2.5 exposure increases the risk of non-small cell lung cancer (NSCLC) progression by enhancing interleukin-17a (IL-17a)-regulated proliferation and metastasis.

PM2.5 is a class of airborne particles and droplets with sustained high levels in many developing countries. Epidemiological studies have indicated that PM2.5 is closely associated with the increased morbidity and mortality of lung cancer in the world. Unfortunately, the effects of PM2.5 on lung cancer are largely unknown. In the present study, we attempted to explore the role of PM2.5 in the etiology of NSCLC. Here, we found that long-term PM2.5 exposure led to significant pulmonary injury. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) properties were highly induced by PM2.5 exposure. EMT was evidenced by the significant up-regulation of MMP2, MMP9, TGF-β1, α-SMA, Fibronectin and Vimentin. Lung cancer progression was associated with the increased expression of Kras, c-Myc, breast cancer resistance protein BCRP (ABCG2), OCT4, SOX2 and Aldh1a1, but the decreased expression of p53 and PTEN. Importantly, mice with IL-17a knockout (IL-17a-/-) showed significantly alleviated lung injury and CSC properties following PM2.5 exposure. Also, IL-17a-/--attenuated tumor growth was recovered in PM2.5-exposed mice injected with recombinant mouse IL-17a, accompanied with significantly restored lung metastasis. Taken together, these data revealed that PM2.5 could promote the progression of lung cancer by enhancing the proliferation and metastasis through IL-17a signaling.

Bioactivity of Circulatory Factors After Pulmonary Exposure to Mild or Stainless Steel Welding Fumes.

Studies suggest that alterations in circulating factors are a driver of pulmonary-induced cardiovascular dysfunction. To evaluate, if circulating factors effect endothelial function after a pulmonary exposure to welding fumes, an exposure known to induce cardiovascular dysfunction, serum collected from Sprague Dawley rats 24 h after an intratracheal instillation exposure to 2 mg/rat of 2 compositionally distinct metal-rich welding fume particulates (manual metal arc welding using stainless steel electrodes [MMA-SS] or gas metal arc welding using mild steel electrodes [GMA-MS]) or saline was used to test molecular and functional effects of in vitro cultures of primary cardiac microvascular endothelial cells (PCMEs) or ex vivo organ cultures. The welding fumes elicited significant pulmonary injury and inflammation with only minor changes in measured serum antioxidant and cytokine levels. PCME cells were challenged for 4 h with serum collected from exposed rats, and 84 genes related to endothelial function were analyzed. Changes in relative mRNA patterns indicated that serum from rats exposed to MMA-SS, and not GMA-MS or PBS, could influence several functional aspects related to endothelial cells, including cell migration, angiogenesis, inflammation, and vascular function. The predictions were confirmed using a functional in vitro assay (scratch assay) as well as an ex vivo multicellular environment (aortic ring angiogenesis assay), validating the concept that endothelial cells can be used as an effective screening tool of exposed workers for determining bioactivity of altered circulatory factors. Overall, the results indicate that pulmonary MMA-SS fume exposure can cause altered endothelial function systemically via altered circulating factors.

Crocin attenuates lung inflammation and pulmonary vascular dysfunction in a rat model of bleomycin-induced pulmonary fibrosis

Amongst the various forms of lung injury; pulmonary fibrosis remains the most intricate form with limited therapeutic options to both the patient and the physicians. Bleomycin (BLM) is a chemotherapeutic agent used for the treatment of various carcinomas; however, its therapeutic value is significantly limited by its associated pulmonary fibrosis. The current study highlights the prominent antioxidant, anti-inflammatory and anti-fibrotic effect of crocin against BLM-induced pulmonary fibrosis. Intratracheal BLM instillation induced significant biochemical, structural, functional and vascular pulmonary injury. BLM instillation increased oxidant load with quenching of antioxidant defenses together with increase inflammatory and fibrotic cytokines expression. Crocin significantly attenuated BLM-induced lung injury and its effect was comparable to the standard anti-fibrotic; halofuginone. The observed anti-inflammatory and anti-fibrotic and antioxidant impacts are thought to be embroiled in the therapeutic impacts of crocin. Down-regulation of TLR4, IL-10 expression is the major pathway involved in the observed anti-inflammatory effects and finally, down-regulation of tissue expression of TNF-α and TGF-β1 is the major pathways implicated in the observed anti-fibrotic activities and modulation of Nrf2 and HO-1 pathways is the main mechanism involved in the observed antioxidant effects.

