Ranjit S. Chima

Diagnostic and risk criteria for HSCT-associated thrombotic microangiopathy: a study in children and young adults

Transplant-associated thrombotic microangiopathy (TMA) leads to generalized endothelial dysfunction that can progress to multiorgan injury, and severe cases are associated with poor outcomes after hematopoietic stem cell transplantation (HSCT). Identifying patients at highest risk for severe disease is challenging. We prospectively evaluated 100 consecutive HSCT recipients to determine the incidence of moderate and severe TMA and factors associated with poor overall outcomes. Thirty-nine subjects (39%) met previously published criteria for TMA. Subjects with TMA had a significantly higher nonrelapse mortality (43.6% vs 7.8%, P < .0001) at 1 year post-HSCT compared with those without TMA. Elevated lactate dehydrogenase, proteinuria on routine urinalysis, and hypertension were the earliest markers of TMA. Proteinuria (>30 mg/dL) and evidence of terminal complement activation (elevated sC5b-9) in the blood at the time of TMA diagnosis were associated with very poor survival (<20% at 1 year), whereas all TMA subjects without proteinuria and a normal sC5b-9 serum concentration survived (P < .01). Based on these prospective observations, we conclude that severe TMA occurred in 18% of HSCT recipients in our cohort and propose an algorithm to identify the highest-risk patients who might benefit from prompt clinical interventions.

Validation of a gene expression-based subclassification strategy for pediatric septic shock

Objective:Septic shock heterogeneity has important implications for clinical trial implementation and patient management. We previously addressed this heterogeneity by identifying three putative subclasses of children with septic shock based exclusively on a 100-gene expression signature. Here we attempted to prospectively validate the existence of these gene expression-based subclasses in a validation cohort. Design:Prospective observational study involving microarray-based bioinformatics. Setting:Multiple pediatric intensive care units in the United States. Patients:Separate derivation (n = 98) and validation (n = 82) cohorts of children with septic shock. Interventions:None other than standard care. Measurements and Main Results:Gene expression mosaics of the 100 class-defining genes were generated for 82 individual patients in the validation cohort. Using computer-based image analysis, patients were classified into one of three subclasses (“A,” “B,” or “C”) based on color and pattern similarity relative to reference mosaics generated from the original derivation cohort. After subclassification, the clinical database was mined for phenotyping. Subclass A patients had higher illness severity relative to subclasses B and C as measured by maximal organ failure, fewer intensive care unit-free days, and a higher Pediatric Risk of Mortality score. Patients in subclass A were characterized by repression of genes corresponding to adaptive immunity and glucocorticoid receptor signaling. Separate subclass assignments were conducted by 21 individual clinicians using visual inspection. The consensus classification of the clinicians had modest agreement with the computer algorithm. Conclusions:We have validated the existence of subclasses of children with septic shock based on a biologically relevant, 100-gene expression signature. The subclasses have relevant clinical differences.

Toward a clinically feasible gene expression-based subclassification strategy for septic shock: proof of concept.

Objective:To develop a clinically feasible stratification strategy for pediatric septic shock, using gene expression mosaics and a 100-gene signature representing the first 24 hrs of admission to the pediatric intensive care unit. Design:Prospective, observational study involving microarray-based bioinformatics. Setting:Multiple pediatric intensive care units in the United States. Patients:Ninety-eight children with septic shock. Interventions:None other than standard care. Measurements and Main Results:Patients were classified into three previously published, genome-wide, expression-based subclasses (subclasses A, B, and C) having clinically relevant phenotypic differences. The class-defining 100-gene signature was depicted for each individual patient, using mosaics generated by the Gene Expression Dynamics Inspector (GEDI). Composite mosaics were generated representing the average expression patterns for each of the three subclasses. Nine individual clinicians served as blinded evaluators. Each evaluator was shown the 98 individual patient mosaics and asked to classify each patient into one of the three subclasses, using the composite mosaics as the reference point. The respective sensitivities, specificities, positive predictive values, and negative predictive values of the subclassification strategy were ≥84% across the three subclasses. The classification strategy also generated positive likelihood ratios of ≥16.8 and negative likelihood ratios of ≤0.2 across the three subclasses. The &kgr; coefficient across all possible interevaluator comparisons was 0.81. Conclusions:We have provided initial evidence (proof of concept) for a clinically feasible and robust stratification strategy for pediatric septic shock based on a 100-gene signature and gene expression mosaics.

