Persistent inflammation, immunosuppression, and catabolism syndrome after severe blunt trauma

Parenteral or Enteral Arginine Supplementation Safety and Efficacy

Arginine supplementation has the potential to improve the health of patients. Its use in hospitalized patients has been a controversial topic in the nutrition literature, especially concerning supplementation of septic patients. In this article, we review the relevant literature both for and against the use of arginine in critically ill, surgical, and hospitalized patients. The effect of critical illness on arginine metabolism is reviewed, as is its use in septic and critically ill patients. Although mounting evidence supports immunonutrition, there are only a few studies that suggest that this is safe in patients with severe sepsis. The use of arginine has been shown to benefit a variety of critically ill patients. It should be considered for inclusion in combinations of immunonutrients or commercial formulations for groups in whom its benefit has been reported consistently, such as those who have suffered trauma and those in acute surgical settings. The aims of this review are to discuss the role of arginine in health, the controversy surrounding arginine supplementation of septic patients, and the use of arginine in critically ill patients.

Preoperative assessment of the risk for multiple complications after surgery

BACKGROUND

The association between preoperative patient characteristics and the number of major postoperative complications after a major operation is not well defined.

METHODS

In a retrospective, single-center cohort of 50,314 adult surgical patients, we used readily available preoperative clinical data to model the number of major postoperative complications from none to ≥3. We included acute kidney injury; prolonged stay (>48 hours) in an intensive care unit; need for prolonged (>48 hours) mechanical ventilation; severe sepsis; and cardiovascular, wound, and neurologic complications. Risk probability scores generated from the multinomial logistic models were used to develop an online calculator. We stratified patients based on their risk of having ≥3 postoperative complications.

RESULTS

Patients older than 65 years (odds ratio 1.5, 95% confidence interval, 1.4-1.6), males (odds ratio 1.2, 95% confidence interval, 1.2-1.3), patients with a greater Charlson comorbidity index (odds ratio 3.9, 95% confidence interval, 3.6-4.2), patients requiring emergency operation (odds ratio 3.5, 95% confidence interval, 3.3.-3.7), and patients admitted on a weekend (odds ratio 1.4, 95% confidence interval, 1.3-1.5) were more likely to have ≥3 postoperative complications than they were to have none. Patients in the medium- and high-risk categories were 3.7 and 6.3 times more likely to have ≥3 postoperative complications, respectively. High-risk patients were 5.8 and 4.4 times more likely to die within 30 and 90 days of admission, respectively.

CONCLUSION

Readily available, preoperative clinical and sociodemographic factors are associated with a greater number of postoperative complications and adverse surgical outcomes. We developed an online calculator that predicts probability of developing each number of complications after a major operation.

Sepsis and septic shock

For more than two decades, sepsis was defined as a microbial infection that produces fever (or hypothermia), tachycardia, tachypnoea and blood leukocyte changes. Sepsis is now increasingly being considered a dysregulated systemic inflammatory and immune response to microbial invasion that produces organ injury for which mortality rates are declining to 15-25%. Septic shock remains defined as sepsis with hyperlactataemia and concurrent hypotension requiring vasopressor therapy, with in-hospital mortality rates approaching 30-50%. With earlier recognition and more compliance to best practices, sepsis has become less of an immediate life-threatening disorder and more of a long-term chronic critical illness, often associated with prolonged inflammation, immune suppression, organ injury and lean tissue wasting. Furthermore, patients who survive sepsis have continuing risk of mortality after discharge, as well as long-term cognitive and functional deficits. Earlier recognition and improved implementation of best practices have reduced in-hospital mortality, but results from the use of immunomodulatory agents to date have been disappointing. Similarly, no biomarker can definitely diagnose sepsis or predict its clinical outcome. Because of its complexity, improvements in sepsis outcomes are likely to continue to be slow and incremental.

Risk Stratification and Prognosis in Sepsis: What Have We Learned from Microarrays?

Sepsis mortality rates have decreased in recent years but remain unacceptably high. Risk stratification and prognostication is of particular importance because high-risk patients may benefit from earlier clinical interventions, whereas low-risk patients may benefit from not undergoing unnecessary procedures. Prognostication is currently done mostly via clinical criteria and blood lactate levels. This article summarizes the literature on the complexity of changes at the molecular level for the casual reader.

