Bench-to-bedside review: Toll-like receptors and their role in septic shock

β-Glucan-conjugated anti-PD-L1 antibody enhances antitumor efficacy in preclinical mouse models

The use of immune checkpoint blockade (ICB) is a promising approach for clinical cancer treatment. However, most of cancer patients do not respond to anti-PD-1/PD-L1 antibody. In this study, we proposed a novel strategy of antibody-β-glucan conjugates (AGC) to enhance the antitumor immune response to ICB therapy. The AGC were constructed by conjugating an anti-PD-L1 antibody with a β-glucan via click chemistry. This design facilitates the delivery of β-glucan into the tumor microenvironment (TME). Furthermore, the bridging effect mediated by AGC can promote the interaction between tumor cells and dendritic cells (DCs), thereby enhancing immunotherapeutic benefits. In the MC38 tumor-bearing mouse model, AGC demonstrated powerful tumor suppression, achieving a tumor suppression rate of 86.7 %. Immunophenotyping, cytokine analysis, RNA sequencing, and FTY720-treated models were combined to elucidate the mechanism underlying AGC function. Compared with anti-PD-L1 antibody, AGC induced an earlier immune response, infiltration of DCs, and activation of preexisting T cells in the TME, with T cells predominantly proliferating locally rather than migrating from other organs. In conclusion, these data suggest that AGC could serve as a promising strategy to improve ICB therapy with prospects for clinical utilization.

Dihydroartemisinin ameliorates innate inflammatory response induced by Streptococcussuis-derived muramidase-released protein via inactivation of TLR4-dependent NF-κB signaling

Muramidase-released protein (MRP) is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis (S. suis). However, the identification of viable therapeutics for S. suis infection was hindered by the absence of an explicit mechanism for MRP-actuated inflammation. Dihydroartemisinin (DhA) is an artemisinin derivative with potential anti-inflammatory activity. The modulatory effect of DhA on the inflammatory response mediated by the virulence factor MRP remains obscure. This research aimed to identify the signaling mechanism by which MRP triggers the innate immune response in mouse spleen and cultured macrophages. With the candidate mechanism in mind, we investigated DhA for its ability to dampen the pro-inflammatory response induced by MRP. The innate immune response in mice was drastically triggered by MRP, manifesting as splenic and systemic inflammation with splenomegaly, immune cell infiltration, and an elevation in pro-inflammatory cytokines. A crucial role for Toll-like receptor 4 (TLR4) in coordinating the MRP-mediated inflammatory response via nuclear factor-kappa B (NF-κB) activation was revealed by TLR4 blockade. In addition, NF-κB-dependent transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinases (MAPKs) activation was required for the inflammatory signal transduction engendered by MRP. Intriguingly, we observed an alleviation effect of DhA on the MRP-induced immune response, which referred to the suppression of TLR4-mediated actuation of NF-κB-STAT3/MAPK cascades. The inflammatory response elicited by MRP is relevant to TLR4-dependent NF-κB activation, followed by an increase in the activity of STAT3 or MAPKs. DhA mitigates the inflammation process induced by MRP via blocking the TLR4 cascade, highlighting the therapeutic potential of DhA in targeting S. suis infection diseases.

The diversity and coexistence of extracellular mitochondria in circulation: A friend or foe of the immune system

The diversity and coexistence of extracellular mitochondria may have a key role in the maintenance of health and progression of disease. Studies report that active mitochondria can be found physiologically outside of cells and circulating in the blood without inducing an inflammatory response. In addition, inactive or harmed mitochondria have been recognized as activators of immune cells, as they play an essential role in diseases characterized by the metabolic deregulation of these cells, such as sepsis. In this review we analyze key aspects regarding the existence of a diversity of extracellular mitochondria, their coexistence in body fluids and their effects on various immune cells. Additionally, we introduce models of how extracellular mitochondria could be interacting to maintain health and affect disease prognosis. Unwrapped mitochondria (freeMitos) can exist as viable, active, inactive or harmed organelles. Mitochondria can also be found wrapped in a membrane (wrappedMitos) that may differ depending on the cell of origin. Mitochondrial fragments can also be present in various body fluids as DAMPs, as mtDNA enclosed in vesicles or as circulating-cell-free mtDNA (ccf-mtDNA). Interestingly, the great quantity of evidence regarding the levels of ccf-mtDNA and their correlation with aging and disease allows for the identification of the diversity, but not type, of extracellular mitochondria. The existence of a diversity of mitochondria and their effects on immune cells opens a new concept in the biomedical field towards the understanding of health, the progression of disease and the development of mitochondria as therapeutic agents.

The Role of Creatine in the Development and Activation of Immune Responses

The use of dietary supplements has become increasingly common over the past 20 years. Whereas supplements were formerly used mainly by elite athletes, age and fitness status no longer dictates who uses these substances. Indeed, many nutritional supplements are recommended by health care professionals to their patients. Creatine (CR) is a widely used dietary supplement that has been well-studied for its effects on performance and health. CR also aids in recovery from strenuous bouts of exercise by reducing inflammation. Although CR is considered to be very safe in recommended doses, a caveat is that a preponderance of the studies have focused upon young athletic individuals; thus there is limited knowledge regarding the effects of CR on children or the elderly. In this review, we examine the potential of CR to impact the host outside of the musculoskeletal system, specifically, the immune system, and discuss the available data demonstrating that CR can impact both innate and adaptive immune responses, together with how the effects on the immune system might be exploited to enhance human health.

Toll-interacting protein impacts on inflammation, autophagy, and vacuole trafficking in human disease

Toll-interacting protein (TOLLIP) is a ubiquitous intracellular adaptor protein involved in multiple intracellular signaling pathways. It plays a key role in mediating inflammatory intracellular responses, promoting autophagy, and enabling vacuole transport within the cell. TOLLIP is being increasingly recognized for its role in disease pathophysiology through involvement in these three primary pathways. Recent research also indicates that TOLLIP is involved in nuclear-cytoplasmic transfer, although this area requires further exploration. TOLLIP is involved in the pathophysiologic pathways associated with neurodegenerative diseases, pulmonary diseases, cardiovascular disease, inflammatory bowel disease, and malignancy. We postulate that TOLLIP plays an integral role in the disease pathophysiology of other conditions involved in vacuole trafficking and autophagy. We suggest that future research in this field should investigate the role of TOLLIP in the pathogenesis of these multiple conditions. This research has the potential to inform disease mechanisms and identify novel opportunities for therapeutic advances in multiple disease processes.

Procalcitonin as a biomarker for critically ill patients with sepsis: Effects of vitamin D supplementation

Early diagnosis of sepsis is often difficult in clinical practice, whilst it can be vital for positive patient outcomes in sepsis management. Any delay in diagnosis and treatment may lead to significant organ failure and can be associated with elevated mortality rates. Early diagnosis and effective management of sepsis can allow for prompt antibiotic therapy and a potential reduction in mortality; it can also minimize the unnecessary use of antibiotics. Furthermore, vitamin D supplementation, which is commonly used in the intensive care units to reduce mortality, may interfere with the ability to use procalcitonin (PCT) as a means of assessing clinical progression. This paper aims to explore the diagnostic and prognostic value of serum levels of PCT as an early marker of sepsis and to assess whether it can be used as a guide for using antibiotic therapy. Several serum-based biomarkers such as C-reactive protein, lactate, presepsin, and cytokines, such as interleukin-1 (IL-1), and IL-6 have been evaluated as early indicators of sepsis but none have been proven sensitive and/or specific enough to make a definitive diagnosis. Finally the potential benefits and disadvantages of using serum levels of PCT to diagnose and monitor patients with sepsis and septic shock will be briefly discussed.

