Differential expression of Toll-like receptor (TLR)-2 and TLR-4 on monocytes in human sepsis

Glucans: A Therapeutic Alternative for Sepsis Treatment

Sepsis treatment is a challenging condition due to its complexity, which involves host inflammatory responses to a severe and potentially fatal infection, associated with organ dysfunction. The aim of this study was to analyze the scientific literature on the immunomodulatory effects of glucans in a murine model of systemic infection induced by cecal ligation and puncture. This study comprises an integrative literature review based on systematic steps, with searches carried out in the PubMed, ScienceDirect, Scopus, Web of Science, and Embase databases. In most studies, the main type of glucan investigated was β-glucan, at 50 mg/kg, and a reduction of inflammatory responses was identified, minimizing the occurrence of tissue damage leading to increased animal survival. Based on the data obtained and discussed in this review, glucans represent a promising biotechnological alternative to modulate the immune response and could potentially be used in the clinical management of septic individuals.

Sex-related immunity: could Toll-like receptors be the answer in acute inflammatory response?

An increasing number of studies have highlighted the existence of a sex-specific immune response, wherein men experience a worse prognosis in cases of acute inflammatory diseases. Initially, this sex-dependent inflammatory response was attributed to the influence of sex hormones. However, a growing body of evidence has shifted the focus toward the influence of chromosomes rather than sex hormones in shaping these inflammatory sex disparities. Notably, certain pattern recognition receptors, such as Toll-like receptors (TLRs), and their associated immune pathways have been implicated in driving the sex-specific immune response. These receptors are encoded by genes located on the X chromosome. TLRs are pivotal components of the innate immune system, playing crucial roles in responding to infectious diseases, including bacterial and viral pathogens, as well as trauma-related conditions. Importantly, the TLR-mediated inflammatory responses, as indicated by the production of specific proteins and cytokines, exhibit discernible sex-dependent patterns. In this review, we delve into the subject of sex bias in TLR activation and explore its clinical implications relatively to both the X chromosome and the hormonal environment. The overarching objective is to enhance our understanding of the fundamental mechanisms underlying these sex differences.

CD14 down-modulation as a real-time biomarker in Kawasaki disease

Objectives

The objectives of this study were to investigate the pathophysiology of Kawasaki disease (KD) from immunological and oxidative stress perspectives, and to identify real-time biomarkers linked to innate immunity and oxidative stress in KD.

Methods

We prospectively enrolled 85 patients with KD and 135 patients with diverse conditions including immune, infectious and non-infectious diseases for this investigation. Flow cytometry was used to analyse the surface expression of CD14, CD38 and CD62L on monocytes, along with a quantitative assessment of CD14 down-modulation. Additionally, oxidative stress levels were evaluated using derivatives of reactive oxygen metabolites (d-ROMs) and antioxidant capacity measured by a free radical elective evaluator system.

Results

During the acute phase of KD, we observed a prominent CD14 down-modulation on monocytes, reflecting the indirect detection of circulating innate immune molecular patterns. Moreover, patients with KD showed a significantly higher CD14 down-modulation compared with infectious and non-infectious disease controls. Notably, the surface expression of CD14 on monocytes was restored concurrently with responses to intravenous immunoglobulin and infliximab treatment in KD. Furthermore, d-ROM levels in patients with KD were significantly elevated compared with patients with infectious and non-infectious diseases. Following intravenous immunoglobulin treatment, oxidative stress levels decreased in patients with KD.

Conclusion

Monitoring CD14 down-modulation on monocytes in real-time is a valuable strategy for assessing treatment response, distinguishing KD relapse from concomitant infections and selecting second-line therapy after IVIG treatment in KD patients. The interplay between inflammation and oxidative stress likely plays a crucial role in the development of KD.

Beyond Pattern Recognition: TLR2 Promotes Chemotaxis, Cell Adhesion, and Migration in THP-1 Cells

The interaction between monocytes and endothelial cells in inflammation is central to chemoattraction, adhesion, and transendothelial migration. Key players, such as selectins and their ligands, integrins, and other adhesion molecules, and their functions in these processes are well studied. Toll-like receptor 2 (TLR2), expressed in monocytes, is critical for sensing invading pathogens and initiating a rapid and effective immune response. However, the extended role of TLR2 in monocyte adhesion and migration has only been partially elucidated. To address this question, we performed several functional cell-based assays using monocyte-like wild type (WT), TLR2 knock-out (KO), and TLR2 knock-in (KI) THP-1 cells. We found that TLR2 promotes the faster and stronger adhesion of monocytes to the endothelium and a more intense endothelial barrier disruption after endothelial activation. In addition, we performed quantitative mass spectrometry, STRING protein analysis, and RT-qPCR, which not only revealed the association of TLR2 with specific integrins but also uncovered novel proteins affected by TLR2. In conclusion, we show that unstimulated TLR2 influences cell adhesion, endothelial barrier disruption, migration, and actin polymerization.

New Frontiers in Sepsis-Induced Acute Kidney Injury and Blood Purification Therapies: The Role of Polymethylmethacrylate Membrane Hemofilter

Acute kidney injury (AKI) is a common consequence of sepsis with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex and involves several mechanisms leading to exacerbated inflammatory response associated with renal injury. A large body of evidence suggests that inflammation is tightly linked to AKI through bidirectional interaction between renal and immune cells. Preclinical data from our and other laboratories have identified in complement system activation a crucial mediator of AKI. Partial recovery following AKI could lead to long-term consequences that predispose to chronic dysfunction and may also accelerate the progression of preexisting chronic kidney disease. Recent findings have revealed striking morphological and functional changes in renal parenchymal cells induced by mitochondrial dysfunction, cell cycle arrest via the activation of signaling pathways involved in aging process, microvascular rarefaction, and early fibrosis. Although major advances have been made in our understanding of the pathophysiology of AKI, there are no available preventive and therapeutic strategies in this field. The identification of ideal clinical biomarkers for AKI enables prompt and effective therapeutic strategy that could prevent the progression of renal injury and promote repair process. Therefore, the use of novel biomarkers associated with clinical and functional criteria could provide early interventions and better outcome. Several new drugs for AKI are currently being investigated; however, the complexity of this disease might explain the failure of pharmacological intervention targeting just one of the many systems involved. The hypothesis that blood purification could improve the outcome of septic AKI has attracted much attention. New relevant findings on the role of polymethylmethacrylate-based continuous veno-venous hemofiltration in septic AKI have been reported. Herein, we provide a comprehensive literature review on advances in the pathophysiology of septic AKI and potential therapeutic approaches in this field.

Signal-Strength and History-Dependent Innate Immune Memory Dynamics in Health and Disease

Innate immunity exhibits memory characteristics, reflected not only in selective recognition of external microbial or internal damage signals, but more importantly in history and signal-strength dependent reprogramming of innate leukocytes characterized by priming, tolerance, and exhaustion. Key innate immune cells such as monocytes and neutrophils can finely discern and attune to the duration and intensity of external signals through rewiring of internal signaling circuitries, giving rise to a vast array of discreet memory phenotypes critically relevant to managing tissue homeostasis as well as diverse repertoires of inflammatory conditions. This review will highlight recent advances in this rapidly expanding field of innate immune programming and memory, as well as its translational implication in the pathophysiology of selected inflammatory diseases.

Gene duplication and adaptive evolution of Toll-like receptor genes in birds

Toll-like receptors (TLRs) play an important role in innate immune through recognizes pathogens. In order to reveal the evolutionary patterns and adaptive evolution of avian TLRs, we examined 66 representative bird species in 26 orders. Phylogenetic results indicated that TLR1A and TLR1B may have differentiated functionally. Evolutionary analysis showed that the TLR genes in birds under strong Purification selection (0.165-0.4265). A total of 126 common positively selected codons were identified in 10 TLR genes of avian, and most sites were located in the extracellular leucine-rich repeat (LRR) functional domains, and both environment and feeding habits were external factors driving the evolution of avian TLR genes. Environmental pressures had a greater effect on TLR1B, TLR2B, TLR3 and TLR4, while feeding habits were active in affecting TLR2A, TLR2B, TLR15 and TLR21. Our data suggested that TLR genes have been subjected to different selective pressures in the diversification of birds and that these changes enabled them to respond differently to pathogens from diverse sources.

