Transcriptomic and Proteomic Characterization of the Immune Response to Elective Spinal Reconstructive Surgery: Impact of Aging and Comparison with Traumatic Injury Response.

BACKGROUND: Major surgery triggers trauma-like stress responses linked to age, surgery duration, and blood loss, resembling polytrauma. This similarity suggests elective surgery as a surrogate model for studying polytrauma immune responses. We investigated stress responses across age groups and compared them with those of polytrauma patients. STUDY DESIGN: Patients undergoing major spinal reconstruction surgery were divided into older (age >65 years, n = 5) and young (age 18 to 39 years, n = 6) groups. A comparison group consisted of matched trauma patients (n = 8). Blood samples were collected before, during, and after surgery. Bone marrow mononuclear cells and peripheral blood mononuclear cells were analyzed using cellular indexing of transcriptomes and epitopes sequencing or single-cell RNA sequencing. Plasma was subjected to dual-platform proteomic analysis (SomaLogic and O-link). RESULTS: Response to polytrauma was highest within 4 hours. By comparison, the response to surgery was highest at 24 hours. Both insults triggered significant changes in cluster of differentiation 14 monocytes, with increased inflammation and lower major histocompatibility complex-class 2 expression. Older patient's cluster of differentiation 14 monocytes displayed higher inflammation and less major histocompatibility complex-class 2 suppression; a trend was also seen in bone marrow mononuclear cells. Although natural killer cells were markedly activated after polytrauma, they were suppressed after surgery, especially in older patients. In plasma, innate immunity proteins dominated at 24 hours, shifting to adaptive immunity proteins by 6 weeks with heightened inflammation in older patients. Senescence-associated secretory phenotype proteins were higher in older patients at baseline and further elevated during and after surgery. CONCLUSIONS: Although both major surgery and polytrauma initiate immune and stress responses, substantial differences exist in timing and cellular profiles, suggesting major elective surgery is not a suitable surrogate for the polytrauma response. Nonetheless, distinct responses in young vs older patients highlight the utility of elective spinal in studying patient-specific factors affecting outcomes after major elective surgery.

Predictors of chronic thromboembolic pulmonary hypertension in patients with submassive pulmonary embolism treated with catheter-directed thrombolysis versus anticoagulation alone: A secondary analysis of the SUNSET sPE trial.

OBJECTIVE: Chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism (PE) is a morbid complication with suboptimal treatment. We aimed to evaluate the biomarker profile and functional outcomes in patients with submassive PE (sPE) treated with catheter-directed thrombolysis (CDT) compared with anticoagulation alone (ACA). We performed a secondary biomarker and survey analysis of the SUNSET sPE (standard vs ultrasound-assisted catheter thrombolysis for submassive pulmonary embolism) randomized trial comparing standard CDT to ultrasound-assisted thrombolysis in patients with sPE. METHODS: As a part of the SUNSET sPE study, patients who did not receive an intervention were enrolled in the medical (ACA) arm. The biomarkers associated with CTEPH in the literature (ie, CCL2, CXCL10, PTX3, GDF-15, RAGE, BCA-1, TFPI) were collected and measured using a multiplex assay at diagnosis, discharge, and 3-month follow-up. Patients underwent a 6-minute walk test and answered quality-of-life questionnaires (pulmonary embolism quality of life; University of California, San Diego, shortness of breath questionnaire; 36-item short-form survey) at 3 months after diagnosis. Comparisons were made using the Student t test. Nonparametric tests were used when the distributions were not normal. Significance was set at P ≤ .05. RESULTS: A total of 72 patients (age, 56 ± 15 years; 40.3% women) were included in the present analysis. Of these 72 patients, 53 underwent CDT and 19 were included in the ACA arm. The baseline right ventricle/left ventricle ratios were similar between the two groups (CST, 1.8; ACA, 1.7). The survival and complication rates were similar between the two groups. At discharge, CXCL10 (768.9 ± 148.6 pg/mL vs 3032.0 ± 1201.0 pg/mL; P = .018) and PTX3 (3203.5 ± 1298.0 pg/mL vs 12,716.2 ± 6961.5 pg/mL; P = .029) were lower in the CDT group and displayed a quicker return to baseline than in the ACA group. This trend, although not significant, was also seen with the other biomarkers. At 3 months, the 6-minute walking distance and quality-of-life scores were similar between both groups. CONCLUSIONS: In patients with sPE, the biomarkers of CTEPH were lower with CDT compared with ACA. At 3 months, both groups demonstrated similar biomarker levels, 6-minute walking distances, and quality-of-life scores.

