Anti-tumor necrosis factor therapy in sepsis: update on clinical trials and lessons learned

Traumatic inflammatory response: pathophysiological role and clinical value of cytokines

Severe trauma is an intractable problem in healthcare. Patients have a widespread immune system response that is complex and vital to survival. Excessive inflammatory response is the main cause of poor prognosis and poor therapeutic effect of medications in trauma patients. Cytokines are signaling proteins that play critical roles in the body's response to injuries, which could amplify or suppress immune responses. Studies have demonstrated that cytokines are closely related to the severity of injuries and prognosis of trauma patients and help present cytokine-based diagnosis and treatment plans for trauma patients. In this review, we introduce the pathophysiological mechanisms of a traumatic inflammatory response and the role of cytokines in trauma patients. Furthermore, we discuss the potential of cytokine-based diagnosis and therapy for post-traumatic inflammatory response, although further clarification to elucidate the underlying mechanisms of cytokines following trauma is warranted.

Relative Adrenal Insufficiency Is a Risk Factor for Pediatric Sepsis: A Proof-of-Concept Study

Glucocorticoid (GC) therapy had been strongly recommended for pediatric sepsis (grade 1A). However, the recommendation was changed to grade 2C in 2020 due to weak evidence. About 32.8% of patients with pediatric septic develop relative adrenal insufficiency (RAI). But whether GC therapy should be determined by RAI status is controversial. This study utilized 21-day-old SF1CreSRBIfl/fl mice as the first pediatric RAI mouse model to assess the pathogenesis of RAI and evaluate GC therapy. RAI mice exhibited a substantially higher mortality rate in cecal ligation and puncture and cecal slurry-induced sepsis. These mice featured persistent inflammatory responses and were effectively rescued by GC therapy. RNA sequencing analysis revealed persistent inflammatory responses in RAI mice, caused by transcriptional dysregulation of AP-1 and NF-κB, and cytokine-induced secondary inflammatory response. Our findings support a precision medicine approach to guide GC therapy for pediatric patients based on the status of RAI.

Fibronectin extra domain a limits liver dysfunction and protects mice during acute inflammation

Background and aim

The primary transcript of fibronectin (FN) undergoes alternative splicing to generate different isoforms, including FN containing the Extra Domain A (FN_EDA+), whose expression is regulated spatially and temporarily during developmental and disease conditions including acute inflammation. The role of FN_EDA+ during sepsis, however, remains elusive.

Methods

Mice constitutively express the EDA domain of fibronectin (EDA^+/+); lacking the FN EDA domain (EDA^-/-) or with a conditional ablation of EDA + inclusion only in liver produced FN (alb-CRE⁺EDA floxed mice) thus expressing normal plasma FN were used. Systemic inflammation and sepsis were induced by either LPS injection (70 mg/kg) or by cecal ligation and puncture (CLP) Neutrophils isolated from septic patients were tested for neutrophil binding ability.

Results

We observed that EDA^+/+ were protected toward sepsis as compared to EDA^-/- mice. Also alb-CRE⁺EDA floxed mice presented reduced survival, thus indicating a key role for EDA in protecting toward sepsis. This phenotype was associated with improved liver and spleen inflammatory profile. Ex vivo experiments showed that neutrophils bind to a larger extent to an FN_EDA + coated surface as compared to FN, thus potentially limiting their over-reactivity.

Conclusions

Our study demonstrates that the inclusion of the EDA domain in fibronectin dampens the nflammatoryi consequences of sepsis.

Black Garlic and Thiosulfinate-Enriched Extracts as Adjuvants to Ceftriaxone Treatment in a Rat Peritonitis Model of Sepsis

To date, there have been no new drugs or adjuvants able to decrease both morbidity and mortality in the context of sepsis and septic shock. Our objective was to evaluate the use of thiosulfinate-enriched Allium sativum and black garlic extracts as adjuvants in the management of sepsis. An experimental in vivo study was carried out with male Sprague-Dawley^® rats. Animals were randomized in four treatment groups: antibiotic (ceftriaxone) treatment (group I), ceftriaxone plus thiosulfinate-enriched extract (TASE, group II), ceftriaxone plus thiosulfinate-enriched extract and black garlic extracts (TASE + BGE, group III), and ceftriaxone plus black garlic extract (BGE, group IV). All animals were housed and inoculated with 1 × 10¹⁰ CFU/15 mL of intraperitoneal Escherichia coli ATCC 25922. Subsequently, they received a daily treatment according to each group for 7 days. Clinical, analytical, microbiological, and histopathological parameters were evaluated. Statistically significant clinical improvement was observed in rats receiving garlic extracts in weight (groups II and III), ocular secretions, and piloerection (group IV). Moreover, less liver edema, vacuolization, and inflammation were observed in groups receiving adjuvant support (groups II, III, and IV). When comparing interleukins 24 h after bacteria inoculum, we found statistically significant differences in TNF-alpha levels in groups receiving BGE (groups III and IV, p ≤ 0.05). Blood and peritoneal liquid cultures were also analyzed, and we detected a certain level of Enterococcus faecalis in peritoneal cultures from all treatment groups and less bacteria presence in blood cultures in rats receiving garlic extracts (groups II, III, and IV). In conclusion, TASE and BGE could be promising nutraceutical or medicinal agents as coadjuvants in the treatment of sepsis because of its effects in modulating the inflammatory response.

Proinflammatory cytokines levels in sepsis and healthy volunteers, and tumor necrosis factor-alpha associated sepsis mortality: A systematic review and meta-analysis

BACKGROUND

Sepsis is a global health challenge associated with significant morbidity and mortality. Detrimental sepsis effects are attributed to excessive inflammation or a "cytokine storm." However, anti-inflammation therapies have failed to lower sepsis mortality. We aim to characterize levels of key inflammatory cytokines in patients with sepsis and compare levels with those in healthy individuals and relate tumor necrosis factor (TNF) α levels to patient characteristics and outcomes.

METHODS

We performed a systematic review and meta-analysis. Medline, Embase, Cochrane Library, and Web of Science Core Collection databases were searched between 1985 and May 2020. Analysis was restricted to studies in English. We included randomized controlled trials (RCTs), controlled trials, cohort studies, case series, and cross-sectional studies that reported mean levels of cytokines in the circulation thought to be relevant for sepsis pathogenesis. We also evaluated concentrations of these cytokines in healthy individuals. The Quality in Prognosis Studies tool was used to assess the methodological quality of included studies. We extracted summary data from published reports. Data analyses were performed using a random-effects model to estimate pooled odds ratios (OR) with 95% confidence intervals for cytokine levels and mortality. This systematic review is registered in PROSPERO (CRD42020179800).

FINDINGS

We identified 3654 records, and 104 studies were included with a total of 3250 participants. The pooled estimated mean TNFα concentration in sepsis patients was 58.4 pg/ml (95% Confidence Interval or CI 39.8-85.8 pg/ml), and in healthy individuals was 5.5 pg/ml (95% CI 3.8-8.0 pg/ml). Pooled estimate means for IL-1β and IFN-γ in sepsis patients were 21.8 pg/ml and 63.3 pg/ml, respectively. Elevated TNFα concentrations associated with increased 28-day sepsis mortality (p = 0.001). In subgroup analyses, we did not detect an association between TNFα levels and sepsis source, sepsis severity, or sequential organ failure assessment (SOFA) score. A TNF-α cutoff level ≥14.7 pg/ml separated sepsis patients from healthy individuals with a sensitivity of 82.6%, a specificity of 91.7%, and a likelihood ratio of 9.9.

INTERPRETATION

Sepsis mean TNFα concentration is increased approximately 10-fold compared to mean concentration in healthy individuals, and TNFα associated with sepsis mortality but not sepsis severity. The concept that elevated cytokines cause sepsis should be revisited in the context of these data.

FUNDING

None.

Blocking P2X7 receptor with AZ 10606120 exacerbates vascular hyperpermeability and inflammation in murine polymicrobial sepsis

Sepsis is a devastating disease with high morbidity and mortality and no specific treatments. The pathophysiology of sepsis involves a hyperinflammatory response and release of damage-associated molecular patterns (DAMPs), including adenosine triphosphate (ATP), from activated and dying cells. Purinergic receptors activated by ATP have gained attention for their roles in sepsis, which can be pro- or anti-inflammatory depending on the context. Current data regarding the role of ATP-specific purinergic receptor P2X7 (P2X7R) in vascular function and inflammation during sepsis are conflicting, and its role on the endothelium has not been well characterized. In this study, we hypothesized that the P2X7R antagonist AZ 10606120 (AZ106) would prevent endothelial dysfunction during sepsis. As proof of concept, we first demonstrated the ability of AZ106 (10 µM) to prevent endothelial dysfunction in intact rat aorta in response to IL-1β, an inflammatory mediator upregulated during sepsis. Likewise, blocking P2X7R with AZ106 (10 µg/g) reduced the impairment of endothelial-dependent relaxation in mice subjected to intraperitoneal injection of cecal slurry (CS), a model of polymicrobial sepsis. However, contrary to our hypothesis, AZ106 did not improve microvascular permeability or injury, lung apoptosis, or illness severity in mice subjected to CS. Instead, AZ106 elevated spleen bacterial burden and circulating inflammatory markers. In conclusion, antagonism of P2X7R signaling during sepsis appears to disrupt the balance between its roles in inflammatory, antimicrobial, and vascular function.

