Immunization with lytic polysaccharide monooxygenase CbpD induces protective immunity against Pseudomonas aeruginosa pneumonia.

Pseudomonas aeruginosa (PA) CbpD belongs to the lytic polysaccharide monooxygenases (LPMOs), a family of enzymes that cleave chitin or related polysaccharides. Here, we demonstrate a virulence role of CbpD in PA pneumonia linked to impairment of host complement function and opsonophagocytic clearance. Following intratracheal challenge, a PA ΔCbpD mutant was more easily cleared and produced less mortality than the wild-type parent strain. The x-ray crystal structure of the CbpD LPMO domain was solved to subatomic resolution (0.75Å) and its two additional domains modeled by small-angle X-ray scattering and Alphafold2 machine-learning algorithms, allowing structure-based immune epitope mapping. Immunization of naive mice with recombinant CbpD generated high IgG antibody titers that promoted human neutrophil opsonophagocytic killing, neutralized enzymatic activity, and protected against lethal PA pneumonia and sepsis. IgG antibodies generated against full-length CbpD or its noncatalytic M2+CBM73 domains were opsonic and protective, even in previously PA-exposed mice, while antibodies targeting the AA10 domain were not. Preexisting antibodies in PA-colonized cystic fibrosis patients primarily target the CbpD AA10 catalytic domain. Further exploration of LPMO family proteins, present across many clinically important and antibiotic-resistant human pathogens, may yield novel and effective vaccine antigens.

Neutrophil Extracellular Traps (NETs): An Emerging Therapeutic Target to Improve Infectious Diseases Outcomes.

Neutrophils possess a diverse repertoire of pathogen clearance mechanisms, one of which is the formation of neutrophil extracellular traps (NETs). NETs are complexes of histone proteins and DNA coated with proteolytic enzymes that are released extracellularly to entrap pathogens and aid in their clearance, in a process known as NETosis. Intravascular NETosis may drive a massive inflammatory response that has been shown to contribute to morbidity and mortality in many infectious diseases, including malaria, dengue fever, influenza, bacterial sepsis, and SARS-CoV-2 infection. In this review we seek to: (1) summarize the current understanding of NETs; (2) discuss infectious diseases in which NET formation contributes to morbidity and mortality; and (3) explore potential adjunctive therapeutics that may be considered for future study in treating severe infections driven by NET pathophysiology. This includes drugs specifically targeting NET inhibition and FDA-approved drugs that may be repurposed as NET inhibitors.

Very Low Driving-Pressure Ventilation in Patients With COVID-19 Acute Respiratory Distress Syndrome on Extracorporeal Membrane Oxygenation: A Physiologic Study.

OBJECTIVES: To determine in patients with acute respiratory distress syndrome (ARDS) on venovenous extracorporeal membrane oxygenation (VV ECMO) whether reducing driving pressure (ΔP) would decrease plasma biomarkers of inflammation and lung injury (interleukin-6 [IL-6], IL-8, and the soluble receptor for advanced glycation end-products sRAGE). DESIGN: A single-center prospective physiologic study. SETTING: At a single university medical center. PARTICIPANTS: Adult patients with severe COVID-19 ARDS on VV ECMO. INTERVENTIONS: Participants on VV ECMO had the following biomarkers measured: (1) pre-ECMO with low-tidal-volume ventilation (LTVV), (2) post-ECMO with LTVV, (3) during low-driving-pressure ventilation (LDPV), (4) after 2 hours of very low driving-pressure ventilation (V-LDPV, main intervention ΔP = 1 cmH2O), and (5) 2 hours after returning to LDPV. MAIN MEASUREMENTS AND RESULTS: Twenty-six participants were enrolled; 21 underwent V-LDPV. There was no significant change in IL-6, IL-8, and sRAGE from LDPV to V-LDPV and from V-LDPV to LDPV. Only participants (9 of 21) with nonspontaneous breaths had significant change (p < 0.001) in their tidal volumes (Vt) (mean ± SD), 1.9 ± 0.5, 0.1 ± 0.2, and 2.0 ± 0.7 mL/kg predicted body weight (PBW). Participants with spontaneous breathing, Vt were unchanged-4.5 ± 3.1, 4.7 ± 3.1, and 5.6 ± 2.9 mL/kg PBW (p = 0.481 and p = 0.065, respectively). There was no relationship found when accounting for Vt changes and biomarkers. CONCLUSIONS: Biomarkers did not significantly change with decreased ΔPs or Vt changes during the first 24 hours post-ECMO. Despite deep sedation, reductions in Vt during V-LDPV were not reliably achieved due to spontaneous breaths. Thus, patients on VV ECMO for ARDS may have higher Vt (ie, transpulmonary pressure) than desired despite low ΔPs or Vt.