Acute toxic effect of lipopolysaccharides to blood tissue in rats and responses to vitamin E and sodium selenite

This work has been prepared to find out changes in the biochemicals with DNA damage, micronucleus, and apoptosis to lipopolysaccharides (LPS) alone or vitamin E (VE) and sodium selenite (SS) in rats' blood tissue. Rats were divided into eight groups according to the treatment into control vitamin E (VE) treatment group (200 mg/kg bw), sodium selenite (SS) treatment (0.35 mg/kg bw) group, VE + SS treatment group (200 + 0.35 mg/kg bw), LPS treatment group (10 mg/kg bw), LPS + VE (10 + 200 mg/kg bw), LPS + SS treatment (10 + 0.35 mg/kg bw), and LPS + SS+VE treatment (10 + 0.35 + 200 mg/kg bw) group for 6 hr. LPS increased malondialdehyde (MDA) level and decreased antioxidant enzymes' activities in rat erythrocytes and leukocytes. DNA damage of leukocytes with comet assay and RAPD-PCR was detected in LPS treatment group. The levels of micronucleus and apoptosis percentage were increased significantly at the end of 6 hr. VE and/or SS protected the LPS-induced erythrocytes and leukocytes against damage as they have caused amelioration of rats by altering the results. As a result, the co-administration of VE and/or SS against LPS-induced damage provides protection. VE and/or SS in patients and animal models with sepsis must be taken in the diet because they are protective against the cellular degradation caused by oxidative damage. PRACTICAL APPLICATIONS: LPS obtained from E. coli is used more frequently in experimental sepsis studies. When LPS is administered to experimental animals, interstitial pneumonia, adult respiratory fatal syndrome, acute tubular necrosis, and fatal effects such as coagulopathy and hypoglycemia may be seen in these animals. The co-treatment of VE and SS may be more effective than using them alone against LPS.

Low-molecular weight mannogalactofucans prevent herpes simplex virus type 1 infection via activation of Toll-like receptor 2

Low-molecular-weight mannogalactofucans (LMMGFs, <4000g/mol) were prepared by the enzymatic degradation of Undaria pinnatifida sporophyll galactofucan (MF) and evaluated or their antiviral activities and underlying action mechanisms against herpes simplex virus type 1 (HSV-1). The 50% inhibitory concentrations (IC₅₀) of LMMGFs and MF were 2.64 and 2.42μg/mL, respectively. LMMGFs inhibited the viral entry on the host cell surface and also exhibited inhibitory activity directly against viral particles, as observed in a virucidal assay. LMMGFs dose-dependently enhanced the mRNA expression of Toll-like receptor 2 (TLR2) and stimulated the phosphorylation of Akt and JNK in Vero cells. These results clearly demonstrated that LMMGFs use TLR2 as their receptor, preventing HSV-1 infection on the host cell surface and antagonizing viral adsorption via TLR2 pathway activation in Vero cells.

Preadmission Use of Calcium Channel Blockers and Outcomes After Hospitalization With Pneumonia: A Retrospective Propensity-Matched Cohort Study

In sepsis, an overwhelming immune response, as mediated by the release of various inflammatory mediators, can lead to shock, multiple organ damage, and even death. Pneumonia is the leading cause of sepsis. In animal septic models, sepsis could induce uncontrolled calcium (Ca) leaking, raising cytosolic Ca to a toxic level, causing irreversible cellular injuries and organ failure. All types of calcium channel blockers (CCBs), by inhibiting Ca influx, have been shown to decrease overall mortality in various septic animal models. However, to our best knowledge, no clinical study had been conducted to investigate the beneficial effect(s) of CCBs in sepsis. We conducted a retrospective propensity-matched cohort study after screening 2214 patients hospitalized for pneumonia from year 2012 to 2014 at our institution. We identified 387 preadmission CCB users and 387 nonusers by propensity score matching. Logistic regression analysis was then used to determine the association between preadmission CCB use and outcomes in pneumonia. Our study showed that the odds for development of severe sepsis was significantly lower in the CCB user group [odds ratio (OR), 0.466; 95% confidence interval (CI), 0.311-0.697; P = 0.002]. Preadmission CCB use was associated with a lower risk of contracting bacteremia (OR, 0.498; 95% CI, 0.262-0.99; P = 0.0327), lower risk of acute respiratory insufficiency (OR, 0.573; 95% CI, 0.412-0.798; P = 0.001), lower risk of intensive care unit admission (OR, 0.602; 95% CI, 0.432-0.840; P = 0.0028). In conclusion, our study suggested preadmission CCB use was associated with a reduction in the risks of development of respiratory insufficiency, bacteremia, and severe sepsis in patients admitted to the hospital with pneumonia.

Role of the IL-33-ST2 axis in sepsis

Sepsis remains a major clinical problem with high morbidity and mortality. As new inflammatory mediators are characterized, it is important to understand their roles in sepsis. Interleukin 33 (IL-33) is a recently described member of the IL-1 family that is widely expressed in cells of barrier tissues. Upon tissue damage, IL-33 is released as an alarmin and activates various types of cells of both the innate and adaptive immune system through binding to the ST2/IL-1 receptor accessory protein complex. IL-33 has apparent pleiotropic functions in many disease models, with its actions strongly shaped by the local microenvironment. Recent studies have established a role for the IL-33-ST2 axis in the initiation and perpetuation of inflammation during endotoxemia, but its roles in sepsis appear to be organism and model dependent. In this review, we focus on the recent advances in understanding the role of the IL-33/ST2 axis in sepsis.

The nexus between systemic inflammation and disordered coagulation in sepsis

The innate immune system is designed as an early defense system that recognizes and clears potential microbial invaders. The coagulation system co-evolved with the innate immune system from a common ancestral cellular origin, and these two systems continue to exhibit a remarkable degree of integration in their signaling pathways and regulatory circuits following tissue injury and microbial invasion. Inflammatory mediators generate procoagulant signals and intravascular thrombosis activates multiple components of the innate immune system. The success of recombinant human activated protein C for the treatment of human septic shock is likely attributable to its combined effects as an endogenous anticoagulant and an anti-inflammatory molecule. Further advances in the management of severe infections may accrue with a better understanding of the integral link between coagulation and innate immunity.

Obesity and Sepsis

Obesity has reached epidemic proportions over the last few decades. Obesity is associated with increased morbidity and mortality in hypertension, cardiovascular diseases, stroke, and cancer and is feared to decrease overall life expectancy over the next few decades. There is a growing body of evidence suggesting that obesity is a chronic inflammatory disease. Obesity is becoming a cause of concern in critically ill patients as well. Sepsis is the number one cause of morbidity and mortality in noncoronary artery disease critical care units all over the world and is associated with a high cost of care. An increase in morbidity in obese septic patients compared with lean people is a cause of growing concern. Laboratory evidence suggests that there is exaggeration in the inflammatory and prothrombogenic phenotype assumed by obese compared with lean septic animals. The exact mechanisms underlying this phenomenon are unknown. This article reviews some of the pathophysiological processes responsible for the underlying inflammation in obesity and sepsis and reviews the literature for the association of the two.

