Risk and the efficacy of antiinflammatory agents: retrospective and confirmatory studies of sepsis

Microglial activation and neuroinflammation in acute and chronic cognitive deficits in sepsis

Sepsis is characterised by dysregulated immune responses to infection, leading to multi-organ dysfunction and high rates of mortality. With increasing survival rates in recent years long-term neurological and psychiatric consequences have become more apparent in survivors. Many patients develop sepsis associated encephalopathy (SAE) which encompasses the profound but usually transient neuropsychiatric syndrome delirium but also new brain injury that emerges in the months and years post-sepsis. It is now clear that systemic inflammatory signals reach the brain during sepsis and that very significant neuroinflammation ensues. The major brain resident immune cell population, the microglia, has been implicated in acute and chronic cognitive dysfunction in animal models of sepsis based on a growing number of studies using bacterial endotoxin and in polymicrobial sepsis models such as cecal ligation and puncture. The current review explores the effects of sepsis on the brain, focussing on how systemic insults translate to microglial activation and neuroinflammation and how this disrupts neuronal function and integrity. We examine what has been demonstrated specifically with respect to microglial activation, revealing robust evidence for a role for neuroinflammation in sepsis-induced brain sequelae but less clear information on the extent of the specific microglial contribution to this, arising from findings using global knockout mice, non-selective drugs and treatments that equally target peripheral and central compartments. There is, nonetheless, clear evidence that microglia do become activated and do contribute to brain consequences of sepsis thus arguing for improved understanding of these neuroinflammatory processes toward the prevention and treatment of sepsis-induced brain dysfunction.

Inflammatory Response and Anti-Inflammatory Treatment in Persistent Inflammation-Immunosuppression-Catabolism Syndrome (PICS)

Many patients now survive their initial critical events but subsequently develop chronic critical illness (CCI). CCI is characterized by prolonged hospital stays, poor outcomes, and significant long-term mortality. The incidence of chronic critical illness (CCI) is estimated to be 34.4 cases per 100,000 population. The incidence varies significantly with age, peaking at 82.1 cases per 100,000 in individuals aged 75-79. The one-year mortality rate among CCI patients approaches 50%. A subset of these patients enters a state of persistent inflammation, immune suppression, and ongoing catabolism, a condition termed persistent inflammation, immunosuppression, and catabolism syndrome (PICS) in 2012. In recent years, some progress has been made in treating PICS. For instance, recent advancements such as the persistent expansion of MDSCs (myeloid-derived suppressor cells) and the mechanisms underlying intestinal barrier dysfunction have provided new directions for therapeutic strategies, as discussed below. Persistent inflammation, a key feature of PICS, has received comparatively little research attention. In this review, we examine the potential pathophysiological changes and molecular mechanisms underlying persistent inflammation and its role in PICS. We also discuss current therapies about inflammation and offer recommendations for managing patients with PICS.

Shadows and lights in sepsis immunotherapy

INTRODUCTION

Sepsis remains a major global public health challenge. The host's response in sepsis involves both an exaggerated inflammatory reaction and immunosuppressive mechanisms. A better understanding of this response has shed light on the failure of anti-inflammatory therapies administered under the 'one size fits all' approach during the last decades.

AREAS COVERED

To date, patients' management has moved toward a comprehensive precision medicine approach that aims to personalize immunotherapy, whether anti-inflammatory or immunostimulatory. Large Prospective interventional randomized controlled trials validating this approach are about to start. A crucial prerequisite for these studies is to stratify patients based on biomarkers that will help defining the patients' immuno-inflammatory trajectory.

EXPERT OPINION

Some biomarkers are already available in routine clinical care, while improvements are anticipated through the standardized use of transcriptomics and other multi-omics technologies in this field. With these precautions in mind, it is reasonable to anticipate improvement in outcomes in sepsis.

The effect of polyclonal and monoclonal based antibodies as promising potential therapy for treatment of sepsis: A systematic review

While mortality caused by sepsis remains an unsolved problem, studies showed conflicting results about effectiveness of monoclonal and polyclonal antibodies in patients suffering sepsis. For this reason, this current study provides an update of review clinical randomized trial studies until March 2024. The main object of this study is to determine effects of monoclonal and polyclonal antibodies on mortality rate and hospitalization of patients suffering sepsis. Search of Scopus, Web of science, EMBASE, PubMed and Cochrane were performed and randomized controlled trials which conducted in patients with septic shock or bacterial sepsis were included. Two reviewers assessed all searched trials for eligibility according to already defined criteria and did data collection and analyses afterwards. Present study showed monoclonal and polyclonal antibodies are a safe strategy with mild-to-moderate adverse effects. However, most studies indicate no significant change among inter-and intra-group comparison (p > 0.05) and further studies are needed, results showed an increase in survival rate, ventilator-and ICU-free days, resolve organ dysfunction, mediating inflammation related cytokines.

Inhibition of cIAP1/2 reduces RIPK1 phosphorylation in pulmonary endothelial cells and alleviate sepsis-induced lung injury and inflammatory response

Acute respiratory distress syndrome (ARDS)/acute lung injury (ALI) is a severe complication of sepsis characterized by acute respiratory distress, hypoxemia, and diffuse bilateral pulmonary infiltrates. The regulation of RIPK1 is an important part of the inflammatory response, and cIAP1/2 serves as the E3 ubiquitin ligase for RIPK1. In this study, we investigated the effect and mechanism of cIAP1/2 inhibition on sepsis-induced lung injury. Our results showed that cIAP1/2 inhibition can alleviate sepsis-induced lung injury and reduce the inflammatory response, which is accompanied by downregulation of RIPK1 phosphorylation and ubiquitination. Additionally, cIAP1/2 inhibition led to the up-regulation of programmed cell death, including apoptosis, necroptosis, and pyroptosis, and inhibiting these three cell death pathways can further reduce the inflammatory response, which is similar to the recently discovered programmed cell death pathway PANoptosis. Our findings suggest that cIAP1/2 and PANoptosis inhibition may be a new strategy for treating sepsis-induced lung injury and provide important references for further exploring the mechanism of sepsis-induced lung injury and identifying new therapeutic targets.

EMERGENCE OF A TECHNOLOGY-DEPENDENT PHENOTYPE OF PEDIATRIC SEPSIS IN A LARGE CHILDREN'S HOSPITAL

ABSTRACT

Objective: To investigate whether pediatric sepsis phenotypes are stable in time. Methods: Retrospective cohort study examining children with suspected sepsis admitted to a Pediatric Intensive Care Unit at a large freestanding children's hospital during two distinct periods: 2010-2014 (early cohort) and 2018-2020 (late cohort). K-means consensus clustering was used to derive types separately in the cohorts. Variables included ensured representation of all organ systems. Results: One thousand ninety-one subjects were in the early cohort and 737 subjects in the late cohort. Clustering analysis yielded four phenotypes in the early cohort and five in the late cohort. Four types were in both: type A (34% of early cohort, 25% of late cohort), mild sepsis, with minimal organ dysfunction and low mortality; type B (25%, 22%), primary respiratory failure; type C (25%, 18%), liver dysfunction, coagulopathy, and higher measures of systemic inflammation; type D (16%, 17%), severe multiorgan dysfunction, with high degrees of cardiorespiratory support, renal dysfunction, and highest mortality. Type E was only detected in the late cohort (19%) and was notable for respiratory failure less severe than B or D, mild hypothermia, and high proportion of diagnoses and technological dependence associated with medical complexity. Despite low mortality, this type had the longest PICU length of stay. Conclusions: This single center study identified four pediatric sepsis phenotypes in an earlier epoch but five in a later epoch, with the new type having a large proportion of characteristics associated with medical complexity, particularly technology dependence. Personalized sepsis therapies need to account for this expanding patient population.

