Neutrophils and galectin-3 defend mice from lethal bacterial infection and humans from acute respiratory failure.

Respiratory infection by Pseudomonas aeruginosa, common in hospitalized immunocompromised and immunocompetent ventilated patients, can be life-threatening because of antibiotic resistance. This raises the question of whether the host's immune system can be educated to combat this bacterium. Here we show that prior exposure to a single low dose of lipopolysaccharide (LPS) protects mice from a lethal infection by P. aeruginosa. LPS exposure trained the innate immune system by promoting expansion of neutrophil and interstitial macrophage populations distinguishable from other immune cells with enrichment of gene sets for phagocytosis- and cell-killing-associated genes. The cell-killing gene set in the neutrophil population uniquely expressed Lgals3, which encodes the multifunctional antibacterial protein, galectin-3. Intravital imaging for bacterial phagocytosis, assessment of bacterial killing and neutrophil-associated galectin-3 protein levels together with use of galectin-3-deficient mice collectively highlight neutrophils and galectin-3 as central players in LPS-mediated protection. Patients with acute respiratory failure revealed significantly higher galectin-3 levels in endotracheal aspirates (ETAs) of survivors compared to non-survivors, galectin-3 levels strongly correlating with a neutrophil signature in the ETAs and a prognostically favorable hypoinflammatory plasma biomarker subphenotype. Taken together, our study provides impetus for harnessing the potential of galectin-3-expressing neutrophils to protect from lethal infections and respiratory failure.

Clinical and economic outcomes associated with lymph node examination status in early-stage non-small cell lung cancer: a real-world US study using the SEER-Medicare linked database.

Background: Clinical practice guidelines recommend adjuvant therapy for patients with early non-small cell lung cancer (eNSCLC), especially those with lymph node metastasis. This study evaluated the prevalence of lymph node examination and its association with adjuvant treatment rates, overall survival (OS), and healthcare costs among United States (US) Medicare patients with resected eNSCLC. Methods: This retrospective observational cohort study used Surveillance, Epidemiology, and End Results cancer registry data linked with Medicare claims data. Eligible patients were aged ≥65 years with newly diagnosed non-small cell lung cancer (NSCLC) stages IA to IIIB [the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, 7th edition] between January 2010 and December 2017 with surgery ≤1 month prior to or ≤12 months after diagnosis. Patients were grouped by lymph node examination status: no examination (pNX), examination and no metastasis (pN0), or metastasis staging in N1 (pN1) or N2 (pN2). OS and costs were evaluated by examination status and number of lymph node examined. OS was analyzed using extended Cox proportional hazards models for specific time periods and time interaction with examination status, and adjusted for patient characteristics. Adjusted post-surgical healthcare costs per patient per month (PPPM) were analyzed using gamma-log regression models. Results: Among the 14,648 patients included in the study, approximately 11% were pNX, whereas most were pN0 (68%), followed by pN1 (11%) and pN2 (10%). Adjuvant treatment rates were higher for pNX (35%) than pN0 (18%), but lower than pN1 (68%) and pN2 (74%) patients (P<0.001). Unadjusted OS for pNX patients was nearly identical to pN2, and significantly worse compared to pN0 and pN1 (P<0.0001). After adjusting for patient characteristics, pNX patients had higher risk of death relative to pN0 patients (P<0.001). Marginal mean adjusted total costs were comparable across pNX ($15,827 PPPM), pN0 ($12,712 PPPM) and pN1 ($17,089 PPPM), but significantly less for pN0 compared to pN2 ($23,566 PPPM) (P=0.002). Conclusions: Inadequate lymph node examination is associated with underutilization of adjuvant treatment and poor OS in resected NSCLC. In the current era of targeted and immunotherapies, lymph node examination is more important than ever, implicating the need for Quality Improvement practices and multidisciplinary coordination.

Increased Neutrophil H2O2 Production and Enhanced Pulmonary Clearance of Klebsiella pneumoniae in G6PD A- Mice.