Increased Peripheral Blood Neutrophil Activation Phenotypes and Neutrophil Extracellular Trap Formation in Critically Ill Coronavirus Disease 2019 (COVID-19) Patients: A Case Series and Review of the Literature.

BACKGROUND: Increased inflammation has been well defined in coronavirus disease 2019 (COVID-19), while definitive pathways driving severe forms of this disease remain uncertain. Neutrophils are known to contribute to immunopathology in infections, inflammatory diseases, and acute respiratory distress syndrome, a primary cause of morbidity and mortality in COVID-19. Changes in neutrophil function in COVID-19 may give insight into disease pathogenesis and identify therapeutic targets. METHODS: Blood was obtained serially from critically ill COVID-19 patients for 11 days. Neutrophil extracellular trap formation (NETosis), oxidative burst, phagocytosis, and cytokine levels were assessed. Lung tissue was obtained immediately postmortem for immunostaining. PubMed searches for neutrophils, lung, and COVID-19 yielded 10 peer-reviewed research articles in English. RESULTS: Elevations in neutrophil-associated cytokines interleukin 8 (IL-8) and interleukin 6, and general inflammatory cytokines IFN-inducible protien-19, granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin 1ß, interleukin 10, and tumor necrosis factor, were identified both at first measurement and across hospitalization (P < .0001). COVID-19 neutrophils had exaggerated oxidative burst (P < .0001), NETosis (P < .0001), and phagocytosis (P < .0001) relative to controls. Increased NETosis correlated with leukocytosis and neutrophilia, and neutrophils and NETs were identified within airways and alveoli in lung parenchyma of 40% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected lungs available for examination (2 of 5). While elevations in IL-8 and absolute neutrophil count correlated with disease severity, plasma IL-8 levels alone correlated with death. CONCLUSIONS: Literature to date demonstrates compelling evidence of increased neutrophils in the circulation and lungs of COVID-19 patients. Importantly, neutrophil quantity and activation correlates with severity of disease. Similarly, our data show that circulating neutrophils in COVID-19 exhibit an activated phenotype with enhanced NETosis and oxidative burst.

A unique case of Miller Fisher-Guillain-Barré overlap syndrome in a liver transplant recipient.

Guillain-Barré syndrome (GBS) is an ascending demyelinating polyneuropathy often associated with recent infection. Miller Fisher syndrome represents a variant with predominant facial and cranial nerve involvement, although Miller Fisher and Guillain-Barré overlap syndromes can occur. Guillain-Barré spectrum syndromes have been thought to be rare among solid organ transplant recipients. We describe an immunocompromised patient with a liver transplant who presented with ophthalmoplegia and bulbar deficits. His symptoms rapidly progressed to a state of descending paralysis involving the diaphragm; he then developed acute respiratory failure and eventually developed quadriparesis. Electromyography and a nerve conduction study demonstrated a severe sensorimotor axonal polyneuropathy consistent with Miller Fisher variant Guillain-Barré syndrome. Despite several negative nasopharyngeal swabs for COVID-19 polymerase chain reaction, a serology for SARS-CoV-2 IgG was positive. He was diagnosed with Miller Fisher-Guillain-Barré overlap syndrome with rapid recovery following treatment with plasma exchange. Although Guillain-Barré is a rare complication in solid organ transplant recipients, this case highlights the importance of rapid diagnosis and treatment of neurologic complications in transplant patients. Furthermore, it demonstrates a possible case of neurological complications from COVID-19 infection.

