Inflammatory and tissue injury marker dynamics in pediatric acute respiratory distress syndrome

BACKGROUND

The molecular signature of pediatric acute respiratory distress syndrome (ARDS) is poorly described, and the degree to which hyperinflammation or specific tissue injury contributes to outcomes is unknown. Therefore, we profiled inflammation and tissue injury dynamics over the first 7 days of ARDS, and associated specific biomarkers with mortality, persistent ARDS, and persistent multiple organ dysfunction syndrome (MODS).

METHODS

In a single-center prospective cohort of intubated pediatric ARDS, we collected plasma on days 0, 3, and 7. Nineteen biomarkers reflecting inflammation, tissue injury, and damage associated molecular patterns were measured. We assessed the relationship between biomarkers and trajectories with mortality, persistent ARDS, or persistent MODS using multivariable mixed effect models.

RESULTS

In 279 subjects (64 [23%] non-survivors), hyperinflammatory cytokines, tissue injury markers, and DAMPs were higher in non-survivors. Survivors and non-survivors showed different biomarker trajectories. IL-1α, sTNFR1, ANG2, and SPD increased in non-survivors, while DAMPs remained persistently elevated. ANG2 and P3NP were associated with persistent ARDS, whereas multiple cytokines, tissue injury markers, and DAMPs were associated with persistent MODS. Corticosteroid use did not impact the association of biomarker levels or trajectory with mortality.

CONCLUSIONS

Pediatric ARDS survivors and non-survivors had distinct biomarker trajectories, with cytokines, endothelial and alveolar epithelial injury, and DAMPs elevated in non-survivors. Mortality markers overlapped with markers associated with persistent MODS, rather than persistent ARDS.

SP-R210 isoforms of Myosin18A modulate endosomal sorting and recognition of influenza A virus infection in macrophages

Influenza A virus (IAV) infection causes acute and often lethal inflammation in the lung. The role of macrophages in this adverse inflammation is partially understood. The surfactant protein A receptor 210 (SP-R210) consists of two isoforms, a long (L) SP-R210L and a short (S) SP-R210S isoform encoded by alternative splicing of the myosin 18A gene. We reported that disruption of SP-R210L enhances cytosolic and endosomal antiviral response pathways. Here, we report that SP-R210L antagonizes type I interferon β (IFNβ), as depletion of SP-R210L potentiates IFNβ secretion. SP-R210 antibodies enhance and attenuate IFNβ secretion in SP-R210L replete and deficient macrophages, respectively, indicating that SP-R210 isoform stoichiometry alters macrophage function intrinsically. This reciprocal response is coupled to unopposed and restricted expression of viral genes in control and SP-R210L-deficient macrophages, respectively. Human monocytic cells with sub-stoichiometric expression of SP-R210L resist IAV infection, whereas alveolar macrophages with increased abundance of SP-R210L permit viral gene expression similar to murine macrophages. Uptake and membrane binding studies show that lack of SP-R210 isoforms does not impair IAV binding and internalization. Lack of SP-R210L, however, results in macropinocytic retention of the virus that depends on both SP-R210S and interferon-inducible transmembrane protein-3 (IFITM3). Mass spectrometry and Western blot analyses indicate that SP-R210 isoforms modulate differential recruitment of the Rho-family GTPase RAC1 and guanine nucleotide exchange factors. Our study suggests that SP-R210 isoforms modulate RAC-dependent macropinosomal sorting of IAV to discrete endosomal and lysosomal compartments that either permit or prevent endolysosomal escape and inflammatory sensing of viral genomes in macrophages.

Identification of molecular subphenotypes in two cohorts of paediatric ARDS

BACKGROUND

Two subphenotypes of acute respiratory distress syndrome (ARDS), hypoinflammatory and hyperinflammatory, have been reported in adults and in a single paediatric cohort. The relevance of these subphenotypes in paediatrics requires further investigation. We aimed to identify subphenotypes in two large observational cohorts of paediatric ARDS and assess their congruence with prior descriptions.

METHODS

We performed latent class analysis (LCA) separately on two cohorts using biomarkers as inputs. Subphenotypes were compared on clinical characteristics and outcomes. Finally, we assessed overlap with adult cohorts using parsimonious classifiers.

FINDINGS

In two cohorts from the Children's Hospital of Philadelphia (n=333) and from a multicentre study based at the University of California San Francisco (n=293), LCA identified two subphenotypes defined by differential elevation of biomarkers reflecting inflammation and endotheliopathy. In both cohorts, hyperinflammatory subjects had greater illness severity, more sepsis and higher mortality (41% and 28% in hyperinflammatory vs 11% and 7% in hypoinflammatory). Both cohorts demonstrated overlap with adult subphenotypes when assessed using parsimonious classifiers.

INTERPRETATION

We identified hypoinflammatory and hyperinflammatory subphenotypes of paediatric ARDS from two separate cohorts with utility for prognostic and potentially predictive, enrichment. Future paediatric ARDS trials should identify and leverage biomarker-defined subphenotypes in their analysis.

Case Report: Successful avoidance of etoposide for primary hemophagocytic lymphohistiocytosis-induced multiple organ dysfunction syndrome using emapalumab

We describe the case of an infant who presented with simple rhinovirus/enterovirus bronchiolitis whose condition worsened with rapid progression to multiple organ dysfunction syndrome (MODS). The patient was presumed to have either primary or secondary hemophagocytic lymphohistiocytosis (HLH), and treatment was initiated using dexamethasone, anakinra, and intravenous immunoglobulin to modulate the immune system. Due to the organ dysfunction, the use of etoposide was avoided and instead, emapalumab, an interferon gamma antagonist, was administered at a dose of 6 mg/kg. The patient's organ failure improved, and the levels of inflammatory markers decreased. The flow cytometry analysis revealed that cytotoxic cells lacked perforin expression, and subsequent genetic analysis confirmed homozygous pathogenic mutations in the perforin gene. This case highlights the potential avoidance of etoposide in cases of primary HLH, the possible benefit of an elevated initial dose of emapalumab, and the contribution offered by a multi-specialty team approach to complex diagnosis.