The X-linked A- variant (rs1050828, Val68Met) in G6PDX accounts for glucose-6-phosphate (G6PD) deficiency in approximately 11% of African American males. This common, hypomorphic variant may impact pulmonary host defense and phagocyte function during pneumonia by altering levels of reactive oxygen species produced by host leukocytes. We used CRISPR-Cas9 technology to generate novel mouse strain with "humanized" G6PD A- variant containing non-synonymous Val68Met single nucleotide polymorphism. Male hemizygous or littermate wild-type (WT) controls were inoculated intratracheally with K. pneumoniae (KP2 serotype, ATCC 43816 strain,103 CFU inoculum). We examined leukocyte recruitment, organ bacterial burden, bone marrow neutrophil and macrophage (BMDM) phagocytic capacity, and hydrogen peroxide (H2O2) production. Unexpectedly, G6PD-deficient mice showed decreased lung bacterial burden (p=0.05) compared to controls 24-h post-infection. Extrapulmonary dissemination and bacteremia were significantly reduced in G6PD-deficient mice 48-h post-infection. Bronchoalveolar lavage fluid (BALF) IL-10 levels were elevated in G6PD-deficient mice (p=0.03) compared to controls at 24-h but were lower at 48-h (p=0.03). G6PD A- BMDMs show mildly decreased in vitro phagocytosis of pHrodo-labeled KP2 (p=0.03). Baseline, but not stimulated, H2O2 production by G6PD A- neutrophils was greater compared to WT neutrophils. G6PD A- variant demonstrate higher basal neutrophil H2O2 production and are protected against acute Klebsiella intrapulmonary infection.

Socioeconomic factors associated with uptake and satisfaction with a post-hospitalization meals benefit in Medicare Advantage.

BACKGROUND: Kaiser Permanente Southern California began offering a 4-week supplemental benefit of home-delivered meals to Medicare Advantage members after discharge from a hospitalization for heart failure and other medical conditions in 2021. The purpose of this study is to explore the associations between socioeconomic disadvantage and food insecurity with patient uptake of and satisfaction with the meals. METHODS: Data for this cross-sectional study were drawn from survey and electronic medical record data for members referred for the meals benefit (n = 6169) and linked to a hospitalization encounter (n = 2254) between January and December 2021. Uptake was assessed using vendor records; measures of socioeconomic status included the neighborhood deprivation index (NDI) and prior receipt of medical financial assistance (MFA) from the health system. Patients were invited to complete an email or phone survey about their satisfaction with the meals and food insecurity. Multivariable log-binomial regression models were used to examine the association between socioeconomic disadvantage and food insecurity with meals uptake and satisfaction. RESULTS: Sixty-two percent of patients referred for the benefit accepted the meals (mean age: 79 ± 9, 59% people of color). While there was no significant relationship between NDI and meals uptake (RR: 0.99, 95% CI: 0.92-1.07, p = 0.77), patients who received prior MFA were more likely to accept the meals (RR: 1.09, 95% CI: 1.02-1.16, p < 0.01). Sixty-nine percent of patients who completed the survey (23% response rate) reported that meals were very or extremely helpful. Patients with food insecurity (29% of survey respondents) were more likely to report that the meals were helpful for their recovery compared to food secure patients (RR: 1.21, 95% CI: 1.09-1.35, p < 0.01). CONCLUSIONS: The home-delivered meals appeared to be particularly utilized by and helpful to patients with greater financial strain and/or food insecurity, suggesting that supplemental benefits could be more targeted toward addressing unmet needs of vulnerable adults.

Association Between Intensity and Timing of Specialty Palliative Care and Hospice Exposure With Quality of End-of-Life Care.

