Tumor necrosis factor and interleukin-1 in the serum of children with severe infectious purpura

How I diagnose and treat acute infection-associated purpura fulminans

ABSTRACT

Purpura fulminans (PF) is a rare but devastating complication of sepsis characterized by a highly thrombotic subtype of disseminated intravascular coagulation (DIC). A medical emergency, PF often requires the involvement of consultant hematologists to assist with diagnosis and management of patients who are in a highly dynamic and deteriorating clinical situation. Patients who survive past the first 24 to 72 hours often die from complications of unchecked thrombosis rather than shock, and survivors are usually left with severe scarring and tissue loss. Despite these challenging features, PF is a pathophysiologically distinct, homogeneous, and highly predictable form of sepsis-associated DIC for which poor outcomes are not a foregone conclusion. The fundamental pathologic lesion in PF is a failure of the anticoagulant protein C pathway, which leads to uncontrolled microvascular clotting and inadequate protein C-mediated cytoprotective effects, which are vital for survival in sepsis. Herein, we review the clinical features and diagnosis of PF. Drawing from existing clinical literature and recent advances in our understanding of the pathophysiology of PF, we describe rationally designed treatment approaches for this disorder, including repletion of natural circulating anticoagulants, use of therapeutic anticoagulation, and ways to optimize transfusion support, and we outline specific interventions that we would recommend avoiding.

Isolation, characterization and liposome-loaded encapsulation of a novel virulent Salmonella phage vB-SeS-01

Introduction

Salmonella is a common foodborne pathogenic bacterium, displaying facultative intracellular parasitic behavior, which can help the escape against antibiotics treatment. Bacteriophages have the potential to control both intracellular and facultative intracellular bacteria and can be developed as antibiotic alternatives.

Methods

This study isolated and characterized vB-SeS-01, a novel Guernseyvirinae phage preying on Salmonella enterica, whose genome is closely related to those of phages SHWT1 and vB-SenS-EnJE1. Furthermore, nine phage-carrying liposome formulations were developed by film hydration method and via liposome extruder.

Results and Discussion

Phage vB-SeS-01 displays strong lysis ability against 9 out of 24 tested S. enterica strains (including the pathogenic "Sendai" and "Enteritidis" serovars), high replicability with a burst size of 111 ± 15 PFU/ cell and a titre up to 2.1 × 1011 PFU/mL, and broad pH (4.0 ~ 13.0) and temperature (4 ~ 80°C) stabilities. Among the nine vB-SeS-01 liposome-carrying formulations, the one encapsulated with PC:Chol:T80:SA = 9:1:2:0.5 without sonication displayed the optimal features. This formulation carried up to 1011 PFU/mL, with an encapsulation rate of 80%, an average size of 172.8 nm, and a polydispersity index (PDI) of 0.087. It remained stable at 4°C and 23°C for at least 21 days and at 37°C for 7 days. Both vB-SeS-01 and vB-SeS-01-loaded liposomes displayed intracellular antimicrobial effects and could reduce the transcription level of some tested intracellular inflammatory factors caused by the infected S. enterica sv. Sendai 16,226 and Enteritidis 50041CMCC.

Adjunctive immunotherapeutic agents in patients with sepsis and septic shock: a multidisciplinary consensus of 23

BACKGROUND

In the last decades, several adjunctive treatments have been proposed to reduce mortality in septic shock patients. Unfortunately, mortality due to sepsis and septic shock remains elevated and NO trials evaluating adjunctive therapies were able to demonstrate any clear benefit. In light of the lack of evidence and conflicting results from previous studies, in this multidisciplinary consensus, the authors considered the rational, recent investigations and potential clinical benefits of targeted adjunctive therapies.

METHODS

A panel of multidisciplinary experts defined clinical phenotypes, treatments and outcomes of greater interest in the field of adjunctive therapies for sepsis and septic shock. After an extensive systematic literature review, the appropriateness of each treatment for each clinical phenotype was determined using the modified RAND/UCLA appropriateness method.

RESULTS

The consensus identified two distinct clinical phenotypes: patients with overwhelming shock and patients with immune paralysis. Six different adjunctive treatments were considered the most frequently used and promising: (i) corticosteroids, (ii) blood purification, (iii) immunoglobulins, (iv) granulocyte/monocyte colony-stimulating factor and (v) specific immune therapy (i.e. interferon-gamma, IL7 and AntiPD1). Agreement was achieved in 70% of the 25 clinical questions.

CONCLUSIONS

Although clinical evidence is lacking, adjunctive therapies are often employed in the treatment of sepsis. To address this gap in knowledge, a panel of national experts has provided a structured consensus on the appropriate use of these treatments in clinical practice.

Low-frequency inherited complement receptor variants are associated with purpura fulminans

ABSTRACT

Extreme disease phenotypes can provide key insights into the pathophysiology of common conditions, but studying such cases is challenging due to their rarity and the limited statistical power of existing methods. Herein, we used a novel approach to pathway-based mutational burden testing, the rare variant trend test (RVTT), to investigate genetic risk factors for an extreme form of sepsis-induced coagulopathy, infectious purpura fulminans (PF). In addition to prospective patient sample collection, we electronically screened over 10.4 million medical records from 4 large hospital systems and identified historical cases of PF for which archived specimens were available to perform germline whole-exome sequencing. We found a significantly increased burden of low-frequency, putatively function-altering variants in the complement system in patients with PF compared with unselected patients with sepsis (P = .01). A multivariable logistic regression analysis found that the number of complement system variants per patient was independently associated with PF after controlling for age, sex, and disease acuity (P = .01). Functional characterization of PF-associated variants in the immunomodulatory complement receptors CR3 and CR4 revealed that they result in partial or complete loss of anti-inflammatory CR3 function and/or gain of proinflammatory CR4 function. Taken together, these findings suggest that inherited defects in CR3 and CR4 predispose to the maladaptive hyperinflammation that characterizes severe sepsis with coagulopathy.

ASC-expressing pyroptotic extracellular vesicles alleviate sepsis by protecting B cells

Pyroptosis is an inflammatory programmed cell death process characterized by membrane rupture. Interestingly, pyroptotic cells can generate plenty of nanosized vesicles. Non-inflammatory apoptotic cell death-derived apoptotic vesicles (apoVs) were systemically characterized and displayed multiple physiological functions and therapeutic potentials. However, the characteristics of pyroptotic cell-generated extracellular vesicles (EVs) are largely unknown. Here, we identified a group of pyroptotic EVs (pyroEVs) from in vitro cultured pyroptotic mesenchymal stem cells (MSCs), as well as from septic mouse blood. Compared with apoVs, pyroEVs express similar levels of annexin V, calreticulin, and common EV markers, but express a decreased level of apoptotic marker cleave caspase-3. PyroEVs, but not apoVs and exosomes, specifically express pyroptotic maker apoptosis-associated speck-like protein containing CARD (ASC). More importantly, MSC-derived pyroEVs protect B cells in the spleen and bone marrow to relieve inflammatory responses and enhance the survival rate of the septic mice. Mechanistically, pyroEV membrane-expressed ASC binds to B cells to repress cell death by repressing Toll-like receptor 4. This study uncovered the characteristics of pyroEVs and their therapeutic role in sepsis and B cell-mediated immune 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.

