Proteomic Analysis of Pediatric Hemophagocytic Lymphohistiocytosis: a Comparative Study with Healthy Controls, Sepsis, Critical Ill, and Active Epstein-Barr virus Infection to Identify Altered Pathways and Candidate Biomarkers.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome characterized by excessive activation of the immune system, along with uncontrolled proliferation of activated macrophages and lymphocytes. The clinical features of HLH often overlap with the clinical features of other severe inflammatory conditions such as sepsis, hindering accurate and timely diagnosis. In this study, we performed a data-independent acquisition mass spectrometry-based plasma proteomic analysis of 33 pediatric patients with HLH compared with four control groups: 39 healthy children, 43 children with sepsis, 39 children hospitalized in the pediatric intensive care unit without confirmed infections, and 21 children with acute Epstein-Barr virus infection. Proteomic comparisons between the HLH group and each of the control groups showed that HLH was characterized by alterations in complement and coagulation cascades, neutrophil extracellular trap formation, and platelet activation pathways. We identified eight differentially expressed proteins in patients with HLH, including plastin-2 (LCP1), vascular cell adhesion protein 1, fibrinogen beta chain, fibrinogen gamma chain, serum amyloid A-4 protein, extracellular matrix protein 1, apolipoprotein A-I, and albumin. LCP1 emerged as a candidate diagnostic marker for HLH with an area under the curve (AUC) of 0.97 in the original cohort and an AUC of 0.90 (sensitivity = 0.83 and specificity = 1.0) in the validation cohort. Complement C1q subcomponent subunit B was associated with disease severity in patients with HLH. Based on comparisons with multiple control groups, this study provides a proteomic profile and candidate biomarkers of HLH, offering researchers novel information to improve the understanding of this condition.

Relationship between serum phosphate and mortality in critically ill children receiving continuous renal replacement therapy.

Purpose: We aimed to explore the relationship between serum phosphate concentration and 90-day mortality in critically ill children receiving continuous renal replacement therapy (CRRT). Methods: Data from the medical records of children aged <13 years who received CRRT at the Pediatric Intensive Care Unit of Hunan Children's Hospital, China from January 2015 to June 2020 were retrospectively collected. Children were grouped into four categories according to the baseline phosphate concentration before CRRT and mean serum phosphate concentration during CRRT: <0.81 mmol/L (hypophosphatemia), 0.81-1.19 mmol/L, 1.2-2.4 mmol/L (normal phosphate concentration), and >2.4 mmol/L (hyperphosphatemia), with the normal phosphate group serving as the comparator group. The correlation of the serum phosphate concentration before and during CRRT with the 90-day mortality after CRRT initiation was analyzed using logistic regression. Results: A total of 177 children were included in our study. The mean serum phosphate concentration before CRRT was 1.46 mmol/L (quartiles: 1.04, 2.20). The 90-day mortality rate was increased in children with a serum phosphate concentration >2.4 mmol/L before CRRT (adjusted odds ratio [aOR] 3.74, 95% confidence interval [CI] 1.42-9.86, P = 0.008). The mean serum phosphate concentration during CRRT was 1.2 mmol/L (quartiles: 0.91, 1.49). The 90-day mortality rate was increased in children with a mean serum phosphate concentration >2.4 mmol/L during CRRT (aOR 7.34, 95% CI 1.59-33.88, P = 0.011). Conclusion: Hyperphosphatemia before and during CRRT predicts a higher 90-day mortality rate.

A Three-Step Screening Procedure for Early Identification of Children at High Risk of Hemophagocytic Lymphohistiocytosis.