Toll-like receptor 2 and 9 expression on circulating neutrophils is associated with increased mortality in critically ill patients

BACKGROUND

Toll-like receptors (TLRs) play an important role in inflammatory processes in critically ill patients by binding to pathogen-associated molecular patterns and danger-associated molecular patterns (DAMPs). Whether neutrophil or monocyte TLR expression patterns are associated with outcome in critical illness is unknown.

OBJECTIVES

To answer this question, we conducted a prospective, observational study including 215 consecutive patients admitted to a medical ICU at a tertiary care center.

METHODS

Blood was drawn at admission and expression of TLR-2, TLR-4, and TLR-9 on neutrophils and monocytes were analyzed by flow cytometry.

RESULTS

Median Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 19, and 30-day mortality was 26%. TLR-2 expression on neutrophils was associated with APACHE II, Simplified Acute Physiology Score II, and Sepsis-related Organ Failure Assessment score. TLR-2 (P < 0.001) and TLR-9 (P < 0.05) expression on neutrophils was significantly higher in nonsurvivors. In contrast, neutrophil TLR-4 expression and monocyte TLR expression were not associated with survival. Neutrophil TLR-2 (odds ratio 3.8; 95% confidence interval 1.4-10.2; P < 0.05) and TLR-9 (odds ratio 4.0; 95% confidence interval 2.0-8.1; P < 0.001) expression in the third tertile predicted mortality independent from APACHE II, serum lactate, serum creatinine, and procalcitonin, respectively.

CONCLUSION

We provide evidence for prognostic properties of neutrophil TLR-2 and TLR-9 expression regarding 30-day mortality in unselected critically ill patients, independent from baseline clinical characteristics, and laboratory values. These findings suggest that specific TLR-dependent activation of the innate immune system via neutrophils possibly caused by cell damage and release of otherwise intracellular components may play a significant role in the pathophysiology of critical illness.

Innate Receptor Activation Patterns Involving TLR and NLR Synergisms in COVID-19, ALI/ARDS and Sepsis Cytokine Storms: A Review and Model Making Novel Predictions and Therapeutic Suggestions

Severe COVID-19 is characterized by a “cytokine storm”, the mechanism of which is not yet understood. I propose that cytokine storms result from synergistic interactions among Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors (NLR) due to combined infections of SARS-CoV-2 with other microbes, mainly bacterial and fungal. This proposition is based on eight linked types of evidence and their logical connections. (1) Severe cases of COVID-19 differ from healthy controls and mild COVID-19 patients in exhibiting increased TLR4, TLR7, TLR9 and NLRP3 activity. (2) SARS-CoV-2 and related coronaviruses activate TLR3, TLR7, RIG1 and NLRP3. (3) SARS-CoV-2 cannot, therefore, account for the innate receptor activation pattern (IRAP) found in severe COVID-19 patients. (4) Severe COVID-19 also differs from its mild form in being characterized by bacterial and fungal infections. (5) Respiratory bacterial and fungal infections activate TLR2, TLR4, TLR9 and NLRP3. (6) A combination of SARS-CoV-2 with bacterial/fungal coinfections accounts for the IRAP found in severe COVID-19 and why it differs from mild cases. (7) Notably, TLR7 (viral) and TLR4 (bacterial/fungal) synergize, TLR9 and TLR4 (both bacterial/fungal) synergize and TLR2 and TLR4 (both bacterial/fungal) synergize with NLRP3 (viral and bacterial). (8) Thus, a SARS-CoV-2-bacterium/fungus coinfection produces synergistic innate activation, resulting in the hyperinflammation characteristic of a cytokine storm. Unique clinical, experimental and therapeutic predictions (such as why melatonin is effective in treating COVID-19) are discussed, and broader implications are outlined for understanding why other syndromes such as acute lung injury, acute respiratory distress syndrome and sepsis display varied cytokine storm symptoms.

Combination of Procalcitonin Value on Hospital Admission and Its Subsequent Change in Value Is Associated With the Prognosis of Sepsis

Supplemental Digital Content is available in the text.

To evaluate the relationship between the procalcitonin value in blood on hospital admission and its subsequent change and prognosis among sepsis patients.

Crude polysaccharide from the milky mushroom, Calocybe indica, modulates innate immunity of macrophage cells by triggering MyD88-dependent TLR4/NF-κB pathway

OBJECTIVES

Calocybe indica is a famous nutritious food in Asian countries and one of the most widely cultivated mushrooms in the world. Here, we have isolated crude polysaccharides from this mushroom, characterized it and investigated its antioxidant and immunostimulatory potential.

METHODS

The polysaccharide was chemically characterized by spectrophotometry, FTIR and high-performance thin layer chromatography and tested its antioxidant potential by in vitro assays. Immunomodulatory activity and its underlying signalling process were ascertained in RAW 264.7 cells.

KEY FINDINGS

The polysaccharide consisted of D-glucose (β-linked sugars), D-mannose and D-galactose, where backbone was organized in random coil structure. Preliminary investigation of the bioactivity of the polysaccharide revealed its antioxidant potential. The polysaccharide could noticeably induce phagocytic activity and production of immune mediators in macrophage cells. The polysaccharide was found to enhance the expression of pro-inflammatory cytokines and activate NF-κB signalling pathway by overexpressing MyD88, Iκ-Bα and NF-κB. Further studies indicated the polysaccharide binds to the toll-like receptor 4 to manifest its immunostimulatory activity in macrophage cells.

CONCLUSIONS

Our findings indicate potential therapeutic properties of the crude polysaccharide of C. indica which might provide the means to treat various radical induced and immunodeficiency disorders in the days to come.

Toll-like receptor 2 downregulation and cytokine dysregulation predict mortality in patients with Staphylococcus aureus bacteremia

BACKGROUND

Staphylococcus aureus bacteremia (SAB) presents heterogeneously, owing to the differences in underlying host conditions and immune responses. Although Toll-like receptor 2 (TLR2) is important in recognizing S. aureus, its function during S. aureus infection remains controversial. We aimed to examine the association of TLR2 expression and associated cytokine responses with clinical SAB outcomes.

METHODS

Patients from a prospective SAB cohort at two tertiary-care medical centers were enrolled. Blood was sampled at several timepoints (≤5 d, 6-9 d, 10-13 d, 14-19 d, and ≥ 20 d) after SAB onset. TLR2 mRNA levels were determined via real-time PCR and serum tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-10 levels were analyzed with multiplex-high-sensitivity electrochemiluminescent ELISA.

RESULTS

TLR2 levels varied among 59 SAB patients. On days 2-5, TLR2 levels were significantly higher in SAB survivors than in healthy controls (p = 0.040) and slightly but not significantly higher than non-survivors (p = 0.120), and SAB patients dying within 7 d had lower TLR2 levels than survivors (P = 0.077) although statistically insignificant. IL-6 and IL-10 levels were significantly higher in non-survivors than in survivors on days 2-5 post-bacteremia (P = 0.010 and P = 0.021, respectively), and those dying within 7 d of SAB (n = 3) displayed significantly higher IL-10/TNF-α ratios than the survivors did (P = 0.007).

CONCLUSION

TLR2 downregulation and IL-6 and IL-10 concentrations suggestive of immune dysregulation during early bacteremia may be associated with mortality from SAB. TLR2 expression levels and associated cytokine reactions during early-phase SAB may be potential prognostic factors in SAB, although larger studies are warranted.

TLR2 and TLR4 expressions in late-onset neonatal sepsis: Is it a potential novel biomarker?

BACKGROUND

Late-onset neonatal sepsis (LONS) detection is problematic as no single examinations (blood culture, c-reactive protein (CRP), procalcitonin (PCT)) are reliable. Toll-like receptors (TLRs), which detect the presence of pathogen-associated molecular patterns is a promising novel biomarker, but less studied in LONS. This study aimed to determine neutrophils and monocytes TLR2 and TLR4 expression in LONS and their diagnostic value.

METHODS

A cross-sectional study conducted in May and June 2017 involving 52 neonates with clinical late-onset (>72 hours of age) sepsis. We examine complete blood count, I/T ratio, CRP, PCT, as well as TLR2 and TLR4 expression to compared with blood culture as the gold standard. We classified cases into proven or unproven sepsis.