Involvement of Inflammasome Components in Kidney Disease

Inflammasomes are multiprotein complexes with an important role in the innate immune response. Canonical activation of inflammasomes results in caspase-1 activation and maturation of cytokines interleukin-1β and -18. These cytokines can elicit their effects through receptor activation, both locally within a certain tissue and systemically. Animal models of kidney diseases have shown inflammasome involvement in inflammation, pyroptosis and fibrosis. In particular, the inflammasome component nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) and related canonical mechanisms have been investigated. However, it has become increasingly clear that other inflammasome components are also of importance in kidney disease. Moreover, it is becoming obvious that the range of molecular interaction partners of inflammasome components in kidney diseases is wide. This review provides insights into these current areas of research, with special emphasis on the interaction of inflammasome components and redox signalling, endoplasmic reticulum stress, and mitochondrial function. We present our findings separately for acute kidney injury and chronic kidney disease. As we strictly divided the results into preclinical and clinical data, this review enables comparison of results from those complementary research specialities. However, it also reveals that knowledge gaps exist, especially in clinical acute kidney injury inflammasome research. Furthermore, patient comorbidities and treatments seem important drivers of inflammasome component alterations in human kidney disease.

Ulinastatin protects against sepsis‑induced myocardial injury by inhibiting NLRP3 inflammasome activation

Myocardial injury is the primary manifestation of multiple organ dysfunction during sepsis, however, the mechanisms underlying sepsis-induced myocardial injury remain unclear. Similarly, no effective therapeutics have yet been developed for myocardial injury. In the present study, the role of the NOD-like receptor 3 (NLRP3) inflammasome on cardiac function were characterized and the effects of different ulinastatin (UTI) doses in protecting a septic rat model from myocardial injury were elucidated. To evaluate UTI efficacy on cardiac function, its effects on anti-inflammatory mediators were analyzed and its cardioprotective effects were investigated. It was demonstrated that circulatory levels of tumor necrosis factor-α and interleukin-1β were elevated during sepsis. It was also observed that NLRP3 and caspase-1 expression enhanced post-cecal ligation and puncture (CLP), and that high UTI levels protected against myocardial injury induced by sepsis. To the best of our knowledge, this is the first study to demonstrate that the mechanisms underpinning UTI-mediated myocardial protection were due to the downregulation of the NLRP3/caspase-1/IL-1β signaling pathway. Based on these findings, it is proposed that UTI exerts beneficial effects during sepsis-induced myocardial injury.

β-Sitosterol Alters the Inflammatory Response in CLP Rat Model of Sepsis by Modulation of NFκB Signaling

Purpose

Sepsis originates from the host inflammatory response, especially to bacterial infections, and is considered one of the main causes of death in intensive care units. Various agents have been developed to inhibit mediators of the inflammatory response; one prospective agent is β-sitosterol (βS), a phytosterol with a structure similar to cholesterol. This study is aimed at evaluating the effects of βS on the biomarkers of inflammation and liver function in cecal ligation and puncture- (CLP-) induced septic rats.

Methods

Thirty male Wistar rats were divided equally into six groups as follows: sham, CLP, CLP+dexamethasone (DX, 0.2 mg/kg), CLP+βS (1 mg/kg), CLP+imipenem (IMI, 20 mg/kg), and CLP+IMI (20 mg/kg)+βS (1 mg/kg). Serum levels of IL-1β, IL-6, IL-10, AST, ALT, and liver glutathione (GSH) were assessed by ELISA. Liver expression levels of TNF-α and NF-κBi mRNAs were evaluated by RT-qPCR.

Results

Serum concentrations of IL-1β, IL-6, IL-10, ALT, and AST and mRNA levels of TNF-α and NF-κBi were all significantly higher in septic rats than in normal rats (p < 0.05). Liver GSH content was markedly lower in the CLP group than that in the sham group. βS-treated rats had remarkably lower levels of IL-1β, IL-6, IL-10, TNF-α, NF-κBi, AST, and ALT (51.79%, 62.63%, 41.46%, 54.35%, 94.37%, 95.30%, 34.87%, and 46.53% lower, respectively) and greater liver GSH content (35.71% greater) compared to the CLP group (p < 0.05).

Conclusion

βS may play a protective role in the septic process by mitigating inflammation. This effect is at least partly mediated by inhibition of the NF-κB signaling pathway. Thus, βS can be considered as a supplementary treatment in septic patients.

Type IV pilus retraction enables sustained bacteremia and plays a key role in the outcome of meningococcal sepsis in a humanized mouse model

Neisseria meningitidis (the meningococcus) remains a major cause of bacterial meningitis and fatal sepsis. This commensal bacterium of the human nasopharynx can cause invasive diseases when it leaves its niche and reaches the bloodstream. Blood-borne meningococci have the ability to adhere to human endothelial cells and rapidly colonize microvessels. This crucial step enables dissemination into tissues and promotes deregulated inflammation and coagulation, leading to extensive necrotic purpura in the most severe cases. Adhesion to blood vessels relies on type IV pili (TFP). These long filamentous structures are highly dynamic as they can rapidly elongate and retract by the antagonistic action of two ATPases, PilF and PilT. However, the consequences of TFP dynamics on the pathophysiology and the outcome of meningococcal sepsis in vivo have been poorly studied. Here, we show that human graft microvessels are replicative niches for meningococci, that seed the bloodstream and promote sustained bacteremia and lethality in a humanized mouse model. Intriguingly, although pilus-retraction deficient N. meningitidis strain (ΔpilT) efficiently colonizes human graft tissue, this mutant did not promote sustained bacteremia nor induce mouse lethality. This effect was not due to a decreased inflammatory response, nor defects in bacterial clearance by the innate immune system. Rather, TFP-retraction was necessary to promote the release of TFP-dependent contacts between bacteria and, in turn, the detachment from colonized microvessels. The resulting sustained bacteremia was directly correlated with lethality. Altogether, these results demonstrate that pilus retraction plays a key role in the occurrence and outcome of meningococcal sepsis by supporting sustained bacteremia. These findings open new perspectives on the role of circulating bacteria in the pathological alterations leading to lethal sepsis.

Cytokines in Febrile Diseases

The human body has a perfect thermoregulatory system to meet the needs of normal life activities. The central regulation of body temperature is mainly explained by the theory of "setting point (setpoint, SP)". Fever is a positive but nonspecific response of the body to infections and other pyrogens, which causes immune cells to release cytokines, leading to a brain protein-mediated rise in body temperature. Cytokines can be roughly divided into 2 categories: proinflammatory cytokines and anti-inflammatory cytokines. IL-1, TNF-α, and IL-6 are proinflammatory cytokines, whereas IL-4 and IL-10 are anti-inflammatory cytokines. IL-2 is a cytokine that can both activate and inhibit immunity. IL-8 is a neutrophil chemotactic factor, and IFN is a cytokine that plays a key role in the proper induction and maintenance of innate and acquired immunity. This article reviews the pathophysiological characteristics of fever and the cytokines related to fever (IL-2, 4, 6, 8, 10, IFN, TNF, etc.).

