Effect of Citizenship Status on Access to Pediatric Liver and Kidney Transplantation.

Transplantation of non-US citizen residents remains controversial. We evaluate national trends in transplant activity amongst pediatric non-citizen residents (PNCR). Pediatric liver and kidney transplant data were obtained from the Organ Procurement and Transplantation Network and Scientific Registry of Transplant Recipients. Data on transplanted organs, region, waitlist additions, procedures, and citizenship status were analyzed from 2012-2022. Rates of PNCR transplantation activity were compared with population rates from the US Census Bureau. On average, 713±47 pediatric liver and 1039±51 kidney patients were added to the waitlist, with 544±32 liver and 742±33 kidney transplants performed annually. Of these, PNCR comprised 1.5% and 3.3% of liver and kidney waitlist additions, and 1.5% and 2.9% of liver and kidney transplant procedures, respectively. There were no significant changes in waitlist or transplant activity nationwide over the study period. There was significant geographic variation in the percentage of waitlist additions and transplants across United Network for Organ Sharing regions amongst PNCR for liver and kidney transplantation. This is the first study to evaluate national trends in transplantation activity amongst PNCR. The significant regional variation in transplantation activity for PNCR may suggest multilevel structural and systemic barriers to transplant accessibility.

Surgical management of liver tumors.

Two percent of pediatric malignancies arise primarily in the liver; roughly 60% of these cancers are hepatoblastoma (HB). Despite the rarity of these cases, international collaborative efforts have led to the consistent histological classification and staging systems, which facilitate ongoing clinical trials. Other primary liver malignancies seen in children include hepatocellular carcinoma (HCC) with or without underlying liver disease, fibrolamellar carcinoma (FLC), undifferentiated embryonal sarcoma of the liver (UESL), and hepatocellular neoplasm not otherwise specified (HCN-NOS). This review describes principles of surgical management of malignant pediatric primary liver tumors, within the context of comprehensive multidisciplinary care.

Immediate extubation after pediatric liver transplantation: Update on a single-center experience.

PURPOSE: Immediate extubation (IE) following liver transplantation (LT) is increasingly common in adult patients. This study reviews our center's experience with IE in children following LT to determine characteristics predictive of successful IE and its effects on post-operative outcomes. METHODS: We performed a retrospective chart review of all patients who underwent LT at our institution between January 2005 and November 2022. Patients with concomitant lung transplants and chronic ventilator requirements were excluded. RESULTS: Overall, 235 patients met study criteria. IE was achieved in 164 (69.8%) patients across all diagnoses and graft types. Of IE patients, only two required re-intubation within 3 days post-transplant. IE patients exhibited significantly shorter ICU (2 [1, 3 IQR] vs. 4 [2, 4 IQR] days, p < .001) and hospital lengths of stay (17 [12, 24 IQR] vs. 22 [14, 42 IQR] days, p = .001). Pre-transplant ICU requirement, high PELD/MELD score, intraoperative transfusion, cold ischemia time, and pressor requirements were risk factors against IE. There was no association between IE and recipient age or weight. The proportion of patients undergoing IE post-transplant increased significantly over time from 2005 to 2022 (p < .001), underscoring the role of clinical experience and transplant team learning curve. CONCLUSION: Spanning 18 years and 235 patients, we report the largest cohort of children undergoing IE following LT. Our findings support that IE is safe across ages and clinical scenarios. As our center gained experience, the rate of IE increased from 40% to 83%. These trends were associated with lower ICU and LOS, the benefits of which include earlier patient mobility and improved resource utilization.

Metastatic pulmonary calcifications after pediatric liver transplantation.

