Endothelial dysfunction is a potential contributor to multiple organ failure and mortality in aged mice subjected to septic shock: preclinical studies in a murine model of cecal ligation and puncture

Tiny Guides, Big Impact: Focus on the Opportunities and Challenges of miR-Based Treatments for ARDS

Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and increased membrane permeability, which represents the leading cause of mortality in ICUs. Mechanical ventilation strategies are at the forefront of supportive approaches for ARDS. Recently, an increasing understanding of RNA biology, function, and regulation, as well as the success of RNA vaccines, has spurred enthusiasm for the emergence of novel RNA-based therapeutics. The most common types of RNA seen in development are silencing (si)RNAs, antisense oligonucleotide therapy (ASO), and messenger (m)RNAs that collectively account for 80% of the RNA therapeutics pipeline. These three RNA platforms are the most mature, with approved products and demonstrated commercial success. Most recently, miRNAs have emerged as pivotal regulators of gene expression. Their dysregulation in various clinical conditions offers insights into ARDS pathogenesis and offers the innovative possibility of using microRNAs as targeted therapy. This review synthesizes the current state of the literature to contextualize the therapeutic potential of miRNA modulation. It considers the potential for miR-based therapeutics as a nuanced approach that incorporates the complexity of ARDS pathophysiology and the multifaceted nature of miRNA interactions.

Exploration of the role of oxidative stress-related genes in LPS-induced acute lung injury via bioinformatics and experimental studies

During the progression of acute lung injury (ALI), oxidative stress and inflammatory responses always promote each other. The datasets analyzed in this research were acquired from the Gene Expression Omnibus (GEO) database. The Weighted Gene Co-expression Network Analysis (WGCNA) and limma package were used to obtain the ALI-related genes (ALIRGs) and differentially expressed genes (DEGs), respectively. In total, two biological markers (Gch1 and Tnfaip3) related to oxidative stress were identified by machine learning algorithms, Receiver Operator Characteristic (ROC), and differential expression analyses. The area under the curve (AUC) value of biological markers was greater than 0.9, indicating an excellent power to distinguish between ALI and control groups. Moreover, 15 differential immune cells were selected between the ALI and control samples, and they were correlated to biological markers. The transcription factor (TF)-microRNA (miRNA)-Target network was constructed to explore the potential regulatory mechanisms. Finally, based on the quantitative reverse transcription polymerase chain reaction (qRT-PCR), the expression of Gch1 and Tnfaip3 was significantly higher in ALI lung tissue than in healthy controls. In conclusion, the differences in expression profiles between ALI and normal controls were found, and two biological markers were identified, providing a research basis for further understanding the pathogenesis of ALI.

Novel transdermal curcumin therapeutic preserves endothelial barrier function in a high-dose LPS rat model

Sepsis is a devastating complication of infection and injury that, through widespread endothelial dysfunction, can cause perfusion deficits and multi-organ failure. To address the recognised need for therapeutics targetting the endothelial barrier, a topical formulation (CUR; VASCEPTOR™; Vascarta Inc, Summit, NJ) was developed to transdermally deliver bio-active concentrations of curcumin-an anti-inflammatory and nitric oxide promoter. Male, Sprague Dawley rats were treated daily with lipopolysaccharide (LPS, 10 mg/kg, IP) to induce endotoxemia, and topical applications of Vehicle Control (LPS + VC; N = 7) or Curcumin (LPS + CUR; N = 7). A third group received neither LPS nor treatment (No-LPS; N = 8). After 72 h, animals were surgically prepared for measurements of physiology and endothelial dysfunction in the exteriorised spinotrapezius muscle through the extravasation of 67 kDa TRITC-BSA (albumin) and 500 kDa FITC-dextran (dextran). At 72 h, LPS + VC saw weight loss, and increases to pulse pressure, lactate, pCO₂, CXCL5 (vs No-LPS) and IL-6 (vs 0 h; p < 0.05). LPS + CUR was similar to No-LPS, but with hypotension. Phenylephrine response was increased in LPS + CUR. Regarding endothelial function, LPS + CUR albumin and dextran extravasation were significantly reduced versus LPS + VC suggesting that Curcumin mitigated endotoxemic endothelial dysfunction. The speculated mechanisms are nitric oxide modulation of the endothelium and/or an indirect anti-inflammatory effect.

Organotypic heterogeneity in microvascular endothelial cell responses in sepsis-a molecular treasure trove and pharmacological Gordian knot

In the last decades, it has become evident that endothelial cells (ECs) in the microvasculature play an important role in the pathophysiology of sepsis-associated multiple organ dysfunction syndrome (MODS). Studies on how ECs orchestrate leukocyte recruitment, control microvascular integrity and permeability, and regulate the haemostatic balance have provided a wealth of knowledge and potential molecular targets that could be considered for pharmacological intervention in sepsis. Yet, this information has not been translated into effective treatments. As MODS affects specific vascular beds, (organotypic) endothelial heterogeneity may be an important contributing factor to this lack of success. On the other hand, given the involvement of ECs in sepsis, this heterogeneity could also be leveraged for therapeutic gain to target specific sites of the vasculature given its full accessibility to drugs. In this review, we describe current knowledge that defines heterogeneity of organ-specific microvascular ECs at the molecular level and elaborate on studies that have reported EC responses across organ systems in sepsis patients and animal models of sepsis. We discuss hypothesis-driven, single-molecule studies that have formed the basis of our understanding of endothelial cell engagement in sepsis pathophysiology, and include recent studies employing high-throughput technologies. The latter deliver comprehensive data sets to describe molecular signatures for organotypic ECs that could lead to new hypotheses and form the foundation for rational pharmacological intervention and biomarker panel development. Particularly results from single cell RNA sequencing and spatial transcriptomics studies are eagerly awaited as they are expected to unveil the full spatiotemporal signature of EC responses to sepsis. With increasing awareness of the existence of distinct sepsis subphenotypes, and the need to develop new drug regimen and companion diagnostics, a better understanding of the molecular pathways exploited by ECs in sepsis pathophysiology will be a cornerstone to halt the detrimental processes that lead to MODS.

Revealing the biological mechanism of acupuncture in alleviating excessive inflammatory responses and organ damage in sepsis: a systematic review

Sepsis is a systemic inflammation caused by a maladjusted host response to infection. In severe cases, it can cause multiple organ dysfunction syndrome (MODS) and even endanger life. Acupuncture is widely accepted and applied in the treatment of sepsis, and breakthroughs have been made regarding its mechanism of action in recent years. In this review, we systematically discuss the current clinical applications of acupuncture in the treatment of sepsis and focus on the mechanisms of acupuncture in animal models of systemic inflammation. In clinical research, acupuncture can not only effectively inhibit excessive inflammatory reactions but also improve the immunosuppressive state of patients with sepsis, thus maintaining immune homeostasis. Mechanistically, a change in the acupoint microenvironment is the initial response link for acupuncture to take effect, whereas PROKR2 neurons, high-threshold thin nerve fibres, cannabinoid CB2 receptor (CB2R) activation, and Ca2+ influx are the key material bases. The cholinergic anti-inflammatory pathway of the vagus nervous system, the adrenal dopamine anti-inflammatory pathway, and the sympathetic nervous system are key to the transmission of acupuncture information and the inhibition of systemic inflammation. In MODS, acupuncture protects against septic organ damage by inhibiting excessive inflammatory reactions, resisting oxidative stress, protecting mitochondrial function, and reducing apoptosis and tissue or organ damage.

Aging-associated augmentation of gut microbiome virulence capability drives sepsis severity

Prior research has focused on host factors as mediators of exaggerated sepsis-associated morbidity and mortality in older adults. This focus on the host, however, has failed to identify therapies that improve sepsis outcomes in the elderly. We hypothesized that the increased susceptibility of the aging population to sepsis is not only a function of the host, but also reflects longevity-associated changes in the virulence of gut pathobionts. We utilized two complementary models of gut microbiota-induced experimental sepsis to establish the aged gut microbiome as a key pathophysiologic driver of heightened disease severity. Further murine and human investigations into these polymicrobial bacterial communities demonstrated that age was associated with only subtle shifts in ecological composition, but an overabundance of genomic virulence factors that have functional consequence on host immune evasion.

One Sentence Summary

The severity of sepsis in the aged host is in part mediated by longevity-associated increases in gut microbial virulence.

Association between age and the host response in critically ill patients with sepsis

BACKGROUND

The association of ageing with increased sepsis mortality is well established. Nonetheless, current investigations on the influence of age on host response aberrations are largely limited to plasma cytokine levels while neglecting other pathophysiological sepsis domains like endothelial cell activation and function, and coagulation activation. The primary objective of this study was to gain insight into the association of ageing with aberrations in key host response pathways and blood transcriptomes in sepsis.

METHODS

We analysed the clinical outcome (n = 1952), 16 plasma biomarkers providing insight in deregulation of specific pathophysiological domains (n = 899), and blood leukocyte transcriptomes (n = 488) of sepsis patients stratified according to age decades. Blood transcriptome results were validated in an independent sepsis cohort and compared with healthy individuals.