Multi-tiered screening and diagnosis strategy for COVID-19: a model for sustainable testing capacity in response to pandemic

Coronavirus disease 2019 (COVID-19), caused by novel enveloped single stranded RNA coronavirus (SARS-CoV-2), is responsible for an ongoing global pandemic. While other countries deployed widespread testing as an early mitigation strategy, the U.S. experienced delays in development and deployment of organism identification assays. As such, there is uncertainty surrounding disease burden and community spread, severely hampering containment efforts. COVID-19 illuminates the need for a tiered diagnostic approach to rapidly identify clinically significant infections and reduce disease spread. Without the ability to efficiently screen patients, hospitals are overwhelmed, potentially delaying treatment for other emergencies. A multi-tiered, diagnostic strategy incorporating a rapid host immune response assay as a screening test, molecular confirmatory testing and rapid IgM/IgG testing to assess benefit from quarantine/further testing and provide information on population exposure/herd immunity would efficiently evaluate potential COVID-19 patients. Triaging patients within minutes with a fingerstick rather than hours/days after an invasive swab is critical to pandemic response as reliance on the existing strategy is limited by assay accuracy, time to results, and testing capacity. Early screening and triage is achievable from the outset of a pandemic with point-of-care host immune response testing which will improve response time to clinical and public health actions.Key messagesDelayed testing deployment has led to uncertainty surrounding overall disease burden and community spread, severely hampering public health containment and healthcare system preparation efforts.A multi-tiered testing strategy incorporating rapid, host immune point-of-care tests can be used now and for future pandemic planning by effectively identifying patients at risk of disease thereby facilitating quarantine earlier in the progression of the outbreak during the weeks and months it can take for pathogen specific confirmatory tests to be developed, validated and manufactured in sufficient quantities.The ability to triage patients at the point of care and support the guidance of medical and therapeutic decisions, for viral isolation or confirmatory testing or for appropriate treatment of COVID-19 and/or bacterial infections, is a critical component to our national pandemic response and there is an urgent need to implement the proposed strategy to combat the current outbreak.

Effects of remifentanil preconditioning on factors related to uterine contraction in WISH cells

Background

Preterm labor and miscarriage may occur in stressful situations, such as a surgical operation or infection during pregnancy. Pharyngeal and buccal abscess and facial bone fractures are inevitable dental surgeries in pregnant patients. Remifentanil is an opioid analgesic that is commonly used for general anesthesia and sedation. Nonetheless, no study has investigated the effects of remifentanil on amniotic epithelial cells. This study evaluated the effects of remifentanil on the factors related to uterine contraction and its mechanism of action on amniotic epithelial cells.

Methods

Amniotic epithelial cells were preconditioned at various concentrations of remifentanil for 1 h, followed by 24-h lipopolysaccharide (LPS) exposure. MTT assays were performed to assess the cell viability in each group. The effects of remifentanil on factors related to uterine contractions in amniotic epithelial cells were assessed using a nitric oxide (NO) assay, western blot examinations of the expression of nuclear factor-kappa B (NF-κB), cyclooxygenase 2 (COX2), and prostaglandin E2 (PGE₂), and RT-PCR examinations of the expression of the proinflammatory cytokines interleukin (IL)-1β and tumor necrosis factor-alpha (TNF-α).

Results

Remifentanil did not affect viability and nitric oxide production of amniotic epithelial cells. Western blot analysis revealed that remifentanil preconditioning resulted in decreased expressions of NF-κB and PGE₂ in the cells in LPS-induced inflammation, and a tendency of decreased COX2 expression. The results were statistically significant only at high concentration. RT-PCR revealed reduced expressions of IL-1β and TNF-α.

Conclusions

Preconditioning with remifentanil does not affect the viability of amniotic epithelial cells but reduces the expression of factors related to uterine contractions in situations where cell inflammation is induced by LPS, which is an important inducer of preterm labor. These findings provide evidence that remifentanil may inhibit preterm labor in clinical settings.

Molecular interactions between Neisseria meningitidis and its human host

Neisseria meningitidis is a Gram‐negative bacterium that asymptomatically colonises the nasopharynx of humans. For an unknown reason, N. meningitidis can cross the nasopharyngeal barrier and invade the bloodstream where it becomes one of the most harmful extracellular bacterial pathogen. This infectious cycle involves the colonisation of two different environments. (a) In the nasopharynx, N. meningitidis grow on the top of mucus‐producing epithelial cells surrounded by a complex microbiota. To survive and grow in this challenging environment, the meningococcus expresses specific virulence factors such as polymorphic toxins and MDAΦ. (b) Meningococci have the ability to survive in the extra cellular fluids including blood and cerebrospinal fluid. The interaction of N. meningitidis with human endothelial cells leads to the formation of typical microcolonies that extend overtime and promote vascular injury, disseminated intravascular coagulation, and acute inflammation. In this review, we will focus on the interplay between N. meningitidis and these two different niches at the cellular and molecular level and discuss the use of inhibitors of piliation as a potent therapeutic approach.

Inner sensors of endotoxin - implications for sepsis research and therapy

Despite great efforts and numerous clinical trials, there is still a major need for effective therapies for sepsis. Neutralization or elimination of bacterial toxins remains a promising approach. The understanding of the interaction of the endotoxin (lipopolysaccharide, LPS) of Gram-negative bacteria with its cellular receptor, namely the CD14/TLR4/MD2 complex, was a major breakthrough. Unfortunately, clinical trials for sepsis on the neutralization of LPS or on the inhibition of TLR4 signaling failed whereas those on LPS removal remain controversial. Recent discoveries of another class of LPS receptors localized within the cytoplasm, namely caspase-11 in mice and caspases-4/5 in humans, have renewed interest in the field. These provide new potential targets for intervention in sepsis pathogenesis. Since cytoplasmic recognition of LPS induces non-canonical inflammasome pathway, a potentially harmful host response, it is conceivable to therapeutically target this mechanism. However, a great deal of care should be used in the translation of research on the non-canonical inflammasome inhibition due to multiple inter-species differences. In this review, we summarize the knowledge on endotoxin sensing in sepsis with special focus on the intracellular sensing. We also highlight the murine versus human differences and discuss potential therapeutic approaches addressing the newly discovered pathways.

Targeting Type IV pili as an antivirulence strategy against invasive meningococcal disease

Bacterial virulence factors are attractive targets for the development of therapeutics. Type IV pili, which are associated with a remarkable array of properties including motility, the interaction between bacteria and attachment to biotic and abiotic surfaces, represent particularly appealing virulence factor targets. Type IV pili are present in numerous bacterial species and are critical for their pathogenesis. In this study, we report that trifluoperazine and related phenothiazines block functions associated with Type IV pili in different bacterial pathogens, by affecting piliation within minutes. Using Neisseria meningitidis as a paradigm of Gram-negative bacterial pathogens that require Type IV pili for pathogenesis, we show that piliation is sensitive to altered activity of the Na⁺ pumping NADH-ubiquinone oxidoreductase (Na⁺-NQR) complex and that these compounds probably altered the establishment of the sodium gradient. In vivo, these compounds exert a strong protective effect. They reduce meningococcal colonization of the human vessels and prevent subsequent vascular dysfunctions, intravascular coagulation and overwhelming inflammation, the hallmarks of invasive meningococcal infections. Finally, they reduce lethality. This work provides a proof of concept that compounds with activity against bacterial Type IV pili could beneficially participate in the treatment of infections caused by Type IV pilus-expressing bacteria.

Epac activation inhibits IL-6-induced cardiac myocyte dysfunction

Pro-inflammatory cytokines are released in septic shock and impair cardiac function via the Jak-STAT pathway. It is well known that sympathetic and thus catecholamine signaling is activated thereafter to compensate for cardiac dysfunction. The mechanism of such compensation by catecholamine signaling has been traditionally understood to be cyclic AMP-dependent protein kinase (PKA)-mediated enforcement of cardiac contractility. We hypothesized that the exchange protein activated by cAMP (Epac), a newly identified target of cAMP signaling that functions independently of PKA, also plays a key role in this mechanism. In cultured cardiac myocytes, activation of Epac attenuated the inhibitory effect of interleukin-6 on the increase of intracellular Ca2+ concentration and contractility in response to isoproterenol, most likely through inhibition of the Jak-STAT pathway via SOCS3, with subsequent changes in inducible nitric oxide synthase expression. These findings suggest a new role of catecholamine signaling in compensating for cardiac dysfunction in heart failure. Epac and its downstream pathway may be a novel target for treating cardiac dysfunction in endotoxemia.