LBP Protects Hepatocyte Mitochondrial Function Via the PPAR-CYP4A2 Signaling Pathway in a Rat Sepsis Model

OBJECTIVES

To explore the role of LPS binding protein (LBP) in metabolism and optimize sepsis treatment.

DESIGN

A sepsis model was established by injecting LPS into LBP-/- rats and WT rats and observing changes in the liver over time (0, 1, 6, and 24 h).

SETTING

Detecting liver inflammation and injury. Optimizing the treatment of sepsis.

SUBJECTS

WT rats and LBP-/- rats.

INTERVENTIONS

We established a sepsis model by injecting LPS intravenously.

MEASUREMENTS AND MAIN RESULTS

First, we induced sepsis in WT and LBP-/- rats with LPS. The rats were sacrificed, and serum and liver samples were collected at 1, 6, and 24 h after LPS injection. We found that the deletion of LBP reduced LPS-induced liver inflammation and injury at 1 and 6 h. Ballooning degeneration was clearly present in LBP-/- rat livers at 24 h after LPS injection. We found that mitochondrial damage and reactive oxygen species (ROS) levels were higher in LBP-/- rat livers than in WT rat livers at 24 h after LPS injection. According to the transcriptomic results, the peroxisome proliferator-activated receptor (PPAR) pathway may be the reason for lesions in LBP-/- rats. To further investigate the function of PPARα in sepsis, we inhibited mTOR with rapamycin and examined mitochondrial injury and ROS levels. The levels of mitochondrial damage and ROS were reduced after LBP-/- rats were pretreated with rapamycin in the context of LPS-induced sepsis. Inhibiting CYP4a2, one of the PPARα-target gene products, reduced the level of LPS-induced ROS in LBP-/- rats.

CONCLUSION

LBP protects hepatic mitochondria against LPS-induced damage via the LBP-PPARα-CYP4a2 signaling pathway.

Design of abiotic polymer ligand-decorated lipid nanoparticles for effective neutralization of target toxins in the blood

Macromolecular toxins often induce inflammatory cytokine production, multiple-organ dysfunction, and cell death. Synthetic polymer ligands (PLs) prepared with several functional monomers have the potential of neutralizing target toxins after binding to them; therefore, they are of significant interest as abiotic antidotes. Although PLs show little toxin neutralization effect in the bloodstream because of immediate elimination from there, the toxin neutralization effect is significantly improved by the direct decoration of PLs onto lipid nanoparticles (PL-LNPs). However, this direct decoration decreases PL mobility, induces LNP aggregation after capturing the target, and decreases LNP blood circulation time. We designed novel PL-LNPs to improve PL mobility, inhibit the aggregation tendency after capturing the target, and increase LNP blood circulation time in order to achieve highly effective toxin neutralization in vivo. Specifically, LNPs were modified with PLs-conjugated polyethylene glycol (PEG), and additional PEG was used to modify the PL-decorated LNPs (PL-PEG-LNPs). Histones were used as target toxins, and N-isopropylacrylamide-based PLs were used for histone capture. PEGylation increased the plasma LNP level 24 h after intravenous injection by ∼90 times and inhibited LNP aggregation after histone capture. The dissociation constant (K_d) of PL-PEG-LNPs against histone was two times smaller compared to that of PL-LNPs. Although PL-LNPs inhibited histone-platelet interaction in the bloodstream, a large amount of histone-PL-LNP complexes accumulated in the lungs because of aggregation. However, PL-PEG-LNPs inhibited both histone-platelet interaction and histone accumulation in the lungs. Importantly, PL-PEG-LNP treatment increased the survival rate of histone-treated mice compared to PL-LNPs. These results provide a platform for the development of abiotic antidote nanoparticles in vivo.

Thiosulfinate-Enriched Allium sativum Extract as an Adjunct to Antibiotic Treatment of Sepsis in a Rat Peritonitis Model

Up to now, there are no studies that have shown a decrease in morbidity and mortality in the context of sepsis and septic shock, except for antibiotic therapy and the objective-guided resuscitation strategy. The goal was to evaluate the use of thiosulfinate-enriched Allium sativum extract (TASE) as an adjuvant in the management of sepsis. An experimental in vivo study was carried out with male Sprague Dawley® rats. Animals were randomized in three treatment groups: the control group (I), antibiotic (ceftriaxone) treatment group (II) and ceftriaxone plus TASE treatment group (III). All animals were housed and inoculated with 1 × 1010 CFU/15 mL of intraperitoneal Escherichia coli ATCC 25922. Subsequently, they received a daily treatment according to each group for 7 days. Clinical, analytical, microbiological, and histopathological parameters were evaluated. Statistically significant clinical improvement was observed in the ceftriaxone plus TASE vs. ceftriaxone group in weight, ocular secretions, whiskers separation and physical activity level (p ≤ 0.05). When comparing interleukins on the third day of treatment between II and III, we found statistically significant differences in IL-1 levels (p < 0.05). Blood and peritoneal liquid cultures of group I were positive for multisensitive E. coli. Group II and III cultures were negative for E. coli, although an overgrowth of Enterococcus faecalis was found. In conclusion, TASE used as an adjuvant to antibiotic treatment in the management of sepsis could improve response profiles with sepsis attenuation, thus reducing overall mortality after an animal peritonitis model.

Antimicrobial peptide LL-37 ameliorates a murine sepsis model via the induction of microvesicle release from neutrophils

Sepsis is a life-threatening disease caused by systemic dys-regulated inflammatory response to infection. We previously revealed that LL-37, a human cathelicidin antimicrobial peptide, improves the survival of cecal ligation and puncture septic mice. Ectosomes, microvesicles released from neutrophils, are reported to be elevated in sepsis survivors; however, the functions of ectosomes in sepsis remain largely unknown. Therefore, we herein elucidated the protective action of LL-37 on sepsis, by focusing on LL-37-induced ectosome release in a cecal ligation and puncture model. The results demonstrated the enhancement of ectosome levels by LL-37 administration, accompanied by a reduction of bacterial load. Importantly, ectosomes isolated from LL-37-injected cecal ligation and puncture mice contained higher amounts of antimicrobial proteins/peptides and exhibited higher antibacterial activity, compared with those from PBS-injected cecal ligation and puncture mice, suggesting that LL-37 induces the release of ectosomes with antibacterial potential in vivo. Actually, LL-37 stimulated mouse bone-marrow neutrophils to release ectosomes ex vivo, and the LL-37-induced ectosomes possessed antibacterial potential. Furthermore, administration of LL-37-induced ectosomes reduced the bacterial load and improved the survival of cecal ligation and puncture mice. Together these observations suggest LL-37 induces the release of antimicrobial ectosomes in cecal ligation and puncture mice, thereby reducing the bacterial load and protecting mice from lethal septic conditions.

The Metabolic Basis of Immune Dysfunction Following Sepsis and Trauma

Critically ill, severely injured and high-risk surgical patients are vulnerable to secondary infections during hospitalization and after hospital discharge. Studies show that the mitochondrial function and oxidative metabolism of monocytes and macrophages are impaired during sepsis. Alternatively, treatment with microbe-derived ligands, such as monophosphoryl lipid A (MPLA), peptidoglycan, or β-glucan, that interact with toll-like receptors and other pattern recognition receptors on leukocytes induces a state of innate immune memory that confers broad-spectrum resistance to infection with common hospital-acquired pathogens. Priming of macrophages with MPLA, CPG oligodeoxynucleotides (CpG ODN), or β-glucan induces a macrophage metabolic phenotype characterized by mitochondrial biogenesis and increased oxidative metabolism in parallel with increased glycolysis, cell size and granularity, augmented phagocytosis, heightened respiratory burst functions, and more effective killing of microbes. The mitochondrion is a bioenergetic organelle that not only contributes to energy supply, biosynthesis, and cellular redox functions but serves as a platform for regulating innate immunological functions such as production of reactive oxygen species (ROS) and regulatory intermediates. This review will define current knowledge of leukocyte metabolic dysfunction during and after sepsis and trauma. We will further discuss therapeutic strategies that target leukocyte mitochondrial function and might have value in preventing or reversing sepsis- and trauma-induced immune dysfunction.