PURPOSE: The first step in diagnosing hemophagocytic lymphohistiocytosis (HLH) is to suspect its presence and then order the appropriate diagnostic tests. The development of screening procedures for HLH could facilitate early diagnosis. In this study, we evaluated the utility of fever, splenomegaly, and cytopenias as screening criteria for identifying pediatric HLH at an early stage, built a screening model using commonly measured laboratory parameters, and developed a step-wise screening procedure for pediatric HLH. METHODS: The medical records of 83,965 pediatric inpatients, including 160 patients with HLH, were collected retrospectively. The utility of fever, splenomegaly, hemoglobin level, and platelet and neutrophil counts at hospital admission as screening criteria for HLH was evaluated. For HLH patients who might be missed by screening based on the presence of fever, splenomegaly, and cytopenias, a screening model using common laboratory parameters was developed. Following that, a three-step screening procedure was then developed. RESULTS: The criteria of cytopenias affecting two or more lineages plus fever or splenomegaly had a sensitivity of 51.9% and a specificity of 98.4% for identifying HLH in pediatric inpatients. Our screening score model comprises six parameters: splenomegaly, platelet count, neutrophil count, albumin level, total bile acid level, and lactate dehydrogenase level. The use of the validation set had a sensitivity of 87.0% and a specificity of 90.6%. A three-step screening procedure has been developed: Step 1: Is fever or splenomegaly present? (Yes: risk for HLH should be considered, go to Step 2; No: less likely HLH); Step 2: Are cytopenias affecting at least two lineages? (Yes: consider HLH; No: go to Step 3); Step 3: Calculate the screening score. Is the sum of the score greater than 37? (Yes: consider HLH; No: less likely HLH). The overall sensitivity and specificity of the three-step screening procedure were 91.9% and 94.4%, respectively. CONCLUSION: A significant proportion of pediatric HLH patients present at the hospital without having all three symptoms: fever, splenomegaly, and cytopenias. Our three-step screening procedure, utilizing commonly available clinical and laboratory parameters, can effectively identify pediatric patients who may be at high risk for HLH.

Development of a screening score for Hemophagocytic Lymphohistiocytosis among pediatric patients with acute infection of Epstein-Barr virus.

Background and aims: Deciding when to suspect hemophagocytic lymphohistiocytosis (HLH) and perform diagnostic tests in patients with acute infection of Epstein-Barr virus (EBV) is challenging, given the high prevalence of EBV infection, the life-threatening risk of EBV-HLH, the relatively low incidence of EBV-HLH, and the wide spectrum of disease presentations. The aim of this study was to develop an EBV-HLH screening model for pediatric patients diagnosed with acute infection of EBV. Methods: An inpatient cohort with 3183 pediatric patients who were diagnosed with active infection of EBV was used to construct and validate the EBV-HLH screening score model. The model parameters were selected from common laboratory parameters using the method of Akaike Information Criterion-optimal selection through cross-validation under logistic regression. Performance of the score was evaluated and compared with the performance of screening methods using the number of cytopenias lineages. Results: The EBV-HLH screening score has five parameters, including hemoglobin, platelet, neutrophil, albumin, and lactate dehydrogenase. Using a cut-of value of 29, the scoring model had a sensitivity of 89.2% and a specificity of 89.5% in the validation set. The false negative rate, false positive rate, positive predictive value, and negative predictive value in the validation set was 10.8%, 10.5%, 26.8%, and 99.5%, respectively, similar to that of the training set. Conclusions: With five common laboratory parameters, the EBV-HLH score provides a simple tool to assist the identification of EBV patients who require further evaluation of HLH. Further studies are needed to evaluate the generalizability of the score and optimize the diagnose process for EBV-HLH.

