Real-Time Acute Kidney Injury Risk Stratification-Biomarker Directed Fluid Management Improves Outcomes in Critically Ill Children and Young Adults.

Introduction: Critically ill admitted patients are at high risk of acute kidney injury (AKI). The renal angina index (RAI) and urinary biomarker neutrophil gelatinase-associated lipocalin (uNGAL) can aid in AKI risk assessment. We implemented the Trial in AKI using NGAL and Fluid Overload to optimize CRRT Use (TAKING FOCUS 2; TF2) to personalize fluid management and continuous renal replacement therapy (CRRT) initiation based on AKI risk and patient fluid accumulation. We compared outcomes pre-TF2 and post-TF2 initiation. Methods: Patients admitted from July 2017 were followed-up prospectively with the following: (i) an automated RAI result at 12 hours of admission, (ii) a conditional uNGAL order for RAI ≥8, and (iii) a CRRT initiation goal at 10% to 15% weight-based fluid accumulation. Results: A total of 286 patients comprised 304 intensive care unit (ICU) RAI+ admissions; 178 patients received CRRT over the observation period (2014-2021). Median time from ICU admission to CRRT initiation was 2 days shorter (P < 0.002), and ≥15% pre-CRRT fluid accumulation rate was lower in the TF2 era (P < 0.02). TF2 ICU length of stay (LOS) after CRRT discontinuation and total ICU LOS were 6 and 11 days shorter for CRRT survivors (both P < 0.02). Survival rates to ICU discharge after CRRT discontinuation were higher in the TF2 era (P = 0.001). These associations persisted in each TF2 year; we estimate a conservative $12,500 health care cost savings per CRRT patient treated after TF2 implementation. Conclusion: We suggest that automated clinical decision support (CDS) combining risk stratification and AKI biomarker assessment can produce durable reductions in pediatric CRRT patient morbidity.

Exogenous nitric oxide delivery protects against cardiopulmonary bypass-associated acute kidney injury: Histologic and serologic evidence from an ovine model.

OBJECTIVE: Several human studies have associated nitric oxide administration via the cardiopulmonary bypass circuit with decreased incidence of cardiopulmonary bypass-associated acute kidney injury, but histopathologic and serologic evidence of nitric oxide efficacy for acute kidney injury attenuation are lacking. METHODS: By using a survival ovine model (72 hours), acute kidney injury was induced by implementing low-flow cardiopulmonary bypass for 2 hours, followed by full-flow cardiopulmonary bypass for 2 hours. The nitric oxide cohort (n = 6) received exogenous nitric oxide through the cardiopulmonary bypass circuit via the oxygenator, and the control group (n = 5) received no nitric oxide. Serial serologic biomarkers and renal histopathology were obtained. RESULTS: Baseline characteristics (age, weight) and intraoperative parameters (cardiopulmonary bypass time, urine output, heart rate, arterial pH, and lactate) were equivalent (P > .10) between groups. Postoperatively, urine output, heart rate, respiratory rate, and peripheral arterial saturation were equivalent (P > .10) between groups. Post-cardiopulmonary bypass creatinine elevations from baseline were significantly greater in the control group versus the nitric oxide group at 16, 24, and 48 hours (all P < .05). Histopathologic evidence of moderate/severe acute kidney injury (epithelial necrosis, tubular slough, cast formation, glomerular edema) occurred in 60% (3/5) of the control group versus 0% (0/6) of the nitric oxide group. Cortical tubular epithelial cilia lengthening (a sensitive sign of cellular injury) was significantly greater in the control group than in the nitric oxide group (P = .012). CONCLUSIONS: In a survival ovine cardiopulmonary bypass model, nitric oxide administered with cardiopulmonary bypass demonstrated serologic and histologic evidence of renal protection from acute kidney injury. These results provide insight into 1 potential mechanism for cardiopulmonary bypass-associated acute kidney injury and supports continued study of nitric oxide via cardiopulmonary bypass circuit for prevention of acute kidney injury.

Use of extracorporeal immunomodulation in a toddler with hemophagocytic lymphohistiocytosis and multisystem organ failure.

INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a dysregulated immune disorder in children, associated with Epstein-Barr virus (EBV) infection or malignancies. In severe forms, HLH presents with signs and symptoms of hyperinflammation that progress to life-threatening multiorgan failure. Intervention with an extracorporeal immunomodulatory treatment utilizing a selective cytopheretic device (SCD) could be beneficial. The SCD with regional citrate anticoagulation selectively binds the most highly activated circulating neutrophils and monocytes and deactivates them before release to the systemic circulation. Multiple clinical studies, including a multicenter study in children, demonstrate SCD therapy attenuates hyperinflammation, resolves ongoing tissue injury and allows progression to functional organ recovery. We report the first case of SCD therapy in a patient with HLH and multi-organ failure. CASE DIAGNOSIS/TREATMENT: A previously healthy 22-month-old toddler presented with fever, abdominal distension, organomegaly, pancytopenia, and signs of hyperinflammation. EBV PCR returned at > 25 million copies. The clinical and laboratory pictures were consistent with systemic EBV-positive T-cell lymphoma with symptoms secondary to HLH. The patient met inclusion criteria for an ongoing study of integration of the SCD with a continuous kidney replacement therapy (CKRT) as part of standard of care. The patient received CKRT-SCD for 4 days with normalization of serum markers of sepsis and inflammation. The patient underwent hematopoietic stem cell transplantation 52 days after presentation and has engrafted with normal kidney function 8 months later. CONCLUSIONS: SCD treatment resulted in improvement of poor tissue perfusion reflected by rapid decline in serum lactate levels, lessened systemic capillary leak with discontinuation of vasoactive agents, and repair and recovery of lung and kidney function with extubation and removal of hemodialysis support.

Integration of the Renal Angina Index and Urine Neutrophil Gelatinase-Associated Lipocalin Improves Severe Acute Kidney Injury Prediction in Critically Ill Children and Young Adults.

Introduction: Acute kidney injury (AKI) occurs in one-fourth of children and young adults admitted to pediatric intensive care unit (PICU). Severe AKI (sAKI; Kidney Disease: Improving Global Outcomes stage 2 or 3) is associated with morbidity and mortality. An AKI risk stratification system, the Renal Angina Index (RAI) calculated at 12 hours of admission, exhibits excellent performance to rule out sAKI at 72 hours of admission. We found that integration of urine neutrophil gelatinase-associated lipocalin (NGAL) with RAI improves prediction of sAKI. We now report the first-year results after implementation of our prospective automated RAI-NGAL clinical decision support (CDS) program. Methods: Patients 3 months to 25 years of age were eligible. Admission order sets have a conditional order for urine NGAL released when a 12-hour RAI ≥8. The primary outcome was sAKI any time at days 2 to 4 of admission. We assessed performance of the RAI and RAI+/NGAL to predict the primary outcome. Results: A total of 1427 unique patients accounted for 1575 admissions. In 147 admissions, RAI was ≥8. RAI <8 had negative predictive value (NPV) of 0.98 (95% CI 0.97-0.99); RAI ≥ 8 had positive predictive value (PPV) of 0.37 (95% CI 0.30-0.46) to predict days 2 to 4 sAKI (area under the receiver operating characteristic curve [AUC-ROC] 0.88 [95% CI 0.84-0.92]). Of 147 RAI+ patients, 89 had NGAL available. RAI/NGAL combination improved PPV (0.64, 95% CI 0.50-0.79) without decrement in NPV (0.98, 95% CI 0.97-0.98). Conclusion: AKI biomarker assessment directed by risk stratification improves prediction of sAKI in critically ill children and young adults. This CDS process has potential to enrich the population for interventional study, although improvement to adherence to CDS is needed.

T cell receptor activation leads to two distinct phases of Pyk2 activation and actin cytoskeletal rearrangement in human T cells.