The immunomodulatory effect of vitamin D in chickens is dose-dependent and influenced by calcium and phosphorus levels

Vitamin D requirement is estimated to be higher than recommended values for the first two weeks of a broiler chicken's life, and is heavily dependent on the concentrations of Ca and P in the diet. There are data indicating the beneficial effect of higher vitamin D levels on performance and overall health of the chickens. However, data on the role of higher vitamin D levels on the innate immune response of chickens are limited. Therefore, in the current study, we examined the effect of higher doses of vitamin D supplementation on the innate immune response in broiler chickens receiving optimal or calcium (Ca) and phosphorus (P) deficient diets. Three hundred Ross-308 male broiler chicks were randomly allocated into 60 cages with 5 birds per cage in a 3 × 2 factorial design with three levels of vitamin D and two levels of Ca/P with each experimental diet fed to 10 cages (10 replicates). Quantitative reverse transcription PCR (n = 5) was used to assess Toll-like receptor (TLR2b and 4), cytokine/chemokine (IL-12, IFN-γ, IL-10, IL-4, IL-13, IL-18, CxCLi2) and cathelicidin (CATH1, CATHB1, CATH3) transcription levels in peripheral blood mononuclear cells (PBMCs), spleen, and bursa of Fabricius. Vitamin D supplementation of the Ca and P deficient diet considerably augmented transcription of TLR2b, TLR4, CATH1, and CATHB1 and predominantly Th2 cytokines in spleen. Supplementation of the control diet with vitamin D downregulated TLR4 transcription, and dose-dependently increased CATH1, CATHB1, Th1, and Th2 cytokine transcription (Th2>Th1). All diets downregulated CATH3 transcription. In conclusion, vitamin D or its derivative 25-OH-D₃ both have a robust immunomodulatory property with a more favorable Th2 response, while at the same time enhancing observed Th2 cytokine responses under both optimal and lower Ca and P inclusion levels in the diets of broiler chickens.

Ginkgolide B functions as a determinant constituent of Ginkgolides in alleviating lipopolysaccharide-induced lung injury

Ginkgolides are the major bioactive components of Ginkgo biloba extracts, however, the exact constituents of Ginkgolides contributing to their pharmacological effects remain unknown. Herein, we have determined the anti-inflammatory effects of Ginkgolide B (GB) and Ginkgolides mixture (GM) at equivalent dosages against lipopolysaccharide (LPS)-induced inflammation. RAW 264.7 cell culture model and mouse model of LPS-induced lung injury were used to evaluate in vitro and in vivo effects of GB and GM, respectively. In RAW 264.7 cells, GB and GM at equivalent dosages exhibit an identical capacity to attenuate LPS-induced inducible nitric oxide synthase mRNA and protein expression and subsequent NO production. Likewise, GB and GM possess almost the same potency in attenuating LPS-induced expression and activation of nuclear factor kappa B (p65) and subsequent increases in tumor necrosis factor-α mRNA levels. In LPS-induced pulmonary injury, GB and GM at the equivalent dosages have equal efficiency in attenuating the accumulation of inflammatory cells, including neutrophils, lymphocytes, and macrophages, and in improving the histological damage of lungs. Moreover, GB and GM at equivalent dosages decrease the exudation of plasma protein to the same degree, whereas GM is superior to GB in alleviating myeloperoxidase activities. Finally, though GB and GM at equivalent dosages appear to reduce LPS-induced IL-1β mRNA and protein levels and IL-10 protein levels to the same degree, GM is more potent than GB to attenuate the IL-10 mRNA levels. Taken together, this study demonstrates that GB functions as the determinant constituent of Ginkgolides in alleviating LPS-induced lung injury.

Emerging therapeutic targets of sepsis-associated acute kidney injury

Sepsis-associated acute kidney injury (SA-AKI) is linked to high morbidity and mortality. To date, singular approaches to target specific pathways known to contribute to the pathogenesis of SA-AKI have failed. Because of the complexity of the pathogenesis of SA-AKI, a reassessment necessitates integrative approaches to therapeutics of SA-AKI that include general supportive therapies such as the use of vasopressors, fluids, antimicrobials, and target-specific and time-dependent therapeutics. There has been recent progress in our understanding of the pathogenesis and treatment of SA-AKI including the temporal nature of proinflammatory and anti-inflammatory processes. In this review, we discuss the clinical and experimental basis of emerging therapeutic approaches that focus on targeting early proinflammatory and late anti-inflammatory processes, as well as therapeutics that may enhance cellular survival and recovery. Finally, we include ongoing clinical trials in sepsis.

Vasoactive intestinal peptide (VIP) differentially affects inflammatory immune responses in human monocytes infected with viable Salmonella or stimulated with LPS

We compared the effect of VIP on human blood monocytes infected with Salmonella typhimurium 4/74 or stimulated with LPS. VIP (10(-7)M) increased monocyte viability by 24% and 9% when cultured for 24h with 4/74 or Salmonella LPS (100ng/ml), respectively. Significantly increased (P<0.05) numbers of 4/74 were also recovered from monocytes co-cultured with VIP after 6h post-infection (pi) and this remained high after 24h pi. Both 4/74 and LPS increased (P<0.05) the concentration of TNF-α, IL-1β and IL-6 measured in monocyte supernatants. However, LPS induced this effect more rapidly while, with the exception of IL-6, 4/74 induced higher concentrations (P<0.05). VIP significantly decreased (P<0.05) TNF-α and IL-1β production by 4/74-infected monocytes after 6 pi, but only after 24h in LPS-cultured monocytes. This trend was reversed for IL-6 production. However, TNF-α and IL-1β production by 4/74-infected monocytes, cultured with VIP, still remained higher (P<0.05) than concentrations measured in supernatants cultured only with LPS. VIP also increased (P<0.05) production of anti-inflammatory IL-10 in both 4/74 and LPS cultures after 24h. We also show a differential effect of VIP on the expression of TNFα and IL-6 receptors, since VIP was only able to decreased expression in LPS-stimulated monocytes but not in 4/74-infected monocytes. In conclusion, we show a differential effect of VIP on human monocytes infected with virulent Salmonella or stimulated with LPS. Our study suggests that the use of VIP in bacteraemia and/or sepsis may be limited to an adjunctive therapy to antibiotic treatment.

Diagnosis of infection in critical care

Sepsis is the primary cause of death in the intensive care unit. The prevention of sepsis complications requires an early and accurate diagnosis as well as the appropriate mon itoring. A deep knowledge of the immunologic basis of sepsis is essential to better understand the scope of incorporating a new marker into clinical practice. Besides revising this theoretical aspect, the current available tools for bacterial iden tification have been briefly reviewed as well as a variety of new markers showing either well-recognized or potential usefulness for diagnosis and prognosis of infections in crit ically ill patients. Particular conditions such as community acquired pneumonia, pedi atric sepsis, or liver transplantation, among others, have been separately treated, since the optimal approaches and markers might be different in these special cases.

Genetic variation in TNFA predicts protection from severe bacterial infections in patients with end-stage liver disease awaiting liver transplantation

BACKGROUND & AIMS

Augmented susceptibility to infections increases mortality in patients with end-stage liver disease (ESLD). We sought to determine the contribution of selected genetic variants involved in inflammatory signalling downstream of the Toll-like receptor 4 (TLR4) to severe bacterial infections (SBIs) in patients with ESLD.

METHODS

We retrospectively assessed incidence of SBIs in 336 adult ESLD patients enlisted for orthotopic liver transplantation (OLT) and genotyped them for TLR4 c.+1196C/T, CD14 c.-159C/T, TNFA c.-238G/A, TNFA c.-863C/A, IL1B c.-31C/T and IL1RN variable number of tandem repeats allelic variants. Principal findings were validated in an independent cohort of 332 ESLD patients.

RESULTS

Thirty-four percent of patients from the identification cohort and 40% of patients from the validation cohort presented with SBI while enlisted for OLT. The presence of the variant allele TNFA c.-238A (rs361525) was associated with lower serum levels of TNF-α, and with significantly decreased risk of SBI in both cohorts. Multivariate analysis showed that the relative protection from SBI associated with this allele almost completely negated the increased susceptibility to SBI owed to advanced ESLD. Although not predictive of overall mortality, the presence of the TNFA c.-238A allele was associated with a complete prevention of SBI-related pre-transplant deaths.

CONCLUSIONS

Our results suggest that genetic variability in inflammatory signalling is associated with the development of SBI in patients with ESLD. Specifically, we identified the importance of the TNFA c.-238A allele as a strong predictor of protection from SBI, and as a genetic marker associated with significantly improved pre-transplant survival in patients with SBI.