BACKGROUND: Pulmonary calcification (PC) is a rare clinical entity observed following liver transplantation (LT). Most often identified in adults or in patients with concomitant renal failure, PC is rarely reported in children. While the clinical course of PC is largely benign, cases of progressive respiratory failure and death have been reported. Additionally, PC may mimic several other disease processes making diagnosis and management challenging. Currently, little is reported regarding the diagnosis, management, and long-term outcomes of children with PC following LT. METHODS: We performed a retrospective chart review of patients undergoing LT at our institution between 2006 and 2023. We identified two patients who developed PC following LT. Their diagnosis, clinical course, and long-term outcomes are reported. A literature review of the presentation, diagnosis, management, and outcomes of adult and pediatric patients with PC post-LT was also performed. CONCLUSIONS: Pulmonary calcifications are a rare but notable complication after pediatric liver transplantation. Our case series adds to the limited literature on this clinical entity in children but also highlights the fact that effective diagnosis and treatment may be safely accomplished without the use of lung biopsy.

Early Graft Loss With Suspected Seventh-Day Syndrome Following Pediatric Liver Transplantation.

INTRODUCTION: Allograft dysfunction within the first week posttransplant is an uncommon but known complication following liver transplantation. Seventh-Day Syndrome (7DS) is a rare complication of allograft dysfunction following liver transplantation characterized by the rapid clinical deterioration of a formerly well-functioning allograft within the first week posttransplant. The etiology of 7DS is unknown, and treatment options remain limited. While cases of graft survival have been reported, the risk of mortality remains exceedingly high without urgent retransplantation. METHODS: Patient data was retrospectively analyzed and a literature review performed. RESULTS: We present a unique case of split liver transplantation into two pediatric recipients in which one recipient developed rapidly progressive graft failure approximately 1 week postoperatively requiring urgent retransplantation while the other recipient had an unremarkable postoperative course. Upon clinical manifestation of progressive graft failure, the patient was treated with thymoglobulin, rituximab, intravenous immunoglobulin, and plasmapheresis. Despite this, the patient's clinical status continued to decline and she underwent retransplantation 11 days following her initial liver transplant. CONCLUSION: Seventh-Day Syndrome is a rare complication following liver transplantation that is associated with a high risk of morbidity and mortality. Our case adds to the limited literature on 7DS in children and is the first to report a comparative posttransplant clinical course in two recipients who received split grafts from the same donor.

Adjuvant conditioning induces an immunosuppressive milieu that delays alloislet rejection through the expansion of myeloid-derived suppressor cells.

Advances in immunosuppression have been relatively stagnant over the past 2 decades, and transplant recipients continue to experience long-term morbidity associated with immunosuppression regimens. Strategies to reduce or eliminate the dosage of immunosuppression medications are needed. We discovered a novel administration strategy using the classic adjuvant alum to condition murine islet transplant recipients, known as adjuvant conditioning (AC), to expand both polymorphonuclear and monocytic myeloid-derived suppressive cells (MDSCs) in vivo. These AC MDSCs potently suppress T cell proliferation when cultured together in vitro. AC MDSCs also facilitate naïve CD4+ T cells to differentiate into regulatory T cells. In addition, we were able to demonstrate a significant delay in alloislet rejection compared with that by saline-treated control following adjuvant treatment in a MDSC-dependent manner. Furthermore, AC MDSCs produce significantly more interleukin (IL)-10 than saline-treated controls, which we demonstrated to be critical for the increased T cell suppressor function of AC MDSCs as well as the observed protective effect of AC against alloislet rejection. Our data suggest that adjuvant-related therapeutics designed to expand MDSCs could be a useful strategy to prevent transplant rejection and curb the use of toxic immunosuppressive regimens currently used in transplant patients.

Intragraft B cell differentiation during the development of tolerance to kidney allografts is associated with a regulatory B cell signature revealed by single cell transcriptomics.