High-dimensional proteomics identifies organ injury patterns associated with outcomes in human trauma.

INTRODUCTION: Severe traumatic injury with shock can lead to direct and indirect organ injury; however, tissue-specific biomarkers are limited in clinical panels. We used proteomic and metabolomic databases to identify organ injury patterns after severe injury in humans. METHODS: Plasma samples (times 0, 24, and 72 hours after arrival to trauma center) from injured patients enrolled in two randomized prehospital trials were subjected to multiplexed proteomics (SomaLogic Inc., Boulder, CO). Patients were categorized by outcome: nonresolvers (died >72 hours or required ≥7 days of critical care), resolvers (survived to 30 days and required <7 days of critical care), and low Injury Severity Score (ISS) controls. Established tissue-specific biomarkers were identified through a literature review and cross-referenced with tissue specificity from the Human Protein Atlas. Untargeted plasma metabolomics (Metabolon Inc., Durham, NC), inflammatory mediators, and endothelial damage markers were correlated with injury biomarkers. Kruskal-Wallis/Mann-Whitney U tests with false discovery rate correction assessed differences in biomarker expression across outcome groups (significance; p < 0.1). RESULTS: Of 142 patients, 78 were nonresolvers (median ISS, 30), 34 were resolvers (median ISS, 22), and 30 were low ISS controls (median ISS, 1). A broad release of tissue-specific damage markers was observed at admission; this was greater in nonresolvers. By 72 hours, nine cardiac, three liver, eight neurologic, and three pulmonary proteins remained significantly elevated in nonresolvers compared with resolvers. Cardiac damage biomarkers showed the greatest elevations at 72 hours in nonresolvers and had significant positive correlations with proinflammatory mediators and endothelial damage markers. Nonresolvers had lower concentrations of fatty acid metabolites compared with resolvers, particularly acyl carnitines and cholines. CONCLUSION: We identified an immediate release of tissue-specific biomarkers with sustained elevation in the liver, pulmonary, neurologic, and especially cardiac injury biomarkers in patients with complex clinical courses after severe injury. The persistent myocardial injury in nonresolvers may be due to a combination of factors including metabolic stress, inflammation, and endotheliopathy.

MACROPHAGE SWITCHING: POLARIZATION AND MOBILIZATION AFTER TRAUMA.