The tyrosine kinase Pyk2 integrates receptor-mediated signals controlling actin cytoskeletal rearrangement, events needed for the activation and function of T cells. Induction of the T cell receptor (TCR) leads to the phosphorylation of Pyk2, but the timing of these events is controversial and not fully understood. In this study, the TCR-induced phosphorylation kinetics of Pyk2 tyrosines 402 and 580 were characterized in human T cells. Interestingly, the early TCR-mediated phosphorylation of Pyk2 was more rapid and transient than ZAP-70, whose phosphorylation kinetics were similar to other T cell signaling proteins. Unexpectedly, Pyk2 had a second burst of phosphorylation 30-60 min after TCR stimulation. Pyk2 was enzymatically active during the two separate bursts of phosphorylation, since both paxillin phosphorylation, a known substrate of Pyk2, and TCR-induced actin polymerization showed similar kinetics. The second burst of Pyk2 phosphorylation did not require actin cytoskeleton rearrangement or PI3K function, but was dependent on the enzymatic activity of Fyn and/or Lck. Collectively, these observations suggest that signaling pathways downstream of TCR activation are hard-wired to induce two separate periods of Pyk2 activation and actin cytoskeletal rearrangement.

The T cell receptor-mediated phosphorylation of Pyk2 tyrosines 402 and 580 occurs via a distinct mechanism than other receptor systems.

The tyrosine kinase Pyk2 is vital for integrating receptor-mediated signals controlling adhesion and motility in neuronal, epithelial, and hematopoietic cell types. In T cells, the stimulation of the TCR and costimulatory, chemokine, cytokine, and integrin receptors leads to the phosphorylation of Pyk2 and the induction of its catalytic activity. However, our understanding of the mechanism of the TCR-induced, site-specific phosphorylation of this kinase is incomplete and contradictory. To address this issue, the role of individual signaling pathways in the phosphorylation of Pyk2 tyrosines 402 and 580 upon TCR activation was assessed in human T cells. In contrast to other receptor systems, the TCR-induced phosphorylation of Pyk2 tyrosines 402 and 580 was dependent on the Src family kinases, Fyn or Lck. Interestingly, the TCR-mediated phosphorylation of Pyk2 tyrosines 402 and 580 did not require Ca(2+) influx, ZAP-70 activation, actin cytoskeleton rearrangement, or PI3K function. These observations are different than other receptor systems, which require the induction of one or more of these pathways. Together, these data have defined more fully the mechanism for the TCR-induced phosphorylation of specific sites on Pyk2, suggesting that the TCR has a distinct pathway for the activation of Pyk2 compared with other receptor systems.

Comparison of T cell receptor-induced proximal signaling and downstream functions in immortalized and primary T cells.

BACKGROUND: Human T cells play an important role in pathogen clearance, but their aberrant activation is also linked to numerous diseases. T cells are activated by the concurrent induction of the T cell receptor (TCR) and one or more costimulatory receptors. The characterization of signaling pathways induced by TCR and/or costimulatory receptor activation is critical, since these pathways are excellent targets for novel therapies for human disease. Although studies using human T cell lines have provided substantial insight into these signaling pathways, no comprehensive, direct comparison of these cell lines to activated peripheral blood T cells (APBTs) has been performed to validate their usefulness as a model of primary T cells. METHODOLOGY/PRINCIPAL FINDINGS: We used quantitative biochemical techniques to compare the activation of two widely used human T cell lines, Jurkat E6.1 and HuT78 T cells, to APBTs. We found that HuT78 cells were similar to APBTs in proximal TCR-mediated signaling events. In contrast, Jurkat E6.1 cells had significantly increased site-specific phosphorylation of Pyk2, PLCgamma1, Vav1, and Erk1/Erk2 and substantially more Ca2+ flux compared to HuT78 cells and APBTs. In part, these effects appear to be due to an overexpression of Itk in Jurkat E6.1 cells compared to HuT78 cells and APBTs. Both cell lines differ from APBTs in the expression and function of costimulatory receptors and in the range of cytokines and chemokines released upon TCR and costimulatory receptor activation. CONCLUSIONS/SIGNIFICANCE: Both Jurkat E6.1 and HuT78 T cells had distinct similarities and differences compared to APBTs. Both cell lines have advantages and disadvantages, which must be taken into account when choosing them as a model T cell line.