Background: Gaps remain in our understanding of the intensity and timing of specialty palliative care (SPC) exposure on end-of-life (EOL) outcomes. Objective: Examine the association between intensity and timing of SPC and hospice (HO) exposure on EOL care outcomes. Design, Settings, Participants: Data for this cohort study were drawn from 2021 adult decedents from Kaiser Permanente Southern California and Colorado (n = 26,251). Caregivers of a decedent subgroup completed a postdeath care experience survey from July to August 2022 (n = 424). Measurements: SPC intensity (inpatient, outpatient, and home-based) and HO exposure in the five years before death were categorized as: (1) No SPC or HO; (2) SPC-only; (3) HO-only; and (4) SPC-HO. Timing of SPC exposure (<90 or 90+ days) before death was stratified by HO enrollment. Death in the hospital and potentially burdensome treatments in the last 14 days of life were extracted from electronic medical records (EMRs) and claims. EOL care experience was obtained from the caregiver survey. Results: Among the EMR cohort, exposure to SPC and HO were: No SPC or HO (38%), SPC-only (14%; of whom, 55% received inpatient SPC only), HO-only (20%), and SPC-HO (28%). For decedents who did not enroll in HO, exposure to SPC 90+ days versus <90 days before death was associated with lower risk of receiving potentially burdensome treatments (adjusted relative risk, aRR: 0.69 [95% confidence interval, CI: 0.62-0.76], p < 0.001) and 23% lower risk of dying in the hospital (aRR: 0.77 [95% CI: 0.73-0.81], p < 0.001). Caregivers of patients in the HO-only (aRR: 1.27 [95% CI: 0.98-1.63], p = 0.07) and SPC-HO cohorts (aRR: 1.19 [95% CI: 0.93-1.52], p = 0.18) tended to report more positive care experience compared to the no SPC or HO cohort. Conclusion: Earlier exposure to SPC was important in reducing potentially burdensome treatments and death in the hospital for decedents who did not enroll in HO. Increasing availability and access to community-based SPC is needed.

Siderophores promote cooperative interspecies and intraspecies cross-protection against antibiotics in vitro.

The antibiotic cefiderocol hijacks iron transporters to facilitate its uptake and resists ß-lactamase degradation. While effective, resistance has been detected clinically with unknown mechanisms. Here, using experimental evolution, we identified cefiderocol resistance mutations in Pseudomonas aeruginosa. Resistance was multifactorial in host-mimicking growth media, led to multidrug resistance and paid fitness costs in cefiderocol-free environments. However, kin selection drove some resistant populations to cross-protect susceptible individuals from killing by increasing pyoverdine secretion via a two-component sensor mutation. While pyochelin sensitized P. aeruginosa to cefiderocol killing, pyoverdine and the enterobacteria siderophore enterobactin displaced iron from cefiderocol, preventing uptake by susceptible cells. Among 113 P. aeruginosa intensive care unit clinical isolates, pyoverdine production directly correlated with cefiderocol tolerance, and high pyoverdine producing isolates cross-protected susceptible P. aeruginosa and other Gram-negative bacteria. These in vitro data show that antibiotic cross-protection can occur via degradation-independent mechanisms and siderophores can serve unexpected protective cooperative roles in polymicrobial communities.

Effectiveness and safety of early treatment with spironolactone for new-onset acute heart failure.

BACKGROUND: The effectiveness and safety of mineralocorticoid receptor antagonists (MRA) in acute heart failure (HF) is uncertain. We sought to describe the prescription of spironolactone during acute HF and whether early treatment is effective and safe in a real-world setting. METHODS: We performed a retrospective cohort study of adult (≥18 years) nonpregnant patients hospitalized with new-onset HF with reduced ejection fraction (HFrEF, defined by ejection fraction ≤40%) within 15 Kaiser Permanente Southern California medical centers between 2016 and 2021. Early treatment was defined by spironolactone prescription at discharge. The primary effectiveness outcome was a composite of HF readmission or all-cause mortality at 180 days. Safety outcomes were hypotension and hyperkalemia at 90 days. RESULTS: Among 2318 HFrEF patients, 368 (15.9%) were treated with spironolactone at discharge. After 1:2 propensity score matching, 354 early treatment and 708 delayed/no treatment patients were included in the analysis. The median age was 63 (IQR: 52-74) years; 61.6% were male, and 38.6% were White. By 90 days, ~20% had crossed over in the two groups. Early treatment was not associated with the composite outcome at 180 days (HR [95% CI]: 0.81 [0.56-1.17]), but a trend towards benefit by 365 days that did not reach statistical significance (0.78 [0.58-1.06]). Early treatment was also associated with hyperkalemia (subdistribution HR [95% CI]: 2.33 [1.30-4.18]) but not hypotension (0.93 [0.51-1.72]). CONCLUSIONS: Early treatment with spironolactone at discharge for new-onset HFrEF in a real-world setting did not reduce the risk of HF readmission or mortality in the first year after discharge. The risk of hyperkalemia was increased.