ABSTRACT: Introduction: Trauma alters the immune response in numerous ways, affecting both the innate and adaptive responses. Macrophages play an important role in inflammation and wound healing following injury. We hypothesize that macrophages mobilize from the circulation to the site of injury and secondary sites after trauma, with a transition from proinflammatory (M1) shortly after trauma to anti-inflammatory (M2) at later time points. Methods: C57Bl6 mice (n = 6/group) underwent a polytrauma model using cardiac puncture/hemorrhage, pseudofemoral fracture, and liver crush injury. The animals were killed at several time points: uninjured, 24 h, and 7 days. Peripheral blood mononuclear cells, spleen, liver nonparenchymal cells, and lung were harvested, processed, and stained for flow cytometry. Macrophages were identified as CD68 + ; M1 macrophages were identified as iNOS + ; M2 macrophages as arginase 1 + . Results: We saw a slight presence of M1 macrophages at baseline in peripheral blood mononuclear cells (6.6%), with no significant change at 24 h and 7 days after polytrauma. In contrast, the spleen has a larger population of M1 macrophages at baseline (27.7%), with levels decreasing at 24 h and 7 days after trauma (20.6% and 12.6%, respectively). A similar trend is seen in the lung where at baseline 14.9% of CD68 + macrophages are M1, with subsequent continual decrease reaching 8.7% at 24 h and 4.4% at 7 days after polytrauma. M1 macrophages in the liver represent 14.3% of CD68 + population in the liver nonparenchymal cells at baseline. This percentage increases to 20.8% after trauma and decreases at 7 days after polytrauma (13.4%). There are few M2 macrophages in circulating peripheral blood mononuclear cells and in spleen at baseline and after trauma. The percentage of M2 macrophages in the lungs remains constant after trauma (7.2% at 24 h and 9.2% at 7 days). In contrast, a large proportion of M2 macrophages are seen in the liver at baseline (36.0%). This percentage trends upward and reaches 45.6% acutely after trauma and drops to 21.4% at 7 days. The phenotypic changes in macrophages seen in the lungs did not correlate with a functional change in the ability of the macrophages to perform oxidative burst, with an increase from 2.0% at baseline to 22.1% at 7 days after polytrauma ( P = 0.0258). Conclusion: Macrophage phenotypic changes after polytrauma are noted, especially with a decrease in the lung M1 phenotype and a short-term increase in the M2 phenotype in the liver. However, macrophage function as measured by oxidative burst increased over the time course of trauma, which may signify a change in subset polarization after injury not captured by the typical macrophage phenotypes.

Plasma proteomics reveals early, broad release of chemokine, cytokine, TNF, and interferon mediators following trauma with delayed increases in a subset of chemokines and cytokines in patients that remain critically ill.

Severe injury is known to cause a systemic cytokine storm that is associated with adverse outcomes. However, a comprehensive assessment of the time-dependent changes in circulating levels of a broad spectrum of protein immune mediators and soluble immune mediator receptors in severely injured trauma patients remains uncharacterized. To address this knowledge gap, we defined the temporal and outcome-based patterns of 184 known immune mediators and soluble cytokine receptors in the circulation of severely injured patients. Proteomics (aptamer-based assay, SomaLogic, Inc) was performed on plasma samples drawn at 0, 24, and 72 hours (h) from time of admission from 150 trauma patients, a representative subset from the Prehospital Plasma during Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock (PAMPer) trial. Patients were categorized into outcome groups including Early Non-Survivors (died within 72 h; ENS; n=38), Non-Resolvers (died after 72 h or required ≥7 days of intensive care; NR; n=78), and Resolvers (survivors that required < 7 days of intensive care; R; n=34), with low Injury Severity Score (ISS) patients from the Tranexamic Acid During Prehospital Transport in Patients at Risk for Hemorrhage After Injury (STAAMP) trial as controls. The major findings include an extensive release of immune mediators and cytokine receptors at time 0h that is more pronounced in ENS and NR patients. There was a selective subset of mediators elevated at 24 and 72 h to a greater degree in NR patients, including multiple cytokines and chemokines not previously described in trauma patients. These findings were validated in a quantitative fashion using mesoscale discovery immunoassays (MSD) from an external validation cohort (VC) of samples from 58 trauma patients matched for R and NR status. This comprehensive longitudinal description of immune mediator patterns associated with trauma outcomes provides a new level of characterization of the immune response that follows severe injury.

EFFECT OF IRRIGATION FLUID COMPOSITION ON HEMOSTASIS IN MOUSE BLEEDING MODELS.