Pulmonary Arterial Hypertension in Pediatric Patients with Hematopoietic Stem Cell Transplant–Associated Thrombotic Microangiopathy

Pulmonary arterial hypertension (PAH) is rarely included in the differential diagnosis of cardiorespiratory failure after pediatric hematopoietic stem cell transplant (HSCT) as the clinical presentation is nonspecific and may mimic other etiologies. The pathogenesis of PAH in HSCT is poorly understood and the diagnosis requires a high degree of suspicion. We describe 5 children diagnosed with PAH after allogeneic HSCT. All 5 patients had prolonged clinical signs of transplantation-associated thrombotic microangiopathy (TA-TMA) when they presented with hypoxemic respiratory failure and evidence of PAH. Four of the 5 patients had echocardiographic evidence of PAH, and 1 patient was diagnosed with PAH only on autopsy. PAH was diagnosed a median of 76 days (range, 56-101 days) after a diagnosis of TA-TMA. Despite aggressive medical management, including inhaled nitric oxide, 4 of the 5 patients died. One patient recovered from PAH after 11 months of sildenafil therapy. Three of the 4 deceased patients had an autopsy performed, demonstrating severe pulmonary vascular disease consistent with TA-TMA and severe PAH. We conclude that TA-TMA can be associated with significant pulmonary vascular injury presenting as hypoxemic respiratory failure with PAH after HSCT. Pediatric patients with unexplained hypoxemia after HSCT should be evaluated for both transplantation complications, TA-TMA and PAH, accordingly.

Ciglitazone ameliorates lung inflammation by modulating the inhibitor κB protein kinase/nuclear factor-κB pathway after hemorrhagic shock

Objective:Peroxisome proliferator-activated receptor-γ is a ligand-activated transcription factor. Ciglitazone, a peroxisome proliferator-activated receptor-γ ligand, has been shown to provide beneficial effects in experimental models of sepsis and ischemia/reperfusion injury. We investigated the effects of ciglitazone on lung inflammation after severe hemorrhage. Design:Prospective, laboratory study, rodent model of hemorrhagic shock. Setting:University hospital laboratory. Subjects:Male rats. Interventions:Hemorrhagic shock was induced by withdrawing blood to a mean arterial pressure of 50 mm Hg. At 3 hrs after hemorrhage, rats were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, animals received ciglitazone (10 mg/kg) or vehicle intraperitoneally. Heart rate and mean arterial pressure were measured throughout the experiment. Plasma and lung tissue were collected for analysis up to 3 hrs after resuscitation. Measurements and Main Results:Ciglitazone treatment ameliorated mean arterial pressure, reduced lung injury, significantly blunted lung neutrophil infiltration, and lowered plasma interleukin-6, interleukin-10, and monocyte chemoattractant protein-1 levels. In a time course analysis, vehicle-treated rats had a significant increase in nuclear factor-&kgr;B DNA binding, which was preceded by increased inhibitor &kgr;B protein kinase activity and inhibitor &kgr;Bα degradation in the lung. Treatment with ciglitazone significantly reduced inhibitor &kgr;B protein kinase activity and inhibitor &kgr;Bα degradation and completely inhibited nuclear factor-&kgr;B DNA binding. This reduction of inhibitor &kgr;B protein kinase activity afforded by ciglitazone appeared to be a consequence of a physical interaction between peroxisome proliferator-activated receptor-γ and increased inhibitor &kgr;B protein kinase. Conclusion:Ciglitazone ameliorates the inflammatory response and may reduce lung injury after hemorrhagic shock. These protective effects appear to be mediated through inhibition of the inhibitor &kgr;B protein kinase/nuclear factor-&kgr;B pathway.

Differences in medical therapy goals for children with severe traumatic brain injury-an international study.

Objectives: To describe the differences in goals for their usual practice for various medical therapies from a number of international centers for children with severe traumatic brain injury. Design: A survey of the goals from representatives of the international centers. Setting: Thirty-two pediatric traumatic brain injury centers in the United States, United Kingdom, France, and Spain. Patients: None. Interventions: None. Measurements and Main Results: A survey instrument was developed that required free-form responses from the centers regarding their usual practice goals for topics of intracranial hypertension therapies, hypoxia/ischemia prevention and detection, and metabolic support. Cerebrospinal fluid diversion strategies varied both across centers and within centers, with roughly equal proportion of centers adopting a strategy of continuous cerebrospinal fluid diversion and a strategy of no cerebrospinal fluid diversion. Use of mannitol and hypertonic saline for hyperosmolar therapies was widespread among centers (90.1% and 96.9%, respectively). Of centers using hypertonic saline, 3% saline preparations were the most common but many other concentrations were in common use. Routine hyperventilation was not reported as a standard goal and 31.3% of centers currently use PbO2 monitoring for cerebral hypoxia. The time to start nutritional support and glucose administration varied widely, with nutritional support beginning before 96 hours and glucose administration being started earlier in most centers. Conclusions: There were marked differences in medical goals for children with severe traumatic brain injury across our international consortium, and these differences seemed to be greatest in areas with the weakest evidence in the literature. Future studies that determine the superiority of the various medical therapies outlined within our survey would be a significant advance for the pediatric neurotrauma field and may lead to new standards of care and improved study designs for clinical trials.