Association between computed tomographic thoracic injury scores and blood gas and acid-base balance in dogs with blunt thoracic trauma.

To determine the association between thoracic injuries evaluated by computed tomography (CT) and arterial blood gas and acid-base status in dogs with blunt thoracic trauma caused by motor vehicle accidents. Prospective observational clinical study. University teaching hospital. Thirty-one client owned traumatized dogs and 15 healthy dogs. All trauma group dogs underwent a CT scan and simultaneous arterial blood gas analysis within 24 hours, but not before 4 hours, after the traumatic incident within a 45-month enrollment period. Thorax injuries were classified as pulmonary, pleural space, or rib cage and each of these components was scored for severity using a CT composite pulmonary, pleural, and rib score. The trauma group arterial blood gas and acid-base status were evaluated for statistical difference from the control group. The pulmonary-arterial oxygen pressure was significantly lower in the trauma group compared to the control group that was supported by significant differences in the calculated variables of arterial blood oxygenation as well. There was also a significant correlation between the composite lung score and pleural score and the variables of arterial oxygen status. The pulmonary-arterial carbon dioxide pressure was not significantly different to any of the thoracic injury variables indicating normal alveolar ventilation. Acid-base imbalances were generally mild, insignificant, and variable. Blunt thoracic trauma causes significant pulmonary and pleural injury and the blood oxygen economy is significantly affected by this. The functional measures of arterial blood oxygenation were well correlated with thoracic CT pathology. Alveolar ventilation was mostly spared but a clinically significant ventilation perfusion mismatch was present.

Increased Subpleural Pulmonary Arteriolar Tone Associated with Inhibition of Nitric Oxide Synthase in a Mouse Model of Type‐1 Diabetes

Type‐1 diabetes, characterized by elevation of blood glucose, inflammation and oxidative stress, results in endothelial injury that alters nitric oxide (NO) signaling and impairs microvascular regulation in a variety of vascular beds. NO signaling also plays a prominent role in the modulation of alveolar perfusion. Therefore, the lungs may be particularly vulnerable to diabetes‐induced endothelial changes. We hypothesized that diabetes‐induced oxidative injury, resulting in decreased NO bioavailability and enhanced fibrinogen‐endothelial interaction, induces endothelial injury and pulmonary microvascular dysfunction in the mouse lung. The effects of acute NO synthase (NOS) inhibition with L‐NAME on subpleural arterioles were examined in streptozotocin‐treated C57BL/6J mice (STZ) and their saline‐treated controls (Control). Microvascular changes were assessed by intravital microscopy of the right lung in anesthetized mice (7 to 11 months old) with open chest and ventilated lungs. Pulmonary arteriolar diameters (ranging from 27.2 – 48.7 μm) were measured before and after acute administration of the nitric oxide synthase (NOS) inhibitor, L‐NAME (0.1mg/g body wt). L‐NAME caused a 13.6 ± 7.5% constriction (n=5, p=0.034) in Control mice. In contrast, there was an 18.0 ± 11% dilation (p<0.009, n=5) in STZ mice. Intra‐arterial administration of fluorescently‐labeled fibrinogen in STZ mice, without L‐NAME treatment, resulted in adherence of fibrinogen in the microvascular network, indicating endothelial injury. These data suggest that diabetes‐induced systemic effects may affect lung endothelial function. Control mice displayed a physiological vasoconstriction response to L‐NAME resulting from a loss of the NO vasodilator influence. In contrast, while L‐NAME may have decreased bioavailable NO in the diabetic lung, inhibition of NOS with L‐NAME appeared to have a vasodilator effect by decreasing formation of reactive nitrogen species or by unmasking another vasodilator. We conclude that diabetes may adversely affect lung microvasculature by inducing inflammation and decreasing NO bioavailability. Altered NO‐induced responses may subsequently cause significant pulmonary endothelial injury and microvascular dysfunction that could lead to ventilation‐perfusion abnormalities and exacerbate systemic complications of diabetesSupport or Funding InformationUniversity of Louisville, School of Medicine Collaborative Enhancement GrantThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Ghrelin ameliorates acute lung injury induced by oleic acid via inhibition of endoplasmic reticulum stress