Mouse kidney allografts are spontaneously accepted in select, fully mismatched donor-recipient strain combinations, like DBA/2J to C57BL/6 (B6), by natural tolerance. We previously showed accepted renal grafts form aggregates containing various immune cells within 2 weeks posttransplant, referred to as regulatory T cell-rich organized lymphoid structures, which are a novel regulatory tertiary lymphoid organ. To characterize the cells within T cell-rich organized lymphoid structures, we performed single-cell RNA sequencing on CD45+ sorted cells from accepted and rejected renal grafts from 1-week to 6-months posttransplant. Analysis of single-cell RNA sequencing data revealed a shifting from a T cell-dominant to a B cell-rich population by 6 months with an increased regulatory B cell signature. Furthermore, B cells were a greater proportion of the early infiltrating cells in accepted vs rejecting grafts. Flow cytometry of B cells at 20 weeks posttransplant revealed T cell, immunoglobulin domain and mucin domain-1+ B cells, potentially implicating a regulatory role in the maintenance of allograft tolerance. Lastly, B cell trajectory analysis revealed intragraft differentiation from precursor B cells to memory B cells in accepted allografts. In summary, we show a shifting T cell- to B cell-rich environment and a differential cellular pattern among accepted vs rejecting kidney allografts, possibly implicating B cells in the maintenance of kidney allograft acceptance.

Triple gallbladder with heterotopic gastric mucosa: a case report.

BACKGROUND: Triple gallbladder is a rare congenital anomaly of the biliary tract that can be associated with heterotopic tissue. Gallbladder triplication results from the failure of rudimentary bile ducts to regress during embryological development, and can be difficult to distinguish from Todani type II choledochal cysts and biliary duplication cysts. CASE PRESENTATION: A 2-year-old patient presented to our institution with intermittent abdominal pain for 1 year. She had elevated transaminases with imaging concerning for a choledochal cyst. After assessment with magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography, she was diagnosed with a gallbladder multiplication and a common bile duct stricture. She underwent laparoscopic cholecystectomy, which confirmed the diagnosis of triple gallbladder. One of the three gallbladders demonstrated heterotopic gastric mucosa on final pathology, including at the cystic duct margin. Follow up testing with a technetium 99 m scan demonstrated a subtle focus of increased activity in the right upper abdomen at the expected location of the common bile duct, concerning for the presence of residual gastric mucosa. The patient remains well without abdominal pain. CONCLUSIONS: We describe the first case of heterotopic gastric mucosa in a triple gallbladder in a young patient presenting with chronic abdominal pain. We also demonstrate the safety and feasibility of laparoscopic cholecystectomy in young children with triple gallbladder. Finally, we propose an interdisciplinary approach to the management of common bile duct strictures in the setting of ectopic acid secretion, involving a combination of medical management, endoscopic intervention, and possible salvage laparoscopic Roux-en-Y hepaticojejunostomy.

Pediatric liver transplant following near catastrophic head bleed: Lessons learned.

Evaluation for liver transplant candidacy is a multidisciplinary effort that involves all aspects of clinical care including social work, nutrition, and a multitude of medical specialties. The prognosis of a pretransplant clinical condition is integrated into the decision to list a patient. Herein, we report a successful liver transplant and recovery of a 3-month-old male following a large right hemispheric subdural hematoma related to acute coagulopathy secondary to undiagnosed end-stage liver disease. On presentation with jaundice, lethargy, and unequal pupils, a CT scan was obtained which demonstrated a large right subdural hematoma with herniation. Once his coagulopathy was corrected, he went for decompressive craniectomy. He survived with medically controlled seizures and improving L-sided neglect and extremity weakness. Six weeks later, given his continued neurologic recovery and worsening liver function, the decision was made to list him for liver transplantation. One month later, he underwent orthotopic liver transplant. His post-operative hospital course was complicated by DVTs and heparin-induced thrombocytopenia, but no neurologic decline, and he was eventually discharged from the hospital on post-op day 26. Three years later, he has a well-functioning allograft and no clinically evident neurologic deficits. The prognosis following pediatric neurologic trauma remains somewhat unclear as recovery and neurologic examinations can be influenced by numerous extrinsic factors. This is one of the first reports of near full neurologic recovery of a pediatric liver transplant recipient following a large subdural hematoma with herniation.

TRIF-dependent innate immune activation is critical for survival to neonatal gram-negative sepsis.