Ex Vivo Endotoxin Stimulation of Blood for Predicting Survival in Patients With Sepsis: A Systematic Review

BACKGROUND

Sepsis is a syndrome characterized by host immune dysfunction, with the extent of immunoparalysis differing among patients. Lipopolysaccharide (LPS) is used commonly to assess the immune function of critically ill patients with sepsis. However, the reliability of this ex vivo diagnostic test in predicting clinical outcomes remains uncertain.

RESEARCH QUESTION

Does LPS-induced tumor necrosis factor (TNF) production from the blood of patients with sepsis predict mortality? Secondary outcomes included ICU and hospital stay durations, nosocomial infection rate, and organ recovery rate.

STUDY DESIGN AND METHODS

Human sepsis studies from various databases through April 2023 were evaluated. Inclusion criteria encompassed LPS-stimulated blood assays, English language, and reported clinical outcomes. Bias risk was evaluated using the Newcastle-Ottawa scale (NOS). Relationships between TNF production and mortality were analyzed at sepsis onset and during established sepsis, alongside secondary outcomes.

RESULTS

Of 11,580 studies, 17 studies (14 adult and three pediatric) were selected for analysis. Although 15 studies were evaluated as moderate to high quality using the NOS, it is important to note that some of these studies also had identifiable biases, such as unclear methods of participant recruitment. Nine studies detailed survival outcomes associated with LPS-induced TNF production at sepsis onset, whereas five studies explored TNF production's relationship with mortality during established sepsis. Trends suggested that lower LPS-induced TNF production correlated with higher mortality. However, heterogeneity in methodologies, especially the LPS assay protocol, hindered definitive conclusions. Publication bias was highlighted using funnel plot analysis. Concerning secondary outcomes, diminished TNF production might signify worsening organ dysfunction, although the link between cytokine production and nosocomial infection varied among studies.

INTERPRETATION

For functional immune profiling in sepsis, streamlined research methodologies are essential. This entails organizing cohorts based on microbial sources of sepsis, establishing standardized definitions of immunoparalysis, using consistent types and dosages of immune stimulants, adhering to uniform blood incubation conditions, and adopting consistent clinical outcomes.

Comparison of whole blood cytokine immunoassays for rapid, functional immune phenotyping in critically ill patients with sepsis

BACKGROUND

Sepsis is characterized by highly heterogeneous immune responses associated with a spectrum of disease severity. Methods that rapidly and sensitively profile these immune responses can potentially personalize immune-adjuvant therapies for sepsis. We hypothesized that the ELLA microfluidic approach to measure cytokine production from the whole blood of septic and critically ill patients would deliver faster, more precise results than the existing optic-driven ELISpot quantification. We tested our hypothesis by measuring ex vivo-stimulated production of TNF and IFNγ in critically ill and septic patients (n = 22), critically ill and non-septic patients (n = 10), and healthy volunteers (n = 10) through both ELLA and ELISpot immunoassays. Blood samples were subjected to one of three stimulants for 4 h or 18 h durations during days 1, 7-10, and 14 of critical illness. Stimulants for lymphocytes included anti-CD3/anti-CD28 and phorbol 12-myristate 13-acetate (PMA), whereas LPS was used for monocytes. Stimulated TNF and IFNγ concentrations were then associated with 30-day mortality.

RESULTS

Both ELISpot and ELLA immunoassays showed substantial agreement in TNF concentrations post 4 h and 18 h LPS stimulation, with concordance correlation coefficients at 0.62 and 0.60, respectively. ELLA had a broad dynamic measurement range and provided accurate TNF and IFNγ readings at both minimal and elevated cytokine concentrations (with mean coefficients of variation between triplicate readings at 2.1 ± 1.4% and 4.9 ± 7.2%, respectively). However, there was no association between the ELLA-determined cytokine concentrations on the first day of critical illness and 30-day mortality rate. In contrast, using the ELISpot for cytokine quantification revealed that non-survivors had reduced baseline TNF levels at 18 h, decreased LPS-induced TNF levels at 18 h, and diminished TNF levels post 4 h/18 h anti-CD3/28 stimulation.

CONCLUSIONS

Our study affirms the feasibility of obtaining dependable immune phenotyping data within 6 h of blood collection from critically ill patients, both septic and non-septic, using the ELLA immunoassay. Both ELLA and ELISpot can offer valuable insights into prognosis, therapeutic strategies, and the underlying mechanisms of sepsis development.

Mesenchymal stromal cells and alpha-1 antitrypsin have a strong synergy in modulating inflammation and its resolution

Rationale: Trauma, surgery, and infection can cause severe inflammation. Both dysregulated inflammation intensity and duration can lead to significant tissue injuries, organ dysfunction, mortality, and morbidity. Anti-inflammatory drugs such as steroids and immunosuppressants can dampen inflammation intensity, but they derail inflammation resolution, compromise normal immunity, and have significant adverse effects. The natural inflammation regulator mesenchymal stromal cells (MSCs) have high therapeutic potential because of their unique capabilities to mitigate inflammation intensity, enhance normal immunity, and accelerate inflammation resolution and tissue healing. Furthermore, clinical studies have shown that MSCs are safe and effective. However, they are not potent enough, alone, to completely resolve severe inflammation and injuries. One approach to boost the potency of MSCs is to combine them with synergistic agents. We hypothesized that alpha-1 antitrypsin (A1AT), a plasma protein used clinically and has an excellent safety profile, was a promising candidate for synergism. Methods: This investigation examined the efficacy and synergy of MSCs and A1AT to mitigate inflammation and promote resolution, using in vitro inflammatory assay and in vivo mouse acute lung injury model. The in vitro assay measured cytokine releases, inflammatory pathways, reactive oxygen species (ROS), and neutrophil extracellular traps (NETs) production by neutrophils and phagocytosis in different immune cell lines. The in vivo model monitored inflammation resolution, tissue healing, and animal survival. Results: We found that the combination of MSCs and A1AT was much more effective than each component alone in i) modulating cytokine releases and inflammatory pathways, ii) inhibiting ROS and NETs production by neutrophils, iii) enhancing phagocytosis and, iv) promoting inflammation resolution, tissue healing, and animal survival. Conclusion: These results support the combined use of MSCs, and A1AT is a promising approach for managing severe, acute inflammation.

