Erythrocyte and blood antibacterial defense

Differences in cell-associated and cell-free microbial DNA in blood

In the absence of infection, blood has previously been understood to be free of microbes. However, with advances in sequencing technology this notion has been challenged, prompting new investigations into microbial DNA within the blood of both healthy and diseased individuals. To comprehensively survey microbial DNA in blood, we separated blood into fractions (plasma, red blood cells, and buffy coat) and assessed if the microbial-DNA is cell-free by the addition of DNase to a subset of each fraction. We measured 16S rRNA gene copy number with digital droplet PCR and identified the taxonomic origin of the microbial DNA with synthetic full-length 16S rRNA gene sequencing. As a use case, we examine microbial DNA from the blood of 5 men without prostate cancer (PC), 5 men with low-grade PC, and 5 men with high-grade PC. Our study demonstrates that the majority of microbial DNA is cell-free, indicating that it is not representative of proliferating microbes. Our analyses also revealed buffy coat had the lowest number of 16S rRNA gene copies yet highest number of genera of the fractions (median 23.3 copies/μL and 10 genera) and thus may be a useful fraction to study moving forward. Additionally, microbial DNA in blood may have utility as a biomarker, as we detected disease-associated compositional differences in the plasma and buffy coat fractions. This study lays the groundwork for rigorously studying microbial DNA in blood, however larger studies are needed to confirm our disease-association findings.

Investigating the time to blood culture positivity: why does it take so long?

Introduction. Bloodstream infections (BSIs) are one of the most serious infections investigated by microbiologists. However, the time to detect a BSI fails to meet the rapidity required to inform clinical decisions in real time.Gap Statement. Blood culture (BC) is considered the gold standard for diagnosing bloodstream infections. However, the time to blood culture positivity can be lengthy. Underpinning this is the reliance on bacteria replicating to a high concentration, which is necessary for the detection using routine blood culture systems. To improve the diagnosis and management of patients with BSIs, more sensitive detection methods are required.Aim. The study aimed to answer key questions addressing the delay in BSI detection and whether the time to BSI detection could be expedited using a Scattered Light Integrated Collection (SLIC) device.Methodology. A proof-of-concept study was conducted to compare the time to positivity (TTP) of Gram-negative BCs flagging positive on BacT/ALERT with an SLIC device. An SLIC device was utilized to compare the TTP of the most prevalent BSI pathogens derived from nutrient broth and BC, the influence of bacterial load on TTP and the TTP directly from whole blood. Additionally, the overall turnaround time (TAT) of SLIC was compared with that of a standard hospital workflow.Results. Most pathogens tested took significantly longer to replicate when derived from BC than from nutrient medium. The median TTP of Gram-negative BC on BacT/ALERT was 13.56 h with a median bacterial load of 6.4×109 c.f.u. ml-1. All pathogens (7/7) derived from BC at a concentration of 105 c.f.u. ml-1 were detectable in under 70 min on SLIC. Decreasing Escherichia coli BC concentration from 105 to 102 c.f.u. ml-1 increased the TTP of SLIC from 15 to 85 min. Direct BSI detection from whole blood on SLIC demonstrated a 76% reduction in TAT when compared with the standard hospital workflow.Conclusion. An SLIC device significantly reduced the TTP of common BSI pathogens. The application of this technology could have a major impact on the detection and management of BSI.

Red Blood Cell-Related Parameters in Rheumatoid Arthritis: Clinical Value and Immunological Significance

Rheumatoid arthritis (RA) is characterized by chronic inflammation and autoimmunity. Moreover, the disease activity, co-morbidities, and prognosis of RA are closely associated with changes in red blood cell (RBC)-related parameters. The role of these parameters in RA has therefore been extensively studied. Accordingly, this article summarizes and analyzes the close relationship of RBC-related parameters such as RBC count, hemoglobin, and RBC distribution width with disease activity, co-morbidities, and prognosis in RA by reviewing the available literature. In addition, given the immunomodulatory functions of RBCs, their surface proteins, contents, and microparticles are involved in the immunomodulatory process during RA. Overall, this review aims to assess the important clinical value and immunological significance of RBCs and their related parameters in the monitoring and management of RA, thus providing a reference for the clinical diagnosis and treatment of RA and the direction for the research on RBC-related immunity.