RESULTS

Older age was associated with increased mortality independent of comorbidities and disease severity. Ageing was associated with lower endothelial cell activation and dysfunction, and similar inflammation and coagulation activation, despite higher disease severity scores. Blood leukocytes of patients ≥ 70 years, compared to patients < 50 years, showed decreased expression of genes involved in cytokine signaling, and innate and adaptive immunity, and increased expression of genes involved in hemostasis and endothelial cell activation. The diminished expression of gene pathways related to innate immunity and cytokine signaling in subjects ≥ 70 years was sepsis-induced, as healthy subjects ≥ 70 years showed enhanced expression of these pathways compared to healthy individuals < 50 years.

CONCLUSIONS

This study provides novel evidence that older age is associated with relatively mitigated sepsis-induced endothelial cell activation and dysfunction, and a blood leukocyte transcriptome signature indicating impaired innate immune and cytokine signaling. These data suggest that age should be considered in patient selection in future sepsis trials targeting the immune system and/or the endothelial cell response.

Pathophysiology of Sepsis and Genesis of Septic Shock: The Critical Role of Mesenchymal Stem Cells (MSCs)

The treatment of sepsis and septic shock remains a major public health issue due to the associated morbidity and mortality. Despite an improvement in the understanding of the physiological and pathological mechanisms underlying its genesis and a growing number of studies exploring an even higher range of targeted therapies, no significant clinical progress has emerged in the past decade. In this context, mesenchymal stem cells (MSCs) appear more and more as an attractive approach for cell therapy both in experimental and clinical models. Pre-clinical data suggest a cornerstone role of these cells and their secretome in the control of the host immune response. Host-derived factors released from infected cells (i.e., alarmins, HMGB1, ATP, DNA) as well as pathogen-associated molecular patterns (e.g., LPS, peptidoglycans) can activate MSCs located in the parenchyma and around vessels to upregulate the expression of cytokines/chemokines and growth factors that influence, respectively, immune cell recruitment and stem cell mobilization. However, the way in which MSCs exert their beneficial effects in terms of survival and control of inflammation in septic states remains unclear. This review presents the interactions identified between MSCs and mediators of immunity and tissue repair in sepsis. We also propose paradigms related to the plausible roles of MSCs in the process of sepsis and septic shock. Finally, we offer a presentation of experimental and clinical studies and open the way to innovative avenues of research involving MSCs from a prognostic, diagnostic, and therapeutic point of view in sepsis.

Plasma syndecan‐1 concentration as a biomarker for endothelial glycocalyx degradation in septic adult horses

BACKGROUND

Limited information is available regarding endothelial glycocalyx degradation during sepsis in horses. Plasma syndecan-1 concentrations are increased in consequence of sepsis in other species and have been useful for prognostication.

OBJECTIVES

To determine whether plasma syndecan-1 levels are increased in adult horses affected with sepsis.

STUDY DESIGN

Retrospective cohort study.

METHODS

Adult horses were assigned to one of three groups based on results of physical and laboratory examinations, clinical diagnosis, and results of previously described SIRS classification: Group 1 horses included healthy, nonseptic horses; Group 2 included horses in which clinical illness was identified but that were not considered to be septic; Group 3 included horses with a clinical diagnosis of sepsis. Plasma syndecan-1 concentration was determined in blood obtained at admission into the hospital for each horse, using an equine specific ELISA. Data were analysed using ANOVA and linear regression (p ≤ 0.05).

RESULTS

One hundred and ninety-one horses were included and divided into three groups. Scores for SIRS were highest for Group 3 horses and lowest in Groups 1 and 2. Plasma syndecan-1 concentrations in Group 3 horses (50.73 ± 84.24 μg/ml; n = 42) were greater than those for Group 1 (15.69 ± 11.28 μg/ml; n = 66) and Group 2 (16.88 ± 15.30 μg/ml; n = 83). There was no difference regarding syndecan concentrations between Groups 1 and 2.

MAIN LIMITATIONS

Retrospective study design, solitary time point of measurement for each patient, and lack of a widely accepted consensus regarding definitive diagnosis of sepsis in adult horses.

CONCLUSIONS

Circulating plasma levels of syndecan-1, a biochemical marker of endothelial glycocalyx damage, are increased in septic adult horses.

SOCS3 limits TNF and endotoxin-induced endothelial dysfunction by blocking a required autocrine interleukin 6 signal in human endothelial cells

Increased circulating levels of soluble interleukin (IL)-6 receptor α (sIL-6Rα) are commonly observed during inflammatory responses, allowing for IL-6 signaling in cells that express the ubiquitous receptor subunit gp130 but not IL-6Rα, such as endothelial cells. Activation of Toll-like receptor (TLR)-4 or the tumor necrosis factor (TNF) receptor leads to NF-κB-dependent increases in endothelial IL-6 expression. Thus, we hypothesize that danger signals may induce autocrine IL-6 signaling within the endothelium via sIL-6Rα-mediated trans-signaling. In support of this hypothesis, we recently demonstrated that conditional deletion in the endothelium of the IL-6 signaling inhibitor SOCS3 leads to rapid mortality in mice challenged with the TLR-4 agonist endotoxin through increases in vascular leakage, thrombosis, leukocyte adhesion, and a type I-like interferon response. Here, we sought to directly test a role for sIL-6Rα in LPS-treated human umbilical vein and dermal blood microvascular endothelial cells. We show that co-treatment with sIL-6Rα dramatically increases the loss of barrier function and the expression of COX2 and tissue factor mRNA levels induced by LPS. This co-treatment led to a strong activation of STAT1 and STAT3 while not affecting LPS-induced activation of p38 and NF-κB signaling. Similar results were obtained when sIL-6Rα was added to a TNF challenge. JAK inhibition by pretreatment with ruxolitinib or by SOCS3 overexpression blunted LPS and sIL-6R synergistic effects, while SOCS3 knockdown further increased the response. Together, these findings demonstrate that IL-6 signaling downstream of NF-kB activation leads to a strong endothelial activation and may explain the acute endotheliopathy observed during critical illness.

The Dipeptidyl Peptidase-4 Inhibitor Linagliptin Ameliorates Endothelial Inflammation and Microvascular Thrombosis in a Sepsis Mouse Model

The pathophysiology of sepsis involves inflammation and hypercoagulability, which lead to microvascular thrombosis and compromised organ perfusion. Dipeptidyl peptidase (DPP)-4 inhibitors, e.g., linagliptin, are commonly used anti-diabetic drugs known to exert anti-inflammatory effects. However, whether these drugs confer an anti-thrombotic effect that preserves organ perfusion in sepsis remains to be investigated. In the present study, human umbilical vein endothelial cells (HUVECs) were treated with linagliptin to examine its anti-inflammatory and anti-thrombotic effects under tumor necrosis factor (TNF)-α treatment. To validate findings from in vitro experiments and provide in vivo evidence for the identified mechanism, a mouse model of lipopolysaccharide (LPS)-induced systemic inflammatory response syndrome was used, and pulmonary microcirculatory thrombosis was measured. In TNF-α-treated HUVECs and LPS-injected mice, linagliptin suppressed expressions of interleukin-1β (IL-1β) and intercellular adhesion molecule 1 (ICAM-1) via a nuclear factor-κB (NF-κB)–dependent pathway. Linagliptin attenuated tissue factor expression via the Akt/endothelial nitric oxide synthase pathway. In LPS-injected mice, linagliptin pretreatment significantly reduced thrombosis in the pulmonary microcirculation. These anti-inflammatory and anti-thrombotic effects were independent of blood glucose level. Together the present results suggest that linagliptin exerts protective effects against endothelial inflammation and microvascular thrombosis in a mouse model of sepsis.

Diagnosis of sepsis with inflammatory biomarkers, cytokines, endothelial functional markers from SIRS patients

BACKGROUND

Sepsis is a life-threatening illness with a challenging diagnosis. Rapid detection is the key to successful treatment of sepsis. To investigate diagnostic value, the plasma protein profiles of inflammatory biomarkers, cytokines, and endothelial functional markers were compared between healthy controls, SIRS, and septic patients.

METHODS

The plasma protein profiles were performed by Luminex Assay in a cohort of 50 SIRS patients, 82 septic patients and 25 healthy controls. Fourteen plasma proteins were analyzed in the same cohort: IL-1β, IL-6, IL-8, IL-10, CCL-2, VEGF, VEGF-C, VEGFR2, CD62E, CD62P, MFG-E8, ICAM-1, TFPI, Urokinase.

RESULT

IL-2R, IL-6, IL-8, IL-10, CCL-2, ICAM-1, and Urokinase were significantly higher in sepsis patients than SIRS patients. VEGF, IL-1β, CD62E, CD62P, MFG-E8, and TFPI have no statistical difference. VEGF-C, VEGFR2 were significantly different in SIRS patients than sepsis patients. Urokinase, ICAM-1, and VEGFR2 were significantly different between sepsis group and SIRS group. The AUCs of Urokinase, ICAM-1, and VEGFR2 and the combination for the diagnosis of sepsis were 0.650, 0.688, 0.643, and 0.741, respectively.