The Unexpected Protective Role of Thrombosis in Sepsis-Induced Inflammatory Lung Injury Via Endothelial Alox15

BACKGROUND

Patients with sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) commonly suffer from severe pulmonary thrombosis, but clinical trials of anti-coagulant therapies in sepsis and ARDS patients have failed. ARDS patients with thrombocytopenia also exhibit increased mortality, and widespread pulmonary thrombosis is often seen in coronavirus disease 2019 (COVID-19) ARDS patients.

METHODS

Employing different amounts of microbeads to induce various levels of pulmonary thrombosis. Acute lung injury was induced by either lipopolysaccharide i.p. or cecal ligation and puncture. Endothelial cell (EC)-targeted nanoparticle coupled with CDH5 promoter was employed to delivery plasmid DNA expressing the CRISPR/Cas9 system for EC-specific gene knockout or expressing Alox15 for EC-specific overexpression. Additionally, thrombocytopenia was induced by genetic depletion of platelets using DTR ^Pf4Cre mice by breeding Pf4 Cre mice into the genetic background of DTR mice.

RESULTS

We show that while severe pulmonary thrombosis or thrombocytopenia augments sepsis-induced ALI, the induction of mild pulmonary thrombosis conversely reduces endothelial cell (EC) apoptosis, ALI, and mortality via sustained expression of endothelial arachidonate 15-lipoxygenase (Alox15). Endothelial Alox15 knockout via EC-targeted nanoparticle delivery of CRISPR/Cas9 plasmid DNA in adult mice abolished the protective impact of mild lung thrombosis. Conversely, overexpression of endothelial Alox15 inhibited the increases in ALI caused by severe pulmonary thrombosis. The clinical relevance of the findings was validated by the observation of reduced ALOX15-expressing ECs in lung autopsy samples of ARDS patients. Additionally, restoration of pulmonary thrombosis in thrombocytopenic mice also normalized endotoxemia-induced ALI.

CONCLUSION

We have demonstrated that moderate levels of thrombosis protect against sepsis-induced inflammatory lung injury via endothelial Alox15. Overexpression of Alox5 inhibits severe pulmonary thrombosis-induced increase of ALI. Thus, activation of ALOX15 signaling represents a promising therapeutic strategy for treatment of ARDS, especially in sub-populations of patients with thrombocytopenia and/or severe pulmonary thrombosis.

Ablation of myeloid discoidin domain receptor 2 exacerbates arthritis and high fat diet induced inflammation

Chronic systemic inflammation leads to sever disorders and diseases. It is of great importance to explore novel target for effective treatment. Discoidin domain receptor 2 (Ddr2) is a member of receptor tyrosine kinase (RTK) family and is implicated in skeletal and fat hemostasis. However, the role of Ddr2 in myeloid cells remains obscure. In this study, we conditionally deleted Ddr2 in myeloid lineage cells to generate cKO mice to investigate the role of Ddr2 in myeloid lineage cells. We found that cKO mice exhibited more severe inflammation both in collagen antibody-induced arthritis (CAIA) and high-fat diet (HFD)-induced obesity, indicating the protective role of Ddr2 against inflammation. Mechanistically, Ddr2 promotes macrophage repolarization from the M1 to M2 phenotype, and protect against systemic inflammation. Our study reveals for the first time that Ddr2 modulates macrophage repolarization and plays critical roles in macrophage-mediated inflammation, providing potential target for the intervention of inflammation and related diseases.

CIITA promoter polymorphism impairs monocytes HLA-DR expression in patients with septic shock

Low monocyte (m)HLA-DR expression is associated with mortality in sepsis. G-286A∗rs3087456 polymorphism in promoter III of HLA class II transactivator (CIITA), the master regulator of HLA, has been associated with autoimmune diseases but its role in sepsis has never been demonstrated. In 203 patients in septic shock, GG genotype was associated with 28-day mortality and mHLA-DR remained low whereas it increased in patients with AA or AG genotype. In ex vivo cells, mHLA-DR failed to augment in GG in comparison with AG or AA genotype on exposure to IFN-γ. Promoter III transcript levels were similar in control monocytes regardless of genotype and exposure to IFN-γ. Promoter III activity was decreased in GG genotype in monocyte cell line but restored after stimulation with IFN-γ. Hereby, we demonstrated that G-286A∗rs3087456 significantly impact mHLA-DR expression in patients with septic shock in part through CIITA promoter III activity, that can be rescued using IFN-γ.

Machine learning and murine models explain failures of clinical sepsis trials

BACKGROUND

Multiple clinical trials failed to demonstrate the efficacy of hydrocortisone, ascorbic acid, and thiamine (HAT) in sepsis. These trials were dominated by patients with pulmonary sepsis and have not accounted for differences in the inflammatory responses across varying etiologies of injury/illness. Hydrocortisone, ascorbic acid, and thiamine have previously revealed tremendous benefits in animal peritonitis sepsis models (cecal ligation and puncture [CLP]) in contradiction to the various clinical trials. The impact of HAT remains unclear in pulmonary sepsis. Our objective was to investigate the impact of HAT in pneumonia, consistent with the predominate etiology in the discordant clinical trials. We hypothesized that, in a pulmonary sepsis model, HAT would act synergistically to reduce end-organ dysfunction by the altering the inflammatory response, in a unique manner compared with CLP.

METHODS

Using Pseudomonas aeruginosa pneumonia, a pulmonary sepsis model (pneumonia [PNA]) was compared directly to previously investigated intra-abdominal sepsis models. Machine learning applied to early vital signs stratified animals into those predicted to die (pDie) versus predicted to live (pLive). Animals were then randomized to receive antibiotics and fluids (vehicle [VEH]) vs. HAT). Vitals, cytokines, vitamin C, and markers of liver and kidney function were assessed in the blood, bronchoalveolar lavage, and organ homogenates.

RESULTS

PNA was induced in 119 outbred wild-type Institute of Cancer Research mice (predicted mortality approximately 50%) similar to CLP. In PNA, interleukin 1 receptor antagonist in 72-hour bronchoalveolar lavage was lower with HAT (2.36 ng/mL) compared with VEH (4.88 ng/mL; p = 0.04). The remaining inflammatory cytokines and markers of liver/renal function showed no significant difference with HAT in PNA. PNA vitamin C levels were 0.62 mg/dL (pDie HAT), lower than vitamin C levels after CLP (1.195 mg/dL). Unlike CLP, PNA mice did not develop acute kidney injury (blood urea nitrogen: pDie, 33.5 mg/dL vs. pLive, 27.6 mg/dL; p = 0.17). Furthermore, following PNA, HAT did not significantly reduce microscopic renal oxidative stress (mean gray area: pDie, 16.64 vs. pLive, 6.88; p = 0.93). Unlike CLP where HAT demonstrated a survival benefit, HAT had no impact on survival in PNA.

CONCLUSION

Hydrocortisone, ascorbic acid, and thiamine therapy has minimal benefits in pneumonia. The inflammatory response induced by pulmonary sepsis is unique compared with the response during intra-abdominal sepsis. Consequently, different etiologies of sepsis respond differently to HAT therapy.