Functional effects of an African glucose-6-phosphate dehydrogenase (G6PD) polymorphism (Val68Met) on red blood cell hemolytic propensity and post-transfusion recovery.

BACKGROUND: Donor genetic variation is associated with red blood cell (RBC) storage integrity and post-transfusion recovery. Our previous large-scale genome-wide association study demonstrated that the African G6PD deficient A- variant (rs1050828, Val68Met) is associated with higher oxidative hemolysis after cold storage. Despite a high prevalence of X-linked G6PD mutation in African American population (>10%), blood donors are not routinely screened for G6PD status and its importance in transfusion medicine is relatively understudied. STUDY DESIGN AND METHODS: To further evaluate the functional effects of the G6PD A- mutation, we created a novel mouse model carrying this genetic variant using CRISPR-Cas9. We hypothesize that this humanized G6PD A- variant is associated with reduced G6PD activity with a consequent effect on RBC hemolytic propensity and post-transfusion recovery. RESULTS: G6PD A- RBCs had reduced G6PD protein with ~5% residual enzymatic activity. Significantly increased in vitro hemolysis induced by oxidative stressors was observed in fresh and stored G6PD A- RBCs, along with a lower GSH:GSSG ratio. However, no differences were observed in storage hemolysis, osmotic fragility, mechanical fragility, reticulocytes, and post-transfusion recovery. Interestingly, a 14% reduction of 24-h survival following irradiation was observed in G6PD A- RBCs compared to WT RBCs. Metabolomic assessment of stored G6PD A- RBCs revealed an impaired pentose phosphate pathway (PPP) with increased glycolytic flux, decreasing cellular antioxidant capacity. DISCUSSION: This novel mouse model of the common G6PD A- variant has impaired antioxidant capacity like humans and low G6PD activity may reduce survival of transfused RBCs when irradiation is performed.

Lung Epithelium Releases Growth Differentiation Factor 15 in Response to Pathogen-mediated Injury.

GDF15 (growth differentiation factor 15) is a stress cytokine with several proposed roles, including support of stress erythropoiesis. Higher circulating GDF15 levels are prognostic of mortality during acute respiratory distress syndrome, but the cellular sources and downstream effects of GDF15 during pathogen-mediated lung injury are unclear. We quantified GDF15 in lower respiratory tract biospecimens and plasma from patients with acute respiratory failure. Publicly available data from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were reanalyzed. We used mouse models of hemorrhagic acute lung injury mediated by Pseudomonas aeruginosa exoproducts in wild-type mice and mice genetically deficient for Gdf15 or its putative receptor, Gfral. In critically ill humans, plasma levels of GDF15 correlated with lower respiratory tract levels and were higher in nonsurvivors. SARS-CoV-2 infection induced GDF15 expression in human lung epithelium, and lower respiratory tract GDF15 levels were higher in coronavirus disease (COVID-19) nonsurvivors. In mice, intratracheal P. aeruginosa type II secretion system exoproducts were sufficient to induce airspace and plasma release of GDF15, which was attenuated with epithelial-specific deletion of Gdf15. Mice with global Gdf15 deficiency had decreased airspace hemorrhage, an attenuated cytokine profile, and an altered lung transcriptional profile during injury induced by P. aeruginosa type II secretion system exoproducts, which was not recapitulated in mice deficient for Gfral. Airspace GDF15 reconstitution did not significantly modulate key lung cytokine levels but increased circulating erythrocyte counts. Lung epithelium releases GDF15 during pathogen injury, which is associated with plasma levels in humans and mice and can increase erythrocyte counts in mice, suggesting a novel lung-blood communication pathway.

Association Between Coronary Artery Disease Testing in Patients with New-Onset Heart Failure and Heart Failure Readmission and Mortality.