Fulfillment status of hypertriglyceridemia and hypofibrinogenemia in children with hemophagocytic lymphohistiocytosis and risks of multiple organ dysfunction syndrome and early mortality.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder. How to stratify high risk patients is one of the current challenges for the treatment of HLH. HLH patients usually fulfill multiple but not all eight diagnostic criteria. Different combinations of the fulfilled criteria may naturally cluster into previously undescribed subsets or phenotypes that may have different pathophysiology and demonstrate different risks for a poor outcome. The objectives of this study were to identify HLH subgroups according to the fulfillment of diagnostic criteria and evaluate the risk of multiple organ dysfunction syndrome (MODS) and 30-day mortality for subgroups. We retrospectively collect medical records of patients with discharge diagnosis of HLH between June 2015 and October 2018 from a tertiary children's hospital in China. Latent class analysis was used to identify class defining variables from HLH diagnostic items, and subgroups were defined according to different combinations of the class defining variables. RESULTS: Triglyceride and fibrinogen were identified as the class defining variables. When evaluated in combinations, patients with hypertriglyceridemia and normal fibrinogen levels during hospitalization had the lowest risks for MODS (27.8%, OR = 1) and 30-day mortality (18.8%, OR = 1), and patients with normal triglyceride and hypofibrinogenemia had the highest risks for MODS (86.2%, OR = 16.24, P = 0.0002) and 30-day mortality (57.1%, OR = 5.78, P = 0.0187). The fulfillment status of hypertriglyceridemia and hypofibrinogenemia within 72 h of hospital admission was also associated with the risk of adverse outcomes. CONCLUSIONS: The fulfillment status of hypertriglyceridemia and hypofibrinogenemia were associated with the risks of MODS and 30-day mortality among pediatric HLH patients. Further studies are needed to validate this association and investigate its clinical utility in the severity evaluation for HLH.

Diagnostic Time Lag of Pediatric Haemophagocytic Lymphohistiocytosis and Patient Characteristics: A Retrospective Cohort Study.

The difficulties and challenges of applying the HLH-2004 diagnostic criteria to early identification and diagnosis of haemophagocytic lymphohistiocytosis have been fully addressed in previous studies. However, the distribution of the diagnostic time lag of haemophagocytic lymphohistiocytosis and related patient characteristics remain unclear. This study investigated the time lags between symptom onset and diagnosis and between hospital admission and diagnosis among pediatric patients with haemophagocytic lymphohistiocytosis, and identified factors that associated with a shorter or longer diagnostic time lag. The cohort of patients with haemophagocytic lymphohistiocytosis was drawn from a tertiary children's hospital and consisted of 122 pediatric patients. The distributions of symptom-to-diagnosis and admission-to-diagnosis time lags were assessed. Clinical characteristics within 48 h of admission and the fulfillment of HLH-2004 diagnostic criteria were compared among admission-to-diagnosis time lag categories. Logistic regression analyses were conducted to identify factors associated with an admission-to-diagnosis time lag >3 days. The median interval from first symptom onset to HLH diagnosis was 12 days (range 4-71 days) and the median interval from hospital admission to HLH diagnosis was 2 days (range 0-23 days). The following factors were negatively associated with admission-to-diagnosis > 3 days: Epstein-Barr virus infection; admission through pediatric intensive care unit; diagnosis established without NK-cell activity and soluble CD25 tests; the performance of all readily available diagnostic tests for HLH (within 48 and 72 h); concurrent fever, splenomegaly, and cytopenias within 48 h; hemophagocytosis, hypertriglyceridemia and/or hypofibrinogenemia within 48 h; and elevated ferritin, total bilirubin, alanine aminotransferase, and prothrombin time within 48 h. Our findings suggest that performance of adequate diagnostic tests for HLH is essential for early diagnosis of HLH. Once suspected, immediate and adequate diagnostic tests for HLH should be arranged for PICU patients. Improvements in diagnostic procedures and monitoring plans are needed to promote early diagnosis of HLH.