RESULT

The incidence of LONS was 32.6% in the subjects. The expression of TLR2 was low in LONS, while TLR4 was high. TLR4 neutrophil expression has 88.2% sensitivity, 20% specificity, 34.9% positive predictive value (PPV), 77.8% negative predictive value (NPV), and an AUC of 0.541. TLR4 monocyte expression has 92.1% sensitivity, 11.4% specificity, 34% PPV, 80% NPV, and an AUC of 0.528. The AUC of CRP is increased from 0.608 to 0.843 after combination with TLR4, comparable with CRP + PCT (AUC 0.829).

CONCLUSION

The increase in TLR4 expression has good sensitivity but low specificity. TLR4 expression, in combination with CRP, could become a reliable biomarker for the diagnosis of LONS.

TLR2 Dimerization Blockade Allows Generation of Homeostatic Intestinal Macrophages under Acute Colitis Challenge

Recruited blood monocytes contribute to the establishment, perpetuation, and resolution of tissue inflammation. Specifically, in the inflamed intestine, monocyte ablation was shown to ameliorate colitis scores in preclinical animal models. However, the majority of intestinal macrophages that seed the healthy gut are also monocyte derived. Monocyte ablation aimed to curb inflammation would therefore likely interfere with intestinal homeostasis. In this study, we used a TLR2 trans-membrane peptide that blocks TLR2 dimerization that is critical for TLR2/1 and TLR2/6 heterodimer signaling to blunt inflammation in a murine colitis model. We show that although the TLR2 peptide treatment ameliorated colitis, it allowed recruited monocytes to give rise to macrophages that lack the detrimental proinflammatory gene signature and reduced potentially damaging neutrophil infiltrates. Finally, we demonstrate TLR blocking activity of the peptide on in vitro cultured human monocyte-derived macrophages. Collectively, we provide a significantly improved anti-inflammatory TLR2 peptide and critical insights in its mechanism of action toward future potential use in the clinic.

Leukocyte Transcriptional Response in Sepsis

BACKGROUND

The complex host response to sepsis is incompletely understood. The aim of this investigation is to use leukocyte RNA sequencing to characterize biological functions, cellular pathways, and key regulatory molecules driving sepsis pathophysiology.

METHODS

This was a prospective, observational study of emergency department patients with sepsis, at an urban, academic, tertiary care center. In the derivation cohort, we collected blood at enrollment and 90 days after hospital discharge allowing each patient to serve as an internal control. We performed RNA sequencing to quantify transcriptional expression changes during sepsis and non-sepsis states. We then performed unsupervised and supervised analyses, as well as functional and pathway analyses. We selected the top down and upregulated genes and key regulatory molecules for validation. Validation occurred in a cohort of septic and non-septic using real-time PCR.

RESULTS

The derivation cohort included 5 patients, and RNA sequencing revealed 916 unique mRNA transcripts differentially expressed during sepsis. Among these, 673 (73%) genes were upregulated, and 243 (27%) were downregulated. Functional enrichment analysis revealed a highly dynamic downstream effect of the transcriptional activity during sepsis. Of the 43 functional cellular pathways activated during sepsis, the top pathways were closely associated with inflammation and response to infection. Validation occurred in 18 septic and 25 non-septic control patients, with 34/45 (76%) of identified genes validated. The regulatory analysis identified several key regulators of sepsis.

CONCLUSIONS

Highly dynamic transcriptional activity occurs in leukocytes during sepsis, activating key cellular pathways and master regulatory molecules that drive the sepsis process.

Intracerebral hemorrhage induces monocyte-related gene expression within six hours: Global transcriptional profiling in swine ICH

Intracerebral hemorrhage (ICH) is a severe neurological disorder with no proven treatment. Our prior research identified a significant association with monocyte level and ICH mortality. To advance our understanding, we sought to identify gene expression after ICH using a swine model to test the hypothesis that ICH would induce peripheral blood mononuclear cell (PBMC) gene expression. In 10 pigs with ICH, two PBMC samples were drawn from each with the first immediately prior to ICH induction and the second six hours later. RNA-seq was performed with subsequent bioinformatics analysis using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Ingenuity® Pathway Analysis (IPA). There were 182 significantly upregulated and 153 significantly down-regulated differentially expressed genes (DEGs) after ICH. Consistent with findings in humans, significant GO and KEGG pathways were primarily related to inflammation and the immune response. Five genes, all upregulated post-ICH and known to be associated with monocyte activation, were repeatedly DEGs in the significant KEGG pathways: CD14, TLR4, CXCL8, IL-18, and CXCL2. In IPA, the majority of upregulated disease/function categories were related to inflammation and immune cell activation. TNF and LPS were the most significantly activated upstream regulators, and ERK was the most highly connected node in the top network. ICH induced changes in PBMC gene expression within 6 h of onset related to inflammation, the immune response, and, more specifically, monocyte activation. Further research is needed to determine if these changes affect outcomes and may represent new therapeutic targets.

Alveolar type 2 progenitor cells for lung injury repair

Alveolar type 2 progenitor cells (AT2) seem closest to clinical translation, specifying the evidence that AT2 may satisfactorily control the immune response to decrease lung injury by stabilizing host immune-competence and a classic and crucial resource for lung regeneration and repair. AT2 establish potential in benefiting injured lungs. However, significant discrepancies linger in our understanding vis-à-vis the mechanisms for AT2 as a regime for stem cell therapy as well as essential guiding information for clinical trials, including effectiveness in appropriate pre-clinical models, safety, mostly specifications for divergent lung injury patients. These important gaps shall be systematically investigated prior to the vast therapeutic perspective of AT2 cells for pulmonary diseases can be considered. This review focused on AT2 cells homeostasis, pathophysiological changes in the pathogenesis of lung injury, physiological function of AT2 cells, apoptosis of AT2 cells in lung diseases, the role of AT2 cells in repairing processes after lung injury, mechanism of AT2 cells activation promote repairing processes after lung injury, and potential therapy of lung disease by utilizing the AT2 progenitor cells. The advancement remains to causally connect the molecular and cellular alteration of AT2 cells to lung injury and repair. Conclusively, it is identified that AT2 cells can convert into AT1 cells; but, the comprehensive cellular mechanisms involved in this transition are unrevealed. Further investigation is mandatory to determine new strategies to prevent lung injury.

How toll-like receptors reveal monocyte plasticity: the cutting edge of antiinflammatory therapy

Toll-like receptors (TLR)s are central in immune response by recognizing pathogen-associated molecular patterns (PAMP)s. If they are essential to eliminate pathogens in earlier stages of infection, they also might play a role in homeostasis and tissue repair. TLR versatility parallels the plasticity of monocytes, which represent an heterogeneous population of immune cells. They are rapidly recruited to sites of infection and involved in clearance of pathogens and in tissue healing. This review underlines how TLRs have proved to be an interesting tool to study the properties of monocytes and why different therapeutic strategies exploring monocyte plasticity may be relevant in the context of chronic inflammatory disorders.

Pediatric Intensive Care: Immunomodulation With Activated Protein C ex vivo

Objective: Sepsis is major cause of morbidity and mortality in the Pediatric Intensive Care Unit (PICU). PICU patients may develop transient immune deficiency during sepsis. Activated Protein C (APC) has significant anti-inflammatory and cytoprotective effects. Clinical trials of APC in adult sepsis initially showed improved outcome but recent trials showed no benefit in adults or children. We aimed to assess the effects of APC treatment on innate immune responses in children. Design and Subjects: We compared neutrophil and monocyte responses to lipopolysaccharide (LPS) with and without APC treatment in PICU patients at the time of evaluation for sepsis compared with healthy adults and age-matched pediatric controls. We used flow cytometry to examine cell activation (CD11b expression), function [intracellular reactive oxygen intermediate (ROI) release] and LPS recognition [Toll like Receptor 4 (TLR4) expression]. Results: PICU patients had significantly decreased protein c levels and LPS responses compared with adult and pediatric controls for all parameters. APC reduced LPS-induced neutrophil PICU TLR4 and adult ROI (p < 0.05). PICU non-survivors had increased LPS induced neutrophil and monocyte ROI production vs. survivors which was significantly reduced by APC. Conclusion: PICU patients demonstrate significantly reduced endotoxin reactivity which may predispose them to sepsis and alter effective antibacterial responses. APC reduces LPS-induced ROI production in adults and may have a role in treating severely compromised PICU patients especially given that newer APC forms are associated with decreased bleeding risk and enhanced anti-inflammatory effects.