E-cigarette use increases susceptibility to bacterial infection by impairment of human neutrophil chemotaxis, phagocytosis, and NET formation.

E-cigarettes are portrayed as safer relative to conventional tobacco. However, burgeoning evidence suggests that E-cigarettes may adversely affect host defenses. However, the precise mechanisms by which E-cigarette vapor alters innate immune cell function have not been fully elucidated. We determined the effects of E-cigarette exposure on the function and responses to infectious challenge of the most abundant innate immune cell, the neutrophil, using isolated human neutrophils and a mouse model of gram-negative infection. Our results revealed that human neutrophils exposed to E-cigarette vapor had 4.2-fold reductions in chemotaxis toward the bacterial cell-well component f-Met-Leu-Phe (P < 0.001). F-actin polarization and membrane fluidity were also adversely affected by E-cigarette vapor exposure. E-cigarette-exposed human neutrophils exhibited a 48% reduction in production of reactive oxygen species (ROS; P < 0.001). Given the central role of ROS in neutrophil extracellular trap (NET) production, NET production was quantified, and E-cigarette vapor exposure was found to reduce NETosis by 3.5-fold (P < 0.01); formulations with and without nicotine containing propylene glycol exhibiting significant suppressive effects. However, noncanonical NETosis was unaffected. In addition, exposure to E-cigarette vapor lowered the rate of phagocytosis of bacterial bioparticles by 47% (P < 0.05). In our physiological mouse model of chronic E-cigarette exposure and sepsis, E-cigarette vapor inhalation led to reduced neutrophil migration in infected spaces and a higher burden of Pseudomonas. These findings provide evidence that E-cigarette use adversely impacts the innate immune system and may place E-cigarette users at higher risk for dysregulated inflammatory responses and invasive bacterial infections.

Female Physician Leadership During Cardiopulmonary Resuscitation Is Associated With Improved Patient Outcomes.

OBJECTIVES: A recently published simulation study suggested that women are inferior leaders of cardiopulmonary resuscitation efforts. The aim of this study was to compare female and male code leaders in regard to cardiopulmonary resuscitation outcomes in a real-world clinical setting. DESIGN: Retrospective cohort review. SETTING: Two academic, urban hospitals in San Diego, California. SUBJECTS: One-thousand eighty-two adult inpatients who suffered cardiac arrest and underwent cardiopulmonary resuscitation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We analyzed whether physician code leader gender was independently associated with sustained return of spontaneous circulation and survival to discharge and with markers of quality cardiopulmonary resuscitation. Of all arrests, 327 (30.1%) were run by female physician code leaders with 251 (76.8%) obtaining return of spontaneous circulation, and 122 (37.3%) surviving to discharge. Male physicians ran 757 codes obtaining return of spontaneous circulation in 543 (71.7%) with 226 (29.9%) surviving to discharge. When adjusting for variables, female physician code leader gender was independently associated with a higher likelihood of return of spontaneous circulation (odds ratio, 1.36; 95% CI, 1.01-1.85; p = 0.049) and survival to discharge (odds ratio, 1.53; 95% CI, 1.15-2.02; p < 0.01). Additionally, the odds ratio for survival to discharge was 1.62 (95% CI, 1.13-2.34; p < 0.01) for female physicians with a female code nurse when compared with male physician code leaders paired with a female code nurse. Gender of code leader was not associated with cardiopulmonary resuscitation quality. CONCLUSIONS: In contrast to data derived from a simulated setting with medical students, real life female physician leadership of cardiopulmonary resuscitation is not associated with inferior outcomes. Appropriately, trained physicians can lead high-quality cardiopulmonary resuscitation irrespective of gender.

Interaction of cell culture process parameters for modulating mAb afucosylation.