AimsAcute lung injury (ALI) is associated with excessive mortality and lacks appropriate therapy. Ghrelin is a novel peptide that protects the lung against ALI. This study aimed to investigate whether endoplasmic reticulum stress (ERS) mediates the protective effect of ghrelin on ALI. Main methodsWe used a rat oleic acid (OA)-induced ALI model. Pulmonary impairment was detected by hematoxylin and eosin (HE) staining, lung mechanics, wet/dry weight ratio, and arterial blood gas analysis. Plasma and lung content of ghrelin was examined by ELISA, and mRNA expression was measured by quantitative real-time PCR. Protein levels were detected by western blot. Key findingsRats with OA treatment showed significant pulmonary injury, edema, inflammatory cellular infiltration, cytokine release, hypoxia and CO2 retention as compared with controls. Plasma and pulmonary content of ghrelin was reduced in rats with ALI, and mRNA expression was downregulated. Ghrelin (10nmol/kg) treatment ameliorated the above symptoms, but treatment with the ghrelin antagonists D-Lys3 GHRP-6 (1μmol/kg) and JMV 2959 (6mg/kg) exacerbated the symptoms. ERS induced by OA was prevented by ghrelin and augmented by ghrelin antagonist treatment. The ERS inducer, tunicamycin (Tm) prevented the ameliorative effect of ghrelin on ALI. The decreased ratio of p-Akt and Akt induced by OA was improved by ghrelin treatment, and was further exacerbated by ghrelin antagonists. SignificanceGhrelin protects against ALI by inhibiting ERS. These results provide a new target for prevention and therapy of ALI.

Neoadjuvant versus definitive chemoradiation for locally advanced esophageal squamous cell carcinoma

A standard treatment option for patients with locally advanced thoracic esophageal squamous cell carcinoma (TESCC) is trimodality therapy, often consisting of neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgery (1-4). However, transhiatal esophagectomy poses significant risks, including tracheal and pulmonary injury, anastomotic leak, vagus nerve injury, infection, and death. Therefore, two randomized trials have addressed this concern by comparing definitive CCRT (dCCRT) alone versus neoadjuvant CCRT (nCCRT) plus surgery in esophageal cancer (5,6). Both trials found no difference in overall survival (OS), but fewer local recurrences were observed in the nCCRT plus surgery groups. Major limitations of these trials included salvage therapy potentially confounding OS, the usage of induction chemotherapy (which is a widely utilized treatment strategy), patient selection based on induction chemotherapy response (6), and diminished applicability to current practice utilizing more advanced radiation techniques like intensity-modulated radiation therapy (IMRT). Consequently, recent high volume data addressing the therapeutic benefits of dCCRT versus nCCRT followed by surgery are lacking, and such data are needed to help inform the optimal management approach for TESCC.

Small Animal Review

Introduction: Acute necrotising pancreatitis in the dog is often associated with significant secondary pulmonary injury and clinical features of respiratory compromise.

Pulmonary Epithelial TLR4 Activation Leads to Lung Injury in Neonatal Necrotizing Enterocolitis.