Multi-Omic Factors Associated with Frequency of Upper Respiratory Infections in Developing Infants

Susceptibility to upper respiratory infections (URIs) may be influenced by host, microbial, and environmental factors. We hypothesized that multi-omic analyses of molecular factors in infant saliva would identify complex host-environment interactions associated with URI frequency. A cohort study involving 146 infants was used to assess URI frequency in the first year of life. Saliva was collected at 6 months for high-throughput multi-omic measurement of cytokines, microRNAs, transcripts, and microbial RNA. Regression analysis identified environmental (daycare attendance, atmospheric pollution, breastfeeding duration), microbial (Verrucomicrobia, Streptococcus phage), and host factors (miR-22-5p) associated with URI frequency (p < 0.05). These results provide pathophysiologic clues about molecular factors that influence URI susceptibility. Validation of these findings in a larger cohort could one day yield novel approaches to detecting and managing URI susceptibility in infants.

Surfactant protein A alters endosomal trafficking of influenza A virus in macrophages

Influenza A virus infection (IAV) often leads to acute lung injury that impairs breathing and can lead to death, with disproportionate mortality in children and the elderly. Surfactant Protein A (SP-A) is a calcium-dependent opsonin that binds a variety of pathogens to help control pulmonary infections by alveolar macrophages. Alveolar macrophages play critical roles in host resistance and susceptibility to IAV infection. The effect of SP-A on IAV infection and antiviral response of macrophages, however, is not understood. Here, we report that SP-A attenuates IAV infection in a dose-dependent manner at the level of endosomal trafficking, resulting in infection delay in a model macrophage cell line. The ability of SP-A to suppress infection was independent of its glycosylation status. Binding of SP-A to hemagglutinin did not rely on the glycosylation status or sugar binding properties of either protein. Incubation of either macrophages or IAV with SP-A slowed endocytic uptake rate of IAV. SP-A interfered with binding to cell membrane and endosomal exit of the viral genome as indicated by experiments using isolated cell membranes, an antibody recognizing a pH-sensitive conformational epitope on hemagglutinin, and microscopy. Lack of SP-A in mice enhanced IFNβ expression, viral clearance and reduced mortality from IAV infection. These findings support the idea that IAV is an opportunistic pathogen that co-opts SP-A to evade host defense by alveolar macrophages. Our study highlights novel aspects of host-pathogen interactions that may lead to better understanding of the local mechanisms that shape activation of antiviral and inflammatory responses to viral infection in the lung.

Inhaled Sargramostim (Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor) for COVID-19-Associated Acute Hypoxemia: Results of the Phase 2, Randomized, Open-Label Trial (iLeukPulm)

INTRODUCTION

Granulocyte-macrophage colony-stimulating factor (GM-CSF), a protein produced in the lung, is essential for pulmonary host defense and alveolar integrity. Prior studies suggest potential benefits in several pulmonary conditions, including acute respiratory distress syndrome and viral infections. This trial evaluated the effect of the addition of inhaled sargramostim (yeast-derived, glycosylated recombinant human GM-CSF) to standard of care (SOC) on oxygenation and clinical outcomes in patients with COVID-19-associated acute hypoxemia.

MATERIALS AND METHODS

A randomized, controlled, open-label trial of hospitalized adults with COVID-19-associated hypoxemia (oxygen saturation <93% on ≥2 L/min oxygen supplementation and/or PaO2/FiO2 <350) randomized 2:1 to inhaled sargramostim (125 mcg twice daily for 5 days) plus SOC versus SOC alone. Institutional SOC before and during the study was not limited. Primary outcomes were change in the alveolar-arterial oxygen gradient (P(A-a)O2) by day 6 and the percentage of patients intubated within 14 days. Safety evaluations included treatment-emergent adverse events. Efficacy analyses were based on the modified intent-to-treat population, the subset of the intent-to-treat population that received ≥1 dose of any study treatment (sargramostim and/or SOC). An analysis of covariance approach was used to analyze changes in oxygenation measures. The intubation rate was analyzed using the chi-squared test. All analyses are considered descriptive. The study was institutional review board approved.

RESULTS

In total, 122 patients were treated (sargramostim, n = 78; SOC, n = 44). The sargramostim arm experienced greater improvement in P(A-a)O2 by day 6 compared to SOC alone (least squares [LS] mean change from baseline [SE]: -102.3 [19.4] versus -30.5 [26.9] mmHg; LS mean difference: -71.7 [SE 33.2, 95% CI -137.7 to -5.8]; P = .033; n = 96). By day 14, 11.5% (9/78) of sargramostim and 15.9% (7/44) of SOC arms required intubation (P = .49). The 28-day mortality was 11.5% (9/78) and 13.6% (6/44) in the sargramostim and SOC arms, respectively (hazard ratio 0.85; P = .76). Treatment-emergent adverse events occurred in 67.9% (53/78) and 70.5% (31/44) on the sargramostim and SOC arms, respectively.

CONCLUSIONS

The addition of inhaled sargramostim to SOC improved P(A-a)O2, a measure of oxygenation, by day 6 in hospitalized patients with COVID-19-associated acute hypoxemia and was well tolerated. Inhaled sargramostim is delivered directly to the lung, minimizing systemic effects, and is simple to administer making it a feasible treatment option in patients in settings where other therapy routes may be difficult. Although proportionally lower rates of intubation and mortality were observed in sargramostim-treated patients, this study was insufficiently powered to demonstrate significant changes in these outcomes. However, the significant improvement in gas exchange with sargramostim shows this inhalational treatment enhances pulmonary efficiency in this severe respiratory illness. These data provide strong support for further evaluation of sargramostim in high-risk patients with COVID-19.

Integrated machine learning approaches for flow cytometric quantification of myeloid-derived suppressor cells in acute sepsis

Highly heterogeneous cell populations require multiple flow cytometric markers for appropriate phenotypic characterization. This exponentially increases the complexity of 2D scatter plot analyses and exacerbates human errors due to variations in manual gating of flow data. We describe a semi-automated workflow, based entirely on the Flowjo Graphical User Interface (GUI), that involves the stepwise integration of several, newly available machine learning tools for the analysis of myeloid-derived suppressor cells (MDSCs) in septic and non-septic critical illness. Supervised clustering of flow cytometric data showed correlation with, but significantly different numbers of, MDSCs as compared with the cell numbers obtained by manual gating. Neither quantification method predicted 30-day clinical outcomes in a cohort of 16 critically ill and septic patients and 5 critically ill and non-septic patients. Machine learning identified a significant decrease in the proportion of PMN-MDSC in critically ill and septic patients as compared with healthy controls. There was no difference between the proportion of these MDSCs in septic and non-septic critical illness.

