In vivo delivery of caspase-8 or Fas siRNA improves the survival of septic mice

Cell death proteins in sepsis: key players and modern therapeutic approaches

Cell death proteins play a central role in host immune signaling during sepsis. These interconnected mechanisms trigger cell demise via apoptosis, necroptosis, and pyroptosis while also driving inflammatory signaling. Targeting cell death mediators with novel therapies may correct the dysregulated inflammation seen during sepsis and improve outcomes for septic patients.

Toll-like receptor 2 deficiency relieves splenic immunosuppression during sepsis

Immunosuppression is associated with long-term mortality during sepsis. However, the underlying mechanism of immunosuppression remains poorly understood. Toll-like receptor 2 (TLR2) contributes to sepsis pathogenesis. We sought to determine the role of TLR2 in immunosuppression in the spleen during polymicrobial sepsis. Using an experimental model of polymicrobial sepsis induced by cecal ligation and puncture (CLP), we measured the expression of inflammatory cytokines and chemokines in spleen 6 and 24 h after CLP to evaluate the immune response, and compared the expression of inflammatory cytokines and chemokines, apoptosis, and intracellular ATP production in spleen of wild-type (WT) and TLR2-deficient (TLR2^-/-) mice 24 h after CLP. We found that pro-inflammatory cytokines and chemokines, such as TNF-α and IL-1β peaked 6 h after CLP, while IL-10, an anti-inflammatory cytokine, peaked 24 h after CLP in the spleen. At this later time point, TLR2^-/- mice presented decreased levels of IL-10 and decreased caspase 3 activation but no significant difference in intracellular ATP production in spleen compared to WT mice. Our data imply that TLR2 has a pronounced effect on sepsis-induced immunosuppression in spleen.

Serum Fas levels during first week of sepsis are associated with severity and mortality

INTRODUCTION

The aim of our study was to explore whether there is an association of serum sFas (cell death apoptosis receptor) concentrations during the first week of sepsis with sepsis severity and sepsis mortality.

METHODS

In this observational study, septic patients were recruited. Serum sFas concentrations were determined on days 1, 4, and 8 of sepsis diagnosis. Thirty-day mortality was the outcome variable.

RESULTS

Surviving patients (n = 181) compared to non-survivors (n = 101) presented lower serum sFas levels on day 1 (p < 0.001), day 4 (p < 0.001) and day 8 (p < 0.001), and lower SOFA on day 1 (p < 0.001), day 4 (p < 0.001) and day 8 (p < 0.001). Logistic regression analyses showed associations between 30-day mortality and serum sFas levels controlling for SOFA on day 1 (OR = 1.005; 95% CI = 1.003-1.007; p < 0.001), day 4 (OR = 1.044; 95% CI = 1.029-1.060; p < 0.001) and day 8 (OR = 1.012; 95% CI = 1.002-1.022; p = 0.02).

CONCLUSIONS

The association of serum sFas concentrations during the first week of sepsis with sepsis severity and sepsis mortality were our new findings.

Cytokeratin 18 cell death assays as biomarkers for quantification of apoptosis and necrosis in COVID-19: a prospective, observational study

BACKGROUND

The mechanism by which SARS-CoV-2 triggers cell damage and necrosis are yet to be fully elucidated. We sought to quantify epithelial cell death in patients with COVID-19, with an estimation of relative contributions of apoptosis and necrosis.

METHODS

Blood samples were collected prospectively from adult patients presenting to the emergency department. Circulating levels of caspase-cleaved (apoptosis) and total cytokeratin 18 (CK-18) (total cell death) were determined using M30 and M65 enzyme assays, respectively. Intact CK-18 (necrosis) was estimated by subtracting M30 levels from M65.

RESULTS

A total of 52 COVID-19 patients and 27 matched sick controls (with respiratory symptoms not due to COVID-19) were enrolled. Compared with sick controls, COVID-19 patients had higher levels of M65 (p = 0.046, total cell death) and M30 (p = 0.0079, apoptosis). Hospitalised COVID-19 patients had higher levels of M65 (p= 0.014) and intact CK-18 (p= 0.004, necrosis) than discharged patients. Intensive care unit (ICU)-admitted COVID-19 patients had higher levels of M65 (p= 0.004), M30 (p= 0.004) and intact CK-18 (p= 0.033) than hospitalised non-ICU admitted patients. In multivariable logistic regression, elevated levels of M65, M30 and intact CK-18 were associated with increased odds of ICU admission (OR=22.05, p=0.014, OR=19.71, p=0.012 and OR=14.12, p=0.016, respectively).

CONCLUSION

Necrosis appears to be the main driver of hospitalisation, whereas apoptosis and necrosis appear to drive ICU admission. Elevated levels CK-18 levels are independent predictors of severe disease, and could be useful for risk stratification of COVID-19 patients and in assessment of therapeutic efficacy in early-phase COVID-19 clinical trials.

Blood caspase-8 concentrations and mortality among septic patients

OBJECTIVE

No data are available on blood caspase-8 concentrations (the initiator caspase in the extrinsic apoptosis pathway) in septic patients. The present study thus describes the blood caspase-8 concentrations in survivors and non-survivors, and examines the possible association between blood caspase-8 concentrations and mortality in septic patients.

DESIGN

A prospective observational study was carried out.

SETTING

Three Spanish Intensive Care Units.

PATIENTS

Septic patients.

INTERVENTIONS

Serum caspase-8 concentrations were determined at the diagnosis of sepsis.

MAIN VARIABLE OF INTEREST

Mortality after 30 days.

RESULTS

Patients not surviving at day 30 (n=81) compared to surviving patients (n=140) showed higher serum caspase-8 levels (p<0.001). Multiple logistic regression analysis found an association between serum caspase-8 levels>43.5ng/ml and mortality (OR=3.306; 95%CI=1.619-6.753; p=0.001). The area under the curve (AUC) for mortality predicted by serum caspase-8 levels was 67% (95% CI=60-73%; p<0.001).

CONCLUSIONS

The novel findings of our study were that blood caspase-8 concentrations are higher in non-survivors than in survivors, and that there is an association between blood caspase-8 concentrations and mortality in septic patients.

Association of serum soluble Fas concentrations and mortality of septic patients

INTRODUCTION

Scarce data on Fas, one of the main receptors that activates the apoptosis extrinsic pathway, in septic patients exists. Higher blood soluble Fas (sFas) concentrations in non-survivor septic patients compared with survivors have been found in small studies; however, the association of blood sFas concentrations with mortality controlling for sepsis severity has not been stablished due to this small sample size in those studies. Thus, our main objective study was to determine whether an association between blood sFas concentrations and sepsis mortality controlling for sepsis severity exists.

METHODS

We included septic patients in this observational and prospective study carried out in three Spanish Intensive Care Units. We obtained serum samples at sepsis diagnosis sepsis for sFas levels determination.

RESULTS

Thirty-day non-surviving patients (n=85) compared to surviving patients (n=151) had higher serum sFas levels (p<0.001). We found in multiple logistic regression analysis an association of serum sFas levels with mortality controlling for age and SOFA (OR=1.004; 95% CI=1.002-1.006; p<0.001), and for age and APACHE-II (OR=1.004; 95% CI=1.002-1.006; p<0.001). Serum sFas levels showed and area under the curve for mortality prediction of 71% (95% CI=65-71%; p<0.001). Kaplan-Meier analysis showed higher mortality rate in patients with serum sFas levels>83.5ng/mL (Hazard ratio=3.2; 95% CI=2.1-5.0; p<0.001).

CONCLUSIONS

That an association between blood sFas concentrations and sepsis mortality controlling for sepsis severity exists was our main new finding study.