CONCLUSIONS

Most patients have the higher level of several cytokines and developed endothelial cell injury in the initial phase of sepsis, Urokinase, ICAM-1, and VEGFR2 may be useful to evaluate severity and prognosis of sepsis patients.

Renal microvascular endothelial cell responses in sepsis-induced acute kidney injury

Microvascular endothelial cells in the kidney have been a neglected cell type in sepsis-induced acute kidney injury (sepsis-AKI) research; yet, they offer tremendous potential as pharmacological targets. As endothelial cells in distinct cortical microvascular segments are highly heterogeneous, this Review focuses on endothelial cells in their anatomical niche. In animal models of sepsis-AKI, reduced glomerular blood flow has been attributed to inhibition of endothelial nitric oxide synthase activation in arterioles and glomeruli, whereas decreased cortex peritubular capillary perfusion is associated with epithelial redox stress. Elevated systemic levels of vascular endothelial growth factor, reduced levels of circulating sphingosine 1-phosphate and loss of components of the glycocalyx from glomerular endothelial cells lead to increased microvascular permeability. Although coagulation disbalance occurs in all microvascular segments, the molecules involved differ between segments. Induction of the expression of adhesion molecules and leukocyte recruitment also occurs in a heterogeneous manner. Evidence of similar endothelial cell responses has been found in kidney and blood samples from patients with sepsis. Comprehensive studies are needed to investigate the relationships between segment-specific changes in the microvasculature and kidney function loss in sepsis-AKI. The application of omics technologies to kidney tissues from animals and patients will be key in identifying these relationships and in developing novel therapeutics for sepsis.

Mesenchymal stromal (stem) cell therapy modulates miR-193b-5p expression to attenuate sepsis-induced acute lung injury

Although mesenchymal stromal (stem) cell (MSC) administration attenuates sepsis-induced lung injury in pre-clinical models, the mechanism(s) of action and host immune system contributions to its therapeutic effects remain elusive. We show that treatment with MSCs decreased expression of host-derived microRNA (miR)-193b-5p and increased expression of its target gene, the tight junctional protein occludin (Ocln), in lungs from septic mice. Mutating the Ocln 3' untranslated region miR-193b-5p binding sequence impaired binding to Ocln mRNA. Inhibition of miR-193b-5p in human primary pulmonary microvascular endothelial cells prevents tumour necrosis factor (TNF)-induced decrease in Ocln gene and protein expression and loss of barrier function. MSC-conditioned media mitigated TNF-induced miR-193b-5p upregulation and Ocln downregulation in vitro When administered in vivo, MSC-conditioned media recapitulated the effects of MSC administration on pulmonary miR-193b-5p and Ocln expression. MiR-193b-deficient mice were resistant to pulmonary inflammation and injury induced by lipopolysaccharide (LPS) instillation. Silencing of Ocln in miR-193b-deficient mice partially recovered the susceptibility to LPS-induced lung injury. In vivo inhibition of miR-193b-5p protected mice from endotoxin-induced lung injury. Finally, the clinical significance of these results was supported by the finding of increased miR-193b-5p expression levels in lung autopsy samples from acute respiratory distress syndrome patients who died with diffuse alveolar damage.

Cell penetrating peptides coupled to an endothelial nitric oxide synthase sequence alter endothelial permeability

Delivery of cargo to cells through the use of cell-penetrating peptide (CPP) sequences is an area of rich investigation for targeted therapeutics. Specific to the endothelium, the layer of cells that cover every blood vessel in the body, the loss or alteration of a key enzyme, endothelial nitric oxide synthase (eNOS), is known to contribute to endothelial health during severe, infectious challenge. While the beneficial effects of eNOS are often thought to be mediated through the generation of nitric oxide, some protection is theorized to be through eNOS binding to regulatory pathways via a pentabasic RRKRK motif. We hypothesized that delivery of the eNOS-RRKRK peptide sequence using common CPPs would allow protection against gram-negative lipopolysaccharide (LPS). Combination of the eNOS-RRKRK sequence to the CPP antennapedia (AP) reduced the impact of LPS-induced permeability in cultured human microvascular endothelial cells (HMVECs) as measured by transendothelial electrical resistance (TEER). There was also a modest reduction in cytokine production, however it was observed that AP alone significantly impaired LPS-induced endothelial permeability and cytokine production. In comparison, the CPP trans-activator of transcription (TAT) did not significantly alter endothelial inflammation by itself. When TAT was coupled to the eNOS-RRKRK sequence, protection against LPS-induced permeability was still demonstrated, however cytokine production was not reduced. These data demonstrate that the RRKRK sequence of eNOS can offer some NO-independent protection against LPS-mediated endothelial inflammation, however the degree of protection is highly dependent on the type of CPP utilized for cargo delivery.

Modulation of oxidative and nitrosative stress attenuates microvascular hyperpermeability in ovine model of Pseudomonas aeruginosa sepsis

In sepsis, microvascular hyperpermeability caused by oxidative/nitrosative stress (O&NS) plays an important role in tissue edema leading to multi-organ dysfunctions and increased mortality. We hypothesized that a novel compound R-107, a modulator of O&NS, effectively ameliorates the severity of microvascular hyperpermeability and preserves multi-organ function in ovine sepsis model. Sepsis was induced in twenty-two adult female Merino sheep by intravenous infusion of Pseudomonas aeruginosa (PA) (1 × 10¹⁰ CFUs). The animals were allocated into: 1) Control (n = 13): intramuscular injection (IM) of saline; and 2) Treatment (n = 9): IM of 50 mg/kg R-107. The treatment was given after the PA injection, and monitored for 24-h. R-107 treatment significantly reduced fluid requirement (15-24 h, P < 0.05), net fluid balance (9-24 h, P < 0.05), and water content in lung/heart/kidney (P = 0.02/0.04/0.01) compared to control. R-107 treatment significantly decreased lung injury score/modified sheep SOFA score at 24-h (P = 0.01/0.04), significantly lowered arterial lactate (21-24 h, P < 0.05), shed syndecan-1 (3-6 h, P < 0.05), interleukin-6 (6-12 h, P < 0.05) levels in plasma, and significantly attenuated lung tissue 3-nitrotyrosine and vascular endothelial growth factor-A expressions (P = 0.03/0.002) compared to control. There was no adverse effect in R-107 treatment. In conclusion, modulation of O&NS by R-107 reduced hyperpermeability markers and improved multi-organ function.

Aged IRF3-KO Mice are Protected from Sepsis

Purpose

Sepsis is a leading cause of hospital admissions and deaths. Older adults (>65 years) are particularly susceptible to sepsis and experience higher morbidity and mortality rates than younger people. We previously showed that interferon regulatory factor 3 (IRF3) contributes to sepsis pathogenesis in young mice subject to cecal ligation and puncture (CLP). In this study, we investigated if IRF3 contributes to sepsis in the context of aging.

Methods

Sepsis was induced in aged wild-type (WT) and IRF3-knock-out (KO) mice, using a clinically-relevant CLP-sepsis model including fluids and antibiotics. Animal survival, disease score and hypothermia were evaluated as indicators of sepsis pathogenesis. Serum cytokines and serum enzymes indicative of organ damage were also measured.

Results

Aged WT mice were highly susceptible to sepsis (90% mortality). In comparison, aged IRF3-KO mice were significantly protected (20% mortality). Aged IRF3-KO mice showed a lower disease score and reduced hypothermia following CLP, compared to WT mice. Serum cytokines interleukin (IL)-6, IL-12/23p40 and macrophage chemoattractant protein (MCP)-1, and creatinine kinase (CK) were lower in aged IRF3-KO septic mice compared to WT counterparts. Aged male mice were found to be more susceptible to sepsis compared to females. Female mice, however, produced higher levels of serum cytokines and CK.

Conclusion

These results demonstrate that IRF3 plays a detrimental role in sepsis in aged mice and highlight the impact of biological sex.

Selenocompounds and Sepsis: Redox Bypass Hypothesis for Early Diagnosis and Treatment: Part A-Early Acute Phase of Sepsis: An Extraordinary Redox Situation (Leukocyte/Endothelium Interaction Leading to Endothelial Damage)

Significance: Sepsis is a health disaster. In sepsis, an initial, beneficial local immune response against infection evolves rapidly into a generalized, dysregulated response or a state of chaos, leading to multiple organ failure. Use of life-sustaining supportive therapies creates an unnatural condition, enabling the complex cascades of the sepsis response to develop in patients who would otherwise die. Multiple attempts to control sepsis at an early stage have been unsuccessful. Recent Advances: Major events in early sepsis include activation and binding of leukocytes and endothelial cells in the microcirculation, damage of the endothelial surface layer (ESL), and a decrease in the plasma concentration of the antioxidant enzyme, selenoprotein-P. These events induce an increase in intracellular redox potential and lymphocyte apoptosis, whereas apoptosis is delayed in monocytes and neutrophils. They also induce endothelial mitochondrial and cell damage. Critical Issues: Neutrophil production increases dramatically, and aggressive immature forms are released. Leukocyte cross talk with other leukocytes and with damaged endothelial cells amplifies the inflammatory response. The release of large quantities of reactive oxygen, halogen, and nitrogen species as a result of the leukocyte respiratory burst, endothelial mitochondrial damage, and ischemia/reperfusion processes, along with the marked decrease in selenoprotein-P concentrations, leads to peroxynitrite damage of the ESL, reducing flow and damaging the endothelial barrier. Future Directions: Endothelial barrier damage by activated leukocytes is a time-sensitive event in sepsis, occurring within hours and representing the first step toward organ failure and death. Reducing or stopping this event is necessary before irreversible damage occurs.