The effect of thyme essential oil and endothelial progenitor stem cells on lipopolysaccharide-induced sepsis in C57BL/6 mice

Sepsis is a potentially fatal syndrome related to severe systemic inflammation developed by infection. Despite different antimicrobial therapies, morbidity and mortality rates remain high. Herbs along with cell therapy have been introduced as a promising option to improve the symptoms of sepsis. The present study aimed to evaluate the therapeutic effect of simultaneous administration of thyme essential oil (TEO) and endothelial progenitor stem cells (EPCs) on lipopolysaccharide (LPS)-induced sepsis in C57BL/6 mice. Sepsis was induced in C57Bl/6J mice by intraperitoneal injection of LPS, followed 2 h later by an intravenous injection of EPCs or oral administration of TEO or simultaneous administration of TEO and EPCs. After 10 days, the complete blood cell, renal and liver factors, serum levels of inflammatory cytokines, and angiogenic factors were measured. Simultaneous treatment with EPCs and TEO significantly increased the survival of mice with sepsis and modulated the inflammatory response by reducing the serum levels of pro-inflammatory cytokines. Moreover, this treatment significantly reduced the level of white blood cells and neutrophils and increased the number of red blood cells, the percentage of hematocrit, and hemoglobin. The combination of TEO with EPCs decreased organ injuries and was assessed by lower levels of the liver enzymes alanine aminotransferase and aspartate aminotransferase compared to the sepsis group. Administration of EPCs and TEO also significantly improved angiogenic factors, lung function, and toll-like receptor 4 expression. EPCs in combination with TEO increase survival in the LPS-induced sepsis mice model by acting on several targets. Thus, the combination of TEO with EPCs can be a feasible approach for the future clinical treatment and control of sepsis.

The oral-gut-circulatory axis: from homeostasis to colon cancer

The human microbiota is widely recognized as providing crucial health benefits to its host, specifically by modulating immune homeostasis. Microbial imbalance, known as dysbiosis, is linked to several conditions in the body. The oral cavity and gut host the two largest microbial communities playing a major role in microbial-associated diseases. While the oral-gut axis has been previously explored, our review uniquely highlights the significance of incorporating the circulatory system into this axis. The interaction between immune cells, inflammatory factors, circulating bacteria, and microbial metabolites influences the homeostasis of both the oral and gut microbiota in a bidirectional manner. In this comprehensive review, we aim to describe the bacterial components of the oral-gut-circulatory axis in both health and disease, with a specific focus on colon cancer.

Oral microbiome mediated inflammation, a potential inductor of vascular diseases: a comprehensive review

The dysbiosis of the oral microbiome and vascular translocation of the periodontopathic microorganism to peripheral blood can cause local and systemic extra-oral inflammation. Microorganisms associated with the subgingival biofilm are readily translocated to the peripheral circulation, generating bacteremia and endotoxemia, increasing the inflammation in the vascular endothelium and resulting in endothelial dysfunction. This review aimed to demonstrate how the dysbiosis of the oral microbiome and the translocation of oral pathogen-induced inflammation to peripheral blood may be linked to cardiovascular diseases (CVDs). The dysbiosis of the oral microbiome can regulate blood pressure and activate endothelial dysfunction. Similarly, the passage of periodontal microorganisms into the peripheral circulation and their virulence factors have been associated with a vascular compartment with a great capacity to activate endothelial cells, monocytes, macrophages, and plaquettes and increase interleukin and chemokine secretion, as well as oxidative stress. This inflammatory process is related to atherosclerosis, hypertension, thrombosis, and stroke. Therefore, oral diseases could be involved in CVDs via inflammation. The preclinic and clinical evidence suggests that periodontal disease increases the proinflammatory markers associated with endothelial dysfunction. Likewise, the evidence from clinical studies of periodontal treatment in the long term evidenced the reduction of these markers and improved overall health in patients with CVDs.