Blood concentrations of proapoptotic sFas and antiapoptotic Bcl2 and COVID-19 patient mortality

Background: There are no data on circulating concentrations of sFas (proapoptotic protein of extrinsic pathway) and Bcl2 (antiapoptotic protein of intrinsic pathway) in COVID-19 patients. Thus, our objective study was to determine whether an association exists between serum concentrations of sFas and Bcl2 and COVID-19 patient mortality.Methods: This observational and prospective study of COVID-19 patients was performed in eight Intensive Care Units (ICU) from Canary Islands (Spain). Serum levels of sFas and Bcl2 at ICU admission were determined. Mortality at 30 days was the end-point study.Results: Surviving patients (n = 42) compared to non-surviving (n = 11) had lower APACHE-II (p < 0.001), lower SOFA (p = 0.004), lower serum sFas levels (p = 0.001) and higher serum Bcl2 levels (p < 0.001). Logistic regression showed an association between high serum sFas levels and mortality after controlling for APACHE-II (OR = 1.004; 95% CI = 1.101-1.007; p = 0.01) or SOFA (OR = 1.003; 95% CI = 1.101-1.106; p = 0.004), and between low serum Bcl2 levels and mortality after controlling for APACHE-II (OR = 0.927; 95% CI = 0.873-0.984; p = 0.01) or SOFA (OR = 0.949; 95% CI = 0.913-0.987; p = 0.01).Conclusions: Thus, to the best of our knowledge, this is the first study reporting blood levels of sFas and Bcl2 in COVID-19 patients and its association with mortality.

Association of serum soluble Fas concentrations and mortality of septic patients

INTRODUCTION

Scarce data on Fas, one of the main receptors that activates the apoptosis extrinsic pathway, in septic patients exists. Higher blood soluble Fas (sFas) concentrations in non-survivor septic patients compared with survivors have been found in small studies; however, the association of blood sFas concentrations with mortality controlling for sepsis severity has not been stablished due to this small sample size in those studies. Thus, our main objective study was to determine whether an association between blood sFas concentrations and sepsis mortality controlling for sepsis severity exists.

METHODS

We included septic patients in this observational and prospective study carried out in three Spanish Intensive Care Units. We obtained serum samples at sepsis diagnosis sepsis for sFas levels determination.

RESULTS

Thirty-day non-surviving patients (n=85) compared to surviving patients (n=151) had higher serum sFas levels (p<0.001). We found in multiple logistic regression analysis an association of serum sFas levels with mortality controlling for age and SOFA (OR=1.004; 95% CI=1.002-1.006; p<0.001), and for age and APACHE-II (OR=1.004; 95% CI=1.002-1.006; p<0.001). Serum sFas levels showed and area under the curve for mortality prediction of 71% (95% CI=65-71%; p<0.001). Kaplan-Meier analysis showed higher mortality rate in patients with serum sFas levels>83.5ng/mL (Hazard ratio=3.2; 95% CI=2.1-5.0; p<0.001).

CONCLUSIONS

That an association between blood sFas concentrations and sepsis mortality controlling for sepsis severity exists was our main new finding study.

Association between serum sFasL concentrations and sepsis mortality

BACKGROUND

There are scarce data on soluble Fas Ligand (sFasL), one of the main ligands that activate the apoptosis extrinsic pathway, in septic patients. In a small study of septic children were found higher plasma sFasL levels in non-survivors compared with survivors; however, an association between blood sFasL levels and mortality controlling for sepsis severity was not stablished due to the small sample size of the study. Therefore, the main objective of this study was to determine whether there is an association between blood sFasL concentrations and mortality in septic patients controlling for sepsis severity. Methods: Septic patients were included in this observational and prospective study conducted in three Spanish Intensive Care Units. Serum samples at diagnosis of sepsis were obtained for serum sFasL levels determination.

RESULTS

Thirty-day non-surviving patients (n = 85) with respect to surviving patients (n = 151) showed higher serum sFasL levels (p<.001). Multiple logistic regression analysis found an association between serum sFasL levels and mortality (odds ratio [OR] = 1.007; 95% confidence interval [CI] = 1.003-1.010; p<.001) after controlling for age, septic shock, SOFA, INR and aPTT. The area under the curve (AUC) for mortality prediction by serum sFasL levels was of 62% (95% CI = 56-69%; p=.003). In Kaplan-Meier analysis was found that patients with serum sFasL levels >109 pg/mL had a higher mortality rate (hazard ratio = 3.6; 95% CI = 1.93-6.78; p<.001).

CONCLUSIONS

The main new finding from our study was that serum sFasL concentrations were associated with mortality in septic patients controlling for sepsis severity. Highlights Blood sFasL concentrations were higher in non-survivor than in survivor patients. There is an association between blood sFasL concentrations and mortality in septic patients. Blood sFasL concentrations could predict mortality of septic patients.

Blood caspase-8 concentrations and mortality among septic patients

OBJECTIVE

No data are available on blood caspase-8 concentrations (the initiator caspase in the extrinsic apoptosis pathway) in septic patients. The present study thus describes the blood caspase-8 concentrations in survivors and non-survivors, and examines the possible association between blood caspase-8 concentrations and mortality in septic patients.

DESIGN

A prospective observational study was carried out.

SETTING

Three Spanish Intensive Care Units.

PATIENTS

Septic patients.

INTERVENTIONS

Serum caspase-8 concentrations were determined at the diagnosis of sepsis.

MAIN VARIABLE OF INTEREST

Mortality after 30 days.

RESULTS

Patients not surviving at day 30 (n=81) compared to surviving patients (n=140) showed higher serum caspase-8 levels (p<0.001). Multiple logistic regression analysis found an association between serum caspase-8 levels>43.5ng/ml and mortality (OR=3.306; 95%CI=1.619-6.753; p=0.001). The area under the curve (AUC) for mortality predicted by serum caspase-8 levels was 67% (95% CI=60-73%; p<0.001).

CONCLUSIONS

The novel findings of our study were that blood caspase-8 concentrations are higher in non-survivors than in survivors, and that there is an association between blood caspase-8 concentrations and mortality in septic patients.

CD4 T Cell Responses and the Sepsis-Induced Immunoparalysis State

Sepsis remains a major cause of death in the United States and worldwide, and costs associated with treating septic patients place a large burden on the healthcare industry. Patients who survive the acute phase of sepsis display long-term impairments in immune function due to reductions in numbers and function of many immune cell populations. This state of chronic immunoparalysis renders sepsis survivors increasingly susceptible to infection with newly or previously encountered infections. CD4 T cells play important roles in the development of cellular and humoral immune responses following infection. Understanding how sepsis impacts the CD4 T cell compartment is critical for informing efforts to develop treatments intended to restore immune system homeostasis following sepsis. This review will focus on the current understanding of how sepsis impacts the CD4 T cell responses, including numerical representation, repertoire diversity, phenotype and effector functionality, subset representation (e.g., Th1 and Treg frequency), and therapeutic efforts to restore CD4 T cell numbers and function following sepsis. Additionally, we will discuss recent efforts to model the acute sepsis phase and resulting immune dysfunction using mice that have previously encountered infection, which more accurately reflects the immune system of humans with a history of repeated infection throughout life. A thorough understanding of how sepsis impacts CD4 T cells based on previous studies and new models that accurately reflect the human immune system may improve translational value of research aimed at restoring CD4 T cell-mediated immunity, and overall immune fitness following sepsis.

Epigenetic biomarkers for human sepsis and septic shock: insights from immunosuppression

Sepsis is a life-threatening condition that occurs when the body responds to an infection damaging its own tissues. Sepsis survivors sometimes suffer from immunosuppression increasing the risk of death. To our best knowledge, there is no 'gold standard' for defining immunosuppression except for a composite clinical end point. As the immune system is exposed to epigenetic changes during and after sepsis, research that focuses on identifying new biomarkers to detect septic patients with immunoparalysis could offer new epigenetic-based strategies to predict short- and long-term pathological events related to this life-threatening state. This review describes the most relevant epigenetic mechanisms underlying alterations in the innate and adaptive immune responses described in sepsis and septic shock, and their consequences for immunosuppression states, providing several candidates to become epigenetic biomarkers that could improve sepsis management and help predict immunosuppression in postseptic patients.