Thrombomodulin gene polymorphism and the occurrence and prognostic value of sepsis acute kidney injury

ABSTRACT

To investigate the relationship between thrombomodulin (THBD) gene single nucleotide polymorphisms (SNPs) and susceptibility to sepsis and the occurrence and prognosis of acute kidney injury (AKI) in sepsis patients.The genotypes of THBD gene rs1962, rs3176123, and rs1042580 in 178 sepsis patients with AKI, 243 sepsis patients without AKI (No AKI), and 103 healthy controls were analyzed by direct sequencing. Enzyme-linked immunosorbent assay (ELISA) was used to detect the plasma THBD protein levels. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value of plasma THBD levels in sepsis, AKI, and death of sepsis patients.The C allele carriers of THBD gene rs1962 were more likely to develop AKI and sepsis than the T allele carriers (OR = 1.61, 95% CI: 1.18-2.19, P < .01; OR = 2.16, 95% CI: 1.42-3.29, P < .01). The rs3176123 G allele was associated with an increased risk of AKI in sepsis patients (OR = 1.41, 95% CI: 1.06-1.88, P = .02), the G allele had a significant association with a higher risk of sepsis susceptibility (OR = 1.91, 95% CI: 1.33-2.75, P < .01). Sepsis patients of rs1042580 C allele had a lower risk of AKI than those of T allele (OR = 0.58, 95% CI: 0.37-0.91, P = .02), the C allele was related to a reduced risk of sepsis susceptibility (OR = 0.38, 95% CI: 0.26-0.55, P < .01). The THBD gene rs1962, rs3176123, and rs1042580 TGT haplotype was linked to higher risk of AKI in patients with sepsis (OR = 1.96, 95%CI: 1.14-3.38, P = .02). Sepsis patients with the THBD gene rs1962 TC + CC genotype had a higher risk of death than those with TT genotype (OR = 10.93, 95%CI: 5.05-26.96, P < .01), but there was no significant difference in the risk of death in sepsis patients with different genotypes at rs3176123 and rs1042580 (P > .05).The THBD gene rs1962, rs3176123, and rs1042580 SNPs are significantly associated with sepsis susceptibility and the risk of AKI. The rs1962 SNP is related to the risk of death in sepsis patients.

Genetically Modified Mesenchymal Stromal/Stem Cells: Application in Critical Illness

Critical illnesses including sepsis, acute respiratory distress syndromes, ischemic cardiovascular disorders and acute organ injuries are associated with high mortality, morbidity as well as significant health care system expenses. While these diverse conditions require different specific therapeutic approaches, mesenchymal stem/stromal cell (MSCs) are multipotent cells capable of self-renewal, tri-lineage differentiation with a broad range regenerative and immunomodulatory activities, making them attractive for the treatment of critical illness. The therapeutic effects of MSCs have been extensively investigated in several pre-clinical models of critical illness as well as in phase I and II clinical cell therapy trials with mixed results. Whilst these studies have demonstrated the therapeutic potential for MSC therapy in critical illness, optimization for clinical use is an ongoing challenge. MSCs can be readily genetically modified by application of different techniques and tools leading to overexpress or inhibit genes related to their immunomodulatory or regenerative functions. Here we will review recent approaches designed to enhance the therapeutic potential of MSCs with an emphasis on the technology used to generate genetically modified cells, target genes, target diseases and the implication of genetically modified MSCs in cell therapy for critical illness.

Endothelial Dysfunction and Impaired Neurovascular Coupling Responses Precede Cognitive Impairment in a Mouse Model of Geriatric Sepsis

Sepsis is a life-threatening condition, the incidence of which is significantly increased in elderly patients. One of the long-lasting effects of sepsis is cognitive impairment defined as a new deficit or exacerbation of preexisting deficits in global cognition or executive function. Normal brain function is dependent on moment-to-moment adjustment of cerebral blood flow to match the increased demands of active brain regions. This homeostatic mechanism, termed neurovascular coupling (NVC, also known as functional hyperemia), is critically dependent on the production of vasodilator NO by microvascular endothelial cells in response to mediators released from activated astrocytes. The goal of this study was to test the hypothesis that sepsis in aging leads to impairment of NVC responses early after treatment and that this neurovascular dysfunction associates with impairments in cognitive performance and vascular endothelial dysfunction. To test this hypothesis, we used a commonly studied bacterial pathogen, Listeria monocytogenes, to induce sepsis in experimental animals (males, 24 months of age) and subjected experimental animals to a standard clinical protocol of 3 doses of ampicillin i.p. and 14 days of amoxicillin added to the drinking water. NVC responses, endothelial function and cognitive performance were measured in septic and age-matched control groups within 14 days after the final antibiotic treatment. Our data demonstrate that sepsis in aging significantly impairs NVC responses measured in somatosensory cortex during whisker stimulation, significantly impairs endothelial function in isolated and pressure cannulated aorta rings in response to acetylcholine stimulation. No significant impairment of cognitive function in post-sepsis aged animals has been observed when measured using the PhenoTyper homecage based system. Our findings suggest that sepsis-associated endothelial dysfunction and impairment of NVC responses may contribute to long-term cognitive deficits in older sepsis survivors.

Immune Cell Number, Phenotype, and Function in the Elderly with Sepsis

Sepsis is a form of life-threatening organ dysfunction caused by dysregulated host responses to an infection that can be partly attributed to immune dysfunction. Although sepsis affects patients of all ages, elderly individuals display increased susceptibility and mortality. This is partly due to immunosenescence, a decline in normal immune system function associated with physiological aging that affects almost all cell types in the innate and adaptive immune systems. In elderly patients with sepsis, these alterations in immune cells such as endothelial cells, neutrophils, monocytes, macrophages, natural killer cells, dendritic cells, T lymphocytes, and B lymphocytes, are largely responsible for their poor prognosis and increased mortality. Here, we review recent studies investigating the events affecting both innate and adaptive immune cells in elderly mice and patients with sepsis, including alterations in their number, phenotype, and function, to shed light on possible new therapeutic strategies.

Cell-Cell Interaction Mechanisms in Acute Lung Injury

ABSTRACT

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are caused by an exaggerated inflammatory response arising from a wide variety of pulmonary and systemic insults. Lung tissue is composed of a variety of cell populations, including parenchymal and immune cells. Emerging evidence has revealed that multiple cell populations in the lung work in concert to regulate lung inflammation in response to both direct and indirect stimulations. To date, the question of how different types of pulmonary cells communicate with each other and subsequently regulate or modulate inflammatory cascades remains to be fully addressed. In this review, we provide an overview of current advancements in understanding the role of cell-cell interaction in the development of ALI and depict molecular mechanisms by which cell-cell interactions regulate lung inflammation, focusing on inter-cellular activities and signaling pathways that point to possible therapeutic opportunities for ALI/ARDS.

The Effect of Type of Delivery on the Nitric Oxide Metabolites and Endothelial Dysfunction in Pregnant Women

Background:

Since endothelial dysfunction is related to atherosclerosis, this study was planned to determine the effect of type of delivery on Nitric Oxide (NO) metabolites and endothelial function.

Materials and Methods:

This Cohort study was conducted in 2015 in selected hospitals of Isfahan. 88 nulliparous women with gestational age of 39 weeks and above were enrolled in this study using convenience sampling method and finally, after giving birth, 51 mothers with vaginal delivery, 21 with urgent C-section and 13 with elective C-section were considered for data analysis. The serum levels of NO metabolites were measured in the laboratory with standard kits and data was analyzed using student and paired t-test, one-way ANOVA, and Chi-square test. The significance level was considered less than 0.05 for all tests.

Results:

The NO metabolites levels in mothers who had vaginal delivery or urgent C-section showed a significant difference before and after delivery (normal vaginal delivery (NVD): t₅₀ = 5.61, p < 0.001, Urgent C-section: t₂₃ = 5.38, p < 0.001). But those with elective C-section showed no significant difference in the nitrate and total nitrite levels before and after delivery (p > 0.05).

Conclusions:

Since reduction in serum levels of NO metabolites may possibly indicate endothelial dysfunction and predict cardiovascular disease, especially atherosclerosis in the future, it could be concluded that, childbirth, regardless of the type of delivery, could damage the endothelial cells but C-section (urgent or elective) could cause more disruption than vaginal delivery.