Monophosphoryl lipid A pretreatment suppresses sepsis- and LPS-induced proinflammatory cytokine production in the medullary thick ascending limb

Sepsis is the leading cause of acute kidney injury in critically ill patients. Tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of septic kidney injury; however, the sites and mechanisms of renal TNF-α production during sepsis remain to be defined. In the present study, we showed that TNF-α expression is increased in medullary thick ascending limbs (MTALs) of mice with sepsis induced by cecal ligation and puncture. Treatment with lipopolysaccharide (LPS) for 3 h in vitro also increased MTAL TNF-α production. Sepsis and LPS increased MTAL TNF-α expression through activation of the myeloid differentiation factor 88 (MyD88)-IL-1 receptor-associated kinase 1-ERK signaling pathway. Pretreatment with monophosphoryl lipid A (MPLA), a nontoxic immunomodulator that protects against bacterial infection, eliminated the sepsis- and LPS-induced increases in MTAL TNF-α production. The suppressive effect of MPLA on TNF-α was mediated through activation of a phosphatidylinositol 3-kinase-dependent pathway that inhibits MyD88-dependent ERK activation. This likely involves MPLA-phosphatidylinositol 3-kinase-mediated induction of Tollip, which negatively regulates the MyD88-ERK pathway by inhibiting activation of IL-1 receptor-associated kinase 1. These regulatory mechanisms are similar to those previously shown to mediate the effect of MPLA to prevent sepsis-induced inhibition of MTAL [Formula: see text] absorption. These results identify the MTAL as a site of local TNF-α production in the kidney during sepsis and identify molecular mechanisms that can be targeted to attenuate renal TNF-α expression. The ability of MPLA pretreatment to suppress MyD88-dependent ERK signaling in the MTAL during sepsis has the dual beneficial effects of protecting tubule transport functions and attenuating harmful proinflammatory responses.

The Pathogenesis of Sepsis and Potential Therapeutic Targets

Sepsis is defined as “a life-threatening organ dysfunction caused by a host’s dysfunctional response to infection”. Although the treatment of sepsis has developed rapidly in the past few years, sepsis incidence and mortality in clinical treatment is still climbing. Moreover, because of the diverse manifestations of sepsis, clinicians continue to face severe challenges in the diagnosis, treatment, and management of patients with sepsis. Here, we review the recent development in our understanding regarding the cellular pathogenesis and the target of clinical diagnosis of sepsis, with the goal of enhancing the current understanding of sepsis. The present state of research on targeted therapeutic drugs is also elaborated upon to provide information for the treatment of sepsis.

Inhibition of transmembrane TNF-α shedding by a specific antibody protects against septic shock

Transmembrane TNF-α (tmTNF-α) and secretory TNF-α (sTNF-α) display opposite effects in septic shock. Reducing tmTNF-α shedding can offset the detrimental effects of sTNF-α and increase the beneficial effect of tmTNF-α. We previously developed a monoclonal antibody that is specific for tmTNF-α and does not cross-react with sTNF-α. In this study, we show that this antibody can specifically suppress tmTNF-α shedding by competing with a TNF-α converting enzyme that cleaves the tmTNF-α ectodomain to release sTNF-α. This tmTNF-α antibody significantly inhibited LPS-induced secretion of interleukin (IL)-1β, IL-6, interferon-β, and nitric oxide by monocytes/macrophages, and protected mice from septic shock induced by lipopolysaccharide (LPS) or cecal ligation and puncture, while reducing the bacterial load. The mechanism associated with the protective effect of this tmTNF-α antibody involved promotion of LPS-induced toll-like receptor 4 (TLR4) internalization and degradation by recruiting Triad3A to TLR4. Moreover, the tmTNF-α antibody inhibited LPS-induced activation of nuclear factor-κB and interferon regulatory factor 3 pathways by upregulating expression of A20 and monocyte chemotactic protein-induced protein 1. Similarly, treatment of macrophages with exogenous tmTNF-α suppressed LPS/TLR4 signaling and release of proinflammatory cytokines, indicating that increased levels of tmTNF-α promoted by the antibody contributed to its inhibitory effect. Thus, use of this tmTNF-α antibody for specific suppression of tmTNF-α shedding may be a promising strategy to treat septic shock.

Cargo-less nanoparticles program innate immune cell responses to toll-like receptor activation

Developing biomaterials to control the responsiveness of innate immune cells represents a clinically relevant approach to treat diseases with an underlying inflammatory basis, such as sepsis. Sepsis can involve activation of Toll-like receptor (TLR) signaling, which activates numerous inflammatory pathways. The breadth of this inflammation has limited the efficacy of pharmacological interventions that target a single molecular pathway. Here, we developed cargo-less particles as a single-agent, multi-target platform to elicit broad anti-inflammatory action against innate immune cells challenged by multiple TLR agonists. The particles, prepared from poly(lactic-co-glycolic acid) (PLGA) and poly(lactic acid) (PLA), displayed potent molecular weight-, polymer composition-, and charge-dependent immunomodulatory properties, including downregulation of TLR-induced costimulatory molecule expression and cytokine secretion. Particles prepared using the anionic surfactant poly(ethylene-alt-maleic acid) (PEMA) significantly blunted the responses of antigen presenting cells to TLR4 (lipopolysaccharide) and TLR9 (CpG-ODN) agonists, demonstrating broad inhibitory activity to both extracellular and intracellular TLR ligands. Interestingly, particles prepared using poly(vinyl alcohol) (PVA), a neutrally-charged surfactant, only marginally inhibited inflammatory cytokine secretions. The biochemical pathways modulated by particles were investigated using TRanscriptional Activity CEll aRrays (TRACER), which implicated IRF1, STAT1, and AP-1 in the mechanism of action for PLA-PEMA particles. Using an LPS-induced endotoxemia mouse model, administration of PLA-PEMA particles prior to or following a lethal challenge resulted in significantly improved mean survival. Cargo-less particles affect multiple biological pathways involved in the development of inflammatory responses by innate immune cells and represent a potentially promising therapeutic strategy to treat severe inflammation.

Protective Effect of Melatonin Against Polymicrobial Sepsis Is Mediated by the Anti-bacterial Effect of Neutrophils

Sepsis is an infection- or toxin-mediated systemic inflammatory syndrome. Previous studies have shown that melatonin, the primary hormone produced by the pineal gland, attenuates the effect of polymicrobial infection-mediated septic shock in animals. However, the mechanism of the anti-septic effect of melatonin during polymicrobial infection has not been well-studied. In this study, we investigated how melatonin protects mice from polymicrobial sepsis. Melatonin treatment inhibited peripheral tissue inflammation and tissue damage in a cecal ligation puncture (CLP)-induced polymicrobial sepsis model, consequently reducing the mortality of the mice. We found that macrophages and neutrophils expressed melatonin receptors. Upon depletion of neutrophils, melatonin-induced protection against polymicrobial infection failed in the mice, but melatonin treatment in macrophage-depleted mice attenuated the mice mortality resulting from polymicrobial sepsis. Moreover, melatonin treatment promoted the development of the neutrophil extracellular trap (NET), which contributed to anti-bacterial activity during polymicrobial infection, whereas the phagocytic activities of neutrophils were inhibited by melatonin. The data from this study support previously unexplained antiseptic effects of melatonin during a polymicrobial infection and could be potentially useful for human patients with sepsis.

Lactate-induced activation of HCA2 improves survival in mice with sepsis

Sepsis is characterized by systemic inflammation that is caused by infection and by activation of proinflammatory pathways, resulting in mitochondrial and cellular dysfunction leading to multiorgan failure. Here, we show the following: 1) in peritoneal immune cells, particularly macrophages, from mice that have undergone cecal ligation and puncture (CLP), hydroxycarboxylic acid receptor 2 (HCA2) expression increased in parallel with proinflammatory cytokines; 2) post-CLP survival rates of Hca2^-/- knockout mice (n = 22) were lower than those of wild-type (WT) mice (n = 15) (P < 0.011), which is suggestive of a protective role for HCA2 in sepsis; 3) WT mice subjected to CLP-induced sepsis and treated with lactated Ringer's solution (LR, n = 13) survived longer than those treated with normal saline (n = 14; P < 0.027); 4) LR treatment of CLP-induced sepsis reduced proinflammatory cytokine expression in CD11b⁺F4/80⁺ macrophages and promoted M2-like polarization; 5) HCA2 was expressed by kidney in the setting of sepsis, but not by normal kidneys; 6) LR administration attenuated sepsis-associated acute kidney injury (AKI), partly restored expression of the key regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor γ coactivator 1α (P < 0.03), and reduced proinflammatory cytokine production (TNF-α, P < 0.04; IL-1β, P < 0.006; IL-6, P < 0.03). Our data suggest that lactate-induced activation of HCA2 during sepsis activates a negative feedback loop to attenuate the inflammatory response. The data further suggest that fluid resuscitation with LR may benefit patients with sepsis, particularly those with sepsis-associated AKI treated with potentially lactate-depleting renal replacement therapies.-Takakura, A., Zandi-Nejad, K. Lactate-induced activation of HCA2 improves survival in mice with sepsis.