BACKGROUND: In patients with new-onset heart failure (HF), coronary artery disease (CAD) testing remains underutilized. Whether widespread CAD testing in patients with new-onset HF leads to improved outcomes remains to be determined. OBJECTIVE: We sought to examine whether CAD testing, and its timing, among patients hospitalized with new-onset HF with reduced ejection fraction (HFrEF), is associated with improved outcomes. DESIGN: Retrospective cohort study. PARTICIPANTS: Adult (≥ 18 years) non-pregnant patients with new-onset HFrEF hospitalized within one of 15 Kaiser Permanente Southern California medical centers between 2016 and 2021. Key exclusion criteria included history of heart transplant, hospice, and a do-not-resuscitate order. MAIN MEASURES: Primary outcome was a composite of HF readmission or all-cause mortality through end of follow-up on 12/31/2022. KEY RESULTS: Among 2729 patients hospitalized with new-onset HFrEF, 1487 (54.5%) received CAD testing. The median age was 66 (56-76) years old, 1722 (63.1%) were male, and 1074 (39.4%) were White. After a median of 1.8 (0.6-3.4) years, the testing group had a reduced risk of HF readmission or all-cause mortality (aHR [95%CI], 0.71 [0.63-0.79]). These results were consistent across subgroups by history of atrial fibrillation, diabetes, renal disease, myocardial infarction, and elevated troponin during hospitalization. In a secondary analysis where CAD testing was further divided to early (received testing before discharge) and late testing (up to 90 days after discharge), there was no difference in late vs early testing (0.97 [0.81-1.16]). CONCLUSIONS: In a contemporary and diverse cohort of patients hospitalized with new-onset HFrEF, CAD testing within 90 days of hospitalization was associated with a lower risk of HF readmission or all-cause mortality. Testing within 90 days after discharge was not associated with worse outcomes.

STAT1 Employs Myeloid Cell-Extrinsic Mechanisms to Regulate the Neutrophil Response and Provide Protection against Invasive Klebsiella pneumoniae Lung Infection.

Klebsiella pneumoniae (KP) is an extracellular Gram-negative bacterium that causes infections in the lower respiratory and urinary tracts and the bloodstream. STAT1 is a master transcription factor that acts to maintain T cell quiescence under homeostatic conditions. Although STAT1 helps defend against systemic spread of acute KP intrapulmonary infection, whether STAT1 regulation of T cell homeostasis impacts pulmonary host defense during acute bacterial infection and injury is less clear. Using a clinical KP respiratory isolate and a pneumonia mouse model, we found that STAT1 deficiency led to an early neutrophil-dominant transcriptional profile and neutrophil recruitment in the lung preceding widespread bacterial dissemination and lung injury development. Yet, myeloid cell STAT1 was dispensable for control of KP proliferation and dissemination, because myeloid cell-specific STAT1-deficient (LysMCre/WT;Stat1fl/fl) mice showed bacterial burden in the lung, liver, and kidney similar to that of their wild-type littermates. Surprisingly, IL-17-producing CD4+ T cells infiltrated Stat1-/- murine lungs early during KP infection. The increase in Th17 cells in the lung was not due to preexisting immunity against KP and was consistent with circulating rather than tissue-resident CD4+ T cells. However, blocking global IL-17 signaling with anti-IL-17RC administration led to increased proliferation and dissemination of KP, suggesting that IL-17 provided by other innate immune cells is essential in defense against KP. Contrastingly, depletion of CD4+ T cells reduced Stat1-/- murine lung bacterial burden, indicating that early CD4+ T cell activation in the setting of global STAT1 deficiency is pathogenic. Altogether, our findings suggest that STAT1 employs myeloid cell-extrinsic mechanisms to regulate neutrophil responses and provides protection against invasive KP by restricting nonspecific CD4+ T cell activation and immunopathology in the lung.

In vivo evolution of a Klebsiella pneumoniae capsule defect with wcaJ mutation promotes complement-mediated opsono-phagocytosis during recurrent infection.