Abstract P5-13-10: Elevated plasma IL-8 predicts for reduced outcomes in CCTG MA.38, a phase 2 randomized trial of palbociclib in ER+/HER2- metastatic breast cancer patients

Background: CCTG MA38 (NCT02630693) was a randomized phase II clinical trial that evaluated the efficacy of 2 dose schedules of palbociclib [100mg PO on continuous daily dose (CDD)] compared to 125mg PO daily for 3 weeks on/1 week off (STD) along with physician-choice of endocrine therapy in patients with ER+, HER- metastatic breast cancer (MBC) in the second-line setting. The final analysis indicated that palbociclib had comparable efficacy, safety and QOL for both treatment arms (SABCS 2018, abstr PD1-10). Our lab has reported that IL-8 was highly expressed by primary human breast cancers, and that higher pretreatment plasma IL-8 was significantly correlated with elevated bone resorption in HR+MBC patients (Kamalakar A et al. Bone 61:176-85, 2014). Most recently, our lab has reported that elevated serum IL-8 predicts for significantly reduced OS in 3 large metastatic cohorts of pancreatic (ASCO 2019, abstr 4131), prostate (ASCO 2020, abstr e17565) and breast cancer patients (ASCO 2020, abstr 1067). In this retrospective study, we investigated the prognostic value of pretreatment plasma IL-8 in CCTG MA38. Methods: 123 patients enrolled in MA38 were analyzed in this retrospective biomarker study. Serum IL-8 levels were measured using the ELLA immunoassay platform (ProteinSimple, San Jose, CA). Kaplan-Meier analysis and log-rank test were used to correlate plasma IL-8 levels with OS and progression-free survival (PFS). Results: In the total study cohort, pretreatment plasma IL-8 concentration had a median of 11.10 pg/ml, and 25% and 75% interquartiles of 7.36 and 15.00 pg/ml, respectively. In univariate analysis higher plasma IL-8 was a significant adverse biomarker for reduced PFS as a continuous variable (p = 0.01), at the median cutpoint (HR= 1.55, p=0.042), and in quartile cutpoints (HR=2.28, p=0.03, Q4 vs Q1). For OS, higher plasma IL-8 also trended significant for reduced OS at the median cutpoint (HR= 1.66, p=0.10). In multivariate analysis, higher plasma IL-8 also trended significant for reduced PFS (HR= 1.47, p=0.094). Conclusions: In the CCTG MA.38 trial, higher pre-treatment plasma IL-8 level was associated with reduced PFS, and is therefore an adverse prognostic biomarker for reduced outcome to the CDK 4/6 inhibitor palbociclib. Anti-IL-8 therapy combined with CDK 4/6 inhibitors should be evaluated in future trials to improve outcome in patients with higher circulating IL-8.

Citation Format: Hyma V Polimera, Dhirisha Bhatt, Lois E Shepherd, Karen Gelmon, Anil A Joy, Wendy R Parulekar, Monika Joshi, Suhail M Ali, Kim Leitzel, Cristina Truica, Monali Vasekar, Joseph J Drabick, Harry Menon, Neal Shah, Ashok Maddukuri, Prashanth Moku, E. Scott Halstead, Daniel McKeone, Todd M Umstead, BE Chen, Allan Lipton. Elevated plasma IL-8 predicts for reduced outcomes in CCTG MA.38, a phase 2 randomized trial of palbociclib in ER+/HER2- metastatic breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-10.

Biomarkers associated with mortality in pediatric patients with cardiac arrest and acute respiratory distress syndrome

AIMS

To identify plasma biomarkers associated with cardiac arrest in a cohort of children with acute respiratory distress syndrome (ARDS), and to assess the association of these biomarkers with mortality in children with cardiac arrest and ARDS (ARDS + CA).

METHODS

This was a secondary analysis of a single-center prospective cohort study of children with ARDS from 2014-2019 with 17 biomarkers measured. Clinical characteristics and biomarkers were compared between subjects with ARDS + CA and ARDS with univariate analysis. In a sub-cohort of ARDS + CA subjects, the association between biomarker levels and mortality was tested using univariate and bivariate logistic regression.

RESULTS

Biomarkers were measured in 333 subjects: 301 with ARDS (median age 5.3 years, 55.5% male) and 32 ARDS + CA (median age 8 years, 53.1% male). More arrests (69%) occurred out-of-hospital with a median CPR duration of 11 (IQR 5.5, 25) minutes. ARDS severity, PRISM III score, vasoactive-ionotropic score and extrapulmonary organ failures were worse in the ARDS + CA versus ARDS group. Eight biomarkers were elevated in the ARDS + CA versus ARDS cohort: sRAGE, nucleosomes, SP-D, CCL22, IL-6, HSP70, IL-8, and MIP-1b. sRAGE, SP-D, and CCL22 remained elevated when the cohorts were matched for illness severity. When controlling for severity of ARDS and cardiac arrest characteristics, sRAGE, IL-6 and granzyme B were associated with mortality in the ARDS + CA group.

CONCLUSION

sRAGE, IL-6 and granzyme B were associated with cardiac arrest mortality when controlling for illness severity. sRAGE was consistently higher in the ARDS + CA cohort compared to ARDS and retained independent association with mortality.

Extracellular matrix-inspired inhalable aerogels for rapid clearance of pulmonary tuberculosis

Tuberculosis (TB) remains a leading cause of death from a single infectious agent, and limiting the spread of multidrug-resistant TB (MDR-TB) is now an urgent global health priority. Essential to the persistence of this disease is the ability of Mycobacterium tuberculosis (Mtb) to circumvent host defenses by infecting lung macrophages to create a cellular niche for its survival and proliferation. This has urged the development of new therapeutic strategies that act through mechanisms distinct from conventional antibiotics, and thus are effective against MDR bacteria, while being able to efficiently kill persister Mtb cells in infected host macrophages. Here, we report a new class of gel-like microparticle aerosols, or 'aerogels', designed to exploit metabolic vulnerabilities of Mtb pathogens and TB-infected macrophages to enable preferential delivery of synergistic peptide-antibiotic combinations for potent and rapid antitubercular therapy. This is achieved by formulating aerogels through the supramolecular assembly of a de novo designed anti-TB peptide and the extracellular matrix (ECM)-derived polysaccharide, hyaluronic acid (HA). Importantly, HA serves as a nutrient source for Mtb cells during tissue invasion and proliferation, and is recognized by CD44 receptors highly expressed on lung macrophages during TB infection. By exploiting this metabolic substrate for pathogen targeting, HA aerogels are shown to avidly bind and kill both drug-sensitive and drug-resistant mycobacteria, while being efficiently internalized into macrophage host cells in vitro and in vivo to clear Mtb persisters. This multifaceted bioactivity suggests aerogels may serve as a versatile inhalable platform upon which novel biomaterials-enabled therapeutics can be developed to rapidly clear pulmonary MDR-TB.