Clinical profiles and risk factors of 7-day and 30-day mortality among 160 pediatric patients with hemophagocytic lymphohistiocytosis.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a relatively rare and life-threatening disorder. Early mortality remains significantly high among patients with HLH. Our aim was to investigate clinical features and risk factors associated with 7-day and 30-day mortality among pediatric HLH patients. We retrospectively collected medical records of patients with discharge diagnosis of HLH between August 2014 and October 2018 from a tertiary children's hospital in China. The main outcome measures were the 7-day and 30-day outcome after hospital admission. The associations between symptoms, concomitant diagnoses, laboratory test results, and the risk of 7-day and 30-day mortality were examined. RESULTS: Among 160 pediatric HLH patients, 18 (11.3%) patients were deceased within 7 days after admission, and 46 (28.8%) patients were deceased within 30 days. The identified strong risk factors (OR > 10 and p < 0.05) for 30-day mortality were myocardial damage, severe pneumonia, respiratory failure, coagulopathy, gastrointestinal disorder, and multiple organ dysfunction syndrome (MODS). Factors strongly associated with 7-day mortality were sepsis, myocardial damage, shock, and respiratory failure. All patients deceased within 7 days developed hepatic dysfunction, coagulopathy, and MODS. CONCLUSIONS: The identified risk factors could help to stratify patients with high risk of early death, and need to be considered in the development of treatment protocols. As early mortality of HLH remains high, studies are needed to investigate how to initiate adequate HLH-directed treatment strategies for patients at higher risk of early death.

Elevated serum myoglobin levels at hospital admission and the risk of early death among patients with hemophagocytic lymphohistiocytosis: evidence from 155 pediatric patients.

Patients with hemophagocytic lymphohistiocytosis (HLH) have high risk of early mortality. The purpose of this study was to test the hypothesis that the elevated level of serum myoglobin among patients with HLH is associated with disease severity and increased risk of mortality. We retrospectively investigated the serum myoglobin levels from 155 pediatric patients diagnosed with HLH in the Hunan Children's Hospital, China. The levels of myoglobin and creatine kinase at hospital admission among non-survivors and survivors were compared. The myoglobin level was dichotomized for the estimation of hazard ratio (HR) for mortality. Patients who died within 7 and 30 days of hospitalization had significantly higher myoglobin levels than did survivors (p < 0.05). The myoglobin level was negatively associated with the days of survival among non-survivors (Spearman correlation coefficient = - 0.29, p = 0.04). An elevated myoglobin level (> 90 ng/mL) was significantly associated with increased mortality (unadjusted HR = 2.66, 95%CI: 1.41, 5.00, p = 0.0024) and persisted after adjusting for age, Epstein-Barr virus infection, admission department, acute kidney injury, myocardial damage, and shock. In conclusion, an elevated serum myoglobin level was associated with increased risk of early death among pediatric patients with HLH, suggesting the potential of myoglobin to be used as a reference indicator for monitoring and managing of HLH.

A Novel Mechanism of Sildenafil Improving the Excessive Proliferation and H2S Production in Pulmonary Arterial Smooth Muscle Cells.

The dysregulation of pulmonary arterial vasoactive mediators or excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) might result in contraction or remodeling of pulmonary blood vessels, leading to related lung diseases. Recent studies suggest that hydrogen sulfide (H2S), a gaseous vasodilator generated in the blood vessels by the enzymes cystathionine γ-lyase (CSE) and cystathionine-ß-synthase (CBS), could induce the vasodilation, thus improving contraction or remodeling-induced lung diseases. In this study, we hypothesized that PASMCs could produce H2S and relax the pulmonary artery, and its mechanism is related to CSE, CBS, and TRPV4 channels by affecting both the excessive proliferation and pulmonary vasoconstriction in PASMCs. We found that the sildenafil treatment could remarkably promote H2S production and control the proliferation in PASMCs; meanwhile, the protein levels of CSE and CBS and the intracellular concentration of calcium could also be increased by sildenafil. Moreover, the effects of sildenafil could be reversed by a CBS inhibitor or a CSE inhibitor, indicating that sildenafil could affect CSE and CBS to modulate the production of H2S and the proliferation in rat PASMCs. Together, we demonstrated a new mechanism for sildenafil to modulate the synthesis of H2S and cell proliferation in PASMCs by affecting CSE and CBS. TRPV4-dependent Ca events and BMP4 may also be involved.