The extent of afucosylation, which refers to the absence of core fucose on Fc glycans, can correlate positively with the antibody-dependent cellular cytotoxicity (ADCC) activity of a monoclonal antibody (mAb). Therefore, it is important to maintain consistent afucosylation during cell culture process scale-up in bioreactors for a mAb with ADCC activity. However, there is currently a lack of understanding about the impact of partial pressure of carbon dioxide (pCO2 )-a parameter that can vary with bioreactor scale-on afucosylation. Using a small-scale (3 L) bioreactor model that can modulate pCO 2 levels through modified configurations and gassing strategies, we identified three cell culture process parameters that influence afucosylation of a mAb produced by a recombinant Chinese Hamster Ovary (CHO) cell line: pCO 2 , media hold duration (at 37°C), and manganese. These three-independent parameters demonstrated a synergistic effect on mAb afucosylation; increase in pCO 2 , media hold duration, and manganese consistently increased afucosylation. Our investigations into the underlying mechanisms through proteomic analysis indicated that the synergistic interactions downregulated pathways related to guanosine diphosphate-fucose synthesis and fucosylation, and upregulated manganese transport into the CHO cells. These new findings highlight the importance of considering potential differences in culture environment and operations across bioreactor scales, and understanding the impact of their interactions on product quality.

Impact of Anesthetics on Human Neutrophil Function.

Anesthetics are widely used drugs administered in a multitude of clinical settings. Their impacts on various functions of the immune system have been studied but are still not fully understood. Neutrophil granulocytes are a critical first-line host defense mechanism against infections and contribute to the inflammatory phase of wound healing, but dysregulated neutrophil activation can also precipitate perioperative organ injury. A better understanding of the interactions between common anesthetics and neutrophils may reveal considerations toward optimizing treatment of our most vulnerable patients in the intensive care unit and in the perioperative setting.

Peripartum Cardiomyopathy: Current Options for Treatment and Cardiovascular Support.

Peripartum cardiomyopathy is a rare form of acute heart failure but the major cause of all deaths in pregnant patients with heart failure. Improved survival rates in recent years, however, emphasize the importance of early recognition and initiation of heart failure treatment. This article, therefore, attempts to raise awareness among cardiac and obstetric anesthesiologists as well as intensivists of this often fatal diagnosis. This review summarizes theories of the pathophysiology and outcome of peripartum cardiomyopathy. Based on the most recent literature, it further outlines diagnostic criteria and treatment options including medical management, mechanical circulatory support devices, and heart transplantation. Earlier recognition of this rare condition and a new generation of mechanical circulatory devices has contributed to the improved outcome. More frequently, patients in cardiogenic shock who fail medical management are successfully bridged to recovery on extracorporeal circulatory devices or survive with a long-lasting implantable ventricular assist device. The outcome of transplanted patients with peripartum cardiomyopathy, however, is worse compared to other recipients of heart transplants and warrants further investigation in the future.

Alterations in human neutrophil function caused by bisphenol A.

Bisphenol A (BPA) is a synthetic, organic compound frequently present in consumer plastics, including plastic-lined cans, water bottles, toys, and teeth sutures. Previous studies have shown that BPA can produce adverse health effects that include defects in reproductive function and altered prenatal/childhood development. However, little is known regarding the effects of BPA on immune function. In this study, we assessed the effect of BPA on human neutrophils, a critical component of the innate immune system's defense against pathogens. We found that BPA induces a concentration-dependent increase in reactive oxygen species (ROS) generation by neutrophils, which is inhibited by the estrogen receptor-ß antagonist PHTPP. Furthermore, incubation with the membrane-permeable calcium chelator BAPTA-AM and/or removal of extracellular calcium inhibited BPA-induced ROS production, indicating that the process is calcium dependent. Transwell chemotaxis assays revealed that BPA exposure reduces the chemotactic capacity of neutrophils in a gradient of the bacterial cell wall component f-Met-Leu-Phe, a potent chemoattractant. Exposure to BPA also inhibits the ability of neutrophils to kill methicillin-resistant Staphylococcus aureus, a leading human pathogen. Our findings reveal that BPA alters the in vitro function of neutrophils, including ROS production, chemotaxis, and bacterial killing, and raises the possibility of altered innate immunity in vivo, especially in those with compromised immune function and who can be exposed to BPA in a wide variety of products.