Biomaterials for vaccine-based cancer immunotherapy

The development of therapeutic cancer vaccines as a means to generate immune reactivity against tumors has been explored since the early discovery of tumor-specific antigens by Georg Klein in the 1960s. However, challenges including weak immunogenicity, systemic toxicity, and off-target effects of cancer vaccines remain as barriers to their broad clinical translation. Advances in the design and implementation of biomaterials are now enabling enhanced efficacy and reduced toxicity of cancer vaccines by controlling the presentation and release of vaccine components to immune cells and their microenvironment. Here, we discuss the rational design and clinical status of several classes of cancer vaccines (including DNA, mRNA, peptide/protein, and cell-based vaccines) along with novel biomaterial-based delivery technologies that improve their safety and efficacy. Further, strategies for designing new platforms for personalized cancer vaccines are also considered.

Expression of Toll-like receptors 2, 4 and 6 in the equine chorioallantois

In mares, placental diseases are a common cause of pregnancy failure and they can have an economic impact on the horse breeding industry. To our knowledge no published data on TLR expression in the equine placenta exist. This study examined the expression of TLR 2, 4 and 6 as transcript and protein in the placenta (chorioallantois) of 14 foals born alive. By PCR, all examined placental samples contained TLR 2, 4 and 6 transcripts. Using immunohistochemistry, trophoblasts and allantoic epithelium were immunopositive for TLR 2, 4 and 6 in all placental samples. The majority of placental samples contained TLR 4 and 6 positive stromal cells and vascular smooth muscle cells. Since these results confirm the expression of TLR 2, 4 and 6 in different cell populations of the equine placenta, they are the basis for studies into the pathogenesis of TLR-associated placental diseases in mares.

Association between TLR2 and TLR4 Expression and Response to Induction Therapy in Acute Myeloid Leukemia Patients

Background: Toll-like receptors (TLRs) are a family of transmembrane pattern-recognition receptors that play a crucial role in the realization of innate and adaptive immune response. TLRs may play a role in tumor development and growth because of expression or up-regulation of functional TLRs in some tumors and tumor cell lines. The participation of TLRs in the pathogenesis of acute myeloid leukemia (AML) remains unspecified. This study aimed to investigate the effect of TLR2 and TLR4 expression in peripheral blood mononuclear cells of AML patients in response to induction chemotherapy. Materials and Methods: Eighty- five patients with newly diagnosed AML were evaluated. Using quantitative reverse transcriptase PCR, the mRNA expression of genes TLR2 and TLR4 was measured before starting and after induction chemotherapy. The differences in the mean expression levels of TLR2 and TLR4 before and after chemotherapy were compared using a paired t-test. The mean expression levels of TLR2 and TLR4 regarding laboratory data were analyzed by one-way ANOVA and Chi-square test. Results: We found that the mRNA expression of TLR2 after induction chemotherapy was significantly lower as compared to before treatment (p=0.001). Also, we found a lower TLR4 gene expression level after chemotherapy as compared to before chemotherapy, albeit it was not statistically significant (p=0.21). Moreover, we observed significantly higher expression of TLR2 and TLR4 in AML-M3 cases compared to non-M3 AML patients. Conclusion: The decreased expression of TLR4 in leukemic samples after induction chemotherapy might indicate a novel potential prognostic role for this receptor, particularly in AML-M3 cases.

Toll-like receptor 2, 4 and 9 polymorphisms and their association with ICU-acquired infections in Central Greece

PURPOSE

To test the potential of four common Toll-like receptor (TLR) polymorphisms to predispose to specific intensive care unit (ICU)-acquired infections and affect outcomes in a Greek ICU.

MATERIALS AND METHODS

The incidence of TLR2-Arg753Gln, TLR4-Asp299Gly, TLR4-Thr399Ile and TLR9-T1237C polymorphisms, and their association with ICU-acquired infections and patients' clinical outcomes were prospectively evaluated The examined genetic polymorphisms were assessed by real-time Polymerase-Chain-Reaction (PCR).

RESULTS

During a 15-month period, 224 patients were enrolled and genotyped. The prevalence of genetic polymorphisms for TLR4-Asp299Gly, TLR4-Thr399Ile, mixed TLR4-Asp299Gly/Thr399Ile, TLR9-T1237C and TLR2-Arg753Gln was 14.4%, 14.7%, 11.2%, 24.5% and 2.2%, respectively. TLR4 polymorphisms were associated with increased susceptibility towards specific ICU-acquired infections, i.e. Gram-negative central-nervous-system infections (CNSI), ventilator-associated pneumonia (VAP) and urinary-tract infections (UTI), principally due to multi-drug resistant (MDR) Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumonia, respectively (all P < 0.05). TLR9-T1237C polymorphism was associated with lower incidence and fewer relapses of CNSIs and UTIs when compared to mixed TLR4-Asp299Gly/Thr399Ile polymorphism group (P ≤ 0.039). ICU-stay was significantly prolonged in TLR4 polymorphisms (P ≤ 0.0416).

CONCLUSIONS

Common TLR-signaling polymorphisms might be implicated in the clinical phenotype of ICU-acquired infections in Central Greece. The possible impact of TLR4 polymorphisms on enhanced susceptibility towards Gram-negative MDR-infections in defined critical-disease states warrants further investigation. Trial Registration Clinical Trials.gov identifier: NCT00932243.

Defects in innate and adaptive immunity in patients with sepsis and health care associated infection

Recent advances in sepsis therapy exclusively involve improvements in supportive care, while sepsis mortality rates remain disturbingly high at 30%. These persistently high sepsis mortality rates arise from the absence of sepsis specific therapies. However with improvements in supportive care, patients with septic shock commonly partially recover from the infection that precipitated their initial illness, yet they frequently succumb to subsequent health care associated infections. Remarkably today the pathophysiology of sepsis in humans, a common disease in western society, remains largely a conundrum. Conventionally sepsis was regarded as primarily a disorder of inflammation. More recently the importance of immune compromise in the pathophysiology of sepsis and health care associated infection has now become more widely accepted. Accordingly a review of the human evidence for this novel sepsis paradigm is timely. Septic patients appear to exhibit a complex and long-lasting immune deficiency state, involving lymphocytes of both the innate and adaptive immune responses that have been linked with mortality and the occurrence of health care associated infection. Such is the pervasive nature of immune compromise in sepsis that ultimately immune modulation will play a crucial role in sepsis therapies of the future.

Comparison of gene expression of Toll-like receptors and cytokines between Piau and Commercial line (Landrace×Large White crossbred) pigs vaccinated against Pasteurella multocida type D

We aimed to compare Toll-like receptors (TLR) and cytokines expression in local Piau breed and a Commercial line (Landrace×Large White crossbred) pigs in response to vaccination against Pasteurella multocida type D. Seronegative gilts for Pasteurella multocida type D and Mycoplasma hyopneumoniae were used, from which peripheral blood mononuclear cells (PBMC) were collected in four time points (T0, T1, T2 and T3; before and after each vaccination dose). For bronchoalveolar lavage fluid cells (BALF), we set groups of vaccinated and unvaccinated animals for both genetic groups. Gene expression was evaluated on PBMC and BALF. In PBMC, when we analyzed time points within breeds, significant differences in expression for TLRs and cytokines, except TGFβ, were observed for Commercial animals. For the Piau pigs, only TGFβ showed differential expression. Comparing the expression among genetic groups, the Commercial pigs showed higher expression for TLRs after first vaccination dose, while for IL2, IL6, IL12 and IL13, higher expression was also observed in T3 and IL8 and IL10, in T1 and T3. Still comparing the breeds, the crossbred animals showed higher expression for TNFα in T1 and T2, while for TGFβ only in T2. For gene expression in BALF, vaccinated Commercial pigs showed higher expression of TLR6, TLR10, IL6, IL8, IL10, TNFα and TGFβ genes than vaccinated Piau pigs. The Commercial line pigs showed higher sensitivity to vaccination, while in local Piau breed lower responsiveness, which may partly explain genetic variability in immune response and will let us better understand the tolerance/susceptibility for pasteurellosis.