Characterization of Toll-like receptors 1-10 in spotted hyenas

Previous research has shown that spotted hyenas (Crocuta crocuta) regularly survive exposure to deadly pathogens such as rabies, canine distemper virus, and anthrax, suggesting that they have robust immune defenses. Toll-like receptors (TLRs) recognize conserved molecular patterns and initiate a wide range of innate and adaptive immune responses. TLR genes are evolutionarily conserved, and assessing TLR expression in various tissues can provide insight into overall immunological organization and function. Studies of the hyena immune system have been minimal thus far due to the logistical and ethical challenges of sampling and preserving the immunological tissues of this and other long-lived, wild species. Tissue samples were opportunistically collected from captive hyenas humanely euthanized for a separate study. We developed primers to amplify partial sequences for TLRs 1-10, sequenced the amplicons, compared sequence identity to those in other mammals, and quantified TLR expression in lymph nodes, spleens, lungs, and pancreases. Results show that hyena TLR DNA and protein sequences are similar to TLRs in other mammals, and that TLRs 1-10 were expressed in all tissues tested. This information will be useful in the development of new assays to understand the interactions among the hyena immune system, pathogens, and the microbial communities that inhabit hyenas.

Vitamin D₃ derivatives increase soluble CD14 release through ERK1/2 activation and decrease IL-8 production in intestinal epithelial cells

Dysfunction of the innate immune system has been reported to cause intestinal inflammation. Vitamin D3 is known to be an important immune system regulator and exerts anti-inflammatory effects. We investigated in vitro effects of vitamin D3 and its derivatives on the innate immune system in HT-29 cells, a line of human colon adenocarcinoma cells. Among the innate immune-related receptors such as Toll-like receptor (TLR) 1, 2, 4, 6, and CD14 examined by flow cytometry, only CD14 was up-regulated by vitamin D3 derivatives. Release of soluble form CD14 (sCD14) was also increased by vitamin D3 derivatives. The 1α,25-dihydroxy-22-oxavitamin D3 (Oxa-D3) induced-sCD14 release was inhibited by U0126 (a specific inhibitor of extracellular signal-regulated kinase; ERK1/2) but not by SB203580 (a specific inhibitor of p38 MAPK), and ERK1/2 phosphorylation was accelerated by Oxa-D3. These results indicate that Oxa-D3 facilitates the release of sCD14 through ERK1/2 activation. IL-8 production stimulated with LPS was diminished by vitamin D3 derivatives. Recombinant sCD14 also lowered the LPS-stimulated IL-8 production, suggesting neutralization of LPS by sCD14. The anti-inflammatory effect of vitamin D3 derivatives was thus associated with diminution of IL-8 production due to increased release of sCD14.

Current trends in inflammatory and immunomodulatory mediators in sepsis

Sepsis refers to severe systemic inflammation in response to invading pathogens. An overwhelming immune response, as mediated by the release of various inflammatory mediators, can lead to shock, multiple organ damage, and even death. Cytokines, proteases, lipid mediators, gaseous substances, vasoactive peptides, and cell stress markers play key roles in sepsis pathophysiology. Various adhesion molecules and chemokines sequester and activate neutrophils into the target organs, further augmenting inflammation and tissue damage. Although the anti-inflammatory substances counterbalance proinflammatory mediators, prolonged immune modulation may cause host susceptibility to concurrent infections, thus reflecting enormous challenge toward developing effective clinical therapy against sepsis. To understand the complex interplay between pro- and anti-inflammatory phenomenon in sepsis, there is still an unmet need to study newly characterized mediators. In addition, revealing the current trends of novel mediators will upgrade our understanding on their signal transduction, cross-talk, and synergistic and immunomodulating roles during sepsis. This review highlights the latest discoveries of the mediators in sepsis linking to innate and adaptive immune systems, which may lead to resolution of many unexplored queries.

Membrane-bound toll-like receptors are overexpressed in peripheral blood and synovial fluid mononuclear cells of enthesitis-related arthritis category of juvenile idiopathic arthritis (JIA–ERA) patients and lead to secretion of inflammatory mediators

We examined expression and function of TLRs in enthesitis-related arthritis (ERA) patients. RNA levels of TLR1, TLR3, and TLRs 5–8 were measured in 24 ERA peripheral blood mononuclear cells (PBMC), 18 synovial fluid mononuclear cells (SFMC), and IRAK1, IRAK4, TRIF, TRAF3, and TRAF6 in 18 PBMC and 10 SFMC. IL-6 and IL-8 were measured in supernatants from ERA PBMC (n=7), SFMC (n=3), and healthy PBMC (n=5) cultured with ligands for TLR1/2 (Pam 3-cys), TLR3 (polyI:C), TLR5 (flagellin), and TLR2/6 (zymosan). TLRs 1, 3, 5, and 6 were measured in whole blood (n=20 ERA, seven healthy) and SFMC (n=2) by flow cytometry. ERA PBMC compared to healthy PBMC and SFMC compared to ERA PBMC had higher RNA expression of TLR1, TLR3, TLR5, TLR6, IRAK1, IRAK4, TRIF, TRAF3, and TRAF6. TLR7 and TLR8 RNA expression was similar in all study groups. IL-6 and IL-8 levels were higher in stimulated ERA SFMC compared to ERA PBMC and in ERA PBMC compared to control PBMC. TLRs 1, 3, and 6 were also overexpressed at the protein level.

The Role of Nuclear Factor Kappa B in the Pathogenesis of Pulmonary Diseases: Implications for Therapy

The nuclear factor kappa B (NF-kappaB) transcription factor plays a key role in the induction of pro-inflammatory gene expression, leading to the synthesis of cytokines, adhesion molecules, chemokines, growth factors and enzymes. Results of studies in in vitro and in vivo models of inflammation and malignancy have also suggested central roles for NF-kappaB in programmed cell death, or apoptosis. NF-kappaB plays a central role in a variety of acute and chronic inflammatory diseases. In the common lung diseases associated with a significant inflammatory component such as severe sepsis, acute lung injury, acute respiratory distress syndrome, cystic fibrosis and asthma, the pathogenic roles of NF-kappaB have been extensively investigated. In COPD, activation of NF-kappaB has been implicated in disease pathogenesis but its exact role is less clearly demonstrable in this heterogeneous patient population. However, the principal risk factor for COPD, cigarette smoking, is strongly associated with NF-kappaB activation. Activation of NF-kappaB has been demonstrated in mineral dust diseases and probably plays a role in the pathogenesis of these chronic illnesses. NF-kB also plays a variety of roles in lung cancer including resistance to chemotherapy, inhibition of tumorigenesis and inducing expression of antiapoptotic genes. The complex NF-kappaB pathway offers a variety of potential molecular targets for chemotherapeutic intervention. A variety of agents aimed at modulating NF-kappaB activity are in various stages of investigation.

Gene expression profiling of dendritic cells in different physiological stages under Cordyceps sinensis treatment

Cordyceps sinensis (CS) has been commonly used as herbal medicine and a health supplement in China for over two thousand years. Although previous studies have demonstrated that CS has benefits in immunoregulation and anti-inflammation, the precise mechanism by which CS affects immunomodulation is still unclear. In this study, we exploited duplicate sets of loop-design microarray experiments to examine two different batches of CS and analyze the effects of CS on dendritic cells (DCs), in different physiology stages: naïve stage and inflammatory stage. Immature DCs were treated with CS, lipopolysaccharide (LPS), or LPS plus CS (LPS/CS) for two days, and the gene expression profiles were examined using cDNA microarrays. The results of two loop-design microarray experiments showed good intersection rates. The expression level of common genes found in both loop-design microarray experiments was consistent, and the correlation coefficients (Rs), were higher than 0.96. Through intersection analysis of microarray results, we identified 295 intersecting significantly differentially expressed (SDE) genes of the three different treatments (CS, LPS, and LPS/CS), which participated mainly in the adjustment of immune response and the regulation of cell proliferation and death. Genes regulated uniquely by CS treatment were significantly involved in the regulation of focal adhesion pathway, ECM-receptor interaction pathway, and hematopoietic cell lineage pathway. Unique LPS regulated genes were significantly involved in the regulation of Toll-like receptor signaling pathway, systemic lupus erythematosus pathway, and complement and coagulation cascades pathway. Unique LPS/CS regulated genes were significantly involved in the regulation of oxidative phosphorylation pathway. These results could provide useful information in further study of the pharmacological mechanisms of CS. This study also demonstrates that with a rigorous experimental design, the biological effects of a complex compound can be reliably studied by a complex system like cDNA microarray.