IL-17A activated by Toll-like receptor 9 contributes to the development of septic acute kidney injury

Toll-like receptor 9 (TLR9), which is activated by endogenously released mtDNA during sepsis, contributes to the development of polymicrobial septic acute kidney injury (AKI). However, downstream factors of TLR9 to AKI remain unknown. We hypothesized that IL-17A activated by TLR9 may play a critical role in septic AKI development. To determine the effects of TLR9 on IL-17A production in septic AKI, we used a cecal ligation and puncture (CLP) model in Tlr9 knockout (Tlr9KO) mice and wild-type (WT) littermates. We also investigated the pathway from TLR9 activation in dendritic cells (DCs) to IL-17A production by γδT cells in vitro. To elucidate the effects of IL-17A on septic AKI, Il-17a knockout (Il-17aKO) mice and WT littermates were subjected to CLP. We further investigated the relationship between the TLR9-IL-17A axis and septic AKI by intravenously administering recombinant IL-17A or vehicle into Tlr9KO mice and assessing kidney function. IL-17A levels in both plasma and the peritoneal cavity and mRNA levels of IL-23 in the spleen were significantly higher in WT mice after CLP than in Tlr9KO mice. Bone marrow-derived DCs activated by TLR9 induced IL-23 and consequently promoted IL-17A production in γδT cells in vitro. Knockout of Il-17a improved survival, functional and morphological aspects of AKI, and splenic apoptosis after CLP. Exogenous IL-17A administration aggravated CLP-induced AKI attenuated by knockout of Tlr9. TLR9 in DCs mediated IL-17A production in γδT cells during sepsis and contributed to the development of septic AKI.

Cortex Mori Radicis extract promotes neurite outgrowth in diabetic rats by activating PI3K/AKT signaling and inhibiting Ca2+ influx associated with the upregulation of transient receptor potential canonical channel 1

Cortex Mori Radicis extract (CMR) has various pharmacological properties, such as anti‑inflammatory, anti‑allergic and anti‑hyperglycemic effects. However, the effects and mechanisms of CMR in the neuroregeneration of diabetic peripheral neuropathy (DPN) are unclear. In the present study, the effects of CMR on neurite outgrowth of dorsal root ganglia (DRG) neurons in diabetic rats were investigated and its underlying mechanisms were explored. SD rats were subjected to a high‑fat diet with low‑dose streptozotocin to induce a Type II diabetes model with peripheral neuropathy. CMR was then applied for four weeks continuously with or without injection of small interfere (si)RNA targeting the transient receptor potential canonical channel 1 (TRPC1) via the tail vein. Blood glucose levels, the number of Nissl bodies, neurite outgrowth and growth cone turning in DRG neurons were evaluated. The expression of TRPC1 protein, Ca2+ influx and activation of the PI3K/AKT signaling pathway were also investigated. The results of the present study showed that CMR significantly lowered blood glucose levels, reversed the loss of Nissl bodies, induced neurite outgrowth and restored the response of the growth cone of DRG neurons in diabetic rats. CMR exerted neurite outgrowth‑promoting effects by increasing TRPC1 expression, reducing Ca2+ influx and enhancing AKT phosphorylation. siRNA targeting TRPC1 in the CMR group abrogated its anti‑diabetic and neuroregenerative effects, suggesting the involvement of TRPC1 in the biological effects of CMR on DPN.

2B4 but not PD-1 blockade improves mortality in septic animals with preexisting malignancy

In addition to its well-known beneficial effects for the treatment of several types of cancer, PD-1 blockade has shown encouraging results in preclinical models of sepsis and in a recent clinical trial in sepsis. Because cancer is the most common comorbidity in septic patients, here we aimed to determine the efficacy of PD-1 checkpoint blockade in the setting of sepsis complicated with preexisting malignancy. In a model of established lung cancer followed by cecal ligation and puncture-induced (CLP-induced) sepsis, PD-1 blockade exhibited no therapeutic effect on sepsis survival. This diminished efficacy of PD-1 blockade in cancer septic animals (septic animals with cancer) was characterized by a reduction in both the quality and quantity of PD-1+ responder cells. Specifically, CD8+ T cells isolated from cancer septic animals exhibited decreased CD28 expression and a reduction in the CXCR5+PD-1+ subset. In addition, flow cytometric analysis of T cells isolated from cancer septic animals revealed 2B4 as another possible checkpoint under these conditions. Administration of anti-2B4 to cancer septic animals significantly improved sepsis survival and was associated with increased T cell costimulatory receptor expression and decreased coinhibitory receptor expression. These results illustrate functions of coinhibitory receptors in the setting of sepsis complicated with cancer.

Activator Protein-1 Decoy Oligodeoxynucleotide Transfection Is Beneficial in Reducing Organ Injury and Mortality in Septic Mice

OBJECTIVES

Inflammation and apoptosis are decisive mechanisms for the development of end-organ injury in sepsis. Activator protein-1 may play a key role in regulating expression of harmful genes responsible for the pathophysiology of septic end-organ injury along with the major transcription factor nuclear factor-κB. We investigated whether in vivo introduction of circular dumbbell activator protein-1 decoy oligodeoxynucleotides can provide benefits for reducing septic end-organ injury.

DESIGN

Laboratory and animal/cell research.

SETTINGS

University research laboratory.

SUBJECTS

Male BALB/c mice (8-10 wk old).

INTERVENTIONS

Activator protein-1 decoy oligodeoxynucleotides were effectively delivered into tissues of septic mice in vivo by preparing into a complex with atelocollagen given 1 hour after surgery.

MATERIALS AND MAIN RESULTS

Polymicrobial sepsis was induced by cecal ligation and puncture in mice. Activator protein-1 decoy oligodeoxynucleotide transfection inhibited abnormal production of proinflammatory and chemotactic cytokines after cecal ligation and puncture. Histopathologic changes in lung, liver, and kidney tissues after cecal ligation and puncture were improved by activator protein-1 decoy oligodeoxynucleotide administration. When activator protein-1 decoy oligodeoxynucleotides were given, apoptosis induction was strikingly suppressed in lungs, livers, kidneys, and spleens of cecal ligation and puncture mice. These beneficial effects of activator protein-1 decoy oligodeoxynucleotides led to a significant survival advantage in mice after cecal ligation and puncture. Apoptotic gene profiling indicated that activator protein-1 activation was involved in the up-regulation of many of proapoptotic and antiapoptotic genes in cecal ligation and puncture-induced sepsis.

CONCLUSIONS

Our results indicate a detrimental role of activator protein-1 in the sepsis pathophysiology and the potential usefulness of activator protein-1 decoy oligodeoxynucleotides for the prevention and treatment of septic end-organ failure.

The volatile anesthetic sevoflurane reduces neutrophil apoptosis via Fas death domain-Fas-associated death domain interaction

Sepsis remains a significant health care burden, with high morbidities and mortalities. Patients with sepsis often require general anesthesia for procedures and imaging studies. Knowing that anesthetic drugs can pose immunomodulatory effects, it would be critical to understand the impact of anesthetics on sepsis pathophysiology. The volatile anesthetic sevoflurane is a common general anesthetic derived from ether as a prototype. Using a murine sepsis model induced by cecal ligation and puncture surgery, we examined the impact of sevoflurane on sepsis outcome. Different from volatile anesthetic isoflurane, sevoflurane exposure significantly improved the outcome of septic mice. This was associated with less apoptosis in the spleen. Because splenic apoptosis was largely attributed to the apoptosis of neutrophils, we examined the effect of sevoflurane on FasL-induced neutrophil apoptosis. Sevoflurane exposure significantly attenuated apoptosis. Sevoflurane did not affect the binding of FasL to the extracellular domain of Fas receptor. Instead, in silico analysis suggested that sevoflurane would bind to the interphase between Fas death domain (DD) and Fas-associated DD (FADD). The effect of sevoflurane on Fas DD-FADD interaction was examined using fluorescence resonance energy transfer (FRET). Sevoflurane attenuated FRET efficiency, indicating that sevoflurane hindered the interaction between Fas DD and FADD. The predicted sevoflurane binding site is known to play a significant role in Fas DD-FADD interaction, supporting our in vitro and in vivo apoptosis results.-Koutsogiannaki, S., Hou, L., Babazada, H., Okuno, T., Blazon-Brown, N., Soriano, S. G., Yokomizo, T., Yuki, K. The volatile anesthetic sevoflurane reduces neutrophil apoptosis via Fas death domain-Fas-associated death domain interaction.