Attenuation of Pseudomonas aeruginosa quorum sensing, virulence and biofilm formation by extracts of Andrographis paniculata

Quorum-sensing (QS) is known to play an essential role in regulation of virulence factors and toxins during Pseudomonas aeruginosa infection which may frequently cause antibiotic resistance and hostile outcomes of inflammatory injury. Therefore, it is an urgent need to search for a novel agent with low risk of resistance development that can target QS and inflammatory damage prevention as well. Andrographis paniculata, a herbaceous plant under the family Acanthaceae, native to Asian countries and also cultivated in Scandinavia and some parts of Europe, has a strong traditional usage with its known antibacterial, anti-inflammatory, antipyretic, antiviral and antioxidant properties. In this study, three different solvent extracts (viz., chloroform, methanol and aqueous) of A. paniculata were examined for their anti-QS and anti-inflammatory activities. Study was carried out to assess the effect on some selected QS-regulatory genes at transcriptional level using Real Time-PCR. In addition, ability to attenuate MAPK pathways upon P. aeruginosa infection was performed to check its potential anti-inflammatory activity. Chloroform and methanol extracts showed significant reduction (p < 0.05) of the QS-controlled extracellular virulence factors in P. aeruginosa including the expression of pyocyanin, elastase, total protease, rhamnolipid and hemolysin without affecting bacterial viability. They also significantly (p < 0.05) reduced swarming motility and biofilm formation of P. aeruginosa. The chloroform extract, which was found to be more effective, decreased expression of lasI, lasR, rhlI and rhlR by 61%, 75%, 41%, and 44%, respectively. Moreover, chloroform extract decreased activation of p-p38 and p-ERK1/2 expression levels in MAPK signal pathways in P. aeruginosa infected macrophage cells. As the present study demonstrates that A. paniculata extracts inhibit QS in P. aeruginosa and exhibit anti-inflammatory activities, therefore it represents itself as a prospective therapeutic agent against P. aeruginosa infection.

Hepatocyte SHP-1 is a Critical Modulator of Inflammation During Endotoxemia

Liver hepatocytes (Hep) are known to be central players during the inflammatory response to systemic infection. Interestingly, the protein tyrosine phosphatases (PTP) SHP-1, has been recognized as a major regulator of inflammation; however their implication in the control of Hep-mediated inflammatory response is still unknown. To study its implication in the regulation of the Hep-mediated inflammatory response during endotoxemia, Cre-Lox mice with a Hep-specific Ptpn6 deletion (Ptpn6^H-KO) were injected with LPS. In contrast to the wild-type mice (Ptpn6^f/f) that started to die by 24 hrs post-inoculation, the Ptpn6^H-KO mice exhibited mortality by 6 hrs. In parallel, higher amounts of metabolic markers, pro-inflammatory mediators and circulating cytokines were detected in Ptpn6^H-KO mice. Primary Hep obtained from Ptpn6^H-KO, also showed increased secretion of pro-inflammatory cytokines and nitric oxide (NO) comparatively to its wild type (Ptpn6^f/f) counterpart. Pharmacological approaches to block TNF-α and NO production protected both the Ptpn6^f/f and the Ptpn6^H-KO mice against deadly LPS-mediated endotoxemia. Collectively, these results establish hepatocyte SHP-1 is a critical player regulating systemic inflammation. Our findings further suggest that SHP-1 activation could represent a new therapeutic avenue to better control inflammatory-related pathologies.

The role of macrophages in hypertension and its complications

Circulating monocytes and tissue macrophages play complex roles in the pathogenesis of hypertension, a highly prevalent disease associated with catastrophic cardiovascular morbidity. In the vasculature and kidney, macrophage-derived reactive oxygen species (ROS) and inflammatory cytokines induce endothelial and epithelial dysfunction, respectively, resulting in vascular oxidative stress and impairment of sodium excretion. By contrast, VEGF-C-expressing macrophages in the skin can facilitate the removal of excess interstitial stores of sodium by stimulating lymphangiogenesis. Inappropriate activation of the renin-angiotensin system (RAS) contributes to essential hypertension in a majority of patients, and macrophages express the type 1 (AT₁) receptor for angiotensin II (Ang II). While proinflammatory macrophages clearly contribute to RAS-dependent hypertension, activation of the AT₁ receptor directly on macrophages suppresses their M1 polarization and limits tubular and interstitial damage to the kidney during hypertension. Thus, stimulating the macrophage AT₁ receptor ameliorates the target organ damage and immune stimulation provoked by AT₁ receptor activation in intrinsic renal and vascular cells. The proinflammatory cytokines TNF-α and IL-1β produced by M1 macrophages drive blood pressure elevation and consequent target organ damage. However, additional studies are needed to identify the tissues in which these cytokines act and the signaling pathways they stimulate during hypertension. Moreover, identifying the precise myeloid cell subsets that contribute to hypertension should guide the development of more precise immunomodulatory therapies for patients with persistent blood pressure elevation and progressive end-organ injury.

Pyroptosis of Salmonella Typhimurium-infected macrophages was suppressed and elimination of intracellular bacteria from macrophages was promoted by blocking QseC

QseC is a membrane-bound histidine sensor kinase found in Gram-negative pathogens and is involved in the regulation of bacterial virulence. LED209, a QseC-specific inhibitor, significantly inhibits the virulence of several pathogens and partially protects infected mice from death by blocking QseC. However, the mechanism of its antibacterial effects remains unclear. In this experiment, a Salmonella Typhimurium (S. Typhimurium) and macrophage co-culture system was utilized to investigate possible mechanisms underlying the antimicrobial effects of the QseC inhibitor. QseC blockade inhibited the expression of QseC-dependent virulence genes, including flhDC, sifA, and sopB, in S. Typhimurium, leading to inhibition of swimming motility, invasion capacity, and replication capacity of the pathogens. Release of lactate dehydrogenase (LDH) from S. Typhimurium-infected macrophages was significantly inhibited by blocking QseC. Activated caspase-1 and IL-1β levels were suppressed, and intracellular bacterial count was reduced in infected macrophages. QseC blockade effectively reduced the virulence of S. Typhimurium, inhibited S. Typhimurium-induced pyroptosis of macrophages, and promoted elimination of intracellular bacteria from infected macrophages. Thus, the antibacterial effects of QseC inhibitor are mediated via enhancement of intracellular killing of S. Typhimurium in macrophages.

Effects of bactericidal/permeability-increasing protein on endotoxin-induced fever and Escherichia coli-induced shock in rabbits

Binding of bactericidal/permeability-increasing protein (BPI) to endotoxin inhibits endotoxin-triggered responses. We investigated the effects of BPI on endotoxin fever and E. coli-induced septic shock in rabbits. Pre-incubation of endotoxin with BPI blocked fever compared to control rabbits (n = 6). A marked reduction in fever was also observed when BPI was injected before endotoxin. E. coli-challenge resulted in 66% mortality (n = 6); pre-treatment with BPI resulted in survival of all animals (n = 3). Mean arterial blood pressure was higher in BPI-treated compared to control rabbits. Comparable leukopenia and thrombocytopenia was observed with either BPI or vehicle treatment. Tumor necrosis factor (TNF) and interleukin-1 receptor antagonist were similarly elevated in both BPI- and saline-treated rabbits. However, in BPI treated rabbits, peak TNF levels were 34 % lower compared to saline controls ( P < 0.05). Further studies are warranted to assess whether BPI may have therapeutic potential for the treatment of septic shock.