A comprehensive time-course-based multicohort analysis of sepsis and sterile inflammation reveals a robust diagnostic gene set

Although several dozen studies of gene expression in sepsis have been published, distinguishing sepsis from a sterile systemic inflammatory response syndrome (SIRS) is still largely up to clinical suspicion. We hypothesized that a multicohort analysis of the publicly available sepsis gene expression data sets would yield a robust set of genes for distinguishing patients with sepsis from patients with sterile inflammation. A comprehensive search for gene expression data sets in sepsis identified 27 data sets matching our inclusion criteria. Five data sets (n = 663 samples) compared patients with sterile inflammation (SIRS/trauma) to time-matched patients with infections. We applied our multicohort analysis framework that uses both effect sizes and P values in a leave-one-data set-out fashion to these data sets. We identified 11 genes that were differentially expressed (false discovery rate ≤1%, inter-data set heterogeneity P > 0.01, summary effect size >1.5-fold) across all discovery cohorts with excellent diagnostic power [mean area under the receiver operating characteristic curve (AUC), 0.87; range, 0.7 to 0.98]. We then validated these 11 genes in 15 independent cohorts comparing (i) time-matched infected versus noninfected trauma patients (4 cohorts), (ii) ICU/trauma patients with infections over the clinical time course (3 cohorts), and (iii) healthy subjects versus sepsis patients (8 cohorts). In the discovery Glue Grant cohort, SIRS plus the 11-gene set improved prediction of infection (compared to SIRS alone) with a continuous net reclassification index of 0.90. Overall, multicohort analysis of time-matched cohorts yielded 11 genes that robustly distinguish sterile inflammation from infectious inflammation.

The future of murine sepsis and trauma research models

Recent comparisons of the murine and human transcriptome in health and disease have called into question the appropriateness of the use of murine models for human sepsis and trauma research. More specifically, researchers have debated the suitability of mouse models of severe inflammation that is intended for eventual translation to human patients. This mini-review outlines this recent research, as well as specifically defines the arguments for and against murine models of sepsis and trauma research based on these transcriptional studies. In addition, we review newer advancements in murine models of infection and injury and define what we envision as an evolving but viable future for murine studies of sepsis and trauma.

A Review of GM-CSF Therapy in Sepsis

Determine what clinical role, if any, GM-CSF may have in the clinical treatment of sepsis in the adult patient. Advancements in the management of sepsis have led to significant decreases in early mortality; however, sepsis remains a significant source of long-term mortality and disability which places strain on healthcare resources with a substantial growing economic impact. Historically, early multiple organ failure (MOF) and death in patients with severe sepsis was thought to result from an exaggerated proinflammatory response called the systemic inflammatory response syndrome (SIRS). Numerous prospective randomized controlled trials (PRCTs) tested therapies aimed at decreasing the organ injury associated with an exaggerated inflammatory response. With few exceptions, the results from these PRCTs have been disappointing, and currently no specific therapeutic agent is approved to counteract the early SIRS response in patients with severe sepsis. It has long been recognized that there is a delayed immunosuppressive state that contributes to long-term morbidity. However, recent findings now support a concurrent proinflammatory and anti-inflammatory response present throughout sepsis. Multiple immunomodulating agents have been studied to combat the immunosuppressive phase of sepsis with the goal of decreasing secondary infection, reducing organ dysfunction, decreasing ICU stays, and improving survival. Granulocyte-macrophage colony stimulating factor (GM-CSF), a myelopoietic growth factor currently used in patients with neutropenia secondary to chemotherapy-induced myelosuppression, has been studied as a potential immune-activating agent. The applicability of GM-CSF as a standard therapy for generalized sepsis is still largely understudied; however, small-scale studies available have demonstrated some improved recovery from infection, decreased hospital length of stay, decreased days requiring mechanical ventilation, and decreased medical costs.

Impact and Progression of Organ Dysfunction in Patients with Necrotizing Soft Tissue Infections: A Multicenter Study

BACKGROUND

Necrotizing soft tissue infections (NSTI) represent a rare but devastating disease for which the systemic manifestations have been poorly characterized. In an effort to define an optimal endpoint for clinical trials in this condition, the objective of this study was to establish the pattern of organ dysfunction over time and determine the correlation between organ dysfunction and clinical outcome in patients with NSTI.

METHODS

We conducted a multicenter, retrospective clinical study of patients with NSTI presenting to 12 academic medical centers in the U.S. during 2013. Patients with a diagnosis of NSTI confirmed by surgical findings were included. Organ dysfunction was assessed using a modified Sequential Organ Failure Assessment (SOFA) score (mSOFA: excluding liver) on admission and on hospital days 1, 2, 3, 7, 10, and 14. The presence of organ dysfunction on admission and resolution of organ dysfunction were correlated with clinical parameters, including intensive care unit (ICU)-free days (of 28 d), ventilator-free days, number of debridements, and mortality rate. The incidence of acute kidney injury (AKI) and recovery also were assessed.