Tolerizing CTL by Sustained Hepatic PD-L1 Expression Provides a New Therapy Approach in Mouse Sepsis

Cytotoxic T lymphocyte (CTL) activation contributes to liver damage during sepsis, but the mechanisms involved are largely unknown. Understanding the underlying principle will permit interference with CTL activation and thus, provide a new therapeutic option. Methods: To elucidate the mechanism leading to CTL activation we used the Hepa1-6 cell line in vitro and the mouse model of in vivo polymicrobial sepsis, following cecal-ligation and -puncture (CLP) in wildtype, myeloid specific NOX-2, global NOX2 and NOX4 knockout mice, and their survival as a final readout. In this in vivo setting, we also determined hepatic mRNA and protein expression as well as clinical parameters of liver damage - aspartate- and alanine amino-transaminases. Hepatocyte specific overexpression of PD-L1 was achieved in vivo by adenoviral infection and transposon-based gene transfer using hydrodynamic injection. Results: We observed downregulation of PD-L1 on hepatocytes in the murine sepsis model. Adenoviral and transposon-based gene transfer to restore PD-L1 expression, significantly improved survival and reduced the release of liver damage, as PD-L1 is a co-receptor that negatively regulates T cell function. Similar protection was observed during pharmacological intervention using recombinant PD-L1-Fc. N-acetylcysteine blocked the downregulation of PD-L1 suggesting the involvement of reactive oxygen species. This was confirmed in vivo, as we observed significant upregulation of PD-L1 expression in NOX4 knockout mice, following sham operation, whereas its expression in global as well as myeloid lineage NOX2 knockout mice was comparable to that in the wild type animals. PD-L1 expression remained high following CLP only in total NOX2 knockouts, resulting in significantly reduced release of liver damage markers. Conclusion: These results suggest that, contrary to common assumption, maintaining PD-L1 expression on hepatocytes improves liver damage and survival of mice during sepsis. We conclude that administering recombinant PD-L1 or inhibiting NOX2 activity might offer a new therapeutic option in sepsis.

Sepsis Induced by Cecal Ligation and Puncture

Despite advances in intensive care unit interventions, including the use of specific antibiotics and anti-inflammation treatment, sepsis with concomitant multiple organ failure is the most common cause of death in many acute care units. In order to understand the mechanisms of clinical sepsis and develop effective therapeutic modalities, there is a need to use effective experimental models that faithfully replicate what occurs in patients with sepsis. Several models are commonly used to study sepsis, including intravenous endotoxin challenge, injection of live organisms into the peritoneal cavity, establishing abscesses in the extremities, and the induction of experimental polymicrobial peritonitis via cecal ligation and puncture (CLP). Here, we describe the surgical procedure of CLP in mice, which has been demonstrated to closely replicate the nature and course of clinical sepsis in human subjects.

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

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

Monoterpenes modulating cytokines - A review

Inflammatory response can be driven by cytokine production and is a pivotal target in the management of inflammatory diseases. Monoterpenes have shown that promising profile as agents which reduce the inflammatory process and also modulate the key chemical mediators of inflammation, such as pro and anti-inflammatory cytokines. The main interest focused on monoterpenes were to develop the analgesic and anti-inflammatory drugs. In this review, we summarized current knowledge on monoterpenes that produce anti-inflammatory effects by modulating the release of cytokines, as well as suggesting that which monoterpenoid molecules may be most effective in the treatment of inflammatory disease. Several different inflammatory markers were evaluated as a target of monoterpenes. The proinflammatory and anti-inflammatory cytokines were found TNF-α, IL-1β, IL-2, IL-5, IL-4, IL-6, IL-8, IL-10, IL-12 IL-13, IL-17A, IFNγ, TGF-β1 and IFN-γ. Our review found evidence that NF-κB and MAPK signaling are important pathways for the anti-inflammatory action of monoterpenes. We found 24 monoterpenes that modulate the production of cytokines, which appears to be the major pharmacological mechanism these compounds possess in relation to the attenuation of inflammatory response. Despite the compelling evidence supporting the anti-inflammatory effect of monoterpenes, further studies are necessary to fully explore their potential as anti-inflammatory compounds.

The impact of immobilisation and inflammation on the regulation of muscle mass and insulin resistance: different routes to similar end-points

Loss of muscle mass and insulin sensitivity are common phenotypic traits of immobilisation and increased inflammatory burden. The suppression of muscle protein synthesis is the primary driver of muscle mass loss in human immobilisation, and includes blunting of post‐prandial increases in muscle protein synthesis. However, the mechanistic drivers of this suppression are unresolved. Immobilisation also induces limb insulin resistance in humans, which appears to be attributable to the reduction in muscle contraction per se. Again mechanistic insight is missing such that we do not know how muscle senses its “inactivity status” or whether the proposed drivers of muscle insulin resistance are simply arising as a consequence of immobilisation. A heightened inflammatory state is associated with major and rapid changes in muscle protein turnover and mass, and dampened insulin‐stimulated glucose disposal and oxidation in both rodents and humans. A limited amount of research has attempted to elucidate molecular regulators of muscle mass loss and insulin resistance during increased inflammatory burden, but rarely concurrently. Nevertheless, there is evidence that Akt (protein kinase B) signalling and FOXO transcription factors form part of a common signalling pathway in this scenario, such that molecular cross‐talk between atrophy and insulin signalling during heightened inflammation is believed to be possible. To conclude, whilst muscle mass loss and insulin resistance are common end‐points of immobilisation and increased inflammatory burden, a lack of understanding of the mechanisms responsible for these traits exists such that a substantial gap in understanding of the pathophysiology in humans endures.

Independent risk factors for postoperative AKI and the impact of the AKI on 30-day postoperative outcomes in patients with type A acute aortic dissection: an updated meta-analysis and meta-regression

Background

This meta-analysis aims to investigate the effects of postoperative acute kidney injury (AKI) on 30-day postoperative outcomes and the independent risk factors for postoperative AKI in patients with type A acute aortic dissection (TAAD).

Methods

Relevant reports published between January 1, 2011 and May 31, 2017 were searched in multiple electronic literature databases. A total of seven eligible articles were included in the meta-analysis.

Results

Postoperative AKI was associated with 249% increase in 30-day postoperative mortality [odds ratio (OR): 3.49; 95% confidence interval (CI): 2.17-5.59; P<0.0001]. Subgroup analysis revealed that patients with stage II/III AKI showed 445% increase in 30-day postoperative mortality compared with the control group (OR: 5.45; 95% CI: 2.87-10.36; P<0.0001). Postoperative AKI was also associated with 143%, 432%, and 126% increase in the incidences of 30-day postoperative stroke, bleeding, and respiratory complications, respectively. Notably, high body mass index (BMI), advanced age, and perioperative sepsis were independent risk factors for postoperative AKI in patients with TAAD.

Conclusions

This meta-analysis firstly provided clinical evidence showing the adverse effects of postoperative AKI on 30-day postoperative outcomes in patients with TAAD and identified high BMI, advanced age, and perioperative sepsis as the independent risk factors for postoperative AKI. These findings suggest that preventive or therapeutic methods to effectively manage postoperative AKI may improve 30-day postoperative outcomes in patients with TAAD.

Tumour Necrosis Factor-alpha and Nuclear Factor-kappa B Gene Variants in Sepsis

Background:

The humoral system is activated and various cytokines are released due to infections in tissues and traumatic damage. Nuclear factor-kappa B dimers are encoded by nuclear factor-kappa B genes and regulate transcription of several crucial proteins of inflammation such as tumour necrosis factor-alpha.

Aims:

To investigate the possible effect of polymorphisms on tumour necrosis factor-alpha serum levels with clinical and prognostic parameters of sepsis by determining the nuclear factor-kappa B-1-94 ins/del ATTG and tumour necrosis factor-alpha (-308 G/A) gene polymorphisms and tumour necrosis factor-alpha serum levels.

Study Design:

Case-control study.

Methods:

Seventy-two patients with sepsis and 104 healthy controls were included in the study. In order to determine the polymorphisms of nuclear factor-kappa B-1-94 ins/del ATTG and tumour necrosis factor-alpha (-308 G/A), polymerase chain reaction–restriction fragment length polymorphism analysis was performed and serum tumour necrosis factor-alpha levels were determined using an enzyme-linked immunosorbent assay.

Results:

We observed no significant differences in tumour necrosis factor-alpha serum levels between the study groups. In the patient group, an increase in the tumour necrosis factor-alpha serum levels in patients carrying the tumour necrosis factor-alpha (-308 G/A) A allele compared to those without the A allele was found to be statistically significant. Additionally, an increase in the tumour necrosis factor-alpha serum levels in patients carrying tumour necrosis factor-alpha (-308 G/A) AA genotype compared with patients carrying the AG or GG genotypes was statistically significant. No significant differences were found in these 2 polymorphisms between the patient and control groups (p>0.05).

Conclusion:

Our results showed the AA genotype and the A allele of the tumour necrosis factor-alpha (-308 G/A) polymorphism may be used as a predictor of elevated tumour necrosis factor-alpha levels in patients with sepsis.

Lipopolysaccharide inhibits myogenic differentiation of C2C12 myoblasts through the Toll-like receptor 4-nuclear factor-κB signaling pathway and myoblast-derived tumor necrosis factor-α

Background

Circulating lipopolysaccharide (LPS) concentrations are often elevated in patients with sepsis or with various endogenous diseases that are associated with metabolic endotoxemia. Involuntary loss of skeletal muscle, termed muscle wasting, is commonly observed in these conditions, suggesting that circulating LPS might play an essential role in its development. Although impairment of muscle regeneration is an important determinant of skeletal muscle wasting, it is unclear whether LPS affects this process and, if so, by what mechanism. Here, we used the C2C12 myoblast cell line to investigate the effects of LPS on myogenesis.