Caspase-1 inhibitor exerts brain-protective effects against sepsis-associated encephalopathy and cognitive impairments in a mouse model of sepsis

Sepsis-associated encephalopathy (SAE) manifested clinically in acute and long-term cognitive impairments and associated with increased morbidity and mortality worldwide. The potential pathological changes of SAE are complex and remain to be elucidated. Pyroptosis, a novel programmed cell death, is executed by caspase-1-cleaved GSDMD N-terminal (GSDMD-NT) and we investigated it in peripheral blood immunocytes of septic patients previously. Here, a caspase-1 inhibitor VX765 was treated with CLP-induced septic mice. Novel object recognition test indicated that VX765 treatment reversed cognitive dysfunction in septic mice. Elevated plus maze, tail suspension test and open field test revealed that depressive-like behaviors of septic mice were relieved. Inhibited caspase-1 suppressed the expressions of GSDMD and its cleavage form GSDMD-NT, and reduced pyroptosis in brain at day 1 and day 7 after sepsis. Meantime, inhibited caspase-1 mitigated the expressions of IL-1β, MCP-1 and TNF-α in serum and brain, diminished microglia activation in septic mice, and reduced sepsis-induced brain-blood barrier disruption and ultrastructure damages in brain as well. Inhibited caspase-1 protected the synapse plasticity and preserved long-term potential, which may be the possible mechanism of cognitive functions protective effects of septic mice. In conclusion, caspase-1 inhibition exerts brain-protective effects against SAE and cognitive impairments in a mouse model of sepsis.

Sepsis-Induced T Cell Immunoparalysis: The Ins and Outs of Impaired T Cell Immunity

Sepsis results in a deluge of pro- and anti-inflammatory cytokines, leading to lymphopenia and chronic immunoparalysis. Sepsis-induced long-lasting immunoparalysis is defined, in part, by impaired CD4 and CD8 αβ T cell responses in the postseptic environment. The dysfunction in T cell immunity affects naive, effector, and memory T cells and is not restricted to classical αβ T cells. Although sepsis-induced severe and transient lymphopenia is a contributory factor to diminished T cell immunity, T cell-intrinsic and -extrinsic factors/mechanisms also contribute to impaired T cell function. In this review, we summarize the current knowledge of how sepsis quantitatively and qualitatively impairs CD4 and CD8 T cell immunity of classical and nonclassical T cell subsets and discuss current therapeutic approaches being developed to boost the recovery of T cell immunity postsepsis induction.

Novel Role for PD-1:PD-L1 as Mediator of Pulmonary Vascular Endothelial Cell Functions in Pathogenesis of Indirect ARDS in Mice

Deficiency of the co-inhibitory receptor, Programmed cell death receptor (PD)-1, provides a survival benefit in our murine shock/sepsis model for the development of indirect acute respiratory distress syndrome (iARDS). Further, of clinical significance, patients that develop ARDS express increased PD-1 on their blood leukocytes. While PD-1 expression and its regulatory role have been associated with mainly T-cell responses, the contribution of its primary ligand, PD-L1, broadly expressed on non-immune cells such as lung endothelial cells (ECs) as well as immune cells, is less well-understood. Here we show that a “priming insult” for iARDS, such as non-lethal hemorrhagic shock alone, produced a marked increase in lung EC PD-L1 as well as blood leukocyte PD-1 expression, and when combined with a subsequent “trigger event” (polymicrobial sepsis), not only induced marked iARDS but significant mortality. These sequelae were both attenuated in the absence of PD-L1. Interestingly, we found that gene deficiency of both PD-1 and PD-L1 improved EC barrier function, as measured by decreased bronchoalveolar lavage fluid protein (i.e., lung leak). However, PD-L1 deficiency, unlike PD-1, significantly decreased EC activation through the Angiopoietin/Tie2 pathway in our iARDS mice. Additionally, while PD-1 gene deficiency was associated with decreased neutrophil influx in our iARDS mice, EC monolayers derived from PD-L1 deficient mice showed increased expression of EC junction proteins in response to ex vivo TNF-α stimulation. Together, these data suggest that ligation of PD-1:PD-L1 may play a novel role(s) in the maintenance of pulmonary EC barrier regulation, beyond that of the classic regulation of the leukocyte tolerogenic immune response, which may account for its pathogenic actions in iARDS.

Endogenous H2S resists mitochondria-mediated apoptosis in the adrenal glands via ATP5A1 S-sulfhydration in male mice

In a previous study, we showed that endogenous hydrogen sulfide (H₂S) plays a key role in the maintenance of intact adrenal cortex function via the protection of mitochondrial function during endoxemia. We further investigated whether mitochondria-mediated apoptosis is involved in H₂S protection of adrenal function. LPS treatment resulted in mitochondria-mediated apoptosis in the adrenal glands of male mice, and these effects were prevented by the H₂S donor GYY4137. In the model of Y1 cells, the LPS-induced mitochondria-mediated apoptosis and blunt response to ACTH were rescued by GYY4137. The H₂S-generating enzyme cystathionine-β-synthase (CBS) knockout heterozygous (CBS^+/-) mice showed mitochondria-mediated apoptosis in the adrenal gland and adrenal insufficiency. GYY4137 treatment restored adrenal function and eliminated mitochondria-mediated apoptosis. Maleimide assay combined with mass spectrometry analysis showed that a number of proteins in mitochondria were S-sulfhydrated in the adrenal gland. ATP5A1 was further confirmed as S-sulfhydrated using a modified biotin switch assay. The level of S-sulfhydrated ATP5A1 was decreased in the adrenal gland of endotoxemic and CBS^+/- mice, which was restored by GYY4137. ATP5A1 was identified as sulfhydrated at cysteine 244 by H₂S. Overexpression of the cysteine 244 mutant ATP5A1 in Y1 cells resulted in a loss of LPS-induced mitochondria-mediated apoptosis and GYY4137 restoration of LPS-induced hyporesponsiveness to ACTH. Collectively, the present study revealed that decreased H₂S generation leads to mitochondrial-mediated apoptosis in the adrenal cortex and a blunt response to ACTH. S-sulfhydration of ATP5A1 at cysteine 244 is an important molecular mechanism by which H₂S maintains mitochondrial function and steroidogenesis in the adrenal glands.

High Circulating Caspase-Cleaved Keratin 18 Fragments (M30) Indicate Short-Term Mortality in Critically Ill Patients

Caspase-cleaved fragments of the intermediate filament protein keratin 18 (cytokeratin-18 (CK18)) can be detected in serum as M30 levels and may serve as a circulating biomarker indicating apoptosis of epithelial and parenchymal cells. In order to evaluate M30 as a biomarker in critical illness, we analyzed circulating M30 levels in 243 critically ill patients (156 with sepsis, 87 without sepsis) at admission to the medical intensive care unit (ICU), in comparison to healthy controls (n = 32). M30 levels were significantly elevated in ICU patients compared with healthy controls. Circulating M30 was closely associated with disease severity but did not differ between patients with sepsis and ICU patients without sepsis. M30 serum levels were correlated with biomarkers of inflammation, cell injury, renal failure, and liver failure in critically ill patients. Patients that died at the ICU showed increased M30 levels at admission, compared with surviving patients. A similar trend was observed for the overall survival. Regression analyses confirmed that M30 levels are associated with mortality, and patients with M30 levels above 250.8 U/L displayed an excessive short-term mortality. Thus, our data support the utility of circulating levels of the apoptosis-related keratin fragment M30 as a prognostic biomarker at ICU admission.