Current evidence suggests that neonatal immunity is functionally distinct from adults. Although TLR signaling through the adaptor protein, MyD88, has been shown to be critical for survival to sepsis in adults, little is known about the role of MyD88 or TRIF in neonatal sepsis. We demonstrate that TRIF(-/-) but not MyD88(-/-) neonates are highly susceptible to Escherichia coli peritonitis and bacteremia. This was associated with decreased innate immune recruitment and function. Importantly, we found that the reverse was true in adults that MyD88(-/-) but not TRIF(-/-) or wild-type adults are susceptible to E. coli peritonitis and bacteremia. In addition, we demonstrate that TRIF but not MyD88 signaling is critical for the TLR4 protective adjuvant effect we have previously demonstrated. These data suggest a differential requirement for the survival of neonates versus adults to Gram-negative infection, and that modulation of TRIF in neonates can be used to augment survival to neonatal sepsis.

Protective immunity and defects in the neonatal and elderly immune response to sepsis.

Populations encompassing extremes of age, including neonates and elderly, have greater mortality from sepsis. We propose that the increased mortality observed in the neonatal and elderly populations after sepsis is due to fundamental differences in host-protective immunity and is manifested at the level of the leukocyte transcriptome. Neonatal (5-7 d), young adult (6-12 wk), or elderly (20-24 mo) mice underwent a cecal slurry model of intra-abdominal sepsis. Both neonatal and elderly mice exhibited significantly greater mortality to sepsis (p < 0.05). Neonates in particular exhibited significant attenuation of their inflammatory response (p < 0.05), as well as reductions in cell recruitment and reactive oxygen species production (both p < 0.05), all of which could be confirmed at the level of the leukocyte transcriptome. In contrast, elderly mice were also more susceptible to abdominal peritonitis, but this was associated with no significant differences in the magnitude of the inflammatory response, reduced bacterial killing (p < 0.05), reduced early myeloid cell activation (p < 0.05), and a persistent inflammatory response that failed to resolve. Interestingly, elderly mice expressed a persistent inflammatory and immunosuppressive response at the level of the leukocyte transcriptome, with failure to return to baseline by 3 d. This study reveals that neonatal and elderly mice have profoundly different responses to sepsis that are manifested at the level of their circulating leukocyte transcriptome, although the net result of increased mortality is similar. Considering these differences are fundamental aspects of the genomic response to sepsis, interventional therapies will require individualization based on the age of the population.

Aged mice are unable to mount an effective myeloid response to sepsis.

The elderly have increased morbidity and mortality following sepsis; however, the cause(s) remains unclear. We hypothesized that these poor outcomes are due in part to defects in innate immunity, rather than to an exaggerated early inflammatory response. Young (6-12 wk) or aged (20-24 mo) mice underwent polymicrobial sepsis, and subsequently, the aged mice had increased mortality and defective peritoneal bacterial clearance compared with young mice. No differences were found in the magnitude of the plasma cytokine responses. Although septic aged mice displayed equivalent or increased numbers of circulating, splenic, and bone marrow myeloid cells, some of these cells exhibited decreased phagocytosis, reactive oxygen species production, and chemotaxis. Blood leukocyte gene expression was less altered in aged versus young mice 1 d after sepsis. Aged mice had a relative inability to upregulate gene expression of pathways related to neutrophil-mediated protective immunity, chemokine/chemokine receptor binding, and responses to exogenous molecules. Expression of most MHC genes remained more downregulated in aged mice at day 3. Despite their increased myeloid response to sepsis, the increased susceptibility of aged mice to sepsis appears not to be due to an exaggerated inflammatory response, but rather, a failure to mount an effective innate immune response.

Novel role for tumor-induced expansion of myeloid-derived cells in cancer cachexia.

Cancer progression is associated with inflammation, increased metabolic demand, infection, cachexia, and eventually death. Myeloid-derived suppressor cells (MDSCs) commonly expand during cancer and are associated with adaptive immune suppression and inflammatory metabolite production. We propose that cancer-induced cachexia is driven at least in part by the expansion of MDSCs. MDSC expansion in 4T1 mammary carcinoma-bearing hosts is associated with induction of a hepatic acute-phase protein response and altered host energy and fat metabolism, and eventually reduced survival to polymicrobial sepsis and endotoxemia. Similar results are also seen in mice bearing a Lewis lung carcinoma and a C26 colon adenocarcinoma. However, a similar cachexia response is not seen with equivalent growth of the 66C4 subclone of 4T1, in which MDSC expansion does not occur. Importantly, reducing MDSC numbers in 4T1-bearing animals can ameliorate some of these late responses and reduce susceptibility to inflammation-induced organ injury and death. In addition, administering MDSCs from both tumor- and nontumor-bearing mice can produce an acute-phase response. Thus, we propose a previously undescribed mechanism for the development of cancer cachexia, whereby progressive MDSC expansion contributes to changes in host protein and energy metabolism and reduced resistance to infection.