Defining Sepsis Phenotypes-Two Murine Models of Sepsis and Machine Learning

INTRODUCTION

The immunobiology defining the clinically apparent differences in response to sepsis remains unclear. We hypothesize that in murine models of sepsis we can identify phenotypes of sepsis using non-invasive physiologic parameters (NIPP) early after infection to distinguish between different inflammatory states.

METHODS

Two murine models of sepsis were used: gram-negative pneumonia (PNA) and cecal ligation and puncture (CLP). All mice were treated with broad spectrum antibiotics and fluid resuscitation. High-risk sepsis responders (pDie) were defined as those predicted to die within 72 h following infection. Low-risk responders (pLive) were expected to survive the initial 72 h of sepsis. Statistical modeling in R was used for statistical analysis and machine learning.

RESULTS

NIPP obtained at 6 and 24 h after infection of 291 mice (85 PNA and 206 CLP) were used to define the sepsis phenotypes. Lasso regression for variable selection with 10-fold cross-validation was used to define the optimal shrinkage parameters. The variables selected to discriminate between phenotypes included 6-h temperature and 24-h pulse distention, heart rate (HR), and temperature. Applying the model to fit test data (n = 55), area under the curve (AUC) for the receiver operating characteristics (ROC) curve was 0.93. Subgroup analysis of 120 CLP mice revealed a HR of <620 bpm at 24 h as a univariate predictor of pDie. (AUC of ROC curve = 0.90). Subgroup analysis of PNA exposed mice (n = 121) did not reveal a single predictive variable highlighting the complex physiological alterations in response to sepsis.

CONCLUSION

In murine models with various etiologies of sepsis, non-invasive vitals assessed just 6 and 24 h after infection can identify different sepsis phenotypes. Stratification by sepsis phenotypes can transform future studies investigating novel therapies for sepsis.

Identification of Clinical Phenotypes in Septic Patients Presenting With Hypotension or Elevated Lactate

Introduction

Targeted therapies for sepsis have failed to show benefit due to high variability among subjects. We sought to demonstrate different phenotypes of septic shock based solely on clinical features and show that these relate to outcome.

Methods

A retrospective analysis was performed of a 1,023-subject cohort with early septic shock from the ProCESS trial. Twenty-three clinical variables at baseline were analyzed using hierarchical clustering, with consensus clustering used to identify and validate the ideal number of clusters in a derivation cohort of 642 subjects from 20 hospitals. Clusters were visualized using heatmaps over 0, 6, 24, and 72 h. Clinical outcomes were 14-day all-cause mortality and organ failure pattern. Cluster robustness was confirmed in a validation cohort of 381 subjects from 11 hospitals.

Results

Five phenotypes were identified, each with unique organ failure patterns that persisted in time. By enrollment criteria, all patients had shock. The two high-risk phenotypes were characterized by distinct multi-organ failure patterns and cytokine signatures, with the highest mortality group characterized most notably by liver dysfunction and coagulopathy while the other group exhibited primarily respiratory failure, neurologic dysfunction, and renal dysfunction. The moderate risk phenotype was that of respiratory failure, while low-risk phenotypes did not have a high degree of additional organ failure.

Conclusions

Sepsis phenotypes with distinct biochemical abnormalities may be identified by clinical characteristics alone and likely provide an opportunity for early clinical actionability and prognosis.

Esmolol to Treat the Hemodynamic Effects of Septic Shock: A Randomized Controlled Trial

INTRODUCTION

Septic shock is often characterized by tachycardia and a hyperdynamic hemodynamic profile. Use of the beta antagonist esmolol has been proposed as a therapy to lower heart rate, thereby improving diastolic filling time and improving cardiac output, resulting in a reduction in vasopressor support.

METHODS

We conducted a two-center, open-label, randomized, Phase II trial comparing esmolol to placebo in septic shock patients with tachycardia. The primary endpoint was improvement in hemodynamics as measured by the difference in norepinephrine equivalent dose (NED) between groups at 6 hours after initiation of study drug. Secondary outcomes included assessing differences in inflammatory biomarkers and oxygen consumption (VO2).

RESULTS

A total of 1,122 patients were assessed for eligibility and met inclusion criteria; 42 underwent randomization, and 40 received study interventions (18 in the esmolol arm and 22 in the usual care arm). The mean NED at 6 h was 0.30 ± 0.17 mcg/kg/min in the esmolol arm compared to 0.21 ± 0.19 in the standard care arm (P = 0.15). There was no difference in number of shock free days between the esmolol (2, IQR 0, 5) and control groups (2.5, IQR 0, 6) (P = 0.32). There were lower levels of C-reactive protein at 12 and 24 h in the esmolol arm, as well as a statistically significant difference in trend over time between groups. There were no differences in terms of IL-4, IL-6, IL-10, and TNFα. Among a subset who underwent VO2 monitoring, there was decreased oxygen consumption in the esmolol patients; the mean difference between groups at 24 h was -2.07 mL/kg/min (95% CI -3.82, -0.31) (P = 0.02), with a significant difference for the trend over time (P < 0.01).

CONCLUSION

Among patients with septic shock, infusion of esmolol did not improve vasopressor requirements or time to shock reversal. Esmolol was associated with decreased levels of C-reactive protein over 24 h.

TRIAL REGISTRATION

www.clinicaltrials.gov. Registered February 24, 2015, https://clinicaltrials.gov/ct2/show/NCT02369900.

Olaparib attenuates sepsis-induced acute multiple organ injury via ERK-mediated CD14 expression

Sepsis is characterized by persistent systemic inflammation, which can cause multi-organ dysfunction. The poly polymerase-1 inhibitor olaparib possesses anti-inflammatory properties. This study aimed to assess the effects of olaparib (pre- and post-treatments) on sepsis, and to investigate whether it could suppress CD14 expression via the ERK pathway in polymicrobial sepsis and peritoneal macrophages models. Sepsis was induced by cecal ligation and puncture in C57BL/6 male mice. Fifty mice were randomly divided into five groups: The sham group was treated with vehicle or olaparib, the cecal ligation and puncture group with vehicle or with olaparib (5 mg/kg i.p.) 1 h before or 2 h after surgery. Olaparib pretreatment significantly improved the survival of septic mice (P < 0.001). Pre- and post-treatment of mice with olaparib partly alleviated cecal ligation and puncture-induced organ injury by decreasing the amounts of the pro-inflammatory mediators TNF-α and IL-6 as well as bacterial burden in the serum, peritoneal lavage fluid, and organs (P < 0.05). The protective effect of olaparib was associated with CD14 suppression via inhibition of ERK activation. Olaparib facilitated negative regulation of ERK-mediated CD14 expression, which may contribute to multi-organ injury in sepsis.

Chrysin Ameliorates Sepsis-Induced Cardiac Dysfunction Through Upregulating Nfr2/Heme Oxygenase 1 Pathway

ABSTRACT

The incidence of myocardial dysfunction caused by sepsis is high, and the mortality of patients with sepsis can be significantly increased. During sepsis, oxidative stress and inflammation can lead to severe organ dysfunction. Flavone chrysin is one of the indispensable biological active ingredients for different fruits and vegetables and has antioxidant and anti-inflammatory properties. However, it is not clear whether chrysin is an effective treatment for heart dysfunction caused by sepsis. We found that it had protective effects against the harmful effects caused by LPS, manifested in improved survival, normalized cardiac function, improved partial pathological scores of myocardial tissue, and remission of apoptosis, as well as reduced oxidative stress and inflammation. Mechanism studies have found that chrysin is an important antioxidant protein, a key regulator of heme oxygenase 1 (HO-1). We found that HO-1 levels were increased after LPS intervention, and chrysin further increased HO-1 levels, along with the addition of Nrf2, a regulator of antioxidant proteins. Pretreatment with PD98059, an extracellular signal-regulated kinase-specific inhibitor, blocked chrysin-mediated phosphorylation of Nrf2 and the nuclear translocation of Nrf2. The protective effect of chrysin on sepsis-induced cardiac dysfunction was blocked by ZnPP, which is a HO-1 blocker. Chrysin increased antioxidant activity and reduced markers of oxidative stress (SOD and MDA) and inflammation (MPO and IL-1β), all of which were blocked by ZnPP. This indicates that HO-1 is the upstream molecule regulating the protective effect of chrysin. Thus, by upregulation of HO-1, chrysin protects against LPS-induced cardiac dysfunction and inflammation by inhibiting oxidative stress.