The Antibacterial Activity of Erythrocytes From Goose (Anser domesticus) Can Be Associated With Phagocytosis and Respiratory Burst Generation

In the lumen of blood vessels, there are large numbers of erythrocytes, which are approximately 95% of the total blood cells. Although the function of erythrocytes is to transport oxygen in the organism, recent studies have shown that mammalian and teleost erythrocytes are involved in the immune response against bacterial infections. However, the immune mechanisms used by avian erythrocytes are not yet clear. Here, we demonstrated that erythrocytes from goose have the ability to phagocytose as well as conduct antimicrobial activity. Firstly, we revealed the phagocytosis or adhesion activity of goose erythrocytes for latex beads 0.1-1.0 μm in diameter by fluorescence microscopy, and scanning and transmission electron microscopy. The low cytometry results also proved that goose erythrocytes had a wide range of phagocytic or adhesion activity for different bacteria. Followed, the low cytometry analysis data further explored that the goose erythrocytes contain the ability to produce reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) in response to bacterial stimulation, and also up-regulated the expression of NOX family includes NOX1 and NOX5. Finally, we also found that goose erythrocytes showed a powerful antibacterial activity against all the three bacteria, meanwhile the stimulation of three kinds of bacteria up-regulated the expression of inflammatory factors, and increased the production of antioxidant enzymes to protect the cells from oxidative damage. Herein, our results demonstrate that goose Erythrocytes possess a certain phagocytic capacity and antioxidant system, and that the antimicrobial activity of erythrocytes can occurred through the production of unique respiratory burst against foreign pathogenic bacteria, which provides new clues to the interaction between bacteria and avian erythrocytes.

Erythrocyte degradation, metabolism, secretion, and communication with immune cells in the blood during sepsis: A review

Sepsis is a health issue that affects millions of people worldwide. It was assumed that erythrocytes were affected by sepsis. However, in recent years, a number of studies have shown that erythrocytes affect sepsis as well. When a pathogen invades the human body, it infects the blood and organs, causing infection and sepsis-related symptoms. Pathogens change the internal environment, increasing the levels of reactive oxygen species, influencing erythrocyte morphology, and causing erythrocyte death, i.e., eryptosis. Characteristics of eryptosis include cell shrinkage, membrane blebbing, and surface exposure of phosphatidylserine (PS). Eryptotic erythrocytes increase immune cell proliferation, and through PS, attract macrophages that remove the infected erythrocytes. Erythrocyte-degraded hemoglobin derivatives and heme deteriorate infection; however, they could also be metabolized to a series of derivatives. The result that erythrocytes play an anti-infection role during sepsis provides new perspectives for treatment. This review focuses on erythrocytes during pathogenic infection and sepsis.

Oral-Gut-Brain Axis in Experimental Models of Periodontitis: Associating Gut Dysbiosis With Neurodegenerative Diseases