Genomic responses in mouse models poorly mimic human inflammatory diseases.

A cornerstone of modern biomedical research is the use of mouse models to explore basic pathophysiological mechanisms, evaluate new therapeutic approaches, and make go or no-go decisions to carry new drug candidates forward into clinical trials. Systematic studies evaluating how well murine models mimic human inflammatory diseases are nonexistent. Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another. Among genes changed significantly in humans, the murine orthologs are close to random in matching their human counterparts (e.g., R(2) between 0.0 and 0.1). In addition to improvements in the current animal model systems, our study supports higher priority for translational medical research to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory diseases.

Improved emergency myelopoiesis and survival in neonatal sepsis by caspase-1/11 ablation.

Over one million newborns die annually from sepsis with the highest mortality in premature and low-birthweight infants. The inflammasome plays a central role in the regulation of innate immunity and inflammation, and is presumed to be involved in protective immunity, in large part through the caspase-1-dependent activation of interleukin-1ß (IL-1ß) and IL-18. Studies in endotoxic shock, however, suggest that endogenous caspase-1 activity and the inflammasome contribute to mortality primarily by promoting excessive systemic inflammatory responses. We examined whether caspase-1 and the inflammasome also regulate neonatal inflammation, host protective immunity and myelopoiesis during polymicrobial sepsis. Neonatal (5-7 days) C57BL/6 and caspase-1/11(-/-) mice underwent a low-lethality caecal slurry model of intra-abdominal sepsis (LD25-45 ). Ablation of caspase-1/11, but not apoptosis-associated speck-like protein containing a CARD domain or nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), improved neonatal survival following septic challenge compared with wild-type mice (P < 0·001), with decreased concentrations of inflammatory cytokines in the serum and peritoneum. Surprisingly, caspase-1/11(-/-) neonates also exhibited increased bone marrow and splenic haematopoietic stem cell expansion (P < 0·001), and increased concentrations of granulocyte and macrophage colony-stimulating factors in the peritoneum (P < 0·001) after sepsis. Ablation of caspase-1/11 signalling was also associated with increased recruitment of peritoneal macrophages and neutrophils (P < 0·001), increased phagocytosis by neutrophils (P = 0·003), and decreased bacterial colonization (P = 0·02) in the peritoneum. These findings suggest that endogenous caspase-1/11 activity, independent of the NLRP3 inflammasome, not only promotes the magnitude of the inflammatory response, but also suppresses protective immunity in the neonate, so contributing to innate immune dysfunction and poor survival in neonatal sepsis.

A better understanding of why murine models of trauma do not recapitulate the human syndrome.