Case Report: Rapid Recognition and Immune Modulation of Secondary HLH Due to Disseminated HSV Infection

We describe the case of a newborn who presented with multiple organ dysfunction syndrome (MODS) and hyperferritinemia, who eventually met criteria for hemophagocytic lymphohistiocytosis (HLH) due to disseminated herpes simplex virus 1 (HSV-1). While the cytokine storm abated after administration of multiple immune modulatory therapies including dexamethasone, etoposide, intravenous immune globulin, anakinra, as well as the interferon gamma antagonist emapalumab, multiple organ dysfunction syndrome progressed. Care was withdrawn after 5 days. Subsequent genetic testing did not reveal any mutations associated with familial HLH. This case highlights that even with appropriate antiviral treatment and immune suppression, disseminated HSV is often fatal. Further study is warranted to determine whether early immune modulatory therapy including interferon gamma blockade can interrupt the HLH inflammatory cascade and prevent progression of MODS.

Higher serum PD-L1 level predicts increased overall survival with lapatinib versus trastuzumab in the CCTG MA.31 phase 3 trial

BACKGROUND

The purpose of this retrospective biomarker study of the Canadian Cancer Trials Group (CCTG) MA.31 randomized phase 3 trial (lapatinib vs trastuzumab) of HER2-positive metastatic breast cancer (MBC) was to evaluate the prognostic and predictive biomarker utility of pretreatment serum programmed death ligand 1 (PD-L1) levels.

METHODS

CCTG MA.31 accrued 652 HER2-positive patients; 387 had serum available (185 in the trastuzumab arm and 202 in the lapatinib arm). The Ella immunoassay platform (ProteinSimple, San Jose, California) was used to quantitate serum PD-L1 levels. Stepwise forward Cox multivariable analyses were performed for progression-free survival and overall survival (OS).

RESULTS

In the whole trial population, continuous pretreatment serum PD-L1 levels were not associated with OS. However, within the trastuzumab arm, a higher continuous pretreatment serum PD-L1 level was significant for shorter OS (hazard ratio [HR], 3.85; P = .04), but within the lapatinib arm, pretreatment serum PD-L1 was not associated with OS (P = .37). In the whole trial, in a multivariable analysis for OS, serum PD-L1 (median cut point) remained a significant independent covariate (HR, 2.38; P = .001). There was a significant interaction between treatment arm and continuous serum PD-L1 (bootstrap method; P = .0025): at or above 214.2 pg/mL (the 89th percentile), serum PD-L1 was associated with significantly shorter OS with trastuzumab treatment versus lapatinib treatment.

CONCLUSIONS

In the CCTG MA.31 trial, serum PD-L1 was a significant predictive factor: a higher pretreatment serum PD-L1 level was associated with shorter OS with trastuzumab treatment but with longer OS with lapatinib treatment. Immune evasion may decrease the effectiveness of trastuzumab therapy. Further evaluation of elevated serum PD-L1 in advanced breast cancer is warranted to identify patients with HER2-positive MBC who may benefit from novel immune-targeted therapies in addition to trastuzumab.

Plasma IL-8 and PD-L1 and overall survival in metastatic castration-resistant prostate cancer patients (mCRPC)

e17565

Background: We previously reported the significant prognostic and predictive utility of pretreatment serum PD-L1 in the CCTG MA.31 breast cancer serum bank (SABCS 2018, abstr PD3-10). IL-8 (CXCL8) is a pro-inflammatory cytokine that binds to CXCR1 and CXCR2 and promotes tumor immune escape and progression. High serum IL-8 levels are associated with poor prognosis in many cancers, and have recently been reported to predict for reduced overall survival (OS) to nivolumab in lung cancer and melanoma (ASCO 2018, abstr #3025). Here we correlated plasma IL-8 and PD-L1 levels with OS in mCRPC patients. Methods: 201 metastatic CRPC patients had EDTA plasma available for this retrospective analysis. Patient eligibility included chemotherapy-naive mCRPC patients. The ELLA immunoassay platform (ProteinSimple, San Jose, CA) was utilized to quantitate plasma IL-8 and PD-L1. Cox regression assessed hazard ratio (HR) for OS using both categorical (median) and continuous (log-transformed) biomarkers. Results: In univariate analysis, higher plasma IL-8 levels were significantly associated with reduced OS when analyzed as a continuous variable (HR = 1.53; p = 0.003) and were of borderline significance at the median cutpoint (HR = 1.32; p = 0.069; 20.9 vs 31.5 mos median OS). Plasma PD-L1 levels were not significantly associated with OS when analyzed as a continuous variable (p = 0.17), but increased levels were significant when analyzed at the median cutpoint (HR = 1.36; p = 0.044; 21.9 vs 29.0 mos median OS). When plasma IL-8 and PD-L1 levels were combined (median cutpoints), plasma IL-8 high / PD-L1 high patients (n = 58) had a significantly shorter OS vs the plasma IL-8 low / PD-L1 low patients (n = 58) (HR = 1.69; p = 0.009; 19.3 vs 32.9 mos median OS, respectively). In multivariate analysis, when adjusted for biopsy Gleason score, age, PSA, and ECOG PS (all at time of blood draw), only high plasma IL-8 (on a continuous basis) was significantly associated with reduced OS (HR = 1.43; p = 0.019). Conclusions: In mCRPC patients, high plasma IL-8 and PD-L1 levels were associated with reduced OS (separately and combined). Circulating IL-8 and PD-L1 evaluation may inform prognosis in mCRPC and could be considered as biomarkers in future studies determining response to immune checkpoint inhibitor and anti-IL8 therapy.