Periodontitis is considered a non-communicable chronic disease caused by a dysbiotic microbiota, which generates a low-grade systemic inflammation that chronically damages the organism. Several studies have associated periodontitis with other chronic non-communicable diseases, such as cardiovascular or neurodegenerative diseases. Besides, the oral bacteria considered a keystone pathogen, Porphyromonas gingivalis, has been detected in the hippocampus and brain cortex. Likewise, gut microbiota dysbiosis triggers a low-grade systemic inflammation, which also favors the risk for both cardiovascular and neurodegenerative diseases. Recently, the existence of an axis of Oral-Gut communication has been proposed, whose possible involvement in the development of neurodegenerative diseases has not been uncovered yet. The present review aims to compile evidence that the dysbiosis of the oral microbiota triggers changes in the gut microbiota, which creates a higher predisposition for the development of neuroinflammatory or neurodegenerative diseases.The Oral-Gut-Brain axis could be defined based on anatomical communications, where the mouth and the intestine are in constant communication. The oral-brain axis is mainly established from the trigeminal nerve and the gut-brain axis from the vagus nerve. The oral-gut communication is defined from an anatomical relation and the constant swallowing of oral bacteria. The gut-brain communication is more complex and due to bacteria-cells, immune and nervous system interactions. Thus, the gut-brain and oral-brain axis are in a bi-directional relationship. Through the qualitative analysis of the selected papers, we conclude that experimental periodontitis could produce both neurodegenerative pathologies and intestinal dysbiosis, and that periodontitis is likely to induce both conditions simultaneously. The severity of the neurodegenerative disease could depend, at least in part, on the effects of periodontitis in the gut microbiota, which could strengthen the immune response and create an injurious inflammatory and dysbiotic cycle. Thus, dementias would have their onset in dysbiotic phenomena that affect the oral cavity or the intestine. The selected studies allow us to speculate that oral-gut-brain communication exists, and bacteria probably get to the brain via trigeminal and vagus nerves.

Erythrocyte-enabled immunomodulation for vaccine delivery

Erythrocytes capture pathogens in circulation and present them to antigen-presenting cells (APCs) in the spleen. Senescent or apoptotic erythrocytes are physiologically eliminated by splenic APCs in a non-inflammatory manner as to not induce an immune reaction, while damaged erythrocytes tend to induce immune activation. The distinct characteristics of erythrocytes in their lifespan or different states inspire the design of targeting splenic APCs for vaccine delivery. Specifically, normal or damaged erythrocyte-driven immune targeting can induce antigen-specific immune activation, whereas senescent or apoptotic erythrocytes can be tailored to achieve antigen-specific immune tolerance. Recent studies have revealed the potential of erythrocyte-based vaccine delivery; however, there is still no in-depth review to describe the latest progress. This review summarizes the characteristics, different immune functions, and diverse vaccine delivery behaviors and biomedical applications of erythrocytes in different states. This review aims to contribute to the rational design and development of erythrocyte-based vaccine delivery systems for treating various infections, tumors, inflammatory diseases, and autoimmune diseases.

The Value of a Complete Blood Count (CBC) for Sepsis Diagnosis and Prognosis

Sepsis represents an important global health burden due to its high mortality and morbidity. The rapid detection of sepsis is crucial in order to prevent adverse outcomes and reduce mortality. However, the diagnosis of sepsis is still challenging and many efforts have been made to identify reliable biomarkers. Unfortunately, many investigated biomarkers have several limitations that do not support their introduction in clinical practice, such as moderate diagnostic and prognostic accuracy, long turn-around time, and high-costs. Complete blood count represents instead a precious test that provides a wealth of information on individual health status. It can guide clinicians to early-identify patients at high risk of developing sepsis and to predict adverse outcomes. It has several advantages, being cheap, easy-to-perform, and available in all wards, from the emergency department to the intensive care unit. Noteworthy, it represents a first-level test and an alteration of its parameters must always be considered within the clinical context, and the eventual suspect of sepsis must be confirmed by more specific investigations. In this review, we describe the usefulness of basic and new complete blood count parameters as diagnostic and prognostic biomarkers of sepsis.

Proteins of allogeneic hepatocytes and pharmacological preparations for the correction of immunometabolic disorders in experimental liver pathology

Introduction: The relationship of numerous metabolic shifts, disorders of hepatocytes functional activity resulting from hypoxia and toxic liver damage with the function of the immune system has not been sufficiently studied so far, nor have the most effective methods of pharmacological correction been established.