Aging influences in the blood-brain barrier permeability and cerebral oxidative stress in sepsis

Sepsis is a set of serious manifestations throughout the body produced by an infection, leading to changes that compromise cellular homeostasis and can result in dysfunction of the central nervous system. The elderly have a higher risk of developing sepsis than younger peoples. Under the influence of inflammatory mediators and oxidizing agents released in the periphery as a result of the infectious stimulus, changes occur in the blood-brain barrier (BBB) permeability, with neutrophil infiltration, the passage of toxic compounds, activation of microglia and production of reactive species that results in potentiation of neuroimmune response, with the progression of neuronal damage and neuroinflammation. The objective of this study is to compare BBB permeability and the development of oxidative stress in the hippocampus and prefrontal cortex of young and old rats submitted to polymicrobial sepsis induction. Male Wistar rats grouped into sham (60d), sham (210d), cecal ligation and perforation (CLP) (60d) and CLP (210d) with n = 16 per experimental group were evaluated using the CLP technique to induce sepsis. The brain regions were collected at 24 h after sepsis induction to determine BBB permeability, myeloperoxidase (MPO) activity as marker of neutrophil activation, nitrite/nitrate (N/N) levels as marker of reactive nitrogen species, thiobarbituric acid reactive substances as marker of lipid peroxidation, protein carbonylation as marker of protein oxidation, and activity of antioxidant enzyme catalase (CAT). There was an increase in the BBB permeability in the CLP groups, and this was enhanced with aging in both brain region. MPO activity in the brain regions increased in the CLP groups, along with a hippocampal increase in the CLP 210d group compared to the 60d group. The concentration of N/N in the brain region was increased in the CLP groups. The damage to lipids and proteins in the two structures was enhanced in the CLP groups, while only lipid peroxidation was higher in the prefrontal cortex of the CLP 210d group compared to the 60d. CAT activity in the hippocampus was decreased in both CLP groups, and this was also influenced by age, whereas in the prefrontal cortex there was only a decrease in CAT in the CLP 60d group compared to the sham 60d. These findings indicate that aging potentiated BBB permeability in sepsis, which possibly triggered an increase in neutrophil infiltration and, consequently, an increase in oxidative stress.

Prognostic performance of endothelial biomarkers to early predict clinical deterioration of patients with suspected bacterial infection and sepsis admitted to the emergency department

BACKGROUND

The objective of this study was to evaluate the ability of endothelial biomarkers to early predict clinical deterioration of patients admitted to the emergency department (ED) with a suspected sepsis. This was a prospective, multicentre, international study conducted in EDs. Adult patients with suspected acute bacterial infection and sepsis were enrolled but only those with confirmed infection were analysed. The kinetics of biomarkers and organ dysfunction were collected at T0, T6 and T24 hours after ED admission to assess prognostic performances of sVEGFR2, suPAR and procalcitonin (PCT). The primary outcome was the deterioration within 72 h and was defined as a composite of relevant outcomes such as death, intensive care unit admission and/or SOFA score increase validated by an independent adjudication committee.

RESULTS

After adjudication of 602 patients, 462 were analysed including 124 who deteriorated (27%). On admission, those who deteriorated were significantly older (73 [60-82] vs 63 [45-78] y-o, p < 0.001) and presented significantly higher SOFA scores (2.15 ± 1.61 vs 1.56 ± 1.40, p = 0.003). At T0, sVEGFR2 (5794 [5026-6788] vs 6681 [5516-8059], p < 0.0001), suPAR (6.04 [4.42-8.85] vs 4.68 [3.50-6.43], p < 0.0001) and PCT (7.8 ± 25.0 vs 5.4 ± 17.9 ng/mL, p = 0.001) were associated with clinical deterioration. In multivariate analysis, low sVEGFR2 expression and high suPAR and PCT levels were significantly associated with early deterioration, independently of confounding parameters (sVEGFR2, OR = 1.53 [1.07-2.23], p < 0.001; suPAR, OR = 1.57 [1.21-2.07], p = 0.003; PCT, OR = 1.10 [1.04-1.17], p = 0.0019). Combination of sVEGFR2 and suPAR had the best prognostic performance (AUC = 0.7 [0.65-0.75]) compared to clinical or biological variables.

CONCLUSIONS

sVEGFR2, either alone or combined with suPAR, seems of interest to predict deterioration of patients with suspected bacterial acute infection upon ED admission and could help front-line physicians in the triage process.

Apoptotic cell therapy for cytokine storm associated with acute severe sepsis

Sepsis has no proven pharmacologic treatment other than appropriate antibiotic agents, fluids, vasopressors as needed, and possibly corticosteroids. It is generally initiated mainly by the simultaneous recognition by various components of the innate immune system of either pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs). In the current study, we employed the murine cecal ligation and puncture (CLP) model for sepsis to evaluate the effect of post-CLP infusion of apoptotic cells (Allocetra-OTS) on a CLP severe sepsis model. Cardiovascular evaluation, acute kidney injury (AKI), acute liver injury (ALI), and hematological and metabolic function were evaluated. Cytokine and chemokine profiles were measured by Multiplex ELISA and mitochondrial function, and glycolysis by Seahorse. The Murine Sepsis Score (MSS) was used for disease severity definition. CLP mice had low blood pressure, poor cardiac output, and lung dysfunction, as well as AKI, ALI, and thrombocytopenia, which correlated with the MSS and corresponded to a cytokine/chemokine storm. Apoptotic cell administration markedly improved the cytokine and chemokine storm and restored the impaired mitochondrial and glycolytic function in white blood cells leading to increased survival, from 6 to 60% (P < 0.0001), together with a significant improvement in organ dysfunction. We conclude that the deleterious immune response in CLP-induced sepsis can be successfully modified by apoptotic cell infusion.

Nrf2 dysfunction and impaired cellular resilience to oxidative stressors in the aged vasculature: from increased cellular senescence to the pathogenesis of age-related vascular diseases

Aging is associated with increased oxidative stress in vascular endothelial and smooth muscle cells, which contribute to the development of a wide range of diseases affecting the circulatory system in older adults. There is growing evidence that in addition to increased production of reactive oxygen species (ROS), aging critically impairs pathways determining cellular resilience to oxidative stressors. In young organisms, the evolutionarily conserved nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated antioxidant response pathway maintains cellular reduction-oxidation homeostasis and promotes a youthful cellular phenotype by regulating the transcription of an array of cytoprotective (antioxidant, pro-survival, anti-inflammatory and macromolecular damage repair) genes. A critical mechanism by which increased ROS production and Nrf2 dysfunction promote vascular aging and exacerbate pathogenesis of age-related vascular diseases is induction of cellular senescence, an evolutionarily conserved cellular stress response mechanism. Senescent cells cease dividing and undergo distinctive phenotypic alterations, contributing to impairment of angiogenic processes, chronic sterile inflammation, remodeling of the extracellular matrix, and barrier dysfunction. Herein, we review mechanisms contributing to dysregulation of Nrf2-driven cytoprotective responses in the aged vasculature and discuss the multifaceted role of Nrf2 dysfunction in the genesis of age-related pathologies affecting the circulatory system, including its role in induction of cellular senescence. Therapeutic strategies that restore Nrf2 signaling and improve vascular resilience in aging are explored to reduce cardiovascular mortality and morbidity in older adults.

Bioassay for Endothelial Damage Mediators Retrieved by Hemoadsorption

Hemoadsorption devices are used to treat septic shock by adsorbing inflammatory cytokines and as yet incompletely defined danger and pathogen associated molecular patterns. In an ideal case, hemoadsorption results in immediate recovery of microvascular endothelial cells’ (mEC) function and rapid recovery from catecholamine-dependency and septic shock. We here tested a single device, which consists of polystyrene-divinylbenzene core particles of 450 μm diameter with a high affinity for hydrophobic compounds. The current study aimed at the proof of concept that endothelial-specific damage mediators are adsorbed and can be recovered from hemoadsorption devices. Because of excellent clinical experience, we tested protein fractions released from a hemoadsorber in a novel endothelial bioassay. Video-based, long-term imaging of mEC proliferation and cell death were evaluated and combined with apoptosis and ATP measurements. Out of a total of 39 fractions recovered from column fractionation, we identified 3 fractions that caused i) inhibition of mEC proliferation, ii) increased cell death and iii) induction of apoptosis in mEC. When adding these 3 fractions to mEC, their ATP contents were reduced. These fractions contained proteins of approximately 15 kDa, and high amounts of nucleic acid, which was at least in part oxidized. The efficacy for endothelial cell damage prevention by hemoadsorption can be addressed by a novel endothelial bioassay and long-term video observation procedures. Protein fractionation of the hemoadsorption devices used is feasible to study and define endothelial damage ligands on a molecular level. The results suggest a significant effect by circulating nucleic acids – bound to an as yet undefined protein, which may constitute a major danger-associated molecular pattern (DAMP) in the exacerbation of inflammation when patients experience septic shock. Hemoadsorption devices may thus limit endothelial damage, through the binding of nucleic acid-bearing aggregates and thus contribute to improved endothelial barrier function.