Methods

C2C12 myoblasts were grown to 80% confluence and induced to differentiate in the absence or presence of LPS (0.1 or 1 μg/mL); TAK-242 (1 μM), a specific inhibitor of Toll-like receptor 4 (TLR4) signaling; and a tumor necrosis factor (TNF)-α neutralizing antibody (5 μg/mL). Expression of a skeletal muscle differentiation marker (myosin heavy chain II), two essential myogenic regulatory factors (myogenin and MyoD), and a muscle negative regulatory factor (myostatin) was analyzed by western blotting. Nuclear factor-κB (NF-κB) DNA-binding activity was measured using an enzyme-linked immunosorbent assay.

Results

LPS dose-dependently and significantly decreased the formation of multinucleated myotubes and the expression of myosin heavy chain II, myogenin, and MyoD, and increased NF-κB DNA-binding activity and myostatin expression. The inhibitory effect of LPS on myogenic differentiation was reversible, suggesting that it was not caused by nonspecific toxicity. Both TAK-242 and anti-TNF-α reduced the LPS-induced increase in NF-κB DNA-binding activity, downregulation of myogenic regulatory factors, and upregulation of myostatin, thereby partially rescuing the impairment of myogenesis.

Conclusions

Our data suggest that LPS inhibits myogenic differentiation via a TLR4–NF-κB-dependent pathway and an autocrine/paracrine TNF-α-induced pathway. These pathways may be involved in the development of muscle wasting caused by sepsis or metabolic endotoxemia.

Immune therapeutic strategies using optimal controls with L1 and L2 type objectives

Therapeutic strategies to correct an excessive immune response to pathogenic infection is investigated as an optimal control problem. The control problem is formulated around a four dimensional mathematical model describing the inflammatory response to a pathogenic insult with two therapeutic control inputs which have either a direct pro- or anti-inflammatory effect in the given system. We use Pontryagin's maximum principle and discuss necessary optimality conditions. We consider both an L¹ type objective functional as well as an L² type objective. For the former, the presence of singular control will be addressed. For each case, numerical simulations using a nonlinear programming optimization solver to acquire different drug treatment strategies are presented and discussed. The results provide insight for possible treatment strategies and the methods could be a relevant tool for future practice to assist in better prediction of clinical outcomes and subsequently better treatment for patients.

Pterostilbene alleviates polymicrobial sepsis-induced liver injury: Possible role of SIRT1 signaling

Liver injury occurs frequently during sepsis. Pterostilbene (Pte), a natural dimethylated analog of resveratrol from blueberries, exerts anti-inflammatory and anti-apoptotic effects in various diseases. However, the role of Pte in sepsis-induced liver injury and its underlying mechanisms remain unknown. The current study aimed to evaluate the protective effects of Pte on sepsis-induced liver injury and its potential mechanisms. Sepsis was induced using cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were administered Pte (5, 10, 15mg/kg, i.p.) at 0.5h, 2h, and 8h after CLP induction. The pathological changes of the liver were evaluated using hematoxylin and eosin (H&E) staining. The serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL-6), myeloperoxidase (MPO), p38 mitogen-activated protein kinase (p38MAPK), Bax, and B-cell lymphoma 2 (Bcl-2) were also evaluated. Pte treatment attenuated the CLP-induced liver injury, as evidenced by the attenuated histopathologic injuries and the decreased serum aminotransferase levels. Pte reduced the serum inflammatory cytokine (TNF-α and IL-6) levels and hepatic mRNA levels of TNF-α and IL-6. Pte also reduced MPO activity and p38MAPK activation in the liver. Additionally, Pte significantly inhibited Bax expression and increased Bcl-2 expression. Moreover, Pte increased the expression of sirtuin-1 (SIRT1) and reduced the expression of acetylated forkhead box O1 (Ac-FoxO1), acetylated Ac-p53, and acetylated nuclear factor-kappa beta (Ac-NF-κB). However, SIRT1 small interfering RNA (siRNA) abolished Pte's effects on the expression levels of those protein. Notably, Pte improved the survival rate in septic mice. In conclusion, Pte alleviates sepsis-induced liver injury by reducing inflammatory response and inhibiting hepatic apoptosis, and the potential mechanism is associated with SIRT1 signaling activation.

Astragaloside IV Alleviates Lipopolysaccharide-Induced Acute Kidney Injury Through Down-Regulating Cytokines, CCR5 and p-ERK, and Elevating Anti-Oxidative Ability

Background

Astragaloside IV (AS-IV) has been shown to prevent ischemia-induced acute kidney injury (AKI) in rat models of ischemia and reperfusion. However, the effects of AS-IV on AKI during sepsis and endotoxinemia is unclear. The current study aimed to investigate the effects and molecular mechanisms of AS-IV on lipopolysaccharide (LPS)-induced AKI.

Material/Methods

Adult male CD-1 mice were randomly assigned into 6 groups (n=8/group): control group: mice were intraperitoneally (i.p.) injected with normal saline; LPS group (10 mg/kg, i.p.); low-dose AS-IV (25 mg/kg; gavage for 7 days) + LPS (i.p., 1 hour after last gavage) group; medial-dose AS-IV (50 mg/kg) + LPS group; high-dose AS-IV (100 mg/kg) + LPS group; high-dose AS-IV alone (100 mg/kg; gavage for 7 days) group. Blood samples were collected at 24 hours after LPS injection, and plasma uric acid and BUN were measured with colorimetric detection kits. The concentration of plasma tumor necrosis factor (TNF)-α and interleukin 1β, renal p-extracellular signal-regulated kinases, and urinary albumin were evaluated by ELISA. The expression of CCR5 in renal tissue was evaluated by PCR and Western blotting. Concentrations of glutathione (GSH) and reactive oxygen species (ROS) in renal tissue were also measured.

Results

AS-IV decreased LPS-stimulated production of blood TNF-α and IL-6, LPS-induced the expression of CCR5, and activation of ERK in the kidneys in a rodent model of endotoxinemia. AS-IV attenuated LPS-caused decreased GSH and increased ROS. It also attenuated LPS-induced increases in plasma uric acid, BUN, and urinary albumin.

Conclusions

AS-IV protects against AKI during bacterial endotoxinemia by attenuating expression of cytokines, CCR5, and p-ERK, and elevating anti-oxidative ability.

The Cytokine Response to Lipopolysaccharide Does Not Predict the Host Response to Infection

The magnitude of the LPS-elicited cytokine response is commonly used to assess immune function in critically ill patients. A suppressed response, known as endotoxin tolerance, is associated with worse outcomes, yet endotoxin tolerance-inducing TLR4 ligands are known to protect animals from infection. Thus, it remains unknown whether the magnitude of the LPS-elicited cytokine response provides an accurate assessment of antimicrobial immunity. To address this, the ability of diverse TLR ligands to modify the LPS-elicited cytokine response and resistance to infection were assessed. Priming of mice with LPS, monophosphoryl lipid A (MPLA), or poly(I:C) significantly reduced plasma LPS-elicited proinflammatory cytokines, reflecting endotoxin tolerance, whereas CpG-ODN-primed mice showed augmented cytokine production. In contrast, LPS, MPLA, and CpG-ODN, but not poly(I:C), improved the host response to a Pseudomonas aeruginosa infection. Mice primed with protective TLR ligands, including CpG-ODN, showed reduced plasma cytokines during P. aeruginosa infection. The protection imparted by TLR ligands persisted for up to 15 d yet was independent of the adaptive immune system. In bone marrow-derived macrophages, protective TLR ligands induced a persistent metabolic phenotype characterized by elevated glycolysis and oxidative metabolism as well as augmented size, granularity, phagocytosis, and respiratory burst. Sustained augmentation of glycolysis in TLR-primed cells was dependent, in part, on hypoxia-inducible factor 1-α and was essential for increased phagocytosis. In conclusion, the magnitude of LPS-elicited cytokine production is not indicative of antimicrobial immunity after exposure to TLR ligands. Additionally, protective TLR ligands induce sustained augmentation of phagocyte metabolism and antimicrobial function.

The total alkaloid fraction of bulbs of Fritillaria cirrhosa displays anti-inflammatory activity and attenuates acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Bulb of Fritillaria cirrhosa D.Don (BFC) has been wildly used in China for a long time for folk medicine since its significant therapeutic effects on respiratory diseases, such as cough, expectoration, pneumonia and bronchial inflammation, which are related to respiratory inflammatory response. However, there is a lack of investigation on the in vivo anti-inflammatory properties of BFC.

AIM OF THE STUDY

The aim of this study was to evaluate the in vivo anti-inflammatory activity of the purified total alkaloid fraction of BFC (TAF) by using different animal models of inflammation to provide scientific evidence for its traditional use.