Materials and Methods: The studies were carried out on 603 mature male Wistar rats and 45 mice. Acute toxic liver damage (ATLD) was modeled by intramuscular introduction of carbon tetrachloride; acute liver ischemia (ALI) was caused by clamping the hepatoduodenal ligament for 20 minutes; chronic alcohol intoxication (CAI) was modeled by forced intragastric administration of 20% ethanol solution for 60 days. Isolation of xenogeneic (murine) and allogeneic (rat) hepatocytes from newborn mice and rats was carried out according to the method of Berry and Friend (1969); culture fluid of hepatocytes and its protein fractions were prepared according to our developed techniques. The obtained biological material was intraperitoneally introduced into the rats with ATLD, ALI, and CAI.

Results and Discussion: In all the models of the liver damage, there developed morphological and biochemical signs of the liver damage, impaired congenital and adaptive immunity, oxidative stress, increased lipid peroxidation processes.

Conclusion: The introduction of allogeneic hepatocytes, culture fluid obtained on their basis,and proteins isolated from it with MW less than 130 kDa to the recipients with toxic and ischemic liver damage more effectively corrects the pathologic changes in the liver in comparison with xenogeneic hepatocytes, their culture fluid and pharmacological preparations (combinations of Essentiale N and Hypoxenum or Heptral and Mexicor).

Oxycytosis and the role of triboelectricity and oxidation in bacteria clearing from the bloodstream

Until recently, little was known about the mechanism for killing and clearing bacteria from the bloodstream. Leukocyte phagocytosis could not be a mechanism for catching, killing and removing bacteria from the bloodstream because of many reasons. Recently accumulated data have led to the conclusion that in bacteremia, bacteria are quickly removed from the blood and erythrocytes are the main cells that capture, kill and remove bacteria. Data were also obtained that erythrocytes catch bacteria by triboelectric charge attraction and kill them by oxygen released from oxyhemoglobin. This phenomenon has been named oxycytosis by analogy with the term phagocytosis. Oxycytosis has been discussed in a number of published articles, but the specific mechanism of triboelectric charging and the mechanism of killing bacteria by oxidation, have not yet been detailed. The purpose of this review is to provide a more detailed explanation of the process of triboelectric charging and capture of bacteria by erythrocytes and destruction of bacteria by oxidation. For the first time, the review presents various variants of oxycytosis (two-stage, three-stage, multi-stage), depending on the resistance of the pathogen to oxidation. The review also discusses the biological significance of oxycytosis and its impact on the understanding of bacteremia and sepsis.

Magnetic Particles with Polymeric Shells Bearing Cholesterol Moieties Sensitize Breast Cancer Cells to Low Doses of Doxorubicin

One of the promising strategies for improvement of cancer treatment is application of a combination therapy. The aim of this study was to investigate the anticancer activity of nanoformulations containing doxorubicin and iron oxide particles covered with polymeric shells bearing cholesterol moieties. It was postulated that due to high affinity to cell membranes, particles comprising poly(cholesteryl acrylate) can sensitize cancer cells to doxorubicin chemotherapy. The performed analyses revealed that the developed systems are effective against the human breast cancer cell lines MCF-7 and MDA-MB-231 even at low doses of the active compound applied (0.5 µM). Additionally, high compatibility and lack of toxicity of the tested materials against human red blood cells, immune (monocytic THP-1) cells, and cardiomyocyte H9C2(2-1) cells was demonstrated. Synergistic effects observed upon administration of doxorubicin with polymer–iron oxide hybrids comprising poly(cholesteryl acrylate) may provide an opportunity to limit toxicity of the drug and to improve its therapeutic efficiency at the same time.

Escherichia coli induced ferroptosis in red blood cells of grass carp (Ctenopharyngodon idella)