RESULTS

There were 198 patients enrolled, of whom 62% were male, the mean age was 51 years, and 40% had monomicrobial infections. The mean mSOFA score on admission was 2.4 ± 3.0, with 49% of the patients having a score ≥2 and 35% a score of ≥3. Patients typically demonstrated worsening of the mSOFA score over the first 24 h followed by gradual resolution. An mSOFA ≥3 at admission was associated with a significant decrease in ventilator-free days (mean 20.1 vs. 25.6 days; p < 0.001); ICU-free days (15.2 vs. 23.1, p < 0.001); more debridements (mean 2.3 vs. 2.0; p = 0.11); a higher mortality rate (15.9% vs. 3.1%; p = 0.003); and a higher rate of AKI (59.4 vs. 35.9%; p < 0.001). The persistence of organ dysfunction (mSOFA >1) among survivors at day 14 was associated with fewer ICU-free days (17.8 vs. 23.6; p < 0.001) and ventilator-free days (23.6 vs. 27; p = 0.001) and a lower recovery rate from AKI (38.7% vs. 81.3%; p < 0.001).

CONCLUSION

Early development of systemic organ dysfunction in patients with NSTI is associated with higher morbidity and mortality rates. Failure of the resolution of organ dysfunction by day 14 forecasts a poor outcome. The mSOFA score may be a useful marker for patient selection for inclusion in interventional trials, and the resolution of organ dysfunction by day 14 may be an important clinical endpoint.

A Detailed Characterization of the Dysfunctional Immunity and Abnormal Myelopoiesis Induced by Severe Shock and Trauma in the Aged

The elderly are particularly susceptible to trauma, and their outcomes are frequently dismal. Such patients often have complicated clinical courses and ultimately die of infection and sepsis. Recent research has revealed that although elderly subjects have increased baseline inflammation as compared with their younger counterparts, the elderly do not respond to severe infection or injury with an exaggerated inflammatory response. Initial retrospective analysis of clinical data from the Glue Grant trauma database demonstrated that despite a similar frequency, elderly trauma patients have worse outcomes to pneumonia than younger subjects do. Subsequent analysis with a murine trauma model also demonstrated that elderly mice had increased mortality after posttrauma Pseudomonas pneumonia. Blood, bone marrow, and bronchoalveolar lavage sample analyses from juvenile and 20-24-mo-old mice showed that increased mortality to trauma combined with secondary infection in the aged are not due to an exaggerated inflammatory response. Rather, they are due to a failure of bone marrow progenitors, blood neutrophils, and bronchoalveolar lavage cells to initiate and complete an emergency myelopoietic response, engendering myeloid cells that fail to clear secondary infection. In addition, elderly people appeared unable to resolve their inflammatory response to severe injury effectively.

Systemic inflammation in xenograft recipients (SIXR): A new paradigm in pig-to-primate xenotransplantation?

Inflammation is a complex response that involves interactions between multiple proteins in the human body. The interaction between inflammation and coagulation is well-recognized, but its role in the dysregulation of coagulation in xenograft recipients is not well-understood. Additionally, inflammation is known to prevent the development of T cell tolerance after transplantation. Recent evidence indicates that systemic inflammation precedes and may be promoting activation of coagulation after pig-to-primate xenotransplantation. Activated recipient innate immune cells expressing tissue factor are increased after xenotransplantation, irrespective of immunosuppressive therapy. With immunosuppression, C-reactive protein (C-RP), fibrinogen, and interleukin-6 levels are significantly increased in pig artery patch recipients. In pig organ recipients, increased C-RP levels are observed prior to the development of features of consumptive coagulopathy. Systemic inflammation in xenograft recipients (Sixr) may be a key factor in the development of dysregulation of coagulation, as well as in resistance to immunosuppressive therapy. While genetic modification of the donor pigs provides protection against humoral responses and the development of thrombotic microangiopathy, therapeutic prevention of Sixr may be essential in order to prevent systemic dysregulation of coagulation in xenograft recipients without the use of intensive immunosuppression.