Multiple Organ Dysfunction Syndrome

Multiple organ dysfunction syndrome (MODS) is one of the most common syndromes of critical illness and the leading cause of mortality among critically ill patients. Multiple organ dysfunction syndrome is the clinical consequence of a dysregulated inflammatory response, triggered by clinically diverse factors with the main pillar of management being invasive organ support. During the last years, the advances in the clarification of the molecular pathways that trigger, mitigate, and determine the outcome of MODS have led to the increasing recognition of MODS as a distinct disease entity with distinct etiology, pathophysiology, and potential future therapeutic interventions. Given the lack of effective treatment for MODS, its early recognition, the early intensive care unit admission, and the initiation of invasive organ support remain the most effective strategies of preventing its progression and improving outcomes.

Cystathionine-γ-lyase (CSE) deficiency increases erythropoiesis and promotes mitochondrial electron transport via the upregulation of coproporphyrinogen III oxidase and consequent stimulation of heme biosynthesis

BACKGROUND

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter produced by mammalian cells. The current study investigated the potential role of H₂S in the regulation of heme biosynthesis using mice deficient in cystathionine gamma-lyase (CSE), one of the three major mammalian H₂S-producing enzymes.

METHODS

Wild-type and global CSE^-/- mice, as well as mitochondria prepared from their liver were used. In vivo, arterial and venous blood gases were measured, and survival of the mice to severe global hypoxia was monitored. Ex vivo, expression of various heme biosynthetic enzymes including coproporphyrinogen oxidase (CPOX) was measured, and mitochondrial function was evaluated using Extracellular Flux Analysis. Urine samples were collected to measure the oxidized porphyrinogen intermediates. The in vivo/ex vivo studies were complemented with mitochondrial bioenergetic studies in hepatocytes in vitro. Moreover, the potential effect of H₂S on the CPOX promoter was studied in cells expressing a CPOX promoter construct system.

RESULTS

The main findings are as follows: (1) CSE^-/- mice exhibit elevated red blood cell counts and red blood cell mean corpuscular volumes compared to wild-type mice; (2) these changes are associated with elevated plasma and liver heme levels and (3) these alterations are likely due to an induction of CPOX (the sixth enzyme involved in heme biosynthesis) in CSE^-/- mice. (4) Based on in vitro promoter data the promoter activation of CPOX is directly influenced by H₂S, the product of CSE. With respect to the potential functional relevance of these findings, (5) the increased circulating red blood cell numbers do not correspond to any detectable alterations in blood gas parameters under resting conditions, (6) nor do they affect the hypoxia tolerance of the animals in an acute severe hypoxia model. However, there may be a functional interaction between the CSE system and the CPOX system in terms of mitochondrial bioenergetics: (7) CSE^-/- hepatocytes and mitochondria isolated from them exhibit increased oxidative phosphorylation parameters, and (8) this increase is partially blunted after CPOX silencing. Although heme is essential for the biosynthesis of mitochondrial electron chain complexes, and CPOX is required for heme biosynthesis, (9) the observed functional mitochondrial alterations are not associated with detectable changes in mitochondrial electron transport chain protein expression.

CONCLUSIONS

The CSE system regulates the expression of CPOX and consequent heme synthesis. These effects in turn, do not influence global oxygen transport parameters, but may regulate mitochondrial electron transport.

PDE2 regulates membrane potential, respiration and permeability transition of rodent subsarcolemmal cardiac mitochondria

Cyclic adenosine monophosphate (cAMP) production regulates certain aspects of mitochondria function in rodent cardiomyocytes, such as ATP production, oxygen consumption, calcium import and mitochondrial permeability transition (MPT), but how this cAMP pool is controlled is not well known. Here, expression, localization and activity of several cAMP-degrading enzymes, i.e. phosphodiesterases (PDEs), were investigated in isolated rodent cardiac mitochondria. In contrast to the heart ventricle where PDE4 is the major PDE, in cardiac mitochondria, cGMP-stimulated PDE2 activity was largest than PDE3 and PDE4 activities. PDE2 expression was mainly detected in subsarcolemmal mitochondria in association with the inner membrane rather than in interfibrillar mitochondria. PDE2, 3 and 4 activities were further confirmed in neonatal rat cardiomyocytes by real time FRET analysis. In addition, the pharmacological inhibition or the cardiac-specific overexpression of PDE2 modulated mitochondrial membrane potential loss, MPT and calcium import. In mitochondria isolated from PDE2 transgenic mice with a cardiac selective PDE2 overexpression, the oxidative phosphorylation (OXPHOS) was significantly lower than in wild-type mice, but stimulated by cGMP. Thus, cAMP degradation by PDEs represents a new regulatory mechanism of mitochondrial function.

The PARP inhibitor olaparib exerts beneficial effects in mice subjected to cecal ligature and puncture and in cells subjected to oxidative stress without impairing DNA integrity: A potential opportunity for repurposing a clinically used oncological drug for the experimental therapy of sepsis

Poly(ADP-ribose) polymerase (PARP) is involved in the pathogenesis of cell dysfunction, inflammation and organ failure during septic shock. The goal of the current study was to investigate the efficacy and safety of the clinically approved PARP inhibitor olaparib in experimental models of oxidative stress in vitro and in sepsis in vivo. In mice subjected to cecal ligation and puncture (CLP) organ injury markers, circulating and splenic immune cell distributions, circulating mediators, DNA integrity and survival was measured. In U937 cells subjected to oxidative stress, cellular bioenergetics, viability and DNA integrity were measured. Olaparib was used to inhibit PARP. The results show that in adult male mice subjected to CLP, olaparib (1-10 mg/kg i.p.) improved multiorgan dysfunction. Olaparib treatment reduced the degree of bacterial CFUs. Olaparib attenuated the increases in the levels of several circulating mediators in the plasma. In the spleen, the number of CD4+ and CD8+ lymphocytes were reduced in response to CLP; this reduction was inhibited by olaparib treatment. Treg but not Th17 lymphocytes increased in response to CLP; these cell populations were reduced in sepsis when the animals received olaparib. The Th17/Treg ratio was lower in CLP-olaparib group than in the CLP control group. Analysis of miRNA expression identified a multitude of changes in spleen and circulating white blood cell miRNA levels after CLP; olaparib treatment selectively modulated these responses. Olaparib extended the survival rate of mice subjected to CLP. In contrast to males, in female mice olaparib did not have significant protective effects in CLP. In aged mice olaparib exerted beneficial effects that were less pronounced than the effects obtained in young adult males. In in vitro experiments in U937 cells subjected to oxidative stress, olaparib (1-100 μM) inhibited PARP activity, protected against the loss of cell viability, preserved NAD⁺ levels and improved cellular bioenergetics. In none of the in vivo or in vitro experiments did we observe any adverse effects of olaparib on nuclear or mitochondrial DNA integrity. In conclusion, olaparib improves organ function and extends survival in septic shock. Repurposing and eventual clinical introduction of this clinically approved PARP inhibitor may be warranted for the experimental therapy of septic shock.

Inter-α-inhibitor Ameliorates Endothelial Inflammation in Sepsis

PURPOSE

Vascular endothelial cells demonstrate severe injury in sepsis, and a reduction in endothelial inflammation would be beneficial. Inter-α-Inhibitor (IαI) is a family of abundant plasma proteins with anti-inflammatory properties and has been investigated in human and animal sepsis with encouraging results. We hypothesized that IαI may protect endothelia from sepsis-related inflammation.

METHODS

IαI-deficient or sufficient mice were treated with endotoxin or underwent complement-induced lung injury. VCAM-1 and ICAM-1 expression was measured in blood and lung as marker of endothelial activation. Human endothelia were exposed to activated complement C5a with or without IαI. Blood from human sepsis patients was examined for VCAM-1 and ICAM-1 and levels were correlated with blood levels of IαI.

RESULTS

IαI-deficient mice showed increased endothelial activation in endotoxin/sepsis- and complement-induced lung injury models. In vitro, levels of endothelial pro-inflammatory cytokines and cell growth factors induced by activated complement C5a were significantly decreased in the presence of IαI. This effect was associated with decreased ERK and NFκB activation. IαI levels were inversely associated with VCAM-1 and ICAM-1 levels in a human sepsis cohort.

CONCLUSIONS

IαI ameliorates endothelial inflammation and may be beneficial as a treatment of sepsis.