Inhibition of MicroRNA-23b Attenuates Immunosuppression During Late Sepsis Through NIK, TRAF1, and XIAP

Background

microRNA-23b (miR-23b) is a multiple functional miRNA. We hypothesize that miR-23b plays a role in the pathogenesis of sepsis. Our study investigated the effect of miR-23b on sepsis-induced immunosuppression.

Methods

Mice were treated with miR-23b inhibitors by tail vein injection 2 days after cecal ligation puncture (CLP)-induced sepsis. Apoptosis in spleens and apoptotic signals were investigated, and survival was monitored. T-cell immunoreactivities were examined during late sepsis. Nuclear factor κB (NF-κB)-inducing kinase (NIK), tumor necrosis factor (TNF)-receptor associated factor 1 (TRAF1), and X-linked inhibitor of apoptosis protein (XIAP), the putative targets of miR-23b, were identified by a dual-luciferase reporter assay.

Results

miR-23b expression is upregulated and sustained during sepsis. The activation of the TLR4/TLR9/p38 MAPK/STAT3 signal pathway contributes to the production of miR-23b in CLP-induced sepsis. miR-23b inhibitor decreased the number of spleen cells positive by terminal deoxynucleotidyl transferase dUTP nick-end labeling and improved survival. miR-23b inhibitor restored the immunoreactivity by alleviating the development of T-cell exhaustion and producing smaller amounts of immunosuppressive interleukin 10 and interleukin 4 during late sepsis. We demonstrated that miR-23b mediated immunosuppression during late sepsis by inhibiting the noncanonical NF-κB signal and promoting the proapoptotic signal pathway by targeting NIK, TRAF1, and XIAP.

Conclusions

Inhibition of miR-23b reduces late-sepsis-induced immunosuppression and improves survival. miR-23b might be a target for immunosuppression.

Nucleic-acid based gene therapy approaches for sepsis

Despite advances in overall medical care, sepsis and its sequelae continue to be an embarrassing clinical entity with an unacceptably high mortality rate. The central reason for high morbidity and high mortality of sepsis and its sequelae is the lack of an effective treatment. Previous clinical trials have largely failed to identify an effective therapeutic target to improve clinical outcomes in sepsis. Thus, the key goal favoring the outcome of septic patients is to devise innovative and evolutionary therapeutic strategies. Gene therapy can be considered as one of the most promising novel therapeutic approaches for nasty disorders. Since a number of transcription factors, such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), play a pivotal role in the pathophysiology of sepsis that can be characterized by the induction of multiple genes and their products, sepsis may be regarded as a gene-related disorder and gene therapy may be considered a promising novel therapeutic approach for treatment of sepsis. In this review article, we provide an up-to-date summary of the gene-targeting approaches, which have been developed in animal models of sepsis. Our review sheds light on the molecular basis of sepsis pathology for the development of novel gene therapy approaches and leads to the conclusion that future research efforts may fully take into account gene therapy for the treatment of sepsis.

Translational Advances of Hydrofection by Hydrodynamic Injection

Hydrodynamic gene delivery has proven to be a safe and efficient procedure for gene transfer, able to mediate, in murine model, therapeutic levels of proteins encoded by the transfected gene. In different disease models and targeting distinct organs, it has been demonstrated to revert the pathologic symptoms and signs. The therapeutic potential of hydrofection led different groups to work on the clinical translation of the procedure. In order to prevent the hemodynamic side effects derived from the rapid injection of a large volume, the conditions had to be moderated to make them compatible with its use in mid-size animal models such as rat, hamster and rabbit and large animals as dog, pig and primates. Despite the different approaches performed to adapt the conditions of gene delivery, the results obtained in any of these mid-size and large animals have been poorer than those obtained in murine model. Among these different strategies to reduce the volume employed, the most effective one has been to exclude the vasculature of the target organ and inject the solution directly. This procedure has permitted, by catheterization and surgical procedures in large animals, achieving protein expression levels in tissue close to those achieved in gold standard models. These promising results and the possibility of employing these strategies to transfer gene constructs able to edit genes, such as CRISPR, have renewed the clinical interest of this procedure of gene transfer. In order to translate the hydrodynamic gene delivery to human use, it is demanding the standardization of the procedure conditions and the molecular parameters of evaluation in order to be able to compare the results and establish a homogeneous manner of expressing the data obtained, as ‘classic’ drugs.

Apoptosis-induced lymphopenia in sepsis and other severe injuries

Sepsis and other acute injuries such as severe trauma, extensive burns, or major surgeries, are usually followed by a period of marked immunosuppression. In particular, while lymphocytes play a pivotal role in immune response, their functions and numbers are profoundly altered after severe injuries. Apoptosis plays a central role in this process by affecting immune response at various levels. Indeed, apoptosis-induced lymphopenia duration and depth have been associated with higher risk of infection and mortality in various clinical settings. Therapies modulating apoptosis represent an interesting approach to restore immune competence after acute injury, although their use in clinical practice still presents several limitations. After briefly describing the apoptosis process in physiology and during severe injuries, we will explore the immunological consequences of injury-induced lymphocyte apoptosis, and describe associations with clinically relevant outcomes in patients. Therapeutic perspectives targeting apoptosis will also be discussed.

Higher serum caspase-cleaved cytokeratin-18 levels during the first week of sepsis diagnosis in non-survivor patients

Background:

Caspase-cleaved cytokeratin (CCCK)-18 is a protein released into the blood during apoptosis. Higher circulating CCCK-18 concentrations have been found in non-survivor than in survivor septic patients at moment of sepsis diagnosis. The following questions arise now: (1) How are serum CCCK-18 levels during the first week of sepsis? (2) Is there an association between sepsis severity and mortality and serum CCCK-18 levels during the first week? The aims of this study were to answer these questions.

Methods:

Multicenter study with 321 severe septic patients from eight Spanish intensive care units. We determined serum concentration of CCCK-18, tumor necrosis factor (TNF)-α, and interleukin (IL)-10 during the first week. Our end-point study was 30-day mortality.

Results:

Non-survivor (n=108) compared to survivor patients (n=213) showed higher serum CCCK-18 levels at days 1, 4 and 8 (p<0.001). ROC curve analyses showed that serum CCCK-18 levels at days 1 (AUC=0.77; 95% CI=0.72–0.82), 4 (AUC=0.81; 95% CI=0.76–0.85) and 8 (AUC=0.83; 95% CI=0.78–0.88) could predict mortality at 30 days (p<0.001). Logistic regression analyses showed that serum CCCK-18 levels at days 1 (OR=4.367; 95% CI=2.491–7.659), 4 (OR=10.137; 95% CI=4.741–21.678) and 8 (OR=8.781; 95% CI=3.626–21.268) were associated with 30-day mortality (p<0.001). We found a positive correlation between CCCK-18, SOFA, and lactic acid at days 1, 4 and 8.

Conclusions:

Non-survivor septic patients showed persistently during the first week higher serum CCCK-18 levels than survivor patients, and there is an association between sepsis severity and mortality and serum CCCK-18 levels during the first week.

The role and regulation of apoptosis in sepsis

Today, sepsis continues to be a growing problem in the critically ill patient population. A number of laboratories have been interested in understanding how changes in immune cell apoptosis during sepsis appear to contribute to septic morbidity. Consistently, it has been found that immune cell apoptosis is altered in a variety of tissue sites and cell populations both in experimental animals and humans. While divergent mediators, such as steroids and TNF, contribute to some of these apoptotic changes, their effects are tissue and cell population selective. Inhibition of FasL—Fas signaling (by either FasL gene deficiency, in vivo gene silencing [siRNA] or with FasL binding protein) protects septic mice from the onset of marked apoptosis and the morbidity/mortality seen in sepsis. Further, this extrinsic apoptosis response appears to utilize aspects of the Bid-induced mitochondrial pathway. This is in keeping with the findings that pan-specific caspase inhibition or the overexpression of Bcl-2 also protect these animals from the sequellae of sepsis.

Immunotherapy of Sepsis: Blind Alley or Call for Personalized Assessment?