Lower respiratory tract delivery, airway clearance, and preclinical efficacy of inhaled GM-CSF in a postinfluenza pneumococcal pneumonia model

Inhaled granulocyte/macrophage colony-stimulating factor (GM-CSF) shows promise as a therapeutic to treat viral and bacterial pneumonia, but no mouse model of inhaled GM-CSF has been described. We sought to 1) develop a mouse model of aerosolized recombinant mouse GM-CSF administration and 2) investigate the protection conferred by inhaled GM-CSF during influenza A virus (IAV) infection against secondary bacterial infection with pneumococcus. To assess lower respiratory tract delivery of aerosolized therapeutics, mice were exposed to aerosolized fluorescein (FITC)-labeled dextran noninvasively via an aerosolization tower or invasively using a rodent ventilator. The efficiency of delivery to the lower respiratory tracts of mice was 0.01% noninvasively compared with 0.3% invasively. The airway pharmacokinetics of inhaled GM-CSF fit a two-compartment model with a terminal phase half-life of 1.3 h. To test if lower respiratory tract levels were sufficient for biological effect, mice were infected intranasally with IAV, treated with aerosolized recombinant mouse GM-CSF, and then secondarily infected with Streptococcus pneumoniae. Inhaled GM-CSF conferred a significant survival benefit to mice against secondary challenge with S. pneumoniae (P < 0.05). Inhaled GM-CSF did not reduce airway or lung parenchymal bacterial growth but significantly reduced the incidence of S. pneumoniae bacteremia (P < 0.01). However, GM-CSF overexpression during influenza virus infection did not affect lung epithelial permeability to FITC-dextran ingress into the bloodstream. Therefore, the mechanism of protection conferred by inhaled GM-CSF appears to be locally mediated improved lung antibacterial resistance to systemic bacteremia during IAV infection.

DNA Viremia Is Associated with Hyperferritinemia in Pediatric Sepsis

OBJECTIVE

To evaluate the relationship between detection of DNA viruses, ferritin, and outcomes in children with severe sepsis.

STUDY DESIGN

We enrolled 75 pediatric patients with severe sepsis admitted to a tertiary care children's hospital. Plasma ferritin was measured within 48 hours of diagnosis and subsequently twice weekly. Herpes simplex type 1, human herpesvirus 6, Epstein-Barr virus, cytomegalovirus, and adenovirus DNAemia were assessed by polymerase chain reaction.

RESULTS

The incidence of DNAemia was increased significantly in patients with ferritin ≥1000 ng/mL (78% vs 28%; P < .05). Patients with ferritin ≥1000 ng/mL were more likely to have multiple DNA viruses detected in plasma (39% vs 4%; P < .001). The number of viruses detected in plasma directly correlated with the degree of hyperferritinemia and development of combined hepatobiliary and hematologic dysfunction after we controlled for bacterial and fungal coinfections (P < .05) as well as increased mortality after we controlled for severity of illness and cancer diagnosis (OR 2.6, 95% CI 1.1-6.3, P < .05).

CONCLUSIONS

Viral DNAemia was associated with hyperferritinemia and adverse outcome in pediatric severe sepsis. Prospective studies are needed to determine whether hyperferritinemia may be used to identify patients at risk of occult DNAemia.

GM-CSF overexpression after influenza a virus infection prevents mortality and moderates M1-like airway monocyte/macrophage polarization

BACKGROUND

Influenza A viruses cause life-threatening pneumonia and lung injury in the lower respiratory tract. Application of high GM-CSF levels prior to infection has been shown to reduce morbidity and mortality from pathogenic influenza infection in mice, but the mechanisms of protection and treatment efficacy have not been established.

METHODS

Mice were infected intranasally with influenza A virus (PR8 strain). Supra-physiologic levels of GM-CSF were induced in the airways using the double transgenic GM-CSF (DTGM) or littermate control mice starting on 3 days post-infection (dpi). Assessment of respiratory mechanical parameters was performed using the flexiVent rodent ventilator. RNA sequence analysis was performed on FACS-sorted airway macrophage subsets at 8 dpi.

RESULTS

Supra-physiologic levels of GM-CSF conferred a survival benefit, arrested the deterioration of lung mechanics, and reduced the abundance of protein exudates in bronchoalveolar (BAL) fluid to near baseline levels. Transcriptome analysis, and subsequent validation ELISA assays, revealed that excess GM-CSF re-directs macrophages from an "M1-like" to a more "M2-like" activation state as revealed by alterations in the ratios of CXCL9 and CCL17 in BAL fluid, respectively. Ingenuity pathway analysis predicted that GM-CSF surplus during IAV infection elicits expression of anti-inflammatory mediators and moderates M1 macrophage pro-inflammatory signaling by Type II interferon (IFN-γ).

CONCLUSIONS

Our data indicate that application of high levels of GM-CSF in the lung after influenza A virus infection alters pathogenic "M1-like" macrophage inflammation. These results indicate a possible therapeutic strategy for respiratory virus-associated pneumonia and acute lung injury.

Viral DNAemia and Immune Suppression in Pediatric Sepsis

OBJECTIVES

Demonstrate that DNA viremia is common in pediatric sepsis and quantitate its associations with host immune function and secondary infection risk.

DESIGN

Retrospective analysis of a prospective cohort study.

PATIENTS

Seventy-three children admitted with sepsis-induced organ failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

This study was performed as an ancillary investigation to a single-center prospective study of children with severe sepsis. Longitudinally collected, batched, frozen plasma was examined using real time-polymerase chain reaction for the presence of cytomegalovirus, Epstein-Barr virus, herpes simplex virus, human herpes virus-6, torque teno virus, and adenovirus DNA. Innate immune function was also measured longitudinally via quantification of ex vivo lipopolysaccharide -induced tumor necrosis factor-α production capacity. Viral DNAemia with a virus other than torque teno virus was detected in 28 of 73 subjects (38%) and included cytomegalovirus 5%, Epstein-Barr virus 11%, herpes simplex virus 4%, human herpes virus-6 8%, and adenovirus 26%. In addition, torque teno virus was detected in 89%. Epstein-Barr virus DNAemia was associated with preexisting immune suppression (p = 0.007) Viral DNAemia was associated with preexisting immune suppression and high risk for the subsequent development of secondary infection (p < 0.05 for both). Subjects with viral DNAemia had lower innate immune function over time compared with those who were virus negative (p < 0.05).