BACKGROUND: Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) bloodstream infections are associated with high mortality. We studied clinical bloodstream KPC-Kp isolates to investigate mechanisms of resistance to complement, a key host defense against bloodstream infection. METHODS: We tested growth of KPC-Kp isolates in human serum. In serial isolates from a single patient, we performed whole genome sequencing and tested for complement resistance and binding by mixing study, direct ELISA, flow cytometry, and electron microscopy. We utilized an isogenic deletion mutant in phagocytosis assays and an acute lung infection model. RESULTS: We found serum resistance in 16 of 59 (27%) KPC-Kp clinical bloodstream isolates. In five genetically-related bloodstream isolates from a single patient, we noted a loss-of-function mutation in the capsule biosynthesis gene, wcaJ. Disruption of wcaJ was associated with decreased polysaccharide capsule, resistance to complement-mediated killing, and surprisingly, increased binding of complement proteins. Furthermore, an isogenic wcaJ deletion mutant exhibited increased opsono-phagocytosis in vitro and impaired in vivo control in the lung after airspace macrophage depletion in mice. CONCLUSIONS: Loss of function in wcaJ led to increased complement resistance, complement binding, and opsono-phagocytosis, which may promote KPC-Kp persistence by enabling co-existence of increased bloodstream fitness and reduced tissue virulence.

Rates of diabetic ketoacidosis with empagliflozin use during hospitalization for acute heart failure.

There is concern that sodium-glucose cotransporter-2 inhibitors during hospitalization for acute heart failure (aHF) may precipitate diabetic ketoacidosis (DKA). A retrospective study of all hospitalization encounters for aHF defined by a primary HF International Classification of Diseases (ICD)-10 code in 15 Kaiser Permanente Southern California medical centers hospitalized between January 1, 2021 and August 31, 2023 was performed to describe rates of DKA with empagliflozin use. DKA was defined by the presence of either a DKA ICD-10 code or ketoacidosis lab criteria (bicarbonate <18 mmol/L and urine ketone 1+ or more or elevated serum beta-hydroxybutyrate within 12 h) during hospitalization. Among 21,630 hospital encounters (15,518 patients) for aHF, 1678 (8%) had empagliflozin use. There were 2 (0.1%) probable DKA cases in empagliflozin encounters and 15 (0.1%) in nonexposed encounters. These rates were similar when stratified by diabetes status and ejection fraction. Empagliflozin may be safe during aHF hospitalization.

Telehealth transitional care and 30-day readmission during the COVID-19 pandemic.

Transitional care management (TCM) services after hospital discharge are critical for continuity of care, and the COVID-19 pandemic accelerated the shift to telehealth modes of delivery. This study examined the shift from face-to-face to telehealth care around the start of the pandemic (April-July 2020) compared with the same months in 2019 and 2021 and the corresponding 30-day readmission rates. We compared the rates of face-to-face and telehealth TCM as well as face-to-face and telehealth non-TCM services and observed a dramatic shift to telehealth in 2020 with a slight drop-off in 2021. For TCM services specifically, face-to-face visits made up nearly 90% of visits in 2019, whereas telehealth made up the vast majority in 2020 and 2021 at 97.5% and 84.9%, respectively. Over the same time periods, 30-day readmission rates remained steady at 10% along with no changes in 30-day mortality. Among those who completed TCM visits, 30-day readmission rates remained between 8% and 9% and 30-day mortality remained below 1%. These data indicate that this dramatic systemwide shift from face-to-face to telehealth TCM was not accompanied by concurrent changes in either 30-day readmission or mortality rates. Although the findings may be subject to ecologic bias, the data at hand did not allow for reliable estimation of differences in effects of patient-level service delivery type on readmission risk or mortality due to the extremely low volume of face-to-face visits during the pandemic periods. Future research would be needed to conduct such comparisons.

BATF2 enhances proinflammatory cytokine responses in macrophages and improves early host defense against pulmonary Klebsiella pneumoniae infection.