Differential susceptibility of rhesus monkeys to high doses of endotoxin

We investigated susceptibility of rhesus monkeys ( Macaca mulatta) to Escherichia coli endotoxin (ETX) in two ways. We infused 8 monkeys (group A) with various doses of ETX (1.0-7.5 mg/kg) to assess the effect of dose on shock severity; and we infused 6 monkeys (group B) with 1.0 mg ETX/kg to test biological variability to ETX challenge. Controls were 7 saline-infused monkeys. Systolic pressure, heart rate (HR), temperature, plasma ETX and inflammatory markers — tumor necrosis factor-α (TNF), interleukin-1 (IL-1) and IL-6 — were quantified before and at 1.5, 2.5, 6 and 26 h after infusion. The highest plasma concentrations of ETX (at 1.5 h) — < 8% that infused — correlated well with the infused doses. ETX elicited hypotension and increases in HR in all monkeys. Fever did not occur. The degree of hypotension and increase in HR and death did not correlate with ETX dose (or plasma ETX concentrations). The response of inflammatory cytokines to ETX was greater in nonsurvivors than in survivors. The observed low mortality rate (4/14) suggests that rhesus monkeys are rather resistant to high endotoxin concentrations similar to baboons but unlike humans or chimpanzees. The lack of correlation between ETX dose and shock severity suggests that there is a critical ETX concentration in each animal that leads to controllable or uncontrollable cytokine elevation in plasma, with reversible or irreversible shock, and resulting survival or death.

Invited review: Neisseria meningitidis lipopolysaccharides in human pathology

Neisseria meningitidis causes meningitis, fulminant septicemia or mild meningococcemia attacking mainly children and young adults. Lipopolysaccharides (LPS) consist of a symmetrical hexa-acyl lipid A and a short oligosaccharide chain and are classified in 11 immunotypes. Lipid A is the primary toxic component of N. meningitidis . LPS levels in plasma and cerebrospinal fluid as determined by Limulus amebocyte lysate (LAL) assay are quantitatively closely associated with inflammatory mediators, clinical symptoms, and outcome. Patients with persistent septic shock, multiple organ failure, and severe coagulopathy reveal extraordinarily high levels of LPS in plasma. The cytokine production is compartmentalized to either the circulation or to the subarachnoid space. Mortality related to shock increases from 0% to > 80% with a 10-fold increase of plasma LPS from 10 to 100 endotoxin units/ml. Hemorrhagic skin lesions and thrombosis are caused by up-regulation of tissue factor which induces coagulation, and by inhibition of fibrinolysis by plasminogen activator inhibitor 1 (PAI-1). Effective antibiotic treatment results in a rapid decline of plasma LPS (half-life 1—3 h) and cytokines, and reduced generation of thrombin, and PAI-1. Early antibiotic treatment is mandatory. Three intervention trials to block lipid A have not significantly reduced the mortality of meningococcal septicemia.

Continuous cardiac output and hemodynamic monitoring: high temporal correlation between plasma TNF-α and hemodynamic changes during a sepsis-like state in cancer immunotherapy

Through continuous cardiac output monitoring, we investigated the temporal relationship between hemodynamic changes and plasma cytokines in a cancer patient who developed collateral sepsis to immunotherapy. A 52-year-old male with metastatic renal cell carcinoma received interleukin-2 (IL-2) infusion completing 72 h of administration. The patient developed 3 sepsis-like states including systemic inflammatory response syndrome (SIRS), shock, and multiple organ dysfunction syndrome (MODS). Hemodynamic parameters including systemic vascular resistance index (SVRI), left ventricular stroke work index (LVSWI) and cardiac index (CI) were measured over 60 h. Peripheral blood was drawn when SVRI dropped 20% in the patient and plasma cytokines including TNF-α , IL-6 and IL-1β were measured using ELISA. After 60 h of immunotherapy, the patient showed a 63.4% decrease in SVRI, 54.5% decrease in LVSWI and 65.4% increase in CI. The evaluation of systemic cytokines revealed different kinetic patterns: (i) a sustained increase in TNFα levels through all 3 sepsis-like states; (ii) IL-6 increased preferentially during SIRS and shock, while up/down-responses were found during MODS; (iii) IL-1β was undetectable during the entire study period. A high temporal relationship between hemodynamic changes and plasma TNF-α, but not IL-6, was found. Although there are factors other than cytokines that can alter vascular resistance, this finding could represent an approach to evaluate the course of hemodynamia and probably the systemic cytokine expression after IL-2 administration in renal cancer.

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Endotoxin is considered to be a systemic (immunological) stressor eliciting a prolonged activation of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA-axis response after an endotoxin challenge is mainly due to released cytokines (IL-1, IL-6 and TNF-α) from stimulated peripheral immune cells, which in turn stimulate different levels of the HPA axis. Controversy exists regarding the main locus of action of endotoxin on glucocorticoid secretion, since the effect of endotoxin on this neuro-endocrine axis has been observed in intact animals and after ablation of the hypothalamus; however, a lack of LPS effect has been described at both pituitary and adrenocortical levels. The resulting increase in adrenal glucocorticoids has well-documented inhibitory effects on the inflammatory process and on inflammatory cytokine release. Therefore, immune activation of the adrenal gland by endotoxin is thought to occur by cytokine stimulation of corticosteroid-releasing hormone (CRH) production in the median eminence of the hypothalamus, which, in turn stimulates the secretion of ACTH from the pituitary. Acute administration of endotoxin stimulates ACTH and cortisol secretion and the release of CRH and vasopressin (AVP) in the hypophysial portal blood. During repeated endotoxemia, tolerance of both immune and HPA function develops, with a crucial role for glucocorticoids in the modulation of the HPA axis. A single exposure to a high dose of LPS can induce a long-lasting state of tolerance to a second exposure of LPS, affecting the response of plasma TNF-α and HPA hormones. Although there are gender differences in the HPA response to endotoxin and IL-1, these responses are enhanced by castration and attenuated by androgen and estrogen replacement. Estrogens attenuate the endotoxin-induced stimulation of IL-6, TNF-α and IL-1ra release and subsequent activation in postmenopausal women. There appears to be a temporal and functional relation between the HPA-axis response to endotoxin and nitric oxide formation in the neuro-endocrine hypothalamus, suggesting a stimulatory role for nitric oxide in modulating the HPA response to immune challenges.

Hyaluronan accumulates around portal vessels in liver after endotoxin treatment of rats

Livers of normal rats and rats treated with lipopolysaccharide from Escherichia coli were isolated in situ and tested for capability to extract [3H]-hyaluronan. In control livers, excess unlabeled hyaluronan inhibited extraction of [3H]-hyaluronan both at 4°C and 37°C. Furthermore, part of the [3H]-hyaluronan extracted at 4°C could be released by subsequent perfusion with excess of unlabeled hyaluronan. This behaviour is in accordance with the well-characterized receptor-mediated uptake of hyaluronan in sinusoidal endothelial cells. However, in lipopolysaccharide-treated animals, the uptake of [3H]-hyaluronan was not inhibited by unlabelled polysaccharide, nor could [3H]-hyaluronan bound at 4°C be released from its binding sites. Both types of livers were perfused with 10 μg/ml of hyaluronan and recovered for histology. An accumulation of hyaluronan in areas around portal veins was found in endotoxin treated rats, while only traces of hyaluronan could be visualized in the vessels of normal livers. The location of hyaluronan coincided with cell infiltrates. Thus, there is a different mechanism for liver clearance of hyaluronan in the endotoxic animal.