Klotho deficiency aggravates sepsis-related multiple organ dysfunction

Sepsis-induced organ failure is characterized by a massive inflammatory response and oxidative stress. Acute kidney injury (AKI) occurs in approximately half of patients in septic shock, and the mortality associated with sepsis-induced AKI is unacceptably high. Klotho is a protein expressed by renal cells and has anti-senescence properties. Klotho has also been shown to protect the kidneys in ischemia-reperfusion injury and to have antioxidant properties. To analyze the role of Klotho in sepsis-related organ dysfunction and AKI, we used a cecal ligation and puncture (CLP) model of sepsis in heterozygous Klotho-haploinsufficient mice and their wild-type littermates (CLP- Kl/+ and CLP-WT mice, respectively). In comparison with the CLP-WT mice, CLP- Kl/+ mice showed lower survival, impaired renal function, impaired hepatic function, greater oxidative stress, upregulation of inflammatory pathways (at the systemic and kidney tissue levels), and increased NF-κB activation. It is noteworthy that CLP- Kl/+ mice also showed lower heart-rate variability, less sympathetic activity, impaired baroreflex sensitivity to sodium nitroprusside, and a blunted blood pressure response to phenylephrine. We also demonstrated that sepsis creates a state of acute Klotho deficiency. Given that low Klotho expression exacerbates sepsis and multiple organ dysfunction, Klotho might play a protective role in sepsis, especially in elderly individuals in whom Klotho expression is naturally reduced.

Real-time Temperature Measurements of HMEC-1 Cells during Inflammation Production and Repair detected by Wireless Thermometry

Cell inflammation process is reflected through real-time in situ cellular temperature changes.

METHODS

A wireless thermometry system for in situ cellular temperature measurements was used in an incubator to detect the HMEC-1 cellular temperature under lipopolysaccharide inflammation production and norepinephrine for inflammation repair. Combining the changes in cell viability, inflammatory factor levels and ATP content caused by different lipopolysaccharide or norepinephrine doses, an obvious inflammatory response and repair effect was obtained. Temperature variations were correlated with ATP content.

RESULTS

An obvious inflammatory response with a lipopolysaccharide concentration of 0.1 mg/L and an optimal repair effect with 1 μM norepinephrine were obtained. The relationship between temperature changes and ATP content were quite different during the production of inflammation in HMEC-1 cells, having an approximately linear relationship, while under conditions of inflammation repair in HMEC-1 cells, there was an obvious nonlinear relationship.

CONCLUSION

During cell damage, cell thermogenesis has a linear correlation with intracellular energy. While during cell repair, there is a gradual saturation relationship between the temperature (small range) and ATP, which may be because the thermogenesis capacity of the cell is enhanced compared to conditions during cell energy storage. Additionally, there is an optimal drug concentration for cell action during cell injury and cell repair, which is not dose-dependent.

SIGNIFICANCE

Whether in inflammation production or treatment, there is an optimal drug concentration. The relationship between cell thermogenesis and intracellular energy reserves is related to cell processes. Quick analysis of the energy changes in different physiological process can be realized.

Group 2 innate lymphoid cells protect lung endothelial cells from pyroptosis in sepsis

Group 2 innate lymphoid cells (ILC2) are one of three subgroups of innate lymphoid cells (ILC1, ILC2, and ILC3), and the major ILC population detected in the lungs. The function of ILC2 in the regulation of lung inflammation remains unclear. In the current study, we explored an important role of ILC2 in protecting lung endothelial cell (EC) from pyroptosis in sepsis-induced acute lung inflammation and the underlying mechanism. Using a cecal ligation and puncture (CLP) mouse sepsis model, we demonstrated that IL-33, which is released in response to sepsis, acting through its receptor ST2 mediates ILC2 expansion in the lungs. We further showed that the increased ILC2 in the lungs secrete IL-9, which in turn prevents lung EC from undergoing pyroptosis, a pro-inflammatory cell death form, by attenuating caspase-1 activation. These findings suggest a previously unidentified innate pathway that negatively regulates lung inflammation following sepsis.

The contribution of mast cells to bacterial and fungal infection immunity

Mast cells are hematopoietic progenitor-derived, granule-containing immune cells that are widely distributed in tissues that interact with the external environment, such as the skin and mucosal tissues. It is well-known that mast cells are significantly involved in IgE-mediated allergic reactions, but because of their location, it has also been long hypothesized that mast cells can act as sentinel cells that sense pathogens and initiate protective immune responses. Using mast cell or mast cell protease-deficient murine models, recent studies by our groups and others indicate that mast cells have pleiotropic regulatory roles in immunological responses against pathogens. In this review, we discuss studies that demonstrate that mast cells can either promote host resistance to infections caused by bacteria and fungi or contribute to dysregulated immune responses that can increase host morbidity and mortality. Overall, these studies indicate that mast cells can influence innate immune responses against bacterial and fungal infections via multiple mechanisms. Importantly, the contribution of mast cells to infection outcomes depends in part on the infection model, including the genetic approach used to assess the influence of mast cells on host immunity, hence highlighting the complexity of mast cell biology in the context of innate immune responses.

Anti-sepsis protection of Xuebijing injection is mediated by differential regulation of pro- and anti-inflammatory Th17 and T regulatory cells in a murine model of polymicrobial sepsis

ETHNOPHARMACOLOGICAL RELEVANCE

Xuebijing injection (XBJ), a Chinese herbal medicine containing extracts from 5 herbs, is frequently used as an add-on with standard therapies to treat sepsis or septic shock with fewer side effects in China. Nonetheless, its mechanism of action on septic shock remains to be unveiled. We explored the differential effects of XBJ on subtypes of CD4+ T cell differentiation and septic shock protection in a murine model to understand the contribution of XBJ to regulation of the inflammation-immune axis function.

MATERIALS AND METHODS

In vitro T cell differentiation assays were performed to determine the effect of XBJ on CD4+ regulatory T cell and T helper cell differentiation. Besides, 2ml/kg, 6ml/kg- and 18ml/kg of XBJ were administered to different groups of septic mice once/day for 5 days after cecal ligation and puncture (CLP) surgeries. 36h after CLP, serum levels of pro-inflammatory cytokine TNF-α and IL-6 were determined with Elisa. Frequencies of CD4+ T cells were analyzed after staining with Tregs and T helper cell lineage specific antibodies by flow cytometer.

RESULTS

XBJ at 18ml/kg stimulated Treg differentiation and moderately inhibited Th17 differentiation in vitro. Accordingly, 18ml/kg XBJ facilitated the expansion of IL-10+ Tregs and normalized pro-inflammatory Th17 population in septic mice. This regimen also significantly reduced serum levels of inflammatory cytokines TNF-α and IL-6 in septic mice. Additionally, 18ml/kg XBJ injection effectively prevented neutrophil infiltration into the lung and kidney and improved survival in this septic shock model.

CONCLUSIONS

In summary, XBJ improves survival in septic shock partially through preventing cytokine storm, inhibiting inflammation and regulating the balance of Tregs and Th17 cells. Thus, higher dose of XBJ is a potential regimen to benefit septic shock patients.

Delayed Treatment with Sodium Hydrosulfide Improves Regional Blood Flow and Alleviates Cecal Ligation and Puncture (CLP)-Induced Septic Shock

Cecal ligation and puncture (CLP)-induced sepsis is a serious medical condition, caused by a severe systemic infection resulting in a systemic inflammatory response. Recent studies have suggested the therapeutic potential of donors of hydrogen sulfide (H2S), a novel endogenous gasotransmitter and biological mediator in various diseases. The aim of the present study was to assess the effect of H2S supplementation in sepsis, with special reference to its effect on the modulation of regional blood flow. We infused sodium hydrosulfide (NaHS), a compound that produces H2S in aqueous solution (1, 3, or 10 mg/kg/h, for 1 h at each dose level) in control rats or rats 24 h after CLP, and measured blood flow using fluorescent microspheres. In normal control animals, NaHS induced a characteristic redistribution of blood flow, and reduced cardiac, hepatic, and renal blood flow in a dose-dependent fashion. In contrast, in rats subjected to CLP, cardiac, hepatic, and renal blood flow was significantly reduced; infusion of NaHS (1 mg/kg/h and 3 mg/kg/h) significantly increased organ blood flow. In other words, the effect of H2S on regional blood flow is dependent on the status of the animals (i.e., a decrease in blood flow in normal controls, but an increase in blood flow in CLP). We have also evaluated the effect of delayed treatment with NaHS on organ dysfunction and the inflammatory response by treating the animals with NaHS (3 mg/kg) intraperitoneally (i.p.) at 24 h after the start of the CLP procedure; plasma levels of various cytokines and tissue indicators of inflammatory cell infiltration and oxidative stress were measured 6 h later. After 24 h of CLP, glomerular function was significantly impaired, as evidenced by markedly increased (over 4-fold over baseline) blood urea nitrogen and creatinine levels; this increase was also significantly reduced by treatment with NaHS. NaHS also attenuated the CLP-induced increases in malondialdehyde levels (an index of oxidative stress) in heart as well as in liver and myeloperoxidase levels (an index of neutrophil infiltration) in heart and lung. Plasma levels of IL-1β, IL-5, IL-6, TNF-α, and HMGB1 were attenuated by NaHS. Treatment of NaHS at 3 mg/kg i.p. (but not 1 mg/kg or 6 mg/kg), starting 24 h post-CLP, with dosing repeated every 6 h, improved the survival rate in CLP animals. In summary, treatment with 3 mg/kg H2S-when started in a delayed manner, when CLP-induced organ injury, inflammation and blood flow redistribution have already ensued-improves blood flow to several organs, protects against multiple organ failure, and reduces the plasma levels of multiple pro-inflammatory mediators. These findings support the view that H2S donation may have therapeutic potential in sepsis.