Cytokine storm and sepsis disease pathogenesis

Infectious diseases are a leading cause of death worldwide. Sepsis is a severe clinical syndrome related to the host response to infection. The severity of infections is due to an activation cascade that will lead to an autoamplifying cytokine production: the cytokine storm. Cytokines are a broad category of relatively small proteins (<40 kDa) that are produced and released with the aim of cell signaling. Our understanding of the processes that trigger this tremendous amount of cytokine production has made dramatic progress over the last decades, but unfortunately, these findings could not translate yet into effective treatments; so far, all clinical trials targeting cytokine production or effects failed. This review aims to summarize the pathophysiology of the cytokine storm; to describe the type, effects, and kinetics of cytokine production; and to discuss the therapeutic challenges of targeting cytokines. New promising therapeutic strategies focusing on the endothelium, as a source and a target of cytokines, are described.

TLR4 (not TLR2) dominate cognate TLR activity associated with CoCrMo implant particles

Innate immune reactions to orthopedic implant debris are the primary cause of total joint replacement (TJR) failure over the long term (15-20 years). The role of pathogen associated pattern recognition receptors (i.e., TLRs) in regulating immune reactivity to metal implant particles remains controversial. Do different TLRs (i.e., TLR2 vs. TLR4) activated by their respective ligands in concert with metal implant debris elicit equivalent innate immune responses? In this investigation, our in vitro and in vivo data indicate that Gram-negative PAMPs are more pro-inflammatory than Gram-positive PAMPs. In vitro results indicated TLR4 activation in concert with CoCrMo orthopedic implant debris (CoCrMo/LPS+) challenged primary macrophages resulted in significantly greater inflammatory responses than CoCrMo/PAM3CSK+ (TLR2). Similarly, in vivo results indicated CoCrMo/LPS+ TLR4 challenge induced a twofold increase in inflammation-induced bone resorption (osteolysis) than CoCrMo/PAM3CSK+ (p < 0.01) or CoCrMo (p < 0.03) alone in an established murine calvaria model. This points to a more potent TLR4-based effect of CoCrMo/LPS+ on innate immune responses, that is, IL-1ß, TNF-α, and resulting osteolysis. Differential CoCrMo/LPS+ induced osteolysis compared to CoCrMo/PAM3CSK+, reveals inherent differences in TLR4 versus TLR2 activation which are relevant to (i) how different types of implant debris elicit differential reactivity, (ii) how TLR2 Gram-positive bacteria benefits from less immune activation possibly due to the down-regulation of TLR2 surface expression, that subsequently impacts Gram-positive infections in TJRs, and (iii) how using TLR4 LPS (a Gram-negative agonist) may not accurately model Gram-positive bacteria responses, alone and/or with specific types of implant particles, particularly CoCrMo alloy. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1007-1017, 2017.

Identification of potential biomarkers of sepsis using bioinformatics analysis

Sepsis is defined as the systemic inflammatory response to infection and is one of the leading causes of mortality in critically ill patients. The goal of the present study is to elucidate the molecular mechanism of sepsis. Transcription profile data (GSE12624) were downloaded that had a total of 70 samples (36 sepsis samples and 34 non-sepsis samples) from the Gene Expression Omnibus database. Protein-protein interaction network analysis was conducted in order to comprehensively understand the interactions of genes in all samples. Hierarchical clustering and analysis of covariance (ANCOVA) global test were performed to identify the differentially expressed clusters in the networks, followed by function and pathway enrichment analyses. Finally, a support vector machine (SVM) was performed to classify the clusters, and 10-fold cross-validation method was performed to evaluate the classification results. A total of 7,672 genes were obtained after preprocessing of the mRNA expression profile data. The PPI network of genes under sepsis and non-sepsis status collected 1,996/2,147 genes and 2,645/2,783 interactions. Moreover, following the ANCOVA global test (P<0.05), 24 differentially expressed clusters with 12 clusters in septic and 12 clusters in non-septic samples were identified. Finally, 207 biomarker genes, including CDC42, CSF3R, GCA, HMGB2, RHOG, SERPINB1, TYROBP SERPINA1, FCER1 G and S100P in the top six clusters, were collected using the SVM method. The SERPINA1, FCER1 G and S100P genes are thought to be potential biomarkers. Furthermore, Gene oncology terms, including the intracellular signaling cascade, regulation of programmed cell death, regulation of cell death, regulation of apoptosis and leukocyte activation may participate in sepsis.

Inflammasome and toll-like receptor signaling in human monocytes after successful cardiopulmonary resuscitation

BACKGROUND

Whole body ischemia-reperfusion injury (IRI) after cardiopulmonary resuscitation (CPR) induces a generalized inflammatory response which contributes to the development of post-cardiac arrest syndrome (PCAS). Recently, pattern recognition receptors (PRRs), such as toll-like receptors (TLRs) and inflammasomes, have been shown to mediate the inflammatory response in IRI. In this study we investigated monocyte PRR signaling and function in PCAS.

METHODS

Blood samples were drawn in the first 12 hours, and at 24 and 48 hours following return of spontaneous circulation in 51 survivors after cardiac arrest. Monocyte mRNA levels of TLR2, TLR4, interleukin-1 receptor-associated kinase (IRAK)3, IRAK4, NLR family pyrin domain containing (NLRP)1, NLRP3, AIM2, PYCARD, CASP1, and IL1B were determined by real-time quantitative PCR. Ex vivo cytokine production in response to stimulation with TLR ligands Pam3CSK4 and lipopolysaccharide (LPS) was assessed in both whole blood and monocyte culture assays. Ex vivo cytokine production of peripheral blood mononuclear cells (PBMCs) from a healthy volunteer in response to stimulation with patients' sera with or without LPS was assessed. The results were compared to 19 hemodynamically stable patients with coronary artery disease.

RESULTS

Monocyte TLR2, TLR4, IRAK3, IRAK4, NLRP3, PYCARD and IL1B were initially upregulated in patients following cardiac arrest. The NLRP1 and AIM2 inflammasomes were downregulated in resuscitated patients. There was a significant positive correlation between TLR2, TLR4, IRAK3 and IRAK4 expression and the degree of ischemia as assessed by serum lactate levels and the time until return of spontaneous circulation. Nonsurvivors at 30 days had significantly lower mRNA levels of TLR2, IRAK3, IRAK4, NLRP3 and CASP1 in the late phase following cardiac arrest. We observed reduced proinflammatory cytokine release in response to both TLR2 and TLR4 activation in whole blood and monocyte culture assays in patients after CPR. Sera from resuscitated patients attenuated the inflammatory response in cultured PBMCs after co-stimulation with LPS.

CONCLUSIONS

Successful resuscitation from cardiac arrest results in changes in monocyte pattern recognition receptor signaling pathways, which may contribute to the post-cardiac arrest syndrome.

TRIAL REGISTRATION

The trial was registered in the German Clinical Trials Register ( DRKS00009684 ) on 27/11/2015.

Innate immunity gene expression changes in critically ill patients with sepsis and disease-related malnutrition

The aim of this study was an attempt to determine whether the expression of genes involved in innate antibacterial response (TL R2, NOD 1, TRAF6, HMGB 1 and Hsp70) in peripheral blood leukocytes in critically ill patients, may undergo significant changes depending on the severity of the infection and the degree of malnutrition. The study was performed in a group of 128 patients with infections treated in the intensive care and surgical ward. In 103/80.5% of patients, infections had a severe course (sepsis, severe sepsis, septic shock, mechanical ventilation of the lungs). Clinical monitoring included diagnosis of severe infection (according to the criteria of the ACC P/SCC M), assessment of severity of the patient condition and risk of death (APACHE II and SAPS II), nutritional assessment (NRS 2002 and SGA scales) and the observation of the early results of treatment. Gene expression at the mRNA level was analyzed by real-time PCR. The results of the present study indicate that in critically ill patients treated in the IC U there are significant disturbances in the expression of genes associated with innate antimicrobial immunity, which may have a significant impact on the clinical outcome. The expression of these genes varies depending on the severity of the patient condition, severity of infection and nutritional status. Expression disorders of genes belonging to innate antimicrobial immunity should be diagnosed as early as possible, monitored during the treatment and taken into account during early therapeutic treatment (including early nutrition to support the functions of immune cells).