MATERIALS AND METHODS

The total alkaloid fraction from BFC was prepared by using H-103 resin column. Anti-inflammatory effect of TAF was evaluated by models of acetic acid-induced capillary permeability accentuation, carrageenan-induced rat paw edema, cotton pellet-induced granuloma formation and LPS-induced acute lung injury (ALI). The level of cytokines (TNF, IL-6, IL-4 and IL-10) was measured by ELISA. Histopathological analyses were performed by using hematoxylin and eosin staining.

RESULTS

TAF can inhibit acetic acid-induced capillary permeability accentuation, carrageenan-induced paw edema, cotton pellet-induced granuloma formation, suppress inflammatory cells recruitment and cytokine production in the bronchoalveolar lavage fluid from LPS-induced ALI mice, and attenuate pathological changes in the lung tissues of ALI mice.

CONCLUSION

This study provides scientific evidence for bulb of F. cirrhosa to treat respiratory inflammation.

Pharmacological inhibitors of TRPV4 channels reduce cytokine production, restore endothelial function and increase survival in septic mice

Sepsis is characterized by systemic inflammation, edema formation and hypo-perfusion leading to organ dysfunction and ultimately death. Activation of the transient receptor potential vanilloid type 4 (TRPV4) channel is associated with edema formation and circulatory collapse. Here, we show that TRPV4 channels are involved in the hyper-inflammatory response and mortality associated with sepsis. Pharmacological inhibition of TRPV4 channels in mice reduced mortality in lipopolysaccharide and cecal-ligation-and-puncture models of sepsis, but not in a tumor necrosis factor-α (TNFα)-induced sepsis model. These protective effects of TRPV4 channel inhibition were attributable to prevention of the sepsis-induced surge of a broad spectrum of pro-inflammatory cytokines, including TNFα, interleukin (IL)-1 and IL-6, and subsequent preservation of endothelial cell function, including Ca²⁺ signaling, integrity and endothelium-dependent vasodilation. These results suggest that TRPV4 antagonists may be of therapeutic utility in the management of sepsis.

Review: Infection, fever, and exogenous and endogenous pyrogens: some concepts have changed

For many years, it was thought that bacterial products caused fever via the intermediate production of a host-derived, fever-producing molecule, called endogenous pyrogen (EP). Bacterial products and other fever-producing substances were termed exogenous pyrogens. It was considered highly unlikely that exogenous pyrogens caused fever by acting directly on the hypothalamic thermoregulatory center since there were countless fever-producing microbial products, mostly large molecules, with no common physical structure. In vivo and in vitro, lipopolysaccharides (LPSs) and other microbial products induced EP, subsequently shown to be interleukin-1 (IL-1). The concept of the `endogenous pyrogen' cause of fever gained considerable support when pure, recombinant IL-1 produced fever in humans and in animals at subnanomolar concentrations. Subsequently, recombinant tumor necrosis factor-α (TNF-α), IL-6 and other cytokines were also shown to cause fever and EPs are now termed pyrogenic cytokines. However, the concept was challenged when specific blockade of either IL-1 or TNF activity did not diminish the febrile response to LPS, to other microbial products or to natural infections in animals and in humans. During infection, fever could occur independently of IL-1 or TNF activity. The cytokine-like property of Toll-like receptor (TLR) signal transduction provides an explanation by which any microbial product can cause fever by engaging its specific TLR on the vascular network supplying the thermoregulatory center in the anterior hypothalamus. Since fever induced by IL-1, TNF-α, IL-6 or TLR ligands requires cyclooxygenase-2, production of prostaglandin E2 (PGE 2) and activation of hypothalamic PGE2 receptors provides a unifying mechanism for fever by endogenous and exogenous pyrogens. Thus, fever is the result of either cytokine receptor or TLR triggering; in autoimmune diseases, fever is mostly cytokine mediated whereas both cytokine and TLR account for fever during infection.

Pathogenic, immunologic, and clinical aspects of sepsis - update 2016

INTRODUCTION

Sepsis is a major cause of death worldwide but its orchestrating components remain incompletely understood. On the one hand, development of sepsis results from an infectious focus that cannot be controlled by the immune system, but on the other, responding immune cells that can eliminate the infection inflict damage to the host by contributing to complications such as endothelial leakage, septic shock, and multiorgan failure.

AREAS COVERED

In this review we give a comprehensive overview of how sepsis occurs, which exogenous and endogenous factors might affect the immune-pathophysiological course of sepsis and finally how this knowledge translates into up-to-date definitions and therapeutic approaches. Expert commentary: Although new immunological mechanisms altering the course of sepsis have been identified recently, future research needs to address the limitations of experimental approaches, redirect the research focus into translational approaches, and finally evaluate personalized treatment strategies.

An Agent-Based Model of a Hepatic Inflammatory Response to Salmonella: A Computational Study under a Large Set of Experimental Data

We present an agent-based model (ABM) to simulate a hepatic inflammatory response (HIR) in a mouse infected by Salmonella that sometimes progressed to problematic proportions, known as "sepsis". Based on over 200 published studies, this ABM describes interactions among 21 cells or cytokines and incorporates 226 experimental data sets and/or data estimates from those reports to simulate a mouse HIR in silico. Our simulated results reproduced dynamic patterns of HIR reported in the literature. As shown in vivo, our model also demonstrated that sepsis was highly related to the initial Salmonella dose and the presence of components of the adaptive immune system. We determined that high mobility group box-1, C-reactive protein, and the interleukin-10: tumor necrosis factor-α ratio, and CD4+ T cell: CD8+ T cell ratio, all recognized as biomarkers during HIR, significantly correlated with outcomes of HIR. During therapy-directed silico simulations, our results demonstrated that anti-agent intervention impacted the survival rates of septic individuals in a time-dependent manner. By specifying the infected species, source of infection, and site of infection, this ABM enabled us to reproduce the kinetics of several essential indicators during a HIR, observe distinct dynamic patterns that are manifested during HIR, and allowed us to test proposed therapy-directed treatments. Although limitation still exists, this ABM is a step forward because it links underlying biological processes to computational simulation and was validated through a series of comparisons between the simulated results and experimental studies.

Association between tumor necrosis factor-alpha G-308A polymorphism and dental peri-implant disease risk: A meta-analysis

BACKGROUND

Tumor necrosis factor-alpha (TNF-α) is a potent immune-inflammatory mediator involved in the regulation of bone resorption. The single nucleotide polymorphism G-308A in the TNF-α gene increases the level of this cytokine. This phenomenon is also related to several diseases. Although the association between TNF-α (G-308A) polymorphism and dental peri-implant disease has been investigated, results have remained controversial. Hence, we performed this meta-analysis to provide a comprehensive and systematic conclusion on this topic.

METHODS

We performed a systematic literature search in PubMed, Embase, ISI Web of Science, Cochrane Library, and Chinese National Knowledge Infrastructure until July 2015. A fixed-effect model was established to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs). The calculated values were then used to assess the strength of the association between the TNF-α (G-308A) polymorphism and the dental peri-implant disease risk. The heterogeneity between included studies was evaluated with Cochran Q and I statistics. Interstudy publication bias was investigated with a funnel plot.

RESULTS

Six eligible studies were included in this meta-analysis. The pooled ORs did not reveal a significant relationship between the TNF-α (G-308A) polymorphism and the disease susceptibility. Subgroup analyses in terms of ethnicity and disease type yielded similar results.

CONCLUSION

Our meta-analysis revealed that TNF-α (G-308A) polymorphism was not significantly associated with the risk of dental peri-implant disease. However, further studies with large sample sizes should be performed to verify these results.

Targeting cytokines as a treatment for patients with sepsis: A lost cause or a strategy still worthy of pursuit?

Despite often knowing the aetiology of sepsis and its clinical course there has not been the anticipated advances in treatment strategies. Cytokines are influential mediators of immune/inflammatory reactions and in patients with sepsis high circulating levels are implicated in the onset and perpetuation of organ failure. Antagonising the activities of pro-inflammatory cytokines enhances survival in animal models of sepsis but, so far, such a therapeutic strategy has not improved patient outcome. This article addresses the questions of why encouraging laboratory findings have failed to be translated into successful treatments of critically ill patients and whether modifying cytokine activity still remains a promising avenue for therapeutic advance in severe sepsis. In pursuing this task we have selected reports that we believe provide an incisive, critical and balanced view of the topic.