We seek to define the mechanisms leading to the development of lung disease in the setting of neonatal necrotizing enterocolitis (NEC), a life-threatening gastrointestinal disease of premature infants characterized by the sudden onset of intestinal necrosis. NEC development in mice requires activation of the LPS receptor TLR4 on the intestinal epithelium, through its effects on modulating epithelial injury and repair. Although NEC-associated lung injury is more severe than the lung injury that occurs in premature infants without NEC, the mechanisms leading to its development remain unknown. In this study, we now show that TLR4 expression in the lung gradually increases during postnatal development, and that mice and humans with NEC-associated lung inflammation express higher levels of pulmonary TLR4 than do age-matched controls. NEC in wild-type newborn mice resulted in significant pulmonary injury that was prevented by deletion of TLR4 from the pulmonary epithelium, indicating a role for pulmonary TLR4 in lung injury development. Mechanistically, intestinal epithelial TLR4 activation induced high-mobility group box 1 release from the intestine, which activated pulmonary epithelial TLR4, leading to the induction of the neutrophil recruiting CXCL5 and the influx of proinflammatory neutrophils to the lung. Strikingly, the aerosolized administration of a novel carbohydrate TLR4 inhibitor prevented CXCL5 upregulation and blocked NEC-induced lung injury in mice. These findings illustrate the critical role of pulmonary TLR4 in the development of NEC-associated lung injury, and they suggest that inhibition of this innate immune receptor in the neonatal lung may prevent this devastating complication of NEC.

The use of angiotensin II in distributive shock.

The interest in the use of non-catecholamine vasopressors for the treatment of hypotension and shock has increased in recent years. The use of vasopressin as an adjunctive vasopressor in shock was reinvigorated by Landry and colleagues [1] and then carefully assessed in the Vasopressin versus Norepinephrine Infusion in Patients with Septic Shock (VASST) trial [2]. In a large, international, multi-center trial, vasopressin demonstrated a satisfactory safety profile, but did not show an improvement in survival compared to norepinephrine [2]. In addition to vasopressin, angiotensin II (ATII) has been proposed as a useful vasopressor for the management of shock [3, 4]. The original studies that assessed ATII for the management of shock were conducted decades ago [3, 5]. In those trials, ATII was assessed primarily in head-to-head studies compared to catecholamine vasopressors, and was shown to have comparable vasopressor effect to norepinephrine [5]. Multiple case reports demonstrated the ability of ATII to work effectively as a vasopressor and also showed that ATII could be used in combination with catecholamines. However, ATII has not been subjected to a randomized controlled trial (RCT) and ATII has not been available at the bedside for at least 15 years. ATII has been used extensively in physiology, hypertension, cancer, and pregnancy studies in humans and has a good safety profile. Recently, we published in Critical Care the first RCT of ATII in patients with distributive shock, and showed that a dose of ATII of 5–40 ng/kg/min was associated with improved blood pressure that resulted in significant catecholamine sparing [6]. In that modest-sized study, we noted that 2 of the 10 patients treated with ATII were exquisitely sensitive to ATII. In these two cases, the subjects receiving physiologic doses of ATII were hypertensive despite the discontinuation of their norepinephrine. When ATII was stopped in these two patients, re-initiation of a high dose of norepinephrine (i.e., 0.3 μg/kg/min) was immediately required in order to maintain mean arterial pressure goals. We speculated that the reason for this sensitivity was likely due to premorbid exposure to angiotensin-converting enzyme (ACE) inhibitors prior to the development of shock. Our theory was that if the subjects were previously treated with ACE inhibitors, their ATII Type I receptors would be upregulated, thus making the patient more sensitive to exogenous ATII infusion. However, after a thorough chart review and re-review, we could not document an ACE inhibitor exposure. While it is possible that the ACE inhibitor exposure was present and not documented, there is an alternative explanation which is related to the nature and distribution of ACE. Angiotensin I (ATI) is converted efficiently to ATII almost exclusively in the lung [7]. ACE is an ectoenzyme which is distributed primarily on the pulmonary capillary endothelium [8, 9]. As a consequence, diseases that affect the pulmonary capillary endothelium can disrupt ACE functionality. Acute respiratory distress syndrome (ARDS) is often associated with significant pulmonary endothelial injury [10]. Patients with more severe ARDS have less capacity to convert angiotensin ATI to ATII, and this disturbance is inversely correlated to the severity of ARDS [11]. Upon re-review, we found that the two patients in our study who were exquisitely ATII sensitive had severe ARDS. Our revised hypothesis is that patients with severe ARDS may have significant pulmonary endothelial injury, which results in either an absolute or relative insufficiency of ATII due to loss of pulmonary ACE. Pre-clinical and human case reports demonstrate that when ATII production is inhibited by ACE inhibition, patients become catecholamine resistant [12]. Thus, patients with ARDS may be at particular risk for ATII insufficiency, which would likely exacerbate existing hypotension. In addition, ATII insufficiency can lead to acute kidney injury due to decreased intra-glomerular pressure. We hypothesize that some patients with shock and ARDS may be at particular risk for a deleterious cascade of events related to ATII insufficiency (Fig. 1). Fig. 1 Proposed cascade of events leading to angiotensin II insufficiency. The figure outlines a cascade of events that could occur amongst patients with inflammation and/or lung injury. When acute lung injury is significantly complicated by pulmonary endothelial ... We would anticipate that, for those patients with ATII insufficiency, increased levels of ATI and reduced ATII may be indicative of this pathophysiology, and that ATI and ATII levels, as well as the ratio of ATI/ATII, may be useful as biomarkers of early ARDS or ARDS severity prior to the development of severe hypoxemia. Moreover, we would anticipate these patients to be ATII-sensitive. We believe that further research to test this hypothesis is warranted. Currently, ATII is being studied in a multi-center international RCT (NCT02338843) wherein some of these parameters will be assessed and may shed further light on this proposed hypothesis.