Resveratrol attenuates TLR-4 mediated inflammation and elicits therapeutic potential in models of sepsis

Sepsis is a potentially fatal condition triggered by systemic inflammatory response to infection. Due to the heightened immune reactivity and multi-organ pathology, treatment options are limited and several clinical trials have not produced the desired outcome, hence the interest in the discovery of novel therapeutic strategies. The polyphenol resveratrol (RSV) has shown promise against several pathological states, including acute and chronic inflammation. In this study, we evaluated its therapeutic potential in a murine model of sepsis and in patients undergoing transrectal ultrasound biopsy. RSV was able to inhibit lipopolysaccharide (LPS) stimulated inflammatory responses through blocking Phospholipase D (PLD) and its downstream signaling molecules SphK1, ERK1/2 and NF-κB. In addition, RSV treatment resulted in the downregulation of MyD88, an adaptor molecule in the TLR4 signaling pathway, and this effect at least in part, involved RSV-induced autophagy. Notably, RSV protected mice against polymicrobial septic shock induced upon cecal ligation and puncture, and inhibited pro-inflammatory cytokine production by human monocytes from transrectal ultrasound (TRUS) biopsy patients. Together, these findings demonstrate the immune regulatory activity of RSV and highlight its therapeutic potential in the management of sepsis.

PhospholipaseCγ1/calcium-dependent membranous localization of Gsdmd-N drives endothelial pyroptosis, contributing to lipopolysaccharide-induced fatal outcome

Multiple organ perfusion is impaired in sepsis. Clinical studies suggest that persistent perfusion disturbances are prognostic of fatal outcome in sepsis. Pyroptosis occurs upon activation of caspases and their subsequent cleavage of gasdermin D (Gsdmd), resulting in Gsdmd-N (activated NH₂-terminal fragment of Gsdmd) that form membrane pores to induce cell death in sepsis. In addition, Gsdmd^-/- mice are protected from a lethal dose of lipopolysaccharide (LPS). However, how Gsdmd-mediated pyroptosis occurs in endothelial cells and leads to impaired perfusion remain unexplored in endotoxemia. We used transgenic mice with ablation of Gsdmd and determined that mice lacking Gsdmd exhibited reduced breakdown of endothelial barrier, improved organ perfusion, as well as increased survival in endotoxemia. Phospholipase Cγ1 (PLCγ1) contributed to Gsdmd-mediated endothelial pyroptosis in a calcium-dependent fashion, without affecting Gsdmd-N production. Cytosolic calcium signaling promoted Gsdmd-N translocation to the plasma membrane, enhancing endothelial pyroptosis induced by LPS. We used adeno-associated virus (AAV9) vectors carrying a short hairpin RNA (shRNA) against murine PLCγ1 mRNA under control of the tie1 core promoter (AAV-tie1-sh-PLCγ1) to uniquely downregulate PLCγ1 expression in the endothelial cells. Here, we showed that unique inhibition of endothelial PLCγ1 attenuated breakdown of endothelial barrier, reduced vascular leakage, and improved perfusion disturbances. Moreover, unique downregulate endothelial PLCγ1 expression markedly decreased mortality of mice in endotoxemia. Thus, we establish that endothelial injury as an important trigger of fatal outcome in endotoxemia. Additionally, these findings suggest that interfering with Gsdmd and PLCγ1-calcium pathway may represent a new treatment strategy for critically ill patients sustaining endotoxemia.NEW & NOTEWORTHY Our study newly reveals that Phospholipase Cγ1 (PLCγ1) contributes to gasdermin D (Gsdmd)-mediated endothelial pyroptosis in a calcium-dependent fashion. Cytosolic calcium signaling promotes activated NH₂-terminal fragment of Gsdmd (Gsdmd-N) to translocate to the plasma membrane, enhancing endothelial pyroptosis induced by cytoplasmic LPS. Genetic or pharmacologic inhibition of endothelial PLCγ1 attenuated breakdown of endothelial barrier, reduced vascular leakage, improve perfusion disturbances, and decrease mortality of mice in endotoxemia.

Overview: Systemic Inflammatory Response Derived From Lung Injury Caused by SARS-CoV-2 Infection Explains Severe Outcomes in COVID-19

Most SARS-CoV2 infections will not develop into severe COVID-19. However, in some patients, lung infection leads to the activation of alveolar macrophages and lung epithelial cells that will release proinflammatory cytokines. IL-6, TNF, and IL-1β increase expression of cell adhesion molecules (CAMs) and VEGF, thereby increasing permeability of the lung endothelium and reducing barrier protection, allowing viral dissemination and infiltration of neutrophils and inflammatory monocytes. In the blood, these cytokines will stimulate the bone marrow to produce and release immature granulocytes, that return to the lung and further increase inflammation, leading to acute respiratory distress syndrome (ARDS). This lung-systemic loop leads to cytokine storm syndrome (CSS). Concurrently, the acute phase response increases the production of platelets, fibrinogen and other pro-thrombotic factors. Systemic decrease in ACE2 function impacts the Renin-Angiotensin-Kallikrein-Kinin systems (RAS-KKS) increasing clotting. The combination of acute lung injury with RAS-KKS unbalance is herein called COVID-19 Associated Lung Injury (CALI). This conservative two-hit model of systemic inflammation due to the lung injury allows new intervention windows and is more consistent with the current knowledge.

A novel role of nifuroxazide in attenuation of sepsis-associated acute lung and myocardial injuries; role of TLR4/NLPR3/IL-1β signaling interruption

Acute lung injury (ALI) and the subsequent multi-system organ failure is a serious health problem with devastating impacts on the health care systems. Indeed, the world has been facing an un-preceded situation in the past couple of months following COVID-19 infestation and the associated high-mortality rates mainly attributed to sepsis and the associated multiple organ failures of particular concern; acute respiratory distress syndrome post lung injury. The current study provides evidence on the ameliorative impact of nifuroxazide, and FDA approved antidiarrheal drug in attenuation of lipopolysaccharide (LPS)-induced ALI and myocarditis when administrated either in prophylactic or curative regimens. Nifuroxazide administration was associated with a significant improvement in lung and heart histopathological characteristics and architecture with retraction of LPS-induced inflammatory-infiltration. This was associated with retraction in serum biomarkers of cellular injury of which; LDH, CK-MB, and ALP. Nifuroxazide administration was associated with a significant improvement in both lung and heart oxidative status. Such positive outcomes were underlined by a significant inhibitory effect of nifuroxazide on lung and heart contents of toll-like receptor (4) (TLR4)/the inflammasome NALPR3/interleukin- 1β (IL-1β). In conclusion: Nifuroxazide attenuates LPS-induced ALI and myocardial injury via interruption of TLR4/NALPR3/IL-1β signaling. Thus it can offer a potential approach for attenuation of sepsis in critically ill patients.