ABSTRACT: Introduction: Intraoperative irrigation, usually with normal saline (NS), aids in bleeding identification and management. We investigated the effect of different irrigation fluids, with additives, on hemostasis using two bleeding models. Methods: C57BL/6 J mice were subjected to a tail bleed model or uncontrolled abdominal hemorrhage via liver laceration followed by abdominal cavity irrigation. We compared NS, lactated Ringer's (LR), and PlasmaLyte. We examined NS and LR at different temperatures. Normal saline or LR with calcium (Ca 2+ ) or tranexamic acid (TXA) was studied. Results: Compared with room temperature (RT), increasing the temperature of the irrigation fluid to 37°C and 42°C reduced tail vein bleeding times substantially in both NS and LR (all P < 0.001), with no significant differences between the two fluids. At RT, LR, but not PlasmaLyte, substantially reduced bleeding times in comparison to NS ( P < 0.0001). Liver injury blood loss was lower with LR ( P < 0.01). Normal saline supplemented with 2.7 mEq/L of Ca 2+ decreased bleeding time and blood loss volume ( P < 0.001 and P < 0.01, respectively) to similar levels as LR. Normal saline with 150 mg/mL of TXA markedly reduced bleeding time ( P < 0.0001), and NS with 62.5 mg/mL TXA decreased blood loss ( P < 0.01). Conclusion: Whereas Ca 2+ - and TXA-supplemented NS reduced bleeding, LR remained superior to all irrigation fluid compositions. As LR contains Ca 2+ , and Ca 2+ -supplemented NS mirrored LR in response, Ca 2+ presence in the irrigation fluid seems key to improving solution's hemostatic ability. Because warming the fluids normalized the choice of agents, the data also suggest that Ca 2+ -containing fluids such as LR may be more suitable for hemostasis when used at RT.

Multi-Omic Admission-Based Prognostic Biomarkers Identified by Machine Learning Algorithms Predict Patient Recovery and 30-Day Survival in Trauma Patients.

Admission-based circulating biomarkers for the prediction of outcomes in trauma patients could be useful for clinical decision support. It is unknown which molecular classes of biomolecules can contribute biomarkers to predictive modeling. Here, we analyzed a large multi-omic database of over 8500 markers (proteomics, metabolomics, and lipidomics) to identify prognostic biomarkers in the circulating compartment for adverse outcomes, including mortality and slow recovery, in severely injured trauma patients. Admission plasma samples from patients (n = 129) enrolled in the Prehospital Air Medical Plasma (PAMPer) trial were analyzed using mass spectrometry (metabolomics and lipidomics) and aptamer-based (proteomics) assays. Biomarkers were selected via Least Absolute Shrinkage and Selection Operator (LASSO) regression modeling and machine learning analysis. A combination of five proteins from the proteomic layer was best at discriminating resolvers from non-resolvers from critical illness with an Area Under the Receiver Operating Characteristic curve (AUC) of 0.74, while 26 multi-omic features predicted 30-day survival with an AUC of 0.77. Patients with traumatic brain injury as part of their injury complex had a unique subset of features that predicted 30-day survival. Our findings indicate that multi-omic analyses can identify novel admission-based prognostic biomarkers for outcomes in trauma patients. Unique biomarker discovery also has the potential to provide biologic insights.

High Dimensional Multiomics Reveals Unique Characteristics of Early Plasma Administration in Polytrauma Patients With TBI.