OBJECTIVE: Genomic analyses from blood leukocytes have concluded that mouse injury poorly reflects human trauma at the leukocyte transcriptome. Concerns have focused on the modest severity of murine injury models, differences in murine compared with human age, dissimilar circulating leukocyte populations between species, and whether similar signaling pathways are involved. We sought to examine whether the transcriptomic response to severe trauma in mice could be explained by these extrinsic factors, by utilizing an increasing severity of murine trauma and shock in young and aged mice over time, and by examining the response in isolated neutrophil populations. DESIGN: Preclinical controlled in vivo laboratory study and retrospective cohort study. SETTING: Laboratory of Inflammation Biology and Surgical Science and multi-institution level 1 trauma centers. SUBJECTS: Six- to 10-week-old and 20- to 24-month-old C57BL/6 (B6) mice and two cohorts of 167 and 244 severely traumatized (Injury Severity Score > 15) adult (> 18 yr) patients. INTERVENTIONS: Mice underwent one of two severity polytrauma models of injury. Total blood leukocyte and neutrophil samples were collected. MEASUREMENTS AND MAIN RESULTS: Fold expression changes in leukocyte and neutrophil genome-wide expression analyses between healthy and injured mice (p < 0.001) were compared with human total and enriched blood leukocyte expression analyses of severe trauma patients at 0.5, 1, 4, 7, 14, and 28 days after injury (Glue Grant trauma-related database). We found that increasing the severity of the murine trauma model only modestly improved the correlation in the transcriptomic response with humans, whereas the age of the mice did not. In addition, the genome-wide response to blood neutrophils (rather than total WBC) was also not well correlated between humans and mice. However, the expression of many individual gene families was much more strongly correlated after injury in mice and humans. CONCLUSIONS: Although overall transcriptomic association remained weak even after adjusting for the severity of injury, age of the animals, timing, and individual leukocyte populations, there were individual signaling pathways and ontogenies that were strongly correlated between mice and humans. These genes are involved in early inflammation and innate/adaptive immunity.

Is there value in plasma cytokine measurements in patients with severe trauma and sepsis?

For the past thirty years, since IL-1ß and TNFα were first cloned, there have been efforts to measure plasma cytokine concentrations in patients with severe sepsis and trauma, and to use these measurements to predict clinical outcome and response to therapies. The numbers of cytokines and chemokines that have been measured in the plasma have literally exploded with the development of multiplex immune approaches. Dozens of relatively small cohort studies have shown plasma cytokine concentrations correlating with outcome in sepsis and trauma. Despite what appears to be a consensus that plasma cytokine concentrations should be useful in the clinical setting, only two cytokines, IL-6 and procalcitonin, have approached routine clinical use. IL-6 has been used as a research tool for entry into sepsis-intervention trials, while procalcitonin is being used clinically at a large number of institutions to distinguish sepsis from other inflammatory processes. For most cytokines, the relative lack of sensitivity and specificity of individual or multiplex cytokine measurements has hindered their utility to predict clinical trajectory in individual patients. The problem rests with a general misunderstanding of cytokine biology, failing to appreciate the general paracrine nature of these mediators, the presence of binding proteins, chaperones and inhibitors in the plasma, and the rapid clearance of these proteins by binding to cell receptors and clearance predominantly by the kidney. The future of using plasma cytokine measurements as an indicator of sepsis/trauma severity or predicting outcome is generally behind us, although there is optimism that procalcitonin measurements may ultimately prove to have utility in the diagnosis of severe sepsis.

Identification and description of a novel murine model for polytrauma and shock.

OBJECTIVE: To develop a novel polytrauma model that better recapitulates the immunologic response of the severely injured patient by combining long-bone fracture, muscle tissue damage, and cecectomy with hemorrhagic shock, resulting in an equivalent Injury Severity Score of greater than 15. We compared this new polytrauma/shock model to historically used murine trauma-hemorrhage models. DESIGN: Pre-clinical controlled in vivo laboratory study. SETTING: Laboratory of Inflammation Biology and Surgical Science. SUBJECTS: Six- to 10-week-old C57BL/6 (B6) mice. INTERVENTIONS: Mice underwent 90 minutes of shock (mean arterial pressure 30 mm Hg) and resuscitation via femoral artery cannulation followed by laparotomy (trauma-hemorrhage), hemorrhage with laparotomy and femur fracture, or laparotomy with cecetomy and femur fracture with muscle tissue damage (polytrauma). Mice were euthanized at 2 hours, 1 day, and 3 days postinjury. MEASUREMENTS AND MAIN RESULTS: The spleen, bone marrow, blood, and serum were collected from mice for analysis at the above time points. None of the models were lethal. Mice undergoing polytrauma exhibited a more robust inflammatory response with significant elevations in cytokine/chemokine concentrations when compared with traditional models. Polytrauma was the only model to induce neutrophilia (Ly6G (+)CD11b(+) cells) on days 1 and 3 (p<0.05). Polytrauma, as compared to trauma-hemorrhage and hemorrhage with laparotomy and femur fracture, induced a loss of circulating CD4(+) T cell with simultaneous increased cell activation (CD69(+) and CD25(+)), similar to human trauma. There was a prolonged loss of major histocompatibility complex class II expression on monocytes in the polytrauma model (p<0.05). Results were confirmed by genome-wide expression analysis that revealed a greater magnitude and duration of blood leukocyte gene expression changes in the polytrauma model than the trauma-hemorrhage and sham models. CONCLUSIONS: This novel polytrauma model better replicates the human leukocyte, cytokine, and overall inflammatory response following injury and hemorrhagic shock.