Toll-like receptor activation of human cells by synthetic triacylated lipid A-like molecules

Recognition of microbial molecules by mammalian host receptors is essential to mount an immune response. Hexaacylated LPS is the prototypic example of a bacterial molecule recognized by the receptor complex TLR4/MD-2 with its lipid A moiety, whereas bacterial lipopeptides are recognized by TLR2. Here we show that a series of synthetic triacylated lipid A-like molecules are weak Toll-like receptor (TLR) agonists (mainly TLR2 agonists) but very potent TLR4/MD-2 antagonists (submicromolar range). Not only do they block human cell responses to LPS but also to whole gram-negative bacteria, and they inhibit the phagocytosis of gram-negative bacteria. These compounds may represent promising immunomodulatory agents.

Cyptoporus polysaccharide prevents lipopolysaccharide-induced acute lung injury associated with down-regulating Toll-like receptor 2 expression

AIM OF THE STUDY

To evaluate the effects and the possible mechanism of Cryptoporus polysaccharides (CP) extracted from fruiting body of Cryptoporus volvatus in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and mice.

MATERIALS AND METHODS

Acute lung injury was induced by intratracheally instillation of LPS into lung in either rats or mice, assessing leukocyte numbers and myeloperoxidase activity in bronchoalveolar lavage fluid, as well as evaluating cytokines mRNA and protein expressions, and Toll-like receptor 2 (TLR(2)) and nuclear factor (NF)-κB mRNA levels in the lung tissues of mice. Vascular permeability and edema of lung in mice, and arterial blood gas in rats were also performed.

RESULTS

In ALI, CP-treated mice and rats exhibited significantly reduced leukocyte invasion, myeloperoxidase activity, vascular permeability, edema of lung, as well as tumor necrosis factor-α and Interleukin-1β mRNA and protein expressions in the lung tissues compared with vehicle-treated mice. TLR(2) and NF-κB mRNA levels of the lung tissues were decreased in CP-treated mice in response to LPS. And decline in arterial blood gas was recovered in CP-treated rats.

CONCLUSIONS

Our results supported a protective role of CP in ALI and suggested that the reduction of the activation of TLR(2) and NF-κB signal pathway in lung injury may be relavant to the pretreatment of CP.

Inhibition of Rac activity alleviates lipopolysaccharide-induced acute pulmonary injury in mice

BACKGROUND

Rac small GTPases play important roles in cytoskeleton and many cell functions including cell cycle, cell growth, cell adhesion and gene transcription. Here, we investigated the roles of Rac including Rac1 and Rac2 in lipopolysaccharide (LPS)-induced pulmonary injury.

METHODS

After LPS was intratracheally instilled to lungs in mice, Rac, CDC42 and RhoA activation assay by pull-down and West blot, inflammatory cell infiltration assay by counting cell numbers and lung histological examination, pro-inflammatory mediator mRNA expression assay by quantitative RT-PCR, measurement of myeloperoxidase (MPO) activity, Evans Blue and albumin accumulation by spectrophotometry were performed to evaluate the roles of Rac in pulmonary injury by using its specific inhibitor, NSC23766.

RESULTS

LPS challenge led to increases of both Rac1 and Rac2, but not CDC42 or RhoA activities in lungs, and intraperitoneal administration with NSC23766 inhibited both Rac1 and Rac2, but not CDC42 or RhoA activities. Treatment with NSC23766 at 1 or 3mg/kg not only reduced the inflammatory cells infiltration and MPO activities, but also inhibited pro-inflammatory mediators, tumor necrosis factor-α and interleukin-1β, mRNA expression. Moreover, in vitro neutrophil migration assay and in vivo microvascular permeability assay indicated that NSC23766 not only inhibited neutrophil transwell migration toward a chemoattractant, fMLP, but also reduced Evans Blue and albumin accumulation in LPS-challenged lungs. LPS activated both Rac1 and Rac2, but not CDC42 or RhoA activities in lungs, and specific inhibition of Rac activities by NSC23766 effectively alleviated LPS-induced injury.

GENERAL SIGNIFICANCE

Rac could be a potential target for therapeutic intervention of pulmonary inflammation.

Glucan phosphate attenuates myocardial HMGB1 translocation in severe sepsis through inhibiting NF-κB activation

Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. High-mobility group box 1 (HMGB1) serves as a late mediator of lethality in sepsis. We have reported that glucan phosphate (GP) attenuates cardiac dysfunction and increases survival in cecal ligation and puncture (CLP)-induced septic mice. In the present study, we examined the effect of GP on HMGB1 translocation from the nucleus to the cytoplasm in the myocardium of septic mice. GP was administered to mice 1 h before induction of CLP. Sham-operated mice served as control. The levels of HMGB1, Toll-like receptor 4 (TLR4), and NF-κB binding activity were examined. In an in vitro study, H9C2 cardiomyoblasts were treated with lipopolysaccharide (LPS) in the presence or absence of GP. H9C2 cells were also transfected with Ad5-IκBα mutant, a super repressor of NF-κB activity, before LPS stimulation. CLP significantly increased the levels of HMGB1, TLR4, and NF-κB binding activity in the myocardium. In contrast, GP administration attenuated CLP-induced HMGB1 translocation from the nucleus to the cytoplasm and reduced CLP-induced increases in TLR4 and NF-κB activity in the myocardium. In vitro studies showed that GP prevented LPS-induced HMGB1 translocation and NF-κB binding activity. Blocking NF-κB binding activity by Ad5-IκBα attenuated LPS-induced HMGB1 translocation. GP administration also reduced the LPS-stimulated interaction of HMGB1 with TLR4. These data suggest that attenuation of HMGB1 translocation by GP is mediated through inhibition of NF-κB activation in CLP-induced sepsis and that activation of NF-κB is required for HMGB1 translocation.

Differential cell sensitivity between OTA and LPS upon releasing TNF-α

The release of tumor necrosis factor α (TNF-α) by ochratoxin A (OTA) was studied in various macrophage and non-macrophage cell lines and compared with E. coli lipopolysaccharide (LPS) as a standard TNF-α release agent. Cells were exposed either to 0, 2.5 or 12.5 µmol/L OTA, or to 0.1 µg/mL LPS, for up to 24 h. OTA at 2.5 µmol/L and LPS at 0.1 µg/mL were not toxic to the tested cells as indicated by viability markers. TNF-α was detected in the incubated cell medium of rat Kupffer cells, peritoneal rat macrophages, and the mouse monocyte macrophage cell line J774A.1: TNF-α concentrations were 1,000 pg/mL, 1,560 pg/mL, and 650 pg/mL, respectively, for 2.5 µmol/L OTA exposure and 3,000 pg/mL, 2,600 pg/mL, and 2,115 pg/mL, respectively, for LPS exposure. Rat liver sinusoidal endothelial cells, rat hepatocytes, human HepG2 cells, and mouse L929 cells lacked any cytokine response to OTA, but showed a significant release of TNF-α after LPS exposure, with the exception of HepG2 cells. In non-responsive cell lines, OTA lacked both any activation of NF-κB or the translocation of activated NF-κB to the cell nucleus, i.e., in mouse L929 cells. In J774A.1 cells, OTA mediated TNF-α release via the pRaf/MEK 1/2-NF-κB and p38-NF-κB pathways, whereas LPS used pRaf/MEK 1/2–NF-κB, but not p38-NF-κB pathways. In contrast, in L929 cells, LPS used other pathways to activate NF-κB. Our data indicate that only macrophages and macrophage derived cells respond to OTA and are considered as sources for TNF-α release upon OTA exposure.