OBJECTIVES: The authors sought to identify causal factors that explain the selective benefit of prehospital administration of thawed plasma (TP) in traumatic brain injury (TBI) patients using mediation analysis of a multiomic database. BACKGROUND: The Prehospital Air Medical Plasma (PAMPer) Trial showed that patients with TBI and a pronounced systemic response to injury [defined as endotype 2 (E2)], have a survival benefit from prehospital administration of TP. An interrogation of high dimensional proteomics, lipidomics and metabolomics previously demonstrated unique patterns in circulating biomarkers in patients receiving prehospital TP, suggesting that a deeper analysis could reveal causal features specific to TBI patients. METHODS: A novel proteomic database (SomaLogic Inc., aptamer-based assay, 7K platform) was generated using admission blood samples from a subset of patients (n=149) from the PAMPer Trial. This proteomic dataset was combined with previously reported metabolomic and lipidomic datasets from these same patients. A 2-step analysis was performed to identify factors that promote survival in E2-TBI patients who had received early TP. First, features were selected using both linear and multivariate-latent-factor regression analyses. Then, the selected features were entered into the causal mediation analysis. RESULTS: Causal mediation analysis of observable features identified 16 proteins and 41 lipids with a high proportion of mediated effect (>50%) to explain the survival benefit of early TP in E2-TBI patients. The multivariate latent-factor regression analyses also uncovered 5 latent clusters of features with a proportion effect >30%, many in common with the observable features. Among the observable and latent features were protease inhibitors known to inhibit activated protein C and block fibrinolysis (SERPINA5 and CPB2), a clotting factor (factor XI), as well as proteins involved in lipid transport and metabolism (APOE3 and sPLA(2)-XIIA). CONCLUSIONS: These findings suggest that severely injured patients with TBI process exogenous plasma differently than those without TBI. The beneficial effects of early TP in E2-TBI patients may be the result of improved blood clotting and the effect of brain protective factors independent of coagulation.

The Use of Multiplexing to Identify Cytokine and Chemokine Networks in the Immune-Inflammatory Response to Trauma.

Significance: The immunoinflammatory responses that follow trauma contribute to clinical trajectory and patient outcomes. While remarkable advances have been made in trauma services and injury management, clarity on how the immune system in humans responds to trauma is lagging. Recent Advances: Multiplexing platforms have transformed our ability to analyze comprehensive immune mediator responses in human trauma. In parallel, with the establishment of large data sets, computational methods have been adapted to yield new insights based on mediator patterns. These efforts have added an important data layer to the emerging multiomic characterization of the human response to injury. Critical Issues: Outcome after trauma is greatly affected by the host immunoinflammatory response. Excessive or sustained responses can contribute to organ damage. Hence, understanding the pathophysiology behind traumatic injury is of vital importance. Future Directions: This review summarizes our work in the study of circulating immune mediators in trauma patients. Our foundational studies into dynamic patterns of inflammatory mediators represent an important contribution to the concepts and computational challenges that these large data sets present. We hope to see further integration and understanding of multiomics strategies in the field of trauma that can aid in patient endotyping and in potentially identifiying certain therapeutic targets in the future. Antioxid. Redox Signal. 35, 1393-1406.

Single-Cell Transcriptomics Reveals Compartment-Specific Differences in Immune Responses and Contributions for Complement Factor 3 in Hemorrhagic Shock Plus Tissue Trauma.

ABSTRACT: Hemorrhagic shock with tissue trauma (HS/T) leads to the activation of a system-wide immune-inflammatory response that involves all organs and body compartments. Recent advances in single-cell analysis permit the simultaneous assessment of transcriptomic patterns in a large number of cells making it feasible to survey the landscape of immune cell responses across numerous anatomic sites. Here, we used single-cell RNA sequencing of leukocytes from the blood, liver, and spleen to identify the major shifts in gene expression by cell type and compartment in a mouse HS/T model. At 6 h, dramatic changes in gene expression were observed across multiple-cell types and in all compartments in wild-type mice. Monocytes from circulation and liver exhibited a significant upregulation of genes associated with chemotaxis and migration and a simultaneous suppression of genes associated with interferon signaling and antigen presentation. In contrast, liver conventional DC exhibited a unique pattern compared with other myeloid cells that included a pronounced increase in major histocompatibility complex class II (MHCII) gene expression. The dominant pattern across all compartments for B and T cells was a suppression of genes associated with cell activation and signaling after HS/T. Using complement factor 3 (C3) knockout mice we unveiled a role for C3 in the suppression of monocyte Major Histocompatibility Complex class II expression and activation of gene expression associated with migration, phagocytosis and cytokine upregulation, and an unexpected role in promoting interferon-signaling in a subset of B and T cells across all three compartments after HS/T. This transcriptomic landscape study of immune cells provides new insights into the host immune response to trauma, as well as a rich resource for further investigation of trauma-induced immune responses and complement in driving interferon signaling.