Premise for Standardized Sepsis Models

Sepsis morbidity and mortality exacts a toll on patients and contributes significantly to healthcare costs. Preclinical models of sepsis have been used to study disease pathogenesis and test new therapies, but divergent outcomes have been observed with the same treatment even when using the same sepsis model. Other disorders such as diabetes, cancer, malaria, obesity, and cardiovascular diseases have used standardized, preclinical models that allow laboratories to compare results. Standardized models accelerate the pace of research and such models have been used to test new therapies or changes in treatment guidelines. The National Institutes of Health mandated that investigators increase data reproducibility and the rigor of scientific experiments and has also issued research funding announcements about the development and refinement of standardized models. Our premise is that refinement and standardization of preclinical sepsis models may accelerate the development and testing of potential therapeutics for human sepsis, as has been the case with preclinical models for other disorders. As a first step toward creating standardized models, we suggest standardizing the technical standards of the widely used cecal ligation and puncture model and creating a list of appropriate organ injury and immune dysfunction parameters. Standardized sepsis models could enhance reproducibility and allow comparison of results between laboratories and may accelerate our understanding of the pathogenesis of sepsis.

Checkpoint inhibitor therapy in preclinical sepsis models: a systematic review and meta-analysis

BACKGROUND

Animal studies reporting immune checkpoint inhibitors (CPIs) improved host defense and survival during bacterial sepsis provided one basis for phase I CPI sepsis trials. We performed a systematic review and meta-analysis examining the benefit of CPI therapy in preclinical studies, and whether variables potentially altering this clinical benefit were investigated. Studies were analyzed that compared survival following bacteria or lipopolysaccharide challenge in animals treated with inhibitors to programmed death-1 (PD-1), PD-ligand1 (PD-L1), cytotoxic T lymphocyte-associated protein-4 (CTLA-4), or B- and T-lymphocyte attenuator (BTLA) versus control.

RESULTS

Nineteen experiments from 11 studies (n = 709) were included. All experiments were in mice, and 10 of the 19 were published from a single research group. Sample size calculations and randomization were not reported in any studies, and blinding procedures were reported in just 1. Across all 19 experiments, CPIs increased the odds ratio for survival (OR, 95% CI) [3.37(1. 55, 7.31)] but with heterogeneity (I² = 59%, p < 0.01). After stratification by checkpoint molecule targeted, challenge site or type, or concurrent antibacterial treatment, CPIs had consistent effects over most experiments in the 9 that included antibacterial treatment [OR = 2.82 (1.60, 4.98), I² = 6%, p = 0.39 with versus 4.01 (0.89, 18.05), I² = 74%, p < 0.01 without]. All 9 antibiotic experiments employed cecal-ligation and puncture (CLP) bacterial challenge while 6 also included a Candida albicans challenge 3-4 days after CLP. In these six experiments (n = 322), CPIs were directed at the fungal challenge when CLP lethality had resolved, and were consistently beneficial [2.91 (2.41, 3.50), I² = 0%, p = 0.99]. In the three experiments (n = 66) providing antibiotics without fungal challenge, CPIs were administered within 1 day of CLP and had variable and non-significant effects [0.05 (0.00, 1.03); 7.86 (0.28, 217.11); and 8.50 (0.90, 80.03)]. No experiment examined pneumonia.

CONCLUSIONS

Preclinical studies showing that CPIs add benefit to antibiotic therapy for the common bacterial infections causing sepsis clinically are needed to support this therapeutic approach. Studies should be reproducible across multiple laboratories and include procedures to reduce the risk of bias.

Incidence, trends, and outcomes of infection sites among hospitalizations of sepsis: A nationwide study

Purpose

To determine the trends of infection sites and outcome of sepsis using a national population-based database.

Materials and methods

Using the Nationwide Inpatient Sample database of the US, adult sepsis hospitalizations and infection sites were identified using a validated approach that selects admissions with explicit ICD-9-CM codes for sepsis and diagnosis/procedure codes for acute organ dysfunctions. The primary outcome was the trend of incidence and in-hospital mortality of specific infection sites in sepsis patients. The secondary outcome was the impact of specific infection sites on in-hospital mortality.

Results

During the 9-year period, we identified 7,860,687 admissions of adult sepsis. Genitourinary tract infection (36.7%), lower respiratory tract infection (36.6%), and systemic fungal infection (9.2%) were the leading three sites of infection in patients with sepsis. Intra-abdominal infection (30.7%), lower respiratory tract infection (27.7%), and biliary tract infection (25.5%) were associated with highest mortality rate. The incidences of all sites of infections were trending upward. Musculoskeletal infection (annual increase: 34.2%) and skin and skin structure infection (annual increase: 23.0%) had the steepest increase. Mortality from all sites of infection has decreased significantly (trend p<0.001). Skin and skin structure infection had the fastest declining rate (annual decrease: 5.5%) followed by primary bacteremia (annual decrease: 5.3%) and catheter related bloodstream infection (annual decrease: 4.8%).

Conclusions

The anatomic site of infection does have a differential impact on the mortality of septic patients. Intra-abdominal infection, lower respiratory tract infection, and biliary tract infection are associated with higher mortality in septic patients.

Haptoglobin therapy has differential effects depending on severity of canine septic shock and cell-free hemoglobin level

BACKGROUND

During sepsis, higher plasma cell-free hemoglobin (CFH) levels portend worse outcomes. In sepsis models, plasma proteins that bind CFH improve survival. In our canine antibiotic-treated Staphylococcus aureus pneumonia model, with and without red blood cell (RBC) exchange transfusion, commercial human haptoglobin (Hp) concentrates bound and compartmentalized CFH intravascularly, increased CFH clearance, and lowered iron levels, improving shock, lung injury, and survival. We now investigate in our model how very high CFH levels and treatment time affect Hp's beneficial effects.

MATERIALS AND METHODS

Two separate canine pneumonia sepsis Hp studies were undertaken: one with exchange transfusion of RBCs after prolonged storage to raise CFH to very high levels and another with rapidly lethal sepsis alone to shorten time to treat. All animals received continuous standard intensive care unit supportive care for 96 hours.

RESULTS

Older RBCs markedly elevated plasma CFH levels and, when combined with Hp therapy, created supraphysiologic CFH-Hp complexes that did not increase CFH or iron clearance or improve lung injury and survival. In a rapidly lethal bacterial challenge model without RBC transfusion, Hp binding did not increase clearance of complexes or iron or show benefits seen previously in the less lethal model.

DISCUSSION

High-level CFH-Hp complexes may impair clearance mechanisms and eliminate Hp's beneficial effect during sepsis. Rapidly lethal sepsis narrows the therapeutic window for CFH and iron clearance, also decreasing Hp's beneficial effects. In designing clinical trials, dosing and kinetics may be critical factors if Hp infusion is used to treat sepsis.

Linezolid and Its Immunomodulatory Effect: In Vitro and In Vivo Evidence

Recent studies have explored the effects of some antibacterial agents on various aspects of the immune response to infection in addition to their bactericidal effects. As a synthetic oxazolidinone class of antibacterial agent, linezolid (LZD) exhibits activity against a broad range of Gram-positive bacteria. In the present review, we summarized the effects of LZD on the immune response and new approaches that can exploit such interactions for the treatment of bacterial infections. In vitro and pre-clinical evidence demonstrate that LZD suppresses the phagocytic ability, cytokine synthesis, and secretion of immune cells as well as the expressions of immune-related genes at the mRNA level under the stimulation of endotoxin or pathogens. Immunomodulatory effects of LZD can not only reduce the inflammatory damage induced by exaggerated or prolonged release of pro-inflammatory cytokines during infections but can also be applied to alleviate the symptoms of non-infectious inflammatory conditions. Further research is necessary to explore the molecular mechanisms involved and confirm these findings in clinical practice.