The red blood cells (RBCs) of fish make up around 95% of the total peripheral blood cells, and the long-held paradigm is that RBCs are mainly responsible for transporting oxygen. Previous studies have showed that the RBCs can be involved in the immune response against bacterial infection; however, this mechanism remains enigmatic. Here, we explored the structure of grass carp RBCs (GcRBCs). The results showed that the GcRBCs released a pseudopodia-like structure when grown in a 24-well plate, and the transmission electron microscopy (TEM) result showed that GcRBCs contained some organelle-like structures. To further verify the organelle-like structures might be the mitochondria and lysosome which similar to other immune cells, a fluorescent labeling assay was used to verify it. To decipher the antibacterial immunity of GcRBCs, transcriptomic profiling of grass carp RBCs after the incubation with E. coli was analyzed. The results showed that there were 4099 differently expressed genes (DEGs) of GcRBCs upon E. coli incubation, including 2041 up-regulated and 2058 down-regulated genes. In addition, to validate our transcriptomic data, we checked the expression of several cytokines, such as CCL4, CCL20, IL4, IL12 and IFN-α, and the results showed that all the selected gens were significantly up-regulated after E. coli incubation. Furthermore, E. coli incubation induced hemoglobin oxidation and increased the heme in GcRBCs, which further activated the expression of heme oxygenase 1 (HO-1), autophagy related genes 5 (ATG5), and ferritin. In contrast, E. coli incubation inhibited the expression of Ferroportin-1 (FPN1), which increased intracellular iron levels, induced Fenton reaction to release reactive oxygen species (ROS), and activated the ferroptosis signaling pathway in GcRBCs. Herein, we demonstrate that E. coli can induce teleost RBCs cell death through an iron-mediated ferroptosis pathway, which sheds new light on the interaction between bacteria and teleost RBCs.

Peripheral blood mononuclear cells (PBMC) microbiome is not affected by colon microbiota in healthy goats

Background

The knowledge about blood circulating microbiome and its functional relevance in healthy individuals remains limited. An assessment of changes in the circulating microbiome was performed by sequencing peripheral blood mononuclear cells (PBMC) bacterial DNA from goats supplemented or not in early life with rumen liquid transplantation.

Results

Most of the bacterial DNA associated to PBMC was identified predominantly as Proteobacteria (55%) followed by Firmicutes (24%), Bacteroidetes (11%) and Actinobacteria (8%). The predominant genera found in PBMC samples were Pseudomonas, Prevotella, Sphingomonas, Acinetobacter, Corynebacterium and Ruminococcus. Other genera such as Butyrivibrivio, Bifidobacterium, Dorea and Coprococcus were also present in lower proportions. Several species known as blood pathogens or others involved in gut homeostasis such as Faecalibacterium prausnitzii were also identified. However, the PBMC microbiome phylum composition differed from that in the colon of goats (P ≤ 0.001), where Firmicutes was the predominant phylum (83%). Although, rumen liquid administration in early-life altered bacterial community structure and increased Tlr5 expression (P = 0.020) in colon pointing to higher bacterial translocation, less than 8% of OTUs in colon were also observed in PBMCs.

Conclusions

Data suggest that in physiological conditions, PBMC microbiome differs from and is not affected by colon gut microbiota in small ruminants. Although, further studies with larger number of animals and covering other animal tissues are required, results point to a common circulating bacterial profile on mammals being phylum Proteobacteria, and genera Pseudomonas and Prevotella the most abundants. All suggest that PBMC microbiome in healthy ruminants could be implicated in homeostatic condition. This study expands our knowledge about PBMC microbiome contribution to health in farm animals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00091-7.

Dental Abscess to Septic Shock: A Case Report and Literature Review

Sepsis is a leading cause of death in the United States, with a mortality rate in excess of 215,000 deaths per year. It may lead to septic shock, a complex pathophysiological process with microbial and host response events that progress to multisystem derangement. There is poor documentation of the relationship between dental infection and septic shock, with only a few case reports of septic shock secondary to dentoalveolar abscess. Presented is a case of sepsis/septic shock in a 23-year-old man with signs and symptoms of pulpal necrosis, acute apical abscess, and canine space infection that rapidly progressed to an altered mental state, hyperthermia, tachycardia, hypotension, acute respiratory failure, diarrhea, renal insufficiency, lactic acidosis, leukocytosis, and hyperglycemia. Once septic shock develops, the mortality rate is nearly 50%. Early antimicrobial intervention is associated with surviving severe sepsis, making it critical for dentists to understand local factors leading to the crisis and the signs and symptoms of the sepsis-septic shock continuum.