Impact of postoperative pancreatic fistula on long-term oncologic outcomes after pancreatic resection.

BACKGROUND: The short-term morbidity associated with post-operative pancreatic fistula (POPF) is well established, however data regarding the long-term impact are lacking. We aim to characterize long-term oncologic outcomes of POPF after pancreatic resection through a single institution, retrospective study of pancreatic resections performed for adenocarcinoma from 2009 to 2016. METHODS: Kaplan-Meier survival analysis, logistic regression, and multivariate analysis (MVA) were used to evaluate impact of POPF on overall survival (OS), disease free survival (DFS), and receipt of adjuvant chemotherapy (AC). RESULTS: 767 patients were included. 82 (10.6%) developed grade B (n = 67) or C (n = 15) POPF. Grade C POPF resulted in decreased OS when compared to no POPF (20.22 vs 26.33 months, p = 0.027) and to grade B POPF (20.22 vs. 26.87 months, p = 0.049). POPF patients were less likely to receive AC than those without POPF (59.5% vs 74.9%, p = 0.003) and grade C POPF were less likely to receive AC than all others (26.7% vs 74.2%, p = 0.0001). CONCLUSION: POPF patients are less likely to receive AC and more likely to have delay in time to AC. These factors are exacerbated in grade C POPF and likely contribute to decreased OS. These findings validate the clinical significance of the ISGPF definition of POPF.

Is the Use of Intraoperative Frozen Section During Pancreaticoduodenectomy Justified?

BACKGROUND: Intraoperative frozen section (IFS) is routinely utilized by many surgeons during pancreaticoduodenectomy. However, its utility has not been rigorously studied. METHODS: Patients who underwent pancreaticoduodenectomy between 2006 and 2015 were identified from institutional data. Measures of diagnostic accuracy of frozen section and multivariate logistic regression are reported. RESULTS: The cohort included 1076 patients. Of resected specimens, 73.3% were malignant. IFS and final pathologic review (the gold standard) were discrepant for (1) pathologic diagnosis or (2) resection margin status in 5.3% and 3.3% of cases. The sensitivity, specificity, and accuracy of IFS for histologic determination of malignancy were 97.2%, 95.3%, and 96.7% respectively. For resection margins, they were 92.3%, 99.3%, and 96.8%, respectively. Positive bile duct and neck margins were revised intraoperatively 62% and 65% of the time, respectively; positive uncinate margins were never resected but led surgeons to avoid revision of a second positive margin in 13% of cases (4.2% of all PDA). Operative changes were rarely noted in the presence of benign disease (n = 11, 1.0%); conversion to total pancreatectomy based on positive margins was performed in just 13 cases (1.2%). Upon multivariable analysis, a positive neck margin proved to be the greatest predictor for a revised resection margin (AOR 16.9 [4.8-59.8]), whereas a positive uncinate margin or a diagnosis of chronic pancreatitis was protective against IFS-driven operative changes (AOR 0.25 [0.09-0.73]; AOR 0.16 [0.13-0.19]). CONCLUSIONS: IFS is highly accurate and guides reresection of margins. However, selective omission of IFS may be justified for cases where benign disease is suspected.

Intraoperative Frozen Section Analysis of the Pancreas: A Case Report and Review of the Literature.

Background: Intraoperative frozen section analysis is frequently used to obtain a histological diagnosis at the time of resection and to assess resection margins. Although many surgeons perceive a clinical benefit, particularly with respect to the transected resection margins, the limitations and pitfalls of frozen section analysis have not been well documented. Case: Here, we report a case of serous cystadenoma with background pancreatitis masquerading on frozen section as an invasive pancreatic ductal adenocarcinoma. This interpretation was a surprise in light of preoperative imaging that was highly suggestive of a benign cystic tumor, but nevertheless prompted intraoperative consideration of a more radical operation to ensure a complete resection was achieved. Conclusions: Frozen section analysis is an imperfect test, and misdiagnoses can potentially impact patient outcomes adversely. Intraoperative decisions must carefully integrate the preliminary pathological interpretation with the overall clinical context. Further studies are warranted to more fully characterize the accuracy, utility, and cost-effectiveness of intraoperative frozen section analysis for pancreatic surgery.