Targeting cytokine signaling in salt-sensitive hypertension

Activated immune cell populations contribute to hypertension in part through inciting damage to the kidney and by provoking inappropriate sodium reabsorption in the nephron. Inflammatory mediators called cytokines produced by T lymphocytes and macrophages act on specific sodium transporters in the kidney, augmenting their activity or expression, with consequent expansion of intravascular fluid volume and cardiac output. The overlapping functions of these cytokines, each of which may activate multiple receptors, present challenges in precisely targeting inflammatory signaling cascades in hypertension. Moreover, broad immune suppression could expose the hypertensive patient to disproportional risks of infection or malignancy. Nevertheless, the possibility that incisive immunomodulatory therapies could provide cardiovascular and renal protection through both blood pressure-dependent and -independent mechanisms justifies comprehensive investigation into the relevant signaling pathways and tissue sites in which inflammatory cytokines function to exaggerate blood pressure elevation and target organ damage in hypertension.

Does rosmarinic acid treatment have protective role against sepsis-induced oxidative damage in Wistar Albino rats?

Reactive oxygen species are believed to be involved in the development of sepsis. Plant-derived phenolic compounds are thought to be possible therapeutic agents against sepsis because of their antioxidant properties. Rosmarinic acid (RA) is a phenolic compound commonly found in various plants, which has many biological activities including antioxidant activity. The aim of this study was to investigate the effects of RA on sepsis-induced DNA damage in the lymphocytes and liver and kidney cells of Wistar albino rats by alkaline comet assay with and without formamidopyrimidine DNA glycosylase protein. The oxidative stress parameters such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and total glutathione (GSH) and malondialdehyde (MDA) levels in the liver and kidney tissues and an inflammatory cytokine, tumor necrosis factor α (TNF-α) level in plasma were also evaluated. It is found that DNA damage in the lymphocytes, livers, and kidneys of the RA-treated rats was significantly lower than that in the sepsis-induced rats. RA treatment also decreased the MDA levels and increased the GSH levels and SOD and GSH-Px activities in the livers and kidneys of the sepsis-induced rats. Plasma TNF-α level was found to be decreased in the RA-treated rats. It seems that RA might have a role in the attenuation of sepsis-induced oxidative damage not only by decreasing the DNA damage but also by increasing the antioxidant status and DNA repair capacity of the animals.

Neutrophil-Related Inflammatory Mediators in Septic Acute Respiratory Distress Syndrome

To disclose the participation of neutrophils in septic acute respiratory distress syndrome (ARDS), characteristics of various inflammatory mediators were examined in septic patients. Forty-seven gram-negative septic patients were divided into ARDS (n = 23) and non-ARDS (n = 24) groups at the transferred point to the intensive care unit. The mediators were measured simultaneously at the transferred point, and then subsequently on days 1, 3, and 5. At the transferred point, the ARDS group showed significantly higher levels of interleukin-8 (IL-8), macrophage inflammatory peptide-1-alpha (MIP-1-α), soluble intercellular adhesion molecule-1 (sICAM-1), and neutrophil elas-tase despite lower neutrophil counts compared to the non-ARDS group. The ARDS group sustained significantly higher levels of sICAM-1 until day 5 and neutrophil elas-tase until day 1 compare to the non-ARDS group. Furthermore, nonsurviving ARDS patients (n = 8) showed significantly higher levels of tumor necrosis factor-alpha, IL-6, IL-8, and IL-10 compared to surviving ARDS patients (n = 15) at the transferred point. In conclusion, neutrophil-related inflammatory mediators, IL-8, MIP-1-α, sICAM-1, and neutrophil elastase, appear to possibly participate in septic ARDS. Cytokines might also play an important role in the mortality of such cases.

Multiple System Organ Failure in the Adult Respiratory Distress Syndrome

Recently completed studies suggest that patients with the adult respiratory distress syndrome (ARDS) manifest early evidence of multiple-site endothelial injury. Ex trapulmonary disease is usually the cause of death in these patients. Furthermore, prognosis in individual cases of ARDS is strongly influenced by specific organ failures (e.g., hepatic and renal failure). The mechanisms by which ARDS and extrapulmonary organ system fail ure interact, however, are poorly delineated. We ad dress three aspects of the multisystemic nature of ARDS. First, we analyze evidence that suggests ARDS is a mul tisystem disorder fron the outset, involving panendothe lial injury mediated by cellular interactions and humoral substances that act similarly at many vascular target sites. Second, we discuss the role of three extrapulmo nary organs in the modulation of ARDS: the liver, the gastrointestinal mucosa, and the kidneys. Third, we ad dress the unifying hypothesis that uncontrolled ongoing inflammation, which is often but not always caused by infection, is the essential link between ARDS and its progression to multiple system organ failure.

Subchronic Toxicity of Thalidomide in Rodents After 13 Weeks of Oral Administration

The subchronic toxicology of thalidomide was determined in CD-1 mice and F344 rats. Animals (10/sex/dose) were orally dosed at 30,300, and 3000 mg/kg/day over 13 weeks. Control animals were given 1% carboxymethylcellulose. No thalidomide-related mortality occurred throughout the study. Some species and sex differences were seen. In mice, thalidomide had no effect on body weight, food consumption, ophthalmic function or clinical chemistry/hematology, but a dose-dependent orange-pink urine was observed in both sexes. The discoloration was probably due to chromogenic breakdown products of thalidomide. The only significant finding in the mouse study was dose-related hepatic centrilobular hypertrophy in the males. This appeared only at the highest dose in the females. The hypertrophy was correlated with increased liver weight for the high dose of both sexes suggesting enzyme induction. In rats, thalidomide produced lower body weights in both sexes compared to control with a dose-response more evident in males. Male rats dosed at 30, 300, and 3000 mg/kg had body weights that were 8, 11, and 19% below control weight just before necropsy. Corresponding female rats were only 6–7% below control weights at all dose levels. Lower food consumption was observed in male rats and varied between 6–13% below control with no dose-response. Decreased forelimb strength was noted in males and could be due to the lower body weights. Functional observational battery tests and histopathology of the sural nerve and lumbar spinal cord sections suggested that the rat did not develop thalidomide-induced peripheral neuropathy. Mild anemia and leukopenia were seen only in some treated males. A decrease in total and free T4 was more consistent in females. Both sexes had lower thymus weights with no histological correlate compared to control. The no-observed-adverse-effect level for mice and female rats were 3000 mg/kg and 30 mg/kg for male rats.

Evaluation of mRNA Biomarkers to Identify Risk of Hospital Acquired Infections in Children Admitted to Paediatric Intensive Care Unit

Objectives

Hospital-acquired infections (HAI) are associated with significant mortality and morbidity and prolongation of hospital stay, adding strain on limited hospital resources. Despite stringent infection control practices some children remain at high risk of developing HAI. The development of biomarkers which could identify these patients would be useful. In this study our objective was to evaluate mRNA candidate biomarkers for HAI prediction in a pediatric intensive care unit.

Design

Serial blood samples were collected from patients admitted to pediatric intensive care unit between March and June 2012. Candidate gene expression (IL1B, TNF, IL10, CD3D, BCL2, BID) was quantified using RT-qPCR. Comparisons of relative gene expression between those that did not develop HAI versus those that did were performed using Mann Whitney U-test.

Patients

Exclusion criteria were: age <28 days or ≥16 years, expected length of stay < 24 hours, expected survival < 28 days, end-stage renal disease and end-stage liver disease. Finally, 45 children were included in this study.