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.

Overexpression of toll-like receptor 2 in glomerular endothelial cells and podocytes in septic acute kidney injury mouse model

Acute kidney injury (AKI) is one of the most common complications in patients with severe sepsis. The development of septic AKI increases patients' mobility and even mortality. Toll-like receptor 2 (TLR2), as a membrane surface receptor for bacterial, fungal, viral and certain endogenous substances, has been described to contribute to the development of septic AKI; however, the renal cell types associating TLR2 overactivation in septic AKI has not been described. In the current study, we investigated the TLR2 activation patterns in the kidney of lipopolysaccharide-induced septic AKI mice. Our results demonstrated that mRNA level of TLR2 significantly increased in the kidney of lipopolysaccharide-treated mice. Immunohistochemistry revealed the overactivation of TLR2 in the glomeruli. Double immunofluorescence analysis shows the precise distribution of TLR2 by showing the colocalization of TLR2 in glomeruli with synaptopodin, a podocyte marker, and Tie2, an endothelial marker. In addition, proapoptotic molecules Bax and Caspase-3 were increased in the glomeruli of lipopolysaccharide-treated mice. Together, the current study indicates that TLR2 is overactivated in the glomerular endothelial cells and podocytes in septic AKI mice, while the abundance of Bax and Caspase-3 were increased in the glomeruli of these mice, it may supply a clue that TLR2 induced these cell apoptosis in AKI. This finding provides an alternative mechanism to understand AKI development and potential targets for treatment.

The immune response to surgery and infection

Surgical trauma affects both the innate and acquired immunity. The severity of immune disorders is proportional to the extent of surgical trauma and depends on a number of factors, including primarily the basic disease requiring surgical treatment (e.g. cancer), often coexisting infections and impaired nutritional status. Disorder of the immune response following surgical trauma may predispose to septic complications burdened with the highest mortality rate. Extensive surgery in cancer patients is associated with simultaneous activation of pro- and anti-inflammatory processes defined as SIRS (systemic inflammatory immune response) and CARS (compensatory anti-inflammatory immune response). However, it is generally believed that major surgical trauma is accompanied by sustained postoperative immunosuppression, which is particularly important in patients operated on for cancer, since the suppression of the immune system promotes not only septic complications, but also proliferation and tumor metastasis. This paper reviews the main features of immune response to surgical trauma and possibilities of its regulation.

Gene expression disorders of innate antibacterial signaling pathway in pancreatic cancer patients: implications for leukocyte dysfunction and tumor progression

The study was carried out to investigate changes in gene expression of innate antibacterial signaling pathways in patients with pancreatic cancer. Expression of the following genes was measured in peripheral blood leukocytes of 55 patients with pancreatic adenocarcinoma using real-time polymerase chain reaction (RT-PCR): TLR4, NOD1, MyD88, TRAF6 and HMGB1. The levels of expression of TLR4, NOD1 and TRAF6 genes were significantly elevated (p = 0.007; p = 0.001 and p = 0.01, respectively), while MyD88 expression was markedly reduced (p = 0.0002), as compared to controls. Expression of TLR4 and NOD1 exceeded the normal level more than 3.5-fold and there was a significant correlation found between the expression of these genes (r = 0.558, p < 0.001). TLR4, NOD1 and MyD88 genes were expressed at a similar level both before and after surgery. No significant changes in the expression of HMGB1 gene were observed. The results of the study clearly indicate abnormal expression of genes belonging to innate antibacterial signaling pathways in peripheral blood leukocytes of patients with pancreatic cancer, which may lead to leukocyte dysfunction. Overexpression of TLR4, NOD1 and TRAF6 genes, and decreased MyD88 gene expression may contribute to chronic inflammation and tumor progression by up-regulation of the innate antibacterial response. The parameters tested are useful for monitoring innate immunity gene disorders and pancreatic cancer progression.

The expression of Toll-like receptors and development of severe sepsis in patients with acute myeloid leukemias after induction chemotherapy

Toll-like receptors play an important role in the host defense against microorganisms. Sepsis remains a common cause of mortality in patients with acute myeloid leukemia (AML) treated with intensive induction chemotherapy. The expression of TLRs and their association with the development of sepsis in patients with acute myeloid leukemia remains unclear. The aim of this study was to investigate the associations between expression of TLR2, TLR4 and TLR9 and occurrence of sepsis in patients treated with intensive induction chemotherapy for AML. A total of 103 patients with newly diagnosed AML were evaluated. Bone marrow samples were taken before induction therapy. Using quantitative reverse transcriptase PCR, the mRNA expression of genes TLR2, TLR4 and TLR9 was measured. Neutropenic fever occurred in 98 patients. We identified 20 episodes of severe sepsis (20%). In patients with neutropenic fever, the mRNA expression of TLR2 and TLR4 was significant higher in septic patients than in patients without sepsis symptoms (ΔCt TLR2 0.93 ± 0.82 vs 0.78 ± 0.85 and ΔCt TLR4 0.38 ± 0.29 vs 0.34 ± 0.25). Moreover, we observed that expression of TLR2 and TLR4 was significantly higher in patients with AML and bacterial infection in comparison with group with separate fungal infection (ΔCt TLR2 1.15 ± 1.06 vs 0.66 ± 0.51 and ΔCt TLR4 0.45 ± 0.38 vs 0.21 ± 0.19). Our results suggest that TLRs could be an independent factor for the development of sepsis in patients with acute myeloid leukemias after intensive induction chemotherapy. This observation should be validated by larger study.

Effect of transforming growth factor-β1 on monocyte Toll-like receptor 4 expression in septic rats

BACKGROUND

Sepsis is a tough problem in critical ill patients. This study aimed to investigate the dynamic changes of monocyte Toll-like receptor (TLR) 4 expression in peripheral blood of septic rats and to determine the effects of transforming growth factor (TGF)-β1 on TLR4 expression.

METHODS

Altogether 132 clean level SD rats were randomly divided into a control group (n=12), a sepsis model group (n=60), and a TGF-β1 intervention group (n=60). In the sepsis model group and TGF-β1 intervention group, the rats were subdivided into five groups (2-hour group, 6-hour group, 12-hour group, 24-hour group, and 48-hour group), with 12 rats in each group. Cecal ligation puncture (CLP) was performed in the sepsis model group and TGF-β1 intervention group to establish models of sepsis. The rats in the sepsis model group were injected with 1 mL normal saline at the caudal vein 0.5 hour after the model establishment; the rats in the TGF-β1 intervention group were injected with 20 ng/mL or 250 g TGF-β1 0.5 hour after the model establishment. Flow cytometry was used to detect the change of monocyte TLR4 in peripheral blood, and enzyme-linked immunosorbent assay (ELISA) was used to detect the change of TNF-α level in peripheral blood.

RESULTS

At 6-12 hours after CLP, the monocyte TLR4 in peripheral blood started to decrease, and reached the lowest level at 12 hours. Compared to the control group, the monocyte TLR4 expression at 6 and 12 hours was lowered significantly (P<0.05). Compared to the sepsis model group at 2, 24 and 48 hours after CLP, the monocyte TLR4 expression in the TGF-β1 intervention group decreased dramatically (P<0.05), but there were no differences between the two groups at 6 and 12 hours respectively. Compared to the control group, the concentration of NF-κ in liver tissue increased significantly 6 hours after CLP (P<0.05). After use of TGF-β1, the concentration of NF-κ was decreased significantly but still higher than that of the control group. Compared to the control group, the concentration of TNF-α in peripheral blood was increased significantly at 2-48 hours after CLP (P<0.05). After use of TGF-β1, TNF-α was further increased.

CONCLUSION

During sepsis, TGF-β1 can decrease the monocyte TLR4 expression and NF-κ in liver tissue, but facilitate the formation of proinflammatory mediator TNF-α. This finding indicates that TGF-β1 may play a role in promoting inflammatory response during sepsis, but this regulation is not via direct regulation of monocyte TLR4 in peripheral blood.