Cytokines in Inflammatory Disease

This review aims to briefly discuss a short list of a broad variety of inflammatory cytokines. Numerous studies have implicated that inflammatory cytokines exert important effects with regard to various inflammatory diseases, yet the reports on their specific roles are not always consistent. They can be used as biomarkers to indicate or monitor disease or its progress, and also may serve as clinically applicable parameters for therapies. Yet, their precise role is not always clearly defined. Thus, in this review, we focus on the existing literature dealing with the biology of cytokines interleukin (IL)-6, IL-1, IL-33, tumor necrosis factor-alpha (TNF-α), IL-10, and IL-8. We will briefly focus on the correlations and role of these inflammatory mediators in the genesis of inflammatory impacts (e.g., shock, trauma, immune dysregulation, osteoporosis, and/or critical illness).

Honokiol Increases CD4+ T Cell Activation and Decreases TNF but Fails to Improve Survival Following Sepsis

Honokiol is a biphenolic isolate extracted from the bark of the magnolia tree that has been used in traditional Chinese and Japanese medicine, and has more recently been investigated for its anti-inflammatory and antibacterial properties. Honokiol has previously been demonstrated to improve survival in sepsis models that have rapid 100% lethality. The purpose of this study was to determine the impact of Honokiol on the host response in a model of sepsis that more closely approximates human disease. Male and female C57BL/6 mice underwent cecal ligation and puncture to induce polymicrobial intra-abdominal sepsis. Mice were then randomized to receive an injection of either Honokiol (120 mg/kg/day) or vehicle and were sacrificed after 24 h for functional studies or followed 7 days for survival. Honokiol treatment after sepsis increased the frequency of CD4 T cells and increased activation of CD4 T cells as measured by the activation marker CD69. Honokiol also increased splenic dendritic cells. Honokiol simultaneously decreased frequency and number of CD8 T cells. Honokiol decreased systemic tumor necrosis factor without impacting other systemic cytokines. Honokiol did not have a detectable effect on kidney function, lung physiology, liver function, or intestinal integrity. In contrast to prior studies of Honokiol in a lethal model of sepsis, Honokiol did not alter survival at 7 days (70% mortality for Honokiol vs. 60% mortality for vehicle). Honokiol is thus effective in modulating the host immune response and inflammation following a clinically relevant model of sepsis but is not sufficient to alter survival.

Epidemiology of Sepsis-3 in a sub-district of Beijing: secondary analysis of a population-based database

BACKGROUND

With the publication of Sepsis-3 definition, epidemiological data based on Sepsis-3 definition from middle-income countries including China are scarce, which prohibits understanding of the disease burden of this newly defined syndrome in these settings. The purpose of this study was to describe incidence and outcome of Sepsis-3 in Yuetan sub-district of Beijing and to estimate the incidence rate of Sepsis-3 in China.

METHODS

The medical records of all adult residents hospitalized from July 1, 2012 to June 30, 2014 in Yuetan sub-district of Beijing were reviewed. Patients with sepsis-3 and severe sepsis/septic shock were identified. The incidence rates and mortality rate of sepsis-3 and sepsis/septic shock were calculated, incidence rates and in-hospital mortality rates were normalized to the population distribution in the 2010 National Census. Population incidence rate and case fatality rate between sexes were compared with the Z test, as the data conformed to Poisson distribution.

RESULTS

Of the 21,191 hospitalized patients, 935 patients were diagnosed with Sepsis-3, and 498 cases met severe sepsis/septic shock criteria. The crude annual incidence rate of Sepsis-3 in Yuetan sub-district was 363 cases per 100,000 population, corresponding to standardized incidence rates of 236 cases per 100,000 population per year, respectively. The overall case fatality rate of Sepsis-3 was 32.0%, the crude population mortality rates of Sepsis-3 was 116 cases per 100,000 population per year, the standardized mortality rate was 67 cases per 100,000 population per year, corresponding to a speculative extrapolation of 700,437 deaths in China. The incidence rate and mortality rate of Sepsis-3 were significantly higher in males, elderly people, and patients with more comorbidities. The 62.1% of patients with Sepsis-3 had community-acquired infections, compared with 75.3% of infected patients without Sepsis-3 (P < 0.001). The most common infection in patients with Sepsis-3 was lower respiratory tract infection. When compared with patients with Sepsis-3, patients diagnosed as severe sepsis/septic shock were more likely to have higher case fatality rate (53.4% vs. 32.0%, P < 0.001) CONCLUSIONS:: This study found the standardized incidence rate of 236 cases per 100,000 person-year for Sepsis-3, which was more common in males and elderly population. This corresponded to about 2.5 million new cases of Sepsis-3 per year, resulting in more than 700,000 deaths in China.

CLINICAL TRIAL REGISTRATION

NCT02285257, https://clinicaltrials.gov/ct2/show/record/NCT02285257.

Risk related therapy in meta-analyses of critical care interventions: Bayesian meta-regression analysis

PURPOSE

The relationship between treatment efficacy and patient risk is explored in a series of meta-analyses from the critical care domain, focusing on mortality outcome.

METHODS

Systematic reviews of randomized controlled trials were identified by electronic search over the period 2002 to July 2018. A Bayesian meta-regression model was employed, using the risk difference metric to estimate the relationship between mortality difference and control arm risk, and estimate the mortality difference with and without adjusting for control arm risk.

RESULTS

Of 780 initially identified published systematic reviews, 113 had appropriate mortality data comprising 123 analysable groups. The 123 meta-analyses were pharmaceutical therapeutic (59.3%), non-pharmaceutical therapeutic (24.4%) and nutritional (16.3%), with a 25% overall average control arm mortality. In 25/123 (20%) analyses, meta-regression indicated significant baseline risk (Bayesian 95% credible intervals excluding zero). In all analyses, the relationship between risk-difference and control arm risk was negative indicating a positive treatment effect with increasing control arm risk. Adjusted estimates identified six studies with significant positive treatment effects, not evident until after adjustment for control arm risk.

CONCLUSION

Underlying risk-related therapy is apparent in meta-analyses of the critically-ill and identification is of importance to both the conduct and interpretation of these meta-analyses.

Anti-inflammatory, anti-oxidative stress effect of Phascolosoma esculenta oligosaccharides on Escherichia coli-induced sepsis mice

Bacterial infection is the most common cause of sepsis. In this study, Phascolosoma esculenta oligosaccharides (PEOs) were prepared to evaluate their resistance against E. coli-induced sepsis. HPLC-MS and FT-IR indicated that PEOs were composed of d-glucosyl, d-galactosyl, with small amount of d-mannosyl, d-arabinosyl and residues with α- and β-type linkage. Different dosage administrations of PEOs for 30 days significantly improved ICR mice survival rate and bacterial clearance ability (P < 0.01) after as E. coli injection. Moreover, PEOs significantly reduced the secretion of IL-1β and TNF-α and enhanced that of IL-10 in sepsis mice, enhanced the antioxidant enzyme activities and total antioxidant capacity, decreased MDA level in the serum, and upregulated mRNA expression of Nrf2 (P < 0.01). All these results indicate that PEOs could improve the resistance of ICR mice against E. coli-induced sepsis that attributed to anti-inflammatory and anti-oxidative stress.