Main Results

The overall HAI rate was 30% of which 62% were respiratory infections. Children who developed HAI had a three-fold increase in hospital stay compared to those who did not (27 days versus 9 days, p<0.001). An increased expression of cytokine genes (IL1B and IL10) was observed in patients who developed HAI, as well as a pro-apoptosis pattern (higher expression of BID and lower expression of BCL2). CD3D, a key TCR co-factor was also significantly down-modulated in patients who developed HAI.

Conclusions

To our knowledge, this is the first study of mRNA biomarkers of HAI in the paediatric population. Increased mRNA expressions of anti-inflammatory cytokine and modulation of apoptotic genes suggest the development of immunosuppression in critically ill children. Immune monitoring using a panel of genes may offer a novel stratification tool to identify HAI risk.

Baicalein attenuates the quorum sensing-controlled virulence factors of Pseudomonas aeruginosa and relieves the inflammatory response in P. aeruginosa-infected macrophages by downregulating the MAPK and NFκB signal-transduction pathways

Burgeoning antibiotic resistance and unfavorable outcomes of inflammatory injury after Pseudomonas aeruginosa infection have necessitated the development of novel agents that not only target quorum sensing (QS) but also combat inflammatory injury with the least risk of resistance. This study aimed to assess the anti-QS and anti-inflammatory activities of baicalein, a traditional herbal medicine that is widely used in the People’s Republic of China, against P. aeruginosa infection. We found that subminimum inhibitory concentrations of baicalein efficiently interfered with the QS-signaling pathway of P. aeruginosa via downregulation of the transcription of QS-regulated genes and the translation of QS-signaling molecules. This interference resulted in the global attenuation of QS-controlled virulence factors, such as motility and biofilm formation, and the secretion into the culture supernatant of extracellular virulence factors, including pyocyanin, LasA protease, LasB elastase, and rhamnolipids. Moreover, we examined the anti-inflammatory activity of baicalein and its mode of action via a P. aeruginosa-infected macrophage model to address its therapeutic effect. Baicalein reduced the P. aeruginosa-induced secretion of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNFα. In addition, baicalein suppressed P. aeruginosa-induced activation of the MAPK and NFκB signal-transduction pathways in cocultured macrophages; this may be the mechanism by which baicalein inhibits the production of proinflammatory cytokines. Therefore, our study demonstrates that baicalein represents a potential treatment for P. aeruginosa infection because it clearly exhibits both antibacterial and anti-inflammatory activities.

Evaluation of a combined MxA and CRP point-of-care immunoassay to identify viral and/or bacterial immune response in patients with acute febrile respiratory infection

Background

Challenges in the clinical differentiation of viral and/or bacterial respiratory infection lead to the misappropriation of antibiotics and increased healthcare costs. A tool to facilitate rapid and accurate point-of-care (POC) differentiation is needed.

Methods and findings

A prospective, single center, blinded, observational clinical trial was conducted at Beth Israel Deaconess Medical Center from December 2012 to August 2013 to determine the accuracy of a POC immunoassay to identify a clinically significant immune response to viral and/or bacterial infection. Sixty patients with acute febrile respiratory infection (19 pharyngitis and 41 lower respiratory tract infection [LRTI]) were enrolled. Participants provided fingerstick blood for immunoassay testing (myxovirus A [MxA] and c-reactive protein [CRP]) and four oropharyngeal samples for viral PCR and routine bacterial cell culture. A venous blood sample was collected. An ELISA was used to measure CRP and MxA. Paired serological testing was used to confirm atypical bacteria. A urine sample was provided for Streptococcus and Legionella antigen testing. Patients with suspected LRTI had sputum and blood cultures, chest X-ray, and WBC count measured. Viral infection was confirmed if oropharyngeal PCR was positive for viral pathogens. Bacterial infection was confirmed in positive throat or sputum cultures. Elevated immunoglobulin M antibodies or twofold increase in IgG antibodies between acute and convalescent phase indicated atypical bacteria. Positive Streptococcus or Legionella urine antigen assays also confirmed bacterial infection. The immunoassay correctly categorized subjects as 92% (22/24) negative, 80% (16/20) with bacterial infection, and 70% (7/10) with viral infection.

Conclusions

The interplay between an MxA value and a semi-quantitative CRP value can aid in the differentiation of infectious etiology. In isolation, neither MxA nor CRP alone is sensitive or specific. However, the pattern of results in a rapid immunoassay provides a sensitive and specific method to differentiate acute febrile respiratory infections. This diagnostic information may help reduce antibiotic misuse and resistance and lower healthcare costs.

Myocardial Dysfunction in Severe Sepsis and Septic Shock: No Correlation With Inflammatory Cytokines in Real-life Clinical Setting

BACKGROUND

In vitro studies suggested that circulating inflammatory cytokines cause septic myocardial dysfunction. However, no in vivo clinical study has investigated whether serum inflammatory cytokine concentrations correlate with septic myocardial dysfunction.

METHODS

Repeated echocardiograms and concurrent serum inflammatory cytokines (IL-1β, IL-6, IL-8, IL-10, IL-18, tumor necrosis factor-α, and monocyte chemoattractant protein-1) and cardiac biomarkers (high-sensitivity [hs] troponin-T and N-terminal pro-B-type natriuretic peptide [NT-proBNP]) were examined in 105 patients with severe sepsis and septic shock. Cytokines and biomarkers were tested for correlations with systolic and diastolic dysfunction, sepsis severity, and mortality.

RESULTS

Systolic dysfunction defined as reduced left ventricular ejection fraction (LVEF) < 50% or < 55% and diastolic dysfunction defined as e'-wave < 8 cm/s on tissue-Doppler imaging (TDI) or E/e'-ratio were found in 13 (12%), 24 (23%), 53 (50%), and 26 (25%) patients, respectively. Forty-four patients (42%) died in-hospital. All cytokines, except IL-1, correlated with Sequential Organ Failure Assessment and APACHE (Acute Physiology and Chronic Health Evaluation) II scores, and all cytokines predicted mortality. IL-10 and IL-18 independently predicted mortality among cytokines (OR = 3.1 and 28.3, P = .006 and < 0.0001). However, none of the cytokines correlated with LVEF, end-diastolic volume index (EDVI), stroke-volume index (SVI), or s'-wave and e'-wave velocities on TDI (Pearson linear and Spearman rank [ρ] nonlinear correlations). Similarly, no differences were found in cytokine concentrations between patients dichotomized to high vs low LVEF, EDVI, SVI, s'-wave, or e'-wave (Mann-Whitney U tests). In contrast, NT-proBNP strongly correlated with both reduced LVEF and reduced e'-wave velocity, and hs-troponin-T correlated mainly with reduced e'-wave.

CONCLUSIONS

Unlike cardiac biomarkers, none of the measured inflammatory cytokines correlates with systolic or diastolic myocardial dysfunction in severe sepsis or septic shock.

Host response biomarkers in the diagnosis of sepsis: a general overview

Critically ill patients who display a systemic inflammatory response syndrome (SIRS) are prone to develop nosocomial infections. The challenge remains to distinguish as early as possible among SIRS patients those who are developing sepsis. Following a sterile insult, damage-associated molecular patterns (DAMPs) released by damaged tissues and necrotic cells initiate an inflammatory response close to that observed during sepsis. During sepsis, pathogen-associated molecular patterns (PAMPs) trigger the release of host mediators involved in innate immunity and inflammation through identical receptors as DAMPs. In both clinical settings, a compensatory anti-inflammatory response syndrome (CARS) is concomitantly initiated. The exacerbated production of pro- or anti-inflammatory mediators allows their detection in biological fluids and particularly within the bloodstream. Some of these mediators can be used as biomarkers to decipher among the patients those who developed sepsis, and eventually they can be used as prognosis markers. In addition to plasma biomarkers, the analysis of some surface markers on circulating leukocytes or the study of mRNA and miRNA can be helpful. While there is no magic marker, a combination of few biomarkers might offer a high accuracy for diagnosis.