Antibacterial activity of erythrocyte from grass carp (Ctenopharyngodon idella) is associated with phagocytosis and reactive oxygen species generation

Red blood cells (RBCs) are widely accepted as their primary function in respiration. Recent studies in mammals have revealed a vital role in immune responses of RBCs; however, little is known about immune function of teleost erythrocytes. Here we demonstrated that RBCs from grass carp (Ctenopharyngodon idella) were capable of binding and aggregating the bacteria with apparent morphological alterations. The phagocytosis by teleost RBCs (erythrophagocytosis) was visualized by confocal, scanning and transmission electron microscopy. Hb-Fe^II of hemoglobin (Hb) could quickly be auto-oxidated to Hb-Fe^III (methemoglobin/metHb) in the presence of oxygen (O₂), and release superoxide radical (O₂^-.) which could be spontaneously dismutated into H₂O₂ that could further oxidize Hb-Fe^III to transient HbFe^IV-OH (ferryl-Hb). Furthermore, bacterial extracellular proteases and pathogen-associated molecular patterns (PAMPs) binding to Hb could synergistically activate pseudoperoxidase, subsequently facilitated the generation of reactive oxygen species (ROS) which were toxic to the bacteria. Our results indicated that erythrocyte pertains anti-bacterial activity using unique ROS generation pathway via oxidation of hemoglobin and associated with its phagocytosis.

Glutaredoxin 1 from big-belly seahorse (Hippocampus abdominalis): Molecular, transcriptional, and functional evidence in teleost immune responses

Glutaredoxins (Grx) are redox enzymes conserved in viruses, eukaryotes, and prokaryotes. In this study, we characterized glutaredoxin 1 (HaGrx1) from big-belly seahorse, Hippocampus abdominalis. In-silico analysis showed that HaGrx1 contained the classical glutaredoxin 1 structure with a CSYC thioredoxin active site motif. According to multiple sequence alignment and phylogenetic reconstruction, HaGrx1 presented the highest homology to the Grx1 ortholog from Hippocampus comes. Transcriptional studies demonstrated the ubiquitous distribution of HaGrx1 transcripts in all the seahorse tissues tested. Significant modulation (p < 0.05) of HaGrx1 transcripts were observed in blood upon stimulation with pathogen-associated molecular patterns and live pathogens. The β-hydroxyethyl disulfide reduction assay confirmed the antioxidant activity of recombinant HaGrx1. Further, dehydroascorbate reduction and insulin disulfide reduction assays revealed the oxidoreductase activity of HaGrx1. HaGrx1 utilized 1,4-dithiothreitol, l-cysteine, 2-mercaptoethanol, and reduced l-glutathione as reducing agent with different dehydroascorbate reduction activity levels. Altogether, our results suggested a vital role of HaGrx1 in redox homeostasis as well as the host innate immune defense system.

Inflammation and thrombosis: roles of neutrophils, platelets and endothelial cells and their interactions in thrombus formation during sepsis

The inflammatory response and the activation of coagulation are two important responses in a host's defense against infection. These mechanisms do not work independently, but cooperate in a complex and synchronous manner. Recent research has also shed light on the critical role of thrombus formation, which prevents the dissemination of microorganisms. The cellular components of blood vessels, i.e. leukocytes, platelets, erythrocytes, and vascular endothelial cells, play significant roles in the development of thrombi in combination with activation of the coagulation system. In addition to the cellular components, alarmins such as histones and high-mobility group box 1, microparticles and secreted granule proteins are all important for clot formation. In this summary, we review the pathophysiology of sepsis-induced coagulopathy and the role of cellular components and critical factors released from damaged cells. In addition, we review important therapeutic approaches that have been developed, are under investigation and are currently available in certain countries, including antithrombin, recombinant thrombomodulin, anti-Toll-like receptor 4 therapy, anti-damage associated molecular pattern therapy, and hemoadsorption with a polymyxin B-immobilized fiber column.