A patient with severe hypercalcemia in multiple organ dysfunction syndrome: role of elevated circulating 1alpha,25(OH)2 vitamin D levels

A 54-year-old man was transferred to our ICU because of systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). He died after 38 days of intensive care. During treatment, his serum calcium (Ca) levels continued to increase and reached 3.95 mmol/L, while the ionized Ca levels reached 2.30 mmol/L before his death. He presented with severe kidney injury, pancreatitis, and hemorrhagic gastric erosion that worsened his prognosis; these were possibly associated with the hypercalcemia. His circulating 1alpha,25-dihydroxyvitamin D [1,25(OH)(2)D] level was elevated (75.7 to 204 pg/mL), whereas the levels of 25-hydroxyvitamin D, parathyroid hormone, and parathyroid hormone-related peptide were not. Liver histology revealed immunoreactivity for 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1) in some of the hepatocytes, in which the localization pattern was similar to that of lysozyme-positive hepatocytes. Our ICU has previously encountered 22 similar MODS patients who presented with hypercalcemia over the last 8 years. SIRS with severe kidney and liver injuries are common clinical findings in hypercalcemic patients with MODS. Of the 23 hypercalcemic MODS patients, including the present patient, 17 had circulating 1,25(OH)(2)D levels exceeding 70 pg/mL despite severe kidney injury. Extrarenal activation of CYP27B1 seems to play a role in the development of hypercalcemia in this disease condition. Clinicians need to be aware that severe hypercalcemia may occur in MODS patients.

Design of novel indolicidin-derived antimicrobial peptides with enhanced cell specificity and potent anti-inflammatory activity

Indolicidin (IN) is a 13-residue Trp-rich antimicrobial peptide isolated from bovine neutrophils. To develop novel IN-derived antimicrobial peptides with enhanced cell specificity (therapeutic index) and potent anti-inflammatory activity, several IN analogs were synthesized by Pro-->Lys substitution. All IN analogs displayed an increase in therapeutic index by 3- to 15-fold relative to parental IN. IN and its analogs induced a significant membrane depolarization against intact Staphylococcus aureus in a dose-dependent manner and depolarized membrane potential at 5 microg/ml (MIC for S. aureus) almost completely. However, these peptides caused less than 40% calcein leakage from negatively charged EYPG/EYPE liposomes mimicking bacterial membranes at 10 microg/ml. Based on these results, we hypothesize that IN and its analogs kill microorganisms via the formation of small ion channels that permit transit of ions or protons, but not molecules as large as calcein. Furthermore, IN and its analogs induced a remarkable suppression in nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA expression in LPS-stimulated mouse macrophage RAW264.7 cells. All IN analogs showed LPS-binding activity comparable to that of IN. Taken together, their potent antimicrobial, anti-inflammatory and LPS-neutralizing activities similar to those of IN, coupled with their no cytotoxicity, our designed IN analogs make excellent candidates for novel antimicrobial and anti-sepsis agents.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Influence of obesity on sepsis

Sepsis is the leading cause of death in non-coronary intensive care units worldwide, with a very high cost of care. There is a growing body of evidence suggesting that the increase in morbidity associated with severe obesity in critically ill patients results in increased resource utilization adding further to the cost of care. There is a relative paucity of information regarding the pathophysiology and treatment of obese critically ill patients, especially with sepsis. Obesity as an exclusion criterion in landmark trials is partly responsible for this paucity. While the preventive strategies for obesity will be the most definitive long-term solution, it will take a long time to affect outcomes in our intensive care units. In the meantime, our hospitals, including the intensive care units must continue to treat obese/morbidly obese critically ill patients with sepsis, making it essential to study and understand the pathophysiology and develop treatment strategies for obese with sepsis. Available laboratory data suggests an increased inflammatory response in obese septic individuals. However, the association between obesity and sepsis in the clinical setting is unclear due to controversial results. This article reviews the available clinical and laboratory data that addresses the effects of obesity on sepsis.

Role of Toll-like receptors in the development of sepsis

The outcome of sepsis and septic shock has not significantly improved in recent decades despite the development of numerous drugs and supportive care therapies. To reduce sepsis-related mortality, a better understanding of molecular mechanism(s) associated with the development of sepsis and sepsis-related organ injury is essential. There is increasing evidence that Toll-like receptors (TLRs) play a key role in the mediation of systemic responses to invading pathogens during sepsis. However, the role of TLRs in the development of sepsis and in sepsis-related organ injury remains debatable. In this review, we focus on the biological significance of TLRs during sepsis. Medline was searched for pertinent publications relating to TLRs, with emphasis on their clinical and pathophysiological importance in sepsis. In addition, a summary of the authors' own experimental data from this field was set in the context of current knowledge regarding TLRs. In both animal models and human sepsis, TLRs are highly expressed on monocytes/macrophages, and this TLR expression may not simply be a ligand-specific response in such an environment. The fact that TLR signaling enables TLRs to recognize harmful mediators induced by invading pathogens may be associated with a positive feedback loop for the inflammatory response among different cell populations. This mechanism(s) may contribute to the organ dysfunction and mortality that occurs in sepsis. A better understanding of TLR biology may unveil novel therapeutic approaches for sepsis.

TAK-242 selectively suppresses Toll-like receptor 4-signaling mediated by the intracellular domain

TAK-242, a small-molecule antisepsis agent, has shown to suppress lipopolysaccharide (LPS)-induced inflammation. In this study, we demonstrate that TAK-242 is a selective inhibitor of Toll-like receptor (TLR)-4 signaling. TAK-242 almost completely suppressed production of nitric oxide (NO) or tumor necrosis factor (TNF)-alpha induced by a TLR4-specific ligand, ultra-pure LPS, in mouse RAW264.7, human U-937 and P31/FUJ cells, whereas this agent showed little effect on other TLR ligands, Pam(3)CSK(4) (TLR1/2), peptidoglycan (TLR2/6), double strand RNA (TLR3), R-848 (TLR7) and CpG oligonucleotide (TLR9). Furthermore, TAK-242 potently inhibited nuclear factor (NF)-kappaB activation induced by ultra-pure LPS in HEK293 cells transiently expressing TLR4 and co-receptors, myeloid differentiation protein-2 (MD2) and CD14, whereas this agent showed little effect on other TLRs, TLR1/2, TLR2/6, TLR3, TLR5, TLR7 and TLR9. TAK-242 also inhibited ligand-independent NF-kappaB activation resulting from over-expression of TLR4. Although chimera receptors, which are consist of the extracellular domain of CD4 and the intracellular domain of human or mouse TLR4, showed constitutive NF-kappaB activation, TAK-242 potently inhibited the signaling from CD4-TLR4 chimera receptors. In contrast, the NF-kappaB activation mediated by TLR4 adaptors, myeloid differentiation factor 88 (MyD88), TIR-associated protein (TIRAP), Toll/IL-1R homology (TIR)-domain-containing adaptor protein-inducing interferon-beta (TRIF) or TRIF-related adaptor molecule (TRAM) was not affected by TAK-242. TAK-242 is therefore a selective inhibitor of signaling from the intracellular domain of TLR4 and represents a novel therapeutic approach to the treatment of TLR4-mediated diseases.