Sepsis is the most frequent cause of death in noncoronary intensive care units. In the past 10 years, progress has been made in the early identification of septic patients and their treatment. These improvements in support and therapy mean that mortality is gradually decreasing, however, the rate of death from sepsis remains unacceptably high. Immunotherapy is not currently part of the routine treatment of sepsis. Despite experimental successes, the administration of agents to block the effect of sepsis mediators failed to show evidence for improved outcome in a multitude of clinical trials. The following survey summarizes the current knowledge and results of clinical trials on the immunotherapy of sepsis and describes the limitations of our knowledge of the pathogenesis of sepsis. Administration of immunomodulatory drugs should be linked to the current immune status assessed by both clinical and molecular patterns. Thus, a careful daily review of the patient's immune status needs to be introduced into routine clinical practice giving the opportunity for effective and tailored use of immunomodulatory therapy.

Role of cellular events in the pathophysiology of sepsis

INTRODUCTION

Sepsis is a dysregulated host immune response due to an uncontrolled infection. It is a leading cause of mortality in adult intensive care units globally. When the host immune response induced against a local infection fails to contain it locally, it progresses to sepsis, severe sepsis, septic shock and death.

METHOD

Literature survey was performed on the roles of different innate and adaptive immune cells in the development and progression of sepsis. Additionally, the effects of septic changes on reprogramming of different immune cells were also summarized to prepare the manuscript.

FINDINGS

Scientific evidences to date suggest that the loss of balance between inflammatory and anti-inflammatory responses results in reprogramming of immune cell activities that lead to irreversible tissue damaging events and multi-organ failure during sepsis. Many surface receptors expressed on immune cells at various stages of sepsis have been suggested as biomarkers for sepsis diagnosis. Various immunomodulatory therapeutics, which could improve the functions of immune cells during sepsis, were shown to restore immunological homeostasis and improve survival in animal models of sepsis.

CONCLUSION

In-depth and comprehensive knowledge on the immune cell activities and their correlation with severity of sepsis will help clinicians and scientists to design effective immunomodulatory therapeutics for treating sepsis.

Role of Mitochondrial DNA in Septic AKI via Toll-Like Receptor 9

Toll-like receptor 9 (TLR9) contributes to the development of polymicrobial septic AKI. However, the mechanisms that activate the TLR9 pathway and cause kidney injury during sepsis remain unknown. To determine the role of mitochondrial DNA (mtDNA) in TLR9-associated septic AKI, we established a cecal ligation and puncture (CLP) model of sepsis in wild-type (WT) and Tlr9-knockout (Tlr9KO) mice. We evaluated systemic circulation and peritoneal cavity dynamics and immune response and tubular mitochondrial dysfunction to determine upstream and downstream effects on the TLR9 pathway, respectively. CLP increased mtDNA levels in the plasma and peritoneal cavity of WT and Tlr9KO mice in the early phase, but the increase in the peritoneal cavity was significantly higher in Tlr9KO mice than in WT mice. Concomitantly, leukocyte migration to the peritoneal cavity increased, and plasma cytokine production and splenic apoptosis decreased in Tlr9KO mice compared with WT mice. Furthermore, CLP-generated renal mitochondrial oxidative stress and mitochondrial vacuolization in the proximal tubules in the early phase were reversed in Tlr9KO mice. To elucidate the effects of mtDNA on immune response and kidney injury, we intravenously injected mice with mitochondrial debris (MTD), including substantial amounts of mtDNA. MTD caused an immune response similar to that induced by CLP, including upregulated levels of plasma IL-12, splenic apoptosis, and mitochondrial injury, but this effect was attenuated by Tlr9KO. Moreover, MTD-induced renal mitochondrial injury was abolished by DNase pretreatment. These findings suggest that mtDNA activates TLR9 and contributes to cytokine production, splenic apoptosis, and kidney injury during polymicrobial sepsis.

Clinical application: Restoration of immune homeostasis by autophagy as a potential therapeutic target in sepsis

Sepsis-induced lymphocyte and dendritic cell apoptosis contributes to immunosuppression, resulting in an inability to eradicate the primary infection and a propensity to acquire secondary infections. However, the inhibition of apoptosis may produce unexpected and undesirable consequences. Another cellular process, autophagy, is also activated in immune cells. There is increasing evidence to suggest that autophagy confers a protective effect in sepsis. The protective mechanisms underlying this effect include limiting apoptotic cell death and maintaining cellular homeostasis. Therefore, understanding the regulation of immune cell autophagy and apoptosis may provide insight into novel therapeutic strategies. The present review examined potential novel therapeutic strategies aimed at restoring immune homeostasis by inducing autophagy. The restoration of balance between apoptosis and autophagy may be a novel approach for improving sepsis-induced immunosuppression and decreasing susceptibility to sepsis.

Imaging Lymphoid Cell Death In Vivo During Polymicrobial Sepsis

OBJECTIVES

Cell death in lymphatic organs, such as the spleen, is in part responsible for immunosuppression and contributes to mortality during sepsis. An early and noninvasive detection of lymphoid cell death could thus have significant clinical implications. Here, we tested in vivo imaging of lymphoid cell death using a near-infrared annexin V (AV-750).

DESIGN

Animal study.

SETTING

Laboratory investigation.

SUBJECTS

C57BL/6J wild-type and toll-like receptor 3 knockout mice.

INTERVENTIONS

Mild and severe polymicrobial sepsis was induced with cecum ligation and puncture. Serum cytokines and acute kidney injury markers were tested by immunoassay and quantitative reverse transcription-polymerase chain reaction, respectively. Sepsis-induced lymphoid cell death was detected by fluorescent AV-750 accumulation in the thorax and abdomen (in vivo), in isolated organs (ex vivo), and in isolated cells (flow cytometry). Caspase-3 cleavage/activity and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining were tested for apoptosis.

MEASUREMENTS AND MAIN RESULTS

Severe sepsis induced marked apoptosis in the thymus, spleen, and liver as demonstrated by cleaved caspase-3 and an increase in caspase-3 activity and terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells. A significant increase in fluorescent AV-750 signal was seen in the thoracic and upper abdominal fields and associated with the severity of sepsis. The in vivo thoracic and abdominal AV-750 fluorescent signal was attributed to the thymus, liver, and spleen as determined by ex vivo imaging and highly correlated with the levels of cell death in thymocytes and splenocytes, respectively, as measured by flow cytometry. Compared with wild-type septic mice, toll-like receptor 3 septic mice had attenuated abdominal AV-750 fluorescent signal, reduced ex vivo fluorescence in the spleen, and decreased splenocyte cell death.

CONCLUSIONS

In vivo AV-750 fluorescent imaging provides spatially resolved and organ-specific detection of lymphoid cell death during polymicrobial sepsis. The AV-750 fluorescent intensity in the thoracic and abdominal fields is associated with sepsis severity and well correlated with sepsis-induced cell death in the thymus and spleen, respectively.

Genipin attenuates sepsis-induced immunosuppression through inhibition of T lymphocyte apoptosis

Sepsis, a systemic inflammatory response to infection, initiates a complex immune response consisting of an early hyperinflammatory response and a subsequent hypoinflammatory response that impairs the removal of infectious organisms. The importance of sepsis-induced immunosuppression and its contribution to mortality has recently emerged. Apoptotic depletion of T lymphocytes is a critical cause of immunosuppression in the late phase of sepsis. Genipin is a major active compound of gardenia fruit that has anti-apoptotic and anti-microbial properties. This study investigated the mechanisms of action of genipin on immunosuppression in the late phase of sepsis. Mice received genipin (1, 2.5 and 5mg/kg, i.v.) at 0 (immediately) and 24h after cecal ligation and puncture (CLP). Twenty-six hours after CLP, the spleen and blood were collected. Genipin improved the survival rate compared to controls. CLP increased the levels of FADD, caspase-8 and caspase-3 protein expression, which were attenuated by genipin. Genipin increased the level of anti-apoptotic B-cell lymphoma-2 protein expression, while it decreased the level of pro-apoptotic phosphorylated-Bim protein expression in CLP. CLP decreased the CD4(+) and CD8(+) T cell population, while it increased the regulatory T cell (Treg) population and the level of cytotoxic T lymphocyte-associated antigen 4 protein expression on Treg. These changes were attenuated by genipin. The splenic levels of interferon-γ and interleukin (IL)-2 were reduced, while the levels of IL-4 and IL-10 increased after CLP. Genipin attenuated these alterations. These findings suggest that genipin reduces immunosuppression by inhibiting T lymphocyte apoptosis in the late phase of sepsis.