Role of interleukin-3 as a prognostic marker in septic patients

Objective

To evaluate the accuracy of IL-3 to predict the outcome of septic patients.

Methods

Prospective cohort study with adult patients in an intensive care unit with sepsis or septic shock diagnosed within the previous 48 hours. Circulating IL-3 levels were measured upon inclusion (day 1) and on days 3 and 7. The primary outcome was hospital mortality.

Results

One hundred and twenty patients were included. Serum levels of IL-3 on day 1 were significantly higher among patients who died than among patients who survived the hospital stay (91.2pg/mL versus 36pg/mL, p = 0.024). In a Cox survival model considering the IL-3 levels at inclusion, age and sequential SOFA, IL-3 values remained independently associated with mortality (HR 1.032; 95%CI 1.010 - 1.055; p = 0.005). An receiver operating characteristic curve was built to further investigate the accuracy of IL-3, with an area under the curve of 0.62 (95%CI 0.51 - 0.73; p = 0.024) for hospital mortality. A cutoff initial IL-3 value above 127.5pg/mL was associated with hospital mortality (OR 2.97; 95%CI: 1.27 - 6.97; p = 0.0019) but with a low performance (82% for specificity, 39% for sensibility, 53% for the positive predictive value, 72% for the negative predictive value, 0.73 for the negative likelihood and 2.16 for the positive likelihood ratio).

Conclusion

Higher levels of IL-3 are shown to be independently associated with hospital mortality in septic patients but with poor clinical performance.

Immune therapy in sepsis: Are we ready to try again?

Immune therapy to ease the burden of sepsis has thus far failed to consistently improve patient outcomes. Advances in cancer immune therapy and awareness that prolonged immune-suppression in sepsis can leave patients vulnerable to secondary infection and death have driven resurgence in the field of sepsis immune-therapy investigation. As we develop and evaluate these novel therapies, we must learn from past experiences where single-mediator targeted immune therapies were blindly delivered to heterogeneous patient cohorts with complex and evolving immune responses. Advances in genomics, proteomics, metabolomics, and point-of-care technology, coupled with a better understanding of sepsis pathogenesis, have meant that personalised immune-therapy is on the horizon. Here, we review the complex immune pathogenesis in sepsis and the contemporary immune therapies that are being investigated to manipulate this response. An outline of the immune biomarkers that may be used to support this approach is also provided.

Effect of Low-Dose Hydrocortisone Therapy in Adult Patients With Septic Shock: A Meta-Analysis With Trial Sequential Analysis of Randomized Controlled Trials

BACKGROUND

The efficacy of low-dose hydrocortisone therapy in the management of septic shock remains controversial in critical care for many years. Hence, we performed this meta-analysis of randomized controlled trials (RCTs) with trial sequential analysis (TSA) to evaluate its effect on clinical outcome among adult patients with septic shock.

METHODS

We identified relevant RCTs published from inception to March 7, 2018 comparing low-dose hydrocortisone with placebo or no intervention in adults admitted to the intensive care unit (ICU) for septic shock. Meta-analyses were performed for the primary and secondary outcomes. The risk of bias was assessed using the Cochrane Collaboration's instrument. Trial sequential analysis was used to pool the results from the included studies for the primary outcomes.

RESULTS

Thirteen studies were retrieved by our literature search strategy. There were no significant differences in 28-day mortality (odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.81-1.00; P = .05) and hospital mortality (OR = 0.91, 95% CI = 0.82-1.02; P = .09) between the 2 groups, which were confirmed by TSA. However, there was a significant improvement in shock reversal in the hydrocortisone group (OR = 1.33, 95% CI = 1.02-1.72; P = .03). Furthermore, subgroup analyses revealed that hydrocortisone plus fludrocortisone statistically reduced the rate of 28-day mortality (OR = 0.79, 95% CI = 0.64-0.97; P = .03), ICU mortality (OR = 0.77, 95% CI = 0.63-0.95; P = .02), and hospital mortality (OR = 0.77, 95% CI = 0.63-0.95; P = .01) in comparison with the placebo, the results were also confirmed by TSA.

CONCLUSION

Among adult patients with septic shock, the use of low-dose hydrocortisone compared with control did not confer overall survival benefits, albeit improving shock reversal rate. The benefit of reducing 28-day mortality, ICU mortality, and hospital mortality was observed in combination use of hydrocortisone and fludrocortisone.

Haptoglobin improves shock, lung injury, and survival in canine pneumonia

During the last half-century, numerous antiinflammatory agents were tested in dozens of clinical trials and have proven ineffective for treating septic shock. The observation in multiple studies that cell-free hemoglobin (CFH) levels are elevated during clinical sepsis and that the degree of increase correlates with higher mortality suggests an alternative approach. Human haptoglobin binds CFH with high affinity and, therefore, can potentially reduce iron availability and oxidative activity. CFH levels are elevated over approximately 24-48 hours in our antibiotic-treated canine model of S. aureus pneumonia that simulates the cardiovascular abnormalities of human septic shock. In this 96-hour model, resuscitative treatments, mechanical ventilation, sedation, and continuous care are translatable to management in human intensive care units. We found, in this S. aureus pneumonia model inducing septic shock, that commercial human haptoglobin concentrate infusions over 48-hours bind canine CFH, increase CFH clearance, and lower circulating iron. Over the 96-hour study, this treatment was associated with an improved metabolic profile (pH, lactate), less lung injury, reversal of shock, and increased survival. Haptoglobin binding compartmentalized CFH to the intravascular space. This observation, in combination with increasing CFHs clearance, reduced available iron as a potential source of bacterial nutrition while decreasing the ability for CFH and iron to cause extravascular oxidative tissue injury. In contrast, haptoglobin therapy had no measurable antiinflammatory effect on elevations in proinflammatory C-reactive protein and cytokine levels. Haptoglobin therapy enhances normal host defense mechanisms in contrast to previously studied antiinflammatory sepsis therapies, making it a biologically plausible novel approach to treat septic shock.

The Emperor Has No Clothes? Searching for Dysregulation in Sepsis

The core conception of sepsis—that it is a dysregulated state—is a powerful and durable idea that has inspired decades of research. But is it true that the body’s response to sepsis is dysregulated? To answer that question, this review surveyed the history of trials of experimental sepsis treatments targeting the host response. Sepsis survival is not improved by blocking one or many immune pathways. Similarly, sepsis is resistant to treatment by normalizing one or many physiologic parameters simultaneously. The vast majority of interventions are either ineffective or harmful. With this track record of failure, it is time to consider the alternative hypothesis—regulation instead of dysregulation—and the possibility that sepsis traits are often functional, and that some physiologic alterations in sepsis do more good than harm, while others are neutral. This review discusses the implications of this perspective for the future of sepsis research.

Chronic Critical Illness and Persistent Inflammation: What can we Learn from the Elderly, Injured, Septic, and Malnourished?

Patients in the intensive care unit (ICU) who develop chronic critical illness significantly stress the clinical capacity and financial resources of healthcare systems. Although vast improvements have been made in critical care management, outcomes for this ICU subset remain poor. A hallmark for patients who progress to chronic critical illness is the development of persistent inflammation and immunosuppression. The risk factors associated with the development of chronic critical illness include increased age, medical comorbidities, severe injury, septic shock, and malnutrition. Interestingly, each of these clinical states bears strikingly similar immune defects, often resulting in the activation of a persistent inflammatory state. Strategies aimed at the prevention or early recognition of this state of immune compromise may help improve outcomes for these individuals and minimize the number who progress to chronic critical illness. This review explores the current knowledge regarding the immune defects associated with the development of persistent inflammation, the ways in which it can manifest clinically, attempted therapeutic interventions to date, and future insights into improving outcomes for this patient population.