GADD34 suppresses lipopolysaccharide-induced sepsis and tissue injury through the regulation of macrophage activation

Growth arrest and DNA damage inducible protein 34 (GADD34) is induced by various cellular stresses, such as DNA damage, endoplasmic reticulum stress, and amino-acid deprivation. Although the major roles of GADD34 are regulating ER stress responses and apoptosis, a recent study suggested that GADD34 is linked to innate immune responses. In this report, we investigated the roles of GADD34 in inflammatory responses against bacterial infection. To explore the effects of GADD34 on systemic inflammation in vivo, we employed a lipopolysaccharide (LPS)-induced murine sepsis model and assessed the lethality, serum cytokine levels, and tissue injury in the presence or absence of GADD34. We found that GADD34 deficiency increased the lethality and serum cytokine levels in LPS-induced sepsis. Moreover, GADD34 deficiency enhanced tissue destruction, cell death, and pro-inflammatory cytokine expression in LPS-induced acute liver injury. Pro-inflammatory cytokine production after LPS stimulation is regulated by the Toll-like receptor 4 (TLR4)-mediated NF-κB signaling pathway. In vitro experiments revealed that GADD34 suppressed pro-inflammatory cytokine production by macrophages through dephosphorylation of IKKβ. In conclusion, GADD34 attenuates LPS-induced sepsis and acute tissue injury through suppressing macrophage activation. Targeting this anti-inflammatory role of GADD34 may be a promising area for the development of therapeutic agents to regulate inflammatory disorders.

Wnt5A/Ryk signaling critically affects barrier function in human vascular endothelial cells

Satisfactory therapeutic strategies for septic shock are still missing. Previously we found elevated levels of Wnt5A in patients with severe sepsis and septic shock. Wnt5A is released by activated macrophages but knowledge of its effects in the vascular system remains scant. Here we investigate the response of human coronary artery endothelial cells (HCAEC) to Wnt5A. We used a genome-wide differential expression approach to define novel targets regulated by Wnt5A. Gene ontology analysis of expression profiles revealed clusters of genes involved in actin cytoskeleton remodeling as the predominant targets of Wnt5A. Wnt5A targeted Rho-associated protein serine/threonine kinase (ROCK), leading to phosphorylation of LIM kinase-2 (LIMK2) and inactivation of the actin depolymerization factor cofilin-1 (CFL1). Functional experiments recording cytoskeletal rearrangements in living cells showed that Wnt5A enhanced stress fiber formation as a consequence of reduced actin depolymerization. The antagonist Wnt inhibitory factor 1 (WIF1) that specifically interferes with the WIF domain of Ryk receptors prevented actin polymerization. Wnt5A disrupted β-catenin and VE-cadherin adherens junctions forming inter-endothelial gaps. Functional experiments targeting the endothelial monolayer integrity and live recording of trans-endothelial resistance revealed enhanced permeability of Wnt5A-treated HCAEC. Ryk silencing completely prevented Wnt5A-induced endothelial hyperpermeability. Wnt5A decreased wound healing capacity of HCAEC monolayers; this was restored by the ROCK inhibitor Y-27632. Here we show that Wnt5A acts on the vascular endothelium causing enhanced permeability through Ryk interaction and downstream ROCK/LIMK2/CFL1 signaling. Wnt5A/Ryk signaling might provide novel therapeutic strategies to prevent capillary leakage in systemic inflammation and septic shock.

Therapeutic Targets in Sepsis: Past, Present, and Future

Antibiotics and fluids have been standard treatment for sepsis since World War II. Many molecular mediators of septic shock have since been identified. In models of sepsis, blocking these mediators improved organ injury and decreased mortality. Clinical trials, however, have failed. The absence of new therapies has been vexing to clinicians, clinical researchers, basic scientists, and the pharmaceutical industry. This article examines the evolution of sepsis therapy and theorizes about why so many well-reasoned therapies have not worked in human trials. We review new molecular targets for sepsis and examine trial designs that might lead to successful treatments for sepsis.

Pathophysiology of sepsis-related cardiac dysfunction: driven by inflammation, energy mismanagement, or both?

Sepsis is a systemic inflammatory response that follows bacterial infection. Cardiac dysfunction is an important consequence of sepsis that affects mortality and has been attributed to either elevated inflammation or suppression of both fatty acid and glucose oxidation and eventual ATP depletion. Moreover, cardiac adrenergic signaling is compromised in septic patients and this aggravates further heart function. While anti-inflammatory therapies are important for the treatment of the disease, administration of anti-inflammatory drugs did not improve survival in septic patients. This review article summarizes findings on inflammatory and other mechanisms that are triggered in sepsis and affect cardiac function and mortality. Particularly, it focuses on the effects of the disease in metabolic pathways, as well as in adrenergic signaling and the potential interplay of the latter with inflammation. It is suggested that therapeutic approaches should include combination of anti-inflammatory treatments, stimulation of energy production, and restoration of adrenergic signaling in the heart.

Impact of treatment with biologic DMARDs on the risk of sepsis or mortality after serious infection in patients with rheumatoid arthritis

Objective

This observational cohort study investigated the impact of biological (b) disease-modifying antirheumatic drugs (DMARDs) on the outcomes of serious infections (SIs) in patients with rheumatoid arthritis.

Methods

We investigated outcomes of SIs observed in 947 patients enrolled in the German biologics register RABBIT(Rheumatoid arthritis: observation of biologic therapy). Outcomes were (1) recovery without complication, (2) sepsis following SI (≤30 days), and (3) death after SI without known sepsis (≤90 days). We applied a multinomial generalised estimating equation model for longitudinal data to evaluate the risks of sepsis and death simultaneously.

Results

Sepsis within 30 days after SI was reported in 135 out of 947 patients, 85 of these had a fatal outcome. Fifty-three patients died within 90 days after SI without known sepsis. The adjusted risk of developing sepsis increased with age and was higher in patients with chronic renal disease. Compared with conventional synthetic (cs)DMARDs, the risk was significantly lower when patients were exposed to bDMARDs at the time of SI (OR: 0.56, 95% CI 0.38 to 0.81). Risk factors of fatal SI were higher age, use of glucocorticoids at higher doses and heart failure. Patients treated with bDMARDs and those with better physical function had a significantly lower mortality risk.

Conclusions

These results suggest a beneficial effect of bDMARDs on the risk of sepsis after SI and the risk of a fatal outcome. Successful immunosuppression may prevent an unregulated host response to SI, that is, the escalation to sepsis. Further investigation is needed to validate these results.

Exploring the translational disconnect between the murine and human inflammatory response: analysis of LPS dose-response relationship in murine versus human cell lines and implications for translation into murine models of sepsis

Background

Inflammation forms an important part of the human innate immune system and is largely dependent on the activation of the “classical” NF-κB pathway through Toll-like receptors (TLRs). Understanding this has allowed researchers to explore roles of therapeutic targets in managing conditions such as sepsis. Recapitulating an inflammatory response using lipopolysaccharide (LPS), a “sterile” technique, can provide information that is dissimilar to the clinical condition. By examining NF-κB activation (through immunoblotting of the p65 subunit) in two separate cell lines (murine and human) and analyzing two murine models of sepsis (intraperitoneal [IP] LPS and IP stool inoculation), an evaluation of the translational disconnect between experimental and clinical sepsis can be made.

Methods

THP-1 (human) cells and RAW 264.7 (murine) cells were dosed with concentrations of LPS (human, 1 pg/mL to 100 ng/mL; murine, 30 pg/mL to 1,000 ng/mL) and nuclear actin and p65 were immunoblotted to measure changes in nuclear density. In vivo, C57BL/6 mice received either IP injection of stool suspension (5 µL/g) or LPS (25 mg/kg) or saline (1 mL/kg). Animals were culled at 6 hours and tissues were analyzed.

Results

An increase in basal p65:actin density in THP-1 cells (mean 0.214, standard error of the mean 0.024) was seen at doses as small as 0.1 ng/mL (0.519±0.064). In contrast to RAW 264.7 cells, basal increases (0.170±0.025) were only seen when a dose of 3 ng/mL (0.387±0.078) was used. Dose–response analysis of p65:actin ratio showed that THP-1 cells respond to lower doses of LPS than RAW 264.7 cells and lower doses produce a greater fold increase in the nuclear p65 density. Both in vivo models showed evidence of neutrophil (NL) recruitment into tissues (which was more intense after LPS treatment). IP stool inoculation resulted in an acute suppurative peritonitis and more substantial evidence of NL recruitment into adipose tissue and skeletal muscle.

Conclusion

Our results support previous observations that translation of murine models into the human clinical setting suffers from considerable limitations including species-associated differences in LPS response seen at a molecular level. Furthermore, the histopathological changes during clinical sepsis cannot be adequately reproduced by injection of LPS. Therefore, the so-called translational disconnect that exists between murine LPS models and human sepsis involves NF-κB activation at a molecular level and is further augmented by the use of LPS as a stimulus for infectious responses in vivo.

Panax ginseng aqueous extract prevents pneumococcal sepsis in vivo by potentiating cell survival and diminishing inflammation

BACKGROUND

More than 50% of sepsis cases are caused by Streptococcus pneumoniae, and hospital mortality related to sepsis comprises 52% of all hospital deaths. Therefore, sepsis is a medical emergency, and any treatment against the agent that produces it, is welcome.

PURPOSE

The role of Panax ginseng C.A. Meyer (Araliaceae) aqueous extract in bacterial infection in vivo is not well understood. Here, the protective effect of Korean red ginseng (KRG) extract against pneumococcal infection and sepsis was elucidated.

STUDY DESIGN

In this study, mice were administrated KRG (25, 50, 100 mg/kg) for 15 days, and then infected with a lethal S. pneumoniae strain. Survival rate, body weight, and colonization were determined.