Persistent inflammatory, immunosuppressed, catabolic syndrome (PICS): A new phenotype of multiple organ failure

A new phenotype of multiple organ failure has appeared: Persistent Inflammatory, Immunosuppressed, Catabolic Syndrome (PICS). Comorbidities and age >65 years have been established as the leading risk factors for PICS. As the percentage of elderly people continues to increase the prevalence of PICS in our ICUs will surely grow. Malnutrition (despite appropriate supplementation), recurrent nosocomial infections, frailty, ventilator dependence, and an indolent death depicts the central theme that plagues PICS patients. Aligned with the recently awarded P50 grant by NIGMS entitled, "PICS: A New Horizon for Surgical Critical Care", and the University Of Florida's Sepsis and Critical Illness Research Center will investigate the genetic make-up of PICS patients, better understand frailty and the implication in trauma patients, and hopefully elucidate new therapies. Currently, there are no therapies to combat PICS aside from nutritional inference elaborated after reviewing the literature on Burns, Cachexia, and Sarcopenia.

Advanced age is associated with worsened outcomes and a unique genomic response in severely injured patients with hemorrhagic shock

INTRODUCTION

We wished to characterize the relationship of advanced age to clinical outcomes and to transcriptomic responses after severe blunt traumatic injury with hemorrhagic shock.

METHODS

We performed epidemiological, cytokine, and transcriptomic analyses on a prospective, multi-center cohort of 1,928 severely injured patients.

RESULTS

We found that there was no difference in injury severity between the aged (age ≥55, n = 533) and young (age <55, n = 1395) cohorts. However, aged patients had more comorbidities. Advanced age was associated with more severe organ failure, infectious complications, ventilator days, and intensive care unit length of stay, as well as, an increased likelihood of being discharged to skilled nursing or long-term care facilities. Additionally, advanced age was an independent predictor of a complicated recovery and 28-day mortality. Acutely after trauma, blood neutrophil genome-wide expression analysis revealed an attenuated transcriptomic response as compared to the young; this attenuated response was supported by the patients' plasma cytokine and chemokine concentrations. Later, these patients demonstrated gene expression changes consistent with simultaneous, persistent pro-inflammatory and immunosuppressive states.

CONCLUSIONS

We concluded that advanced age is one of the strongest non-injury related risk factors for poor outcomes after severe trauma with hemorrhagic shock and is associated with an altered and unique peripheral leukocyte genomic response. As the general population's age increases, it will be important to individualize prediction models and therapeutic targets to this high risk cohort.

Anti-HMGB1 monoclonal antibody ameliorates immunosuppression after peripheral tissue trauma: attenuated T-lymphocyte response and increased splenic CD11b (+) Gr-1 (+) myeloid-derived suppressor cells require HMGB1

Although tissue-derived high mobility group box 1 (HMGB1) is involved in many aspects of inflammation and tissue injury after trauma, its role in trauma-induced immune suppression remains elusive. Using an established mouse model of peripheral tissue trauma, which includes soft tissue and fracture components, we report here that treatment with anti-HMGB1 monoclonal antibody ameliorated the trauma-induced attenuated T-cell responses and accumulation of CD11b⁺Gr-1⁺ myeloid-derived suppressor cells in the spleens seen two days after injury. Our data suggest that HMGB1 released after tissue trauma contributes to signaling pathways that lead to attenuation of T-lymphocyte responses and enhancement of myeloid-derived suppressor cell expansion.

Persistent neutrophil dysfunction and suppression of acute lung injury in mice following cecal ligation and puncture sepsis

Sepsis, both in humans and in rodents, is associated with persistent immunosuppression accompanied by defects in innate immunity during the acute phase of sepsis. Mice were rendered septic by cecal ligation and puncture (CLP) followed by the induction of acute lung injury, employing distal airway deposition of IgG immune complexes, in order to quantitatively evaluate innate immune responses following the induction of sepsis. Suppression of innate immune responses in the lung occurred as early as 12 h after CLP and up to 21 days thereafter. The mechanism of innate immune defects included a reduced leak of albumin into the lungs together with reduced levels of tumor necrosis factor in bronchoalveolar lavage fluids and increased levels of interleukin-10 that were persistent. Bone marrow-derived neutrophils (polymorphonuclear neutrophils; PMNs) from CLP mice also had reduced levels of the activation marker CD11b and a depressed respiratory burst following stimulation in vitro. These results were not observed in mice with endotoxemia, where the innate inflammatory response was preserved. However, sustained lymphopenia was present in both models, suggesting differential regulation of innate and adaptive immunity in the two sepsis models. These data indicate that CLP induced a prolonged suppression of inflammatory responses both in the lung and systemically, as defined by bone marrow-derived PMN dysfunction.