Advances in the understanding and treatment of sepsis-induced immunosuppression

Sepsis is defined as a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Sepsis can induce acute kidney injury and multiple organ failures and represents the most common cause of death in the intensive care unit. Sepsis initiates a complex immune response that varies over time, with the concomitant occurrence of both pro-inflammatory and anti-inflammatory mechanisms. As a result, most patients with sepsis rapidly display signs of profound immunosuppression, which is associated with deleterious consequences. Scientific advances have highlighted the role of metabolic failure, epigenetic reprogramming, myeloid-derived suppressor cells, immature suppressive neutrophils and immune alterations in primary lymphoid organs (the thymus and bone marrow) in sepsis. An improved understanding of the mechanisms underlying this immunosuppression as well as of the similarities between sepsis-induced immunosuppression and immune defects in cancer or immunosenescence has led to novel therapeutic strategies aimed at stimulating immune function in patients with sepsis. Trials assessing the therapeutic benefit of IL-7, granulocyte-macrophage colony-stimulating factor (GM-CSF) and antibodies against programmed cell death protein 1 (PD1) and programmed cell death 1 ligand 1 (PDL1) for the treatment of sepsis are in progress. The reappraisal of sepsis pathophysiology has also resulted in a novel approach to the design of clinical trials evaluating sepsis treatments, based on an evaluation of the immune status and biomarker-based stratification of patients.

Impact of thrombosis on pulmonary endothelial injury and repair following sepsis

The prevailing morbidity and mortality in sepsis are largely due to multiple organ dysfunction (MOD), most commonly lung injury, as well as renal and cardiac dysfunction. Despite recent advances in defining many aspects of the pathogenesis of sepsis-related MOD, including acute respiratory distress syndrome (ARDS), there are currently no effective pharmacological or cell-based treatments for the disease. Human and animal studies have shown that pulmonary thrombosis is common in sepsis-induced ARDS, and preclinical studies have shown that anticoagulation may improve outcome following sepsis challenge. The potential beneficial effect of anticoagulation on outcome is unconvincing in clinical studies, however, and these discrepancies may arise from the multiple and sometimes opposing actions of thrombosis on the pulmonary endothelium following sepsis. It has been suggested, for example, that mild pulmonary thrombosis prevents escape of bacterial infection into the circulation, while severe thrombosis causes hypoxia and results in pulmonary endothelial damage. Evidence from both human and animal studies has demonstrated the key role of microvascular leakage in determining the outcome of sepsis. In this review, we describe thrombosis-dependent mechanisms that regulate pulmonary endothelial injury and repair following sepsis, including activation of the coagulation cascade by tissue factor and stimulation of vascular repair by hypoxia-inducible factors. Targeting such mechanisms through anticoagulant, anti-inflammatory, and reparative methods may represent a novel approach for the treatment of septic patients.

Simultaneous targeting of CD14 and factor XIa by a fusion protein consisting of an anti-CD14 antibody and the modified second domain of bikunin improves survival in rabbit sepsis models

Severe sepsis is a complex, multifactorial, and rapidly progressing disease characterized by excessive inflammation and coagulation following bacterial infection. To simultaneously suppress pro-inflammatory and pro-coagulant responses, we genetically engineered a novel fusion protein (MR1007) consisting of an anti-CD14 antibody and the modified second domain of bikunin, and evaluated the potential of MR1007 as an anti-sepsis agent. Suppressive effects of MR1007 on lipopolysaccharide (LPS)-induced inflammatory responses were assessed using peripheral blood mononuclear cells or endothelial cells. Its inhibitory activity against the coagulation factor XIa was assessed using a purified enzyme and a chromogenic substrate. Anticoagulant activity was assessed using human or rabbit plasma. Anti-inflammatory and anti-coagulant effects and/or survival benefits were evaluated in an endotoxemia model and a cecal ligation and puncture model. MR1007 inhibited LPS-induced cytokine production in peripheral blood mononuclear cells and endothelial cells, inhibited factor XIa, and exhibited anticoagulant activity. In an endotoxemia model, 0.3-3mg/kg MR1007 suppressed pro-inflammatory and pro-coagulant responses in a dose-dependent manner; at a dose of 3mg/kg, the protein improved survival even when administered 8h after the LPS injection. In addition, 10mg/kg MR1007 administered 2h post cecal ligation and puncture improved survival. However, MR1007 administered at doses up to 30mg/kg did not increase ear bleeding time or bacterial counts in the cecal ligation and puncture model. Thus, simultaneous targeting of CD14 and factor XIa improves survival in the rabbit endotoxemia and sepsis models and represents a promising approach for the treatment of severe sepsis.

Butyrate pretreatment attenuates heart depression in a mice model of endotoxin-induced sepsis via anti-inflammation and anti-oxidation

OBJECTIVES

The depressed heart function is the main complication to cause death of septic patients in clinic. It is urgent to find effective interventions for this intractable disease. In this study, we investigated whether butyrate could be protective for heart against sepsis and the underlying mechanism.

METHODS

Mice were randomly divided into three groups. Model group challenged with LPS (30 mg/kg, i.p.) only. Butyrate group received butyrate (200 mg/kg·d) for 3days prior to LPS administration (30 mg/kg). Normal group received saline only. 6h and 12h after LPS administration were chosen for detection the parameters to estimate the effects or mechanism of butyrate pretreatment on heart of sepsis.

RESULTS

The data showed that septic heart depression was attenuated by butyrate pretreatment through improvement of heart function depression (P<0.01) and reduction of morphological changes of myocardium. The overexpression of proinflammatory factors, TNF-α, IL-6 and LTB4, in heart tissues induced by sepsis was significantly alleviated by butyrate pretreatment (P<0.01). As oxidative stress indicators, SOD and CAT activity, and MDA content in heart were deteriorated by LPS challenge, which was noticeably ameliorated by butyrate pretreatment (P<0.01 or P<0.05).

CONCLUSIONS

In conclusion, pretreatment with butyrate attenuated septic heart depression via anti-inflammation and anti-oxidation.

Treatment of endotoxaemia and septicaemia in the equine patient

Endotoxins, constituents of the cell wall of gram-positive and gram-negative bacteria, regularly result in severe illness and death in horses. In endotoxaemia, these constituents are present in the systemic circulation; in septicaemia, whole microbes invade normally sterile parts of the body. Interaction of these endotoxins with pathogen recognition receptors leads to an inflammatory response that cannot always be sufficiently contained and hence needs direct treatment. Over the last decennia, our understanding of the pathophysiology of endotoxaemia and septicaemia has significantly increased. Based on improved understanding of the interaction between receptors and endotoxins as well as the subsequent downstream signalling pathways, new therapeutic targets have been identified in laboratory animal species and humans. Important species differences in the recognition of endotoxins and pathogens by their receptors as well as the inflammatory response to receptor activation hamper extrapolation of this information to the horse (and other species). Historically, horses with endotoxaemia and septicaemia have been treated mainly symptomatically and supportively. Based on the identified therapeutic targets, this review describes the current knowledge of the treatment for endotoxaemia and septicaemia in the horse with reference to the findings in other animal species and humans.