Piper Study Rationale and Design: Characterizing the Incidence of Acute Respiratory Distress Syndrome in Hematology-Oncology Patients Following the Transfusion of Conventional or Pathogen-Reduced Platelet Components

The INTERCEPT™ Blood System (amotosalen + UVA illumination) for platelets is FDA-approved in the USA for the ex vivo preparation of pathogen-reduced, apheresis platelet components (PCs) to reduce transfusion-transmitted infection, including sepsis, and to potentially reduce the risk of transfusion-associated graft vs. host disease. Platelet transfusion is a potential risk factor for acute respiratory distress syndrome (ARDS), but the incidence of ARDS following platelet transfusion is not well-defined. A phase 3 study (SPRINT) of patients treated with INTERCEPT PCs vs. conventional PCs reported a frequency of ARDS of 1.6% vs. 0%, respectively (Snyder et al., Transfusion 2005;45:1864-1875). This unexpectedly low incidence of ARDS, owing to the lack of precise definitions, prompted the conduct of a blinded reanalysis using the American European Consensus Criteria for ARDS. Reanalysis demonstrated a frequency of ARDS of 6.0% and 4.9% for recipients of pathogen-reduced PCs and conventional PCs, respectively, with no significant treatment difference between groups (Corash et al., Blood 2011;117:1014-1020). Large scale active hemovigilance programs in Europe conducted by regulatory authorities from 2009-2014 reported no differences in the incidence of ARDS following platelet transfusion (0.33 vs. 0.32 cases per 10,000 platelets transfused). To evaluate the incidence of severe pulmonary adverse events requiring assisted ventilation in hematology-oncology (heme/onc) patients following the transfusion of apheresis derived INTERCEPT PCs compared to transfusion of conventional apheresis PCs. A prospective, non-randomized sequential cohort, open label, multi-center, non-inferiority, phase 4 surveillance study following transfusion of INTERCEPT PCs will be conducted. The patient population will be heme/onc hematopoietic stem cell transplant (HSCT) patients expected to require >1 PC transfusions. The proportion of patients requiring treatment-emergent assisted mechanical ventilation (TEAMV) during the observation period as defined by intubation or tight-fitting mask. TEAMV provides an objective measure of severe, clinically significant pulmonary injury. Patients will be assessed for TEAMV within 7 days after each study PC transfusion. 3000 patients allow for >90% power (one-sided alpha 0.025) for a non-inferiority margin of 0.023, assuming an event rate of 3.7% for the Control group. Events will be adjudicated by a blinded Pulmonary Expert Adjudication Panel. The PIPER study will address a significant deficit in the understanding of serious pulmonary events in heme/onc HSCT patients who require platelet support. It will be the first large controlled trial designed and powered to detect serious pulmonary adverse events in this patient population.