Saikosaponin A protects against experimental sepsis via inhibition of NOD2-mediated NF-κB activation

The excessive production of inflammatory cytokines during invasive infection primarily mediates the pathophysiology of sepsis. To improve the survival of septic patients, many selective or mediator-specific anti-inflammatory agents have been developed. Saikosaponin A (SsA), a triterpenoid saponin isolated from Radix Bupleuri, inhibits the production of proinflammatory mediators in several cell types and protects against CCl₄-induced liver injury in rats. However, whether SsA treatment provides protective effects against sepsis remains unknown. The aim of the present study was to investigate the anti-inflammatory role of SsA in septic rats and the possible involvement of the nucleotide-binding oligomerization domain 2 (NOD2)/NF-κB signaling pathway in the regulation of inflammatory cytokine expression. Sixty male Wistar rats were randomly divided into six groups (10 rats per group): Sham surgery, cecal ligation and puncture (CLP), CLP plus SsA (1.0 mg/kg), CLP plus SsA (2.5 mg/kg), CLP plus SsA (5.0 mg/kg) and sham surgery plus SsA (2.5 mg/kg) groups. Rats in the SsA groups were intraperitoneally (i.p.) injected with different doses of SsA following the CLP surgery. Tissues from the ileum were harvested 8 h after CLP or sham surgery and the levels of inflammatory cytokines and NOD2 mRNA, and the activation of NF-κB were measured. The concentrations of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6, as well as the NOD2 mRNA expression levels and NF-κB activation in the intestinal tissues were significantly increased in the septic rats of the CLP group compared with those in the sham group. SsA administration effectively suppressed the increase in the levels of TNF-α and IL-6. Moreover, the upregulation of NOD2 mRNA expression and phospho-NF-κB p65 levels was significantly inhibited following the administration of SsA. SsA may exert a protective role in the septic process by suppressing TNF-α and IL-6 concentrations in the intestines of septic rats and these effects appear to be mediated, at least partly, via inhibition of the NOD2/NF-κB signaling pathway.

Same species, different diseases: how and why typhoidal and non-typhoidal Salmonella enterica serovars differ

Human infections by the bacterial pathogen Salmonella enterica represent major disease burdens worldwide. This highly ubiquitous species consists of more than 2600 different serovars that can be divided into typhoidal and non-typhoidal Salmonella (NTS) serovars. Despite their genetic similarity, these two groups elicit very different diseases and distinct immune responses in humans. Comparative analyses of the genomes of multiple Salmonella serovars have begun to explain the basis of the variation in disease manifestations. Recent advances in modeling both enteric fever and intestinal gastroenteritis in mice will facilitate investigation into both the bacterial- and host-mediated mechanisms involved in salmonelloses. Understanding the genetic and molecular mechanisms responsible for differences in disease outcome will augment our understanding of Salmonella pathogenesis, host immunity, and the molecular basis of host specificity. This review outlines the differences in epidemiology, clinical manifestations, and the human immune response to typhoidal and NTS infections and summarizes the current thinking on why these differences might exist.

Novel RNA interference-based therapies for sepsis

INTRODUCTION

Sepsis is an extremely fast-paced disease, initiated by an infection that can progress to multiple organ dysfunction and death. The complexity associated with sepsis makes the therapies difficult to develop. Moreover, the 'one-fits-all' kind of therapy is far from being realistic.

AREAS COVERED

This review provides a conspectus of the current results of sepsis therapies and their benefits, focusing on the development of small interfering RNA (siRNA) therapeutics for targeting immune cells and sepsis pathways.

EXPERT OPINION

The question, 'When will an effective therapy for sepsis be available for patients?' remains unanswered. New RNA interference-mediated therapies are emerging as novel approaches for the treatment of sepsis by downregulating key inflammatory cytokine expression. Strategies that exploit multimodal gene silencing using siRNA and targeted delivery systems are discussed in this review. Some of these strategies have shown positive results in preclinical model of sepsis.

Immunotherapy for the adjunctive treatment of sepsis: from immunosuppression to immunostimulation. Time for a paradigm change?

Sepsis is the leading cause of death in the intensive care unit and ranks in the top 10 causes of death in general worldwide. Proinflammatory mediators are related to symptoms observed early in patients with sepsis, such as fever and hemodynamic instability. However, in recent years it has become clear that most septic patients do not die from an overwhelming proinflammatory immune response but in an immunosuppressive state, which can last for days or even weeks, and that results in increased susceptibility to secondary (opportunistic) infections. Although infection control and supportive therapies will remain the cornerstone of treatment, especially in the early phase of sepsis, the identification of this so-called "immunoparalysis" is currently causing a paradigm shift in the adjunctive treatment of sepsis from therapies that suppress the immune system toward immunostimulation. In this Critical Care Perspective we give an overview of the pathophysiology of sepsis, with a focus on immunosuppressive mechanisms that play an important role in outcome. In addition, we present an appraisal of the recent advances in immunotherapy as an adjunctive treatment for sepsis.

Effect of the PA-MSHA vaccine on septic serum-induced inflammatory response

Sepsis is defined as a complex clinical syndrome caused by a serious infection followed by an amplified and deregulated inflammatory response. The complex syndrome is associated with a high rate of morbidity and mortality, despite substantial clinical advances. A vaccine derived from the outer membrane proteins of the Gram-negative bacteria Pseudomonas aeruginosa (PA-MSHA) has been demonstrated to exhibit immune modulatory properties. In the present study, the effect of the PA-MSHA vaccine on the inflammatory response induced by serum from septic patients in peripheral blood mononuclear cells was determined. It was observed that PA-MSHA pretreatment inhibits the production of septic serum-induced tumor necrosis factor-α. In addition, PA-MSHA treatment increases interleukin-10 levels and promotes the generation of CD4+CD25+Foxp3+ T cells. Thus, the results of the current study provide mechanistic insight relevant to the potential application of PA-MSHA in the treatment of sepsis.

Adhesion of Neisseria meningitidis to dermal vessels leads to local vascular damage and purpura in a humanized mouse model

Septic shock caused by Neisseria meningitidis is typically rapidly evolving and often fatal despite antibiotic therapy. Further understanding of the mechanisms underlying the disease is necessary to reduce fatality rates. Postmortem samples from the characteristic purpuric rashes of the infection show bacterial aggregates in close association with microvessel endothelium but the species specificity of N. meningitidis has previously hindered the development of an in vivo model to study the role of adhesion on disease progression. Here we introduced human dermal microvessels into SCID/Beige mice by xenografting human skin. Bacteria injected intravenously exclusively associated with the human vessel endothelium in the skin graft. Infection was accompanied by a potent inflammatory response with the secretion of human inflammatory cytokines and recruitment of inflammatory cells. Importantly, infection also led to local vascular damage with hemostasis, thrombosis, vascular leakage and finally purpura in the grafted skin, replicating the clinical presentation for the first time in an animal model. The adhesive properties of the type IV pili of N. meningitidis were found to be the main mediator of association with the dermal microvessels in vivo. Bacterial mutants with altered type IV pili function also did not trigger inflammation or lead to vascular damage. This work demonstrates that local type IV pili mediated adhesion of N. meningitidis to the vascular wall, as opposed to circulating bacteria, determines vascular dysfunction in meningococcemia.