Isoflurane Impacts Murine Melanoma Growth in a Sex-Specific, Immune-Dependent Manner: A Brief Report.

The impact of volatile anesthetics on cancer progression has been observed for decades, but sex differences have not been described. Male and female immune systems vary considerably, and the immune system plays an important role in limiting cancer growth. Currently, mouse models describing the impact of volatile anesthetics on cancer growth are limited to same-sex models. In this brief report, we describe a sex-specific impact of isoflurane on melanoma growth observed in wild-type but not in immune-deficient mice. Future experimental designs related to anesthesia and cancer should evaluate the biological variable of sex in a systematic manner.

The influence of spaying and its timing relative to the onset of puberty on urinary and general behaviour in Labrador Retrievers.

Benefits and risks of spaying on the behaviour of female dogs are controversially discussed. Increased aggressiveness and male urinary behaviour were postulated to be the consequence of masculinization after spaying in some female dogs. To investigate if spaying or its timing relative to the onset of puberty may have a masculinization effect, urinary behaviour, that is, frequency of urination, urinary posture and ground scratching after urination were recorded in 58 female Labrador Retrievers during 15 min of a daily walk with their owners. General behaviour of the dogs during the walks was assessed using an owner questionnaire. Data were analysed for age, reproductive status, lifetime of ovary exposure and/or time interval since spaying. Urinary behaviour of intact females (n = 12) and dogs spayed before (n = 17) or after (n = 29) puberty was similar and not influenced by age, lifetime of ovary exposure and/or time interval since spaying. Owners of spayed dogs described more frequent or more intense fear reaction in their animals in response to loud noises, unfamiliar objects approaching on or near the sidewalk, or if they were approached by unknown dogs barking, growling or jumping. In conclusion, we found no evidence of a masculinization effect after spaying on urinary behaviour in female Labrador Retrievers. In contrast to popular belief, gonadectomy did not inevitably result in a behaviourally more stable dog. Extrapolation of our findings from female Labrador Retrievers to other breeds should be performed with caution, as the effect of spaying on behaviour may differ among dog breeds.

Prediction of Readmission Following Sepsis Using Social Determinants of Health.

OBJECTIVES: To determine the predictive value of social determinants of health (SDoH) variables on 30-day readmission following a sepsis hospitalization as compared with traditional clinical variables. DESIGN: Multicenter retrospective cohort study using patient-level data, including demographic, clinical, and survey data. SETTINGS: Thirty-five hospitals across the United States from 2017 to 2021. PATIENTS: Two hundred seventy-one thousand four hundred twenty-eight individuals in the AllofUs initiative, of which 8909 had an index sepsis hospitalization. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Unplanned 30-day readmission to the hospital. Multinomial logistic regression models were constructed to account for survival in determination of variables associate with 30-day readmission and are presented as adjusted odds rations (aORs). Of the 8909 sepsis patients in our cohort, 21% had an unplanned hospital readmission within 30 days. Median age (interquartile range) was 54 years (41-65 yr), 4762 (53.4%) were female, and there were self-reported 1612 (18.09%) Black, 2271 (25.49%) Hispanic, and 4642 (52.1%) White individuals. In multinomial logistic regression models accounting for survival, we identified that change to nonphysician provider type due to economic reasons (aOR, 2.55 [2.35-2.74]), delay of receiving medical care due to lack of transportation (aOR, 1.68 [1.62-1.74]), and inability to afford flow-up care (aOR, 1.59 [1.52-1.66]) were strongly and independently associated with a 30-day readmission when adjusting for survival. Patients who lived in a ZIP code with a high percentage of patients in poverty and without health insurance were also more likely to be readmitted within 30 days (aOR, 1.26 [1.22-1.29] and aOR, 1.28 [1.26-1.29], respectively). Finally, we found that having a primary care provider and health insurance were associated with low odds of an unplanned 30-day readmission. CONCLUSIONS: In this multicenter retrospective cohort, several SDoH variables were strongly associated with unplanned 30-day readmission. Models predicting readmission following sepsis hospitalization may benefit from the addition of SDoH factors to traditional clinical variables.