METHODS

The RAW 264.7 macrophage cells were infected with S. pneumoniae and cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Inflammation was examined using an enzyme-linked immunosorbent assay (ELISA) and hematoxylin and eosin (HE) staining while gene expression was determined using western blotting.

RESULTS

KRG-pre-treated mice (100 mg/kg of KRG) had significantly higher survival rates and body weights than those of the non-treated controls; KRG-pre-treated mice had lower bacterial number and morbidity than those of the non-treated controls. 100 mg/kg of KRG administration decreased cytokine levels including tumor necrosis factor (TNF)-α (897 and 623 pg/ml, control and KRG groups, respectively, P < 0.05) and interleukin (IL)-1β (175 and 127 pg/ml, control and KRG groups, respectively, P = 0.051), nitric oxide level (149 and 81 nM, control and KRG groups, respectively, P < 0.05), and neutrophil infiltration 48 h post-infection, in vivo. In pneumococcal infection, KRG pre-treatment downregulated toll-like receptor (TLR) 4 and TNF-ɑ expressions in RAW 264.7 macrophage cells and increased cell survival by activating phosphoinositide 3-kinase (PI3K)/AKT signaling.

CONCLUSION

Taken together, 100 mg/kg of KRG appeared to protect host cells from lethal pneumococcal sepsis by inhibiting inflammation as well as by enhancing bacterial clearance thereby reinforcing cell survival against pneumococcal infection.

Protective effects of Sparstolonin B, a selective TLR2 and TLR4 antagonist, on mouse endotoxin shock

Sepsis is characterized by an overwhelming systemic inflammation and multiple organ injury. Toll-like receptors (TLRs) 2 and 4 mediate these inflammatory responses. Sparstolonin B (SsnB), isolated from Chinese herb Scirpus yagara, is a new selective TLR2/4 antagonist. Herein, we report that SsnB inhibited the expression of various inflammatory mediators such as tumor necrosis factor (TNF-α), interleukin (IL)-1β, IL-6, and chemokine (C-C motif) ligand 2 (CCL-2) in lipopolysaccharide (LPS)- or Pam3csk4-stimulated macrophages. Moreover, in LPS-stimulated macrophages, the downregulation of peroxisome proliferator-activated receptor γ (PPAR-γ) was reversed by SsnB dose-dependently; and SsnB had synergistic inhibitory effects with rosiglitazone, a PPAR-γ agonist, on TNF-α and IL-6 expression in LPS-stimulated macrophages. The effects of SsnB were further evaluated in a mouse endotoxin shock model. When intraperitoneal injected in mice 2 days before or 1-2h after LPS challenge, SsnB attenuated the body temperature reduction and decreased the mortality. SsnB pre-treatment significantly suppressed LPS-induced increase of TNF-α and IL-6 in serum, lungs and livers, and substantially attenuated lung dysfunction in mice. In vivo toxicity test showed that at doses as high as 500 mg/kg, SsnB did not cause death of mice. These results suggest that SsnB protects mice against endotoxin shock by inhibiting production of multiple cytokines and lung dysfunction. In conclusion, our findings indicate that SsnB may be used in the prevention and treatment of endotoxin shock.

The effect of progesterone on systemic inflammation and oxidative stress in the rat model of sepsis

OBJECTIVES

To explore the protective effect of progesterone on inflammation and oxidative stress in a rat model of sepsis created by cecal ligation and puncture (CLP).

MATERIALS AND METHODS

Rats were randomly divided into 4 groups: Overiectomy group (OVX), sham operated (control), sepsis (CLP) group and progesterone-treated CLP group (CLP+ progesterone). The rats in CLP+ progesterone group received intraperitoneal progesterone (2 mg/kg). Cardiac blood samples were obtained for the measurement levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Tissue samples, including liver, kidney and uterus of rats were prepared to determine activities of myeloperoxidase (MPO), glutathione peroxidase (GPx) and levels of malondialdehyde (MDA).

RESULTS

Increased serum IL-6 and TNF-α levels were found in the CLP group in comparison with the control group (P = 0.01, P = 0.02; respectively). In CLP+ progesterone group, mean MDA concentration of kidney tissue was significantly lower than in CLP group (P = 0.003). Liver MDA concentration of the CLP+ progesterone group was not significantly different from that of the control group. While there were no significant differences among groups regarding liver MPO; in the CLP group, MPO activity in kidney (P = 0.02) and uterine tissues (P = 0.03) were found to be significantly higher compared to the control group. In CLP+ progesterone group, mean MPO activities of all tissues were not different than those of control group. The uterine tissue GPx activity in the CLP+ progesterone group was not statistically significantly different from control group.

CONCLUSIONS

We suggest that progesterone ameliorates sepsis syndrome by reduction of the inflammatory cytokines IL-6 and TNF-α, and by restoration of antioxidant enzyme activities in some tissues.

Role of endogenous TNF-α in cardiomyocyte apoptosis induced by bacteria lipoprotein and the protective effect of IL-10

Cardiomyocyte apoptosis is thought to play an important role in sepsis-induced cardiodepression. Previous studies mainly focused on the role of exogenous TNF-α in sepsis-induced cardiac damage, however, the role of endogenous TNF-α is rarely known. Therefore, we hypothesized that endogenous TNF-α also contributed to sepsis-induced cardiomyocyte apoptosis. Primary neonatal rat cardiomyocytes were time- and dose-dependently stimulated with BLP and TNF-α. In separate experiments, cells were treated with TNF-α antagonist and IL-10, respectively, to determine effects of endogenous TNF-α and exogenous IL-10 on BLP-induced cardiomyocyte apoptosis. After treatment, apoptosis was evaluated by nuclear condensation, membrane permeability change, caspase-3 activation, and pro- to anti-apoptotic protein (bax to bcl-2) expression. Treatment of cardiomyocytes with BLP and TNF-α both significantly induced caspase-3 activation in a time- and dose-dependent manner and caused apparent nuclear condensation and increased membrane permeability. TNF-α antagonist pretreatment attenuated BLP-induced caspase-3 activation, and downregulated bax/bcl-2 ratio. In addition, administration of IL-10 inhibited TNF-α production and suppressed cardiomyocyte apoptosis induced by BLP. Our data suggest that endogenous TNF-α play an important role in BLP-induced cardiomyocyte apoptosis and IL-10 protect cardiomyocytes from BLP-induced apoptosis, an effect partially through inhibition of endogenous TNF-α production.

Monocyte Tumor Necrosis Factor-α-Converting Enzyme Catalytic Activity and Substrate Shedding in Sepsis and Noninfectious Systemic Inflammation

Objectives:

To determine the effect of severe sepsis on monocyte tumor necrosis factor-α–converting enzyme baseline and inducible activity profiles.

Design:

Observational clinical study.

Setting:

Mixed surgical/medical teaching hospital ICU.

Patients:

Sixteen patients with severe sepsis, 15 healthy volunteers, and eight critically ill patients with noninfectious systemic inflammatory response syndrome.

Interventions:

None.

Measurements and Main Results:

Monocyte expression of human leukocyte antigen-D-related peptide, sol-tumor necrosis factor production, tumor necrosis factor-α–converting enzyme expression and catalytic activity, tumor necrosis factor receptor 1 and 2 expression, and shedding at 48-hour intervals from day 0 to day 4, as well as p38-mitogen activated protein kinase expression. Compared with healthy volunteers, both sepsis and systemic inflammatory response syndrome patients’ monocytes expressed reduced levels of human leukocyte antigen-D-related peptide and released less sol-tumor necrosis factor on in vitro lipopolysaccharide stimulation, consistent with the term monocyte deactivation. However, patients with sepsis had substantially elevated levels of basal tumor necrosis factor-α–converting enzyme activity that were refractory to lipopolysaccharide stimulation and this was accompanied by similar changes in p38-mitogen activated protein kinase signaling. In patients with systemic inflammatory response syndrome, monocyte basal tumor necrosis factor-α–converting enzyme, and its induction by lipopolysaccharide, appeared similar to healthy controls. Changes in basal tumor necrosis factor-α–converting enzyme activity at day 0 for sepsis patients correlated with Acute Physiology and Chronic Health Evaluation II score and the attenuated tumor necrosis factor-α–converting enzyme response to lipopolysaccharide was associated with increased mortality. Similar changes in monocyte tumor necrosis factor-α–converting enzyme activity could be induced in healthy volunteer monocytes using an in vitro two-hit inflammation model. Patients with sepsis also displayed reduced shedding of monocyte tumor necrosis factor receptors upon stimulation with lipopolysaccharide.

Conclusions:

Monocyte tumor necrosis factor-α–converting enzyme catalytic activity appeared altered by sepsis and may result in reduced shedding of tumor necrosis factor receptors. Changes seemed specific to sepsis and correlated with illness severity. A better understanding of how tumor necrosis factor-α–converting enzyme function is altered during sepsis will enhance our understanding of sepsis pathophysiology, which will help in the assessment of patient inflammatory status and ultimately may provide new strategies to treat sepsis.