Development of a genomic metric that can be rapidly used to predict clinical outcome in severely injured trauma patients.

OBJECTIVE: Many patients have complicated recoveries following severe trauma due to the development of organ injury. Physiological and anatomical prognosticators have had limited success in predicting clinical trajectories. We report on the development and retrospective validation of a simple genomic composite score that can be rapidly used to predict clinical outcomes. DESIGN: Retrospective cohort study. SETTING: Multi-institutional level 1 trauma centers. PATIENTS: Data were collected from 167 severely traumatized (injury severity score >15) adult (18-55 yr) patients. METHODS: Microarray-derived genomic data obtained from 167 severely traumatized patients over 28 days were assessed for differences in messenger RNA abundance among individuals with different clinical trajectories. Once a set of genes was identified based on differences in expression over the entire study period, messenger RNA abundance from these subjects obtained in the first 24 hours was analyzed in a blinded fashion using a rapid multiplex platform, and genomic data reduced to a single metric. RESULTS: From the existing genomic dataset, we identified 63 genes whose leukocyte expression differed between an uncomplicated and complicated clinical outcome over 28 days. Using a multiplex approach that can quantitate messenger RNA abundance in less than 12 hours, we reassessed total messenger RNA abundance from the first 24 hours after trauma and reduced the genomic data to a single composite score using the difference from reference. This composite score showed good discriminatory capacity to distinguish patients with a complicated outcome (area under a receiver-operator curve, 0.811; p <0.001). This was significantly better than the predictive power of either Acute Physiology and Chronic Health Evaluation II or new injury severity score scoring systems. CONCLUSIONS: A rapid genomic composite score obtained in the first 24 hours after trauma can retrospectively identify trauma patients who are likely to develop complicated clinical trajectories. A novel platform is described in which this genomic score can be obtained within 12 hours of blood collection, making it available for clinical decision making.

Neutrophil mobilization from the bone marrow during polymicrobial sepsis is dependent on CXCL12 signaling.

Neutrophils are essential for successful host eradication of bacterial pathogens and for survival to polymicrobial sepsis. During inflammation, the bone marrow provides a large reserve of neutrophils that are released into the peripheral circulation where they traverse to sites of infection. Although neutrophils are essential for survival, few studies have investigated the mechanisms responsible for neutrophil mobilization from the bone marrow during polymicrobial sepsis. Using a cecal ligation and puncture model of polymicrobial sepsis, we demonstrated that neutrophil mobilization from the bone marrow is not dependent on TLR4, MyD88, TRIF, IFNARα/ß, or CXCR2 pathway signaling during sepsis. In contrast, we observed that bone marrow CXCL12 mRNA abundance and specific CXCL12 levels are sharply reduced, whereas splenic CXCR4 mRNA and cell surface expression are increased during sepsis. Blocking CXCL12 activity significantly reduced blood neutrophilia by inhibiting bone marrow release of granulocytes during sepsis. However, CXCL12 inhibition had no impact on the expansion of bone marrow neutrophil precursors and hematopoietic progenitors. Bone marrow neutrophil retention by CXCL12 blockade prevented blood neutrophilia, inhibited peritoneal neutrophil accumulation, allowed significant peritoneal bacterial invasion, and increased polymicrobial sepsis mortality. We concluded that changes in the pattern of CXCL12 signaling during sepsis are essential for neutrophil bone marrow mobilization and host survival but have little impact on bone marrow granulopoiesis.