Intracellular Hmgb1 inhibits inflammatory nucleosome release and limits acute pancreatitis in mice.

BACKGROUND & AIMS: High mobility group box 1 (HMGB1) is an abundant protein that regulates chromosome architecture and also functions as a damage-associated molecular pattern molecule. Little is known about its intracellular roles in response to tissue injury or during subsequent local and systemic inflammatory responses. We investigated the function of Hmgb1 in mice after induction of acute pancreatitis. METHODS: We utilized a Cre/LoxP system to create mice with pancreas-specific disruption in Hmbg1 (Pdx1-Cre; HMGB1(flox/flox) mice). Acute pancreatitis was induced in these mice (HMGB1(flox/flox) mice served as controls) after injection of l-arginine or cerulein. Pancreatic tissues and acinar cells were collected and analyzed by histologic, immunoblot, and immunohistochemical analyses. RESULTS: After injection of l-arginine or cerulein, Pdx1-Cre; HMGB1(flox/flox) mice developed acute pancreatitis more rapidly than controls, with increased mortality. Pancreatic tissues of these mice also had higher levels of serum amylase, acinar cell death, leukocyte infiltration, and interstitial edema than controls. Pancreatic tissues and acinar cells collected from the Pdx1-Cre; HMGB1(flox/flox) mice after l-arginine or cerulein injection demonstrated nuclear catastrophe with greater nucleosome release when compared with controls, along with increased phosphorylation/activation of RELA nuclear factor κB, degradation of inhibitor of κB, and phosphorylation of mitogen-activated protein kinase. Inhibitors of reactive oxygen species (N-acetyl-l-cysteine) blocked l-arginine-induced DNA damage, necrosis, apoptosis, release of nucleosomes, and activation of nuclear factor κB in pancreatic tissues and acinar cells from Pdx1-Cre; HMGB1(flox/flox) and control mice. Exogenous genomic DNA and recombinant histone H3 proteins significantly induced release of HMGB1 from mouse macrophages; administration of antibodies against H3 to mice reduced serum levels of HMGB1 and increased survival after l-arginine injection. CONCLUSIONS: In 2 mouse models of acute pancreatitis, intracellular HMGB1 appeared to prevent nuclear catastrophe and release of inflammatory nucleosomes to block inflammation. These findings indicate a role for the innate immune response in tissue damage.

Sweating the small stuff: microRNAs and genetic changes define pancreatic cancer.

MicroRNAs (miRNAs) are 18- to 22-nucleotide-long, single-stranded, noncoding RNAs that regulate important biological processes including differentiation, proliferation, and response to cellular stressors such as hypoxia, nutrient depletion, and traversion of the cell cycle by controlling protein expression within the cell. Many investigators have profiled cancer tissue and serum miRNAs to identify potential therapeutic targets, understand the pathways involved in tumorigenesis, and identify diagnostic tumor signatures. In the setting of pancreatic cancer, obtaining pancreatic tissue is invasive and impractical for early diagnosis. Several groups have profiled miRNAs that are present in the blood as a means to diagnose tumor progression and predict prognosis/survival or drug resistance. Several miRNA signatures found in pancreatic tissue and the peripheral blood, as well as the pathways that are associated with pancreatic cancer, are reviewed here in detail. Three miRNA biomarkers (miR-21, miR-155, and miR-200) have been repetitively identified in both pancreatic cancer tissue and patients' blood. Those miRNAs regulate and are regulated by the central genetic and epigenetic changes observed in pancreatic cancer including p53, transforming growth factor ß, p16(INK4A), BRCA1/2, and Kras. These miRNAs are involved in DNA repair, cell cycle, and cell invasion and also play important roles in promoting metastases.