Whole Body Periodic Acceleration (pGz) as a non-invasive preconditioning strategy for pediatric cardiac surgery

We hypothesized that pGz has cardio and neuroprotective effects due to upregulation of pathways which include eNOS, anti-apoptotic, and anti-inflammatory pathways. We analyze protein expression of these pathways in the brain of neonatal piglets, as well as report on the myocardial function after Deep Hypothermic Circulatory Arrest (DHCA) and pGz preconditioning. Animal data affirms both a cardio and neuroprotective role for pGz. These findings suggest that pGz can be a simple, non-invasive cardio and neuroprotective strategy preconditioning strategy in children requiring surgical intervention.

MiR-4505 aggravates lipopolysaccharide-induced vascular endothelial injury by targeting heat shock protein A12B

Heat shock protein family A member 12B (HSPA12B) is a heat shock protein primarily expressed in endothelial cells. Our previous study showed that it was protective against endothelial injury induced by lipopolysaccharide (LPS). The present study was performed to investigate whether micro (mi)RNA was involved in HSPA12B expression in endothelial cells challenged by LPS. We first screened the miRNA candidates potentially related to HSPA12B by bioinformatics analysis. Then the mimics of the miRNA candidates were transfected into human umbilical vein endothelial cells (HUVECs) to investigate the miRNAs that negatively regulated HSPA12B expression. The miRNA expression was also determined in LPS‑stimulated HUVECs. Dual luciferase activity assay was performed to confirm the relationship between the candidate miRNA and HSPA12B. Role of nuclear factor (NF)‑κB in the miRNA expression was investigated by using its inhibitor. Finally, the role of the miRNA on LPS induced injury was investigated. Eleven miRNAs were screened by bioinformatics analysis and 4 of them could inhibit HSPA12B expression at both mRNA and protein levels. Among the 4 miRNA candidates, only miR‑4505 was highly expressed in HUVECs stimulated by LPS. Luciferase analysis showed that miR‑4505 directly interacted with the 3'untranslated region of HSPA12B. LPS‑induced upregulation of miR‑4505 was blocked by NF‑κB inhibitor. Transfection with miR‑4505 mimics reduced the transendothelial electrical resistance and vascular endothelial‑cadherin expression. The scratch test demonstrated that miR‑4505 inhibited endothelial migration capacity. In conclusion, miR‑4505 downregulates the expression of HSPA12B and aggravates the LPS‑induced vascular endothelial cell injury.

Clinical factors influencing mortality risk in hospital-acquired sepsis

BACKGROUND

Identification of factors that confer an increased risk of mortality in hospital-acquired sepsis (HAS) is necessary to help prevent, and improve the outcome of, this condition.

AIM

To evaluate the clinical characteristics and factors associated with mortality in patients with HAS.

METHODS

Retrospective study of patients with HAS in a major Spanish Hospital from 2011 to 2015. Data from adults receiving any of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes associated with sepsis were collected. Those fulfilling the SEPSIS-2 definition with no evidence of infection during the first 48 h following hospitalization were included (N = 196). Multivariate analysis was employed to identify the risk factors of mortality.

FINDINGS

HAS patients were found to have many of the risk factors associated with cardiovascular disease (male sex, ageing, antecedent of cardiac disease, arterial hypertension, dyslipidaemia, smoking habit) and cancer. Vascular disease or chronic kidney disease were associated with 28-day mortality. Time from hospital admission to sepsis diagnosis, and the presence of organ failure were risk factors for 28-day and hospital mortality. Experiencing more than one episode of sepsis increased the risk of hospital mortality. 'Sepsis code' for the early identification of sepsis was protective against hospital mortality.

CONCLUSION

This study identifies several major factors associated with mortality in patients suffering from HAS. Implementation of surveillance programmes for the early identification and treatment of sepsis translate into a clear benefit.

Hepatic mitochondrial bioenergetics in aged C57BL/6 mice exhibit delayed recovery from severe burn injury

Severe burn injuries initiate a cascade of downstream events, culminating in multiple organ dysfunction, sepsis, and even death. The elderly are in particular vulnerable to such outcomes, due primarily to a scarcity of knowledge on trauma progression at the biomolecular level in this population. Mitochondria, the cellular powerhouses, have been increasingly scrutinized recently for their contribution to trauma outcomes. We hypothesized that elderly have a worse outcome compared to adult patients due to failed recovery of hepatic mitochondria. Using a murine model of burn injury, Seahorse respirometry and functional proteomic assays, we demonstrate the impact of thermal trauma on hepatic mitochondrial respiration in adult and aged mice. While the mitochondria in adults rebound from the initial insult within 7days of the injury, the older animals display delayed recovery of mitochondrial bioenergetics accompanied by uncoupling and an oxidative environment. This is associated with a state of increased protein oxidation and nitrosylation, along with increases in circulating mtDNA, a known damage-associated molecular pattern. These findings suggest that hepatic mitochondria fail to normalize after trauma in aged mice and we suggest that this cellular failure is associated with organ damage and subsequently increased morbidity and mortality in elderly burn patients.

Expression of c-FLIP in a rat model of sepsis and its effects on endothelial apoptosis

Sepsis is characterized by the impaired regulation of inflammatory responses. Apoptosis is important in the pathogenesis of sepsis. Cellular FLICE-inhibitory protein (c-FLIP) is a catalytically inactive caspase-8 homologue, which negatively interferes with apoptotic signaling. The role of c-FLIP in sepsis and in endothelial cell apoptosis, a critical step in the pathogenesis of sepsis, remains controversial. In the present study, to investigate the relationship between c-FLIP and sepsis, a rat model of sepsis was induced by cecal ligation and puncture, and western blot analysis was used to detect the expression of c-FLIP_L, the long isoform of c-FLIP. Lower protein expression levels of c-FLIP_L were found in the brain, intestine and lung of the rat sepsis model, compared with the rats in the sham surgery group. The association between the expression of c-FLIP_L and endothelial cell apoptosis was further examined in vitro by c-FLIP_L overexpression and flow cytometry, which demonstrated that the expression of c-FLIP_L was inversely correlated with endothelial cell apoptosis. These data suggested that c-FLIP may be important in sepsis and shed light on therapeutic strategies.

Blood transfusions may impair endothelium-dependent vasodilatation during coronary artery bypass surgery

OBJECTIVE

The hemolytic product free-hemoglobin (fHb) reduces nitric oxide (NO) bioavailability. The present study aims to establish whether administration of different blood transfusions result in increased circulating fHb levels and NO consumption with effects on arterial NO-dependent blood flow in patients undergoing CABG surgery.

METHODS

Ninety-five consecutive patients undergoing elective CABG surgery were prospectively divided in four groups based on blood transfusion requirements during surgery: stored blood cells (SBC, n. 21), intraoperative autologous salvaged blood (ASB, n. 25), SBC and ASB (n.22), no transfusion (control, n. 27). Blood samples were collected before and after intervention to analyse plasma levels of fHb and NO consumption. Endothelium-dependent relaxation was assessed in left internal mammary artery (LIMA) rings harvested before chest closure. Peripheral artery tonometry was assessed after intervention.

RESULTS

Transfusions with SBC increased plasma fHb (p<0.05). Transfusions of ASB resulted in higher plasma fHb compared to SBC (p<0.01). fHb concentrations directly correlated with NO consumption (r=0.65, p<0.001). Maximal endothelium-dependent relaxation in LIMA was significantly attenuated in SBC and ASB patients compared to control (15.2±3.1% vs 21.1±2.5% vs 43±5.0% respectively; p<0.01). Significant correlations were identified between the aortic pressure wave velocity, plasma fHb concentration and NO consumption (p<0.01).

CONCLUSIONS

Intraoperative blood transfusions and particularly autologous salvaged blood impair endothelium-dependent relaxation through NO scavenging by fHb. These findings obtained in vitro and in vivo provide new insights into the adverse relation between blood transfusions and patient outcome.

Opportunities for the repurposing of PARP inhibitors for the therapy of non-oncological diseases

The recent clinical availability of the PARP inhibitor olaparib (Lynparza) opens the door for potential therapeutic repurposing for non-oncological indications. Considering (a) the preclinical efficacy data with PARP inhibitors in non-oncological diseases and (b) the risk-benefit ratio of treating patients with a compound that inhibits an enzyme that has physiological roles in the regulation of DNA repair, we have selected indications, where (a) the severity of the disease is high, (b) the available therapeutic options are limited, and (c) the duration of PARP inhibitor administration could be short, to provide first-line options for therapeutic repurposing. These indications are as follows: acute ischaemic stroke; traumatic brain injury; septic shock; acute pancreatitis; and severe asthma and severe acute lung injury. In addition, chronic, devastating diseases, where alternative therapeutic options cannot halt disease development (e.g. Parkinson's disease, progressive multiple sclerosis or severe fibrotic diseases), should also be considered. We present a preclinical and clinical action plan for the repurposing of PARP inhibitors.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.