CONCLUSIONS

DNAemia from multiple viruses can be detected in septic children and is strongly associated with preexisting immune suppression and secondary infection risk. The role of DNA viruses in the perpetuation of impaired host defense in this setting should be the subject of prospective study.

An Electrochemical Biosensor for Rapid Detection of Pediatric Bloodstream Infections

Bloodstream infections are major contributing factors of morbidity and mortality among children. Precise and timely identification of causative agents can improve the clinical management and outcome of the infection, potentially saving lives. Electrochemical biosensors previously described by Gao et al. (2017) have the potential to deliver greater speed and discrimination. However, to date there are no data that determine whether the age of the host would cause bacteria to demonstrate different growth characteristics, or whether pediatric samples would behave differently using this electrochemical biosensor. The importance of this knowledge gap is clear: the preclinical testing phase of this line of research is limited by the relative lack of pediatric healthy blood volunteers to complete this work. Therefore, in this study we have applied this novel technology to diagnose bacteria spiked into pediatric blood and compared directly with adult blood samples. Only 180 µL of blood was utilized from both adult and pediatric volunteers and inoculated with Escherichia coli 67, and the signals generated at different time points were compared. We were able to demonstrate that the signals generated by adult and pediatric blood were not significantly different with this detection technology.

SH3GLB2/endophilin B2 regulates lung homeostasis and recovery from severe influenza A virus infection

New influenza A viruses that emerge frequently elicit composite inflammatory responses to both infection and structural damage of alveolar-capillary barrier cells that hinders regeneration of respiratory function. The host factors that relinquish restoration of lung health to enduring lung injury are insufficiently understood. Here, we investigated the role of endophilin B2 (B2) in susceptibility to severe influenza infection. WT and B2-deficient mice were infected with H1N1 PR8 by intranasal administration and course of influenza pneumonia, inflammatory, and tissue responses were monitored over time. Disruption of B2 enhanced recovery from severe influenza infection as indicated by swift body weight recovery and significantly better survival of endophilin B2-deficient mice compared to WT mice. Compared to WT mice, the B2-deficient lungs exhibited induction of genes that express surfactant proteins, ABCA3, GM-CSF, podoplanin, and caveolin mRNA after 7 days, temporal induction of CCAAT/enhancer binding protein CEBPα, β, and δ mRNAs 3-14 days after infection, and differences in alveolar extracellular matrix integrity and respiratory mechanics. Flow cytometry and gene expression studies demonstrated robust recovery of alveolar macrophages and recruitment of CD4+ lymphocytes in B2-deficient lungs. Targeting of endophilin B2 alleviates adverse effects of IAV infection on respiratory and immune cells enabling restoration of alveolar homeostasis.

Circulating PD-L1 (programmed death-ligand 1) and outcomes in a HER2-positive metastatic breast cancer cohort treated with first-line trastuzumab

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Background: Recently the immune checkpoint inhibitors (ICIs) have demonstrated efficacy across a wide variety of cancers, but have been less effective in breast cancer. PD-L1 (B7-H1, CD274) is a ligand produced by many tumor cells and some immune cells, and suppresses the T cell immune response. This allows tumor cells to escape immune detection. PD-L1 is used as a companion tumor tissue IHC biomarker for patient selection for some of the FDA-approved ICIs (pembrolizumab), but not for others (nivolumab, atezolizumab). Circulating PD-L1 has been detected in multiple myeloma, renal, lung, and gastric cancer, but not in breast cancer. Here we correlated serum PD-L1 levels with outcome in a HER2-positive metastatic breast cancer cohort treated with trastuzumab. Methods: Pretreatment serum was obtained from 63 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. A novel ELLA microfluidic channel immunoassay platform (ProteinSimple, San Jose, CA) was employed to quantitate serum PD-L1. Serum PD-L1 levels were analyzed using continuous, quartile, and dichotomous (25%, median, and 75%) cutpoints. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Results: On a continuous basis, patients with higher serum PD-L1 had a significantly reduced PFS (p = 0.045) and overall survival OS (p = 0.004) compared to patients with lower serum PD-L1 levels. Patients with the higher quartiles of serum PD-L1 also trended to have reduced PFS (0.11) and significantly reduced OS (p = 0.015) compared to the lower quartiles of serum PD-L1. Finally, using either the 25th or 75th percentile of serum PD-L1 as dichotomous cutpoint, patients with higher serum PD-L1 had significantly reduced OS (p = 0.04). Conclusions: Higher circulating PD-L1 levels were prognostic for reduced PFS and OS in HER2-positive metastatic breast cancer patients treated with first-line trastuzumab. Circulating PD-L1 deserves further study for prognostic and predictive biomarker utility in larger trials of immune checkpoint inhibitors and other immunotherapies in breast and other cancers. AA, LK contributed equally.

A Systemic Inflammation Mortality Risk Assessment Contingency Table for Severe Sepsis

OBJECTIVES

We tested the hypothesis that a C-reactive protein and ferritin-based systemic inflammation contingency table can track mortality risk in pediatric severe sepsis.

DESIGN

Prospective cohort study.

SETTING

Tertiary PICU.

PATIENTS

Children with 100 separate admission episodes of severe sepsis were enrolled.

INTERVENTIONS

Blood samples were attained on day 2 of sepsis and bi-weekly for biomarker batch analysis. A 2 × 2 contingency table using C-reactive protein and ferritin thresholds was developed.