HS-23, Lonicera japonica extract, attenuates septic injury by suppressing toll-like receptor 4 signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Lonicera japonica Thunberg is a traditional herbal medicine widely used in East Asia as an anti-bacterial, anti-inflammatory, and antiviral agent. This study was designed to investigate the effects of HS-23, ethanol extract of the dried flower buds of Lonicera japonica, in experimental models of sepsis and elucidate the mechanisms of action of HS-23.

MATERIALS AND METHODS

Male ICR mice were intravenously administered HS-23 (20 and 40 mg/kg) for 0 (immediately) and 24 h after cecal ligation and puncture (CLP) for survival tests, and HS-23 (40 mg/kg) immediately after CLP for biochemical assays.

RESULTS

HS-23 improved sepsis-induced mortality, enhanced bacterial clearance, and attenuated multiple organ failure. The mechanisms of action of HS-23 included attenuation of increased toll-like receptor (TLR)4 protein and mRNA expression. HS-23 suppressed sepsis-induced increases in protein expression of myeloid differentiation primary response protein 88, p38 and c-Jun N-terminal kinase in both liver and lung, as well as TIR-domain-containing adapter-inducing interferon-β and interferon regulatory transcription factor 3 protein expression in liver.

CONCLUSION

The results of this study revealed that HS-23 attenuated sepsis through suppression of TLR signaling pathways. Therefore, our findings suggest that HS-23 might be useful as a potential therapeutic agent for treatment of sepsis.

Toll-like receptor signaling in neonatal sepsis and inflammation: a matter of orchestration and conditioning

Altered neonatal Toll-like receptor (TLR) function is hypothesized to contribute to the heightened susceptibility to infection and perpetuated inflammation in term and preterm neonates, clinically evident in neonatal sepsis and increased rates of inflammatory disorders. Current data indicate that basal TLR expression in term neonates equals adult expression patterns, while expression in preterm infants seems to increase, depending on gestational age. Regarding TLR signaling, some studies suggest TLR incompetence in neonates associated with impaired pro-inflammatory responses, others describe neonatal TLR function well developed and allude to its hyper-inflammation tendency. We discuss the competing positions and considerable limitations of research approaches and conclude that neonatal innate immunity is not generally less able to respond to TLR stimulation. Moreover, we describe pre-conditioning factors other than immaturity having a comparable impact. In the long term, better understanding of the complex interplay of pre- and postnatal conditions and maturation-dependent neonatal TLR function may provide new therapeutic approaches.

Lactobacillus rhamnosus GG and Bifidobacterium longum attenuate lung injury and inflammatory response in experimental sepsis

Introduction

Probiotic use to prevent nosocomial gastrointestinal and potentially respiratory tract infections in critical care has shown great promise in recent clinical trials of adult and pediatric patients. Despite well-documented benefits of probiotic use in intestinal disorders, the potential for probiotic treatment to reduce lung injury following infection and shock has not been well explored.

Objective

Evaluate if Lactobacillus rhamnosus GG (LGG) or Bifidobacterium longum (BL) treatment in a weanling mouse model of cecal ligation and puncture (CLP) peritonitis will protect against lung injury.

Methods

3 week-old FVB/N mice were orally gavaged with 200 µl of either LGG, BL or sterile water (vehicle) immediately prior to CLP. Mice were euthanized at 24 h. Lung injury was evaluated via histology and lung neutrophil infiltration was evaluated by myeloperoxidase (MPO) staining. mRNA levels of IL-6, TNF-α, MyD88, TLR-4, TLR-2, NFΚB (p50/p105) and Cox-2 in the lung analyzed via real-time PCR. TNF-α and IL-6 in lung was analyzed via ELISA.

Results

LGG and BL treatment significantly improved lung injury following experimental infection and sepsis and lung neutrophil infiltration was significantly lower than in untreated septic mice. Lung mRNA and protein levels of IL-6 and TNF-α and gene expression of Cox-2 were also significantly reduced in mice receiving LGG or BL treatment. Gene expression of TLR-2, MyD88 and NFΚB (p50/p105) was significantly increased in septic mice compared to shams and decreased in the lung of mice receiving LGG or BL while TLR-4 levels remained unchanged.

Conclusions

Treatment with LGG and BL can reduce lung injury following experimental infection and sepsis and is associated with reduced lung inflammatory cell infiltrate and decreased markers of lung inflammatory response. Probiotic therapy may be a promising intervention to improve clinical lung injury following systemic infection and sepsis.

Stimulation of the α7 nicotinic acetylcholine receptor protects against sepsis by inhibiting Toll-like receptor via phosphoinositide 3-kinase activation

BACKGROUND

The Toll-like receptor (TLR) plays an important role in the induction of the hyperinflammatory response and tissue injury in sepsis. The cholinergic antiinflammatory pathway serves as a link between the parasympathetic and innate immune systems. We examined the antiinflammatory effect of nicotine, a potent α7 nicotinic acetylcholine receptor (α7nAChR) agonist, with regard to TLR expression and signaling during sepsis.

METHODS

Polymicrobial sepsis was induced in mice by cecal ligation and puncture (CLP). The subjects received intraperitoneal nicotine (400 μg/kg) immediately after CLP for the biochemical study and 0, 24, 48, and 72 hours after CLP for the survival test. Intraperitoneal methyllycaconitine (MLA; 5 mg/kg), an α7nAChR antagonist, was administered 5 minutes prior to nicotine treatment. We evaluated the effects of nicotine using α7nAChR and phosphoinositide 3-kinase (PI3K) inhibitors in lipopolysaccharide-stimulated RAW264.7 cells.

RESULTS

Nicotine improved sepsis-induced mortality, attenuated organ failure, and suppressed inflammatory cytokines, which were abolished by MLA. Nicotine enhanced PI3K/Akt activation and reduced PU.1 activity and TLR4 expression. MLA and PI3K inhibitors blocked this effect of nicotine.

CONCLUSIONS

Our findings suggest that stimulation of the cholinergic antiinflammatory pathway by nicotine protects against septic injury and that this may be associated with inhibition of TLR4 expression via α7nAChR/PI3K signaling.

The contribution of group A streptococcal virulence determinants to the pathogenesis of sepsis

Streptococcus pyogenes (group A streptococcus, GAS) is responsible for a wide range of pathologies ranging from mild pharyngitis and impetigo to severe invasive soft tissue infections. Despite the continuing susceptibility of the bacterium to β-lactam antibiotics there has been an unexplained resurgence in the prevalence of invasive GAS infection over the past 30 years. Of particular importance was the emergence of a GAS-associated sepsis syndrome that is analogous to the systemic toxicosis associated with TSST-1 producing strains of Staphylococcus aureus. Despite being recognized for over 20 years, the etiology of GAS associated sepsis and the streptococcal toxic shock syndrome remains poorly understood. Here we review the virulence factors that contribute to the etiology of GAS associated sepsis with a particular focus on coagulation system interactions and the role of the superantigens in the development of streptococcal toxic shock syndrome.

Regulatory multitasking of tolerogenic dendritic cells - lessons taken from vitamin d3-treated tolerogenic dendritic cells

Tolerogenic dendritic cells (DCs) work through silencing of differentiated antigen-specific T cells, activation and expansion of naturally occurring T regulatory cells (Tregs), transfer of regulatory properties to T cells, and the differentiation of naïve T cells into Tregs. Due to an operational definition based on T cell activation assays, the identity of tolerogenic DCs has been a matter of debate and it need not represent a specialized DC subset. Human tolerogenic DCs generated in vitro using inhibitory cytokines, growth factors, natural immunomodulators, or genetic manipulation have been effective and several of these tolerogenic DCs are currently being tested for clinical use. Ex vivo generated tolerogenic DCs reduce activation of naïve T cells using various means, promote a variety of regulatory T cells and most importantly, frequently show stable inhibitory phenotypes upon repetitive maturation with inflammatory factors. Yet, tolerogenic DCs differ with respect to the phenotype or the number of regulatory mechanisms they employ to modulate the immune system. In our experience, tolerogenic DCs generated using the biologically active form of vitamin D (VD3-DCs), alone, or combined with dexamethasone are proficient in their immunoregulatory functions. These tolerogenic DCs show a stable maturation-resistant semi-mature phenotype with low expression of activating co-stimulatory molecules, no production of the IL-12 family of cytokines and high expression of inhibitory molecules and IL-10. VD3-DCs induce increased apoptosis of effector T cells and induce antigen-specific regulatory T cells, which work through linked suppression ensuring infectious tolerance. Lessons learned on VD3-DCs help understanding the contribution of different pattern-recognition receptors (PRRs) and secondary signals to the tolerogenic function and how a cross-talk between DCs and T cells translates into immune regulation.