Sepsis: from bench to bedside

Sepsis is a syndrome related to severe infections. It is defined as the systemic host response to microorganisms in previously sterile tissues and is characterized by end-organ dysfunction away from the primary site of infection. The normal host response to infection is complex and aims to identify and control pathogen invasion, as well as to start immediate tissue repair. Both the cellular and humoral immune systems are activated, giving rise to both anti-inflammatory and proinflammatory responses. The chain of events that leads to sepsis is derived from the exacerbation of these mechanisms, promoting massive liberation of mediators and the progression of multiple organ dysfunction. Despite increasing knowledge about the pathophysiological pathways and processes involved in sepsis, morbidity and mortality remain unacceptably high. A large number of immunomodulatory agents have been studied in experimental and clinical settings in an attempt to find an efficacious anti-inflammatory drug that reduces mortality. Even though preclinical results had been promising, the vast majority of these trials actually showed little success in reducing the overwhelmingly high mortality rate of septic shock patients as compared with that of other critically ill intensive care unit patients. Clinical management usually begins with prompt recognition, determination of the probable infection site, early administration of antibiotics, and resuscitation protocols based on "early-goal" directed therapy. In this review, we address the research efforts that have been targeting risk factor identification, including genetics, pathophysiological mechanisms and strategies to recognize and treat these patients as early as possible.

Sepsis

Sepsis is a clinical syndrome defined by a systemic response to infection. With progression to sepsis-associated organ failure (ie, severe sepsis) or hypotension (ie, septic shock) mortality increases. Sepsis is a cause of considerable mortality, morbidity, cost, and health care utilization. Abnormalities in the inflammation, immune, coagulation, oxygen delivery, and utilization pathways play a role in organ dysfunction and death. Early identification of septic patients allows for evidence-based interventions, such as prompt antibiotics, goal-directed resuscitation, and activated protein C. Appropriate care for sepsis may be more easily delivered by dividing this clinical entity into various stages and with changes in structures of delivery that extend across traditional boundaries. Better description of the molecular basis of the disease process also will allow for more targeted therapies.

An introduction to Toll-like receptors and their possible role in the initiation of labour

Toll-like receptors (TLR) have emerged as key upstream mediators of inflammation at many tissue sites in humans. Inflammatory processes are involved in the process of parturition suggesting that TLR activity within gestation-associated tissues might have an important role in the initiation and/or maintenance of normal term labour and in various pathological states of pregnancy such as infection-associated preterm labour. Either TLRs or their signalling molecules might be excellent therapeutic targets for prevention of preterm labour.

Pharmacokinetic Characteristics of Antimicrobials and Optimal Treatment of Urosepsis

Urosepsis accounts for approximately 25% of all sepsis cases and may develop from a community-acquired or nosocomial urinary tract infection (UTI). Nevertheless, the underlying UTI is almost exclusively a complicated one with involvement of the parenchymatous urogenital organs (e.g. kidneys, prostate) and mostly associated with any kind of obstructive uropathy. If urosepsis originates from a nosocomial infection, a broad spectrum of Gram-negative and Gram-positive pathogens have to be expected, which are often multiresistant. In urosepsis, as in other types of sepsis, the severity of sepsis depends mostly upon the host response. The treatment of urosepsis follows the generally accepted rules of the 'Surviving Sepsis' campaign guidelines. Early normalisation of blood pressure and early adequate empirical antibacterial therapy with optimised dosing are equally important to meet the requirements of early goal-directed therapy. In most cases of urosepsis, early control of the infectious focus is possible and as important. Optimal supportive measures need to follow the early phase of resuscitation. To lower mortality from urosepsis, an optimal interdisciplinary approach between intensive care, anti-infective therapy and urology is essential, assisted by easy access to the necessary laboratory and imaging diagnostic procedures. Although most antibacterials achieve high urinary concentrations, there are several unique features of complicated UTI, and thus urosepsis, that influence the activity of antibacterial substances: (i) renal pharmacokinetics differ in unilateral and bilateral renal impairment and in unilateral and bilateral renal obstruction; (ii) variations in pH may influence the activity of certain antibacterials; and (iii) biofilm infection is frequently found under these conditions, which may increase the minimal inhibitory concentrations (MIC) of the antibacterials at the site of infection by several hundred folds. Assessment of antibacterial pharmacodynamic properties in such situations should take into account not only the MIC as determined in vitro and the plasma concentrations of the free (unbound) drug, which are the guiding principles for many infections, but also the actual renal excretion and urinary bactericidal activity of the antibacterial substance. In the treatment of urosepsis, it is important to achieve optimal exposure to antibacterials both in plasma and in the urinary tract. The role of drugs with low renal excretion rates is therefore limited. Since urosepsis quite often originates from catheter-associated UTI and urological interventions, optimal catheter care and optimal strategies to prevent nosocomial UTI may be able to reduce the frequency of urosepsis.

In silico identification and biological evaluation of antimicrobial peptides based on human cathelicidin LL-37

Bacterial lipopolysaccharides (LPS) are important triggers of the widespread inflammatory response, which contributes to the development of multiple organ failure during sepsis. The helical 37-amino-acid-long human antimicrobial peptide LL-37 not only possesses a broad-spectrum antimicrobial activity but also binds and neutralizes LPS. However, the use of LL-37 in sepsis treatment is hampered by the fact that it is also cytotoxic. To find a less toxic analog of LL-37, we used in silico analysis to identify amphipathic helical regions of LL-37. A 21-amino-acid fragment (GKE) was synthesized, the biological actions of which were compared to those of two equally long peptides derived from the N and C termini of LL-37 as well as native LL-37. GKE displayed antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Candida parapsilosis that was similar to or even stronger than LL-37. GKE, as well as the equally long control peptides, attracted granulocytes in a fashion similar to that of LL-37, while only GKE was as potent as LL-37 in inhibiting LPS-induced vascular nitric oxide production. GKE caused less hemolysis and apoptosis in human cultured smooth muscle cells than LL-37. In summary, we have identified an active domain of LL-37, GKE, which displays antimicrobial activity in vitro and LPS-binding activity similar to those of LL-37 but is less toxic. GKE therefore holds promise as a template for the development of peptide antibiotics for the treatment of sepsis.

Role of Toll-like receptors in infection and immunity: clinical implications

The remarkable discovery of the Toll-like receptors (TLRs) over the past 5 years has opened up an entirely new era in the understanding of the molecular events that initiate the inflammatory response. These type 1 transmembrane receptors are expressed on a large number of immune cells as well as epithelial cells and play an essential role in the activation of the innate immune response to microbial pathogens. They impact on adaptive immune reactions and contribute to the initiation and maintenance of the inflammatory response to a multitude of potential microbial pathogens through recognition of pathogen-associated molecular patterns. TLRs also interact with a variety of endogenous human ligands and influence the activity of a wide range of tissues and cell processes. Among the common and important processes in which TLRs play a role are asthma, acute respiratory distress syndrome, cardiac ischaemia, coronary artery disease, ventricular remodelling, vascular collapse, inflammatory bowel disease, acute tubular necrosis, psoriasis, rheumatoid arthritis, pre-term birth, fertility, cancer angiogenesis and transplant rejection. From this strikingly diverse list, many important opportunities for disease modification through TLR manipulation can be imagined. Their role as potential targets for therapeutic intervention is just beginning to be appreciated, and the current status of these treatment strategies is reviewed in this article.