Basic leucine zipper transcription factor ATF-like 2 (BATF2) is a transcription factor that is emerging as an important regulator of the innate immune system. BATF2 is among the top upregulated genes in human alveolar macrophages treated with LPS, but the signaling pathways that induce BATF2 expression in response to Gram-negative stimuli are incompletely understood. In addition, the role of BATF2 in the host response to pulmonary infection with a Gram-negative pathogen like Klebsiella pneumoniae (Kp) is not known. We show that induction of Batf2 gene expression in macrophages in response to Kp in vitro requires TRIF and type I interferon (IFN) signaling, but not MyD88 signaling. Analysis of the impact of BATF2 deficiency on macrophage effector functions in vitro showed that BATF2 does not directly impact macrophage phagocytic uptake and intracellular killing of Kp. However, BATF2 markedly enhanced macrophage proinflammatory gene expression and Kp-induced cytokine responses. In vivo, Batf2 gene expression was elevated in lung tissue of wild-type (WT) mice 24 h after pulmonary Kp infection, and Kp-infected BATF2-deficient (Batf2-/-) mice displayed an increase in bacterial burden in the lung, spleen, and liver compared with WT mice. WT and Batf2-/- mice showed similar recruitment of leukocytes following infection, but in line with in vitro observations, proinflammatory cytokine levels in the alveolar space were reduced in Batf2-/- mice. Altogether, these results suggest that BATF2 enhances proinflammatory cytokine responses in macrophages in response to Kp and contributes to the early host defense against pulmonary Kp infection.NEW & NOTEWORTHY This study investigates the signaling pathways that mediate induction of BATF2 expression downstream of TLR4 and also the impact of BATF2 on the host defense against pulmonary Kp infection. We demonstrate that Kp-induced upregulation of BATF2 in macrophages requires TRIF and type I IFN signaling. We also show that BATF2 enhances Kp-induced macrophage cytokine responses and that BATF2 contributes to the early host defense against pulmonary Kp infection.

Help a mother out: The impact of acute care surgeon response in postpartum hemorrhage.

INTRODUCTION: A Code White (CW) activation is a hospital-wide alert for postpartum hemorrhage (PPH) and acute care surgeons (ACS) were added to the response team to assist in resuscitation. A multidisciplinary training program was also implemented. This study aimed to evaluate the impact of ACS involvement and training on maternal outcomes. METHODS: A retrospective review was performed on all CW activations from 1/1/2015-8/31/2022. Three groups-pre-ACS response, ACS response, and ACS response â€‹+ â€‹training (R&T)-were compared. RESULTS: 218 patients had CW activations. ACS response increased MTP activations (50.0%vs76.5%vs76.2%, p â€‹= â€‹0.014) and TXA administration (50.0%vs96.5%vs93.3%, p â€‹< â€‹0.0001). The ACS R&T had the highest ACS presence (53.6%vs72.9%vs96.2%, p â€‹< â€‹0.0001), shortest operation (99 vs 67 vs 53min, p â€‹= â€‹0.002), lowest crystalloid use (2000 vs 1110 vs 800 â€‹ml, p â€‹= â€‹0.003), and lowest transfusion requirements. Mortality decreased from 17.9% in pre-ACS to 2.4% in ACS response and 0% in ACS R&T (p â€‹< â€‹0.0001). CONCLUSION: ACS assistance in CW activations and multidisciplinary PPH education led to the prevention of maternal mortality. ACS are a valuable resource in this unique population.

In vivo evolution of a Klebsiella pneumoniae capsule defect promotes complement-mediated opsono-phagocytosis and persistence during recurrent infection.

Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) bloodstream infections rarely overwhelm the host but are associated with high mortality. The complement system is a key host defense against bloodstream infection. However, there are varying reports of serum resistance among KPC-Kp isolates. We assessed growth of 59 KPC-Kp clinical isolates in human serum and found increased resistance in 16/59 (27%). We identified five genetically-related bloodstream isolates with varying serum resistance profiles collected from a single patient during an extended hospitalization marked by recurrent KPC-Kp bloodstream infections. We noted a loss-of-function mutation in the capsule biosynthesis gene, wcaJ, that emerged during infection was associated with decreased polysaccharide capsule content, and resistance to complement-mediated killing. Surprisingly, disruption of wcaJ increased deposition of complement proteins on the microbial surface compared to the wild-type strain and led to increased complement-mediated opsono-phagocytosis in human whole blood. Disabling opsono-phagocytosis in the airspaces of mice impaired in vivo control of the wcaJ loss-of-function mutant in an acute lung infection model. These findings describe the rise of a capsular mutation that promotes KPC-Kp persistence within the host by enabling co-existence of increased bloodstream fitness and reduced tissue virulence.