Platelet‐Endothelial Association with Fibrinogen/Fibrin, Coupled with Oxidative Stress, Protein Nitrosylation, and Fibrosis may underlie Pulmonary Endothelial Cell Dysfunction in a Mouse Model of Type 1 Diabetes

Diabetes is characterized by inflammation and abnormal microvascular function. Pulmonary complications, although not well characterized, have been reported in diabetic patients. We hypothesized that oxidative stress, altered nitric oxide synthesis and enhanced fibrinogen‐endothelial interaction in the diabetic lung may underlie pulmonary vascular dysfunction. FVB mice, 8‐10 weeks‐old, were injected with streptozocin (FVB DM; 50mg/kg for 5 days) to induce type 1 diabetes, or with vehicle (FVB Ctr). Lung superoxide formation (DHE) and protein nitrosylation (3‐NT) were assessed after 5 months as indicators of oxidative stress, and type I and type III collagen deposition (Sirius Red) as a marker of pulmonary fibrosis. Superoxide production (152.74 ± 9.11 DM vs. 110.23 ± 3.34 Ctr) and collagen deposition (259.47 ± 8.9 DM vs. 192.89 ± 17.68 Ctr) significantly increased in FVB‐DM (p<0.05; n=3). Protein nitrosylation was elevated, but did not reach significance (102.61 ± 19.18 DM vs. 84.97 ± 10.48 Ctr). Fibrinogen, endothelial cell (CD‐31) and platelet (CD‐61) interactions, assessed by immunochemical staining, showed enhanced expression and co‐localization in FVB DM mice. These data indicate that the lung may be an important target of diabetes‐induced inflammatory injury, inducing decreased nitric oxide bioavailability, significant pulmonary microvascular injury and fibrosis. We conclude that diabetic pulmonary complications could lead to ventilation‐perfusion abnormalities that would exacerbate systemic complications of diabetes.

Comparative Microscopic Study of Human and Rat Lungs After Overexposure to Welding Fume

Welding is a common industrial process used to join metals and generates complex aerosols of potentially hazardous metal fumes and gases. Most long-time welders experience some type of respiratory disorder during their time of employment. The use of animal models and the ability to control the welding fume exposure in toxicology studies have been helpful in developing a better understanding of how welding fumes affect health. There are no studies that have performed a side-by-side comparison of the pulmonary responses from an animal toxicology welding fume study with the lung responses associated with chronic exposure to welding fume by a career welder. In this study, post-mortem lung tissue was donated from a long-time welder with a well-characterized work background and a history of extensive welding fume exposure. To simulate a long-term welding exposure in an animal model, Sprague-Dawley rats were treated once a week for 28 weeks by intratracheal instillation with 2mg of a stainless steel, hard-surfacing welding fume. Lung tissues from the welder and the welding fume-treated rats were examined by light and electron microscopy. Pathological analysis of lung tissue collected from the welder demonstrated inflammatory cell influx and significant pulmonary injury. The poor and deteriorating lung condition observed in the welder examined in this study was likely due to exposure to very high levels of potentially toxic metal fumes and gases for a significant number of years due to work in confined spaces. The lung toxicity profile for the rats treated with welding fume was similar. For tissue samples from both the welder and treated rats, welding particle accumulations deposited and persisted in lung structures and were easily visualized using light microscopic techniques. Agglomerates of deposited welding particles mostly were observed within lung cells, particularly alveolar macrophages. Analysis of individual particles within the agglomerates showed that these particles were metal complexes with iron, chromium, and nickel being the most common metals present. In conclusion, long-term exposure to specific welding fume can lead to serious chronic lung disease characterized by significant particle deposition and persistence as demonstrated in both a human case study and rat model. Not only were the lung responses similar in the human and rat lungs, as evidenced by inflammatory cell influx and pulmonary disease, but the composition of individual welding particles and agglomerations in situ was comparable.