Inhibition of Toll-like receptor 9 attenuates sepsis-induced mortality through suppressing excessive inflammatory response

Sepsis, a major clinical problem with high morbidity and mortality, is caused by overwhelming systemic host-inflammatory response. Toll-like receptors (TLRs) play a fundamental role in induction of hyperinflammation and tissue damage in sepsis. In this study, we demonstrate a protective role of TLR9 inhibition against the dysregulated inflammatory response and tissue injury in sepsis. TLR9 deficiency decreased the mortality of mice following cecal ligation and puncture (CLP)-induced sepsis. TLR9 knockout mice showed dampened p38 activation and augmented Akt phosphorylation in the spleen, lung and liver. In addition, TLR9 deficiency decreased the levels of inflammatory cytokines and attenuated splenic apoptosis after CLP. These results indicate that TLR9 inhibition might offer a novel therapeutic strategy for the management of sepsis.

Chitosan/siRNA nanoparticles targeting cyclooxygenase type 2 attenuate unilateral ureteral obstruction-induced kidney injury in mice

Cyclooxygenase type 2 (COX-2) plays a predominant role in the progression of kidney injury in obstructive nephropathy. The aim of this study was to test the efficacy of chitosan/small interfering RNA (siRNA) nanoparticles to knockdown COX-2 specifically in macrophages to prevent kidney injury induced by unilateral ureteral obstruction (UUO). Using optical imaging techniques and confocal microscopy, we demonstrated that chitosan/siRNA nanoparticles accumulated in macrophages in the obstructed kidney. Consistent with the imaging data, the obstructed kidney contained a higher amount of siRNA and macrophages. Chitosan-formulated siRNA against COX-2 was evaluated on RAW macrophages demonstrating reduced COX-2 expression and activity after LPS stimulation. Injection of COX-2 chitosan/siRNA nanoparticles in mice subjected to three-day UUO diminished the UUO-induced COX-2 expression. Likewise, macrophages in the obstructed kidney had reduced COX-2 immunoreactivity, and histological examination showed lesser tubular damage in COX-2 siRNA-treated UUO mice. Parenchymal inflammation, assessed by tumor necrosis factor-alpha (TNF-α) and interleukin 6 mRNA expression, was attenuated by COX-2 siRNA. Furthermore, treatment with COX-2 siRNA reduced heme oxygenase-1 and cleaved caspase-3 in UUO mice, indicating lesser oxidative stress and apoptosis. Our results demonstrate a novel strategy to prevent UUO-induced kidney damage by using chitosan/siRNA nanoparticles to knockdown COX-2 specifically in macrophages.

Immunomodulatory therapies for acute pancreatitis

It is currently difficult for conventional treatments of acute pancreatitis (AP), which primarily consist of anti-inflammatory therapies, to prevent the progression of AP or to improve its outcome. This may be because the occurrence and progression of AP, which involves various inflammatory cells and cytokines, includes a series of complex immune events. Considering the complex immune system alterations during the course of AP, it is necessary to monitor the indicators related to immune cells and inflammatory mediators and to develop more individualized interventions for AP patients using immunomodulatory therapy. This review discusses the recent advances in immunomodulatory therapies. It has been suggested that overactive inflammatory responses should be inhibited and excessive immunosuppression should be avoided in the early stages of AP. The optimal duration of anti-inflammatory therapy may be shorter than previously expected (< 24 h), and appropriate immunostimulatory therapies should be administered during the period from the 3^rd d to the 14^th d in the course of AP. A combination therapy of anti-inflammatory and immune-stimulating drugs would hopefully constitute an alternative to anti-inflammatory drug monotherapy. Additionally, the detection of the genotypes of critical inflammatory mediators may be useful for screening populations of AP patients at high risk of severe infections to enable the administration of early interventions to improve their prognosis.

Revisiting caspases in sepsis

Sepsis is a life-threatening illness that occurs due to an abnormal host immune network which extends through the initial widespread and overwhelming inflammation, and culminates at the late stage of immunosupression. Recently, interest has been shifted toward therapies aimed at reversing the accompanying periods of immune suppression. Studies in experimental animals and critically ill patients have demonstrated that increased apoptosis of lymphoid organs and some parenchymal tissues contributes to this immune suppression, anergy and organ dysfunction. Immediate to the discoveries of the intracellular proteases, caspases for the induction of apoptosis and inflammation, and their striking roles in sepsis have been focused elaborately in a number of original and review articles. Here we revisited the different aspects of caspases in terms of apoptosis, pyroptosis, necroptosis and inflammation and focused their links in sepsis by reviewing several recent findings. In addition, we have documented striking perspectives which not only rewrite the pathophysiology, but also modernize our understanding for developing novel therapeutics against sepsis.

Remedial applications of silencing ribonucleic acids and modalities for its delivery to the kidneys--a review

BACKGROUND

The Kidney has been the target organ for the delivery of silencing ribonucleic acids (silencing RNA) administered systemically in comparison to other body tissues.

MATERIALS AND METHOD

In this review, we discussed different approaches made to delivering proteins to the kidneys in different conditions like normal and pathological defects. Data from clinical experiments have been used to discuss and support the administration of silencing RNA for the treatment of kidney diseases.

RESULTS

Results were achieved using the available genome wide RNA libraries.

CONCLUSION

The research results are helpful in application to 3D and conventional models to find the involvement of signal pathways in kidney diseases.

Serum levels of caspase-cleaved cytokeratin-18 and mortality are associated in severe septic patients: pilot study

OBJECTIVE

Apoptosis is increased in sepsis. Cytokeratin 18 (CK-18), a protein of the intermediate filament group present in most epithelial and parenchymal cells, is cleaved by the action of caspases and released into the blood as caspase-cleaved CK (CCCK)-18 during apoptosis. Circulating levels of CCCK-18 have scarcely been explored in septic patients. In one study with 101 severe septic patients, the authors reported higher serum CCCK-18 levels in non-survivors than in survivors; however, the sample size was too small to demonstrate an association between serum CCCK-18 levels and early mortality and whether they could be used as a biomarker to predict outcomes in septic patients. Thus, these were the objectives of this study with a large series of patients.

METHODS

We performed a prospective, multicenter, observational study in six Spanish Intensive Care Units with 224 severe septic patients. Blood samples were collected at the time that severe sepsis was diagnosed to determine serum levels of CCCK-18, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-10. The end point was 30-day mortality.

RESULTS

Non-surviving patients (n = 80) showed higher serum CCCK-18 levels (P<0.001) than survivors (n = 144). Multiple logistic regression analysis showed that serum CCCK-18 levels>391 u/L were associated with 30-day survival (Odds ratio = 2.687; 95% confidence interval = 1.449-4.983; P = 0.002), controlling for SOFA score, serum lactic acid levels and age. Kaplan-Meier survival analysis showed that the risk of death in septic patients with serum CCCK-18 levels >391 u/L was higher than in patients with lower values (Hazard Ratio = 3.1; 95% CI = 1.96-4.84; P<0.001). Serum CCCK-18 levels were positively associated with serum levels of IL-6 and lactic acid, and with SOFA and APACHE scores.

CONCLUSIONS

The major novel finding of our study, the largest cohort of septic patients providing data on circulating CCCK-18 levels, was that serum CCCK-18 levels are associated with mortality in severe septic patients.

Pilot Investigation of the Association Between Serum Stress Neuropeptide Levels and Lymphocyte Expression of Fas and Fas Ligand in Critical Illness

Introduction:

In critical illness, apoptotic loss of immunocytes is associated with immunosuppression.