Sepsis and septic shock: Pathogenesis and treatment perspectives

The majority of bacteremias do not develop to sepsis: bacteria are cleared from the bloodstream. Oxygen released from erythrocytes and humoral immunity kill bacteria in the bloodstream. Sepsis develops if bacteria are resistant to oxidation and proliferate in erythrocytes. Bacteria provoke oxygen release from erythrocytes to arterial blood. Abundant release of oxygen to the plasma triggers a cascade of events that cause: 1. oxygen delivery failure to cells; 2. oxidation of plasma components that impairs humoral regulation and inactivates immune complexes; 3. disseminated intravascular coagulation and multiple organs' failure. Bacterial reservoir inside erythrocytes provides the long-term survival of bacteria and is the cause of ineffectiveness of antibiotics and host immune reactions. Treatment perspectives that include different aspects of sepsis development are discussed.

Comprehensive description of blood microbiome from healthy donors assessed by 16S targeted metagenomic sequencing

BACKGROUND

Recent studies have revealed that the blood of healthy humans is not as sterile as previously supposed. The objective of this study was to provide a comprehensive description of the microbiome present in different fractions of the blood of healthy individuals.

STUDY DESIGN AND METHODS

The study was conducted in 30 healthy blood donors to the French national blood collection center (Établissement Français du Sang). We have set up a 16S rDNA quantitative polymerase chain reaction assay as well as a 16S targeted metagenomics sequencing pipeline specifically designed to analyze the blood microbiome, which we have used on whole blood as well as on different blood fractions (buffy coat [BC], red blood cells [RBCs], and plasma).

RESULTS

Most of the blood bacterial DNA is located in the BC (93.74%), and RBCs contain more bacterial DNA (6.23%) than the plasma (0.03%). The distribution of 16S DNA is different for each fraction and spreads over a relatively broad range among donors. At the phylum level, blood fractions contain bacterial DNA mostly from the Proteobacteria phylum (more than 80%) but also from Actinobacteria, Firmicutes, and Bacteroidetes. At deeper taxonomic levels, there are striking differences between the bacterial profiles of the different blood fractions.

CONCLUSION

We demonstrate that a diversified microbiome exists in healthy blood. This microbiome has most likely an important physiologic role and could be implicated in certain transfusion-transmitted bacterial infections. In this regard, the amount of 16S bacterial DNA or the microbiome profile could be monitored to improve the safety of the blood supply.

The dormant blood microbiome in chronic, inflammatory diseases

Blood in healthy organisms is seen as a ‘sterile’ environment: it lacks proliferating microbes. Dormant or not-immediately-culturable forms are not absent, however, as intracellular dormancy is well established. We highlight here that a great many pathogens can survive in blood and inside erythrocytes. ‘Non-culturability’, reflected by discrepancies between plate counts and total counts, is commonplace in environmental microbiology. It is overcome by improved culturing methods, and we asked how common this would be in blood. A number of recent, sequence-based and ultramicroscopic studies have uncovered an authentic blood microbiome in a number of non-communicable diseases. The chief origin of these microbes is the gut microbiome (especially when it shifts composition to a pathogenic state, known as ‘dysbiosis’). Another source is microbes translocated from the oral cavity. ‘Dysbiosis’ is also used to describe translocation of cells into blood or other tissues. To avoid ambiguity, we here use the term ‘atopobiosis’ for microbes that appear in places other than their normal location. Atopobiosis may contribute to the dynamics of a variety of inflammatory diseases. Overall, it seems that many more chronic, non-communicable, inflammatory diseases may have a microbial component than are presently considered, and may be treatable using bactericidal antibiotics or vaccines.

Atopobiosis of microbes (the term describing microbes that appear in places other than where they should be), as well as the products of their metabolism, seems to correlate with, and may contribute to, the dynamics of a variety of inflammatory diseases.