MEASUREMENTS AND MAIN RESULTS

A C-reactive protein of 4.08 mg/dL and a ferritin of 1,980 ng/mL were found to be optimal cutoffs for outcome prediction at first sampling (n = 100) using the Youden index. PICU mortality was increased in the "high-risk" C-reactive protein greater than or equal to 4.08 mg/dL and ferritin greater than or equal to 1,980 ng/mL category (6/13 [46.15%]) compared with the "intermediate-risk" C-reactive protein greater than or equal to 4.08 mg/dL and ferritin less than 1,980 ng/mL or C-reactive protein less than 4.08 mg/dL and ferritin greater than or equal to 1,980 ng/mL categories (2/43 [4.65%]), and the "low-risk" C-reactive protein less than 4.08 mg/dL and ferritin less than 1,980 ng/mL category (0/44 [0%]) (odds ratio, 36.43 [95% CI, 6.16-215.21]). The high-risk category was also associated with the development of immunoparalysis (odds ratio, 4.47 [95% CI, 1.34-14.96]) and macrophage activation syndrome (odds ratio, 24.20 [95% CI, 5.50-106.54]). Sixty-three children underwent sequential blood sampling; those who were initially in the low-risk category (n = 24) and those who subsequently migrated (n = 19) to the low-risk category all survived, whereas those who remained in the "at-risk" categories had increased mortality (7/20 [35%]; p < 0.05).

CONCLUSIONS

A C-reactive protein- and ferritin-based contingency table effectively assessed mortality risk. Reduction in systemic inflammation below a combined threshold C-reactive protein of 4.08 mg/dL and ferritin of 1,980 ng/mL appeared to be a desired response in children with severe sepsis.

Intrapulmonary Percussive Ventilation as an Airway Clearance Technique during Venoarterial Extracorporeal Life Support in an Infant with Pertussis

Initiation of extracorporeal life support (ECLS) is often followed by complete opacification of pulmonary parenchyma and volume loss. The optimal mechanical ventilator management and lung recruitment strategy of a pediatric patient requiring extracorporeal membrane oxygenation is not known. We present a case of a 4-week old infant who developed a severe pertussis infection requiring ECLS. The severity of his illness and pertussis infection-associated intraluminal bronchiole obstruction made medical management challenging. In addition to lung protection ventilator strategies and bronchoscopy, intrapulmonary percussive ventilation was initiated to facilitate lung recruitment. This was associated with precipitous incremental improvement in lung compliance and eventual liberation from venoarterial ECLS.

Hyperferritinemic Sepsis: An Opportunity for Earlier Diagnosis and Intervention?

We describe a case of an infant with HSV meningitis and septic shock who demonstrated a remarkably high serum ferritin level. Aggressive pediatric intensive care and the administration of high-dose glucocorticoids were not able to reverse the multiple organ dysfunctions. Subsequent autopsy identified the presence of hemophagocytosis, thus the patient fulfilled hemophagocytic lymphohistiocytosis (HLH) criteria post-mortem. This case highlights that serum ferritin may be an important early indicator of mortality in sepsis due to a cytokine storm similar to macrophage activation syndrome and HLH.

Lethal influenza infection: Is a macrophage to blame?

Alveolar macrophages (AMs) are critical for immunity against influenza A virus (IAV) infection. Depletion, hyporeactivity, and disruption of AM development and differentiation are all associated with lethal IAV infection. AMs drive the innate immune response that limits IAV infection. AMs are crucial for steady-state homeostasis of pulmonary surfactant, and in turn surfactant proteins regulate AMs and participate in host defense against IAV. Known factors that are necessary for AM function and differentiation in vivo include surfactant proteins, the growth factor GM-CSF, the hormone receptor PPARγ, and the transcription factors PU.1 and Bach2. Although PU.1 and PPARγ are downstream effectors of GM-CSF, Bach2 works independently. GM-CSF and Bach2-deficient AMs have phenotypes with immature or alternatively activated states of differentiation, respectively, and both extremes are unsuitable for surfactant homeostasis. The activation state of AMs and the local microenvironment may determine the development of symptomatic versus asymptomatic IAV infection in different individuals.

Rapid onset of hippocampal atrophy in febrile-infection related epilepsy syndrome (FIRES)

Febrile infection-related epilepsy syndrome (FIRES) is a catastrophic and usually refractory epilepsy syndrome that occurs after a febrile illness in previously normal children. The pathogenesis of the syndrome is unknown, and the diagnosis is typically made by exclusion after an exhaustive negative workup for central nervous system infections and autoimmune or metabolic disorders. Magnetic resonance imaging of patients with this condition has previously shown hippocampal abnormalities, typically found several months or longer after initial seizures. We report a previously healthy 5-year-old child who developed hippocampal atrophy by day 37 of his illness. The development of early hippocampal atrophy in this epileptic encephalopathy may provide insight into pathogenesis and highlights the need for aggressive and effective interventions early in the disease process.

IL-15 enhances survival and function of HIV-specific CD8+ T cells

HIV-specific CD8(+) T cells are prone to undergo apoptosis, and this may affect their ability to control HIV infection. Because CD8-mediated immune responses play a key role in controlling HIV infection, enhancing the survival and effector function of HIV-specific CD8(+) T cells may augment their ability to control HIV virus. We show here that interleukin 15 (IL-15) potently inhibits spontaneous and CD95/Fas-induced apoptosis of HIV-specific CD8(+) T cells. IL-15 inhibits apoptosis in both CD45RA(-)CD62L(-) and CD45RA(+)CD62L(-) effector memory subpopulations of these cells. Furthermore, IL-15 greatly enhances the survival of HIV-specific CD8(+) T cells in long-term cultures. Finally, IL-15 directly enhances activation, interferon gamma (IFNgamma) production, and direct ex vivo cytotoxicity of HIV-specific CD8(+) T cells. Thus, IL-15 potently enhances the survival and effector function of HIV-specific CD8(+) T cells and, therefore, may prove useful in augmenting the antiviral function of these cells.

In vivo stimulation of CD137 broadens primary antiviral CD8+ T cell responses

Given the key role CD8+ T cells play in controlling viral infection, strategies to enhance these responses may have important clinical applications. We found that in vivo CD137 stimulation with an agonistic monoclonal antibody enhanced the primary CD8+ T cell response to influenza type A viral infection in mice. Stimulation of CD137 increased the absolute number of CD8+ T cells to influenza epitopes in the lungs of infected animals, preferentially expanded CD8+ T cells that recognized nondominant epitopes and greatly enhanced direct ex vivo cytotoxicity. CD137 stimulation also restored the CD8+ T cell response to the immunodominant influenza epitope in CD28-/- mice. Thus, in vivo CD137 stimulation enhances and broadens the CD8+ T cell response to influenza virus and can restore the CD8+ T cell response when CD28 costimulation is absent. This suggests that CD137 stimulation may be useful as a strategy to enhance the CD8+ T cell response to viruses.