Aim:

To explore expression of Fas/Fas ligand (FasL) on B and T cells from critically ill patients without sepsis compared to matched controls and associations with disease severity and neuropeptide Y (NPY), cortisol, adrenocorticotropic hormone (ACTH), and prolactin (PRL) levels.

Methods:

Repeated-measures correlational design with 36 critically ill patients (14-day follow-up) and 36 controls. Disease severity was assessed using the Multiple Organ Dysfunction Score (MODS) and Multi Organ Failure scale. Fas/FasL values were standardized for viable cell counts. An enzyme-linked immunosorbent assay (NPY) and electrochemiluminescence immunoassay (cortisol, ACTH, and PRL) were employed.

Results:

Fas and FasL expression on T-helper ( p < .0001–.03) and T-cytotoxic cells ( p < .0001–.002) and Fas expression on B cells ( p < .0001–.03) were higher in patients. MODS severity was associated with FasL expression on cytotoxic T cells ( r = .752–.902, p = .023–.037). There was an inverse association between Day 1 NPY levels and Fas expression on T-helper cells ( r = −.447, p = .019). On the day of maximum severity, we report for the first time an inverse association between NPY levels and FasL expression on helper ( r = −.733, p = .016) and cytotoxic ( r = −.862, p = .003) T cells. Cortisol levels were positively associated with counts of FasL-positive helper ( r = .828) and cytotoxic ( r = .544, p < .05) T cells.

Conclusion:

Results suggest a potential role for stress neuropeptides in lymphocyte survival and activation in critical illness.

Receptor-interacting protein kinase 3 deficiency inhibits immune cell infiltration and attenuates organ injury in sepsis

INTRODUCTION

Sepsis is defined as a systemic hyper-inflammatory immune response, with a subsequent immune-suppressive phase, which leads to multiple organ dysfunction and late lethality. Receptor-interacting protein kinase 3 (RIPK3)-dependent necrosis is implicated in driving tumor necrosis factor alpha (TNF-α)- and sepsis-induced mortality in mice. However, it is unknown if RIPK3 deficiency has any impact on immune cell trafficking, which contributes to organ damage in sepsis.

METHODS

To study this, male wild-type (WT) and RIPK3-deficient (Ripk3-/-) mice on C57BL/6 background were subjected to sham operation or cecal ligation and puncture (CLP)-induced sepsis. Blood and tissue samples were collected 20 hours post-CLP for various measurements.

RESULTS

In our severe sepsis model, the mean survival time of Ripk3-/- mice was significantly extended to 68 hours compared to 41 hours for WT mice. Ripk3-/- mice had significantly decreased plasma levels of TNF-α and IL-6 and organ injury markers compared to WT mice post-CLP. In the lungs, Ripk3-/- mice preserved better integrity of microscopic structure with reduced apoptosis, and decreased levels of IL-6, macrophage inflammatory protein (MIP)-2 and keratinocyte-derived chemokine (KC), compared to WT. In the liver, the levels of MIP-1, MIP-2 and KC were also decreased in septic Ripk3-/- mice. Particularly, the total number of neutrophils in the lungs and liver of Ripk3-/- mice decreased by 59.9% and 66.7%, respectively, compared to WT mice post-CLP. In addition, the number of natural killer (NK) and CD8T cells in the liver decreased by 64.8% and 53.4%, respectively, in Ripk3-/- mice compared to WT mice post-sepsis.

CONCLUSIONS

Our data suggest that RIPK3 deficiency modestly protected from CLP-induced severe sepsis and altered the immune cell trafficking in an organ-specific manner attenuating organ injury. Thus, RIPK3 acts as a detrimental factor in contributing to the organ deterioration in sepsis.

Fab'-bearing siRNA TNFα-loaded nanoparticles targeted to colonic macrophages offer an effective therapy for experimental colitis

Patients suffering from inflammatory bowel disease (IBD) are currently treated by systemic drugs that can have significant side effects. Thus, it would be highly desirable to target TNFα siRNA (a therapeutic molecule) to the inflamed tissue. Here, we demonstrate that TNFα siRNA can be efficiently loaded into nanoparticles (NPs) made of poly (lactic acid) poly (ethylene glycol) block copolymer (PLA-PEG), and that grafting of the Fab' portion of the F4/80 Ab (Fab'-bearing) onto the NP surface via maleimide/thiol group-mediated covalent bonding improves the macrophage (MP)-targeting kinetics of the NPs to RAW264.7 cells in vitro. Direct binding was shown between MPs and the Fab'-bearing NPs. Next, we orally administered hydrogel (chitosan/alginate)-encapsulated Fab'-bearing TNFα-siRNA-loaded NPs to 3% dextran sodium sulfate (DSS)-treated mice and investigated the therapeutic effect on colitis. In vivo, the release of TNFα-siRNA-loaded NPs into the mouse colon attenuated colitis more efficiently when the NPs were covered with Fab'-bearing, compared to uncovered NPs. All DSS-induced parameters of colonic inflammation (e.g., weight loss, myeloperoxidase activity, and Iκbα accumulation) were more attenuated Fab'-bearing NPs loaded with TNFα siRNA than without the Fab'-bearing. Grafting the Fab'-bearing onto the NPs improved the kinetics of endocytosis as well as the MP-targeting ability, as indicated by flow cytometry. Collectively, our results show that Fab'-bearing PLA-PEG NPs are powerful and efficient nanosized tools for delivering siRNAs into colonic macrophages.

Activated neutrophils induce epithelial cell apoptosis through oxidant-dependent tyrosine dephosphorylation of caspase-8

Activated neutrophils can injure host cells through direct effects of oxidants on membrane phospholipids, but an ability to induce apoptotic cell death has not previously been reported. We show that neutrophils activated in vivo in patients who have sustained multiple trauma or in vitro by exposure to bacterial lipopolysaccharide promote epithelial cell apoptosis through SHP-1-mediated dephosphorylation of epithelial cell caspase-8. Epithelial cell apoptosis induced by circulating neutrophils from patients who had sustained serious injury depended on the generation of neutrophil-derived reactive oxygen intermediates and was blocked by inhibition of NADPH oxidase or restoration of intracellular glutathione. Caspase-8 was constitutively tyrosine phosphorylated in a panel of resting epithelial cells, but underwent SHP-1-dependent dephosphorylation in response to hydrogen peroxide, activated neutrophils, or inhibition of Src kinases. Cells transfected with a mutant caspase-8 in which tyrosine residues at Tyr397 or Tyr465 are replaced by nonphosphorylatable phenylalanine underwent accelerated apoptosis, whereas either mutation of these residues to phosphomimetic glutamic acid or transfection with the Src kinases Lyn or c-Src inhibited hydrogen peroxide-induced apoptosis. Exposure to either hydrogen peroxide or lipopolysaccharide-stimulated neutrophils increased phosphorylation and activity of the phosphatase SHP-1, increased activity of caspases 8 and 3, and accelerated epithelial cell apoptosis. These observations reveal a novel mechanism for neutrophil-mediated tissue injury through oxidant-dependent, SHP-1-mediated dephosphorylation of caspase-8 resulting in enhanced epithelial cell apoptosis.

The new normal: immunomodulatory agents against sepsis immune suppression

Sepsis is the leading cause of death among critically ill patients in intensive care units, and treatment options are limited. Therapies developed against the proinflammatory stage have failed clinically; therefore, new approaches that target the host immune response in sepsis are necessary. Increasing evidence suggests that a major pathophysiological event in sepsis is immune suppression, often resulting in secondary fungal, bacterial, or viral infections. Recent studies from animal sepsis models and patient samples suggest that cytokines such as interleukin-7 (IL-7), IL-15, granulocyte macrophage colony-stimulating factor (GM-CSF), as well as co-inhibitory molecule blockade, such as anti-programmed cell death receptor-1 (anti-PD-1) and anti-B and T lymphocyte attenuator (anti-BTLA), may have utility in alleviating the clinical morbidity associated with sustained sepsis. This review discusses some of these novel immunomodulatory agents and evaluates their potential use as therapeutics.