Low dose LPS does not increase TLR4 expression on monocytes in a human in vivo model

BACKGROUND AND PURPOSE

Toll like receptor 4 (TLR4) is the major recognition receptor for lipopolysaccharides and plays a major role in the inflammatory response. CD11b is expressed on the surface of many leukocytes including monocytes. The CD11b/CD18 complex is involved in the inflammatory response by mediating migration and adhesion of leukocytes. The aim of this human in vivo study was to investigate the expression of TLR4 and CD11b on the surface of human monocytes after in vivo low-dose LPS stimulation.

METHODS

We performed a double-blind, randomized crossover study with 16 healthy males who received a bolus injection of bacterial lipopolysaccharide (LPS; 0.4ng/kg) or normal saline. Vital parameters, blood counts, serum cytokine levels, the expression of TLR4, and CD11b on CD14 positive cells were analyzed.

RESULTS

The experimentally induced inflammatory response was reflected by transient increases in body temperature, circulating leukocyte numbers, and plasma levels of pro- (TNF-α, IL-6) and anti-inflammatory cytokines (IL-10, IL-1ra). In contrast to a significant increase in CD11b expression, no changes in TLR4 expression on circulating monocytes were detectable.

CONCLUSION

Early changes in TLR4 expression on circulating monocytes are not necessarily part of the inflammatory response to low dose LPS in humans whereas the detected increase of CD11b expression might already be sufficient for optimized recognition and signalling.

Development of monocyte Toll-like receptor 2 and Toll-like receptor 4 in preterm newborns during the first few months of life

BACKGROUND

Although the immaturity of Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) at birth in preterm newborns is known, their development during the first few months of life remains unclear.

METHODS

Blood monocytes of preterm newborns (gestational age: 24-36 wk) were obtained every 2 wk when possible in order to perform serial measurements of TLR2 and TLR4 surface expression, as well as lipopolysaccharide (LPS)-induced cytokine production. Measurements using monocytes from term newborns and adults were also performed.

RESULTS

The monocytes of preterm newborns obtained at birth displayed reduced surface expression of TLR2 and TLR4, and diminished responses of tumor necrosis factor-α (TNF-α) and interleukin (IL)-8 to LPS stimulation. Regardless of gestational age, monocyte expression of TLR2 and TLR4 in preterm newborns increased rapidly within the first 2 wk after birth, quickly reaching those of term newborns. These increases continued for the following 4-6 wk, although the increase began to plateau. By contrast, LPS-induced production of TNF-α and IL-8 did not elevate over this period in preterm newborns.

CONCLUSION

The blood monocytes of preterm newborns display rapid increase in TLR2 and TLR4 expression during the first few months of life, whereas LPS-induced cytokine production functionality did not improve in parallel.

Surface expression and genotypes of Toll-like receptors 2 and 4 in patients with juvenile idiopathic arthritis and systemic lupus erythematosus

BACKGROUND

Chronic arthritis is a common feature of juvenile idiopathic arthritis (JIA) and systemic lupus erythematosus (SLE). It was subsequently discovered that Toll-like receptors (TLRs) are able to upregulate cytokine production in response to endogenous ligands released after tissue damage, suggesting that TLRs can maintain an inflammatory response even in absence of pathogen. Thus, TLRs may contribute to increased inflammation in JIA and SLE patients. The aim of this study was to investigate the role of TLRs in JIA and SLE. We examined the in vivo expression and polymorphisms of TLR2 and TLR4 in peripheral monocytes of patients with JIA and SLE during active and inactive disease phases.

METHODS

This single center cohort study consisted of JIA and SLE affected children and control subjects. TLR2 and TLR4 protein expression on CD14+ monocytes was examined by flow cytometry. TLR2 and TLR4 genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism method (RFLP-PCR).

RESULTS

A significant reduction in the level of TLR4 expression (p ≤ 0.001) was observed on monocytes of patients with JIA and SLE compared with that of healthy control subjects. There was no correlation between the TLR2 or TLR4 genotypes and the observed differential TLR protein expression on monocytes.

CONCLUSIONS

To conclude, our observations suggest involvement of investigated TLRs in the pathogenesis of JIA and SLE. It still remains to be elucidated whether reduced TLR4 expression is cause of chronic arthritis or a result of some feedback loop.

CHOP deficiency results in elevated lipopolysaccharide-induced inflammation and kidney injury

C/EBP homologous protein (CHOP) is an important mediator of endoplasmic reticulum (ER) stress-induced cell and organ injury. Here we show that lipopolysaccharide (LPS)-induced acute kidney injury (AKI) is associated with ER stress and elevated CHOP. We postulated that CHOP(-/-) mice would be protected against LPS-induced-AKI. Unexpectedly, while Toll-like receptor 4 (TLR4) expression levels were comparable in kidneys of CHOP(-/-) and wild-type (WT) mice, CHOP(-/-) mice developed more severe AKI after LPS injection. Furthermore, the severe kidney injury in CHOP(-/-) mice was associated with an exaggerated inflammatory response. Serum TNF-α levels were more elevated in LPS-treated CHOP(-/-) mice. There was a 3.5-fold higher amount of renal neutrophil infiltrates in LPS-treated CHOP(-/-) than in WT mice. Additionally, the kidneys of LPS-treated CHOP(-/-) mice had a more prominent increase in NF-κB activation and further upregulation of proinflammatory genes, i.e., c-x-c motif ligand 1 (CXCL-1), macrophage inflammatory protein-2 (MIP-2), and IL-6. Finally, proximal tubules, glomeruli, and podocytes isolated from CHOP(-/-) mice also had an exaggerated proinflammatory response to LPS. Since LPS directly increased CHOP in glomeruli and podocytes of WT mice, together these data suggest that the LPS-induced increase of CHOP in kidneys may inhibit inflammatory response in renal cells and provide protection against AKI.

Creating a "pro-survival" phenotype through epigenetic modulation

BACKGROUND

We demonstrated recently that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improved survival in a rodent model of lipopolysaccharide (LPS)-induced endotoxic shock. The precise mechanisms, however, have not been well-defined. The aim of this study was to investigate the impact of SAHA treatment on gene expression profiles at an early stage of shock.

METHODS

Male C57BL/6J mice were treated with or without SAHA (50 mg/kg, IP), followed by a lethal dose of LPS (20 mg/kg, IP) and a second dose of SAHA. Lungs of the animals (LPS and SAHA+LPS groups; n = 3 per group) were harvested 3 hours post-LPS insult. Sham mice (no LPS and no SAHA) served as controls. RNA was isolated from the tissues and gene expression was analyzed using Affymatrix microarray (23,000 genes). A lower confidence bound of fold change was determined for comparison of LPS versus SAHA + LPS, and genes with a lower confidence bound of >2 were considered to be differentially expressed. Reverse transcriptase polymerase chain reaction, Western blotting, and tissue staining were performed to verify the key changes. Network graphs were used to determine gene interaction and biologic relevance.

RESULTS

The expression of many genes known to be involved in septic pathophysiology changed after the LPS insult. Interestingly, a number of genes not implicated previously in the septic response were also altered. SAHA treatment attenuated expression of several key genes involved in inflammation. It also decreased neutrophil infiltration in lungs and histologic evidence of acute lung injury. Further analysis confirmed genes engaged in the cellular and humoral arms of the innate immune system were specifically inhibited by SAHA. Gene network analysis identified numerous molecules for the potential development of targeted therapies.

CONCLUSION

Administration of SAHA in a rodent model of LPS shock rapidly modulates gene transcription, with an attenuation of inflammatory mediators derived from both arms (cellular and humoral) of the innate immune system. This may be a novel mechanism responsible for the survival advantage seen with SAHA treatment.