Vitamin D3 down-regulates monocyte TLR expression and triggers hyporesponsiveness to pathogen-associated molecular patterns

Toll-like receptors (TLR) represent an ancient front-line defence system that enables the host organism to sense the presence of microbial components within minutes. As inducers of inflammation, TLR act as important triggers of distinct entities such as sepsis or autoimmune disease exacerbation. We report here that vitamin D3 [1alpha,25-dihydroxycholecalciferol, 1,25(OH)(2)D3] suppresses the expression of TLR2 and TLR4 protein and mRNA in human monocytes in a time- and dose-dependent fashion. Despite 1,25(OH)(2)D3-induced up-regulation of CD14, challenge of human monocytes with either LPS or lipoteichoic acid resulted in impaired TNF-alpha and procoagulatory tissue factor (CD142) production, emphasizing the critical role of TLR in the induction of inflammation. Moreover, reduced TLR levels in 1,25(OH)(2)D3-treated phagocytes were accompanied by impaired NF-kappaB/RelA translocation to the nucleus and by reduced p38 and p42/44 (extracellular signal-regulated kinase 1/2) phosphorylation upon TLR-ligand engagement. Both TLR down-regulation and CD14 up-regulation were substantially inhibited by the vitamin D receptor (VDR) antagonist ZK 159222, indicating that the immunomodulatory effect of 1,25(OH)(2)D3 on innate immunity receptors requires VDR transcription factor activation. Our data provide strong evidence that 1,25(OH)(2)D3 primes monocytes to respond less effectively to bacterial cell wall components in a VDR-dependent mechanism, most likely due to decreased levels of TLR2 and TLR4.

Syndecan 1 shedding contributes to Pseudomonas aeruginosa sepsis

The innate immune system is comprised of many components that function coordinately to prevent bacterial sepsis. However, thermal injury suppresses many of these factors, and the opportunistic pathogen Pseudomonas aeruginosa takes advantage of this condition, making it one of the leading causes of morbidity and mortality in the setting of thermal injury. P. aeruginosa is extremely efficient at colonizing burn wounds, spreading systemically, and causing sepsis, which often results in a systemic inflammatory response, multiple-organ failure, and death. The pathogenicity of P. aeruginosa is due to the arsenal of virulence factors produced by the pathogen and the immunocompromised state of the host. Syndecan 1 is a major heparan sulfate proteoglycan present on many host cells involved in thermal injury. Syndecan 1 anchored to the cell surface can be cleaved in a process termed ectodomain shedding. Syndecan 1 shedding results in the release of intact, soluble proteoglycan ectodomains that have diverse roles in innate immunity. Here we show for the first time that thermal injury results in shedding of syndecan 1 from host tissue. Our data show that syndecan 1 null mice are significantly less susceptible to P. aeruginosa infection than their wild-type counterparts, as demonstrated by (i) significantly lower mortality; (ii) absence of systemic spread of P. aeruginosa; and (iii) significant reductions in some proinflammatory cytokines. These results suggest that shed syndecan 1 plays an important role in the pathogenesis of P. aeruginosa infection of thermal injury and that syndecan 1-neutralizing agents may be effective supplements to current P. aeruginosa treatments.

The Toll-like receptors and their role in septic shock

The Toll-like receptors (TLRs) are a class of pattern recognition molecules with unique functions in the innate and the acquired immune systems. The innate immune response has evolved as the immediate host defence system in response to foreign structures and it also serves to prime the adaptive immune response. As such, the TLRs set the tone and pace of the inflammatory response that follows initial contact with a microbial pathogen over the course of the following minutes, hours and days. Sepsis, a leading cause of death in critically ill patients worldwide, is defined as 'the systemic inflammatory response syndrome that occurs during infection' [1]; that is, sepsis is the orchestration of the events controlled by the gene products triggered by signals transduced through the TLRs. Through analysis of the human genome, ten TLRs have been identified, and several of them have been characterised with respect to their associated ligands. Following engagement of the cognate ligand to the ectodomain of each TLR, the assembly of intracellular homo- or heterodimers or multimers induces cell signalling. The receptors are variably expressed on different types of cells, such as neutrophils, dendritic cells, lymphocytes, endothelial cells etc. and can be up- and downregulated, blocked or triggered by mimetic substances. By controlling or modifying TLR responses, the trajectory of the entire septic process may be modified. This review covers the events responsible for TLR activation in detail, with an emphasis on possible points of pharmacological intervention.

THE USE OF IMMUNOCOMPROMISED ANIMALS AS MODELS FOR HUMAN SEPTIC SHOCK

Although it is generally understood that no single animal model truly reflects human sepsis, the study of sepsis in immunocompromised animals is highly relevant to human sepsis research. The majority of patients with severe sepsis have significant underlying diseases that may alter innate immune defenses, disrupt microbial clearance mechanisms, and complicate the pathophysiology of human sepsis. Septic shock itself has significant effects upon the innate and adaptive host immune responses that may contribute to a state of sepsis-induced immune dysregulation. A number of animal models of sepsis displaying an array of immunocompromised states are now available. Most of these systems are small animal models with genetically defined defects of immune defenses or acquired defects from receipt of immunosuppressive or myeloablative agents. Greater emphasis should be placed on preclinical models of immunocompromised animals in the future to assess the potential clinical utility of novel drugs for human septic shock.

A pilot-controlled study of a polymyxin B-immobilized hemoperfusion cartridge in patients with severe sepsis secondary to intra-abdominal infection

Endotoxin is an important pathogenic trigger for sepsis. The polymyxin B-immobilized endotoxin removal hemoperfusion cartridge, Toraymyxin (hereafter PMX), has been shown to remove endotoxin in preclinical and open-label clinical studies. In a multicenter, open-label, pilot, randomized, controlled study conducted in the intensive care unit in six academic medical centers in Europe, 36 postsurgical patients with severe sepsis or septic shock secondary to intra-abdominal infection were randomized to PMX treatment of 2 h (n = 17) or standard therapy (n = 19). PMX was well tolerated and showed no significant side effects. There were no statistically significant differences in the change in endotoxin levels from baseline to 6 to 8 h after treatment or to 24 h after treatment between the two groups. There was also no significant difference in the change in interleukin (IL)-6 levels from baseline to 6 to 8 h after treatment or to 24 h after treatment between the two groups. Patients treated with PMX demonstrated significant increases in cardiac index (CI; P = 0.012 and 0.032 at days 1 and 2, respectively), left ventricular stroke work index (LVSWI, P = 0.015 at day 2), and oxygen delivery index (DO2I, P = 0.007 at day 2) compared with the controls. The need for continuous renal replacement therapy (CRRT) after study entry was reduced in the PMX group (P = 0.043). There was no significant difference between the groups in organ dysfunction as assessed by the Sequential Organ Failure Assessment (SOFA) scores from day 0 (baseline) to day 6. Treatment using the PMX cartridge is safe and may improve cardiac and renal dysfunction due to sepsis or septic shock. Further studies are needed to prove this effectiveness.

Pathophysiology of Mifepristone-Induced Septic Shock Due toClostridium sordellii

OBJECTIVE:

To explain the role of mifepristone in medical abortions that results in fulminant and lethal septic shock due to Clostridium sordellii.

DATA SOURCES:

MEDLINE, PubMed, and Google Scholar databases were searched (1984–March 2005%). Key search terms were mifepristone, RU38486, RU486, Mifeprex, medical abortion, septic shock, innate immune system, cytokines, and Clostridium sordellii.

STUDY SELECTION AND DATA EXTRACTION:

All articles identified from the data sources were evaluated and all information deemed relevant was included for the information related to the development of the understanding of the pathophysiology of mifepristone-induced septic shock due to C. sordellii.

DATA SYNTHESIS:

The mechanisms of action of mifepristone were incorporated into the pathophysiology of septic shock due to C. sordellii. Mifepristone, by blocking both progesterone and glucocorticoid receptors, interferes with the controlled release and functioning of cortisol and cytokines. Failure of physiologically controlled cortisol and cytokine responses results in an impaired innate immune system that results in disintegration of the body's defense system necessary to prevent the endometrial spread of C. sordellii infection. The abnormal cortisol and cytokine responses due to mifepristone coupled to the release of potent exotoxins and an endotoxin from C. sordellii are the major contributors to the rapid development of lethal septic shock.

CONCLUSIONS:

Theoretically, it appears that the mechanisms of mifepristone action favor the development of infection that leads to septic shock and intensifies the actions of multiple inflammatory cytokines, resulting in fulminant, lethal septic shock.