Improved outcomes for stem cell transplant recipients requiring pediatric intensive care

Objectives: Survival for hematopoietic stem cell transplant patients requiring pediatric intensive care unit admission may be improving. This study was conducted to review outcomes for patients undergoing hematopoietic stem cell transplantation requiring admission to our pediatric intensive care unit and to identify variables impacting survival. Design: Retrospective database review. Setting: Pediatric intensive care unit and bone marrow transplant service of a children’s hospital. Patients: Patients undergoing hematopoietic stem cell transplantation at our center from July 2004 through June 2010 requiring pediatric intensive care unit admission during the same period. Measurements and Main Results: Thirty-five percent of patients (155 of 448) undergoing hematopoietic stem cell transplantation required 319 admissions over this period. Of these 155 patients, 63% (97 of 155) were discharged alive following their most recent admission with a 100-day survival of 51% (79 of 155). Forty-five percent (69 of 155) of patients were still alive on long-term follow-up. Intubation and mechanical ventilation were required for 57% (88 of 155) of patients, with 39% (34 of 88) of patients surviving their last pediatric intensive care unit admission. Renal support was utilized for 25% (38 of 155) of patients with 34% (13 of 38) survival to pediatric intensive care unit discharge. Admissions surviving to pediatric intensive care unit discharge had significantly lower Pediatric Risk of Mortality II scores, shorter pediatric intensive care unit length of stay, lower utilization of intubation and mechanical ventilation with fewer ventilator days, and lower use of renal support when compared to nonsurvivors. Of note, each prior pediatric intensive care unit admission significantly reduced the odds of pediatric intensive care unit survival. Conclusions: We report a 63% survival to pediatric intensive care unit discharge, with 45% surviving at a median follow-up of over 2 yrs for all hematopoietic stem cell transplantation patients admitted to our pediatric intensive care unit over a 6-yr period. Our data suggest improved survival outcomes for this high risk patient population.

Pulmonary Hypertension after Hematopoietic Stem Cell Transplantation

Pulmonary hypertension (PH) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT). Given its nonspecific clinical presentation, it is likely that this clinical entity is underdiagnosed after HSCT. Data describing the incidence, risk factors, and etiology of PH in HSCT recipients are minimal. Physicians caring for HSCT recipients should be aware of this severe post-transplant complication because timely diagnosis and treatment may allow improved clinical outcomes. We summarize the pathophysiology, clinical presentation, diagnosis, and management of PH in HSCT recipients.

Abnormal Echocardiography 7 Days after Stem Cell Transplantation May Be an Early Indicator of Thrombotic Microangiopathy

Cardiac complications after hematopoietic stem cell transplantation (HSCT) can lead to significant morbidity and mortality. Cardiac evaluation during the first 100 days after HSCT is usually performed only if clinically indicated, and no studies have examined whether routine screening is beneficial in this patient population at high risk for tissue injury. We conducted a single-center prospective clinical study to screen for cardiac complications in pediatric and young adult patients. One hundred consecutive HSCT patients underwent scheduled echocardiographic screening on day +7 after transplantation, independent of their clinical condition. At least 1 abnormality was identified in 30% of cases. Seventeen children had a pericardial effusion, 13 elevated right ventricular pressure, and 3 reduced left ventricular function. Survival was reduced in children with any echocardiographic abnormality at day 7 (67% versus 80% in those with and without, respectively, abnormality, P = .073). Moreover, raised right ventricular pressure at day +7 was significantly associated with transplant-associated thrombotic microangiopathy (TA-TMA; P = .004) and may indicate early vascular injury in the lungs. These data suggest that echocardiography 7 days after HSCT can detect early cardiac complications of HSCT and may identify early vascular injury associated with TA-TMA.

C-peptide ameliorates kidney injury following hemorrhagic shock.

Reperfusion injury following hemorrhagic shock is accompanied by the development of a systemic inflammatory state that may lead to organ failure. Insulin connecting peptide (C-peptide) has been shown to exert anti-inflammatory effects in sepsis and myocardial ischemia-reperfusion injury and to ameliorate renal dysfunction in diabetic animals. Hence, we investigated the effect of C-peptide on kidney injury after hemorrhagic shock. We hypothesized that C-peptide would exert renoprotective effects by blunting inflammation. Hemorrhagic shock was induced in male rats (3-4 months old) by withdrawing blood from the femoral artery to a mean arterial pressure of 50 mmHg. Animals were kept in shock for 3 h, at which time they were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, one group of animals received C-peptide (280 nmol/kg), whereas another group received vehicle. Hemorrhagic shock resulted in significant rise in plasma levels of creatinine and elevated kidney neutrophil infiltration as evaluated by myeloperoxidase activity in vehicle-treated rats in comparison with sham rats, thus suggesting kidney injury. Treatment with C-peptide significantly attenuated the rise in creatinine and kidney myeloperoxidase activity when compared with vehicle group. At a molecular level, these effects of C-peptide were associated with reduced expression of the c-Fos subunit and reduced activation of the proinflammatory kinases, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase and subsequently reduced DNA binding of activator protein 1 in the kidney. Thus, our data suggest that C-peptide may exert renoprotective effects after hemorrhagic shock by modulating activator protein 1 signaling.